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

Markus Metzger
2013-03-04T17:07:26Z

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