• Vineet Gupta's avatar
    ARC: [mm] Aliasing VIPT dcache support 2/4 · 4102b533
    Vineet Gupta authored
    This is the meat of the series which prevents any dcache alias creation
    by always keeping the U and K mapping of a page congruent.
    If a mapping already exists, and other tries to access the page, prev
    one is flushed to physical page (wback+inv)
    
    Essentially flush_dcache_page()/copy_user_highpage() create K-mapping
    of a page, but try to defer flushing, unless U-mapping exist.
    When page is actually mapped to userspace, update_mmu_cache() flushes
    the K-mapping (in certain cases this can be optimised out)
    
    Additonally flush_cache_mm(), flush_cache_range(), flush_cache_page()
    handle the puring of stale userspace mappings on exit/munmap...
    
    flush_anon_page() handles the existing U-mapping for anon page before
    kernel reads it via the GUP path.
    
    Note that while not complete, this is enough to boot a simple
    dynamically linked Busybox based rootfs
    Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
    4102b533
page.h 3.42 KB