Commit 01e4ae47 authored by Jiri Olsa's avatar Jiri Olsa Committed by Andrii Nakryiko
Browse files

selftests/bpf: Add test for missed counts of perf event link kprobe 



Adding test that puts kprobe on bpf_fentry_test1 that calls
bpf_kfunc_common_test kfunc, which has also kprobe on.

The latter won't get triggered due to kprobe recursion check
and kprobe missed counter is incremented.

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarHou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20230920213145.1941596-8-jolsa@kernel.org
parent b563b9ba

tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c

+5 −0
Original line number Diff line number Diff line
@@ -138,6 +138,10 @@ __bpf_kfunc void bpf_iter_testmod_seq_destroy(struct bpf_iter_testmod_seq *it) 
	it->cnt = 0;

}



__bpf_kfunc void bpf_kfunc_common_test(void)

{

}



struct bpf_testmod_btf_type_tag_1 {

	int a;

};
@@ -343,6 +347,7 @@ BTF_SET8_START(bpf_testmod_common_kfunc_ids) 
BTF_ID_FLAGS(func, bpf_iter_testmod_seq_new, KF_ITER_NEW)

BTF_ID_FLAGS(func, bpf_iter_testmod_seq_next, KF_ITER_NEXT | KF_RET_NULL)

BTF_ID_FLAGS(func, bpf_iter_testmod_seq_destroy, KF_ITER_DESTROY)

BTF_ID_FLAGS(func, bpf_kfunc_common_test)

BTF_SET8_END(bpf_testmod_common_kfunc_ids)



static const struct btf_kfunc_id_set bpf_testmod_common_kfunc_set = {

tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h

+2 −0
Original line number Diff line number Diff line
@@ -104,4 +104,6 @@ void bpf_kfunc_call_test_fail1(struct prog_test_fail1 *p); 
void bpf_kfunc_call_test_fail2(struct prog_test_fail2 *p);

void bpf_kfunc_call_test_fail3(struct prog_test_fail3 *p);

void bpf_kfunc_call_test_mem_len_fail1(void *mem, int len);



void bpf_kfunc_common_test(void) __ksym;

#endif /* _BPF_TESTMOD_KFUNC_H */

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

0 → 100644
+47 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>

#include "missed_kprobe.skel.h"



/*

 * Putting kprobe on bpf_fentry_test1 that calls bpf_kfunc_common_test

 * kfunc, which has also kprobe on. The latter won't get triggered due

 * to kprobe recursion check and kprobe missed counter is incremented.

 */

static void test_missed_perf_kprobe(void)

{

	LIBBPF_OPTS(bpf_test_run_opts, topts);

	struct bpf_link_info info = {};

	struct missed_kprobe *skel;

	__u32 len = sizeof(info);

	int err, prog_fd;



	skel = missed_kprobe__open_and_load();

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

		goto cleanup;



	err = missed_kprobe__attach(skel);

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

		goto cleanup;



	prog_fd = bpf_program__fd(skel->progs.trigger);

	err = bpf_prog_test_run_opts(prog_fd, &topts);

	ASSERT_OK(err, "test_run");

	ASSERT_EQ(topts.retval, 0, "test_run");



	err = bpf_link_get_info_by_fd(bpf_link__fd(skel->links.test2), &info, &len);

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

		goto cleanup;



	ASSERT_EQ(info.type, BPF_LINK_TYPE_PERF_EVENT, "info.type");

	ASSERT_EQ(info.perf_event.type, BPF_PERF_EVENT_KPROBE, "info.perf_event.type");

	ASSERT_EQ(info.perf_event.kprobe.missed, 1, "info.perf_event.kprobe.missed");



cleanup:

	missed_kprobe__destroy(skel);

}



void test_missed(void)

{

	if (test__start_subtest("perf_kprobe"))

		test_missed_perf_kprobe();

}

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

0 → 100644
+30 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include "vmlinux.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include "../bpf_testmod/bpf_testmod_kfunc.h"



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



/*

 * No tests in here, just to trigger 'bpf_fentry_test*'

 * through tracing test_run

 */

SEC("fentry/bpf_modify_return_test")

int BPF_PROG(trigger)

{

	return 0;

}



SEC("kprobe/bpf_fentry_test1")

int test1(struct pt_regs *ctx)

{

	bpf_kfunc_common_test();

	return 0;

}



SEC("kprobe/bpf_kfunc_common_test")

int test2(struct pt_regs *ctx)

{

	return 0;

}