selftests/bpf: add testcases for fsession cookie

Test session cookie for fsession. Multiple fsession BPF progs is attached
to bpf_fentry_test1() and session cookie is read and write in the
testcase.

bpf_get_func_ip() will influence the layout of the session cookies, so we
test the cookie in two case: with and without bpf_get_func_ip().

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20260124062008.8657-13-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 100 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/fsession_test.c b/tools/testing/selftests/bpf/prog_tests/fsession_test.c
index 75bb42942b67..0c4b428e1cee 100644
--- a/tools/testing/selftests/bpf/prog_tests/fsession_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/fsession_test.c
@@ -77,6 +77,38 @@ cleanup:
 	fsession_test__destroy(skel);
 }
 
+static void test_fsession_cookie(void)
+{
+	struct fsession_test *skel = NULL;
+	int err;
+
+	skel = fsession_test__open();
+	if (!ASSERT_OK_PTR(skel, "fsession_test__open"))
+		goto cleanup;
+
+	/*
+	 * The test_fsession_basic() will test the session cookie with
+	 * bpf_get_func_ip() case, so we need only check
+	 * the cookie without bpf_get_func_ip() case here
+	 */
+	bpf_program__set_autoload(skel->progs.test6, false);
+
+	err = fsession_test__load(skel);
+	if (!ASSERT_OK(err, "fsession_test__load"))
+		goto cleanup;
+
+	err = fsession_test__attach(skel);
+	if (!ASSERT_OK(err, "fsession_attach"))
+		goto cleanup;
+
+	skel->bss->test6_entry_result = 1;
+	skel->bss->test6_exit_result = 1;
+
+	check_result(skel);
+cleanup:
+	fsession_test__destroy(skel);
+}
+
 void test_fsession_test(void)
 {
 #if !defined(__x86_64__)
@@ -87,4 +119,6 @@ void test_fsession_test(void)
 		test_fsession_basic();
 	if (test__start_subtest("fsession_reattach"))
 		test_fsession_reattach();
+	if (test__start_subtest("fsession_cookie"))
+		test_fsession_cookie();
 }
diff --git a/tools/testing/selftests/bpf/progs/fsession_test.c b/tools/testing/selftests/bpf/progs/fsession_test.c
index 0e1b66b2dddc..211332bdcccb 100644
--- a/tools/testing/selftests/bpf/progs/fsession_test.c
+++ b/tools/testing/selftests/bpf/progs/fsession_test.c
@@ -95,3 +95,69 @@ int BPF_PROG(test5, struct bpf_fentry_test_t *arg, int ret)
 	return 0;
 }
 
+__u64 test6_entry_result = 0;
+__u64 test6_exit_result = 0;
+SEC("fsession/bpf_fentry_test1")
+int BPF_PROG(test6, int a)
+{
+	__u64 addr = bpf_get_func_ip(ctx);
+
+	if (bpf_session_is_return(ctx))
+		test6_exit_result = (const void *) addr == &bpf_fentry_test1;
+	else
+		test6_entry_result = (const void *) addr == &bpf_fentry_test1;
+	return 0;
+}
+
+__u64 test7_entry_ok = 0;
+__u64 test7_exit_ok = 0;
+SEC("fsession/bpf_fentry_test1")
+int BPF_PROG(test7, int a)
+{
+	volatile __u64 *cookie = bpf_session_cookie(ctx);
+
+	if (!bpf_session_is_return(ctx)) {
+		*cookie = 0xAAAABBBBCCCCDDDDull;
+		test7_entry_ok = *cookie == 0xAAAABBBBCCCCDDDDull;
+		return 0;
+	}
+
+	test7_exit_ok = *cookie == 0xAAAABBBBCCCCDDDDull;
+	return 0;
+}
+
+__u64 test8_entry_ok = 0;
+__u64 test8_exit_ok = 0;
+
+SEC("fsession/bpf_fentry_test1")
+int BPF_PROG(test8, int a)
+{
+	volatile __u64 *cookie = bpf_session_cookie(ctx);
+
+	if (!bpf_session_is_return(ctx)) {
+		*cookie = 0x1111222233334444ull;
+		test8_entry_ok = *cookie == 0x1111222233334444ull;
+		return 0;
+	}
+
+	test8_exit_ok = *cookie == 0x1111222233334444ull;
+	return 0;
+}
+
+__u64 test9_entry_result = 0;
+__u64 test9_exit_result = 0;
+
+SEC("fsession/bpf_fentry_test1")
+int BPF_PROG(test9, int a, int ret)
+{
+	__u64 *cookie = bpf_session_cookie(ctx);
+
+	if (!bpf_session_is_return(ctx)) {
+		test9_entry_result = a == 1 && ret == 0;
+		*cookie = 0x123456ULL;
+		return 0;
+	}
+
+	test9_exit_result = a == 1 && ret == 2 && *cookie == 0x123456ULL;
+	return 0;
+}