powerpc/nohash/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE

Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on 32bit and 64bit.

On 64bit, let's use MSB 56 (LSB 7), located right next to the page type. 
On 32bit, let's use LSB 2 to avoid stealing one bit from the swap offset.

There seems to be no real reason why these bits cannot be used for swap
PTEs.  The important part is that _PAGE_PRESENT and _PAGE_HASHPTE remain
0.

While at it, mask the type in __swp_entry() and remove _PAGE_BIT_SWAP_TYPE
from pte-e500.h: while it was used in 64bit code it was ignored in 32bit
code.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Christophe Leroy <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions