refactor mega-commit.

- reorganised the entire project so that the entire kernel is a single codebase rather than a kernel and a libk.

kernel/src/arch/x86_64/memory/allocation/allocator.rs

@@ -0,0 +1,249 @@
+use core::alloc::{GlobalAlloc, Layout};
+use core::ptr;
+use spin::{Mutex, MutexGuard};
+use x86_64::structures::paging::{Size4KiB, mapper::MapToError};
+
+/// We are currently using a linked list heap allocator which uses our underlying page allocator.
+#[global_allocator]
+/// This is now Rust's global allocator, so we can use stuff requiring heap allocations.
+static ALLOCATOR: Locked<FoundryAllocator> = Locked::new(FoundryAllocator::new());
+
+pub const HEAP_START: usize = 0x4444_4444_0000;
+pub const HEAP_SIZE: usize = 1024 * 1024 * 1024;
+
+/// Sets up the heap using the backing page frame allocator.
+pub unsafe fn init_heap() -> Result<(), MapToError<Size4KiB>> {
+    unsafe {
+        // code to allocate frames is now done in the page fault interrupt handler!
+        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()
+    }
+}
+
+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) }
+    }
+}

kernel/src/arch/x86_64/memory/allocation/foundry_kalloc.rs

@@ -0,0 +1 @@
+

kernel/src/arch/x86_64/memory/allocation/mod.rs

@@ -0,0 +1,2 @@
+pub mod allocator;
+mod foundry_kalloc;

kernel/src/arch/x86_64/memory/memory.rs

@@ -0,0 +1,146 @@
+// use lib_alloc::allocator::FoundryAllocator;
+use limine::{memory_map::EntryType, response::MemoryMapResponse};
+use spin::{Mutex, Once};
+use x86_64::{
+    PhysAddr, VirtAddr,
+    registers::control::Cr3,
+    structures::paging::{FrameAllocator, OffsetPageTable, PageTable, PhysFrame, Size4KiB},
+};
+
+pub static FRAME_ALLOCATOR: Once<Mutex<FoundryOSFrameAllocator>> = Once::new();
+pub static OFFSET_PAGE_TABLE: Once<Mutex<OffsetPageTable>> = Once::new();
+/// Returns a mutable reference to the current level 4 page table.
+///
+/// # Safety
+///
+/// The caller must ensure that the level 4 page table is not modified
+/// simultaneously. The caller must also ensure that the physical memory offset
+/// is correct, to ensure that the correct virtual address is constructed.
+unsafe fn active_l4_table(physical_memory_offset: VirtAddr) -> &'static mut PageTable {
+    let (level_4_frame, _) = Cr3::read();
+
+    let phys_addr = level_4_frame.start_address();
+    let virt = phys_addr.as_u64() + physical_memory_offset.as_u64();
+    unsafe { &mut *(virt as *mut PageTable) }
+}
+
+/// Initializes the `OffsetPageTable` for the current CPU architecture.
+///
+/// # Safety
+///
+/// This function must be called only once and should be called before any
+/// memory operations are performed that rely on virtual memory management.
+/// The provided `physical_memory_offset` must be accurate to ensure correct
+/// translation of physical addresses.
+///
+/// # Parameters
+///
+/// - `physical_memory_offset`: The offset to convert physical addresses to
+///   virtual addresses in the higher-half direct map.
+///
+/// # Returns
+///
+/// Returns an `OffsetPageTable` that allows for manipulation of the page
+/// tables for the current CPU architecture.
+pub fn init_page_table(physical_memory_offset: VirtAddr) {
+    unsafe {
+        let l4_table = active_l4_table(physical_memory_offset);
+        let offset_table = OffsetPageTable::new(l4_table, physical_memory_offset);
+        OFFSET_PAGE_TABLE.call_once(|| Mutex::new(offset_table));
+    }
+}
+
+pub struct FoundryOSFrameAllocator {
+    memory_map: &'static MemoryMapResponse,
+    next: usize,
+}
+
+pub fn init_frame_allocator(memory_map: &'static MemoryMapResponse) {
+    unsafe {
+        FRAME_ALLOCATOR.call_once(|| Mutex::new(FoundryOSFrameAllocator::init(memory_map)));
+    }
+}
+
+impl FoundryOSFrameAllocator {
+    /// Creates a new `FoundryOSFrameAllocator` from a memory map.
+    ///
+    /// This function takes a reference to a `MemoryMapResponse` and initializes a
+    /// `FoundryOSFrameAllocator` with it. The `next` field is set to 0, indicating that
+    /// the first frame to be allocated is the first frame in the memory map.
+    pub const unsafe fn init(memory_map: &'static MemoryMapResponse) -> Self {
+        Self {
+            memory_map,
+            next: 0,
+        }
+    }
+
+    pub fn count_usable_frames(&self) -> u32 {
+        self.usable_frames().count() as u32
+    }
+
+    /// An iterator over all usable frames in the memory map.
+    ///
+    /// Yields one `PhysFrame` for each available 4KiB frame in the memory map.
+    ///
+    /// This function is used to allocate frames for the pagemap.
+    fn usable_frames(&self) -> impl Iterator<Item = PhysFrame> + use<> {
+        let regions = self.memory_map.entries().iter();
+        let usable_regions = regions.filter(|region| region.entry_type == EntryType::USABLE);
+
+        let addr_ranges = usable_regions.map(|region| region.base..region.base + region.length);
+
+        let frame_addresses = addr_ranges.flat_map(|r| r.step_by(4096));
+
+        frame_addresses.map(|addr| PhysFrame::from_start_address(PhysAddr::new(addr)).unwrap())
+    }
+}
+
+unsafe impl FrameAllocator<Size4KiB> for FoundryOSFrameAllocator {
+    /// Allocates a frame from the list of usable frames.
+    ///
+    /// This function returns the next available `PhysFrame` from the memory map,
+    /// if one exists. Once a frame is allocated, the internal counter is incremented
+    /// to point to the next frame for future allocations.
+    ///
+    /// # Returns
+    ///
+    /// - `Some(PhysFrame)`: If a usable frame is available.
+    /// - `None`: If there are no more usable frames to allocate.
+    fn allocate_frame(&mut self) -> Option<PhysFrame> {
+        let frame = self.usable_frames().nth(self.next);
+        self.next += 1;
+        frame
+    }
+}
+
+// pub unsafe fn translate_addr(addr: VirtAddr, physical_memory_offset: VirtAddr) -> Option<PhysAddr> {
+//     translate_addr_inner(addr, physical_memory_offset)
+// }
+
+// fn translate_addr_inner(addr: VirtAddr, physical_memory_offset: VirtAddr) -> Option<PhysAddr> {
+//     let (l4_table_frame, _) = Cr3::read();
+
+//     let table_indexes = [
+//         addr.p4_index(),
+//         addr.p3_index(),
+//         addr.p2_index(),
+//         addr.p1_index(),
+//     ];
+//     let mut frame = l4_table_frame;
+
+//     for &i in &table_indexes {
+//         let virt = physical_memory_offset + frame.start_address().as_u64();
+//         let table_ptr: *const PageTable = virt.as_ptr();
+//         let table = unsafe { &*table_ptr };
+
+//         let entry = &table[i];
+
+//         frame = match entry.frame() {
+//             Ok(frame) => frame,
+//             Err(FrameError::FrameNotPresent) => return None,
+//             Err(FrameError::HugeFrame) => panic!("huge frames are not supported!"),
+//         };
+//     }
+
+//     Some(frame.start_address() + u64::from(addr.page_offset()))
+// }

