On Fri, Jul 11, 2025 at 1:19 AM Alexei Starovoitov alexei.starovoitov@gmail.com wrote:
On Thu, Jul 10, 2025 at 9:27 AM KaFai Wan mannkafai@gmail.com wrote:
Show the precise rejected function name when attaching tracing to __btf_id functions.
$ ./fentry libbpf: prog 'migrate_disable': BPF program load failed: -EINVAL libbpf: prog 'migrate_disable': -- BEGIN PROG LOAD LOG -- Attaching tracing to __btf_id function 'migrate_disable' is rejected.
Signed-off-by: KaFai Wan mannkafai@gmail.com
kernel/bpf/verifier.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 275d82fb1a1a..2779d63e1f8b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -23938,6 +23938,8 @@ 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 to __btf_id function '%s' is rejected.\n",tgt_info.tgt_name);"Attaching tracing to __btf_id" ?! What does it mean?
The term "tracing" refers to BPF_PROG_TYPE_TRACING. I believe it is useful because it helps identify which functions cannot be attached by a given BPF program type. Perhaps we should replace "tracing" with "a tracing prog" for clarity?
Drop "__btf_id" and "tracing" bits.