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    SubjectRe: [PATCH v3 07/33] nds32: MMU initialization
    On Mon, Dec 18, 2017 at 07:21:30PM +0800, Greentime Hu wrote:
    > Hi, Guo Ren:
    >
    > 2017-12-18 17:08 GMT+08:00 Guo Ren <ren_guo@c-sky.com>:
    > > Hi Greentime,
    > >
    > > On Fri, Dec 08, 2017 at 05:11:50PM +0800, Greentime Hu wrote:
    > > [...]
    > >>
    > >> diff --git a/arch/nds32/mm/highmem.c b/arch/nds32/mm/highmem.c
    > > [...]
    > >> +void *kmap(struct page *page)
    > >> +{
    > >> + unsigned long vaddr;
    > >> + might_sleep();
    > >> + if (!PageHighMem(page))
    > >> + return page_address(page);
    > >> + vaddr = (unsigned long)kmap_high(page);
    > > Here should invalid the cpu_mmu_tlb's entry, Or invalid it in the
    > > set_pte().
    > >
    > > eg:
    > > vaddr0 = kmap(page0)
    > > *vaddr0 = val0 //It will cause tlb-miss, and hard-refill to MMU-tlb
    > > kunmap(page0)
    > > vaddr1 = kmap(page1) // Mostly vaddr1 = vaddr0
    > > val = vaddr1; //No tlb-miss and it will get page0's val not page1, because
    > > last expired vaddr0's entry is left in CPU-MMU-tlb.
    > >
    >
    > Thanks.
    > I will add __nds32__tlbop_inv(vaddr); to invalidate this mapping
    > before retrun vaddr.

    Sorry, perhaps I'm wrong. See
    kmap->kmap_high->map_new_virtual->get_next_pkmap_nr(color).

    Seems pkmap will return the vaddr by vaddr + 1 until
    no_more_pkmaps(), and then flush_all_zero_pkmaps.
    Just kmap_atomic need it, and you've done.

    But I don't know why mips need flush_tlb_one in
    arch/mips/mm/highmem.c:kmap(). VIPT? but kmap give the get_pkmap_color
    for aliasing.

    Best Regards
    Guo Ren

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