Commit 0983b169 authored by Jiri Olsa's avatar Jiri Olsa Committed by Andrii Nakryiko
Browse files

selftests/bpf: Add kprobe session test 



Adding kprobe session test and testing that the entry program
return value controls execution of the return probe program.

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240430112830.1184228-7-jolsa@kernel.org
parent 7b949654

tools/testing/selftests/bpf/bpf_kfuncs.h

+2 −0
Original line number Diff line number Diff line
@@ -75,4 +75,6 @@ extern void bpf_key_put(struct bpf_key *key) __ksym; 
extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,

				      struct bpf_dynptr *sig_ptr,

				      struct bpf_key *trusted_keyring) __ksym;



extern bool bpf_session_is_return(void) __ksym __weak;

#endif

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

+39 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include "trace_helpers.h"

#include "kprobe_multi_empty.skel.h"

#include "kprobe_multi_override.skel.h"

#include "kprobe_multi_session.skel.h"

#include "bpf/libbpf_internal.h"

#include "bpf/hashmap.h"
@@ -326,6 +327,42 @@ static void test_attach_api_fails(void) 
	kprobe_multi__destroy(skel);

}



static void test_session_skel_api(void)

{

	struct kprobe_multi_session *skel = NULL;

	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);

	LIBBPF_OPTS(bpf_test_run_opts, topts);

	struct bpf_link *link = NULL;

	int i, err, prog_fd;



	skel = kprobe_multi_session__open_and_load();

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

		return;



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



	err = kprobe_multi_session__attach(skel);

	if (!ASSERT_OK(err, " kprobe_multi_session__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");



	/* bpf_fentry_test1-4 trigger return probe, result is 2 */

	for (i = 0; i < 4; i++)

		ASSERT_EQ(skel->bss->kprobe_session_result[i], 2, "kprobe_session_result");



	/* bpf_fentry_test5-8 trigger only entry probe, result is 1 */

	for (i = 4; i < 8; i++)

		ASSERT_EQ(skel->bss->kprobe_session_result[i], 1, "kprobe_session_result");



cleanup:

	bpf_link__destroy(link);

	kprobe_multi_session__destroy(skel);

}



static size_t symbol_hash(long key, void *ctx __maybe_unused)

{

	return str_hash((const char *) key);
@@ -690,4 +727,6 @@ void test_kprobe_multi_test(void) 
		test_attach_api_fails();

	if (test__start_subtest("attach_override"))

		test_attach_override();

	if (test__start_subtest("session"))

		test_session_skel_api();

}

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

0 → 100644
+79 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include <stdbool.h>

#include "bpf_kfuncs.h"



#define ARRAY_SIZE(x) (int)(sizeof(x) / sizeof((x)[0]))



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



extern const void bpf_fentry_test1 __ksym;

extern const void bpf_fentry_test2 __ksym;

extern const void bpf_fentry_test3 __ksym;

extern const void bpf_fentry_test4 __ksym;

extern const void bpf_fentry_test5 __ksym;

extern const void bpf_fentry_test6 __ksym;

extern const void bpf_fentry_test7 __ksym;

extern const void bpf_fentry_test8 __ksym;



int pid = 0;



__u64 kprobe_session_result[8];



static int session_check(void *ctx)

{

	unsigned int i;

	__u64 addr;

	const void *kfuncs[] = {

		&bpf_fentry_test1,

		&bpf_fentry_test2,

		&bpf_fentry_test3,

		&bpf_fentry_test4,

		&bpf_fentry_test5,

		&bpf_fentry_test6,

		&bpf_fentry_test7,

		&bpf_fentry_test8,

	};



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

		return 1;



	addr = bpf_get_func_ip(ctx);



	for (i = 0; i < ARRAY_SIZE(kfuncs); i++) {

		if (kfuncs[i] == (void *) addr) {

			kprobe_session_result[i]++;

			break;

		}

	}



	/*

	 * Force probes for function bpf_fentry_test[5-8] not to

	 * install and execute the return probe

	 */

	if (((const void *) addr == &bpf_fentry_test5) ||

	    ((const void *) addr == &bpf_fentry_test6) ||

	    ((const void *) addr == &bpf_fentry_test7) ||

	    ((const void *) addr == &bpf_fentry_test8))

		return 1;



	return 0;

}



/*

 * 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.session/bpf_fentry_test*")

int test_kprobe(struct pt_regs *ctx)

{

	return session_check(ctx);

}