feat: add Platform::map_shared and wire memory delegation to page mapping

crates/platform/src/lib.rs

@@ -2,8 +2,10 @@
 
 use domain::{memory::MemoryRegion, thread::SavedContext};
 use types::{
-    address::{EntryPoint, StackPointer},
+    address::{EntryPoint, PhysicalAddress, StackPointer},
+    bounded::PageCount,
     id::{CoreId, IrqId, ProcessId},
+    permission::PermissionSet,
     time::{Ticks, TimerDuration},
 };
 
@@ -20,4 +22,11 @@ pub trait Platform {
     fn send_ipi(&mut self, target: CoreId);
     fn core_id(&self) -> CoreId;
     fn num_cores(&self) -> u8;
+    fn map_shared(
+        &mut self,
+        process: ProcessId,
+        base: PhysicalAddress,
+        size: PageCount,
+        permissions: PermissionSet,
+    );
 }