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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2010-07-23 08:53:23 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2010-07-23 08:53:23 +1000
commitca91e6c09d656c6deb1f2bc5d57186c718106aa5 (patch)
treea8d30759b6fac5616691b7a4a94222ab371d2bd6 /arch
parentb1623e7eb280f853f60338c7bb68bd3f3a970205 (diff)
downloadlinux-2.6.34-ux500-ca91e6c09d656c6deb1f2bc5d57186c718106aa5.tar.gz
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/mm/hash_low_64.S9
-rw-r--r--arch/powerpc/mm/hash_utils_64.c19
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 */