diff options
Diffstat (limited to 'tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c')
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c new file mode 100644 index 000000000..11a769e18 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c @@ -0,0 +1,152 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <test_progs.h> +#include "test_stacktrace_build_id.skel.h" + +static __u64 read_perf_max_sample_freq(void) +{ + __u64 sample_freq = 5000; /* fallback to 5000 on error */ + FILE *f; + __u32 duration = 0; + + f = fopen("/proc/sys/kernel/perf_event_max_sample_rate", "r"); + if (f == NULL) + return sample_freq; + CHECK(fscanf(f, "%llu", &sample_freq) != 1, "Get max sample rate", + "return default value: 5000,err %d\n", -errno); + fclose(f); + return sample_freq; +} + +void test_stacktrace_build_id_nmi(void) +{ + int control_map_fd, stackid_hmap_fd, stackmap_fd; + struct test_stacktrace_build_id *skel; + int err, pmu_fd; + struct perf_event_attr attr = { + .freq = 1, + .type = PERF_TYPE_HARDWARE, + .config = PERF_COUNT_HW_CPU_CYCLES, + }; + __u32 key, previous_key, val, duration = 0; + char buf[256]; + int i, j; + struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH]; + int build_id_matches = 0; + int retry = 1; + + attr.sample_freq = read_perf_max_sample_freq(); + +retry: + skel = test_stacktrace_build_id__open(); + if (CHECK(!skel, "skel_open", "skeleton open failed\n")) + return; + + /* override program type */ + bpf_program__set_perf_event(skel->progs.oncpu); + + err = test_stacktrace_build_id__load(skel); + if (CHECK(err, "skel_load", "skeleton load failed: %d\n", err)) + goto cleanup; + + pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, + 0 /* cpu 0 */, -1 /* group id */, + 0 /* flags */); + if (pmu_fd < 0 && errno == ENOENT) { + printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n", __func__); + test__skip(); + goto cleanup; + } + if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n", + pmu_fd, errno)) + goto cleanup; + + skel->links.oncpu = bpf_program__attach_perf_event(skel->progs.oncpu, + pmu_fd); + if (CHECK(IS_ERR(skel->links.oncpu), "attach_perf_event", + "err %ld\n", PTR_ERR(skel->links.oncpu))) { + close(pmu_fd); + goto cleanup; + } + + /* find map fds */ + control_map_fd = bpf_map__fd(skel->maps.control_map); + stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap); + stackmap_fd = bpf_map__fd(skel->maps.stackmap); + + if (CHECK_FAIL(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null"))) + goto cleanup; + if (CHECK_FAIL(system("taskset 0x1 ./urandom_read 100000"))) + goto cleanup; + /* disable stack trace collection */ + key = 0; + val = 1; + bpf_map_update_elem(control_map_fd, &key, &val, 0); + + /* for every element in stackid_hmap, we can find a corresponding one + * in stackmap, and vise versa. + */ + err = compare_map_keys(stackid_hmap_fd, stackmap_fd); + if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap", + "err %d errno %d\n", err, errno)) + goto cleanup; + + err = compare_map_keys(stackmap_fd, stackid_hmap_fd); + if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap", + "err %d errno %d\n", err, errno)) + goto cleanup; + + err = extract_build_id(buf, 256); + + if (CHECK(err, "get build_id with readelf", + "err %d errno %d\n", err, errno)) + goto cleanup; + + err = bpf_map_get_next_key(stackmap_fd, NULL, &key); + if (CHECK(err, "get_next_key from stackmap", + "err %d, errno %d\n", err, errno)) + goto cleanup; + + do { + char build_id[64]; + + err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs); + if (CHECK(err, "lookup_elem from stackmap", + "err %d, errno %d\n", err, errno)) + goto cleanup; + for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i) + if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID && + id_offs[i].offset != 0) { + for (j = 0; j < 20; ++j) + sprintf(build_id + 2 * j, "%02x", + id_offs[i].build_id[j] & 0xff); + if (strstr(buf, build_id) != NULL) + build_id_matches = 1; + } + previous_key = key; + } while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0); + + /* stack_map_get_build_id_offset() is racy and sometimes can return + * BPF_STACK_BUILD_ID_IP instead of BPF_STACK_BUILD_ID_VALID; + * try it one more time. + */ + if (build_id_matches < 1 && retry--) { + test_stacktrace_build_id__destroy(skel); + printf("%s:WARN:Didn't find expected build ID from the map, retrying\n", + __func__); + goto retry; + } + + if (CHECK(build_id_matches < 1, "build id match", + "Didn't find expected build ID from the map\n")) + goto cleanup; + + /* + * We intentionally skip compare_stack_ips(). This is because we + * only support one in_nmi() ips-to-build_id translation per cpu + * at any time, thus stack_amap here will always fallback to + * BPF_STACK_BUILD_ID_IP; + */ + +cleanup: + test_stacktrace_build_id__destroy(skel); +} |