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

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Date:	Wed, 11 Mar 2009 11:53:33 +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


* Jaswinder Singh Rajput <jaswinder@...nel.org> wrote:

> On Tue, 2009-03-10 at 18:45 +0100, Ingo Molnar wrote:
> > Thanks - picked it up into tip:x86/debug. (Note that i 
> > rearranged the Makefile details a bit so that it does not 
> > conflict with tip:perfcounters)
> > 
> > Not yet in tip:master, because it triggers this build failure:
> > 
> > arch/x86/kernel/cpu/cpu_debug.c: In function ‘print_dt’:
> > arch/x86/kernel/cpu/cpu_debug.c:475: error: implicit declaration of function ‘store_ldt’
> > 
> 
> Here is the fix.
> 
> The following changes since commit 259ef6fcea4046fe24495b1e3631c1b905c531c1:
>   Jaswinder Singh Rajput (1):
>         x86: cpu architecture debug code
> 
> are available in the git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/jaswinder/linux-2.6-tip-cpu.git master
> 
> Jaswinder Singh Rajput (1):
>       x86: cpu_debug.c remove some dependency
> 
>  arch/x86/kernel/cpu/cpu_debug.c |    8 ++++----
>  1 files changed, 4 insertions(+), 4 deletions(-)
> 
> Complete diff:
> diff --git a/arch/x86/kernel/cpu/cpu_debug.c b/arch/x86/kernel/cpu/cpu_debug.c
> index 0bdf4da..08c365a 100755
> --- a/arch/x86/kernel/cpu/cpu_debug.c
> +++ b/arch/x86/kernel/cpu/cpu_debug.c
> @@ -464,19 +464,19 @@ static void print_dt(void *seq)
>  	unsigned long ldt;
>  
>  	/* IDT */
> -	store_idt((struct desc_ptr *)&dt);
> +	native_store_idt((struct desc_ptr *)&dt);

hm, this wont work on Xen then.

>  	print_desc_ptr("IDT", seq, dt);
>  
>  	/* GDT */
> -	store_gdt((struct desc_ptr *)&dt);
> +	native_store_gdt((struct desc_ptr *)&dt);
>  	print_desc_ptr("GDT", seq, dt);
>  
>  	/* LDT */
> -	store_ldt(ldt);
> +	asm volatile("sldt %0" : "=m" (ldt));
>  	seq_printf(seq, " LDT\t: %016lx\n", ldt);
>  
>  	/* TR */
> -	store_tr(ldt);
> +	asm volatile("str %0" : "=r" (ldt));
>  	seq_printf(seq, " TR\t: %016lx\n", ldt);

we do have a store_tr() primitive - why open code the assembly?

The real fix (if it's not just a missing include line) would be 
to make sure these primitives are generally available.

	Ingo
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