[PATCH] NX protection for kernel data : fix xen boot

[matthieu castet <castet.matthieu@free.fr>]

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I think it should be applied before 2.6.38 release, because without
this patch S3 suspend doesn't work on x86_32 with CONFIG_DEBUG_RODATA.



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>From 8e4bdefe9649a89c972974d94510f0c2bd2d0ea4 Mon Sep 17 00:00:00 2001
From: Matthieu CASTET <castet.matthieu@free.fr>
Date: Thu, 27 Jan 2011 21:36:07 +0100
Subject: [PATCH] NX protection for kernel data : fix 32 bits wakeup

32 bits wakeup realmode trampoline enable paging, while still
in low memory.

We should make this memory !NX in order it works.

Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Tested-by: Matthias Hopf <mhopf@suse.de>
---
 arch/x86/mm/init_32.c  |    8 ++++++++
 arch/x86/mm/pageattr.c |    7 +++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index c821074..0048738 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -227,6 +227,14 @@ page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
 
 static inline int is_kernel_text(unsigned long addr)
 {
+#if defined(CONFIG_X86_32) && defined(CONFIG_ACPI_SLEEP)
+	/*
+	 * We need to make the wakeup trampoline in first 1MB !NX
+	 */
+	if (addr >= PAGE_OFFSET && addr <= (PAGE_OFFSET + (1<<20)))
+		return 1;
+#endif
+
 	if (addr >= (unsigned long)_text && addr <= (unsigned long)__init_end)
 		return 1;
 	return 0;
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index d343b3c..f1d6cf5 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -265,6 +265,13 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 	if (pcibios_enabled && within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
 		pgprot_val(forbidden) |= _PAGE_NX;
 #endif
+	/*
+	 * We need to make the wakeup trampoline in first 1MB !NX
+	 */
+#if defined(CONFIG_X86_32) && defined(CONFIG_ACPI_SLEEP)
+	if (within(address, PAGE_OFFSET, PAGE_OFFSET + (1<<20)))
+		pgprot_val(forbidden) |= _PAGE_NX;
+#endif
 
 	/*
 	 * The kernel text needs to be executable for obvious reasons
-- 
1.7.2.3