diff --git a/Cargo.toml b/Cargo.toml index efd8869..ff7084b 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -29,3 +29,7 @@ test-timeout = 300 [[test]] name = "should_panic" harness = false + +[[test]] +name = "stack_overflow" +harness = false diff --git a/src/gdt.rs b/src/gdt.rs new file mode 100644 index 0000000..6503aa7 --- /dev/null +++ b/src/gdt.rs @@ -0,0 +1,57 @@ +use lazy_static::lazy_static; +use x86_64::{ + instructions::tables::load_tss, + registers::segmentation::{Segment, CS}, + structures::{ + gdt::{Descriptor, GlobalDescriptorTable, SegmentSelector}, + tss::TaskStateSegment, + }, + 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() { + GDT.0.load(); + + unsafe { + CS::set_reg(GDT.1.code_selector); + load_tss(GDT.1.tss_selector); + } +} diff --git a/src/interrupts.rs b/src/interrupts.rs index ea0d2fa..53f1787 100644 --- a/src/interrupts.rs +++ b/src/interrupts.rs @@ -1,12 +1,18 @@ use lazy_static::lazy_static; use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame}; -use crate::println; +use crate::{gdt, println}; 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 }; } @@ -19,6 +25,13 @@ 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() { x86_64::instructions::interrupts::int3(); diff --git a/src/lib.rs b/src/lib.rs index fa998a7..e98a9bc 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -5,6 +5,7 @@ #![test_runner(crate::test_runner)] #![reexport_test_harness_main = "test_main"] +pub mod gdt; pub mod interrupts; pub mod serial; pub mod vga_buffer; @@ -72,5 +73,6 @@ pub fn exit_qemu(exit_code: QemuExitCode) { } pub fn init() { + gdt::init(); interrupts::init_idt(); } diff --git a/tests/stack_overflow.rs b/tests/stack_overflow.rs new file mode 100644 index 0000000..2d10860 --- /dev/null +++ b/tests/stack_overflow.rs @@ -0,0 +1,58 @@ +#![no_std] +#![no_main] +#![feature(abi_x86_interrupt)] + +use core::panic::PanicInfo; + +use lazy_static::lazy_static; +use nel_os::{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(nel_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 {} +} + +#[unsafe(no_mangle)] +pub extern "C" fn _start() -> ! { + serial_print!("stack_overflow::stack_overflow...\t"); + + nel_os::gdt::init(); + init_test_idt(); + + stack_overflow(); + + panic!("Execution continued after stack overflow"); +} + +#[panic_handler] +fn panic(info: &PanicInfo) -> ! { + nel_os::test_panic_handler(info) +} + +#[allow(unconditional_recursion)] +fn stack_overflow() { + stack_overflow(); + volatile::Volatile::new(0).read(); +}