samples/bpf/trace_output_user.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <stdio.h>
   3 #include <unistd.h>
   4 #include <stdlib.h>
   5 #include <stdbool.h>
   6 #include <string.h>
   7 #include <fcntl.h>
   8 #include <poll.h>
   9 #include <linux/perf_event.h>
  10 #include <linux/bpf.h>
  11 #include <errno.h>
  12 #include <assert.h>
  13 #include <sys/syscall.h>
  14 #include <sys/ioctl.h>
  15 #include <sys/mman.h>
  16 #include <time.h>
  17 #include <signal.h>
  18 #include <libbpf.h>
  19 #include "bpf_load.h"
  20 #include "perf-sys.h"
  21 #include "trace_helpers.h"
  22
  23 static int pmu_fd;
  24
  25 static __u64 time_get_ns(void)
  26 {
  27         struct timespec ts;
  28
  29         clock_gettime(CLOCK_MONOTONIC, &ts);
  30         return ts.tv_sec * 1000000000ull + ts.tv_nsec;
  31 }
  32
  33 static __u64 start_time;
  34
  35 #define MAX_CNT 100000ll
  36
  37 static int print_bpf_output(void *data, int size)
  38 {
  39         static __u64 cnt;
  40         struct {
  41                 __u64 pid;
  42                 __u64 cookie;
  43         } *e = data;
  44
  45         if (e->cookie != 0x12345678) {
  46                 printf("BUG pid %llx cookie %llx sized %d\n",
  47                        e->pid, e->cookie, size);
  48                 return LIBBPF_PERF_EVENT_ERROR;
  49         }
  50
  51         cnt++;
  52
  53         if (cnt == MAX_CNT) {
  54                 printf("recv %lld events per sec\n",
  55                        MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
  56                 return LIBBPF_PERF_EVENT_DONE;
  57         }
  58
  59         return LIBBPF_PERF_EVENT_CONT;
  60 }
  61
  62 static void test_bpf_perf_event(void)
  63 {
  64         struct perf_event_attr attr = {
  65                 .sample_type = PERF_SAMPLE_RAW,
  66                 .type = PERF_TYPE_SOFTWARE,
  67                 .config = PERF_COUNT_SW_BPF_OUTPUT,
  68         };
  69         int key = 0;
  70
  71         pmu_fd = sys_perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
  72
  73         assert(pmu_fd >= 0);
  74         assert(bpf_map_update_elem(map_fd[0], &key, &pmu_fd, BPF_ANY) == 0);
  75         ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
  76 }
  77
  78 int main(int argc, char **argv)
  79 {
  80         char filename[256];
  81         FILE *f;
  82         int ret;
  83
  84         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  85
  86         if (load_bpf_file(filename)) {
  87                 printf("%s", bpf_log_buf);
  88                 return 1;
  89         }
  90
  91         test_bpf_perf_event();
  92
  93         if (perf_event_mmap(pmu_fd) < 0)
  94                 return 1;
  95
  96         f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
  97         (void) f;
  98
  99         start_time = time_get_ns();
 100         ret = perf_event_poller(pmu_fd, print_bpf_output);
 101         kill(0, SIGINT);
 102         return ret;
 103 }