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.leroy@xxxxxx] 发送时间: 2019年10月31日 19:13 收件人: Wangshaobo (bobo) <bobo.shaobowang@xxxxxxxxxx> 抄送: chengjian (D) <cj.chengjian@xxxxxxxxxx>; Libin (Huawei) <huawei.libin@xxxxxxxxxx>; Xiexiuqi <xiexiuqi@xxxxxxxxxx>; zhangyi (F) <yi.zhang@xxxxxxxxxx> 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.leroy@xxxxxx] > 发送时间: 2019年10月26日 19:20 > 收件人: Wangshaobo (bobo) <bobo.shaobowang@xxxxxxxxxx> > 抄送: linux-arch@xxxxxxxxxxxxxxx; alistair@xxxxxxxxxxxx; chengjian (D) > <cj.chengjian@xxxxxxxxxx>; Xiexiuqi <xiexiuqi@xxxxxxxxxx>; > linux-kernel@xxxxxxxxxxxxxxx; oss@xxxxxxxxxxxx; paulus@xxxxxxxxx; > Libin (Huawei) <huawei.libin@xxxxxxxxxx>; agust@xxxxxxx; > linuxppc-dev@xxxxxxxxxxxxxxxx > 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 ................ >>
