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 A93B6C43603 for ; Mon, 9 Dec 2019 13:33:35 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6290A20726 for ; Mon, 9 Dec 2019 13:33:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6290A20726 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 47Wkfh6gxszDqKj for ; Tue, 10 Dec 2019 00:33:32 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=ajd@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 47WkVb3vgBzDqKj for ; Tue, 10 Dec 2019 00:26:31 +1100 (AEDT) Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id xB9DMXWk068509 for ; Mon, 9 Dec 2019 08:26:28 -0500 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0a-001b2d01.pphosted.com with ESMTP id 2wskq6g2cg-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 09 Dec 2019 08:26:28 -0500 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 9 Dec 2019 13:26:23 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id xB9DQM9851642478 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 9 Dec 2019 13:26:23 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CC6F4A405E; Mon, 9 Dec 2019 13:26:22 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 83B15A4057; Mon, 9 Dec 2019 13:26:22 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 9 Dec 2019 13:26:22 +0000 (GMT) Received: from [9.81.215.63] (unknown [9.81.215.63]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id B2F12A01E4; Tue, 10 Dec 2019 00:26:19 +1100 (AEDT) Subject: Re: [PATCH] powerpc: Fix __clear_user() with KUAP enabled To: Christophe Leroy , linuxppc-dev@lists.ozlabs.org References: <20191209105946.13474-1-ajd@linux.ibm.com> <3349b5d5-c277-a868-8a27-ef168aae7daa@c-s.fr> From: Andrew Donnellan Date: Tue, 10 Dec 2019 00:26:20 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <3349b5d5-c277-a868-8a27-ef168aae7daa@c-s.fr> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19120913-4275-0000-0000-0000038D43FF X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19120913-4276-0000-0000-000038A0F152 Message-Id: <6ff56858-87f2-1ca2-64f7-044b0c730dfc@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-12-09_04:2019-12-09,2019-12-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1015 malwarescore=0 mlxlogscore=676 lowpriorityscore=0 phishscore=0 suspectscore=0 priorityscore=1501 spamscore=0 bulkscore=0 mlxscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1912090116 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: syzbot+f25ecf4b2982d8c7a640@syzkaller-ppc64.appspotmail.com, Daniel Axtens Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 9/12/19 10:50 pm, Christophe Leroy wrote: >> -extern unsigned long __clear_user(void __user *addr, unsigned long >> size); >> +extern unsigned long clear_user_asm(void __user *addr, unsigned long >> size); >>   static inline unsigned long clear_user(void __user *addr, unsigned >> long size) >>   { >> @@ -409,12 +409,17 @@ static inline unsigned long clear_user(void >> __user *addr, unsigned long size) >>       might_fault(); >>       if (likely(access_ok(addr, size))) { >>           allow_write_to_user(addr, size); >> -        ret = __clear_user(addr, size); >> +        ret = clear_user_asm(addr, size); >>           prevent_write_to_user(addr, size); >>       } > > What about changing the above by the following ? > >        if (likely(access_ok(addr, size)))        ret = > __clear_user(addr, size); > >>       return ret; >>   } >> +static inline unsigned long __clear_user(void __user *addr, unsigned >> long size) >> +{ >> +        return clear_user(addr, size); >> +} >> + > > Then > > static inline unsigned long __clear_user(void __user *addr, unsigned > long size) > { >     allow_write_to_user(addr, size); >     ret = clear_user_asm(addr, size); >     prevent_write_to_user(addr, size); > >     return ret; > } This is exactly the patch I initially wrote, I ran it past mpe privately and he suggested aliasing clear_user() -> __clear_user() instead, as there's not much point keeping a separate path around for a single user for a basically non-existent performance gain. -- Andrew Donnellan OzLabs, ADL Canberra ajd@linux.ibm.com IBM Australia Limited