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:[email protected]]
发送时间: 2019年10月31日 19:13
收件人: Wangshaobo (bobo) <[email protected]>
抄送: chengjian (D) <[email protected]>; Libin (Huawei) <[email protected]>; Xiexiuqi <[email protected]>; zhangyi (F) <[email protected]>
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:[email protected]]
> 发送时间: 2019年10月26日 19:20
> 收件人: Wangshaobo (bobo) <[email protected]>
> 抄送: [email protected]; [email protected]; chengjian (D)
> <[email protected]>; Xiexiuqi <[email protected]>;
> [email protected]; [email protected]; [email protected];
> Libin (Huawei) <[email protected]>; [email protected];
> [email protected]
> 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----
>>
>> 00000000: 00000000 00000000 00000000 00000000 ................
>>
>> 00000010: 00000000 00000000 00000000 00000000 ................
>>
>> 00000020: 00000000 00000000 00000000 00000000 ................
>>
>> 00000030: 00000000 00000000 00000000 00000000 ................
>>
>> 00000040: 00000000 00000000 00000000 00000000 ................
>>
>> 00000050: 00000000 00000000 00000000 00000000 ................
>>
>> 00000060: 00000000 00000000 00000000 00000000 ................
>>
>> 00000070: 00000000 00000000 00000000 00000000 ................
>>
>> 00000080: 00000000 00000000 00000000 00000000 ................
>>
>> 00000090: 00000000 00000000 00000000 00000000 ................
>>
Hi,
Le 01/11/2019 à 02:57, Wangshaobo (bobo) a écrit :
> 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.
It's not a problem ... it's a feature.
I have no idea whether the same kind of issue can happen on other
arches, sorry.
Christophe
>
> thanks very much.
>
> -----邮件原件-----
> 发件人: Christophe Leroy [mailto:[email protected]]
> 发送时间: 2019年10月31日 19:13
> 收件人: Wangshaobo (bobo) <[email protected]>
> 抄送: chengjian (D) <[email protected]>; Libin (Huawei) <[email protected]>; Xiexiuqi <[email protected]>; zhangyi (F) <[email protected]>
> 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:[email protected]]
>> 发送时间: 2019年10月26日 19:20
>> 收件人: Wangshaobo (bobo) <[email protected]>
>> 抄送: [email protected]; [email protected]; chengjian (D)
>> <[email protected]>; Xiexiuqi <[email protected]>;
>> [email protected]; [email protected]; [email protected];
>> Libin (Huawei) <[email protected]>; [email protected];
>> [email protected]
>> 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----
>>>
>>> 00000000: 00000000 00000000 00000000 00000000 ................
>>>
>>> 00000010: 00000000 00000000 00000000 00000000 ................
>>>
>>> 00000020: 00000000 00000000 00000000 00000000 ................
>>>
>>> 00000030: 00000000 00000000 00000000 00000000 ................
>>>
>>> 00000040: 00000000 00000000 00000000 00000000 ................
>>>
>>> 00000050: 00000000 00000000 00000000 00000000 ................
>>>
>>> 00000060: 00000000 00000000 00000000 00000000 ................
>>>
>>> 00000070: 00000000 00000000 00000000 00000000 ................
>>>
>>> 00000080: 00000000 00000000 00000000 00000000 ................
>>>
>>> 00000090: 00000000 00000000 00000000 00000000 ................
>>>