* [PATCH v2 1/1] btrace: Resume recording after disconnect.
2016-07-19 7:45 [PATCH v2 0/1] btrace: Resume recording after disconnect Tim Wiederhake
@ 2016-07-19 7:45 ` Tim Wiederhake
2016-07-21 16:17 ` Pedro Alves
0 siblings, 1 reply; 3+ messages in thread
From: Tim Wiederhake @ 2016-07-19 7:45 UTC (permalink / raw)
To: gdb-patches; +Cc: palves, markus.t.metzger
This patch allows gdbserver to continue recording after disconnect. On
reconnect, the recorded data is accessible to gdb as if no disconnect happened.
A possible application for this feature is remotely examine bugs that occur
at irregular intervals, where maintaining a gdb connection is inconvenient.
This also fixes the issue mentioned here:
https://sourceware.org/ml/gdb-patches/2015-11/msg00424.html
2016-07-19 Tim Wiederhake <tim.wiederhake@intel.com>
gdb/ChangeLog:
* NEWS: Resume btrace on reconnect.
* record-btrace.c: Added record-btrace.h include.
(record_btrace_open): Split into this and ...
(record_btrace_push_target): ... this.
(record_btrace_disconnect): New function.
(init_record_btrace_ops): Use record_btrace_disconnect.
* record-btrace.h: New file.
* remote.c: Added record-btrace.h include.
(remote_start_remote): Check recording status.
(remote_btrace_maybe_reopen): New function.
gdb/doc/ChangeLog:
* gdb.texinfo: Resume btrace on reconnect.
gdb/testsuite/ChangeLog:
* gdb.btrace/reconnect.c: New file.
* gdb.btrace/reconnect.exp: New file.
---
gdb/NEWS | 3 ++
gdb/doc/gdb.texinfo | 4 +-
gdb/record-btrace.c | 51 ++++++++++++++++++------
gdb/record-btrace.h | 28 +++++++++++++
gdb/remote.c | 61 ++++++++++++++++++++++++++++
gdb/testsuite/gdb.btrace/reconnect.c | 25 ++++++++++++
gdb/testsuite/gdb.btrace/reconnect.exp | 73 ++++++++++++++++++++++++++++++++++
7 files changed, 231 insertions(+), 14 deletions(-)
create mode 100644 gdb/record-btrace.h
create mode 100644 gdb/testsuite/gdb.btrace/reconnect.c
create mode 100644 gdb/testsuite/gdb.btrace/reconnect.exp
diff --git a/gdb/NEWS b/gdb/NEWS
index 3823f20..c1d7cab 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,9 @@
*** Changes since GDB 7.11
+* GDBserver now supports record btrace without maintaining an active
+ GDB connection.
+
* GDB now supports a negative repeat count in the 'x' command to examine
memory backward from the given address. For example:
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index a068622..6e2cebf 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -6631,7 +6631,9 @@ Hardware-supported instruction recording. This method does not record
data. Further, the data is collected in a ring buffer so old data will
be overwritten when the buffer is full. It allows limited reverse
execution. Variables and registers are not available during reverse
-execution.
+execution. In remote debugging, recording continues on disconnect.
+Recorded data can be inspected after reconnecting. The recording may
+be stopped using @code{record stop}.
