i386: add ptep_test_and_clear_{dirty,young}
David Rientjes [Sun, 6 May 2007 21:49:19 +0000 (14:49 -0700)]
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>

include/asm-i386/pgtable.h

index c6b8b94..995e8b3 100644 (file)
@@ -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);                           \
        }                                                               \