From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753809Ab2BUKCI (ORCPT ); Tue, 21 Feb 2012 05:02:08 -0500 Received: from mga05.intel.com ([192.55.52.89]:48349 "EHLO fmsmga101.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753086Ab2BUKCG (ORCPT ); Tue, 21 Feb 2012 05:02:06 -0500 Authentication-Results: mr.google.com; spf=pass (google.com: domain of matt.fleming@intel.com designates 10.68.190.8 as permitted sender) smtp.mail=matt.fleming@intel.com Subject: Re: build failure in Linus' tree with gcc 4.4.3 From: Matt Fleming To: Stephen Rothwell Cc: "H. Peter Anvin" , LKML In-Reply-To: <1329731019.3639.20.camel@mfleming-mobl1.ger.corp.intel.com> References: <20120220133936.936bff0d5817ac609a5211e0@canb.auug.org.au> <20120220142208.ab97f13b9ade345402d054fb@canb.auug.org.au> <1329731019.3639.20.camel@mfleming-mobl1.ger.corp.intel.com> Content-Type: text/plain; charset="UTF-8" Organization: Intel Corporation (UK) Ltd. - Registered No. 1134945 - Pipers Way, Swindon SN3 1RJ Date: Tue, 21 Feb 2012 10:01:57 +0000 Message-ID: <1329818517.3639.29.camel@mfleming-mobl1.ger.corp.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.32.3 (2.32.3-1.fc14) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-02-20 at 09:43 +0000, Matt Fleming wrote: > On Mon, 2012-02-20 at 14:22 +1100, Stephen Rothwell wrote: > > Which is all endian specific code that will run on the host when building > > the kernel ... > > Gah, right. I didn't think about cross-building this code. > > Thanks Stephen, I'll fix this up. Looks like the segfault is caused by an unaligned access? How does this patch look? >>From 54b2707a6a911330d8db2f4ec2fb1baa5e38acf9 Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Mon, 20 Feb 2012 17:32:42 +0000 Subject: [PATCH] x86, efi: Fix segfault caused by unaligned access We need to use memcpy() instead of directly dereferencing a pointer because memcpy() correctly handles the case where the source/destination are unaligned, which can lead to a segfault when cross-building an x86 kernel on risc architectures. Stephen Rothwell noticed this bug when he hit a segfault while cross-building an x86_64 allmodconfig kernel on PowerPC. Cc: H. Peter Anvin Reported-by: Stephen Rothwell Signed-off-by: Matt Fleming --- arch/x86/boot/tools/build.c | 26 ++++++++++++++------------ 1 files changed, 14 insertions(+), 12 deletions(-) diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c index 4e9bd6b..b4d85b5 100644 --- a/arch/x86/boot/tools/build.c +++ b/arch/x86/boot/tools/build.c @@ -200,36 +200,38 @@ int main(int argc, char ** argv) #ifdef CONFIG_EFI_STUB file_sz = sz + i + ((sys_size * 16) - sz); - pe_header = *(unsigned int *)&buf[0x3c]; + memcpy(&pe_header, &buf[0x3c], sizeof(pe_header)); /* Size of code */ - *(unsigned int *)&buf[pe_header + 0x1c] = file_sz; + memcpy(&buf[pe_header + 0x1c], &file_sz, sizeof(file_sz)); /* Size of image */ - *(unsigned int *)&buf[pe_header + 0x50] = file_sz; + memcpy(&buf[pe_header + 0x50], &file_sz, sizeof(file_sz)); #ifdef CONFIG_X86_32 /* Address of entry point */ - *(unsigned int *)&buf[pe_header + 0x28] = i; + memcpy(&buf[pe_header + 0x28], &i, sizeof(i)); /* .text size */ - *(unsigned int *)&buf[pe_header + 0xb0] = file_sz; + memcpy(&buf[pe_header + 0xb0], &file_sz, sizeof(file_sz)); /* .text size of initialised data */ - *(unsigned int *)&buf[pe_header + 0xb8] = file_sz; + memcpy(&buf[pe_header + 0xb8], &file_sz, sizeof(file_sz)); #else + /* .text size */ + memcpy(&buf[pe_header + 0xc0], &file_sz, sizeof(file_sz)); + + /* .text size of initialised data */ + memcpy(&buf[pe_header + 0xc8], &file_sz, sizeof(file_sz)); + /* * Address of entry point. startup_32 is at the beginning and * the 64-bit entry point (startup_64) is always 512 bytes * after. */ - *(unsigned int *)&buf[pe_header + 0x28] = i + 512; + file_sz = i + 512; + memcpy(&buf[pe_header + 0x28], &file_sz, sizeof(file_sz)); - /* .text size */ - *(unsigned int *)&buf[pe_header + 0xc0] = file_sz; - - /* .text size of initialised data */ - *(unsigned int *)&buf[pe_header + 0xc8] = file_sz; #endif /* CONFIG_X86_32 */ #endif /* CONFIG_EFI_STUB */ -- 1.7.4.4