From 13790d1cc72c22f6e7a1248e5f6d20d720797e95 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Mon, 7 May 2018 10:50:49 -0700 Subject: bpf: add selftest for stackmap with build_id in NMI context This new test captures stackmap with build_id with hardware event PERF_COUNT_HW_CPU_CYCLES. Because we only support one ips-to-build_id lookup per cpu in NMI context, stack_amap will not be able to do the lookup in this test. Therefore, we didn't do compare_stack_ips(), as it will alwasy fail. urandom_read.c is extended to run configurable cycles so that it can be caught by the perf event. Signed-off-by: Song Liu Signed-off-by: Daniel Borkmann --- tools/testing/selftests/bpf/test_progs.c | 134 +++++++++++++++++++++++++++++++ 1 file changed, 134 insertions(+) (limited to 'tools/testing/selftests/bpf/test_progs.c') diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c index f7731973ec68..3ecf733330c1 100644 --- a/tools/testing/selftests/bpf/test_progs.c +++ b/tools/testing/selftests/bpf/test_progs.c @@ -1272,6 +1272,139 @@ out: return; } +static void test_stacktrace_build_id_nmi(void) +{ + int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd; + const char *file = "./test_stacktrace_build_id.o"; + int err, pmu_fd, prog_fd; + struct perf_event_attr attr = { + .sample_freq = 5000, + .freq = 1, + .type = PERF_TYPE_HARDWARE, + .config = PERF_COUNT_HW_CPU_CYCLES, + }; + __u32 key, previous_key, val, duration = 0; + struct bpf_object *obj; + char buf[256]; + int i, j; + struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH]; + int build_id_matches = 0; + + err = bpf_prog_load(file, BPF_PROG_TYPE_PERF_EVENT, &obj, &prog_fd); + if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno)) + return; + + pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, + 0 /* cpu 0 */, -1 /* group id */, + 0 /* flags */); + if (CHECK(pmu_fd < 0, "perf_event_open", + "err %d errno %d. Does the test host support PERF_COUNT_HW_CPU_CYCLES?\n", + pmu_fd, errno)) + goto close_prog; + + err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0); + if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n", + err, errno)) + goto close_pmu; + + err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); + if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n", + err, errno)) + goto disable_pmu; + + /* find map fds */ + control_map_fd = bpf_find_map(__func__, obj, "control_map"); + if (CHECK(control_map_fd < 0, "bpf_find_map control_map", + "err %d errno %d\n", err, errno)) + goto disable_pmu; + + stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap"); + if (CHECK(stackid_hmap_fd < 0, "bpf_find_map stackid_hmap", + "err %d errno %d\n", err, errno)) + goto disable_pmu; + + stackmap_fd = bpf_find_map(__func__, obj, "stackmap"); + if (CHECK(stackmap_fd < 0, "bpf_find_map stackmap", "err %d errno %d\n", + err, errno)) + goto disable_pmu; + + stack_amap_fd = bpf_find_map(__func__, obj, "stack_amap"); + if (CHECK(stack_amap_fd < 0, "bpf_find_map stack_amap", + "err %d errno %d\n", err, errno)) + goto disable_pmu; + + assert(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null") + == 0); + assert(system("taskset 0x1 ./urandom_read 100000") == 0); + /* 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 disable_pmu; + + 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 disable_pmu; + + err = extract_build_id(buf, 256); + + if (CHECK(err, "get build_id with readelf", + "err %d errno %d\n", err, errno)) + goto disable_pmu; + + 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 disable_pmu; + + 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 disable_pmu; + 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); + + if (CHECK(build_id_matches < 1, "build id match", + "Didn't find expected build ID from the map\n")) + goto disable_pmu; + + /* + * 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; + */ + +disable_pmu: + ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE); + +close_pmu: + close(pmu_fd); + +close_prog: + bpf_object__close(obj); +} + #define MAX_CNT_RAWTP 10ull #define MAX_STACK_RAWTP 100 struct get_stack_trace_t { @@ -1425,6 +1558,7 @@ int main(void) test_tp_attach_query(); test_stacktrace_map(); test_stacktrace_build_id(); + test_stacktrace_build_id_nmi(); test_stacktrace_map_raw_tp(); test_get_stack_raw_tp(); -- cgit v1.2.3-59-g8ed1b