Merge branch 'post-05' into post-06

Set CS register with non-deprecated function

Cargo.lock

@@ -4,21 +4,15 @@ version = 4
 
 [[package]]
 name = "bit_field"
-version = "0.10.2"
+version = "0.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dc827186963e592360843fb5ba4b973e145841266c1357f7180c43526f2e5b61"
+checksum = "dcb6dd1c2376d2e096796e234a70e17e94cc2d5d54ff8ce42b28cef1d0d359a4"
 
 [[package]]
 name = "bitflags"
-version = "1.3.2"
+version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
-
-[[package]]
-name = "bitflags"
-version = "2.9.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6a65b545ab31d687cff52899d4890855fec459eb6afe0da6417b8a18da87aa29"
 
 [[package]]
 name = "blog_os"
@@ -26,7 +20,7 @@ version = "0.1.0"
 dependencies = [
  "bootloader",
  "lazy_static",
- "spin 0.5.2",
+ "spin",
  "uart_16550",
  "volatile 0.2.7",
  "x86_64",
@@ -34,45 +28,32 @@ dependencies = [
 
 [[package]]
 name = "bootloader"
-version = "0.9.33"
+version = "0.9.30"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7bdfddac270bbdd45903296bc1caf29a7fdce6b326aaf0bbab7f04c5f98b7447"
+checksum = "8a9c8b93781debeb5bc44a12adc4be812aa9feb659d60eeafcd7e9bedb549561"
 
 [[package]]
 name = "lazy_static"
-version = "1.5.0"
+version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 dependencies = [
- "spin 0.9.8",
+ "spin",
 ]
 
-[[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"
 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"
+version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "614ff2a87880d4bd4374722268598a970bbad05ced8bf630439417347254ab2e"
+checksum = "503a6c0e6d82daa87985e662d120c0176b09587c92a68db22781b28ae95405dd"
 dependencies = [
- "bitflags 1.3.2",
+ "bitflags",
- "rustversion",
  "x86_64",
 ]
 
@@ -84,18 +65,17 @@ checksum = "f6b06ad3ed06fef1713569d547cdbdb439eafed76341820fb0e0344f29a41945"
 
 [[package]]
 name = "volatile"
-version = "0.4.6"
+version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "442887c63f2c839b346c192d047a7c87e73d0689c9157b00b53dcc27dd5ea793"
+checksum = "e4c2dbd44eb8b53973357e6e207e370f0c1059990df850aca1eca8947cf464f0"
 
 [[package]]
 name = "x86_64"
-version = "0.14.13"
+version = "0.14.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c101112411baafbb4bf8d33e4c4a80ab5b02d74d2612331c61e8192fc9710491"
+checksum = "fb611915c917c6296d11e23f71ff1ecfe49c5766daba92cd3df52df6b58285b6"
 dependencies = [
  "bit_field",
- "bitflags 2.9.2",
+ "bitflags",
- "rustversion",
+ "volatile 0.4.4",
- "volatile 0.4.6",
 ]

Cargo.toml

@@ -2,12 +2,16 @@
 name = "blog_os"
 version = "0.1.0"
 authors = ["Philipp Oppermann <dev@phil-opp.com>"]
-edition = "2024"
+edition = "2018"
 
 [[test]]
 name = "should_panic"
 harness = false
 
+[[test]]
+name = "stack_overflow"
+harness = false
+
 [dependencies]
 bootloader = "0.9"
 volatile = "0.2.6"
@@ -19,19 +23,10 @@ uart_16550 = "0.2.0"
 version = "1.0"
 features = ["spin_no_std"]
 
-[[bin]]
-name = "blog_os"
-test = true
-bench = false
-
 
 [package.metadata.bootimage]
 test-args = [
-    "-device",
+    "-device", "isa-debug-exit,iobase=0xf4,iosize=0x04", "-serial", "stdio",
-    "isa-debug-exit,iobase=0xf4,iosize=0x04",
+    "-display", "none"
-    "-serial",
-    "stdio",
-    "-display",
-    "none",
 ]
 test-success-exit-code = 33         # (0x10 << 1) | 1