The recording format can be specified as parameter. Without a parameter
the command chooses the recording format. The following recording
diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 24594a9..4a51b8e 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -21,6 +21,7 @@
#include "defs.h"
#include "record.h"
+#include "record-btrace.h"
#include "gdbthread.h"
#include "target.h"
#include "gdbcmd.h"
@@ -199,6 +200,26 @@ record_btrace_handle_async_inferior_event (gdb_client_data data)
inferior_event_handler (INF_REG_EVENT, NULL);
}
+/* See record-btrace.h. */
+
+void
+record_btrace_push_target (void)
+{
+ const char *format;
+
+ record_btrace_auto_enable ();
+
+ push_target (&record_btrace_ops);
+
+ record_btrace_async_inferior_event_handler
+ = create_async_event_handler (record_btrace_handle_async_inferior_event,
+ NULL);
+ record_btrace_generating_corefile = 0;
+
+ format = btrace_format_short_string (record_btrace_conf.format);
+ observer_notify_record_changed (current_inferior (), 1, "btrace", format);
+}
+
/* The to_open method of target record-btrace. */
static void
@@ -206,7 +227,6 @@ record_btrace_open (const char *args, int from_tty)
{
struct cleanup *disable_chain;
struct thread_info *tp;
- const char *format;
DEBUG ("open");
@@ -226,17 +246,7 @@ record_btrace_open (const char *args, int from_tty)
make_cleanup (record_btrace_disable_callback, tp);
}
- record_btrace_auto_enable ();
-
- push_target (&record_btrace_ops);
-
- record_btrace_async_inferior_event_handler
- = create_async_event_handler (record_btrace_handle_async_inferior_event,
- NULL);
- record_btrace_generating_corefile = 0;
-
- format = btrace_format_short_string (record_btrace_conf.format);
- observer_notify_record_changed (current_inferior (), 1, "btrace", format);
+ record_btrace_push_target ();
discard_cleanups (disable_chain);
}
@@ -257,6 +267,21 @@ record_btrace_stop_recording (struct target_ops *self)
btrace_disable (tp);
}
+/* The to_disconnect method of target record-btrace. */
+
+static void
+record_btrace_disconnect (struct target_ops *self, const char *args,
+ int from_tty)
+{
+ struct target_ops *beneath = self->beneath;
+
+ /* Do not stop recording, just clean up GDB side. */
+ unpush_target (self);
+
+ /* Forward disconnect. */
+ beneath->to_disconnect (beneath, args, from_tty);
+}
+
/* The to_close method of target record-btrace. */
static void
@@ -2824,7 +2849,7 @@ init_record_btrace_ops (void)
ops->to_close = record_btrace_close;
ops->to_async = record_btrace_async;
ops->to_detach = record_detach;
- ops->to_disconnect = record_disconnect;
+ ops->to_disconnect = record_btrace_disconnect;
ops->to_mourn_inferior = record_mourn_inferior;
ops->to_kill = record_kill;
ops->to_stop_recording = record_btrace_stop_recording;
diff --git a/gdb/record-btrace.h b/gdb/record-btrace.h
new file mode 100644
index 0000000..d2062b8
--- /dev/null
+++ b/gdb/record-btrace.h
@@ -0,0 +1,28 @@
+/* Branch trace support for GDB, the GNU debugger.
+
+ Copyright (C) 2016 Free Software Foundation, Inc.
+
+ Contributed by Intel Corp. <tim.wiederhake@intel.com>
+
+ This file is part of GDB.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+#ifndef RECORD_BTRACE_H
+#define RECORD_BTRACE_H
+
+/* Push the record_btrace target. */
+extern void record_btrace_push_target (void);
+
+#endif /* RECORD_BTRACE_H */
diff --git a/gdb/remote.c b/gdb/remote.c
index 501f3c6..4158ad8 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -70,6 +70,7 @@
#include "ax-gdb.h"
#include "agent.h"
#include "btrace.h"
+#include "record-btrace.h"
/* Temp hacks for tracepoint encoding migration. */
static char *target_buf;
@@ -231,6 +232,8 @@ static int remote_can_run_breakpoint_commands (struct target_ops *self);
static void remote_btrace_reset (void);
+static void remote_btrace_maybe_reopen (void);
+
static int stop_reply_queue_length (void);
static void readahead_cache_invalidate (void);
@@ -4298,6 +4301,10 @@ remote_start_remote (int from_tty, struct target_ops *target, int extended_p)
merge_uploaded_tracepoints (&uploaded_tps);
}
+ /* Possibly the target has been engaged in a btrace record started
+ previously; find out where things are at. */
+ remote_btrace_maybe_reopen ();
+
/* The thread and inferior lists are now synchronized with the
target, our symbols have been relocated, and we're merged the
target's tracepoints with ours. We're done with basic start
@@ -12774,6 +12781,60 @@ btrace_read_config (struct btrace_config *conf)
