linux-kernel - Re: [PATCH] microblaze: nommu: Don't clobber R11 on syscalls

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Message-ID: <4B20A3E7.70806@monstr.eu>
Date:	Thu, 10 Dec 2009 08:31:51 +0100
From:	Michal Simek <monstr@...str.eu>
To:	steve@...idescorp.com
CC:	microblaze-uclinux@...e.uq.edu.au, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] microblaze: nommu: Don't clobber R11 on syscalls

Hi Steve,

steve@...idescorp.com wrote:
> The noMMU syscall trap has a bug that causes R11 to be zero on return to 
> userland. Remove the extra "save" of R11 responsible for the bug.

Can you please look if is even possible to remove that one line below?
( I mean line 212 - lwi	r11, r0, PER_CPU(KM) */
Interrupt rutine don't have it too. I am pretty sure that we can remove 
that line too.

Thanks for testing,
Michal


> 
> Signed-off-by: Steven J. Magnani <steve@...idescorp.com>
> ---
> diff -uprN a/arch/microblaze/kernel/entry-nommu.S b/arch/microblaze/kernel/entry-nommu.S
> --- a/arch/microblaze/kernel/entry-nommu.S	2009-12-09 17:05:11.000000000 -0600
> +++ b/arch/microblaze/kernel/entry-nommu.S	2009-12-09 17:07:31.000000000 -0600
> @@ -208,7 +208,6 @@ ENTRY(_user_exception)
>  	lwi	r1, r1, TS_THREAD_INFO		/* get the thread info */
>  	/* calculate kernel stack pointer */
>  	addik	r1, r1, THREAD_SIZE - PT_SIZE
> -	swi	r11, r0, PER_CPU(R11_SAVE)	/* temporarily save r11 */
>  	lwi	r11, r0, PER_CPU(KM)		/* load mode indicator */
>  2:
>  	swi	r11, r1, PT_MODE		/* store the mode */
> 


-- 
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian
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