+
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2021 Hengqi Chen */
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+#include "tcpstates.h"
+
+#define MAX_ENTRIES 10240
+#define AF_INET 2
+#define AF_INET6 10
+
+const volatile bool filter_by_sport = false;
+const volatile bool filter_by_dport = false;
+const volatile short target_family = 0;
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, MAX_ENTRIES);
+ __type(key, __u16);
+ __type(value, __u16);
+} sports SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, MAX_ENTRIES);
+ __type(key, __u16);
+ __type(value, __u16);
+} dports SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, MAX_ENTRIES);
+ __type(key, struct sock *);
+ __type(value, __u64);
+} timestamps SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(__u32));
+} events SEC(".maps");
+
+SEC("tracepoint/sock/inet_sock_set_state")
+int handle_set_state(struct trace_event_raw_inet_sock_set_state *ctx)
+{
+ struct sock *sk = (struct sock *)ctx->skaddr;
+ __u16 family = ctx->family;
+ __u16 sport = ctx->sport;
+ __u16 dport = ctx->dport;
+ __u64 *tsp, delta_us, ts;
+ struct event event = {};
+
+ if (ctx->protocol != IPPROTO_TCP)
+ return 0;
+
+ if (target_family && target_family != family)
+ return 0;
+
+ if (filter_by_sport && !bpf_map_lookup_elem(&sports, &sport))
+ return 0;
+
+ if (filter_by_dport && !bpf_map_lookup_elem(&dports, &dport))
+ return 0;
+
+ tsp = bpf_map_lookup_elem(×tamps, &sk);
+ ts = bpf_ktime_get_ns();
+ if (!tsp)
+ delta_us = 0;
+ else
+ delta_us = (ts - *tsp) / 1000;
+
+ event.skaddr = (__u64)sk;
+ event.ts_us = ts / 1000;
+ event.delta_us = delta_us;
+ event.pid = bpf_get_current_pid_tgid() >> 32;
+ event.oldstate = ctx->oldstate;
+ event.newstate = ctx->newstate;
+ event.family = family;
+ event.sport = sport;
+ event.dport = dport;
+ bpf_get_current_comm(&event.task, sizeof(event.task));
+
+ if (family == AF_INET) {
+ bpf_probe_read_kernel(&event.saddr, sizeof(event.saddr), &sk->__sk_common.skc_rcv_saddr);
+ bpf_probe_read_kernel(&event.daddr, sizeof(event.daddr), &sk->__sk_common.skc_daddr);
+ } else { /* family == AF_INET6 */
+ bpf_probe_read_kernel(&event.saddr, sizeof(event.saddr), &sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
+ bpf_probe_read_kernel(&event.daddr, sizeof(event.daddr), &sk->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
+ }
+
+ bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU, &event, sizeof(event));
+
+ if (ctx->newstate == TCP_CLOSE)
+ bpf_map_delete_elem(×tamps, &sk);
+ else
+ bpf_map_update_elem(×tamps, &sk, &ts, BPF_ANY);
+
+ return 0;
+}
+
+char LICENSE[] SEC("license") = "Dual BSD/GPL";
+
tcpstates 是一个追踪当前系统上的TCP套接字的TCP状态的程序，主要通过跟踪内核跟踪点 inet_sock_set_state 来实现。统计数据通过 perf_event向用户态传输。
SEC("tracepoint/sock/inet_sock_set_state")
int handle_set_state(struct trace_event_raw_inet_sock_set_state *ctx)
@@ -253,15 +357,13 @@ static void handle_lost_events(void* ctx, int cpu, __u64 lost_cnt) {
收到事件后所调用对应的处理函数并进行输出打印。
-
-git clone https://github.com/libbpf/libbpf-bootstrap libbpf-bootstrap-cloned- 将 libbpf-bootstrap目录下的文件复制到
libbpf-bootstrap-cloned/examples/c下
-- 修改
libbpf-bootstrap-cloned/examples/c/Makefile ，在其 APPS 项后添加 tcpstates
-- 在
libbpf-bootstrap-cloned/examples/c 下运行 make tcpstates
-sudo ./tcpstates
-
-root@yutong-VirtualBox:~/libbpf-bootstrap/examples/c# ./tcpstates
+$ make
+...
+ BPF .output/tcpstates.bpf.o
+ GEN-SKEL .output/tcpstates.skel.h
+ CC .output/tcpstates.o
+ BINARY tcpstates
+$ sudo ./tcpstates
SKADDR PID COMM LADDR LPORT RADDR RPORT OLDSTATE -> NEWSTATE MS
ffff9bf61bb62bc0 164978 node 192.168.88.15 0 52.178.17.2 443 CLOSE -> SYN_SENT 0.000
ffff9bf61bb62bc0 0 swapper/0 192.168.88.15 41596 52.178.17.2 443 SYN_SENT -> ESTABLISHED 225.794
@@ -273,7 +375,6 @@ ffff9bf6d8ee88c0 229832 redis-serv 0.0.0.0 6379 0.0.0.0 0
ffff9bf6d8ee88c0 229832 redis-serv 0.0.0.0 6379 0.0.0.0 0 LISTEN -> CLOSE 1.763
ffff9bf7109d6900 88750 node 127.0.0.1 39755 127.0.0.1 50966 ESTABLISHED -> FIN_WAIT1 0.000
-对于输出的详细解释，详见 README.md
这里的代码修改自 https://github.com/iovisor/bcc/blob/master/libbpf-tools/tcpstates.bpf.c
diff --git a/14-tcpstates/libbpf-bootstrap/tcpstates.bpf.c b/14-tcpstates/libbpf-bootstrap/tcpstates.bpf.c
deleted file mode 100644
index 0f9ed24..0000000
--- a/14-tcpstates/libbpf-bootstrap/tcpstates.bpf.c
+++ /dev/null
@@ -1,102 +0,0 @@
-// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
-/* Copyright (c) 2021 Hengqi Chen */
-#include
-#include
-#include
-#include
-#include "tcpstates.h"
-
-#define MAX_ENTRIES 10240
-#define AF_INET 2
-#define AF_INET6 10
-
-const volatile bool filter_by_sport = false;
-const volatile bool filter_by_dport = false;
-const volatile short target_family = 0;
-
-struct {
- __uint(type, BPF_MAP_TYPE_HASH);
- __uint(max_entries, MAX_ENTRIES);
- __type(key, __u16);
- __type(value, __u16);
-} sports SEC(".maps");
-
-struct {
- __uint(type, BPF_MAP_TYPE_HASH);
- __uint(max_entries, MAX_ENTRIES);
- __type(key, __u16);
- __type(value, __u16);
-} dports SEC(".maps");
-
-struct {
- __uint(type, BPF_MAP_TYPE_HASH);
- __uint(max_entries, MAX_ENTRIES);
- __type(key, struct sock *);
- __type(value, __u64);
-} timestamps SEC(".maps");
-
-struct {
- __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
- __uint(key_size, sizeof(__u32));
- __uint(value_size, sizeof(__u32));
-} events SEC(".maps");
-
-SEC("tracepoint/sock/inet_sock_set_state")
-int handle_set_state(struct trace_event_raw_inet_sock_set_state *ctx)
-{
- struct sock *sk = (struct sock *)ctx->skaddr;
- __u16 family = ctx->family;
- __u16 sport = ctx->sport;
- __u16 dport = ctx->dport;
- __u64 *tsp, delta_us, ts;
- struct event event = {};
-
- if (ctx->protocol != IPPROTO_TCP)
- return 0;
-
- if (target_family && target_family != family)
- return 0;
-
- if (filter_by_sport && !bpf_map_lookup_elem(&sports, &sport))
- return 0;
-
- if (filter_by_dport && !bpf_map_lookup_elem(&dports, &dport))
- return 0;
-
- tsp = bpf_map_lookup_elem(×tamps, &sk);
- ts = bpf_ktime_get_ns();
- if (!tsp)
- delta_us = 0;
- else
- delta_us = (ts - *tsp) / 1000;
-
- event.skaddr = (__u64)sk;
- event.ts_us = ts / 1000;
- event.delta_us = delta_us;
- event.pid = bpf_get_current_pid_tgid() >> 32;
- event.oldstate = ctx->oldstate;
- event.newstate = ctx->newstate;
- event.family = family;
- event.sport = sport;
- event.dport = dport;
- bpf_get_current_comm(&event.task, sizeof(event.task));
-
- if (family == AF_INET) {
- bpf_probe_read_kernel(&event.saddr, sizeof(event.saddr), &sk->__sk_common.skc_rcv_saddr);
- bpf_probe_read_kernel(&event.daddr, sizeof(event.daddr), &sk->__sk_common.skc_daddr);
- } else { /* family == AF_INET6 */
- bpf_probe_read_kernel(&event.saddr, sizeof(event.saddr), &sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
- bpf_probe_read_kernel(&event.daddr, sizeof(event.daddr), &sk->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
- }
-
- bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU, &event, sizeof(event));
-
- if (ctx->newstate == TCP_CLOSE)
- bpf_map_delete_elem(×tamps, &sk);
- else
- bpf_map_update_elem(×tamps, &sk, &ts, BPF_ANY);
-
- return 0;
-}
-
-char LICENSE[] SEC("license") = "Dual BSD/GPL";
diff --git a/14-tcpstates/tcpstates.bpf.c b/14-tcpstates/tcpstates.bpf.c
index b479ca4..0f9ed24 100644
--- a/14-tcpstates/tcpstates.bpf.c
+++ b/14-tcpstates/tcpstates.bpf.c
@@ -4,42 +4,38 @@
#include
#include
#include
-#include "tcpstates.bpf.h"
+#include "tcpstates.h"
-#define MAX_ENTRIES 10240
-#define AF_INET 2
-#define AF_INET6 10
+#define MAX_ENTRIES 10240
+#define AF_INET 2
+#define AF_INET6 10
const volatile bool filter_by_sport = false;
const volatile bool filter_by_dport = false;
const volatile short target_family = 0;
-struct
-{
+struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, MAX_ENTRIES);
__type(key, __u16);
__type(value, __u16);
} sports SEC(".maps");
-struct
-{
+struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, MAX_ENTRIES);
__type(key, __u16);
__type(value, __u16);
} dports SEC(".maps");
-struct
-{
+struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, MAX_ENTRIES);
__type(key, struct sock *);
__type(value, __u64);
} timestamps SEC(".maps");
-struct
-{
+struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(__u32));
@@ -85,13 +81,10 @@ int handle_set_state(struct trace_event_raw_inet_sock_set_state *ctx)
event.dport = dport;
bpf_get_current_comm(&event.task, sizeof(event.task));
- if (family == AF_INET)
- {
+ if (family == AF_INET) {
bpf_probe_read_kernel(&event.saddr, sizeof(event.saddr), &sk->__sk_common.skc_rcv_saddr);
bpf_probe_read_kernel(&event.daddr, sizeof(event.daddr), &sk->__sk_common.skc_daddr);
- }
- else
- { /* family == AF_INET6 */
+ } else { /* family == AF_INET6 */
bpf_probe_read_kernel(&event.saddr, sizeof(event.saddr), &sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
bpf_probe_read_kernel(&event.daddr, sizeof(event.daddr), &sk->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
}
diff --git a/14-tcpstates/tcpstates.bpf.h b/14-tcpstates/tcpstates.bpf.h
deleted file mode 100644
index 9084301..0000000
--- a/14-tcpstates/tcpstates.bpf.h
+++ /dev/null
@@ -1,24 +0,0 @@
-// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
-/* Copyright (c) 2021 Hengqi Chen */
-#ifndef __TCPSTATES_H
-#define __TCPSTATES_H
-
-#define TASK_COMM_LEN 16
-
-struct event
-{
- unsigned __int128 saddr;
- unsigned __int128 daddr;
- __u64 skaddr;
- __u64 ts_us;
- __u64 delta_us;
- __u32 pid;
- int oldstate;
- int newstate;
- __u16 family;
- __u16 sport;
- __u16 dport;
- char task[TASK_COMM_LEN];
-};
-
-#endif /* __TCPSTATES_H */
diff --git a/14-tcpstates/libbpf-bootstrap/tcpstates.c b/14-tcpstates/tcpstates.c
similarity index 100%
rename from 14-tcpstates/libbpf-bootstrap/tcpstates.c
rename to 14-tcpstates/tcpstates.c
diff --git a/14-tcpstates/libbpf-bootstrap/tcpstates.h b/14-tcpstates/tcpstates.h
similarity index 100%
rename from 14-tcpstates/libbpf-bootstrap/tcpstates.h
rename to 14-tcpstates/tcpstates.h
diff --git a/15-tcprtt/index.html b/15-tcprtt/index.html
index 3e8d45c..709e2e8 100644
--- a/15-tcprtt/index.html
+++ b/15-tcprtt/index.html
@@ -179,10 +179,10 @@ const volatile bool targ_ms = false;
/// @sample {"interval": 1000, "type" : "log2_hist"}
struct {
- __uint(type, BPF_MAP_TYPE_HASH);
- __uint(max_entries, MAX_ENTRIES);
- __type(key, u64);
- __type(value, struct hist);
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, MAX_ENTRIES);
+ __type(key, u64);
+ __type(value, struct hist);
} hists SEC(".maps");
static struct hist zero;
@@ -190,69 +190,55 @@ static struct hist zero;
SEC("fentry/tcp_rcv_established")
int BPF_PROG(tcp_rcv, struct sock *sk)
{
- const struct inet_sock *inet = (struct inet_sock *)(sk);
- struct tcp_sock *ts;
- struct hist *histp;
- u64 key, slot;
- u32 srtt;
+ const struct inet_sock *inet = (struct inet_sock *)(sk);
+ struct tcp_sock *ts;
+ struct hist *histp;
+ u64 key, slot;
+ u32 srtt;
- if (targ_sport && targ_sport != inet->inet_sport)
- return 0;
- if (targ_dport && targ_dport != sk->__sk_common.skc_dport)
- return 0;
- if (targ_saddr && targ_saddr != inet->inet_saddr)
- return 0;
- if (targ_daddr && targ_daddr != sk->__sk_common.skc_daddr)
- return 0;
+ if (targ_sport && targ_sport != inet->inet_sport)
+ return 0;
+ if (targ_dport && targ_dport != sk->__sk_common.skc_dport)
+ return 0;
+ if (targ_saddr && targ_saddr != inet->inet_saddr)
+ return 0;
+ if (targ_daddr && targ_daddr != sk->__sk_common.skc_daddr)
+ return 0;
- if (targ_laddr_hist)
- key = inet->inet_saddr;
- else if (targ_raddr_hist)
- key = inet->sk.__sk_common.skc_daddr;
- else
- key = 0;
- histp = bpf_map_lookup_or_try_init(&hists, &key, &zero);
- if (!histp)
- return 0;
- ts = (struct tcp_sock *)(sk);
- srtt = BPF_CORE_READ(ts, srtt_us) >> 3;
- if (targ_ms)
- srtt /= 1000U;
- slot = log2l(srtt);
- if (slot >= MAX_SLOTS)
- slot = MAX_SLOTS - 1;
- __sync_fetch_and_add(&histp->slots[slot], 1);
- if (targ_show_ext) {
- __sync_fetch_and_add(&histp->latency, srtt);
- __sync_fetch_and_add(&histp->cnt, 1);
- }
- return 0;
+ if (targ_laddr_hist)
+ key = inet->inet_saddr;
+ else if (targ_raddr_hist)
+ key = inet->sk.__sk_common.skc_daddr;
+ else
+ key = 0;
+ histp = bpf_map_lookup_or_try_init(&hists, &key, &zero);
+ if (!histp)
+ return 0;
+ ts = (struct tcp_sock *)(sk);
+ srtt = BPF_CORE_READ(ts, srtt_us) >> 3;
+ if (targ_ms)
+ srtt /= 1000U;
+ slot = log2l(srtt);
+ if (slot >= MAX_SLOTS)
+ slot = MAX_SLOTS - 1;
+ __sync_fetch_and_add(&histp->slots[slot], 1);
+ if (targ_show_ext) {
+ __sync_fetch_and_add(&histp->latency, srtt);
+ __sync_fetch_and_add(&histp->cnt, 1);
+ }
+ return 0;
}
这段代码是基于eBPF的网络延迟分析工具，它通过hooking TCP协议栈中的tcp_rcv_established函数来统计TCP连接的RTT分布。下面是这段代码的主要工作原理：
--
-
首先定义了一个名为"hists"的eBPF哈希表，用于保存RTT直方图数据。
-
--
-
当tcp_rcv_established函数被调用时，它首先从传入的socket结构体中获取TCP相关信息，包括本地/远程IP地址、本地/远程端口号以及TCP状态信息等。
-
--
-
接下来，代码会检查用户指定的条件是否匹配当前TCP连接。如果匹配失败，则直接返回。
-
--
-
如果匹配成功，则从"hists"哈希表中查找与本地/远程IP地址匹配的直方图数据。如果该IP地址的直方图不存在，则创建一个新的直方图并插入哈希表中。
-
--
-
接下来，代码会从socket结构体中获取当前TCP连接的RTT(srtt)，并根据用户设置的选项来将srtt值进行处理。如果用户设置了"-ms"选项，则将srtt值除以1000。
-
--
-
接着，代码会将srtt值转换为直方图的槽位(slot)，并将该槽位的计数器+1。
-
--
-
如果用户设置了"-show-ext"选项，则还会累加直方图的总延迟(latency)和计数(cnt)。
-
+- 首先定义了一个名为"hists"的eBPF哈希表，用于保存RTT直方图数据。
+- 当tcp_rcv_established函数被调用时，它首先从传入的socket结构体中获取TCP相关信息，包括本地/远程IP地址、本地/远程端口号以及TCP状态信息等。
+- 接下来，代码会检查用户指定的条件是否匹配当前TCP连接。如果匹配失败，则直接返回。
+- 如果匹配成功，则从"hists"哈希表中查找与本地/远程IP地址匹配的直方图数据。如果该IP地址的直方图不存在，则创建一个新的直方图并插入哈希表中。
+- 接下来，代码会从socket结构体中获取当前TCP连接的RTT(srtt)，并根据用户设置的选项来将srtt值进行处理。如果用户设置了"-ms"选项，则将srtt值除以1000。
+- 接着，代码会将srtt值转换为直方图的槽位(slot)，并将该槽位的计数器+1。
+- 如果用户设置了"-show-ext"选项，则还会累加直方图的总延迟(latency)和计数(cnt)。
eunomia-bpf 是一个结合 Wasm 的开源 eBPF 动态加载运行时和开发工具链，它的目的是简化 eBPF 程序的开发、构建、分发、运行。可以参考 https://github.com/eunomia-bpf/eunomia-bpf 下载和安装 ecc 编译工具链和 ecli 运行时。我们使用 eunomia-bpf 编译运行这个例子。
diff --git a/print.html b/print.html
index 306def7..f0cb94f 100644
--- a/print.html
+++ b/print.html
@@ -2235,7 +2235,7 @@ TIME EVENT COMM PID PPID FILENAME/EXIT CODE
在互联网后端日常开发接口的时候中，不管你使用的是C、Java、PHP还是Golang，都避免不了需要调用mysql、redis等组件来获取数据，可能还需要执行一些rpc远程调用，或者再调用一些其它restful api。 在这些调用的底层，基本都是在使用TCP协议进行传输。这是因为在传输层协议中，TCP协议具备可靠的连接，错误重传，拥塞控制等优点，所以目前应用比UDP更广泛一些。但相对而言，tcp 连接也有一些缺点，例如建立连接的延时较长等。因此也会出现像 QUIC ，即 快速UDP网络连接 ( Quick UDP Internet Connections )这样的替代方案。
tcp 连接延时分析对于网络性能分析优化或者故障排查都能起到不少作用。
-tcpconnlat 这个工具跟踪执行活动TCP连接的内核函数 (例如，通过connect()系统调用），并显示本地测量的连接的延迟（时间），即从发送 SYN 到响应包的时间。
+tcpconnlat 这个工具跟踪执行活动TCP连接的内核函数（例如，通过connect()系统调用），并显示本地测量的连接的延迟（时间），即从发送 SYN 到响应包的时间。
tcp 连接的整个过程如图所示：
@@ -2350,15 +2350,13 @@ cleanup:
}
-
-git clone https://github.com/libbpf/libbpf-bootstrap libbpf-bootstrap-cloned- 将 libbpf-bootstrap目录下的文件复制到
libbpf-bootstrap-cloned/examples/c下
-- 修改
libbpf-bootstrap-cloned/examples/c/Makefile ，在其 APPS 项后添加 tcpconnlat
-- 在
libbpf-bootstrap-cloned/examples/c 下运行 make tcpconnlat
-sudo ./tcpconnlat
-
-root@yutong-VirtualBox:~/libbpf-bootstrap/examples/c# ./tcpconnlat
+$ make
+...
+ BPF .output/tcpconnlat.bpf.o
+ GEN-SKEL .output/tcpconnlat.skel.h
+ CC .output/tcpconnlat.o
+ BINARY tcpconnlat
+$ sudo ./tcpconnlat
PID COMM IP SADDR DADDR DPORT LAT(ms)
222564 wget 4 192.168.88.15 110.242.68.3 80 25.29
222684 wget 4 192.168.88.15 167.179.101.42 443 246.76
@@ -2369,139 +2367,111 @@ PID COMM IP SADDR DADDR DPORT LAT(ms)
通过上面的实验，我们可以看到，tcpconnlat 工具的实现原理是基于内核的TCP连接的跟踪，并且可以跟踪到 tcp 连接的延迟时间；除了命令行使用方式之外，还可以将其和容器、k8s 等元信息综合起来，通过 prometheus 和 grafana 等工具进行网络性能分析。
来源：https://github.com/iovisor/bcc/blob/master/libbpf-tools/tcpconnlat.bpf.c
-
-
-在互联网后端日常开发接口的时候中，不管你使用的是C、Java、PHP还是Golang，都避免不了需要调用mysql、redis等组件来获取数据，可能还需要执行一些rpc远程调用，或者再调用一些其它restful api。 在这些调用的底层，基本都是在使用TCP协议进行传输。这是因为在传输层协议中，TCP协议具备可靠的连接，错误重传，拥塞控制等优点，所以目前应用比UDP更广泛一些。但相对而言，tcp 连接也有一些缺点，例如建立连接的延时较长等。因此也会出现像 QUIC ，即 快速UDP网络连接 ( Quick UDP Internet Connections )这样的替代方案。
-tcp 连接延时分析对于网络性能分析优化或者故障排查都能起到不少作用。
-
-tcpconnlat 这个工具跟踪执行活动TCP连接的内核函数 (例如，通过connect()系统调用），并显示本地测量的连接的延迟（时间），即从发送 SYN 到响应包的时间。
-
-tcp 连接的整个过程如图所示：
-
-在这个连接过程中，我们来简单分析一下每一步的耗时：
-
-- 客户端发出SYNC包：客户端一般是通过connect系统调用来发出 SYN 的，这里牵涉到本机的系统调用和软中断的 CPU 耗时开销
-- SYN传到服务器：SYN从客户端网卡被发出，这是一次长途远距离的网络传输
-- 服务器处理SYN包：内核通过软中断来收包，然后放到半连接队列中，然后再发出SYN/ACK响应。主要是 CPU 耗时开销
-- SYC/ACK传到客户端：长途网络跋涉
-- 客户端处理 SYN/ACK：客户端内核收包并处理SYN后，经过几us的CPU处理，接着发出 ACK。同样是软中断处理开销
-- ACK传到服务器：长途网络跋涉
-- 服务端收到ACK：服务器端内核收到并处理ACK，然后把对应的连接从半连接队列中取出来，然后放到全连接队列中。一次软中断CPU开销
-- 服务器端用户进程唤醒：正在被accpet系统调用阻塞的用户进程被唤醒，然后从全连接队列中取出来已经建立好的连接。一次上下文切换的CPU开销
-
-在客户端视角，在正常情况下一次TCP连接总的耗时也就就大约是一次网络RTT的耗时。但在某些情况下，可能会导致连接时的网络传输耗时上涨、CPU处理开销增加、甚至是连接失败。这种时候在发现延时过长之后，就可以结合其他信息进行分析。
-
-在 TCP 三次握手的时候，Linux 内核会维护两个队列，分别是：
-
-- 半连接队列，也称 SYN 队列；
-- 全连接队列，也称 accepet 队列；
-
-服务端收到客户端发起的 SYN 请求后，内核会把该连接存储到半连接队列，并向客户端响应 SYN+ACK，接着客户端会返回 ACK，服务端收到第三次握手的 ACK 后，内核会把连接从半连接队列移除，然后创建新的完全的连接，并将其添加到 accept 队列，等待进程调用 accept 函数时把连接取出来。
-我们的 ebpf 代码实现在 https://github.com/yunwei37/Eunomia/blob/master/bpftools/tcpconnlat/tcpconnlat.bpf.c 中：
-它主要使用了 trace_tcp_rcv_state_process 和 kprobe/tcp_v4_connect 这样的跟踪点：
-
-SEC("kprobe/tcp_v4_connect")
-int BPF_KPROBE(tcp_v4_connect, struct sock *sk)
-{
- return trace_connect(sk);
-}
-
-SEC("kprobe/tcp_v6_connect")
-int BPF_KPROBE(tcp_v6_connect, struct sock *sk)
-{
- return trace_connect(sk);
-}
-
-SEC("kprobe/tcp_rcv_state_process")
-int BPF_KPROBE(tcp_rcv_state_process, struct sock *sk)
-{
- return handle_tcp_rcv_state_process(ctx, sk);
-}
-
-在 trace_connect 中，我们跟踪新的 tcp 连接，记录到达时间，并且把它加入 map 中：
-struct {
- __uint(type, BPF_MAP_TYPE_HASH);
- __uint(max_entries, 4096);
- __type(key, struct sock *);
- __type(value, struct piddata);
-} start SEC(".maps");
-
-static int trace_connect(struct sock *sk)
-{
- u32 tgid = bpf_get_current_pid_tgid() >> 32;
- struct piddata piddata = {};
-
- if (targ_tgid && targ_tgid != tgid)
- return 0;
-
- bpf_get_current_comm(&piddata.comm, sizeof(piddata.comm));
- piddata.ts = bpf_ktime_get_ns();
- piddata.tgid = tgid;
- bpf_map_update_elem(&start, &sk, &piddata, 0);
- return 0;
-}
-
-在 handle_tcp_rcv_state_process 中，我们跟踪接收到的 tcp 数据包，从 map 从提取出对应的 connect 事件，并且计算延迟：
-static int handle_tcp_rcv_state_process(void *ctx, struct sock *sk)
-{
- struct piddata *piddatap;
- struct event event = {};
- s64 delta;
- u64 ts;
-
- if (BPF_CORE_READ(sk, __sk_common.skc_state) != TCP_SYN_SENT)
- return 0;
-
- piddatap = bpf_map_lookup_elem(&start, &sk);
- if (!piddatap)
- return 0;
-
- ts = bpf_ktime_get_ns();
- delta = (s64)(ts - piddatap->ts);
- if (delta < 0)
- goto cleanup;
-
- event.delta_us = delta / 1000U;
- if (targ_min_us && event.delta_us < targ_min_us)
- goto cleanup;
- __builtin_memcpy(&event.comm, piddatap->comm,
- sizeof(event.comm));
- event.ts_us = ts / 1000;
- event.tgid = piddatap->tgid;
- event.lport = BPF_CORE_READ(sk, __sk_common.skc_num);
- event.dport = BPF_CORE_READ(sk, __sk_common.skc_dport);
- event.af = BPF_CORE_READ(sk, __sk_common.skc_family);
- if (event.af == AF_INET) {
- event.saddr_v4 = BPF_CORE_READ(sk, __sk_common.skc_rcv_saddr);
- event.daddr_v4 = BPF_CORE_READ(sk, __sk_common.skc_daddr);
- } else {
- BPF_CORE_READ_INTO(&event.saddr_v6, sk,
- __sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
- BPF_CORE_READ_INTO(&event.daddr_v6, sk,
- __sk_common.skc_v6_daddr.in6_u.u6_addr32);
- }
- bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU,
- &event, sizeof(event));
-
-cleanup:
- bpf_map_delete_elem(&start, &sk);
- return 0;
-}
-
-
-TODO
-
-通过上面的实验，我们可以看到，tcpconnlat 工具的实现原理是基于内核的TCP连接的跟踪，并且可以跟踪到 tcp 连接的延迟时间；除了命令行使用方式之外，还可以将其和容器、k8s 等元信息综合起来，通过 prometheus 和 grafana 等工具进行网络性能分析。
-
-Eunomia 是一个使用 C/C++ 开发的基于 eBPF的轻量级，高性能云原生监控工具，旨在帮助用户了解容器的各项行为、监控可疑的容器安全事件，力求提供覆盖容器全生命周期的轻量级开源监控解决方案。它使用 Linux eBPF 技术在运行时跟踪您的系统和应用程序，并分析收集的事件以检测可疑的行为模式。目前，它包含性能分析、容器集群网络可视化分析*、容器安全感知告警、一键部署、持久化存储监控等功能，提供了多样化的 ebpf 追踪点。其核心导出器/命令行工具最小仅需要约 4MB 大小的二进制程序，即可在支持的 Linux 内核上启动。
-
-项目地址：https://github.com/yunwei37/Eunomia
-
-
-- http://kerneltravel.net/blog/2020/tcpconnlat/
-- https://network.51cto.com/article/640631.html
-
+
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2021 Hengqi Chen */
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+#include "tcpstates.h"
+
+#define MAX_ENTRIES 10240
+#define AF_INET 2
+#define AF_INET6 10
+
+const volatile bool filter_by_sport = false;
+const volatile bool filter_by_dport = false;
+const volatile short target_family = 0;
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, MAX_ENTRIES);
+ __type(key, __u16);
+ __type(value, __u16);
+} sports SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, MAX_ENTRIES);
+ __type(key, __u16);
+ __type(value, __u16);
+} dports SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, MAX_ENTRIES);
+ __type(key, struct sock *);
+ __type(value, __u64);
+} timestamps SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(__u32));
+} events SEC(".maps");
+
+SEC("tracepoint/sock/inet_sock_set_state")
+int handle_set_state(struct trace_event_raw_inet_sock_set_state *ctx)
+{
+ struct sock *sk = (struct sock *)ctx->skaddr;
+ __u16 family = ctx->family;
+ __u16 sport = ctx->sport;
+ __u16 dport = ctx->dport;
+ __u64 *tsp, delta_us, ts;
+ struct event event = {};
+
+ if (ctx->protocol != IPPROTO_TCP)
+ return 0;
+
+ if (target_family && target_family != family)
+ return 0;
+
+ if (filter_by_sport && !bpf_map_lookup_elem(&sports, &sport))
+ return 0;
+
+ if (filter_by_dport && !bpf_map_lookup_elem(&dports, &dport))
+ return 0;
+
+ tsp = bpf_map_lookup_elem(×tamps, &sk);
+ ts = bpf_ktime_get_ns();
+ if (!tsp)
+ delta_us = 0;
+ else
+ delta_us = (ts - *tsp) / 1000;
+
+ event.skaddr = (__u64)sk;
+ event.ts_us = ts / 1000;
+ event.delta_us = delta_us;
+ event.pid = bpf_get_current_pid_tgid() >> 32;
+ event.oldstate = ctx->oldstate;
+ event.newstate = ctx->newstate;
+ event.family = family;
+ event.sport = sport;
+ event.dport = dport;
+ bpf_get_current_comm(&event.task, sizeof(event.task));
+
+ if (family == AF_INET) {
+ bpf_probe_read_kernel(&event.saddr, sizeof(event.saddr), &sk->__sk_common.skc_rcv_saddr);
+ bpf_probe_read_kernel(&event.daddr, sizeof(event.daddr), &sk->__sk_common.skc_daddr);
+ } else { /* family == AF_INET6 */
+ bpf_probe_read_kernel(&event.saddr, sizeof(event.saddr), &sk->__sk_common.skc_v6_rcv_saddr.in6_u.u6_addr32);
+ bpf_probe_read_kernel(&event.daddr, sizeof(event.daddr), &sk->__sk_common.skc_v6_daddr.in6_u.u6_addr32);
+ }
+
+ bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU, &event, sizeof(event));
+
+ if (ctx->newstate == TCP_CLOSE)
+ bpf_map_delete_elem(×tamps, &sk);
+ else
+ bpf_map_update_elem(×tamps, &sk, &ts, BPF_ANY);
+
+ return 0;
+}
+
+char LICENSE[] SEC("license") = "Dual BSD/GPL";
+
tcpstates 是一个追踪当前系统上的TCP套接字的TCP状态的程序，主要通过跟踪内核跟踪点 inet_sock_set_state 来实现。统计数据通过 perf_event向用户态传输。
SEC("tracepoint/sock/inet_sock_set_state")
int handle_set_state(struct trace_event_raw_inet_sock_set_state *ctx)
@@ -2609,16 +2579,14 @@ static void handle_lost_events(void* ctx, int cpu, __u64 lost_cnt) {
}
收到事件后所调用对应的处理函数并进行输出打印。
-
-
-git clone https://github.com/libbpf/libbpf-bootstrap libbpf-bootstrap-cloned- 将 libbpf-bootstrap目录下的文件复制到
libbpf-bootstrap-cloned/examples/c下
-- 修改
libbpf-bootstrap-cloned/examples/c/Makefile ，在其 APPS 项后添加 tcpstates
-- 在
libbpf-bootstrap-cloned/examples/c 下运行 make tcpstates
-sudo ./tcpstates
-
-root@yutong-VirtualBox:~/libbpf-bootstrap/examples/c# ./tcpstates
+
+$ make
+...
