• Steven Capper's avatar
    ARM: 8108/1: mm: Introduce {pte,pmd}_isset and {pte,pmd}_isclear · f2950706
    Steven Capper authored
    Long descriptors on ARM are 64 bits, and some pte functions such as
    pte_dirty return a bitwise-and of a flag with the pte value. If the
    flag to be tested resides in the upper 32 bits of the pte, then we run
    into the danger of the result being dropped if downcast.
    
    For example:
    	gather_stats(page, md, pte_dirty(*pte), 1);
    where pte_dirty(*pte) is downcast to an int.
    
    This patch introduces a new macro pte_isset which performs the bitwise
    and, then performs a double logical invert (where needed) to ensure
    predictable downcasting. The logical inverse pte_isclear is also
    introduced.
    
    Equivalent pmd functions for Transparent HugePages have also been
    added.
    Signed-off-by: default avatarSteve Capper <steve.capper@linaro.org>
    Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    f2950706
pgtable.h 11.2 KB