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