/*
 * Greets: All GNU Generation
 *
 * Author: Paulus Gandung Prakosa (syn-attack@devilzc0de.org)
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>

#define __vsys_fatal_error(msg) { \
	printk(KERN_ERR msg); \
}

#define __vsys_out(msg, fmt...) { \
	printk(KERN_INFO msg, ##fmt); \
}

#define __self_likely(arg)	__builtin_expect(!!(arg), 1)
#define __self_unlikely(arg)	__builtin_expect(!!(arg), 0)

struct control_register {
	unsigned long __cr0;
	unsigned long __cr2;
	unsigned long __cr3;
} __attribute__ ((packed));

static int __init __self_module_loader(void) {
	struct control_register *cr_t;

	cr_t = kmalloc(sizeof(*cr_t), GFP_KERNEL);
	if (__self_unlikely(cr_t == NULL)) {
		__vsys_fatal_error("Not enough memory to allocate.\n");
		return -1;
	}

#ifdef __x86_64__
	__vsys_out("Current system architecture is 64-bit.\n");

	asm volatile("movl	%%cr0, %%rax\n"
		     "movl	%%rax, %0\n"
		     "xorl	%%rax, %%rax\n"
		     "movl	%%cr2, %%rax\n"
		     "movl	%%rax, %1\n"
		     "xorl	%%rax, %%rax\n"
		     "movl	%%cr3, %%rax\n"
		     "movl	%%rax, %2\n"
		     "xorl	%%rax, %%rax\n"
		     : "=r" (cr_t->__cr0), "=r" (cr_t->__cr2), "=r" (cr_t->__cr3));
#elif defined(__i386__)
	__vsys_out("Current system architecture is 32-bit.\n");

	asm volatile("movl	%%cr0, %%eax\n"
		     "movl	%%eax, %0\n"
		     "xorl	%%eax, %%eax\n"
		     "movl	%%cr2, %%eax\n"
		     "movl	%%eax, %1\n"
		     "xorl	%%eax, %%eax\n"
		     "movl	%%cr3, %%eax\n"
		     "movl	%%eax, %2\n"
		     "xorl	%%eax, %%eax\n"
		     : "=r" (cr_t->__cr0), "=r" (cr_t->__cr2), "=r" (cr_t->__cr3));
#endif

	__vsys_out("cr0: 0x%08lx\n", cr_t->__cr0);
	__vsys_out("cr2: 0x%08lx\n", cr_t->__cr2);
	__vsys_out("cr3: 0x%08lx\n", cr_t->__cr3);

	kfree(cr_t);

	return 0;
}

static void __exit __self_module_unloader(void) {
	__vsys_out("Overall process done.\n");

	return;
}

MODULE_AUTHOR("Paulus Gandung Prakosa (syn-attack@devilzc0de.org)");
MODULE_DESCRIPTION("Control Register");
MODULE_LICENSE("GPL");

module_init(__self_module_loader);
module_exit(__self_module_unloader);