Let's use the newly-free PTE SW bit (58) to add support for uffd-wp.
The standard handlers are implemented for set/test/clear for both pte
and pmd. Additionally we must also track the uffd-wp state as a pte swp
bit, so use a free swap pte bit (3).
Acked-by: Peter Xu <peterx@xxxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
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