[PATCH bpf-next v2 3/3] selftests/bpf: Add selftest for attaching tracing programs to functions in deny list

[KaFai Wan <mannkafai@gmail.com>]

The reuslt:

  $ tools/testing/selftests/bpf/test_progs --name=tracing_deny
  #467/1   tracing_deny/migrate_disable:OK
  #467     tracing_deny:OK
  Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: KaFai Wan <mannkafai@gmail.com>
---
 .../selftests/bpf/prog_tests/tracing_deny.c       | 11 +++++++++++
 tools/testing/selftests/bpf/progs/tracing_deny.c  | 15 +++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/tracing_deny.c
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_deny.c

diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_deny.c b/tools/testing/selftests/bpf/prog_tests/tracing_deny.c
new file mode 100644
index 000000000000..460c59a9667f
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_deny.c
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "tracing_deny.skel.h"
+
+void test_tracing_deny(void)
+{
+	/* migrate_disable depends on CONFIG_SMP */
+	if (libbpf_find_vmlinux_btf_id("migrate_disable", BPF_TRACE_FENTRY) > 0)
+		RUN_TESTS(tracing_deny);
+}
diff --git a/tools/testing/selftests/bpf/progs/tracing_deny.c b/tools/testing/selftests/bpf/progs/tracing_deny.c
new file mode 100644
index 000000000000..98ef834f0b6d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tracing_deny.c
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("fentry/migrate_disable")
+__failure __msg("Attaching tracing programs to function 'migrate_disable' is rejected.")
+int BPF_PROG(migrate_disable)
+{
+	return 0;
+}
-- 
2.43.0