From 4160cb6d7ea894e17c7bb7b33a5f43f0f789f585 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Tue, 18 Apr 2017 12:00:17 +0200
Subject: [PATCH] Begin creating an ActivePageTable::with function

---
 src/memory/paging/mod.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/memory/paging/mod.rs b/src/memory/paging/mod.rs
index 2aa7e85..25e1e77 100644
--- a/src/memory/paging/mod.rs
+++ b/src/memory/paging/mod.rs
@@ -157,6 +157,23 @@ impl ActivePageTable {
         // TODO free p(1,2,3) table if empty
         //allocator.deallocate_frame(frame);
     }
+
+    pub fn with<F>(&mut self,
+                table: &mut InactivePageTable,
+                f: F)
+        where F: FnOnce(&mut ActivePageTable)
+    {
+        use x86_64::instructions::tlb;
+
+        // overwrite recursive mapping
+        self.p4_mut()[511].set(table.p4_frame.clone(), PRESENT | WRITABLE);
+        tlb::flush_all();
+
+        // execute f in the new context
+        f(self);
+
+        // TODO restore recursive mapping to original p4 table
+    }
 }
 
 pub struct InactivePageTable {