Fix page fault by mapping the complete heap

src/memory/mod.rs

@@ -43,7 +43,18 @@ pub fn init(boot_info: &BootInformation) {
         boot_info.start_address(), boot_info.end_address(),
         memory_map_tag.memory_areas());
 
-    paging::remap_the_kernel(&mut frame_allocator, boot_info);
+    let mut active_table = paging::remap_the_kernel(&mut frame_allocator,
+        boot_info);
+
+    use self::paging::{Page, WRITABLE};
+    use bump_allocator::{HEAP_START, HEAP_SIZE};
+
+    let heap_start_page = Page::containing_address(HEAP_START);
+    let heap_end_page = Page::containing_address(HEAP_START + HEAP_SIZE-1);
+
+    for page in Page::range_inclusive(heap_start_page, heap_end_page) {
+        active_table.map(page, paging::WRITABLE, &mut frame_allocator);
+    }
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]

src/memory/paging/mod.rs

@@ -24,7 +24,7 @@ const ENTRY_COUNT: usize = 512;
 pub type PhysicalAddress = usize;
 pub type VirtualAddress = usize;
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Page {
     number: usize,
 }
@@ -53,6 +53,32 @@ impl Page {
     fn p1_index(&self) -> usize {
         (self.number >> 0) & 0o777
     }
+
+    pub fn range_inclusive(start: Page, end: Page) -> PageIter {
+        PageIter {
+            start: start,
+            end: end,
+        }
+    }
+}
+
+pub struct PageIter {
+    start: Page,
+    end: Page,
+}
+
+impl Iterator for PageIter {
+    type Item = Page;
+
+    fn next(&mut self) -> Option<Page> {
+        if self.start <= self.end {
+            let page = self.start;
+            self.start.number += 1;
+            Some(page)
+        } else {
+            None
+        }
+    }
 }
 
 pub struct ActivePageTable {
@@ -142,6 +168,7 @@ impl InactivePageTable {
 }
 
 pub fn remap_the_kernel<A>(allocator: &mut A, boot_info: &BootInformation)
+    -> ActivePageTable
     where A: FrameAllocator
 {
     let mut temporary_page = TemporaryPage::new(Page { number: 0xcafebabe }, allocator);
@@ -196,4 +223,6 @@ pub fn remap_the_kernel<A>(allocator: &mut A, boot_info: &BootInformation)
     let old_p4_page = Page::containing_address(old_table.p4_frame.start_address());
     active_table.unmap(old_p4_page, allocator);
     println!("guard page at {:#x}", old_p4_page.start_address());
+
+    active_table
 }