From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755989Ab1GJQrP (ORCPT ); Sun, 10 Jul 2011 12:47:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:4370 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753689Ab1GJQrO (ORCPT ); Sun, 10 Jul 2011 12:47:14 -0400 Date: Sun, 10 Jul 2011 18:44:24 +0200 From: Oleg Nesterov To: Andrew Morton Cc: "H. Peter Anvin" , Ingo Molnar , linux-kernel@vger.kernel.org Subject: [PATCH] x86: kill handle_signal()->set_fs() Message-ID: <20110710164424.GA20261@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org handle_signal()->set_fs() has a nice comment which explains what set_fs() is, but it doesn't explain why it is needed and why it depends on CONFIG_X86_64. Afaics, the history of this confusion is: 1. I guess today nobody can explain why it was needed in arch/i386/kernel/signal.c, perhaps it was always wrong. This predates 2.4.0 kernel. 2. then it was copy-and-past'ed to the new x86_64 arch. 3. then it was removed from i386 (but not from x86_64) by b93b6ca3 "i386: remove unnecessary code". 4. then it was reintroduced under CONFIG_X86_64 when x86 unified i386 and x86_64, because the patch above didn't touch x86_64. Remove it. ->addr_limit should be correct. Even if it was possible that it is wrong, it is too late to fix it after setup_rt_frame(). Signed-off-by: Oleg Nesterov --- arch/x86/kernel/signal.c | 9 --------- 1 file changed, 9 deletions(-) --- ptrace/arch/x86/kernel/signal.c~1_kill_set_fs 2011-05-22 16:27:28.000000000 +0200 +++ ptrace/arch/x86/kernel/signal.c 2011-07-10 18:06:30.000000000 +0200 @@ -717,15 +717,6 @@ handle_signal(unsigned long sig, siginfo if (ret) return ret; -#ifdef CONFIG_X86_64 - /* - * This has nothing to do with segment registers, - * despite the name. This magic affects uaccess.h - * macros' behavior. Reset it to the normal setting. - */ - set_fs(USER_DS); -#endif - /* * Clear the direction flag as per the ABI for function entry. */