Wip

Update post-10 branch for new "Paging Implementation" post

Cargo.toml

@@ -5,7 +5,7 @@ authors = ["Philipp Oppermann <dev@phil-opp.com>"]
 edition = "2018"
 
 [dependencies]
-bootloader = "0.4.0"
+bootloader = { version = "0.4.0", features = ["map_physical_memory"]}
 volatile = "0.2.3"
 spin = "0.4.9"
 uart_16550 = "0.1.0"

README.md

@@ -1,10 +1,10 @@
-# Blog OS (Hardware Interrupts)
+# Blog OS (Paging Implementation)
 
-[![Build Status](https://travis-ci.org/phil-opp/blog_os.svg?branch=post-08)](https://travis-ci.org/phil-opp/blog_os/branches)
+[![Build Status](https://travis-ci.org/phil-opp/blog_os.svg?branch=post-10)](https://travis-ci.org/phil-opp/blog_os/branches)
 
-This repository contains the source code for the [Hardware Interrupts][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
+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.
 
-[post]: https://os.phil-opp.com/hardware-interrupts/
+[post]: https://os.phil-opp.com/paging-implementation/
 
 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**
 

src/bin/test-basic-boot.rs

@@ -1,8 +1,11 @@
 #![cfg_attr(not(test), no_std)]
 #![cfg_attr(not(test), no_main)] // disable all Rust-level entry points
 #![cfg_attr(test, allow(unused_imports))]
+#![feature(alloc_error_handler)]
 
+use blog_os::memory::allocator::DummyAllocator;
 use blog_os::{exit_qemu, serial_println};
+use core::alloc::Layout;
 use core::panic::PanicInfo;
 
 /// This function is the entry point, since the linker looks for a function
@@ -31,3 +34,11 @@ fn panic(info: &PanicInfo) -> ! {
     }
     loop {}
 }
+
+#[global_allocator]
+static ALLOCATOR: DummyAllocator = DummyAllocator;
+
+#[alloc_error_handler]
+fn out_of_memory(layout: Layout) -> ! {
+    panic!("out of memory: allocation for {:?} failed", layout);
+}

src/bin/test-exception-breakpoint.rs

@@ -1,8 +1,11 @@
 #![no_std]
 #![cfg_attr(not(test), no_main)]
 #![cfg_attr(test, allow(dead_code, unused_macros, unused_imports))]
+#![feature(alloc_error_handler)]
 
+use blog_os::memory::allocator::DummyAllocator;
 use blog_os::{exit_qemu, serial_println};
+use core::alloc::Layout;
 use core::panic::PanicInfo;
 
 #[cfg(not(test))]
@@ -32,3 +35,11 @@ fn panic(info: &PanicInfo) -> ! {
     }
     loop {}
 }
+
+#[global_allocator]
+static ALLOCATOR: DummyAllocator = DummyAllocator;
+
+#[alloc_error_handler]
+fn out_of_memory(layout: Layout) -> ! {
+    panic!("out of memory: allocation for {:?} failed", layout);
+}

src/bin/test-exception-double-fault-stack-overflow.rs

@@ -2,8 +2,11 @@
 #![no_std]
 #![cfg_attr(not(test), no_main)]
 #![cfg_attr(test, allow(dead_code, unused_macros, unused_imports))]
+#![feature(alloc_error_handler)]
 
+use blog_os::memory::allocator::DummyAllocator;
 use blog_os::{exit_qemu, serial_println};
+use core::alloc::Layout;
 use core::panic::PanicInfo;
 use lazy_static::lazy_static;
 
@@ -45,6 +48,14 @@ fn panic(info: &PanicInfo) -> ! {
     loop {}
 }
 
+#[global_allocator]
+static ALLOCATOR: DummyAllocator = DummyAllocator;
+
+#[alloc_error_handler]
+fn out_of_memory(layout: Layout) -> ! {
+    panic!("out of memory: allocation for {:?} failed", layout);
+}
+
 use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
 
 lazy_static! {

src/bin/test-panic.rs

@@ -1,8 +1,11 @@
 #![cfg_attr(not(test), no_std)]
 #![cfg_attr(not(test), no_main)]
 #![cfg_attr(test, allow(unused_imports))]
+#![feature(alloc_error_handler)]
 
