linux-kernel - Re: [PATCH v2 2/9] bpf/btf: tracing: Move finding func-proto API and getting func-param API to BTF

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Message-Id: <20230718225606.926222723cdd8c2c37294e41@kernel.org>
Date:   Tue, 18 Jul 2023 22:56:06 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     Masami Hiramatsu (Google) <mhiramat@...nel.org>
Cc:     Donglin Peng <dolinux.peng@...il.com>,
        linux-trace-kernel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Steven Rostedt <rostedt@...dmis.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>, bpf@...r.kernel.org,
        Sven Schnelle <svens@...ux.ibm.com>,
        Alexei Starovoitov <ast@...nel.org>
Subject: Re: [PATCH v2 2/9] bpf/btf: tracing: Move finding func-proto API
 and getting func-param API to BTF

On Tue, 18 Jul 2023 19:44:31 +0900
Masami Hiramatsu (Google) <mhiramat@...nel.org> wrote:

> > >  static const struct btf_param *find_btf_func_param(const char *funcname, s32 *nr,
> > >                                                    bool tracepoint)
> > >  {
> > > +       struct btf *btf = traceprobe_get_btf();
> > 
> > I found that traceprobe_get_btf() only returns the vmlinux's btf. But
> > if the function is
> > defined in a kernel module, we should get the module's btf.
> > 
> 
> Good catch! That should be a separated fix (or improvement?)
> I think it's better to use btf_get() and btf_put(), and pass btf via
> traceprobe_parse_context.

Hmm, it seems that there is no exposed API to get the module's btf.
Should I use btf_idr and btf_idr_lock directly to find the corresponding
btf? If there isn't yet, I will add it too.

Thank you,

-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>