+ BPF .output/tcpstates.bpf.o
+ GEN-SKEL .output/tcpstates.skel.h
+ CC .output/tcpstates.o
+ BINARY tcpstates
+$ sudo ./tcpstates
SKADDR PID COMM LADDR LPORT RADDR RPORT OLDSTATE -> NEWSTATE MS
ffff9bf61bb62bc0 164978 node 192.168.88.15 0 52.178.17.2 443 CLOSE -> SYN_SENT 0.000
ffff9bf61bb62bc0 0 swapper/0 192.168.88.15 41596 52.178.17.2 443 SYN_SENT -> ESTABLISHED 225.794
@@ -2630,11 +2598,10 @@ ffff9bf6d8ee88c0 229832 redis-serv 0.0.0.0 6379 0.0.0.0 0
ffff9bf6d8ee88c0 229832 redis-serv 0.0.0.0 6379 0.0.0.0 0 LISTEN -> CLOSE 1.763
ffff9bf7109d6900 88750 node 127.0.0.1 39755 127.0.0.1 50966 ESTABLISHED -> FIN_WAIT1 0.000
-对于输出的详细解释，详见 README.md
-
+
这里的代码修改自 https://github.com/iovisor/bcc/blob/master/libbpf-tools/tcpstates.bpf.c
-
+
网络质量在互联网社会中是一个很重要的因素。导致网络质量差的因素有很多，可能是硬件因素导致，也可能是程序
写的不好导致。为了能更好地定位网络问题，tcprtt 工具被提出。它可以监测TCP链接的往返时间，从而分析
网络质量，帮助用户定位问题来源。
@@ -2668,10 +2635,10 @@ const volatile bool targ_ms = false;
/// @sample {"interval": 1000, "type" : "log2_hist"}
struct {
- __uint(type, BPF_MAP_TYPE_HASH);
- __uint(max_entries, MAX_ENTRIES);
- __type(key, u64);
- __type(value, struct hist);
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, MAX_ENTRIES);
+ __type(key, u64);
+ __type(value, struct hist);
} hists SEC(".maps");
static struct hist zero;
@@ -2679,71 +2646,57 @@ static struct hist zero;
SEC("fentry/tcp_rcv_established")
int BPF_PROG(tcp_rcv, struct sock *sk)
{
- const struct inet_sock *inet = (struct inet_sock *)(sk);
- struct tcp_sock *ts;
- struct hist *histp;
- u64 key, slot;
- u32 srtt;
+ const struct inet_sock *inet = (struct inet_sock *)(sk);
+ struct tcp_sock *ts;
+ struct hist *histp;
+ u64 key, slot;
+ u32 srtt;
- if (targ_sport && targ_sport != inet->inet_sport)
- return 0;
- if (targ_dport && targ_dport != sk->__sk_common.skc_dport)
- return 0;
- if (targ_saddr && targ_saddr != inet->inet_saddr)
- return 0;
- if (targ_daddr && targ_daddr != sk->__sk_common.skc_daddr)
- return 0;
+ if (targ_sport && targ_sport != inet->inet_sport)
+ return 0;
+ if (targ_dport && targ_dport != sk->__sk_common.skc_dport)
+ return 0;
+ if (targ_saddr && targ_saddr != inet->inet_saddr)
+ return 0;
+ if (targ_daddr && targ_daddr != sk->__sk_common.skc_daddr)
+ return 0;
- if (targ_laddr_hist)
- key = inet->inet_saddr;
- else if (targ_raddr_hist)
- key = inet->sk.__sk_common.skc_daddr;
- else
- key = 0;
- histp = bpf_map_lookup_or_try_init(&hists, &key, &zero);
- if (!histp)
- return 0;
- ts = (struct tcp_sock *)(sk);
- srtt = BPF_CORE_READ(ts, srtt_us) >> 3;
- if (targ_ms)
- srtt /= 1000U;
- slot = log2l(srtt);
- if (slot >= MAX_SLOTS)
- slot = MAX_SLOTS - 1;
- __sync_fetch_and_add(&histp->slots[slot], 1);
- if (targ_show_ext) {
- __sync_fetch_and_add(&histp->latency, srtt);
- __sync_fetch_and_add(&histp->cnt, 1);
- }
- return 0;
+ if (targ_laddr_hist)
+ key = inet->inet_saddr;
+ else if (targ_raddr_hist)
+ key = inet->sk.__sk_common.skc_daddr;
+ else
+ key = 0;
+ histp = bpf_map_lookup_or_try_init(&hists, &key, &zero);
+ if (!histp)
+ return 0;
+ ts = (struct tcp_sock *)(sk);
+ srtt = BPF_CORE_READ(ts, srtt_us) >> 3;
+ if (targ_ms)
+ srtt /= 1000U;
+ slot = log2l(srtt);
+ if (slot >= MAX_SLOTS)
+ slot = MAX_SLOTS - 1;
+ __sync_fetch_and_add(&histp->slots[slot], 1);
+ if (targ_show_ext) {
+ __sync_fetch_and_add(&histp->latency, srtt);
+ __sync_fetch_and_add(&histp->cnt, 1);
+ }
+ return 0;
}
这段代码是基于eBPF的网络延迟分析工具，它通过hooking TCP协议栈中的tcp_rcv_established函数来统计TCP连接的RTT分布。下面是这段代码的主要工作原理：
--
-
首先定义了一个名为"hists"的eBPF哈希表，用于保存RTT直方图数据。
-
--
-
当tcp_rcv_established函数被调用时，它首先从传入的socket结构体中获取TCP相关信息，包括本地/远程IP地址、本地/远程端口号以及TCP状态信息等。
-
--
-
接下来，代码会检查用户指定的条件是否匹配当前TCP连接。如果匹配失败，则直接返回。
-
--
-
如果匹配成功，则从"hists"哈希表中查找与本地/远程IP地址匹配的直方图数据。如果该IP地址的直方图不存在，则创建一个新的直方图并插入哈希表中。
-
--
-
接下来，代码会从socket结构体中获取当前TCP连接的RTT(srtt)，并根据用户设置的选项来将srtt值进行处理。如果用户设置了"-ms"选项，则将srtt值除以1000。
-
--
-
接着，代码会将srtt值转换为直方图的槽位(slot)，并将该槽位的计数器+1。
-
--
-
如果用户设置了"-show-ext"选项，则还会累加直方图的总延迟(latency)和计数(cnt)。
-
+- 首先定义了一个名为"hists"的eBPF哈希表，用于保存RTT直方图数据。
+- 当tcp_rcv_established函数被调用时，它首先从传入的socket结构体中获取TCP相关信息，包括本地/远程IP地址、本地/远程端口号以及TCP状态信息等。
+- 接下来，代码会检查用户指定的条件是否匹配当前TCP连接。如果匹配失败，则直接返回。
+- 如果匹配成功，则从"hists"哈希表中查找与本地/远程IP地址匹配的直方图数据。如果该IP地址的直方图不存在，则创建一个新的直方图并插入哈希表中。
+- 接下来，代码会从socket结构体中获取当前TCP连接的RTT(srtt)，并根据用户设置的选项来将srtt值进行处理。如果用户设置了"-ms"选项，则将srtt值除以1000。
+- 接着，代码会将srtt值转换为直方图的槽位(slot)，并将该槽位的计数器+1。
+- 如果用户设置了"-show-ext"选项，则还会累加直方图的总延迟(latency)和计数(cnt)。
-
+
eunomia-bpf 是一个结合 Wasm 的开源 eBPF 动态加载运行时和开发工具链，它的目的是简化 eBPF 程序的开发、构建、分发、运行。可以参考 https://github.com/eunomia-bpf/eunomia-bpf 下载和安装 ecc 编译工具链和 ecli 运行时。我们使用 eunomia-bpf 编译运行这个例子。
Compile:
docker run -it -v `pwd`/:/src/ yunwei37/ebpm:latest
@@ -2817,12 +2770,12 @@ cnt = 0
4096 -> 8191 : 16 |****************************************|
8192 -> 16383 : 4 |********** |
-
+
tcprtt是一个基于eBPF的TCP延迟分析工具。通过hooking TCP协议栈中的tcp_rcv_established函数来统计TCP连接的RTT分布，可以对指定的TCP连接进行RTT分布统计，并将结果保存到eBPF哈希表中。同时，这个工具支持多种条件过滤和RTT分布数据扩展功能，以便用户可以更好地进行网络性能分析和调优。
更多的例子和详细的开发指南，请参考 eunomia-bpf 的官方文档：https://github.com/eunomia-bpf/eunomia-bpf
完整的教程和源代码已经全部开源，可以在 https://github.com/eunomia-bpf/bpf-developer-tutorial 中查看。
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+
内存泄漏对于一个程序而言是一个很严重的问题。倘若放任一个存在内存泄漏的程序运行，久而久之
系统的内存会慢慢被耗尽，导致程序运行速度显著下降。为了避免这一情况，memleak工具被提出。
它可以跟踪并匹配内存分配和释放的请求，并且打印出已经被分配资源而又尚未释放的堆栈信息。
@@ -3027,7 +2980,7 @@ int BPF_KPROBE(free_enter, void *address)
gen_free_enter函数接收一个地址参数，该函数首先使用allocs map查找该地址对应的内存分配信息。如果未找到，则表示该地址没有被分配，该函数返回0。如果找到了对应的内存分配信息，则使用bpf_map_delete_elem从allocs map中删除该信息。
接下来，调用update_statistics_del函数用于更新内存分配的统计信息，它接收堆栈ID和内存块大小作为参数。首先在combined_allocs map中查找堆栈ID对应的内存分配统计信息。如果没有找到，则输出一条日志，表示查找失败，并且函数直接返回。如果找到了对应的内存分配统计信息，则使用原子操作从内存分配统计信息中减去该内存块大小和1（表示减少了1个内存块）。这是因为堆栈ID对应的内存块数量减少了1，而堆栈ID对应的内存块总大小也减少了该内存块的大小。
最后定义了一个bpf程序BPF_KPROBE(free_enter, void *address)会在进程调用free函数时执行。它会接收参数address，表示正在释放的内存块的地址，并调用gen_free_enter函数来处理该内存块的释放。
-
+
$ git clone https://github.com/iovisor/bcc.git --recurse-submodules
$ cd libbpf-tools/
$ make memleak
@@ -3047,11 +3000,11 @@ Tracing outstanding memory allocs... Hit Ctrl-C to end
6 [<ffffffff82000b62>] <null sym>
...
-
+
memleak是一个内存泄漏监控工具，可以用来跟踪内存分配和释放时间对应的调用栈信息。随着时间的推移，这个工具可以显示长期不被释放的内存。
这份代码来自于https://github.com/iovisor/bcc/blob/master/libbpf-tools/memleak.bpf.c
-
+
Biopattern 可以统计随机/顺序磁盘I/O次数的比例。
TODO
@@ -3060,13 +3013,13 @@ Tracing outstanding memory allocs... Hit Ctrl-C to end
会获得操作信息，根据哈希表中该设备的上一次操作记录来判断本次操作是随机IO还是顺序IO，并更新操作计数。
TODO
-
+
Biopattern 可以展现随机/顺序磁盘I/O次数的比例，对于开发者把握整体I/O情况有较大帮助。
TODO
TODO
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+
LSM 从 Linux 2.6 开始成为官方内核的一个安全框架，基于此的安全实现包括 SELinux 和 AppArmor 等。在 Linux 5.7 引入 BPF LSM 后，系统开发人员已经能够自由地实现函数粒度的安全检查能力，本文就提供了这样一个案例：限制通过 socket connect 函数对特定 IPv4 地址进行访问的 BPF LSM 程序。（可见其控制精度是很高的）
LSM（Linux Security Modules）是 Linux 内核中用于支持各种计算机安全模型的框架。LSM 在 Linux 内核安全相关的关键路径上预置了一批 hook 点，从而实现了内核和安全模块的解耦，使不同的安全模块可以自由地在内核中加载/卸载，无需修改原有的内核代码就可以加入安全检查功能。
@@ -3151,7 +3104,7 @@ int BPF_PROG(restrict_connect, struct socket *sock, struct sockaddr *address, in
若请求地址为 1.1.1.1 则拒绝连接，否则允许连接；
在程序运行期间，所有通过 socket 的连接操作都会被输出到 /sys/kernel/debug/tracing/trace_pipe。
-
+
通过容器编译：
docker run -it -v `pwd`/:/src/ yunwei37/ebpm:latest
@@ -3182,7 +3135,7 @@ Retrying.
wget-7061 [000] d...1 6318.800698: bpf_trace_printk: lsm: found connect to 16843009
wget-7061 [000] d...1 6318.800700: bpf_trace_printk: lsm: blocking 16843009
-
+
本文介绍了如何使用 BPF LSM 来限制通过 socket 对特定 IPv4 地址的访问。我们可以通过修改 GRUB 配置文件来开启 LSM 的 BPF 挂载点。在 eBPF 程序中，我们通过 BPF_PROG 宏定义函数，并通过 SEC 宏指定挂载点；在函数实现上，遵循 LSM 安全检查模块中 "cannot override a denial" 的原则，并根据 socket 连接请求的目的地址对该请求进行限制。
更多的例子和详细的开发指南，请参考 eunomia-bpf 的官方文档：https://github.com/eunomia-bpf/eunomia-bpf
完整的教程和源代码已经全部开源，可以在 https://github.com/eunomia-bpf/bpf-developer-tutorial 中查看。
@@ -3233,7 +3186,7 @@ char __license[] SEC("license") = "GPL";
这些注释告诉 TC 将 eBPF 程序附加到网络接口的 ingress 附加点，并指定了 handle 和 priority 选项的值。
总之，这段代码实现了一个简单的 eBPF 程序，用于捕获数据包并打印出它们的信息。
-
+
docker run -it -v `pwd`/:/src/ yunwei37/ebpm:latest
or compile with ecc:
@@ -3254,7 +3207,7 @@ something like this:
sshd-1254728 [006] ..s1 8737831.674349: 0: Got IP packet: tot_len: 72, ttl: 64
node-1254811 [007] ..s1 8737831.674550: 0: Got IP packet: tot_len: 71, ttl: 64
-
+
TODO
diff --git a/searchindex.js b/searchindex.js
index 1650884..a266460 100644
--- a/searchindex.js
+++ b/searchindex.js
@@ -1 +1 @@
-Object.assign(window.search, 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10240);\n} sizes SEC(\".maps\"); struct { __uint(type, BPF_MAP_TYPE_HASH); __type(key, u64); /* address */ __type(value, struct alloc_info); __uint(max_entries, ALLOCS_MAX_ENTRIES);\n} allocs SEC(\".maps\"); struct { __uint(type, BPF_MAP_TYPE_HASH); __type(key, u64); /* stack id */ __type(value, union combined_alloc_info); __uint(max_entries, COMBINED_ALLOCS_MAX_ENTRIES);\n} combined_allocs SEC(\".maps\"); struct { __uint(type, BPF_MAP_TYPE_HASH); __type(key, u64); __type(value, u64); __uint(max_entries, 10240);\n} memptrs SEC(\".maps\"); struct { __uint(type, BPF_MAP_TYPE_STACK_TRACE); __type(key, u32);\n} stack_traces SEC(\".maps\"); struct alloc_info { __u64 size; __u64 timestamp_ns; int stack_id;\n}; union combined_alloc_info { struct { __u64 total_size : 40; __u64 number_of_allocs : 24; }; __u64 bits;\n}; 这段代码定义了memleak工具中使用的5个BPF Map： sizes用于记录程序中每个内存分配请求的大小； allocs用于跟踪每个内存分配请求的详细信息，包括请求的大小、堆栈信息等； combined_allocs的键是堆栈的唯一标识符(stack id)，值是一个combined_alloc_info联合体，用于记录该堆栈的内存分配总大小和内存分配数量； memptrs用于跟踪每个内存分配请求返回的指针，以便在内存释放请求到来时找到对应的内存分配请求； stack_traces是一个堆栈跟踪类型的哈希表，用于存储每个线程的堆栈信息（key为线程id，value为堆栈跟踪信息）以便在内存分配和释放请求到来时能够追踪和分析相应的堆栈信息。 其中combined_alloc_info是一个联合体，其中包含一个结构体和一个unsigned long long类型的变量bits。结构体中的两个成员变量total_size和number_of_allocs分别表示总分配大小和分配的次数。其中40和24分别表示total_size和number_of_allocs这两个成员变量所占用的位数，用来限制其大小。通过这样的位数限制，可以节省combined_alloc_info结构的存储空间。同时，由于total_size和number_of_allocs在存储时是共用一个unsigned long long类型的变量bits，因此可以通过在成员变量bits上进行位运算来访问和修改total_size和number_of_allocs，从而避免了在程序中定义额外的变量和函数的复杂性。 static int gen_alloc_enter(size_t size)\n{ if (size < min_size || size > max_size) return 0; if (sample_rate > 1) { if (bpf_ktime_get_ns() % sample_rate != 0) return 0; } const pid_t pid = bpf_get_current_pid_tgid() >> 32; bpf_map_update_elem(&sizes, &pid, &size, BPF_ANY); if (trace_all) bpf_printk(\"alloc entered, size = %lu\\n\", size); return 0;\n} SEC(\"uprobe\")\nint BPF_KPROBE(malloc_enter, size_t size)\n{ return gen_alloc_enter(size);\n} 这个函数用于处理内存分配请求的进入事件。它会首先检查内存分配请求的大小是否在指定的范围内，如果不在范围内，则直接返回0表示不处理该事件。如果启用了采样率(sample_rate > 1)，则该函数会采样内存分配请求的进入事件。如果当前时间戳不是采样周期的倍数，则也会直接返回0，表示不处理该事件。接下来，该函数会获取当前线程的PID并将其存储在pid变量中。然后，它会将当前线程的pid和请求的内存分配大小存储在sizes map中，以便后续收集和分析内存分配信息。如果开启了跟踪模式(trace_all)，该函数会通过bpf_printk打印日志信息，以便用户实时监控内存分配的情况。 最后定义了BPF_KPROBE(malloc_enter, size_t size)，它会在malloc函数被调用时被BPF uprobe拦截执行，并通过gen_alloc_enter来记录内存分配大小。 static void update_statistics_add(u64 stack_id, u64 sz)\n{ union combined_alloc_info *existing_cinfo; existing_cinfo = bpf_map_lookup_or_try_init(&combined_allocs, &stack_id, &initial_cinfo); if (!existing_cinfo) return; const union combined_alloc_info incremental_cinfo = { .total_size = sz, .number_of_allocs = 1 }; __sync_fetch_and_add(&existing_cinfo->bits, incremental_cinfo.bits);\n}\nstatic int gen_alloc_exit2(void *ctx, u64 address)\n{ const pid_t pid = bpf_get_current_pid_tgid() >> 32; struct alloc_info info; const u64* size = bpf_map_lookup_elem(&sizes, &pid); if (!size) return 0; // missed alloc entry __builtin_memset(&info, 0, sizeof(info)); info.size = *size; bpf_map_delete_elem(&sizes, &pid); if (address != 0) { info.timestamp_ns = bpf_ktime_get_ns(); info.stack_id = bpf_get_stackid(ctx, &stack_traces, stack_flags); bpf_map_update_elem(&allocs, &address, &info, BPF_ANY); update_statistics_add(info.stack_id, info.size); } if (trace_all) { bpf_printk(\"alloc exited, size = %lu, result = %lx\\n\", info.size, address); } return 0;\n}\nstatic int gen_alloc_exit(struct pt_regs *ctx)\n{ return gen_alloc_exit2(ctx, PT_REGS_RC(ctx));\n} SEC(\"uretprobe\")\nint BPF_KRETPROBE(malloc_exit)\n{ return gen_alloc_exit(ctx);\n} gen_alloc_exit2函数会在内存释放时被调用，它用来记录内存释放的信息，并更新相关的 map。具体地，它首先通过 bpf_get_current_pid_tgid 来获取当前进程的 PID，并将其右移32位，获得PID值，然后使用 bpf_map_lookup_elem 查找 sizes map 中与该 PID 相关联的内存分配大小信息，并将其赋值给 info.size。如果找不到相应的 entry，则返回 0，表示在内存分配时没有记录到该 PID 相关的信息。接着，它会调用 __builtin_memset 来将 info 的所有字段清零，并调用 bpf_map_delete_elem 来删除 sizes map 中与该 PID 相关联的 entry。 如果 address 不为 0，则说明存在相应的内存分配信息，此时它会调用 bpf_ktime_get_ns 来获取当前时间戳，并将其赋值给 info.timestamp_ns。然后，它会调用 bpf_get_stackid 来获取当前函数调用堆栈的 ID，并将其赋值给 info.stack_id。最后，它会调用 bpf_map_update_elem 来将 address 和 info 相关联，即将 address 映射到 info。随后，它会调用 update_statistics_add 函数来更新 combined_allocs map 中与 info.stack_id 相关联的内存分配信息。 最后，如果 trace_all 为真，则会调用 bpf_printk 打印相关的调试信息。 update_statistics_add函数的主要作用是更新内存分配的统计信息，其中参数stack_id是当前内存分配的堆栈ID，sz是当前内存分配的大小。该函数首先通过bpf_map_lookup_or_try_init函数在combined_allocs map中查找与当前堆栈ID相关联的combined_alloc_info结构体，如果找到了，则将新的分配大小和分配次数加入到已有的combined_alloc_info结构体中；如果未找到，则使用initial_cinfo初始化一个新的combined_alloc_info结构体，并添加到combined_allocs map中。 更新combined_alloc_info结构体的方法是使用__sync_fetch_and_add函数，原子地将incremental_cinfo中的值累加到existing_cinfo中的值中。通过这种方式，即使多个线程同时调用update_statistics_add函数，也可以保证计数的正确性。 在gen_alloc_exit函数中，将ctx参数传递给gen_alloc_exit2函数，并将它的返回值作为自己的返回值。这里使用了PT_REGS_RC宏获取函数返回值。 最后定义的BPF_KRETPROBE(malloc_exit)是一个kretprobe类型的函数，用于在malloc函数返回时执行。并调用gen_alloc_exit函数跟踪内存分配和释放的请求。 static void update_statistics_del(u64 stack_id, u64 sz)\n{ union combined_alloc_info *existing_cinfo; existing_cinfo = bpf_map_lookup_elem(&combined_allocs, &stack_id); if (!existing_cinfo) { bpf_printk(\"failed to lookup combined allocs\\n\"); return; } const union combined_alloc_info decremental_cinfo = { .total_size = sz, .number_of_allocs = 1 }; __sync_fetch_and_sub(&existing_cinfo->bits, decremental_cinfo.bits);\n} static int gen_free_enter(const void *address)\n{ const u64 addr = (u64)address; const struct alloc_info *info = bpf_map_lookup_elem(&allocs, &addr); if (!info) return 0; bpf_map_delete_elem(&allocs, &addr); update_statistics_del(info->stack_id, info->size); if (trace_all) { bpf_printk(\"free entered, address = %lx, size = %lu\\n\", address, info->size); } return 0;\n} SEC(\"uprobe\")\nint BPF_KPROBE(free_enter, void *address)\n{ return gen_free_enter(address);\n} gen_free_enter函数接收一个地址参数，该函数首先使用allocs map查找该地址对应的内存分配信息。如果未找到，则表示该地址没有被分配，该函数返回0。如果找到了对应的内存分配信息，则使用bpf_map_delete_elem从allocs map中删除该信息。 接下来，调用update_statistics_del函数用于更新内存分配的统计信息，它接收堆栈ID和内存块大小作为参数。首先在combined_allocs map中查找堆栈ID对应的内存分配统计信息。如果没有找到，则输出一条日志，表示查找失败，并且函数直接返回。如果找到了对应的内存分配统计信息，则使用原子操作从内存分配统计信息中减去该内存块大小和1（表示减少了1个内存块）。这是因为堆栈ID对应的内存块数量减少了1，而堆栈ID对应的内存块总大小也减少了该内存块的大小。 最后定义了一个bpf程序BPF_KPROBE(free_enter, void *address)会在进程调用free函数时执行。它会接收参数address，表示正在释放的内存块的地址，并调用gen_free_enter函数来处理该内存块的释放。","breadcrumbs":"eBPF 入门实践教程：编写 eBPF 程序 Memleak 监控内存泄漏 » 编写 eBPF 程序","id":"102","title":"编写 eBPF 程序"},"103":{"body":"$ git clone https://github.com/iovisor/bcc.git --recurse-submodules $ cd libbpf-tools/\n$ make memleak\n$ sudo ./memleak using default object: libc.so.6\nusing page size: 4096\ntracing kernel: true\nTracing outstanding memory allocs... Hit Ctrl-C to end\n[17:17:27] Top 10 stacks with outstanding allocations:\n1236992 bytes in 302 allocations from stack 0 [] 1 [] 2 [] 3 [] 4 [] 5 [] 6 [] \n...","breadcrumbs":"eBPF 入门实践教程：编写 eBPF 程序 Memleak 监控内存泄漏 » 编译运行","id":"103","title":"编译运行"},"104":{"body":"memleak是一个内存泄漏监控工具，可以用来跟踪内存分配和释放时间对应的调用栈信息。随着时间的推移，这个工具可以显示长期不被释放的内存。 这份代码来自于https://github.com/iovisor/bcc/blob/master/libbpf-tools/memleak.bpf.c","breadcrumbs":"eBPF 入门实践教程：编写 eBPF 程序 Memleak 监控内存泄漏 » 总结","id":"104","title":"总结"},"105":{"body":"","breadcrumbs":"eBPF 入门实践教程：编写 eBPF 程序 Biopattern: 统计随机/顺序磁盘 I/O » eBPF 入门实践教程：编写 eBPF 程序 Biopattern: 统计随机/顺序磁盘 I/O","id":"105","title":"eBPF 入门实践教程：编写 eBPF 程序 Biopattern: 统计随机/顺序磁盘 I/O"},"106":{"body":"Biopattern 可以统计随机/顺序磁盘I/O次数的比例。 TODO","breadcrumbs":"eBPF 入门实践教程：编写 eBPF 程序 Biopattern: 统计随机/顺序磁盘 I/O » 背景","id":"106","title":"背景"},"107":{"body":"Biopattern 的ebpf代码在 tracepoint/block/block_rq_complete 挂载点下实现。在磁盘完成IO请求 后，程序会经过此挂载点。Biopattern 内部存有一张以设备号为主键的哈希表，当程序经过挂载点时, Biopattern 会获得操作信息，根据哈希表中该设备的上一次操作记录来判断本次操作是随机IO还是顺序IO，并更新操作计数。","breadcrumbs":"eBPF 入门实践教程：编写 eBPF 程序 Biopattern: 统计随机/顺序磁盘 I/O » 实现原理","id":"107","title":"实现原理"},"108":{"body":"TODO","breadcrumbs":"eBPF 入门实践教程：编写 eBPF 程序 Biopattern: 统计随机/顺序磁盘 I/O » 编写 eBPF 程序","id":"108","title":"编写 eBPF 程序"},"109":{"body":"Biopattern 可以展现随机/顺序磁盘I/O次数的比例，对于开发者把握整体I/O情况有较大帮助。 TODO","breadcrumbs":"eBPF 入门实践教程：编写 eBPF 程序 Biopattern: 统计随机/顺序磁盘 I/O » 总结","id":"109","title":"总结"},"11":{"body":"开发、构建和分发 eBPF 一直以来都是一个高门槛的工作，使用 BCC、bpftrace 等工具开发效率高、可移植性好，但是分发部署时需要安装 LLVM、Clang等编译环境，每次运行的时候执行本地或远程编译过程，资源消耗较大；使用原生的 CO-RE libbpf时又需要编写不少用户态加载代码来帮助 eBPF 程序正确加载和从内核中获取上报的信息，同时对于 eBPF 程序的分发、管理也没有很好地解决方案。 eunomia-bpf 是一个开源的 eBPF 动态加载运行时和开发工具链，是为了简化 eBPF 程序的开发、构建、分发、运行而设计的，基于 libbpf 的 CO-RE 轻量级开发框架。 使用 eunomia-bpf ，可以： 在编写 eBPF 程序或工具时只编写内核态代码，自动获取内核态导出信息，并作为模块动态加载； 使用 WASM 进行用户态交互程序的开发，在 WASM 虚拟机内部控制整个 eBPF 程序的加载和执行，以及处理相关数据； eunomia-bpf 可以将预编译的 eBPF 程序打包为通用的 JSON 或 WASM 模块，跨架构和内核版本进行分发，无需重新编译即可动态加载运行。 eunomia-bpf 由一个编译工具链和一个运行时库组成, 对比传统的 BCC、原生 libbpf 等框架，大幅简化了 eBPF 程序的开发流程，在大多数时候只需编写内核态代码，即可轻松构建、打包、发布完整的 eBPF 应用，同时内核态 eBPF 代码保证和主流的 libbpf, libbpfgo, libbpf-rs 等开发框架的 100% 兼容性。需要编写用户态代码的时候，也可以借助 Webassembly 实现通过多种语言进行用户态开发。和 bpftrace 等脚本工具相比, eunomia-bpf 保留了类似的便捷性, 同时不仅局限于 trace 方面, 可以用于更多的场景, 如网络、安全等等。 eunomia-bpf 项目 Github 地址: https://github.com/eunomia-bpf/eunomia-bpf gitee 镜像: https://gitee.com/anolis/eunomia","breadcrumbs":"eBPF 入门开发实践教程一：介绍 eBPF 的基本概念、常见的开发工具 » eunomia-bpf","id":"11","title":"eunomia-bpf"},"110":{"body":"TODO","breadcrumbs":"更多的参考资料 » 更多的参考资料","id":"110","title":"更多的参考资料"},"111":{"body":"","breadcrumbs":"eBPF 入门实践教程：使用 LSM 进行安全检测防御 » eBPF 入门实践教程：使用 LSM 进行安全检测防御","id":"111","title":"eBPF 入门实践教程：使用 LSM 进行安全检测防御"},"112":{"body":"LSM 从 Linux 2.6 开始成为官方内核的一个安全框架，基于此的安全实现包括 SELinux 和 AppArmor 等。在 Linux 5.7 引入 BPF LSM 后，系统开发人员已经能够自由地实现函数粒度的安全检查能力，本文就提供了这样一个案例：限制通过 socket connect 函数对特定 IPv4 地址进行访问的 BPF LSM 程序。（可见其控制精度是很高的）","breadcrumbs":"eBPF 入门实践教程：使用 LSM 进行安全检测防御 » 背景","id":"112","title":"背景"},"113":{"body":"LSM（Linux Security Modules）是 Linux 内核中用于支持各种计算机安全模型的框架。LSM 在 Linux 内核安全相关的关键路径上预置了一批 hook 点，从而实现了内核和安全模块的解耦，使不同的安全模块可以自由地在内核中加载/卸载，无需修改原有的内核代码就可以加入安全检查功能。 在过去，使用 LSM 主要通过配置已有的安全模块（如 SELinux 和 AppArmor）或编写自己的内核模块；而在 Linux 5.7 引入 BPF LSM 机制后，一切都变得不同了：现在，开发人员可以通过 eBPF 编写自定义的安全策略，并将其动态加载到内核中的 LSM 挂载点，而无需配置或编写内核模块。 现在 LSM 支持的 hook 点包括但不限于： 对文件的打开、创建、删除和移动等； 文件系统的挂载； 对 task 和 process 的操作； 对 socket 的操作（创建、绑定 socket，发送和接收消息等）； 更多 hook 点可以参考 lsm_hooks.h 。","breadcrumbs":"eBPF 入门实践教程：使用 LSM 进行安全检测防御 » LSM 概述","id":"113","title":"LSM 概述"},"114":{"body":"首先，请确认内核版本高于 5.7。接下来，可以通过 $ cat /boot/config-$(uname -r) | grep BPF_LSM\nCONFIG_BPF_LSM=y 判断是否内核是否支持 BPF LSM。上述条件都满足的情况下，可以通过 $ cat /sys/kernel/security/lsm\nndlock,lockdown,yama,integrity,apparmor 查看输出是否包含 bpf 选项，如果输出不包含（像上面的例子），可以通过修改 /etc/default/grub： GRUB_CMDLINE_LINUX=\"lsm=ndlock,lockdown,yama,integrity,apparmor,bpf\" 并通过 update-grub2 命令更新 grub 配置（不同系统的对应命令可能不同），然后重启系统。","breadcrumbs":"eBPF 入门实践教程：使用 LSM 进行安全检测防御 » 确认 BPF LSM 是否可用","id":"114","title":"确认 BPF LSM 是否可用"},"115":{"body":"// lsm-connect.bpf.c\n#include \"vmlinux.h\"\n#include \n#include \n#include char LICENSE[] SEC(\"license\") = \"GPL\"; #define EPERM 1\n#define AF_INET 2 const __u32 blockme = 16843009; // 1.1.1.1 -> int SEC(\"lsm/socket_connect\")\nint BPF_PROG(restrict_connect, struct socket *sock, struct sockaddr *address, int addrlen, int ret)\n{ // Satisfying \"cannot override a denial\" rule if (ret != 0) { return ret; } // Only IPv4 in this example if (address->sa_family != AF_INET) { return 0; } // Cast the address to an IPv4 socket address struct sockaddr_in *addr = (struct sockaddr_in *)address; // Where do you want to go? __u32 dest = addr->sin_addr.s_addr; bpf_printk(\"lsm: found connect to %d\", dest); if (dest == blockme) { bpf_printk(\"lsm: blocking %d\", dest); return -EPERM; } return 0;\n} 这是一段 C 实现的 eBPF 内核侧代码，它会阻碍所有试图通过 socket 对 1.1.1.1 的连接操作，其中： SEC(\"lsm/socket_connect\") 宏指出该程序期望的挂载点； 程序通过 BPF_PROG 宏定义（详情可查看 tools/lib/bpf/bpf_tracing.h ）； restrict_connect 是 BPF_PROG 宏要求的程序名； ret 是该挂载点上（潜在的）当前函数之前的 LSM 检查程序的返回值； 整个程序的思路不难理解： 首先，若其他安全检查函数返回值不为 0（不通过），则无需检查，直接返回不通过； 接下来，判断是否为 IPV4 的连接请求，并比较试图连接的地址是否为 1.1.1.1； 若请求地址为 1.1.1.1 则拒绝连接，否则允许连接； 在程序运行期间，所有通过 socket 的连接操作都会被输出到 /sys/kernel/debug/tracing/trace_pipe。","breadcrumbs":"eBPF 入门实践教程：使用 LSM 进行安全检测防御 » 编写 eBPF 程序","id":"115","title":"编写 eBPF 程序"},"116":{"body":"通过容器编译： docker run -it -v `pwd`/:/src/ yunwei37/ebpm:latest 或是通过 ecc 编译： $ ecc lsm-connect.bpf.c\nCompiling bpf object...\nPacking ebpf object and config into package.json... 并通过 ecli 运行： $ sudo ecli run package.json 接下来，可以打开另一个 terminal，并尝试访问 1.1.1.1： $ ping 1.1.1.1\nping: connect: Operation not permitted\n$ curl 1.1.1.1\ncurl: (7) Couldn't connect to server\n$ wget 1.1.1.1\n--2023-04-23 08:41:18-- (try: 2) http://1.1.1.1/\nConnecting to 1.1.1.1:80... failed: Operation not permitted.\nRetrying. 同时，我们可以查看 bpf_printk 的输出： $ sudo cat /sys/kernel/debug/tracing/trace_pipe ping-7054 [000] d...1 6313.430872: bpf_trace_printk: lsm: found connect to 16843009 ping-7054 [000] d...1 6313.430874: bpf_trace_printk: lsm: blocking 16843009 curl-7058 [000] d...1 6316.346582: bpf_trace_printk: lsm: found connect to 16843009 curl-7058 [000] d...1 6316.346584: bpf_trace_printk: lsm: blocking 16843009 wget-7061 [000] d...1 6318.800698: bpf_trace_printk: lsm: found connect to 16843009 wget-7061 [000] d...1 6318.800700: bpf_trace_printk: lsm: blocking 16843009","breadcrumbs":"eBPF 入门实践教程：使用 LSM 进行安全检测防御 » 编译运行","id":"116","title":"编译运行"},"117":{"body":"本文介绍了如何使用 BPF LSM 来限制通过 socket 对特定 IPv4 地址的访问。我们可以通过修改 GRUB 配置文件来开启 LSM 的 BPF 挂载点。在 eBPF 程序中，我们通过 BPF_PROG 宏定义函数，并通过 SEC 宏指定挂载点；在函数实现上，遵循 LSM 安全检查模块中 \"cannot override a denial\" 的原则，并根据 socket 连接请求的目的地址对该请求进行限制。 更多的例子和详细的开发指南，请参考 eunomia-bpf 的官方文档： https://github.com/eunomia-bpf/eunomia-bpf 完整的教程和源代码已经全部开源，可以在 https://github.com/eunomia-bpf/bpf-developer-tutorial 中查看。","breadcrumbs":"eBPF 入门实践教程：使用 LSM 进行安全检测防御 » 总结","id":"117","title":"总结"},"118":{"body":"https://github.com/leodido/demo-cloud-native-ebpf-day https://aya-rs.dev/book/programs/lsm/#writing-lsm-bpf-program","breadcrumbs":"eBPF 入门实践教程：使用 LSM 进行安全检测防御 » 参考","id":"118","title":"参考"},"119":{"body":"","breadcrumbs":"eBPF 入门实践教程：使用 eBPF 进行 tc 流量控制 » eBPF 入门实践教程：使用 eBPF 进行 tc 流量控制","id":"119","title":"eBPF 入门实践教程：使用 eBPF 进行 tc 流量控制"},"12":{"body":"eBPF 介绍： https://ebpf.io/ BPF Compiler Collection (BCC)： https://github.com/iovisor/bcc eunomia-bpf： https://github.com/eunomia-bpf/eunomia-bpf 完整的教程和源代码已经全部开源，可以在 https://github.com/eunomia-bpf/bpf-developer-tutorial 中查看。","breadcrumbs":"eBPF 入门开发实践教程一：介绍 eBPF 的基本概念、常见的开发工具 » 参考资料","id":"12","title":"参考资料"},"120":{"body":"#include \n#include \n#include \n#include #define TC_ACT_OK 0\n#define ETH_P_IP 0x0800 /* Internet Protocol packet */ /// @tchook {\"ifindex\":1, \"attach_point\":\"BPF_TC_INGRESS\"}\n/// @tcopts {\"handle\":1, \"priority\":1}\nSEC(\"tc\")\nint tc_ingress(struct __sk_buff *ctx)\n{ void *data_end = (void *)(__u64)ctx->data_end; void *data = (void *)(__u64)ctx->data; struct ethhdr *l2; struct iphdr *l3; if (ctx->protocol != bpf_htons(ETH_P_IP)) return TC_ACT_OK; l2 = data; if ((void *)(l2 + 1) > data_end) return TC_ACT_OK; l3 = (struct iphdr *)(l2 + 1); if ((void *)(l3 + 1) > data_end) return TC_ACT_OK; bpf_printk(\"Got IP packet: tot_len: %d, ttl: %d\", bpf_ntohs(l3->tot_len), l3->ttl); return TC_ACT_OK;\n} char __license[] SEC(\"license\") = \"GPL\"; 这段代码定义了一个 eBPF 程序，它可以通过 Linux TC（Transmission Control）来捕获数据包并进行处理。在这个程序中，我们限定了只捕获 IPv4 协议的数据包，然后通过 bpf_printk 函数打印出数据包的总长度和 Time-To-Live（TTL）字段的值。 需要注意的是，我们在代码中使用了一些 BPF 库函数，例如 bpf_htons 和 bpf_ntohs 函数，它们用于进行网络字节序和主机字节序之间的转换。此外，我们还使用了一些注释来为 TC 提供附加点和选项信息。例如，在这段代码的开头，我们使用了以下注释： /// @tchook {\"ifindex\":1, \"attach_point\":\"BPF_TC_INGRESS\"}\n/// @tcopts {\"handle\":1, \"priority\":1} 这些注释告诉 TC 将 eBPF 程序附加到网络接口的 ingress 附加点，并指定了 handle 和 priority 选项的值。 总之，这段代码实现了一个简单的 eBPF 程序，用于捕获数据包并打印出它们的信息。","breadcrumbs":"eBPF 入门实践教程：使用 eBPF 进行 tc 流量控制 » tc 程序示例","id":"120","title":"tc 程序示例"},"121":{"body":"docker run -it -v `pwd`/:/src/ yunwei37/ebpm:latest or compile with ecc: $ ecc tc.bpf.c\nCompiling bpf object...\nPacking ebpf object and config into package.json... $ sudo ecli run ./package.json\n...\nSuccessfully started! Please run `sudo cat /sys/kernel/debug/tracing/trace_pipe` to see output of the BPF program.\n...... The tc output in /sys/kernel/debug/tracing/trace_pipe should look something like this: $ sudo cat /sys/kernel/debug/tracing/trace_pipe node-1254811 [007] ..s1 8737831.671074: 0: Got IP packet: tot_len: 79, ttl: 64 sshd-1254728 [006] ..s1 8737831.674334: 0: Got IP packet: tot_len: 79, ttl: 64 sshd-1254728 [006] ..s1 8737831.674349: 0: Got IP packet: tot_len: 72, ttl: 64 node-1254811 [007] ..s1 8737831.674550: 0: Got IP packet: tot_len: 71, ttl: 64","breadcrumbs":"eBPF 入门实践教程：使用 eBPF 进行 tc 流量控制 » 编译运行","id":"121","title":"编译运行"},"122":{"body":"TODO","breadcrumbs":"eBPF 入门实践教程：使用 eBPF 进行 tc 流量控制 » 总结","id":"122","title":"总结"},"123":{"body":"","breadcrumbs":"BPF Features by Linux Kernel Version » BPF Features by Linux Kernel Version","id":"123","title":"BPF Features by Linux Kernel Version"},"124":{"body":"Kernel version Commit 3.15 bd4cf0ed331a","breadcrumbs":"BPF Features by Linux Kernel Version » eBPF support","id":"124","title":"eBPF support"},"125":{"body":"The list of supported architectures for your kernel can be retrieved with: git grep HAVE_EBPF_JIT arch/ Feature / Architecture Kernel version Commit x86_64 3.16 622582786c9e ARM64 3.18 e54bcde3d69d s390 4.1 054623105728 Constant blinding for JIT machines 4.7 4f3446bb809f PowerPC64 4.8 156d0e290e96 Constant blinding - PowerPC64 4.9 b7b7013cac55 Sparc64 4.12 7a12b5031c6b MIPS 4.13 f381bf6d82f0 ARM32 4.14 39c13c204bb1 x86_32 4.18 03f5781be2c7 RISC-V RV64G 5.1 2353ecc6f91f RISC-V RV32G 5.7 5f316b65e99f PowerPC32 5.13 51c66ad849a7 LoongArch 6.1 5dc615520c4d","breadcrumbs":"BPF Features by Linux Kernel Version » JIT compiling","id":"125","title":"JIT compiling"},"126":{"body":"Several (but not all) of these main features translate to an eBPF program type. The list of such program types supported in your kernel can be found in file include/uapi/linux/bpf.h : git grep -W 'bpf_prog_type {' include/uapi/linux/bpf.h Feature Kernel version Commit AF_PACKET (libpcap/tcpdump, cls_bpf classifier, netfilter's xt_bpf, team driver's load-balancing mode…) 3.15 bd4cf0ed331a Kernel helpers 3.15 bd4cf0ed331a bpf() syscall 3.18 99c55f7d47c0 Maps ( a.k.a. Tables; details below) 3.18 99c55f7d47c0 BPF attached to sockets 3.19 89aa075832b0 BPF attached to kprobes 4.1 2541517c32be cls_bpf / act_bpf for tc 4.1 e2e9b6541dd4 Tail calls 4.2 04fd61ab36ec Non-root programs on sockets 4.4 1be7f75d1668 Persistent maps and programs (virtual FS) 4.4 b2197755b263 tc's direct-action (da) mode 4.4 045efa82ff56 tc's clsact qdisc 4.5 1f211a1b929c BPF attached to tracepoints 4.7 98b5c2c65c29 Direct packet access 4.7 969bf05eb3ce XDP (see below) 4.8 6a773a15a1e8 BPF attached to perf events 4.9 0515e5999a46 Hardware offload for tc's cls_bpf 4.9 332ae8e2f6ec Verifier exposure and internal hooks 4.9 13a27dfc6697 BPF attached to cgroups for socket filtering 4.10 0e33661de493 Lightweight tunnel encapsulation 4.10 3a0af8fd61f9 e BPF support for xt_bpf module (iptables) 4.10 2c16d6033264 BPF program tag 4.10 7bd509e311f4 Tracepoints to debug BPF 4.11 (removed in 4.18) a67edbf4fb6d 4d220ed0f814 Testing / benchmarking BPF programs 4.12 1cf1cae963c2 BPF programs and maps IDs 4.13 dc4bb0e23561 BPF support for sock_ops 4.13 40304b2a1567 BPF support for skbs on sockets 4.14 b005fd189cec bpftool utility in kernel sources 4.15 71bb428fe2c1 BPF attached to cgroups as device controller 4.15 ebc614f68736 bpf2bpf function calls 4.16 cc8b0b92a169 BPF used for monitoring socket RX/TX data 4.17 4f738adba30a BPF attached to raw tracepoints 4.17 c4f6699dfcb8 BPF attached to bind() system call 4.17 4fbac77d2d09 aac3fc320d94 BPF attached to connect() system call 4.17 d74bad4e74ee BPF Type Format (BTF) 4.18 69b693f0aefa AF_XDP 4.18 fbfc504a24f5 bpfilter 4.18 d2ba09c17a06 End.BPF action for seg6local LWT 4.18 004d4b274e2a BPF attached to LIRC devices 4.18 f4364dcfc86d Pass map values to map helpers 4.18 d71962f3e627 BPF socket reuseport 4.19 2dbb9b9e6df6 BPF flow dissector 4.20 d58e468b1112 BPF 1M insn limit 5.2 c04c0d2b968a BPF cgroup sysctl 5.2 7b146cebe30c BPF raw tracepoint writable 5.2 9df1c28bb752 BPF bounded loop 5.3 2589726d12a1 BPF trampoline 5.5 fec56f5890d9 BPF LSM hook 5.7 fc611f47f218 641cd7b06c91 BPF iterator 5.8 180139dca8b3 BPF socket lookup hook 5.9 e9ddbb7707ff Sleepable BPF programs 5.10 1e6c62a88215","breadcrumbs":"BPF Features by Linux Kernel Version » Main features","id":"126","title":"Main features"},"127":{"body":"Program type Kernel version Commit Enum Socket filter 3.19 ddd872bc3098 BPF_PROG_TYPE_SOCKET_FILTER Kprobe 4.1 2541517c32be BPF_PROG_TYPE_KPROBE traffic control (TC) 4.1 96be4325f443 BPF_PROG_TYPE_SCHED_CLS traffic control (TC) 4.1 94caee8c312d BPF_PROG_TYPE_SCHED_ACT Tracepoint 4.7 98b5c2c65c29 BPF_PROG_TYPE_TRACEPOINT XDP 4.8 6a773a15a1e8 BPF_PROG_TYPE_XDP Perf event 4.9 0515e5999a46 BPF_PROG_TYPE_PERF_EVENT cgroup socket filtering 4.10 0e33661de493 BPF_PROG_TYPE_CGROUP_SKB cgroup sock modification 4.10 610236587600 BPF_PROG_TYPE_CGROUP_SOCK lightweight tunnel (IN) 4.10 3a0af8fd61f9 BPF_PROG_TYPE_LWT_IN lightweight tunnel (OUT) 4.10 3a0af8fd61f9 BPF_PROG_TYPE_LWT_OUT lightweight tunnel (XMIT) 4.10 3a0af8fd61f9 BPF_PROG_TYPE_LWT_XMIT cgroup sock ops (per conn) 4.13 40304b2a1567 BPF_PROG_TYPE_SOCK_OPS stream parser / stream verdict 4.14 b005fd189cec BPF_PROG_TYPE_SK_SKB cgroup device manager 4.15 ebc614f68736 BPF_PROG_TYPE_CGROUP_DEVICE socket msg verdict 4.17 4f738adba30a BPF_PROG_TYPE_SK_MSG Raw tracepoint 4.17 c4f6699dfcb8 BPF_PROG_TYPE_RAW_TRACEPOINT socket binding 4.17 4fbac77d2d09 BPF_PROG_TYPE_CGROUP_SOCK_ADDR LWT seg6local 4.18 004d4b274e2a BPF_PROG_TYPE_LWT_SEG6LOCAL lirc devices 4.18 f4364dcfc86d BPF_PROG_TYPE_LIRC_MODE2 lookup SO_REUSEPORT socket 4.19 2dbb9b9e6df6 BPF_PROG_TYPE_SK_REUSEPORT flow dissector 4.20 d58e468b1112 BPF_PROG_TYPE_FLOW_DISSECTOR cgroup sysctl 5.2 7b146cebe30c BPF_PROG_TYPE_CGROUP_SYSCTL writable raw tracepoints 5.2 9df1c28bb752 BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE cgroup getsockopt/setsockopt 5.3 0d01da6afc54 BPF_PROG_TYPE_CGROUP_SOCKOPT Tracing (BTF/BPF trampoline) 5.5 f1b9509c2fb0 BPF_PROG_TYPE_TRACING struct ops 5.6 27ae7997a661 BPF_PROG_TYPE_STRUCT_OPS extensions 5.6 be8704ff07d2 BPF_PROG_TYPE_EXT LSM 5.7 fc611f47f218 BPF_PROG_TYPE_LSM lookup listening socket 5.9 e9ddbb7707ff BPF_PROG_TYPE_SK_LOOKUP Allow executing syscalls 5.15 79a7f8bdb159 BPF_PROG_TYPE_SYSCALL","breadcrumbs":"BPF Features by Linux Kernel Version » Program types","id":"127","title":"Program types"},"128":{"body":"","breadcrumbs":"BPF Features by Linux Kernel Version » Maps ( a.k.a. Tables, in BCC lingo)","id":"128","title":"Maps ( a.k.a. Tables, in BCC lingo)"},"129":{"body":"The list of map types supported in your kernel can be found in file include/uapi/linux/bpf.h : git grep -W 'bpf_map_type {' include/uapi/linux/bpf.h Map type Kernel version Commit Enum Hash 3.19 0f8e4bd8a1fc BPF_MAP_TYPE_HASH Array 3.19 28fbcfa08d8e BPF_MAP_TYPE_ARRAY Prog array 4.2 04fd61ab36ec BPF_MAP_TYPE_PROG_ARRAY Perf events 4.3 ea317b267e9d BPF_MAP_TYPE_PERF_EVENT_ARRAY Per-CPU hash 4.6 824bd0ce6c7c BPF_MAP_TYPE_PERCPU_HASH Per-CPU array 4.6 a10423b87a7e BPF_MAP_TYPE_PERCPU_ARRAY Stack trace 4.6 d5a3b1f69186 BPF_MAP_TYPE_STACK_TRACE cgroup array 4.8 4ed8ec521ed5 BPF_MAP_TYPE_CGROUP_ARRAY LRU hash 4.10 29ba732acbee 3a08c2fd7634 BPF_MAP_TYPE_LRU_HASH LRU per-CPU hash 4.10 8f8449384ec3 961578b63474 BPF_MAP_TYPE_LRU_PERCPU_HASH LPM trie (longest-prefix match) 4.11 b95a5c4db09b BPF_MAP_TYPE_LPM_TRIE Array of maps 4.12 56f668dfe00d BPF_MAP_TYPE_ARRAY_OF_MAPS Hash of maps 4.12 bcc6b1b7ebf8 BPF_MAP_TYPE_HASH_OF_MAPS Netdevice references (array) 4.14 546ac1ffb70d BPF_MAP_TYPE_DEVMAP Socket references (array) 4.14 174a79ff9515 BPF_MAP_TYPE_SOCKMAP CPU references 4.15 6710e1126934 BPF_MAP_TYPE_CPUMAP AF_XDP socket (XSK) references 4.18 fbfc504a24f5 BPF_MAP_TYPE_XSKMAP Socket references (hashmap) 4.18 81110384441a BPF_MAP_TYPE_SOCKHASH cgroup storage 4.19 de9cbbaadba5 BPF_MAP_TYPE_CGROUP_STORAGE reuseport sockarray 4.19 5dc4c4b7d4e8 BPF_MAP_TYPE_REUSEPORT_SOCKARRAY precpu cgroup storage 4.20 b741f1630346 BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE queue 4.20 f1a2e44a3aec BPF_MAP_TYPE_QUEUE stack 4.20 f1a2e44a3aec BPF_MAP_TYPE_STACK socket local storage 5.2 6ac99e8f23d4 BPF_MAP_TYPE_SK_STORAGE Netdevice references (hashmap) 5.4 6f9d451ab1a3 BPF_MAP_TYPE_DEVMAP_HASH struct ops 5.6 85d33df357b6 BPF_MAP_TYPE_STRUCT_OPS ring buffer 5.8 457f44363a88 BPF_MAP_TYPE_RINGBUF inode storage 5.10 8ea636848aca BPF_MAP_TYPE_INODE_STORAGE task storage 5.11 4cf1bc1f1045 BPF_MAP_TYPE_TASK_STORAGE Bloom filter 5.16 9330986c0300 BPF_MAP_TYPE_BLOOM_FILTER user ringbuf 6.1 583c1f420173 BPF_MAP_TYPE_USER_RINGBUF","breadcrumbs":"BPF Features by Linux Kernel Version » Map types","id":"129","title":"Map types"},"13":{"body":"在本篇博客中，我们将深入探讨eBPF（Extended Berkeley Packet Filter）的基本框架和开发流程。eBPF是一种在Linux内核上运行的强大网络和性能分析工具，它为开发者提供了在内核运行时动态加载、更新和运行用户定义代码的能力。这使得开发者可以实现高效、安全的内核级别的网络监控、性能分析和故障排查等功能。 本文是eBPF入门开发实践教程的第二篇，我们将重点关注如何编写一个简单的eBPF程序，并通过实际例子演示整个开发流程。在阅读本教程之前，建议您先学习第一篇教程，以便对eBPF的基本概念有个大致的了解。 在开发eBPF程序时，有多种开发框架可供选择，如 BCC（BPF Compiler Collection）libbpf、cilium/ebpf、eunomia-bpf 等。虽然不同工具的特点各异，但它们的基本开发流程大致相同。在接下来的内容中，我们将深入了解这些流程，并以 Hello World 程序为例，带领读者逐步掌握eBPF开发的基本技巧。 本教程将帮助您了解eBPF程序的基本结构、编译和加载过程、用户空间与内核空间的交互方式以及调试与优化技巧。通过学习本教程，您将掌握eBPF开发的基本知识，并为后续进一步学习和实践奠定坚实的基础。","breadcrumbs":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程 » eBPF 入门开发实践教程二：Hello World，基本框架和开发流程","id":"13","title":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程"},"130":{"body":"Some (but not all) of these API features translate to a subcommand beginning with BPF_MAP_. The list of subcommands supported in your kernel can be found in file include/uapi/linux/bpf.h : git grep -W 'bpf_cmd {' include/uapi/linux/bpf.h Feature Kernel version Commit Basic operations (lookup, update, delete, GET_NEXT_KEY) 3.18 db20fd2b0108 Pass flags to UPDATE_ELEM 3.19 3274f52073d8 Pre-alloc map memory by default 4.6 6c9059817432 Pass NULL to GET_NEXT_KEY 4.12 8fe45924387b Creation: select NUMA node 4.14 96eabe7a40aa Restrict access from syscall side 4.15 6e71b04a8224 Creation: specify map name 4.15 ad5b177bd73f LOOKUP_AND_DELETE_ELEM 4.20 bd513cd08f10 Creation: BPF_F_ZERO_SEED 5.0 96b3b6c9091d BPF_F_LOCK flag for lookup / update 5.1 96049f3afd50 Restrict access from BPF side 5.2 591fe9888d78 FREEZE 5.2 87df15de441b mmap() support for array maps 5.5 fc9702273e2e LOOKUP_BATCH 5.6 cb4d03ab499d UPDATE_BATCH, DELETE_BATCH 5.6 aa2e93b8e58e LOOKUP_AND_DELETE_BATCH 5.6 057996380a42 LOOKUP_AND_DELETE_ELEM support for hash maps 5.14 3e87f192b405","breadcrumbs":"BPF Features by Linux Kernel Version » Map userspace API","id":"130","title":"Map userspace API"},"131":{"body":"An approximate list of drivers or components supporting XDP programs for your kernel can be retrieved with: git grep -l XDP_SETUP_PROG drivers/ Feature / Driver Kernel version Commit XDP core architecture 4.8 6a773a15a1e8 Action: drop 4.8 6a773a15a1e8 Action: pass on to stack 4.8 6a773a15a1e8 Action: direct forwarding (on same port) 4.8 6ce96ca348a9 Direct packet data write 4.8 4acf6c0b84c9 Mellanox mlx4 driver 4.8 47a38e155037 Mellanox mlx5 driver 4.9 86994156c736 Netronome nfp driver 4.10 ecd63a0217d5 QLogic (Cavium) qed* drivers 4.10 496e05170958 virtio_net driver 4.10 f600b6905015 Broadcom bnxt_en driver 4.11 c6d30e8391b8 Intel ixgbe* drivers 4.12 924708081629 Cavium thunderx driver 4.12 05c773f52b96 Generic XDP 4.12 b5cdae3291f7 Intel i40e driver 4.13 0c8493d90b6b Action: redirect 4.14 6453073987ba Support for tap 4.14 761876c857cb Support for veth 4.14 d445516966dc Intel ixgbevf driver 4.17 c7aec59657b6 Freescale dpaa2 driver 5.0 7e273a8ebdd3 Socionext netsec driver 5.3 ba2b232108d3 TI cpsw driver 5.3 9ed4050c0d75 Intel ice driver 5.5 efc2214b6047 Solarflare sfc driver 5.5 eb9a36be7f3e Marvell mvneta driver 5.5 0db51da7a8e9 Microsoft hv_netvsc driver 5.6 351e1581395f Amazon ena driver 5.6 838c93dc5449 xen-netfront driver 5.9 6c5aa6fc4def Intel igb driver 5.10 9cbc948b5a20","breadcrumbs":"BPF Features by Linux Kernel Version » XDP","id":"131","title":"XDP"},"132":{"body":"The list of helpers supported in your kernel can be found in file include/uapi/linux/bpf.h : git grep '\tFN(' include/uapi/linux/bpf.h Alphabetical order Helper Kernel version License Commit BPF_FUNC_bind() 4.17 d74bad4e74ee BPF_FUNC_bprm_opts_set() 5.11 3f6719c7b62f BPF_FUNC_btf_find_by_name_kind() 5.14 3d78417b60fb BPF_FUNC_cgrp_storage_delete() 6.2 c4bcfb38a95e BPF_FUNC_cgrp_storage_get() 6.2 c4bcfb38a95e BPF_FUNC_check_mtu() 5.12 34b2021cc616 BPF_FUNC_clone_redirect() 4.2 3896d655f4d4 BPF_FUNC_copy_from_user() 5.10 07be4c4a3e7a BPF_FUNC_copy_from_user_task() 5.18 GPL 376040e47334 BPF_FUNC_csum_diff() 4.6 7d672345ed29 BPF_FUNC_csum_level() 5.7 7cdec54f9713 BPF_FUNC_csum_update() 4.9 36bbef52c7eb BPF_FUNC_current_task_under_cgroup() 4.9 60d20f9195b2 BPF_FUNC_d_path() 5.10 6e22ab9da793 BPF_FUNC_dynptr_data() 5.19 34d4ef5775f7 BPF_FUNC_dynptr_from_mem() 5.19 263ae152e962 BPF_FUNC_dynptr_read() 5.19 13bbbfbea759 BPF_FUNC_dynptr_write() 5.19 13bbbfbea759 BPF_FUNC_fib_lookup() 4.18 GPL 87f5fc7e48dd BPF_FUNC_find_vma() 5.17 7c7e3d31e785 BPF_FUNC_for_each_map_elem() 5.13 69c087ba6225 BPF_FUNC_get_attach_cookie() 5.15 7adfc6c9b315 BPF_FUNC_get_branch_snapshot() 5.16 GPL 856c02dbce4f BPF_FUNC_get_current_ancestor_cgroup_id() 5.6 b4490c5c4e02 BPF_FUNC_get_cgroup_classid() 4.3 8d20aabe1c76 BPF_FUNC_get_current_cgroup_id() 4.18 bf6fa2c893c5 BPF_FUNC_get_current_comm() 4.2 ffeedafbf023 BPF_FUNC_get_current_pid_tgid() 4.2 ffeedafbf023 BPF_FUNC_get_current_task() 4.8 GPL 606274c5abd8 BPF_FUNC_get_current_task_btf() 5.11 GPL 3ca1032ab7ab BPF_FUNC_get_current_uid_gid() 4.2 ffeedafbf023 BPF_FUNC_get_func_arg() 5.17 f92c1e183604 BPF_FUNC_get_func_arg_cnt() 5.17 f92c1e183604 BPF_FUNC_get_func_ip() 5.15 5d8b583d04ae BPF_FUNC_get_func_ret() 5.17 f92c1e183604 BPF_FUNC_get_retval() 5.18 b44123b4a3dc BPF_FUNC_get_hash_recalc() 4.8 13c5c240f789 BPF_FUNC_get_listener_sock() 5.1 dbafd7ddd623 BPF_FUNC_get_local_storage() 4.19 cd3394317653 BPF_FUNC_get_netns_cookie() 5.7 f318903c0bf4 BPF_FUNC_get_ns_current_pid_tgid() 5.7 b4490c5c4e02 BPF_FUNC_get_numa_node_id() 4.10 2d0e30c30f84 BPF_FUNC_get_prandom_u32() 4.1 03e69b508b6f BPF_FUNC_get_route_realm() 4.4 c46646d0484f BPF_FUNC_get_smp_processor_id() 4.1 c04167ce2ca0 BPF_FUNC_get_socket_cookie() 4.12 91b8270f2a4d BPF_FUNC_get_socket_uid() 4.12 6acc5c291068 BPF_FUNC_get_stack() 4.18 GPL de2ff05f48af BPF_FUNC_get_stackid() 4.6 GPL d5a3b1f69186 BPF_FUNC_get_task_stack() 5.9 fa28dcb82a38 BPF_FUNC_getsockopt() 4.15 cd86d1fd2102 BPF_FUNC_ima_file_hash() 5.18 174b16946e39 BPF_FUNC_ima_inode_hash() 5.11 27672f0d280a BPF_FUNC_inode_storage_delete() 5.10 8ea636848aca BPF_FUNC_inode_storage_get() 5.10 8ea636848aca BPF_FUNC_jiffies64() 5.5 5576b991e9c1 BPF_FUNC_kallsyms_lookup_name() 5.16 d6aef08a872b BPF_FUNC_kptr_xchg() 5.19 c0a5a21c25f3 BPF_FUNC_ktime_get_boot_ns() 5.8 71d19214776e BPF_FUNC_ktime_get_coarse_ns() 5.11 d05512618056 BPF_FUNC_ktime_get_ns() 4.1 d9847d310ab4 BPF_FUNC_ktime_get_tai_ns() 6.1 c8996c98f703 BPF_FUNC_l3_csum_replace() 4.1 91bc4822c3d6 BPF_FUNC_l4_csum_replace() 4.1 91bc4822c3d6 BPF_FUNC_load_hdr_opt() 5.10 0813a841566f BPF_FUNC_loop() 5.17 e6f2dd0f8067 BPF_FUNC_lwt_push_encap() 4.18 fe94cc290f53 BPF_FUNC_lwt_seg6_action() 4.18 fe94cc290f53 BPF_FUNC_lwt_seg6_adjust_srh() 4.18 fe94cc290f53 BPF_FUNC_lwt_seg6_store_bytes() 4.18 fe94cc290f53 BPF_FUNC_map_delete_elem() 3.19 d0003ec01c66 BPF_FUNC_map_lookup_elem() 3.19 d0003ec01c66 BPF_FUNC_map_lookup_percpu_elem() 5.19 07343110b293 BPF_FUNC_map_peek_elem() 4.20 f1a2e44a3aec BPF_FUNC_map_pop_elem() 4.20 f1a2e44a3aec BPF_FUNC_map_push_elem() 4.20 f1a2e44a3aec BPF_FUNC_map_update_elem() 3.19 d0003ec01c66 BPF_FUNC_msg_apply_bytes() 4.17 2a100317c9eb BPF_FUNC_msg_cork_bytes() 4.17 91843d540a13 BPF_FUNC_msg_pop_data() 5.0 7246d8ed4dcc BPF_FUNC_msg_pull_data() 4.17 015632bb30da BPF_FUNC_msg_push_data() 4.20 6fff607e2f14 BPF_FUNC_msg_redirect_hash() 4.18 81110384441a BPF_FUNC_msg_redirect_map() 4.17 4f738adba30a BPF_FUNC_per_cpu_ptr() 5.10 eaa6bcb71ef6 BPF_FUNC_perf_event_output() 4.4 GPL a43eec304259 BPF_FUNC_perf_event_read() 4.3 GPL 35578d798400 BPF_FUNC_perf_event_read_value() 4.15 GPL 908432ca84fc BPF_FUNC_perf_prog_read_value() 4.15 GPL 4bebdc7a85aa BPF_FUNC_probe_read() 4.1 GPL 2541517c32be BPF_FUNC_probe_read_kernel() 5.5 GPL 6ae08ae3dea2 BPF_FUNC_probe_read_kernel_str() 5.5 GPL 6ae08ae3dea2 BPF_FUNC_probe_read_user() 5.5 GPL 6ae08ae3dea2 BPF_FUNC_probe_read_user_str() 5.5 GPL 6ae08ae3dea2 BPF_FUNC_probe_read_str() 4.11 GPL a5e8c07059d0 BPF_FUNC_probe_write_user() 4.8 GPL 96ae52279594 BPF_FUNC_rc_keydown() 4.18 GPL f4364dcfc86d BPF_FUNC_rc_pointer_rel() 5.0 GPL 01d3240a04f4 BPF_FUNC_rc_repeat() 4.18 GPL f4364dcfc86d BPF_FUNC_read_branch_records() 5.6 GPL fff7b64355ea BPF_FUNC_redirect() 4.4 27b29f63058d BPF_FUNC_redirect_map() 4.14 97f91a7cf04f BPF_FUNC_redirect_neigh() 5.10 b4ab31414970 BPF_FUNC_redirect_peer() 5.10 9aa1206e8f48 BPF_FUNC_reserve_hdr_opt() 5.10 0813a841566f BPF_FUNC_ringbuf_discard() 5.8 457f44363a88 BPF_FUNC_ringbuf_discard_dynptr() 5.19 bc34dee65a65 BPF_FUNC_ringbuf_output() 5.8 457f44363a88 BPF_FUNC_ringbuf_query() 5.8 457f44363a88 BPF_FUNC_ringbuf_reserve() 5.8 457f44363a88 BPF_FUNC_ringbuf_reserve_dynptr() 5.19 bc34dee65a65 BPF_FUNC_ringbuf_submit() 5.8 457f44363a88 BPF_FUNC_ringbuf_submit_dynptr() 5.19 bc34dee65a65 BPF_FUNC_send_signal() 5.3 8b401f9ed244 BPF_FUNC_send_signal_thread() 5.5 8482941f0906 BPF_FUNC_seq_printf() 5.7 GPL 492e639f0c22 BPF_FUNC_seq_printf_btf() 5.10 eb411377aed9 BPF_FUNC_seq_write() 5.7 GPL 492e639f0c22 BPF_FUNC_set_hash() 4.13 ded092cd73c2 BPF_FUNC_set_hash_invalid() 4.9 7a4b28c6cc9f BPF_FUNC_set_retval() 5.18 b44123b4a3dc BPF_FUNC_setsockopt() 4.13 8c4b4c7e9ff0 BPF_FUNC_sk_ancestor_cgroup_id() 5.7 f307fa2cb4c9 BPF_FUNC_sk_assign() 5.6 cf7fbe660f2d BPF_FUNC_sk_cgroup_id() 5.7 f307fa2cb4c9 BPF_FUNC_sk_fullsock() 5.1 46f8bc92758c BPF_FUNC_sk_lookup_tcp() 4.20 6acc9b432e67 BPF_FUNC_sk_lookup_udp() 4.20 6acc9b432e67 BPF_FUNC_sk_redirect_hash() 4.18 81110384441a BPF_FUNC_sk_redirect_map() 4.14 174a79ff9515 BPF_FUNC_sk_release() 4.20 6acc9b432e67 BPF_FUNC_sk_select_reuseport() 4.19 2dbb9b9e6df6 BPF_FUNC_sk_storage_delete() 5.2 6ac99e8f23d4 BPF_FUNC_sk_storage_get() 5.2 6ac99e8f23d4 BPF_FUNC_skb_adjust_room() 4.13 2be7e212d541 BPF_FUNC_skb_ancestor_cgroup_id() 4.19 7723628101aa BPF_FUNC_skb_change_head() 4.10 3a0af8fd61f9 BPF_FUNC_skb_change_proto() 4.8 6578171a7ff0 BPF_FUNC_skb_change_tail() 4.9 5293efe62df8 BPF_FUNC_skb_change_type() 4.8 d2485c4242a8 BPF_FUNC_skb_cgroup_classid() 5.10 b426ce83baa7 BPF_FUNC_skb_cgroup_id() 4.18 cb20b08ead40 BPF_FUNC_skb_ecn_set_ce() 5.1 f7c917ba11a6 BPF_FUNC_skb_get_tunnel_key() 4.3 d3aa45ce6b94 BPF_FUNC_skb_get_tunnel_opt() 4.6 14ca0751c96f BPF_FUNC_skb_get_xfrm_state() 4.18 12bed760a78d BPF_FUNC_skb_load_bytes() 4.5 05c74e5e53f6 BPF_FUNC_skb_load_bytes_relative() 4.18 4e1ec56cdc59 BPF_FUNC_skb_output() 5.5 a7658e1a4164 BPF_FUNC_skb_pull_data() 4.9 36bbef52c7eb BPF_FUNC_skb_set_tstamp() 5.18 9bb984f28d5b BPF_FUNC_skb_set_tunnel_key() 4.3 d3aa45ce6b94 BPF_FUNC_skb_set_tunnel_opt() 4.6 14ca0751c96f BPF_FUNC_skb_store_bytes() 4.1 91bc4822c3d6 BPF_FUNC_skb_under_cgroup() 4.8 4a482f34afcc BPF_FUNC_skb_vlan_pop() 4.3 4e10df9a60d9 BPF_FUNC_skb_vlan_push() 4.3 4e10df9a60d9 BPF_FUNC_skc_lookup_tcp() 5.2 edbf8c01de5a BPF_FUNC_skc_to_mctcp_sock() 5.19 3bc253c2e652 BPF_FUNC_skc_to_tcp_sock() 5.9 478cfbdf5f13 BPF_FUNC_skc_to_tcp_request_sock() 5.9 478cfbdf5f13 BPF_FUNC_skc_to_tcp_timewait_sock() 5.9 478cfbdf5f13 BPF_FUNC_skc_to_tcp6_sock() 5.9 af7ec1383361 BPF_FUNC_skc_to_udp6_sock() 5.9 0d4fad3e57df BPF_FUNC_skc_to_unix_sock() 5.16 9eeb3aa33ae0 BPF_FUNC_snprintf() 5.13 7b15523a989b BPF_FUNC_snprintf_btf() 5.10 c4d0bfb45068 BPF_FUNC_sock_from_file() 5.11 4f19cab76136 BPF_FUNC_sock_hash_update() 4.18 81110384441a BPF_FUNC_sock_map_update() 4.14 174a79ff9515 BPF_FUNC_spin_lock() 5.1 d83525ca62cf BPF_FUNC_spin_unlock() 5.1 d83525ca62cf BPF_FUNC_store_hdr_opt() 5.10 0813a841566f BPF_FUNC_strncmp() 5.17 c5fb19937455 BPF_FUNC_strtol() 5.2 d7a4cb9b6705 BPF_FUNC_strtoul() 5.2 d7a4cb9b6705 BPF_FUNC_sys_bpf() 5.14 79a7f8bdb159 BPF_FUNC_sys_close() 5.14 3abea089246f BPF_FUNC_sysctl_get_current_value() 5.2 1d11b3016cec BPF_FUNC_sysctl_get_name() 5.2 808649fb787d BPF_FUNC_sysctl_get_new_value() 5.2 4e63acdff864 BPF_FUNC_sysctl_set_new_value() 5.2 4e63acdff864 BPF_FUNC_tail_call() 4.2 04fd61ab36ec BPF_FUNC_task_pt_regs() 5.15 GPL dd6e10fbd9f BPF_FUNC_task_storage_delete() 5.11 4cf1bc1f1045 BPF_FUNC_task_storage_get() 5.11 4cf1bc1f1045 BPF_FUNC_tcp_check_syncookie() 5.2 399040847084 BPF_FUNC_tcp_gen_syncookie() 5.3 70d66244317e BPF_FUNC_tcp_raw_check_syncookie_ipv4() 6.0 33bf9885040c BPF_FUNC_tcp_raw_check_syncookie_ipv6() 6.0 33bf9885040c BPF_FUNC_tcp_raw_gen_syncookie_ipv4() 6.0 33bf9885040c BPF_FUNC_tcp_raw_gen_syncookie_ipv6() 6.0 33bf9885040c BPF_FUNC_tcp_send_ack() 5.5 206057fe020a BPF_FUNC_tcp_sock() 5.1 655a51e536c0 BPF_FUNC_this_cpu_ptr() 5.10 63d9b80dcf2c BPF_FUNC_timer_init() 5.15 b00628b1c7d5 BPF_FUNC_timer_set_callback() 5.15 b00628b1c7d5 BPF_FUNC_timer_start() 5.15 b00628b1c7d5 BPF_FUNC_timer_cancel() 5.15 b00628b1c7d5 BPF_FUNC_trace_printk() 4.1 GPL 9c959c863f82 BPF_FUNC_trace_vprintk() 5.16 GPL 10aceb629e19 BPF_FUNC_user_ringbuf_drain() 6.1 205715673844 BPF_FUNC_xdp_adjust_head() 4.10 17bedab27231 BPF_FUNC_xdp_adjust_meta() 4.15 de8f3a83b0a0 BPF_FUNC_xdp_adjust_tail() 4.18 b32cc5b9a346 BPF_FUNC_xdp_get_buff_len() 5.18 0165cc817075 BPF_FUNC_xdp_load_bytes() 5.18 3f364222d032 BPF_FUNC_xdp_store_bytes() 5.18 3f364222d032 BPF_FUNC_xdp_output() 5.6 GPL d831ee84bfc9 BPF_FUNC_override_return() 4.16 GPL 9802d86585db BPF_FUNC_sock_ops_cb_flags_set() 4.16 b13d88072172 Note: GPL-only BPF helpers require a GPL-compatible license. The current licenses considered GPL-compatible by the kernel are: GPL GPL v2 GPL and additional rights Dual BSD/GPL Dual MIT/GPL Dual MPL/GPL Check the list of GPL-compatible licenses in your kernel source code .","breadcrumbs":"BPF Features by Linux Kernel Version » Helpers","id":"132","title":"Helpers"},"133":{"body":"The list of program types and supported helper functions can be retrieved with: git grep -W 'func_proto(enum bpf_func_id func_id' kernel/ net/ drivers/ Program Type Helper Functions BPF_PROG_TYPE_SOCKET_FILTER BPF_FUNC_skb_load_bytes() BPF_FUNC_skb_load_bytes_relative() BPF_FUNC_get_socket_cookie() BPF_FUNC_get_socket_uid() BPF_FUNC_perf_event_output() Base functions BPF_PROG_TYPE_KPROBE BPF_FUNC_perf_event_output() BPF_FUNC_get_stackid() BPF_FUNC_get_stack() BPF_FUNC_perf_event_read_value() BPF_FUNC_override_return() Tracing functions BPF_PROG_TYPE_SCHED_CLS BPF_PROG_TYPE_SCHED_ACT BPF_FUNC_skb_store_bytes() BPF_FUNC_skb_load_bytes() BPF_FUNC_skb_load_bytes_relative() BPF_FUNC_skb_pull_data() BPF_FUNC_csum_diff() BPF_FUNC_csum_update() BPF_FUNC_l3_csum_replace() BPF_FUNC_l4_csum_replace() BPF_FUNC_clone_redirect() BPF_FUNC_get_cgroup_classid() BPF_FUNC_skb_vlan_push() BPF_FUNC_skb_vlan_pop() BPF_FUNC_skb_change_proto() BPF_FUNC_skb_change_type() BPF_FUNC_skb_adjust_room() BPF_FUNC_skb_change_tail() BPF_FUNC_skb_get_tunnel_key() BPF_FUNC_skb_set_tunnel_key() BPF_FUNC_skb_get_tunnel_opt() BPF_FUNC_skb_set_tunnel_opt() BPF_FUNC_redirect() BPF_FUNC_get_route_realm() BPF_FUNC_get_hash_recalc() BPF_FUNC_set_hash_invalid() BPF_FUNC_set_hash() BPF_FUNC_perf_event_output() BPF_FUNC_get_smp_processor_id() BPF_FUNC_skb_under_cgroup() BPF_FUNC_get_socket_cookie() BPF_FUNC_get_socket_uid() BPF_FUNC_fib_lookup() BPF_FUNC_skb_get_xfrm_state() BPF_FUNC_skb_cgroup_id() Base functions BPF_PROG_TYPE_TRACEPOINT BPF_FUNC_perf_event_output() BPF_FUNC_get_stackid() BPF_FUNC_get_stack() BPF_FUNC_d_path() Tracing functions BPF_PROG_TYPE_XDP BPF_FUNC_perf_event_output() BPF_FUNC_get_smp_processor_id() BPF_FUNC_csum_diff() BPF_FUNC_xdp_adjust_head() BPF_FUNC_xdp_adjust_meta() BPF_FUNC_redirect() BPF_FUNC_redirect_map() BPF_FUNC_xdp_adjust_tail() BPF_FUNC_fib_lookup() Base functions BPF_PROG_TYPE_PERF_EVENT BPF_FUNC_perf_event_output() BPF_FUNC_get_stackid() BPF_FUNC_get_stack() BPF_FUNC_perf_prog_read_value() Tracing functions BPF_PROG_TYPE_CGROUP_SKB BPF_FUNC_skb_load_bytes() BPF_FUNC_skb_load_bytes_relative() BPF_FUNC_get_socket_cookie() BPF_FUNC_get_socket_uid() Base functions BPF_PROG_TYPE_CGROUP_SOCK BPF_FUNC_get_current_uid_gid() Base functions BPF_PROG_TYPE_LWT_IN BPF_FUNC_lwt_push_encap() LWT functions Base functions BPF_PROG_TYPE_LWT_OUT LWT functions Base functions BPF_PROG_TYPE_LWT_XMIT BPF_FUNC_skb_get_tunnel_key() BPF_FUNC_skb_set_tunnel_key() BPF_FUNC_skb_get_tunnel_opt() BPF_FUNC_skb_set_tunnel_opt() BPF_FUNC_redirect() BPF_FUNC_clone_redirect() BPF_FUNC_skb_change_tail() BPF_FUNC_skb_change_head() BPF_FUNC_skb_store_bytes() BPF_FUNC_csum_update() BPF_FUNC_l3_csum_replace() BPF_FUNC_l4_csum_replace() BPF_FUNC_set_hash_invalid() LWT functions BPF_PROG_TYPE_SOCK_OPS BPF_FUNC_setsockopt() BPF_FUNC_getsockopt() BPF_FUNC_sock_ops_cb_flags_set() BPF_FUNC_sock_map_update() BPF_FUNC_sock_hash_update() BPF_FUNC_get_socket_cookie() Base functions BPF_PROG_TYPE_SK_SKB BPF_FUNC_skb_store_bytes() BPF_FUNC_skb_load_bytes() BPF_FUNC_skb_pull_data() BPF_FUNC_skb_change_tail() BPF_FUNC_skb_change_head() BPF_FUNC_get_socket_cookie() BPF_FUNC_get_socket_uid() BPF_FUNC_sk_redirect_map() BPF_FUNC_sk_redirect_hash() BPF_FUNC_sk_lookup_tcp() BPF_FUNC_sk_lookup_udp() BPF_FUNC_sk_release() Base functions BPF_PROG_TYPE_CGROUP_DEVICE BPF_FUNC_map_lookup_elem() BPF_FUNC_map_update_elem() BPF_FUNC_map_delete_elem() BPF_FUNC_get_current_uid_gid() BPF_FUNC_trace_printk() BPF_PROG_TYPE_SK_MSG BPF_FUNC_msg_redirect_map() BPF_FUNC_msg_redirect_hash() BPF_FUNC_msg_apply_bytes() BPF_FUNC_msg_cork_bytes() BPF_FUNC_msg_pull_data() BPF_FUNC_msg_push_data() BPF_FUNC_msg_pop_data() Base functions BPF_PROG_TYPE_RAW_TRACEPOINT BPF_FUNC_perf_event_output() BPF_FUNC_get_stackid() BPF_FUNC_get_stack() BPF_FUNC_skb_output() Tracing functions BPF_PROG_TYPE_CGROUP_SOCK_ADDR BPF_FUNC_get_current_uid_gid() BPF_FUNC_bind() BPF_FUNC_get_socket_cookie() Base functions BPF_PROG_TYPE_LWT_SEG6LOCAL BPF_FUNC_lwt_seg6_store_bytes() BPF_FUNC_lwt_seg6_action() BPF_FUNC_lwt_seg6_adjust_srh() LWT functions BPF_PROG_TYPE_LIRC_MODE2 BPF_FUNC_rc_repeat() BPF_FUNC_rc_keydown() BPF_FUNC_rc_pointer_rel() BPF_FUNC_map_lookup_elem() BPF_FUNC_map_update_elem() BPF_FUNC_map_delete_elem() BPF_FUNC_ktime_get_ns() BPF_FUNC_tail_call() BPF_FUNC_get_prandom_u32() BPF_FUNC_trace_printk() BPF_PROG_TYPE_SK_REUSEPORT BPF_FUNC_sk_select_reuseport() BPF_FUNC_skb_load_bytes() BPF_FUNC_load_bytes_relative() Base functions BPF_PROG_TYPE_FLOW_DISSECTOR BPF_FUNC_skb_load_bytes() Base functions Function Group Functions Base functions BPF_FUNC_map_lookup_elem() BPF_FUNC_map_update_elem() BPF_FUNC_map_delete_elem() BPF_FUNC_map_peek_elem() BPF_FUNC_map_pop_elem() BPF_FUNC_map_push_elem() BPF_FUNC_get_prandom_u32() BPF_FUNC_get_smp_processor_id() BPF_FUNC_get_numa_node_id() BPF_FUNC_tail_call() BPF_FUNC_ktime_get_boot_ns() BPF_FUNC_ktime_get_ns() BPF_FUNC_trace_printk() BPF_FUNC_spin_lock() BPF_FUNC_spin_unlock() Tracing functions BPF_FUNC_map_lookup_elem() BPF_FUNC_map_update_elem() BPF_FUNC_map_delete_elem() BPF_FUNC_probe_read() BPF_FUNC_ktime_get_boot_ns() BPF_FUNC_ktime_get_ns() BPF_FUNC_tail_call() BPF_FUNC_get_current_pid_tgid() BPF_FUNC_get_current_task() BPF_FUNC_get_current_uid_gid() BPF_FUNC_get_current_comm() BPF_FUNC_trace_printk() BPF_FUNC_get_smp_processor_id() BPF_FUNC_get_numa_node_id() BPF_FUNC_perf_event_read() BPF_FUNC_probe_write_user() BPF_FUNC_current_task_under_cgroup() BPF_FUNC_get_prandom_u32() BPF_FUNC_probe_read_str() BPF_FUNC_get_current_cgroup_id() BPF_FUNC_send_signal() BPF_FUNC_probe_read_kernel() BPF_FUNC_probe_read_kernel_str() BPF_FUNC_probe_read_user() BPF_FUNC_probe_read_user_str() BPF_FUNC_send_signal_thread() BPF_FUNC_get_ns_current_pid_tgid() BPF_FUNC_xdp_output() BPF_FUNC_get_task_stack() LWT functions BPF_FUNC_skb_load_bytes() BPF_FUNC_skb_pull_data() BPF_FUNC_csum_diff() BPF_FUNC_get_cgroup_classid() BPF_FUNC_get_route_realm() BPF_FUNC_get_hash_recalc() BPF_FUNC_perf_event_output() BPF_FUNC_get_smp_processor_id() BPF_FUNC_skb_under_cgroup()","breadcrumbs":"BPF Features by Linux Kernel Version » Program Types","id":"133","title":"Program Types"},"134":{"body":"","breadcrumbs":"Kernel Configuration for BPF Features » Kernel Configuration for BPF Features","id":"134","title":"Kernel Configuration for BPF Features"},"135":{"body":"Functionalities Kernel Configuration Description Basic CONFIG_BPF_SYSCALL Enable the bpf() system call CONFIG_BPF_JIT BPF programs are normally handled by a BPF interpreter. This option allows the kernel to generate native code when a program is loaded into the kernel. This will significantly speed-up processing of BPF programs CONFIG_HAVE_BPF_JIT Enable BPF Just In Time compiler CONFIG_HAVE_EBPF_JIT Extended BPF JIT (eBPF) CONFIG_HAVE_CBPF_JIT Classic BPF JIT (cBPF) CONFIG_MODULES Enable to build loadable kernel modules CONFIG_BPF BPF VM interpreter CONFIG_BPF_EVENTS Allow the user to attach BPF programs to kprobe, uprobe, and tracepoint events CONFIG_PERF_EVENTS Kernel performance events and counters CONFIG_HAVE_PERF_EVENTS Enable perf events CONFIG_PROFILING Enable the extended profiling support mechanisms used by profilers BTF CONFIG_DEBUG_INFO_BTF Generate deduplicated BTF type information from DWARF debug info CONFIG_PAHOLE_HAS_SPLIT_BTF Generate BTF for each selected kernel module CONFIG_DEBUG_INFO_BTF_MODULES Generate compact split BTF type information for kernel modules Security CONFIG_BPF_JIT_ALWAYS_ON Enable BPF JIT and removes BPF interpreter to avoid speculative execution CONFIG_BPF_UNPRIV_DEFAULT_OFF Disable unprivileged BPF by default by setting Cgroup CONFIG_CGROUP_BPF Support for BPF programs attached to cgroups Network CONFIG_BPFILTER BPF based packet filtering framework (BPFILTER) CONFIG_BPFILTER_UMH This builds bpfilter kernel module with embedded user mode helper CONFIG_NET_CLS_BPF BPF-based classifier - to classify packets based on programmable BPF (JIT'ed) filters as an alternative to ematches CONFIG_NET_ACT_BPF Execute BPF code on packets. The BPF code will decide if the packet should be dropped or not CONFIG_BPF_STREAM_PARSER Enable this to allow a TCP stream parser to be used with BPF_MAP_TYPE_SOCKMAP CONFIG_LWTUNNEL_BPF Allow to run BPF programs as a nexthop action following a route lookup for incoming and outgoing packets CONFIG_NETFILTER_XT_MATCH_BPF BPF matching applies a linux socket filter to each packet and accepts those for which the filter returns non-zero CONFIG_IPV6_SEG6_BPF To support BPF seg6local hook. bpf: Add IPv6 Segment Routing helpersy. Reference kprobes CONFIG_KPROBE_EVENTS This allows the user to add tracing events (similar to tracepoints) on the fly via the ftrace interface CONFIG_KPROBES Enable kprobes-based dynamic events CONFIG_HAVE_KPROBES Check if krpobes enabled CONFIG_HAVE_REGS_AND_STACK_ACCESS_API This symbol should be selected by an architecture if it supports the API needed to access registers and stack entries from pt_regs. For example the kprobes-based event tracer needs this API. CONFIG_KPROBES_ON_FTRACE Have kprobes on function tracer if arch supports full passing of pt_regs to function tracing kprobe multi CONFIG_FPROBE Enable fprobe to attach the probe on multiple functions at once kprobe override CONFIG_BPF_KPROBE_OVERRIDE Enable BPF programs to override a kprobed function uprobes CONFIG_UPROBE_EVENTS Enable uprobes-based dynamic events CONFIG_ARCH_SUPPORTS_UPROBES Arch specific uprobes support CONFIG_UPROBES Uprobes is the user-space counterpart to kprobes: they enable instrumentation applications (such as 'perf probe') to establish unintrusive probes in user-space binaries and libraries, by executing handler functions when the probes are hit by user-space applications. CONFIG_MMU MMU-based virtualised addressing space support by paged memory management Tracepoints CONFIG_TRACEPOINTS Enable inserting tracepoints in the kernel and connect to proble functions CONFIG_HAVE_SYSCALL_TRACEPOINTS Enable syscall enter/exit tracing Raw Tracepoints Same as Tracepoints LSM CONFIG_BPF_LSM Enable instrumentation of the security hooks with BPF programs for implementing dynamic MAC and Audit Policies LIRC CONFIG_BPF_LIRC_MODE2 Allow attaching BPF programs to a lirc device","breadcrumbs":"Kernel Configuration for BPF Features » BPF Related Kernel Configurations","id":"135","title":"BPF Related Kernel Configurations"},"136":{"body":"Intended for search (Ctrl-F) and reference. For tutorials, start with tutorial.md . This guide is incomplete. If something feels missing, check the bcc and kernel source. And if you confirm we're missing something, please send a pull request to fix it, and help out everyone.","breadcrumbs":"bcc Reference Guide » bcc Reference Guide","id":"136","title":"bcc Reference Guide"},"137":{"body":"BPF C Events & Arguments 1. kprobes 2. kretprobes 3. Tracepoints 4. uprobes 5. uretprobes 6. USDT probes 7. Raw Tracepoints 8. system call tracepoints 9. kfuncs 10. kretfuncs 11. lsm probes 12. bpf iterators Data 1. bpf_probe_read_kernel() 2. bpf_probe_read_kernel_str() 3. bpf_ktime_get_ns() 4. bpf_get_current_pid_tgid() 5. bpf_get_current_uid_gid() 6. bpf_get_current_comm() 7. bpf_get_current_task() 8. bpf_log2l() 9. bpf_get_prandom_u32() 10. bpf_probe_read_user() 11. bpf_probe_read_user_str() 12. bpf_get_ns_current_pid_tgid() Debugging 1. bpf_override_return() Output 1. bpf_trace_printk() 2. BPF_PERF_OUTPUT 3. perf_submit() 4. perf_submit_skb() 5. BPF_RINGBUF_OUTPUT 6. ringbuf_output() 7. ringbuf_reserve() 8. ringbuf_submit() 9. ringbuf_discard() Maps 1. BPF_TABLE 2. BPF_HASH 3. BPF_ARRAY 4. BPF_HISTOGRAM 5. BPF_STACK_TRACE 6. BPF_PERF_ARRAY 7. BPF_PERCPU_HASH 8. BPF_PERCPU_ARRAY 9. BPF_LPM_TRIE 10. BPF_PROG_ARRAY 11. BPF_DEVMAP 12. BPF_CPUMAP 13. BPF_XSKMAP 14. BPF_ARRAY_OF_MAPS 15. BPF_HASH_OF_MAPS 16. BPF_STACK 17. BPF_QUEUE 18. BPF_SOCKHASH 19. map.lookup() 20. map.lookup_or_try_init() 21. map.delete() 22. map.update() 23. map.insert() 24. map.increment() 25. map.get_stackid() 26. map.perf_read() 27. map.call() 28. map.redirect_map() 29. map.push() 30. map.pop() 31. map.peek() 32. map.sock_hash_update() 33. map.msg_redirect_hash() 34. map.sk_redirect_hash() Licensing Rewriter bcc Python Initialization 1. BPF 2. USDT Events 1. attach_kprobe() 2. attach_kretprobe() 3. attach_tracepoint() 4. attach_uprobe() 5. attach_uretprobe() 6. USDT.enable_probe() 7. attach_raw_tracepoint() 8. attach_raw_socket() 9. attach_xdp() 10. attach_func() 11. detach_func() 12. detach_kprobe() 13. detach_kretprobe() Debug Output 1. trace_print() 2. trace_fields() Output APIs 1. perf_buffer_poll() 2. ring_buffer_poll() 3. ring_buffer_consume() Map APIs 1. get_table() 2. open_perf_buffer() 3. items() 4. values() 5. clear() 6. items_lookup_and_delete_batch() 7. items_lookup_batch() 8. items_delete_batch() 9. items_update_batch() 10. print_log2_hist() 11. print_linear_hist() 12. open_ring_buffer() 13. push() 14. pop() 15. peek() Helpers 1. ksym() 2. ksymname() 3. sym() 4. num_open_kprobes() 5. get_syscall_fnname() BPF Errors 1. Invalid mem access 2. Cannot call GPL only function from proprietary program Environment Variables 1. kernel source directory 2. kernel version overriding","breadcrumbs":"bcc Reference Guide » Contents","id":"137","title":"Contents"},"138":{"body":"This section describes the C part of a bcc program.","breadcrumbs":"bcc Reference Guide » BPF C","id":"138","title":"BPF C"},"139":{"body":"","breadcrumbs":"bcc Reference Guide » Events & Arguments","id":"139","title":"Events & Arguments"},"14":{"body":"在开始编写eBPF程序之前，我们需要准备一个合适的开发环境，并了解eBPF程序的基本开发流程。本部分将详细介绍这些内容。","breadcrumbs":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程 » eBPF开发环境准备与基本开发流程","id":"14","title":"eBPF开发环境准备与基本开发流程"},"140":{"body":"Syntax: kprobe__ kernel_function_name kprobe__ is a special prefix that creates a kprobe (dynamic tracing of a kernel function call) for the kernel function name provided as the remainder. You can also use kprobes by declaring a normal C function, then using the Python BPF.attach_kprobe() (covered later) to associate it with a kernel function. Arguments are specified on the function declaration: kprobe__ kernel_function_name (struct pt_regs *ctx [, argument1 ...]) For example: int kprobe__tcp_v4_connect(struct pt_regs *ctx, struct sock *sk) { [...]\n} This instruments the tcp_v4_connect() kernel function using a kprobe, with the following arguments: struct pt_regs *ctx: Registers and BPF context. struct sock *sk: First argument to tcp_v4_connect(). The first argument is always struct pt_regs *, the remainder are the arguments to the function (they don't need to be specified, if you don't intend to use them). Examples in situ: code ( output ), code ( output )","breadcrumbs":"bcc Reference Guide » 1. kprobes","id":"140","title":"1. kprobes"},"141":{"body":"Syntax: kretprobe__ kernel_function_name kretprobe__ is a special prefix that creates a kretprobe (dynamic tracing of a kernel function return) for the kernel function name provided as the remainder. You can also use kretprobes by declaring a normal C function, then using the Python BPF.attach_kretprobe() (covered later) to associate it with a kernel function. Return value is available as PT_REGS_RC(ctx), given a function declaration of: kretprobe__ kernel_function_name (struct pt_regs *ctx) For example: int kretprobe__tcp_v4_connect(struct pt_regs *ctx)\n{ int ret = PT_REGS_RC(ctx); [...]