Merge branch 'post-09' into post-10

# Conflicts:
#	README.md

.cargo/config.toml

@@ -1,5 +1,5 @@
 [unstable]
-build-std = ["core", "compiler_builtins"]
+build-std = ["core", "compiler_builtins", "alloc"]
 build-std-features = ["compiler-builtins-mem"]
 
 [build]

Cargo.lock

@@ -20,6 +20,7 @@ version = "0.1.0"
 dependencies = [
  "bootloader",
  "lazy_static",
+ "linked_list_allocator",
  "pc-keyboard",
  "pic8259",
  "spin",
@@ -43,6 +44,24 @@ dependencies = [
  "spin",
 ]
 
+[[package]]
+name = "linked_list_allocator"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d0b725207570aa16096962d0b20c79f8a543df2280bd3c903022b9b0b4d7ea68"
+dependencies = [
+ "spinning_top",
+]
+
+[[package]]
+name = "lock_api"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0382880606dff6d15c9476c416d18690b72742aa7b605bb6dd6ec9030fbf07eb"
+dependencies = [
+ "scopeguard",
+]
+
 [[package]]
 name = "pc-keyboard"
 version = "0.5.1"
@@ -58,12 +77,27 @@ dependencies = [
  "x86_64",
 ]
 
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
 [[package]]
 name = "spin"
 version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
 
+[[package]]
+name = "spinning_top"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75adad84ee84b521fb2cca2d4fd0f1dab1d8d026bda3c5bea4ca63b5f9f9293c"
+dependencies = [
+ "lock_api",
+]
+
 [[package]]
 name = "uart_16550"
 version = "0.2.14"

Cargo.toml

@@ -20,6 +20,7 @@ x86_64 = "0.14.2"
 uart_16550 = "0.2.0"
 pic8259 = "0.10.1"
 pc-keyboard = "0.5.0"
+linked_list_allocator = "0.9.0"
 
 [dependencies.lazy_static]
 version = "1.0"

README.md

@@ -1,10 +1,10 @@
-# Blog OS (Paging Implementation)
+# Blog OS (Heap Allocation)
 
-[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-09)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-09)
+[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-10)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-10)
 
-This repository contains the source code for the [Paging Implementation][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
+This repository contains the source code for the [Heap Allocation][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
 
-[post]: https://os.phil-opp.com/paging-implementation/
+[post]: https://os.phil-opp.com/heap-allocation/
 
 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**
 

src/allocator.rs

@@ -0,0 +1,54 @@
+use alloc::alloc::{GlobalAlloc, Layout};
+use core::ptr::null_mut;
+use linked_list_allocator::LockedHeap;
+use x86_64::{
+    structures::paging::{
+        mapper::MapToError, FrameAllocator, Mapper, Page, PageTableFlags, Size4KiB,
+    },
+    VirtAddr,
+};
+
+pub const HEAP_START: usize = 0x_4444_4444_0000;
+pub const HEAP_SIZE: usize = 100 * 1024; // 100 KiB
+
+#[global_allocator]
+static ALLOCATOR: LockedHeap = LockedHeap::empty();
+
+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(())
+}
+
+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/lib.rs

@@ -2,11 +2,14 @@
 #![cfg_attr(test, no_main)]
 #![feature(custom_test_frameworks)]
 #![feature(abi_x86_interrupt)]
+#![feature(alloc_error_handler)]
 #![test_runner(crate::test_runner)]
 #![reexport_test_harness_main = "test_main"]
 
+extern crate alloc;
 use core::panic::PanicInfo;
 
+pub mod allocator;
 pub mod gdt;
 pub mod interrupts;
 pub mod memory;
@@ -90,3 +93,8 @@ fn test_kernel_main(_boot_info: &'static BootInfo) -> ! {
 fn panic(info: &PanicInfo) -> ! {
     test_panic_handler(info)
 }
+
+#[alloc_error_handler]
+fn alloc_error_handler(layout: alloc::alloc::Layout) -> ! {
+    panic!("allocation error: {:?}", layout)
+}

src/main.rs

@@ -4,6 +4,9 @@
 #![test_runner(blog_os::test_runner)]
 #![reexport_test_harness_main = "test_main"]
 
