From c3e1897c23cbea927cde047c296d913d7878da54 Mon Sep 17 00:00:00 2001
From: Sainnhe Park <sainnhe@gmail.com>
Date: Wed, 12 Jan 2022 16:54:57 +0800
Subject: [PATCH] Introduction to Paging

---
 src/interrupts.rs | 13 ++++++++++++-
 src/main.rs       | 10 ++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/interrupts.rs b/src/interrupts.rs
index 870d8d3..652888c 100644
--- a/src/interrupts.rs
+++ b/src/interrupts.rs
@@ -1,9 +1,10 @@
-use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};
+use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame, PageFaultErrorCode};
 use crate::{println, print};
 use lazy_static::lazy_static;
 use crate::gdt;
 use pic8259::ChainedPics;
 use spin;
+use crate::hlt_loop;
 
 lazy_static! {
     static ref IDT: InterruptDescriptorTable = {
@@ -17,6 +18,7 @@ lazy_static! {
             .set_handler_fn(timer_interrupt_handler);
         idt[InterruptIndex::Keyboard.as_usize()]
             .set_handler_fn(keyboard_interrupt_handler);
+        idt.page_fault.set_handler_fn(page_fault_handler);
         idt
     };
 }
@@ -89,3 +91,12 @@ extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: InterruptStac
             .notify_end_of_interrupt(InterruptIndex::Keyboard.as_u8());
     }
 }
+
+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();
+}
diff --git a/src/main.rs b/src/main.rs
index 693740f..def8cbe 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -16,6 +16,16 @@ pub extern "C" fn _start() -> ! {
 
     anos::init();
 
+    let ptr = 0x2031b2 as *mut u32;
+    unsafe { let x = *ptr; }
+    println!("read worked");
+    unsafe { *ptr = 42 };
+    println!("write worked");
+
+    use x86_64::registers::control::Cr3;
+    let (level_4_page_table, _) = Cr3::read();
+    println!("Level 4 page table at: {:?}", level_4_page_table.start_address());
+
     // 触发一个中断
     x86_64::instructions::interrupts::int3();
     println!("It didn't crash!");