[PATCH] paravirt: combine flush accessed dirty.patch

Remove ptep_test_and_clear_{dirty|young} from i386, and instead use the
dominating functions, ptep_clear_flush_{dirty|young}.  This allows the TLB
page flush to be contained in the same macro, and allows for an eager
optimization - if reading the PTE initially returned dirty/accessed, we can
assume the fact that no subsequent update to the PTE which cleared accessed /
dirty has occurred, as the only way A/D bits can change without holding the
page table lock is if a remote processor clears them.  This eliminates an
extra branch which came from the generic version of the code, as we know that
no other CPU could have cleared the A/D bit, so the flush will always be
needed.

We still export these two defines, even though we do not actually define
the macros in the i386 code:

 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
 #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY

The reason for this is that the only use of these functions is within the
generic clear_flush functions, and we want a strong guarantee that there
are no other users of these functions, so we want to prevent the generic
code from defining them for us.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
index 541b3e23433571d590f8e79291bb2c21fded9306..94c87ff4b5acbe75ea11f3f1688451d150004fce 100644 (file)
--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h
@@ -262,21 +262,36 @@ 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);
-}
+
+#define __HAVE_ARCH_PTEP_CLEAR_DIRTY_FLUSH
+#define ptep_clear_flush_dirty(vma, address, ptep)                     \
+({                                                                     \
+       int __dirty;                                                    \
+       __dirty = pte_dirty(*(ptep));                                   \
+       if (__dirty) {                                                  \
+               clear_bit(_PAGE_BIT_DIRTY, &(ptep)->pte_low);           \
+               flush_tlb_page(vma, address);                           \
+       }                                                               \
+       __dirty;                                                        \
+})
+
+#define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
+#define ptep_clear_flush_young(vma, address, ptep)                     \
+({                                                                     \
+       int __young;                                                    \
+       __young = pte_young(*(ptep));                                   \
+       if (__young) {                                                  \
+               clear_bit(_PAGE_BIT_ACCESSED, &(ptep)->pte_low);        \
+               flush_tlb_page(vma, address);                           \
+       }                                                               \
+       __young;                                                        \
+})
 
 #define __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
 static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, unsigned long addr, pte_t *ptep, int full)