Catch divide error instead of page fault

The divide error pushes no error code. Thus we avoid stack misalignment (see #184).

(cherry picked from commit e8b3a1fff1)

src/interrupts/mod.rs

@@ -4,7 +4,7 @@ lazy_static! {
     static ref IDT: idt::Idt = {
         let mut idt = idt::Idt::new();
 
-        idt.set_handler(14, page_fault_handler);
+        idt.set_handler(0, divide_by_zero_handler);
 
         idt
     };
@@ -16,7 +16,7 @@ pub fn init() {
 
 use vga_buffer::print_error;
 
-extern "C" fn page_fault_handler() -> ! {
-    unsafe { print_error(format_args!("EXCEPTION: PAGE FAULT")) };
+extern "C" fn divide_by_zero_handler() -> ! {
+    unsafe { print_error(format_args!("EXCEPTION: DIVIDE BY ZERO")) };
     loop {}
 }

src/lib.rs

@@ -10,6 +10,7 @@
 #![feature(lang_items)]
 #![feature(const_fn, unique)]
 #![feature(alloc, collections)]
+#![feature(asm)]
 #![no_std]
 
 extern crate rlibc;
@@ -49,8 +50,12 @@ pub extern "C" fn rust_main(multiboot_information_address: usize) {
     // initialize our IDT
     interrupts::init();
 
-    // provoke a page fault inside println
-    println!("{:?}", unsafe{ *(0xdeadbeaf as *mut u64) = 42 });
+    fn divide_by_zero() {
+        unsafe { asm!("mov dx, 0; div dx" ::: "ax", "dx" : "volatile", "intel") }
+    }
+
+    // provoke a divide by zero fault inside println
+    println!("{:?}", divide_by_zero());
 
     println!("It did not crash!");
     loop {}