powerpc/mm: Add option for non-atomic PTE updates to ppc64

ppc32 has it already, add it to ppc64 as a preliminary for adding
support for Book3E 64-bit support

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 13 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
index 768e0f08f009..c40db05f21e0 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64.h
@@ -178,6 +178,7 @@ static inline unsigned long pte_update(struct mm_struct *mm,
                                        pte_t *ptep, unsigned long clr,
                                        int huge)
 {
+#ifdef PTE_ATOMIC_UPDATES
         unsigned long old, tmp;
 
         __asm__ __volatile__(
@@ -190,7 +191,10 @@ static inline unsigned long pte_update(struct mm_struct *mm,
         : "=&r" (old), "=&r" (tmp), "=m" (*ptep)
         : "r" (ptep), "r" (clr), "m" (*ptep), "i" (_PAGE_BUSY)
         : "cc" );
-
+#else
+        unsigned long old = pte_val(*ptep);
+        *ptep = __pte(old & ~clr);
+#endif
         /* huge pages use the old page table lock */
         if (!huge)
                 assert_pte_locked(mm, addr);
@@ -278,6 +282,8 @@ static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
         unsigned long bits = pte_val(entry) &
                 (_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW |
                  _PAGE_EXEC | _PAGE_HWEXEC);
+
+#ifdef PTE_ATOMIC_UPDATES
         unsigned long old, tmp;
 
         __asm__ __volatile__(
@@ -290,6 +296,10 @@ static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
         :"=&r" (old), "=&r" (tmp), "=m" (*ptep)
         :"r" (bits), "r" (ptep), "m" (*ptep), "i" (_PAGE_BUSY)
         :"cc");
+#else
+        unsigned long old = pte_val(*ptep);
+        *ptep = __pte(old | bits);
+#endif
 }
 
 #define __HAVE_ARCH_PTE_SAME
diff --git a/arch/powerpc/include/asm/pte-hash64.h b/arch/powerpc/include/asm/pte-hash64.h
index b61b7e4a18de..0419eeb53274 100644
--- a/arch/powerpc/include/asm/pte-hash64.h
+++ b/arch/powerpc/include/asm/pte-hash64.h
@@ -41,6 +41,8 @@
 #define _PTEIDX_SECONDARY       0x8
 #define _PTEIDX_GROUP_IX        0x7
 
+/* Hash table based platforms need atomic updates of the linux PTE */
+#define PTE_ATOMIC_UPDATES      1
 
 #ifdef CONFIG_PPC_64K_PAGES
 #include <asm/pte-hash64-64k.h>