Merge branch 'post-04' into post-05

Set `test=true` to enable `main.rs` testing again

.github/workflows/code.yml

@@ -67,6 +67,31 @@ jobs:
         with:
           command: bootimage
 
+      # install QEMU
+      - name: Install QEMU (Linux)
+        run: sudo apt update && sudo apt install qemu-system-x86
+        if: runner.os == 'Linux'
+      - name: Install QEMU (macOS)
+        run: brew install qemu
+        if: runner.os == 'macOS'
+        env:
+          HOMEBREW_NO_AUTO_UPDATE: 1
+          HOMEBREW_NO_BOTTLE_SOURCE_FALLBACK: 1
+          HOMEBREW_NO_INSTALL_CLEANUP: 1
+      - name: Install QEMU (Windows)
+        run: |
+          choco install qemu --version 2021.5.5
+          echo "$Env:Programfiles\qemu" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+        if: runner.os == 'Windows'
+        shell: pwsh
+      - name: "Print QEMU Version"
+        run: qemu-system-x86_64 --version
+
+      - name: Run `cargo test`
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+
   check_formatting:
     name: Check Formatting
     runs-on: ubuntu-latest

Cargo.lock

@@ -2,6 +2,24 @@
 # 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 = "2.9.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a65b545ab31d687cff52899d4890855fec459eb6afe0da6417b8a18da87aa29"
+
 [[package]]
 name = "blog_os"
 version = "0.1.0"
@@ -9,7 +27,9 @@ dependencies = [
  "bootloader",
  "lazy_static",
  "spin 0.5.2",
- "volatile",
+ "uart_16550",
+ "volatile 0.2.7",
+ "x86_64",
 ]
 
 [[package]]
@@ -27,6 +47,12 @@ dependencies = [
  "spin 0.9.8",
 ]
 
+[[package]]
+name = "rustversion"
+version = "1.0.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b39cdef0fa800fc44525c84ccb54a029961a8215f9619753635a9c0d2538d46d"
+
 [[package]]
 name = "spin"
 version = "0.5.2"
@@ -39,8 +65,37 @@ 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 2.9.2",
+ "rustversion",
+ "volatile 0.4.6",
+]

Cargo.toml

@@ -4,10 +4,16 @@ version = "0.1.0"
 authors = ["Philipp Oppermann <dev@phil-opp.com>"]
 edition = "2024"
 
+[[test]]
+name = "should_panic"
+harness = false
+
 [dependencies]
 bootloader = "0.9"
 volatile = "0.2.6"
 spin = "0.5.2"
+x86_64 = "0.14.2"
+uart_16550 = "0.2.0"
 
 [dependencies.lazy_static]
 version = "1.0"
@@ -15,5 +21,17 @@ features = ["spin_no_std"]
 
 [[bin]]
 name = "blog_os"
-test = false
+test = true
 bench = false
+
+
+[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

README.md

@@ -1,10 +1,10 @@
-# Blog OS (VGA Text Mode)
+# Blog OS (CPU Exceptions)
 
-[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-03)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-03)
+[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-05)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-05)
 
-This repository contains the source code for the [VGA Text Mode][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
+This repository contains the source code for the [CPU Exceptions][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
 
-[post]: https://os.phil-opp.com/vga-text-mode/
+[post]: https://os.phil-opp.com/cpu-exceptions/
 
 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**
 
@@ -56,6 +56,10 @@ dd if=target/x86_64-blog_os/debug/bootimage-blog_os.bin of=/dev/sdX && sync
 
 Where `sdX` is the device name of your USB stick. **Be careful** to choose the correct device name, because everything on that device is overwritten.
 
