[patch v9 10/23] remote, btrace: add branch tracing protocol to Qbtrace packet

[Markus Metzger <markus dot t dot metzger at intel dot com>]

We might want to add support for LBR branch tracing in the future.

To prepare for this, I would specify the branch trace recording method
in the Qbtrace packet when requesting branch tracing.

Similar to qXfer, I am adding separate packets for each recording method plus
one packet to disable tracing.  The currently supported packets are:

  Qbtrace:off
  Qbtrace:bts

CC: Pedro Alves <palves@redhat.com>


2013-03-04  Markus Metzger  <markus.t.metzger@intel.com>
---
 gdb/doc/gdb.texinfo    |   18 +++++++++---
 gdb/gdbserver/server.c |    7 +++--
 gdb/remote.c           |   69 +++++++++++++++++++++++++----------------------
 3 files changed, 54 insertions(+), 40 deletions(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 5ac450c..337675c 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -37321,7 +37321,12 @@ These are the currently defined stub features and their properties:
 @tab @samp{-}
 @tab Yes
 
-@item @samp{Qbtrace}
+@item @samp{Qbtrace:off}
+@tab Yes
+@tab @samp{-}
+@tab Yes
+
+@item @samp{Qbtrace:bts}
 @tab Yes
 @tab @samp{-}
 @tab Yes
@@ -37562,8 +37567,11 @@ rather than reporting the hit to @value{GDBN}.
 @item qbtrace
 The remote stub understands the @samp{qbtrace} packet.
 
-@item Qbtrace
-The remote stub understands the @samp{Qbtrace} packet.
+@item Qbtrace:off
+The remote stub understands the @samp{Qbtrace:off} packet.
+
+@item Qbtrace:bts
+The remote stub understands the @samp{Qbtrace:bts} packet.
 
 @end table
 
@@ -37942,8 +37950,8 @@ No new branch trace data is available.
 A badly formed request or an error was encountered.
 @end table
 
-@item Qbtrace:on
-Enable branch tracing for the current thread.
+@item Qbtrace:bts
+Enable branch tracing for the current thread using bts tracing.
 
 Reply:
 @table @samp
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index e755ba0..00cac8e 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -463,12 +463,12 @@ handle_btrace_general_set (char *own_buf)
 
   err = NULL;
 
-  if (strcmp (op, "on") == 0)
+  if (strcmp (op, "bts") == 0)
     err = handle_btrace_enable (thread);
   else if (strcmp (op, "off") == 0)
     err = handle_btrace_disable (thread);
   else
-    err = "E.Bad Qbtrace operation. Use on or off.";
+    err = "E.Bad Qbtrace operation. Use bts or off.";
 
   if (err != 0)
     strcpy (own_buf, err);
@@ -1828,7 +1828,8 @@ handle_query (char *own_buf, int packet_len, int *new_packet_len_p)
       if (target_supports_btrace ())
 	{
 	  strcat (own_buf, ";qbtrace+");
-	  strcat (own_buf, ";Qbtrace+");
+	  strcat (own_buf, ";Qbtrace:bts+");
+	  strcat (own_buf, ";Qbtrace:off+");
 	  strcat (own_buf, ";qXfer:btrace:read+");
 	}
 
diff --git a/gdb/remote.c b/gdb/remote.c
index 787c596..2365713 100755
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -1286,7 +1286,8 @@ enum {
   PACKET_QDisableRandomization,
   PACKET_QAgent,
   PACKET_qbtrace,
-  PACKET_Qbtrace,
+  PACKET_Qbtrace_off,
+  PACKET_Qbtrace_bts,
   PACKET_qXfer_btrace,
   PACKET_MAX
 };
@@ -4000,7 +4001,8 @@ static struct protocol_feature remote_protocol_features[] = {
   { "tracenz", PACKET_DISABLE,
     remote_string_tracing_feature, -1 },
   { "qbtrace", PACKET_DISABLE, remote_supported_packet, PACKET_qbtrace },
-  { "Qbtrace", PACKET_DISABLE, remote_supported_packet, PACKET_Qbtrace },
+  { "Qbtrace:off", PACKET_DISABLE, remote_supported_packet, PACKET_Qbtrace_off },
+  { "Qbtrace:bts", PACKET_DISABLE, remote_supported_packet, PACKET_Qbtrace_bts },
   { "qXfer:btrace:read", PACKET_DISABLE, remote_supported_packet,
     PACKET_qXfer_btrace }
 };
@@ -11140,7 +11142,9 @@ remote_supports_btrace (void)
 {
   if (remote_protocol_packets[PACKET_qbtrace].support != PACKET_ENABLE)
     return 0;
-  if (remote_protocol_packets[PACKET_Qbtrace].support != PACKET_ENABLE)
+  if (remote_protocol_packets[PACKET_Qbtrace_off].support != PACKET_ENABLE)
+    return 0;
+  if (remote_protocol_packets[PACKET_Qbtrace_bts].support != PACKET_ENABLE)
     return 0;
   if (remote_protocol_packets[PACKET_qXfer_btrace].support != PACKET_ENABLE)
     return 0;
@@ -11148,12 +11152,13 @@ remote_supports_btrace (void)
   return 1;
 }
 
