X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fuserprog%2Fpagedir.c;h=f26496d79467aa316e5b0f13953c2c07eb6d4fa4;hb=8382bdd7884a6d38f7529e0517dd9a7083f4ce73;hp=6c819c790efb9afff04980dd2f162f0a6f3d5469;hpb=18f989e9fa405e5c3bd7b5f5458e22db0e28740b;p=pintos-anon

diff --git a/src/userprog/pagedir.c b/src/userprog/pagedir.c
index 6c819c7..f26496d 100644
--- a/src/userprog/pagedir.c
+++ b/src/userprog/pagedir.c
@@ -13,7 +13,7 @@
 uint32_t *
 pagedir_create (void) 
 {
-  uint32_t *pd = palloc_get (0);
+  uint32_t *pd = palloc_get_page (0);
   memcpy (pd, base_page_dir, PGSIZE);
   return pd;
 }
@@ -28,6 +28,7 @@ pagedir_destroy (uint32_t *pd)
   if (pd == NULL)
     return;
 
+  ASSERT (pd != base_page_dir);
   for (pde = pd; pde < pd + pd_no (PHYS_BASE); pde++)
     if (*pde & PG_P) 
       {
@@ -36,10 +37,10 @@ pagedir_destroy (uint32_t *pd)
         
         for (pte = pt; pte < pt + PGSIZE / sizeof *pte; pte++)
           if (*pte & PG_P) 
-            palloc_free (pte_get_page (*pte));
-        palloc_free (pt);
+            palloc_free_page (pte_get_page (*pte));
+        palloc_free_page (pt);
       }
-  palloc_free (pd);
+  palloc_free_page (pd);
 }
 
 /* Returns the mapping of user virtual address UADDR in page
@@ -47,14 +48,18 @@ pagedir_destroy (uint32_t *pd)
    If UADDR is unmapped, behavior varies based on CREATE:
    if CREATE is true, then a new, zeroed page is created and a
    pointer into it is returned,
-   otherwise a null pointer is returned. */
+   otherwise a null pointer is returned.
+   Also returns a null pointer if UADDR is a kernel address. */
 static uint32_t *
 lookup_page (uint32_t *pd, void *uaddr, bool create)
 {
   uint32_t *pt, *pde;
 
   ASSERT (pd != NULL);
-  ASSERT (uaddr < PHYS_BASE);
+
+  /* Make sure it's a user address. */
+  if (uaddr >= PHYS_BASE)
+    return NULL;
 
   /* Check for a page table for UADDR.
      If one is missing, create one if requested. */
@@ -63,7 +68,7 @@ lookup_page (uint32_t *pd, void *uaddr, bool create)
     {
       if (create)
         {
-          pt = palloc_get (PAL_ZERO);
+          pt = palloc_get_page (PAL_ZERO);
           if (pt == NULL) 
             return NULL; 
       
@@ -93,7 +98,8 @@ pagedir_set_page (uint32_t *pd, void *upage, void *kpage,
 
   ASSERT (pg_ofs (upage) == 0);
   ASSERT (pg_ofs (kpage) == 0);
-  ASSERT (lookup_page (pd, upage, false) == NULL);
+  ASSERT (upage < PHYS_BASE);
+  ASSERT (pagedir_get_page (pd, upage) == NULL);
 
   pte = lookup_page (pd, upage, true);
   if (pte != NULL)