fix runs

src/allocator.rs

@@ -1,7 +1,6 @@
-use crate::println;
 use alloc::alloc::{GlobalAlloc, Layout};
-use bootloader::BootInfo;
 use core::ptr::null_mut;
+use fixed_size_block::FixedSizeBlockAllocator;
 use x86_64::{
     structures::paging::{
         mapper::MapToError, FrameAllocator, Mapper, Page, PageTableFlags, Size4KiB,
@@ -13,26 +12,12 @@ pub mod bump;
 pub mod fixed_size_block;
 pub mod linked_list;
 
-use fixed_size_block::FixedSizeBlockAllocator;
+pub const HEAP_START: usize = 0x_4444_4444_0000;
+pub const HEAP_SIZE: usize = 4 * 1024 * 1024; // 4 MiB
 
 #[global_allocator]
 static ALLOCATOR: Locked<FixedSizeBlockAllocator> = Locked::new(FixedSizeBlockAllocator::new());
 
-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")
-    }
-}
-
-pub const HEAP_START: usize = 0x_4444_4444_0000;
-pub const HEAP_SIZE: usize = 4 * 1024 * 1024; // 4 MiB
-
 pub fn init_heap(
     mapper: &mut impl Mapper<Size4KiB>,
     frame_allocator: &mut impl FrameAllocator<Size4KiB>,
@@ -53,17 +38,23 @@ pub fn init_heap(
         mapper.map_to(page, frame, flags, frame_allocator)?.flush();
     }
 
+    unsafe {
+        ALLOCATOR.lock().init(HEAP_START, HEAP_SIZE);
+    }
+
     Ok(())
 }
 
-pub fn init(boot_info: &'static BootInfo) {
-    use crate::memory::{self, BootInfoFrameAllocator};
+pub struct Dummy;
 
-    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) };
+unsafe impl GlobalAlloc for Dummy {
+    unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
+        null_mut()
+    }
 
-    init_heap(&mut mapper, &mut frame_allocator).expect("heap initialization failed");
+    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
+        panic!("dealloc should be never called")
+    }
 }
 
 /// A wrapper around spin::Mutex to permit trait implementations.

src/allocator/bump.rs

@@ -26,7 +26,7 @@ impl BumpAllocator {
     /// memory range is unused. Also, this method must be called only once.
     pub unsafe fn init(&mut self, heap_start: usize, heap_size: usize) {
         self.heap_start = heap_start;
-        self.heap_end = heap_start + heap_size;
+        self.heap_end = heap_start.saturating_add(heap_size);
         self.next = heap_start;
     }
 }

src/allocator/fixed_size_block.rs

@@ -5,16 +5,24 @@ use core::{
     ptr::{self, NonNull},
 };
 
-struct ListNode {
-    next: Option<&'static mut ListNode>,
-}
-
 /// The block sizes to use.
 ///
 /// The sizes must each be power of 2 because they are also used as
 /// the block alignment (alignments must be always powers of 2).
 const BLOCK_SIZES: &[usize] = &[8, 16, 32, 64, 128, 256, 512, 1024, 2048];
 
+/// Choose an appropriate block size for the given layout.
+///
+/// Returns an index into the `BLOCK_SIZES` array.
+fn list_index(layout: &Layout) -> Option<usize> {
+    let required_block_size = layout.size().max(layout.align());
+    BLOCK_SIZES.iter().position(|&s| s >= required_block_size)
+}
+
+struct ListNode {
+    next: Option<&'static mut ListNode>,
+}
+
 pub struct FixedSizeBlockAllocator {
     list_heads: [Option<&'static mut ListNode>; BLOCK_SIZES.len()],
     fallback_allocator: linked_list_allocator::Heap,
@@ -47,14 +55,6 @@ impl FixedSizeBlockAllocator {
     }
 }
 
-/// Choose an appropriate block size for the given layout.
-///
-/// Returns an index into the `BLOCK_SIZES` array.
-fn list_index(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<FixedSizeBlockAllocator> {
     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
         let mut allocator = self.lock();

src/allocator/linked_list.rs

@@ -81,8 +81,7 @@ impl LinkedListAllocator {
         None
     }
 
-    /// Try to use the given region for an allocation with given size and
-    /// alignment.
+    /// Try to use the given region for an allocation with given size and alignment.
     ///
     /// Returns the allocation start address on success.
     fn alloc_from_region(region: &ListNode, size: usize, align: usize) -> Result<usize, ()> {

src/lib.rs

@@ -31,12 +31,20 @@ use bootloader::BootInfo;
 use core::panic::PanicInfo;
 
 pub fn init(boot_info: &'static BootInfo) {
+    use x86_64::VirtAddr;
+    use self::memory::{self, BootInfoFrameAllocator};
+
     println!("XeOS booting:");
     gdt::init();
     interrupts::init_idt();
     unsafe { interrupts::PICS.lock().initialize() };
     x86_64::instructions::interrupts::enable();
-    allocator::init(&boot_info);
+
+    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");
 }
 
 pub fn hlt_loop() -> ! {

src/memory.rs

@@ -1,7 +1,8 @@
 use bootloader::bootinfo::{MemoryMap, MemoryRegionType};
 use x86_64::{
     structures::paging::{
-        FrameAllocator, Mapper, OffsetPageTable, Page, PageTable, PhysFrame, Size4KiB, UnusedPhysFrame,
+        FrameAllocator, Mapper, OffsetPageTable, Page, PageTable, PhysFrame, Size4KiB,
+        UnusedPhysFrame,
     },
     PhysAddr, VirtAddr,
 };
@@ -35,6 +36,32 @@ 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));
+    // FIXME: ONLY FOR TEMPORARY TESTING
+    let unused_frame = unsafe { UnusedPhysFrame::new(frame) };
+    let flags = Flags::PRESENT | Flags::WRITABLE;
+
+    let map_to_result = mapper.map_to(page, unused_frame, flags, frame_allocator);
+    map_to_result.expect("map_to failed").flush();
+}
+
+/// A FrameAllocator that always returns `None`.
+pub struct EmptyFrameAllocator;
+
+unsafe impl FrameAllocator<Size4KiB> for EmptyFrameAllocator {
+    fn allocate_frame(&mut self) -> Option<UnusedPhysFrame> {
+        None
+    }
+}
+
 /// A FrameAllocator that returns usable frames from the bootloader's memory map.
 pub struct BootInfoFrameAllocator {
     memory_map: &'static MemoryMap,
@@ -53,18 +80,14 @@ impl BootInfoFrameAllocator {
             next: 0,
         }
     }
-}
 
-impl BootInfoFrameAllocator {
     /// Returns an iterator over the usable frames specified in the memory map.
     fn usable_frames(&self) -> impl Iterator<Item = UnusedPhysFrame> {
         // get usable regions from memory map
         let regions = self.memory_map.iter();
-        let usable_regions = regions
-            .filter(|r| r.region_type == MemoryRegionType::Usable);
+        let usable_regions = regions.filter(|r| r.region_type == MemoryRegionType::Usable);
         // map each region to its address range
-        let addr_ranges = usable_regions
-            .map(|r| r.range.start_addr()..r.range.end_addr());
+        let addr_ranges = usable_regions.map(|r| r.range.start_addr()..r.range.end_addr());
         // transform to an iterator of frame start addresses
         let frame_addresses = addr_ranges.flat_map(|r| r.step_by(4096));
         // create `PhysFrame` types from the start addresses
@@ -81,4 +104,3 @@ unsafe impl FrameAllocator<Size4KiB> for BootInfoFrameAllocator {
         frame
     }
 }
-