linux-kernel - Re: [PATCH 4/5] Powerpc/hw-breakpoint: Optimize disable path

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Message-Id: <6eb4afef-3277-a920-70d2-cadf34a05be6@linux.ibm.com>
Date:   Wed, 19 Jun 2019 11:44:50 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     Christophe Leroy <christophe.leroy@....fr>
Cc:     mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        mikey@...ling.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, npiggin@...il.com,
        naveen.n.rao@...ux.vnet.ibm.com,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH 4/5] Powerpc/hw-breakpoint: Optimize disable path



On 6/18/19 12:01 PM, Christophe Leroy wrote:
>> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
>> index f002d2ffff86..265fac9fb3a4 100644
>> --- a/arch/powerpc/kernel/process.c
>> +++ b/arch/powerpc/kernel/process.c
>> @@ -793,10 +793,22 @@ static inline int set_dabr(struct arch_hw_breakpoint *brk)
>>       return __set_dabr(dabr, dabrx);
>>   }
>>   +static int disable_dawr(void)
>> +{
>> +    if (ppc_md.set_dawr)
>> +        return ppc_md.set_dawr(0, 0);
>> +
>> +    mtspr(SPRN_DAWRX, 0);
> 
> And SPRN_DAWR ?

Setting DAWRx with 0 should be enough to disable the breakpoint.