From: Jiri Olsa <jolsa@redhat.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>
Subject: Re: [RFC PATCH bpf-next 1/4] bpf: Allow trampoline re-attach
Date: Mon, 5 Apr 2021 16:06:35 +0200 [thread overview]
Message-ID: <YGsZa1fT/Sbff9rB@krava> (raw)
In-Reply-To: <87blavd31f.fsf@toke.dk>
On Sat, Apr 03, 2021 at 01:24:12PM +0200, Toke Høiland-Jørgensen wrote:
> Jiri Olsa <jolsa@kernel.org> writes:
>
> > Currently we don't allow re-attaching of trampolines. Once
> > it's detached, it can't be re-attach even when the program
> > is still loaded.
> >
> > Adding the possibility to re-attach the loaded tracing
> > kernel program.
>
> Hmm, yeah, didn't really consider this case when I added the original
> disallow. But don't see why not, so (with one nit below):
>
> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
>
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > kernel/bpf/syscall.c | 25 +++++++++++++++++++------
> > kernel/bpf/trampoline.c | 2 +-
> > 2 files changed, 20 insertions(+), 7 deletions(-)
> >
> > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > index 9603de81811a..e14926b2e95a 100644
> > --- a/kernel/bpf/syscall.c
> > +++ b/kernel/bpf/syscall.c
> > @@ -2645,14 +2645,27 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog,
> > * target_btf_id using the link_create API.
> > *
> > * - if tgt_prog == NULL when this function was called using the old
> > - * raw_tracepoint_open API, and we need a target from prog->aux
> > - *
> > - * The combination of no saved target in prog->aux, and no target
> > - * specified on load is illegal, and we reject that here.
> > + * raw_tracepoint_open API, and we need a target from prog->aux
> > + *
> > + * The combination of no saved target in prog->aux, and no target
> > + * specified on is legal only for tracing programs re-attach, rest
> > + * is illegal, and we reject that here.
> > */
> > if (!prog->aux->dst_trampoline && !tgt_prog) {
> > - err = -ENOENT;
> > - goto out_unlock;
> > + /*
> > + * Allow re-attach for tracing programs, if it's currently
> > + * linked, bpf_trampoline_link_prog will fail.
> > + */
> > + if (prog->type != BPF_PROG_TYPE_TRACING) {
> > + err = -ENOENT;
> > + goto out_unlock;
> > + }
> > + if (!prog->aux->attach_btf) {
> > + err = -EINVAL;
> > + goto out_unlock;
> > + }
>
> I'm wondering about the two different return codes here. Under what
> circumstances will aux->attach_btf be NULL, and why is that not an
> ENOENT error? :)
right, that should be always there.. I'll remove it
thanks,
jirka
next prev parent reply other threads:[~2021-04-05 14:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-28 11:26 [RFC PATCH bpf-next 0/4] bpf: Tracing programs re-attach Jiri Olsa
2021-03-28 11:26 ` [RFC PATCH bpf-next 1/4] bpf: Allow trampoline re-attach Jiri Olsa
2021-03-30 1:18 ` Song Liu
2021-04-03 11:24 ` Toke Høiland-Jørgensen
2021-04-03 18:21 ` Alexei Starovoitov
2021-04-05 14:08 ` Jiri Olsa
2021-04-05 14:15 ` Toke Høiland-Jørgensen
2021-04-05 21:58 ` Jiri Olsa
2021-04-05 14:06 ` Jiri Olsa [this message]
2021-03-28 11:26 ` [RFC PATCH bpf-next 2/4] selftests/bpf: Add re-attach test to fentry_test Jiri Olsa
2021-03-30 1:23 ` Song Liu
2021-03-30 20:02 ` Jiri Olsa
2021-03-28 11:26 ` [RFC PATCH bpf-next 3/4] selftests/bpf: Add re-attach test to fexit_test Jiri Olsa
2021-03-28 11:26 ` [RFC PATCH bpf-next 4/4] selftests/bpf: Test that module can't be unloaded with attached trampoline Jiri Olsa
2021-03-30 6:12 ` Song Liu
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