Make backtraces slightly more reliable.

[pintos-anon] / src / lib / debug.c

diff --git a/src/lib/debug.c b/src/lib/debug.c
index 577ab67f06c39f60f8fd606d157b6a8a564916bd..1dc1bf8fd69db3c5651654620dcf79200cbf6844 100644 (file)
--- a/src/lib/debug.c
+++ b/src/lib/debug.c
@@ -1,19 +1,32 @@
-#include "debug.h"
+#include <debug.h>
 #include <stdarg.h>
-#include "interrupt.h"
-#include "lib.h"
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
 
+/* Prints the call stack, that is, a list of addresses, one in
+   each of the functions we are nested within.  gdb or addr2line
+   may be applied to kernel.o to translate these into file names,
+   line numbers, and function names.  */
 void
-panic (const char *format, ...)
+debug_backtrace (void) 
 {
-  va_list args;
+  static bool explained;
+  void **frame;
+  
+  printf ("Call stack:");
+  for (frame = __builtin_frame_address (0);
+       (uintptr_t) frame >= 0x1000 && frame[0] != NULL;
+       frame = frame[0]) 
+    printf (" %p", frame[1]);
+  printf (".\n");
 
-  intr_disable ();
-
-  va_start (args, format);
-  vprintk (format, args);
-  printk ("\n");
-  va_end (args);
-
-  for (;;);
+  if (!explained) 
+    {
+      explained = true;
+      printf ("The `backtrace' program can make call stacks useful.\n"
+              "Read \"Backtraces\" in the \"Debugging Tools\" chapter\n"
+              "of the Pintos documentation for more information.\n");
+    }
 }