root/tools/testing/selftests/bpf/prog_tests/perf_buffer.c

DEFINITIONS

1. on_sample
2. test_perf_buffer

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define _GNU_SOURCE
   3 #include <pthread.h>
   4 #include <sched.h>
   5 #include <sys/socket.h>
   6 #include <test_progs.h>
   7 #include "libbpf_internal.h"
   8 
   9 static void on_sample(void *ctx, int cpu, void *data, __u32 size)
  10 {
  11         int cpu_data = *(int *)data, duration = 0;
  12         cpu_set_t *cpu_seen = ctx;
  13 
  14         if (cpu_data != cpu)
  15                 CHECK(cpu_data != cpu, "check_cpu_data",
  16                       "cpu_data %d != cpu %d\n", cpu_data, cpu);
  17 
  18         CPU_SET(cpu, cpu_seen);
  19 }
  20 
  21 void test_perf_buffer(void)
  22 {
  23         int err, prog_fd, on_len, nr_on_cpus = 0,  nr_cpus, i, duration = 0;
  24         const char *prog_name = "kprobe/sys_nanosleep";
  25         const char *file = "./test_perf_buffer.o";
  26         struct perf_buffer_opts pb_opts = {};
  27         struct bpf_map *perf_buf_map;
  28         cpu_set_t cpu_set, cpu_seen;
  29         struct bpf_program *prog;
  30         struct bpf_object *obj;
  31         struct perf_buffer *pb;
  32         struct bpf_link *link;
  33         bool *online;
  34 
  35         nr_cpus = libbpf_num_possible_cpus();
  36         if (CHECK(nr_cpus < 0, "nr_cpus", "err %d\n", nr_cpus))
  37                 return;
  38 
  39         err = parse_cpu_mask_file("/sys/devices/system/cpu/online",
  40                                   &online, &on_len);
  41         if (CHECK(err, "nr_on_cpus", "err %d\n", err))
  42                 return;
  43 
  44         for (i = 0; i < on_len; i++)
  45                 if (online[i])
  46                         nr_on_cpus++;
  47 
  48         /* load program */
  49         err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd);
  50         if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno)) {
  51                 obj = NULL;
  52                 goto out_close;
  53         }
  54 
  55         prog = bpf_object__find_program_by_title(obj, prog_name);
  56         if (CHECK(!prog, "find_probe", "prog '%s' not found\n", prog_name))
  57                 goto out_close;
  58 
  59         /* load map */
  60         perf_buf_map = bpf_object__find_map_by_name(obj, "perf_buf_map");
  61         if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n"))
  62                 goto out_close;
  63 
  64         /* attach kprobe */
  65         link = bpf_program__attach_kprobe(prog, false /* retprobe */,
  66                                           SYS_NANOSLEEP_KPROBE_NAME);
  67         if (CHECK(IS_ERR(link), "attach_kprobe", "err %ld\n", PTR_ERR(link)))
  68                 goto out_close;
  69 
  70         /* set up perf buffer */
  71         pb_opts.sample_cb = on_sample;
  72         pb_opts.ctx = &cpu_seen;
  73         pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
  74         if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
  75                 goto out_detach;
  76 
  77         /* trigger kprobe on every CPU */
  78         CPU_ZERO(&cpu_seen);
  79         for (i = 0; i < nr_cpus; i++) {
  80                 if (i >= on_len || !online[i]) {
  81                         printf("skipping offline CPU #%d\n", i);
  82                         continue;
  83                 }
  84 
  85                 CPU_ZERO(&cpu_set);
  86                 CPU_SET(i, &cpu_set);
  87 
  88                 err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set),
  89                                              &cpu_set);
  90                 if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n",
  91                                  i, err))
  92                         goto out_detach;
  93 
  94                 usleep(1);
  95         }
  96 
  97         /* read perf buffer */
  98         err = perf_buffer__poll(pb, 100);
  99         if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
 100                 goto out_free_pb;
 101 
 102         if (CHECK(CPU_COUNT(&cpu_seen) != nr_on_cpus, "seen_cpu_cnt",
 103                   "expect %d, seen %d\n", nr_on_cpus, CPU_COUNT(&cpu_seen)))
 104                 goto out_free_pb;
 105 
 106 out_free_pb:
 107         perf_buffer__free(pb);
 108 out_detach:
 109         bpf_link__destroy(link);
 110 out_close:
 111         bpf_object__close(obj);
 112         free(online);
 113 }