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| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2010-07-23 08:53:23 +1000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2010-07-23 08:53:23 +1000 |
| commit | ca91e6c09d656c6deb1f2bc5d57186c718106aa5 (patch) | |
| tree | a8d30759b6fac5616691b7a4a94222ab371d2bd6 | |
| parent | b1623e7eb280f853f60338c7bb68bd3f3a970205 (diff) | |
| download | linux-3.10-ca91e6c09d656c6deb1f2bc5d57186c718106aa5.tar.gz linux-3.10-ca91e6c09d656c6deb1f2bc5d57186c718106aa5.tar.bz2 linux-3.10-ca91e6c09d656c6deb1f2bc5d57186c718106aa5.zip | |
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>
| -rw-r--r-- | arch/powerpc/mm/hash_low_64.S | 9 | ||||
| -rw-r--r-- | arch/powerpc/mm/hash_utils_64.c | 19 |
2 files changed, 11 insertions, 17 deletions
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 */ |