From 24032a9edde906693398798431a7d3dced95851b Mon Sep 17 00:00:00 2001
From: Erin <erin@hashbang.sh>
Date: Sun, 4 Jun 2017 15:53:45 -0500
Subject: [PATCH] memory::paging: add a struct to own the P4 table, make Page
 Clone+Copy

---
 src/arch/x86_64/memory/paging/mod.rs | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/arch/x86_64/memory/paging/mod.rs b/src/arch/x86_64/memory/paging/mod.rs
index 5846a74..7cd63be 100644
--- a/src/arch/x86_64/memory/paging/mod.rs
+++ b/src/arch/x86_64/memory/paging/mod.rs
@@ -3,11 +3,16 @@
 //! Extremely ripped off from Phil Oppermann's tutorials, because I don't feel like writing
 //! a paging system off the top of my head today.
 
+use core::ptr::Unique;
 use super::PAGE_SIZE;
+use super::{Frame, FrameAllocator};
 
 mod entry;
 mod table;
 
+use self::entry::*;
+use self::table::{Table, Level4};
+
 /// Upper bound on entries per page table
 const ENTRY_COUNT: usize = 512;
 
@@ -15,7 +20,23 @@ const ENTRY_COUNT: usize = 512;
 pub type PhysicalAddress = usize;
 pub type VirtualAddress = usize;
 
-/// A representation of a virtual page
+/// Owns the top-level active page table (P4).
+pub struct ActivePageTable {
+    p4: Unique<Table<Level4>>,
+}
+
+impl ActivePageTable {
+    /// There **must** be ***only one*** ActivePageTable instance.
+    /// Since we cannot guarantee this trivially, the constructor is unsafe.
+    pub unsafe fn new() -> ActivePageTable {
+        ActivePageTable {
+            p4: Unique::new(table::P4),
+        }
+    }
+}
+
+/// A representation of a virtual page.
+#[derive(Clone, Copy, Debug)]
 pub struct Page {
     index: usize,
 }