RE: A bug about system call on ARM

[Wang, Yalin]

Hi  Will,

Have you received the log files?

And is there someone looking at this issue now ?
This issue happened on Qcom Scorpoin CPUs,
And  it just happened in our stability test occasionally .

If you have some patch for this issue,
I can do the test for it .

Thanks for your help very much !

-----Original Message-----
From: Wang, Yalin 
Sent: Wednesday, May 29, 2013 5:51 PM
To: 'Will Deacon'; richard -rw- weinberger
Cc: linux-arch@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Subject: RE: A bug about system call on ARM

Hi 

This is kernel.log  and  the stack which is recovered by Trace32 tools.
Please have a look at it .

Thanks 

-----Original Message-----
From: Will Deacon [mailto:will.deacon@xxxxxxx]
Sent: Wednesday, May 29, 2013 5:48 PM
To: richard -rw- weinberger
Cc: Wang, Yalin; linux-arch@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Subject: Re: A bug about system call on ARM

Hello,

On Wed, May 29, 2013 at 09:46:42AM +0100, richard -rw- weinberger wrote:
> On Wed, May 29, 2013 at 10:24 AM, Wang, Yalin <Yalin.Wang@xxxxxxxxxxxxxx> wrote:
> > I have download the latest linux kernel code  3.9.4 And Compare with
> > 3.4.0 kernel .
> >
> > It seems there is no change for this part , So it will still happen 
> > .
> > Does anyone know who is responsible for  arm arch part kernel code ?
> 
> See MAINTAINERS file.
> CC'ing linux-arm-kernel@xxxxxxxxxxxxxxxxxxx

Cheers for adding us to CC.

> >> #ifdef CONFIG_ARM_THUMB
> >>         tst     r8, #PSR_T_BIT
> >>         movne   r10, #0                         @ no thumb OABI emulation
> >>         ldreq   r10, [lr, #-4]                  @ get SWI instruction          // crash at this instruction, when get SWI instruction

Do you have the panic log please? Also, which SoC are you using and how are you reproducing this?

> >>         ldr     r10, [lr, #-4]                  @ get SWI instruction
> >>   A710( and     ip, r10, #0x0f000000            @ check for SWI         )
> >>   A710( teq     ip, #0x0f000000                                         )
> >>   A710( bne     .Larm710bug                                             )
> >> #endif
> >> #ifdef CONFIG_CPU_ENDIAN_BE8
> >>         rev     r10, r10                        @ little endian instruction
> >> #endif
> >>
> >> /******************************************************************
> >> ***
> >> ******************************/
> >>
> >> Then reason why it will crash when get SWI instruction is maybe 
> >> This page is clear to aged by kernel, But this MMU fault happpened 
> >> in kernel, So the kernel do_page_fault function will not clear this 
> >> page to young, So that  will crash .

Sounds like we might need some USER annotations around the instruction loads, but we should also rework the code so that we re-enable interrupts first.

Will
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