add user_ring_buffer example

src/35-user-ringbuf/.gitignore

@@ -0,0 +1,8 @@
+.vscode
+package.json
+*.o
+*.skel.json
+*.skel.yaml
+package.yaml
+ecli
+user_ringbuf

src/35-user-ringbuf/Makefile

@@ -0,0 +1,141 @@
+# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+OUTPUT := .output
+CLANG ?= clang
+LIBBPF_SRC := $(abspath ../third_party/libbpf/src)
+BPFTOOL_SRC := $(abspath ../third_party/bpftool/src)
+LIBBPF_OBJ := $(abspath $(OUTPUT)/libbpf.a)
+BPFTOOL_OUTPUT ?= $(abspath $(OUTPUT)/bpftool)
+BPFTOOL ?= $(BPFTOOL_OUTPUT)/bootstrap/bpftool
+LIBBLAZESYM_SRC := $(abspath ../third_party/blazesym/)
+LIBBLAZESYM_OBJ := $(abspath $(OUTPUT)/libblazesym.a)
+LIBBLAZESYM_HEADER := $(abspath $(OUTPUT)/blazesym.h)
+ARCH ?= $(shell uname -m | sed 's/x86_64/x86/' \
+			 | sed 's/arm.*/arm/' \
+			 | sed 's/aarch64/arm64/' \
+			 | sed 's/ppc64le/powerpc/' \
+			 | sed 's/mips.*/mips/' \
+			 | sed 's/riscv64/riscv/' \
+			 | sed 's/loongarch64/loongarch/')
+VMLINUX := ../third_party/vmlinux/$(ARCH)/vmlinux.h
+# Use our own libbpf API headers and Linux UAPI headers distributed with
+# libbpf to avoid dependency on system-wide headers, which could be missing or
+# outdated
+INCLUDES := -I$(OUTPUT) -I../third_party/libbpf/include/uapi -I$(dir $(VMLINUX))
+CFLAGS := -g -Wall
+ALL_LDFLAGS := $(LDFLAGS) $(EXTRA_LDFLAGS)
+
+APPS = user_ringbuf # minimal minimal_legacy uprobe kprobe fentry usdt sockfilter tc ksyscall
+
+CARGO ?= $(shell which cargo)
+ifeq ($(strip $(CARGO)),)
+BZS_APPS :=
+else
+BZS_APPS := # profile
+APPS += $(BZS_APPS)
+# Required by libblazesym
+ALL_LDFLAGS += -lrt -ldl -lpthread -lm
+endif
+
+# Get Clang's default includes on this system. We'll explicitly add these dirs
+# to the includes list when compiling with `-target bpf` because otherwise some
+# architecture-specific dirs will be "missing" on some architectures/distros -
+# headers such as asm/types.h, asm/byteorder.h, asm/socket.h, asm/sockios.h,
+# sys/cdefs.h etc. might be missing.
+#
+# Use '-idirafter': Don't interfere with include mechanics except where the
+# build would have failed anyways.
+CLANG_BPF_SYS_INCLUDES ?= $(shell $(CLANG) -v -E - </dev/null 2>&1 \
+	| sed -n '/<...> search starts here:/,/End of search list./{ s| \(/.*\)|-idirafter \1|p }')
+
+ifeq ($(V),1)
+	Q =
+	msg =
+else
+	Q = @
+	msg = @printf '  %-8s %s%s\n'					\
+		      "$(1)"						\
+		      "$(patsubst $(abspath $(OUTPUT))/%,%,$(2))"	\
+		      "$(if $(3), $(3))";
+	MAKEFLAGS += --no-print-directory
+endif
+
+define allow-override
+  $(if $(or $(findstring environment,$(origin $(1))),\
+            $(findstring command line,$(origin $(1)))),,\
+    $(eval $(1) = $(2)))
+endef
+
+$(call allow-override,CC,$(CROSS_COMPILE)cc)
+$(call allow-override,LD,$(CROSS_COMPILE)ld)
+
+.PHONY: all
+all: $(APPS)
+
+.PHONY: clean
+clean:
+	$(call msg,CLEAN)
+	$(Q)rm -rf $(OUTPUT) $(APPS)
+
+$(OUTPUT) $(OUTPUT)/libbpf $(BPFTOOL_OUTPUT):
+	$(call msg,MKDIR,$@)
+	$(Q)mkdir -p $@
+
+# Build libbpf
+$(LIBBPF_OBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(OUTPUT)/libbpf
+	$(call msg,LIB,$@)
+	$(Q)$(MAKE) -C $(LIBBPF_SRC) BUILD_STATIC_ONLY=1		      \
+		    OBJDIR=$(dir $@)/libbpf DESTDIR=$(dir $@)		      \
+		    INCLUDEDIR= LIBDIR= UAPIDIR=			      \
+		    install
+
+# Build bpftool
+$(BPFTOOL): | $(BPFTOOL_OUTPUT)
+	$(call msg,BPFTOOL,$@)
+	$(Q)$(MAKE) ARCH= CROSS_COMPILE= OUTPUT=$(BPFTOOL_OUTPUT)/ -C $(BPFTOOL_SRC) bootstrap
+
+
+$(LIBBLAZESYM_SRC)/target/release/libblazesym.a::
+	$(Q)cd $(LIBBLAZESYM_SRC) && $(CARGO) build --features=cheader,dont-generate-test-files --release
+
+$(LIBBLAZESYM_OBJ): $(LIBBLAZESYM_SRC)/target/release/libblazesym.a | $(OUTPUT)
+	$(call msg,LIB, $@)
+	$(Q)cp $(LIBBLAZESYM_SRC)/target/release/libblazesym.a $@
+
+$(LIBBLAZESYM_HEADER): $(LIBBLAZESYM_SRC)/target/release/libblazesym.a | $(OUTPUT)
+	$(call msg,LIB,$@)
+	$(Q)cp $(LIBBLAZESYM_SRC)/target/release/blazesym.h $@
+
+# Build BPF code
+$(OUTPUT)/%.bpf.o: %.bpf.c $(LIBBPF_OBJ) $(wildcard %.h) $(VMLINUX) | $(OUTPUT) $(BPFTOOL)
+	$(call msg,BPF,$@)
+	$(Q)$(CLANG) -g -O2 -target bpf -D__TARGET_ARCH_$(ARCH)		      \
+		     $(INCLUDES) $(CLANG_BPF_SYS_INCLUDES)		      \
+		     -c $(filter %.c,$^) -o $(patsubst %.bpf.o,%.tmp.bpf.o,$@)
+	$(Q)$(BPFTOOL) gen object $@ $(patsubst %.bpf.o,%.tmp.bpf.o,$@)
+
+# Generate BPF skeletons
+$(OUTPUT)/%.skel.h: $(OUTPUT)/%.bpf.o | $(OUTPUT) $(BPFTOOL)
+	$(call msg,GEN-SKEL,$@)
+	$(Q)$(BPFTOOL) gen skeleton $< > $@
+
+# Build user-space code
+$(patsubst %,$(OUTPUT)/%.o,$(APPS)): %.o: %.skel.h
+
+$(OUTPUT)/%.o: %.c $(wildcard %.h) | $(OUTPUT)
+	$(call msg,CC,$@)
+	$(Q)$(CC) $(CFLAGS) $(INCLUDES) -c $(filter %.c,$^) -o $@
+
+$(patsubst %,$(OUTPUT)/%.o,$(BZS_APPS)): $(LIBBLAZESYM_HEADER)
+
+$(BZS_APPS): $(LIBBLAZESYM_OBJ)
+
+# Build application binary
+$(APPS): %: $(OUTPUT)/%.o $(LIBBPF_OBJ) | $(OUTPUT)
+	$(call msg,BINARY,$@)
+	$(Q)$(CC) $(CFLAGS) $^ $(ALL_LDFLAGS) -lelf -lz -o $@
+
+# delete failed targets
+.DELETE_ON_ERROR:
+
+# keep intermediate (.skel.h, .bpf.o, etc) targets
+.SECONDARY:

src/35-user-ringbuf/user_ringbuf.bpf.c

@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+#include "user_ringbuf.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+	__uint(type, BPF_MAP_TYPE_USER_RINGBUF);
+	__uint(max_entries, 256 * 1024);
+} user_ringbuf SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_RINGBUF);
+	__uint(max_entries, 256 * 1024);
+} kernel_ringbuf SEC(".maps");
+
+int read = 0;
+
+static long
+do_nothing_cb(struct bpf_dynptr *dynptr, void *context)
+{
+	struct event *e;
+	pid_t pid;
+	/* get PID and TID of exiting thread/process */
+	pid = bpf_get_current_pid_tgid() >> 32;
+
+	/* reserve sample from BPF ringbuf */
+	e = bpf_ringbuf_reserve(&kernel_ringbuf, sizeof(*e), 0);
+	if (!e)
+		return 0;
+
+	e->pid = pid;
+	bpf_get_current_comm(&e->comm, sizeof(e->comm));
+
+	/* send data to user-space for post-processing */
+	bpf_ringbuf_submit(e, 0);
+	__sync_fetch_and_add(&read, 1);
+	return 0;
+}
+
+SEC("tracepoint/syscalls/sys_exit_kill")
+int kill_exit(struct trace_event_raw_sys_exit *ctx)
+{
+	long num_samples;
+	int err = 0;
+
+	num_samples = bpf_user_ringbuf_drain(&user_ringbuf, do_nothing_cb, NULL, 0);
+
+	return 0;
+}

