Fix GDT, among other things

Currently in a bootable state. I haven't worked on this project in a while, so many of the fixes in this commit I have forgotten. Sorry!

Author: katietheqt-old

src/protected/Cargo.toml

@@ -6,4 +6,5 @@ members = [
 [profile.release]
 opt-level = "z"
 panic = "abort"
-lto = true
+lto = true
+debug = true

src/protected/stage_3/src/lib.rs

@@ -7,7 +7,7 @@ mod panic;
 
 #[no_mangle]
 pub extern "C" fn third_stage() -> ! {
-	println!("X");
+	println!("[Bootloader] [32] Stage 3");
 
 	loop {}
 }

src/real/Cargo.toml

@@ -12,3 +12,6 @@ lto = true
 [profile.release.package.bootsector]
 opt-level = "s"
 codegen-units = 1
+
+[profile.release.package.stage_2]
+debug = true

src/real/bootsector/src/lib.rs

@@ -16,7 +16,7 @@ global_asm!(include_str!("bootstrap.s"));
 
 #[no_mangle]
 extern "C" fn rust_start(disk_number: u16) -> ! {
-    real_mode_println(b"Stage 1");
+    real_mode_println(b"[Bootloader] [16] Bootsector");
 
     check_int13h_extensions(disk_number);
 

src/real/stage_2/src/lib.rs

@@ -1,13 +1,9 @@
 #![feature(global_asm, llvm_asm)]
 #![no_std]
 
-// FIXME
-#![allow(dead_code, unused_variables)]
-
 use shared::linker_symbol;
 use shared::println;
 use shared::structures::gdt::{Descriptor, GlobalDescriptorTable, TaskStateSegment};
-
 use lazy_static::lazy_static;
 
 mod panic;
@@ -16,8 +12,6 @@ extern "C" {
     fn protected_mode_switch() -> !;
 }
 
-global_asm!(include_str!("protected_mode.s"));
-
 lazy_static! {
     static ref TSS: TaskStateSegment = {
         let mut tss = TaskStateSegment::new();
@@ -26,80 +20,31 @@ lazy_static! {
 
         tss
     };
+
     static ref GDT: GlobalDescriptorTable = {
         let mut gdt = GlobalDescriptorTable::new();
 
         gdt.add_entry(Descriptor::kernel_code_segment());
         gdt.add_entry(Descriptor::kernel_data_segment());
-        gdt.add_entry(Descriptor::user_code_segment());
-        gdt.add_entry(Descriptor::user_data_segment());
 
         gdt.add_entry(Descriptor::tss_segment(&TSS));
 
         gdt
     };
 }
 
+global_asm!(include_str!("protected_mode.s"));
+
 #[no_mangle]
 pub fn second_stage() -> ! {
-    println!("Stage 2");
-
-    unsafe {
-        //GDT.load();
-        
-        println!("Switching to Protected Mode");
-    
-        protected_mode_switch();
-    }
-}
-
-fn enter_protected_mode() -> ! {
-    unsafe {
-        GDT.load();
-    }
-
-    println!("Switching to Protected Mode");
+    println!("[Bootloader] [16] Stage 2");
 
     enable_a20();
 
-    println!("A20 On");
-
-
-    unsafe {
-        llvm_asm!("cli" :::: "intel", "volatile");
-    }
-
-    println!("Interrupts off");
-
-    let ds: u16;
-    let es: u16;
-
-    unsafe {
-        llvm_asm!("mov ax, ds
-                   mov bx, es"
-                  : "={ax}"(ds), "={bx}"(es)
-                  ::: "intel", "volatile");
-    }
-
-    println!("Segments stored");
-
     unsafe {
-        llvm_asm!("mov bx, 0x0
-                   mov ds, bx
-                   mov es, bx" ::: "bx" : "intel", "volatile");
-    }
-
-    println!("Segments set");
-
-    unsafe {
-        llvm_asm!("mov eax, cr0
-                   or al, 1
-                   mov cr0, eax
-
-                   push dx
-                   push cx
-
-                   jmp third_stage" :: "{dx}"(ds), "{cx}"(es) :: "intel", "volatile");
+        GDT.load();
+        
+        protected_mode_switch();
     }
 
     unreachable!();

src/real/stage_2/src/protected_mode.s

@@ -4,8 +4,6 @@
 protected_mode_switch:
     cli
 
-    lgdt [gdt32info]
-
     mov eax, cr0
     or al, 1
     mov cr0, eax
@@ -15,36 +13,11 @@ protected_mode_switch:
     push eax
     retf
 
+.code32
 protected_mode:
     mov bx, 0x10
+
     mov ds, bx
     mov es, bx
 
-    jmp third_stage
-
-gdt32info:
-   .word gdt32_end - gdt32 - 1  # last byte in table
-   .word gdt32                  # start of table
-
-gdt32:
-    # entry 0 is always unused
-    .quad 0
-codedesc:
-    .byte 0xff
-    .byte 0xff
-    .byte 0
-    .byte 0
-    .byte 0
-    .byte 0x9a
-    .byte 0xcc
-    .byte 0
-datadesc:
-    .byte 0xff
-    .byte 0xff
-    .byte 0
-    .byte 0
-    .byte 0
-    .byte 0x92
-    .byte 0xcc
-    .byte 0
-gdt32_end:
+    jmp third_stage

src/shared/Cargo.toml

@@ -12,4 +12,10 @@ spin = "0.5"
 
 [dependencies.lazy_static]
 version = "1"
-features = ["spin_no_std"]
+features = ["spin_no_std"]
+
+[profile.release]
+debug = true
+opt-level = "z"
+panic = "abort"
+lto = true

src/shared/src/console.rs

@@ -9,7 +9,7 @@ lazy_static! {
     /// Used by the `print!` and `println!` macros.
     pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
         column_position: 0,
-        color_code: ColorCode::new(Color::Red, Color::Black),
+        color_code: ColorCode::new(Color::LightGray, Color::Black),
         buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
     });
 }

src/shared/src/instructions/assembly.s

@@ -0,0 +1,3 @@
+.intel_syntax noprefix
+
+retf: retf

src/shared/src/instructions/mod.rs

@@ -0,0 +1,5 @@
+global_asm!(include_str!("assembly.s"));
+
+extern "C" {
+	pub fn retf(cs: u32, eip: u32);
+}