linux-kernel - Re: [git-pull -tip V2] x86: cpu architecture debug code

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Message-ID: <20090311131321.GC1074@elte.hu>
Date:	Wed, 11 Mar 2009 14:13:21 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Jaswinder Singh Rajput <jaswinder@...nel.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>, x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [git-pull -tip V2] x86: cpu architecture debug code

* Ingo Molnar <mingo@...e.hu> wrote:

> * Jaswinder Singh Rajput <jaswinder@...nel.org> wrote:
> 
> > @@ -472,7 +473,7 @@ static void print_dt(void *seq)
> >  	print_desc_ptr("GDT", seq, dt);
> >  
> >  	/* LDT */
> > -	store_ldt(ldt);
> > +	asm volatile("sldt %0" : "=m" (ldt));
> 
> this is still wrong.

As i pointed it out before, we should not open-code an assembly 
primitive - especially since store_ldt() is available in 
arch/x86/include/asm/desc.h.

True, that primitive is not available on CONFIG_PARAVIRT, but 
that is a bug: the fix is to move the store_ldt() definition 
outside the CONFIG_PARAVIRT section in desc.h, not to hack 
around the problem by open-coding assembly code.

I.e. dont let an uncleanliness and incomplete primitive spread 
to other code. Fix the primitive and remove the uncleanliness 
that way.

	Ingo
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