From: Huang, Ying <ying.huang@intel.com>
Date: Wed, 17 Oct 2007 16:04:35 +0000 (+0200)
Subject: x86: NX bit handling in change_page_attr()
X-Git-Tag: v2.6.24-rc1~476^2~90
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84e0fdb1754d066dd0a8b257de7299f392d1e727;p=pandora-kernel.git

x86: NX bit handling in change_page_attr()

This patch fixes a bug of change_page_attr/change_page_attr_addr on
Intel x86_64 CPUs.  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>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

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