From: Jarod Wilson <jwilson@redhat.com>
Date: Mon, 8 Oct 2007 11:49:27 -0400
Subject: [x86_64] Add NX mask for PTE entry
Message-id: 470A5187.3000709@redhat.com
O-Subject: [RHEL5.2 PATCH] x86_64: Add NX mask for PTE entry
Bugzilla: 232748

Bugzilla #232748: X crashes during logout on x86_64 system with i945
graphics and XD disabled
https://bugzilla.redhat.com/show_bug.cgi?id=232748

Description
-----------
X crashes on logout/restart when running on x86_64 arch, with i945
graphics and XD bit capability is disabled.

Same as upstream freedesktop.org bug:
https://bugs.freedesktop.org/show_bug.cgi?id=5085

Patch posted upstream to lkml:
http://lkml.org/lkml/2006/10/18/68

Summary on lkml posting:
--
If function change_page_attr_addr calls revert_page to revert
to original pte value, mk_pte_phys does not mask NX bit. If NX bit
is set on no NX hardware supported x86_64 machine, there is will
be RSVD type page fault and system will crash. This patch adds NX
mask bit for PTE entry.
--

Test status
-----------
I have no reproducing hardware myself, but the original bug reporter
applied the upstream 1-line patch atop a RHEL5 kernel, and no longer
experiences crashes on X logout.

Please ACK.

--
Jarod Wilson
jwilson@redhat.com

Acked-by: Larry Woodman <lwoodman@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Pete Zaitcev <zaitcev@redhat.com>
Acked-by: Chris Lalancette <clalance@redhat.com>
---
 include/asm-x86_64/pgtable.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/include/asm-x86_64/pgtable.h b/include/asm-x86_64/pgtable.h
index c63ecb7..20cf067 100644
--- a/include/asm-x86_64/pgtable.h
+++ b/include/asm-x86_64/pgtable.h
@@ -390,6 +390,7 @@ static inline pte_t mk_pte_phys(unsigned long physpage, pgprot_t pgprot)
 { 
 	pte_t pte;
 	pte_val(pte) = physpage | pgprot_val(pgprot); 
+	pte_val(pte) &= __supported_pte_mask;
 	return pte; 
 }
  
-- 
1.5.3.5.645.gbb47