Add linked list allocator with automatic resizing

Fix memory leaks in exec
Remove warnings

src/allocator/mod.rs

@@ -0,0 +1,36 @@
+use paging::{ActivePageTable, Page, VirtualAddress};
+use paging::entry::EntryFlags;
+use paging::mapper::MapperFlushAll;
+
+#[cfg(not(feature="slab"))]
+pub use self::linked_list::Allocator;
+
+#[cfg(feature="slab")]
+pub use self::slab::Allocator;
+
+mod linked_list;
+mod slab;
+
+unsafe fn map_heap(active_table: &mut ActivePageTable, offset: usize, size: usize) {
+    let mut flush_all = MapperFlushAll::new();
+
+    let heap_start_page = Page::containing_address(VirtualAddress::new(offset));
+    let heap_end_page = Page::containing_address(VirtualAddress::new(offset + size-1));
+    for page in Page::range_inclusive(heap_start_page, heap_end_page) {
+        let result = active_table.map(page, EntryFlags::PRESENT | EntryFlags::GLOBAL | EntryFlags::WRITABLE | EntryFlags::NO_EXECUTE);
+        flush_all.consume(result);
+    }
+
+    flush_all.flush(active_table);
+}
+
+pub unsafe fn init(active_table: &mut ActivePageTable) {
+    let offset = ::KERNEL_HEAP_OFFSET;
+    let size = ::KERNEL_HEAP_SIZE;
+
+    // Map heap pages
+    map_heap(active_table, offset, size);
+
+    // Initialize global heap
+    Allocator::init(offset, size);
+}