From 950de8645c57f50a35f0fd6abdf44ff8a70b0093 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Lov=C3=A9n?= <thomasloven@gmail.com>
Date: Mon, 18 Dec 2017 23:23:08 +0100
Subject: [PATCH] Update GDT pointer after unmapping GDT

---
 src/kernel/boot/boot.S | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/kernel/boot/boot.S b/src/kernel/boot/boot.S
index 48e84aa..95d1f7a 100644
--- a/src/kernel/boot/boot.S
+++ b/src/kernel/boot/boot.S
@@ -58,7 +58,7 @@ jmp 0x8:V2P(long_mode_start)
   movabs rax, offset upper_memory
   jmp rax
 
-  upper_memory:
+upper_memory:
 
   //; Move stack pointer to kernel space
   mov rax, KERNEL_OFFSET
@@ -68,9 +68,27 @@ jmp 0x8:V2P(long_mode_start)
   mov rax, 0
   movabs [BootP4], rax
 
+  //; Update page tables
   mov rax, cr3
   mov cr3, rax
 
+  //; Reload GDT
+  movabs rax, offset BootGDTp
+  lgdt [rax]
+  mov rax, 0x0
+  mov ss, rax
+  mov ds, rax
+  mov es, rax
+  mov fs, rax
+  mov gs, rax
+
+  //; Reload CS
+  movabs rax, offset .reload_cs
+  pushq 0x8
+  push rax
+  retfq
+.reload_cs:
+
   //; Jump to kmain()
 .extern kmain
   movabs rax, offset kmain