+use blog_os::memory::allocator::DummyAllocator;
 use blog_os::{exit_qemu, serial_println};
+use core::alloc::Layout;
 use core::panic::PanicInfo;
 
 #[cfg(not(test))]
@@ -21,3 +24,11 @@ fn panic(_info: &PanicInfo) -> ! {
     }
     loop {}
 }
+
+#[global_allocator]
+static ALLOCATOR: DummyAllocator = DummyAllocator;
+
+#[alloc_error_handler]
+fn out_of_memory(layout: Layout) -> ! {
+    panic!("out of memory: allocation for {:?} failed", layout);
+}

src/interrupts.rs

@@ -8,7 +8,7 @@ use crate::{gdt, hlt_loop, print, println};
 use lazy_static::lazy_static;
 use pic8259_simple::ChainedPics;
 use spin;
-use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
+use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame, PageFaultErrorCode};
 
 pub const PIC_1_OFFSET: u8 = 32;
 pub const PIC_2_OFFSET: u8 = PIC_1_OFFSET + 8;
@@ -37,6 +37,7 @@ lazy_static! {
     static ref IDT: InterruptDescriptorTable = {
         let mut idt = InterruptDescriptorTable::new();
         idt.breakpoint.set_handler_fn(breakpoint_handler);
+        idt.page_fault.set_handler_fn(page_fault_handler);
         unsafe {
             idt.double_fault
                 .set_handler_fn(double_fault_handler)
@@ -56,6 +57,19 @@ extern "x86-interrupt" fn breakpoint_handler(stack_frame: &mut InterruptStackFra
     println!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
 }
 
+extern "x86-interrupt" fn page_fault_handler(
+    stack_frame: &mut InterruptStackFrame,
+    _error_code: PageFaultErrorCode,
+) {
+    use crate::hlt_loop;
+    use x86_64::registers::control::Cr2;
+
+    println!("EXCEPTION: PAGE FAULT");
+    println!("Accessed Address: {:?}", Cr2::read());
+    println!("{:#?}", stack_frame);
+    hlt_loop();
+}
+
 extern "x86-interrupt" fn double_fault_handler(
     stack_frame: &mut InterruptStackFrame,
     _error_code: u64,

src/lib.rs

@@ -1,8 +1,13 @@
 #![cfg_attr(not(test), no_std)]
 #![feature(abi_x86_interrupt)]
+#![feature(alloc)]
+#![feature(const_fn)]
+
+extern crate alloc;
 
 pub mod gdt;
 pub mod interrupts;
+pub mod memory;
 pub mod serial;
 pub mod vga_buffer;
 

src/main.rs

@@ -1,14 +1,27 @@
 #![cfg_attr(not(test), no_std)]
 #![cfg_attr(not(test), no_main)]
 #![cfg_attr(test, allow(unused_imports))]
+#![feature(alloc)]
+#![feature(alloc_error_handler)]
 
-use blog_os::println;
+extern crate alloc;
+
+use alloc::vec::Vec;
+use blog_os::{
+    memory::allocator::{BumpAllocator, LinkedListAllocator, LockedAllocator, BucketAllocator},
+    println,
+};
+use bootloader::{entry_point, BootInfo};
+use core::alloc::Layout;
 use core::panic::PanicInfo;
 
+entry_point!(kernel_main);
+
 #[cfg(not(test))]
-#[no_mangle]
+fn kernel_main(boot_info: &'static BootInfo) -> ! {
-pub extern "C" fn _start() -> ! {
     use blog_os::interrupts::PICS;
+    use blog_os::memory;
+    use x86_64::{structures::paging::Page, VirtAddr};
 
     println!("Hello World{}", "!");
 
@@ -17,6 +30,25 @@ pub extern "C" fn _start() -> ! {
     unsafe { PICS.lock().initialize() };
     x86_64::instructions::interrupts::enable();
 
+    let mut mapper = unsafe { memory::init(boot_info.physical_memory_offset) };
+    let mut frame_allocator = memory::init_frame_allocator(&boot_info.memory_map);
+
+    let heap_start = VirtAddr::new(HEAP_START);
+    let heap_end = VirtAddr::new(HEAP_END);
+    memory::map_heap(heap_start, heap_end, &mut mapper, &mut frame_allocator)
+        .expect("map_heap failed");
+
+    ALLOCATOR.lock().underlying().add_memory(heap_start, HEAP_END - HEAP_START);
+
+    //let mut x = Vec::with_capacity(1000);
+    let mut x = Vec::new();
+    for i in 0..1000 {
+        x.push(i);
+    }
+    println!("{:?}", *ALLOCATOR.lock());
+    println!("with vec of size {}: {}", x.len(), x.iter().sum::<i32>());
+    println!("with formular: {}", 999 * 1000 / 2);
+
     println!("It did not crash!");
     blog_os::hlt_loop();
 }
@@ -28,3 +60,15 @@ fn panic(info: &PanicInfo) -> ! {
     println!("{}", info);
     blog_os::hlt_loop();
 }
+
+const HEAP_START: u64 = 0o_001_000_000_0000;
+const HEAP_END: u64 = HEAP_START + 10 * 0x1000;
+
+#[global_allocator]
+static ALLOCATOR: LockedAllocator<BucketAllocator<LinkedListAllocator>> =
+    LockedAllocator::new(BucketAllocator::new(LinkedListAllocator::empty()));
+
+#[alloc_error_handler]
+fn out_of_memory(layout: Layout) -> ! {
+    panic!("out of memory: allocation for {:?} failed", layout);
+}

src/memory.rs

@@ -0,0 +1,120 @@
+use bootloader::bootinfo::{MemoryMap, MemoryRegionType};
+use x86_64::{
+    structures::paging::{
+        mapper, FrameAllocator, MappedPageTable, Mapper, MapperAllSizes, Page, PageTable,
+        PhysFrame, Size4KiB,
+    },
+    PhysAddr, VirtAddr,
+};
+
+pub mod allocator;
+
+/// Initialize a new MappedPageTable.
+///
+/// This function is unsafe because the caller must guarantee that the
+/// complete physical memory is mapped to virtual memory at the passed
+/// `physical_memory_offset`. Also, this function must be only called once
+/// to avoid aliasing `&mut` references (which is undefined behavior).
+pub unsafe fn init(physical_memory_offset: u64) -> impl MapperAllSizes {
+    let level_4_table = active_level_4_table(physical_memory_offset);
+    let phys_to_virt = move |frame: PhysFrame| -> *mut PageTable {
+        let phys = frame.start_address().as_u64();
+        let virt = VirtAddr::new(phys + physical_memory_offset);
+        virt.as_mut_ptr()
+    };
+    MappedPageTable::new(level_4_table, phys_to_virt)
+}
+
+/// Create a FrameAllocator from the passed memory map
+pub fn init_frame_allocator(
+    memory_map: &'static MemoryMap,
+) -> BootInfoFrameAllocator<impl Iterator<Item = PhysFrame>> {
+    // get usable regions from memory map
+    let regions = memory_map
+        .iter()
+        .filter(|r| r.region_type == MemoryRegionType::Usable);
+    // map each region to its address range
+    let addr_ranges = 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.into_iter().step_by(4096));
+    // create `PhysFrame` types from the start addresses
+    let frames = frame_addresses.map(|addr| PhysFrame::containing_address(PhysAddr::new(addr)));
+
+    BootInfoFrameAllocator { frames }
+}
+
+/// Returns a mutable reference to the active level 4 table.
+///
+/// This function is unsafe because the caller must guarantee that the
+/// complete physical memory is mapped to virtual memory at the passed
+/// `physical_memory_offset`. Also, this function must be only called once
+/// to avoid aliasing `&mut` references (which is undefined behavior).
+unsafe fn active_level_4_table(physical_memory_offset: u64) -> &'static mut PageTable {
+    use x86_64::{registers::control::Cr3, VirtAddr};
+
+    let (level_4_table_frame, _) = Cr3::read();
+
+    let phys = level_4_table_frame.start_address();
+    let virt = VirtAddr::new(phys.as_u64() + physical_memory_offset);
+    let page_table_ptr: *mut PageTable = virt.as_mut_ptr();
+
+    &mut *page_table_ptr // unsafe
+}
+
+pub fn map_heap(
+    heap_start: VirtAddr,
+    heap_end: VirtAddr,
+    mapper: &mut impl Mapper<Size4KiB>,
+    frame_allocator: &mut impl FrameAllocator<Size4KiB>,
+) -> Result<(), MapHeapError> {
+    use x86_64::structures::paging::PageTableFlags as Flags;
+
+    let flags = Flags::PRESENT | Flags::WRITABLE;
+    let start_page = Page::containing_address(heap_start);
+    let end_page = Page::containing_address(heap_end - 1u64);
+
+    for page in Page::range_inclusive(start_page, end_page) {
+        let frame = frame_allocator.allocate_frame();
+        let frame = frame.ok_or(MapHeapError::FrameAllocationFailed)?;
+        unsafe { mapper.map_to(page, frame, flags, frame_allocator)?.flush() };
+    }
+
+    Ok(())
+}
+
+#[derive(Debug)]
+pub enum MapHeapError {
+    FrameAllocationFailed,
+    MapToError(mapper::MapToError),
+}
+
+impl From<mapper::MapToError> for MapHeapError {
+    fn from(err: mapper::MapToError) -> Self {
+        MapHeapError::MapToError(err)
+    }
+}
+
+/// A FrameAllocator that always returns `None`.
+pub struct EmptyFrameAllocator;
+
+impl FrameAllocator<Size4KiB> for EmptyFrameAllocator {
+    fn allocate_frame(&mut self) -> Option<PhysFrame> {
+        None
+    }
+}
+
+pub struct BootInfoFrameAllocator<I>
+where
+    I: Iterator<Item = PhysFrame>,
+{
+    frames: I,
+}
+
+impl<I> FrameAllocator<Size4KiB> for BootInfoFrameAllocator<I>
+where
+    I: Iterator<Item = PhysFrame>,
+{
+    fn allocate_frame(&mut self) -> Option<PhysFrame> {
+        self.frames.next()
+    }
+}

