MIPS: Expand __swp_offset() to carry 40 significant bits for 64-bit kernel.
MIPS: Expand __swp_offset() to carry 40 significant bits for 64-bit kernel.

With CONFIG_MIGRATION, the PFN of the migrating pages is stored in
__swp_offset(), so we must have enough bits to store the largest
possible PFN.  OCTEON NUMA systems have 41 bits of physical address
space, so with 4K pages (12-bits), we need at least 29 bits to store
the PFN.

The current width of 24-bits is too narrow, so expand it all the way
out to 40-bits.  This leaves the low order 16 bits as zero which does
not interfere with any of the PTE bits.

Signed-off-by: David Daney <eec15f2dea0e7d114bf41a5bde8a2858b8f3e893@cavium.com>
Cc: 562397917b9a8bf316569a848858b12fb417723f@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9315/
Signed-off-by: Ralf Baechle <92f48d309cda194c8eda36aa8f9ae28c488fa208@linux-mips.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs