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

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Message-ID: <20160302204622.GI8362@pd.tnic>
Date:	Wed, 2 Mar 2016 21:46:22 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	"H. Peter Anvin" <hpa@...or.com>
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 Wed, Mar 02, 2016 at 08:50:53PM +0100, Borislav Petkov wrote:
> But better safe than sorry.

I got this, it looks good when I'm single-stepping through it with gdb
and it boots fine in kvm. I'll run it on baremetal tomorrow:

        /*
         * Setup stack for verify_cpu(): make sure we don't clobber a valid
         * stack pointer by using temporary registers.
         */
        movq    stack_start(%rip), %rax
        movq    $__START_KERNEL_map, %rdx
        subq    %rdx, %rax
        movq    %rax, %rsp

Thanks.

-- 
Regards/Gruss,
    Boris.

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