[PATCH] NX protection for kernel data : support xen

[Matthieu CASTET]

Xen want page table pages read only.

But the initial page table (from head_*.S) live in .data or .bss.
Don't make static_protections enforce rw for .data/.bss in xen case.

Signed-off-by: Matthieu CASTET <castet.matthieu@xxxxxxx>
---
 arch/x86/mm/pageattr.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 8b830ca..8698521 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -283,11 +283,14 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 		   __pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
 		pgprot_val(forbidden) |= _PAGE_RW;
 	/*
-	 * .data and .bss should always be writable.
+	 * .data and .bss should always be writable, but xen won't like
+	 * if we make page table rw (that live in .data or .bss)
 	 */
+#ifndef CONFIG_XEN
 	if (within(address, (unsigned long)_sdata, (unsigned long)_edata) ||
 	    within(address, (unsigned long)__bss_start, (unsigned long)__bss_stop))
 		pgprot_val(required) |= _PAGE_RW;
+#endif
 
 #if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
 	/*
-- 
1.7.2.3


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