X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fthreads%2Fpaging.c;h=ca5f4b49ac0e56ea4c1bad738230f26f9c83e69e;hb=f6580e9ad405b519dbe85027691bf3c66074b0a4;hp=9fd568caf894107e02b09edda8dff05d9d060d9e;hpb=a98578bf3b6b5c946713654b404a886a7199dbee;p=pintos-anon

diff --git a/src/threads/paging.c b/src/threads/paging.c
index 9fd568c..ca5f4b4 100644
--- a/src/threads/paging.c
+++ b/src/threads/paging.c
@@ -2,35 +2,28 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include "init.h"
-#include "lib.h"
 #include "mmu.h"
 #include "palloc.h"
+#include "lib/lib.h"
 
 static uint32_t *base_page_dir;
 
-static uint32_t
-make_pde (uint32_t *pagetab) 
-{
-  ASSERT (pg_ofs (pagetab) == 0);
-  
-  return vtop (pagetab) | PG_U | PG_P | PG_W;
+static uint32_t make_pde (uint32_t *pt) {
+  ASSERT (pg_ofs (pt) == 0);
+  return vtop (pt) | PG_U | PG_P | PG_W;
 }
 
-static uint32_t
-make_pte (uint32_t *page, bool writable)
-{
-  uint32_t entry;
-
+static uint32_t make_kernel_pte (uint32_t *page, bool writable) {
   ASSERT (pg_ofs (page) == 0);
-  
-  entry = vtop (page) | PG_U | PG_P;
-  if (writable)
-    entry |= PG_W;
-  return entry;
+  return vtop (page) | PG_P | (writable ? PG_W : 0);
+}
+
+static uint32_t make_user_pte (uint32_t *page, bool writable) {
+  return make_kernel_pte (page, writable) | PG_U;
 }
 
 static uint32_t *
-pde_get_pagetab (uint32_t pde) 
+pde_get_pt (uint32_t pde) 
 {
   ASSERT (pde & PG_P);
 
@@ -50,9 +43,9 @@ pte_get_page (uint32_t pte)
    new page directory.
 
    At the time this function is called, the active page table
-   only maps the first 4 MB of RAM, so it should not try to use
-   extravagant amounts of memory.  Fortunately, there is no need
-   to do so. */
+   (set up by loader.S) only maps the first 4 MB of RAM, so we
+   should not try to use extravagant amounts of memory.
+   Fortunately, there is no need to do so. */
 void
 paging_init (void)
 {
@@ -74,11 +67,10 @@ paging_init (void)
           pd[pde_idx] = make_pde (pt);
         }
 
-      pt[pte_idx] = make_pte (vaddr, true);
+      pt[pte_idx] = make_kernel_pte (vaddr, true);
     }
 
-  /* Set the page table. */
-  asm volatile ("movl %0,%%cr3" :: "r" (vtop (pd)));
+  pagedir_activate (pd);
 }
 
 uint32_t *
@@ -93,57 +85,73 @@ void
 pagedir_destroy (uint32_t *pd) 
 {
   void *kpage, *upage;
+  unsigned pde_idx;
 
+  /* Destroy user pages. */
   for (kpage = pagedir_first (pd, &upage); kpage != NULL;
        kpage = pagedir_next (pd, &upage)) 
     palloc_free (kpage);
+
+  /* Destroy page table pages. */
+  for (pde_idx = 0; pde_idx < pd_no (PHYS_BASE); pde_idx++) 
+    {
+      uint32_t pde = pd[pde_idx];
+
+      if (pde != 0) 
+        {
+          uint32_t *pt = pde_get_pt (pde);
+          palloc_free (pt);
+        }
+    }
+
+  /* Destroy page directory. */
   palloc_free (pd);
 }
 
 static uint32_t *
-lookup_page (uint32_t *pagedir, void *upage, bool create)
+lookup_page (uint32_t *pd, void *upage, bool create)
 {
-  uint32_t *pagetab;
+  uint32_t *pt;
   uint32_t *pde;
 
