feat: implement heap allocation

Author: criskell

.cargo/config.toml

@@ -3,7 +3,7 @@ target = "bare-metal-target.json"
 
 [unstable]
 build-std-features = ["compiler-builtins-mem"]
-build-std = ["core", "compiler_builtins"]
+build-std = ["core", "compiler_builtins", "alloc"]
 
 [target.'cfg(target_os = "none")']
 runner = "bootimage runner"

Cargo.lock

@@ -11,6 +11,7 @@ x86_64 = "0.14.2"
 uart_16550 = "0.2.0"
 pic8259 = "0.10.1"
 pc-keyboard = "0.7.0"
+linked_list_allocator = "0.9.0"
 
 [dependencies.lazy_static]
 version = "1.0"
@@ -41,4 +42,4 @@ harness = false       # disable test runner from default and custom test framewo
 
 [[test]]
 name = "stack_overflow"
-harness = false
+harness = false

Cargo.toml

@@ -0,0 +1,59 @@
+use alloc::alloc::{GlobalAlloc, Layout};
+use core::ptr::null_mut;
+use linked_list_allocator::LockedHeap;
+use x86_64::{
+    VirtAddr,
+    structures::paging::{
+        FrameAllocator, Mapper, Page, PageTableFlags, Size4KiB, mapper::MapToError,
+    },
+};
+
+pub const HEAP_START: usize = 0x_4444_4444_0000;
+pub const HEAP_SIZE: usize = 100 * 1024; // 100 KiB
+
+pub fn init_heap(
+    mapper: &mut impl Mapper<Size4KiB>,
+    frame_allocator: &mut impl FrameAllocator<Size4KiB>,
+) -> Result<(), MapToError<Size4KiB>> {
+    let page_range = {
+        let heap_start = VirtAddr::new(HEAP_START as u64);
+        let heap_end = heap_start + HEAP_SIZE - 1u64;
+        let heap_start_page = Page::containing_address(heap_start);
+        let heap_end_page = Page::containing_address(heap_end);
+
+        Page::range_inclusive(heap_start_page, heap_end_page)
+    };
+
+    for page in page_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, HEAP_SIZE);
+    }
+
+    Ok(())
+}
+
+#[global_allocator]
+static ALLOCATOR: LockedHeap = LockedHeap::empty();
+
+pub struct Dummy;
+
+unsafe impl GlobalAlloc for Dummy {
+    unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
+        null_mut()
+    }
+
+    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
+        panic!("dealloc should be never called")
+    }
+}

src/allocator.rs

@@ -7,6 +7,9 @@
 
 use core::panic::PanicInfo;
 
+extern crate alloc;
+
+pub mod allocator;
 pub mod gdt;
 pub mod interrupts;
 pub mod memory;

src/lib.rs

@@ -4,16 +4,19 @@
 #![test_runner(osdev_rust::test_runner)]
 #![reexport_test_harness_main = "test_main"]
 
+use alloc::{boxed::Box, rc::Rc, vec, vec::Vec};
 use bootloader::{BootInfo, entry_point};
 use core::panic::PanicInfo;
 use osdev_rust::println;
 
+extern crate alloc;
+
 entry_point!(kernel_main);
 
 fn kernel_main(boot_info: &'static BootInfo) -> ! {
-    use osdev_rust::memory;
-    use osdev_rust::memory::BootInfoFrameAllocator;
-    use x86_64::{VirtAddr, structures::paging::Page};
+    use osdev_rust::allocator;
+    use osdev_rust::memory::{self, BootInfoFrameAllocator};
+    use x86_64::VirtAddr;
 
     println!("Hello World!");
 
@@ -23,14 +26,31 @@ fn kernel_main(boot_info: &'static BootInfo) -> ! {
     let mut mapper = unsafe { memory::init(phys_mem_offset) };
     let mut frame_allocator = unsafe { BootInfoFrameAllocator::init(&boot_info.memory_map) };
 
-    let page = Page::containing_address(VirtAddr::new(0xdeadbeef000));
-    memory::create_example_mapping(page, &mut mapper, &mut frame_allocator);
+    allocator::init_heap(&mut mapper, &mut frame_allocator).expect("heap initialization failed");
+
+    let heap_value = Box::new(42);
+    println!("heap_value at {:p}", heap_value);
+
+    let mut vec = Vec::new();
 
