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 } 133