Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v12 04/31] arm64/mm: define
 ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
To:     Mark Rutland <mark.rutland@arm.com>
Cc:     akpm@linux-foundation.org, mhocko@kernel.org, peterz@infradead.org,
        kirill@shutemov.name, ak@linux.intel.com, dave@stgolabs.net,
        jack@suse.cz, Matthew Wilcox <willy@infradead.org>,
        aneesh.kumar@linux.ibm.com, benh@kernel.crashing.org,
        mpe@ellerman.id.au, paulus@samba.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, hpa@zytor.com,
        Will Deacon <will.deacon@arm.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        sergey.senozhatsky.work@gmail.com,
        Andrea Arcangeli <aarcange@redhat.com>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        kemi.wang@intel.com, Daniel Jordan <daniel.m.jordan@oracle.com>,
        David Rientjes <rientjes@google.com>,
        Jerome Glisse <jglisse@redhat.com>,
        Ganesh Mahendran <opensource.ganesh@gmail.com>,
        Minchan Kim <minchan@kernel.org>,
        Punit Agrawal <punitagrawal@gmail.com>,
        vinayak menon <vinayakm.list@gmail.com>,
        Yang Shi <yang.shi@linux.alibaba.com>,
        zhong jiang <zhongjiang@huawei.com>,
        Haiyan Song <haiyanx.song@intel.com>,
        Balbir Singh <bsingharora@gmail.com>, sj38.park@gmail.com,
        Michel Lespinasse <walken@google.com>,
        Mike Rapoport <rppt@linux.ibm.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        haren@linux.vnet.ibm.com, npiggin@gmail.com,
        paulmck@linux.vnet.ibm.com, Tim Chen <tim.c.chen@linux.intel.com>,
        linuxppc-dev@lists.ozlabs.org, x86@kernel.org
References: <20190416134522.17540-1-ldufour@linux.ibm.com>
 <20190416134522.17540-5-ldufour@linux.ibm.com>
 <20190416142710.GA54515@lakrids.cambridge.arm.com>
From:   Laurent Dufour <ldufour@linux.ibm.com>
Date:   Tue, 16 Apr 2019 16:31:27 +0200
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0)
 Gecko/20100101 Thunderbird/60.6.1
MIME-Version: 1.0
In-Reply-To: <20190416142710.GA54515@lakrids.cambridge.arm.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Message-Id: <4ef9ff4b-2230-0644-2254-c1de22d41e6c@linux.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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@gmail.com>
>>
>> Set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT for arm64. This
>> enables Speculative Page Fault handler.
>>
>> Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.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
>>
>