Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030306AbXBTRFP (ORCPT ); Tue, 20 Feb 2007 12:05:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030310AbXBTRFO (ORCPT ); Tue, 20 Feb 2007 12:05:14 -0500 Received: from saraswathi.solana.com ([198.99.130.12]:54981 "EHLO saraswathi.solana.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030297AbXBTREo (ORCPT ); Tue, 20 Feb 2007 12:04:44 -0500 Date: Tue, 20 Feb 2007 11:56:37 -0500 From: Jeff Dike To: akpm@osdl.org Cc: "Christopher S. Aker" , Sapan Bhatia , linux-kernel@vger.kernel.org, user-mode-linux@lists.sourceforge.net Subject: [PATCH 2/3] UML - Host VDSO fix Message-ID: <20070220165637.GA6250@ccure.user-mode-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1671 Lines: 40 This fixes a problem seen by a number of people running UML on newer host kernels. init would hang with an infinite segfault loop. It turns out that the host kernel was providing a AT_SYSINFO_EHDR of 0xffffe000, which faked UML into believing that the host VDSO page could be reused. However, AT_SYSINFO pointed into the middle of the address space, and was unmapped as a result. Because UML was providing AT_SYSINFO_EHDR and AT_SYSINFO to its own processes, these would branch to nowhere when trying to use the VDSO. The fix is to also check the location of AT_SYSINFO when deciding whether to use the host's VDSO. Signed-off-by: Jeff Dike -- arch/um/os-Linux/elf_aux.c | 3 +++ 1 file changed, 3 insertions(+) Index: linux-2.6.17/arch/um/os-Linux/elf_aux.c =================================================================== --- linux-2.6.17.orig/arch/um/os-Linux/elf_aux.c 2006-06-17 21:49:35.000000000 -0400 +++ linux-2.6.17/arch/um/os-Linux/elf_aux.c 2007-02-20 10:57:52.000000000 -0500 @@ -40,6 +40,9 @@ __init void scan_elf_aux( char **envp) switch ( auxv->a_type ) { case AT_SYSINFO: __kernel_vsyscall = auxv->a_un.a_val; + /* See if the page is under TASK_SIZE */ + if (__kernel_vsyscall < (unsigned long) envp) + __kernel_vsyscall = 0; break; case AT_SYSINFO_EHDR: vsyscall_ehdr = auxv->a_un.a_val; -- Work email - jdike at linux dot intel dot com - 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/