PR remote/18965: vforkdone stop reply should indicate parent PID

The vforkdone stop reply misses indicating the thread ID of the vfork parent which the event relates to: @cindex vfork events, remote reply @item vfork The packet indicates that @code{vfork} was called, and @var{r} is the thread ID of the new child process. Refer to @ref{thread-id syntax} for the format of the @var{thread-id} field. This packet is only applicable to targets that support vfork events. @cindex vforkdone events, remote reply @item vforkdone The packet indicates that a child process created by a vfork has either called @code{exec} or terminated, so that the address spaces of the parent and child process are no longer shared. The @var{r} part is ignored. This packet is only applicable to targets that support vforkdone events. Unfortunately, this is not just a documentation issue. GDBserver is really not specifying the thread ID. I noticed because in non-stop mode, gdb complains: [Thread 6089.6089] riscvarchive#1 stopped. #0 0x0000003615a011f0 in ?? () 0x0000003615a011f0 in ?? () (gdb) set debug remote 1 (gdb) c Continuing. Sending packet: $QPassSignals:e;10;14;17;1a;1b;1c;21;24;25;2c;4c;#5f...Packet received: OK Sending packet: $vCont;c:p17c9.17c9#88...Packet received: OK Notification received: Stop:T05vfork:p17ce.17ce;06:40d7ffffff7f0000;07:30d7ffffff7f0000;10:e4c9eb1536000000;thread:p17c9.17c9;core:2; Sending packet: $vStopped#55...Packet received: OK Sending packet: $D;17ce#af...Packet received: OK Sending packet: $vCont;c:p17c9.17c9#88...Packet received: OK Notification received: Stop:T05vforkdone:; No process or thread specified in stop reply: T05vforkdone:; (gdb) This is not non-stop-mode-specific, however. Consider e.g., that in all-stop, you may be debugging more than one process at the same time. You continue, and both processes vfork. So when you next get a T05vforkdone, there's no way to tell which of the parent processes is done with the vfork. Tests will be added later. Tested on x86_64 Fedora 20. gdb/ChangeLog: 2015-09-15 Pedro Alves <[email protected]> PR remote/18965 * remote-utils.c (prepare_resume_reply): Merge TARGET_WAITKIND_VFORK_DONE switch case with the TARGET_WAITKIND_FORKED case. gdb/doc/ChangeLog: 2015-09-15 Pedro Alves <[email protected]> PR remote/18965 * gdb.texinfo (Stop Reply Packets): Explain that vforkdone's 'r' part indicates the thread ID of the parent process.
palmer-dabbelt · Sep 15, 2015 · 8228463 · 8228463
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diff --git a/gdb/ChangeLog b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2015-09-15  Pedro Alves  <[email protected]>
+
+	PR remote/18965
+	* remote-utils.c (prepare_resume_reply): Merge
+	TARGET_WAITKIND_VFORK_DONE switch case with the
+	TARGET_WAITKIND_FORKED case.
+
 2015-09-15  Yao Qi  <[email protected]>
 
 	* aarch64-linux-nat.c (aarch64_linux_can_do_single_step): New

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
@@ -1,3 +1,9 @@
+2015-09-15  Pedro Alves  <[email protected]>
+
+	PR remote/18965
+	* gdb.texinfo (Stop Reply Packets): Explain that vforkdone's 'r'
+	part indicates the thread ID of the parent process.
+
 2015-09-15  Yao Qi  <[email protected]>
 
 	* gdb.texinfo (General Query Packets): Add vContSupported to

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
@@ -35498,11 +35498,12 @@ indicating support.
 
 @cindex vforkdone events, remote reply
 @item vforkdone
-The packet indicates that a child process created by a vfork
-has either called @code{exec} or terminated, so that the
-address spaces of the parent and child process are no longer
-shared. The @var{r} part is ignored.  This packet is only
-applicable to targets that support vforkdone events.
+The packet indicates that a child process created by a vfork has
+either called @code{exec} or terminated, so that the address spaces of
+the parent and child process are no longer shared.  The @var{r} part
+is the thread ID of the parent process.  Refer to @ref{thread-id
+syntax} for the format of the @var{thread-id} field.  This packet is
+only applicable to targets that support vforkdone events.
 
 This packet should not be sent by default; older @value{GDBN} versions
 did not support it.  @value{GDBN} requests it, by supplying an

diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c
@@ -1117,6 +1117,7 @@ prepare_resume_reply (char *buf, ptid_t ptid,
     case TARGET_WAITKIND_STOPPED:
     case TARGET_WAITKIND_FORKED:
     case TARGET_WAITKIND_VFORKED:
+    case TARGET_WAITKIND_VFORK_DONE:
     case TARGET_WAITKIND_EXECD:
       {
 	struct thread_info *saved_thread;
@@ -1135,6 +1136,12 @@ prepare_resume_reply (char *buf, ptid_t ptid,
 	    buf = write_ptid (buf, status->value.related_pid);
 	    strcat (buf, ";");
 	  }
+	else if (status->kind == TARGET_WAITKIND_VFORK_DONE && report_vfork_events)
+	  {
+	    enum gdb_signal signal = GDB_SIGNAL_TRAP;
+
+	    sprintf (buf, "T%02xvforkdone:;", signal);
+	  }
 	else if (status->kind == TARGET_WAITKIND_EXECD && multi_process)
 	  {
 	    enum gdb_signal signal = GDB_SIGNAL_TRAP;
@@ -1269,16 +1276,6 @@ prepare_resume_reply (char *buf, ptid_t ptid,
       else
 	sprintf (buf, "X%02x", status->value.sig);
       break;
-    case TARGET_WAITKIND_VFORK_DONE:
-      if (report_vfork_events)
-	{
-	  enum gdb_signal signal = GDB_SIGNAL_TRAP;
-
-	  sprintf (buf, "T%02xvforkdone:;", signal);
-	}
-      else
-	sprintf (buf, "T%02x", GDB_SIGNAL_0);
-      break;
     default:
       error ("unhandled waitkind");
       break;