linux-kernel - Re: A bug about system call on ARM

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Date:	Wed, 29 May 2013 10:46:42 +0200
From:	richard -rw- weinberger <richard.weinberger@...il.com>
To:	"Wang, Yalin" <Yalin.Wang@...ymobile.com>
Cc:	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: A bug about system call on ARM

On Wed, May 29, 2013 at 10:24 AM, Wang, Yalin <Yalin.Wang@...ymobile.com> wrote:
> Hi
>
> 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@...ts.infradead.org

>
> Thanks
>
>
> -----Original Message-----
> From: Wang, Yalin
> Sent: Wednesday, May 29, 2013 3:38 PM
> To: 'richard -rw- weinberger'
> Cc: linux-arch@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: RE: A bug about system call on ARM
>
> Hi  Richard,
>
> Thanks for your reply ,
> I will make a check for this .
>
>
> -----Original Message-----
> From: richard -rw- weinberger [mailto:richard.weinberger@...il.com]
> Sent: Wednesday, May 29, 2013 3:35 PM
> To: Wang, Yalin
> Cc: linux-arch@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: A bug about system call on ARM
>
> Hi!
>
> On Wed, May 29, 2013 at 8:52 AM, Wang, Yalin <Yalin.Wang@...ymobile.com> wrote:
>> Hi  all,
>>
>> I am a new comer to this mailing list , I am happy to join this
>> community .
>>
>> I have a bug reported from our android phones which is caused by  the system call .
>> It seems like kernel bugs from my view .
>
> Is this a unmodified Linux kernel from kernel.org? In other works, no (half broken) board support package from your hardware vendor?
> Did you try a more recent kernel? (At least 3.4.47).
> Maybe your problem is already known and fixed...
>
>> Crash in  file  arch\arm\kernel\ entry-common.S
>>
>> /***************************************************************/
>>
>> ENTRY(vector_swi)
>>         sub     sp, sp, #S_FRAME_SIZE
>>         stmia   sp, {r0 - r12}                  @ Calling r0 - r12
>>  ARM(   add     r8, sp, #S_PC           )
>>  ARM(   stmdb   r8, {sp, lr}^           )       @ Calling sp, lr
>>  THUMB( mov     r8, sp                  )
>>  THUMB( store_user_sp_lr r8, r10, S_SP  )       @ calling sp, lr
>>         mrs     r8, spsr                        @ called from non-FIQ mode, so ok.
>>         str     lr, [sp, #S_PC]                 @ Save calling PC
>>         str     r8, [sp, #S_PSR]                @ Save CPSR
>>         str     r0, [sp, #S_OLD_R0]             @ Save OLD_R0
>>         zero_fp
>>
>>         /*
>>          * Get the system call number.
>>          */
>>
>> #if defined(CONFIG_OABI_COMPAT)
>>
>>         /*
>>          * If we have CONFIG_OABI_COMPAT then we need to look at the swi
>>          * value to determine if it is an EABI or an old ABI call.
>>          */
>> #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
>> #else
>>         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 .
>>
>> It should poll this page to make it present or the fault should be
>> handled by fixup section , Anyway, this place should not crash by kernel .
>>
>> The kernel version I used  is  3.4.0
>> I have add the kernel log and the call stack recovered  by trace32
>> tools Pls have a look at it .
>>
>>
>> Thanks .
>>
>>
>>
>> Sony Mobile Communications
>> Tel: +86 10 5966 9819
>> Phone: 18610323092
>> Address: No.16 Guangshun South Street, Chaoyang, Beijing, P.R.C.
>>
>> sonymobile.com
>>
>>
>>
>
>
>
> --
> Thanks,
> //richard
> --
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--
Thanks,
//richard
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