bpf: add selftest for stackmap with BPF_F_STACK_BUILD_ID
test_stacktrace_build_id() is added. It accesses tracepoint urandom_read
with "dd" and "urandom_read" and gathers stack traces. Then it reads the
stack traces from the stackmap.
urandom_read is a statically link binary that reads from /dev/urandom.
test_stacktrace_build_id() calls readelf to read build ID of urandom_read
and compares it with build ID from the stackmap.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 27ad540..e9df48b 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -841,7 +841,8 @@ static void test_tp_attach_query(void)
static int compare_map_keys(int map1_fd, int map2_fd)
{
__u32 key, next_key;
- char val_buf[PERF_MAX_STACK_DEPTH * sizeof(__u64)];
+ char val_buf[PERF_MAX_STACK_DEPTH *
+ sizeof(struct bpf_stack_build_id)];
int err;
err = bpf_map_get_next_key(map1_fd, NULL, &key);
@@ -964,6 +965,166 @@ static void test_stacktrace_map()
return;
}
+static int extract_build_id(char *build_id, size_t size)
+{
+ FILE *fp;
+ char *line = NULL;
+ size_t len = 0;
+
+ fp = popen("readelf -n ./urandom_read | grep 'Build ID'", "r");
+ if (fp == NULL)
+ return -1;
+
+ if (getline(&line, &len, fp) == -1)
+ goto err;
+ fclose(fp);
+
+ if (len > size)
+ len = size;
+ memcpy(build_id, line, len);
+ build_id[len] = '\0';
+ return 0;
+err:
+ fclose(fp);
+ return -1;
+}
+
+static void test_stacktrace_build_id(void)
+{
+ int control_map_fd, stackid_hmap_fd, stackmap_fd;
+ const char *file = "./test_stacktrace_build_id.o";
+ int bytes, efd, err, pmu_fd, prog_fd;
+ struct perf_event_attr attr = {};
+ __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_TRACEPOINT, &obj, &prog_fd);
+ if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
+ goto out;
+
+ /* Get the ID for the sched/sched_switch tracepoint */
+ snprintf(buf, sizeof(buf),
+ "/sys/kernel/debug/tracing/events/random/urandom_read/id");
+ efd = open(buf, O_RDONLY, 0);
+ if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
+ goto close_prog;
+
+ bytes = read(efd, buf, sizeof(buf));
+ close(efd);
+ if (CHECK(bytes <= 0 || bytes >= sizeof(buf),
+ "read", "bytes %d errno %d\n", bytes, errno))
+ goto close_prog;
+
+ /* Open the perf event and attach bpf progrram */
+ attr.config = strtol(buf, NULL, 0);
+ attr.type = PERF_TYPE_TRACEPOINT;
+ attr.sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CALLCHAIN;
+ attr.sample_period = 1;
+ attr.wakeup_events = 1;
+ 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\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;
+
+ assert(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")
+ == 0);
+ assert(system("./urandom_read if=/dev/urandom of=/dev/zero count=4 2> /dev/null") == 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);
+
+ CHECK(build_id_matches < 1, "build id match",
+ "Didn't find expected build ID from the map");
+
+disable_pmu:
+ ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
+
+close_pmu:
+ close(pmu_fd);
+
+close_prog:
+ bpf_object__close(obj);
+
+out:
+ return;
+}
+
int main(void)
{
test_pkt_access();
@@ -976,6 +1137,7 @@ int main(void)
test_obj_name();
test_tp_attach_query();
test_stacktrace_map();
+ test_stacktrace_build_id();
printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
return error_cnt ? EXIT_FAILURE : EXIT_SUCCESS;