Re: [PATCH 2/2] x86/unwind/orc: Silence warnings caused by missing ORC data
From: Josh Poimboeuf
Date: Wed Feb 24 2021 - 11:02:47 EST
On Wed, Feb 24, 2021 at 03:52:01PM +0100, Peter Zijlstra wrote:
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On Fri, Feb 05, 2021 at 08:24:03AM -0600, Josh Poimboeuf wrote:
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> The ORC unwinder attempts to fall back to frame pointers when ORC data
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> is missing for a given instruction. It sets state->error, but then
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> tries to keep going as a best-effort type of thing. That may result in
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> further warnings if the unwinder gets lost.
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>
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> Until we have some way to register generated code with the unwinder,
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> missing ORC will be expected, and occasionally going off the rails will
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> also be expected. So don't warn about it.
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I recently ran into another variant of missing ORC data, some files are
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simply not processed by objtool, eg. arch/x86/realmode/init.c. Would it
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make sense to have the vmlinux pass (when it isn't used to generate orc
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in the first place) also check that all code it finds has ORC data?
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It's not fool proof, but it should help find files we're missing for
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some raisin.
Doesn't validate_reachable_instructions() basically already do that?
--
Josh