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authorWill Deacon <will.deacon@arm.com>2014-02-21 17:01:48 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2014-02-25 11:32:40 +0000
commit1971188aa19651d8f447211c6535fb68661d77c5 (patch)
treebfaccbce3e19113ebd908b59cd7208d8012709ca /arch
parentc32ffce0f66e5d1d4856254516e24f5ef275cd00 (diff)
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ARM: 7985/1: mm: implement pte_accessible for faulting mappings
The pte_accessible macro can be used to identify page table entries capable of being cached by a TLB. In principle, this differs from pte_present, since PROT_NONE mappings are mapped using invalid entries identified as present and ptes designated as `old' can use either invalid entries or those with the access flag cleared (guaranteed not to be in the TLB). However, there is a race to take care of, as described in 20841405940e ("mm: fix TLB flush race between migration, and change_protection_range"), between a page being migrated and mprotected at the same time. In this case, we can check whether a TLB invalidation is pending for the mm and if so, temporarily consider PROT_NONE mappings as valid. This patch implements a quick pte_accessible macro for ARM by simply checking if the pte is valid/present depending on the mm. For classic MMU, these checks are identical and will generate some false positives for PROT_NONE mappings, but this is better than the current asm-generic definition of ((void)(pte),1). Finally, pte_present_user is moved to use pte_valid (and renamed appropriately) since we don't care about cache flushing for faulting mappings. Acked-by: Steve Capper <steve.capper@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/include/asm/pgtable.h7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 7d59b524f2af..5478e5d6ad89 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -216,13 +216,16 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)
#define pte_none(pte) (!pte_val(pte))
#define pte_present(pte) (pte_val(pte) & L_PTE_PRESENT)
+#define pte_valid(pte) (pte_val(pte) & L_PTE_VALID)
+#define pte_accessible(mm, pte) (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid(pte))
#define pte_write(pte) (!(pte_val(pte) & L_PTE_RDONLY))
#define pte_dirty(pte) (pte_val(pte) & L_PTE_DIRTY)
#define pte_young(pte) (pte_val(pte) & L_PTE_YOUNG)
#define pte_exec(pte) (!(pte_val(pte) & L_PTE_XN))
#define pte_special(pte) (0)
-#define pte_present_user(pte) (pte_present(pte) && (pte_val(pte) & L_PTE_USER))
+#define pte_valid_user(pte) \
+ (pte_valid(pte) && (pte_val(pte) & L_PTE_USER) && pte_young(pte))
#if __LINUX_ARM_ARCH__ < 6
static inline void __sync_icache_dcache(pte_t pteval)
@@ -237,7 +240,7 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
{
unsigned long ext = 0;
- if (addr < TASK_SIZE && pte_present_user(pteval)) {
+ if (addr < TASK_SIZE && pte_valid_user(pteval)) {
__sync_icache_dcache(pteval);
ext |= PTE_EXT_NG;
}