From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754833Ab1HRCdH (ORCPT ); Wed, 17 Aug 2011 22:33:07 -0400 Received: from mail.windriver.com ([147.11.1.11]:51970 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752090Ab1HRCdD (ORCPT ); Wed, 17 Aug 2011 22:33:03 -0400 Date: Thu, 18 Aug 2011 10:32:47 +0800 From: Yong Zhang To: David Daney CC: , , Ralf Baechle Subject: Re: [PATCH] MIPS: use 32-bit wrapper for compat_sys_futex Message-ID: <20110818023247.GA3750@windriver.com> Reply-To: Yong Zhang References: <1313546094-11882-1-git-send-email-yong.zhang@windriver.com> <4E4BF7C0.80703@cavium.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: <4E4BF7C0.80703@cavium.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Originating-IP: [128.224.158.133] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 17, 2011 at 10:17:52AM -0700, David Daney wrote: > >diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S > >index 46c4763..f48b18e 100644 > >--- a/arch/mips/kernel/scall64-o32.S > >+++ b/arch/mips/kernel/scall64-o32.S > >@@ -441,7 +441,7 @@ sys_call_table: > > PTR sys_fremovexattr /* 4235 */ > > PTR sys_tkill > > PTR sys_sendfile64 > >- PTR compat_sys_futex > >+ PTR sys_32_futex > > This change is redundant, scall64-o32.S already does the right thing My first virsion(not sent out) doesn't include scall64-o32.S either. > so additional zero extending is not needed and is just extra > instructions to execute for no reason. Why I'm adding it here is for: 1)code consistent, otherwise we must move SYSCALL_DEFINE6(32_futex,...) under CONFIG_MIPS32_N32; 2)I'm afraid there may be some other way to touch the high 32-bit of a register, so touching scall64-o32.S is also for safety(due to unknown reason, fix me if I'm wrong). Thanks, Yong