+extern crate alloc;
+
+use alloc::{boxed::Box, rc::Rc, vec, vec::Vec};
 use blog_os::println;
 use bootloader::{entry_point, BootInfo};
 use core::panic::PanicInfo;
@@ -11,8 +14,9 @@ use core::panic::PanicInfo;
 entry_point!(kernel_main);
 
 fn kernel_main(boot_info: &'static BootInfo) -> ! {
+    use blog_os::allocator;
     use blog_os::memory::{self, BootInfoFrameAllocator};
-    use x86_64::{structures::paging::Page, VirtAddr};
+    use x86_64::VirtAddr;
 
     println!("Hello World{}", "!");
     blog_os::init();
@@ -21,13 +25,31 @@ 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) };
 
-    // map an unused page
+    allocator::init_heap(&mut mapper, &mut frame_allocator).expect("heap initialization failed");
-    let page = Page::containing_address(VirtAddr::new(0xdeadbeaf000));
-    memory::create_example_mapping(page, &mut mapper, &mut frame_allocator);
 
-    // write the string `New!` to the screen through the new mapping
+    // allocate a number on the heap
-    let page_ptr: *mut u64 = page.start_address().as_mut_ptr();
+    let heap_value = Box::new(41);
-    unsafe { page_ptr.offset(400).write_volatile(0x_f021_f077_f065_f04e) };
+    println!("heap_value at {:p}", heap_value);
+
+    // create a dynamically sized vector
+    let mut vec = Vec::new();
+    for i in 0..500 {
+        vec.push(i);
+    }
+    println!("vec at {:p}", vec.as_slice());
+
+    // create a reference counted vector -> will be freed when count reaches 0
+    let reference_counted = Rc::new(vec![1, 2, 3]);
+    let cloned_reference = reference_counted.clone();
+    println!(
+        "current reference count is {}",
+        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/memory.rs

@@ -1,8 +1,6 @@
 use bootloader::bootinfo::{MemoryMap, MemoryRegionType};
 use x86_64::{
-    structures::paging::{
+    structures::paging::{FrameAllocator, OffsetPageTable, PageTable, PhysFrame, Size4KiB},
-        FrameAllocator, Mapper, OffsetPageTable, Page, PageTable, PhysFrame, Size4KiB,
-    },
     PhysAddr, VirtAddr,
 };
 
@@ -35,24 +33,6 @@ unsafe fn active_level_4_table(physical_memory_offset: VirtAddr) -> &'static mut
     &mut *page_table_ptr // unsafe
 }
 
-/// Creates an example mapping for the given page to frame `0xb8000`.
-pub fn create_example_mapping(
-    page: Page,
-    mapper: &mut OffsetPageTable,
-    frame_allocator: &mut impl FrameAllocator<Size4KiB>,
-) {
-    use x86_64::structures::paging::PageTableFlags as Flags;
-
-    let frame = PhysFrame::containing_address(PhysAddr::new(0xb8000));
-    let flags = Flags::PRESENT | Flags::WRITABLE;
-
-    let map_to_result = unsafe {
-        // FIXME: this is not safe, we do it only for testing
-        mapper.map_to(page, frame, flags, frame_allocator)
-    };
-    map_to_result.expect("map_to failed").flush();
-}
-
 /// A FrameAllocator that always returns `None`.
 pub struct EmptyFrameAllocator;
 

tests/heap_allocation.rs

@@ -0,0 +1,60 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(blog_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+extern crate alloc;
+
+use alloc::{boxed::Box, vec::Vec};
+use blog_os::allocator::HEAP_SIZE;
+use bootloader::{entry_point, BootInfo};
+use core::panic::PanicInfo;
+
+entry_point!(main);
+
+fn main(boot_info: &'static BootInfo) -> ! {
+    use blog_os::allocator;
+    use blog_os::memory::{self, BootInfoFrameAllocator};
+    use x86_64::VirtAddr;
+
+    blog_os::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 {}
+}
+
+#[test_case]
+fn simple_allocation() {
+    let heap_value_1 = Box::new(41);
+    let heap_value_2 = Box::new(13);
+    assert_eq!(*heap_value_1, 41);
+    assert_eq!(*heap_value_2, 13);
+}
+
+#[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);
+    }
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    blog_os::test_panic_handler(info)
+}