linux-kernel - Re: [PATCH v12 04/31] arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE

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Date:   Tue, 16 Apr 2019 16:31:27 +0200
From:   Laurent Dufour <ldufour@...ux.ibm.com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     akpm@...ux-foundation.org, mhocko@...nel.org, peterz@...radead.org,
        kirill@...temov.name, ak@...ux.intel.com, dave@...olabs.net,
        jack@...e.cz, Matthew Wilcox <willy@...radead.org>,
        aneesh.kumar@...ux.ibm.com, benh@...nel.crashing.org,
        mpe@...erman.id.au, paulus@...ba.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
        Will Deacon <will.deacon@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        sergey.senozhatsky.work@...il.com,
        Andrea Arcangeli <aarcange@...hat.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        kemi.wang@...el.com, Daniel Jordan <daniel.m.jordan@...cle.com>,
        David Rientjes <rientjes@...gle.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Ganesh Mahendran <opensource.ganesh@...il.com>,
        Minchan Kim <minchan@...nel.org>,
        Punit Agrawal <punitagrawal@...il.com>,
        vinayak menon <vinayakm.list@...il.com>,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        zhong jiang <zhongjiang@...wei.com>,
        Haiyan Song <haiyanx.song@...el.com>,
        Balbir Singh <bsingharora@...il.com>, sj38.park@...il.com,
        Michel Lespinasse <walken@...gle.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        haren@...ux.vnet.ibm.com, npiggin@...il.com,
        paulmck@...ux.vnet.ibm.com, Tim Chen <tim.c.chen@...ux.intel.com>,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: Re: [PATCH v12 04/31] arm64/mm: define
 ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT

Le 16/04/2019 à 16:27, Mark Rutland a écrit :
> On Tue, Apr 16, 2019 at 03:44:55PM +0200, Laurent Dufour wrote:
>> From: Mahendran Ganesh <opensource.ganesh@...il.com>
>>
>> Set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT for arm64. This
>> enables Speculative Page Fault handler.
>>
>> Signed-off-by: Ganesh Mahendran <opensource.ganesh@...il.com>
> 
> This is missing your S-o-B.

You're right, I missed that...

> 
> The first patch noted that the ARCH_SUPPORTS_* option was there because
> the arch code had to make an explicit call to try to handle the fault
> speculatively, but that isn't addeed until patch 30.
> 
> Why is this separate from that code?

Andrew was recommended this a long time ago for bisection purpose. This 
allows to build the code with CONFIG_SPECULATIVE_PAGE_FAULT before the 
code that trigger the spf handler is added to the per architecture's code.

Thanks,
Laurent.

> Thanks,
> Mark.
> 
>> ---
>>   arch/arm64/Kconfig | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 870ef86a64ed..8e86934d598b 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -174,6 +174,7 @@ config ARM64
>>   	select SWIOTLB
>>   	select SYSCTL_EXCEPTION_TRACE
>>   	select THREAD_INFO_IN_TASK
>> +	select ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>>   	help
>>   	  ARM 64-bit (AArch64) Linux support.
>>   
>> -- 
>> 2.21.0
>>
>