feat: implement allocator, kindof

src/memory/allocator/mod.rs

@@ -0,0 +1,46 @@
+use core::{
+    alloc::{GlobalAlloc, Layout},
+    mem::transmute,
+};
+
+static mut NODES: Option<&mut LinkedAllocatorNode> = None;
+
+#[global_allocator]
+static ALLOCATOR: LinkedListAllocator = LinkedListAllocator {};
+
+pub struct LinkedListAllocator {}
+
+unsafe impl<'a> GlobalAlloc for LinkedListAllocator {
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        if NODES.is_none() {
+            panic!("LinkedListAllocator has not been initialized yet");
+        }
+
+        let node = NODES.as_deref_mut().unwrap();
+
+        if layout.size() > node.size {
+            panic!("Out of heap memory");
+        }
+
+        node.size = node.size - layout.size();
+        let ptr = node as *mut _ as usize + node.size;
+
+        ptr as *mut u8
+    }
+
+    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
+        // unimplemented!("Deallocate")
+    }
+}
+
+pub unsafe fn init(node: &'static mut LinkedAllocatorNode) {
+    if NODES.is_some() {
+        panic!("LinkedListAllocator is already initialized");
+    }
+    NODES = Some(node);
+}
+
+pub struct LinkedAllocatorNode<'a> {
+    pub(crate) size: usize,
+    pub(crate) next: Option<&'a mut Self>,
+}

src/memory/mod.rs

@@ -1,15 +1,17 @@
-use multiboot2::{BootInformation, ElfSectionFlags};
-use x86_64::registers::control::{Cr0, Cr0Flags};
-use x86_64::registers::model_specific::{Efer, EferFlags, Msr};
-use x86_64::registers::xcontrol::{XCr0, XCr0Flags};
+use core::ops::RangeInclusive;
 
+use crate::memory::allocator::LinkedAllocatorNode;
 use crate::memory::frames::bump_alloc::BumpAllocator;
 use crate::memory::frames::{FrameIter, PhysicalFrame, PAGE_SIZE};
 use crate::memory::paging::entry::EntryFlags;
-use crate::memory::paging::mapper::{self, ActivePageTable};
+use crate::memory::paging::mapper::ActivePageTable;
 use crate::memory::paging::Page;
 use crate::println;
-use core::ops::RangeInclusive;
+use alloc::string::String;
+use multiboot2::{BootInformation, ElfSectionFlags};
+use x86_64::registers::control::{Cr0, Cr0Flags};
+use x86_64::registers::model_specific::{Efer, EferFlags, Msr};
+use x86_64::registers::xcontrol::{XCr0, XCr0Flags};
 
 use self::frames::FrameAlloc;
 use self::paging::inactive::InactivePageTable;
@@ -45,6 +47,25 @@ pub(super) fn init(boot_info: &BootInformation) -> () {
     remap_kernel(&mut frame_allocator, &mut active_page, boot_info);
 
     println!("[OK] Kernel remapped!");
+    println!("[INFO] Initializing linked list allocator...");
+
+    let page = Page::containing_address(0xffff_ffff_ff00_0000);
+    let frame = frame_allocator.allocate_frame().expect("Out of memory");
+    active_page.map_to(page, frame, EntryFlags::WRITABLE, &mut frame_allocator);
+    let node: &mut LinkedAllocatorNode<'static> = unsafe { &mut *(page.start_address() as *mut _) };
+
+    *node = LinkedAllocatorNode {
+        size: PAGE_SIZE as usize - 16,
+        next: None,
+    };
+
+    unsafe { allocator::init(node) };
+
+    println!("[OK] Linked list allocator initialized!");
+    let mut str = String::from("Hello");
+
+    str += " World!";
+    println!("String: {}", str);
 }
 
 fn remap_kernel<A: FrameAlloc>(