tools/bpf: add a test for bpf_get_stack with tracepoint prog

The test_stacktrace_map and test_stacktrace_build_id are
enhanced to call bpf_get_stack in the helper to get the
stack trace as well.  The stack traces from bpf_get_stack
and bpf_get_stackid are compared to ensure that for the
same stack as represented as the same hash, their ip addresses
or build id's must be the same.

Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 0ddbf34b2438dfd1effcb2a9262baccee24bd24f..aa336f0abebc325f00a4bb68ecdfc3635e9d76e7 100644 (file)
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -906,11 +906,47 @@ static int compare_map_keys(int map1_fd, int map2_fd)
        return 0;
 }
 
+static int compare_stack_ips(int smap_fd, int amap_fd, int stack_trace_len)
+{
+       __u32 key, next_key, *cur_key_p, *next_key_p;
+       char *val_buf1, *val_buf2;
+       int i, err = 0;
+
+       val_buf1 = malloc(stack_trace_len);
+       val_buf2 = malloc(stack_trace_len);
+       cur_key_p = NULL;
+       next_key_p = &key;
+       while (bpf_map_get_next_key(smap_fd, cur_key_p, next_key_p) == 0) {
+               err = bpf_map_lookup_elem(smap_fd, next_key_p, val_buf1);
+               if (err)
+                       goto out;
+               err = bpf_map_lookup_elem(amap_fd, next_key_p, val_buf2);
+               if (err)
+                       goto out;
+               for (i = 0; i < stack_trace_len; i++) {
+                       if (val_buf1[i] != val_buf2[i]) {
+                               err = -1;
+                               goto out;
+                       }
+               }
+               key = *next_key_p;
+               cur_key_p = &key;
+               next_key_p = &next_key;
+       }
+       if (errno != ENOENT)
+               err = -1;
+
+out:
+       free(val_buf1);
+       free(val_buf2);
+       return err;
+}
+
 static void test_stacktrace_map()
 {
-       int control_map_fd, stackid_hmap_fd, stackmap_fd;
+       int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
        const char *file = "./test_stacktrace_map.o";
-       int bytes, efd, err, pmu_fd, prog_fd;
+       int bytes, efd, err, pmu_fd, prog_fd, stack_trace_len;
        struct perf_event_attr attr = {};
        __u32 key, val, duration = 0;
        struct bpf_object *obj;
@@ -966,6 +1002,10 @@ static void test_stacktrace_map()
        if (stackmap_fd < 0)
                goto disable_pmu;
 
+       stack_amap_fd = bpf_find_map(__func__, obj, "stack_amap");
+       if (stack_amap_fd < 0)
+               goto disable_pmu;
+
        /* give some time for bpf program run */
        sleep(1);
 
@@ -987,6 +1027,12 @@ static void test_stacktrace_map()
                  "err %d errno %d\n", err, errno))
                goto disable_pmu_noerr;
 
+       stack_trace_len = PERF_MAX_STACK_DEPTH * sizeof(__u64);
+       err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
+       if (CHECK(err, "compare_stack_ips stackmap vs. stack_amap",
+                 "err %d errno %d\n", err, errno))
+               goto disable_pmu_noerr;
+
        goto disable_pmu_noerr;
 disable_pmu:
        error_cnt++;
@@ -1080,9 +1126,9 @@ err:
 
 static void test_stacktrace_build_id(void)
 {
-       int control_map_fd, stackid_hmap_fd, stackmap_fd;
+       int control_map_fd, stackid_hmap_fd, stackmap_fd, stack_amap_fd;
        const char *file = "./test_stacktrace_build_id.o";
-       int bytes, efd, err, pmu_fd, prog_fd;
+       int bytes, efd, err, pmu_fd, prog_fd, stack_trace_len;
        struct perf_event_attr attr = {};
        __u32 key, previous_key, val, duration = 0;
        struct bpf_object *obj;
@@ -1147,6 +1193,11 @@ static void test_stacktrace_build_id(void)
                  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("./urandom_read if=/dev/urandom of=/dev/zero count=4 2> /dev/null") == 0);
@@ -1198,8 +1249,15 @@ static void test_stacktrace_build_id(void)
                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");
+       if (CHECK(build_id_matches < 1, "build id match",
+                 "Didn't find expected build ID from the map"))
+               goto disable_pmu;
+
+       stack_trace_len = PERF_MAX_STACK_DEPTH
+               * sizeof(struct bpf_stack_build_id);
+       err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
+       CHECK(err, "compare_stack_ips stackmap vs. stack_amap",
+             "err %d errno %d\n", err, errno);
 
 disable_pmu:
        ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);

