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From: Ingo Molnar <mingo@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Networking <netdev@vger.kernel.org>, 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>,
	Peter Zijlstra <peterz@infradead.org>,
	x86@kernel.org
Subject: Re: [PATCH v2] ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid adding weak function
Date: Fri, 27 May 2022 12:04:14 +0200	[thread overview]
Message-ID: <YpCiHlBjj99hALbV@gmail.com> (raw)
In-Reply-To: <20220526091106.1eb2287a@gandalf.local.home>


* Steven Rostedt <rostedt@goodmis.org> wrote:

> On Thu, 26 May 2022 04:50:17 +0200
> Ingo Molnar <mingo@kernel.org> wrote:
> 
> 
> > > The real fix would be to fix kallsyms to not show address of weak
> > > functions as the function before it. But that would require adding code in
> > > the build to add function size to kallsyms so that it can know when the
> > > function ends instead of just using the start of the next known symbol.  
> > 
> > Yeah, so I actually have a (prototype...) objtool based kallsyms 
> > implementation in the (way too large) fast-headers tree that is both faster 
> > & allows such details in principle:
> 
> Nice.
> 
> Will this work for other architectures too?

For those which implement objtool, it certainly should: as we parse through 
each object file during the build, generating kallsyms data structures is 
relatively straightforward.

Objtool availability is a big gating condition though. :-/

[ ... and still Acked-by on -v4 too. ]

Thanks,

	Ingo

  reply	other threads:[~2022-05-27 10:04 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-25 22:05 [PATCH v2] ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid adding weak function Steven Rostedt
2022-05-26  2:50 ` Ingo Molnar
2022-05-26 13:11   ` Steven Rostedt
2022-05-27 10:04     ` Ingo Molnar [this message]
2022-05-27 20:36       ` Steven Rostedt
2022-05-26  7:39 ` Peter Zijlstra
2022-05-26 13:14   ` Steven Rostedt

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