LXR linux/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id

   1// SPDX-License-Identifier: GPL-2.0
   2#include <test_progs.h>
   3#include "test_stacktrace_build_id.skel.h"
   4
   5static __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
  20void 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
  39retry:
  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 (!ASSERT_OK_PTR(skel->links.oncpu, "attach_perf_event")) {
  66                close(pmu_fd);
  67                goto cleanup;
  68        }
  69
  70        /* find map fds */
  71        control_map_fd = bpf_map__fd(skel->maps.control_map);
  72        stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);
  73        stackmap_fd = bpf_map__fd(skel->maps.stackmap);
  74
  75        if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")))
  76                goto cleanup;
  77        if (CHECK_FAIL(system("taskset 0x1 ./urandom_read 100000")))
  78                goto cleanup;
  79        /* disable stack trace collection */
  80        key = 0;
  81        val = 1;
  82        bpf_map_update_elem(control_map_fd, &key, &val, 0);
  83
  84        /* for every element in stackid_hmap, we can find a corresponding one
  85         * in stackmap, and vise versa.
  86         */
  87        err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
  88        if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
  89                  "err %d errno %d\n", err, errno))
  90                goto cleanup;
  91
  92        err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
  93        if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
  94                  "err %d errno %d\n", err, errno))
  95                goto cleanup;
  96
  97        err = extract_build_id(buf, 256);
  98
  99        if (CHECK(err, "get build_id with readelf",
 100                  "err %d errno %d\n", err, errno))
 101                goto cleanup;
 102
 103        err = bpf_map_get_next_key(stackmap_fd, NULL, &key);
 104        if (CHECK(err, "get_next_key from stackmap",
 105                  "err %d, errno %d\n", err, errno))
 106                goto cleanup;
 107
 108        do {
 109                char build_id[64];
 110
 111                err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
 112                if (CHECK(err, "lookup_elem from stackmap",
 113                          "err %d, errno %d\n", err, errno))
 114                        goto cleanup;
 115                for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
 116                        if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
 117                            id_offs[i].offset != 0) {
 118                                for (j = 0; j < 20; ++j)
 119                                        sprintf(build_id + 2 * j, "%02x",
 120                                                id_offs[i].build_id[j] & 0xff);
 121                                if (strstr(buf, build_id) != NULL)
 122                                        build_id_matches = 1;
 123                        }
 124                previous_key = key;
 125        } while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);
 126
 127        /* stack_map_get_build_id_offset() is racy and sometimes can return
 128         * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
 129         * try it one more time.
 130         */
 131        if (build_id_matches < 1 && retry--) {
 132                test_stacktrace_build_id__destroy(skel);
 133                printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
 134                       __func__);
 135                goto retry;
 136        }
 137
 138        if (CHECK(build_id_matches < 1, "build id match",
 139                  "Didn't find expected build ID from the map\n"))
 140                goto cleanup;
 141
 142        /*
 143         * We intentionally skip compare_stack_ips(). This is because we
 144         * only support one in_nmi() ips-to-build_id translation per cpu
 145         * at any time, thus stack_amap here will always fallback to
 146         * BPF_STACK_BUILD_ID_IP;
 147         */
 148
 149cleanup:
 150        test_stacktrace_build_id__destroy(skel);
 151}
 152