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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Ivan Babrou <ivan@cloudflare.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH 2/2] x86/unwind/orc: Silence warnings caused by missing ORC data
Date: Wed, 24 Feb 2021 09:18:05 -0600	[thread overview]
Message-ID: <20210224151805.zrujocamlb5pxf7m@treble> (raw)
In-Reply-To: <YDZoEehURLLI/lWq@hirez.programming.kicks-ass.net>

On Wed, Feb 24, 2021 at 03:52:01PM +0100, Peter Zijlstra wrote:
> On Fri, Feb 05, 2021 at 08:24:03AM -0600, Josh Poimboeuf wrote:
> > The ORC unwinder attempts to fall back to frame pointers when ORC data
> > is missing for a given instruction.  It sets state->error, but then
> > tries to keep going as a best-effort type of thing.  That may result in
> > further warnings if the unwinder gets lost.
> > 
> > Until we have some way to register generated code with the unwinder,
> > missing ORC will be expected, and occasionally going off the rails will
> > also be expected.  So don't warn about it.
> 
> I recently ran into another variant of missing ORC data, some files are
> simply not processed by objtool, eg. arch/x86/realmode/init.c. Would it
> make sense to have the vmlinux pass (when it isn't used to generate orc
> in the first place) also check that all code it finds has ORC data?
> 
> It's not fool proof, but it should help find files we're missing for
> some raisin.

Doesn't validate_reachable_instructions() basically already do that?

-- 
Josh


  reply	other threads:[~2021-02-24 16:02 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-05 14:24 [PATCH 0/2] x86/unwind/orc: Handle missing ORC data better Josh Poimboeuf
2021-02-05 14:24 ` [PATCH 1/2] x86/unwind/orc: Disable KASAN checking in the ORC unwinder, part 2 Josh Poimboeuf
2021-02-05 14:51   ` Steven Rostedt
2021-02-05 18:27   ` Ivan Babrou
2021-03-04  8:51   ` [tip: x86/urgent] " tip-bot2 for Josh Poimboeuf
2021-03-06 10:44   ` tip-bot2 for Josh Poimboeuf
2021-03-06 12:18   ` tip-bot2 for Josh Poimboeuf
2021-02-05 14:24 ` [PATCH 2/2] x86/unwind/orc: Silence warnings caused by missing ORC data Josh Poimboeuf
2021-02-08 19:56   ` Josh Poimboeuf
2021-02-08 20:00     ` Ivan Babrou
2021-02-24 14:52   ` Peter Zijlstra
2021-02-24 15:18     ` Josh Poimboeuf [this message]
2021-02-24 18:07       ` Peter Zijlstra
2021-02-24 18:12         ` Josh Poimboeuf
2021-03-04  8:51   ` [tip: x86/urgent] " tip-bot2 for Josh Poimboeuf
2021-03-06 10:44   ` tip-bot2 for Josh Poimboeuf
2021-03-06 12:18   ` tip-bot2 for Josh Poimboeuf
2021-02-24 12:02 ` [PATCH 0/2] x86/unwind/orc: Handle missing ORC data better Miroslav Benes

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