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

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2021 Facebook */
   3 #define _GNU_SOURCE
   4 #include <pthread.h>
   5 #include <sched.h>
   6 #include <test_progs.h>
   7 #include "testing_helpers.h"
   8 #include "test_perf_link.skel.h"
   9
  10 #define BURN_TIMEOUT_MS 100
  11 #define BURN_TIMEOUT_NS BURN_TIMEOUT_MS * 1000000
  12
  13 static void burn_cpu(void)
  14 {
  15         volatile int j = 0;
  16         cpu_set_t cpu_set;
  17         int i, err;
  18
  19         /* generate some branches on cpu 0 */
  20         CPU_ZERO(&cpu_set);
  21         CPU_SET(0, &cpu_set);
  22         err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), &cpu_set);
  23         ASSERT_OK(err, "set_thread_affinity");
  24
  25         /* spin the loop for a while (random high number) */
  26         for (i = 0; i < 1000000; ++i)
  27                 ++j;
  28 }
  29
  30 /* TODO: often fails in concurrent mode */
  31 void serial_test_perf_link(void)
  32 {
  33         struct test_perf_link *skel = NULL;
  34         struct perf_event_attr attr;
  35         int pfd = -1, link_fd = -1, err;
  36         int run_cnt_before, run_cnt_after;
  37         struct bpf_link_info info;
  38         __u32 info_len = sizeof(info);
  39         __u64 timeout_time_ns;
  40
  41         /* create perf event */
  42         memset(&attr, 0, sizeof(attr));
  43         attr.size = sizeof(attr);
  44         attr.type = PERF_TYPE_SOFTWARE;
  45         attr.config = PERF_COUNT_SW_CPU_CLOCK;
  46         attr.freq = 1;
  47         attr.sample_freq = 1000;
  48         pfd = syscall(__NR_perf_event_open, &attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
  49         if (!ASSERT_GE(pfd, 0, "perf_fd"))
  50                 goto cleanup;
  51
  52         skel = test_perf_link__open_and_load();
  53         if (!ASSERT_OK_PTR(skel, "skel_load"))
  54                 goto cleanup;
  55
  56         link_fd = bpf_link_create(bpf_program__fd(skel->progs.handler), pfd,
  57                                   BPF_PERF_EVENT, NULL);
  58         if (!ASSERT_GE(link_fd, 0, "link_fd"))
  59                 goto cleanup;
  60
  61         memset(&info, 0, sizeof(info));
  62         err = bpf_link_get_info_by_fd(link_fd, &info, &info_len);
  63         if (!ASSERT_OK(err, "link_get_info"))
  64                 goto cleanup;
  65
  66         ASSERT_EQ(info.type, BPF_LINK_TYPE_PERF_EVENT, "link_type");
  67         ASSERT_GT(info.id, 0, "link_id");
  68         ASSERT_GT(info.prog_id, 0, "link_prog_id");
  69
  70         /* ensure we get at least one perf_event prog execution */
  71         timeout_time_ns = get_time_ns() + BURN_TIMEOUT_NS;
  72         while (true) {
  73                 burn_cpu();
  74                 if (skel->bss->run_cnt > 0)
  75                         break;
  76                 if (!ASSERT_LT(get_time_ns(), timeout_time_ns, "run_cnt_timeout"))
  77                         break;
  78         }
  79
  80         /* perf_event is still active, but we close link and BPF program
  81          * shouldn't be executed anymore
  82          */
  83         close(link_fd);
  84         link_fd = -1;
  85
  86         /* make sure there are no stragglers */
  87         kern_sync_rcu();
  88
  89         run_cnt_before = skel->bss->run_cnt;
  90         burn_cpu();
  91         run_cnt_after = skel->bss->run_cnt;
  92
  93         ASSERT_EQ(run_cnt_before, run_cnt_after, "run_cnt_before_after");
  94
  95 cleanup:
  96         if (link_fd >= 0)
  97                 close(link_fd);
  98         if (pfd >= 0)
  99                 close(pfd);
 100         test_perf_link__destroy(skel);
 101 }