From f897b6b09ea7d0f33d0806a13affd6d7c5c7d380 Mon Sep 17 00:00:00 2001
From: Erin <erin@hashbang.sh>
Date: Sun, 4 Jun 2017 17:49:50 -0500
Subject: [PATCH] memory::paging: add an InactivePageTable struct

---
 src/arch/x86_64/memory/paging/mod.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/arch/x86_64/memory/paging/mod.rs b/src/arch/x86_64/memory/paging/mod.rs
index e44847b..d293fb4 100644
--- a/src/arch/x86_64/memory/paging/mod.rs
+++ b/src/arch/x86_64/memory/paging/mod.rs
@@ -90,11 +90,26 @@ impl ActivePageTable {
     }
 }
 
+/// Owns an inactive P4 table.
+pub struct InactivePageTable {
+    p4_frame: Frame,
+}
 
+impl InactivePageTable {
+    pub fn new(frame: Frame, active_table: &mut ActivePageTable, temporary_page: &mut TemporaryPage)
+            -> InactivePageTable {
+        {
+            let table = temporary_page.map_table_frame(frame.clone(), active_table);
 
+            // zero the new inactive page table
+            table.zero();
 
+            // set up a recursive mapping for this table
+            table[511].set(frame.clone(), PRESENT | WRITABLE);
         }
+        temporary_page.unmap(active_table);
 
+        InactivePageTable { p4_frame: frame }
     }
 }