Copy kernel module function and execute

kmemfun.c

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>

unsigned long *amem; 

static void enable_page_protection(void)
{
    unsigned long value;
    asm volatile("mov %%cr0, %0" : "=r" (value));

    if((value & 0x00010000))
        return;

    asm volatile("mov %0, %%cr0" : : "r" (value | 0x00010000));
}

static void disable_page_protection(void)
{
    unsigned long value;
    asm volatile("mov %%cr0, %0" : "=r" (value));

    if(!(value & 0x00010000))
        return;

    asm volatile("mov %0, %%cr0" : : "r" (value & ~0x00010000));
}

unsigned long __imf(void)
{
   asm("movq amem, %rbx");
   asm("movq (%rbx), %rbx");
   asm("inc %rbx");
   asm("inc %rbx");
   asm("movq amem, %rcx");
   asm("movq %rbx, (%rcx)");
   asm("mov amem, %rbx");
   asm("mov %rbx, %rax");
   asm("pop %rbp");
   asm("ret");
}

int init_module(void)
{
    unsigned long diff;
    void *code; 
    unsigned long (*ime)(void); 

    unsigned long gdata = 0x444f4f4b;

    // allocate memory for data & copy it
    amem = kmalloc(sizeof(unsigned long), GFP_KERNEL); 
    memcpy(amem, &gdata, sizeof(unsigned long));  

    // allocate memory for code & copy it
    diff = ((unsigned long)&init_module - (unsigned long)&__imf); 
    code = __vmalloc(diff, GFP_KERNEL|__GFP_NOWARN, PAGE_KERNEL);
    memcpy(code, &__imf, diff);

    // you could map PAGE_KERNEL_EXEC.. or you *could* map as 
    // PAGE_KERNEL and disable NX if you are feeling saucy
    disable_page_protection(); 
    //dnx = (void *)kallsyms_lookup_name("disable_nx");
    //*(dnx) = 1;
    __supported_pte_mask &= ~_PAGE_NX;
    enable_page_protection();

    ime = code; 
    printk("IT'S SOME OK %s\n", (char *)ime());
    return 0;
}

void cleanup_module(void)
{      
    // nothing happens here so memory remains allocated
}

MODULE_AUTHOR("linuxthor");
MODULE_LICENSE("GPL");