initial commit

.cargo/config.toml

@@ -0,0 +1,9 @@
+[build]
+target = "x86_64-rustos.json" # target OS specifications
+
+[target.'cfg(target_os="none")']
+runner = "bootimage runner" # run with QEMU
+
+[unstable]
+build-std = ["core", "compiler_builtins"]
+build-std-features = ["compiler-builtins-mem"]

.gitignore

@@ -0,0 +1 @@
+/target

Cargo.lock

@@ -0,0 +1,118 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "bit_field"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc827186963e592360843fb5ba4b973e145841266c1357f7180c43526f2e5b61"
+
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
+[[package]]
+name = "bitflags"
+version = "2.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c8214115b7bf84099f1309324e63141d4c5d7cc26862f97a0a857dbefe165bd"
+
+[[package]]
+name = "bootloader"
+version = "0.9.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "974e79cf1b0b737839f01330fb5393095daf1124d52693696494e32523ae9ef5"
+
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+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 = "rustos"
+version = "0.1.0"
+dependencies = [
+ "bootloader",
+ "lazy_static",
+ "pc-keyboard",
+ "pic8259",
+ "spin 0.5.2",
+ "uart_16550",
+ "volatile 0.2.7",
+ "x86_64",
+]
+
+[[package]]
+name = "rustversion"
+version = "1.0.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eded382c5f5f786b989652c49544c4877d9f015cc22e145a5ea8ea66c2921cd2"
+
+[[package]]
+name = "spin"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
+
+[[package]]
+name = "spin"
+version = "0.9.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
+
+[[package]]
+name = "uart_16550"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "614ff2a87880d4bd4374722268598a970bbad05ced8bf630439417347254ab2e"
+dependencies = [
+ "bitflags 1.3.2",
+ "rustversion",
+ "x86_64",
+]
+
+[[package]]
+name = "volatile"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f6b06ad3ed06fef1713569d547cdbdb439eafed76341820fb0e0344f29a41945"
+
+[[package]]
+name = "volatile"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "442887c63f2c839b346c192d047a7c87e73d0689c9157b00b53dcc27dd5ea793"
+
+[[package]]
+name = "x86_64"
+version = "0.14.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c101112411baafbb4bf8d33e4c4a80ab5b02d74d2612331c61e8192fc9710491"
+dependencies = [
+ "bit_field",
+ "bitflags 2.9.0",
+ "rustversion",
+ "volatile 0.4.6",
+]

Cargo.toml

@@ -0,0 +1,34 @@
+[package]
+name = "rustos"
+version = "0.1.0"
+edition = "2024"
+authors = [ "mtgmonkey" ]
+
+# Special debug shutdown device in QEMU
+[package.metadata.bootimage]
+test-args = ["-device", "isa-debug-exit,iobase=0xf4,iosize=0x04", 
+"-serial", "stdio",
+"-display", "none"]
+test-success-exit-code = 33 # (0x10 << 1) | 1
+test-timeout = 30 # in seconds
+
+[dependencies]
+bootloader = { version = "0.9", features = ["map_physical_memory"] }
+pc-keyboard = "0.7.0"
+pic8259 = "0.10.1"
+spin = "0.5.2"
+uart_16550 = "0.2.0"
+volatile = "0.2.6"
+x86_64 = "0.14.2"
+
+[dependencies.lazy_static]
+version = "1.0"
+features = ["spin_no_std"]
+
+[[test]]
+name = "should_panic"
+harness = false
+
+[[test]]
+name = "stack_overflow"
+harness = false

rust-toolchain

@@ -0,0 +1 @@
+nightly

shell.nix

@@ -0,0 +1,8 @@
+{ pkgs ? import <nixpkgs> {  } }:
+pkgs.mkShell {
+  nativeBuildInputs = [
+    pkgs.qemu
+    pkgs.rustup
+  ];
+  RUST_SRC_PATH = "${pkgs.rust.packages.stable.rustPlatform.rustLibSrc}";
+}

