selftests/bpf: Ensure fentry prog cannot attach to bpf_spin_{lock,unl…

…cok}()

Add two tests to ensure fentry programs cannot attach to
bpf_spin_{lock,unlock}() helpers. The tracing_failure.c files
can be used in the future for other tracing failure cases.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240207070107.335341-1-yonghong.song@linux.dev

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

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
+#include <test_progs.h>
+#include "tracing_failure.skel.h"
+
+static void test_bpf_spin_lock(bool is_spin_lock)
+{
+	struct tracing_failure *skel;
+	int err;
+
+	skel = tracing_failure__open();
+	if (!ASSERT_OK_PTR(skel, "tracing_failure__open"))
+		return;
+
+	if (is_spin_lock)
+		bpf_program__set_autoload(skel->progs.test_spin_lock, true);
+	else
+		bpf_program__set_autoload(skel->progs.test_spin_unlock, true);
+
+	err = tracing_failure__load(skel);
+	if (!ASSERT_OK(err, "tracing_failure__load"))
+		goto out;
+
+	err = tracing_failure__attach(skel);
+	ASSERT_ERR(err, "tracing_failure__attach");
+
+out:
+	tracing_failure__destroy(skel);
+}
+
+void test_tracing_failure(void)
+{
+	if (test__start_subtest("bpf_spin_lock"))
+		test_bpf_spin_lock(true);
+	if (test__start_subtest("bpf_spin_unlock"))
+		test_bpf_spin_lock(false);
+}

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

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("?fentry/bpf_spin_lock")
+int BPF_PROG(test_spin_lock, struct bpf_spin_lock *lock)
+{
+	return 0;
+}
+
+SEC("?fentry/bpf_spin_unlock")
+int BPF_PROG(test_spin_unlock, struct bpf_spin_lock *lock)
+{
+	return 0;
+}