src/memory/allocator.rs

@@ -0,0 +1,49 @@
+pub use bump::BumpAllocator;
+pub use dummy::DummyAllocator;
+pub use linked_list::LinkedListAllocator;
+pub use bucket::BucketAllocator;
+
+use core::alloc::{GlobalAlloc, Layout};
+use spin::{Mutex, MutexGuard};
+
+mod bump;
+mod dummy;
+mod linked_list;
+mod bucket;
+
+pub struct LockedAllocator<T> {
+    allocator: Mutex<T>,
+}
+
+impl<T> LockedAllocator<T> {
+    pub const fn new(allocator: T) -> Self {
+        Self {
+            allocator: Mutex::new(allocator),
+        }
+    }
+}
+
+impl<T> LockedAllocator<T> {
+    pub fn lock(&self) -> MutexGuard<T> {
+        self.allocator.lock()
+    }
+}
+
+unsafe impl<T> GlobalAlloc for LockedAllocator<T>
+where
+    T: MutGlobalAlloc,
+{
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        self.allocator.lock().alloc(layout)
+    }
+
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        self.allocator.lock().dealloc(ptr, layout)
+    }
+}
+
+pub trait MutGlobalAlloc {
+    fn alloc(&mut self, layout: Layout) -> *mut u8;
+
+    fn dealloc(&mut self, ptr: *mut u8, layout: Layout);
+}

