From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755967Ab1HRQX5 (ORCPT ); Thu, 18 Aug 2011 12:23:57 -0400 Received: from mail3.caviumnetworks.com ([12.108.191.235]:2120 "EHLO mail3.caviumnetworks.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755228Ab1HRQX4 (ORCPT ); Thu, 18 Aug 2011 12:23:56 -0400 Message-ID: <4E4D3C8D.1040707@cavium.com> Date: Thu, 18 Aug 2011 09:23:41 -0700 From: David Daney User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.15) Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10 MIME-Version: 1.0 To: Yong Zhang CC: linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, Ralf Baechle Subject: Re: [PATCH] MIPS: use 32-bit wrapper for compat_sys_futex References: <1313546094-11882-1-git-send-email-yong.zhang@windriver.com> <4E4BF7C0.80703@cavium.com> <20110818023247.GA3750@windriver.com> In-Reply-To: <20110818023247.GA3750@windriver.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 18 Aug 2011 16:23:55.0628 (UTC) FILETIME=[39C772C0:01CC5DC3] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/17/2011 07:32 PM, Yong Zhang wrote: > 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; No, you don't have to move it. Just don't call it. > 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). OK: You are mistaken. You claim you don't understand what the code does. That is really a poor justification for modifying it. David Daney