Merge branch 'post-07' into post-08

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

Cargo.lock

@@ -26,6 +26,8 @@ version = "0.1.0"
 dependencies = [
  "bootloader",
  "lazy_static",
+ "pc-keyboard",
+ "pic8259",
  "spin 0.5.2",
  "uart_16550",
  "volatile 0.2.7",
@@ -34,9 +36,9 @@ 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"
@@ -47,6 +49,21 @@ 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

@@ -8,12 +8,18 @@ edition = "2024"
 name = "should_panic"
 harness = false
 
+[[test]]
+name = "stack_overflow"
+harness = false
+
 [dependencies]
 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"
@@ -21,7 +27,7 @@ features = ["spin_no_std"]
 
 [[bin]]
 name = "blog_os"
-test = false
+test = true
 bench = false
 
 

README.md

@@ -1,10 +1,10 @@
-# Blog OS (Testing)
+# Blog OS (Introduction to Paging)
 
-[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-04)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-04)
+[![Build Status](https://github.com/phil-opp/blog_os/workflows/Code/badge.svg?branch=post-08)](https://github.com/phil-opp/blog_os/actions?query=workflow%3A%22Code%22+branch%3Apost-08)
 
-This repository contains the source code for the [Testing][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
+This repository contains the source code for the [Introduction to Paging][post] post of the [Writing an OS in Rust](https://os.phil-opp.com) series.
 
-[post]: https://os.phil-opp.com/testing/
+[post]: https://os.phil-opp.com/paging-introduction/
 
 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**
 

src/gdt.rs

@@ -0,0 +1,52 @@
+use lazy_static::lazy_static;
+use x86_64::VirtAddr;
+use x86_64::structures::gdt::{Descriptor, GlobalDescriptorTable, SegmentSelector};
+use x86_64::structures::tss::TaskStateSegment;
+
+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];
+
+            let stack_start = VirtAddr::from_ptr(&raw const STACK);
+            let stack_end = stack_start + STACK_SIZE;
+            stack_end
+        };
+        tss
+    };
+}
+
+lazy_static! {
+    static ref GDT: (GlobalDescriptorTable, Selectors) = {
+        let mut gdt = GlobalDescriptorTable::new();
+        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,
+            },
+        )
+    };
+}
+
+struct Selectors {
+    code_selector: SegmentSelector,
+    tss_selector: SegmentSelector,
+}
+
+pub fn init() {
+    use x86_64::instructions::segmentation::{CS, Segment};
+    use x86_64::instructions::tables::load_tss;
+
+    GDT.0.load();
+    unsafe {
+        CS::set_reg(GDT.1.code_selector);
+        load_tss(GDT.1.tss_selector);
+    }
+}

src/interrupts.rs

@@ -0,0 +1,119 @@
+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())
+    }
+}
+
+pub static PICS: spin::Mutex<ChainedPics> =
+    spin::Mutex::new(unsafe { ChainedPics::new(PIC_1_OFFSET, PIC_2_OFFSET) });
+
+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
+    };
+}
+
+pub fn init_idt() {
+    IDT.load();
+}
+
+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,
+) -> ! {
+    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
+    x86_64::instructions::interrupts::int3();
+}

src/lib.rs

@@ -1,14 +1,23 @@
 #![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 gdt;
+pub mod interrupts;
 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) -> ();
 }
@@ -36,7 +45,7 @@ pub fn test_panic_handler(info: &PanicInfo) -> ! {
     serial_println!("[failed]\n");
     serial_println!("Error: {}\n", info);
     exit_qemu(QemuExitCode::Failed);
-    loop {}
+    hlt_loop();
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -55,12 +64,19 @@ pub fn exit_qemu(exit_code: QemuExitCode) {
     }
 }
 
+pub fn hlt_loop() -> ! {
+    loop {
+        x86_64::instructions::hlt();
+    }
+}
+
 /// Entry point for `cargo xtest`
 #[cfg(test)]
 #[unsafe(no_mangle)]
 pub extern "C" fn _start() -> ! {
+    init();
     test_main();
-    loop {}
+    hlt_loop();
 }
 
 #[cfg(test)]

src/main.rs

@@ -9,12 +9,22 @@ use core::panic::PanicInfo;
 
 #[unsafe(no_mangle)]
 pub extern "C" fn _start() -> ! {
+    use x86_64::registers::control::Cr3;
     println!("Hello World{}", "!");
 
+    blog_os::init();
+
+    let (level_4_page_table, _) = Cr3::read();
+    println!(
+        "Level 4 page table at: {:?}",
+        level_4_page_table.start_address()
+    );
+
     #[cfg(test)]
     test_main();
 
-    loop {}
+    println!("It did not crash!");
+    blog_os::hlt_loop();
 }
 
 /// This function is called on panic.
@@ -22,7 +32,7 @@ pub extern "C" fn _start() -> ! {
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
     println!("{}", info);
-    loop {}
+    blog_os::hlt_loop();
 }
 
 #[cfg(test)]

src/serial.rs

@@ -13,10 +13,14 @@ lazy_static! {
 #[doc(hidden)]
 pub fn _print(args: ::core::fmt::Arguments) {
     use core::fmt::Write;
-    SERIAL1
+    use x86_64::instructions::interrupts;
-        .lock()
+
-        .write_fmt(args)
+    interrupts::without_interrupts(|| {
-        .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

@@ -163,11 +163,16 @@ 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;
-    WRITER.lock().write_fmt(args).unwrap();
+    use x86_64::instructions::interrupts;
+
+    interrupts::without_interrupts(|| {
+        WRITER.lock().write_fmt(args).unwrap();
+    });
 }
 
 #[test_case]
@@ -184,10 +189,16 @@ 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";
-    println!("{}", s);
+    interrupts::without_interrupts(|| {
-    for (i, c) in s.chars().enumerate() {
+        let mut writer = WRITER.lock();
-        let screen_char = WRITER.lock().buffer.chars[BUFFER_HEIGHT - 2][i].read();
+        writeln!(writer, "\n{}", s).expect("writeln failed");
-        assert_eq!(char::from(screen_char.ascii_character), c);
+        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);
+        }
+    });
 }

tests/stack_overflow.rs

@@ -0,0 +1,58 @@
+#![no_std]
+#![no_main]
+#![feature(abi_x86_interrupt)]
+
+use blog_os::{QemuExitCode, exit_qemu, serial_print, serial_println};
+use core::panic::PanicInfo;
+use lazy_static::lazy_static;
+use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
+
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    serial_print!("stack_overflow::stack_overflow...\t");
+
+    blog_os::gdt::init();
+    init_test_idt();
+
+    // trigger a stack overflow
+    stack_overflow();
+
+    panic!("Execution continued after stack overflow");
+}
+
+#[allow(unconditional_recursion)]
+fn stack_overflow() {
+    stack_overflow(); // for each recursion, the return address is pushed
+    volatile::Volatile::new(0).read(); // prevent tail recursion optimizations
+}
+
+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(blog_os::gdt::DOUBLE_FAULT_IST_INDEX);
+        }
+
+        idt
+    };
+}
+
+pub fn init_test_idt() {
+    TEST_IDT.load();
+}
+
+extern "x86-interrupt" fn test_double_fault_handler(
+    _stack_frame: InterruptStackFrame,
+    _error_code: u64,
+) -> ! {
+    serial_println!("[ok]");
+    exit_qemu(QemuExitCode::Success);
+    loop {}
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    blog_os::test_panic_handler(info)
+}

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,