From bea6a729fe3effa88f77f59c9fd6956b510b45a0 Mon Sep 17 00:00:00 2001
From: Jack Halford <jack@crans.org>
Date: Fri, 6 Apr 2018 17:43:58 +0200
Subject: [PATCH] gdt in place but triple faults because of spin::Once for now

---
 kernel-rs/Cargo.toml          |  9 +++++----
 kernel-rs/src/arch/x86/gdt.rs | 34 ++++++++++++++++++++++++++++++++++
 kernel-rs/src/arch/x86/mod.rs | 13 +++++++------
 kernel-rs/src/arch/x86/pti.rs |  3 +++
 kernel-rs/src/lib.rs          |  2 ++
 kernel-rs/src/memory/mod.rs   |  2 +-
 6 files changed, 52 insertions(+), 11 deletions(-)
 create mode 100644 kernel-rs/src/arch/x86/gdt.rs

diff --git a/kernel-rs/Cargo.toml b/kernel-rs/Cargo.toml
index 217b03ac..d2b8779f 100644
--- a/kernel-rs/Cargo.toml
+++ b/kernel-rs/Cargo.toml
@@ -13,11 +13,12 @@ spin = "0.4"
 slab_allocator = "0.3.1"
 multiboot2 = { path = "multiboot2-elf64" }		# added rsdp tag
 x86 = { path = "x86" }							# forked for IA32
+raw-cpuid = { path = "rust-cpuid" }
 
-[dependencies.raw-cpuid]
-# need to use github/master because of features not yet on crates.io
-git = "https://github.com/gz/rust-cpuid"
-features = ["nightly"]
+# [dependencies.raw-cpuid]
+# # need to use github/master because of features not yet on crates.io
+# git = "https://github.com/gz/rust-cpuid"
+# features = ["nightly"]
 
 [dependencies.lazy_static]
 version = "1.0.0"
diff --git a/kernel-rs/src/arch/x86/gdt.rs b/kernel-rs/src/arch/x86/gdt.rs
new file mode 100644
index 00000000..0fed6425
--- /dev/null
+++ b/kernel-rs/src/arch/x86/gdt.rs
@@ -0,0 +1,34 @@
+use x86::structures::gdt;
+use x86::structures::tss;
+use x86::instructions::segmentation::set_cs;
+use x86::instructions::tables::load_tss;
+use spin::Once;
+
+static GDT: Once<gdt::Gdt> = Once::new();
+static TSS: Once<tss::TaskStateSegment> = Once::new();
+
+pub fn init() {
+    // let tss = tss::TaskStateSegment::new();
+    let tss = TSS.call_once(|| {
+        let mut tss = tss::TaskStateSegment::new();
+        tss
+    });
+
+    // let mut code_selector = gdt::SegmentSelector(0);
+    // let mut tss_selector = gdt::SegmentSelector(0);
+
+    // let gdt = GDT.call_once(|| {
+    //     let mut gdt =  gdt::Gdt::new();
+    //     code_selector = gdt.add_entry(gdt::Descriptor::kernel_code_segment());
+    //     tss_selector = gdt.add_entry(gdt::Descriptor::tss_segment(&tss));
+    //     gdt
+    // });
+
+    // gdt.load();
+    // unsafe {
+    //     // reload code segment register
+    //     set_cs(code_selector);
+    //     // load TSS
+    //     load_tss(tss_selector);
+    // }
+}
diff --git a/kernel-rs/src/arch/x86/mod.rs b/kernel-rs/src/arch/x86/mod.rs
index f00125a2..74572557 100644
--- a/kernel-rs/src/arch/x86/mod.rs
+++ b/kernel-rs/src/arch/x86/mod.rs
@@ -6,6 +6,7 @@ pub mod interrupt;
 pub mod device;
 pub mod pti;
 
+pub mod gdt;
 pub mod idt;
 
 use multiboot2;
@@ -25,9 +26,6 @@ pub unsafe extern fn x86_rust_start(multiboot_info_addr: usize) {
         acpi::init().expect("ACPI failed");
     }
 
-    // set up interrupts
-    idt::init();
-
     // set up physical allocator
      ::memory::init(&boot_info);
 
@@ -37,12 +35,15 @@ pub unsafe extern fn x86_rust_start(multiboot_info_addr: usize) {
     // set up heap
     ::allocator::init(&mut active_table);
 
+    // set up memory segmentation
+    // gdt::init();
+
+    // set up interrupts
+    idt::init();
+
     // set up pic & apic
     device::init(&mut active_table);
 
-    // after core has loaded
-    ::memory::init_noncore();
-
     // primary CPU entry point
     ::kmain();
 }
diff --git a/kernel-rs/src/arch/x86/pti.rs b/kernel-rs/src/arch/x86/pti.rs
index 7ed277cb..7942d611 100644
--- a/kernel-rs/src/arch/x86/pti.rs
+++ b/kernel-rs/src/arch/x86/pti.rs
@@ -12,6 +12,8 @@ pub static mut PTI_CONTEXT_STACK: usize = 0;
 #[inline(always)]
 unsafe fn switch_stack(old: usize, new: usize) {
     let old_esp: usize;
+
+    // save the old esp
     asm!("" : "={esp}"(old_esp) : : : "intel", "volatile");
 
     let offset_esp = old - old_esp;
@@ -24,6 +26,7 @@ unsafe fn switch_stack(old: usize, new: usize) {
         offset_esp
     );
 
+    // switch the esp with the new one
     asm!("" : : "{esp}"(new_esp) : : "intel", "volatile");
 }
 
diff --git a/kernel-rs/src/lib.rs b/kernel-rs/src/lib.rs
index 509d3d71..8db6c338 100644
--- a/kernel-rs/src/lib.rs
+++ b/kernel-rs/src/lib.rs
@@ -47,6 +47,8 @@ pub mod arch;
 
 /// kernel entry point. arch module is responsible for calling this
 pub fn kmain() -> ! {
+    // core is loaded now
+    memory::init_noncore();
 
     // x86::instructions::interrupts::int3();
 
diff --git a/kernel-rs/src/memory/mod.rs b/kernel-rs/src/memory/mod.rs
index 01514299..a8c28ed5 100644
--- a/kernel-rs/src/memory/mod.rs
+++ b/kernel-rs/src/memory/mod.rs
@@ -72,7 +72,7 @@ pub fn deallocate_frames(frame: PhysFrame, count: usize) {
 
 /// Init memory module after core
 /// Must be called once, and only once,
-pub unsafe fn init_noncore() {
+pub fn init_noncore() {
     if let Some(ref mut controler) = *MEMORY_CONTROLER.lock() {
         controler.frame_allocator.set_core(true);
     } else {