linux-kernel - Re: [tip: objtool/urgent] objtool: Consolidate annotation macros

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Message-ID: <aTCF5rABohJTVCVl@gmail.com>
Date: Wed, 3 Dec 2025 19:48:06 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, linux-tip-commits@...r.kernel.org,
	Josh Poimboeuf <jpoimboe@...nel.org>, x86@...nel.org
Subject: Re: [tip: objtool/urgent] objtool: Consolidate annotation macros


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Wed, 3 Dec 2025 at 08:57, Ingo Molnar <mingo@...nel.org> wrote:
> >
> > Find below a diff of the arch/x86/kernel/process.s output
> > of your tree versus current tip:objtool/urgent.
>
> Yeah, just a single example would have been sufficient, ie a simple
>
>    Turn
>
>         911:
>                .pushsection .discard.annotate_insn,"M", @progbits, 8
>                .long 911b - .
>                .long 1
>                .popsection
>                jmp __x86_return_thunk
>
>   Into
>
>         911: .pushsection ".discard.annotate_insn", "M", @progbits, 8;
> .long 911b - .; .long 1; .popsection
>         jmp __x86_return_thunk

I ended up rebasing the commit after all and added your example,
because seeing it written out triggered further enhancements:

> and btw, the quotes around the section name are not necessary afaik.
>
> Also, I have to say that being mergeable is a bit annoying here:
> without that, we could drop the "@progbits, 8" parts too which is just
> strange noise.  Is the mergeability really a win? Because I'd assume
> that it's never *actually* merged, since the expression "911b-." ends
> up being a unique value?
>
> What am I missing? It *feels* like this should just all be
>
>         911: .pushsection .discard.annotate_insn ; .long 911b - .;
> .long 1; .popsection
>         jmp __x86_return_thunk
>
> instead. But it's entirely possible I'm not seeing the reason here...

Thanks,

	Ingo