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>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 17 insertions, 8 deletions

diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
index c6b8b944120c..995e8b34efd0 100644
--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h
@@ -296,12 +296,23 @@ 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
@@ -318,9 +329,8 @@ 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);                           \
         }                                                               \
@@ -331,9 +341,8 @@ 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);                           \
         }                                                               \