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    SubjectRe: [RFC/PATCH] mm: Pass virtual address to [__]p{te,ud,md}_free_tlb()
    On Wed, Jul 15, 2009 at 05:49:47PM +1000, Benjamin Herrenschmidt wrote:
    > Upcoming paches to support the new 64-bit "BookE" powerpc architecture
    > will need to have the virtual address corresponding to PTE page when
    > freeing it, due to the way the HW table walker works.
    > Basically, the TLB can be loaded with "large" pages that cover the whole
    > virtual space (well, sort-of, half of it actually) represented by a PTE
    > page, and which contain an "indirect" bit indicating that this TLB entry
    > RPN points to an array of PTEs from which the TLB can then create direct
    > entries.

    RPN is PFN in ppc speak, right?

    > Thus, in order to invalidate those when PTE pages are deleted,
    > we need the virtual address to pass to tlbilx or tlbivax instructions.

    Interesting arrangement. So are these last level ptes modifieable
    from userspace or something? If not, I wonder if you could manage
    them as another level of pointers with the existing pagetable

    > The old trick of sticking it somewhere in the PTE page struct page sucks
    > too much, the address is almost readily available in all call sites and
    > almost everybody implemets these as macros, so we may as well add the
    > argument everywhere. I added it to the pmd and pud variants for consistency.
    > Signed-off-by: Benjamin Herrenschmidt <>
    > ---
    > I would like to merge the new support that depends on this in 2.6.32,
    > so unless there's major objections, I'd like this to go in early during
    > the merge window. We can sort out separately how to carry the patch
    > around in -next until then since the powerpc tree will have a dependency
    > on it.

    Can't see any problem with that.

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