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

   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
   8 static void on_sample(void *ctx, int cpu, void *data, __u32 size)
   9 {
  10         int cpu_data = *(int *)data, duration = 0;
  11         cpu_set_t *cpu_seen = ctx;
  12
  13         if (cpu_data != cpu)
  14                 CHECK(cpu_data != cpu, "check_cpu_data",
  15                       "cpu_data %d != cpu %d\n", cpu_data, cpu);
  16
  17         CPU_SET(cpu, cpu_seen);
  18 }
  19
  20 void test_perf_buffer(void)
  21 {
  22         int err, prog_fd, nr_cpus, i, duration = 0;
  23         const char *prog_name = "kprobe/sys_nanosleep";
  24         const char *file = "./test_perf_buffer.o";
  25         struct perf_buffer_opts pb_opts = {};
  26         struct bpf_map *perf_buf_map;
  27         cpu_set_t cpu_set, cpu_seen;
  28         struct bpf_program *prog;
  29         struct bpf_object *obj;
  30         struct perf_buffer *pb;
  31         struct bpf_link *link;
  32
  33         nr_cpus = libbpf_num_possible_cpus();
  34         if (CHECK(nr_cpus < 0, "nr_cpus", "err %d\n", nr_cpus))
  35                 return;
  36
  37         /* load program */
  38         err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd);
  39         if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))
  40                 return;
  41
  42         prog = bpf_object__find_program_by_title(obj, prog_name);
  43         if (CHECK(!prog, "find_probe", "prog '%s' not found\n", prog_name))
  44                 goto out_close;
  45
  46         /* load map */
  47         perf_buf_map = bpf_object__find_map_by_name(obj, "perf_buf_map");
  48         if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n"))
  49                 goto out_close;
  50
  51         /* attach kprobe */
  52         link = bpf_program__attach_kprobe(prog, false /* retprobe */,
  53                                           SYS_NANOSLEEP_KPROBE_NAME);
  54         if (CHECK(IS_ERR(link), "attach_kprobe", "err %ld\n", PTR_ERR(link)))
  55                 goto out_close;
  56
  57         /* set up perf buffer */
  58         pb_opts.sample_cb = on_sample;
  59         pb_opts.ctx = &cpu_seen;
  60         pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
  61         if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
  62                 goto out_detach;
  63
  64         /* trigger kprobe on every CPU */
  65         CPU_ZERO(&cpu_seen);
  66         for (i = 0; i < nr_cpus; i++) {
  67                 CPU_ZERO(&cpu_set);
  68                 CPU_SET(i, &cpu_set);
  69
  70                 err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set),
  71                                              &cpu_set);
  72                 if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n",
  73                                  i, err))
  74                         goto out_detach;
  75
  76                 usleep(1);
  77         }
  78
  79         /* read perf buffer */
  80         err = perf_buffer__poll(pb, 100);
  81         if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
  82                 goto out_free_pb;
  83
  84         if (CHECK(CPU_COUNT(&cpu_seen) != nr_cpus, "seen_cpu_cnt",
  85                   "expect %d, seen %d\n", nr_cpus, CPU_COUNT(&cpu_seen)))
  86                 goto out_free_pb;
  87
  88 out_free_pb:
  89         perf_buffer__free(pb);
  90 out_detach:
  91         bpf_link__destroy(link);
  92 out_close:
  93         bpf_object__close(obj);
  94 }