Show the rejected function name when attaching tracing programs to functions in deny list.
With this change, we know why tracing programs can't attach to functions like __rcu_read_lock() from log.
$ ./fentry libbpf: prog '__rcu_read_lock': BPF program load failed: -EINVAL libbpf: prog '__rcu_read_lock': -- BEGIN PROG LOAD LOG -- Attaching tracing programs to function '__rcu_read_lock' is rejected.
Suggested-by: Leon Hwang leon.hwang@linux.dev Signed-off-by: KaFai Wan kafai.wan@linux.dev Acked-by: Yafang Shao laoar.shao@gmail.com Acked-by: Yonghong Song yonghong.song@linux.dev --- kernel/bpf/verifier.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 00d287814f12..c24c0d57e595 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -23942,6 +23942,8 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) return ret; } else if (prog->type == BPF_PROG_TYPE_TRACING && btf_id_set_contains(&btf_id_deny, btf_id)) { + verbose(env, "Attaching tracing programs to function '%s' is rejected.\n", + tgt_info.tgt_name); return -EINVAL; } else if ((prog->expected_attach_type == BPF_TRACE_FEXIT || prog->expected_attach_type == BPF_MODIFY_RETURN) &&