linux-kernel - Re: [tip:x86/asm] x86/asm/entry/64: Rename 'old_rsp' to 'rsp

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Date:	Mon, 23 Mar 2015 14:58:33 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Denys Vlasenko <dvlasenk@...hat.com>
Cc:	tglx@...utronix.de, fweisbec@...il.com, ast@...mgrid.com,
	oleg@...hat.com, luto@...capital.net, keescook@...omium.org,
	hpa@...or.com, bp@...en8.de, torvalds@...ux-foundation.org,
	rostedt@...dmis.org, linux-kernel@...r.kernel.org,
	wad@...omium.org, linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/asm] x86/asm/entry/64: Rename 'old_rsp' to 'rsp_scratch'


* Denys Vlasenko <dvlasenk@...hat.com> wrote:

> On 03/17/2015 05:43 PM, tip-bot for Ingo Molnar wrote:
> > Commit-ID:  c38e503804b0402c510f82437069f7769fa0cea9
> > Gitweb:     http://git.kernel.org/tip/c38e503804b0402c510f82437069f7769fa0cea9
> > Author:     Ingo Molnar <mingo@...nel.org>
> > AuthorDate: Tue, 17 Mar 2015 14:42:59 +0100
> > Committer:  Ingo Molnar <mingo@...nel.org>
> > CommitDate: Tue, 17 Mar 2015 16:01:42 +0100
> > 
> > x86/asm/entry/64: Rename 'old_rsp' to 'rsp_scratch'
> > 
> > Make clear that the usage of PER_CPU(old_rsp) is purely temporary,
> > by renaming it to 'rsp_scratch'.
> ...
> > @@ -657,7 +657,7 @@ common_interrupt:
> >  	ASM_CLAC
> >  	addq $-0x80,(%rsp)		/* Adjust vector to [-256,-1] range */
> >  	interrupt do_IRQ
> > -	/* 0(%rsp): old_rsp */
> > +	/* 0(%rsp): rsp_scratch */
> >  ret_from_intr:
> 
> Here the "old_rsp" word in comment did not refer to old_rsp variable.
> 
> Rather, it literally means "old %rsp register value (before we possibly
> switched to per-CPU interrupt stack)".
> 
> The stack switch is hidden in "interrupt do_IRQ" macro invocation.
> 
> I think here "old_rsp" needs to be replaced by "old rsp" or "old %rsp".

Indeed - and I applied your comment-fix patch.

Thanks,

	Ingo
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