Successfully load TSS

Author: katietheqt-old

build.rs

@@ -63,6 +63,8 @@ fn main() {
     );
 
     // Inform cargo that we should rerun this on linker script changes
+    //
+    // This is NOT performed by default
     println!("cargo:rerun-if-changed=linker.ld");
 }
 

src/panic.rs

@@ -1,12 +1,11 @@
 use core::panic::PanicInfo;
-use shared::println;
-use shared::utils;
+use shared::{println, instructions};
 
 #[panic_handler]
 pub fn panic(info: &PanicInfo) -> ! {
     println!("[Panic] {}", info);
 
     loop {
-        utils::hlt()
+        instructions::hlt()
     }
 }

src/protected/stage_3/src/lib.rs

@@ -1,6 +1,7 @@
 #![no_std]
 
 use shared::println;
+use shared::instructions;
 
 mod panic;
 
@@ -15,5 +16,12 @@ pub extern "C" fn third_stage() -> ! {
 
     println!("[Bootloader] [32] > 1MB");
 
+    // Load the TSS
+    unsafe {
+        instructions::ltr(0x2B)
+    };
+
+    println!("[Bootloader] [32] Loaded TSS");
+
 	loop {}
 }

src/protected/stage_3/src/panic.rs

@@ -1,12 +1,12 @@
 use core::panic::PanicInfo;
 use shared::println;
-use shared::utils;
+use shared::instructions;
 
 #[panic_handler]
 pub fn panic(info: &PanicInfo) -> ! {
     println!("[Panic] {}", info);
 
     loop {
-        utils::hlt()
+        instructions::hlt()
     }
 }

src/real/bootsector/src/errors.rs

@@ -1,18 +1,18 @@
 use super::console::real_mode_println;
-use shared::utils;
+use shared::instructions;
 
 #[no_mangle]
 extern "C" fn dap_load_failed() -> ! {
     real_mode_println(b"[!] DAP Load Failed");
     loop {
-        utils::hlt()
+        instructions::hlt()
     }
 }
 
 #[no_mangle]
 extern "C" fn no_int13h_extensions() -> ! {
     real_mode_println(b"[!] No int13h Extensions");
     loop {
-        utils::hlt()
+        instructions::hlt()
     }
 }

src/real/bootsector/src/lib.rs

@@ -7,7 +7,7 @@ mod errors;
 
 use self::console::real_mode_println;
 use core::panic::PanicInfo;
-use shared::{dap, linker_symbol, utils};
+use shared::{dap, linker_symbol, instructions};
 
 extern "C" {
     fn second_stage() -> !;
@@ -49,6 +49,6 @@ fn panic(_info: &PanicInfo) -> ! {
     real_mode_println(b"[Panic]");
 
     loop {
-        utils::hlt()
+        instructions::hlt()
     }
 }

src/real/stage_2/src/lib.rs

@@ -24,11 +24,17 @@ lazy_static! {
     static ref GDT: GlobalDescriptorTable = {
         let mut gdt = GlobalDescriptorTable::new();
 
+        // Set up kernel segments
         gdt.add_entry(Descriptor::kernel_code_segment());
         gdt.add_entry(Descriptor::kernel_data_segment());
 
-        gdt.add_entry(Descriptor::tss_segment(&TSS));
+        // Set up user segments
+        gdt.add_entry(Descriptor::user_code_segment());
+        gdt.add_entry(Descriptor::user_data_segment());
 
+        // Set up the TSS
+        gdt.add_entry(Descriptor::tss_segment(&*TSS));
+        
         gdt
     };
 }
@@ -43,11 +49,11 @@ pub fn second_stage() -> ! {
 
     unsafe {
         GDT.load();
+
+        println!("[Bootloader] [16] Loaded GDT");
 
         protected_mode_switch();
     }
-
-    unreachable!();
 }
 
 fn enable_a20() {

src/real/stage_2/src/panic.rs

@@ -1,12 +1,12 @@
 use core::panic::PanicInfo;
 use shared::println;
-use shared::utils;
+use shared::instructions;
 
 #[panic_handler]
 pub fn panic(info: &PanicInfo) -> ! {
     println!("[Panic] {}", info);
 
     loop {
-        utils::hlt()
+        instructions::hlt()
     }
 }

src/shared/src/instructions.rs

@@ -0,0 +1,31 @@
+/// Performs a retf instruction, jumping to cs:eip
+///
+/// # Unsafety
+/// We make no guarantees that the cs and eip are valid, nor that they contain executable code
+#[inline(always)]
+pub unsafe fn retf(cs: u16, eip: u32) {
+	asm!("push {0:x}
+		  push {1}
+		  retf",
+		  in(reg) cs, in(reg) eip);
+}
+
+/// Loads a new value into the task state register
+///
+/// # Unsafety
+/// A bad value will cause undefined behaviour
+#[inline(always)]
+pub unsafe fn ltr(task_state: u16) {
+	asm!("ltr {0:x}",
+		 in(reg) task_state,
+		 options(nostack)
+	);
+}
+
+/// Halts the processor
+#[inline(always)]
+pub fn hlt() {
+	unsafe {
+    	asm!("hlt", options(nostack, nomem));
+    }
+}