linux通过进程虚拟地址找到物理地址

通过进程id找到对应的task_struct，就得到了cr3中存储着的页表首地址，然后同ing过页表找到最后页的物理地址

static pte_t *get_pte(struct task_struct *task, unsigned long address)
{
	pgd_t* pgd;
    p4d_t* p4d;
	pud_t* pud;
	pmd_t* pmd;
	pte_t* pte;

	struct mm_struct *mm = task->mm;

	// mm里面存储了最高级页表的首地址，pgd_offset根据首地址和便宜算出下一级页表的首地址
	pgd = pgd_offset(mm, address);
	if(pgd_none(*pgd) || pgd_bad(*pgd))
	{
		printk("pgd is null\n");
		return NULL;
	}
    
    p4d = p4d_offset(pgd, address);
    if (p4d_none(*p4d) || p4d_bad(*p4d))
	{
		printk("p4d is null\n");
		return NULL;
	}

    pud = pud_offset(p4d, address);
    if (pud_none(*pud) || pud_bad(*pud))
	{
		printk("pud is null\n");
		return NULL;
	}

	pmd = pmd_offset(pud, address);
	if(pmd_none(*pmd) || pmd_bad(*pmd))
	{
		printk("pmd is null\n");
		return NULL;
	}

	pte = pte_offset_kernel(pmd, address);
	if(pte_none(*pte))
	{
		printk("pte is null\n");
		return NULL;
	}

	return pte;
}


int main()
{
	pte_t *pte = get_pte(task, addr);

	// unsigned int level;
	// pte_t *pte = lookup_address(addr, &level);

	if(pte)
	{
		printk("evict\n");
		pte->pte &= (~_PAGE_PRESENT);
	}
}