[PATCH] [23/36] CPA: Make change_page_attr() more robust against use of PAT bits

!MAILaRCHIVE_VOTE_RePLACE
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To: <linux-kernel@...>, <mingo@...>, <tglx@...>, <jbeulich@...>, <venkatesh.pallipadi@...>
Date: Wednesday, January 16, 2008 - 6:15 pm

Use the page table level instead of the PSE bit to check if the PTE 
is for a 4K page or not. This makes the code more robust when the PAT
bit is changed because the PAT bit on 4K pages is in the same position as the
PSE bit.

Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Jan Beulich <jbeulich@novell.com>

---
 arch/x86/mm/pageattr_32.c |    4 ++--
 arch/x86/mm/pageattr_64.c |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

Index: linux/arch/x86/mm/pageattr_32.c
===================================================================
--- linux.orig/arch/x86/mm/pageattr_32.c
+++ linux/arch/x86/mm/pageattr_32.c
@@ -209,7 +209,7 @@ __change_page_attr(struct page *page, pg
 	set_tlb_flush(address);
 
 	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) { 
-		if (!pte_huge(*kpte)) {
+		if (level == 3) {
 			set_pte_atomic(kpte, mk_pte(page, prot)); 
 		} else {
 			pgprot_t ref_prot;
@@ -225,7 +225,7 @@ __change_page_attr(struct page *page, pg
 			kpte_page = split;
 		}
 		page_private(kpte_page)++;
-	} else if (!pte_huge(*kpte)) {
+	} else if (level == 3) {
 		set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
 		BUG_ON(page_private(kpte_page) == 0);
 		page_private(kpte_page)--;
Index: linux/arch/x86/mm/pageattr_64.c
===================================================================
--- linux.orig/arch/x86/mm/pageattr_64.c
+++ linux/arch/x86/mm/pageattr_64.c
@@ -184,7 +184,7 @@ __change_page_attr(unsigned long address
 	set_tlb_flush(address);
 
 	if (pgprot_val(prot) != pgprot_val(ref_prot)) { 
-		if (!pte_huge(*kpte)) {
+		if (level == 4) {
 			set_pte(kpte, pfn_pte(pfn, prot));
 		} else {
 			/*
@@ -201,7 +201,7 @@ __change_page_attr(unsigned long address
 			kpte_page = split;
 		}
 		page_private(kpte_page)++;
-	} else if (!pte_huge(*kpte)) {
+	} else if (level == 4) {
 		set_pte(kpte, pfn_pte(pfn, ref_prot));
 		BUG_ON(page_private(kpte_page) == 0);
 		page_private(kpte_page)--;
--
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Messages in current thread:
[PATCH] [35/36] Remove set_kernel_exec, Andi Kleen, (Wed Jan 16, 6:15 pm)
[PATCH] [36/36] Clean up pte_exec, Andi Kleen, (Wed Jan 16, 6:15 pm)
[PATCH] [23/36] CPA: Make change_page_attr() more robust aga..., Andi Kleen, (Wed Jan 16, 6:15 pm)
[PATCH] [14/36] CPA: Add simple self test at boot, Andi Kleen, (Wed Jan 16, 6:15 pm)
[PATCH] [10/36] Add pte_pgprot on i386, Andi Kleen, (Wed Jan 16, 6:15 pm)
[PATCH] [9/36] Add pte accessors for the global bit, Andi Kleen, (Wed Jan 16, 6:15 pm)
[PATCH] [8/36] CPA: Do a simple self test at boot, Andi Kleen, (Wed Jan 16, 6:15 pm)
[PATCH] [4/36] CPA: Undo white space changes, Andi Kleen, (Wed Jan 16, 6:15 pm)
[PATCH] [1/36] Undo pat cpa patch, Andi Kleen, (Wed Jan 16, 6:14 pm)