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

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <test_progs.h>
   3
   4 void test_stacktrace_build_id(void)
   5 {
   6         int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
   7         const char *prog_name = "tracepoint/random/urandom_read";
   8         const char *file = "./test_stacktrace_build_id.o";
   9         int err, prog_fd, stack_trace_len;
  10         __u32 key, previous_key, val, duration = 0;
  11         struct bpf_program *prog;
  12         struct bpf_object *obj;
  13         struct bpf_link *link = NULL;
  14         char buf[256];
  15         int i, j;
  16         struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
  17         int build_id_matches = 0;
  18         int retry = 1;
  19
  20 retry:
  21         err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
  22         if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
  23                 return;
  24
  25         prog = bpf_object__find_program_by_title(obj, prog_name);
  26         if (CHECK(!prog, "find_prog", "prog '%s' not found\n", prog_name))
  27                 goto close_prog;
  28
  29         link = bpf_program__attach_tracepoint(prog, "random", "urandom_read");
  30         if (CHECK(IS_ERR(link), "attach_tp", "err %ld\n", PTR_ERR(link)))
  31                 goto close_prog;
  32
  33         /* find map fds */
  34         control_map_fd = bpf_find_map(__func__, obj, "control_map");
  35         if (CHECK(control_map_fd < 0, "bpf_find_map control_map",
  36                   "err %d errno %d\n", err, errno))
  37                 goto disable_pmu;
  38
  39         stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap");
  40         if (CHECK(stackid_hmap_fd < 0, "bpf_find_map stackid_hmap",
  41                   "err %d errno %d\n", err, errno))
  42                 goto disable_pmu;
  43
  44         stackmap_fd = bpf_find_map(__func__, obj, "stackmap");
  45         if (CHECK(stackmap_fd < 0, "bpf_find_map stackmap", "err %d errno %d\n",
  46                   err, errno))
  47                 goto disable_pmu;
  48
  49         stack_amap_fd = bpf_find_map(__func__, obj, "stack_amap");
  50         if (CHECK(stack_amap_fd < 0, "bpf_find_map stack_amap",
  51                   "err %d errno %d\n", err, errno))
  52                 goto disable_pmu;
  53
  54         assert(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")
  55                == 0);
  56         assert(system("./urandom_read") == 0);
  57         /* disable stack trace collection */
  58         key = 0;
  59         val = 1;
  60         bpf_map_update_elem(control_map_fd, &key, &val, 0);
  61
  62         /* for every element in stackid_hmap, we can find a corresponding one
  63          * in stackmap, and vise versa.
  64          */
  65         err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
  66         if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
  67                   "err %d errno %d\n", err, errno))
  68                 goto disable_pmu;
  69
  70         err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
  71         if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
  72                   "err %d errno %d\n", err, errno))
  73                 goto disable_pmu;
  74
  75         err = extract_build_id(buf, 256);
  76
  77         if (CHECK(err, "get build_id with readelf",
  78                   "err %d errno %d\n", err, errno))
  79                 goto disable_pmu;
  80
  81         err = bpf_map_get_next_key(stackmap_fd, NULL, &key);
  82         if (CHECK(err, "get_next_key from stackmap",
  83                   "err %d, errno %d\n", err, errno))
  84                 goto disable_pmu;
  85
  86         do {
  87                 char build_id[64];
  88
  89                 err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
  90                 if (CHECK(err, "lookup_elem from stackmap",
  91                           "err %d, errno %d\n", err, errno))
  92                         goto disable_pmu;
  93                 for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
  94                         if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
  95                             id_offs[i].offset != 0) {
  96                                 for (j = 0; j < 20; ++j)
  97                                         sprintf(build_id + 2 * j, "%02x",
  98                                                 id_offs[i].build_id[j] & 0xff);
  99                                 if (strstr(buf, build_id) != NULL)
 100                                         build_id_matches = 1;
 101                         }
 102                 previous_key = key;
 103         } while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);
 104
 105         /* stack_map_get_build_id_offset() is racy and sometimes can return
 106          * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
 107          * try it one more time.
 108          */
 109         if (build_id_matches < 1 && retry--) {
 110                 bpf_link__destroy(link);
 111                 bpf_object__close(obj);
 112                 printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
 113                        __func__);
 114                 goto retry;
 115         }
 116
 117         if (CHECK(build_id_matches < 1, "build id match",
 118                   "Didn't find expected build ID from the map\n"))
 119                 goto disable_pmu;
 120
 121         stack_trace_len = PERF_MAX_STACK_DEPTH
 122                 * sizeof(struct bpf_stack_build_id);
 123         err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
 124         CHECK(err, "compare_stack_ips stackmap vs. stack_amap",
 125               "err %d errno %d\n", err, errno);
 126
 127 disable_pmu:
 128         bpf_link__destroy(link);
 129
 130 close_prog:
 131         bpf_object__close(obj);
 132 }