Given the top-level Page Directory, the offset in that directory is calculated
using the upper 8 bits:
-extern inline pgd_t * pgd_offset(struct mm_struct * mm, unsigned long address)
+static inline pgd_t * pgd_offset(struct mm_struct * mm, unsigned long address)
{
return mm->pgd + (address >> PGDIR_SHIFT);
}
Since the Middle Directory does not exist, it is a unity mapping:
-extern inline pmd_t * pmd_offset(pgd_t * dir, unsigned long address)
+static inline pmd_t * pmd_offset(pgd_t * dir, unsigned long address)
{
return (pmd_t *) dir;
}
The Page Table provides the final lookup by using bits 13 to 23 as index:
-extern inline pte_t * pte_offset(pmd_t * dir, unsigned long address)
+static inline pte_t * pte_offset(pmd_t * dir, unsigned long address)
{
return (pte_t *) pmd_page(*dir) + ((address >> PAGE_SHIFT) &
(PTRS_PER_PTE - 1));