\n} This instruments the return of the tcp_v4_connect() kernel function using a kretprobe, and stores the return value in ret. Examples in situ: code ( output )","breadcrumbs":"bcc Reference Guide » 2. kretprobes","id":"141","title":"2. kretprobes"},"142":{"body":"Syntax: TRACEPOINT_PROBE( category , event ) This is a macro that instruments the tracepoint defined by category : event . The tracepoint name is :. The probe function name is tracepoint____. Arguments are available in an args struct, which are the tracepoint arguments. One way to list these is to cat the relevant format file under /sys/kernel/debug/tracing/events/ category / event /format. The args struct can be used in place of ctx in each functions requiring a context as an argument. This includes notably perf_submit() . For example: TRACEPOINT_PROBE(random, urandom_read) { // args is from /sys/kernel/debug/tracing/events/random/urandom_read/format bpf_trace_printk(\"%d\\\\n\", args->got_bits); return 0;\n} This instruments the tracepoint random:urandom_read tracepoint, and prints the tracepoint argument got_bits. When using Python API, this probe is automatically attached to the right tracepoint target. For C++, this tracepoint probe can be attached by specifying the tracepoint target and function name explicitly: BPF::attach_tracepoint(\"random:urandom_read\", \"tracepoint__random__urandom_read\") Note the name of the probe function defined above is tracepoint__random__urandom_read. Examples in situ: code ( output ), search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 3. Tracepoints","id":"142","title":"3. Tracepoints"},"143":{"body":"These are instrumented by declaring a normal function in C, then associating it as a uprobe probe in Python via BPF.attach_uprobe() (covered later). Arguments can be examined using PT_REGS_PARM macros. For example: int count(struct pt_regs *ctx) { char buf[64]; bpf_probe_read_user(&buf, sizeof(buf), (void *)PT_REGS_PARM1(ctx)); bpf_trace_printk(\"%s %d\", buf, PT_REGS_PARM2(ctx)); return(0);\n} This reads the first argument as a string, and then prints it with the second argument as an integer. Examples in situ: code","breadcrumbs":"bcc Reference Guide » 4. uprobes","id":"143","title":"4. uprobes"},"144":{"body":"These are instrumented by declaring a normal function in C, then associating it as a uretprobe probe in Python via BPF.attach_uretprobe() (covered later). Return value is available as PT_REGS_RC(ctx), given a function declaration of: function_name (struct pt_regs *ctx) For example: BPF_HISTOGRAM(dist);\nint count(struct pt_regs *ctx) { dist.increment(PT_REGS_RC(ctx)); return 0;\n} This increments the bucket in the dist histogram that is indexed by the return value. Examples in situ: code ( output ), code ( output )","breadcrumbs":"bcc Reference Guide » 5. uretprobes","id":"144","title":"5. uretprobes"},"145":{"body":"These are User Statically-Defined Tracing (USDT) probes, which may be placed in some applications or libraries to provide a user-level equivalent of tracepoints. The primary BPF method provided for USDT support method is enable_probe(). USDT probes are instrumented by declaring a normal function in C, then associating it as a USDT probe in Python via USDT.enable_probe(). Arguments can be read via: bpf_usdt_readarg( index , ctx, &addr) For example: int do_trace(struct pt_regs *ctx) { uint64_t addr; char path[128]; bpf_usdt_readarg(6, ctx, &addr); bpf_probe_read_user(&path, sizeof(path), (void *)addr); bpf_trace_printk(\"path:%s\\\\n\", path); return 0;\n}; This reads the sixth USDT argument, and then pulls it in as a string to path. When initializing USDTs via the third argument of BPF::init in the C API, if any USDT fails to init, entire BPF::init will fail. If you're OK with some USDTs failing to init, use BPF::init_usdt before calling BPF::init. Examples in situ: code , search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 6. USDT probes","id":"145","title":"6. USDT probes"},"146":{"body":"Syntax: RAW_TRACEPOINT_PROBE( event ) This is a macro that instruments the raw tracepoint defined by event . The argument is a pointer to struct bpf_raw_tracepoint_args, which is defined in bpf.h . The struct field args contains all parameters of the raw tracepoint where you can found at linux tree include/trace/events directory. For example: RAW_TRACEPOINT_PROBE(sched_switch)\n{ // TP_PROTO(bool preempt, struct task_struct *prev, struct task_struct *next) struct task_struct *prev = (struct task_struct *)ctx->args[1]; struct task_struct *next= (struct task_struct *)ctx->args[2]; s32 prev_tgid, next_tgid; bpf_probe_read_kernel(&prev_tgid, sizeof(prev->tgid), &prev->tgid); bpf_probe_read_kernel(&next_tgid, sizeof(next->tgid), &next->tgid); bpf_trace_printk(\"%d -> %d\\\\n\", prev_tgid, next_tgid);\n} This instruments the sched:sched_switch tracepoint, and prints the prev and next tgid. Examples in situ: search /tools","breadcrumbs":"bcc Reference Guide » 7. Raw Tracepoints","id":"146","title":"7. Raw Tracepoints"},"147":{"body":"Syntax: syscall__SYSCALLNAME syscall__ is a special prefix that creates a kprobe for the system call name provided as the remainder. You can use it by declaring a normal C function, then using the Python BPF.get_syscall_fnname(SYSCALLNAME) and BPF.attach_kprobe() to associate it. Arguments are specified on the function declaration: syscall__SYSCALLNAME(struct pt_regs *ctx, [, argument1 ...]). For example: int syscall__execve(struct pt_regs *ctx, const char __user *filename, const char __user *const __user *__argv, const char __user *const __user *__envp)\n{ [...]\n} This instruments the execve system call. The first argument is always struct pt_regs *, the remainder are the arguments to the function (they don't need to be specified, if you don't intend to use them). Corresponding Python code: b = BPF(text=bpf_text)\nexecve_fnname = b.get_syscall_fnname(\"execve\")\nb.attach_kprobe(event=execve_fnname, fn_name=\"syscall__execve\") Examples in situ: code ( output )","breadcrumbs":"bcc Reference Guide » 8. system call tracepoints","id":"147","title":"8. system call tracepoints"},"148":{"body":"Syntax: KFUNC_PROBE( function , typeof(arg1) arg1, typeof(arg2) arge ...) This is a macro that instruments the kernel function via trampoline before the function is executed. It's defined by function name and the function arguments defined as argX . For example: KFUNC_PROBE(do_sys_open, int dfd, const char *filename, int flags, int mode)\n{ ... This instruments the do_sys_open kernel function and make its arguments accessible as standard argument values. Examples in situ: search /tools","breadcrumbs":"bcc Reference Guide » 9. kfuncs","id":"148","title":"9. kfuncs"},"149":{"body":"Syntax: KRETFUNC_PROBE( event , typeof(arg1) arg1, typeof(arg2) arge ..., int ret) This is a macro that instruments the kernel function via trampoline after the function is executed. It's defined by function name and the function arguments defined as argX . The last argument of the probe is the return value of the instrumented function. For example: KRETFUNC_PROBE(do_sys_open, int dfd, const char *filename, int flags, int mode, int ret)\n{ ... This instruments the do_sys_open kernel function and make its arguments accessible as standard argument values together with its return value. Examples in situ: search /tools","breadcrumbs":"bcc Reference Guide » 10. kretfuncs","id":"149","title":"10. kretfuncs"},"15":{"body":"要开发eBPF程序，您需要安装以下软件和工具： Linux 内核：由于eBPF是内核技术，因此您需要具备较新版本的Linux内核（推荐4.8及以上版本），以支持eBPF功能。 LLVM 和 Clang：这些工具用于编译eBPF程序。安装最新版本的LLVM和Clang可以确保您获得最佳的eBPF支持。 eBPF 程序主要由两部分构成：内核态部分和用户态部分。内核态部分包含 eBPF 程序的实际逻辑，用户态部分负责加载、运行和监控内核态程序。当您选择了合适的开发框架后，如 BCC（BPF Compiler Collection）、libbpf、cilium/ebpf或eunomia-bpf等，您可以开始进行用户态和内核态程序的开发。以 BCC 工具为例，我们将介绍 eBPF 程序的基本开发流程： 当您选择了合适的开发框架后，如BCC（BPF Compiler Collection）、libbpf、cilium/ebpf或eunomia-bpf等，您可以开始进行用户态和内核态程序的开发。以BCC工具为例，我们将介绍eBPF程序的基本开发流程： 安装BCC工具：根据您的Linux发行版，按照BCC官方文档的指南安装BCC工具和相关依赖。 编写eBPF程序（C语言）：使用C语言编写一个简单的eBPF程序，例如Hello World程序。该程序可以在内核空间执行并完成特定任务，如统计网络数据包数量。 编写用户态程序（Python或C等）：使用Python、C等语言编写用户态程序，用于加载、运行eBPF程序以及与之交互。在这个程序中，您需要使用BCC提供的API来加载和操作内核态的eBPF程序。 编译eBPF程序：使用BCC工具，将C语言编写的eBPF程序编译成内核可以执行的字节码。BCC会在运行时动态从源码编译eBPF程序。 加载并运行eBPF程序：在用户态程序中，使用BCC提供的API加载编译好的eBPF程序到内核空间，然后运行该程序。 与eBPF程序交互：用户态程序通过BCC提供的API与eBPF程序交互，实现数据收集、分析和展示等功能。例如，您可以使用BCC API读取eBPF程序中的map数据，以获取网络数据包统计信息。 卸载eBPF程序：当不再需要eBPF程序时，用户态程序应使用BCC API将其从内核空间卸载。 调试与优化：使用 bpftool 等工具进行eBPF程序的调试和优化，提高程序性能和稳定性。 通过以上流程，您可以使用BCC工具开发、编译、运行和调试eBPF程序。请注意，其他框架（如libbpf、cilium/ebpf和eunomia-bpf）的开发流程大致相似但略有不同，因此在选择框架时，请参考相应的官方文档和示例。 通过这个过程，你可以开发出一个能够在内核中运行的 eBPF 程序。eunomia-bpf 是一个开源的 eBPF 动态加载运行时和开发工具链，它的目的是简化 eBPF 程序的开发、构建、分发、运行。它基于 libbpf 的 CO-RE 轻量级开发框架，支持通过用户态 WASM 虚拟机控制 eBPF 程序的加载和执行，并将预编译的 eBPF 程序打包为通用的 JSON 或 WASM 模块进行分发。我们会使用 eunomia-bpf 进行演示。","breadcrumbs":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程 » 安装必要的软件和工具","id":"15","title":"安装必要的软件和工具"},"150":{"body":"Syntax: LSM_PROBE( hook , typeof(arg1) arg1, typeof(arg2) arg2 ...) This is a macro that instruments an LSM hook as a BPF program. It can be used to audit security events and implement MAC security policies in BPF. It is defined by specifying the hook name followed by its arguments. Hook names can be found in include/linux/security.h by taking functions like security_hookname and taking just the hookname part. For example, security_bpf would simply become bpf. Unlike other BPF program types, the return value specified in an LSM probe matters. A return value of 0 allows the hook to succeed, whereas any non-zero return value will cause the hook to fail and deny the security operation. The following example instruments a hook that denies all future BPF operations: LSM_PROBE(bpf, int cmd, union bpf_attr *attr, unsigned int size)\n{ return -EPERM;\n} This instruments the security_bpf hook and causes it to return -EPERM. Changing return -EPERM to return 0 would cause the BPF program to allow the operation instead. LSM probes require at least a 5.7+ kernel with the following configuation options set: CONFIG_BPF_LSM=y CONFIG_LSM comma separated string must contain \"bpf\" (for example, CONFIG_LSM=\"lockdown,yama,bpf\") Examples in situ: search /tests","breadcrumbs":"bcc Reference Guide » 11. LSM Probes","id":"150","title":"11. LSM Probes"},"151":{"body":"Syntax: BPF_ITER(target) This is a macro to define a program signature for a bpf iterator program. The argument target specifies what to iterate for the program. Currently, kernel does not have interface to discover what targets are supported. A good place to find what is supported is in tools/testing/selftests/bpf/prog_test/bpf_iter.c and some sample bpf iter programs are in tools/testing/selftests/bpf/progs with file name prefix bpf_iter . The following example defines a program for target task , which traverses all tasks in the kernel. BPF_ITER(task)\n{ struct seq_file *seq = ctx->meta->seq; struct task_struct *task = ctx->task; if (task == (void *)0) return 0; ... task->pid, task->tgid, task->comm, ... return 0;\n} BPF iterators are introduced in 5.8 kernel for task, task_file, bpf_map, netlink_sock and ipv6_route . In 5.9, support is added to tcp/udp sockets and bpf map element (hashmap, arraymap and sk_local_storage_map) traversal.","breadcrumbs":"bcc Reference Guide » 12. BPF ITERATORS","id":"151","title":"12. BPF ITERATORS"},"152":{"body":"","breadcrumbs":"bcc Reference Guide » Data","id":"152","title":"Data"},"153":{"body":"Syntax: int bpf_probe_read_kernel(void *dst, int size, const void *src) Return: 0 on success This copies size bytes from kernel address space to the BPF stack, so that BPF can later operate on it. For safety, all kernel memory reads must pass through bpf_probe_read_kernel(). This happens automatically in some cases, such as dereferencing kernel variables, as bcc will rewrite the BPF program to include the necessary bpf_probe_read_kernel(). Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 1. bpf_probe_read_kernel()","id":"153","title":"1. bpf_probe_read_kernel()"},"154":{"body":"Syntax: int bpf_probe_read_kernel_str(void *dst, int size, const void *src) Return: > 0 length of the string including the trailing NULL on success < 0 error This copies a NULL terminated string from kernel address space to the BPF stack, so that BPF can later operate on it. In case the string length is smaller than size, the target is not padded with further NULL bytes. In case the string length is larger than size, just size - 1 bytes are copied and the last byte is set to NULL. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 2. bpf_probe_read_kernel_str()","id":"154","title":"2. bpf_probe_read_kernel_str()"},"155":{"body":"Syntax: u64 bpf_ktime_get_ns(void) Return: u64 number of nanoseconds. Starts at system boot time but stops during suspend. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 3. bpf_ktime_get_ns()","id":"155","title":"3. bpf_ktime_get_ns()"},"156":{"body":"Syntax: u64 bpf_get_current_pid_tgid(void) Return: current->tgid << 32 | current->pid Returns the process ID in the lower 32 bits (kernel's view of the PID, which in user space is usually presented as the thread ID), and the thread group ID in the upper 32 bits (what user space often thinks of as the PID). By directly setting this to a u32, we discard the upper 32 bits. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 4. bpf_get_current_pid_tgid()","id":"156","title":"4. bpf_get_current_pid_tgid()"},"157":{"body":"Syntax: u64 bpf_get_current_uid_gid(void) Return: current_gid << 32 | current_uid Returns the user ID and group IDs. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 5. bpf_get_current_uid_gid()","id":"157","title":"5. bpf_get_current_uid_gid()"},"158":{"body":"Syntax: bpf_get_current_comm(char *buf, int size_of_buf) Return: 0 on success Populates the first argument address with the current process name. It should be a pointer to a char array of at least size TASK_COMM_LEN, which is defined in linux/sched.h. For example: #include int do_trace(struct pt_regs *ctx) { char comm[TASK_COMM_LEN]; bpf_get_current_comm(&comm, sizeof(comm));\n[...] Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 6. bpf_get_current_comm()","id":"158","title":"6. bpf_get_current_comm()"},"159":{"body":"Syntax: bpf_get_current_task() Return: current task as a pointer to struct task_struct. Returns a pointer to the current task's task_struct object. This helper can be used to compute the on-CPU time for a process, identify kernel threads, get the current CPU's run queue, or retrieve many other pieces of information. With Linux 4.13, due to issues with field randomization, you may need two #define directives before the includes: #define randomized_struct_fields_start struct {\n#define randomized_struct_fields_end };\n#include int do_trace(void *ctx) { struct task_struct *t = (struct task_struct *)bpf_get_current_task();\n[...] Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 7. bpf_get_current_task()","id":"159","title":"7. bpf_get_current_task()"},"16":{"body":"可以通过以下步骤下载和安装 eunomia-bpf： 下载 ecli 工具，用于运行 eBPF 程序： $ wget https://aka.pw/bpf-ecli -O ecli && chmod +x ./ecli\n$ ./ecli -h\nUsage: ecli [--help] [--version] [--json] [--no-cache] url-and-args 下载编译器工具链，用于将 eBPF 内核代码编译为 config 文件或 WASM 模块： $ wget https://github.com/eunomia-bpf/eunomia-bpf/releases/latest/download/ecc && chmod +x ./ecc\n$ ./ecc -h\neunomia-bpf compiler\nUsage: ecc [OPTIONS] [EXPORT_EVENT_HEADER]\n.... 也可以使用 docker 镜像进行编译： $ docker run -it -v `pwd`/:/src/ yunwei37/ebpm:latest # 使用 docker 进行编译。`pwd` 应该包含 *.bpf.c 文件和 *.h 文件。\nexport PATH=PATH:~/.eunomia/bin\nCompiling bpf object...\nPacking ebpf object and config into /src/package.json...","breadcrumbs":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程 » 下载安装 eunomia-bpf 开发工具","id":"16","title":"下载安装 eunomia-bpf 开发工具"},"160":{"body":"Syntax: unsigned int bpf_log2l(unsigned long v) Returns the log-2 of the provided value. This is often used to create indexes for histograms, to construct power-of-2 histograms. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 8. bpf_log2l()","id":"160","title":"8. bpf_log2l()"},"161":{"body":"Syntax: u32 bpf_get_prandom_u32() Returns a pseudo-random u32. Example in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 9. bpf_get_prandom_u32()","id":"161","title":"9. bpf_get_prandom_u32()"},"162":{"body":"Syntax: int bpf_probe_read_user(void *dst, int size, const void *src) Return: 0 on success This attempts to safely read size bytes from user address space to the BPF stack, so that BPF can later operate on it. For safety, all user address space memory reads must pass through bpf_probe_read_user(). Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 10. bpf_probe_read_user()","id":"162","title":"10. bpf_probe_read_user()"},"163":{"body":"Syntax: int bpf_probe_read_user_str(void *dst, int size, const void *src) Return: > 0 length of the string including the trailing NULL on success < 0 error This copies a NULL terminated string from user address space to the BPF stack, so that BPF can later operate on it. In case the string length is smaller than size, the target is not padded with further NULL bytes. In case the string length is larger than size, just size - 1 bytes are copied and the last byte is set to NULL. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 11. bpf_probe_read_user_str()","id":"163","title":"11. bpf_probe_read_user_str()"},"164":{"body":"Syntax: u32 bpf_get_ns_current_pid_tgid(u64 dev, u64 ino, struct bpf_pidns_info* nsdata, u32 size) Values for pid and tgid as seen from the current namespace will be returned in nsdata . Return 0 on success, or one of the following in case of failure: -EINVAL if dev and inum supplied don't match dev_t and inode number with nsfs of current task, or if dev conversion to dev_t lost high bits. -ENOENT if pidns does not exists for the current task. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 12. bpf_get_ns_current_pid_tgid()","id":"164","title":"12. bpf_get_ns_current_pid_tgid()"},"165":{"body":"","breadcrumbs":"bcc Reference Guide » Debugging","id":"165","title":"Debugging"},"166":{"body":"Syntax: int bpf_override_return(struct pt_regs *, unsigned long rc) Return: 0 on success When used in a program attached to a function entry kprobe, causes the execution of the function to be skipped, immediately returning rc instead. This is used for targeted error injection. bpf_override_return will only work when the kprobed function is whitelisted to allow error injections. Whitelisting entails tagging a function with ALLOW_ERROR_INJECTION() in the kernel source tree; see io_ctl_init for an example. If the kprobed function is not whitelisted, the bpf program will fail to attach with ioctl(PERF_EVENT_IOC_SET_BPF): Invalid argument int kprobe__io_ctl_init(void *ctx) { bpf_override_return(ctx, -ENOMEM); return 0;\n}","breadcrumbs":"bcc Reference Guide » 1. bpf_override_return()","id":"166","title":"1. bpf_override_return()"},"167":{"body":"","breadcrumbs":"bcc Reference Guide » Output","id":"167","title":"Output"},"168":{"body":"Syntax: int bpf_trace_printk(const char *fmt, ...) Return: 0 on success A simple kernel facility for printf() to the common trace_pipe (/sys/kernel/debug/tracing/trace_pipe). This is ok for some quick examples, but has limitations: 3 args max, 1 %s only, and trace_pipe is globally shared, so concurrent programs will have clashing output. A better interface is via BPF_PERF_OUTPUT(). Note that calling this helper is made simpler than the original kernel version, which has fmt_size as the second parameter. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 1. bpf_trace_printk()","id":"168","title":"1. bpf_trace_printk()"},"169":{"body":"Syntax: BPF_PERF_OUTPUT(name) Creates a BPF table for pushing out custom event data to user space via a perf ring buffer. This is the preferred method for pushing per-event data to user space. For example: struct data_t { u32 pid; u64 ts; char comm[TASK_COMM_LEN];\n};\nBPF_PERF_OUTPUT(events); int hello(struct pt_regs *ctx) { struct data_t data = {}; data.pid = bpf_get_current_pid_tgid(); data.ts = bpf_ktime_get_ns(); bpf_get_current_comm(&data.comm, sizeof(data.comm)); events.perf_submit(ctx, &data, sizeof(data)); return 0;\n} The output table is named events, and data is pushed to it via events.perf_submit(). Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 2. BPF_PERF_OUTPUT","id":"169","title":"2. BPF_PERF_OUTPUT"},"17":{"body":"我们会先从一个简单的 eBPF 程序开始，它会在内核中打印一条消息。我们会使用 eunomia-bpf 的编译器工具链将其编译为 bpf 字节码文件，然后使用 ecli 工具加载并运行该程序。作为示例，我们可以暂时省略用户态程序的部分。 ```c\n/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */\n#define BPF_NO_GLOBAL_DATA\n#include \n#include \n#include typedef unsigned int u32;\ntypedef int pid_t;\nconst pid_t pid_filter = 0; char LICENSE[] SEC(\"license\") = \"Dual BSD/GPL\"; SEC(\"tp/syscalls/sys_enter_write\")\nint handle_tp(void *ctx)\n{ pid_t pid = bpf_get_current_pid_tgid() >> 32; if (pid_filter && pid != pid_filter) return 0; bpf_printk(\"BPF triggered from PID %d.\\n\", pid); return 0;\n} 这段程序通过定义一个 handle_tp 函数并使用 SEC 宏把它附加到 sys_enter_write tracepoint（即在进入 write 系统调用时执行）。该函数通过使用 bpf_get_current_pid_tgid 和 bpf_printk 函数获取调用 write 系统调用的进程 ID，并在内核日志中打印出来。 bpf_trace_printk()： 一种将信息输出到trace_pipe(/sys/kernel/debug/tracing/trace_pipe)简单机制。 在一些简单用例中这样使用没有问题， but它也有一些限制：最多3 参数； 第一个参数必须是%s(即字符串)；同时trace_pipe在内核中全局共享，其他并行使用trace_pipe的程序有可能会将 trace_pipe 的输出扰乱。 一个更好的方式是通过 BPF_PERF_OUTPUT(), 稍后将会讲到。 void *ctx：ctx本来是具体类型的参数， 但是由于我们这里没有使用这个参数，因此就将其写成void *类型。 return 0;：必须这样，返回0 (如果要知道why, 参考 #139 https://github.com/iovisor/bcc/issues/139 )。 要编译和运行这段程序，可以使用 ecc 工具和 ecli 命令。首先使用 ecc 编译程序： $ ecc minimal.bpf.c\nCompiling bpf object...\nPacking ebpf object and config into package.json... 或使用 docker 镜像进行编译： docker run -it -v `pwd`/:/src/ yunwei37/ebpm:latest 然后使用 ecli 运行编译后的程序： $ sudo ecli run ./package.json\nRuning eBPF program... 运行这段程序后，可以通过查看 /sys/kernel/debug/tracing/trace_pipe 文件来查看 eBPF 程序的输出： $ sudo cat /sys/kernel/debug/tracing/trace_pipe <...>-3840345 [010] d... 3220701.101143: bpf_trace_printk: write system call from PID 3840345. <...>-3840345 [010] d... 3220701.101143: bpf_trace_printk: write system call from PID 3840345.","breadcrumbs":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程 » Hello World - minimal eBPF program","id":"17","title":"Hello World - minimal eBPF program"},"170":{"body":"Syntax: int perf_submit((void *)ctx, (void *)data, u32 data_size) Return: 0 on success A method of a BPF_PERF_OUTPUT table, for submitting custom event data to user space. See the BPF_PERF_OUTPUT entry. (This ultimately calls bpf_perf_event_output().) The ctx parameter is provided in kprobes or kretprobes . For SCHED_CLS or SOCKET_FILTER programs, the struct __sk_buff *skb must be used instead. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 3. perf_submit()","id":"170","title":"3. perf_submit()"},"171":{"body":"Syntax: int perf_submit_skb((void *)ctx, u32 packet_size, (void *)data, u32 data_size) Return: 0 on success A method of a BPF_PERF_OUTPUT table available in networking program types, for submitting custom event data to user space, along with the first packet_size bytes of the packet buffer. See the BPF_PERF_OUTPUT entry. (This ultimately calls bpf_perf_event_output().) Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 4. perf_submit_skb()","id":"171","title":"4. perf_submit_skb()"},"172":{"body":"Syntax: BPF_RINGBUF_OUTPUT(name, page_cnt) Creates a BPF table for pushing out custom event data to user space via a ringbuf ring buffer. BPF_RINGBUF_OUTPUT has several advantages over BPF_PERF_OUTPUT, summarized as follows: Buffer is shared across all CPUs, meaning no per-CPU allocation Supports two APIs for BPF programs map.ringbuf_output() works like map.perf_submit() (covered in ringbuf_output ) map.ringbuf_reserve()/map.ringbuf_submit()/map.ringbuf_discard() split the process of reserving buffer space and submitting events into two steps (covered in ringbuf_reserve , ringbuf_submit , ringbuf_discard ) BPF APIs do not require access to a CPU ctx argument Superior performance and latency in userspace thanks to a shared ring buffer manager Supports two ways of consuming data in userspace Starting in Linux 5.8, this should be the preferred method for pushing per-event data to user space. Example of both APIs: struct data_t { u32 pid; u64 ts; char comm[TASK_COMM_LEN];\n}; // Creates a ringbuf called events with 8 pages of space, shared across all CPUs\nBPF_RINGBUF_OUTPUT(events, 8); int first_api_example(struct pt_regs *ctx) { struct data_t data = {}; data.pid = bpf_get_current_pid_tgid(); data.ts = bpf_ktime_get_ns(); bpf_get_current_comm(&data.comm, sizeof(data.comm)); events.ringbuf_output(&data, sizeof(data), 0 /* flags */); return 0;\n} int second_api_example(struct pt_regs *ctx) { struct data_t *data = events.ringbuf_reserve(sizeof(struct data_t)); if (!data) { // Failed to reserve space return 1; } data->pid = bpf_get_current_pid_tgid(); data->ts = bpf_ktime_get_ns(); bpf_get_current_comm(&data->comm, sizeof(data->comm)); events.ringbuf_submit(data, 0 /* flags */); return 0;\n} The output table is named events. Data is allocated via events.ringbuf_reserve() and pushed to it via events.ringbuf_submit(). Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 5. BPF_RINGBUF_OUTPUT","id":"172","title":"5. BPF_RINGBUF_OUTPUT"},"173":{"body":"Syntax: int ringbuf_output((void *)data, u64 data_size, u64 flags) Return: 0 on success Flags: BPF_RB_NO_WAKEUP: Do not sent notification of new data availability BPF_RB_FORCE_WAKEUP: Send notification of new data availability unconditionally A method of the BPF_RINGBUF_OUTPUT table, for submitting custom event data to user space. This method works like perf_submit(), although it does not require a ctx argument. Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 6. ringbuf_output()","id":"173","title":"6. ringbuf_output()"},"174":{"body":"Syntax: void* ringbuf_reserve(u64 data_size) Return: Pointer to data struct on success, NULL on failure A method of the BPF_RINGBUF_OUTPUT table, for reserving space in the ring buffer and simultaenously allocating a data struct for output. Must be used with one of ringbuf_submit or ringbuf_discard. Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 7. ringbuf_reserve()","id":"174","title":"7. ringbuf_reserve()"},"175":{"body":"Syntax: void ringbuf_submit((void *)data, u64 flags) Return: Nothing, always succeeds Flags: BPF_RB_NO_WAKEUP: Do not sent notification of new data availability BPF_RB_FORCE_WAKEUP: Send notification of new data availability unconditionally A method of the BPF_RINGBUF_OUTPUT table, for submitting custom event data to user space. Must be preceded by a call to ringbuf_reserve() to reserve space for the data. Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 8. ringbuf_submit()","id":"175","title":"8. ringbuf_submit()"},"176":{"body":"Syntax: void ringbuf_discard((void *)data, u64 flags) Return: Nothing, always succeeds Flags: BPF_RB_NO_WAKEUP: Do not sent notification of new data availability BPF_RB_FORCE_WAKEUP: Send notification of new data availability unconditionally A method of the BPF_RINGBUF_OUTPUT table, for discarding custom event data; userspace ignores the data associated with the discarded event. Must be preceded by a call to ringbuf_reserve() to reserve space for the data. Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 9. ringbuf_discard()","id":"176","title":"9. ringbuf_discard()"},"177":{"body":"Maps are BPF data stores, and are the basis for higher level object types including tables, hashes, and histograms.","breadcrumbs":"bcc Reference Guide » Maps","id":"177","title":"Maps"},"178":{"body":"Syntax: BPF_TABLE(_table_type, _key_type, _leaf_type, _name, _max_entries) Creates a map named _name. Most of the time this will be used via higher-level macros, like BPF_HASH, BPF_ARRAY, BPF_HISTOGRAM, etc. BPF_F_TABLE is a variant that takes a flag in the last parameter. BPF_TABLE(https://github.com/iovisor/bcc/tree/master.) is actually a wrapper to BPF_F_TABLE(https://github.com/iovisor/bcc/tree/master., 0 /* flag */). Methods (covered later): map.lookup(), map.lookup_or_try_init(), map.delete(), map.update(), map.insert(), map.increment(). Examples in situ: search /examples , search /tools Pinned Maps Syntax: BPF_TABLE_PINNED(_table_type, _key_type, _leaf_type, _name, _max_entries, \"/sys/fs/bpf/xyz\") Create a new map if it doesn't exist and pin it to the bpffs as a FILE, otherwise use the map that was pinned to the bpffs. The type information is not enforced and the actual map type depends on the map that got pinned to the location. For example: BPF_TABLE_PINNED(\"hash\", u64, u64, ids, 1024, \"/sys/fs/bpf/ids\");","breadcrumbs":"bcc Reference Guide » 1. BPF_TABLE","id":"178","title":"1. BPF_TABLE"},"179":{"body":"Syntax: BPF_HASH(name [, key_type [, leaf_type [, size]]]) Creates a hash map (associative array) named name, with optional parameters. Defaults: BPF_HASH(name, key_type=u64, leaf_type=u64, size=10240) For example: BPF_HASH(start, struct request *); This creates a hash named start where the key is a struct request *, and the value defaults to u64. This hash is used by the disksnoop.py example for saving timestamps for each I/O request, where the key is the pointer to struct request, and the value is the timestamp. This is a wrapper macro for BPF_TABLE(\"hash\", ...). Methods (covered later): map.lookup(), map.lookup_or_try_init(), map.delete(), map.update(), map.insert(), map.increment(). Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 2. BPF_HASH","id":"179","title":"2. BPF_HASH"},"18":{"body":"如上所述， eBPF 程序的基本框架包括： 包含头文件：需要包含 和 等头文件。 定义许可证：需要定义许可证，通常使用 \"Dual BSD/GPL\"。 定义 BPF 函数：需要定义一个 BPF 函数，例如其名称为 handle_tp，其参数为 void *ctx，返回值为 int。通常用 C 语言编写。 使用 BPF 助手函数：在例如 BPF 函数中，可以使用 BPF 助手函数 bpf_get_current_pid_tgid() 和 bpf_printk()。 返回值","breadcrumbs":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程 » eBPF 程序的基本框架","id":"18","title":"eBPF 程序的基本框架"},"180":{"body":"Syntax: BPF_ARRAY(name [, leaf_type [, size]]) Creates an int-indexed array which is optimized for fastest lookup and update, named name, with optional parameters. Defaults: BPF_ARRAY(name, leaf_type=u64, size=10240) For example: BPF_ARRAY(counts, u64, 32); This creates an array named counts where with 32 buckets and 64-bit integer values. This array is used by the funccount.py example for saving call count of each function. This is a wrapper macro for BPF_TABLE(\"array\", ...). Methods (covered later): map.lookup(), map.update(), map.increment(). Note that all array elements are pre-allocated with zero values and can not be deleted. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 3. BPF_ARRAY","id":"180","title":"3. BPF_ARRAY"},"181":{"body":"Syntax: BPF_HISTOGRAM(name [, key_type [, size ]]) Creates a histogram map named name, with optional parameters. Defaults: BPF_HISTOGRAM(name, key_type=int, size=64) For example: BPF_HISTOGRAM(dist); This creates a histogram named dist, which defaults to 64 buckets indexed by keys of type int. This is a wrapper macro for BPF_TABLE(\"histgram\", ...). Methods (covered later): map.increment(). Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 4. BPF_HISTOGRAM","id":"181","title":"4. BPF_HISTOGRAM"},"182":{"body":"Syntax: BPF_STACK_TRACE(name, max_entries) Creates stack trace map named name, with a maximum entry count provided. These maps are used to store stack traces. For example: BPF_STACK_TRACE(stack_traces, 1024); This creates stack trace map named stack_traces, with a maximum number of stack trace entries of 1024. This is a wrapper macro for BPF_TABLE(\"stacktrace\", ...). Methods (covered later): map.get_stackid(). Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 5. BPF_STACK_TRACE","id":"182","title":"5. BPF_STACK_TRACE"},"183":{"body":"Syntax: BPF_PERF_ARRAY(name, max_entries) Creates perf array named name, with a maximum entry count provided, which must be equal to the number of system cpus. These maps are used to fetch hardware performance counters. For example: text=\"\"\"\nBPF_PERF_ARRAY(cpu_cycles, NUM_CPUS);\n\"\"\"\nb = bcc.BPF(text=text, cflags=[\"-DNUM_CPUS=%d\" % multiprocessing.cpu_count()])\nb[\"cpu_cycles\"].open_perf_event(b[\"cpu_cycles\"].HW_CPU_CYCLES) This creates a perf array named cpu_cycles, with number of entries equal to the number of cpus/cores. The array is configured so that later calling map.perf_read() will return a hardware-calculated counter of the number of cycles elapsed from some point in the past. Only one type of hardware counter may be configured per table at a time. Methods (covered later): map.perf_read(). Examples in situ: search /tests","breadcrumbs":"bcc Reference Guide » 6. BPF_PERF_ARRAY","id":"183","title":"6. BPF_PERF_ARRAY"},"184":{"body":"Syntax: BPF_PERCPU_HASH(name [, key_type [, leaf_type [, size]]]) Creates NUM_CPU int-indexed hash maps (associative arrays) named name, with optional parameters. Each CPU will have a separate copy of this array. The copies are not kept synchronized in any way. Note that due to limits defined in the kernel (in linux/mm/percpu.c), the leaf_type cannot have a size of more than 32KB. In other words, BPF_PERCPU_HASH elements cannot be larger than 32KB in size. Defaults: BPF_PERCPU_HASH(name, key_type=u64, leaf_type=u64, size=10240) For example: BPF_PERCPU_HASH(start, struct request *); This creates NUM_CPU hashes named start where the key is a struct request *, and the value defaults to u64. This is a wrapper macro for BPF_TABLE(\"percpu_hash\", ...). Methods (covered later): map.lookup(), map.lookup_or_try_init(), map.delete(), map.update(), map.insert(), map.increment(). Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 7. BPF_PERCPU_HASH","id":"184","title":"7. BPF_PERCPU_HASH"},"185":{"body":"Syntax: BPF_PERCPU_ARRAY(name [, leaf_type [, size]]) Creates NUM_CPU int-indexed arrays which are optimized for fastest lookup and update, named name, with optional parameters. Each CPU will have a separate copy of this array. The copies are not kept synchronized in any way. Note that due to limits defined in the kernel (in linux/mm/percpu.c), the leaf_type cannot have a size of more than 32KB. In other words, BPF_PERCPU_ARRAY elements cannot be larger than 32KB in size. Defaults: BPF_PERCPU_ARRAY(name, leaf_type=u64, size=10240) For example: BPF_PERCPU_ARRAY(counts, u64, 32); This creates NUM_CPU arrays named counts where with 32 buckets and 64-bit integer values. This is a wrapper macro for BPF_TABLE(\"percpu_array\", ...). Methods (covered later): map.lookup(), map.update(), map.increment(). Note that all array elements are pre-allocated with zero values and can not be deleted. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 8. BPF_PERCPU_ARRAY","id":"185","title":"8. BPF_PERCPU_ARRAY"},"186":{"body":"Syntax: BPF_LPM_TRIE(name [, key_type [, leaf_type [, size]]]) Creates a longest prefix match trie map named name, with optional parameters. Defaults: BPF_LPM_TRIE(name, key_type=u64, leaf_type=u64, size=10240) For example: BPF_LPM_TRIE(trie, struct key_v6); This creates an LPM trie map named trie where the key is a struct key_v6, and the value defaults to u64. This is a wrapper macro to BPF_F_TABLE(\"lpm_trie\", ..., BPF_F_NO_PREALLOC). Methods (covered later): map.lookup(), map.lookup_or_try_init(), map.delete(), map.update(), map.insert(), map.increment(). Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 9. BPF_LPM_TRIE","id":"186","title":"9. BPF_LPM_TRIE"},"187":{"body":"Syntax: BPF_PROG_ARRAY(name, size) This creates a program array named name with size entries. Each entry of the array is either a file descriptor to a bpf program or NULL. The array acts as a jump table so that bpf programs can \"tail-call\" other bpf programs. This is a wrapper macro for BPF_TABLE(\"prog\", ...). Methods (covered later): map.call(). Examples in situ: search /examples , search /tests , assign fd","breadcrumbs":"bcc Reference Guide » 10. BPF_PROG_ARRAY","id":"187","title":"10. BPF_PROG_ARRAY"},"188":{"body":"Syntax: BPF_DEVMAP(name, size) This creates a device map named name with size entries. Each entry of the map is an ifindex to a network interface. This map is only used in XDP. For example: BPF_DEVMAP(devmap, 10); Methods (covered later): map.redirect_map(). Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 11. BPF_DEVMAP","id":"188","title":"11. BPF_DEVMAP"},"189":{"body":"Syntax: BPF_CPUMAP(name, size) This creates a cpu map named name with size entries. The index of the map represents the CPU id and each entry is the size of the ring buffer allocated for the CPU. This map is only used in XDP. For example: BPF_CPUMAP(cpumap, 16); Methods (covered later): map.redirect_map(). Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 12. BPF_CPUMAP","id":"189","title":"12. BPF_CPUMAP"},"19":{"body":"跟踪点（tracepoints）是内核静态插桩技术，跟踪点在技术上只是放置在内核源代码中的跟踪函数，实际上就是在源码中插入的一些带有控制条件的探测点，这些探测点允许事后再添加处理函数。比如在内核中，最常见的静态跟踪方法就是 printk，即输出日志。又比如：在系统调用、调度程序事件、文件系统操作和磁盘 I/O 的开始和结束时都有跟踪点。 于 2009 年在 Linux 2.6.32 版本中首次提供。跟踪点是一种稳定的 API，数量有限。","breadcrumbs":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程 » tracepoints","id":"19","title":"tracepoints"},"190":{"body":"Syntax: BPF_XSKMAP(name, size [, \"/sys/fs/bpf/xyz\"]) This creates a xsk map named name with size entries and pin it to the bpffs as a FILE. Each entry represents one NIC's queue id. This map is only used in XDP to redirect packet to an AF_XDP socket. If the AF_XDP socket is binded to a queue which is different than the current packet's queue id, the packet will be dropped. For kernel v5.3 and latter, lookup method is available and can be used to check whether and AF_XDP socket is available for the current packet's queue id. More details at AF_XDP . For example: BPF_XSKMAP(xsks_map, 8); Methods (covered later): map.redirect_map(). map.lookup() Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 13. BPF_XSKMAP","id":"190","title":"13. BPF_XSKMAP"},"191":{"body":"Syntax: BPF_ARRAY_OF_MAPS(name, inner_map_name, size) This creates an array map with a map-in-map type (BPF_MAP_TYPE_HASH_OF_MAPS) map named name with size entries. The inner map meta data is provided by map inner_map_name and can be most of array or hash maps except BPF_MAP_TYPE_PROG_ARRAY, BPF_MAP_TYPE_CGROUP_STORAGE and BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE. For example: BPF_TABLE(\"hash\", int, int, ex1, 1024);\nBPF_TABLE(\"hash\", int, int, ex2, 1024);\nBPF_ARRAY_OF_MAPS(maps_array, \"ex1\", 10);","breadcrumbs":"bcc Reference Guide » 14. BPF_ARRAY_OF_MAPS","id":"191","title":"14. BPF_ARRAY_OF_MAPS"},"192":{"body":"Syntax: BPF_HASH_OF_MAPS(name, key_type, inner_map_name, size) This creates a hash map with a map-in-map type (BPF_MAP_TYPE_HASH_OF_MAPS) map named name with size entries. The inner map meta data is provided by map inner_map_name and can be most of array or hash maps except BPF_MAP_TYPE_PROG_ARRAY, BPF_MAP_TYPE_CGROUP_STORAGE and BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE. For example: BPF_ARRAY(ex1, int, 1024);\nBPF_ARRAY(ex2, int, 1024);\nBPF_HASH_OF_MAPS(maps_hash, struct custom_key, \"ex1\", 10);","breadcrumbs":"bcc Reference Guide » 15. BPF_HASH_OF_MAPS","id":"192","title":"15. BPF_HASH_OF_MAPS"},"193":{"body":"Syntax: BPF_STACK(name, leaf_type, max_entries[, flags]) Creates a stack named name with value type leaf_type and max entries max_entries. Stack and Queue maps are only available from Linux 4.20+. For example: BPF_STACK(stack, struct event, 10240); This creates a stack named stack where the value type is struct event, that holds up to 10240 entries. Methods (covered later): map.push(), map.pop(), map.peek(). Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 16. BPF_STACK","id":"193","title":"16. BPF_STACK"},"194":{"body":"Syntax: BPF_QUEUE(name, leaf_type, max_entries[, flags]) Creates a queue named name with value type leaf_type and max entries max_entries. Stack and Queue maps are only available from Linux 4.20+. For example: BPF_QUEUE(queue, struct event, 10240); This creates a queue named queue where the value type is struct event, that holds up to 10240 entries. Methods (covered later): map.push(), map.pop(), map.peek(). Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 17. BPF_QUEUE","id":"194","title":"17. BPF_QUEUE"},"195":{"body":"Syntax: BPF_SOCKHASH(name[, key_type [, max_entries) Creates a hash named name, with optional parameters. sockhash is only available from Linux 4.18+. Default: BPF_SOCKHASH(name, key_type=u32, max_entries=10240) For example: struct sock_key { u32 remote_ip4; u32 local_ip4; u32 remote_port; u32 local_port;\n};\nBPF_HASH(skh, struct sock_key, 65535); This creates a hash named skh where the key is a struct sock_key. A sockhash is a BPF map type that holds references to sock structs. Then with a new sk/msg redirect bpf helper BPF programs can use the map to redirect skbs/msgs between sockets (map.sk_redirect_hash()/map.msg_redirect_hash()). The difference between BPF_SOCKHASH and BPF_SOCKMAP is that BPF_SOCKMAP is implemented based on an array, and enforces keys to be four bytes. While BPF_SOCKHASH is implemented based on hash table, and the type of key can be specified freely. Methods (covered later): map.sock_hash_update(), map.msg_redirect_hash(), map.sk_redirect_hash(). search /tests","breadcrumbs":"bcc Reference Guide » 18. BPF_SOCKHASH","id":"195","title":"18. BPF_SOCKHASH"},"196":{"body":"Syntax: *val map.lookup(&key) Lookup the key in the map, and return a pointer to its value if it exists, else NULL. We pass the key in as an address to a pointer. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 19. map.lookup()","id":"196","title":"19. map.lookup()"},"197":{"body":"Syntax: *val map.lookup_or_try_init(&key, &zero) Lookup the key in the map, and return a pointer to its value if it exists, else initialize the key's value to the second argument. This is often used to initialize values to zero. If the key cannot be inserted (e.g. the map is full) then NULL is returned. Examples in situ: search /examples , search /tools Note: The old map.lookup_or_init() may cause return from the function, so lookup_or_try_init() is recommended as it does not have this side effect.","breadcrumbs":"bcc Reference Guide » 20. map.lookup_or_try_init()","id":"197","title":"20. map.lookup_or_try_init()"},"198":{"body":"Syntax: map.delete(&key) Delete the key from the hash. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 21. map.delete()","id":"198","title":"21. map.delete()"},"199":{"body":"Syntax: map.update(&key, &val) Associate the value in the second argument to the key, overwriting any previous value. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 22. map.update()","id":"199","title":"22. map.update()"},"2":{"body":"对于浏览器而言，JavaScript 的引入带来的可编程性开启了一场巨大的革命，使浏览器发展成为几乎独立的操作系统。现在让我们回到 eBPF：为了理解 eBPF 对 Linux 内核的可编程性影响，对 Linux 内核的结构以及它如何与应用程序和硬件进行交互有一个高层次的理解是有帮助的[4]。 kernel-arch Linux 内核的主要目的是抽象出硬件或虚拟硬件，并提供一个一致的API（系统调用），允许应用程序运行和共享资源。为了实现这个目的，我们维护了一系列子系统和层，以分配这些责任[5]。每个子系统通常允许某种程度的配置，以考虑到用户的不同需求。如果不能配置所需的行为，就需要改变内核，从历史上看，改变内核的行为，或者让用户编写的程序能够在内核中运行，就有两种选择: 本地支持内核模块 写一个内核模块 改变内核源代码，并说服Linux内核社区相信这种改变是必要的。等待几年，让新的内核版本成为一种商品。 定期修复它，因为每个内核版本都可能破坏它。由于缺乏安全边界，冒着破坏你的Linux内核的风险 实际上，两种方案都不常用，前者成本太高，后者则几乎没有可移植性。 有了 eBPF，就有了一个新的选择，可以重新编程 Linux 内核的行为，而不需要改变内核的源代码或加载内核模块，同时保证在不同内核版本之间一定程度上的行为一致性和兼容性、以及安全性[6]。为了实现这个目的，eBPF 程序也需要有一套对应的 API，允许用户定义的应用程序运行和共享资源 --- 换句话说，某种意义上讲 eBPF 虚拟机也提供了一套类似于系统调用的机制，借助 eBPF 和用户态通信的机制，Wasm 虚拟机和用户态应用也可以获得这套“系统调用”的完整使用权，一方面能可编程地扩展传统的系统调用的能力，另一方面能在网络、文件系统等许多层次实现更高效的可编程 IO 处理。 new-os 正如上图所示，当今的 Linux 内核正在向一个新的内核模型演化：用户定义的应用程序可以在内核态和用户态同时执行，用户态通过传统的系统调用访问系统资源，内核态则通过 BPF Helper Calls 和系统的各个部分完成交互。截止 2023 年初，内核中的 eBPF 虚拟机中已经有 220 多个Helper 系统接口，涵盖了非常多的应用场景。 值得注意的是，BPF Helper Call 和系统调用二者并不是竞争关系，它们的编程模型和有性能优势的场景完全不同，也不会完全替代对方。对 Wasm 和 Wasi 相关生态来说，情况也类似，专门设计的 wasi 接口需要经历一个漫长的标准化过程，但可能在特定场景能为用户态应用获取更佳的性能和可移植性保证，而 eBPF 在保证沙箱本质和可移植性的前提下，可以提供一个快速灵活的扩展系统接口的方案。 目前的 eBPF 仍然处于早期阶段，但是借助当前 eBPF 提供的内核接口和用户态交互的能力，经由 Wasm-bpf 的系统接口转换，Wasm 虚拟机中的应用已经几乎有能力获取内核以及用户态任意一个函数调用的数据和返回值（kprobe，uprobe...）；以很低的代价收集和理解所有系统调用，并获取所有网络操作的数据包和套接字级别的数据（tracepoint，socket...）；在网络包处理解决方案中添加额外的协议分析器，并轻松地编程任何转发逻辑（XDP，TC...），以满足不断变化的需求，而无需离开Linux内核的数据包处理环境。 不仅如此，eBPF 还有能力往用户空间任意进程的任意地址写入数据（bpf_probe_write_user[7]），有限度地修改内核函数的返回值（bpf_override_return[8]），甚至在内核态直接执行某些系统调用[9]；所幸的是，eBPF 在加载进内核之前对字节码会进行严格的安全检查，确保没有内存越界等操作，同时，许多可能会扩大攻击面、带来安全风险的功能都是需要在编译内核时明确选择启用才能使用的；在 Wasm 虚拟机将字节码加载进内核之前，也可以明确选择启用或者禁用某些 eBPF 功能，以确保沙箱的安全性。","breadcrumbs":"eBPF 入门开发实践教程一：介绍 eBPF 的基本概念、常见的开发工具 » eBPF 的未来：内核的 JavaScript 可编程接口","id":"2","title":"eBPF 的未来：内核的 JavaScript 可编程接口"},"20":{"body":"面对创建一个 eBPF 项目，您是否对如何开始搭建环境以及选择编程语言感到困惑？别担心，我们为您准备了一系列 GitHub 模板，以便您快速启动一个全新的eBPF项目。只需在GitHub上点击 Use this template 按钮，即可开始使用。 https://github.com/eunomia-bpf/libbpf-starter-template ：基于C语言和 libbpf 框架的eBPF项目模板 https://github.com/eunomia-bpf/cilium-ebpf-starter-template ：基于C语言和cilium/ebpf框架的eBPF项目模板 https://github.com/eunomia-bpf/libbpf-rs-starter-template ：基于Rust语言和libbpf-rs框架的eBPF项目模板 https://github.com/eunomia-bpf/eunomia-template ：基于C语言和eunomia-bpf框架的eBPF项目模板 这些启动模板包含以下功能： 一个 Makefile，让您可以一键构建项目 一个 Dockerfile，用于为您的 eBPF 项目自动创建一个容器化环境并发布到 Github Packages GitHub Actions，用于自动化构建、测试和发布流程 eBPF 开发所需的所有依赖项 通过将现有仓库设置为模板，您和其他人可以快速生成具有相同基础结构的新仓库，从而省去了手动创建和配置的繁琐过程。借助 GitHub 模板仓库，开发者可以专注于项目的核心功能和逻辑，而无需为基础设置和结构浪费时间。更多关于模板仓库的信息，请参阅官方文档：https://docs.github.com/en/repositories/creating-and-managing-repositories/creating-a-template-repository","breadcrumbs":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程 » GitHub 模板：轻松构建 eBPF 项目和开发环境","id":"20","title":"GitHub 模板：轻松构建 eBPF 项目和开发环境"},"200":{"body":"Syntax: map.insert(&key, &val) Associate the value in the second argument to the key, only if there was no previous value. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 23. map.insert()","id":"200","title":"23. map.insert()"},"201":{"body":"Syntax: map.increment(key[, increment_amount]) Increments the key's value by increment_amount, which defaults to 1. Used for histograms. map.increment() are not atomic. In the concurrency case. If you want more accurate results, use map.atomic_increment() instead of map.increment(). The overhead of map.increment() and map.atomic_increment() is similar. Note. When using map.atomic_increment() to operate on a BPF map of type BPF_MAP_TYPE_HASH, map.atomic_increment() does not guarantee the atomicity of the operation when the specified key does not exist. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 24. map.increment()","id":"201","title":"24. map.increment()"},"202":{"body":"Syntax: int map.get_stackid(void *ctx, u64 flags) This walks the stack found via the struct pt_regs in ctx, saves it in the stack trace map, and returns a unique ID for the stack trace. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 25. map.get_stackid()","id":"202","title":"25. map.get_stackid()"},"203":{"body":"Syntax: u64 map.perf_read(u32 cpu) This returns the hardware performance counter as configured in 5. BPF_PERF_ARRAY Examples in situ: search /tests","breadcrumbs":"bcc Reference Guide » 26. map.perf_read()","id":"203","title":"26. map.perf_read()"},"204":{"body":"Syntax: void map.call(void *ctx, int index) This invokes bpf_tail_call() to tail-call the bpf program which the index entry in BPF_PROG_ARRAY points to. A tail-call is different from the normal call. It reuses the current stack frame after jumping to another bpf program and never goes back. If the index entry is empty, it won't jump anywhere and the program execution continues as normal. For example: BPF_PROG_ARRAY(prog_array, 10); int tail_call(void *ctx) { bpf_trace_printk(\"Tail-call\\n\"); return 0;\n} int do_tail_call(void *ctx) { bpf_trace_printk(\"Original program\\n\"); prog_array.call(ctx, 2); return 0;\n} b = BPF(src_file=\"example.c\")\ntail_fn = b.load_func(\"tail_call\", BPF.KPROBE)\nprog_array = b.get_table(\"prog_array\")\nprog_array[c_int(2)] = c_int(tail_fn.fd)\nb.attach_kprobe(event=\"some_kprobe_event\", fn_name=\"do_tail_call\") This assigns tail_call() to prog_array[2]. In the end of do_tail_call(), prog_array.call(ctx, 2) tail-calls tail_call() and executes it. NOTE: To prevent infinite loop, the maximum number of tail-calls is 32 ( MAX_TAIL_CALL_CNT ). Examples in situ: search /examples , search /tests","breadcrumbs":"bcc Reference Guide » 27. map.call()","id":"204","title":"27. map.call()"},"205":{"body":"Syntax: int map.redirect_map(int index, int flags) This redirects the incoming packets based on the index entry. If the map is BPF_DEVMAP , the packet will be sent to the transmit queue of the network interface that the entry points to. If the map is BPF_CPUMAP , the packet will be sent to the ring buffer of the index CPU and be processed by the CPU later. If the map is BPF_XSKMAP , the packet will be sent to the AF_XDP socket attached to the queue. If the packet is redirected successfully, the function will return XDP_REDIRECT. Otherwise, it will return XDP_ABORTED to discard the packet. For example: BPF_DEVMAP(devmap, 1); int redirect_example(struct xdp_md *ctx) { return devmap.redirect_map(0, 0);\n}\nint xdp_dummy(struct xdp_md *ctx) { return XDP_PASS;\n} ip = pyroute2.IPRoute()\nidx = ip.link_lookup(ifname=\"eth1\")[0] b = bcc.BPF(src_file=\"example.c\") devmap = b.get_table(\"devmap\")\ndevmap[c_uint32(0)] = c_int(idx) in_fn = b.load_func(\"redirect_example\", BPF.XDP)\nout_fn = b.load_func(\"xdp_dummy\", BPF.XDP)\nb.attach_xdp(\"eth0\", in_fn, 0)\nb.attach_xdp(\"eth1\", out_fn, 0) Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 28. map.redirect_map()","id":"205","title":"28. map.redirect_map()"},"206":{"body":"Syntax: int map.push(&val, int flags) Push an element onto a Stack or Queue table. Passing BPF_EXIST as a flag causes the Queue or Stack to discard the oldest element if it is full. Returns 0 on success, negative error on failure. Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 29. map.push()","id":"206","title":"29. map.push()"},"207":{"body":"Syntax: int map.pop(&val) Pop an element from a Stack or Queue table. *val is populated with the result. Unlike peeking, popping removes the element. Returns 0 on success, negative error on failure. Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 30. map.pop()","id":"207","title":"30. map.pop()"},"208":{"body":"Syntax: int map.peek(&val) Peek an element at the head of a Stack or Queue table. *val is populated with the result. Unlike popping, peeking does not remove the element. Returns 0 on success, negative error on failure. Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 31. map.peek()","id":"208","title":"31. map.peek()"},"209":{"body":"Syntax: int map.sock_hash_update(struct bpf_sock_ops *skops, &key, int flags) Add an entry to, or update a sockhash map referencing sockets. The skops is used as a new value for the entry associated to key. flags is one of: BPF_NOEXIST: The entry for key must not exist in the map.\nBPF_EXIST: The entry for key must already exist in the map.\nBPF_ANY: No condition on the existence of the entry for key. If the map has eBPF programs (parser and verdict), those will be inherited by the socket being added. If the socket is already attached to eBPF programs, this results in an error. Return 0 on success, or a negative error in case of failure. Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 32. map.sock_hash_update()","id":"209","title":"32. map.sock_hash_update()"},"21":{"body":"eBPF 程序的开发和使用流程可以概括为如下几个步骤： 定义 eBPF 程序的接口和类型：这包括定义 eBPF 程序的接口函数，定义和实现 eBPF 内核映射（maps）和共享内存（perf events），以及定义和使用 eBPF 内核帮助函数（helpers）。 编写 eBPF 程序的代码：这包括编写 eBPF 程序的主要逻辑，实现 eBPF 内核映射的读写操作，以及使用 eBPF 内核帮助函数。 编译 eBPF 程序：这包括使用 eBPF 编译器（例如 clang）将 eBPF 程序代码编译为 eBPF 字节码，并生成可执行的 eBPF 内核模块。ecc 本质上也是调用 clang 编译器来编译 eBPF 程序。 加载 eBPF 程序到内核：这包括将编译好的 eBPF 内核模块加载到 Linux 内核中，并将 eBPF 程序附加到指定的内核事件上。 使用 eBPF 程序：这包括监测 eBPF 程序的运行情况，并使用 eBPF 内核映射和共享内存进行数据交换和共享。 在实际开发中，还可能需要进行其他的步骤，例如配置编译和加载参数，管理 eBPF 内核模块和内核映射，以及使用其他高级功能等。 需要注意的是，BPF 程序的执行是在内核空间进行的，因此需要使用特殊的工具和技术来编写、编译和调试 BPF 程序。eunomia-bpf 是一个开源的 BPF 编译器和工具包，它可以帮助开发者快速和简单地编写和运行 BPF 程序。 本教程的文档和源代码已经全部开源，可以在 https://github.com/eunomia-bpf/bpf-developer-tutorial 中查看。","breadcrumbs":"eBPF 入门开发实践教程二：Hello World，基本框架和开发流程 » 总结","id":"21","title":"总结"},"210":{"body":"Syntax: int map.msg_redirect_hash(struct sk_msg_buff *msg, void *key, u64 flags) This helper is used in programs implementing policies at the socket level. If the message msg is allowed to pass (i.e. if the verdict eBPF program returns SK_PASS), redirect it to the socket referenced by map (of type BPF_MAP_TYPE_SOCKHASH) using hash key. Both ingress and egress interfaces can be used for redirection. The BPF_F_INGRESS value in flags is used to make the distinction (ingress path is selected if the flag is present, egress path otherwise). This is the only flag supported for now. Return SK_PASS on success, or SK_DROP on error. Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 33. map.msg_redirect_hash()","id":"210","title":"33. map.msg_redirect_hash()"},"211":{"body":"Syntax: int map.sk_redirect_hash(struct sk_buff *skb, void *key, u64 flags) This helper is used in programs implementing policies at the skb socket level. If the sk_buff skb is allowed to pass (i.e. if the verdict eBPF program returns SK_PASS), redirect it to the socket referenced by map (of type BPF_MAP_TYPE_SOCKHASH) using hash key. Both ingress and egress interfaces can be used for redirection. The BPF_F_INGRESS value in flags is used to make the distinction (ingress path is selected if the flag is present, egress otherwise). This is the only flag supported for now. Return SK_PASS on success, or SK_DROP on error. Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 34. map.sk_redirect_hash()","id":"211","title":"34. map.sk_redirect_hash()"},"212":{"body":"Depending on which BPF helpers are used, a GPL-compatible license is required. The special BCC macro BPF_LICENSE specifies the license of the BPF program. You can set the license as a comment in your source code, but the kernel has a special interface to specify it programmatically. If you need to use GPL-only helpers, it is recommended to specify the macro in your C code so that the kernel can understand it: // SPDX-License-Identifier: GPL-2.0+\n#define BPF_LICENSE GPL Otherwise, the kernel may reject loading your program (see the error description below). Note that it supports multiple words and quotes are not necessary: // SPDX-License-Identifier: GPL-2.0+ OR BSD-2-Clause\n#define BPF_LICENSE Dual BSD/GPL Check the BPF helpers reference to see which helpers are GPL-only and what the kernel understands as GPL-compatible. If the macro is not specified, BCC will automatically define the license of the program as GPL.","breadcrumbs":"bcc Reference Guide » Licensing","id":"212","title":"Licensing"},"213":{"body":"One of jobs for rewriter is to turn implicit memory accesses to explicit ones using kernel helpers. Recent kernel introduced a config option ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE which will be set for architectures who user address space and kernel address are disjoint. x86 and arm has this config option set while s390 does not. If ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE is not set, the bpf old helper bpf_probe_read() will not be available. Some existing users may have implicit memory accesses to access user memory, so using bpf_probe_read_kernel() will cause their application to fail. Therefore, for non-s390, the rewriter will use bpf_probe_read() for these implicit memory accesses. For s390, bpf_probe_read_kernel() is used as default and users should use bpf_probe_read_user() explicitly when accessing user memories.","breadcrumbs":"bcc Reference Guide » Rewriter","id":"213","title":"Rewriter"},"214":{"body":"","breadcrumbs":"bcc Reference Guide » bcc Python","id":"214","title":"bcc Python"},"215":{"body":"Constructors.","breadcrumbs":"bcc Reference Guide » Initialization","id":"215","title":"Initialization"},"216":{"body":"Syntax: BPF({text=BPF_program | src_file=filename} [, usdt_contexts=[USDT_object, ...]] [, cflags=[arg1, ...]] [, debug=int]) Creates a BPF object. This is the main object for defining a BPF program, and interacting with its output. Exactly one of text or src_file must be supplied (not both). The cflags specifies additional arguments to be passed to the compiler, for example -DMACRO_NAME=value or -I/include/path. The arguments are passed as an array, with each element being an additional argument. Note that strings are not split on whitespace, so each argument must be a different element of the array, e.g. [\"-include\", \"header.h\"]. The debug flags control debug output, and can be or'ed together: DEBUG_LLVM_IR = 0x1 compiled LLVM IR DEBUG_BPF = 0x2 loaded BPF bytecode and register state on branches DEBUG_PREPROCESSOR = 0x4 pre-processor result DEBUG_SOURCE = 0x8 ASM instructions embedded with source DEBUG_BPF_REGISTER_STATE = 0x10 register state on all instructions in addition to DEBUG_BPF DEBUG_BTF = 0x20 print the messages from the libbpf library. Examples: # define entire BPF program in one line:\nBPF(text='int do_trace(void *ctx) { bpf_trace_printk(\"hit!\\\\n\"); return 0; }'); # define program as a variable:\nprog = \"\"\"\nint hello(void *ctx) { bpf_trace_printk(\"Hello, World!\\\\n\"); return 0;\n}\n\"\"\"\nb = BPF(text=prog) # source a file:\nb = BPF(src_file = \"vfsreadlat.c\") # include a USDT object:\nu = USDT(pid=int(pid))\n[...]\nb = BPF(text=bpf_text, usdt_contexts=[u]) # add include paths:\nu = BPF(text=prog, cflags=[\"-I/path/to/include\"]) Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 1. BPF","id":"216","title":"1. BPF"},"217":{"body":"Syntax: USDT({pid=pid | path=path}) Creates an object to instrument User Statically-Defined Tracing (USDT) probes. Its primary method is enable_probe(). Arguments: pid: attach to this process ID. path: instrument USDT probes from this binary path. Examples: # include a USDT object:\nu = USDT(pid=int(pid))\n[...]\nb = BPF(text=bpf_text, usdt_contexts=[u]) Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 2. USDT","id":"217","title":"2. USDT"},"218":{"body":"","breadcrumbs":"bcc Reference Guide » Events","id":"218","title":"Events"},"219":{"body":"Syntax: BPF.attach_kprobe(event=\"event\", fn_name=\"name\") Instruments the kernel function event() using kernel dynamic tracing of the function entry, and attaches our C defined function name() to be called when the kernel function is called. For example: b.attach_kprobe(event=\"sys_clone\", fn_name=\"do_trace\") This will instrument the kernel sys_clone() function, which will then run our BPF defined do_trace() function each time it is called. You can call attach_kprobe() more than once, and attach your BPF function to multiple kernel functions. You can also call attach_kprobe() more than once to attach multiple BPF functions to the same kernel function. See the previous kprobes section for how to instrument arguments from BPF. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 1. attach_kprobe()","id":"219","title":"1. attach_kprobe()"},"22":{"body":"eBPF (Extended Berkeley Packet Filter) 是 Linux 内核上的一个强大的网络和性能分析工具。它允许开发者在内核运行时动态加载、更新和运行用户定义的代码。 本文是 eBPF 入门开发实践教程的第二篇，在 eBPF 中使用 kprobe 捕获 unlink 系统调用。本文会先讲解关于 kprobes 的基本概念和技术背景，然后介绍如何在 eBPF 中使用 kprobe 捕获 unlink 系统调用。","breadcrumbs":"eBPF 入门开发实践教程二：在 eBPF 中使用 kprobe 监测捕获 unlink 系统调用 » eBPF 入门开发实践教程二：在 eBPF 中使用 kprobe 监测捕获 unlink 系统调用","id":"22","title":"eBPF 入门开发实践教程二：在 eBPF 中使用 kprobe 监测捕获 unlink 系统调用"},"220":{"body":"Syntax: BPF.attach_kretprobe(event=\"event\", fn_name=\"name\" [, maxactive=int]) Instruments the return of the kernel function event() using kernel dynamic tracing of the function return, and attaches our C defined function name() to be called when the kernel function returns. For example: b.attach_kretprobe(event=\"vfs_read\", fn_name=\"do_return\") This will instrument the kernel vfs_read() function, which will then run our BPF defined do_return() function each time it is called. You can call attach_kretprobe() more than once, and attach your BPF function to multiple kernel function returns. You can also call attach_kretprobe() more than once to attach multiple BPF functions to the same kernel function return. When a kretprobe is installed on a kernel function, there is a limit on how many parallel calls it can catch. You can change that limit with maxactive. See the kprobes documentation for its default value. See the previous kretprobes section for how to instrument the return value from BPF. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 2. attach_kretprobe()","id":"220","title":"2. attach_kretprobe()"},"221":{"body":"Syntax: BPF.attach_tracepoint(tp=\"tracepoint\", fn_name=\"name\") Instruments the kernel tracepoint described by tracepoint, and when hit, runs the BPF function name(). This is an explicit way to instrument tracepoints. The TRACEPOINT_PROBE syntax, covered in the earlier tracepoints section, is an alternate method with the advantage of auto-declaring an args struct containing the tracepoint arguments. With attach_tracepoint(), the tracepoint arguments need to be declared in the BPF program. For example: # define BPF program\nbpf_text = \"\"\"\n#include struct urandom_read_args { // from /sys/kernel/debug/tracing/events/random/urandom_read/format u64 __unused__; u32 got_bits; u32 pool_left; u32 input_left;\n}; int printarg(struct urandom_read_args *args) { bpf_trace_printk(\"%d\\\\n\", args->got_bits); return 0;\n};\n\"\"\" # load BPF program\nb = BPF(text=bpf_text)\nb.attach_tracepoint(\"random:urandom_read\", \"printarg\") Notice how the first argument to printarg() is now our defined struct. Examples in situ: code , search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 3. attach_tracepoint()","id":"221","title":"3. attach_tracepoint()"},"222":{"body":"Syntax: BPF.attach_uprobe(name=\"location\", sym=\"symbol\", fn_name=\"name\" [, sym_off=int]), BPF.attach_uprobe(name=\"location\", sym_re=\"regex\", fn_name=\"name\"), BPF.attach_uprobe(name=\"location\", addr=int, fn_name=\"name\") Instruments the user-level function symbol() from either the library or binary named by location using user-level dynamic tracing of the function entry, and attach our C defined function name() to be called whenever the user-level function is called. If sym_off is given, the function is attached to the offset within the symbol. The real address addr may be supplied in place of sym, in which case sym must be set to its default value. If the file is a non-PIE executable, addr must be a virtual address, otherwise it must be an offset relative to the file load address. Instead of a symbol name, a regular expression can be provided in sym_re. The uprobe will then attach to symbols that match the provided regular expression. Libraries can be given in the name argument without the lib prefix, or with the full path (/usr/lib/...). Binaries can be given only with the full path (/bin/sh). For example: b.attach_uprobe(name=\"c\", sym=\"strlen\", fn_name=\"count\") This will instrument strlen() function from libc, and call our BPF function count() when it is called. Note how the \"lib\" in \"libc\" is not necessary to specify. Other examples: b.attach_uprobe(name=\"c\", sym=\"getaddrinfo\", fn_name=\"do_entry\")\nb.attach_uprobe(name=\"/usr/bin/python\", sym=\"main\", fn_name=\"do_main\") You can call attach_uprobe() more than once, and attach your BPF function to multiple user-level functions. See the previous uprobes section for how to instrument arguments from BPF. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 4. attach_uprobe()","id":"222","title":"4. attach_uprobe()"},"223":{"body":"Syntax: BPF.attach_uretprobe(name=\"location\", sym=\"symbol\", fn_name=\"name\") Instruments the return of the user-level function symbol() from either the library or binary named by location using user-level dynamic tracing of the function return, and attach our C defined function name() to be called whenever the user-level function returns. For example: b.attach_uretprobe(name=\"c\", sym=\"strlen\", fn_name=\"count\") This will instrument strlen() function from libc, and call our BPF function count() when it returns. Other examples: b.attach_uretprobe(name=\"c\", sym=\"getaddrinfo\", fn_name=\"do_return\")\nb.attach_uretprobe(name=\"/usr/bin/python\", sym=\"main\", fn_name=\"do_main\") You can call attach_uretprobe() more than once, and attach your BPF function to multiple user-level functions. See the previous uretprobes section for how to instrument the return value from BPF. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 5. attach_uretprobe()","id":"223","title":"5. attach_uretprobe()"},"224":{"body":"Syntax: USDT.enable_probe(probe=probe, fn_name=name) Attaches a BPF C function name to the USDT probe probe. Example: # enable USDT probe from given PID\nu = USDT(pid=int(pid))\nu.enable_probe(probe=\"http__server__request\", fn_name=\"do_trace\") To check if your binary has USDT probes, and what they are, you can run readelf -n binary and check the stap debug section. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 6. USDT.enable_probe()","id":"224","title":"6. USDT.enable_probe()"},"225":{"body":"Syntax: BPF.attach_raw_tracepoint(tp=\"tracepoint\", fn_name=\"name\") Instruments the kernel raw tracepoint described by tracepoint (event only, no category), and when hit, runs the BPF function name(). This is an explicit way to instrument tracepoints. The RAW_TRACEPOINT_PROBE syntax, covered in the earlier raw tracepoints section, is an alternate method. For example: b.attach_raw_tracepoint(\"sched_switch\", \"do_trace\") Examples in situ: search /tools","breadcrumbs":"bcc Reference Guide » 7. attach_raw_tracepoint()","id":"225","title":"7. attach_raw_tracepoint()"},"226":{"body":"Syntax: BPF.attach_raw_socket(fn, dev) Attaches a BPF function to the specified network interface. The fn must be the type of BPF.function and the bpf_prog type needs to be BPF_PROG_TYPE_SOCKET_FILTER (fn=BPF.load_func(func_name, BPF.SOCKET_FILTER)) fn.sock is a non-blocking raw socket that was created and bound to dev. All network packets processed by dev are copied to the recv-q of fn.sock after being processed by bpf_prog. Try to recv packet form fn.sock with rev/recvfrom/recvmsg. Note that if the recv-q is not read in time after the recv-q is full, the copied packets will be discarded. We can use this feature to capture network packets just like tcpdump. We can use ss --bpf --packet -p to observe fn.sock. Example: BPF.attach_raw_socket(bpf_func, ifname) Examples in situ: search /examples","breadcrumbs":"bcc Reference Guide » 8. attach_raw_socket()","id":"226","title":"8. attach_raw_socket()"},"227":{"body":"Syntax: BPF.attach_xdp(dev=\"device\", fn=b.load_func(\"fn_name\",BPF.XDP), flags) Instruments the network driver described by dev , and then receives the packet, run the BPF function fn_name() with flags. Here is a list of optional flags. # from xdp_flags uapi/linux/if_link.h\nXDP_FLAGS_UPDATE_IF_NOEXIST = (1 << 0)\nXDP_FLAGS_SKB_MODE = (1 << 1)\nXDP_FLAGS_DRV_MODE = (1 << 2)\nXDP_FLAGS_HW_MODE = (1 << 3)\nXDP_FLAGS_REPLACE = (1 << 4) You can use flags like this BPF.attach_xdp(dev=\"device\", fn=b.load_func(\"fn_name\",BPF.XDP), flags=BPF.XDP_FLAGS_UPDATE_IF_NOEXIST) The default value of flags is 0. This means if there is no xdp program with device, the fn will run with that device. If there is an xdp program running with device, the old program will be replaced with new fn program. Currently, bcc does not support XDP_FLAGS_REPLACE flag. The following are the descriptions of other flags. 1. XDP_FLAGS_UPDATE_IF_NOEXIST If an XDP program is already attached to the specified driver, attaching the XDP program again will fail. 2. XDP_FLAGS_SKB_MODE Driver doesn’t have support for XDP, but the kernel fakes it. XDP program works, but there’s no real performance benefit because packets are handed to kernel stack anyways which then emulates XDP – this is usually supported with generic network drivers used in home computers, laptops, and virtualized HW. 3. XDP_FLAGS_DRV_MODE A driver has XDP support and can hand then to XDP without kernel stack interaction – Few drivers can support it and those are usually for enterprise HW. 4. XDP_FLAGS_HW_MODE XDP can be loaded and executed directly on the NIC – just a handful of NICs can do that. For example: b.attach_xdp(dev=\"ens1\", fn=b.load_func(\"do_xdp\", BPF.XDP)) This will instrument the network device ens1 , which will then run our BPF defined do_xdp() function each time it receives packets. Don't forget to call b.remove_xdp(\"ens1\") at the end! Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 9. attach_xdp()","id":"227","title":"9. attach_xdp()"},"228":{"body":"Syntax: BPF.attach_func(fn, attachable_fd, attach_type [, flags]) Attaches a BPF function of the specified type to a particular attachable_fd. if the attach_type is BPF_FLOW_DISSECTOR, the function is expected to attach to current net namespace and attachable_fd must be 0. For example: b.attach_func(fn, cgroup_fd, BPFAttachType.CGROUP_SOCK_OPS)\nb.attach_func(fn, map_fd, BPFAttachType.SK_MSG_VERDICT) Note. When attached to \"global\" hooks (xdp, tc, lwt, cgroup). If the \"BPF function\" is no longer needed after the program terminates, be sure to call detach_func when the program exits. Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 10. attach_func()","id":"228","title":"10. attach_func()"},"229":{"body":"Syntax: BPF.detach_func(fn, attachable_fd, attach_type) Detaches a BPF function of the specified type. For example: b.detach_func(fn, cgroup_fd, BPFAttachType.CGROUP_SOCK_OPS)\nb.detach_func(fn, map_fd, BPFAttachType.SK_MSG_VERDICT) Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 11. detach_func()","id":"229","title":"11. detach_func()"},"23":{"body":"开发人员在内核或者模块的调试过程中，往往会需要要知道其中的一些函数有无被调用、何时被调用、执行是否正确以及函数的入参和返回值是什么等等。比较简单的做法是在内核代码对应的函数中添加日志打印信息，但这种方式往往需要重新编译内核或模块，重新启动设备之类的，操作较为复杂甚至可能会破坏原有的代码执行过程。 而利用kprobes技术，用户可以定义自己的回调函数，然后在内核或者模块中几乎所有的函数中（有些函数是不可探测的，例如kprobes自身的相关实现函数，后文会有详细说明）动态的插入探测点，当内核执行流程执行到指定的探测函数时，会调用该回调函数，用户即可收集所需的信息了，同时内核最后还会回到原本的正常执行流程。如果用户已经收集足够的信息，不再需要继续探测，则同样可以动态地移除探测点。因此kprobes技术具有对内核执行流程影响小和操作方便的优点。 kprobes技术包括的3种探测手段分别时kprobe、jprobe和kretprobe。首先kprobe是最基本的探测方式，是实现后两种的基础，它可以在任意的位置放置探测点（就连函数内部的某条指令处也可以），它提供了探测点的调用前、调用后和内存访问出错3种回调方式，分别是pre_handler、post_handler和fault_handler，其中pre_handler函数将在被探测指令被执行前回调，post_handler会在被探测指令执行完毕后回调（注意不是被探测函数），fault_handler会在内存访问出错时被调用；jprobe基于kprobe实现，它用于获取被探测函数的入参值；最后kretprobe从名字中就可以看出其用途了，它同样基于kprobe实现，用于获取被探测函数的返回值。 kprobes的技术原理并不仅仅包含存软件的实现方案，它也需要硬件架构提供支持。其中涉及硬件架构相关的是CPU的异常处理和单步调试技术，前者用于让程序的执行流程陷入到用户注册的回调函数中去，而后者则用于单步执行被探测点指令，因此并不是所有的架构均支持，目前kprobes技术已经支持多种架构，包括i386、x86_64、ppc64、ia64、sparc64、arm、ppc和mips（有些架构实现可能并不完全，具体可参考内核的Documentation/kprobes.txt）。 kprobes的特点与使用限制： kprobes允许在同一个被被探测位置注册多个kprobe，但是目前jprobe却不可以；同时也不允许以其他的jprobe回调函数和kprobe的post_handler回调函数作为被探测点。 一般情况下，可以探测内核中的任何函数，包括中断处理函数。不过在kernel/kprobes.c和arch/*/kernel/kprobes.c程序中用于实现kprobes自身的函数是不允许被探测的，另外还有do_page_fault和notifier_call_chain； 如果以一个内联函数为探测点，则kprobes可能无法保证对该函数的所有实例都注册探测点。由于gcc可能会自动将某些函数优化为内联函数，因此可能无法达到用户预期的探测效果； 一个探测点的回调函数可能会修改被探测函数运行的上下文，例如通过修改内核的数据结构或者保存与struct pt_regs结构体中的触发探测器之前寄存器信息。因此kprobes可以被用来安装bug修复代码或者注入故障测试代码； kprobes会避免在处理探测点函数时再次调用另一个探测点的回调函数，例如在printk()函数上注册了探测点，则在它的回调函数中可能再次调用printk函数，此时将不再触发printk探测点的回调，仅仅时增加了kprobe结构体中nmissed字段的数值； 在kprobes的注册和注销过程中不会使用mutex锁和动态的申请内存； kprobes回调函数的运行期间是关闭内核抢占的，同时也可能在关闭中断的情况下执行，具体要视CPU架构而定。因此不论在何种情况下，在回调函数中不要调用会放弃CPU的函数（如信号量、mutex锁等）； kretprobe通过替换返回地址为预定义的trampoline的地址来实现，因此栈回溯和gcc内嵌函数__builtin_return_address()调用将返回trampoline的地址而不是真正的被探测函数的返回地址； 如果一个函数的调用次数和返回次数不相等，则在类似这样的函数上注册kretprobe将可能不会达到预期的效果，例如do_exit()函数会存在问题，而do_execve()函数和do_fork()函数不会； 如果当在进入和退出一个函数时，CPU运行在非当前任务所有的栈上，那么往该函数上注册kretprobe可能会导致不可预料的后果，因此，kprobes不支持在X86_64的结构下为__switch_to()函数注册kretprobe，将直接返回-EINVAL。","breadcrumbs":"eBPF 入门开发实践教程二：在 eBPF 中使用 kprobe 监测捕获 unlink 系统调用 » kprobes 技术背景","id":"23","title":"kprobes 技术背景"},"230":{"body":"Syntax: BPF.detach_kprobe(event=\"event\", fn_name=\"name\") Detach a kprobe handler function of the specified event. For example: b.detach_kprobe(event=\"__page_cache_alloc\", fn_name=\"trace_func_entry\")","breadcrumbs":"bcc Reference Guide » 12. detach_kprobe()","id":"230","title":"12. detach_kprobe()"},"231":{"body":"Syntax: BPF.detach_kretprobe(event=\"event\", fn_name=\"name\") Detach a kretprobe handler function of the specified event. For example: b.detach_kretprobe(event=\"__page_cache_alloc\", fn_name=\"trace_func_return\")","breadcrumbs":"bcc Reference Guide » 13. detach_kretprobe()","id":"231","title":"13. detach_kretprobe()"},"232":{"body":"","breadcrumbs":"bcc Reference Guide » Debug Output","id":"232","title":"Debug Output"},"233":{"body":"Syntax: BPF.trace_print(fmt=\"fields\") This method continually reads the globally shared /sys/kernel/debug/tracing/trace_pipe file and prints its contents. This file can be written to via BPF and the bpf_trace_printk() function, however, that method has limitations, including a lack of concurrent tracing support. The BPF_PERF_OUTPUT mechanism, covered earlier, is preferred. Arguments: fmt: optional, and can contain a field formatting string. It defaults to None. Examples: # print trace_pipe output as-is:\nb.trace_print() # print PID and message:\nb.trace_print(fmt=\"{1} {5}\") Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 1. trace_print()","id":"233","title":"1. trace_print()"},"234":{"body":"Syntax: BPF.trace_fields(nonblocking=False) This method reads one line from the globally shared /sys/kernel/debug/tracing/trace_pipe file and returns it as fields. This file can be written to via BPF and the bpf_trace_printk() function, however, that method has limitations, including a lack of concurrent tracing support. The BPF_PERF_OUTPUT mechanism, covered earlier, is preferred. Arguments: nonblocking: optional, defaults to False. When set to True, the program will not block waiting for input. Examples: while 1: try: (task, pid, cpu, flags, ts, msg) = b.trace_fields() except ValueError: continue [...] Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 2. trace_fields()","id":"234","title":"2. trace_fields()"},"235":{"body":"Normal output from a BPF program is either: per-event: using PERF_EVENT_OUTPUT, open_perf_buffer(), and perf_buffer_poll(). map summary: using items(), or print_log2_hist(), covered in the Maps section.","breadcrumbs":"bcc Reference Guide » Output APIs","id":"235","title":"Output APIs"},"236":{"body":"Syntax: BPF.perf_buffer_poll(timeout=T) This polls from all open perf ring buffers, calling the callback function that was provided when calling open_perf_buffer for each entry. The timeout parameter is optional and measured in milliseconds. In its absence, polling continues indefinitely. Example: # loop with callback to print_event\nb[\"events\"].open_perf_buffer(print_event)\nwhile 1: try: b.perf_buffer_poll() except KeyboardInterrupt: exit(); Examples in situ: code , search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 1. perf_buffer_poll()","id":"236","title":"1. perf_buffer_poll()"},"237":{"body":"Syntax: BPF.ring_buffer_poll(timeout=T) This polls from all open ringbuf ring buffers, calling the callback function that was provided when calling open_ring_buffer for each entry. The timeout parameter is optional and measured in milliseconds. In its absence, polling continues until there is no more data or the callback returns a negative value. Example: # loop with callback to print_event\nb[\"events\"].open_ring_buffer(print_event)\nwhile 1: try: b.ring_buffer_poll(30) except KeyboardInterrupt: exit(); Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 2. ring_buffer_poll()","id":"237","title":"2. ring_buffer_poll()"},"238":{"body":"Syntax: BPF.ring_buffer_consume() This consumes from all open ringbuf ring buffers, calling the callback function that was provided when calling open_ring_buffer for each entry. Unlike ring_buffer_poll, this method does not poll for data before attempting to consume. This reduces latency at the expense of higher CPU consumption. If you are unsure which to use, use ring_buffer_poll. Example: # loop with callback to print_event\nb[\"events\"].open_ring_buffer(print_event)\nwhile 1: try: b.ring_buffer_consume() except KeyboardInterrupt: exit(); Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 3. ring_buffer_consume()","id":"238","title":"3. ring_buffer_consume()"},"239":{"body":"Maps are BPF data stores, and are used in bcc to implement a table, and then higher level objects on top of tables, including hashes and histograms.","breadcrumbs":"bcc Reference Guide » Map APIs","id":"239","title":"Map APIs"},"24":{"body":"完整代码如下： #include \"vmlinux.h\"\n#include \n#include \n#include char LICENSE[] SEC(\"license\") = \"Dual BSD/GPL\"; SEC(\"kprobe/do_unlinkat\")\nint BPF_KPROBE(do_unlinkat, int dfd, struct filename *name)\n{ pid_t pid; const char *filename; pid = bpf_get_current_pid_tgid() >> 32; filename = BPF_CORE_READ(name, name); bpf_printk(\"KPROBE ENTRY pid = %d, filename = %s\\n\", pid, filename); return 0;\n} SEC(\"kretprobe/do_unlinkat\")\nint BPF_KRETPROBE(do_unlinkat_exit, long ret)\n{ pid_t pid; pid = bpf_get_current_pid_tgid() >> 32; bpf_printk(\"KPROBE EXIT: pid = %d, ret = %ld\\n\", pid, ret); return 0;\n} 这段代码是一个简单的 eBPF 程序，用于监测和捕获在 Linux 内核中执行的 unlink 系统调用。unlink 系统调用的功能是删除一个文件。这个 eBPF 程序通过使用 kprobe（内核探针）在 do_unlinkat 函数的入口和退出处放置钩子，实现对该系统调用的跟踪。 首先，我们导入必要的头文件，如 vmlinux.h，bpf_helpers.h，bpf_tracing.h 和 bpf_core_read.h。接着，我们定义许可证，以允许程序在内核中运行。 #include \"vmlinux.h\"\n#include \n#include \n#include char LICENSE[] SEC(\"license\") = \"Dual BSD/GPL\"; 接下来，我们定义一个名为 BPF_KPROBE(do_unlinkat) 的 kprobe，当进入 do_unlinkat 函数时，它会被触发。该函数接受两个参数：dfd（文件描述符）和 name（文件名结构体指针）。在这个 kprobe 中，我们获取当前进程的 PID（进程标识符），然后读取文件名。最后，我们使用 bpf_printk 函数在内核日志中打印 PID 和文件名。 SEC(\"kprobe/do_unlinkat\")\nint BPF_KPROBE(do_unlinkat, int dfd, struct filename *name)\n{ pid_t pid; const char *filename; pid = bpf_get_current_pid_tgid() >> 32; filename = BPF_CORE_READ(name, name); bpf_printk(\"KPROBE ENTRY pid = %d, filename = %s\\n\", pid, filename); return 0;\n} 接下来，我们定义一个名为 BPF_KRETPROBE(do_unlinkat_exit) 的 kretprobe，当从 do_unlinkat 函数退出时，它会被触发。这个 kretprobe 的目的是捕获函数的返回值（ret）。我们再次获取当前进程的 PID，并使用 bpf_printk 函数在内核日志中打印 PID 和返回值。 SEC(\"kretprobe/do_unlinkat\")\nint BPF_KRETPROBE(do_unlinkat_exit, long ret)\n{ pid_t pid; pid = bpf_get_current_pid_tgid() >> 32; bpf_printk(\"KPROBE EXIT: pid = %d, ret = %ld\\n\", pid, ret); return 0;\n} eunomia-bpf 是一个结合 Wasm 的开源 eBPF 动态加载运行时和开发工具链，它的目的是简化 eBPF 程序的开发、构建、分发、运行。可以参考 https://github.com/eunomia-bpf/eunomia-bpf 下载和安装 ecc 编译工具链和 ecli 运行时。 要编译这个程序，请使用 ecc 工具： $ ecc kprobe-link.bpf.c\nCompiling bpf object...\nPacking ebpf object and config into package.json... 然后运行： sudo ecli run package.json 在另外一个窗口中： touch test1\nrm test1\ntouch test2\nrm test2 在 /sys/kernel/debug/tracing/trace_pipe 文件中，应该能看到类似下面的 kprobe 演示输出： $ sudo cat /sys/kernel/debug/tracing/trace_pipe rm-9346 [005] d..3 4710.951696: bpf_trace_printk: KPROBE ENTRY pid = 9346, filename = test1 rm-9346 [005] d..4 4710.951819: bpf_trace_printk: KPROBE EXIT: ret = 0 rm-9346 [005] d..3 4710.951852: bpf_trace_printk: KPROBE ENTRY pid = 9346, filename = test2 rm-9346 [005] d..4 4710.951895: bpf_trace_printk: KPROBE EXIT: ret = 0","breadcrumbs":"eBPF 入门开发实践教程二：在 eBPF 中使用 kprobe 监测捕获 unlink 系统调用 » kprobe 示例","id":"24","title":"kprobe 示例"},"240":{"body":"Syntax: BPF.get_table(name) Returns a table object. This is no longer used, as tables can now be read as items from BPF. Eg: BPF[name]. Examples: counts = b.get_table(\"counts\") counts = b[\"counts\"] These are equivalent.","breadcrumbs":"bcc Reference Guide » 1. get_table()","id":"240","title":"1. get_table()"},"241":{"body":"Syntax: table.open_perf_buffers(callback, page_cnt=N, lost_cb=None) This operates on a table as defined in BPF as BPF_PERF_OUTPUT(), and associates the callback Python function callback to be called when data is available in the perf ring buffer. This is part of the recommended mechanism for transferring per-event data from kernel to user space. The size of the perf ring buffer can be specified via the page_cnt parameter, which must be a power of two number of pages and defaults to 8. If the callback is not processing data fast enough, some submitted data may be lost. lost_cb will be called to log / monitor the lost count. If lost_cb is the default None value, it will just print a line of message to stderr. Example: # process event\ndef print_event(cpu, data, size): event = ct.cast(data, ct.POINTER(Data)).contents [...] # loop with callback to print_event\nb[\"events\"].open_perf_buffer(print_event)\nwhile 1: try: b.perf_buffer_poll() except KeyboardInterrupt: exit() Note that the data structure transferred will need to be declared in C in the BPF program. For example: // define output data structure in C\nstruct data_t { u32 pid; u64 ts; char comm[TASK_COMM_LEN];\n};\nBPF_PERF_OUTPUT(events);\n[...] In Python, you can either let bcc generate the data structure from C declaration automatically (recommended): def print_event(cpu, data, size): event = b[\"events\"].event(data)\n[...] or define it manually: # define output data structure in Python\nTASK_COMM_LEN = 16 # linux/sched.h\nclass Data(ct.Structure): _fields_ = [(\"pid\", ct.c_ulonglong), (\"ts\", ct.c_ulonglong), (\"comm\", ct.c_char * TASK_COMM_LEN)] def print_event(cpu, data, size): event = ct.cast(data, ct.POINTER(Data)).contents\n[...] Examples in situ: code , search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 2. open_perf_buffer()","id":"241","title":"2. open_perf_buffer()"},"242":{"body":"Syntax: table.items() Returns an array of the keys in a table. This can be used with BPF_HASH maps to fetch, and iterate, over the keys. Example: # print output\nprint(\"%10s %s\" % (\"COUNT\", \"STRING\"))\ncounts = b.get_table(\"counts\")\nfor k, v in sorted(counts.items(), key=lambda counts: counts[1].value): print(\"%10d \\\"%s\\\"\" % (v.value, k.c.encode('string-escape'))) This example also uses the sorted() method to sort by value. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 3. items()","id":"242","title":"3. items()"},"243":{"body":"Syntax: table.values() Returns an array of the values in a table.","breadcrumbs":"bcc Reference Guide » 4. values()","id":"243","title":"4. values()"},"244":{"body":"Syntax: table.clear() Clears the table: deletes all entries. Example: # print map summary every second:\nwhile True: time.sleep(1) print(\"%-8s\\n\" % time.strftime(\"%H:%M:%S\"), end=\"\") dist.print_log2_hist(sym + \" return:\") dist.clear() Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 5. clear()","id":"244","title":"5. clear()"},"245":{"body":"Syntax: table.items_lookup_and_delete_batch() Returns an array of the keys in a table with a single call to BPF syscall. This can be used with BPF_HASH maps to fetch, and iterate, over the keys. It also clears the table: deletes all entries. You should rather use table.items_lookup_and_delete_batch() than table.items() followed by table.clear(). It requires kernel v5.6. Example: # print call rate per second:\nprint(\"%9s-%9s-%8s-%9s\" % (\"PID\", \"COMM\", \"fname\", \"counter\"))\nwhile True: for k, v in sorted(b['map'].items_lookup_and_delete_batch(), key=lambda kv: (kv[0]).pid): print(\"%9s-%9s-%8s-%9d\" % (k.pid, k.comm, k.fname, v.counter)) sleep(1)","breadcrumbs":"bcc Reference Guide » 6. items_lookup_and_delete_batch()","id":"245","title":"6. items_lookup_and_delete_batch()"},"246":{"body":"Syntax: table.items_lookup_batch() Returns an array of the keys in a table with a single call to BPF syscall. This can be used with BPF_HASH maps to fetch, and iterate, over the keys. You should rather use table.items_lookup_batch() than table.items(). It requires kernel v5.6. Example: # print current value of map:\nprint(\"%9s-%9s-%8s-%9s\" % (\"PID\", \"COMM\", \"fname\", \"counter\"))\nwhile True: for k, v in sorted(b['map'].items_lookup_batch(), key=lambda kv: (kv[0]).pid): print(\"%9s-%9s-%8s-%9d\" % (k.pid, k.comm, k.fname, v.counter))","breadcrumbs":"bcc Reference Guide » 7. items_lookup_batch()","id":"246","title":"7. items_lookup_batch()"},"247":{"body":"Syntax: table.items_delete_batch(keys) It clears all entries of a BPF_HASH map when keys is None. It is more efficient than table.clear() since it generates only one system call. You can delete a subset of a map by giving an array of keys as parameter. Those keys and their associated values will be deleted. It requires kernel v5.6. Arguments: keys is optional and by default is None.","breadcrumbs":"bcc Reference Guide » 8. items_delete_batch()","id":"247","title":"8. items_delete_batch()"},"248":{"body":"Syntax: table.items_update_batch(keys, values) Update all the provided keys with new values. The two arguments must be the same length and within the map limits (between 1 and the maximum entries). It requires kernel v5.6. Arguments: keys is the list of keys to be updated values is the list containing the new values.","breadcrumbs":"bcc Reference Guide » 9. items_update_batch()","id":"248","title":"9. items_update_batch()"},"249":{"body":"Syntax: table.print_log2_hist(val_type=\"value\", section_header=\"Bucket ptr\", section_print_fn=None) Prints a table as a log2 histogram in ASCII. The table must be stored as log2, which can be done using the BPF function bpf_log2l(). Arguments: val_type: optional, column header. section_header: if the histogram has a secondary key, multiple tables will print and section_header can be used as a header description for each. section_print_fn: if section_print_fn is not None, it will be passed the bucket value. Example: b = BPF(text=\"\"\"\nBPF_HISTOGRAM(dist); int kprobe__blk_account_io_done(struct pt_regs *ctx, struct request *req)\n{ dist.increment(bpf_log2l(req->__data_len / 1024)); return 0;\n}\n\"\"\")\n[...] b[\"dist\"].print_log2_hist(\"kbytes\") Output: kbytes : count distribution 0 -> 1 : 3 | | 2 -> 3 : 0 | | 4 -> 7 : 211 |********** | 8 -> 15 : 0 | | 16 -> 31 : 0 | | 32 -> 63 : 0 | | 64 -> 127 : 1 | | 128 -> 255 : 800 |**************************************| This output shows a multi-modal distribution, with the largest mode of 128->255 kbytes and a count of 800. This is an efficient way to summarize data, as the summarization is performed in-kernel, and only the count column is passed to user space. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 10. print_log2_hist()","id":"249","title":"10. print_log2_hist()"},"25":{"body":"通过本文的示例，我们学习了如何使用 eBPF 的 kprobe 和 kretprobe 捕获 unlink 系统调用。更多的例子和详细的开发指南，请参考 eunomia-bpf 的官方文档： https://github.com/eunomia-bpf/eunomia-bpf 本文是 eBPF 入门开发实践教程的第二篇。下一篇文章将介绍如何在 eBPF 中使用 fentry 监测捕获 unlink 系统调用。 完整的教程和源代码已经全部开源，可以在 https://github.com/eunomia-bpf/bpf-developer-tutorial 中查看。","breadcrumbs":"eBPF 入门开发实践教程二：在 eBPF 中使用 kprobe 监测捕获 unlink 系统调用 » 总结","id":"25","title":"总结"},"250":{"body":"Syntax: table.print_linear_hist(val_type=\"value\", section_header=\"Bucket ptr\", section_print_fn=None) Prints a table as a linear histogram in ASCII. This is intended to visualize small integer ranges, eg, 0 to 100. Arguments: val_type: optional, column header. section_header: if the histogram has a secondary key, multiple tables will print and section_header can be used as a header description for each. section_print_fn: if section_print_fn is not None, it will be passed the bucket value. Example: b = BPF(text=\"\"\"\nBPF_HISTOGRAM(dist); int kprobe__blk_account_io_done(struct pt_regs *ctx, struct request *req)\n{ dist.increment(req->__data_len / 1024); return 0;\n}\n\"\"\")\n[...] b[\"dist\"].print_linear_hist(\"kbytes\") Output: kbytes : count distribution 0 : 3 |****** | 1 : 0 | | 2 : 0 | | 3 : 0 | | 4 : 19 |****************************************| 5 : 0 | | 6 : 0 | | 7 : 0 | | 8 : 4 |******** | 9 : 0 | | 10 : 0 | | 11 : 0 | | 12 : 0 | | 13 : 0 | | 14 : 0 | | 15 : 0 | | 16 : 2 |**** |\n[...] This is an efficient way to summarize data, as the summarization is performed in-kernel, and only the values in the count column are passed to user space. Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 11. print_linear_hist()","id":"250","title":"11. print_linear_hist()"},"251":{"body":"Syntax: table.open_ring_buffer(callback, ctx=None) This operates on a table as defined in BPF as BPF_RINGBUF_OUTPUT(), and associates the callback Python function callback to be called when data is available in the ringbuf ring buffer. This is part of the new (Linux 5.8+) recommended mechanism for transferring per-event data from kernel to user space. Unlike perf buffers, ringbuf sizes are specified within the BPF program, as part of the BPF_RINGBUF_OUTPUT macro. If the callback is not processing data fast enough, some submitted data may be lost. In this case, the events should be polled more frequently and/or the size of the ring buffer should be increased. Example: # process event\ndef print_event(ctx, data, size): event = ct.cast(data, ct.POINTER(Data)).contents [...] # loop with callback to print_event\nb[\"events\"].open_ring_buffer(print_event)\nwhile 1: try: b.ring_buffer_poll() except KeyboardInterrupt: exit() Note that the data structure transferred will need to be declared in C in the BPF program. For example: // define output data structure in C\nstruct data_t { u32 pid; u64 ts; char comm[TASK_COMM_LEN];\n};\nBPF_RINGBUF_OUTPUT(events, 8);\n[...] In Python, you can either let bcc generate the data structure from C declaration automatically (recommended): def print_event(ctx, data, size): event = b[\"events\"].event(data)\n[...] or define it manually: # define output data structure in Python\nTASK_COMM_LEN = 16 # linux/sched.h\nclass Data(ct.Structure): _fields_ = [(\"pid\", ct.c_ulonglong), (\"ts\", ct.c_ulonglong), (\"comm\", ct.c_char * TASK_COMM_LEN)] def print_event(ctx, data, size): event = ct.cast(data, ct.POINTER(Data)).contents\n[...] Examples in situ: search /examples ,","breadcrumbs":"bcc Reference Guide » 12. open_ring_buffer()","id":"251","title":"12. open_ring_buffer()"},"252":{"body":"Syntax: table.push(leaf, flags=0) Push an element onto a Stack or Queue table. Raises an exception if the operation does not succeed. Passing QueueStack.BPF_EXIST as a flag causes the Queue or Stack to discard the oldest element if it is full. Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 13. push()","id":"252","title":"13. push()"},"253":{"body":"Syntax: leaf = table.pop() Pop an element from a Stack or Queue table. Unlike peek(), pop() removes the element from the table before returning it. Raises a KeyError exception if the operation does not succeed. Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 14. pop()","id":"253","title":"14. pop()"},"254":{"body":"Syntax: leaf = table.peek() Peek the element at the head of a Stack or Queue table. Unlike pop(), peek() does not remove the element from the table. Raises an exception if the operation does not succeed. Examples in situ: search /tests ,","breadcrumbs":"bcc Reference Guide » 15. peek()","id":"254","title":"15. peek()"},"255":{"body":"Some helper methods provided by bcc. Note that since we're in Python, we can import any Python library and their methods, including, for example, the libraries: argparse, collections, ctypes, datetime, re, socket, struct, subprocess, sys, and time.","breadcrumbs":"bcc Reference Guide » Helpers","id":"255","title":"Helpers"},"256":{"body":"Syntax: BPF.ksym(addr) Translate a kernel memory address into a kernel function name, which is returned. Example: print(\"kernel function: \" + b.ksym(addr)) Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 1. ksym()","id":"256","title":"1. ksym()"},"257":{"body":"Syntax: BPF.ksymname(name) Translate a kernel name into an address. This is the reverse of ksym. Returns -1 when the function name is unknown. Example: print(\"kernel address: %x\" % b.ksymname(\"vfs_read\")) Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 2. ksymname()","id":"257","title":"2. ksymname()"},"258":{"body":"Syntax: BPF.sym(addr, pid, show_module=False, show_offset=False) Translate a memory address into a function name for a pid, which is returned. A pid of less than zero will access the kernel symbol cache. The show_module and show_offset parameters control whether the module in which the symbol lies should be displayed, and whether the instruction offset from the beginning of the symbol should be displayed. These extra parameters default to False. Example: print(\"function: \" + b.sym(addr, pid)) Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 3. sym()","id":"258","title":"3. sym()"},"259":{"body":"Syntax: BPF.num_open_kprobes() Returns the number of open k[ret]probes. Can be useful for scenarios where event_re is used while attaching and detaching probes. Excludes perf_events readers. Example: b.attach_kprobe(event_re=pattern, fn_name=\"trace_count\")\nmatched = b.num_open_kprobes()\nif matched == 0: print(\"0 functions matched by \\\"%s\\\". Exiting.\" % args.pattern) exit() Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 4. num_open_kprobes()","id":"259","title":"4. num_open_kprobes()"},"26":{"body":"eBPF (Extended Berkeley Packet Filter) 是 Linux 内核上的一个强大的网络和性能分析工具。它允许开发者在内核运行时动态加载、更新和运行用户定义的代码。 本文是 eBPF 入门开发实践教程的第三篇，在 eBPF 中使用 fentry 捕获 unlink 系统调用。","breadcrumbs":"eBPF 入门开发实践教程三：在 eBPF 中使用 fentry 监测捕获 unlink 系统调用 » eBPF 入门开发实践教程三：在 eBPF 中使用 fentry 监测捕获 unlink 系统调用","id":"26","title":"eBPF 入门开发实践教程三：在 eBPF 中使用 fentry 监测捕获 unlink 系统调用"},"260":{"body":"Syntax: BPF.get_syscall_fnname(name : str) Return the corresponding kernel function name of the syscall. This helper function will try different prefixes and use the right one to concatenate with the syscall name. Note that the return value may vary in different versions of linux kernel and sometimes it will causing trouble. (see #2590 ) Example: print(\"The function name of %s in kernel is %s\" % (\"clone\", b.get_syscall_fnname(\"clone\")))\n# sys_clone or __x64_sys_clone or ... Examples in situ: search /examples , search /tools","breadcrumbs":"bcc Reference Guide » 5. get_syscall_fnname()","id":"260","title":"5. get_syscall_fnname()"},"261":{"body":"See the \"Understanding eBPF verifier messages\" section in the kernel source under Documentation/networking/filter.txt.","breadcrumbs":"bcc Reference Guide » BPF Errors","id":"261","title":"BPF Errors"},"262":{"body":"This can be due to trying to read memory directly, instead of operating on memory on the BPF stack. All kernel memory reads must be passed via bpf_probe_read_kernel() to copy kernel memory into the BPF stack, which can be automatic by the bcc rewriter in some cases of simple dereferencing. bpf_probe_read_kernel() does all the required checks. Example: bpf: Permission denied\n0: (bf) r6 = r1\n1: (79) r7 = *(u64 *)(r6 +80)\n2: (85) call 14\n3: (bf) r8 = r0\n[...]\n23: (69) r1 = *(u16 *)(r7 +16)\nR7 invalid mem access 'inv' Traceback (most recent call last): File \"./tcpaccept\", line 179, in b = BPF(text=bpf_text) File \"/usr/lib/python2.7/dist-packages/bcc/__init__.py\", line 172, in __init__ self._trace_autoload() File \"/usr/lib/python2.7/dist-packages/bcc/__init__.py\", line 612, in _trace_autoload fn = self.load_func(func_name, BPF.KPROBE) File \"/usr/lib/python2.7/dist-packages/bcc/__init__.py\", line 212, in load_func raise Exception(\"Failed to load BPF program %s\" % func_name)\nException: Failed to load BPF program kretprobe__inet_csk_accept","breadcrumbs":"bcc Reference Guide » 1. Invalid mem access","id":"262","title":"1. Invalid mem access"},"263":{"body":"This error happens when a GPL-only helper is called from a non-GPL BPF program. To fix this error, do not use GPL-only helpers from a proprietary BPF program, or relicense the BPF program under a GPL-compatible license. Check which BPF helpers are GPL-only, and what licenses are considered GPL-compatible. Example calling bpf_get_stackid(), a GPL-only BPF helper, from a proprietary program (#define BPF_LICENSE Proprietary): bpf: Failed to load program: Invalid argument\n[...]\n8: (85) call bpf_get_stackid#27\ncannot call GPL only function from proprietary program","breadcrumbs":"bcc Reference Guide » 2. Cannot call GPL only function from proprietary program","id":"263","title":"2. Cannot call GPL only function from proprietary program"},"264":{"body":"","breadcrumbs":"bcc Reference Guide » Environment Variables","id":"264","title":"Environment Variables"},"265":{"body":"eBPF program compilation needs kernel sources or kernel headers with headers compiled. In case your kernel sources are at a non-standard location where BCC cannot find then, its possible to provide BCC the absolute path of the location by setting BCC_KERNEL_SOURCE to it.","breadcrumbs":"bcc Reference Guide » 1. Kernel source directory","id":"265","title":"1. Kernel source directory"},"266":{"body":"By default, BCC stores the LINUX_VERSION_CODE in the generated eBPF object which is then passed along to the kernel when the eBPF program is loaded. Sometimes this is quite inconvenient especially when the kernel is slightly updated such as an LTS kernel release. Its extremely unlikely the slight mismatch would cause any issues with the loaded eBPF program. By setting BCC_LINUX_VERSION_CODE to the version of the kernel that's running, the check for verifying the kernel version can be bypassed. This is needed for programs that use kprobes. This needs to be encoded in the format: (VERSION * 65536) + (PATCHLEVEL * 256) + SUBLEVEL. For example, if the running kernel is 4.9.10, then can set export BCC_LINUX_VERSION_CODE=264458 to override the kernel version check successfully.","breadcrumbs":"bcc Reference Guide » 2. Kernel version overriding","id":"266","title":"2. Kernel version overriding"},"267":{"body":"Some tools have special filtering capabitilies, the main use case is to trace processes running in containers, but those mechanisms are generic and could be used in other cases as well.","breadcrumbs":"Special Filtering » Special Filtering","id":"267","title":"Special Filtering"},"268":{"body":"Some tools have an option to filter by cgroup by referencing a pinned BPF hash map managed externally. Examples of commands: # ./opensnoop --cgroupmap /sys/fs/bpf/test01\n# ./execsnoop --cgroupmap /sys/fs/bpf/test01\n# ./tcpconnect --cgroupmap /sys/fs/bpf/test01\n# ./tcpaccept --cgroupmap /sys/fs/bpf/test01\n# ./tcptracer --cgroupmap /sys/fs/bpf/test01 The commands above will only display results from processes that belong to one of the cgroups whose id, returned by bpf_get_current_cgroup_id(), is in the pinned BPF hash map. The BPF hash map can be created by: # bpftool map create /sys/fs/bpf/test01 type hash key 8 value 8 entries 128 \\ name cgroupset flags 0 To get a shell in a new cgroup, you can use: # systemd-run --pty --unit test bash The shell will be running in the cgroup /sys/fs/cgroup/unified/system.slice/test.service. The cgroup id can be discovered using the name_to_handle_at() system call. In the examples/cgroupid, you will find an example of program to get the cgroup id. # cd examples/cgroupid\n# make\n# ./cgroupid hex /sys/fs/cgroup/unified/system.slice/test.service or, using Docker: # cd examples/cgroupid\n# docker build -t cgroupid .\n# docker run --rm --privileged -v /sys/fs/cgroup:/sys/fs/cgroup \\ cgroupid cgroupid hex /sys/fs/cgroup/unified/system.slice/test.service This prints the cgroup id as a hexadecimal string in the host endianness such as 77 16 00 00 01 00 00 00. # FILE=/sys/fs/bpf/test01\n# CGROUPID_HEX=\"77 16 00 00 01 00 00 00\"\n# bpftool map update pinned $FILE key hex $CGROUPID_HEX value hex 00 00 00 00 00 00 00 00 any Now that the shell started by systemd-run has its cgroup id in the BPF hash map, bcc tools will display results from this shell. Cgroups can be added and removed from the BPF hash map without restarting the bcc tool. This feature is useful for integrating bcc tools in external projects.","breadcrumbs":"Special Filtering » Filtering by cgroups","id":"268","title":"Filtering by cgroups"},"269":{"body":"The BPF hash map can be created by: # bpftool map create /sys/fs/bpf/mnt_ns_set type hash key 8 value 4 entries 128 \\ name mnt_ns_set flags 0 Execute the execsnoop tool filtering only the mount namespaces in /sys/fs/bpf/mnt_ns_set: # tools/execsnoop.py --mntnsmap /sys/fs/bpf/mnt_ns_set Start a terminal in a new mount namespace: # unshare -m bash Update the hash map with the mount namespace ID of the terminal above: FILE=/sys/fs/bpf/mnt_ns_set\nif [ $(printf '\\1' | od -dAn) -eq 1 ]; then HOST_ENDIAN_CMD=tac\nelse HOST_ENDIAN_CMD=cat\nfi NS_ID_HEX=\"$(printf '%016x' $(stat -Lc '%i' /proc/self/ns/mnt) | sed 's/.\\{2\\}/&\\n/g' | $HOST_ENDIAN_CMD)\"\nbpftool map update pinned $FILE key hex $NS_ID_HEX value hex 00 00 00 00 any Execute a command in this terminal: # ping kinvolk.io You'll see how on the execsnoop terminal you started above the call is logged: # tools/execsnoop.py --mntnsmap /sys/fs/bpf/mnt_ns_set\n[sudo] password for mvb:\nPCOMM PID PPID RET ARGS\nping 8096 7970 0 /bin/ping kinvolk.io","breadcrumbs":"Special Filtering » Filtering by mount by namespace","id":"269","title":"Filtering by mount by namespace"},"27":{"body":"fentry（function entry）和fexit（function exit）是eBPF（扩展的伯克利包过滤器）中的两种探针类型，用于在Linux内核函数的入口和退出处进行跟踪。它们允许开发者在内核函数执行的特定阶段收集信息、修改参数或观察返回值。这种跟踪和监控功能在性能分析、故障排查和安全分析等场景中非常有用。 与 kprobes 相比，fentry 和 fexit 程序有更高的性能和可用性。在这个例子中，我们可以直接访问函数的指针参数，就像在普通的 C 代码中一样，而不需要使用各种读取帮助程序。fexit 和 kretprobe 程序最大的区别在于，fexit 程序可以访问函数的输入参数和返回值，而 kretprobe 只能访问返回值。从 5.5 内核开始，fentry 和 fexit 对 eBPF 程序可用。 #include \"vmlinux.h\"\n#include \n#include char LICENSE[] SEC(\"license\") = \"Dual BSD/GPL\"; SEC(\"fentry/do_unlinkat\")\nint BPF_PROG(do_unlinkat, int dfd, struct filename *name)\n{ pid_t pid; pid = bpf_get_current_pid_tgid() >> 32; bpf_printk(\"fentry: pid = %d, filename = %s\\n\", pid, name->name); return 0;\n} SEC(\"fexit/do_unlinkat\")\nint BPF_PROG(do_unlinkat_exit, int dfd, struct filename *name, long ret)\n{ pid_t pid; pid = bpf_get_current_pid_tgid() >> 32; bpf_printk(\"fexit: pid = %d, filename = %s, ret = %ld\\n\", pid, name->name, ret); return 0;\n} 这段程序是用C语言编写的eBPF（扩展的伯克利包过滤器）程序，它使用BPF的fentry和fexit探针来跟踪Linux内核函数do_unlinkat。在这个教程中，我们将以这段程序作为示例，让您学会如何在eBPF中使用fentry监测捕获unlink系统调用。 程序包含以下部分： 包含头文件：包括vmlinux.h（用于访问内核数据结构）、bpf/bpf_helpers.h（包含eBPF帮助函数）、bpf/bpf_tracing.h（用于eBPF跟踪相关功能）。 定义许可证：这里定义了一个名为LICENSE的字符数组，包含许可证信息\"Dual BSD/GPL\"。 定义fentry探针：我们定义了一个名为BPF_PROG(do_unlinkat)的fentry探针，该探针在do_unlinkat函数的入口处被触发。这个探针获取当前进程的PID（进程ID）并将其与文件名一起打印到内核日志。 定义fexit探针：我们还定义了一个名为BPF_PROG(do_unlinkat_exit)的fexit探针，该探针在do_unlinkat函数的退出处被触发。与fentry探针类似，这个探针也会获取当前进程的PID并将其与文件名和返回值一起打印到内核日志。 通过这个示例，您可以学习如何在eBPF中使用fentry和fexit探针来监控和捕获内核函数调用，例如在本教程中的unlink系统调用。 eunomia-bpf 是一个结合 Wasm 的开源 eBPF 动态加载运行时和开发工具链，它的目的是简化 eBPF 程序的开发、构建、分发、运行。可以参考 https://github.com/eunomia-bpf/eunomia-bpf 下载和安装 ecc 编译工具链和 ecli 运行时。我们使用 eunomia-bpf 编译运行这个例子。 编译运行上述代码： $ ecc fentry-link.bpf.c\nCompiling bpf object...\nPacking ebpf object and config into package.json...\n$ sudo ecli run package.json\nRuning eBPF program... 在另外一个窗口中： touch test_file\nrm test_file\ntouch test_file2\nrm test_file2 运行这段程序后，可以通过查看 /sys/kernel/debug/tracing/trace_pipe 文件来查看 eBPF 程序的输出： $ sudo cat /sys/kernel/debug/tracing/trace_pipe rm-9290 [004] d..2 4637.798698: bpf_trace_printk: fentry: pid = 9290, filename = test_file rm-9290 [004] d..2 4637.798843: bpf_trace_printk: fexit: pid = 9290, filename = test_file, ret = 0 rm-9290 [004] d..2 4637.798698: bpf_trace_printk: fentry: pid = 9290, filename = test_file2 rm-9290 [004] d..2 4637.798843: bpf_trace_printk: fexit: pid = 9290, filename = test_file2, ret = 0","breadcrumbs":"eBPF 入门开发实践教程三：在 eBPF 中使用 fentry 监测捕获 unlink 系统调用 » Fentry","id":"27","title":"Fentry"},"270":{"body":"This tutorial covers how to use bcc tools to quickly solve performance, troubleshooting, and networking issues. If you want to develop new bcc tools, see tutorial_bcc_python_developer.md for that tutorial. It is assumed for this tutorial that bcc is already installed, and you can run tools like execsnoop successfully. See INSTALL.md . This uses enhancements added to the Linux 4.x series.","breadcrumbs":"bcc Tutorial » bcc Tutorial","id":"270","title":"bcc Tutorial"},"271":{"body":"Some quick wins.","breadcrumbs":"bcc Tutorial » Observability","id":"271","title":"Observability"},"272":{"body":"Before using bcc, you should start with the Linux basics. One reference is the Linux Performance Analysis in 60,000 Milliseconds post, which covers these commands: uptime dmesg | tail vmstat 1 mpstat -P ALL 1 pidstat 1 iostat -xz 1 free -m sar -n DEV 1 sar -n TCP,ETCP 1 top","breadcrumbs":"bcc Tutorial » 0. Before bcc","id":"272","title":"0. Before bcc"},"273":{"body":"Here is a generic checklist for performance investigations with bcc, first as a list, then in detail: execsnoop opensnoop ext4slower (or btrfs*, xfs*, zfs*) biolatency biosnoop cachestat tcpconnect tcpaccept tcpretrans runqlat profile These tools may be installed on your system under /usr/share/bcc/tools, or you can run them from the bcc github repo under /tools where they have a .py extension. Browse the 50+ tools available for more analysis options. 1.1 execsnoop # ./execsnoop\nPCOMM PID RET ARGS\nsupervise 9660 0 ./run\nsupervise 9661 0 ./run\nmkdir 9662 0 /bin/mkdir -p ./main\nrun 9663 0 ./run\n[...] execsnoop prints one line of output for each new process. Check for short-lived processes. These can consume CPU resources, but not show up in most monitoring tools that periodically take snapshots of which processes are running. It works by tracing exec(), not the fork(), so it will catch many types of new processes but not all (eg, it won't see an application launching working processes, that doesn't exec() anything else). More examples . 1.2. opensnoop # ./opensnoop\nPID COMM FD ERR PATH\n1565 redis-server 5 0 /proc/1565/stat\n1565 redis-server 5 0 /proc/1565/stat\n1565 redis-server 5 0 /proc/1565/stat\n1603 snmpd 9 0 /proc/net/dev\n1603 snmpd 11 0 /proc/net/if_inet6\n1603 snmpd -1 2 /sys/class/net/eth0/device/vendor\n1603 snmpd 11 0 /proc/sys/net/ipv4/neigh/eth0/retrans_time_ms\n1603 snmpd 11 0 /proc/sys/net/ipv6/neigh/eth0/retrans_time_ms\n1603 snmpd 11 0 /proc/sys/net/ipv6/conf/eth0/forwarding\n[...] opensnoop prints one line of output for each open() syscall, including details. Files that are opened can tell you a lot about how applications work: identifying their data files, config files, and log files. Sometimes applications can misbehave, and perform poorly, when they are constantly attempting to read files that do not exist. opensnoop gives you a quick look. More examples . 1.3. ext4slower (or btrfs*, xfs*, zfs*) # ./ext4slower\nTracing ext4 operations slower than 10 ms\nTIME COMM PID T BYTES OFF_KB LAT(ms) FILENAME\n06:35:01 cron 16464 R 1249 0 16.05 common-auth\n06:35:01 cron 16463 R 1249 0 16.04 common-auth\n06:35:01 cron 16465 R 1249 0 16.03 common-auth\n06:35:01 cron 16465 R 4096 0 10.62 login.defs\n06:35:01 cron 16464 R 4096 0 10.61 login.defs ext4slower traces the ext4 file system and times common operations, and then only prints those that exceed a threshold. This is great for identifying or exonerating one type of performance issue: show individually slow disk i/O via the file system. Disks process I/O asynchronously, and it can be difficult to associate latency at that layer with the latency applications experience. Tracing higher up in the kernel stack, at the VFS -> file system interface, will more closely match what an application suffers. Use this tool to identify if file system latency exceeds a given threshold. Similar tools exist in bcc for other file systems: btrfsslower, xfsslower, and zfsslower. There is also fileslower, which works at the VFS layer and traces everything (although at some higher overhead). More examples . 1.4. biolatency # ./biolatency\nTracing block device I/O... Hit Ctrl-C to end.\n^C usecs : count distribution 0 -> 1 : 0 | | 2 -> 3 : 0 | | 4 -> 7 : 0 | | 8 -> 15 : 0 | | 16 -> 31 : 0 | | 32 -> 63 : 0 | | 64 -> 127 : 1 | | 128 -> 255 : 12 |******** | 256 -> 511 : 15 |********** | 512 -> 1023 : 43 |******************************* | 1024 -> 2047 : 52 |**************************************| 2048 -> 4095 : 47 |********************************** | 4096 -> 8191 : 52 |**************************************| 8192 -> 16383 : 36 |************************** | 16384 -> 32767 : 15 |********** | 32768 -> 65535 : 2 |* | 65536 -> 131071 : 2 |* | biolatency traces disk I/O latency (time from device issue to completion), and when the tool ends (Ctrl-C, or a given interval), it prints a histogram summary of the latency. This is great for understanding disk I/O latency beyond the average times given by tools like iostat. I/O latency outliers will be visible at the end of the distribution, as well as multi-mode distributions. More examples . 1.5. biosnoop # ./biosnoop\nTIME(s) COMM PID DISK T SECTOR BYTES LAT(ms)\n0.000004001 supervise 1950 xvda1 W 13092560 4096 0.74\n0.000178002 supervise 1950 xvda1 W 13092432 4096 0.61\n0.001469001 supervise 1956 xvda1 W 13092440 4096 1.24\n0.001588002 supervise 1956 xvda1 W 13115128 4096 1.09\n1.022346001 supervise 1950 xvda1 W 13115272 4096 0.98\n1.022568002 supervise 1950 xvda1 W 13188496 4096 0.93\n[...] biosnoop prints a line of output for each disk I/O, with details including latency (time from device issue to completion). This allows you to examine disk I/O in more detail, and look for time-ordered patterns (eg, reads queueing behind writes). Note that the output will be verbose if your system performs disk I/O at a high rate. More examples . 1.6. cachestat # ./cachestat HITS MISSES DIRTIES READ_HIT% WRITE_HIT% BUFFERS_MB CACHED_MB 1074 44 13 94.9% 2.9% 1 223 2195 170 8 92.5% 6.8% 1 143 182 53 56 53.6% 1.3% 1 143 62480 40960 20480 40.6% 19.8% 1 223 7 2 5 22.2% 22.2% 1 223 348 0 0 100.0% 0.0% 1 223\n[...] cachestat prints a one line summary every second (or every custom interval) showing statistics from the file system cache. Use this to identify a low cache hit ratio, and a high rate of misses: which gives one lead for performance tuning. More examples . 1.7. tcpconnect # ./tcpconnect\nPID COMM IP SADDR DADDR DPORT\n1479 telnet 4 127.0.0.1 127.0.0.1 23\n1469 curl 4 10.201.219.236 54.245.105.25 80\n1469 curl 4 10.201.219.236 54.67.101.145 80\n1991 telnet 6 ::1 ::1 23\n2015 ssh 6 fe80::2000:bff:fe82:3ac fe80::2000:bff:fe82:3ac 22\n[...] tcpconnect prints one line of output for every active TCP connection (eg, via connect()), with details including source and destination addresses. Look for unexpected connections that may point to inefficiencies in application configuration, or an intruder. More examples . 1.8. tcpaccept # ./tcpaccept\nPID COMM IP RADDR LADDR LPORT\n907 sshd 4 192.168.56.1 192.168.56.102 22\n907 sshd 4 127.0.0.1 127.0.0.1 22\n5389 perl 6 1234:ab12:2040:5020:2299:0:5:0 1234:ab12:2040:5020:2299:0:5:0 7001\n[...] tcpaccept prints one line of output for every passive TCP connection (eg, via accept()), with details including source and destination addresses. Look for unexpected connections that may point to inefficiencies in application configuration, or an intruder. More examples . 1.9. tcpretrans # ./tcpretrans\nTIME PID IP LADDR:LPORT T> RADDR:RPORT STATE\n01:55:05 0 4 10.153.223.157:22 R> 69.53.245.40:34619 ESTABLISHED\n01:55:05 0 4 10.153.223.157:22 R> 69.53.245.40:34619 ESTABLISHED\n01:55:17 0 4 10.153.223.157:22 R> 69.53.245.40:22957 ESTABLISHED\n[...] tcprerans prints one line of output for every TCP retransmit packet, with details including source and destination addresses, and kernel state of the TCP connection. TCP retransmissions cause latency and throughput issues. For ESTABLISHED retransmits, look for patterns with networks. For SYN_SENT, this may point to target kernel CPU saturation and kernel packet drops. More examples . 1.10. runqlat # ./runqlat\nTracing run queue latency... Hit Ctrl-C to end.\n^C usecs : count distribution 0 -> 1 : 233 |*********** | 2 -> 3 : 742 |************************************ | 4 -> 7 : 203 |********** | 8 -> 15 : 173 |******** | 16 -> 31 : 24 |* | 32 -> 63 : 0 | | 64 -> 127 : 30 |* | 128 -> 255 : 6 | | 256 -> 511 : 3 | | 512 -> 1023 : 5 | | 1024 -> 2047 : 27 |* | 2048 -> 4095 : 30 |* | 4096 -> 8191 : 20 | | 8192 -> 16383 : 29 |* | 16384 -> 32767 : 809 |****************************************| 32768 -> 65535 : 64 |*** | runqlat times how long threads were waiting on the CPU run queues, and prints this as a histogram. This can help quantify time lost waiting for a turn on CPU, during periods of CPU saturation. More examples . 1.11. profile # ./profile\nSampling at 49 Hertz of all threads by user + kernel stack... Hit Ctrl-C to end.\n^C 00007f31d76c3251 [unknown] 47a2c1e752bf47f7 [unknown] - sign-file (8877) 1 ffffffff813d0af8 __clear_user ffffffff813d5277 iov_iter_zero ffffffff814ec5f2 read_iter_zero ffffffff8120be9d __vfs_read ffffffff8120c385 vfs_read ffffffff8120d786 sys_read ffffffff817cc076 entry_SYSCALL_64_fastpath 00007fc5652ad9b0 read - dd (25036) 4 0000000000400542 func_a 0000000000400598 main 00007f12a133e830 __libc_start_main 083e258d4c544155 [unknown] - func_ab (13549) 5 [...] ffffffff8105eb66 native_safe_halt ffffffff8103659e default_idle ffffffff81036d1f arch_cpu_idle ffffffff810bba5a default_idle_call ffffffff810bbd07 cpu_startup_entry ffffffff8104df55 start_secondary - swapper/1 (0) 75 profile is a CPU profiler, which takes samples of stack traces at timed intervals, and prints a summary of unique stack traces and a count of their occurrence. Use this tool to understand the code paths that are consuming CPU resources. More examples .","breadcrumbs":"bcc Tutorial » 1. General Performance","id":"273","title":"1. General Performance"},"274":{"body":"In addition to the above tools for performance tuning, below is a checklist for bcc generic tools, first as a list, and in detail: trace argdist funccount These generic tools may be useful to provide visibility to solve your specific problems. 2.1. trace Example 1 Suppose you want to track file ownership change. There are three syscalls, chown, fchown and lchown which users can use to change file ownership. The corresponding syscall entry is SyS_[f|l]chown. The following command can be used to print out syscall parameters and the calling process user id. You can use id command to find the uid of a particular user. $ trace.py \\ 'p::SyS_chown \"file = %s, to_uid = %d, to_gid = %d, from_uid = %d\", arg1, arg2, arg3, $uid' \\ 'p::SyS_fchown \"fd = %d, to_uid = %d, to_gid = %d, from_uid = %d\", arg1, arg2, arg3, $uid' \\ 'p::SyS_lchown \"file = %s, to_uid = %d, to_gid = %d, from_uid = %d\", arg1, arg2, arg3, $uid'\nPID TID COMM FUNC -\n1269255 1269255 python3.6 SyS_lchown file = /tmp/dotsync-usisgezu/tmp, to_uid = 128203, to_gid = 100, from_uid = 128203\n1269441 1269441 zstd SyS_chown file = /tmp/dotsync-vic7ygj0/dotsync-package.zst, to_uid = 128203, to_gid = 100, from_uid = 128203\n1269255 1269255 python3.6 SyS_lchown file = /tmp/dotsync-a40zd7ev/tmp, to_uid = 128203, to_gid = 100, from_uid = 128203\n1269442 1269442 zstd SyS_chown file = /tmp/dotsync-gzp413o_/dotsync-package.zst, to_uid = 128203, to_gid = 100, from_uid = 128203\n1269255 1269255 python3.6 SyS_lchown file = /tmp/dotsync-whx4fivm/tmp/.bash_profile, to_uid = 128203, to_gid = 100, from_uid = 128203 Example 2 Suppose you want to count nonvoluntary context switches (nvcsw) in your bpf based performance monitoring tools and you do not know what is the proper method. /proc//status already tells you the number (nonvoluntary_ctxt_switches) for a pid and you can use trace.py to do a quick experiment to verify your method. With kernel source code, the nvcsw is counted at file linux/kernel/sched/core.c function __schedule and under condition !(!preempt && prev->state) // i.e., preempt || !prev->state The __schedule function is marked as notrace, and the best place to evaluate the above condition seems in sched/sched_switch tracepoint called inside function __schedule and defined in linux/include/trace/events/sched.h. trace.py already has args being the pointer to the tracepoint TP_STRUCT__entry. The above condition in function __schedule can be represented as args->prev_state == TASK_STATE_MAX || args->prev_state == 0 The below command can be used to count the involuntary context switches (per process or per pid) and compare to /proc//status or /proc//task//status for correctness, as in typical cases, involuntary context switches are not very common. $ trace.py -p 1134138 't:sched:sched_switch (args->prev_state == TASK_STATE_MAX || args->prev_state == 0)'\nPID TID COMM FUNC\n1134138 1134140 contention_test sched_switch\n1134138 1134142 contention_test sched_switch\n...\n$ trace.py -L 1134140 't:sched:sched_switch (args->prev_state == TASK_STATE_MAX || args->prev_state == 0)'\nPID TID COMM FUNC\n1134138 1134140 contention_test sched_switch\n1134138 1134140 contention_test sched_switch\n... Example 3 This example is related to issue 1231 and 1516 where uprobe does not work at all in certain cases. First, you can do a strace as below $ strace trace.py 'r:bash:readline \"%s\", retval'\n...\nperf_event_open(0x7ffd968212f0, -1, 0, -1, 0x8 /* PERF_FLAG_??? */) = -1 EIO (Input/output error)\n... The perf_event_open syscall returns -EIO. Digging into kernel uprobe related codes in /kernel/trace and /kernel/events directories to search EIO, the function uprobe_register is the most suspicious. Let us find whether this function is called or not and what is the return value if it is called. In one terminal using the following command to print out the return value of uprobe_register, $ trace.py 'r::uprobe_register \"ret = %d\", retval' In another terminal run the same bash uretprobe tracing example, and you should get $ trace.py 'r::uprobe_register \"ret = %d\", retval'\nPID TID COMM FUNC -\n1041401 1041401 python2.7 uprobe_register ret = -5 The -5 error code is EIO. This confirms that the following code in function uprobe_register is the most suspicious culprit. if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping)) return -EIO; The shmem_mapping function is defined as bool shmem_mapping(struct address_space *mapping)\n{ return mapping->a_ops == &shmem_aops;\n} To confirm the theory, find what is inode->i_mapping->a_ops with the following command $ trace.py -I 'linux/fs.h' 'p::uprobe_register(struct inode *inode) \"a_ops = %llx\", inode->i_mapping->a_ops'\nPID TID COMM FUNC -\n814288 814288 python2.7 uprobe_register a_ops = ffffffff81a2adc0\n^C$ grep ffffffff81a2adc0 /proc/kallsyms\nffffffff81a2adc0 R empty_aops The kernel symbol empty_aops does not have readpage defined and hence the above suspicious condition is true. Further examining the kernel source code shows that overlayfs does not provide its own a_ops while some other file systems (e.g., ext4) define their own a_ops (e.g., ext4_da_aops), and ext4_da_aops defines readpage. Hence, uprobe works fine on ext4 while not on overlayfs. More examples . 2.2. argdist More examples . 2.3. funccount More examples .","breadcrumbs":"bcc Tutorial » 2. Observability with Generic Tools","id":"274","title":"2. Observability with Generic Tools"},"275":{"body":"To do.","breadcrumbs":"bcc Tutorial » Networking","id":"275","title":"Networking"},"276":{"body":"This tutorial is about developing bcc tools and programs using the Python interface. There are two parts: observability then networking. Snippets are taken from various programs in bcc: see their files for licences. Also see the bcc developer's reference_guide.md , and a tutorial for end-users of tools: tutorial.md . There is also a lua interface for bcc.","breadcrumbs":"bcc Python Developer Tutorial » bcc Python Developer Tutorial","id":"276","title":"bcc Python Developer Tutorial"},"277":{"body":"This observability tutorial contains 17 lessons, and 46 enumerated things to learn.","breadcrumbs":"bcc Python Developer Tutorial » Observability","id":"277","title":"Observability"},"278":{"body":"Start by running examples/hello_world.py , while running some commands (eg, \"ls\") in another session. It should print \"Hello, World!\" for new processes. If not, start by fixing bcc: see INSTALL.md . # ./examples/hello_world.py bash-13364 [002] d... 24573433.052937: : Hello, World! bash-13364 [003] d... 24573436.642808: : Hello, World!\n[...] Here's the code for hello_world.py: from bcc import BPF\nBPF(text='int kprobe__sys_clone(void *ctx) { bpf_trace_printk(\"Hello, World!\\\\n\"); return 0; }').trace_print() There are six things to learn from this: text='...': This defines a BPF program inline. The program is written in C. kprobe__sys_clone(): This is a short-cut for kernel dynamic tracing via kprobes. If the C function begins with kprobe__, the rest is treated as a kernel function name to instrument, in this case, sys_clone(). void *ctx: ctx has arguments, but since we aren't using them here, we'll just cast it to void *. bpf_trace_printk(): A simple kernel facility for printf() to the common trace_pipe (/sys/kernel/debug/tracing/trace_pipe). This is ok for some quick examples, but has limitations: 3 args max, 1 %s only, and trace_pipe is globally shared, so concurrent programs will have clashing output. A better interface is via BPF_PERF_OUTPUT(), covered later. return 0;: Necessary formality (if you want to know why, see #139 ). .trace_print(): A bcc routine that reads trace_pipe and prints the output.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 1. Hello World","id":"278","title":"Lesson 1. Hello World"},"279":{"body":"Write a program that traces the sys_sync() kernel function. Print \"sys_sync() called\" when it runs. Test by running sync in another session while tracing. The hello_world.py program has everything you need for this. Improve it by printing \"Tracing sys_sync()... Ctrl-C to end.\" when the program first starts. Hint: it's just Python.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 2. sys_sync()","id":"279","title":"Lesson 2. sys_sync()"},"28":{"body":"这段程序是一个 eBPF 程序，通过使用 fentry 和 fexit 捕获 do_unlinkat 和 do_unlinkat_exit 函数，并通过使用 bpf_get_current_pid_tgid 和 bpf_printk 函数获取调用 do_unlinkat 的进程 ID、文件名和返回值，并在内核日志中打印出来。 编译这个程序可以使用 ecc 工具，运行时可以使用 ecli 命令，并通过查看 /sys/kernel/debug/tracing/trace_pipe 文件查看 eBPF 程序的输出。更多的例子和详细的开发指南，请参考 eunomia-bpf 的官方文档： https://github.com/eunomia-bpf/eunomia-bpf 完整的教程和源代码已经全部开源，可以在 https://github.com/eunomia-bpf/bpf-developer-tutorial 中查看。","breadcrumbs":"eBPF 入门开发实践教程三：在 eBPF 中使用 fentry 监测捕获 unlink 系统调用 » 总结","id":"28","title":"总结"},"280":{"body":"This program is in examples/tracing/hello_fields.py . Sample output (run commands in another session): # examples/tracing/hello_fields.py\nTIME(s) COMM PID MESSAGE\n24585001.174885999 sshd 1432 Hello, World!\n24585001.195710000 sshd 15780 Hello, World!\n24585001.991976000 systemd-udevd 484 Hello, World!\n24585002.276147000 bash 15787 Hello, World! Code: from bcc import BPF # define BPF program\nprog = \"\"\"\nint hello(void *ctx) { bpf_trace_printk(\"Hello, World!\\\\n\"); return 0;\n}\n\"\"\" # load BPF program\nb = BPF(text=prog)\nb.attach_kprobe(event=b.get_syscall_fnname(\"clone\"), fn_name=\"hello\") # header\nprint(\"%-18s %-16s %-6s %s\" % (\"TIME(s)\", \"COMM\", \"PID\", \"MESSAGE\")) # format output\nwhile 1: try: (task, pid, cpu, flags, ts, msg) = b.trace_fields() except ValueError: continue print(\"%-18.9f %-16s %-6d %s\" % (ts, task, pid, msg)) This is similar to hello_world.py, and traces new processes via sys_clone() again, but has a few more things to learn: prog =: This time we declare the C program as a variable, and later refer to it. This is useful if you want to add some string substitutions based on command line arguments. hello(): Now we're just declaring a C function, instead of the kprobe__ shortcut. We'll refer to this later. All C functions declared in the BPF program are expected to be executed on a probe, hence they all need to take a pt_reg* ctx as first argument. If you need to define some helper function that will not be executed on a probe, they need to be defined as static inline in order to be inlined by the compiler. Sometimes you would also need to add _always_inline function attribute to it. b.attach_kprobe(event=b.get_syscall_fnname(\"clone\"), fn_name=\"hello\"): Creates a kprobe for the kernel clone system call function, which will execute our defined hello() function. You can call attach_kprobe() more than once, and attach your C function to multiple kernel functions. b.trace_fields(): Returns a fixed set of fields from trace_pipe. Similar to trace_print(), this is handy for hacking, but for real tooling we should switch to BPF_PERF_OUTPUT().","breadcrumbs":"bcc Python Developer Tutorial » Lesson 3. hello_fields.py","id":"280","title":"Lesson 3. hello_fields.py"},"281":{"body":"Remember the days of sysadmins typing sync three times on a slow console before reboot, to give the first asynchronous sync time to complete? Then someone thought sync;sync;sync was clever, to run them all on one line, which became industry practice despite defeating the original purpose! And then sync became synchronous, so more reasons it was silly. Anyway. The following example times how quickly the do_sync function is called, and prints output if it has been called more recently than one second ago. A sync;sync;sync will print output for the 2nd and 3rd sync's: # examples/tracing/sync_timing.py\nTracing for quick sync's... Ctrl-C to end\nAt time 0.00 s: multiple syncs detected, last 95 ms ago\nAt time 0.10 s: multiple syncs detected, last 96 ms ago This program is examples/tracing/sync_timing.py : from __future__ import print_function\nfrom bcc import BPF # load BPF program\nb = BPF(text=\"\"\"\n#include BPF_HASH(last); int do_trace(struct pt_regs *ctx) { u64 ts, *tsp, delta, key = 0; // attempt to read stored timestamp tsp = last.lookup(&key); if (tsp != NULL) { delta = bpf_ktime_get_ns() - *tsp; if (delta < 1000000000) { // output if time is less than 1 second bpf_trace_printk(\"%d\\\\n\", delta / 1000000); } last.delete(&key); } // update stored timestamp ts = bpf_ktime_get_ns(); last.update(&key, &ts); return 0;\n}\n\"\"\") b.attach_kprobe(event=b.get_syscall_fnname(\"sync\"), fn_name=\"do_trace\")\nprint(\"Tracing for quick sync's... Ctrl-C to end\") # format output\nstart = 0\nwhile 1: (task, pid, cpu, flags, ts, ms) = b.trace_fields() if start == 0: start = ts ts = ts - start print(\"At time %.2f s: multiple syncs detected, last %s ms ago\" % (ts, ms)) Things to learn: bpf_ktime_get_ns(): Returns the time as nanoseconds. BPF_HASH(last): Creates a BPF map object that is a hash (associative array), called \"last\". We didn't specify any further arguments, so it defaults to key and value types of u64. key = 0: We'll only store one key/value pair in this hash, where the key is hardwired to zero. last.lookup(&key): Lookup the key in the hash, and return a pointer to its value if it exists, else NULL. We pass the key in as an address to a pointer. if (tsp != NULL) {: The verifier requires that pointer values derived from a map lookup must be checked for a null value before they can be dereferenced and used. last.delete(&key): Delete the key from the hash. This is currently required because of a kernel bug in .update() (fixed in 4.8.10). last.update(&key, &ts): Associate the value in the 2nd argument to the key, overwriting any previous value. This records the timestamp.