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

   1// SPDX-License-Identifier: GPL-2.0
   2#include <test_progs.h>
   3
   4void 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
  20retry:
  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        if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")))
  55                goto disable_pmu;
  56        if (CHECK_FAIL(system("./urandom_read")))
  57                goto disable_pmu;
  58        /* disable stack trace collection */
  59        key = 0;
  60        val = 1;
  61        bpf_map_update_elem(control_map_fd, &key, &val, 0);
  62
  63        /* for every element in stackid_hmap, we can find a corresponding one
  64         * in stackmap, and vise versa.
  65         */
  66        err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
  67        if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
  68                  "err %d errno %d\n", err, errno))
  69                goto disable_pmu;
  70
  71        err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
  72        if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
  73                  "err %d errno %d\n", err, errno))
  74                goto disable_pmu;
  75
  76        err = extract_build_id(buf, 256);
  77
  78        if (CHECK(err, "get build_id with readelf",
  79                  "err %d errno %d\n", err, errno))
  80                goto disable_pmu;
  81
  82        err = bpf_map_get_next_key(stackmap_fd, NULL, &key);
  83        if (CHECK(err, "get_next_key from stackmap",
  84                  "err %d, errno %d\n", err, errno))
  85                goto disable_pmu;
  86
  87        do {
  88                char build_id[64];
  89
  90                err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
  91                if (CHECK(err, "lookup_elem from stackmap",
  92                          "err %d, errno %d\n", err, errno))
  93                        goto disable_pmu;
  94                for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
  95                        if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
  96                            id_offs[i].offset != 0) {
  97                                for (j = 0; j < 20; ++j)
  98                                        sprintf(build_id + 2 * j, "%02x",
  99                                                id_offs[i].build_id[j] & 0xff);
 100                                if (strstr(buf, build_id) != NULL)
 101                                        build_id_matches = 1;
 102                        }
 103                previous_key = key;
 104        } while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);
 105
 106        /* stack_map_get_build_id_offset() is racy and sometimes can return
 107         * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID;
 108         * try it one more time.
 109         */
 110        if (build_id_matches < 1 && retry--) {
 111                bpf_link__destroy(link);
 112                bpf_object__close(obj);
 113                printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
 114                       __func__);
 115                goto retry;
 116        }
 117
 118        if (CHECK(build_id_matches < 1, "build id match",
 119                  "Didn't find expected build ID from the map\n"))
 120                goto disable_pmu;
 121
 122        stack_trace_len = PERF_MAX_STACK_DEPTH
 123                * sizeof(struct bpf_stack_build_id);
 124        err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
 125        CHECK(err, "compare_stack_ips stackmap vs. stack_amap",
 126              "err %d errno %d\n", err, errno);
 127
 128disable_pmu:
 129        bpf_link__destroy(link);
 130
 131close_prog:
 132        bpf_object__close(obj);
 133}
 134