mm: Add arch hooks for saving/restoring tags

Arm's Memory Tagging Extension (MTE) adds some metadata (tags) to
every physical page, when swapping pages out to disk it is necessary to
save these tags, and later restore them when reading the pages back.

Add some hooks along with dummy implementations to enable the
arch code to handle this.

Three new hooks are added to the swap code:
 * arch_prepare_to_swap() and
 * arch_swap_invalidate_page() / arch_swap_invalidate_area().
One new hook is added to shmem:
 * arch_swap_restore()

Signed-off-by: Steven Price <[email protected]>
[[email protected]: add unlock_page() on the error path]
[[email protected]: dropped the _tags suffix]
Signed-off-by: Catalin Marinas <[email protected]>
Acked-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions