implement page table and use it for lazy loading of segments

1 files changed, 15 insertions, 1 deletions

diff --git a/userprog/exception.c b/userprog/exception.c
index 17620ad..54621fa 100644
--- a/userprog/exception.c
+++ b/userprog/exception.c
@@ -5,6 +5,7 @@
 #include "threads/interrupt.h"
 #include "threads/thread.h"
 #include "threads/vaddr.h"
+#include "vm/page.h"
 
 /* Number of page faults processed. */
 static long long page_fault_cnt;
@@ -121,12 +122,13 @@ kill (struct intr_frame *f)
    description of "Interrupt 14--Page Fault Exception (#PF)" in
    [IA32-v3a] section 5.15 "Exception and Interrupt Reference". */
 static void
-page_fault (struct intr_frame *f) 
+page_fault (struct intr_frame *f)
 {
   bool not_present;  /* True: not-present page, false: writing r/o page. */
   bool write;        /* True: access was write, false: access was read. */
   bool user;         /* True: access by user, false: access by kernel. */
   void *fault_addr;  /* Fault address. */
+  struct page_table_entry *pte;
 
   /* Obtain faulting address, the virtual address that was
      accessed to cause the fault.  It may point to code or to
@@ -153,6 +155,17 @@ page_fault (struct intr_frame *f)
      body, adding code that brings in the page to
      which fault_addr refers. */
   if (is_user_vaddr(fault_addr)) {
+    pte = page_table_fetch (&thread_current ()->page_table, pg_round_down (fault_addr));
+    if (pte != NULL)
+      page_load (pte);
+    else
+    {
+      printf ("Page fault %p\n", pte);
+      kill (f);
+    }
+
+    //TODO
+#if 0
     if (! user) {
       /* syscall exception; set eax and eip */
       f->eip = (void*)f->eax;
@@ -162,6 +175,7 @@ page_fault (struct intr_frame *f)
       /* user process access violation */
       thread_exit();
     }
+#endif
   } else {
     printf ("Page fault at %p: %s error %s page in %s context.\n",
             fault_addr,