From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3BDB3C3A5A5 for ; Thu, 5 Sep 2019 03:56:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 158BF20820 for ; Thu, 5 Sep 2019 03:56:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730704AbfIED4y (ORCPT ); Wed, 4 Sep 2019 23:56:54 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:47416 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727544AbfIED4x (ORCPT ); Wed, 4 Sep 2019 23:56:53 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x853qFEx172050 for ; Wed, 4 Sep 2019 23:56:52 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 2utrp24u0g-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 04 Sep 2019 23:56:51 -0400 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 5 Sep 2019 04:56:50 +0100 Received: from b06avi18878370.portsmouth.uk.ibm.com (9.149.26.194) by e06smtp02.uk.ibm.com (192.168.101.132) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 5 Sep 2019 04:56:48 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x853ul1S45285656 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 5 Sep 2019 03:56:47 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 21DA811C04A; Thu, 5 Sep 2019 03:56:47 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8491F11C04C; Thu, 5 Sep 2019 03:56:45 +0000 (GMT) Received: from [9.124.31.69] (unknown [9.124.31.69]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 5 Sep 2019 03:56:45 +0000 (GMT) From: Ravi Bangoria Subject: Re: [PATCH v3 2/3] Powerpc64/Watchpoint: Don't ignore extraneous exceptions To: "Naveen N. Rao" , mpe@ellerman.id.au Cc: mikey@neuling.org, benh@kernel.crashing.org, christophe.leroy@c-s.fr, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, npiggin@gmail.com, paulus@samba.org, Ravi Bangoria References: <20190710045445.31037-1-ravi.bangoria@linux.ibm.com> <20190710045445.31037-3-ravi.bangoria@linux.ibm.com> <1567608022.j44gajn34z.naveen@linux.ibm.com> Date: Thu, 5 Sep 2019 09:26:44 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1567608022.j44gajn34z.naveen@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19090503-0008-0000-0000-000003114319 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19090503-0009-0000-0000-00004A2F9A9F Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-09-05_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=852 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1909050040 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/4/19 8:12 PM, Naveen N. Rao wrote: > Ravi Bangoria wrote: >> On Powerpc64, watchpoint match range is double-word granular. On >> a watchpoint hit, DAR is set to the first byte of overlap between >> actual access and watched range. And thus it's quite possible that >> DAR does not point inside user specified range. Ex, say user creates >> a watchpoint with address range 0x1004 to 0x1007. So hw would be >> configured to watch from 0x1000 to 0x1007. If there is a 4 byte >> access from 0x1002 to 0x1005, DAR will point to 0x1002 and thus >> interrupt handler considers it as extraneous, but it's actually not, >> because part of the access belongs to what user has asked. So, let >> kernel pass it on to user and let user decide what to do with it >> instead of silently ignoring it. The drawback is, it can generate >> false positive events. > > I think you should do the additional validation here, instead of generating false positives. You should be able to read the instruction, run it through analyse_instr(), and then use OP_IS_LOAD_STORE() and GETSIZE() to understand the access range. This can be used to then perform a better match against what the user asked for. Ok. Let me see how feasible that is. But patch 1 and 3 are independent of this and can still go in. mpe? -Ravi