- implemented a custom allocator (fixed size block) with a fallback (linked list allocator) for larger block sizes

- apic code still not working (commented out, check lib.rs)

libk/src/drivers/kalloc/allocator.rs

@@ -1,15 +1,15 @@
 use linked_list_allocator::LockedHeap;
+use spin::{Mutex, MutexGuard};
 use x86_64::structures::paging::{
     mapper::MapToError,
     Size4KiB,
 };
+use crate::drivers::kalloc::foundry_kalloc::FoundryAllocator;
 
 /// 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();
+static ALLOCATOR: Locked<FoundryAllocator> = Locked::new(FoundryAllocator::new());
 
 pub const HEAP_START: usize = 0x4444_4444_0000;
 pub const HEAP_SIZE: usize = 1024 * 1024 * 1024;
@@ -19,8 +19,24 @@ pub fn init_heap() -> Result<(), MapToError<Size4KiB>> {
     // code to allocate frames is now done in the page fault interrupt handler!
 
     unsafe {
-        ALLOCATOR.lock().init(HEAP_START as *mut u8, HEAP_SIZE);
+        ALLOCATOR.lock().init(HEAP_START, HEAP_SIZE);
     }
 
     Ok(())
 }
+
+pub struct Locked<T> {
+    inner: Mutex<T>,
+}
+
+impl<T> Locked<T> {
+    pub const fn new(inner: T) -> Self {
+        Locked {
+            inner: Mutex::new(inner)
+        }
+    }
+
+    pub fn lock(&self) -> MutexGuard<T> {
+        self.inner.lock()
+    }
+}

