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 void test_stacktrace_build_id_nmi(void)
   6 {
   7         int control_map_fd, stackid_hmap_fd, stackmap_fd;
   8         struct test_stacktrace_build_id *skel;
   9         int err, pmu_fd;
  10         struct perf_event_attr attr = {
  11                 .freq = 1,
  12                 .type = PERF_TYPE_HARDWARE,
  13                 .config = PERF_COUNT_HW_CPU_CYCLES,
  14         };
  15         __u32 key, prev_key, val, duration = 0;
  16         char buf[BPF_BUILD_ID_SIZE];
  17         struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
  18         int build_id_matches = 0, build_id_size;
  19         int i, retry = 1;
  20
  21         attr.sample_freq = read_perf_max_sample_freq();
  22
  23 retry:
  24         skel = test_stacktrace_build_id__open();
  25         if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
  26                 return;
  27
  28         /* override program type */
  29         bpf_program__set_type(skel->progs.oncpu, BPF_PROG_TYPE_PERF_EVENT);
  30
  31         err = test_stacktrace_build_id__load(skel);
  32         if (CHECK(err, "skel_load", "skeleton load failed: %d\n", err))
  33                 goto cleanup;
  34
  35         pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
  36                          0 /* cpu 0 */, -1 /* group id */,
  37                          0 /* flags */);
  38         if (pmu_fd < 0 && (errno == ENOENT || errno == EOPNOTSUPP)) {
  39                 printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n", __func__);
  40                 test__skip();
  41                 goto cleanup;
  42         }
  43         if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
  44                   pmu_fd, errno))
  45                 goto cleanup;
  46
  47         skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu,
  48                                                            pmu_fd);
  49         if (!ASSERT_OK_PTR(skel->links.oncpu, "attach_perf_event")) {
  50                 close(pmu_fd);
  51                 goto cleanup;
  52         }
  53
  54         /* find map fds */
  55         control_map_fd = bpf_map__fd(skel->maps.control_map);
  56         stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);
  57         stackmap_fd = bpf_map__fd(skel->maps.stackmap);
  58
  59         if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")))
  60                 goto cleanup;
  61         if (CHECK_FAIL(system("taskset 0x1 ./urandom_read 100000")))
  62                 goto cleanup;
  63         /* disable stack trace collection */
  64         key = 0;
  65         val = 1;
  66         bpf_map_update_elem(control_map_fd, &key, &val, 0);
  67
  68         /* for every element in stackid_hmap, we can find a corresponding one
  69          * in stackmap, and vise versa.
  70          */
  71         err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
  72         if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
  73                   "err %d errno %d\n", err, errno))
  74                 goto cleanup;
  75
  76         err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
  77         if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
  78                   "err %d errno %d\n", err, errno))
  79                 goto cleanup;
  80
  81         build_id_size = read_build_id("urandom_read", buf, sizeof(buf));
  82         err = build_id_size < 0 ? build_id_size : 0;
  83
  84         if (CHECK(err, "get build_id with readelf",
  85                   "err %d errno %d\n", err, errno))
  86                 goto cleanup;
  87
  88         err = bpf_map__get_next_key(skel->maps.stackmap, NULL, &key, sizeof(key));
  89         if (CHECK(err, "get_next_key from stackmap",
  90                   "err %d, errno %d\n", err, errno))
  91                 goto cleanup;
  92
  93         do {
  94                 err = bpf_map__lookup_elem(skel->maps.stackmap, &key, sizeof(key),
  95                                            id_offs, sizeof(id_offs), 0);
  96                 if (CHECK(err, "lookup_elem from stackmap",
  97                           "err %d, errno %d\n", err, errno))
  98                         goto cleanup;
  99                 for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
 100                         if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
 101                             id_offs[i].offset != 0) {
 102                                 if (memcmp(buf, id_offs[i].build_id, build_id_size) == 0)
 103                                         build_id_matches = 1;
 104                         }
 105                 prev_key = key;
 106         } while (bpf_map__get_next_key(skel->maps.stackmap, &prev_key, &key, sizeof(key)) == 0);
 107
 108         /* stack_map_get_build_id_offset() is racy and sometimes can return
 109          * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
 110          * try it one more time.
 111          */
 112         if (build_id_matches < 1 && retry--) {
 113                 test_stacktrace_build_id__destroy(skel);
 114                 printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
 115                        __func__);
 116                 goto retry;
 117         }
 118
 119         if (CHECK(build_id_matches < 1, "build id match",
 120                   "Didn't find expected build ID from the map\n"))
 121                 goto cleanup;
 122
 123         /*
 124          * We intentionally skip compare_stack_ips(). This is because we
 125          * only support one in_nmi() ips-to-build_id translation per cpu
 126          * at any time, thus stack_amap here will always fallback to
 127          * BPF_STACK_BUILD_ID_IP;
 128          */
 129
 130 cleanup:
 131         test_stacktrace_build_id__destroy(skel);
 132 }