add physical memory map

Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.0"
 edition = "2018"
 
 [dependencies]
-bootloader = "0.9"
+bootloader = { version = "0.9", features = ["map_physical_memory"] }
 volatile = "0.2.6"
 spin = "0.5.2"
 x86_64 = "0.14.2"
@@ -17,6 +17,10 @@ version = "1.0"
 features = ["spin_no_std"]
 
 [package.metadata.bootimage]
+run-args = [
+  "-serial",
+  "stdio"
+]
 test-args = [
     "-device",
     "isa-debug-exit,iobase=0xf4,iosize=0x04",

src/interrupts.rs

@@ -13,6 +13,8 @@ lazy_static! {
                 .set_handler_fn(double_fault_handler)
                 .set_stack_index(gdt::DOUBLE_FAULT_IST_INDEX);
         }
+        idt.page_fault.set_handler_fn(page_fault_handler);
+
         idt[InterruptIndex::Timer.as_usize()].set_handler_fn(timer_interrupt_handler);
         idt[InterruptIndex::Keyboard.as_usize()].set_handler_fn(keyboard_interrupt_handler);
 
@@ -35,6 +37,22 @@ extern "x86-interrupt" fn double_fault_handler(
     panic!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
 }
 
+use crate::hlt_loop;
+use x86_64::structures::idt::PageFaultErrorCode;
+
+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();
+}
+
 pub const PIC_1_OFFSET: u8 = 32;
 pub const PIC_2_OFFSET: u8 = PIC_1_OFFSET + 8;
 

src/lib.rs

@@ -7,11 +7,17 @@
 
 pub mod gdt;
 pub mod interrupts;
+pub mod memory;
 pub mod serial;
 pub mod vga_buffer;
 
 use core::panic::PanicInfo;
 
+#[cfg(test)]
+use bootloader::entry_point;
+#[cfg(test)]
+use bootloader::BootInfo;
+
 pub trait Testable {
     fn run(&self) -> ();
 }
@@ -43,8 +49,10 @@ pub fn test_panic_handler(info: &PanicInfo) -> ! {
 }
 
 #[cfg(test)]
-#[unsafe(no_mangle)]
-pub extern "C" fn _start() -> ! {
+entry_point!(test_kernel_main);
+
+#[cfg(test)]
+fn test_kernel_main(_boot_info: &'static BootInfo) -> ! {
     init();
     test_main();
     hlt_loop();

src/main.rs

@@ -4,8 +4,10 @@
 #![test_runner(nel_os::test_runner)]
 #![reexport_test_harness_main = "test_main"]
 
+use bootloader::{entry_point, BootInfo};
 use core::panic::PanicInfo;
-use nel_os::println;
+use nel_os::{memory, println};
+use x86_64::{structures::paging::Translate, VirtAddr};
 
 #[cfg(not(test))]
 #[panic_handler]
@@ -20,12 +22,28 @@ fn panic(info: &PanicInfo) -> ! {
     nel_os::test_panic_handler(info)
 }
 
-#[no_mangle]
-pub extern "C" fn _start() -> ! {
+entry_point!(kernel_main);
+
+fn kernel_main(boot_info: &'static BootInfo) -> ! {
     println!("NelOS v{}", env!("CARGO_PKG_VERSION"));
 
     nel_os::init();
 
+    let phys_mem_offset = VirtAddr::new(boot_info.physical_memory_offset);
+    let mapper = unsafe { memory::init(phys_mem_offset) };
+    let addresses = [
+        0xb8000,
+        0x201008,
+        0x0100_0020_1a10,
+        boot_info.physical_memory_offset,
+    ];
+
+    for &address in &addresses {
+        let virt = VirtAddr::new(address);
+        let phys = mapper.translate_addr(virt);
+        println!("{:?} -> {:?}", virt, phys);
+    }
+
     #[cfg(test)]
     test_main();
 

src/memory.rs

@@ -0,0 +1,23 @@
+use x86_64::{
+    structures::paging::{OffsetPageTable, PageTable},
+    VirtAddr,
+};
+
+unsafe fn active_level_4_table(physical_memory_offset: VirtAddr) -> &'static mut PageTable {
+    use x86_64::registers::control::Cr3;
+
+    let (level_4_table_frame, _) = Cr3::read();
+
+    let phys = level_4_table_frame.start_address();
+    let virt = physical_memory_offset + phys.as_u64();
+    let page_table_ptr: *mut PageTable = virt.as_mut_ptr();
+
+    unsafe { &mut *page_table_ptr }
+}
+
+pub unsafe fn init(physical_memory_offset: VirtAddr) -> OffsetPageTable<'static> {
+    unsafe {
+        let level_4_table = active_level_4_table(physical_memory_offset);
+        OffsetPageTable::new(level_4_table, physical_memory_offset)
+    }
+}

src/vga_buffer.rs

@@ -4,6 +4,8 @@ use lazy_static::lazy_static;
 use spin::Mutex;
 use volatile::Volatile;
 
+use crate::serial::SERIAL1;
+
 lazy_static! {
     pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
         column_position: 0,
@@ -30,6 +32,10 @@ pub fn _print(args: fmt::Arguments) {
 
     interrupts::without_interrupts(|| {
         WRITER.lock().write_fmt(args).unwrap();
+        SERIAL1
+            .lock()
+            .write_fmt(args)
+            .expect("Printing to serial failed");
     });
 }