-  ASSERT (pagedir != NULL);
+  ASSERT (pd != NULL);
   ASSERT (pg_ofs (upage) == 0);
   ASSERT (upage < PHYS_BASE);
 
   /* Check for a page table for UPAGE.
      If one is missing, create one if requested. */
-  pde = pagedir + pd_no (upage);
+  pde = pd + pd_no (upage);
   if (*pde == 0) 
     {
       if (create)
         {
-          pagetab = palloc_get (PAL_ZERO);
-          if (pagetab == NULL) 
+          pt = palloc_get (PAL_ZERO);
+          if (pt == NULL) 
             return NULL; 
       
-          *pde = make_pde (pagetab);
+          *pde = make_pde (pt);
         }
       else
         return NULL;
     }
 
   /* Return the page table entry. */
-  pagetab = pde_get_pagetab (*pde);
-  return &pagetab[pt_no (upage)];
+  pt = pde_get_pt (*pde);
+  return &pt[pt_no (upage)];
 }
 
 bool
-pagedir_set_page (uint32_t *pagedir, void *upage, void *kpage,
+pagedir_set_page (uint32_t *pd, void *upage, void *kpage,
                   bool writable) 
 {
   uint32_t *pte;
 
   ASSERT (pg_ofs (kpage) == 0);
 
-  pte = lookup_page (pagedir, upage, true);
+  pte = lookup_page (pd, upage, true);
   if (pte != NULL) 
     {
-      *pte = make_pte (kpage, writable);
+      *pte = make_user_pte (kpage, writable);
       return true;
     }
   else
@@ -151,16 +159,16 @@ pagedir_set_page (uint32_t *pagedir, void *upage, void *kpage,
 }
 
 void *
-pagedir_get_page (uint32_t *pagedir, void *upage) 
+pagedir_get_page (uint32_t *pd, void *upage) 
 {
-  uint32_t *pte = lookup_page (pagedir, upage, false);
+  uint32_t *pte = lookup_page (pd, upage, false);
   return pte != NULL && *pte != 0 ? pte_get_page (*pte) : NULL;
 }
 
 void
-pagedir_clear_page (uint32_t *pagedir, void *upage)
+pagedir_clear_page (uint32_t *pd, void *upage)
 {
-  uint32_t *pte = lookup_page (pagedir, upage, false);
+  uint32_t *pte = lookup_page (pd, upage, false);
   if (pte != NULL)
     *pte = 0;
 }
@@ -195,7 +203,7 @@ scan_pd (uint32_t *pd, unsigned pde_idx, void **upage)
 
       if (pde != 0) 
         {
-          void *kpage = scan_pt (pde_get_pagetab (pde), pde_idx, 0, upage);
+          void *kpage = scan_pt (pde_get_pt (pde), pde_idx, 0, upage);
           if (kpage != NULL)
             return kpage;
         }
@@ -205,9 +213,9 @@ scan_pd (uint32_t *pd, unsigned pde_idx, void **upage)
 }
 
 void *
-pagedir_first (uint32_t *pagedir, void **upage) 
+pagedir_first (uint32_t *pd, void **upage) 
 {
-  return scan_pd (pagedir, 0, upage);
+  return scan_pd (pd, 0, upage);
 }
 
 void *
@@ -218,11 +226,17 @@ pagedir_next (uint32_t *pd, void **upage)
 
   pde_idx = pd_no (*upage);
   pte_idx = pt_no (*upage);
-  kpage = scan_pt (pde_get_pagetab (pd[pde_idx]),
+  kpage = scan_pt (pde_get_pt (pd[pde_idx]),
                    pde_idx, pte_idx + 1, upage);
   if (kpage == NULL)
     kpage = scan_pd (pd, pde_idx + 1, upage);
   return kpage;
 }
 
-void pagedir_activate (uint32_t *pagedir);
+void
+pagedir_activate (uint32_t *pd) 
+{
+  if (pd == NULL)
+    pd = base_page_dir;
+  asm volatile ("movl %0,%%cr3" :: "r" (vtop (pd)));
+}