linux-kernel - Re: [RFC PATCH] x86: Make sure verify

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Message-ID: <EFC40C33-9525-409C-B57B-A70BC5F00C1B@zytor.com>
Date:	Wed, 02 Mar 2016 14:32:54 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	Brian Gerst <brgerst@...il.com>, X86 ML <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [RFC PATCH] x86: Make sure verify_cpu has a good stack

On March 2, 2016 2:28:42 PM PST, Borislav Petkov <bp@...en8.de> wrote:
>On Wed, Mar 02, 2016 at 02:11:51PM -0800, H. Peter Anvin wrote:
>> Not sure if we need a reference to _text here.
>
>Ah, so stack_start is in .ref.data, I guess we can add a __ref_data
>marker in vmlinux.lds.S to denote the start of the .ref.data section
>and
>use that for calculating the delta...

I'm trying to think of any reason why we couldn't simply have a symbol at the top of the initial stack?  Then a simple leaq would suffice; this is for the BSP after all.
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