ARM: 7654/1: Preserve L_PTE_VALID in pte_modify()

Following commit 26ffd0d4 (ARM: mm: introduce present, faulting entries
for PAGE_NONE), if a page has been mapped as PROT_NONE, the L_PTE_VALID
bit is cleared by the set_pte_ext() code. With LPAE the software and
hardware pte share the same location and subsequent modifications of pte
range (change_protection()) will leave the L_PTE_VALID bit cleared.

This patch adds the L_PTE_VALID bit to the newprot mask in pte_modify().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Subash Patel <subash.rp@samsung.com>
Tested-by: Subash Patel <subash.rp@samsung.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: <stable@vger.kernel.org> # 3.8.x
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 9c82f988c0e3..c09474942f3e 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -240,7 +240,8 @@ static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
 
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
-        const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER | L_PTE_NONE;
+        const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER |
+                L_PTE_NONE | L_PTE_VALID;
         pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
         return pte;
 }