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Date: Tue, 17 Mar 2015 18:57:51 +0100
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Subject: Re: [tip:x86/asm] x86/asm/entry/64: Rename 'old_rsp' to 'rsp_scratch'
References: <tip-c38e503804b0402c510f82437069f7769fa0cea9@git.kernel.org>
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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@kernel.org>
> AuthorDate: Tue, 17 Mar 2015 14:42:59 +0100
> Committer:  Ingo Molnar <mingo@kernel.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".