[PATCH] Fix swap entry for MIPS32 36-bit physical address

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

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Hello.

    With 64-bit physical address enabled, 'swapon' was causing kernel oops
on Alchemy CPUs (MIPS32R1) because of the swap entry type field corrupting the
_PAGE_FILE bit in pte_low. So, change layout of the swap entry to use all bits
except _PAGE_PRESENT and _PAGE_FILE (the harware protection bits are loaded
from pte_high which should be cleared by __swp_entry_to_pte() macro) -- which
gives 25 bits for the swap entry offset.
    Additionally, PTEs in MIPS32R2 should have the same layout for the 36-bit
physical address case as in MIPS32R1, according to the architecture manuals --
so, fix the #ifdef's.

WBR, Sergei

Signed-off-by: Konstantin Baydarov <kbaidarov@ru.mvista.com>
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>



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diff --git a/include/asm-mips/pgtable-32.h b/include/asm-mips/pgtable-32.h
index 0cff64c..89c269f 100644
--- a/include/asm-mips/pgtable-32.h
+++ b/include/asm-mips/pgtable-32.h
@@ -116,7 +116,7 @@ static inline void pmd_clear(pmd_t *pmdp
 	pmd_val(*pmdp) = ((unsigned long) invalid_pte_table);
 }
 
-#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32_R1)
+#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
 #define pte_page(x)		pfn_to_page(pte_pfn(x))
 #define pte_pfn(x)		((unsigned long)((x).pte_high >> 6))
 static inline pte_t
@@ -139,7 +139,7 @@ pfn_pte(unsigned long pfn, pgprot_t prot
 #define pte_pfn(x)		((unsigned long)((x).pte >> PAGE_SHIFT))
 #define pfn_pte(pfn, prot)	__pte(((unsigned long long)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
 #endif
-#endif /* defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32_R1) */
+#endif /* defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32) */
 
 #define __pgd_offset(address)	pgd_index(address)
 #define __pud_offset(address)	(((address) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
@@ -190,11 +190,27 @@ pfn_pte(unsigned long pfn, pgprot_t prot
 
 #else
 
+#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
+/*
+ * For 36-bit physical address we store swap entry in pte_low and 0 in pte_high,
+ * which gives up 25 bits available for swap offset.
+ */
+#define __swp_type(x)		((x).val & 0x1f)
+#define __swp_offset(x) 	((((x).val >> 5) & 0x1) | \
+				 (((x).val >> 6) & 0xe) | \
+				 (((x).val >> 11) << 4))
+#define __swp_entry(type,offset) \
+		((swp_entry_t) {((type) & 0x1f ) | \
+				(((offset) & 0x1) << 5) | \
+				(((offset) & 0xe) << 6) | \
+				(((offset) >> 4 ) << 11)})
+#else
 /* Swap entries must have VALID and GLOBAL bits cleared. */
 #define __swp_type(x)		(((x).val >> 8) & 0x1f)
 #define __swp_offset(x)		((x).val >> 13)
 #define __swp_entry(type,offset)	\
 		((swp_entry_t) { ((type) << 8) | ((offset) << 13) })
+#endif /* 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
@@ -202,7 +218,7 @@ pfn_pte(unsigned long pfn, pgprot_t prot
  */
 #define PTE_FILE_MAX_BITS	27
 
-#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32_R1)
+#if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
 	/* fixme */
 #define pte_to_pgoff(_pte) (((_pte).pte_high >> 6) + ((_pte).pte_high & 0x3f))
 #define pgoff_to_pte(off) \
diff --git a/include/asm-mips/pgtable-bits.h b/include/asm-mips/pgtable-bits.h
index 01e76e9..8cbc493 100644
--- a/include/asm-mips/pgtable-bits.h
+++ b/include/asm-mips/pgtable-bits.h
@@ -33,7 +33,7 @@
  * unpredictable things.  The code (when it is written) to deal with
  * this problem will be in the update_mmu_cache() code for the r4k.
  */
-#if defined(CONFIG_CPU_MIPS32_R1) && defined(CONFIG_64BIT_PHYS_ADDR)
+#if defined(CONFIG_CPU_MIPS32) && defined(CONFIG_64BIT_PHYS_ADDR)
 
 #define _PAGE_PRESENT               (1<<6)  /* implemented in software */
 #define _PAGE_READ                  (1<<7)  /* implemented in software */