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Date: Sun, 19 Jul 2009 22:13:30 +0200 From: Sam Ravnborg <sam@...nborg.org> To: Siarhei Liakh <sliakh.lkml@...il.com> Cc: linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org, Andi Kleen <andi@...stfloor.org>, Rusty Russell <rusty@...tcorp.com.au>, Arjan van de Ven <arjan@...radead.org>, Ingo Molnar <mingo@...e.hu>, James Morris <jmorris@...ei.org>, Andrew Morton <akpm@...ux-foundation.org>, Andi Kleen <ak@....de>, Thomas Gleixner <tglx@...utronix.de>, "H. Peter Anvin" <hpa@...or.com>, linux-cris-kernel@...s.com, Roland Dreier <rdreier@...co.com> Subject: Re: [PATCH] x86: NX protection for kernel data On Sun, Jul 19, 2009 at 03:43:06PM -0400, Siarhei Liakh 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 scripts are adjusted so .text always starts and end on a page boundary > 2. Linker scripts are adjusted so .rodata and .data always starts and > end on a page boundary > 3. void mark_nxdata_nx(void) added to arch/x86/mm/init_64.c and > arch/x86/mm/init_32.c with actual functionality: NX is set for all > pages from _etext through _edata > 4. mark_nxdata_nx() called from init_post(void) in init/main.c > > The patch have been developed for Linux 2.6.30 x86 by Siarhei Liakh > <sliakh.lkml@...il.com> and Xuxian Jiang <jiang@...ncsu.edu>. The patch no longer applies. The file vmlinux_32.lds.S and vmlinux_64.lds.S has been unified into one file. > --- a/arch/x86/kernel/vmlinux_32.lds.S > +++ b/arch/x86/kernel/vmlinux_32.lds.S > @@ -47,6 +47,7 @@ SECTIONS > IRQENTRY_TEXT > *(.fixup) > *(.gnu.warning) > + . = ALIGN(PAGE_SIZE); /* .text should occupy whole number of pages */ > _etext = .; /* End of text section */ So _etext cover until page boundary - makes sense. > } :text = 0x9090 > > @@ -93,6 +94,7 @@ SECTIONS > *(.data.read_mostly) > _edata = .; /* End of data section */ > } > + . = ALIGN(PAGE_SIZE); /* needed so we can set NX for .data */ But here _edata does not cover until page boundary. And alignmnet is located outside the output section definition. It would be better/more consistent to follow the style you use for .text here. Sam -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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