-    let page_ptr: *mut u64 = page.start_address().as_mut_ptr();
-    unsafe {
-        page_ptr.offset(400).write_volatile(0x_f021_f077_f065_f04e);
+    for i in 0..500 {
+        vec.push(i);
     }
 
+    println!("vec at {:p}", vec.as_slice());
+
+    let reference_counted = Rc::new(vec![1, 2, 3]);
+    let cloned_reference = reference_counted.clone();
+    println!(
+        "current reference count: {}",
+        Rc::strong_count(&cloned_reference),
+    );
+    core::mem::drop(reference_counted);
+    println!(
+        "reference count is {} now",
+        Rc::strong_count(&cloned_reference)
+    );
+
     #[cfg(test)]
     test_main();
 

src/main.rs

@@ -8,7 +8,7 @@ use core::panic::PanicInfo;
 
 use osdev_rust::println;
 
-#[no_mangle]
+#[unsafe(no_mangle)]
 pub extern "C" fn _start() -> ! {
     test_main();
 

tests/basic_boot.rs

@@ -0,0 +1,64 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(osdev_rust::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+extern crate alloc;
+
+use alloc::{boxed::Box, vec::Vec};
+use bootloader::{BootInfo, entry_point};
+use core::panic::PanicInfo;
+use osdev_rust::allocator::HEAP_SIZE;
+
+entry_point!(main);
+
+fn main(boot_info: &'static BootInfo) -> ! {
+    use osdev_rust::allocator;
+    use osdev_rust::memory::{self, BootInfoFrameAllocator};
+    use x86_64::VirtAddr;
+
+    osdev_rust::init();
+
+    let phys_mem_offset = VirtAddr::new(boot_info.physical_memory_offset);
+    let mut mapper = unsafe { memory::init(phys_mem_offset) };
+    let mut frame_allocator = unsafe { BootInfoFrameAllocator::init(&boot_info.memory_map) };
+    allocator::init_heap(&mut mapper, &mut frame_allocator).expect("heap initialization failed");
+
+    test_main();
+    loop {}
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    osdev_rust::test_panic_handler(info);
+}
+
+#[test_case]
+fn simple_allocation() {
+    let heap_value_1 = Box::new(42);
+    let heap_value_2 = Box::new(43);
+
+    assert_eq!(*heap_value_1, 42);
+    assert_eq!(*heap_value_2, 43);
+}
+
+#[test_case]
+fn large_vec() {
+    let n = 1000;
+    let mut vec = Vec::new();
+
+    for i in 0..n {
+        vec.push(i);
+    }
+
+    assert_eq!(vec.iter().sum::<u64>(), (n - 1) * n / 2);
+}
+
+#[test_case]
+fn many_boxes() {
+    for i in 0..HEAP_SIZE {
+        let x = Box::new(i);
+        assert_eq!(*x, i);
+    }
+}

tests/heap_allocation.rs

@@ -5,9 +5,9 @@
 
 use core::panic::PanicInfo;
 
-use osdev_rust::{exit_qemu, serial_print, serial_println, QemuExitCode};
+use osdev_rust::{QemuExitCode, exit_qemu, serial_print, serial_println};
 
-#[no_mangle]
+#[unsafe(no_mangle)]
 pub extern "C" fn _start() -> ! {
     should_fail();
     serial_println!("[test did not panic]");

tests/should_panic.rs

@@ -5,12 +5,12 @@
 use core::panic::PanicInfo;
 use lazy_static::lazy_static;
 use osdev_rust::{
-    exit_qemu, gdt::DOUBLE_FAULT_IST_INDEX, serial_print, serial_println, test_panic_handler,
-    QemuExitCode,
+    QemuExitCode, exit_qemu, gdt::DOUBLE_FAULT_IST_INDEX, serial_print, serial_println,
+    test_panic_handler,
 };
 use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
 
-#[no_mangle]
+#[unsafe(no_mangle)]
 pub extern "C" fn _start() -> ! {
     serial_print!("stack_overflow::stack_overflow...\t");