Debug output tweaks in the Linux target backends

This adds/tweaks a few debug logs I found useful recently.

gdb/gdbserver/ChangeLog:
2015-03-24  Pedro Alves  <palves@redhat.com>

	* linux-low.c (check_stopped_by_breakpoint): Tweak debug log
	output.  Also dump TRAP_TRACE.
	(linux_low_filter_event): In debug output, distinguish a
	resume_stop SIGSTOP from a delayed SIGSTOP.

gdb/ChangeLog:
2015-03-24  Pedro Alves  <palves@redhat.com>

	* linux-nat.c (linux_nat_resume): Output debug logs before trying
	to resume the event lwp.  Use the lwp's ptid instead of the passed
	in (maybe wildcard) ptid.
	(stop_wait_callback): Tweak debug log output.
	(check_stopped_by_breakpoint): Tweak debug log output.  Also dump
	TRAP_TRACE.
	(linux_nat_filter_event): In debug output, distinguish a
	resume_stop SIGSTOP from a delayed SIGSTOP.  Output debug logs
	before trying to resume the lwp.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 43dda55..fc65c60 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,15 @@
+2015-03-24  Pedro Alves  <palves@redhat.com>
+
+       * linux-nat.c (linux_nat_resume): Output debug logs before trying
+       to resume the event lwp.  Use the lwp's ptid instead of the passed
+       in (maybe wildcard) ptid.
+       (stop_wait_callback): Tweak debug log output.
+       (check_stopped_by_breakpoint): Tweak debug log output.  Also dump
+       TRAP_TRACE.
+       (linux_nat_filter_event): In debug output, distinguish a
+       resume_stop SIGSTOP from a delayed SIGSTOP.  Output debug logs
+       before trying to resume the lwp.
+
 2015-03-24  Joel Brobecker  <brobecker@adacore.com>
 
        * gdbtypes.h (struct dynamic_prop_list) <prop>: Remove

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index d9bc729..396abcb 100644 (file)
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,10 @@
+2015-03-24  Pedro Alves  <palves@redhat.com>
+
+       * linux-low.c (check_stopped_by_breakpoint): Tweak debug log
+       output.  Also dump TRAP_TRACE.
+       (linux_low_filter_event): In debug output, distinguish a
+       resume_stop SIGSTOP from a delayed SIGSTOP.
+
 2015-03-24  Gary Benson  <gbenson@redhat.com>
 
        * linux-x86-low.c (x86_linux_new_thread): Moved to

diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index 4743f7b..e4c5420 100644 (file)
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -562,7 +562,7 @@ check_stopped_by_breakpoint (struct lwp_info *lwp)
                {
                  struct thread_info *thr = get_lwp_thread (lwp);
 
-                 debug_printf ("CSBB: Push back software breakpoint for %s\n",
+                 debug_printf ("CSBB: %s stopped by software breakpoint\n",
                                target_pid_to_str (ptid_of (thr)));
                }
 
@@ -585,8 +585,8 @@ check_stopped_by_breakpoint (struct lwp_info *lwp)
                {
                  struct thread_info *thr = get_lwp_thread (lwp);
 
-                 debug_printf ("CSBB: Push back hardware "
-                               "breakpoint/watchpoint for %s\n",
+                 debug_printf ("CSBB: %s stopped by hardware "
+                               "breakpoint/watchpoint\n",
                                target_pid_to_str (ptid_of (thr)));
                }
 
@@ -595,6 +595,16 @@ check_stopped_by_breakpoint (struct lwp_info *lwp)
              current_thread = saved_thread;
              return 1;
            }
+         else if (siginfo.si_code == TRAP_TRACE)
+           {
+             if (debug_threads)
+               {
+                 struct thread_info *thr = get_lwp_thread (lwp);
+
+                 debug_printf ("CSBB: %s stopped by trace\n",
+                               target_pid_to_str (ptid_of (thr)));
+               }
+           }
        }
     }
 #else
@@ -2059,16 +2069,28 @@ linux_low_filter_event (int lwpid, int wstat)
        {
          /* We want to report the stop to the core.  Treat the
             SIGSTOP as a normal event.  */
+         if (debug_threads)
+           debug_printf ("LLW: resume_stop SIGSTOP caught for %s.\n",
+                         target_pid_to_str (ptid_of (thread)));
        }
       else if (stopping_threads != NOT_STOPPING_THREADS)
        {
          /* Stopping threads.  We don't want this SIGSTOP to end up
             pending.  */
+         if (debug_threads)
+           debug_printf ("LLW: SIGSTOP caught for %s "
+                         "while stopping threads.\n",
+                         target_pid_to_str (ptid_of (thread)));
          return NULL;
        }
       else
        {
-         /* Filter out the event.  */
+         /* This is a delayed SIGSTOP.  Filter out the event.  */
+         if (debug_threads)
+           debug_printf ("LLW: %s %s, 0, 0 (discard delayed SIGSTOP)\n",
+                         child->stepping ? "step" : "continue",
+                         target_pid_to_str (ptid_of (thread)));
+
          linux_resume_one_lwp (child, child->stepping, 0, NULL);
          return NULL;
        }

diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 803bdf6..660dc8f 100644 (file)
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -1799,16 +1799,16 @@ linux_nat_resume (struct target_ops *ops,
   if (resume_many)
     iterate_over_lwps (ptid, linux_nat_resume_callback, lp);
 
