On Fri, Jul 11, 2025 at 1:19 AM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> On Thu, Jul 10, 2025 at 9:27 AM KaFai Wan <mannkafai@xxxxxxxxx> 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@xxxxxxxxx>
> > ---
> > 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.
--
Regards
Yafang
