#include<linux/module.h>
#include<linux/printk.h>
#include<linux/mm.h>
#include<asm/desc.h>
#include<linux/kernel.h>
#include<asm/traps.h>


static u64 kern_page; // u64 - macro meaning unsigned 64 bits
static gate
static struct desc_ptr default_idtr; // to save existing idtr

static int __init IDT_rebuild(void)
{
  struct desc_ptr idtr; // here we're going to store our new interupts table
  pr_info("---IDT-REBUILD INITIATED---");
  store_idt(&default_idtr); // getting current idtr and store it
  pr_info("obtained idtr");
  pr_info("allocating new memory page"); 
  kern_page = __get_free_page(GFP_KERNEL);
  if (!kern_page)
  {
    return -ENOMEM;
  }
  idtr.address = kern_page; // going to store 
  idtr.size = default_idtr.size;
  return 0;
}

static void __exit IDT_restore(void)
{
  struct desc_ptr idtr;
  store_idt(&idtr);
  if (idtr.address != default_idtr.address || idtr.size != default_idtr.size)
  {
    load_idt(&default_idtr);
    free_page(kern_page);
  }
}

module_init(IDT_rebuild);
module_exit(IDT_restore);
MODULE_LICENSE("GPL");