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x86: CPA return early when requested feature is not available 

Mask out the not supported bits (e.g. NX). If the clr/set masks
are empty after the mask return without changing anything.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner 2008-02-04 16:48:06 +01:00 committed by Ingo Molnar
parent 1c083eb2cb
commit 331e406588
1 changed files with 12 additions and 2 deletions
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14
arch/x86/mm/pageattr.c
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@ -405,8 +405,18 @@ static int __change_page_attr_set_clr(unsigned long addr, int numpages,
static int change_page_attr_set_clr(unsigned long addr, int numpages,
pgprot_t mask_set, pgprot_t mask_clr)
{
int ret = __change_page_attr_set_clr(addr, numpages, mask_set,
mask_clr);
int ret;
/*
* Check, if we are requested to change a not supported
* feature:
*/
mask_set = canon_pgprot(mask_set);
mask_clr = canon_pgprot(mask_clr);
if (!pgprot_val(mask_set) && !pgprot_val(mask_clr))
return 0;
ret = __change_page_attr_set_clr(addr, numpages, mask_set, mask_clr);
/*
* On success we use clflush, when the CPU supports it to