libk/src/drivers/kalloc/foundry_kalloc.rs

@@ -0,0 +1,231 @@
+use alloc::collections::LinkedList;
+use core::alloc::{GlobalAlloc, Layout};
+use core::{mem, ptr};
+use core::ptr::NonNull;
+use crate::drivers::kalloc::allocator::Locked;
+const BLOCK_SIZES: &[usize] = &[8, 16, 32, 64, 128, 256, 512, 1024, 2048];
+
+struct ListNode {
+    next: Option<&'static mut ListNode>,
+}
+
+pub struct FoundryAllocator {
+    list_heads: [Option<&'static mut ListNode>; BLOCK_SIZES.len()],
+    fallback: Locked<FoundryFallbackAllocator>,
+}
+
+impl Default for FoundryAllocator {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl FoundryAllocator {
+    pub const fn new() -> Self {
+        const EMPTY: Option<&'static mut ListNode> = None;
+        Self {
+            list_heads: [EMPTY; BLOCK_SIZES.len()],
+            fallback: Locked::new(FoundryFallbackAllocator::new()),
+        }
+    }
+    pub unsafe fn init(&mut self, heap_start: usize, heap_size: usize) { unsafe {
+        self.fallback.lock().init(heap_start, heap_size);
+    }}
+
+    unsafe fn fallback_alloc(&mut self, layout: Layout) -> *mut u8 { unsafe {
+        self.fallback.alloc(layout)
+    }}
+
+    fn block_size(&self, layout: &Layout) -> Option<usize> {
+        let required_block_size = layout.size().max(layout.align());
+        BLOCK_SIZES.iter().position(|&s| s >= required_block_size)
+    }
+}
+
+unsafe impl GlobalAlloc for Locked<FoundryAllocator> {
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        let mut allocator = self.lock();
+
+        match allocator.block_size(&layout) {
+            Some(index) => {
+                match allocator.list_heads[index].take() {
+                    Some(node) => {
+                        allocator.list_heads[index] = node.next.take();
+                        node as *mut ListNode as *mut u8
+                    }
+                    None => {
+                        // no block exists in list => allocate new block
+                        let block_size = BLOCK_SIZES[index];
+                        // only works if all block sizes are a power of 2
+                        let block_align = block_size;
+                        let layout = Layout::from_size_align(block_size, block_align)
+                            .unwrap();
+                        unsafe { allocator.fallback_alloc(layout) }
+                    }
+                }
+            }
+            None => unsafe { allocator.fallback_alloc(layout) },
+        }
+    }
+
+
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        let mut allocator = self.lock();
+        match allocator.block_size(&layout) {
+            Some(idx) => {
+                let new_node = ListNode {
+                    next: allocator.list_heads[idx].take(),
+                };
+
+                let new_ptr = ptr as *mut ListNode;
+                unsafe { new_ptr.write(new_node) };
+                allocator.list_heads[idx] = Some( unsafe { &mut *new_ptr });
+            }
+            None => {;
+                unsafe { allocator.fallback.dealloc(ptr, layout) };
+            }
+        }
+    }
+}
+
+struct FallbackListNode {
+    size: usize,
+    next: Option<&'static mut FallbackListNode>,
+}
+
+impl FallbackListNode {
+    const fn new(size: usize) -> Self {
+        Self {
+            size,
+            next: None,
+        }
+    }
+
+    fn start_addr(&self) -> usize {
+        self as *const Self as usize
+    }
+
+    fn end_addr(&self) -> usize {
+        self.start_addr() + self.size
+    }
+}
+
+pub struct FoundryFallbackAllocator {
+    head: FallbackListNode,
+}
+
+impl FoundryFallbackAllocator {
+    pub const fn new() -> Self {
+        Self {
+            head: FallbackListNode::new(0),
+        }
+    }
+
+    pub unsafe fn init(&mut self, heap_start: usize, heap_size: usize) {
+        unsafe { self.add_region(heap_start, heap_size) };
+    }
+
+    unsafe fn add_region(&mut self, addr: usize, size: usize) { unsafe {
+        let mut node = FallbackListNode::new(size);
+        node.next = self.head.next.take();
+        let node_ptr = addr as *mut FallbackListNode;
+        node_ptr.write(node);
+        self.head.next = Some(&mut *node_ptr);
+    }}
+
+    fn find_region(&mut self, size: usize, align: usize) -> Option<(&'static mut FallbackListNode, usize)> {
+        let mut current = &mut self.head;
+        // look for a large enough memory region in linked list
+        while let Some(ref mut region) = current.next {
+            if let Ok(alloc_start) = Self::alloc_from_region(&region, size, align) {
+                // region suitable for allocation -> remove node from list
+                let next = region.next.take();
+                let ret = Some((current.next.take().unwrap(), alloc_start));
+                current.next = next;
+                return ret;
+            } else {
+                // region not suitable -> continue with next region
+                current = current.next.as_mut().unwrap();
+            }
+        }
+        None
+    }
+    const fn align_up(addr: usize, align: usize) -> usize {
+        (addr + align - 1) & !(align - 1)
+    }
+
+    fn size_align(layout: Layout) -> (usize, usize) {
+        let layout = layout
+            .align_to(align_of::<ListNode>())
+            .expect("adjusting alignment failed")
+            .pad_to_align();
+        let size = layout.size().max(size_of::<ListNode>());
+        (size, layout.align())
+    }
+
+    fn alloc_from_region(region: &FallbackListNode, size: usize, align: usize) -> Result<usize, ()>
+    {
+        let alloc_start = Self::align_up(region.start_addr(), align);
+        let alloc_end = alloc_start.checked_add(size).ok_or(())?;
+
+        if alloc_end > region.end_addr() {
+            return Err(());
+        }
+
+        let excess_size = region.end_addr() - alloc_end;
+        if excess_size > 0 && excess_size < size_of::<ListNode>() {
+            return Err(());
+        }
+
+        Ok(alloc_start)
+    }
+}
+
+unsafe impl GlobalAlloc for Locked<FoundryFallbackAllocator> {
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        let mut allocator = self.lock();
+        // perform layout adjustments
+        let (size, align) = FoundryFallbackAllocator::size_align(layout);
+
+        if let Some((region, alloc_start)) = allocator.find_region(size, align) {
+            let alloc_end = alloc_start.checked_add(size).expect("overflow");
+            let excess_size = region.end_addr() - alloc_end;
+            if excess_size > 0 {
+                unsafe { allocator.add_region(alloc_end, excess_size) };
+            }
+            alloc_start as *mut u8
+        } else {
+            ptr::null_mut()
+        }
+    }
+
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        let mut allocator = self.lock();
+
+        // perform layout adjustments
+        let (size, _) = FoundryFallbackAllocator::size_align(layout);
+
+        unsafe {
+            allocator.add_region(ptr as usize, size)
+        }
+    }
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+

libk/src/drivers/kalloc/mod.rs

@@ -1 +1,2 @@
 pub mod allocator;
+mod foundry_kalloc;