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tools/bpf: add a test for bpf_get_stack with tracepoint prog
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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>
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Yonghong Song authored and Alexei Starovoitov committed Apr 29, 2018
1 parent 173965f commit 79b4535
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Showing 3 changed files with 98 additions and 11 deletions.
70 changes: 64 additions & 6 deletions tools/testing/selftests/bpf/test_progs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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);

Expand All @@ -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++;
Expand Down Expand Up @@ -1080,9 +1126,9 @@ static int extract_build_id(char *build_id, size_t size)

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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand Down
20 changes: 18 additions & 2 deletions tools/testing/selftests/bpf/test_stacktrace_build_id.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 = {
Expand All @@ -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;
Expand All @@ -42,16 +50,24 @@ 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)
return 0; /* skip if non-zero *value_p */

/* 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;
}
Expand Down
19 changes: 16 additions & 3 deletions tools/testing/selftests/bpf/test_stacktrace_map.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand All @@ -44,16 +51,22 @@ 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)
return 0; /* skip if non-zero *value_p */

/* 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;
}
Expand Down

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