record btrace: add configuration struct

Add a struct to describe the branch trace configuration and use it for
enabling branch tracing.

The user will be able to set configuration fields for each tracing format
to be used for new threads.

The actual configuration that is active for a given thread will be shown
in the "info record" command.

At the moment, the configuration struct only contains a format field
that is set to the only available format.

The format is the only configuration option that can not be set via set
commands.  It is given as argument to the "record btrace" command when
starting recording.

2015-02-09  Markus Metzger  <markus.t.metzger@intel.com>

	* Makefile.in (XMLFILES): Add btrace-conf.dtd.
	* x86-linux-nat.c (x86_linux_enable_btrace): Update parameters.
	(x86_linux_btrace_conf): New.
	(x86_linux_create_target): Initialize to_btrace_conf.
	* nat/linux-btrace.c (linux_enable_btrace): Update parameters.
	Check format.  Split into this and ...
	(linux_enable_bts): ... this.
	(linux_btrace_conf): New.
	(perf_event_skip_record): Renamed into ...
	(perf_event_skip_bts_record): ... this.  Updated users.
	(linux_disable_btrace): Split into this and ...
	(linux_disable_bts): ... this.
	(linux_read_btrace): Check format.
	* nat/linux-btrace.h (linux_enable_btrace): Update parameters.
	(linux_btrace_conf): New.
	(btrace_target_info)<ptid>: Moved.
	(btrace_target_info)<conf>: New.
	(btrace_target_info): Split into this and ...
	(btrace_tinfo_bts): ... this.  Updated users.
	* btrace.c (btrace_enable): Update parameters.
	(btrace_conf, parse_xml_btrace_conf_bts, parse_xml_btrace_conf)
	(btrace_conf_children, btrace_conf_attributes)
	(btrace_conf_elements): New.
	* btrace.h (btrace_enable): Update parameters.
	(btrace_conf, parse_xml_btrace_conf): New.
	* common/btrace-common.h (btrace_config): New.
	* feature/btrace-conf.dtd: New.
	* record-btrace.c (record_btrace_conf): New.
	(record_btrace_cmdlist): New.
	(record_btrace_enable_warn, record_btrace_open): Pass
	&record_btrace_conf.
	(record_btrace_info): Print recording format.
	(cmd_record_btrace_bts_start): New.
	(cmd_record_btrace_start): Call cmd_record_btrace_bts_start.
	(_initialize_record_btrace): Add "record btrace bts" subcommand.
	Add "record bts" alias command.
	* remote.c (remote_state)<btrace_config>: New.
	(remote_btrace_reset, PACKET_qXfer_btrace_conf): New.
	(remote_protocol_features): Add qXfer:btrace-conf:read.
	(remote_open_1): Call remote_btrace_reset.
	(remote_xfer_partial): Handle TARGET_OBJECT_BTRACE_CONF.
	(btrace_target_info)<conf>: New.
	(btrace_sync_conf, btrace_read_config): New.
	(remote_enable_btrace): Update parameters.  Call btrace_sync_conf and
	btrace_read_conf.
	(remote_btrace_conf): New.
	(init_remote_ops): Initialize to_btrace_conf.
	(_initialize_remote): Add qXfer:btrace-conf packet.
	* target.c (target_enable_btrace): Update parameters.
	(target_btrace_conf): New.
	* target.h (target_enable_btrace): Update parameters.
	(target_btrace_conf): New.
	(target_object)<TARGET_OBJECT_BTRACE_CONF>: New.
	(target_ops)<to_enable_btrace>: Update parameters and comment.
	(target_ops)<to_btrace_conf>: New.
	* target-delegates: Regenerate.
	* target-debug.h (target_debug_print_const_struct_btrace_config_p)
	(target_debug_print_const_struct_btrace_target_info_p): New.
	NEWS: Announce new command and new packet.

doc/
	* gdb.texinfo (Process Record and Replay): Describe the "record
	btrace bts" command.
	(General Query Packets): Describe qXfer:btrace-conf:read packet.
	(Branch Trace Configuration Format): New.

gdbserver/
	* linux-low.c (linux_low_enable_btrace): Update parameters.
	(linux_low_btrace_conf): New.
	(linux_target_ops)<to_btrace_conf>: Initialize.
	* server.c (current_btrace_conf): New.
	(handle_btrace_enable): Rename to ...
	(handle_btrace_enable_bts): ... this.  Pass &current_btrace_conf
	to target_enable_btrace.  Update comment.  Update users.
	(handle_qxfer_btrace_conf): New.
    (qxfer_packets): Add btrace-conf entry.
	(handle_query): Report qXfer:btrace-conf:read as supported packet.
	* target.h (target_ops)<enable_btrace>: Update parameters and comment.
	(target_ops)<read_btrace_conf>: New.
	(target_enable_btrace): Update parameters.
	(target_read_btrace_conf): New.

testsuite/
	* gdb.btrace/delta.exp: Update "info record" output.
	* gdb.btrace/enable.exp: Update "info record" output.
	* gdb.btrace/finish.exp: Update "info record" output.
	* gdb.btrace/instruction_history.exp: Update "info record" output.
	* gdb.btrace/next.exp: Update "info record" output.
	* gdb.btrace/nexti.exp: Update "info record" output.
	* gdb.btrace/step.exp: Update "info record" output.
	* gdb.btrace/stepi.exp: Update "info record" output.
	* gdb.btrace/nohist.exp: Update "info record" output.