-  linux_resume_one_lwp (lp, step, signo);
-
   if (debug_linux_nat)
     fprintf_unfiltered (gdb_stdlog,
                        "LLR: %s %s, %s (resume event thread)\n",
                        step ? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
-                       target_pid_to_str (ptid),
+                       target_pid_to_str (lp->ptid),
                        (signo != GDB_SIGNAL_0
                         ? strsignal (gdb_signal_to_host (signo)) : "0"));
 
+  linux_resume_one_lwp (lp, step, signo);
+
   if (target_can_async_p ())
     target_async (inferior_event_handler, 0);
 }
@@ -2618,7 +2618,7 @@ stop_wait_callback (struct lwp_info *lp, void *data)
 
          if (debug_linux_nat)
            fprintf_unfiltered (gdb_stdlog,
-                               "SWC: Delayed SIGSTOP caught for %s.\n",
+                               "SWC: Expected SIGSTOP caught for %s.\n",
                                target_pid_to_str (lp->ptid));
 
          /* Reset SIGNALLED only after the stop_wait_callback call
@@ -2795,8 +2795,8 @@ check_stopped_by_breakpoint (struct lwp_info *lp)
            {
              if (debug_linux_nat)
                fprintf_unfiltered (gdb_stdlog,
-                                   "CSBB: Push back software "
-                                   "breakpoint for %s\n",
+                                   "CSBB: %s stopped by software "
+                                   "breakpoint\n",
                                    target_pid_to_str (lp->ptid));
 
              /* Back up the PC if necessary.  */
@@ -2811,14 +2811,21 @@ check_stopped_by_breakpoint (struct lwp_info *lp)
            {
              if (debug_linux_nat)
                fprintf_unfiltered (gdb_stdlog,
-                                   "CSBB: Push back hardware "
-                                   "breakpoint/watchpoint for %s\n",
+                                   "CSBB: %s stopped by hardware "
+                                   "breakpoint/watchpoint\n",
                                    target_pid_to_str (lp->ptid));
 
              lp->stop_pc = pc;
              lp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
              return 1;
            }
+         else if (siginfo.si_code == TRAP_TRACE)
+           {
+             if (debug_linux_nat)
+               fprintf_unfiltered (gdb_stdlog,
+                                   "CSBB: %s stopped by trace\n",
+                                   target_pid_to_str (lp->ptid));
+           }
        }
     }
 #else
@@ -2830,7 +2837,7 @@ check_stopped_by_breakpoint (struct lwp_info *lp)
         breakpoint instruction.  */
       if (debug_linux_nat)
        fprintf_unfiltered (gdb_stdlog,
-                           "CB: Push back software breakpoint for %s\n",
+                           "CSBB: %s stopped by software breakpoint\n",
                            target_pid_to_str (lp->ptid));
 
       /* Back up the PC if necessary.  */
@@ -2846,7 +2853,7 @@ check_stopped_by_breakpoint (struct lwp_info *lp)
     {
       if (debug_linux_nat)
        fprintf_unfiltered (gdb_stdlog,
-                           "CB: Push back hardware breakpoint for %s\n",
+                           "CSBB: stopped by hardware breakpoint %s\n",
                            target_pid_to_str (lp->ptid));
 
       lp->stop_pc = pc;
@@ -3206,28 +3213,28 @@ linux_nat_filter_event (int lwpid, int status)
   if (lp->signalled
       && WIFSTOPPED (status) && WSTOPSIG (status) == SIGSTOP)
     {
-      if (debug_linux_nat)
-       fprintf_unfiltered (gdb_stdlog,
-                           "LLW: Delayed SIGSTOP caught for %s.\n",
-                           target_pid_to_str (lp->ptid));
-
       lp->signalled = 0;
 
-      if (lp->last_resume_kind != resume_stop)
+      if (lp->last_resume_kind == resume_stop)
        {
-         /* This is a delayed SIGSTOP.  */
+         if (debug_linux_nat)
+           fprintf_unfiltered (gdb_stdlog,
+                               "LLW: resume_stop SIGSTOP caught for %s.\n",
+                               target_pid_to_str (lp->ptid));
+       }
+      else
+       {
+         /* This is a delayed SIGSTOP.  Filter out the event.  */
 
-         linux_resume_one_lwp (lp, lp->step, GDB_SIGNAL_0);
          if (debug_linux_nat)
            fprintf_unfiltered (gdb_stdlog,
-                               "LLW: %s %s, 0, 0 (discard SIGSTOP)\n",
+                               "LLW: %s %s, 0, 0 (discard delayed SIGSTOP)\n",
                                lp->step ?
                                "PTRACE_SINGLESTEP" : "PTRACE_CONT",
                                target_pid_to_str (lp->ptid));
 
+         linux_resume_one_lwp (lp, lp->step, GDB_SIGNAL_0);
          gdb_assert (lp->resumed);
-
-         /* Discard the event.  */
          return NULL;
        }
     }