[patch v9 05/23] remote, btrace: add branch trace remote ops

Markus Metzger
2013-03-04T17:07:31Z

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

qbtrace query the current thread if new trace data is available
returns "yes" or "no" or "Enn"

Qbtrace:on enable branch tracing for the current thread
returns "OK" or "Enn"

Qbtrace:off disable branch tracing for the current thread
returns "OK" or "Enn"

qXfer:btrace:read read the full branch trace data for the current thread

2013-03-04 Markus Metzger <markus.t.metzger@intel.com>

* target.h (enum target_object): Add TARGET_OBJECT_BTRACE.
* remote.c: Include btrace.h.
(struct btrace_target_info): New struct.
(remote_supports_btrace): New function.
(send_Qbtrace): 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 packet configuration for branch tracing.

---
gdb/remote.c | 178 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
gdb/target.h | 4 +-
2 files changed, 181 insertions(+), 1 deletions(-)
mode change 100644 => 100755 gdb/remote.c

diff --git a/gdb/remote.c b/gdb/remote.c
old mode 100644
new mode 100755
index 88a57c8..787c596
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -68,6 +68,7 @@
#include "ax.h"
#include "ax-gdb.h"
#include "agent.h"
+#include "btrace.h"

/* Temp hacks for tracepoint encoding migration. */
static char *target_buf;
@@ -1284,6 +1285,9 @@ enum {
PACKET_qXfer_fdpic,
PACKET_QDisableRandomization,
PACKET_QAgent,
+ PACKET_qbtrace,
+ PACKET_Qbtrace,
+ PACKET_qXfer_btrace,
PACKET_MAX
};

@@ -3995,6 +3999,10 @@ 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;
@@ -8796,6 +8804,10 @@ 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;
}
@@ -11115,6 +11127,158 @@ 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;
+}
+
+/* Send the Qbtrace packet and check the response. */
+
+static void
+send_Qbtrace (ptid_t ptid, int enable)
+{
+ 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."));
+
+ set_general_thread (ptid);
+
+ buf += xsnprintf (buf, endbuf - buf, "%s:", packet->name);
+ buf += xsnprintf (buf, endbuf - buf, enable ? "on" : "off");
+ 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);
+
+ tinfo = xzalloc (sizeof (*tinfo));
+ tinfo->ptid = ptid;
+
+ return tinfo;
+}
+
+/* Disable branch tracing. */
+
+static void
+remote_disable_btrace (struct btrace_target_info *tinfo)
+{
+ /* This will throw an error if disabling failed. */
+ send_Qbtrace (tinfo->ptid, 0);
+
+ 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."));
+
+ set_general_thread (tinfo->ptid);
+
+ buf += xsnprintf (buf, endbuf - buf, "%s", packet->name);
+ putpkt (rs->buf);
+ getpkt (&rs->buf, &rs->buf_size, 0);
+
+ switch (packet_ok (rs->buf, packet))
+ {
+ case PACKET_OK:
+ break;
+
+ case PACKET_UNKNOWN:
+ return 0;
+
+ case PACKET_ERROR:
+ error (_("Failed to check for branch trace data for %s: %s."),
+ target_pid_to_str (tinfo->ptid), rs->buf);
+ }
+
+ if (strcmp (rs->buf, "yes") == 0)
+ return 1;
+
+ if (strcmp (rs->buf, "no") == 0)
+ return 0;
+
+ error (_("Bad remote reply: %s."), rs->buf);
+
+ return 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 ();
+ VEC (btrace_block_s) *btrace = NULL;
+ char *xml;
+
+ 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
+
+ xml = target_read_stralloc (&current_target,
+ TARGET_OBJECT_BTRACE, NULL);
+ if (xml != NULL)
+ {
+ struct cleanup *cleanup = make_cleanup (xfree, xml);
+
+ btrace = parse_xml_btrace (xml);
+ do_cleanups (cleanup);
+ }
+
+ return btrace;
+}
+
static void
init_remote_ops (void)
{
@@ -11231,6 +11395,11 @@ 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
@@ -11755,6 +11924,15 @@ 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 628c108..c543118 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