src/gdt.rs

@@ -0,0 +1,53 @@
+use lazy_static::lazy_static;
+use x86_64::structures::gdt::{Descriptor, GlobalDescriptorTable, SegmentSelector};
+use x86_64::structures::tss::TaskStateSegment;
+use x86_64::VirtAddr;
+
+struct Selectors {
+    code_selector: SegmentSelector,
+    tss_selector: SegmentSelector,
+}
+
+lazy_static! {
+    static ref GDT: (GlobalDescriptorTable, Selectors) = {
+        let mut gdt = GlobalDescriptorTable::new();
+        // SAFETY ensure these values are safe in init()
+        let code_selector = gdt.add_entry(Descriptor::kernel_code_segment());
+        let tss_selector = gdt.add_entry(Descriptor::tss_segment(&TSS));
+        (
+            gdt,
+            Selectors {
+                code_selector,
+                tss_selector,
+            },
+        )
+    };
+}
+
+// IST index to use for double fault stack
+pub const DOUBLE_FAULT_IST_INDEX: u16 = 0;
+
+lazy_static! {
+    static ref TSS: TaskStateSegment = {
+        let mut tss = TaskStateSegment::new();
+        tss.interrupt_stack_table[DOUBLE_FAULT_IST_INDEX as usize] = {
+            const STACK_SIZE: usize = 4096 * 5;
+            static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE]; // TODO make real stack
+            let stack_start = VirtAddr::from_ptr(&raw const STACK);
+            let stack_end = stack_start + STACK_SIZE;
+            stack_end
+        };
+        tss
+    };
+}
+
+pub fn init() {
+    use x86_64::instructions::segmentation::{Segment, CS};
+    use x86_64::instructions::tables::load_tss;
+    GDT.0.load();
+    // SAFETY ensure GDT returns the right values
+    unsafe {
+        CS::set_reg(GDT.1.code_selector);
+        load_tss(GDT.1.tss_selector);
+    }
+}

src/interrupts.rs

@@ -0,0 +1,125 @@
+use crate::{gdt, hlt_loop, print, 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())
+    }
+}
+
+// set offsets for PICs
+// SAFETY
+pub static PICS: spin::Mutex<ChainedPics> =
+    spin::Mutex::new(unsafe { ChainedPics::new(PIC_1_OFFSET, PIC_2_OFFSET) });
+
+// only init idt in memory when first referred to
+// allows static mut
+lazy_static! {
+    static ref IDT: InterruptDescriptorTable = {
+        let mut idt = InterruptDescriptorTable::new();
+        idt.breakpoint.set_handler_fn(breakpoint_handler);
+        // SAFETY ensure index is valid and not passed to any other exceptions
+        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.page_fault.set_handler_fn(page_fault_handler);
+        idt
+    };
+}
+
+// handle breakpoint exceptions
+extern "x86-interrupt" fn breakpoint_handler(stack_frame: InterruptStackFrame) {
+    println!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
+}
+
+// handle double fault exceptions
+extern "x86-interrupt" fn double_fault_handler(
+    stack_frame: InterruptStackFrame,
+    _error_code: u64,
+) -> ! {
+    panic!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
+}
+
+// init idt
+pub fn init_idt() {
+    IDT.load();
+}
+
+extern "x86-interrupt" fn keyboard_interrupt_handler(_keyboard_stack_frame: InterruptStackFrame) {
+    use pc_keyboard::{layouts, DecodedKey, HandleControl, Keyboard, ScancodeSet1};
+    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());
+    }
+}
+
+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();
+}
+
+// forcefully throws breakpoint exception
+#[test_case]
+fn test_breakpoint_exception() {
+    x86_64::instructions::interrupts::int3();
+}
+
+extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: InterruptStackFrame) {
+    print!(".");
+    unsafe {
+        PICS.lock()
+            .notify_end_of_interrupt(InterruptIndex::Timer.as_u8());
+    };
+}

