powerpc/nohash: Add _PAGE_WRITE to supplement _PAGE_RW

Several places, _PAGE_RW maps to write permission and don't
always imply read. To make it more clear, do as book3s/64 in
commit c7d54842deb1 ("powerpc/mm: Use _PAGE_READ to indicate
Read access") and use _PAGE_WRITE when more relevant.

For the time being _PAGE_WRITE is equivalent to _PAGE_RW but that
will change when _PAGE_READ gets added in following patches.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/1f79b88db54d030ada776dc9845e0e88345bfc28.1695659959.git.christophe.leroy@csgroup.eu

6 files changed, 15 insertions, 4 deletions

diff --git a/arch/powerpc/include/asm/nohash/32/pte-40x.h b/arch/powerpc/include/asm/nohash/32/pte-40x.h
index 0b4e5f8ce3e8..e28ef0f5781e 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-40x.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-40x.h
@@ -49,6 +49,8 @@
 #define _PAGE_EXEC	0x200	/* hardware: EX permission */
 #define _PAGE_ACCESSED	0x400	/* software: R: page referenced */
 
+#define _PAGE_WRITE	_PAGE_RW
+
 /* No page size encoding in the linux PTE */
 #define _PAGE_PSIZE		0
 
diff --git a/arch/powerpc/include/asm/nohash/32/pte-44x.h b/arch/powerpc/include/asm/nohash/32/pte-44x.h
index b7ed13cee137..fc0c075006ea 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-44x.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-44x.h
@@ -75,6 +75,8 @@
 #define _PAGE_NO_CACHE	0x00000400		/* H: I bit */
 #define _PAGE_WRITETHRU	0x00000800		/* H: W bit */
 
+#define _PAGE_WRITE	_PAGE_RW
+
 /* No page size encoding in the linux PTE */
 #define _PAGE_PSIZE		0
 
diff --git a/arch/powerpc/include/asm/nohash/32/pte-85xx.h b/arch/powerpc/include/asm/nohash/32/pte-85xx.h
index 16451df5ddb0..462acf69e302 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-85xx.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-85xx.h
@@ -31,6 +31,8 @@
 #define _PAGE_WRITETHRU	0x00400	/* H: W bit */
 #define _PAGE_SPECIAL	0x00800 /* S: Special page */
 
+#define _PAGE_WRITE	_PAGE_RW
+
 #define _PAGE_KERNEL_RO		0
 #define _PAGE_KERNEL_ROX	_PAGE_EXEC
 #define _PAGE_KERNEL_RW		(_PAGE_DIRTY | _PAGE_RW)
diff --git a/arch/powerpc/include/asm/nohash/64/pgtable.h b/arch/powerpc/include/asm/nohash/64/pgtable.h
index 36b9bad428cc..2202c78730e8 100644
--- a/arch/powerpc/include/asm/nohash/64/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
@@ -149,7 +149,7 @@ static inline void p4d_set(p4d_t *p4dp, unsigned long val)
 static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
 					   unsigned long addr, pte_t *ptep)
 {
-	pte_update(mm, addr, ptep, _PAGE_RW, 0, 1);
+	pte_update(mm, addr, ptep, _PAGE_WRITE, 0, 1);
 }
 
 #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index 942f46e86b4b..9a91efa6455b 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -84,7 +84,7 @@ static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
 static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
 				      pte_t *ptep)
 {
-	pte_update(mm, addr, ptep, _PAGE_RW, 0, 0);
+	pte_update(mm, addr, ptep, _PAGE_WRITE, 0, 0);
 }
 #endif
 #define __HAVE_ARCH_PTEP_SET_WRPROTECT
@@ -122,6 +122,9 @@ static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
 #ifndef pte_mkwrite_novma
 static inline pte_t pte_mkwrite_novma(pte_t pte)
 {
+	/*
+	 * write implies read, hence set both
+	 */
 	return __pte(pte_val(pte) | _PAGE_RW);
 }
 #endif
@@ -139,7 +142,7 @@ static inline pte_t pte_mkyoung(pte_t pte)
 #ifndef pte_wrprotect
 static inline pte_t pte_wrprotect(pte_t pte)
 {
-	return __pte(pte_val(pte) & ~_PAGE_RW);
+	return __pte(pte_val(pte) & ~_PAGE_WRITE);
 }
 #endif
 
@@ -153,7 +156,7 @@ static inline pte_t pte_mkexec(pte_t pte)
 #ifndef pte_write
 static inline int pte_write(pte_t pte)
 {
-	return pte_val(pte) & _PAGE_RW;
+	return pte_val(pte) & _PAGE_WRITE;
 }
 #endif
 #ifndef pte_read
diff --git a/arch/powerpc/include/asm/nohash/pte-e500.h b/arch/powerpc/include/asm/nohash/pte-e500.h
index 9f9e3f02d414..b775c7d465a4 100644
--- a/arch/powerpc/include/asm/nohash/pte-e500.h
+++ b/arch/powerpc/include/asm/nohash/pte-e500.h
@@ -55,6 +55,8 @@
 #define _PAGE_KERNEL_ROX	(_PAGE_BAP_SR | _PAGE_BAP_SX)
 #define _PAGE_USER		(_PAGE_BAP_UR | _PAGE_BAP_SR) /* Can be read */
 
+#define _PAGE_WRITE	_PAGE_RW
+
 #define _PAGE_SPECIAL	_PAGE_SW0
 
 /* Base page size */