From 331e406588dc90331753e6562e5e3757bb907eb8 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 4 Feb 2008 16:48:06 +0100 Subject: [PATCH] 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 Signed-off-by: Ingo Molnar --- arch/x86/mm/pageattr.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index a629cea5e465..f60b93dc2e57 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -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