src/memory/allocator/bucket.rs

@@ -0,0 +1,126 @@
+use super::MutGlobalAlloc;
+use core::alloc::Layout;
+use core::mem::size_of;
+use core::fmt::{self, Debug};
+use core::cmp;
+
+#[derive(Debug)]
+pub struct BucketAllocator<A> where A: MutGlobalAlloc + Debug {
+    underlying: A,
+    buckets: [Bucket; 10],
+}
+
+impl<A> BucketAllocator<A> where A: MutGlobalAlloc + Debug {
+    pub const fn new(underlying: A) -> Self {
+        Self {
+            underlying,
+            buckets: [
+                Bucket::new(size_of::<Region>()),
+                Bucket::new(16),
+                Bucket::new(32),
+                Bucket::new(64),
+                Bucket::new(128),
+                Bucket::new(256),
+                Bucket::new(512),
+                Bucket::new(1024),
+                Bucket::new(2048),
+                Bucket::new(4096),
+            ]
+        }
+    }
+
+    pub fn underlying(&mut self) -> &mut A {
+        &mut self.underlying
+    }
+}
+
+pub struct Bucket {
+    size: usize,
+    head: Option<&'static mut Region>,
+}
+
+impl Bucket {
+    const fn new(size: usize) -> Self {
+        Bucket {
+            size,
+            head: None,
+        }
+    }
+
+    fn layout(&self) -> Layout {
+        Layout::from_size_align(self.size, self.size).unwrap()
+    }
+}
+
+impl fmt::Debug for Bucket {
+    fn fmt(&self, f: &mut fmt::Formatter)-> fmt::Result {
+        let mut regions = 0;
+        let mut current = &self.head;
+        while let Some(region) = current {
+            current = &region.next;
+            regions += 1;
+        }
+        f.debug_struct("Bucket").field("size", &self.size).field("regions", &regions).finish()
+    }
+}
+
+#[derive(Debug)]
+struct Region {
+    next: Option<&'static mut Region>,
+}
+
+impl Region {
+    fn new() -> Self {
+        Self {
+            next: None,
+        }
+    }
+
+    fn as_mut_u8(&'static mut self) -> *mut u8 {
+        self as *mut Region as *mut u8
+    }
+
+    unsafe fn from_mut_u8(ptr: *mut u8) -> &'static mut Self {
+        (ptr as *mut Region).write(Region::new());
+        &mut *(ptr as *mut Region)
+    }
+}
+
+impl<A> BucketAllocator<A> where A: MutGlobalAlloc + Debug {
+    fn get_bucket_index(&self, layout: &Layout) -> Option<usize> {
+        let required_bucket_size = cmp::max(layout.size(), layout.align());
+        match self.buckets.binary_search_by(|bucket| bucket.size.cmp(&required_bucket_size)) {
+            Ok(index) => Some(index),
+            Err(index) if index < self.buckets.len() => Some(index),
+            Err(_) => None,
+        }
+    }
+}
+
+impl<A> MutGlobalAlloc for BucketAllocator<A> where A: MutGlobalAlloc + Debug {
+    fn alloc(&mut self, layout: Layout) -> *mut u8 {
+        if let Some(bucket_index) = self.get_bucket_index(&layout) {
+            let bucket = &mut self.buckets[bucket_index];
+            if let Some(head) = bucket.head.take() {
+                let next = head.next.take();
+                bucket.head = next;
+                return head.as_mut_u8();
+            } else {
+                self.underlying.alloc(bucket.layout())
+            }
+        } else {
+            self.underlying.alloc(layout)
+        }
+    }
+
+    fn dealloc(&mut self, ptr: *mut u8, layout: Layout) {
+        if let Some(bucket_index) = self.get_bucket_index(&layout) {
+            let bucket = &mut self.buckets[bucket_index];
+            let region = unsafe {Region::from_mut_u8(ptr)};
+            region.next = bucket.head.take();
+            bucket.head = Some(region);
+        } else {
+            self.underlying.dealloc(ptr, layout);
+        }
+    }
+}

src/memory/allocator/bump.rs

@@ -0,0 +1,38 @@
+use super::MutGlobalAlloc;
+use core::alloc::Layout;
+use x86_64::align_up;
+
+pub struct BumpAllocator {
+    heap_start: u64,
+    heap_end: u64,
+    next: u64,
+}
+
+impl BumpAllocator {
+    pub const fn new(heap_start: u64, heap_end: u64) -> Self {
+        Self {
+            heap_start,
+            heap_end,
+            next: heap_start,
+        }
+    }
+}
+
+impl MutGlobalAlloc for BumpAllocator {
+    fn alloc(&mut self, layout: Layout) -> *mut u8 {
+        let alloc_start = align_up(self.next, layout.align() as u64);
+        let alloc_end = alloc_start.saturating_add(layout.size() as u64);
+
+        if alloc_end >= self.heap_end {
+            // out of memory
+            return 0 as *mut u8;
+        }
+
+        self.next = alloc_end;
+        alloc_start as *mut u8
+    }
+
+    fn dealloc(&mut self, _ptr: *mut u8, _layout: Layout) {
+        panic!("BumpAllocator::dealloc called");
+    }
+}

