samples/bpf/trace_output_user.c

   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
   9 static __u64 time_get_ns(void)
  10 {
  11         struct timespec ts;
  12
  13         clock_gettime(CLOCK_MONOTONIC, &ts);
  14         return ts.tv_sec * 1000000000ull + ts.tv_nsec;
  15 }
  16
  17 static __u64 start_time;
  18 static __u64 cnt;
  19
  20 #define MAX_CNT 100000ll
  21
  22 static 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("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("recv %lld events per sec\n",
  39                        MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
  40                 return;
  41         }
  42 }
  43
  44 int main(int argc, char **argv)
  45 {
  46         struct perf_buffer_opts pb_opts = {};
  47         struct bpf_link *link = NULL;
  48         struct bpf_program *prog;
  49         struct perf_buffer *pb;
  50         struct bpf_object *obj;
  51         int map_fd, ret = 0;
  52         char filename[256];
  53         FILE *f;
  54
  55         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  56         obj = bpf_object__open_file(filename, NULL);
  57         if (libbpf_get_error(obj)) {
  58                 fprintf(stderr, "ERROR: opening BPF object file failed\n");
  59                 return 0;
  60         }
  61
  62         /* load BPF program */
  63         if (bpf_object__load(obj)) {
  64                 fprintf(stderr, "ERROR: loading BPF object file failed\n");
  65                 goto cleanup;
  66         }
  67
  68         map_fd = bpf_object__find_map_fd_by_name(obj, "my_map");
  69         if (map_fd < 0) {
  70                 fprintf(stderr, "ERROR: finding a map in obj file failed\n");
  71                 goto cleanup;
  72         }
  73
  74         prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
  75         if (libbpf_get_error(prog)) {
  76                 fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
  77                 goto cleanup;
  78         }
  79
  80         link = bpf_program__attach(prog);
  81         if (libbpf_get_error(link)) {
  82                 fprintf(stderr, "ERROR: bpf_program__attach failed\n");
  83                 link = NULL;
  84                 goto cleanup;
  85         }
  86
  87         pb_opts.sample_cb = print_bpf_output;
  88         pb = perf_buffer__new(map_fd, 8, &pb_opts);
  89         ret = libbpf_get_error(pb);
  90         if (ret) {
  91                 printf("failed to setup perf_buffer: %d\n", ret);
  92                 return 1;
  93         }
  94
  95         f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
  96         (void) f;
  97
  98         start_time = time_get_ns();
  99         while ((ret = perf_buffer__poll(pb, 1000)) >= 0 && cnt < MAX_CNT) {
 100         }
 101         kill(0, SIGINT);
 102
 103 cleanup:
 104         bpf_link__destroy(link);
 105         bpf_object__close(obj);
 106         return ret;
 107 }