Introducing the hottest library crate in town (libk!)

libk/src/alloc/allocator.rs

@@ -0,0 +1,45 @@
+use linked_list_allocator::LockedHeap;
+use x86_64::{
+    structures::paging::{
+        mapper::MapToError, FrameAllocator, Mapper, Page, PageTableFlags, Size4KiB,
+    },
+    VirtAddr,
+};
+
+/// We are currently using a linked list heap allocator which uses our underlying page allocator.
+pub type FoundryAllocator = LockedHeap;
+
+#[global_allocator]
+/// This is now Rust's global allocator, so we can use stuff requiring heap allocations.
+static ALLOCATOR: FoundryAllocator = FoundryAllocator::empty();
+
+pub const HEAP_START: usize = 0x4444_4444_0000;
+pub const HEAP_SIZE: usize = 1000 * 1024;
+
+/// Sets up the heap using the backing page frame allocator.
+pub fn init_heap(
+    mapper: &mut impl Mapper<Size4KiB>,
+    frame_allocator: &mut impl FrameAllocator<Size4KiB>,
+) -> Result<(), MapToError<Size4KiB>> {
+    let range = {
+        let heap_start = VirtAddr::new(HEAP_START as u64);
+        let heap_end = heap_start + HEAP_SIZE as u64 - 1u64;
+        let heap_start_page = Page::<Size4KiB>::containing_address(heap_start);
+        let heap_end_page = Page::<Size4KiB>::containing_address(heap_end);
+        Page::range_inclusive(heap_start_page, heap_end_page)
+    };
+
+    for page in range {
+        let frame = frame_allocator
+            .allocate_frame()
+            .ok_or(MapToError::FrameAllocationFailed)?;
+        let flags = PageTableFlags::PRESENT | PageTableFlags::WRITABLE;
+        unsafe { mapper.map_to(page, frame, flags, frame_allocator)?.flush() };
+    }
+
+    unsafe {
+        ALLOCATOR.lock().init(HEAP_START as *mut u8, HEAP_SIZE);
+    }
+
+    Ok(())
+}