}
}
+/* Maybe reopen target btrace. */
+
+static void
+remote_btrace_maybe_reopen (void)
+{
+ struct remote_state *rs = get_remote_state ();
+ struct cleanup *cleanup;
+ struct thread_info *tp;
+ int btrace_target_pushed = 0;
+ int warned = 0;
+
+ cleanup = make_cleanup_restore_current_thread ();
+ ALL_NON_EXITED_THREADS (tp)
+ {
+ set_general_thread (tp->ptid);
+
+ memset (&rs->btrace_config, 0x00, sizeof (struct btrace_config));
+ btrace_read_config (&rs->btrace_config);
+
+ if (rs->btrace_config.format == BTRACE_FORMAT_NONE)
+ continue;
+
+#if !defined (HAVE_LIBIPT)
+ if (rs->btrace_config.format == BTRACE_FORMAT_PT)
+ {
+ if (!warned)
+ {
+ warned = 1;
+ warning (_("GDB does not support Intel Processor Trace. "
+ "\"record\" will not work in this session."));
+ }
+
+ continue;
+ }
+#endif /* !defined (HAVE_LIBIPT) */
+
+ /* Push target, once, but before anything else happens. This way our
+ changes to the threads will be cleaned up by unpushing the target
+ in case btrace_read_config () throws. */
+ if (!btrace_target_pushed)
+ {
+ btrace_target_pushed = 1;
+ record_btrace_push_target ();
+ printf_filtered (_("Target is recording using %s.\n"),
+ btrace_format_string (rs->btrace_config.format));
+ }
+
+ tp->btrace.target = XCNEW (struct btrace_target_info);
+ tp->btrace.target->ptid = tp->ptid;
+ tp->btrace.target->conf = rs->btrace_config;
+ }
+ do_cleanups (cleanup);
+}
+
/* Enable branch tracing. */
static struct btrace_target_info *
diff --git a/gdb/testsuite/gdb.btrace/reconnect.c b/gdb/testsuite/gdb.btrace/reconnect.c
new file mode 100644
index 0000000..f2a9d35
--- /dev/null
+++ b/gdb/testsuite/gdb.btrace/reconnect.c
@@ -0,0 +1,25 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2016 Free Software Foundation, Inc.
+
+ Contributed by Intel Corp. <tim.wiederhake@intel.com>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+
+int
+main (void)
+{
+ return 0;
+}
diff --git a/gdb/testsuite/gdb.btrace/reconnect.exp b/gdb/testsuite/gdb.btrace/reconnect.exp
new file mode 100644
index 0000000..266ecb4
--- /dev/null
+++ b/gdb/testsuite/gdb.btrace/reconnect.exp
@@ -0,0 +1,73 @@
+# This testcase is part of GDB, the GNU debugger.
+#
+# Copyright 2016 Free Software Foundation, Inc.
+#
+# Contributed by Intel Corp. <tim.wiederhake@intel.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+load_lib gdbserver-support.exp
+
+if { [skip_btrace_tests] } { return -1 }
+if { [skip_gdbserver_tests] } { return -1 }
+
+standard_testfile
+if [prepare_for_testing $testfile.exp $testfile $srcfile] {
+ return -1
+}
+
+# Make sure we're disconnected and no recording is active, in case
+# we're testing with an extended-remote board, therefore already
+# connected.
+gdb_test "record stop" ".*" "preparation record stop"
+gdb_test "disconnect" ".*" "preparation disconnect"
+
+# Start fresh gdbserver.
+set gdbserver_reconnect_p 1
+set res [gdbserver_start "" $binfile]
+set gdbserver_protocol [lindex $res 0]
+set gdbserver_gdbport [lindex $res 1]
+gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport
+
+# Create a record.
+gdb_test_no_output "record btrace" "record btrace enable" "first record btrace"
+gdb_test "stepi 19" "0x.* in .* from target.*" "stepi"
+gdb_test "info record" [multi_line \
+ "Active record target: .*" \
+ "Recorded 19 instructions in .+ functions \\(. gaps\\) for thread 1 \\(Thread .*\\)."
+] "first info record"
+
+# Reconnect.
+gdb_test "disconnect" "Ending remote debugging." "first reconnect"
+gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport
+
+# Test if we can access the recorded data from first connect.
+# Note: BTS loses the first function call entry with its associated
+# instructions for technical reasons. This is why we test for
+# "a number between 10 and 19", so we catch at least the case where
+# there are 0 instructions in the record.
+gdb_test "info record" [multi_line \
+ "Active record target: .*" \
+ "Recorded 1. instructions in .+ functions \\(. gaps\\) for thread 1 \\(Thread .*\\)."
+] "second info record"
+
+# Stop recording.
+gdb_test "record stop" "Process record is stopped and all execution logs are deleted."
+
+# Reconnect.
+gdb_test "disconnect" "Ending remote debugging." "second reconnect"
+gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport
+
+# Test that recording is now off.
+gdb_test "info record" "No record target is currently active." "third info record"
--
2.7.4
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