stacktrace_build_id_nmi.c (4534B)
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, prev_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_type(skel->progs.oncpu, BPF_PROG_TYPE_PERF_EVENT); 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(skel->maps.stackmap, NULL, &key, sizeof(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(skel->maps.stackmap, &key, sizeof(key), 112 id_offs, sizeof(id_offs), 0); 113 if (CHECK(err, "lookup_elem from stackmap", 114 "err %d, errno %d\n", err, errno)) 115 goto cleanup; 116 for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i) 117 if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID && 118 id_offs[i].offset != 0) { 119 for (j = 0; j < 20; ++j) 120 sprintf(build_id + 2 * j, "%02x", 121 id_offs[i].build_id[j] & 0xff); 122 if (strstr(buf, build_id) != NULL) 123 build_id_matches = 1; 124 } 125 prev_key = key; 126 } while (bpf_map__get_next_key(skel->maps.stackmap, &prev_key, &key, sizeof(key)) == 0); 127 128 /* stack_map_get_build_id_offset() is racy and sometimes can return 129 * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID; 130 * try it one more time. 131 */ 132 if (build_id_matches < 1 && retry--) { 133 test_stacktrace_build_id__destroy(skel); 134 printf("%s:WARN:Didn't find expected build ID from the map, retrying\n", 135 __func__); 136 goto retry; 137 } 138 139 if (CHECK(build_id_matches < 1, "build id match", 140 "Didn't find expected build ID from the map\n")) 141 goto cleanup; 142 143 /* 144 * We intentionally skip compare_stack_ips(). This is because we 145 * only support one in_nmi() ips-to-build_id translation per cpu 146 * at any time, thus stack_amap here will always fallback to 147 * BPF_STACK_BUILD_ID_IP; 148 */ 149 150cleanup: 151 test_stacktrace_build_id__destroy(skel); 152}