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 S1753348AbbCDWNG (ORCPT <rfc822;w@1wt.eu>);
	Wed, 4 Mar 2015 17:13:06 -0500
Received: from mail-wg0-f49.google.com ([74.125.82.49]:43565 "EHLO
	mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753241AbbCDWNE (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 4 Mar 2015 17:13:04 -0500
Date: Wed, 4 Mar 2015 23:12:58 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: X86 ML <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Borislav Petkov <bp@alien8.de>, Oleg Nesterov <oleg@redhat.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC 1/3] x86: Add this_cpu_sp0() to read sp0 for the current cpu
Message-ID: <20150304221258.GA22826@gmail.com>
References: <cover.1424994489.git.luto@amacapital.net>
 <385661f737a3c430ee2fb50e1531ae002fa263a0.1424994489.git.luto@amacapital.net>
 <20150304080210.GA12265@gmail.com>
 <CALCETrXi_RFCOwLvsgP8xsJ7-bFayK5OdJ+ROrhhO9S7w6sW_A@mail.gmail.com>
 <20150304203958.GA7247@gmail.com>
 <CALCETrVkS1f-yx12u5dekHoE6xGzNZKcdwPeOzrUDEpdqRnmtw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CALCETrVkS1f-yx12u5dekHoE6xGzNZKcdwPeOzrUDEpdqRnmtw@mail.gmail.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


* Andy Lutomirski <luto@amacapital.net> wrote:

> On Wed, Mar 4, 2015 at 12:39 PM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Andy Lutomirski <luto@amacapital.net> wrote:
> >
> >> On Wed, Mar 4, 2015 at 12:02 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >> >
> >> > * Andy Lutomirski <luto@amacapital.net> wrote:
> >> >
> >> >> We currently store references to the top of the kernel stack in
> >> >> multiple places: kernel_stack (with an offset) and
> >> >> init_tss.x86_tss.sp0 (no offset).  The latter is defined by hardware
> >> >> and is a clean canonical way to find the top of the stack.  Add an
> >> >
> >> > Btw., 'per_cpu(init_tss)' is a somewhat misleading name these days, as
> >> > there's nothing 'init' about it anymore - we load it during CPU init
> >> > and then manually maintain its contents. A better name would be
> >> > 'current_tss' - referring to both the current CPU and the current
> >> > task?
> >>
> >> Hmm.  That seems a little odd to me, since we never change the TSS
> >> pointer.  It's certainly better than init_tss, though.  I'll add a
> >> followup to rename it.
> >
> > Alternatively we could use 'cpu_tss': the CPU's current TSS.
> 
> I painted my bikeshed "singleton_tss", since cpu_tss seemed 
> redundant for something that's already per cpu.  If you prefer your 
> bikeshed color, let me know.

Yeah, name it *anything* but 'singleton'!!

/me gets sick of design patterns ;-)

Thanks,

	Ingo