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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 5BBCCC4321D for ; Tue, 21 Aug 2018 14:25:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 181D6216C4 for ; Tue, 21 Aug 2018 14:25:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 181D6216C4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727206AbeHURps (ORCPT ); Tue, 21 Aug 2018 13:45:48 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33888 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726679AbeHURpr (ORCPT ); Tue, 21 Aug 2018 13:45:47 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w7LEItci115708 for ; Tue, 21 Aug 2018 10:25:25 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 2m0k56v4gc-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 21 Aug 2018 10:25:25 -0400 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 21 Aug 2018 15:25:23 +0100 Received: from b06cxnps4074.portsmouth.uk.ibm.com (9.149.109.196) 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) Tue, 21 Aug 2018 15:25:21 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w7LEPKhp30212132 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 21 Aug 2018 14:25:20 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C376E52051; Tue, 21 Aug 2018 17:25:20 +0100 (BST) Received: from skywalker (unknown [9.85.94.159]) by d06av21.portsmouth.uk.ibm.com (Postfix) with SMTP id E72975204E; Tue, 21 Aug 2018 17:25:18 +0100 (BST) Received: (nullmailer pid 18405 invoked by uid 1000); Tue, 21 Aug 2018 14:25:17 -0000 From: "Aneesh Kumar K.V" To: Christophe Leroy , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , aneesh.kumar@linux.vnet.ibm.com Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] powerpc/nohash: fix pte_access_permitted() In-Reply-To: <8097a1d32403ea47d076803e9070869badfe24bc.1534856426.git.christophe.leroy@c-s.fr> References: <8097a1d32403ea47d076803e9070869badfe24bc.1534856426.git.christophe.leroy@c-s.fr> Date: Tue, 21 Aug 2018 19:55:17 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 18082114-0008-0000-0000-00000264B0D9 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18082114-0009-0000-0000-000021CCEF7B Message-Id: <87eferg5ki.fsf@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-08-21_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=890 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1808210151 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christophe Leroy writes: > Commit 5769beaf180a8 ("powerpc/mm: Add proper pte access check helper > for other platforms") replaced generic pte_access_permitted() by an > arch specific one. > > The generic one is defined as > (pte_present(pte) && (!(write) || pte_write(pte))) > > The arch specific one is open coded checking that _PAGE_USER and > _PAGE_WRITE (_PAGE_RW) flags are set, but lacking to check that > _PAGE_RO and _PAGE_PRIVILEGED are unset, leading to a useless test > on targets like the 8xx which defines _PAGE_RW and _PAGE_USER as 0. > > Commit 5fa5b16be5b31 ("powerpc/mm/hugetlb: Use pte_access_permitted > for hugetlb access check") replaced some tests performed with > pte helpers by a call to pte_access_permitted(), leading to the same > issue. > > This patch rewrites powerpc/nohash pte_access_permitted() > using pte helpers. > Thanks for fixing this. I should have used the helper instead of opencoding it on nohash platforms. This is another reason why I was also suggesting we should avoid consolidating pte accessors across platforms and user accessors instead of opencoding. https://lore.kernel.org/lkml/87lgcusc6z.fsf@linux.vnet.ibm.com/T/#u Reviewed-by: Aneesh Kumar K.V > Fixes: 5769beaf180a8 ("powerpc/mm: Add proper pte access check helper for other platforms") > Fixes: 5fa5b16be5b31 ("powerpc/mm/hugetlb: Use pte_access_permitted for hugetlb access check") > Cc: stable@vger.kernel.org # v4.15+ > Signed-off-by: Christophe Leroy > --- > arch/powerpc/include/asm/nohash/pgtable.h | 9 +++------ > 1 file changed, 3 insertions(+), 6 deletions(-) > > diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h > index 2160be2e4339..b321c82b3624 100644 > --- a/arch/powerpc/include/asm/nohash/pgtable.h > +++ b/arch/powerpc/include/asm/nohash/pgtable.h > @@ -51,17 +51,14 @@ static inline int pte_present(pte_t pte) > #define pte_access_permitted pte_access_permitted > static inline bool pte_access_permitted(pte_t pte, bool write) > { > - unsigned long pteval = pte_val(pte); > /* > * A read-only access is controlled by _PAGE_USER bit. > * We have _PAGE_READ set for WRITE and EXECUTE > */ > - unsigned long need_pte_bits = _PAGE_PRESENT | _PAGE_USER; > - > - if (write) > - need_pte_bits |= _PAGE_WRITE; > + if (!pte_present(pte) || !pte_user(pte) || !pte_read(pte)) > + return false; > > - if ((pteval & need_pte_bits) != need_pte_bits) > + if (write && !pte_write(pte)) > return false; > > return true; > -- > 2.13.3