kernel/src/arch/x86_64/memory/memory_map.rs

@@ -0,0 +1,55 @@
+//! Sets up a memory map using Limine.
+
+use limine::{
+    request::{HhdmRequest, KernelAddressRequest, MemoryMapRequest},
+    response::MemoryMapResponse,
+};
+use spin::Lazy;
+
+#[used]
+#[unsafe(link_section = ".requests")]
+static MEMORY_MAP_REQUEST: MemoryMapRequest = MemoryMapRequest::new();
+
+#[used]
+#[unsafe(link_section = ".requests")]
+static HIGHER_HALF_DIRECT_MAP_REQUEST: HhdmRequest = HhdmRequest::new();
+
+#[used]
+#[unsafe(link_section = ".requests")]
+static KERNEL_ADDRESS_REQUEST: KernelAddressRequest = KernelAddressRequest::new();
+
+/// ```rs
+/// let virt_addr = phys_addr + offset;
+/// let phys_addr = virt_addr - offset; // (given VA is in the HHDM). Do not use for executable code.
+/// ```
+pub static PHYSICAL_MEMORY_OFFSET: Lazy<u64> = Lazy::new(|| {
+    HIGHER_HALF_DIRECT_MAP_REQUEST
+        .get_response()
+        .unwrap()
+        .offset()
+});
+
+/// Converts virtual addresses in the kernel to a physical address like this:
+/// ```rs
+/// let phys_addr = virt_addr - virtual_base + physical_base;
+/// ```
+///
+/// Returns (virtual_base, physical_base)
+pub static _KERNEL_PHYSICAL_MEMORY_OFFSET: Lazy<(u64, u64)> = Lazy::new(|| {
+    let resp = KERNEL_ADDRESS_REQUEST.get_response().unwrap();
+
+    // These are base addresses, using Limine's built in page table.
+    (resp.virtual_base(), resp.physical_base())
+});
+
+/// Fetches the memory map from Limine.
+///
+/// # Panics
+///
+/// Panics if the memory map was not found in MEMORY_MAP_REQUEST.
+pub fn get_memory_map() -> &'static MemoryMapResponse {
+    MEMORY_MAP_REQUEST.get_response().map_or_else(
+        || unreachable!("Could not fetch memory map from Limine."),
+        |memory_map| memory_map,
+    )
+}

kernel/src/arch/x86_64/memory/mod.rs

@@ -0,0 +1,3 @@
+pub mod allocation;
+pub mod memory;
+pub mod memory_map;