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

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <test_progs.h>
   3 #include "test_stacktrace_build_id.skel.h"
   4
   5 static __u64 read_perf_max_sample_freq(void)
   6 {
   7         __u64 sample_freq = 5000; /* fallback to 5000 on error */
   8         FILE *f;
   9         __u32 duration = 0;
  10
  11         f = fopen("/proc/sys/kernel/perf_event_max_sample_rate", "r");
  12         if (f == NULL)
  13                 return sample_freq;
  14         CHECK(fscanf(f, "%llu", &sample_freq) != 1, "Get max sample rate",
  15                   "return default value: 5000,err %d\n", -errno);
  16         fclose(f);
  17         return sample_freq;
  18 }
  19
  20 void test_stacktrace_build_id_nmi(void)
  21 {
  22         int control_map_fd, stackid_hmap_fd, stackmap_fd;
  23         struct test_stacktrace_build_id *skel;
  24         int err, pmu_fd;
  25         struct perf_event_attr attr = {
  26                 .freq = 1,
  27                 .type = PERF_TYPE_HARDWARE,
  28                 .config = PERF_COUNT_HW_CPU_CYCLES,
  29         };
  30         __u32 key, previous_key, val, duration = 0;
  31         char buf[256];
  32         int i, j;
  33         struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
  34         int build_id_matches = 0;
  35         int retry = 1;
  36
  37         attr.sample_freq = read_perf_max_sample_freq();
  38
  39 retry:
  40         skel = test_stacktrace_build_id__open();
  41         if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
  42                 return;
  43
  44         /* override program type */
  45         bpf_program__set_perf_event(skel->progs.oncpu);
  46
  47         err = test_stacktrace_build_id__load(skel);
  48         if (CHECK(err, "skel_load", "skeleton load failed: %d\n", err))
  49                 goto cleanup;
  50
  51         pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
  52                          0 /* cpu 0 */, -1 /* group id */,
  53                          0 /* flags */);
  54         if (pmu_fd < 0 && errno == ENOENT) {
  55                 printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n", __func__);
  56                 test__skip();
  57                 goto cleanup;
  58         }
  59         if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
  60                   pmu_fd, errno))
  61                 goto cleanup;
  62
  63         skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
  64                                                            pmu_fd);
  65         if (CHECK(IS_ERR(skel->links.oncpu), "attach_perf_event",
  66                   "err %ld\n", PTR_ERR(skel->links.oncpu))) {
  67                 close(pmu_fd);
  68                 goto cleanup;
  69         }
  70
  71         /* find map fds */
  72         control_map_fd = bpf_map__fd(skel->maps.control_map);
  73         stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);
  74         stackmap_fd = bpf_map__fd(skel->maps.stackmap);
  75
  76         if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")))
  77                 goto cleanup;
  78         if (CHECK_FAIL(system("taskset 0x1 ./urandom_read 100000")))
  79                 goto cleanup;
  80         /* disable stack trace collection */
  81         key = 0;
  82         val = 1;
  83         bpf_map_update_elem(control_map_fd, &key, &val, 0);
  84
  85         /* for every element in stackid_hmap, we can find a corresponding one
  86          * in stackmap, and vise versa.
  87          */
  88         err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
  89         if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
  90                   "err %d errno %d\n", err, errno))
  91                 goto cleanup;
  92
  93         err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
  94         if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
  95                   "err %d errno %d\n", err, errno))
  96                 goto cleanup;
  97
  98         err = extract_build_id(buf, 256);
  99
 100         if (CHECK(err, "get build_id with readelf",
 101                   "err %d errno %d\n", err, errno))
 102                 goto cleanup;
 103
 104         err = bpf_map_get_next_key(stackmap_fd, NULL, &key);
 105         if (CHECK(err, "get_next_key from stackmap",
 106                   "err %d, errno %d\n", err, errno))
 107                 goto cleanup;
 108
 109         do {
 110                 char build_id[64];
 111
 112                 err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
 113                 if (CHECK(err, "lookup_elem from stackmap",
 114                           "err %d, errno %d\n", err, errno))
 115                         goto cleanup;
 116                 for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
 117                         if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
 118                             id_offs[i].offset != 0) {
 119                                 for (j = 0; j < 20; ++j)
 120                                         sprintf(build_id + 2 * j, "%02x",
 121                                                 id_offs[i].build_id[j] & 0xff);
 122                                 if (strstr(buf, build_id) != NULL)
 123                                         build_id_matches = 1;
 124                         }
 125                 previous_key = key;
 126         } while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);
 127
 128         /* stack_map_get_build_id_offset() is racy and sometimes can return
 129          * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
 130          * try it one more time.
 131          */
 132         if (build_id_matches < 1 && retry--) {
 133                 test_stacktrace_build_id__destroy(skel);
 134                 printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
 135                        __func__);
 136                 goto retry;
 137         }
 138
 139         if (CHECK(build_id_matches < 1, "build id match",
 140                   "Didn't find expected build ID from the map\n"))
 141                 goto cleanup;
 142
 143         /*
 144          * We intentionally skip compare_stack_ips(). This is because we
 145          * only support one in_nmi() ips-to-build_id translation per cpu
 146          * at any time, thus stack_amap here will always fallback to
 147          * BPF_STACK_BUILD_ID_IP;
 148          */
 149
 150 cleanup:
 151         test_stacktrace_build_id__destroy(skel);
 152 }