From 25e4df5bae333a06cd2c9b88baf14432652dc9f7 Mon Sep 17 00:00:00 2001 From: Zachary Amsden Date: Sat, 30 Sep 2006 23:29:34 -0700 Subject: [PATCH] [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 Cc: Rusty Russell Cc: Jeremy Fitzhardinge Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-i386/pgtable.h | 41 ++++++++++++++++++++++++++------------ 1 file changed, 28 insertions(+), 13 deletions(-) diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h index 541b3e234335..94c87ff4b5ac 100644 --- 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)