sh: Provide _PAGE_SPECIAL for 32-bit.

Allocate one of the unused PTE bits for _PAGE_SPECIAL directly. This is
prep work for fast gup and the zero page revival.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

diff --git a/arch/sh/include/asm/pgtable_32.h b/arch/sh/include/asm/pgtable_32.h
index 72ea209..0db19db 100644 (file)
--- a/arch/sh/include/asm/pgtable_32.h
+++ b/arch/sh/include/asm/pgtable_32.h
@@ -20,7 +20,7 @@
  * - Bit 9 is reserved by everyone and used by _PAGE_PROTNONE.
  *
  * - Bits 10 and 11 are low bits of the PPN that are reserved on >= 4K pages.
- *   Bit 10 is used for _PAGE_ACCESSED, bit 11 remains unused.
+ *   Bit 10 is used for _PAGE_ACCESSED, and bit 11 is used for _PAGE_SPECIAL.
  *
  * - On 29 bit platforms, bits 31 to 29 are used for the space attributes
  *   and timing control which (together with bit 0) are moved into the
@@ -52,6 +52,7 @@
 #define _PAGE_PROTNONE 0x200           /* software: if not present  */
 #define _PAGE_ACCESSED 0x400           /* software: page referenced */
 #define _PAGE_FILE     _PAGE_WT        /* software: pagecache or swap? */
+#define _PAGE_SPECIAL  0x800           /* software: special page */
 
 #define _PAGE_SZ_MASK  (_PAGE_SZ0 | _PAGE_SZ1)
 #define _PAGE_PR_MASK  (_PAGE_RW | _PAGE_USER)
@@ -148,8 +149,12 @@
 # define _PAGE_SZHUGE  (_PAGE_FLAGS_HARD)
 #endif
 
+/*
+ * Mask of bits that are to be preserved accross pgprot changes.
+ */
 #define _PAGE_CHG_MASK \
-       (PTE_MASK | _PAGE_ACCESSED | _PAGE_CACHABLE | _PAGE_DIRTY)
+       (PTE_MASK | _PAGE_ACCESSED | _PAGE_CACHABLE | \
+        _PAGE_DIRTY | _PAGE_SPECIAL)
 
 #ifndef __ASSEMBLY__
 
@@ -328,7 +333,7 @@ static inline void set_pte(pte_t *ptep, pte_t pte)
 #define pte_dirty(pte)         ((pte).pte_low & _PAGE_DIRTY)
 #define pte_young(pte)         ((pte).pte_low & _PAGE_ACCESSED)
 #define pte_file(pte)          ((pte).pte_low & _PAGE_FILE)
-#define pte_special(pte)       (0)
+#define pte_special(pte)       ((pte).pte_low & _PAGE_SPECIAL)
 
 #ifdef CONFIG_X2TLB
 #define pte_write(pte)         ((pte).pte_high & _PAGE_EXT_USER_WRITE)
@@ -358,8 +363,9 @@ PTE_BIT_FUNC(low, mkclean, &= ~_PAGE_DIRTY);
 PTE_BIT_FUNC(low, mkdirty, |= _PAGE_DIRTY);
 PTE_BIT_FUNC(low, mkold, &= ~_PAGE_ACCESSED);
 PTE_BIT_FUNC(low, mkyoung, |= _PAGE_ACCESSED);
+PTE_BIT_FUNC(low, mkspecial, |= _PAGE_SPECIAL);
 
-static inline pte_t pte_mkspecial(pte_t pte) { return pte; }
+#define __HAVE_ARCH_PTE_SPECIAL
 
 /*
  * Macro and implementation to make a page protection as uncachable.