src/lib.rs

@@ -0,0 +1,93 @@
+#![no_std]
+#![cfg_attr(test, no_main)]
+#![feature(abi_x86_interrupt)]
+#![feature(custom_test_frameworks)]
+#![test_runner(test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+pub mod gdt;
+pub mod interrupts;
+pub mod serial;
+pub mod vga_buffer;
+
+use core::panic::PanicInfo;
+
+// wizardry for Testable Fn() type
+pub trait Testable {
+    fn run(&self) -> ();
+}
+
+impl<T> Testable for T
+where
+    T: Fn(),
+{
+    fn run(&self) {
+        serial_print!("{}...\t", core::any::type_name::<T>());
+        self();
+        serial_println!("[ok]");
+    }
+}
+
+// defines QemuExitCodes
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u32)]
+pub enum QemuExitCode {
+    Success = 0x10,
+    Failed = 0x11,
+}
+
+#[cfg(test)]
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    init();
+    test_main();
+    hlt_loop();
+}
+
+// exits qemu with an exit code
+// qemu has special escape port at 0xf4
+pub fn exit_qemu(exit_code: QemuExitCode) {
+    use x86_64::instructions::port::Port;
+    unsafe {
+        let mut port = Port::new(0xf4);
+        port.write(exit_code as u32);
+    }
+}
+
+pub fn hlt_loop() -> ! {
+    loop {
+        x86_64::instructions::hlt();
+    }
+}
+// common init fn for kernel
+pub fn init() {
+    gdt::init();
+    interrupts::init_idt();
+    // SAFETY ensure the PICs are properly defined in interrupts.rs
+    unsafe { interrupts::PICS.lock().initialize() };
+    x86_64::instructions::interrupts::enable();
+}
+
+// prints error code for failed test and exits qemu with a failure
+pub fn test_panic_handler(info: &PanicInfo) -> ! {
+    serial_println!("[failed]\n");
+    serial_println!("Error: {}\n", info);
+    exit_qemu(QemuExitCode::Failed);
+    hlt_loop();
+}
+
+// runs tests
+pub fn test_runner(tests: &[&dyn Testable]) {
+    serial_println!("Running {} tests", tests.len());
+    for test in tests {
+        test.run();
+    }
+    exit_qemu(QemuExitCode::Success);
+}
+
+// called on panic
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    test_panic_handler(info)
+}

src/main.rs

@@ -0,0 +1,47 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(rustos::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use core::panic::PanicInfo;
+use rustos::println;
+
+// SAFETY: make sure no other global fn _start exists
+// called on start
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    println!("Hello World{}", "!");
+    rustos::init(); // initializes kernel
+
+    use x86_64::registers::control::Cr3;
+
+    let (level_4_page_table, _) = Cr3::read();
+    println!(
+        "Level 4 page table at: {:?}",
+        level_4_page_table.start_address()
+    );
+
+    #[cfg(test)]
+    test_main();
+
+    println!("Hey, it didn't crash!");
+    rustos::hlt_loop();
+}
+
+// called on test panic
+// prints to console error message
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    rustos::test_panic_handler(info)
+}
+
+// called on panic
+// prints to vga error message
+#[cfg(not(test))]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    println!("{}", info);
+    rustos::hlt_loop();
+}

src/serial.rs

@@ -0,0 +1,35 @@
+use lazy_static::lazy_static;
+use spin::Mutex;
+use uart_16550::SerialPort;
+
+#[macro_export]
+macro_rules! serial_print {
+  ($($arg:tt)*) => { $crate::serial::_print(format_args!($($arg)*)); };
+}
+
+#[macro_export]
+macro_rules! serial_println {
+  () => ($crate::serial_print!("\n"));
+  ($fmt:expr) => ($crate::serial_print!(concat!($fmt, "\n")));
+  ($fmt:expr, $($arg:tt)*) => ($crate::serial_print!( concat!($fmt, "\n"), $($arg)*));
+}
+
+lazy_static! {
+    pub static ref SERIAL1: Mutex<SerialPort> = {
+        let mut serial_port = unsafe { SerialPort::new(0x3F8) };
+        serial_port.init();
+        Mutex::new(serial_port)
+    };
+}
+
+#[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");
+    });
+}

