linux-kernel - [PATCH -V1] x86: make executable for video bios area

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Date:	Tue, 15 Nov 2011 14:42:38 +0800
From:	wangyanqing <udknight@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	castet.matthieu@...e.fr, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, gregkh@...e.de
Subject: [PATCH -V1] x86: make executable for video bios area

5bd5a452662bc37c54fb6828db1a3faf87e6511c make area
between BIOS_BEGIN and BIOS_END have NX protection
when boot machine with acpi enable(acpi will disable pcibios).

This commit make my machine can't boot, system hang with black screen
very early when I enable CONFIG_FB_UVESA, CONFIG_X86_PAE, CONFIG_ACPI.

below is the maps when boot normal without acpi:
00000000-00001000 rw-s 00000000 00:01 822        /dev/mem
00009000-0000a000 r-xp 00001000 00:01 912        /sbin/v86d
00010000-00050000 rwxp 00000000 00:01 818        /dev/zero
000a0000-000c0000 rw-s 000a0000 00:01 822        /dev/mem
000c0000-00100000 r-xs 000c0000 00:01 822        /dev/mem <== must executable
08048000-0804c000 r-xp 00001000 00:01 912        /sbin/v86d
0804c000-0804d000 rw-p 00004000 00:01 912        /sbin/v86d
b7875000-b7876000 r-xp 00000000 00:00 0          [vdso]
bfe9d000-bfebe000 rw-p 00000000 00:00 0          [stack]

So I prepare this patch.It works with me.
Any comment is welcome.

Thanks.

Signed-off-by: Wang YanQing <Udknight@...il.com>
---
 arch/x86/include/asm/e820.h |    2 ++
 arch/x86/mm/pageattr.c      |    3 ++-
 2 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h
index 908b969..a6fa897 100644
--- a/arch/x86/include/asm/e820.h
+++ b/arch/x86/include/asm/e820.h
@@ -72,6 +72,8 @@ struct e820map {
 #define BIOS_BEGIN		0x000a0000
 #define BIOS_END		0x00100000
 
+#define BIOS_VIDEO		0x000c0000
+
 #define BIOS_ROM_BASE		0xffe00000
 #define BIOS_ROM_END		0xffffffff
 
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index f9e5267..12acac0 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -260,7 +260,8 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 	 * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
 	 */
 #ifdef CONFIG_PCI_BIOS
-	if (pcibios_enabled && within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
+	if ((pcibios_enabled || within(pfn, BIOS_VIDEO >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT)) &&
+	     within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
 		pgprot_val(forbidden) |= _PAGE_NX;
 #endif
 
-- 
1.7.3.4

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