linux-kernel - Re: [PATCH v3 5/6] x86: alternative.h: use asm

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Message-ID: <20190913054155.GA118828@gmail.com>
Date:   Fri, 13 Sep 2019 07:41:55 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        ndesaulniers@...gle.com,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Nadav Amit <namit@...are.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH v3 5/6] x86: alternative.h: use asm_inline for all
 alternative variants


* Rasmus Villemoes <linux@...musvillemoes.dk> wrote:

> Most, if not all, uses of the alternative* family just provide one or
> two instructions in .text, but the string literal can be quite large,
> causing gcc to overestimate the size of the generated code. That in
> turn affects its decisions about inlining of the function containing
> the alternative() asm statement.
> 
> New enough versions of gcc allow one to overrule the estimated size by
> using "asm inline" instead of just "asm". So replace asm by the helper
> asm_inline, which for older gccs just expands to asm.
> 
> Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>

Acked-by: Ingo Molnar <mingo@...nel.org>

Thanks,

	Ingo