ArmPkg/CpuDxe: Expose unified region-to-EFI attribute conversion

In preparation for introducing an implementation of the EFI memory
attributes protocol that is shared between ARM and AArch64, unify the
existing code that converts a page table descriptor into a
EFI_MEMORY_xx bitfield, so it can be called from the generic code.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>

ArmPkg/Drivers/CpuDxe/CpuDxe.h

@@ -126,4 +126,18 @@ SetGcdMemorySpaceAttributes (
   IN UINT64                           Attributes
   );
 
+/**
+  Convert an arch specific set of page attributes into a mask
+  of EFI_MEMORY_xx constants.
+
+  @param  PageAttributes  The set of page attributes.
+
+  @retval The mask of EFI_MEMORY_xx constants.
+
+**/
+UINT64
+RegionAttributeToGcdAttribute (
+  IN UINTN  PageAttributes
+  );
+
 #endif // CPU_DXE_H_