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add the compile method of profile (#30)

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try-agaaain
2023-04-29 16:50:34 +08:00
committed by GitHub
parent 39a0f4a1a7
commit f91e119b81
3 changed files with 109 additions and 37 deletions
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78
src/12-profile/README.md
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@@ -50,55 +50,59 @@ static int open_and_attach_perf_event(int freq, struct bpf_program *prog,
其ebpf程序实现逻辑是对程序的堆栈进行定时采样，从而捕获程序的执行流程。
```c
SEC("perf_event")
int do_perf_event(struct bpf_perf_event_data *ctx)
int profile(void *ctx)
{
__u64 id = bpf_get_current_pid_tgid();
__u32 pid = id >> 32;
__u32 tid = id;
__u64 *valp;
static const __u64 zero;
struct key_t key = {};
int pid = bpf_get_current_pid_tgid() >> 32;
int cpu_id = bpf_get_smp_processor_id();
struct stacktrace_event *event;
int cp;
if (!include_idle && tid == 0)
return 0;
event = bpf_ringbuf_reserve(&events, sizeof(*event), 0);
if (!event)
return 1;
if (targ_pid != -1 && targ_pid != pid)
return 0;
if (targ_tid != -1 && targ_tid != tid)
return 0;
event->pid = pid;
event->cpu_id = cpu_id;
key.pid = pid;
bpf_get_current_comm(&key.name, sizeof(key.name));
if (bpf_get_current_comm(event->comm, sizeof(event->comm)))
event->comm[0] = 0;
if (user_stacks_only)
key.kern_stack_id = -1;
else
key.kern_stack_id = bpf_get_stackid(&ctx->regs, &stackmap, 0);
event->kstack_sz = bpf_get_stack(ctx, event->kstack, sizeof(event->kstack), 0);
if (kernel_stacks_only)
key.user_stack_id = -1;
else
key.user_stack_id = bpf_get_stackid(&ctx->regs, &stackmap, BPF_F_USER_STACK);
event->ustack_sz = bpf_get_stack(ctx, event->ustack, sizeof(event->ustack), BPF_F_USER_STACK);
if (key.kern_stack_id >= 0) {
// populate extras to fix the kernel stack
__u64 ip = PT_REGS_IP(&ctx->regs);
if (is_kernel_addr(ip)) {
key.kernel_ip = ip;
}
}
valp = bpf_map_lookup_or_try_init(&counts, &key, &zero);
if (valp)
__sync_fetch_and_add(valp, 1);
bpf_ringbuf_submit(event, 0);
return 0;
}
```
通过这种方式，它可以根据用户指令，简单的决定追踪用户态层面的执行流程或是内核态层面的执行流程。
### Eunomia中使用方式
### 编译运行
```console
$ git clone https://github.com/libbpf/libbpf-bootstrap.git --recurse-submodules
$ cd examples/c
$ make profile
$ sudo ./profile
COMM: chronyd (pid=156) @ CPU 1
Kernel:
0 [<ffffffff81ee9f56>] _raw_spin_lock_irqsave+0x16
1 [<ffffffff811527b4>] remove_wait_queue+0x14
2 [<ffffffff8132611d>] poll_freewait+0x3d
3 [<ffffffff81326d3f>] do_select+0x7bf
4 [<ffffffff81327af2>] core_sys_select+0x182
5 [<ffffffff81327f3a>] __x64_sys_pselect6+0xea
6 [<ffffffff81ed9e38>] do_syscall_64+0x38
7 [<ffffffff82000099>] entry_SYSCALL_64_after_hwframe+0x61
Userspace:
0 [<00007fab187bfe09>]
1 [<000000000ee6ae98>]
COMM: profile (pid=9843) @ CPU 6
No Kernel Stack
Userspace:
0 [<0000556deb068ac8>]
1 [<0000556dec34cad0>]
```
### 总结
`profile` 实现了对程序执行流程的分析，在debug等操作中可以极大的帮助开发者提高效率。
`profile` 实现了对程序执行流程的分析，在debug等操作中可以极大的帮助开发者提高效率。

42
src/12-profile/profile.bpf.c Normal file
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@@ -0,0 +1,42 @@
// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/* Copyright (c) 2022 Meta Platforms, Inc. */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_core_read.h>
#include "profile.h"
char LICENSE[] SEC("license") = "Dual BSD/GPL";
struct {
__uint(type, BPF_MAP_TYPE_RINGBUF);
__uint(max_entries, 256 * 1024);
} events SEC(".maps");
SEC("perf_event")
int profile(void *ctx)
{
int pid = bpf_get_current_pid_tgid() >> 32;
int cpu_id = bpf_get_smp_processor_id();
struct stacktrace_event *event;
int cp;
event = bpf_ringbuf_reserve(&events, sizeof(*event), 0);
if (!event)
return 1;
event->pid = pid;
event->cpu_id = cpu_id;
if (bpf_get_current_comm(event->comm, sizeof(event->comm)))
event->comm[0] = 0;
event->kstack_sz = bpf_get_stack(ctx, event->kstack, sizeof(event->kstack), 0);
event->ustack_sz = bpf_get_stack(ctx, event->ustack, sizeof(event->ustack), BPF_F_USER_STACK);
bpf_ringbuf_submit(event, 0);
return 0;
}

26
src/12-profile/profile.h Normal file
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@@ -0,0 +1,26 @@
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
/* Copyright (c) 2022 Meta Platforms, Inc. */
#ifndef __PROFILE_H_
#define __PROFILE_H_
#ifndef TASK_COMM_LEN
#define TASK_COMM_LEN 16
#endif
#ifndef MAX_STACK_DEPTH
#define MAX_STACK_DEPTH 128
#endif
typedef __u64 stack_trace_t[MAX_STACK_DEPTH];
struct stacktrace_event {
__u32 pid;
__u32 cpu_id;
char comm[TASK_COMM_LEN];
__s32 kstack_sz;
__s32 ustack_sz;
stack_trace_t kstack;
stack_trace_t ustack;
};
#endif /* __PROFILE_H_ */