Add memory clobbers to several asm statements,

[pintos-anon] / src / userprog / pagedir.c

diff --git a/src/userprog/pagedir.c b/src/userprog/pagedir.c
index 5e7fa9293f2850eb16cc876d2b728deaad42c222..30bdfe263b67f58ee9787b413036de6984c7628b 100644 (file)
--- a/src/userprog/pagedir.c
+++ b/src/userprog/pagedir.c
@@ -3,7 +3,7 @@
 #include <stddef.h>
 #include <string.h>
 #include "threads/init.h"
-#include "threads/mmu.h"
+#include "threads/pte.h"
 #include "threads/palloc.h"
 
 static uint32_t *active_pd (void);
@@ -34,13 +34,13 @@ pagedir_destroy (uint32_t *pd)
 
   ASSERT (pd != base_page_dir);
   for (pde = pd; pde < pd + pd_no (PHYS_BASE); pde++)
-    if (*pde & PG_P) 
+    if (*pde & PTE_P) 
       {
         uint32_t *pt = pde_get_pt (*pde);
         uint32_t *pte;
         
         for (pte = pt; pte < pt + PGSIZE / sizeof *pte; pte++)
-          if (*pte & PG_P) 
+          if (*pte & PTE_P) 
             palloc_free_page (pte_get_page (*pte));
         palloc_free_page (pt);
       }
@@ -85,18 +85,18 @@ lookup_page (uint32_t *pd, const void *vaddr, bool create)
   return &pt[pt_no (vaddr)];
 }
 
-/* Adds a mapping from user virtual page UPAGE to kernel virtual
-   address KPAGE in page directory PD.
+/* Adds a mapping in page directory PD from user virtual page
+   UPAGE to the physical frame identified by kernel virtual
+   address KPAGE.
    UPAGE must not already be mapped.
    KPAGE should probably be a page obtained from the user pool
-   with palloc_get_page() .
+   with palloc_get_page().
    If WRITABLE is true, the new page is read/write;
    otherwise it is read-only.
    Returns true if successful, false if memory allocation
    failed. */
 bool
-pagedir_set_page (uint32_t *pd, void *upage, void *kpage,
-                  bool writable) 
+pagedir_set_page (uint32_t *pd, void *upage, void *kpage, bool writable)
 {
   uint32_t *pte;
 
@@ -110,7 +110,7 @@ pagedir_set_page (uint32_t *pd, void *upage, void *kpage,
 
   if (pte != NULL) 
     {
-      ASSERT ((*pte & PG_P) == 0);
+      ASSERT ((*pte & PTE_P) == 0);
       *pte = pte_create_user (kpage, writable);
       return true;
     }
@@ -118,9 +118,10 @@ pagedir_set_page (uint32_t *pd, void *upage, void *kpage,
     return false;
 }
 
-/* Returns the kernel virtual address that user virtual address
-   UADDR is mapped to in PD, or a null pointer if UADDR is not
-   present. */
+/* Looks up the physical address that corresponds to user virtual
+   address UADDR in PD.  Returns the kernel virtual address
+   corresponding to that physical address, or a null pointer if
+   UADDR is unmapped. */
 void *
 pagedir_get_page (uint32_t *pd, const void *uaddr) 
 {
@@ -129,7 +130,7 @@ pagedir_get_page (uint32_t *pd, const void *uaddr)
   ASSERT (is_user_vaddr (uaddr));
   
   pte = lookup_page (pd, uaddr, false);
-  if (pte != NULL && (*pte & PG_P) != 0)
+  if (pte != NULL && (*pte & PTE_P) != 0)
     return pte_get_page (*pte) + pg_ofs (uaddr);
   else
     return NULL;
@@ -148,9 +149,9 @@ pagedir_clear_page (uint32_t *pd, void *upage)
   ASSERT (is_user_vaddr (upage));
 
   pte = lookup_page (pd, upage, false);
-  if (pte != NULL && (*pte & PG_P) != 0)
+  if (pte != NULL && (*pte & PTE_P) != 0)
     {
-      *pte &= ~PG_P;
+      *pte &= ~PTE_P;
       invalidate_pagedir (pd);
     }
 }
@@ -163,7 +164,7 @@ bool
 pagedir_is_dirty (uint32_t *pd, const void *vpage) 
 {
   uint32_t *pte = lookup_page (pd, vpage, false);
-  return pte != NULL && (*pte & PG_D) != 0;
+  return pte != NULL && (*pte & PTE_D) != 0;
 }
 
 /* Set the dirty bit to DIRTY in the PTE for virtual page VPAGE
@@ -175,10 +176,10 @@ pagedir_set_dirty (uint32_t *pd, const void *vpage, bool dirty)
   if (pte != NULL) 
     {
       if (dirty)
-        *pte |= PG_D;
+        *pte |= PTE_D;
       else 
         {
-          *pte &= ~(uint32_t) PG_D;
+          *pte &= ~(uint32_t) PTE_D;
           invalidate_pagedir (pd);
         }
     }
@@ -192,7 +193,7 @@ bool
 pagedir_is_accessed (uint32_t *pd, const void *vpage) 
 {
   uint32_t *pte = lookup_page (pd, vpage, false);
-  return pte != NULL && (*pte & PG_A) != 0;
+  return pte != NULL && (*pte & PTE_A) != 0;
 }
 
 /* Sets the accessed bit to ACCESSED in the PTE for virtual page
@@ -204,10 +205,10 @@ pagedir_set_accessed (uint32_t *pd, const void *vpage, bool accessed)
   if (pte != NULL) 
     {
       if (accessed)
-        *pte |= PG_A;
+        *pte |= PTE_A;
       else 
         {
-          *pte &= ~(uint32_t) PG_A; 
+          *pte &= ~(uint32_t) PTE_A; 
           invalidate_pagedir (pd);
         }
     }
@@ -224,8 +225,9 @@ pagedir_activate (uint32_t *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 ("movl %0, %%cr3" :: "r" (vtop (pd)));
+     to/from Control Registers" and [IA32-v3a] 3.7.5 "Base
+     Address of the Page Directory". */
+  asm volatile ("movl %0, %%cr3" : : "r" (vtop (pd)) : "memory");
 }
 
 /* Returns the currently active page directory. */
@@ -235,7 +237,7 @@ 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. */
+     [IA32-v3a] 3.7.5 "Base Address of the Page Directory". */
   uintptr_t pd;
   asm volatile ("movl %%cr3, %0" : "=r" (pd));
   return ptov (pd);
@@ -254,9 +256,8 @@ invalidate_pagedir (uint32_t *pd)
 {
   if (active_pd () == pd) 
     {
-      /* We cleared a page-table entry in the active page
-         table, so we have to invalidate the TLB.  See
-         [IA32-v3], section 3.11. */
+      /* Re-activating PD clears the TLB.  See [IA32-v3a] 3.12
+         "Translation Lookaside Buffers (TLBs)". */
       pagedir_activate (pd);
     } 
 }