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 4. sync_timing.py","id":"281","title":"Lesson 4. sync_timing.py"},"282":{"body":"Modify the sync_timing.py program (prior lesson) to store the count of all kernel sync system calls (both fast and slow), and print it with the output. This count can be recorded in the BPF program by adding a new key index to the existing hash.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 5. sync_count.py","id":"282","title":"Lesson 5. sync_count.py"},"283":{"body":"Browse the examples/tracing/disksnoop.py program to see what is new. Here is some sample output: # disksnoop.py\nTIME(s) T BYTES LAT(ms)\n16458043.436012 W 4096 3.13\n16458043.437326 W 4096 4.44\n16458044.126545 R 4096 42.82\n16458044.129872 R 4096 3.24\n[...] And a code snippet: [...]\nREQ_WRITE = 1 # from include/linux/blk_types.h # load BPF program\nb = BPF(text=\"\"\"\n#include \n#include BPF_HASH(start, struct request *); void trace_start(struct pt_regs *ctx, struct request *req) { // stash start timestamp by request ptr u64 ts = bpf_ktime_get_ns(); start.update(&req, &ts);\n} void trace_completion(struct pt_regs *ctx, struct request *req) { u64 *tsp, delta; tsp = start.lookup(&req); if (tsp != 0) { delta = bpf_ktime_get_ns() - *tsp; bpf_trace_printk(\"%d %x %d\\\\n\", req->__data_len, req->cmd_flags, delta / 1000); start.delete(&req); }\n}\n\"\"\")\nif BPF.get_kprobe_functions(b'blk_start_request'): b.attach_kprobe(event=\"blk_start_request\", fn_name=\"trace_start\")\nb.attach_kprobe(event=\"blk_mq_start_request\", fn_name=\"trace_start\")\nif BPF.get_kprobe_functions(b'__blk_account_io_done'): b.attach_kprobe(event=\"__blk_account_io_done\", fn_name=\"trace_completion\")\nelse: b.attach_kprobe(event=\"blk_account_io_done\", fn_name=\"trace_completion\")\n[...] Things to learn: REQ_WRITE: We're defining a kernel constant in the Python program because we'll use it there later. If we were using REQ_WRITE in the BPF program, it should just work (without needing to be defined) with the appropriate #includes. trace_start(struct pt_regs *ctx, struct request *req): This function will later be attached to kprobes. The arguments to kprobe functions are struct pt_regs *ctx, for registers and BPF context, and then the actual arguments to the function. We'll attach this to blk_start_request(), where the first argument is struct request *. start.update(&req, &ts): We're using the pointer to the request struct as a key in our hash. What? This is commonplace in tracing. Pointers to structs turn out to be great keys, as they are unique: two structs can't have the same pointer address. (Just be careful about when it gets free'd and reused.) So what we're really doing is tagging the request struct, which describes the disk I/O, with our own timestamp, so that we can time it. There's two common keys used for storing timestamps: pointers to structs, and, thread IDs (for timing function entry to return). req->__data_len: We're dereferencing members of struct request. See its definition in the kernel source for what members are there. bcc actually rewrites these expressions to be a series of bpf_probe_read_kernel() calls. Sometimes bcc can't handle a complex dereference, and you need to call bpf_probe_read_kernel() directly. This is a pretty interesting program, and if you can understand all the code, you'll understand many important basics. We're still using the bpf_trace_printk() hack, so let's fix that next.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 6. disksnoop.py","id":"283","title":"Lesson 6. disksnoop.py"},"284":{"body":"Let's finally stop using bpf_trace_printk() and use the proper BPF_PERF_OUTPUT() interface. This will also mean we stop getting the free trace_field() members like PID and timestamp, and will need to fetch them directly. Sample output while commands are run in another session: # hello_perf_output.py\nTIME(s) COMM PID MESSAGE\n0.000000000 bash 22986 Hello, perf_output!\n0.021080275 systemd-udevd 484 Hello, perf_output!\n0.021359520 systemd-udevd 484 Hello, perf_output!\n0.021590610 systemd-udevd 484 Hello, perf_output!\n[...] Code is examples/tracing/hello_perf_output.py : from bcc import BPF # define BPF program\nprog = \"\"\"\n#include // define output data structure in C\nstruct data_t { u32 pid; u64 ts; char comm[TASK_COMM_LEN];\n};\nBPF_PERF_OUTPUT(events); int hello(struct pt_regs *ctx) { struct data_t data = {}; data.pid = bpf_get_current_pid_tgid(); data.ts = bpf_ktime_get_ns(); bpf_get_current_comm(&data.comm, sizeof(data.comm)); events.perf_submit(ctx, &data, sizeof(data)); return 0;\n}\n\"\"\" # load BPF program\nb = BPF(text=prog)\nb.attach_kprobe(event=b.get_syscall_fnname(\"clone\"), fn_name=\"hello\") # header\nprint(\"%-18s %-16s %-6s %s\" % (\"TIME(s)\", \"COMM\", \"PID\", \"MESSAGE\")) # process event\nstart = 0\ndef print_event(cpu, data, size): global start event = b[\"events\"].event(data) if start == 0: start = event.ts time_s = (float(event.ts - start)) / 1000000000 print(\"%-18.9f %-16s %-6d %s\" % (time_s, event.comm, event.pid, \"Hello, perf_output!\")) # loop with callback to print_event\nb[\"events\"].open_perf_buffer(print_event)\nwhile 1: b.perf_buffer_poll() Things to learn: struct data_t: This defines the C struct we'll use to pass data from kernel to user space. BPF_PERF_OUTPUT(events): This names our output channel \"events\". struct data_t data = {};: Create an empty data_t struct that we'll then populate. bpf_get_current_pid_tgid(): Returns the process ID in the lower 32 bits (kernel's view of the PID, which in user space is usually presented as the thread ID), and the thread group ID in the upper 32 bits (what user space often thinks of as the PID). By directly setting this to a u32, we discard the upper 32 bits. Should you be presenting the PID or the TGID? For a multi-threaded app, the TGID will be the same, so you need the PID to differentiate them, if that's what you want. It's also a question of expectations for the end user. bpf_get_current_comm(): Populates the first argument address with the current process name. events.perf_submit(): Submit the event for user space to read via a perf ring buffer. def print_event(): Define a Python function that will handle reading events from the events stream. b[\"events\"].event(data): Now get the event as a Python object, auto-generated from the C declaration. b[\"events\"].open_perf_buffer(print_event): Associate the Python print_event function with the events stream. while 1: b.perf_buffer_poll(): Block waiting for events.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 7. hello_perf_output.py","id":"284","title":"Lesson 7. hello_perf_output.py"},"285":{"body":"Rewrite sync_timing.py, from a prior lesson, to use BPF_PERF_OUTPUT.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 8. sync_perf_output.py","id":"285","title":"Lesson 8. sync_perf_output.py"},"286":{"body":"The following tool records a histogram of disk I/O sizes. Sample output: # bitehist.py\nTracing... Hit Ctrl-C to end.\n^C kbytes : count distribution 0 -> 1 : 3 | | 2 -> 3 : 0 | | 4 -> 7 : 211 |********** | 8 -> 15 : 0 | | 16 -> 31 : 0 | | 32 -> 63 : 0 | | 64 -> 127 : 1 | | 128 -> 255 : 800 |**************************************| Code is examples/tracing/bitehist.py : from __future__ import print_function\nfrom bcc import BPF\nfrom time import sleep # load BPF program\nb = BPF(text=\"\"\"\n#include \n#include BPF_HISTOGRAM(dist); int kprobe__blk_account_io_done(struct pt_regs *ctx, struct request *req)\n{ dist.increment(bpf_log2l(req->__data_len / 1024)); return 0;\n}\n\"\"\") # header\nprint(\"Tracing... Hit Ctrl-C to end.\") # trace until Ctrl-C\ntry: sleep(99999999)\nexcept KeyboardInterrupt: print() # output\nb[\"dist\"].print_log2_hist(\"kbytes\") A recap from earlier lessons: kprobe__: This prefix means the rest will be treated as a kernel function name that will be instrumented using kprobe. struct pt_regs *ctx, struct request *req: Arguments to kprobe. The ctx is registers and BPF context, the req is the first argument to the instrumented function: blk_account_io_done(). req->__data_len: Dereferencing that member. New things to learn: BPF_HISTOGRAM(dist): Defines a BPF map object that is a histogram, and names it \"dist\". dist.increment(): Increments the histogram bucket index provided as first argument by one by default. Optionally, custom increments can be passed as the second argument. bpf_log2l(): Returns the log-2 of the provided value. This becomes the index of our histogram, so that we're constructing a power-of-2 histogram. b[\"dist\"].print_log2_hist(\"kbytes\"): Prints the \"dist\" histogram as power-of-2, with a column header of \"kbytes\". The only data transferred from kernel to user space is the bucket counts, making this efficient.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 9. bitehist.py","id":"286","title":"Lesson 9. bitehist.py"},"287":{"body":"Write a program that times disk I/O, and prints a histogram of their latency. Disk I/O instrumentation and timing can be found in the disksnoop.py program from a prior lesson, and histogram code can be found in bitehist.py from a prior lesson.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 10. disklatency.py","id":"287","title":"Lesson 10. disklatency.py"},"288":{"body":"This example is split into separate Python and C files. Example output: # vfsreadlat.py 1\nTracing... Hit Ctrl-C to end. usecs : count distribution 0 -> 1 : 0 | | 2 -> 3 : 2 |*********** | 4 -> 7 : 7 |****************************************| 8 -> 15 : 4 |********************** | usecs : count distribution 0 -> 1 : 29 |****************************************| 2 -> 3 : 28 |************************************** | 4 -> 7 : 4 |***** | 8 -> 15 : 8 |*********** | 16 -> 31 : 0 | | 32 -> 63 : 0 | | 64 -> 127 : 0 | | 128 -> 255 : 0 | | 256 -> 511 : 2 |** | 512 -> 1023 : 0 | | 1024 -> 2047 : 0 | | 2048 -> 4095 : 0 | | 4096 -> 8191 : 4 |***** | 8192 -> 16383 : 6 |******** | 16384 -> 32767 : 9 |************ | 32768 -> 65535 : 6 |******** | 65536 -> 131071 : 2 |** | usecs : count distribution 0 -> 1 : 11 |****************************************| 2 -> 3 : 2 |******* | 4 -> 7 : 10 |************************************ | 8 -> 15 : 8 |***************************** | 16 -> 31 : 1 |*** | 32 -> 63 : 2 |******* |\n[...] Browse the code in examples/tracing/vfsreadlat.py and examples/tracing/vfsreadlat.c . Things to learn: b = BPF(src_file = \"vfsreadlat.c\"): Read the BPF C program from a separate source file. b.attach_kretprobe(event=\"vfs_read\", fn_name=\"do_return\"): Attaches the BPF C function do_return() to the return of the kernel function vfs_read(). This is a kretprobe: instrumenting the return from a function, rather than its entry. b[\"dist\"].clear(): Clears the histogram.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 11. vfsreadlat.py","id":"288","title":"Lesson 11. vfsreadlat.py"},"289":{"body":"Tracing while a dd if=/dev/urandom of=/dev/null bs=8k count=5 is run: # urandomread.py\nTIME(s) COMM PID GOTBITS\n24652832.956994001 smtp 24690 384\n24652837.726500999 dd 24692 65536\n24652837.727111001 dd 24692 65536\n24652837.727703001 dd 24692 65536\n24652837.728294998 dd 24692 65536\n24652837.728888001 dd 24692 65536 Hah! I caught smtp by accident. Code is examples/tracing/urandomread.py : from __future__ import print_function\nfrom bcc import BPF # load BPF program\nb = BPF(text=\"\"\"\nTRACEPOINT_PROBE(random, urandom_read) { // args is from /sys/kernel/debug/tracing/events/random/urandom_read/format bpf_trace_printk(\"%d\\\\n\", args->got_bits); return 0;\n}\n\"\"\") # header\nprint(\"%-18s %-16s %-6s %s\" % (\"TIME(s)\", \"COMM\", \"PID\", \"GOTBITS\")) # format output\nwhile 1: try: (task, pid, cpu, flags, ts, msg) = b.trace_fields() except ValueError: continue print(\"%-18.9f %-16s %-6d %s\" % (ts, task, pid, msg)) Things to learn: TRACEPOINT_PROBE(random, urandom_read): Instrument the kernel tracepoint random:urandom_read. These have a stable API, and thus are recommend to use instead of kprobes, wherever possible. You can run perf list for a list of tracepoints. Linux >= 4.7 is required to attach BPF programs to tracepoints. args->got_bits: args is auto-populated to be a structure of the tracepoint arguments. The comment above says where you can see that structure. Eg: # cat /sys/kernel/debug/tracing/events/random/urandom_read/format\nname: urandom_read\nID: 972\nformat: field:unsigned short common_type;\toffset:0;\tsize:2;\tsigned:0; field:unsigned char common_flags;\toffset:2;\tsize:1;\tsigned:0; field:unsigned char common_preempt_count;\toffset:3;\tsize:1;\tsigned:0; field:int common_pid;\toffset:4;\tsize:4;\tsigned:1; field:int got_bits;\toffset:8;\tsize:4;\tsigned:1; field:int pool_left;\toffset:12;\tsize:4;\tsigned:1; field:int input_left;\toffset:16;\tsize:4;\tsigned:1; print fmt: \"got_bits %d nonblocking_pool_entropy_left %d input_entropy_left %d\", REC->got_bits, REC->pool_left, REC->input_left In this case, we were printing the got_bits member.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 12. urandomread.py","id":"289","title":"Lesson 12. urandomread.py"},"29":{"body":"eBPF（Extended Berkeley Packet Filter）是一种内核执行环境，它可以让用户在内核中运行一些安全的、高效的程序。它通常用于网络过滤、性能分析、安全监控等场景。eBPF 之所以强大，是因为它能够在内核运行时捕获和修改数据包或者系统调用，从而实现对操作系统行为的监控和调整。 本文是 eBPF 入门开发实践教程的第四篇，主要介绍如何捕获进程打开文件的系统调用集合，并使用全局变量在 eBPF 中过滤进程 pid。 在 Linux 系统中，进程与文件之间的交互是通过系统调用来实现的。系统调用是用户态程序与内核态程序之间的接口，它们允许用户态程序请求内核执行特定操作。在本教程中，我们关注的是 sys_openat 系统调用，它是用于打开文件的。 当进程打开一个文件时，它会向内核发出 sys_openat 系统调用，并传递相关参数（例如文件路径、打开模式等）。内核会处理这个请求，并返回一个文件描述符（file descriptor），这个描述符将在后续的文件操作中用作引用。通过捕获 sys_openat 系统调用，我们可以了解进程在什么时候以及如何打开文件。","breadcrumbs":"eBPF 入门开发实践教程四：在 eBPF 中捕获进程打开文件的系统调用集合，使用全局变量过滤进程 pid » eBPF 入门开发实践教程四：在 eBPF 中捕获进程打开文件的系统调用集合，使用全局变量过滤进程 pid","id":"29","title":"eBPF 入门开发实践教程四：在 eBPF 中捕获进程打开文件的系统调用集合，使用全局变量过滤进程 pid"},"290":{"body":"Convert disksnoop.py from a previous lesson to use the block:block_rq_issue and block:block_rq_complete tracepoints.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 13. disksnoop.py fixed","id":"290","title":"Lesson 13. disksnoop.py fixed"},"291":{"body":"This program instruments a user-level function, the strlen() library function, and frequency counts its string argument. Example output: # strlen_count.py\nTracing strlen()... Hit Ctrl-C to end.\n^C COUNT STRING 1 \" \" 1 \"/bin/ls\" 1 \".\" 1 \"cpudist.py.1\" 1 \".bashrc\" 1 \"ls --color=auto\" 1 \"key_t\"\n[...] 10 \"a7:~# \" 10 \"/root\" 12 \"LC_ALL\" 12 \"en_US.UTF-8\" 13 \"en_US.UTF-8\" 20 \"~\" 70 \"#%^,~:-=?+/}\" 340 \"\\x01\\x1b]0;root@bgregg-test: ~\\x07\\x02root@bgregg-test:~# \" These are various strings that are being processed by this library function while tracing, along with their frequency counts. strlen() was called on \"LC_ALL\" 12 times, for example. Code is examples/tracing/strlen_count.py : from __future__ import print_function\nfrom bcc import BPF\nfrom time import sleep # load BPF program\nb = BPF(text=\"\"\"\n#include struct key_t { char c[80];\n};\nBPF_HASH(counts, struct key_t); int count(struct pt_regs *ctx) { if (!PT_REGS_PARM1(ctx)) return 0; struct key_t key = {}; u64 zero = 0, *val; bpf_probe_read_user(&key.c, sizeof(key.c), (void *)PT_REGS_PARM1(ctx)); // could also use `counts.increment(key)` val = counts.lookup_or_try_init(&key, &zero); if (val) { (*val)++; } return 0;\n};\n\"\"\")\nb.attach_uprobe(name=\"c\", sym=\"strlen\", fn_name=\"count\") # header\nprint(\"Tracing strlen()... Hit Ctrl-C to end.\") # sleep until Ctrl-C\ntry: sleep(99999999)\nexcept KeyboardInterrupt: pass # print output\nprint(\"%10s %s\" % (\"COUNT\", \"STRING\"))\ncounts = b.get_table(\"counts\")\nfor k, v in sorted(counts.items(), key=lambda counts: counts[1].value): print(\"%10d \\\"%s\\\"\" % (v.value, k.c.encode('string-escape'))) Things to learn: PT_REGS_PARM1(ctx): This fetches the first argument to strlen(), which is the string. b.attach_uprobe(name=\"c\", sym=\"strlen\", fn_name=\"count\"): Attach to library \"c\" (if this is the main program, use its pathname), instrument the user-level function strlen(), and on execution call our C function count().","breadcrumbs":"bcc Python Developer Tutorial » Lesson 14. strlen_count.py","id":"291","title":"Lesson 14. strlen_count.py"},"292":{"body":"This program instruments a user statically-defined tracing (USDT) probe, which is the user-level version of a kernel tracepoint. Sample output: # nodejs_http_server.py 24728\nTIME(s) COMM PID ARGS\n24653324.561322998 node 24728 path:/index.html\n24653335.343401998 node 24728 path:/images/welcome.png\n24653340.510164998 node 24728 path:/images/favicon.png Relevant code from examples/tracing/nodejs_http_server.py : from __future__ import print_function\nfrom bcc import BPF, USDT\nimport sys if len(sys.argv) < 2: print(\"USAGE: nodejs_http_server PID\") exit()\npid = sys.argv[1]\ndebug = 0 # load BPF program\nbpf_text = \"\"\"\n#include \nint do_trace(struct pt_regs *ctx) { uint64_t addr; char path[128]={0}; bpf_usdt_readarg(6, ctx, &addr); bpf_probe_read_user(&path, sizeof(path), (void *)addr); bpf_trace_printk(\"path:%s\\\\n\", path); return 0;\n};\n\"\"\" # enable USDT probe from given PID\nu = USDT(pid=int(pid))\nu.enable_probe(probe=\"http__server__request\", fn_name=\"do_trace\")\nif debug: print(u.get_text()) print(bpf_text) # initialize BPF\nb = BPF(text=bpf_text, usdt_contexts=[u]) Things to learn: bpf_usdt_readarg(6, ctx, &addr): Read the address of argument 6 from the USDT probe into addr. bpf_probe_read_user(&path, sizeof(path), (void *)addr): Now the string addr points to into our path variable. u = USDT(pid=int(pid)): Initialize USDT tracing for the given PID. u.enable_probe(probe=\"http__server__request\", fn_name=\"do_trace\"): Attach our do_trace() BPF C function to the Node.js http__server__request USDT probe. b = BPF(text=bpf_text, usdt_contexts=[u]): Need to pass in our USDT object, u, to BPF object creation.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 15. nodejs_http_server.py","id":"292","title":"Lesson 15. nodejs_http_server.py"},"293":{"body":"This is an older tutorial included as a bonus lesson. Use this for recap and to reinforce what you've already learned. This is a slightly more complex tracing example than Hello World. This program will be invoked for every task change in the kernel, and record in a BPF map the new and old pids. The C program below introduces a new concept: the prev argument. This argument is treated specially by the BCC frontend, such that accesses to this variable are read from the saved context that is passed by the kprobe infrastructure. The prototype of the args starting from position 1 should match the prototype of the kernel function being kprobed. If done so, the program will have seamless access to the function parameters. #include \n#include struct key_t { u32 prev_pid; u32 curr_pid;\n}; BPF_HASH(stats, struct key_t, u64, 1024);\nint count_sched(struct pt_regs *ctx, struct task_struct *prev) { struct key_t key = {}; u64 zero = 0, *val; key.curr_pid = bpf_get_current_pid_tgid(); key.prev_pid = prev->pid; // could also use `stats.increment(key);` val = stats.lookup_or_try_init(&key, &zero); if (val) { (*val)++; } return 0;\n} The userspace component loads the file shown above, and attaches it to the finish_task_switch kernel function. The [] operator of the BPF object gives access to each BPF_HASH in the program, allowing pass-through access to the values residing in the kernel. Use the object as you would any other python dict object: read, update, and deletes are all allowed. from bcc import BPF\nfrom time import sleep b = BPF(src_file=\"task_switch.c\")\nb.attach_kprobe(event=\"finish_task_switch\", fn_name=\"count_sched\") # generate many schedule events\nfor i in range(0, 100): sleep(0.01) for k, v in b[\"stats\"].items(): print(\"task_switch[%5d->%5d]=%u\" % (k.prev_pid, k.curr_pid, v.value)) These programs can be found in the files examples/tracing/task_switch.c and examples/tracing/task_switch.py respectively.","breadcrumbs":"bcc Python Developer Tutorial » Lesson 16. task_switch.c","id":"293","title":"Lesson 16. task_switch.c"},"294":{"body":"For further study, see Sasha Goldshtein's linux-tracing-workshop , which contains additional labs. There are also many tools in bcc /tools to study. Please read CONTRIBUTING-SCRIPTS.md if you wish to contribute tools to bcc. At the bottom of the main README.md , you'll also find methods for contacting us. Good luck, and happy tracing!","breadcrumbs":"bcc Python Developer Tutorial » Lesson 17. Further Study","id":"294","title":"Lesson 17. Further Study"},"295":{"body":"To do.","breadcrumbs":"bcc Python Developer Tutorial » Networking","id":"295","title":"Networking"},"3":{"body":"本文不会对 eBPF 的原理做更详细的介绍，不过这里有一个学习规划和参考资料，也许会有一些价值：","breadcrumbs":"eBPF 入门开发实践教程一：介绍 eBPF 的基本概念、常见的开发工具 » 2. 关于如何学习 eBPF 相关的开发的一些建议","id":"3","title":"2. 关于如何学习 eBPF 相关的开发的一些建议"},"30":{"body":"首先，我们需要编写一段 eBPF 程序来捕获进程打开文件的系统调用，具体实现如下： #include \n#include /// @description \"Process ID to trace\"\nconst volatile int pid_target = 0; SEC(\"tracepoint/syscalls/sys_enter_openat\")\nint tracepoint__syscalls__sys_enter_openat(struct trace_event_raw_sys_enter* ctx)\n{ u64 id = bpf_get_current_pid_tgid(); u32 pid = id; if (pid_target && pid_target != pid) return false; // Use bpf_printk to print the process information bpf_printk(\"Process ID: %d enter sys openat\\n\", pid); return 0;\n} /// \"Trace open family syscalls.\"\nchar LICENSE[] SEC(\"license\") = \"GPL\"; 这段 eBPF 程序实现了： 引入头文件： 包含了内核数据结构的定义， 包含了 eBPF 程序所需的辅助函数。 定义全局变量 pid_target，用于过滤指定进程 ID。这里设为 0 表示捕获所有进程的 sys_openat 调用。 使用 SEC 宏定义一个 eBPF 程序，关联到 tracepoint \"tracepoint/syscalls/sys_enter_openat\"。这个 tracepoint 会在进程发起 sys_openat 系统调用时触发。 实现 eBPF 程序 tracepoint__syscalls__sys_enter_openat，它接收一个类型为 struct trace_event_raw_sys_enter 的参数 ctx。这个结构体包含了关于系统调用的信息。 使用 bpf_get_current_pid_tgid() 函数获取当前进程的 PID 和 TGID（线程组 ID）。由于我们只关心 PID，所以将其赋值给 u32 类型的变量 pid。 检查 pid_target 变量是否与当前进程的 pid 相等。如果 pid_target 不为 0 且与当前进程的 pid 不相等，则返回 false，不对该进程的 sys_openat 调用进行捕获。 使用 bpf_printk() 函数打印捕获到的进程 ID 和 sys_openat 调用的相关信息。这些信息将在用户空间通过 BPF 工具查看。 将程序许可证设置为 \"GPL\"，这是运行 eBPF 程序的必要条件。 这个 eBPF 程序可以通过 libbpf 或 eunomia-bpf 等工具加载到内核并执行。它将捕获指定进程（或所有进程）的 sys_openat 系统调用，并在用户空间输出相关信息。 eunomia-bpf 是一个结合 Wasm 的开源 eBPF 动态加载运行时和开发工具链，它的目的是简化 eBPF 程序的开发、构建、分发、运行。可以参考 https://github.com/eunomia-bpf/eunomia-bpf 下载和安装 ecc 编译工具链和 ecli 运行时。我们使用 eunomia-bpf 编译运行这个例子。 编译运行上述代码： $ ecc opensnoop.bpf.c\nCompiling bpf object...\nPacking ebpf object and config into package.json...\n$ sudo ecli run package.json\nRuning eBPF program... 运行这段程序后，可以通过查看 /sys/kernel/debug/tracing/trace_pipe 文件来查看 eBPF 程序的输出： $ sudo cat /sys/kernel/debug/tracing/trace_pipe <...>-3840345 [010] d... 3220701.101179: bpf_trace_printk: Process ID: 3840345 enter sys openat <...>-3840345 [010] d... 3220702.158000: bpf_trace_printk: Process ID: 3840345 enter sys openat 此时，我们已经能够捕获进程打开文件的系统调用了。","breadcrumbs":"eBPF 入门开发实践教程四：在 eBPF 中捕获进程打开文件的系统调用集合，使用全局变量过滤进程 pid » 在 eBPF 中捕获进程打开文件的系统调用集合","id":"30","title":"在 eBPF 中捕获进程打开文件的系统调用集合"},"31":{"body":"全局变量在 eBPF 程序中充当一种数据共享机制，它们允许用户态程序与 eBPF 程序之间进行数据交互。这在过滤特定条件或修改 eBPF 程序行为时非常有用。这种设计使得用户态程序能够在运行时动态地控制 eBPF 程序的行为。 在我们的例子中，全局变量 pid_target 用于过滤进程 PID。用户态程序可以设置此变量的值，以便在 eBPF 程序中只捕获与指定 PID 相关的 sys_openat 系统调用。 使用全局变量的原理是，全局变量在 eBPF 程序的数据段（data section）中定义并存储。当 eBPF 程序加载到内核并执行时，这些全局变量会保持在内核中，可以通过 BPF 系统调用进行访问。用户态程序可以使用 BPF 系统调用中的某些特性，如 bpf_obj_get_info_by_fd 和 bpf_obj_get_info，获取 eBPF 对象的信息，包括全局变量的位置和值。 可以通过执行 ecli -h 命令来查看 opensnoop 的帮助信息： $ ecli package.json -h\nUsage: opensnoop_bpf [--help] [--version] [--verbose] [--pid_target VAR] Trace open family syscalls. Optional arguments: -h, --help shows help message and exits -v, --version prints version information and exits --verbose prints libbpf debug information --pid_target Process ID to trace Built with eunomia-bpf framework.\nSee https://github.com/eunomia-bpf/eunomia-bpf for more information. 可以通过 --pid_target 参数来指定要捕获的进程的 pid，例如： $ sudo ./ecli run package.json --pid_target 618\nRuning eBPF program... 运行这段程序后，可以通过查看 /sys/kernel/debug/tracing/trace_pipe 文件来查看 eBPF 程序的输出： $ sudo cat /sys/kernel/debug/tracing/trace_pipe <...>-3840345 [010] d... 3220701.101179: bpf_trace_printk: Process ID: 618 enter sys openat <...>-3840345 [010] d... 3220702.158000: bpf_trace_printk: Process ID: 618 enter sys openat","breadcrumbs":"eBPF 入门开发实践教程四：在 eBPF 中捕获进程打开文件的系统调用集合，使用全局变量过滤进程 pid » 使用全局变量在 eBPF 中过滤进程 pid","id":"31","title":"使用全局变量在 eBPF 中过滤进程 pid"},"32":{"body":"本文介绍了如何使用 eBPF 程序来捕获进程打开文件的系统调用。在 eBPF 程序中，我们可以通过定义 tracepoint__syscalls__sys_enter_open 和 tracepoint__syscalls__sys_enter_openat 函数并使用 SEC 宏把它们附加到 sys_enter_open 和 sys_enter_openat 两个 tracepoint 来捕获进程打开文件的系统调用。我们可以使用 bpf_get_current_pid_tgid 函数获取调用 open 或 openat 系统调用的进程 ID，并使用 bpf_printk 函数在内核日志中打印出来。在 eBPF 程序中，我们还可以通过定义一个全局变量 pid_target 来指定要捕获的进程的 pid，从而过滤输出，只输出指定的进程的信息。 通过学习本教程，您应该对如何在 eBPF 中捕获和过滤特定进程的系统调用有了更深入的了解。这种方法在系统监控、性能分析和安全审计等场景中具有广泛的应用。 更多的例子和详细的开发指南，请参考 eunomia-bpf 的官方文档： https://github.com/eunomia-bpf/eunomia-bpf 完整的教程和源代码已经全部开源，可以在 https://github.com/eunomia-bpf/bpf-developer-tutorial 中查看。","breadcrumbs":"eBPF 入门开发实践教程四：在 eBPF 中捕获进程打开文件的系统调用集合，使用全局变量过滤进程 pid » 总结","id":"32","title":"总结"},"33":{"body":"eBPF (Extended Berkeley Packet Filter) 是 Linux 内核上的一个强大的网络和性能分析工具，它允许开发者在内核运行时动态加载、更新和运行用户定义的代码。 本文是 eBPF 入门开发实践教程的第五篇，主要介绍如何使用 uprobe 捕获 bash 的 readline 函数调用。","breadcrumbs":"eBPF 入门开发实践教程五：在 eBPF 中使用 uprobe 捕获 bash 的 readline 函数调用 » eBPF 入门开发实践教程五：在 eBPF 中使用 uprobe 捕获 bash 的 readline 函数调用","id":"33","title":"eBPF 入门开发实践教程五：在 eBPF 中使用 uprobe 捕获 bash 的 readline 函数调用"},"34":{"body":"uprobe是一种用户空间探针，uprobe探针允许在用户空间程序中动态插桩，插桩位置包括：函数入口、特定偏移处，以及函数返回处。当我们定义uprobe时，内核会在附加的指令上创建快速断点指令（x86机器上为int3指令），当程序执行到该指令时，内核将触发事件，程序陷入到内核态，并以回调函数的方式调用探针函数，执行完探针函数再返回到用户态继续执行后序的指令。 uprobe基于文件，当一个二进制文件中的一个函数被跟踪时，所有使用到这个文件的进程都会被插桩，包括那些尚未启动的进程，这样就可以在全系统范围内跟踪系统调用。 uprobe适用于在用户态去解析一些内核态探针无法解析的流量，例如http2流量（报文header被编码，内核无法解码），https流量（加密流量，内核无法解密）。","breadcrumbs":"eBPF 入门开发实践教程五：在 eBPF 中使用 uprobe 捕获 bash 的 readline 函数调用 » 什么是uprobe","id":"34","title":"什么是uprobe"},"35":{"body":"uprobe 是一种用于捕获用户空间函数调用的 eBPF 的探针，我们可以通过它来捕获用户空间程序调用的系统函数。 例如，我们可以使用 uprobe 来捕获 bash 的 readline 函数调用，从而获取用户在 bash 中输入的命令行。示例代码如下： #include \n#include \n#include #define TASK_COMM_LEN 16\n#define MAX_LINE_SIZE 80 /* Format of u[ret]probe section definition supporting auto-attach: * u[ret]probe/binary:function[+offset] * * binary can be an absolute/relative path or a filename; the latter is resolved to a * full binary path via bpf_program__attach_uprobe_opts. * * Specifying uprobe+ ensures we carry out strict matching; either \"uprobe\" must be * specified (and auto-attach is not possible) or the above format is specified for * auto-attach. */\nSEC(\"uretprobe//bin/bash:readline\")\nint BPF_KRETPROBE(printret, const void *ret)\n{ char str[MAX_LINE_SIZE]; char comm[TASK_COMM_LEN]; u32 pid; if (!ret) return 0; bpf_get_current_comm(&comm, sizeof(comm)); pid = bpf_get_current_pid_tgid() >> 32; bpf_probe_read_user_str(str, sizeof(str), ret); bpf_printk(\"PID %d (%s) read: %s \", pid, comm, str); return 0;\n}; char LICENSE[] SEC(\"license\") = \"GPL\"; 这段代码的作用是在 bash 的 readline 函数返回时执行指定的 BPF_KRETPROBE 函数，即 printret 函数。 在 printret 函数中，我们首先获取了调用 readline 函数的进程的进程名称和进程 ID，然后通过 bpf_probe_read_user_str 函数读取了用户输入的命令行字符串，最后通过 bpf_printk 函数打印出进程 ID、进程名称和输入的命令行字符串。 除此之外，我们还需要通过 SEC 宏来定义 uprobe 探针，并使用 BPF_KRETPROBE 宏来定义探针函数。 在 SEC 宏中，我们需要指定 uprobe 的类型、要捕获的二进制文件的路径和要捕获的函数名称。例如，上面的代码中的 SEC 宏的定义如下： SEC(\"uprobe//bin/bash:readline\") 这表示我们要捕获的是 /bin/bash 二进制文件中的 readline 函数。 接下来，我们需要使用 BPF_KRETPROBE 宏来定义探针函数，例如： BPF_KRETPROBE(printret, const void *ret) 这里的 printret 是探针函数的名称，const void *ret 是探针函数的参数，它代表被捕获的函数的返回值。 然后，我们使用了 bpf_get_current_comm 函数获取当前任务的名称，并将其存储在 comm 数组中。 bpf_get_current_comm(&comm, sizeof(comm)); 使用 bpf_get_current_pid_tgid 函数获取当前进程的 PID，并将其存储在 pid 变量中。 pid = bpf_get_current_pid_tgid() >> 32; 使用 bpf_probe_read_user_str 函数从用户空间读取 readline 函数的返回值，并将其存储在 str 数组中。 bpf_probe_read_user_str(str, sizeof(str), ret); 最后使用 bpf_printk 函数输出 PID、任务名称和用户输入的字符串。 bpf_printk(\"PID %d (%s) read: %s \", pid, comm, str); eunomia-bpf 是一个结合 Wasm 的开源 eBPF 动态加载运行时和开发工具链，它的目的是简化 eBPF 程序的开发、构建、分发、运行。可以参考 https://github.com/eunomia-bpf/eunomia-bpf 下载和安装 ecc 编译工具链和 ecli 运行时。我们使用 eunomia-bpf 编译运行这个例子。 编译运行上述代码： $ ecc bashreadline.bpf.c\nCompiling bpf object...\nPacking ebpf object and config into package.json...\n$ sudo ecli run package.json\nRuning eBPF program... 运行这段程序后，可以通过查看 /sys/kernel/debug/tracing/trace_pipe 文件来查看 eBPF 程序的输出： $ sudo cat /sys/kernel/debug/tracing/trace_pipe bash-32969 [000] d..31 64001.375748: bpf_trace_printk: PID 32969 (bash) read: fff bash-32969 [000] d..31 64002.056951: bpf_trace_printk: PID 32969 (bash) read: fff 可以看到，我们成功的捕获了 bash 的 readline 函数调用，并获取了用户在 bash 中输入的命令行。","breadcrumbs":"eBPF 入门开发实践教程五：在 eBPF 中使用 uprobe 捕获 bash 的 readline 函数调用 » 使用 uprobe 捕获 bash 的 readline 函数调用","id":"35","title":"使用 uprobe 捕获 bash 的 readline 函数调用"},"36":{"body":"在上述代码中，我们使用了 SEC 宏来定义了一个 uprobe 探针，它指定了要捕获的用户空间程序 (bin/bash) 和要捕获的函数 (readline)。此外，我们还使用了 BPF_KRETPROBE 宏来定义了一个用于处理 readline 函数返回值的回调函数 (printret)。该函数可以获取到 readline 函数的返回值，并将其打印到内核日志中。通过这样的方式，我们就可以使用 eBPF 来捕获 bash 的 readline 函数调用，并获取用户在 bash 中输入的命令行。 更多的例子和详细的开发指南，请参考 eunomia-bpf 的官方文档： https://github.com/eunomia-bpf/eunomia-bpf 完整的教程和源代码已经全部开源，可以在 https://github.com/eunomia-bpf/bpf-developer-tutorial 中查看。","breadcrumbs":"eBPF 入门开发实践教程五：在 eBPF 中使用 uprobe 捕获 bash 的 readline 函数调用 » 总结","id":"36","title":"总结"},"37":{"body":"eBPF (Extended Berkeley Packet Filter) 是 Linux 内核上的一个强大的网络和性能分析工具，它允许开发者在内核运行时动态加载、更新和运行用户定义的代码。 本文是 eBPF 入门开发实践教程的第六篇，主要介绍如何实现一个 eBPF 工具，捕获进程发送信号的系统调用集合，使用 hash map 保存状态。","breadcrumbs":"eBPF 入门开发实践教程六：捕获进程发送信号的系统调用集合，使用 hash map 保存状态 » eBPF 入门开发实践教程六：捕获进程发送信号的系统调用集合，使用 hash map 保存状态","id":"37","title":"eBPF 入门开发实践教程六：捕获进程发送信号的系统调用集合，使用 hash map 保存状态"},"38":{"body":"示例代码如下： #include \n#include \n#include 