README.md

@@ -1,10 +1,10 @@
-# Blog OS (CPU Exceptions)
+# Blog OS (Double Faults)
 
-[![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)
+[![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 [CPU Exceptions][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/cpu-exceptions/
+[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/gdt.rs

@@ -0,0 +1,52 @@
+use lazy_static::lazy_static;
+use x86_64::structures::gdt::{Descriptor, GlobalDescriptorTable, SegmentSelector};
+use x86_64::structures::tss::TaskStateSegment;
+use x86_64::VirtAddr;
+
+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::{Segment, CS};
+    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

@@ -1,4 +1,4 @@
-use crate::println;
+use crate::{gdt, println};
 use lazy_static::lazy_static;
 use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
 
@@ -6,6 +6,11 @@ lazy_static! {
     static ref IDT: InterruptDescriptorTable = {
         let mut idt = InterruptDescriptorTable::new();
         idt.breakpoint.set_handler_fn(breakpoint_handler);
+        unsafe {
+            idt.double_fault
+                .set_handler_fn(double_fault_handler)
+                .set_stack_index(gdt::DOUBLE_FAULT_IST_INDEX);
+        }
         idt
     };
 }
@@ -18,6 +23,13 @@ extern "x86-interrupt" fn breakpoint_handler(stack_frame: InterruptStackFrame) {
     println!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
 }
 
+extern "x86-interrupt" fn double_fault_handler(
+    stack_frame: InterruptStackFrame,
+    _error_code: u64,
+) -> ! {
+    panic!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
+}
+
 #[test_case]
 fn test_breakpoint_exception() {
     // invoke a breakpoint exception

src/lib.rs

@@ -7,11 +7,13 @@
 
 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();
 }
 pub trait Testable {
@@ -62,7 +64,7 @@ pub fn exit_qemu(exit_code: QemuExitCode) {
 
 /// Entry point for `cargo xtest`
 #[cfg(test)]
-#[unsafe(no_mangle)]
+#[no_mangle]
 pub extern "C" fn _start() -> ! {
     init();
     test_main();

src/main.rs

@@ -7,14 +7,18 @@
 use blog_os::println;
 use core::panic::PanicInfo;
 
-#[unsafe(no_mangle)]
+#[no_mangle]
 pub extern "C" fn _start() -> ! {
     println!("Hello World{}", "!");
 
     blog_os::init();
 
-    // invoke a breakpoint exception
+    fn stack_overflow() {
-    x86_64::instructions::interrupts::int3();
+        stack_overflow(); // for each recursion, the return address is pushed
+    }
+
+    // uncomment line below to trigger a stack overflow
+    // stack_overflow();
 
     #[cfg(test)]
     test_main();

tests/basic_boot.rs

@@ -7,7 +7,7 @@
 use blog_os::println;
 use core::panic::PanicInfo;
 
-#[unsafe(no_mangle)] // don't mangle the name of this function
+#[no_mangle] // don't mangle the name of this function
 pub extern "C" fn _start() -> ! {
     test_main();
 

tests/should_panic.rs

@@ -1,10 +1,10 @@
 #![no_std]
 #![no_main]
 
-use blog_os::{QemuExitCode, exit_qemu, serial_print, serial_println};
+use blog_os::{exit_qemu, serial_print, serial_println, QemuExitCode};
 use core::panic::PanicInfo;
 
-#[unsafe(no_mangle)]
+#[no_mangle]
 pub extern "C" fn _start() -> ! {
     should_fail();
     serial_println!("[test did not panic]");

tests/stack_overflow.rs

@@ -0,0 +1,58 @@
+#![no_std]
+#![no_main]
+#![feature(abi_x86_interrupt)]
+
+use blog_os::{exit_qemu, serial_print, serial_println, QemuExitCode};
+use core::panic::PanicInfo;
+use lazy_static::lazy_static;
+use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
+
+#[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

@@ -3,8 +3,8 @@
     "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,
+    "target-c-int-width": "32",
     "os": "none",
     "executables": true,
     "linker-flavor": "ld.lld",