pagedir_get_page (uint32_t *pd, const void *uaddr)
{
uint32_t *pte = lookup_page (pd, (void *) uaddr, false);
- return pte != NULL && *pte != 0 ? pte_get_page (*pte) : NULL;
+ return (pte != NULL && *pte != 0
+ ? (uint8_t *) pte_get_page (*pte) + pg_ofs (uaddr)
+ : NULL);
}
/* Clears any mapping for user virtual address UPAGE in page
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)
+/* Resets the accessed bit in the PTE for user virtual page UPAGE
+ in PD. */
+void
+pagedir_clear_accessed (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;
+ *pte &= ~(uint32_t) PG_A;
}
/* Loads page directory PD into the CPU's page directory base
{
if (pd == NULL)
pd = base_page_dir;
- asm volatile ("movl %0,%%cr3" :: "r" (vtop (pd)));
+
+ /* Store the physical address of the page directory into CR3
+ aka PDBR (page directory base register). This activates our
+ new page tables immediately. See [IA32-v2a] "MOV--Move
+ to/from Control Registers" and [IA32-v3] 3.7.5. */
+ asm volatile ("mov %%cr3, %0" :: "r" (vtop (pd)));
}
/* Returns the currently active page directory. */
static uint32_t *
active_pd (void)
{
+ /* Copy CR3, the page directory base register (PDBR), into
+ `pd'.
+ See [IA32-v2a] "MOV--Move to/from Control Registers" and
+ [IA32-v3] 3.7.5. */
uint32_t *pd;
-
- asm ("movl %%cr3,%0" : "=r" (pd));
+ asm ("mov %0, %%cr3" : "=r" (pd));
return pd;
}