2 files changed, 72 insertions, 6 deletions

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 9c12d9a..b4a9cba 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,10 @@
+2015-02-09  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* gdb.texinfo (Process Record and Replay): Describe the "record
+	btrace bts" command.
+	(General Query Packets): Describe qXfer:btrace-conf:read packet.
+	(Branch Trace Configuration Format): New.
+
 2015-01-31  Gary Benson <gbenson@redhat.com>
 	    Doug Evans  <dje@google.com>
 
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index aee17d3..411f067 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -6372,9 +6372,13 @@ For architecture environments that support process record and replay,
 @kindex record
 @kindex record full
 @kindex record btrace
+@kindex record btrace bts
+@kindex record bts
 @kindex rec
 @kindex rec full
 @kindex rec btrace
+@kindex rec btrace bts
+@kindex rec bts
 @item record @var{method}
 This command starts the process record and replay target.  The
 recording method can be specified as parameter.  Without a parameter
@@ -6387,13 +6391,25 @@ Full record/replay recording using @value{GDBN}'s software record and
 replay implementation.  This method allows replaying and reverse
 execution.
 
-@item btrace
+@item btrace @var{format}
 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 replay and
 reverse execution.
 
-This recording method may not be available on all processors.
+The recording format can be specified as parameter.  Without a parameter
+the command chooses the recording format.  The following recording
+formats are available:
+
+@table @code
+@item bts
+@cindex branch trace store
+Use the @dfn{Branch Trace Store} (@acronym{BTS}) recording format.  In
+this format, the processor stores a from/to record for each executed
+branch in the btrace ring buffer.
+@end table
+
+Not all recording formats may be available on all processors.
 @end table
 
 The process record and replay target can only debug a process that is
@@ -6571,9 +6587,9 @@ Maximum number of instructions that may be contained in the execution log.
 @end itemize
 
 @item btrace
-For the @code{btrace} recording method, it shows the number of
-instructions that have been recorded and the number of blocks of
-sequential control-flow that is formed by the recorded instructions.
+For the @code{btrace} recording method, it shows the recording format,
+the number of instructions that have been recorded and the number of blocks
+of sequential control-flow that is formed by the recorded instructions.
 @end table
 
 @kindex record delete
@@ -33066,7 +33082,8 @@ MS-Windows shared libraries (@pxref{Shared Libraries})
 @item
 Traceframe info (@pxref{Traceframe Info Format})
 @item
-Branch trace (@pxref{Branch Trace Format})
+Branch trace (@pxref{Branch Trace Format},
+@pxref{Branch Trace Configuration Format})
 @end itemize
 
 @item zlib
@@ -34051,6 +34068,7 @@ Show the current setting of the target wait timeout.
 * Thread List Format::
 * Traceframe Info Format::
 * Branch Trace Format::
+* Branch Trace Configuration Format::
 @end menu
 
 @node Overview
@@ -35723,6 +35741,11 @@ These are the currently defined stub features and their properties:
 @tab @samp{-}
 @tab Yes
 
+@item @samp{qXfer:btrace-conf:read}
+@tab No
+@tab @samp{-}
+@tab Yes
+
 @item @samp{qXfer:features:read}
 @tab No
 @tab @samp{-}
@@ -35907,6 +35930,10 @@ The remote stub understands the @samp{qXfer:auxv:read} packet
 The remote stub understands the @samp{qXfer:btrace:read}
 packet (@pxref{qXfer btrace read}).
 
+@item qXfer:btrace-conf:read
+The remote stub understands the @samp{qXfer:btrace-conf:read}
+packet (@pxref{qXfer btrace-conf read}).
+
 @item qXfer:features:read
 The remote stub understands the @samp{qXfer:features:read} packet
 (@pxref{qXfer target description read}).
@@ -36201,6 +36228,15 @@ If the trace buffer overflowed, returns an error indicating the overflow.
 This packet is not probed by default; the remote stub must request it
 by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
 
+@item qXfer:btrace-conf:read::@var{offset},@var{length}
+@anchor{qXfer btrace-conf read}
+
+Return a description of the current branch trace configuration.
+@xref{Branch Trace Configuration Format}.
+
+This packet is not probed by default; the remote stub must request it
+by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
+
 @item qXfer:features:read:@var{annex}:@var{offset},@var{length}
 @anchor{qXfer target description read}
 Access the @dfn{target description}.  @xref{Target Descriptions}.  The
@@ -39005,6 +39041,29 @@ The formal DTD for the branch trace format is given below:
                        end    CDATA   #REQUIRED>
 @end smallexample
 
+@node Branch Trace Configuration Format
+@section Branch Trace Configuration Format
+@cindex branch trace configuration format
+
+For each inferior thread, @value{GDBN} can obtain the branch trace
+configuration using the @samp{qXfer:btrace-conf:read}
+(@pxref{qXfer btrace-conf read}) packet.
+
+The configuration describes the branch trace format and configuration
+settings for that format.
+
+@value{GDBN} must be linked with the Expat library to support XML
+branch trace configuration discovery.  @xref{Expat}.
+
+The formal DTD for the branch trace configuration format is given below:
+
+@smallexample
+<!ELEMENT btrace-conf	(bts?)>
+<!ATTLIST btrace-conf	version	CDATA	#FIXED "1.0">
+
+<!ELEMENT bts	EMPTY>
+@end smallexample
+
 @include agentexpr.texi
 
 @node Target Descriptions