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SubjectRe: 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@sonymobile.com> 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@lists.infradead.org

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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