samples/bpf: add perf_event+bpf example (1c47910e) · Commits · 戴 / test

samples/bpf/Makefile

+4 −0

Original line number	Diff line number	Diff line
		@@ -25,6 +25,7 @@ hostprogs-y += test_cgrp2_array_pin
		hostprogs-y += xdp1
		hostprogs-y += xdp2
		hostprogs-y += test_current_task_under_cgroup
		hostprogs-y += trace_event

		test_verifier-objs := test_verifier.o libbpf.o
		test_maps-objs := test_maps.o libbpf.o
		@@ -52,6 +53,7 @@ xdp1-objs := bpf_load.o libbpf.o xdp1_user.o
		xdp2-objs := bpf_load.o libbpf.o xdp1_user.o
		test_current_task_under_cgroup-objs := bpf_load.o libbpf.o \
		test_current_task_under_cgroup_user.o
		trace_event-objs := bpf_load.o libbpf.o trace_event_user.o

		# Tell kbuild to always build the programs
		always := $(hostprogs-y)
		@@ -79,6 +81,7 @@ always += test_cgrp2_tc_kern.o
		always += xdp1_kern.o
		always += xdp2_kern.o
		always += test_current_task_under_cgroup_kern.o
		always += trace_event_kern.o

		HOSTCFLAGS += -I$(objtree)/usr/include

		@@ -103,6 +106,7 @@ HOSTLOADLIBES_test_overhead += -lelf -lrt
		HOSTLOADLIBES_xdp1 += -lelf
		HOSTLOADLIBES_xdp2 += -lelf
		HOSTLOADLIBES_test_current_task_under_cgroup += -lelf
		HOSTLOADLIBES_trace_event += -lelf

		# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
		# make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang

samples/bpf/bpf_helpers.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -55,6 +55,8 @@ static int (bpf_skb_get_tunnel_opt)(void ctx, void *md, int size) =
		(void *) BPF_FUNC_skb_get_tunnel_opt;
		static int (bpf_skb_set_tunnel_opt)(void ctx, void *md, int size) =
		(void *) BPF_FUNC_skb_set_tunnel_opt;
		static unsigned long long (*bpf_get_prandom_u32)(void) =
		(void *) BPF_FUNC_get_prandom_u32;

		/* llvm builtin functions that eBPF C program may use to
		* emit BPF_LD_ABS and BPF_LD_IND instructions

samples/bpf/bpf_load.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -51,6 +51,7 @@ static int load_and_attach(const char event, struct bpf_insn prog, int size)
		bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
		bool is_tracepoint = strncmp(event, "tracepoint/", 11) == 0;
		bool is_xdp = strncmp(event, "xdp", 3) == 0;
		bool is_perf_event = strncmp(event, "perf_event", 10) == 0;
		enum bpf_prog_type prog_type;
		char buf[256];
		int fd, efd, err, id;
		@@ -69,6 +70,8 @@ static int load_and_attach(const char event, struct bpf_insn prog, int size)
		prog_type = BPF_PROG_TYPE_TRACEPOINT;
		} else if (is_xdp) {
		prog_type = BPF_PROG_TYPE_XDP;
		} else if (is_perf_event) {
		prog_type = BPF_PROG_TYPE_PERF_EVENT;
		} else {
		printf("Unknown event '%s'\n", event);
		return -1;
		@@ -82,7 +85,7 @@ static int load_and_attach(const char event, struct bpf_insn prog, int size)

		prog_fd[prog_cnt++] = fd;

		if (is_xdp)
		if (is_xdp \|\| is_perf_event)
		return 0;

		if (is_socket) {
		@@ -326,6 +329,7 @@ int load_bpf_file(char *path)
		memcmp(shname_prog, "kretprobe/", 10) == 0 \|\|
		memcmp(shname_prog, "tracepoint/", 11) == 0 \|\|
		memcmp(shname_prog, "xdp", 3) == 0 \|\|
		memcmp(shname_prog, "perf_event", 10) == 0 \|\|
		memcmp(shname_prog, "socket", 6) == 0)
		load_and_attach(shname_prog, insns, data_prog->d_size);
		}
		@@ -344,6 +348,7 @@ int load_bpf_file(char *path)
		memcmp(shname, "kretprobe/", 10) == 0 \|\|
		memcmp(shname, "tracepoint/", 11) == 0 \|\|
		memcmp(shname, "xdp", 3) == 0 \|\|
		memcmp(shname, "perf_event", 10) == 0 \|\|
		memcmp(shname, "socket", 6) == 0)
		load_and_attach(shname, data->d_buf, data->d_size);
		}

samples/bpf/trace_event_kern.c

0 → 100644

+65 −0

Original line number	Diff line number	Diff line
		/* Copyright (c) 2016 Facebook
		*
		* This program is free software; you can redistribute it and/or
		* modify it under the terms of version 2 of the GNU General Public
		* License as published by the Free Software Foundation.
		*/
		#include <linux/ptrace.h>
		#include <linux/version.h>
		#include <uapi/linux/bpf.h>
		#include <uapi/linux/bpf_perf_event.h>
		#include <uapi/linux/perf_event.h>
		#include "bpf_helpers.h"

		struct key_t {
		char comm[TASK_COMM_LEN];
		u32 kernstack;
		u32 userstack;
		};

		struct bpf_map_def SEC("maps") counts = {
		.type = BPF_MAP_TYPE_HASH,
		.key_size = sizeof(struct key_t),
		.value_size = sizeof(u64),
		.max_entries = 10000,
		};

		struct bpf_map_def SEC("maps") stackmap = {
		.type = BPF_MAP_TYPE_STACK_TRACE,
		.key_size = sizeof(u32),
		.value_size = PERF_MAX_STACK_DEPTH * sizeof(u64),
		.max_entries = 10000,
		};

		#define KERN_STACKID_FLAGS (0 \| BPF_F_FAST_STACK_CMP)
		#define USER_STACKID_FLAGS (0 \| BPF_F_FAST_STACK_CMP \| BPF_F_USER_STACK)

		SEC("perf_event")
		int bpf_prog1(struct bpf_perf_event_data *ctx)
		{
		char fmt[] = "CPU-%d period %lld ip %llx";
		u32 cpu = bpf_get_smp_processor_id();
		struct key_t key;
		u64 *val, one = 1;

		if (ctx->sample_period < 10000)
		/* ignore warmup */
		return 0;
		bpf_get_current_comm(&key.comm, sizeof(key.comm));
		key.kernstack = bpf_get_stackid(ctx, &stackmap, KERN_STACKID_FLAGS);
		key.userstack = bpf_get_stackid(ctx, &stackmap, USER_STACKID_FLAGS);
		if ((int)key.kernstack < 0 && (int)key.userstack < 0) {
		bpf_trace_printk(fmt, sizeof(fmt), cpu, ctx->sample_period,
		ctx->regs.ip);
		return 0;
		}

		val = bpf_map_lookup_elem(&counts, &key);
		if (val)
		(*val)++;
		else
		bpf_map_update_elem(&counts, &key, &one, BPF_NOEXIST);
		return 0;
		}

		char _license[] SEC("license") = "GPL";

samples/bpf/trace_event_user.c

0 → 100644

+213 −0

Original line number	Diff line number	Diff line
		/* Copyright (c) 2016 Facebook
		*
		* This program is free software; you can redistribute it and/or
		* modify it under the terms of version 2 of the GNU General Public
		* License as published by the Free Software Foundation.
		*/
		#include <stdio.h>
		#include <unistd.h>
		#include <stdlib.h>
		#include <stdbool.h>
		#include <string.h>
		#include <fcntl.h>
		#include <poll.h>
		#include <sys/ioctl.h>
		#include <linux/perf_event.h>
		#include <linux/bpf.h>
		#include <signal.h>
		#include <assert.h>
		#include <errno.h>
		#include <sys/resource.h>
		#include "libbpf.h"
		#include "bpf_load.h"

		#define SAMPLE_FREQ 50

		static bool sys_read_seen, sys_write_seen;

		static void print_ksym(__u64 addr)
		{
		struct ksym *sym;

		if (!addr)
		return;
		sym = ksym_search(addr);
		printf("%s;", sym->name);
		if (!strcmp(sym->name, "sys_read"))
		sys_read_seen = true;
		else if (!strcmp(sym->name, "sys_write"))
		sys_write_seen = true;
		}

		static void print_addr(__u64 addr)
		{
		if (!addr)
		return;
		printf("%llx;", addr);
		}