src/35-user-ringbuf/user_ringbuf.c

@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2020 Facebook */
+#include <argp.h>
+#include <signal.h>
+#include <stdio.h>
+#include <time.h>
+#include <sys/resource.h>
+#include <bpf/libbpf.h>
+#include "user_ringbuf.h"
+#include "user_ringbuf.skel.h"
+
+static void drain_current_samples(void)
+{
+	printf("Draining current samples...\n");
+}
+
+static int write_samples(struct user_ring_buffer *ringbuf)
+{
+	int i, err = 0;
+	struct user_sample *entry;
+
+	entry = user_ring_buffer__reserve(ringbuf, sizeof(*entry));
+	if (!entry) {
+		err = -errno;
+		goto done;
+	}
+
+		entry->i = getpid();
+		strcpy(entry->comm, "hello");
+
+		int read = snprintf(entry->comm, sizeof(entry->comm), "%u", i);
+		if (read <= 0) {
+			/* Assert on the error path to avoid spamming logs with
+			 * mostly success messages.
+			 */
+			err = read;
+			user_ring_buffer__discard(ringbuf, entry);
+			goto done;
+		}
+
+		user_ring_buffer__submit(ringbuf, entry);
+
+done:
+	drain_current_samples();
+
+	return err;
+}
+
+static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
+{
+	return vfprintf(stderr, format, args);
+}
+
+static volatile bool exiting = false;
+
+static void sig_handler(int sig)
+{
+	exiting = true;
+}
+
+	struct user_ring_buffer *user_ringbuf = NULL;
+
+static int handle_event(void *ctx, void *data, size_t data_sz)
+{
+	const struct event *e = data;
+	struct tm *tm;
+	char ts[32];
+	time_t t;
+
+	time(&t);
+	tm = localtime(&t);
+	strftime(ts, sizeof(ts), "%H:%M:%S", tm);
+
+		printf("%-8s %-5s %-16s %-7d\n",
+		       ts, "SIGN", e->comm, e->pid);
+	write_samples(user_ringbuf);
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	struct ring_buffer *rb = NULL;
+	struct user_ringbuf_bpf *skel;
+	int err;
+
+	/* Set up libbpf errors and debug info callback */
+	libbpf_set_print(libbpf_print_fn);
+
+	/* Cleaner handling of Ctrl-C */
+	signal(SIGINT, sig_handler);
+	signal(SIGTERM, sig_handler);
+
+	/* Load and verify BPF application */
+	skel = user_ringbuf_bpf__open();
+	if (!skel) {
+		fprintf(stderr, "Failed to open and load BPF skeleton\n");
+		return 1;
+	}
+
+	/* Parameterize BPF code with minimum duration parameter */
+	skel->bss->read = 0;
+
+	/* Load & verify BPF programs */
+	err = user_ringbuf_bpf__load(skel);
+	if (err) {
+		fprintf(stderr, "Failed to load and verify BPF skeleton\n");
+		goto cleanup;
+	}
+
+	/* Attach tracepoints */
+	err = user_ringbuf_bpf__attach(skel);
+	if (err) {
+		fprintf(stderr, "Failed to attach BPF skeleton\n");
+		goto cleanup;
+	}
+
+	/* Set up ring buffer polling */
+	rb = ring_buffer__new(bpf_map__fd(skel->maps.kernel_ringbuf), handle_event, NULL, NULL);
+	if (!rb) {
+		err = -1;
+		fprintf(stderr, "Failed to create ring buffer\n");
+		goto cleanup;
+	}
+	user_ringbuf = user_ring_buffer__new(bpf_map__fd(skel->maps.user_ringbuf), NULL);
+
+	write_samples(user_ringbuf);
+
+	/* Process events */
+	printf("%-8s %-5s %-16s %-7s %-7s %s\n",
+	       "TIME", "EVENT", "COMM", "PID", "PPID", "FILENAME/EXIT CODE");
+	while (!exiting) {
+		err = ring_buffer__poll(rb, 100 /* timeout, ms */);
+		/* Ctrl-C will cause -EINTR */
+		if (err == -EINTR) {
+			err = 0;
+			break;
+		}
+		if (err < 0) {
+			printf("Error polling perf buffer: %d\n", err);
+			break;
+		}
+	}
+
+cleanup:
+	/* Clean up */
+	ring_buffer__free(rb);
+	user_ringbuf_bpf__destroy(skel);
+	user_ring_buffer__free(user_ringbuf);
+
+	return err < 0 ? -err : 0;
+}

src/35-user-ringbuf/user_ringbuf.h

@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2020 Facebook */
+#ifndef __BOOTSTRAP_H
+#define __BOOTSTRAP_H
+
+#define TASK_COMM_LEN 16
+#define MAX_FILENAME_LEN 127
+
+struct event {
+	int pid;
+	char comm[TASK_COMM_LEN];
+};
+
+struct user_sample {
+	int i;
+	char comm[TASK_COMM_LEN];
+};
+
+#endif /* __BOOTSTRAP_H */