From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752988AbbCKPUB (ORCPT <rfc822;w@1wt.eu>);
	Wed, 11 Mar 2015 11:20:01 -0400
Received: from mx1.redhat.com ([209.132.183.28]:52770 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751186AbbCKPUA (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Wed, 11 Mar 2015 11:20:00 -0400
Message-ID: <55005D05.6010606@redhat.com>
Date: Wed, 11 Mar 2015 16:19:33 +0100
From: Denys Vlasenko <dvlasenk@redhat.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0
MIME-Version: 1.0
To: Borislav Petkov <bp@alien8.de>
CC: Ingo Molnar <mingo@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>, "H. Peter Anvin" <hpa@zytor.com>,
        Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4] x86: entry_64.S: remove unused thread_struct::usersp
References: <1425984307-2143-1-git-send-email-dvlasenk@redhat.com> <1425984307-2143-2-git-send-email-dvlasenk@redhat.com> <20150311125552.GA3359@pd.tnic>
In-Reply-To: <20150311125552.GA3359@pd.tnic>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 03/11/2015 01:55 PM, Borislav Petkov wrote:
> On Tue, Mar 10, 2015 at 11:45:07AM +0100, Denys Vlasenko wrote:
>> @@ -894,11 +893,6 @@ extern unsigned long thread_saved_pc(struct task_struct *tsk);
>>  #define task_pt_regs(tsk)	((struct pt_regs *)(tsk)->thread.sp0 - 1)
>>  extern unsigned long KSTK_ESP(struct task_struct *task);
>>  
>> -/*
>> - * User space RSP while inside the SYSCALL fast path
>> - */
>> -DECLARE_PER_CPU(unsigned long, old_rsp);
> 
> Please grep the whole arch/x86/ tree for old_rsp as there are more
> leftovers.

I think I did:

$ grep -r old_rsp arch/x86
arch/x86/xen/xen-asm_64.S:	movq %rsp, PER_CPU_VAR(old_rsp)
arch/x86/xen/xen-asm_64.S:	pushq PER_CPU_VAR(old_rsp)
arch/x86/xen/xen-asm_64.S:	movq %rsp, PER_CPU_VAR(old_rsp)
arch/x86/xen/xen-asm_64.S:	pushq PER_CPU_VAR(old_rsp)
arch/x86/kernel/process_64.c:__visible DEFINE_PER_CPU(unsigned long, old_rsp);
arch/x86/kernel/entry_64.S:	movq	%rsp,PER_CPU_VAR(old_rsp)
arch/x86/kernel/entry_64.S:	movq	PER_CPU_VAR(old_rsp),%rcx
arch/x86/kernel/entry_64.S:	/* 0(%rsp): old_rsp */

The only remaining use in C code is the definition in process_64.c
It is necessary for assembly (.S) files.