A bug about system call on ARM

[Wang, Yalin]

Hi  Will,

I have a question about this patch .

If the user space is thumb mode,
The PC should be rewind by 2 bytes,
So the fix_up code should be 

Sub lr, lr, #2 .


Am I right ?


Thanks for your help .

-----Original Message-----
From: Wang, Yalin 
Sent: Friday, May 31, 2013 7:31 PM
To: 'Will Deacon'
Cc: 'richard -rw- weinberger'; 'linux-arch at vger.kernel.org'; 'linux-kernel at vger.kernel.org'; 'linux-arm-kernel at lists.infradead.org'
Subject: RE: A bug about system call on ARM

Hi Will,

I see,
I will make one more test .

Thanks for your clarification .

-----Original Message-----
From: Will Deacon [mailto:will.deacon at arm.com] 
Sent: Friday, May 31, 2013 7:13 PM
To: Wang, Yalin
Cc: 'richard -rw- weinberger'; 'linux-arch at vger.kernel.org'; 'linux-kernel at vger.kernel.org'; 'linux-arm-kernel at lists.infradead.org'
Subject: Re: A bug about system call on ARM

On Fri, May 31, 2013 at 12:02:49PM +0100, Wang, Yalin wrote:
> Hi  Will,
> 
> I have merge your code ,
> But there is a different ,
> 
> +	
> +	ct_user_exit

I thought you didn't have ct_user_exit? In which case, just delete this line.

> +#ifdef CONFIG_ALIGNMENT_TRAP
> +	ldr	ip, __cr_alignment
> +	ldr	ip, [ip]
> +	mcr	p15, 0, ip, c1, c0		@ update control register
> +#endif
> 
> +	enable_irq
> +	get_thread_info tsk

Hard to tell without context. You can take a look at my git tree if you like (I fixed it up based on Nico's comment):

  https://git.kernel.org/cgit/linux/kernel/git/will/linux.git/commit/?h=misc-patches

Will