linux-kernel - Re: [PATCH v2 -tip] x86/percpu: Use C for arch_raw_cpu

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Message-ID: <20231012160801.blc2t37gfqhlah5h@treble>
Date:   Thu, 12 Oct 2023 09:08:01 -0700
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     "H. Peter Anvin" <hpa@...or.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Uros Bizjak <ubizjak@...il.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Nadav Amit <namit@...are.com>,
        Andy Lutomirski <luto@...nel.org>,
        Brian Gerst <brgerst@...il.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH v2 -tip] x86/percpu: Use C for arch_raw_cpu_ptr()

On Thu, Oct 12, 2023 at 08:19:14AM +0200, Ingo Molnar wrote:
> 
> * Josh Poimboeuf <jpoimboe@...nel.org> wrote:
> 
> > Though, another problem is that .text has a crazy amount of padding
> > which makes it always the same size, due to the SRSO alias mitigation
> > alignment linker magic.  We should fix that somehow.
> 
> We could emit a non-aligned end-of-text symbol (we might have it already),
> and have a script or small .c program in scripts/ or tools/ that looks
> at vmlinux and displays a user-friendly and accurate list of text and
> data sizes in the kernel?
> 
> And since objtool is technically an 'object files tool', and it already
> looks at sections & symbols, it could also grow a:
> 
> 	objtool size <objfile>
> 
> command that does the sane thing ... I'd definitely start using that, instead of 'size'.
> 
> /me runs :-)

Yeah, that's actually not a bad idea.

I had been thinking a "simple" script would be fine, but I'm realizing
the scope of this thing could grow over time.  In which case a script is
less than ideal.  And objtool already has the ability to do this pretty
easily.

-- 
Josh