From db4e879c34bac09a1be841f4986037258022e353 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Fri, 25 Jan 2019 13:56:40 +0100
Subject: [PATCH] Create a new GDT module and a static TSS

---
 src/gdt.rs | 20 ++++++++++++++++++++
 src/lib.rs |  1 +
 2 files changed, 21 insertions(+)
 create mode 100644 src/gdt.rs

diff --git a/src/gdt.rs b/src/gdt.rs
new file mode 100644
index 00000000..2b82eb86
--- /dev/null
+++ b/src/gdt.rs
@@ -0,0 +1,20 @@
+use lazy_static::lazy_static;
+use x86_64::structures::tss::TaskStateSegment;
+use x86_64::VirtAddr;
+
+pub const DOUBLE_FAULT_IST_INDEX: u16 = 0;
+
+lazy_static! {
+    static ref TSS: TaskStateSegment = {
+        let mut tss = TaskStateSegment::new();
+        tss.interrupt_stack_table[DOUBLE_FAULT_IST_INDEX as usize] = {
+            const STACK_SIZE: usize = 4096;
+            static mut STACK: [u8; STACK_SIZE] = [0; STACK_SIZE];
+
+            let stack_start = VirtAddr::from_ptr(unsafe { &STACK });
+            let stack_end = stack_start + STACK_SIZE;
+            stack_end
+        };
+        tss
+    };
+}
diff --git a/src/lib.rs b/src/lib.rs
index 562de39e..0bd6fe54 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,7 @@
 #![cfg_attr(not(test), no_std)]
 #![feature(abi_x86_interrupt)]
 
+pub mod gdt;
 pub mod interrupts;
 pub mod serial;
 pub mod vga_buffer;