linux-kernel - Re: [PATCH V5] x86: NX protection for kernel data

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Message-ID: <20091012213229.11898c12@infradead.org>
Date:	Mon, 12 Oct 2009 21:32:29 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Siarhei Liakh <sliakh.lkml@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	James Morris <jmorris@...ei.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@....de>, Rusty Russell <rusty@...tcorp.com.au>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	David Howells <dhowells@...hat.com>,
	Aristeu Rozanski <aris@...hat.com>
Subject: Re: [PATCH V5] x86: NX protection for kernel data

On Mon, 12 Oct 2009 21:03:17 -0400
Siarhei Liakh <sliakh.lkml@...il.com> wrote:

> This patch expands functionality of CONFIG_DEBUG_RODATA to set main
> (static) kernel data area as NX.
> The following steps are taken to achieve this:
> 1. Linker script is adjusted so .text always starts and ends on a
> page boundary 2. Linker script is adjusted so .rodata and .data
> always start and end on a page boundary
> 3. void mark_nxdata_nx(void) added to arch/x86/mm/init.c with actual
> functionality: NX is set for all pages from _etext through _end.
> 4. mark_nxdata_nx() called from free_initmem() (after init has been
> released) 5. free_init_pages() sets released memory NX in
> arch/x86/mm/init.c
> 
> The patch have been developed for Linux 2.6.31-rc7 x86 by Siarhei
> Liakh <sliakh.lkml@...il.com> and Xuxian Jiang <jiang@...ncsu.edu>.
> 

I like doing this, but... maybe it is useful to have a diff of the
pagetable dump (PT_DUMP config option) to show the effect, in the
changelog. That'd be like the proof on the pudding...


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
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