From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>, Martin KaFai Lau <kafai@fb.com>,
Jiri Olsa <jolsa@kernel.org>,
dwarves@vger.kernel.org, bpf <bpf@vger.kernel.org>,
Kernel Team <kernel-team@fb.com>,
Andrii Nakryiko <andrii@kernel.org>
Subject: Re: [PATCH dwarves] btf: Generate btf for functions in the .BTF_ids section
Date: Wed, 28 Apr 2021 10:10:50 -0300 [thread overview]
Message-ID: <YIle2kdR4IniQnbN@kernel.org> (raw)
In-Reply-To: <CAEf4Bzbh7+WJ502J_MQKiHDZ_Ab-Vb_ysHO6NNuZwNfThKCAKw@mail.gmail.com>
Em Tue, Apr 27, 2021 at 01:38:51PM -0700, Andrii Nakryiko escreveu:
> On Tue, Apr 27, 2021 at 5:34 AM Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> > And tools that expect to trace a function can get that information from
> > the BTF info instead of getting some failure when trying to trace those
> > functions, right?
> I don't think it belongs in BTF, though.
My thinking was that since BTF is used when tracing, one would be
interested in knowing if some functions can't be used for that.
> Plus there are additional limitations enforced by BPF verifier that
> will prevent some functions to be attached. So just because the
> function is in BTF doesn't mean it's 100% attachable.
Well, at least we would avoid some that can't for sure be used for
tracing. But, a bit in there is precious, so probably geting a NACK from
the kernel should be a good enough capability query. :-)
Tools should just silently prune things in wildcards provided by the
user that aren't traceable, silently, and provide an error message when
the user explicitely asks for tracing a verbotten function.
- Arnaldo
next prev parent reply other threads:[~2021-04-28 13:10 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-23 21:37 [PATCH dwarves] btf: Generate btf for functions in the .BTF_ids section Martin KaFai Lau
2021-04-26 23:26 ` Andrii Nakryiko
2021-04-27 11:38 ` Jiri Olsa
2021-04-27 12:34 ` Arnaldo Carvalho de Melo
2021-04-27 12:43 ` Jiri Olsa
2021-04-27 20:38 ` Andrii Nakryiko
2021-04-28 13:10 ` Arnaldo Carvalho de Melo [this message]
2021-04-28 19:45 ` Andrii Nakryiko
2021-04-28 22:05 ` Arnaldo Carvalho de Melo
2021-05-01 0:16 ` Martin KaFai Lau
2021-05-01 22:23 ` Jiri Olsa
2021-04-27 11:42 ` Jiri Olsa
2021-04-27 18:20 ` Martin KaFai Lau
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