+/* Returns true if the PTE for user virtual page UPAGE in PD has
+ been accessed recently, that is, between the time the PTE was
+ installed and the last time it was cleared.
+ Returns false if PD contains no PDE for UPAGE. */
+bool
+pagedir_test_accessed (uint32_t *pd, const void *upage)
+{
+ uint32_t *pte = lookup_page (pd, (void *) upage, false);
+ return pte != NULL && (*pte & PG_A) != 0;
+}
+
+/* Returns true if the PTE for user virtual page UPAGE in PD has
+ been accessed recently, and then resets the accessed bit for
+ that page.
+ Returns false and has no effect if PD contains no PDE for
+ UPAGE. */
+bool
+pagedir_test_accessed_and_clear (uint32_t *pd, const void *upage)
+{
+ uint32_t *pte = lookup_page (pd, (void *) upage, false);
+ if (pte != NULL)
+ {
+ bool accessed = (*pte & PG_A) != 0;
+ *pte &= ~(uint32_t) PG_A;
+ return accessed;
+ }
+ else
+ return false;
+}
+
+/* Loads page directory PD into the CPU's page directory base
+ register. */