From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1HUpdU-0005Jo-OX for user-mode-linux-devel@lists.sourceforge.net; Fri, 23 Mar 2007 12:41:20 -0700 Received: from [198.99.130.12] (helo=saraswathi.solana.com) by mail.sourceforge.net with esmtp (Exim 4.44) id 1HUpdT-00074c-8r for user-mode-linux-devel@lists.sourceforge.net; Fri, 23 Mar 2007 12:41:16 -0700 Date: Fri, 23 Mar 2007 15:37:30 -0400 From: Jeff Dike Message-ID: <20070323193730.GA9519@c2.user-mode-linux.org> Mime-Version: 1.0 Content-Disposition: inline Subject: [uml-devel] [PATCH] UML - host VDSO fix List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: user-mode-linux-devel-bounces@lists.sourceforge.net Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net To: stable@kernel.org Cc: LKML , uml-devel 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 2007-02-23 15:00:51.000000000 -0500 +++ linux-2.6.17/arch/um/os-Linux/elf_aux.c 2007-02-23 15:09:58.000000000 -0500 @@ -39,6 +39,9 @@ __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; ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel