X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fuserprog%2Fexception.c;h=4f3e4f9d120efcef5ddecf1fb845956e0e44f40d;hb=c9d2f441f65d0c3a92938df02a752e6c78de487d;hp=79ba7a921b61042e111cce1b0c6231f7ed1cc8ea;hpb=ff7d61d07724b3a00e9ba408a5ae88f9df559c21;p=pintos-anon

diff --git a/src/userprog/exception.c b/src/userprog/exception.c
index 79ba7a9..4f3e4f9 100644
--- a/src/userprog/exception.c
+++ b/src/userprog/exception.c
@@ -1,9 +1,9 @@
-#include "exception.h"
+#include "userprog/exception.h"
 #include <inttypes.h>
-#include "lib.h"
-#include "gdt.h"
-#include "interrupt.h"
-#include "thread.h"
+#include <stdio.h>
+#include "userprog/gdt.h"
+#include "threads/interrupt.h"
+#include "threads/thread.h"
 
 static void kill (struct intr_frame *);
 static void page_fault (struct intr_frame *);
@@ -12,9 +12,10 @@ static void page_fault (struct intr_frame *);
    programs.
 
    In a real Unix-like OS, most of these interrupts would be
-   passed along to the user process in the form of signals, but
-   we don't implement signals.  Instead, we'll make them simply
-   kill the user process.
+   passed along to the user process in the form of signals, as
+   described in [SV-386] 3-24 and 3-25, but we don't implement
+   signals.  Instead, we'll make them simply kill the user
+   process.
 
    Page faults are an exception.  Here they are treated the same
    way as other exceptions, but this will need to change to
@@ -72,9 +73,8 @@ kill (struct intr_frame *f)
     case SEL_UCSEG:
       /* User's code segment, so it's a user exception, as we
          expected.  Kill the user process.  */
-      printk ("%s: dying due to interrupt %#04x (%s).\n",
-              thread_name (thread_current ()),
-              f->vec_no, intr_name (f->vec_no));
+      printf ("%s: dying due to interrupt %#04x (%s).\n",
+              thread_name (), f->vec_no, intr_name (f->vec_no));
       intr_dump_frame (f);
       thread_exit (); 
 
@@ -89,7 +89,7 @@ kill (struct intr_frame *f)
     default:
       /* Some other code segment?  Shouldn't happen.  Panic the
          kernel. */
-      printk ("Interrupt %#04x (%s) in unknown segment %04x\n",
+      printf ("Interrupt %#04x (%s) in unknown segment %04x\n",
              f->vec_no, intr_name (f->vec_no), f->cs);
       thread_exit ();
     }
@@ -101,7 +101,8 @@ kill (struct intr_frame *f)
 #define PF_U 0x4    /* 0: kernel, 1: user process. */
 
 /* Page fault handler.  This is a skeleton that must be filled in
-   to implement virtual memory.
+   to implement virtual memory.  Some solutions to project 2 may
+   also require modifying this code.
 
    At entry, the address that faulted is in CR2 (Control Register
    2) and information about the fault, formatted as described in
@@ -116,24 +117,27 @@ page_fault (struct intr_frame *f)
   bool not_present, write, user;
   uint32_t fault_addr;
 
-  /* Determine cause. */
-  not_present = (f->error_code & PF_P) == 0;
-  write = (f->error_code & PF_W) != 0;
-  user = (f->error_code & PF_U) != 0;
-
-  /* Obtain faulting address.
+  /* Obtain faulting address, then turn interrupts back on.
+     (Interrupts were only off so that we could be assured of
+     reading CR2 before it changed.)
 
-     (The faulting address is not necesarily the address of the
+     The faulting address is not necesarily the address of the
      instruction that caused the fault--that's in F's eip
      member.  Rather, it's the linear address that was accessed
      to cause the fault, which is probably an address of data,
-     not code.) */
+     not code. */
   asm ("movl %%cr2, %0" : "=r" (fault_addr));
+  intr_enable ();
+
+  /* Determine cause. */
+  not_present = (f->error_code & PF_P) == 0;
+  write = (f->error_code & PF_W) != 0;
+  user = (f->error_code & PF_U) != 0;
 
   /* To implement virtual memory, delete the rest of the function
      body, and replace it with code that brings in the page to
      which fault_addr refers. */
-  printk ("Page fault on address %08"PRIx32": %s %s page in %s context.\n",
+  printf ("Page fault at %08"PRIx32": %s error %s page in %s context.\n",
           fault_addr,
           not_present ? "not present" : "rights violation",
           write ? "writing" : "reading",