ARM: pgtable: switch order of Linux vs hardware page tables

This switches the ordering of the Linux vs hardware page tables in
each page, thereby eliminating some of the arithmetic in the page
table walks.  As we now place the Linux page table at the beginning
of the page, we can deal with the offset in the pgt by simply masking
it away, along with the other control bits.

This also makes the arithmetic all be positive, rather than a mixture.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 17 insertions, 22 deletions

diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h
index 1f1064b..9763be0 100644
--- a/arch/arm/include/asm/pgalloc.h
+++ b/arch/arm/include/asm/pgalloc.h
@@ -35,6 +35,11 @@ extern void pgd_free(struct mm_struct *mm, pgd_t *pgd);
 
 #define PGALLOC_GFP	(GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO)
 
+static inline void clean_pte_table(pte_t *pte)
+{
+	clean_dcache_area(pte + PTE_HWTABLE_PTRS, PTE_HWTABLE_SIZE);
+}
+
 /*
  * Allocate one PTE table.
  *
@@ -42,14 +47,14 @@ extern void pgd_free(struct mm_struct *mm, pgd_t *pgd);
  * into one table thus:
  *
  *  +------------+
- *  |  h/w pt 0  |
- *  +------------+
- *  |  h/w pt 1  |
- *  +------------+
  *  | Linux pt 0 |
  *  +------------+
  *  | Linux pt 1 |
  *  +------------+
+ *  |  h/w pt 0  |
+ *  +------------+
+ *  |  h/w pt 1  |
+ *  +------------+
  */
 static inline pte_t *
 pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
@@ -57,10 +62,8 @@ pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
 	pte_t *pte;
 
 	pte = (pte_t *)__get_free_page(PGALLOC_GFP);
-	if (pte) {
-		clean_dcache_area(pte, sizeof(pte_t) * PTRS_PER_PTE);
-		pte += PTRS_PER_PTE;
-	}
+	if (pte)
+		clean_pte_table(pte);
 
 	return pte;
 }
@@ -76,10 +79,8 @@ pte_alloc_one(struct mm_struct *mm, unsigned long addr)
 	pte = alloc_pages(PGALLOC_GFP, 0);
 #endif
 	if (pte) {
-		if (!PageHighMem(pte)) {
-			void *page = page_address(pte);
-			clean_dcache_area(page, sizeof(pte_t) * PTRS_PER_PTE);
-		}
+		if (!PageHighMem(pte))
+			clean_pte_table(page_address(pte));
 		pgtable_page_ctor(pte);
 	}
 
@@ -91,10 +92,8 @@ pte_alloc_one(struct mm_struct *mm, unsigned long addr)
  */
 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 {
-	if (pte) {
-		pte -= PTRS_PER_PTE;
+	if (pte)
 		free_page((unsigned long)pte);
-	}
 }
 
 static inline void pte_free(struct mm_struct *mm, pgtable_t pte)
@@ -106,7 +105,7 @@ static inline void pte_free(struct mm_struct *mm, pgtable_t pte)
 static inline void __pmd_populate(pmd_t *pmdp, phys_addr_t pte,
 	unsigned long prot)
 {
-	unsigned long pmdval = pte | prot;
+	unsigned long pmdval = (pte + PTE_HWTABLE_OFF) | prot;
 	pmdp[0] = __pmd(pmdval);
 	pmdp[1] = __pmd(pmdval + 256 * sizeof(pte_t));
 	flush_pmd_entry(pmdp);
@@ -121,14 +120,10 @@ static inline void __pmd_populate(pmd_t *pmdp, phys_addr_t pte,
 static inline void
 pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp, pte_t *ptep)
 {
-	unsigned long pte_ptr = (unsigned long)ptep;
-
 	/*
-	 * The pmd must be loaded with the physical
-	 * address of the PTE table
+	 * The pmd must be loaded with the physical address of the PTE table
 	 */
-	pte_ptr -= PTRS_PER_PTE * sizeof(void *);
-	__pmd_populate(pmdp, __pa(pte_ptr), _PAGE_KERNEL_TABLE);
+	__pmd_populate(pmdp, __pa(ptep), _PAGE_KERNEL_TABLE);
 }
 
 static inline void