Merge branch 'post-05' into post-06

Fix: `target-pointer-width` field now expects an integer

Cargo.lock

@@ -26,8 +26,6 @@ version = "0.1.0"
 dependencies = [
  "bootloader",
  "lazy_static",
- "pc-keyboard",
- "pic8259",
  "spin 0.5.2",
  "uart_16550",
  "volatile 0.2.7",
@@ -36,9 +34,9 @@ dependencies = [
 
 [[package]]
 name = "bootloader"
-version = "0.9.32"
+version = "0.9.33"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ea119c3ed05625c179e09d17d0914570a3753ca09c890a73d98f6b72aea00d2"
+checksum = "7bdfddac270bbdd45903296bc1caf29a7fdce6b326aaf0bbab7f04c5f98b7447"
 
 [[package]]
 name = "lazy_static"
@@ -49,21 +47,6 @@ dependencies = [
  "spin 0.9.8",
 ]
 
-[[package]]
-name = "pc-keyboard"
-version = "0.7.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed089a1fbffe3337a1a345501c981f1eb1e47e69de5a40e852433e12953c3174"
-
-[[package]]
-name = "pic8259"
-version = "0.10.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cb844b5b01db1e0b17938685738f113bfc903846f18932b378bc0eabfa40e194"
-dependencies = [
- "x86_64",
-]
-
 [[package]]
 name = "rustversion"
 version = "1.0.22"

Cargo.toml

@@ -13,13 +13,11 @@ name = "stack_overflow"
 harness = false
 
 [dependencies]
-bootloader = { version = "0.9", features = ["map_physical_memory"] }
+bootloader = "0.9"
 volatile = "0.2.6"
 spin = "0.5.2"
 x86_64 = "0.14.2"
 uart_16550 = "0.2.0"
-pic8259 = "0.10.1"
-pc-keyboard = "0.7.0"
 
 [dependencies.lazy_static]
 version = "1.0"

README.md

@@ -1,10 +1,10 @@
-# Blog OS (Paging Implementation)
+# Blog OS (Double Faults)
 
-[![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-06)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-06)
 
-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 [Double Faults][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/double-fault-exceptions/
 
 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**
 

src/interrupts.rs

@@ -1,44 +1,16 @@
-use crate::{gdt, hlt_loop, print, println};
+use crate::{gdt, println};
 use lazy_static::lazy_static;
-use pic8259::ChainedPics;
-use spin;
-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;
-
-#[derive(Debug, Clone, Copy)]
-#[repr(u8)]
-pub enum InterruptIndex {
-    Timer = PIC_1_OFFSET,
-    Keyboard,
-}
-
-impl InterruptIndex {
-    fn as_u8(self) -> u8 {
-        self as u8
-    }
-
-    fn as_usize(self) -> usize {
-        usize::from(self.as_u8())
-    }
-}
-
-pub static PICS: spin::Mutex<ChainedPics> =
-    spin::Mutex::new(unsafe { ChainedPics::new(PIC_1_OFFSET, PIC_2_OFFSET) });
+use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
 
 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)
                 .set_stack_index(gdt::DOUBLE_FAULT_IST_INDEX);
         }
-        idt[InterruptIndex::Timer.as_usize()].set_handler_fn(timer_interrupt_handler);
-        idt[InterruptIndex::Keyboard.as_usize()].set_handler_fn(keyboard_interrupt_handler);
         idt
     };
 }
@@ -51,19 +23,6 @@ extern "x86-interrupt" fn breakpoint_handler(stack_frame: InterruptStackFrame) {
     println!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
 }
 
-extern "x86-interrupt" fn page_fault_handler(
-    stack_frame: InterruptStackFrame,
-    error_code: PageFaultErrorCode,
-) {
-    use x86_64::registers::control::Cr2;
-
-    println!("EXCEPTION: PAGE FAULT");
-    println!("Accessed Address: {:?}", Cr2::read());
-    println!("Error Code: {:?}", error_code);
-    println!("{:#?}", stack_frame);
-    hlt_loop();
-}
-
 extern "x86-interrupt" fn double_fault_handler(
     stack_frame: InterruptStackFrame,
     _error_code: u64,
@@ -71,47 +30,6 @@ extern "x86-interrupt" fn double_fault_handler(
     panic!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
 }
 
-extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: InterruptStackFrame) {
-    print!(".");
-    unsafe {
-        PICS.lock()
-            .notify_end_of_interrupt(InterruptIndex::Timer.as_u8());
-    }
-}
-
-extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: InterruptStackFrame) {
-    use pc_keyboard::{DecodedKey, HandleControl, Keyboard, ScancodeSet1, layouts};
-    use spin::Mutex;
-    use x86_64::instructions::port::Port;
-
-    lazy_static! {
-        static ref KEYBOARD: Mutex<Keyboard<layouts::Us104Key, ScancodeSet1>> =
-            Mutex::new(Keyboard::new(
-                ScancodeSet1::new(),
-                layouts::Us104Key,
-                HandleControl::Ignore
-            ));
-    }
-
-    let mut keyboard = KEYBOARD.lock();
-    let mut port = Port::new(0x60);
-
-    let scancode: u8 = unsafe { port.read() };
-    if let Ok(Some(key_event)) = keyboard.add_byte(scancode) {
-        if let Some(key) = keyboard.process_keyevent(key_event) {
-            match key {
-                DecodedKey::Unicode(character) => print!("{}", character),
-                DecodedKey::RawKey(key) => print!("{:?}", key),
-            }
-        }
-    }
-
-    unsafe {
-        PICS.lock()
-            .notify_end_of_interrupt(InterruptIndex::Keyboard.as_u8());
-    }
-}
-
 #[test_case]
 fn test_breakpoint_exception() {
     // invoke a breakpoint exception

src/lib.rs

@@ -9,15 +9,12 @@ use core::panic::PanicInfo;
 
 pub mod gdt;
 pub mod interrupts;
-pub mod memory;
 pub mod serial;
 pub mod vga_buffer;
 
 pub fn init() {
     gdt::init();
     interrupts::init_idt();
-    unsafe { interrupts::PICS.lock().initialize() };
-    x86_64::instructions::interrupts::enable();
 }
 pub trait Testable {
     fn run(&self) -> ();
@@ -46,7 +43,7 @@ pub fn test_panic_handler(info: &PanicInfo) -> ! {
     serial_println!("[failed]\n");
     serial_println!("Error: {}\n", info);
     exit_qemu(QemuExitCode::Failed);
-    hlt_loop();
+    loop {}
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -65,24 +62,13 @@ pub fn exit_qemu(exit_code: QemuExitCode) {
     }
 }
 
-pub fn hlt_loop() -> ! {
-    loop {
-        x86_64::instructions::hlt();
-    }
-}
-
-#[cfg(test)]
-use bootloader::{BootInfo, entry_point};
-
-#[cfg(test)]
-entry_point!(test_kernel_main);
-
 /// Entry point for `cargo xtest`
 #[cfg(test)]
-fn test_kernel_main(_boot_info: &'static BootInfo) -> ! {
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
     init();
     test_main();
-    hlt_loop();
+    loop {}
 }
 
 #[cfg(test)]

src/main.rs

@@ -5,35 +5,26 @@
 #![reexport_test_harness_main = "test_main"]
 
 use blog_os::println;
-use bootloader::{BootInfo, entry_point};
 use core::panic::PanicInfo;
 
-entry_point!(kernel_main);
-
-fn kernel_main(boot_info: &'static BootInfo) -> ! {
-    use blog_os::memory::{self, BootInfoFrameAllocator};
-    use x86_64::{VirtAddr, structures::paging::Page};
-
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
     println!("Hello World{}", "!");
+
     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) };
+    fn stack_overflow() {
+        stack_overflow(); // for each recursion, the return address is pushed
+    }
 
-    // map an unused page
-    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
-    let page_ptr: *mut u64 = page.start_address().as_mut_ptr();
-    unsafe { page_ptr.offset(400).write_volatile(0x_f021_f077_f065_f04e) };
+    // uncomment line below to trigger a stack overflow
+    // stack_overflow();
 
     #[cfg(test)]
     test_main();
 
     println!("It did not crash!");
-    blog_os::hlt_loop();
+    loop {}
 }
 
 /// This function is called on panic.
@@ -41,7 +32,7 @@ fn kernel_main(boot_info: &'static BootInfo) -> ! {
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
     println!("{}", info);
-    blog_os::hlt_loop();
+    loop {}
 }
 
 #[cfg(test)]

src/memory.rs

@@ -1,106 +0,0 @@
-use bootloader::bootinfo::{MemoryMap, MemoryRegionType};
-use x86_64::{
-    PhysAddr, VirtAddr,
-    structures::paging::{
-        FrameAllocator, Mapper, OffsetPageTable, Page, PageTable, PhysFrame, Size4KiB,
-    },
-};
-
-/// Initialize a new OffsetPageTable.
-///
-/// 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: VirtAddr) -> OffsetPageTable<'static> {
-    unsafe {
-        let level_4_table = active_level_4_table(physical_memory_offset);
-        OffsetPageTable::new(level_4_table, physical_memory_offset)
-    }
-}
-
-/// 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: VirtAddr) -> &'static mut PageTable {
-    use x86_64::registers::control::Cr3;
-
-    let (level_4_table_frame, _) = Cr3::read();
-
-    let phys = level_4_table_frame.start_address();
-    let virt = physical_memory_offset + phys.as_u64();
-    let page_table_ptr: *mut PageTable = virt.as_mut_ptr();
-
-    unsafe { &mut *page_table_ptr }
-}
-
-/// 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;
-
-unsafe impl FrameAllocator<Size4KiB> for EmptyFrameAllocator {
-    fn allocate_frame(&mut self) -> Option<PhysFrame> {
-        None
-    }
-}
-
-/// A FrameAllocator that returns usable frames from the bootloader's memory map.
-pub struct BootInfoFrameAllocator {
-    memory_map: &'static MemoryMap,
-    next: usize,
-}
-
-impl BootInfoFrameAllocator {
-    /// Create a FrameAllocator from the passed memory map.
-    ///
-    /// This function is unsafe because the caller must guarantee that the passed
-    /// memory map is valid. The main requirement is that all frames that are marked
-    /// as `USABLE` in it are really unused.
-    pub unsafe fn init(memory_map: &'static MemoryMap) -> Self {
-        BootInfoFrameAllocator {
-            memory_map,
-            next: 0,
-        }
-    }
-
-    /// Returns an iterator over the usable frames specified in the memory map.
-    fn usable_frames(&self) -> impl Iterator<Item = PhysFrame> {
-        // get usable regions from memory map
-        let regions = self.memory_map.iter();
-        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());
-        // 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
-        frame_addresses.map(|addr| PhysFrame::containing_address(PhysAddr::new(addr)))
-    }
-}
-
-unsafe impl FrameAllocator<Size4KiB> for BootInfoFrameAllocator {
-    fn allocate_frame(&mut self) -> Option<PhysFrame> {
-        let frame = self.usable_frames().nth(self.next);
-        self.next += 1;
-        frame
-    }
-}

src/serial.rs

@@ -13,14 +13,10 @@ lazy_static! {
 #[doc(hidden)]
 pub fn _print(args: ::core::fmt::Arguments) {
     use core::fmt::Write;
-    use x86_64::instructions::interrupts;
-
-    interrupts::without_interrupts(|| {
-        SERIAL1
-            .lock()
-            .write_fmt(args)
-            .expect("Printing to serial failed");
-    });
+    SERIAL1
+        .lock()
+        .write_fmt(args)
+        .expect("Printing to serial failed");
 }
 
 /// Prints to the host through the serial interface.

src/vga_buffer.rs

@@ -163,16 +163,11 @@ macro_rules! println {
     ($($arg:tt)*) => ($crate::print!("{}\n", format_args!($($arg)*)));
 }
 
-/// Prints the given formatted string to the VGA text buffer
-/// through the global `WRITER` instance.
+/// Prints the given formatted string to the VGA text buffer through the global `WRITER` instance.
 #[doc(hidden)]
 pub fn _print(args: fmt::Arguments) {
     use core::fmt::Write;
-    use x86_64::instructions::interrupts;
-
-    interrupts::without_interrupts(|| {
-        WRITER.lock().write_fmt(args).unwrap();
-    });
+    WRITER.lock().write_fmt(args).unwrap();
 }
 
 #[test_case]
@@ -189,16 +184,10 @@ fn test_println_many() {
 
 #[test_case]
 fn test_println_output() {
-    use core::fmt::Write;
-    use x86_64::instructions::interrupts;
-
     let s = "Some test string that fits on a single line";
-    interrupts::without_interrupts(|| {
-        let mut writer = WRITER.lock();
-        writeln!(writer, "\n{}", s).expect("writeln failed");
-        for (i, c) in s.chars().enumerate() {
-            let screen_char = writer.buffer.chars[BUFFER_HEIGHT - 2][i].read();
-            assert_eq!(char::from(screen_char.ascii_character), c);
-        }
-    });
+    println!("{}", s);
+    for (i, c) in s.chars().enumerate() {
+        let screen_char = WRITER.lock().buffer.chars[BUFFER_HEIGHT - 2][i].read();
+        assert_eq!(char::from(screen_char.ascii_character), c);
+    }
 }

x86_64-blog_os.json

@@ -3,7 +3,7 @@
     "data-layout": "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128",
     "arch": "x86_64",
     "target-endian": "little",
-    "target-pointer-width": "64",
+    "target-pointer-width": 64,
     "target-c-int-width": 32,
     "os": "none",
     "executables": true,