linux-kernel - RE: [PATCH 20/22] x86,word-at-a-time: Remove .fixup usage

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Date:   Wed, 10 Nov 2021 10:46:42 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Peter Zijlstra' <peterz@...radead.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>
CC:     Bill Wendling <morbo@...gle.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "dvyukov@...gle.com" <dvyukov@...gle.com>,
        "seanjc@...gle.com" <seanjc@...gle.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "mbenes@...e.cz" <mbenes@...e.cz>,
        "llvm@...ts.linux.dev" <llvm@...ts.linux.dev>,
        "linux-toolchains@...r.kernel.org" <linux-toolchains@...r.kernel.org>
Subject: RE: [PATCH 20/22] x86,word-at-a-time: Remove .fixup usage

From: Peter Zijlstra
> Sent: 09 November 2021 21:08
...
> 
> GCC does the same, but I wanted to have the exception stuff be in
> .text.cold, but alas it doesn't do that. I left the attribute because of
> it's descriptive value.
> 
> >  Unless the cold attribute is helping move
> > ("shrink-wrap"?) the basic block to a whole other section
> > (.text.cold.)?
> 
> I was hoping it would do that, but it doesn't on gcc-11.

Wouldn't moving part of a function to .text.cold (or .text.unlikely)
generate the same problems with the stack backtrace code as the
.text.fixup section you are removing had??

	David

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