Set up a frame pointer on interrupt entry, to improve backtraces of

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

diff --git a/src/userprog/process.c b/src/userprog/process.c
index 08e78c683e0024af747573e9fb78e48d63aee4e2..88c9d8dcae20995bb5e7dc3b4b2d5a42ca5b8e6e 100644 (file)
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -31,7 +31,7 @@ process_execute (const char *filename)
 
   /* Make a copy of FILENAME.
      Otherwise there's a race between the caller and load(). */
-  fn_copy = palloc_get (0);
+  fn_copy = palloc_get_page (0);
   if (fn_copy == NULL)
     return TID_ERROR;
   strlcpy (fn_copy, filename, PGSIZE);
@@ -39,7 +39,7 @@ process_execute (const char *filename)
   /* Create a new thread to execute FILENAME. */
   tid = thread_create (filename, PRI_DEFAULT, execute_thread, fn_copy);
   if (tid == TID_ERROR)
-    palloc_free (fn_copy); 
+    palloc_free_page (fn_copy); 
   return tid;
 }
 
@@ -54,6 +54,8 @@ execute_thread (void *filename_)
 
   /* Initialize interrupt frame and load executable. */
   memset (&if_, 0, sizeof if_);
+  if_.gs = SEL_UDSEG;
+  if_.fs = SEL_UDSEG;
   if_.es = SEL_UDSEG;
   if_.ds = SEL_UDSEG;
   if_.cs = SEL_UCSEG;
@@ -62,7 +64,7 @@ execute_thread (void *filename_)
   success = load (filename, &if_.eip, &if_.esp);
 
   /* If load failed, quit. */
-  palloc_free (filename);
+  palloc_free_page (filename);
   if (!success) 
     thread_exit ();
 
@@ -71,28 +73,32 @@ execute_thread (void *filename_)
 
   /* Start the user process by simulating a return from an
      interrupt, implemented by intr_exit (in
-     threads/intr-stubs.pl).  Because intr_exit takes all of its
+     threads/intr-stubs.S).  Because intr_exit takes all of its
      arguments on the stack in the form of a `struct intr_frame',
      we just point the stack pointer (%esp) to our stack frame
      and jump to it. */
-  asm ("mov %0, %%esp\n"
-       "jmp intr_exit\n"
-       : /* no outputs */
-       : "g" (&if_));
+  asm ("mov %%esp, %0; jmp intr_exit" :: "g" (&if_));
   NOT_REACHED ();
 }
 
-/* Destroys the user address space in T and frees all of its
-   resources. */
+/* Free the current process's resources. */
 void
-process_destroy (struct thread *t)
+process_exit (void)
 {
-  ASSERT (t != thread_current ());
-
-  if (t->pagedir != NULL) 
+  struct thread *cur = thread_current ();
+  uint32_t *pd;
+
+  /* Destroy the current process's page directory and switch back
+     to the kernel-only page directory.  We have to set
+     cur->pagedir to NULL before switching page directories, or a
+     timer interrupt might switch back to the process page
+     directory. */
+  pd = cur->pagedir;
+  if (pd != NULL) 
     {
-      pagedir_destroy (t->pagedir);
-      t->pagedir = NULL; 
+      cur->pagedir = NULL;
+      pagedir_activate (NULL);
+      pagedir_destroy (pd);
     }
 }
 
@@ -103,10 +109,11 @@ process_activate (void)
 {
   struct thread *t = thread_current ();
 
-  /* Activate T's page tables. */
+  /* Activate thread's page tables. */
   pagedir_activate (t->pagedir);
 
-  /* Set T's kernel stack for use in processing interrupts. */
+  /* Set thread's kernel stack for use in processing
+     interrupts. */
   tss_set_esp0 ((uint8_t *) t + PGSIZE);
 }
 \f
@@ -219,7 +226,7 @@ load (const char *filename, void (**eip) (void), void **esp)
   if (ehdr.e_machine != 3)
     LOAD_ERROR (("ELF executable is not x86"));
   if (ehdr.e_version != 1)
-    LOAD_ERROR (("ELF executable hasunknown version %d",
+    LOAD_ERROR (("ELF executable has unknown version %d",
                  (int) ehdr.e_version));
   if (ehdr.e_phentsize != sizeof (struct Elf32_Phdr))
     LOAD_ERROR (("bad ELF program header size"));
@@ -232,7 +239,10 @@ load (const char *filename, void (**eip) (void), void **esp)
     {
       struct Elf32_Phdr phdr;
 
+      if (file_ofs < 0 || file_ofs > file_length (file))
+        LOAD_ERROR (("bad file offset %ld", (long) file_ofs));
       file_seek (file, file_ofs);
+
       if (file_read (file, &phdr, sizeof phdr) != sizeof phdr)
         LOAD_ERROR (("error reading program header"));
       file_ofs += sizeof phdr;
@@ -308,6 +318,13 @@ load_segment (struct file *file, const struct Elf32_Phdr *phdr)
       return false; 
     }
 
+  /* p_offset must point within file. */
+  if (phdr->p_offset > (Elf32_Off) file_length (file)) 
+    {
+      printf ("bad p_offset %"PE32Ox, phdr->p_offset);
+      return false;
+    }
+
   /* [ELF1] 2-3 says that p_memsz must be at least as big as
      p_filesz. */
   if (phdr->p_memsz < phdr->p_filesz) 
@@ -339,14 +356,14 @@ load_segment (struct file *file, const struct Elf32_Phdr *phdr)
          file into the page and zero the rest. */
       size_t read_bytes = filesz_left >= PGSIZE ? PGSIZE : filesz_left;
       size_t zero_bytes = PGSIZE - read_bytes;
-      uint8_t *kpage = palloc_get (PAL_USER);
+      uint8_t *kpage = palloc_get_page (PAL_USER);
       if (kpage == NULL)
         return false;
 
       /* Do the reading and zeroing. */
       if (file_read (file, kpage, read_bytes) != (int) read_bytes) 
         {
-          palloc_free (kpage);
+          palloc_free_page (kpage);
           return false; 
         }
       memset (kpage + read_bytes, 0, zero_bytes);
@@ -355,7 +372,7 @@ load_segment (struct file *file, const struct Elf32_Phdr *phdr)
       /* Add the page to the process's address space. */
       if (!install_page (upage, kpage)) 
         {
-          palloc_free (kpage);
+          palloc_free_page (kpage);
           return false; 
         }
     }
@@ -371,14 +388,14 @@ setup_stack (void **esp)
   uint8_t *kpage;
   bool success = false;
 
-  kpage = palloc_get (PAL_USER | PAL_ZERO);
+  kpage = palloc_get_page (PAL_USER | PAL_ZERO);
   if (kpage != NULL) 
     {
       success = install_page (((uint8_t *) PHYS_BASE) - PGSIZE, kpage);
       if (success)
         *esp = PHYS_BASE;
       else
-        palloc_free (kpage);
+        palloc_free_page (kpage);
     }
   else
     printf ("failed to allocate process stack\n");