[PATCH bpf-next v3 3/4] selftests/bpf: Add selftest for attaching tracing programs to functions in deny list

[KaFai Wan]

The result:

 $ tools/testing/selftests/bpf/test_progs -t tracing_failure/tracing_deny
 #468/3   tracing_failure/tracing_deny:OK
 #468     tracing_failure:OK
 Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: KaFai Wan <kafai....@linux.dev>
---
 .../bpf/prog_tests/tracing_failure.c          | 33 +++++++++++++++++++
 .../selftests/bpf/progs/tracing_failure.c     |  6 ++++
 2 files changed, 39 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c 
b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c
index a222df765bc3..140fb0d175cf 100644
--- a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c
@@ -28,10 +28,43 @@ static void test_bpf_spin_lock(bool is_spin_lock)
        tracing_failure__destroy(skel);
 }
 
+static void test_tracing_deny(void)
+{
+       struct tracing_failure *skel;
+       char log_buf[256];
+       int btf_id, err;
+
+       /* migrate_disable depends on CONFIG_SMP */
+       btf_id = libbpf_find_vmlinux_btf_id("migrate_disable", 
BPF_TRACE_FENTRY);
+       if (btf_id <= 0) {
+               test__skip();
+               return;
+       }
+
+       skel = tracing_failure__open();
+       if (!ASSERT_OK_PTR(skel, "tracing_failure__open"))
+               return;
+
+       bpf_program__set_autoload(skel->progs.tracing_deny, true);
+       bpf_program__set_log_buf(skel->progs.tracing_deny, log_buf, 
sizeof(log_buf));
+
+       err = tracing_failure__load(skel);
+       if (!ASSERT_ERR(err, "tracing_failure__load"))
+               goto out;
+
+       ASSERT_HAS_SUBSTR(log_buf,
+                         "Attaching tracing programs to function 
'migrate_disable' is rejected.",
+                         "log_buf");
+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);
+       if (test__start_subtest("tracing_deny"))
+               test_tracing_deny();
 }
diff --git a/tools/testing/selftests/bpf/progs/tracing_failure.c 
b/tools/testing/selftests/bpf/progs/tracing_failure.c
index d41665d2ec8c..dfa152e8194e 100644
--- a/tools/testing/selftests/bpf/progs/tracing_failure.c
+++ b/tools/testing/selftests/bpf/progs/tracing_failure.c
@@ -18,3 +18,9 @@ int BPF_PROG(test_spin_unlock, struct bpf_spin_lock *lock)
 {
        return 0;
 }
+
+SEC("?fentry/migrate_disable")
+int BPF_PROG(tracing_deny)
+{
+       return 0;
+}
-- 
2.43.0