dma: deallocate

Signed-off-by: Anhad Singh <[email protected]>

src/aero_kernel/src/main.rs

@@ -47,6 +47,7 @@
     const_ptr_is_null, // https://github.com/rust-lang/rust/issues/74939
     trait_upcasting, // https://github.com/rust-lang/rust/issues/65991
     naked_functions, // https://github.com/rust-lang/rust/issues/32408
+    strict_provenance
 )]
 #![deny(trivial_numeric_casts, unused_allocation)]
 #![test_runner(crate::tests::test_runner)]

src/aero_kernel/src/mem/paging/frame.rs

@@ -77,6 +77,13 @@ impl LockedFrameAllocator {
             .call_once(|| Mutex::new(GlobalFrameAllocator::new(memory_map)));
     }
 
+    pub fn dealloc(&self, addr: PhysAddr, size_bytes: usize) {
+        let order = order_from_size(size_bytes as u64);
+
+        let mut allocator = self.0.get().unwrap().lock_irq();
+        allocator.deallocate_frame_inner(addr, order);
+    }
+
     pub fn alloc(&self, size_bytes: usize) -> Option<PhysAddr> {
         let order = order_from_size(size_bytes as u64);
 

src/aero_kernel/src/utils/dma.rs

@@ -30,7 +30,6 @@ pub struct DmaAllocator;
 // the data using the ISA or PCI system bus (which carry physical addresses).
 unsafe impl Allocator for DmaAllocator {
     fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
-        // XXX: The DMA buffer must be aligned to a page boundary.
         let size_bytes = layout.size();
 
         let phys = FRAME_ALLOCATOR.alloc_zeroed(size_bytes).ok_or(AllocError)?;
@@ -41,7 +40,14 @@ unsafe impl Allocator for DmaAllocator {
         Ok(NonNull::slice_from_raw_parts(ptr, size_bytes))
     }
 
-    unsafe fn deallocate(&self, _ptr: NonNull<u8>, _layout: Layout) {}
+    unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
+        let size_bytes = layout.size();
+
+        let addr: usize = ptr.addr().into();
+        let addr = VirtAddr::new(addr as u64);
+
+        FRAME_ALLOCATOR.dealloc(addr.as_hhdm_phys(), size_bytes);
+    }
 }
 
 pub type DmaBuffer<T> = Box<T, DmaAllocator>;