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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 64edc8ed5f.  There is
absolutely no reason to force these pages RW after they have already
been marked RO.

Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Matthieu CASTET 2011-01-20 21:11:45 +01:00 committed by H. Peter Anvin
parent afe8a88755
commit f12d3d04e8
1 changed files with 0 additions and 8 deletions
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8
arch/x86/mm/pageattr.c
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@ -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;
}