Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <CAADnVQ+hLnyztCi9aqpptjQk-P+ByAkyj2pjbdD45dsXwpZ0bw@mail.gmail.com>
 <20220722120854.3cc6ec4b@gandalf.local.home> <20220722122548.2db543ca@gandalf.local.home>
 <YtsRD1Po3qJy3w3t@krava> <20220722174120.688768a3@gandalf.local.home>
 <YtxqjxJVbw3RD4jt@krava> <YvbDlwJCTDWQ9uJj@krava> <20220813150252.5aa63650@rorschach.local.home>
 <YvkTLziHX4BINnla@krava> <77477710-c383-73b1-4f78-fe65a81c09b7@huawei.com> <Yvn+En35XDqKWptm@krava>
In-Reply-To: <Yvn+En35XDqKWptm@krava>
From:   =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>
Date:   Mon, 15 Aug 2022 13:01:06 +0200
Message-ID: <CAJ+HfNjLbsDuE4EB_1jwSOnyaUdjejMZJP6U=zcKvZd=iwhhDQ@mail.gmail.com>
Subject: Re: [RFC] ftrace: Add support to keep some functions out of ftrace
To:     Jiri Olsa <olsajiri@gmail.com>
Cc:     Chen Zhongjin <chenzhongjin@huawei.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Ingo Molnar <mingo@redhat.com>, bpf <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>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Mon, 15 Aug 2022 at 10:04, Jiri Olsa <olsajiri@gmail.com> wrote:
[...]
> > > >
> > > > Today, objtool has also got involved, and added an "--mcount" optio=
n
> > > > that will create the section too.
> > > I overlooked that objtool is involved as well,
> > > will check on that
> >
> > objtool --mcount option only involves mcount_loc generation (see
> > annotate_call_site) and other validation check call destination directl=
y
> > (see is_fentry_call).
> >
> > Some simply removing --mcount option dose work for this.
> >
> >
> > Another question, it seems we can export and use DEFINE_BPF_DISPATCHER =
out
> > of kernel, does that means we should add NO_MCOUNT_FILES for these sing=
le
> > uages as well?
>
> yes, cc-ing Bj=C3=B6rn to make sure it's valid use case for dispatcher
>

Hmm, could you expand a bit on how this would work?