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 b8d4a14462c63faecf6ac69944db4180b83d2914..88c9d8dcae20995bb5e7dc3b4b2d5a42ca5b8e6e 100644 (file)
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -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;
@@ -71,14 +73,11 @@ 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 ();
 }
 
@@ -320,7 +319,7 @@ load_segment (struct file *file, const struct Elf32_Phdr *phdr)
     }
 
   /* p_offset must point within file. */
-  if (phdr->p_offset < 0 || phdr->p_offset > file_length (file)) 
+  if (phdr->p_offset > (Elf32_Off) file_length (file)) 
     {
       printf ("bad p_offset %"PE32Ox, phdr->p_offset);
       return false;