linux-kernel - [PATCH 1/2] x86: Fix pXd_flags() to handle _PAGE_PAT

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Date:	Thu,  9 Jul 2015 11:03:50 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	hpa@...or.com, tglx@...utronix.de, mingo@...hat.com
Cc:	akpm@...ux-foundation.org, bp@...en8.de, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, x86@...nel.org, jgross@...e.com,
	konrad.wilk@...cle.com, elliott@...com,
	Toshi Kani <toshi.kani@...com>
Subject: [PATCH 1/2] x86: Fix pXd_flags() to handle _PAGE_PAT_LARGE

The PAT bit gets relocated to bit 12 when PUD and PMD mappings are
used.  This bit 12, however, is not covered by PTE_FLAGS_MASK, which
is corrently used for masking the flag bits for all cases.

Fix pud_flags() and pmd_flags() to cover the PAT bit, _PAGE_PAT_LARGE,
when they are used to map a large page with _PAGE_PSE set.

Signed-off-by: Toshi Kani <toshi.kani@...com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Konrad Wilk <konrad.wilk@...cle.com>
Cc: Robert Elliott <elliott@...com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
---
 arch/x86/include/asm/pgtable_types.h |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 13f310b..caaf45c 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -212,9 +212,13 @@ enum page_cache_mode {
 /* PTE_PFN_MASK extracts the PFN from a (pte|pmd|pud|pgd)val_t */
 #define PTE_PFN_MASK		((pteval_t)PHYSICAL_PAGE_MASK)
 
-/* PTE_FLAGS_MASK extracts the flags from a (pte|pmd|pud|pgd)val_t */
+/* Extracts the flags from a (pte|pmd|pud|pgd)val_t of a 4KB page */
 #define PTE_FLAGS_MASK		(~PTE_PFN_MASK)
 
+/* Extracts the flags from a (pmd|pud)val_t of a (1GB|2MB) page */
+#define PMD_FLAGS_MASK_LARGE	((~PTE_PFN_MASK) | _PAGE_PAT_LARGE)
+#define PUD_FLAGS_MASK_LARGE	((~PTE_PFN_MASK) | _PAGE_PAT_LARGE)
+
 typedef struct pgprot { pgprotval_t pgprot; } pgprot_t;
 
 typedef struct { pgdval_t pgd; } pgd_t;
@@ -278,12 +282,18 @@ static inline pmdval_t native_pmd_val(pmd_t pmd)
 
 static inline pudval_t pud_flags(pud_t pud)
 {
-	return native_pud_val(pud) & PTE_FLAGS_MASK;
+	if (native_pud_val(pud) & _PAGE_PSE)
+		return native_pud_val(pud) & PUD_FLAGS_MASK_LARGE;
+	else
+		return native_pud_val(pud) & PTE_FLAGS_MASK;
 }
 
 static inline pmdval_t pmd_flags(pmd_t pmd)
 {
-	return native_pmd_val(pmd) & PTE_FLAGS_MASK;
+	if (native_pmd_val(pmd) & _PAGE_PSE)
+		return native_pmd_val(pmd) & PMD_FLAGS_MASK_LARGE;
+	else
+		return native_pmd_val(pmd) & PTE_FLAGS_MASK;
 }
 
 static inline pte_t native_make_pte(pteval_t val)
--
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