• Zachary Amsden's avatar
    [PATCH] paravirt: combine flush accessed dirty.patch · 25e4df5b
    Zachary Amsden authored
    
    
    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: default avatarZachary 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: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    25e4df5b