linux-kernel - Re: [git pull] x86 fixes

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Message-ID: <alpine.LFD.1.10.0807241233450.3237@nehalem.linux-foundation.org>
Date:	Thu, 24 Jul 2008 12:36:38 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Ingo Molnar <mingo@...e.hu>
cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [git pull] x86 fixes



On Thu, 24 Jul 2008, Ingo Molnar wrote:
>
> Hugh Dickins (1):
>       x86: BUILD_IRQ say .text to avoid .data.percpu
> 
> diff --git a/arch/x86/kernel/irqinit_64.c b/arch/x86/kernel/irqinit_64.c
> index 0373e88..9414125 100644
> --- a/arch/x86/kernel/irqinit_64.c
> +++ b/arch/x86/kernel/irqinit_64.c
> @@ -43,7 +43,7 @@
>  
>  #define BUILD_IRQ(nr)				\
>  	asmlinkage void IRQ_NAME(nr);		\
> -	asm("\n.p2align\n"			\
> +	asm("\n.text\n.p2align\n"		\
>  	    "IRQ" #nr "_interrupt:\n\t"		\
>  	    "push $~(" #nr ") ; "		\
>  	    "jmp common_interrupt");

I do not think this is a good idea AT ALL.

You need a ".previous" there too, otherwise any random C code that doesn't 
_happen_ to change segments will now possibly put some random variable in 
the .text segment.

And yes, dependign on just where the BUILD_IRQ() is, and what is around 
it, and what compiler version we have, this bug may or may not show. But 
it's still _wrong_.

I pulled it, will fix up by hand.

		Linus
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