#include <linux/mm.h>
#include <linux/mm_types.h>
#include <linux/sched.h>

#include <asm/pgalloc.h>
#include <asm/tlbflush.h>

//vaddr_h: vaddr above 4G
long sys_cr3(unsigned long vaddr_h)
{
    unsigned long eax;
    unsigned long vaddr=0x10000000 | (vaddr_h & 0xfff);
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd, pmd_n;
    pte_t *pte, *pte_h;
    struct page *page;
    pgprot_t pgprot;

    //get origen page above 4G
    pgd = pgd_offset(current->mm, vaddr_h);
    pud = pud_offset(pgd, vaddr_h);
    pmd = pmd_offset(pud, vaddr_h);
    pgprot = __pgprot(pmd_val(*pmd) & 0xfff);
    pte_h = pte_offset_map(pmd, vaddr_h);

    //mapping vaddr_h above 4G to vaddr below 4G
    //alloc page entry
    pgd = pgd_offset(current->mm, vaddr);
    if(pgd_none(*pgd)) {
        printk("pgd entry not found, alloc new pud and set pgd entry\n");
        /* FIXME */
        //pud = pud_alloc(current->mm, current->mm->pgd, vaddr);
        //set_pud(pgd, *pud);
        pgd = pgd_alloc(current->mm);
    }
    pud = pud_offset(pgd, vaddr);
    if(pud_none(*pud)) {
        printk("pud entry not found, alloc new pmd and set pud entry\n");
        /* FIXME */
        pud = pud_alloc(current->mm, pgd, vaddr);
    }
    pmd = pmd_offset(pud, vaddr);
    if(pmd_none(*pmd)) {
        printk("pmd entry not found, alloc new pte and set pmd entry\n");
        //pmd = pmd_alloc(current->mm, pud, vaddr);
        page = pte_alloc_one(current->mm, vaddr);
        pmd_n = mk_pmd(page, pgprot);
        set_pmd(pmd, pmd_n);
    }

    //pte = page table entry
    pte = pte_offset_map(pmd, vaddr);

    //set new pte as origin pte_h
    set_pte(pte, *pte_h);

    //update_mmu_cache(current->mm->mmap, vaddr, pte);
    //flush_tlb_mm(current->mm);
}