• Russell King's avatar
    MM: Pass a PTE pointer to update_mmu_cache() rather than the PTE itself · 4b3073e1
    Russell King authored
    On VIVT ARM, when we have multiple shared mappings of the same file
    in the same MM, we need to ensure that we have coherency across all
    copies.  We do this via make_coherent() by making the pages
    uncacheable.
    
    This used to work fine, until we allowed highmem with highpte - we
    now have a page table which is mapped as required, and is not available
    for modification via update_mmu_cache().
    
    Ralf Beache suggested getting rid of the PTE value passed to
    update_mmu_cache():
    
      On MIPS update_mmu_cache() calls __update_tlb() which walks pagetables
      to construct a pointer to the pte again.  Passing a pte_t * is much
      more elegant.  Maybe we might even replace the pte argument with the
      pte_t?
    
    Ben Herrenschmidt would also like the pte pointer for PowerPC:
    
      Passing the ptep in there is exactly what I want.  I want that
      -instead- of the PTE value, because I have issue on some ppc cases,
      for I$/D$ coherency, where set_pte_at() may decide to mask out the
      _PAGE_EXEC.
    
    So, pass in the mapped page table pointer into update_mmu_cache(), and
    remove the PTE value, updating all implementations and call sites to
    suit.
    
    Includes a fix from Stephen Rothwell:
    
      sparc: fix fallout from update_mmu_cache API change
    Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
    Acked-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    4b3073e1
pgtable_64.h 4.49 KB