src/vga_buffer.rs

@@ -0,0 +1,191 @@
+use core::fmt;
+use lazy_static::lazy_static;
+use spin::Mutex;
+use volatile::Volatile;
+
+// macros exported on root ie $crate::print
+#[macro_export]
+macro_rules! print {
+  ($($arg:tt)*) => ($crate::vga_buffer::_print(format_args!($($arg)*)));
+}
+
+#[macro_export]
+macro_rules! println {
+  () => ($crate::print!("\n"));
+  ($($arg:tt)*) => ($crate::print!("{}\n", format_args!($($arg)*)));
+}
+
+// program ignores unused code
+// enable semantics for the type
+// represent it as u8
+#[allow(dead_code)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u8)]
+pub enum Color {
+    Black = 0,
+    Blue = 1,
+    Green = 2,
+    Cyan = 3,
+    Red = 4,
+    Magenta = 5,
+    Brown = 6,
+    LightGray = 7,
+    DarkGray = 8,
+    LightBlue = 9,
+    LightGreen = 10,
+    LightCyan = 11,
+    LightRed = 12,
+    Pink = 13,
+    Yellow = 14,
+    White = 15,
+}
+
+const BUFFER_HEIGHT: usize = 25;
+const BUFFER_WIDTH: usize = 80;
+
+#[repr(transparent)]
+struct Buffer {
+    chars: [[Volatile<ScreenChar>; BUFFER_WIDTH]; BUFFER_HEIGHT],
+}
+
+// full byte color code
+// repr(transparent) ensures struct has same memory layout as type, in this case u8
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(transparent)]
+struct ColorCode(u8);
+
+// implementation of colorCode
+impl ColorCode {
+    fn new(foreground: Color, background: Color) -> ColorCode {
+        ColorCode((background as u8) << 4 | (foreground as u8))
+    }
+}
+
+// uses C-like struct to gurantee field ordering
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(C)]
+struct ScreenChar {
+    ascii_character: u8,
+    color_code: ColorCode,
+}
+
+// 'static tells the runtime how long the reference is valid; 'static is forever
+pub struct Writer {
+    column_position: usize,
+    color_code: ColorCode,
+    buffer: &'static mut Buffer,
+}
+
+impl Writer {
+    // writes byte to screen, automatically handling newlines
+    // expects a printable byte
+    pub fn write_byte(&mut self, byte: u8) {
+        match byte {
+            b'\n' => self.new_line(),
+            byte => {
+                if self.column_position >= BUFFER_WIDTH {
+                    self.new_line();
+                }
+
+                let row = BUFFER_HEIGHT - 1;
+                let col = self.column_position;
+
+                // .write with Volatile<ScreenChar> ensures this will never be optimised away
+                let color_code = self.color_code;
+                self.buffer.chars[row][col].write(ScreenChar {
+                    ascii_character: byte,
+                    color_code,
+                });
+                self.column_position += 1;
+            }
+        }
+    }
+    // doesn't expect printable bytes
+    pub fn write_string(&mut self, s: &str) {
+        for byte in s.bytes() {
+            match byte {
+                0x20..=0x7e | b'\n' => self.write_byte(byte),
+                // filters out non-printable bytes
+                _ => self.write_byte(0xfe),
+            }
+        }
+    }
+    // iterates each character 1 row up and replaces cursor
+    fn new_line(&mut self) {
+        for row in 1..BUFFER_HEIGHT {
+            for col in 0..BUFFER_WIDTH {
+                let character = self.buffer.chars[row][col].read();
+                self.buffer.chars[row - 1][col].write(character);
+            }
+        }
+        self.clear_row(BUFFER_HEIGHT - 1);
+        self.column_position = 0;
+    }
+    // overwrites a row with spaces
+    fn clear_row(&mut self, row: usize) {
+        let blank = ScreenChar {
+            ascii_character: b' ',
+            color_code: self.color_code,
+        };
+        for col in 0..BUFFER_WIDTH {
+            self.buffer.chars[row][col].write(blank);
+        }
+    }
+}
+
+// required by fmt: write_str (self, str) -> fmt::Result
+impl fmt::Write for Writer {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write_string(s);
+        Ok(())
+    }
+}
+
+// static WRITER evaluates lazily
+lazy_static! {
+  // spin Mutex 'locks' thread without OS features
+  pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
+    column_position: 0,
+    color_code: ColorCode::new(Color::Magenta, Color::Black),
+    buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
+  });
+}
+
+// hides from generated docs despite publicity
+#[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();
+    });
+}
+
+#[test_case]
+fn test_println_many() {
+    for _ in 0..1023 {
+        println!("test_println_many output");
+    }
+}
+
+#[test_case]
+fn test_println_output() {
+    use core::fmt::Write;
+    use x86_64::instructions::interrupts;
+
+    let s = "Some test string that fits in a single line";
+    interrupts::without_interrupts(|| {
+        // prevent race condition where an exception prints while it io
+        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);
+        }
+    });
+}
+
+#[test_case]
+fn test_println_simple() {
+    println!("test_println_simple output");
+}

