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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 A6836C10F03 for ; Tue, 23 Apr 2019 15:17:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 80BCD217D9 for ; Tue, 23 Apr 2019 15:17:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728449AbfDWPRV (ORCPT ); Tue, 23 Apr 2019 11:17:21 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:57764 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727305AbfDWPRT (ORCPT ); Tue, 23 Apr 2019 11:17:19 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x3NFAFE6031169 for ; Tue, 23 Apr 2019 11:17:18 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2s23rm4n8h-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 23 Apr 2019 11:17:18 -0400 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 23 Apr 2019 16:17:16 +0100 Received: from b06cxnps3075.portsmouth.uk.ibm.com (9.149.109.195) 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, 23 Apr 2019 16:17:14 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3NFHDZC55050432 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 23 Apr 2019 15:17:13 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F09DEA404D; Tue, 23 Apr 2019 15:17:12 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7CEADA4040; Tue, 23 Apr 2019 15:17:12 +0000 (GMT) Received: from pomme.aus.stglabs.ibm.com (unknown [9.145.7.116]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 23 Apr 2019 15:17:12 +0000 (GMT) From: Laurent Dufour To: mpe@ellerman.id.au Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Thomas Gleixner Subject: [PATCH] powerpc/mm: Comment arch_unmap() Date: Tue, 23 Apr 2019 17:17:12 +0200 X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19042315-0008-0000-0000-000002DCDD42 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19042315-0009-0000-0000-000022492EC3 Message-Id: <20190423151712.79391-1-ldufour@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-23_04:,, 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=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904230102 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During a different patch review, the check in arch_munmap() was found spucious due the lake of explanation. Adding a comment to clarify the test. Suggested-by: Thomas Gleixner Cc: Michael Ellerman Signed-off-by: Laurent Dufour --- arch/powerpc/include/asm/mmu_context.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h index 6ee8195a2ffb..638f481b3c9f 100644 --- a/arch/powerpc/include/asm/mmu_context.h +++ b/arch/powerpc/include/asm/mmu_context.h @@ -240,6 +240,17 @@ static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long start, unsigned long end) { + /* + * There are 2 assumptions here: + * 1. the VDSO is one page size (guaranteed by vdso_data_store) + * 2. 'start' and 'end' are page aligned (guaranteed by the caller) + * The test is wrote in a way to handle unmap operation surrounding the + * VDSO area like: + * | VDSO | + * ^ start ^ end + * The test also covers the munmap() operation done to the exact VDSO's + * boundaries. + */ if (start <= mm->context.vdso_base && mm->context.vdso_base < end) mm->context.vdso_base = 0; } -- 2.21.0