Commit e1cc1f39 authored by Namhyung Kim's avatar Namhyung Kim Committed by Alexei Starovoitov
Browse files

selftests/bpf: Test skipping stacktrace 



Add a test case for stacktrace with skip > 0 using a small sized
buffer.  It didn't support skipping entries greater than or equal to
the size of buffer and filled the skipped part with 0.

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220314182042.71025-2-namhyung@kernel.org
parent ee2a0988

tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c

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// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>

#include "stacktrace_map_skip.skel.h"



#define TEST_STACK_DEPTH  2



void test_stacktrace_map_skip(void)

{

	struct stacktrace_map_skip *skel;

	int stackid_hmap_fd, stackmap_fd, stack_amap_fd;

	int err, stack_trace_len;



	skel = stacktrace_map_skip__open_and_load();

	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))

		return;



	/* find map fds */

	stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);

	if (!ASSERT_GE(stackid_hmap_fd, 0, "stackid_hmap fd"))

		goto out;



	stackmap_fd = bpf_map__fd(skel->maps.stackmap);

	if (!ASSERT_GE(stackmap_fd, 0, "stackmap fd"))

		goto out;



	stack_amap_fd = bpf_map__fd(skel->maps.stack_amap);

	if (!ASSERT_GE(stack_amap_fd, 0, "stack_amap fd"))

		goto out;



	skel->bss->pid = getpid();



	err = stacktrace_map_skip__attach(skel);

	if (!ASSERT_OK(err, "skel_attach"))

		goto out;



	/* give some time for bpf program run */

	sleep(1);



	/* disable stack trace collection */

	skel->bss->control = 1;



	/* 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 (!ASSERT_OK(err, "compare_map_keys stackid_hmap vs. stackmap"))

		goto out;



	err = compare_map_keys(stackmap_fd, stackid_hmap_fd);

	if (!ASSERT_OK(err, "compare_map_keys stackmap vs. stackid_hmap"))

		goto out;



	stack_trace_len = TEST_STACK_DEPTH * sizeof(__u64);

	err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);

	if (!ASSERT_OK(err, "compare_stack_ips stackmap vs. stack_amap"))

		goto out;



	if (!ASSERT_EQ(skel->bss->failed, 0, "skip_failed"))

		goto out;



out:

	stacktrace_map_skip__destroy(skel);

}

tools/testing/selftests/bpf/progs/stacktrace_map_skip.c

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// SPDX-License-Identifier: GPL-2.0

#include <vmlinux.h>

#include <bpf/bpf_helpers.h>



#define TEST_STACK_DEPTH	2

#define TEST_MAX_ENTRIES	16384



typedef __u64 stack_trace_t[TEST_STACK_DEPTH];



struct {

	__uint(type, BPF_MAP_TYPE_STACK_TRACE);

	__uint(max_entries, TEST_MAX_ENTRIES);

	__type(key, __u32);

	__type(value, stack_trace_t);

} stackmap SEC(".maps");



struct {

	__uint(type, BPF_MAP_TYPE_HASH);

	__uint(max_entries, TEST_MAX_ENTRIES);

	__type(key, __u32);

	__type(value, __u32);

} stackid_hmap SEC(".maps");



struct {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__uint(max_entries, TEST_MAX_ENTRIES);

	__type(key, __u32);

	__type(value, stack_trace_t);

} stack_amap SEC(".maps");



int pid = 0;

int control = 0;

int failed = 0;



SEC("tracepoint/sched/sched_switch")

int oncpu(struct trace_event_raw_sched_switch *ctx)

{

	__u32 max_len = TEST_STACK_DEPTH * sizeof(__u64);

	__u32 key = 0, val = 0;

	__u64 *stack_p;



	if (pid != (bpf_get_current_pid_tgid() >> 32))

		return 0;



	if (control)

		return 0;



	/* it should allow skipping whole buffer size entries */

	key = bpf_get_stackid(ctx, &stackmap, TEST_STACK_DEPTH);

	if ((int)key >= 0) {

		/* The size of stackmap and stack_amap should be the same */

		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, TEST_STACK_DEPTH);

			/* it wrongly skipped all the entries and filled zero */

			if (stack_p[0] == 0)

				failed = 1;

		}

	} else {

		/* old kernel doesn't support skipping that many entries */

		failed = 2;

	}



	return 0;

}



char _license[] SEC("license") = "GPL";