src/memory/allocator/dummy.rs

@@ -0,0 +1,16 @@
+use core::alloc::{GlobalAlloc, Layout};
+
+/// A dummy allocator that panics on every `alloc` or `dealloc` call.
+pub struct DummyAllocator;
+
+unsafe impl GlobalAlloc for DummyAllocator {
+    /// Always panics.
+    unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
+        panic!("DummyAllocator::alloc called");
+    }
+
+    /// Always panics.
+    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
+        panic!("DummyAllocator::dealloc called");
+    }
+}

src/memory/allocator/linked_list.rs

@@ -0,0 +1,95 @@
+use super::MutGlobalAlloc;
+use core::alloc::Layout;
+use core::mem;
+use x86_64::{align_up, VirtAddr};
+
+#[derive(Debug)]
+pub struct LinkedListAllocator {
+    head: Region,
+}
+
+impl LinkedListAllocator {
+    pub const fn empty() -> Self {
+        let head = Region {
+            size: 0,
+            next: None,
+        };
+        Self { head }
+    }
+
+    pub unsafe fn new(heap_start: VirtAddr, heap_size: u64) -> Self {
+        let mut allocator = Self::empty();
+        allocator.add_memory(heap_start, heap_size);
+        allocator
+    }
+
+    pub fn add_memory(&mut self, start: VirtAddr, size: u64) {
+        let aligned = start.align_up(mem::size_of::<Region>() as u64);
+        let mut region = Region {
+            size: size - (aligned - start),
+            next: None
+        };
+        mem::swap(&mut self.head.next, &mut region.next);
+
+        let region_ptr: *mut Region = aligned.as_mut_ptr();
+        unsafe { region_ptr.write(region) };
+        self.head.next = Some(unsafe { &mut *region_ptr });
+    }
+}
+
+impl MutGlobalAlloc for LinkedListAllocator {
+    fn alloc(&mut self, layout: Layout) -> *mut u8 {
+        let size = align_up(layout.size() as u64, mem::size_of::<Region>() as u64);
+
+        let mut current = &mut self.head;
+        loop {
+            let next = match current.next {
+                Some(ref mut next) => next,
+                None => break,
+            };
+            let next_start = VirtAddr::new(*next as *mut Region as u64);
+            let next_end = next_start + next.size;
+
+            let alloc_start = next_start.align_up(layout.align() as u64);
+            let alloc_end = alloc_start + size;
+
+            // check if Region large enough
+            if alloc_end <= next_end {
+                // remove Region from list
+                let next_next = next.next.take();
+                current.next = next_next;
+                // insert remaining Region to list
+                self.add_memory(alloc_end, next_end - alloc_end);
+                // return allocated memory
+                return alloc_start.as_mut_ptr();
+            }
+
+            // continue with next element
+            //
+            // This is basically `current = next`, but we need a new `match` expression because
+            // the compiler can't figure the lifetimes out when we use the `next` binding
+            // from above.
+            current = match current.next {
+                Some(ref mut next) => next,
+                None => unreachable!(),
+            };
+        }
+
+        // no large enough Region found
+        0 as *mut u8
+    }
+
+    fn dealloc(&mut self, ptr: *mut u8, layout: Layout) {
+        let size = align_up(layout.size() as u64, mem::size_of::<Region>() as u64);
+        self.add_memory(VirtAddr::new(ptr as u64), size);
+    }
+}
+
+#[derive(Debug)]
+struct Region {
+    size: u64,
+    next: Option<&'static mut Region>,
+}
+
+
+// TODO recycle alignment