From: Thomas Gleixner <tglx@linutronix.de>
Date: Fri, 15 Feb 2008 21:17:57 +0000 (+0100)
Subject: x86: CPA: avoid double checking of alias ranges
X-Git-Tag: v2.6.25-rc3~131^2~2
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f34b439f34c49d7de858234bab5e2dd03cfaf3c1;p=linux-2.6

x86: CPA: avoid double checking of alias ranges

When the CPA code is called with an virtual address in the range of
the direct mapping or the high alias then we do not need to run
through the alias check for this range.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index b8f5323315..3ee14996c8 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -594,19 +594,34 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias);
 static int cpa_process_alias(struct cpa_data *cpa)
 {
 	struct cpa_data alias_cpa;
-	int ret;
+	int ret = 0;
 
 	if (cpa->pfn > max_pfn_mapped)
 		return 0;
 
-	alias_cpa = *cpa;
-	alias_cpa.vaddr = (unsigned long) __va(cpa->pfn << PAGE_SHIFT);
+	/*
+	 * No need to redo, when the primary call touched the direct
+	 * mapping already:
+	 */
+	if (!within(cpa->vaddr, PAGE_OFFSET,
+		    PAGE_OFFSET + (max_pfn_mapped << PAGE_SHIFT))) {
 
-	ret = __change_page_attr_set_clr(&alias_cpa, 0);
+		alias_cpa = *cpa;
+		alias_cpa.vaddr = (unsigned long) __va(cpa->pfn << PAGE_SHIFT);
+
+		ret = __change_page_attr_set_clr(&alias_cpa, 0);
+	}
 
 #ifdef CONFIG_X86_64
 	if (ret)
 		return ret;
+	/*
+	 * No need to redo, when the primary call touched the high
+	 * mapping already:
+	 */
+	if (within(cpa->vaddr, (unsigned long) _text, (unsigned long) _end))
+		return 0;
+
 	/*
 	 * If the physical address is inside the kernel map, we need
 	 * to touch the high mapped kernel as well: