Record a thread's last four fault locations.

3 files changed, 45 insertions, 7 deletions

diff --git a/viengoos/server.c b/viengoos/server.c
index eca721f..4caddf8 100644
--- a/viengoos/server.c
+++ b/viengoos/server.c
@@ -122,8 +122,12 @@ page_fault_handler (struct thread *thread, uintptr_t fault, int access)
 	 (fault & MEM_WRITABLE) ? "Write" : "Read", fault,
 	 thread_ip (thread), thread_sp (thread));
 
-  thread->last_fault = fault;
-  thread->last_fault_ip = thread_ip (thread);
+  thread->last_fault[thread->last_fault_idx] = fault;
+  thread->last_fault_ip[thread->last_fault_idx] = thread_ip (thread);
+  thread->last_fault_idx ++;
+  if (thread->last_fault_idx
+      == sizeof (thread->last_fault) / sizeof (thread->last_fault[0]))
+    thread->last_fault_idx = 0;
 
   struct activity *activity
     = (struct activity *) vg_cap_to_object (root_activity,
diff --git a/viengoos/thread.c b/viengoos/thread.c
index 7f7a2cb..e647793 100644
--- a/viengoos/thread.c
+++ b/viengoos/thread.c
@@ -79,7 +79,7 @@ thread_dump (int argc, char *argv[])
 	  "time: %d ns (last payout at %ld.%09ld s)\n"
 	  "total time: %ld.%09ld s\n"
 	  "\n"
-	  "last fault: %"PRIxPTR" (ip: %"PRIxPTR")\n",
+	  "last fault:\n",
 	  REGS_PRINTF (thread),
 	  VG_CAP_PRINTF (&thread->aspace),
 	  VG_CAP_PRINTF (&thread->activity),
@@ -90,8 +90,41 @@ thread_dump (int argc, char *argv[])
 	  thread->last_payout / 1000 / 1000 / 1000,
 	  thread->last_payout % (1000 * 1000 * 1000),
 	  thread->total_time / 1000 / 1000 / 1000,
-	  thread->total_time % (1000 * 1000 * 1000),
-	  thread->last_fault, thread->last_fault_ip);
+	  thread->total_time % (1000 * 1000 * 1000));
+
+  int cnt = sizeof (thread->last_fault) / sizeof (thread->last_fault[0]);
+  int i;
+  for (i = -1; i >= -cnt; i --)
+    {
+      int idx = (cnt + thread->last_fault_idx + i) % cnt;
+      printf ("  %d: %"PRIxPTR" (%"PRIxPTR")\n",
+	      i, thread->last_fault[idx], thread->last_fault_ip[idx]);
+    }
+
+  struct vg_object *object = vg_cap_to_object (root_activity, &thread->utcb);
+  if (object)
+    {
+      struct vg_utcb *utcb = (struct vg_utcb *) object;
+      printf ("\nUTCB:\n"
+	      " activated mode: %d\n"
+	      " pending_message: %d\n"
+	      " interrupt in transition: %d\n"
+	      " saved ip: %"PRIxPTR"\n"
+	      " saved sp: %"PRIxPTR"\n"
+	      " activation handler sp: %"PRIxPTR"\n"
+	      " activation handler ip: %"PRIxPTR"\n"
+	      " activation handler end: %"PRIxPTR"\n"
+	      " messenger id: %"PRIxPTR"\n",
+	      utcb->activated_mode,
+	      utcb->pending_message,
+	      utcb->interrupt_in_transition,
+	      utcb->saved_ip,
+	      utcb->saved_sp,
+	      utcb->activation_handler_sp,
+	      utcb->activation_handler_ip,
+	      utcb->activation_handler_end,
+	      utcb->messenger_id);
+    }
 }
 
 static struct debug_command debug_command =
diff --git a/viengoos/thread.h b/viengoos/thread.h
index ea6b49e..a1826ac 100644
--- a/viengoos/thread.h
+++ b/viengoos/thread.h
@@ -86,8 +86,9 @@ struct thread
   struct vg_object_name name;
 
   /* The last fault.  */
-  uintptr_t last_fault;
-  uintptr_t last_fault_ip;
+  int last_fault_idx;
+  uintptr_t last_fault[4];
+  uintptr_t last_fault_ip[4];
 
   enum thread_state state;
   struct list_node run_queue_node;