diff --git a/tools/testing/selftests/bpf/test_stacktrace_build_id.c b/tools/testing/selftests/bpf/test_stacktrace_build_id.c
index b755bd783ce5acca3c86e6f6264d728c02a5c3cf..d86c281e957fd9c3cf2baaecb3844f057b3fb05f 100644 (file)
--- a/tools/testing/selftests/bpf/test_stacktrace_build_id.c
+++ b/tools/testing/selftests/bpf/test_stacktrace_build_id.c
@@ -19,7 +19,7 @@ struct bpf_map_def SEC("maps") stackid_hmap = {
        .type = BPF_MAP_TYPE_HASH,
        .key_size = sizeof(__u32),
        .value_size = sizeof(__u32),
-       .max_entries = 10000,
+       .max_entries = 16384,
 };
 
 struct bpf_map_def SEC("maps") stackmap = {
@@ -31,6 +31,14 @@ struct bpf_map_def SEC("maps") stackmap = {
        .map_flags = BPF_F_STACK_BUILD_ID,
 };
 
+struct bpf_map_def SEC("maps") stack_amap = {
+       .type = BPF_MAP_TYPE_ARRAY,
+       .key_size = sizeof(__u32),
+       .value_size = sizeof(struct bpf_stack_build_id)
+               * PERF_MAX_STACK_DEPTH,
+       .max_entries = 128,
+};
+
 /* taken from /sys/kernel/debug/tracing/events/random/urandom_read/format */
 struct random_urandom_args {
        unsigned long long pad;
@@ -42,7 +50,10 @@ struct random_urandom_args {
 SEC("tracepoint/random/urandom_read")
 int oncpu(struct random_urandom_args *args)
 {
+       __u32 max_len = sizeof(struct bpf_stack_build_id)
+                       * PERF_MAX_STACK_DEPTH;
        __u32 key = 0, val = 0, *value_p;
+       void *stack_p;
 
        value_p = bpf_map_lookup_elem(&control_map, &key);
        if (value_p && *value_p)
@@ -50,8 +61,13 @@ int oncpu(struct random_urandom_args *args)
 
        /* The size of stackmap and stackid_hmap should be the same */
        key = bpf_get_stackid(args, &stackmap, BPF_F_USER_STACK);
-       if ((int)key >= 0)
+       if ((int)key >= 0) {
                bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
+               stack_p = bpf_map_lookup_elem(&stack_amap, &key);
+               if (stack_p)
+                       bpf_get_stack(args, stack_p, max_len,
+                                     BPF_F_USER_STACK | BPF_F_USER_BUILD_ID);
+       }
 
        return 0;
 }

diff --git a/tools/testing/selftests/bpf/test_stacktrace_map.c b/tools/testing/selftests/bpf/test_stacktrace_map.c
index 76d85c5d08bdbc95af3f9e60c9a89f98e836f41e..af111af7ca1a737ddf4db6b83b0f1370930b5992 100644 (file)
--- a/tools/testing/selftests/bpf/test_stacktrace_map.c
+++ b/tools/testing/selftests/bpf/test_stacktrace_map.c
@@ -19,14 +19,21 @@ struct bpf_map_def SEC("maps") stackid_hmap = {
        .type = BPF_MAP_TYPE_HASH,
        .key_size = sizeof(__u32),
        .value_size = sizeof(__u32),
-       .max_entries = 10000,
+       .max_entries = 16384,
 };
 
 struct bpf_map_def SEC("maps") stackmap = {
        .type = BPF_MAP_TYPE_STACK_TRACE,
        .key_size = sizeof(__u32),
        .value_size = sizeof(__u64) * PERF_MAX_STACK_DEPTH,
-       .max_entries = 10000,
+       .max_entries = 16384,
+};
+
+struct bpf_map_def SEC("maps") stack_amap = {
+       .type = BPF_MAP_TYPE_ARRAY,
+       .key_size = sizeof(__u32),
+       .value_size = sizeof(__u64) * PERF_MAX_STACK_DEPTH,
+       .max_entries = 16384,
 };
 
 /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */
@@ -44,7 +51,9 @@ struct sched_switch_args {
 SEC("tracepoint/sched/sched_switch")
 int oncpu(struct sched_switch_args *ctx)
 {
+       __u32 max_len = PERF_MAX_STACK_DEPTH * sizeof(__u64);
        __u32 key = 0, val = 0, *value_p;
+       void *stack_p;
 
        value_p = bpf_map_lookup_elem(&control_map, &key);
        if (value_p && *value_p)
@@ -52,8 +61,12 @@ int oncpu(struct sched_switch_args *ctx)
 
        /* The size of stackmap and stackid_hmap should be the same */
        key = bpf_get_stackid(ctx, &stackmap, 0);
-       if ((int)key >= 0)
+       if ((int)key >= 0) {
                bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
+               stack_p = bpf_map_lookup_elem(&stack_amap, &key);
+               if (stack_p)
+                       bpf_get_stack(ctx, stack_p, max_len, 0);
+       }
 
        return 0;
 }