From ca91e6c09d656c6deb1f2bc5d57186c718106aa5 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Fri, 23 Jul 2010 08:53:23 +1000 Subject: 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 --- arch/powerpc/mm/hash_low_64.S | 9 --------- arch/powerpc/mm/hash_utils_64.c | 19 +++++++++++-------- 2 files changed, 11 insertions(+), 17 deletions(-) (limited to 'arch') diff --git a/arch/powerpc/mm/hash_low_64.S b/arch/powerpc/mm/hash_low_64.S index a719f53921a..3079f6b44cf 100644 --- a/arch/powerpc/mm/hash_low_64.S +++ b/arch/powerpc/mm/hash_low_64.S @@ -68,9 +68,6 @@ _GLOBAL(__hash_page_4K) std r8,STK_PARM(r8)(r1) std r9,STK_PARM(r9)(r1) - /* Add _PAGE_PRESENT to access */ - ori r4,r4,_PAGE_PRESENT - /* Save non-volatile registers. * r31 will hold "old PTE" * r30 is "new PTE" @@ -347,9 +344,6 @@ _GLOBAL(__hash_page_4K) std r8,STK_PARM(r8)(r1) std r9,STK_PARM(r9)(r1) - /* Add _PAGE_PRESENT to access */ - ori r4,r4,_PAGE_PRESENT - /* Save non-volatile registers. * r31 will hold "old PTE" * r30 is "new PTE" @@ -687,9 +681,6 @@ _GLOBAL(__hash_page_64K) std r8,STK_PARM(r8)(r1) std r9,STK_PARM(r9)(r1) - /* Add _PAGE_PRESENT to access */ - ori r4,r4,_PAGE_PRESENT - /* Save non-volatile registers. * r31 will hold "old PTE" * r30 is "new PTE" diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index 98f262de558..40847a9dd6d 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -955,6 +955,17 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap) 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 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap) 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 */ -- cgit v1.2.3