Kernel: Add double fault handler

moon/src/arch/x86_64/cpu.rs

@@ -25,3 +25,7 @@ pub fn halt() -> ! {
 pub fn wait_for_interrupt() -> () {
     unsafe { asm!("hlt"); }
 }
+
+pub fn breakpoint() -> () {
+    unsafe { asm!("int3"); }
+}

moon/src/arch/x86_64/interrupts.rs

@@ -14,11 +14,16 @@ extern "x86-interrupt" fn page_fault_handler(stack_frame: InterruptStackFrame, f
     try_println!("Page fault at {:#?}\n{:#?}", faulting_address, stack_frame);
 }
 
+extern "x86-interrupt" fn double_fault_handler(stack_frame: InterruptStackFrame, _error_code: u64) -> ! {
+    panic!("Double fault!\n{:#?}", stack_frame);
+}
+
 pub fn load()
 {
     unsafe { 
         IDT.breakpoint.set_handler_fn(breakpoint_handler);
         IDT.page_fault.set_handler_fn(page_fault_handler);
+        IDT.double_fault.set_handler_fn(double_fault_handler);
         IDT.load(); 
     }
 }

moon/src/main.rs

@@ -15,8 +15,6 @@ mod log;
 use arch::cpu;
 use arch::interrupts;
 
-use x86_64::instructions::interrupts::int3;
-
 use video::Color;
 
 #[no_mangle]
@@ -35,7 +33,7 @@ pub extern "C" fn _start() -> ! {
 
     interrupts::enable();
 
-    int3();
+    cpu::breakpoint();
 
     println!("Still here!");
     

moon/src/panic.rs

@@ -1,9 +1,12 @@
 use core::panic::PanicInfo;
 
-use crate::println;
+use crate::try_println;
+use crate::arch::io::SERIAL;
+use crate::arch::cpu;
 
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
-    println!("Kernel {}", info);
-    loop {}
+    unsafe { SERIAL.force_unlock(); } // since we're panicking, this is not relevant anymore.
+    try_println!("Kernel {}", info); // we probably should succeed, unless another CPU locked the serial port just after we unlocked it but before try_println attempts to lock it.
+    cpu::halt();
 }