linux-kernel - Re: [PATCH] NX protection for kernel data : fix 32 bits S3 suspend

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Message-ID: <4D4F2F92.9080902@zytor.com>
Date:	Sun, 06 Feb 2011 15:32:34 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	7eggert@...fuerspam.de
CC:	Bodo Eggert 
	<arcoristkaputtundbrauchtdiesentext.7eggert@...fuerspam.de>,
	Ingo Molnar <mingo@...e.hu>, castet.matthieu@...e.fr,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	linux-security-module@...r.kernel.org,
	Matthias Hopf <mhopf@...e.de>, rjw@...k.pl,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] NX protection for kernel data : fix 32 bits S3 suspend

On 02/06/2011 02:30 AM, Bodo Eggert wrote:
> H. Peter Anvin <hpa@...or.com> wrote:
> 
>> In static_protections() we have:
>>
>>>         /*
>>>          * The BIOS area between 640k and 1Mb needs to be executable for
>>>          * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
>>>          */
> 
> I don't think the CGA/MDA/VGA graphics memory areas should be executable,
> and I doubt execute access to these areas is required - is it?
> 
> 0xA000:0000 might be a BIOS area, if it is, you don't have a VGA and the
> ROM will be exactly 64K. 0xB800 and 0xB000 SHOULD NOT be a ROM, nobody dared
> to use it (I don't remember exactly where ROMs are searched).


0xA0000..0xBFFFF can be ROM if you don't have a VGA card; this is new in
PCI 3.x IIRC.  However, in legacy systems you will not have ROM in this
area.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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