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 S1755337AbdKBJxh (ORCPT <rfc822;w@1wt.eu>);
        Thu, 2 Nov 2017 05:53:37 -0400
Received: from mail-wm0-f67.google.com ([74.125.82.67]:44139 "EHLO
        mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1752560AbdKBJxf (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 2 Nov 2017 05:53:35 -0400
X-Google-Smtp-Source: ABhQp+SfnDXGqI0Akn3GuZAfFPBHRxoj6d6i7xcjGvQqmXEgSqoH1dqSf4DfZjdQneoIxVVEqWQlIQ==
Date: Thu, 2 Nov 2017 10:53:31 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: X86 ML <x86@kernel.org>, Borislav Petkov <bpetkov@suse.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Brian Gerst <brgerst@gmail.com>, Dave Hansen <dave.hansen@intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v2 13/20] x86/asm/64: Pass sp0 directly to load_sp0()
Message-ID: <20171102095331.is3wpxjin5islzzq@gmail.com>
References: <cover.1509609304.git.luto@kernel.org>
 <2655d8b42ed940aa384fe18ee1129bbbcf730a08.1509609304.git.luto@kernel.org>
 <20171102094813.idw77gu2rarcu4zq@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20171102094813.idw77gu2rarcu4zq@gmail.com>
User-Agent: NeoMutt/20170609 (1.8.3)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


* Ingo Molnar <mingo@kernel.org> wrote:

> 
> * Andy Lutomirski <luto@kernel.org> wrote:
> 
> > load_sp0() had an odd signature:
> > 
> > void load_sp0(struct tss_struct *tss, struct thread_struct *thread);
> > 
> > Simplify it to:
> > 
> > void load_sp0(unsigned long sp0);
> 
> I also added this to the changelog:
> 
> > Also simplify a few get_cpu()/put_cpu() sequences to
> > preempt_disable()/preempt_enable().
> 
> Plus:
> 
> > --- a/arch/x86/kernel/cpu/common.c
> > +++ b/arch/x86/kernel/cpu/common.c
> > @@ -1572,7 +1572,7 @@ void cpu_init(void)
> >  	initialize_tlbstate_and_flush();
> >  	enter_lazy_tlb(&init_mm, me);
> >  
> > -	load_sp0(t, &current->thread);
> > +	load_sp0(current->thread.sp0);
> >  	set_tss_desc(cpu, t);
> >  	load_TR_desc();
> >  	load_mm_ldt(&init_mm);
> > @@ -1627,7 +1627,7 @@ void cpu_init(void)
> >  	initialize_tlbstate_and_flush();
> >  	enter_lazy_tlb(&init_mm, curr);
> >  
> > -	load_sp0(t, thread);
> > +	load_sp0(thread->sp0);
> >  	set_tss_desc(cpu, t);
> >  	load_TR_desc();
> >  	load_mm_ldt(&init_mm);
> 
> In the 32-bit path this was the last use of 'thread', making the local variable 
> unused - I removed it.

Correction, it's patch #16 that removes the last reference:

   [PATCH v2 16/20] x86/boot/64: Stop initializing TSS.sp0 at boot

I removed the local variable there.

Thanks,

	Ingo