mm: enhance region_is_ram() to region_intersects()
region_is_ram() is used to prevent the establishment of aliased mappings to physical "System RAM" with incompatible cache settings. However, it uses "-1" to indicate both "unknown" memory ranges (ranges not described by platform firmware) and "mixed" ranges (where the parameters describe a range that partially overlaps "System RAM"). Fix this up by explicitly tracking the "unknown" vs "mixed" resource cases and returning REGION_INTERSECTS, REGION_MIXED, or REGION_DISJOINT. This re-write also adds support for detecting when the requested region completely eclipses all of a resource. Note, the implementation treats overlaps between "unknown" and the requested memory type as REGION_INTERSECTS. Finally, other memory types can be passed in by name, for now the only usage "System RAM". Suggested-by:Luis R. Rodriguez <mcgrof@suse.com> Reviewed-by:
Toshi Kani <toshi.kani@hp.com> Signed-off-by:
Dan Williams <dan.j.williams@intel.com>
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