1// SPDX-License-Identifier: GPL-2.0-only
2#include <stdio.h>
3#include <fcntl.h>
4#include <poll.h>
5#include <time.h>
6#include <signal.h>
7#include <bpf/libbpf.h>
8
9static __u64 time_get_ns(void)
10{
11 struct timespec ts;
12
13 clock_gettime(CLOCK_MONOTONIC, tp: &ts);
14 return ts.tv_sec * 1000000000ull + ts.tv_nsec;
15}
16
17static __u64 start_time;
18static __u64 cnt;
19
20#define MAX_CNT 100000ll
21
22static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
23{
24 struct {
25 __u64 pid;
26 __u64 cookie;
27 } *e = data;
28
29 if (e->cookie != 0x12345678) {
30 printf(format: "BUG pid %llx cookie %llx sized %d\n",
31 e->pid, e->cookie, size);
32 return;
33 }
34
35 cnt++;
36
37 if (cnt == MAX_CNT) {
38 printf(format: "recv %lld events per sec\n",
39 MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
40 return;
41 }
42}
43
44int main(int argc, char **argv)
45{
46 struct bpf_link *link = NULL;
47 struct bpf_program *prog;
48 struct perf_buffer *pb;
49 struct bpf_object *obj;
50 int map_fd, ret = 0;
51 char filename[256];
52 FILE *f;
53
54 snprintf(s: filename, maxlen: sizeof(filename), format: "%s.bpf.o", argv[0]);
55 obj = bpf_object__open_file(filename, NULL);
56 if (libbpf_get_error(obj)) {
57 fprintf(stderr, format: "ERROR: opening BPF object file failed\n");
58 return 0;
59 }
60
61 /* load BPF program */
62 if (bpf_object__load(obj)) {
63 fprintf(stderr, format: "ERROR: loading BPF object file failed\n");
64 goto cleanup;
65 }
66
67 map_fd = bpf_object__find_map_fd_by_name(obj, "my_map");
68 if (map_fd < 0) {
69 fprintf(stderr, format: "ERROR: finding a map in obj file failed\n");
70 goto cleanup;
71 }
72
73 prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
74 if (libbpf_get_error(prog)) {
75 fprintf(stderr, format: "ERROR: finding a prog in obj file failed\n");
76 goto cleanup;
77 }
78
79 link = bpf_program__attach(prog);
80 if (libbpf_get_error(link)) {
81 fprintf(stderr, format: "ERROR: bpf_program__attach failed\n");
82 link = NULL;
83 goto cleanup;
84 }
85
86 pb = perf_buffer__new(map_fd, 8, print_bpf_output, NULL, NULL, NULL);
87 ret = libbpf_get_error(pb);
88 if (ret) {
89 printf(format: "failed to setup perf_buffer: %d\n", ret);
90 return 1;
91 }
92
93 f = popen(command: "taskset 1 dd if=/dev/zero of=/dev/null", modes: "r");
94 (void) f;
95
96 start_time = time_get_ns();
97 while ((ret = perf_buffer__poll(pb, 1000)) >= 0 && cnt < MAX_CNT) {
98 }
99 kill(pid: 0, SIGINT);
100
101cleanup:
102 bpf_link__destroy(link);
103 bpf_object__close(obj);
104 return ret;
105}
106

source code of linux/samples/bpf/trace_output_user.c