samples/bpf/trace_output_user.c

   1 /* This program is free software; you can redistribute it and/or
   2  * modify it under the terms of version 2 of the GNU General Public
   3  * License as published by the Free Software Foundation.
   4  */
   5 #include <stdio.h>
   6 #include <unistd.h>
   7 #include <stdlib.h>
   8 #include <stdbool.h>
   9 #include <string.h>
  10 #include <fcntl.h>
  11 #include <poll.h>
  12 #include <linux/perf_event.h>
  13 #include <linux/bpf.h>
  14 #include <errno.h>
  15 #include <assert.h>
  16 #include <sys/syscall.h>
  17 #include <sys/ioctl.h>
  18 #include <sys/mman.h>
  19 #include <time.h>
  20 #include <signal.h>
  21 #include <libbpf.h>
  22 #include "bpf_load.h"
  23 #include "perf-sys.h"
  24 #include "trace_helpers.h"
  25
  26 static int pmu_fd;
  27
  28 static __u64 time_get_ns(void)
  29 {
  30         struct timespec ts;
  31
  32         clock_gettime(CLOCK_MONOTONIC, &ts);
  33         return ts.tv_sec * 1000000000ull + ts.tv_nsec;
  34 }
  35
  36 static __u64 start_time;
  37
  38 #define MAX_CNT 100000ll
  39
  40 static int print_bpf_output(void *data, int size)
  41 {
  42         static __u64 cnt;
  43         struct {
  44                 __u64 pid;
  45                 __u64 cookie;
  46         } *e = data;
  47
  48         if (e->cookie != 0x12345678) {
  49                 printf("BUG pid %llx cookie %llx sized %d\n",
  50                        e->pid, e->cookie, size);
  51                 return LIBBPF_PERF_EVENT_ERROR;
  52         }
  53
  54         cnt++;
  55
  56         if (cnt == MAX_CNT) {
  57                 printf("recv %lld events per sec\n",
  58                        MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
  59                 return LIBBPF_PERF_EVENT_DONE;
  60         }
  61
  62         return LIBBPF_PERF_EVENT_CONT;
  63 }
  64
  65 static void test_bpf_perf_event(void)
  66 {
  67         struct perf_event_attr attr = {
  68                 .sample_type = PERF_SAMPLE_RAW,
  69                 .type = PERF_TYPE_SOFTWARE,
  70                 .config = PERF_COUNT_SW_BPF_OUTPUT,
  71         };
  72         int key = 0;
  73
  74         pmu_fd = sys_perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
  75
  76         assert(pmu_fd >= 0);
  77         assert(bpf_map_update_elem(map_fd[0], &key, &pmu_fd, BPF_ANY) == 0);
  78         ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
  79 }
  80
  81 int main(int argc, char **argv)
  82 {
  83         char filename[256];
  84         FILE *f;
  85         int ret;
  86
  87         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  88
  89         if (load_bpf_file(filename)) {
  90                 printf("%s", bpf_log_buf);
  91                 return 1;
  92         }
  93
  94         test_bpf_perf_event();
  95
  96         if (perf_event_mmap(pmu_fd) < 0)
  97                 return 1;
  98
  99         f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
 100         (void) f;
 101
 102         start_time = time_get_ns();
 103         ret = perf_event_poller(pmu_fd, print_bpf_output);
 104         kill(0, SIGINT);
 105         return ret;
 106 }