		#define TASK_COMM_LEN 16

		struct key_t {
		char comm[TASK_COMM_LEN];
		__u32 kernstack;
		__u32 userstack;
		};

		static void print_stack(struct key_t *key, __u64 count)
		{
		__u64 ip[PERF_MAX_STACK_DEPTH] = {};
		static bool warned;
		int i;

		printf("%3lld %s;", count, key->comm);
		if (bpf_lookup_elem(map_fd[1], &key->kernstack, ip) != 0) {
		printf("---;");
		} else {
		for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
		print_ksym(ip[i]);
		}
		printf("-;");
		if (bpf_lookup_elem(map_fd[1], &key->userstack, ip) != 0) {
		printf("---;");
		} else {
		for (i = PERF_MAX_STACK_DEPTH - 1; i >= 0; i--)
		print_addr(ip[i]);
		}
		printf("\n");

		if (key->kernstack == -EEXIST && !warned) {
		printf("stackmap collisions seen. Consider increasing size\n");
		warned = true;
		} else if ((int)key->kernstack < 0 && (int)key->userstack < 0) {
		printf("err stackid %d %d\n", key->kernstack, key->userstack);
		}
		}

		static void int_exit(int sig)
		{
		kill(0, SIGKILL);
		exit(0);
		}

		static void print_stacks(void)
		{
		struct key_t key = {}, next_key;
		__u64 value;
		__u32 stackid = 0, next_id;
		int fd = map_fd[0], stack_map = map_fd[1];

		sys_read_seen = sys_write_seen = false;
		while (bpf_get_next_key(fd, &key, &next_key) == 0) {
		bpf_lookup_elem(fd, &next_key, &value);
		print_stack(&next_key, value);
		bpf_delete_elem(fd, &next_key);
		key = next_key;
		}

		if (!sys_read_seen \|\| !sys_write_seen) {
		printf("BUG kernel stack doesn't contain sys_read() and sys_write()\n");
		int_exit(0);
		}

		/* clear stack map */
		while (bpf_get_next_key(stack_map, &stackid, &next_id) == 0) {
		bpf_delete_elem(stack_map, &next_id);
		stackid = next_id;
		}
		}

		static void test_perf_event_all_cpu(struct perf_event_attr *attr)
		{
		int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
		int pmu_fd = malloc(nr_cpus sizeof(int));
		int i;

		/* open perf_event on all cpus */
		for (i = 0; i < nr_cpus; i++) {
		pmu_fd[i] = perf_event_open(attr, -1, i, -1, 0);
		if (pmu_fd[i] < 0) {
		printf("perf_event_open failed\n");
		goto all_cpu_err;
		}
		assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
		assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
		}
		system("dd if=/dev/zero of=/dev/null count=5000k");
		print_stacks();
		all_cpu_err:
		for (i--; i >= 0; i--)
		close(pmu_fd[i]);
		free(pmu_fd);
		}

		static void test_perf_event_task(struct perf_event_attr *attr)
		{
		int pmu_fd;

		/* open task bound event */
		pmu_fd = perf_event_open(attr, 0, -1, -1, 0);
		if (pmu_fd < 0) {
		printf("perf_event_open failed\n");
		return;
		}
		assert(ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
		assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0) == 0);
		system("dd if=/dev/zero of=/dev/null count=5000k");
		print_stacks();
		close(pmu_fd);
		}

		static void test_bpf_perf_event(void)
		{
		struct perf_event_attr attr_type_hw = {
		.sample_freq = SAMPLE_FREQ,
		.freq = 1,
		.type = PERF_TYPE_HARDWARE,
		.config = PERF_COUNT_HW_CPU_CYCLES,
		.inherit = 1,
		};
		struct perf_event_attr attr_type_sw = {
		.sample_freq = SAMPLE_FREQ,
		.freq = 1,
		.type = PERF_TYPE_SOFTWARE,
		.config = PERF_COUNT_SW_CPU_CLOCK,
		.inherit = 1,
		};

		test_perf_event_all_cpu(&attr_type_hw);
		test_perf_event_task(&attr_type_hw);
		test_perf_event_all_cpu(&attr_type_sw);
		test_perf_event_task(&attr_type_sw);
		}


		int main(int argc, char **argv)
		{
		struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
		char filename[256];

		snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
		setrlimit(RLIMIT_MEMLOCK, &r);

		signal(SIGINT, int_exit);

		if (load_kallsyms()) {
		printf("failed to process /proc/kallsyms\n");
		return 1;
		}

		if (load_bpf_file(filename)) {
		printf("%s", bpf_log_buf);
		return 2;
		}

		if (fork() == 0) {
		read_trace_pipe();
		return 0;
		}
		test_bpf_perf_event();

		int_exit(0);
		return 0;
		}

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