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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 72995C433E0 for ; Thu, 16 Jul 2020 21:09:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F67E207E8 for ; Thu, 16 Jul 2020 21:09:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726858AbgGPVJd (ORCPT ); Thu, 16 Jul 2020 17:09:33 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:14260 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725959AbgGPVJc (ORCPT ); Thu, 16 Jul 2020 17:09:32 -0400 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 06GL3Xv8109986; Thu, 16 Jul 2020 17:09:24 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 32aurams6v-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 16 Jul 2020 17:09:24 -0400 Received: from m0098399.ppops.net (m0098399.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 06GL3cfW110485; Thu, 16 Jul 2020 17:09:24 -0400 Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 32aurams6a-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 16 Jul 2020 17:09:24 -0400 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 06GKpmvU028550; Thu, 16 Jul 2020 21:09:21 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma03ams.nl.ibm.com with ESMTP id 327527x097-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 16 Jul 2020 21:09:21 +0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 06GL9Isq47645114 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 16 Jul 2020 21:09:18 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B9B8EAE045; Thu, 16 Jul 2020 21:09:18 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8D321AE04D; Thu, 16 Jul 2020 21:09:15 +0000 (GMT) Received: from [9.102.2.181] (unknown [9.102.2.181]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 16 Jul 2020 21:09:15 +0000 (GMT) From: Hari Bathini Subject: Re: [PATCH v3 04/12] ppc64/kexec_file: avoid stomping memory used by special regions To: Thiago Jung Bauermann Cc: Pingfan Liu , Nayna Jain , Kexec-ml , Mahesh J Salgaonkar , Mimi Zohar , lkml , linuxppc-dev , Sourabh Jain , Petr Tesarik , Andrew Morton , Dave Young , Vivek Goyal , Eric Biederman References: <159466074408.24747.10036072269371204890.stgit@hbathini.in.ibm.com> <159466088775.24747.1248185448154277951.stgit@hbathini.in.ibm.com> <87365t8pse.fsf@morokweng.localdomain> Message-ID: <0582476e-415e-3f60-2bb2-6199d0340156@linux.ibm.com> Date: Fri, 17 Jul 2020 02:39:14 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <87365t8pse.fsf@morokweng.localdomain> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-07-16_11:2020-07-16,2020-07-16 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_spam_definite policy=outbound score=100 mlxscore=100 adultscore=0 mlxlogscore=-1000 suspectscore=0 clxscore=1015 bulkscore=0 spamscore=100 phishscore=0 malwarescore=0 impostorscore=0 priorityscore=1501 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007160139 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/07/20 8:09 am, Thiago Jung Bauermann wrote: > > Hari Bathini writes: > >> +/** >> + * __locate_mem_hole_top_down - Looks top down for a large enough memory hole >> + * in the memory regions between buf_min & buf_max >> + * for the buffer. If found, sets kbuf->mem. >> + * @kbuf: Buffer contents and memory parameters. >> + * @buf_min: Minimum address for the buffer. >> + * @buf_max: Maximum address for the buffer. >> + * >> + * Returns 0 on success, negative errno on error. >> + */ >> +static int __locate_mem_hole_top_down(struct kexec_buf *kbuf, >> + u64 buf_min, u64 buf_max) >> +{ >> + int ret = -EADDRNOTAVAIL; >> + phys_addr_t start, end; >> + u64 i; >> + >> + for_each_mem_range_rev(i, &memblock.memory, NULL, NUMA_NO_NODE, >> + MEMBLOCK_NONE, &start, &end, NULL) { >> + if (start > buf_max) >> + continue; >> + >> + /* Memory hole not found */ >> + if (end < buf_min) >> + break; >> + >> + /* Adjust memory region based on the given range */ >> + if (start < buf_min) >> + start = buf_min; >> + if (end > buf_max) >> + end = buf_max; >> + >> + start = ALIGN(start, kbuf->buf_align); >> + if (start < end && (end - start + 1) >= kbuf->memsz) { > > This is why I dislike using start and end to express address ranges: > > While struct resource seems to use the [address, end] convention, my struct crash_mem also uses [address, end] convention. This off-by-one error did not cause any issues as the hole start and size we try to find are at least page aligned. Nonetheless, I think fixing 'end' early in the loop with "end -= 1" would ensure correctness while continuing to use the same convention for structs crash_mem & resource. Thanks Hari