From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759549AbXEQWZ5 (ORCPT ); Thu, 17 May 2007 18:25:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756766AbXEQWZu (ORCPT ); Thu, 17 May 2007 18:25:50 -0400 Received: from smtpa1.mediabeam.com ([194.25.41.13]:6221 "EHLO smtpa1.mediabeam.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755287AbXEQWZt convert rfc822-to-8bit (ORCPT ); Thu, 17 May 2007 18:25:49 -0400 X-Greylist: delayed 1124 seconds by postgrey-1.27 at vger.kernel.org; Thu, 17 May 2007 18:25:48 EDT Date: Fri, 18 May 2007 00:06:38 +0200 From: Philipp Kohlbecher To: Dave Jones , "H. Peter Anvin" Cc: Arnd Bergmann , linux-kernel@vger.kernel.org, linux-assembly@vger.kernel.org Subject: [PATCH 2.6.21.1] i386: save registers before intra-privilege syscall Message-ID: <20070517220638.GA6532@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline User-Agent: Mutt/1.5.11 Content-Transfer-Encoding: 8BIT X-mediaBEAM-MailScanner-Information: Spam-/VirusProtection V1.1 X-mediaBEAM-VirusProtection: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Philipp Kohlbecher The kernel_execve function issues a software interrupt (int 0x80) to make a system call to sys_execve. This function expects to find the stack segment and stack pointer of the function that issued the system call in the pt_regs struct. The syscall entry code that sets up this struct expects the stack segment and the stack pointer of the issuing function already on the stack. But the Intel processor saves these registers only if a stack-switch occurs, i.e. for inter-privilege interrupts and exceptions (cf. Intel Software Developer’s Manual, Vol. 3A, p. 5-17, http://www.intel.com/design/processor/manuals/253668.pdf). For an intra-privilege interrupt like the one issued in kernel_execve, these registers must be saved manually. Signed-off-by: Philipp Kohlbecher --- I am a total newbie and this is my first patch, so please be merciful... Also, please CC me, I am not on the list. --- a/arch/i386/kernel/sys_i386.c 2007-05-13 18:40:33.000000000 +0200 +++ b/arch/i386/kernel/sys_i386.c 2007-05-13 17:23:10.000000000 +0200 @@ -258,7 +258,8 @@ int kernel_execve(const char *filename, int kernel_execve(const char *filename, char *const argv[], char *const envp[]) { long __res; - asm volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx" + asm volatile ("push %%ebx ; movl %2,%%ebx ; push %%ss ; push %%esp;" + "int $0x80 ; addl $(4*2),%%esp ; pop %%ebx" : "=a" (__res) : "0" (__NR_execve),"ri" (filename),"c" (argv), "d" (envp) : "memory"); return __res;