MIPS: Two-level pagetables for 64-bit kernels with 64KB pages.

For 64-bit kernels with 64KB pages and two level page tables, there are
42 bits worth of virtual address space This is larger than the 40 bits of
virtual address space obtained with the default 4KB Page size and three
levels, so there are no draw backs for using two level tables with this
configuration.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/761/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 34 insertions, 2 deletions

diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h
index 8eda30b467da..24314d21a708 100644
--- a/arch/mips/include/asm/pgtable-64.h
+++ b/arch/mips/include/asm/pgtable-64.h
@@ -16,7 +16,11 @@
 #include <asm/cachectl.h>
 #include <asm/fixmap.h>
 
+#ifdef CONFIG_PAGE_SIZE_64KB
+#include <asm-generic/pgtable-nopmd.h>
+#else
 #include <asm-generic/pgtable-nopud.h>
+#endif
 
 /*
  * Each address space has 2 4K pages as its page directory, giving 1024
@@ -37,13 +41,20 @@
  * fault address - VMALLOC_START.
  */
 
+
+/* PGDIR_SHIFT determines what a third-level page table entry can map */
+#ifdef __PAGETABLE_PMD_FOLDED
+#define PGDIR_SHIFT     (PAGE_SHIFT + PAGE_SHIFT + PTE_ORDER - 3)
+#else
+
 /* PMD_SHIFT determines the size of the area a second-level page table can map */
 #define PMD_SHIFT       (PAGE_SHIFT + (PAGE_SHIFT + PTE_ORDER - 3))
 #define PMD_SIZE        (1UL << PMD_SHIFT)
 #define PMD_MASK        (~(PMD_SIZE-1))
 
-/* PGDIR_SHIFT determines what a third-level page table entry can map */
+
 #define PGDIR_SHIFT     (PMD_SHIFT + (PAGE_SHIFT + PMD_ORDER - 3))
+#endif
 #define PGDIR_SIZE      (1UL << PGDIR_SHIFT)
 #define PGDIR_MASK      (~(PGDIR_SIZE-1))
 
@@ -92,12 +103,14 @@
 #ifdef CONFIG_PAGE_SIZE_64KB
 #define PGD_ORDER               0
 #define PUD_ORDER               aieeee_attempt_to_allocate_pud
-#define PMD_ORDER               0
+#define PMD_ORDER               aieeee_attempt_to_allocate_pmd
 #define PTE_ORDER               0
 #endif
 
 #define PTRS_PER_PGD    ((PAGE_SIZE << PGD_ORDER) / sizeof(pgd_t))
+#ifndef __PAGETABLE_PMD_FOLDED
 #define PTRS_PER_PMD    ((PAGE_SIZE << PMD_ORDER) / sizeof(pmd_t))
+#endif
 #define PTRS_PER_PTE    ((PAGE_SIZE << PTE_ORDER) / sizeof(pte_t))
 
 #if PGDIR_SIZE >= TASK_SIZE
@@ -122,15 +135,30 @@
 
 #define pte_ERROR(e) \
         printk("%s:%d: bad pte %016lx.\n", __FILE__, __LINE__, pte_val(e))
+#ifndef __PAGETABLE_PMD_FOLDED
 #define pmd_ERROR(e) \
         printk("%s:%d: bad pmd %016lx.\n", __FILE__, __LINE__, pmd_val(e))
+#endif
 #define pgd_ERROR(e) \
         printk("%s:%d: bad pgd %016lx.\n", __FILE__, __LINE__, pgd_val(e))
 
 extern pte_t invalid_pte_table[PTRS_PER_PTE];
 extern pte_t empty_bad_page_table[PTRS_PER_PTE];
+
+
+#ifndef __PAGETABLE_PMD_FOLDED
+/*
+ * For 3-level pagetables we defines these ourselves, for 2-level the
+ * definitions are supplied by <asm-generic/pgtable-nopmd.h>.
+ */
+typedef struct { unsigned long pmd; } pmd_t;
+#define pmd_val(x)      ((x).pmd)
+#define __pmd(x)        ((pmd_t) { (x) } )
+
+
 extern pmd_t invalid_pmd_table[PTRS_PER_PMD];
 extern pmd_t empty_bad_pmd_table[PTRS_PER_PMD];
+#endif
 
 /*
  * Empty pgd/pmd entries point to the invalid_pte_table.
@@ -151,6 +179,7 @@ static inline void pmd_clear(pmd_t *pmdp)
 {
         pmd_val(*pmdp) = ((unsigned long) invalid_pte_table);
 }
+#ifndef __PAGETABLE_PMD_FOLDED
 
 /*
  * Empty pud entries point to the invalid_pmd_table.
@@ -174,6 +203,7 @@ static inline void pud_clear(pud_t *pudp)
 {
         pud_val(*pudp) = ((unsigned long) invalid_pmd_table);
 }
+#endif
 
 #define pte_page(x)             pfn_to_page(pte_pfn(x))
 
@@ -198,6 +228,7 @@ static inline void pud_clear(pud_t *pudp)
 /* to find an entry in a page-table-directory */
 #define pgd_offset(mm, addr)    ((mm)->pgd + pgd_index(addr))
 
+#ifndef __PAGETABLE_PMD_FOLDED
 static inline unsigned long pud_page_vaddr(pud_t pud)
 {
         return pud_val(pud);
@@ -210,6 +241,7 @@ static inline pmd_t *pmd_offset(pud_t * pud, unsigned long address)
 {
         return (pmd_t *) pud_page_vaddr(*pud) + pmd_index(address);
 }
+#endif
 
 /* Find an entry in the third-level page table.. */
 #define __pte_offset(address)                                           \