powerpc: Fixes for CONFIG_PTE_64BIT for SMP support

There are some minor issues with support 64-bit PTEs on a 32-bit processor
when dealing with SMP.

* We need to order the stores in set_pte_at to make sure the flag word
  is set second.
* Change pte_clear to use pte_update so only the flag word is cleared
* Added a WARN_ON to set_pte_at to ensure the pte isn't present for
  the 64-bit pte/SMP case (to ensure our assumption of this fact).

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Becky Bruce <becky.bruce@freescale.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/highmem.h b/arch/powerpc/include/asm/highmem.h
index 5d99b6489d56..91c589520c0a 100644
--- a/arch/powerpc/include/asm/highmem.h
+++ b/arch/powerpc/include/asm/highmem.h
@@ -84,7 +84,7 @@ static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgpro
 #ifdef CONFIG_DEBUG_HIGHMEM
         BUG_ON(!pte_none(*(kmap_pte-idx)));
 #endif
-        set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
+        __set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
         flush_tlb_page(NULL, vaddr);
 
         return (void*) vaddr;