powerpc/mm: Allow platforms to redefine some helpers

The 40xx defines _PAGE_HWWRITE while others don't.
The 8xx defines _PAGE_RO instead of _PAGE_RW.
The 8xx defines _PAGE_PRIVILEGED instead of _PAGE_USER.
The 8xx defines _PAGE_HUGE and _PAGE_NA while others don't.

Lets those platforms redefine pte_write(), pte_wrprotect() and
pte_mkwrite() and get _PAGE_RO and _PAGE_HWWRITE off the common
helpers.

Lets the 8xx redefine pte_user(), pte_mkprivileged() and pte_mkuser()
and get rid of _PAGE_PRIVILEGED and _PAGE_USER default values.

Lets the 8xx redefine pte_mkhuge() and get rid of
_PAGE_HUGE default value.

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/nohash/32/pgtable.h

@@ -136,14 +136,12 @@ extern int icache_44x_need_flush;
 #define pte_clear(mm, addr, ptep) \
 	do { pte_update(ptep, ~0, 0); } while (0)
 
+#ifndef pte_mkwrite
 static inline pte_t pte_mkwrite(pte_t pte)
 {
-	pte_basic_t ptev;
-
-	ptev = pte_val(pte) & ~_PAGE_RO;
-	ptev |= _PAGE_RW;
-	return __pte(ptev);
+	return __pte(pte_val(pte) | _PAGE_RW);
 }
+#endif
 
 static inline pte_t pte_mkdirty(pte_t pte)
 {
@@ -155,14 +153,12 @@ static inline pte_t pte_mkyoung(pte_t pte)
 	return __pte(pte_val(pte) | _PAGE_ACCESSED);
 }
 
+#ifndef pte_wrprotect
 static inline pte_t pte_wrprotect(pte_t pte)
 {
-	pte_basic_t ptev;
-
-	ptev = pte_val(pte) & ~(_PAGE_RW | _PAGE_HWWRITE);
-	ptev |= _PAGE_RO;
-	return __pte(ptev);
+	return __pte(pte_val(pte) & ~_PAGE_RW);
 }
+#endif
 
 static inline pte_t pte_mkexec(pte_t pte)
 {

arch/powerpc/include/asm/nohash/32/pte-40x.h

@@ -87,5 +87,21 @@
 #define PAGE_READONLY	__pgprot(_PAGE_BASE | _PAGE_USER)
 #define PAGE_READONLY_X	__pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
 
+#ifndef __ASSEMBLY__
+static inline pte_t pte_wrprotect(pte_t pte)
+{
+	return __pte(pte_val(pte) & ~(_PAGE_RW | _PAGE_HWWRITE));
+}
+
+#define pte_wrprotect pte_wrprotect
+
+static inline pte_t pte_mkclean(pte_t pte)
+{
+	return __pte(pte_val(pte) & ~(_PAGE_DIRTY | _PAGE_HWWRITE));
+}
+
+#define pte_mkclean pte_mkclean
+#endif
+
 #endif /* __KERNEL__ */
 #endif /*  _ASM_POWERPC_NOHASH_32_PTE_40x_H */

arch/powerpc/include/asm/nohash/32/pte-8xx.h

@@ -87,5 +87,56 @@
 #define PAGE_READONLY	__pgprot(_PAGE_BASE | _PAGE_RO)
 #define PAGE_READONLY_X	__pgprot(_PAGE_BASE | _PAGE_RO | _PAGE_EXEC)
 
+#ifndef __ASSEMBLY__
+static inline pte_t pte_wrprotect(pte_t pte)
+{
+	return __pte(pte_val(pte) | _PAGE_RO);
+}
+
+#define pte_wrprotect pte_wrprotect
+
+static inline int pte_write(pte_t pte)
+{
+	return !(pte_val(pte) & _PAGE_RO);
+}
+
+#define pte_write pte_write
+
+static inline pte_t pte_mkwrite(pte_t pte)
+{
+	return __pte(pte_val(pte) & ~_PAGE_RO);
+}
+
+#define pte_mkwrite pte_mkwrite
+
+static inline bool pte_user(pte_t pte)
+{
+	return !(pte_val(pte) & _PAGE_PRIVILEGED);
+}
+
+#define pte_user pte_user
+
+static inline pte_t pte_mkprivileged(pte_t pte)
+{
+	return __pte(pte_val(pte) | _PAGE_PRIVILEGED);
+}
+
+#define pte_mkprivileged pte_mkprivileged
+
+static inline pte_t pte_mkuser(pte_t pte)
+{
+	return __pte(pte_val(pte) & ~_PAGE_PRIVILEGED);
+}
+
+#define pte_mkuser pte_mkuser
+
+static inline pte_t pte_mkhuge(pte_t pte)
+{
+	return __pte(pte_val(pte) | _PAGE_HUGE);
+}
+
+#define pte_mkhuge pte_mkhuge
+#endif
+
 #endif /* __KERNEL__ */
 #endif /*  _ASM_POWERPC_NOHASH_32_PTE_8xx_H */

arch/powerpc/include/asm/nohash/64/pgtable.h

@@ -90,11 +90,7 @@
  */
 #include <asm/nohash/pte-book3e.h>
 
-#define _PAGE_HWWRITE	0
 #define _PAGE_SAO	0
-#define _PAGE_RO 0
-#define _PAGE_NA 0
-#define _PAGE_HUGE 0
 
