linux-kernel - Re: [PATCH] Powerpc/Watchpoint: Restore nvgprs while returning from exception

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Date:   Thu, 6 Jun 2019 14:00:59 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     mpe@...erman.id.au
Cc:     mikey@...ling.org, benh@...nel.crashing.org, paulus@...ba.org,
        npiggin@...il.com, christophe.leroy@....fr,
        mahesh@...ux.vnet.ibm.com, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH] Powerpc/Watchpoint: Restore nvgprs while returning from
 exception



On 6/6/19 12:59 PM, Ravi Bangoria wrote:
> Powerpc hw triggers watchpoint before executing the instruction.
> To make trigger-after-execute behavior, kernel emulates the
> instruction. If the instruction is 'load something into non-
> volatile register', exception handler should restore emulated
> register state while returning back, otherwise there will be
> register state corruption. Ex, Adding a watchpoint on a list
> can corrput the list:
> 
>   # cat /proc/kallsyms | grep kthread_create_list
>   c00000000121c8b8 d kthread_create_list
> 
> Add watchpoint on kthread_create_list->next:

s/kthread_create_list->next/kthread_create_list->prev/