powerpc/mm: Move around testing of _PAGE_PRESENT in hash code
Instead of adding _PAGE_PRESENT to the access permission mask
in each low level routine independently, we add it once from
hash_page().
We also move the preliminary access check (the racy one before
the PTE is locked) up so it applies to the huge page case. This
duplicates code in __hash_page_huge() which we'll remove in a
subsequent patch to fix a race in there.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 98f262d..40847a9 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -955,6 +955,17 @@
return 1;
}
+ /* Add _PAGE_PRESENT to the required access perm */
+ access |= _PAGE_PRESENT;
+
+ /* Pre-check access permissions (will be re-checked atomically
+ * in __hash_page_XX but this pre-check is a fast path
+ */
+ if (access & ~pte_val(*ptep)) {
+ DBG_LOW(" no access !\n");
+ return 1;
+ }
+
#ifdef CONFIG_HUGETLB_PAGE
if (hugeshift)
return __hash_page_huge(ea, access, vsid, ptep, trap, local,
@@ -967,14 +978,6 @@
DBG_LOW(" i-pte: %016lx %016lx\n", pte_val(*ptep),
pte_val(*(ptep + PTRS_PER_PTE)));
#endif
- /* Pre-check access permissions (will be re-checked atomically
- * in __hash_page_XX but this pre-check is a fast path
- */
- if (access & ~pte_val(*ptep)) {
- DBG_LOW(" no access !\n");
- return 1;
- }
-
/* Do actual hashing */
#ifdef CONFIG_PPC_64K_PAGES
/* If _PAGE_4K_PFN is set, make sure this is a 4k segment */