00mm5 combine flush accessed dirty.patch
Subsystems (2)
PATCH 4/9 00mm5 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.
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include/asm-i386/pgtable.h +28 -13
@@ -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_FULLstatic inline pte_t ptep_get_and_clear_full (struct mm_struct *mm,unsigned long addr,pte_t *ptep,int full)
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