 #define PTE_RPN_MASK	(~((1UL << PTE_RPN_SHIFT) - 1))
 

arch/powerpc/include/asm/nohash/pgtable.h

@@ -39,10 +39,12 @@
 #ifndef __ASSEMBLY__
 
 /* Generic accessors to PTE bits */
+#ifndef pte_write
 static inline int pte_write(pte_t pte)
 {
-	return (pte_val(pte) & (_PAGE_RW | _PAGE_RO)) != _PAGE_RO;
+	return pte_val(pte) & _PAGE_RW;
 }
+#endif
 static inline int pte_read(pte_t pte)		{ return 1; }
 static inline int pte_dirty(pte_t pte)		{ return pte_val(pte) & _PAGE_DIRTY; }
 static inline int pte_special(pte_t pte)	{ return pte_val(pte) & _PAGE_SPECIAL; }
@@ -84,10 +86,12 @@ static inline bool pte_hw_valid(pte_t pte)
  * and PTE_64BIT, PAGE_KERNEL_X contains _PAGE_BAP_SR which is also in
  * _PAGE_USER.  Need to explicitly match _PAGE_BAP_UR bit in that case too.
  */
+#ifndef pte_user
 static inline bool pte_user(pte_t pte)
 {
-	return (pte_val(pte) & (_PAGE_USER | _PAGE_PRIVILEGED)) == _PAGE_USER;
+	return (pte_val(pte) & _PAGE_USER) == _PAGE_USER;
 }
+#endif
 
 /*
  * We only find page table entry in the last level
@@ -127,10 +131,12 @@ static inline pte_t pte_exprotect(pte_t pte)
 	return __pte(pte_val(pte) & ~_PAGE_EXEC);
 }
 
+#ifndef pte_mkclean
 static inline pte_t pte_mkclean(pte_t pte)
 {
-	return __pte(pte_val(pte) & ~(_PAGE_DIRTY | _PAGE_HWWRITE));
+	return __pte(pte_val(pte) & ~_PAGE_DIRTY);
 }
+#endif
 
 static inline pte_t pte_mkold(pte_t pte)
 {
@@ -147,20 +153,26 @@ static inline pte_t pte_mkspecial(pte_t pte)
 	return __pte(pte_val(pte) | _PAGE_SPECIAL);
 }
 
+#ifndef pte_mkhuge
 static inline pte_t pte_mkhuge(pte_t pte)
 {
-	return __pte(pte_val(pte) | _PAGE_HUGE);
+	return __pte(pte_val(pte));
 }
+#endif
 
+#ifndef pte_mkprivileged
 static inline pte_t pte_mkprivileged(pte_t pte)
 {
-	return __pte((pte_val(pte) & ~_PAGE_USER) | _PAGE_PRIVILEGED);
+	return __pte(pte_val(pte) & ~_PAGE_USER);
 }
+#endif
 
+#ifndef pte_mkuser
 static inline pte_t pte_mkuser(pte_t pte)
 {
-	return __pte((pte_val(pte) & ~_PAGE_PRIVILEGED) | _PAGE_USER);
+	return __pte(pte_val(pte) | _PAGE_USER);
 }
+#endif
 
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {

arch/powerpc/include/asm/pte-common.h

@@ -5,36 +5,12 @@
  * Some bits are only used on some cpu families... Make sure that all
  * the undefined gets a sensible default
  */
-#ifndef _PAGE_HWWRITE
-#define _PAGE_HWWRITE	0
-#endif
 #ifndef _PAGE_COHERENT
 #define _PAGE_COHERENT	0
 #endif
 #ifndef _PAGE_WRITETHRU
 #define _PAGE_WRITETHRU	0
 #endif
-/* _PAGE_RO and _PAGE_RW shall not be defined at the same time */
-#ifndef _PAGE_RO
-#define _PAGE_RO 0
-#else
-#define _PAGE_RW 0
-#endif
-
-/* At least one of _PAGE_PRIVILEGED or _PAGE_USER must be defined */
-#ifndef _PAGE_PRIVILEGED
-#define _PAGE_PRIVILEGED 0
-#else
-#ifndef _PAGE_USER
-#define _PAGE_USER 0
-#endif
-#endif
-#ifndef _PAGE_NA
-#define _PAGE_NA 0
-#endif
-#ifndef _PAGE_HUGE
-#define _PAGE_HUGE 0
-#endif
 
 /* Location of the PFN in the PTE. Most 32-bit platforms use the same
  * as _PAGE_SHIFT here (ie, naturally aligned).