+## Testing
+
+To run the unit and integration tests, execute `cargo xtest`.
+
 ## License
 
 Licensed under either of

src/interrupts.rs

@@ -0,0 +1,25 @@
+use crate::println;
+use lazy_static::lazy_static;
+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
+    };
+}
+
+pub fn init_idt() {
+    IDT.load();
+}
+
+extern "x86-interrupt" fn breakpoint_handler(stack_frame: InterruptStackFrame) {
+    println!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
+}
+
+#[test_case]
+fn test_breakpoint_exception() {
+    // invoke a breakpoint exception
+    x86_64::instructions::interrupts::int3();
+}

src/lib.rs

@@ -0,0 +1,76 @@
+#![no_std]
+#![cfg_attr(test, no_main)]
+#![feature(custom_test_frameworks)]
+#![feature(abi_x86_interrupt)]
+#![test_runner(crate::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use core::panic::PanicInfo;
+
+pub mod interrupts;
+pub mod serial;
+pub mod vga_buffer;
+
+pub fn init() {
+    interrupts::init_idt();
+}
+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]");
+    }
+}
+
+pub fn test_runner(tests: &[&dyn Testable]) {
+    serial_println!("Running {} tests", tests.len());
+    for test in tests {
+        test.run();
+    }
+    exit_qemu(QemuExitCode::Success);
+}
+
+pub fn test_panic_handler(info: &PanicInfo) -> ! {
+    serial_println!("[failed]\n");
+    serial_println!("Error: {}\n", info);
+    exit_qemu(QemuExitCode::Failed);
+    loop {}
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u32)]
+pub enum QemuExitCode {
+    Success = 0x10,
+    Failed = 0x11,
+}
+
+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);
+    }
+}
+
+/// Entry point for `cargo xtest`
+#[cfg(test)]
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    init();
+    test_main();
+    loop {}
+}
+
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    test_panic_handler(info)
+}

src/main.rs

@@ -1,20 +1,43 @@
 #![no_std]
 #![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(blog_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]
 
+use blog_os::println;
 use core::panic::PanicInfo;
 
-mod vga_buffer;
-
 #[unsafe(no_mangle)]
 pub extern "C" fn _start() -> ! {
     println!("Hello World{}", "!");
 
+    blog_os::init();
+
+    // invoke a breakpoint exception
+    x86_64::instructions::interrupts::int3();
+
+    #[cfg(test)]
+    test_main();
+
+    println!("It did not crash!");
     loop {}
 }
 
 /// This function is called on panic.
+#[cfg(not(test))]
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
     println!("{}", info);
     loop {}
 }
+
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    blog_os::test_panic_handler(info)
+}
+
+#[test_case]
+fn trivial_assertion() {
+    assert_eq!(1, 1);
+}

src/serial.rs

@@ -0,0 +1,37 @@
+use lazy_static::lazy_static;
+use spin::Mutex;
+use uart_16550::SerialPort;
+
+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;
+    SERIAL1
+        .lock()
+        .write_fmt(args)
+        .expect("Printing to serial failed");
+}
+
+/// Prints to the host through the serial interface.
+#[macro_export]
+macro_rules! serial_print {
+    ($($arg:tt)*) => {
+        $crate::serial::_print(format_args!($($arg)*));
+    };
+}
+
+/// Prints to the host through the serial interface, appending a newline.
+#[macro_export]
+macro_rules! serial_println {
+    () => ($crate::serial_print!("\n"));
+    ($fmt:expr) => ($crate::serial_print!(concat!($fmt, "\n")));
+    ($fmt:expr, $($arg:tt)*) => ($crate::serial_print!(
+        concat!($fmt, "\n"), $($arg)*));
+}

src/vga_buffer.rs

@@ -169,3 +169,25 @@ pub fn _print(args: fmt::Arguments) {
     use core::fmt::Write;
     WRITER.lock().write_fmt(args).unwrap();
 }
+
+#[test_case]
+fn test_println_simple() {
+    println!("test_println_simple output");
+}
+
+#[test_case]
+fn test_println_many() {
+    for _ in 0..200 {
+        println!("test_println_many output");
+    }
+}
+
+#[test_case]
+fn test_println_output() {
+    let s = "Some test string that fits on a single line";
+    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);
+    }
+}

tests/basic_boot.rs

@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(blog_os::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use blog_os::println;
+use core::panic::PanicInfo;
+
+#[unsafe(no_mangle)] // don't mangle the name of this function
+pub extern "C" fn _start() -> ! {
+    test_main();
+
+    loop {}
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    blog_os::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 blog_os::{QemuExitCode, exit_qemu, serial_print, serial_println};
+use core::panic::PanicInfo;
+
+#[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);
+}
+
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    serial_println!("[ok]");
+    exit_qemu(QemuExitCode::Success);
+    loop {}
+}