[MIPS] Fix non-linear memory mapping on MIPS

    
Fix the non-linear memory mapping done via remap_file_pages() -- it
didn't work on any MIPS CPU because the page offset clashing with
_PAGE_FILE and some other page protection bits which should have been left
zeros for this kind of pages.
Signed-off-by: Konstantin Baydarov <kbaidarov@ru.mvista.com>
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

include/asm-mips/pgtable-32.h

@@ -177,16 +177,18 @@ pfn_pte(unsigned long pfn, pgprot_t prot)
 	((swp_entry_t) { ((type) << 10) | ((offset) << 15) })
 
 /*
- * Bits 0, 1, 2, 9 and 10 are taken, split up the 27 bits of offset
- * into this range:
+ * Bits 0, 4, 8, and 9 are taken, split up 28 bits of offset into this range:
  */
-#define PTE_FILE_MAX_BITS	27
+#define PTE_FILE_MAX_BITS	28
 
-#define pte_to_pgoff(_pte) \
-	((((_pte).pte >> 3) & 0x3f ) + (((_pte).pte >> 11) << 8 ))
+#define pte_to_pgoff(_pte)	((((_pte).pte >> 1 ) & 0x07) | \
+				 (((_pte).pte >> 2 ) & 0x38) | \
+				 (((_pte).pte >> 10) <<  6 ))
 
-#define pgoff_to_pte(off) \
-	((pte_t) { (((off) & 0x3f) << 3) + (((off) >> 8) << 11) + _PAGE_FILE })
+#define pgoff_to_pte(off)	((pte_t) { (((off) & 0x07) << 1 ) | \
+					   (((off) & 0x38) << 2 ) | \
+					   (((off) >>  6 ) << 10) | \
+					   _PAGE_FILE })
 
 #else
 
@@ -203,24 +205,29 @@ pfn_pte(unsigned long pfn, pgprot_t prot)
 		((swp_entry_t)  { ((type) << 8) | ((offset) << 13) })
 #endif /* defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32) */
 
+#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
 /*
- * Bits 0, 1, 2, 7 and 8 are taken, split up the 27 bits of offset
- * into this range:
+ * Bits 0 and 1 of pte_high are taken, use the rest for the page offset...
  */
-#define PTE_FILE_MAX_BITS	27
+#define PTE_FILE_MAX_BITS	30
 
-#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32_R1)
-	/* fixme */
-#define pte_to_pgoff(_pte) (((_pte).pte_high >> 6) + ((_pte).pte_high & 0x3f))
-#define pgoff_to_pte(off) \
-	((pte_t){(((off) & 0x3f) + ((off) << 6) + _PAGE_FILE)})
+#define pte_to_pgoff(_pte)	((_pte).pte_high >> 2)
+#define pgoff_to_pte(off) 	((pte_t) { _PAGE_FILE, (off) << 2 })
 
 #else
-#define pte_to_pgoff(_pte) \
-	((((_pte).pte >> 3) & 0x1f ) + (((_pte).pte >> 9) << 6 ))
+/*
+ * Bits 0, 4, 6, and 7 are taken, split up 28 bits of offset into this range:
+ */
+#define PTE_FILE_MAX_BITS	28
+
+#define pte_to_pgoff(_pte)	((((_pte).pte >> 1) & 0x7) | \
+				 (((_pte).pte >> 2) & 0x8) | \
+				 (((_pte).pte >> 8) <<  4))
 
-#define pgoff_to_pte(off) \
-	((pte_t) { (((off) & 0x1f) << 3) + (((off) >> 6) << 9) + _PAGE_FILE })
+#define pgoff_to_pte(off)	((pte_t) { (((off) & 0x7) << 1) | \
+					   (((off) & 0x8) << 2) | \
+					   (((off) >>  4) << 8) | \
+					   _PAGE_FILE })
 #endif
 
 #endif

include/asm-mips/pgtable-64.h

@@ -224,15 +224,12 @@ static inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
 #define __swp_entry_to_pte(x)	((pte_t) { (x).val })
 
 /*
- * Bits 0, 1, 2, 7 and 8 are taken, split up the 32 bits of offset
- * into this range:
+ * Bits 0, 4, 6, and 7 are taken. Let's leave bits 1, 2, 3, and 5 alone to
+ * make things easier, and only use the upper 56 bits for the page offset...
  */
-#define PTE_FILE_MAX_BITS	32
+#define PTE_FILE_MAX_BITS	56
 
-#define pte_to_pgoff(_pte) \
-	((((_pte).pte >> 3) & 0x1f ) + (((_pte).pte >> 9) << 6 ))
-
-#define pgoff_to_pte(off) \
-	((pte_t) { (((off) & 0x1f) << 3) + (((off) >> 6) << 9) + _PAGE_FILE })
+#define pte_to_pgoff(_pte)	((_pte).pte >> 8)
+#define pgoff_to_pte(off)	((pte_t) { ((off) << 8) | _PAGE_FILE })
 
 #endif /* _ASM_PGTABLE_64_H */