tests/basic_boot.rs

@@ -0,0 +1,24 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(rustos::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use core::panic::PanicInfo;
+use rustos::println;
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+  test_main();
+  loop {}
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+  rustos::test_panic_handler(info)
+}
+
+#[test_case]
+fn test_println() {
+  println!("test_println output");
+}

tests/should_panic.rs

@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+
+use core::panic::PanicInfo;
+use rustos::{QemuExitCode, exit_qemu, serial_print, serial_println};
+
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+  serial_println!("[ok]");
+  exit_qemu(QemuExitCode::Success);
+  loop {}
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+  should_fail();
+  serial_println!("[test did not panic]");
+  exit_qemu(QemuExitCode::Failed);
+  loop {}
+}
+
+fn should_fail() {
+  serial_print!("should_panic::should_fail...\t");
+  assert_eq!(0, 1);
+}

tests/stack_overflow.rs

@@ -0,0 +1,55 @@
+#![no_std]
+#![no_main]
+#![feature(abi_x86_interrupt)]
+
+use core::panic::PanicInfo;
+use lazy_static::lazy_static;
+use rustos::{exit_qemu, serial_print, serial_println, QemuExitCode};
+use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
+
+lazy_static! {
+    static ref TEST_IDT: InterruptDescriptorTable = {
+        let mut idt = InterruptDescriptorTable::new();
+        unsafe {
+            idt.double_fault
+                .set_handler_fn(test_double_fault_handler)
+                .set_stack_index(rustos::gdt::DOUBLE_FAULT_IST_INDEX);
+        }
+        idt
+    };
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    serial_print!("stack_overflow::stack_overflow...\t");
+
+    rustos::gdt::init();
+    init_test_idt();
+    stack_overflow();
+
+    panic!("Execution continued after stack overflow");
+}
+
+pub fn init_test_idt() {
+    TEST_IDT.load();
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    rustos::test_panic_handler(info)
+}
+
+#[allow(unconditional_recursion)]
+fn stack_overflow() {
+    stack_overflow();
+    volatile::Volatile::new(0).read(); // prevent optimizations
+}
+
+extern "x86-interrupt" fn test_double_fault_handler(
+    _stack_frame: InterruptStackFrame,
+    _error_code: u64,
+) -> ! {
+    serial_println!("[ok]");
+    exit_qemu(QemuExitCode::Success);
+    loop {}
+}

x86_64-rustos.json

@@ -0,0 +1,19 @@
+{
+  "llvm-target": "x86_64-unknown-none",
+  "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-c-int-width": "32",
+  "os": "none",
+  "executables": true,
+
+  "features": "-mmx,-sse,+soft-float",
+  "rustc-abi": "x86-softfloat",
+
+  "disable-redzone": true,
+  "panic-strategy": "abort",
+
+  "linker-flavor": "ld.lld",
+  "linker": "rust-lld"
+}