MIPS: Add support for XPA.

Add support for extended physical addressing (XPA) so that
32-bit platforms can access equal to or greater than 40 bits
of physical addresses.

NOTE:
      1) XPA and EVA are not the same and cannot be used
         simultaneously.
      2) If you configure your kernel for XPA, the PTEs
         and all address sizes become 64-bit.
      3) Your platform MUST have working HIGHMEM support.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9355/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 14 insertions, 22 deletions

diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index e1fec0237ce2..bffd46ca3694 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -133,7 +133,7 @@ extern void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
 
 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
 
-#define pte_none(pte)           (!(((pte).pte_low | (pte).pte_high) & ~_PAGE_GLOBAL))
+#define pte_none(pte)           (!(((pte).pte_high) & ~_PAGE_GLOBAL))
 #define pte_present(pte)        ((pte).pte_low & _PAGE_PRESENT)
 
 static inline void set_pte(pte_t *ptep, pte_t pte)
@@ -142,16 +142,14 @@ static inline void set_pte(pte_t *ptep, pte_t pte)
         smp_wmb();
         ptep->pte_low = pte.pte_low;
 
-        if (pte.pte_low & _PAGE_GLOBAL) {
+        if (pte.pte_high & _PAGE_GLOBAL) {
                 pte_t *buddy = ptep_buddy(ptep);
                 /*
                  * Make sure the buddy is global too (if it's !none,
                  * it better already be global)
                  */
-                if (pte_none(*buddy)) {
-                        buddy->pte_low  |= _PAGE_GLOBAL;
+                if (pte_none(*buddy))
                         buddy->pte_high |= _PAGE_GLOBAL;
-                }
         }
 }
 
@@ -161,8 +159,8 @@ static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *pt
 
         htw_stop();
         /* Preserve global status for the pair */
-        if (ptep_buddy(ptep)->pte_low & _PAGE_GLOBAL)
-                null.pte_low = null.pte_high = _PAGE_GLOBAL;
+        if (ptep_buddy(ptep)->pte_high & _PAGE_GLOBAL)
+                null.pte_high = _PAGE_GLOBAL;
 
         set_pte_at(mm, addr, ptep, null);
         htw_start();
@@ -242,21 +240,21 @@ static inline int pte_young(pte_t pte)	{ return pte.pte_low & _PAGE_ACCESSED; }
 
 static inline pte_t pte_wrprotect(pte_t pte)
 {
-        pte.pte_low  &= ~(_PAGE_WRITE | _PAGE_SILENT_WRITE);
+        pte.pte_low  &= ~_PAGE_WRITE;
         pte.pte_high &= ~_PAGE_SILENT_WRITE;
         return pte;
 }
 
 static inline pte_t pte_mkclean(pte_t pte)
 {
-        pte.pte_low  &= ~(_PAGE_MODIFIED | _PAGE_SILENT_WRITE);
+        pte.pte_low  &= ~_PAGE_MODIFIED;
         pte.pte_high &= ~_PAGE_SILENT_WRITE;
         return pte;
 }
 
 static inline pte_t pte_mkold(pte_t pte)
 {
-        pte.pte_low  &= ~(_PAGE_ACCESSED | _PAGE_SILENT_READ);
+        pte.pte_low  &= ~_PAGE_ACCESSED;
         pte.pte_high &= ~_PAGE_SILENT_READ;
         return pte;
 }
@@ -264,30 +262,24 @@ static inline pte_t pte_mkold(pte_t pte)
 static inline pte_t pte_mkwrite(pte_t pte)
 {
         pte.pte_low |= _PAGE_WRITE;
-        if (pte.pte_low & _PAGE_MODIFIED) {
-                pte.pte_low  |= _PAGE_SILENT_WRITE;
+        if (pte.pte_low & _PAGE_MODIFIED)
                 pte.pte_high |= _PAGE_SILENT_WRITE;
-        }
         return pte;
 }
 
 static inline pte_t pte_mkdirty(pte_t pte)
 {
         pte.pte_low |= _PAGE_MODIFIED;
-        if (pte.pte_low & _PAGE_WRITE) {
-                pte.pte_low  |= _PAGE_SILENT_WRITE;
+        if (pte.pte_low & _PAGE_WRITE)
                 pte.pte_high |= _PAGE_SILENT_WRITE;
-        }
         return pte;
 }
 
 static inline pte_t pte_mkyoung(pte_t pte)
 {
         pte.pte_low |= _PAGE_ACCESSED;
-        if (pte.pte_low & _PAGE_READ) {
-                pte.pte_low  |= _PAGE_SILENT_READ;
+        if (pte.pte_low & _PAGE_READ)
                 pte.pte_high |= _PAGE_SILENT_READ;
-        }
         return pte;
 }
 #else
@@ -391,10 +383,10 @@ static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
-        pte.pte_low  &= _PAGE_CHG_MASK;
+        pte.pte_low  &= (_PAGE_MODIFIED | _PAGE_ACCESSED | _PFNX_MASK);
         pte.pte_high &= (_PFN_MASK | _CACHE_MASK);
-        pte.pte_low  |= pgprot_val(newprot);
-        pte.pte_high |= pgprot_val(newprot) & ~(_PFN_MASK | _CACHE_MASK);
+        pte.pte_low  |= pgprot_val(newprot) & ~_PFNX_MASK;
+        pte.pte_high |= pgprot_val(newprot) & ~_PFN_MASK;
         return pte;
 }
 #else