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, 27 insertions, 17 deletions

diff --git a/arch/mips/mm/pgtable-64.c b/arch/mips/mm/pgtable-64.c
index 1121019fa456..78eaa4f0b0ec 100644
--- a/arch/mips/mm/pgtable-64.c
+++ b/arch/mips/mm/pgtable-64.c
@@ -15,23 +15,31 @@
 void pgd_init(unsigned long page)
 {
         unsigned long *p, *end;
+        unsigned long entry;
+
+#ifdef __PAGETABLE_PMD_FOLDED
+        entry = (unsigned long)invalid_pte_table;
+#else
+        entry = (unsigned long)invalid_pmd_table;
+#endif
 
         p = (unsigned long *) page;
         end = p + PTRS_PER_PGD;
 
         while (p < end) {
-                p[0] = (unsigned long) invalid_pmd_table;
-                p[1] = (unsigned long) invalid_pmd_table;
-                p[2] = (unsigned long) invalid_pmd_table;
-                p[3] = (unsigned long) invalid_pmd_table;
-                p[4] = (unsigned long) invalid_pmd_table;
-                p[5] = (unsigned long) invalid_pmd_table;
-                p[6] = (unsigned long) invalid_pmd_table;
-                p[7] = (unsigned long) invalid_pmd_table;
+                p[0] = entry;
+                p[1] = entry;
+                p[2] = entry;
+                p[3] = entry;
+                p[4] = entry;
+                p[5] = entry;
+                p[6] = entry;
+                p[7] = entry;
                 p += 8;
         }
 }
 
+#ifndef __PAGETABLE_PMD_FOLDED
 void pmd_init(unsigned long addr, unsigned long pagetable)
 {
         unsigned long *p, *end;
@@ -40,17 +48,18 @@ void pmd_init(unsigned long addr, unsigned long pagetable)
         end = p + PTRS_PER_PMD;
 
         while (p < end) {
-                p[0] = (unsigned long)pagetable;
-                p[1] = (unsigned long)pagetable;
-                p[2] = (unsigned long)pagetable;
-                p[3] = (unsigned long)pagetable;
-                p[4] = (unsigned long)pagetable;
-                p[5] = (unsigned long)pagetable;
-                p[6] = (unsigned long)pagetable;
-                p[7] = (unsigned long)pagetable;
+                p[0] = pagetable;
+                p[1] = pagetable;
+                p[2] = pagetable;
+                p[3] = pagetable;
+                p[4] = pagetable;
+                p[5] = pagetable;
+                p[6] = pagetable;
+                p[7] = pagetable;
                 p += 8;
         }
 }
+#endif
 
 void __init pagetable_init(void)
 {
@@ -59,8 +68,9 @@ void __init pagetable_init(void)
 
         /* Initialize the entire pgd.  */
         pgd_init((unsigned long)swapper_pg_dir);
+#ifndef __PAGETABLE_PMD_FOLDED
         pmd_init((unsigned long)invalid_pmd_table, (unsigned long)invalid_pte_table);
-
+#endif
         pgd_base = swapper_pg_dir;
         /*
          * Fixed mappings: