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Subject: Re: [RFC PATCH] x86: Make sure verify_cpu has a good stack
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Wed, 02 Mar 2016 10:25:24 -0800
To: Borislav Petkov <bp@alien8.de>
CC: Brian Gerst <brgerst@gmail.com>, X86 ML <x86@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Tom Lendacky <thomas.lendacky@amd.com>
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On March 2, 2016 10:15:56 AM PST, Borislav Petkov <bp@alien8.de> wrote:
>On Wed, Mar 02, 2016 at 09:53:28AM -0800, H. Peter Anvin wrote:
>> Please explain why we can't use rip-relative addressing in some
>form...
>
>We *can* do almost what Brian suggested:
>
>        movq    stack_start(%rip), %rsp
>        subq    $__START_KERNEL_map, %rsp
>
>But we still have to subtract __START_KERNEL_map.

Obviously.
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