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Subject[patch -mm 1/2] i386: add ptep_test_and_clear_{dirty,young}
Add ptep_test_and_clear_{dirty,young} to i386.  They advertise that they
have it and there is at least one place where it needs to be called
without the page table lock: to clear the accessed bit on write to
/proc/pid/clear_refs.
ptep_clear_flush_{dirty,young} are updated to use the new functions. The
overall net effect to current users of ptep_clear_flush_{dirty,young} is
that we introduce an additional branch.
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
---
include/asm-i386/pgtable.h | 25 +++++++++++++++++--------
1 files changed, 17 insertions(+), 8 deletions(-)
diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h
@@ -283,12 +283,23 @@ do { \
} \
} while (0)

-/*
- * We don't actually have these, but we want to advertise them so that
- * we can encompass the flush here.
- */
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY
+static inline int ptep_test_and_clear_dirty(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep)
+{
+ if (!pte_dirty(*ptep))
+ return 0;
+ return test_and_clear_bit(_PAGE_BIT_DIRTY, &ptep->pte_low);
+}
+
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
+static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep)
+{
+ if (!pte_young(*ptep))
+ return 0;
+ return test_and_clear_bit(_PAGE_BIT_ACCESSED, &ptep->pte_low);
+}

/*
* Rules for using ptep_establish: the pte MUST be a user pte, and
@@ -305,9 +316,8 @@ do { \
#define ptep_clear_flush_dirty(vma, address, ptep) \
({ \
int __dirty; \
- __dirty = pte_dirty(*(ptep)); \
+ __dirty = ptep_test_and_clear_dirty((vma), (address), (ptep)); \
if (__dirty) { \
- clear_bit(_PAGE_BIT_DIRTY, &(ptep)->pte_low); \
pte_update_defer((vma)->vm_mm, (address), (ptep)); \
flush_tlb_page(vma, address); \
} \
@@ -318,9 +328,8 @@ do { \
#define ptep_clear_flush_young(vma, address, ptep) \
({ \
int __young; \
- __young = pte_young(*(ptep)); \
+ __young = ptep_test_and_clear_young((vma), (address), (ptep)); \
if (__young) { \
- clear_bit(_PAGE_BIT_ACCESSED, &(ptep)->pte_low); \
pte_update_defer((vma)->vm_mm, (address), (ptep)); \
flush_tlb_page(vma, address); \
} \
-
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