Hi, Christophe
I am sorry that we are in some troubles for some unpredictable problems
when we replay and haven't given you a quick reply.
I also want to ask does the phenomeon(use memcpy_toio when copy
ioremap_address) only occurs in powerpc ? does any other
arch also has the same problem ? we are in persuit of asking why this
phenomenon happened. Our linux kernel version is 4.4.
thanks very much.
-邮件原件-
发件人: Christophe Leroy [mailto:christophe.le...@c-s.fr]
发送时间: 2019年10月31日 19:13
收件人: Wangshaobo (bobo)
抄送: chengjian (D) ; Libin (Huawei)
; Xiexiuqi ; zhangyi (F)
主题: Re: 答复: loop nesting in alignment exception and machine check
Hi,
Did you try ? Does it work ?
Christophe
Le 28/10/2019 à 06:57, Wangshaobo (bobo) a écrit :
> Hi,Christophe
>
> Thank you for your quick reply. I will try to use memcpy_toio() instead of
> memcpy().
>
> -邮件原件-
> 发件人: Christophe Leroy [mailto:christophe.le...@c-s.fr]
> 发送时间: 2019年10月26日 19:20
> 收件人: Wangshaobo (bobo)
> 抄送: linux-a...@vger.kernel.org; alist...@popple.id.au; chengjian (D)
> ; Xiexiuqi ;
> linux-ker...@vger.kernel.org; o...@buserror.net; pau...@samba.org;
> Libin (Huawei) ; ag...@denx.de;
> linuxppc-dev@lists.ozlabs.org
> 主题: Re: loop nesting in alignment exception and machine check
>
> Hi,
>
> Le 26/10/2019 à 09:23, Wangshaobo (bobo) a écrit :
>> Hi,
>>
>> I encountered a problem about a loop nesting occurred in
>> manufacturing the alignment exception in machine check, trigger background
>> is :
>>
>> problem:
>>
>> machine checkout or critical interrupt ->…->kbox_write[for recording
>> last words] -> memcpy(irremap_addr, src,size):_GLOBAL(memcpy)…
>>
>> when we enter memcpy,a command ‘dcbz r11,r6’ will cause a alignment
>> exception, in this situation,r11 loads the ioremap address,which
>> leads to the alignment exception,
>
> You can't use memcpy() on something else than memory.
>
> For an ioremapped area, you have to use memcpy_toio()
>
> Christophe
>
>>
>> then the command can not be process successfully,as we still in
>> machine check.at the end ,it triggers a new irq machine check in irq
>> handler function,a loop nesting begins.
>>
>> analysis:
>>
>> We have analysed a lot,but it still can not come to a reasonable
>> description,in common,the alignment triggered in machine check
>> context can still be collected into the Kbox
>>
>> after alignment exception be handled by handler function, but how
>> does the machine checkout can be triggered in the handler fucntion
>> for any causes? We print relevant registers
>>
>> as follow when first enter machine check and alignment exception
>> handler
>> function:
>>
>> MSR:0x2 MSR:0x0
>>
>> SRR1:0x2 SRR1:0x21002
>>
>> But the manual says SRR1 should be set to MSR(0x2),why
>> that happened ?
>>
>> Then a branch in handler function copy the SRR1 to
>> MSR,this enble MSR[ME] and MSR[CE],system collapses.
>>
>> Conclusion:
>>
>> 1) why the alignment exception can not be handled in
>> machine check ?
>>
>> 2) besides memcpy,any other function can cause the
>> alignment exception ?
>>
>> We still recurrent it, the line as follows:
>>
>> Cpu dead lock->watch log->trigger
>> fiq->kbox_write->memcpy->alignment exception->print last words.
>>
>> but for those problems as below,what the kbox printed is empty.
>>
>> --kbox restart:[ 10.147594]
>>
>> kbox verify fs magic fail
>>
>> kbox mem mabye destroyed, format it
>>
>> kbox: load OK
>>
>> lock-task: major[249] minor[0]
>>
>> -start show_destroyed_kbox_mem_head
>>
>> :
>>
>> 0010:
>>
>> 0020:
>>
>> 0030:
>>
>> 0040:
>>
>> 0050:
>>
>> 0060:
>>
>> 0070:
>>
>> 0080:
>>
>> 0090:
>>
