x86, nx: Don't force pages RW when setting NX bits

Xen want page table pages read only. But the initial page table (from head_*.S) live in .data or .bss. That was broken by 64edc8e. There is absolutely no reason to force these pages RW after they have already been marked RO. Signed-off-by: Matthieu CASTET <[email protected]> Tested-by: Konrad Rzeszutek Wilk <[email protected]> Signed-off-by: H. Peter Anvin <[email protected]>
mna · Feb 3, 2011 · f12d3d0 · f12d3d0
1 parent afe8a88
commit f12d3d0
Showing 1 changed file with 0 additions and 8 deletions.
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
@@ -256,7 +256,6 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 				   unsigned long pfn)
 {
 	pgprot_t forbidden = __pgprot(0);
-	pgprot_t required = __pgprot(0);
 
 	/*
 	 * The BIOS area between 640k and 1Mb needs to be executable for
@@ -282,12 +281,6 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 	if (within(pfn, __pa((unsigned long)__start_rodata) >> PAGE_SHIFT,
 		   __pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
 		pgprot_val(forbidden) |= _PAGE_RW;
-	/*
-	 * .data and .bss should always be writable.
-	 */
-	if (within(address, (unsigned long)_sdata, (unsigned long)_edata) ||
-	    within(address, (unsigned long)__bss_start, (unsigned long)__bss_stop))
-		pgprot_val(required) |= _PAGE_RW;
 
 #if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
 	/*
@@ -327,7 +320,6 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 #endif
 
 	prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
-	prot = __pgprot(pgprot_val(prot) | pgprot_val(required));
 
 	return prot;
 }