-static int page_present(struct mm_struct *mm, void __user *uptr, int wr)
-{
- unsigned long addr = (unsigned long)uptr;
- pgd_t *pgd = pgd_offset(mm, addr);
- if (pgd_present(*pgd)) {
- pmd_t *pmd = pmd_offset(pgd, addr);
- if (pmd_present(*pmd)) {
- pte_t *pte = pte_offset_map(pmd, addr);
- return (pte_present(*pte) && (!wr || pte_write(*pte)));
- }
- }
- return 0;
-}
-
-static int copy_locked(void __user *uptr, void *kptr, size_t size, int write,
- void (*copyfn)(void *, void __user *))
-{
- unsigned char v, __user *userptr = uptr;
- int err = 0;
-
- do {
- struct mm_struct *mm;
-
- if (write) {
- __put_user_error(0, userptr, err);
- __put_user_error(0, userptr + size - 1, err);
- } else {
- __get_user_error(v, userptr, err);
- __get_user_error(v, userptr + size - 1, err);
- }
-
- if (err)
- break;
-
- mm = current->mm;
- spin_lock(&mm->page_table_lock);
- if (page_present(mm, userptr, write) &&
- page_present(mm, userptr + size - 1, write)) {
- copyfn(kptr, uptr);
- } else
- err = 1;
- spin_unlock(&mm->page_table_lock);
- } while (err);
-
- return err;
-}
-