[patch v4 08/13] remote, btrace: add branch trace remote ops

[markus.t.metzger@intel.com]

From: Markus Metzger <markus.t.metzger@intel.com>

Add the gdb remote target operations for branch tracing. We define the following
packets:

  qbtrace:<ptid>  query if new trace data is available for a thread
                  returns "yes" or "no" or "Enn"

  Qbtrace:on:<ptid>  enable branch tracing for one thread
                     returns "OK" or "Enn"

  Qbtrace:off:<ptid>  disable branch tracing for one thread
                      returns "OK" or "Enn"

  qXfer:btrace:read:<ptid>   read the full branch trace data for one thread

2012-11-27 Markus Metzger <markus.t.metzger@intel.com>

	* target.h (enum target_object): Add TARGET_OBJECT_BTRACE.
	* remote.c (struct btrace_target_info): New struct.
	(remote_supports_btrace): New function.
	(remote_enable_btrace): New function.
	(remote_disable_btrace): New function.
	(remote_btrace_has_changed): New function.
	(remote_read_btrace): New function.
	(init_remote_ops): Add btrace ops.
	(enum <unnamed>): Add btrace packets.
	(struct protocol_feature remote_protocol_features[]): Add btrace packets.
	(_initialize_remote): Add btrace packets.


---
 gdb/remote.c |  157 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/target.h |    4 +-
 2 files changed, 160 insertions(+), 1 deletions(-)

diff --git a/gdb/remote.c b/gdb/remote.c
index 929d4f5..c512b93 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -67,6 +67,7 @@
 #include "ax.h"
 #include "ax-gdb.h"
 #include "agent.h"
+#include "btrace.h"
 
 /* Temp hacks for tracepoint encoding migration.  */
 static char *target_buf;
@@ -1292,6 +1293,9 @@ enum {
   PACKET_qXfer_fdpic,
   PACKET_QDisableRandomization,
   PACKET_QAgent,
+  PACKET_qbtrace,
+  PACKET_Qbtrace,
+  PACKET_qXfer_btrace,
   PACKET_MAX
 };
 
@@ -3946,6 +3950,10 @@ static struct protocol_feature remote_protocol_features[] = {
   { "QAgent", PACKET_DISABLE, remote_supported_packet, PACKET_QAgent},
   { "tracenz", PACKET_DISABLE,
     remote_string_tracing_feature, -1 },
+  { "qbtrace", PACKET_DISABLE, remote_supported_packet, PACKET_qbtrace },
+  { "Qbtrace", PACKET_DISABLE, remote_supported_packet, PACKET_Qbtrace },
+  { "qXfer:btrace:read", PACKET_DISABLE, remote_supported_packet,
+    PACKET_qXfer_btrace }
 };
 
 static char *remote_support_xml;
@@ -8682,6 +8690,10 @@ remote_xfer_partial (struct target_ops *ops, enum target_object object,
       return remote_read_qxfer (ops, "uib", annex, readbuf, offset, len,
 				&remote_protocol_packets[PACKET_qXfer_uib]);
 
+    case TARGET_OBJECT_BTRACE:
+      return remote_read_qxfer (ops, "btrace", annex, readbuf, offset, len,
+        &remote_protocol_packets[PACKET_qXfer_btrace]);
+
     default:
       return -1;
     }
@@ -11001,6 +11013,137 @@ remote_can_use_agent (void)
   return (remote_protocol_packets[PACKET_QAgent].support != PACKET_DISABLE);
 }
 
