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

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <test_progs.h>
   3 #include "test_stacktrace_build_id.skel.h"
   4
   5 void test_stacktrace_build_id(void)
   6 {
   7
   8         int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
   9         struct test_stacktrace_build_id *skel;
  10         int err, stack_trace_len;
  11         __u32 key, prev_key, val, duration = 0;
  12         char buf[256];
  13         int i, j;
  14         struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
  15         int build_id_matches = 0;
  16         int retry = 1;
  17
  18 retry:
  19         skel = test_stacktrace_build_id__open_and_load();
  20         if (CHECK(!skel, "skel_open_and_load", "skeleton open/load failed\n"))
  21                 return;
  22
  23         err = test_stacktrace_build_id__attach(skel);
  24         if (CHECK(err, "attach_tp", "err %d\n", err))
  25                 goto cleanup;
  26
  27         /* find map fds */
  28         control_map_fd = bpf_map__fd(skel->maps.control_map);
  29         stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);
  30         stackmap_fd = bpf_map__fd(skel->maps.stackmap);
  31         stack_amap_fd = bpf_map__fd(skel->maps.stack_amap);
  32
  33         if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")))
  34                 goto cleanup;
  35         if (CHECK_FAIL(system("./urandom_read")))
  36                 goto cleanup;
  37         /* disable stack trace collection */
  38         key = 0;
  39         val = 1;
  40         bpf_map_update_elem(control_map_fd, &key, &val, 0);
  41
  42         /* for every element in stackid_hmap, we can find a corresponding one
  43          * in stackmap, and vise versa.
  44          */
  45         err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
  46         if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
  47                   "err %d errno %d\n", err, errno))
  48                 goto cleanup;
  49
  50         err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
  51         if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
  52                   "err %d errno %d\n", err, errno))
  53                 goto cleanup;
  54
  55         err = extract_build_id(buf, 256);
  56
  57         if (CHECK(err, "get build_id with readelf",
  58                   "err %d errno %d\n", err, errno))
  59                 goto cleanup;
  60
  61         err = bpf_map__get_next_key(skel->maps.stackmap, NULL, &key, sizeof(key));
  62         if (CHECK(err, "get_next_key from stackmap",
  63                   "err %d, errno %d\n", err, errno))
  64                 goto cleanup;
  65
  66         do {
  67                 char build_id[64];
  68
  69                 err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
  70                 if (CHECK(err, "lookup_elem from stackmap",
  71                           "err %d, errno %d\n", err, errno))
  72                         goto cleanup;
  73                 for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
  74                         if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
  75                             id_offs[i].offset != 0) {
  76                                 for (j = 0; j < 20; ++j)
  77                                         sprintf(build_id + 2 * j, "%02x",
  78                                                 id_offs[i].build_id[j] & 0xff);
  79                                 if (strstr(buf, build_id) != NULL)
  80                                         build_id_matches = 1;
  81                         }
  82                 prev_key = key;
  83         } while (bpf_map__get_next_key(skel->maps.stackmap, &prev_key, &key, sizeof(key)) == 0);
  84
  85         /* stack_map_get_build_id_offset() is racy and sometimes can return
  86          * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
  87          * try it one more time.
  88          */
  89         if (build_id_matches < 1 && retry--) {
  90                 test_stacktrace_build_id__destroy(skel);
  91                 printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
  92                        __func__);
  93                 goto retry;
  94         }
  95
  96         if (CHECK(build_id_matches < 1, "build id match",
  97                   "Didn't find expected build ID from the map\n"))
  98                 goto cleanup;
  99
 100         stack_trace_len = PERF_MAX_STACK_DEPTH *
 101                           sizeof(struct bpf_stack_build_id);
 102         err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
 103         CHECK(err, "compare_stack_ips stackmap vs. stack_amap",
 104               "err %d errno %d\n", err, errno);
 105
 106 cleanup:
 107         test_stacktrace_build_id__destroy(skel);
 108 }