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    SubjectRe: [PATCH 01/11] Initialize the mapping of KASan shadow memory
    On Thu, Oct 12, 2017 at 02:42:49AM +0300, Dmitry Osipenko wrote:
    > On 11.10.2017 11:22, Abbott Liu wrote:
    > > +void __init kasan_map_early_shadow(pgd_t *pgdp)
    > > +{
    > > + int i;
    > > + unsigned long start = KASAN_SHADOW_START;
    > > + unsigned long end = KASAN_SHADOW_END;
    > > + unsigned long addr;
    > > + unsigned long next;
    > > + pgd_t *pgd;
    > > +
    > > + for (i = 0; i < PTRS_PER_PTE; i++)
    > > + set_pte_at(&init_mm, KASAN_SHADOW_START + i*PAGE_SIZE,
    > > + &kasan_zero_pte[i], pfn_pte(
    > > + virt_to_pfn(kasan_zero_page),
    > > + __pgprot(_L_PTE_DEFAULT | L_PTE_DIRTY | L_PTE_XN)));
    >
    > Shouldn't all __pgprot's contain L_PTE_MT_WRITETHROUGH ?

    One of the architecture restrictions is that the cache attributes of
    all aliases should match (but there is a specific workaround that
    permits this, provided that the dis-similar mappings aren't accessed
    without certain intervening instructions.)

    Why should it be L_PTE_MT_WRITETHROUGH, and not the same cache
    attributes as the lowmem mapping?

    --
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