+struct btrace_target_info
+{
+  /* The ptid of the traced thread.  */
+  ptid_t ptid;
+};
+
+/* Check whether the target supports branch tracing.  */
+static int
+remote_supports_btrace (void)
+{
+  if (remote_protocol_packets[PACKET_qbtrace].support != PACKET_ENABLE)
+    return 0;
+  if (remote_protocol_packets[PACKET_Qbtrace].support != PACKET_ENABLE)
+    return 0;
+  if (remote_protocol_packets[PACKET_qXfer_btrace].support != PACKET_ENABLE)
+    return 0;
+
+  return 1;
+}
+
+/* Enable branch tracing for @ptid.  */
+static struct btrace_target_info *
+remote_enable_btrace (ptid_t ptid)
+{
+  struct packet_config *packet = &remote_protocol_packets[PACKET_Qbtrace];
+  struct remote_state *rs = get_remote_state ();
+  struct btrace_target_info *tinfo = NULL;
+  char *buf = rs->buf;
+  char *endbuf = rs->buf + get_remote_packet_size ();
+
+  if (packet->support != PACKET_ENABLE)
+    error (_("Target does not support branch tracing."));
+
+  buf += xsnprintf (buf, endbuf - buf, "%s", packet->name);
+  buf += xsnprintf (buf, endbuf - buf, ":on:");
+  buf = write_ptid (buf, endbuf, ptid);
+  putpkt (rs->buf);
+  getpkt (&rs->buf, &rs->buf_size, 0);
+
+  if (packet_ok (rs->buf, packet) != PACKET_OK)
+    error (_("Could not enable branch tracing for %s."),
+           target_pid_to_str (ptid));
+
+  tinfo = xzalloc (sizeof (*tinfo));
+  tinfo->ptid = ptid;
+
+  return tinfo;
+}
+
+/* Disable branch tracing.  */
+static void
+remote_disable_btrace (struct btrace_target_info *tinfo)
+{
+  struct packet_config *packet = &remote_protocol_packets[PACKET_Qbtrace];
+  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."));
+
+  buf += xsnprintf (buf, endbuf - buf, "%s", packet->name);
+  buf += xsnprintf (buf, endbuf - buf, ":off:");
+  buf = write_ptid (buf, endbuf, tinfo->ptid);
+  putpkt (rs->buf);
+  getpkt (&rs->buf, &rs->buf_size, 0);
+
+  if (packet_ok (rs->buf, packet) != PACKET_OK)
+    error (_("Could not disable branch tracing for %s."),
+           target_pid_to_str (tinfo->ptid));
+
+  xfree (tinfo);
+}
+
+/* Check whether branch trace data has changed.  */
+static int
+remote_btrace_has_changed (struct btrace_target_info *tinfo)
+{
+  struct packet_config *packet = &remote_protocol_packets[PACKET_qbtrace];
+  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."));
+
+  buf += xsnprintf (buf, endbuf - buf, "%s", packet->name);
+  buf += xsnprintf (buf, endbuf - buf, ":");
+  buf = write_ptid (buf, endbuf, tinfo->ptid);
+  putpkt (rs->buf);
+  getpkt (&rs->buf, &rs->buf_size, 0);
+
+  if (packet_ok (rs->buf, packet) != PACKET_OK)
+    error (_("Failed to check for branch trace data for %s."),
+           target_pid_to_str (tinfo->ptid));
+
+  return (strcmp (rs->buf, "yes") == 0);
+}
+
+/* Read the branch trace.  */
+static VEC (btrace_block_s) *
+remote_read_btrace (struct btrace_target_info *tinfo)
+{
+  struct packet_config *packet = &remote_protocol_packets[PACKET_qXfer_btrace];
+  struct remote_state *rs = get_remote_state ();
+  char *xml, annex[64], *pend;
+  VEC (btrace_block_s) *btrace = NULL;
+
+  if (packet->support != PACKET_ENABLE)
+    error (_("Target does not support branch tracing."));
+
+#if !defined(HAVE_LIBEXPAT)
+  error (_("Cannot process branch tracing result. XML parsing not supported."));
+#endif
+
+  memset (annex, 0, sizeof (annex));
+  pend = write_ptid (annex, annex + sizeof (annex), tinfo->ptid);
+
+  xml = target_read_stralloc (&current_target,
+                              TARGET_OBJECT_BTRACE, annex);
+  if (xml)
+    {
+      struct cleanup *cleanup = make_cleanup (xfree, xml);
+
+      btrace = parse_xml_btrace (xml);
+      do_cleanups (cleanup);
+    }
+
+  return btrace;
+}
+
 static void
 init_remote_ops (void)
 {
@@ -11117,6 +11260,11 @@ Specify the serial device it is connected to\n\
   remote_ops.to_traceframe_info = remote_traceframe_info;
   remote_ops.to_use_agent = remote_use_agent;
   remote_ops.to_can_use_agent = remote_can_use_agent;
+  remote_ops.to_supports_btrace = remote_supports_btrace;
+  remote_ops.to_enable_btrace = remote_enable_btrace;
+  remote_ops.to_disable_btrace = remote_disable_btrace;
+  remote_ops.to_btrace_has_changed = remote_btrace_has_changed;
+  remote_ops.to_read_btrace = remote_read_btrace;
 }
 
 /* Set up the extended remote vector by making a copy of the standard
@@ -11643,6 +11791,15 @@ Show the maximum size of the address (in bits) in a memory packet."), NULL,
   add_packet_config_cmd (&remote_protocol_packets[PACKET_QAgent],
 			 "QAgent", "agent", 0);
 
+  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_qXfer_btrace],
+       "qXfer:btrace", "read-btrace", 0);
+
   /* Keep the old ``set remote Z-packet ...'' working.  Each individual
      Z sub-packet has its own set and show commands, but users may
      have sets to this variable in their .gdbinit files (or in their
diff --git a/gdb/target.h b/gdb/target.h
index 4889ce4..ffdd512 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -287,7 +287,9 @@ enum target_object
   /* Darwin dynamic linker info data.  */
   TARGET_OBJECT_DARWIN_DYLD_INFO,
   /* OpenVMS Unwind Information Block.  */
-  TARGET_OBJECT_OPENVMS_UIB
+  TARGET_OBJECT_OPENVMS_UIB,
+  /* Branch trace data, in XML format.  */
+  TARGET_OBJECT_BTRACE
   /* Possible future objects: TARGET_OBJECT_FILE, ...  */
 };
 
-- 
1.7.1