Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753953Ab3JIOPK (ORCPT ); Wed, 9 Oct 2013 10:15:10 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52898 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752198Ab3JIOPI (ORCPT ); Wed, 9 Oct 2013 10:15:08 -0400 Message-ID: <52556486.9080109@zytor.com> Date: Wed, 09 Oct 2013 07:13:26 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130923 Thunderbird/17.0.9 MIME-Version: 1.0 To: HATAYAMA Daisuke CC: Dave Anderson , Kees Cook , LKML , x86@kernel.org, kernel-hardening@lists.openwall.com, Aaron Durbin , Eric Northup , Julien Tinnes , Will Drewry , Mathias Krause , Zhang Yanfei , "Discussion list for crash utility usage, maintenance and development" Subject: Re: [PATCH 6/7] x86, kaslr: report kernel offset on panic References: <1380656245-29975-1-git-send-email-keescook@chromium.org> <524BE3C5.2070302@jp.fujitsu.com> <524CBB70.2060809@jp.fujitsu.com> <1408843968.872421.1380808038820.JavaMail.root@redhat.com> <52521566.20402@jp.fujitsu.com> <1678208981.2178058.1381152105871.JavaMail.root@redhat.com> <5253D5E4.7060004@jp.fujitsu.com> <391752872.2807845.1381239492989.JavaMail.root@redhat.com> <52552A2A.8030505@jp.fujitsu.com> In-Reply-To: <52552A2A.8030505@jp.fujitsu.com> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1283 Lines: 35 On 10/09/2013 03:04 AM, HATAYAMA Daisuke wrote: >>> >>> Sorry, I don't understand why relocation size cannot be calculated when >>> CONFIG_PHYSICALSTART > CONFIG_PHYSICAL_ALIGN. Could you explain that? >> >> I just meant that when CONFIG_PHYSICAL_START > CONFIG_PHYSICAL_ALIGN, >> the 32-bit x86 kernel >> gets relocated (like the secondary kdump kernel), but that information >> is not readily available >> from the vmlinux/vmcore pair. >> > > My understanding on CONFIG_PHYSICAL_ALIGN was that starting address of > kernel text area > is always rounded up to CONFIG_PHYSICAL_ALIGN, only. Your explanation > would be part I don't > understand well. I'll reconsider it locally... > If CONFIG_PHYSICAL_START == CONFIG_PHYSICAL_ALIGN, then it is very likely that the kernel (in the absence of kASLR) will be run at the CONFIG_PHYSICAL_START address, as the initial loading address, usually 1 MB, will be rounded up to CONFIG_PHYSICAL_ALIGN. Since CONFIG_PHYSICAL_START is the unrelocated linking address, they end up matching. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/