From: Andrew Morton <akpm@linux-foundation.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Andi Kleen <ak@suse.de>, linux-kernel@vger.kernel.org
Subject: Re: [BUGFIX] x86_64: NX bit handling in change_page_attr
Date: Tue, 11 Sep 2007 20:23:32 -0700 [thread overview]
Message-ID: <20070911202332.c539f1fe.akpm@linux-foundation.org> (raw)
In-Reply-To: <1187328518.28497.6.camel@caritas-dev.intel.com>
On Fri, 17 Aug 2007 13:28:38 +0800 "Huang, Ying" <ying.huang@intel.com> wrote:
> This patch fixes a bug of change_page_attr/change_page_attr_addr on
> Intel x86_64 CPU. After changing page attribute to be executable with
> these functions, the page remains un-executable on Intel x86_64
> CPU. Because on Intel x86_64 CPU, only if the "NX" bits of all four
> level page tables are cleared, the corresponding page is executable
> (refer to section 4.13.2 of Intel 64 and IA-32 Architectures Software
> Developer's Manual). So, the bug is fixed through clearing the "NX"
> bit of PMD when splitting the huge PMD.
>
> Signed-off-by: Huang Ying <ying.huang@intel.com>
>
> ---
>
> Index: linux-2.6.23-rc2-mm2/arch/x86_64/mm/pageattr.c
> ===================================================================
> --- linux-2.6.23-rc2-mm2.orig/arch/x86_64/mm/pageattr.c 2007-08-17 12:50:25.000000000 +0800
> +++ linux-2.6.23-rc2-mm2/arch/x86_64/mm/pageattr.c 2007-08-17 12:50:48.000000000 +0800
> @@ -147,6 +147,7 @@
> split = split_large_page(address, prot, ref_prot2);
> if (!split)
> return -ENOMEM;
> + pgprot_val(ref_prot2) &= ~_PAGE_NX;
> set_pte(kpte, mk_pte(split, ref_prot2));
> kpte_page = split;
> }
What happened with this? Still valid?
next prev parent reply other threads:[~2007-09-12 3:23 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-17 5:28 [BUGFIX] x86_64: NX bit handling in change_page_attr Huang, Ying
2007-09-12 3:23 ` Andrew Morton [this message]
2007-09-12 6:18 ` Huang, Ying
2007-09-12 13:35 ` Andi Kleen
2007-09-13 1:12 ` Huang, Ying
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