linux-kernel - Re: [RFC 1/3] x86: Add this_cpu_sp0() to read sp0 for the current cpu

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Message-ID: <20150304203958.GA7247@gmail.com>
Date:	Wed, 4 Mar 2015 21:39:58 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Borislav Petkov <bp@...en8.de>,
	Oleg Nesterov <oleg@...hat.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [RFC 1/3] x86: Add this_cpu_sp0() to read sp0 for the current cpu


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

> On Wed, Mar 4, 2015 at 12:02 AM, Ingo Molnar <mingo@...nel.org> wrote:
> >
> > * Andy Lutomirski <luto@...capital.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.

Thanks,

	Ingo
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