Commit ee5cf82c authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann

selftests/bpf: test perf buffer API

Add test verifying perf buffer API functionality.
Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent d7ff34d5
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <pthread.h>
#include <sched.h>
#include <sys/socket.h>
#include <test_progs.h>
#ifdef __x86_64__
#define SYS_KPROBE_NAME "__x64_sys_nanosleep"
#else
#define SYS_KPROBE_NAME "sys_nanosleep"
#endif
static void on_sample(void *ctx, int cpu, void *data, __u32 size)
{
int cpu_data = *(int *)data, duration = 0;
cpu_set_t *cpu_seen = ctx;
if (cpu_data != cpu)
CHECK(cpu_data != cpu, "check_cpu_data",
"cpu_data %d != cpu %d\n", cpu_data, cpu);
CPU_SET(cpu, cpu_seen);
}
void test_perf_buffer(void)
{
int err, prog_fd, nr_cpus, i, duration = 0;
const char *prog_name = "kprobe/sys_nanosleep";
const char *file = "./test_perf_buffer.o";
struct perf_buffer_opts pb_opts = {};
struct bpf_map *perf_buf_map;
cpu_set_t cpu_set, cpu_seen;
struct bpf_program *prog;
struct bpf_object *obj;
struct perf_buffer *pb;
struct bpf_link *link;
nr_cpus = libbpf_num_possible_cpus();
if (CHECK(nr_cpus < 0, "nr_cpus", "err %d\n", nr_cpus))
return;
/* load program */
err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd);
if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))
return;
prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK(!prog, "find_probe", "prog '%s' not found\n", prog_name))
goto out_close;
/* load map */
perf_buf_map = bpf_object__find_map_by_name(obj, "perf_buf_map");
if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n"))
goto out_close;
/* attach kprobe */
link = bpf_program__attach_kprobe(prog, false /* retprobe */,
SYS_KPROBE_NAME);
if (CHECK(IS_ERR(link), "attach_kprobe", "err %ld\n", PTR_ERR(link)))
goto out_close;
/* set up perf buffer */
pb_opts.sample_cb = on_sample;
pb_opts.ctx = &cpu_seen;
pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
goto out_detach;
/* trigger kprobe on every CPU */
CPU_ZERO(&cpu_seen);
for (i = 0; i < nr_cpus; i++) {
CPU_ZERO(&cpu_set);
CPU_SET(i, &cpu_set);
err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set),
&cpu_set);
if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n",
i, err))
goto out_detach;
usleep(1);
}
/* read perf buffer */
err = perf_buffer__poll(pb, 100);
if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
goto out_free_pb;
if (CHECK(CPU_COUNT(&cpu_seen) != nr_cpus, "seen_cpu_cnt",
"expect %d, seen %d\n", nr_cpus, CPU_COUNT(&cpu_seen)))
goto out_free_pb;
out_free_pb:
perf_buffer__free(pb);
out_detach:
bpf_link__destroy(link);
out_close:
bpf_object__close(obj);
}
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
#include <linux/ptrace.h>
#include <linux/bpf.h>
#include "bpf_helpers.h"
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__uint(key_size, sizeof(int));
__uint(value_size, sizeof(int));
} perf_buf_map SEC(".maps");
SEC("kprobe/sys_nanosleep")
int handle_sys_nanosleep_entry(struct pt_regs *ctx)
{
int cpu = bpf_get_smp_processor_id();
bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU,
&cpu, sizeof(cpu));
return 0;
}
char _license[] SEC("license") = "GPL";
__u32 _version SEC("version") = 1;
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