Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751094AbdFTGrj (ORCPT ); Tue, 20 Jun 2017 02:47:39 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:55945 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750994AbdFTGri (ORCPT ); Tue, 20 Jun 2017 02:47:38 -0400 Subject: Re: [RFC v2 10/12] powerpc: Read AMR only if pkey-violation caused the exception. To: Ram Pai , Michael Ellerman References: <1497671564-20030-1-git-send-email-linuxram@us.ibm.com> <1497671564-20030-11-git-send-email-linuxram@us.ibm.com> <87bmpkuti2.fsf@concordia.ellerman.id.au> <20170619175919.GD5845@ram.oc3035372033.ibm.com> Cc: linux-kernel@vger.kernel.org, dave.hansen@intel.com, paulus@samba.org, aneesh.kumar@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org From: Anshuman Khandual Date: Tue, 20 Jun 2017 12:16:40 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <20170619175919.GD5845@ram.oc3035372033.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable x-cbid: 17062006-0012-0000-0000-00000249C4CC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17062006-0013-0000-0000-00000762480D Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-06-20_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1706200123 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1242 Lines: 32 On 06/19/2017 11:29 PM, Ram Pai wrote: > On Mon, Jun 19, 2017 at 09:06:13PM +1000, Michael Ellerman wrote: >> Ram Pai writes: >> >>> Signed-off-by: Ram Pai >>> --- >>> arch/powerpc/kernel/exceptions-64s.S | 16 ++++++++++------ >>> 1 file changed, 10 insertions(+), 6 deletions(-) >>> >>> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S >>> index 8db9ef8..a4de1b4 100644 >>> --- a/arch/powerpc/kernel/exceptions-64s.S >>> +++ b/arch/powerpc/kernel/exceptions-64s.S >>> @@ -493,13 +493,15 @@ EXC_COMMON_BEGIN(data_access_common) >>> ld r12,_MSR(r1) >>> ld r3,PACA_EXGEN+EX_DAR(r13) >>> lwz r4,PACA_EXGEN+EX_DSISR(r13) >>> + std r3,_DAR(r1) >>> + std r4,_DSISR(r1) >>> #ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS >>> + andis. r0,r4,DSISR_KEYFAULT@h /* save AMR only if its a key fault */ >>> + beq+ 1f >> >> This seems to be incremental on top of one of your other patches. >> >> But I don't see why, can you please just squash this into whatever patch >> adds this code in the first place. > > It was an optimization added later. But yes it can be squashed into an > earlier patch. Could you please explain what is the optimization this achieves ?