selftests/bpf: add session cookie testcase for fsession

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

Signed-off-by: Menglong Dong <[email protected]>

Author: image-dragon

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

@@ -2,6 +2,7 @@
 /* Copyright (c) 2025 ChinaTelecom */
 #include <test_progs.h>
 #include "fsession_test.skel.h"
+#include "fsession_cookie.skel.h"
 
 static int check_result(struct fsession_test *skel)
 {
@@ -82,6 +83,37 @@ static void test_fsession_reattach(void)
 	fsession_test__destroy(skel);
 }
 
+static void test_fsession_cookie(void)
+{
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+	struct fsession_cookie *skel = NULL;
+	int err, prog_fd;
+
+	skel = fsession_cookie__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "fsession_cookie__open_and_load"))
+		goto cleanup;
+
+	err = fsession_cookie__attach(skel);
+	if (!ASSERT_OK(err, "fsession_cookie_attach"))
+		goto cleanup;
+
+	/* Trigger target once */
+	prog_fd = bpf_program__fd(skel->progs.test1);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	if (!ASSERT_OK(err, "test_run_opts err"))
+		goto cleanup;
+	if (!ASSERT_OK(topts.retval, "test_run_opts retval"))
+		goto cleanup;
+
+	for (int i = 0; i < sizeof(*skel->bss) / sizeof(__u64); i++) {
+		if (!ASSERT_EQ(((__u64 *)skel->bss)[i], 1, "test_result"))
+			goto cleanup;
+	}
+
+cleanup:
+	fsession_cookie__destroy(skel);
+}
+
 void test_fsession_test(void)
 {
 #if !defined(__x86_64__)
@@ -92,4 +124,6 @@ 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();
 }

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

@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 ChinaTelecom */
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u64 test1_entry_ok = 0;
+__u64 test1_exit_ok = 0;
+
+SEC("fsession/bpf_fentry_test1")
+int BPF_PROG(test1, int a)
+{
+	__u64 *cookie = bpf_fsession_cookie(ctx);
+
+	if (!bpf_tracing_is_exit(ctx)) {
+		if (cookie) {
+			*cookie = 0xAAAABBBBCCCCDDDDull;
+			test1_entry_ok = *cookie == 0xAAAABBBBCCCCDDDDull;
+		}
+		return 0;
+	}
+
+	if (cookie)
+		test1_exit_ok = *cookie == 0xAAAABBBBCCCCDDDDull;
+	return 0;
+}
+
+__u64 test2_entry_ok = 0;
+__u64 test2_exit_ok = 0;
+
+SEC("fsession/bpf_fentry_test1")
+int BPF_PROG(test2, int a)
+{
+	__u64 *cookie = bpf_fsession_cookie(ctx);
+
+	if (!bpf_tracing_is_exit(ctx)) {
+		if (cookie) {
+			*cookie = 0x1111222233334444ull;
+			test2_entry_ok = *cookie == 0x1111222233334444ull;
+		}
+		return 0;
+	}
+
+	if (cookie)
+		test2_exit_ok = *cookie == 0x1111222233334444ull;
+	return 0;
+}