-/* Send the Qbtrace packet and check the response. */
+/* Enable branch tracing.  */
 
-static void
-send_Qbtrace (ptid_t ptid, int enable)
+static struct btrace_target_info *
+remote_enable_btrace (ptid_t ptid)
 {
-  struct packet_config *packet = &remote_protocol_packets[PACKET_Qbtrace];
+  struct btrace_target_info *tinfo = NULL;
+  struct packet_config *packet = &remote_protocol_packets[PACKET_Qbtrace_bts];
   struct remote_state *rs = get_remote_state ();
   char *buf = rs->buf;
   char *endbuf = rs->buf + get_remote_packet_size ();
@@ -11163,31 +11168,13 @@ send_Qbtrace (ptid_t ptid, int enable)
 
   set_general_thread (ptid);
 
-  buf += xsnprintf (buf, endbuf - buf, "%s:", packet->name);
-  buf += xsnprintf (buf, endbuf - buf, enable ? "on" : "off");
+  buf += xsnprintf (buf, endbuf - buf, "%s", packet->name);
   putpkt (rs->buf);
   getpkt (&rs->buf, &rs->buf_size, 0);
 
   if (packet_ok (rs->buf, packet) == PACKET_ERROR)
-    {
-      if (enable != 0)
-	error (_("Could not enable branch tracing for %s: %s"),
-	       target_pid_to_str (ptid), rs->buf);
-      else
-	error (_("Could not disable branch tracing for %s: %s"),
-	       target_pid_to_str (ptid), rs->buf);
-    }
-}
-
-/* Enable branch tracing.  */
-
-static struct btrace_target_info *
-remote_enable_btrace (ptid_t ptid)
-{
-  struct btrace_target_info *tinfo = NULL;
-
-  /* This will throw an error if enabling failed.  */
-  send_Qbtrace (ptid, 1);
+    error (_("Could not enable branch tracing for %s: %s"),
+	   target_pid_to_str (ptid), rs->buf);
 
   tinfo = xzalloc (sizeof (*tinfo));
   tinfo->ptid = ptid;
@@ -11200,8 +11187,23 @@ remote_enable_btrace (ptid_t ptid)
 static void
 remote_disable_btrace (struct btrace_target_info *tinfo)
 {
-  /* This will throw an error if disabling failed.  */
-  send_Qbtrace (tinfo->ptid, 0);
+  struct packet_config *packet = &remote_protocol_packets[PACKET_Qbtrace_off];
+  struct remote_state *rs = get_remote_state ();
+  char *buf = rs->buf;
+  char *endbuf = rs->buf + get_remote_packet_size ();
+
+  if (packet->support != PACKET_ENABLE)
+    error (_("Target does not support branch tracing."));
+
+  set_general_thread (tinfo->ptid);
+
+  buf += xsnprintf (buf, endbuf - buf, "%s", packet->name);
+  putpkt (rs->buf);
+  getpkt (&rs->buf, &rs->buf_size, 0);
+
+  if (packet_ok (rs->buf, packet) == PACKET_ERROR)
+    error (_("Could not disable branch tracing for %s: %s"),
+	   target_pid_to_str (tinfo->ptid), rs->buf);
 
   xfree (tinfo);
 }
@@ -11927,8 +11929,11 @@ Show the maximum size of the address (in bits) in a memory packet."), NULL,
   add_packet_config_cmd (&remote_protocol_packets[PACKET_qbtrace],
        "qbtrace", "query-btrace", 0);
 
-  add_packet_config_cmd (&remote_protocol_packets[PACKET_Qbtrace],
-       "Qbtrace", "enable-btrace", 0);
+  add_packet_config_cmd (&remote_protocol_packets[PACKET_Qbtrace_off],
+       "Qbtrace:off", "disable-btrace", 0);
+
+  add_packet_config_cmd (&remote_protocol_packets[PACKET_Qbtrace_bts],
+       "Qbtrace:bts", "enable-btrace", 0);
 
   add_packet_config_cmd (&remote_protocol_packets[PACKET_qXfer_btrace],
        "qXfer:btrace", "read-btrace", 0);
-- 
1.7.1