From cea73b3ab9aede168214365d47720d7abafec793 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Mon, 11 Apr 2016 22:14:04 +0200
Subject: [PATCH] Move memory intialization to memory::init function

---
 src/lib.rs        | 25 ++-----------------------
 src/memory/mod.rs | 28 ++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 23 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index a5bcdd2b..f72da1c7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -35,32 +35,11 @@ pub extern "C" fn rust_main(multiboot_information_address: usize) {
     println!("Hello World{}", "!");
 
     let boot_info = unsafe { multiboot2::load(multiboot_information_address) };
-    let memory_map_tag = boot_info.memory_map_tag().expect("Memory map tag required");
-    let elf_sections_tag = boot_info.elf_sections_tag().expect("Elf sections tag required");
-
-    let kernel_start = elf_sections_tag.sections().map(|s| s.addr).min().unwrap();
-    let kernel_end = elf_sections_tag.sections().map(|s| s.addr + s.size).max().unwrap();
-
-    let multiboot_start = multiboot_information_address;
-    let multiboot_end = multiboot_start + (boot_info.total_size as usize);
-
-    println!("kernel start: 0x{:x}, kernel end: 0x{:x}",
-             kernel_start,
-             kernel_end);
-    println!("multiboot start: 0x{:x}, multiboot end: 0x{:x}",
-             multiboot_start,
-             multiboot_end);
-
-    let mut frame_allocator = memory::AreaFrameAllocator::new(kernel_start as usize,
-                                                              kernel_end as usize,
-                                                              multiboot_start,
-                                                              multiboot_end,
-                                                              memory_map_tag.memory_areas());
-
     enable_nxe_bit();
     enable_write_protect_bit();
 
-    memory::remap_the_kernel(&mut frame_allocator, boot_info);
+    // set up guard page and map the heap pages
+    memory::init(boot_info);
 
     use alloc::boxed::Box;
     let heap_test = Box::new(42);
diff --git a/src/memory/mod.rs b/src/memory/mod.rs
index 139b69fb..f4905c03 100644
--- a/src/memory/mod.rs
+++ b/src/memory/mod.rs
@@ -10,12 +10,40 @@
 pub use self::area_frame_allocator::AreaFrameAllocator;
 pub use self::paging::remap_the_kernel;
 use self::paging::PhysicalAddress;
+use multiboot2::BootInformation;
 
 mod area_frame_allocator;
 mod paging;
 
 pub const PAGE_SIZE: usize = 4096;
 
+pub fn init(boot_info: &BootInformation) {
+    let memory_map_tag = boot_info.memory_map_tag().expect(
+        "Memory map tag required");
+    let elf_sections_tag = boot_info.elf_sections_tag().expect(
+        "Elf sections tag required");
+
+    let kernel_start = elf_sections_tag.sections()
+        .filter(|s| s.is_allocated()).map(|s| s.addr).min().unwrap();
+    let kernel_end = elf_sections_tag.sections()
+        .filter(|s| s.is_allocated()).map(|s| s.addr + s.size).max()
+        .unwrap();
+
+    println!("kernel start: {:#x}, kernel end: {:#x}",
+             kernel_start,
+             kernel_end);
+    println!("multiboot start: {:#x}, multiboot end: {:#x}",
+             boot_info.start_address(),
+             boot_info.end_address());
+
+    let mut frame_allocator = AreaFrameAllocator::new(
+        kernel_start as usize, kernel_end as usize,
+        boot_info.start_address(), boot_info.end_address(),
+        memory_map_tag.memory_areas());
+
+    paging::remap_the_kernel(&mut frame_allocator, boot_info);
+}
+
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Frame {
     number: usize,