btrace: support Intel(R) Processor Trace

Adds a new command "record btrace pt" to configure the kernel to use
Intel(R) Processor Trace instead of Branch Trace Strore.

The "record btrace" command chooses the tracing format automatically.

Intel(R) Processor Trace support requires Linux 4.1 and libipt.

gdb/
	* NEWS: Announce new commands "record btrace pt" and "record pt".
	Announce new options "set|show record btrace pt buffer-size".
	* btrace.c: Include "rsp-low.h".
	Include "inttypes.h".
	(btrace_add_pc): Add forward declaration.
	(pt_reclassify_insn, ftrace_add_pt, btrace_pt_readmem_callback)
	(pt_translate_cpu_vendor, btrace_finalize_ftrace_pt)
	(btrace_compute_ftrace_pt): New.
	(btrace_compute_ftrace): Support BTRACE_FORMAT_PT.
	(check_xml_btrace_version): Update version check.
	(parse_xml_raw, parse_xml_btrace_pt_config_cpu)
	(parse_xml_btrace_pt_raw, parse_xml_btrace_pt)
	(btrace_pt_config_cpu_attributes, btrace_pt_config_children)
	(btrace_pt_children): New.
	(btrace_children): Add support for "pt".
	(parse_xml_btrace_conf_pt, btrace_conf_pt_attributes): New.
	(btrace_conf_children): Add support for "pt".
	* btrace.h: Include "intel-pt.h".
	(btrace_pt_error): New.
	* common/btrace-common.c (btrace_format_string, btrace_data_fini)
	(btrace_data_empty): Support BTRACE_FORMAT_PT.
	* common/btrace-common.h (btrace_format): Add BTRACE_FORMAT_PT.
	(struct btrace_config_pt): New.
	(struct btrace_config)<pt>: New.
	(struct btrace_data_pt_config, struct btrace_data_pt): New.
	(struct btrace_data)<pt>: New.
	* features/btrace-conf.dtd (btrace-conf)<pt>: New.
	(pt): New.
	* features/btrace.dtd (btrace)<pt>: New.
	(pt, pt-config, cpu): New.
	* nat/linux-btrace.c (perf_event_read, perf_event_read_all)
	(perf_event_pt_event_type, kernel_supports_pt)
	(linux_supports_pt): New.
	(linux_supports_btrace): Support BTRACE_FORMAT_PT.
	(linux_enable_bts): Free tinfo on error.
	(linux_enable_pt): New.
	(linux_enable_btrace): Support BTRACE_FORMAT_PT.
	(linux_disable_pt): New.
	(linux_disable_btrace): Support BTRACE_FORMAT_PT.
	(linux_fill_btrace_pt_config, linux_read_pt): New.
	(linux_read_btrace): Support BTRACE_FORMAT_PT.
	* nat/linux-btrace.h (struct btrace_tinfo_pt): New.
	(struct btrace_target_info)<pt>: New.
	* record-btrace.c (set_record_btrace_pt_cmdlist)
	(show_record_btrace_pt_cmdlist): New.
	(record_btrace_print_pt_conf): New.
	(record_btrace_print_conf): Support BTRACE_FORMAT_PT.
	(btrace_ui_out_decode_error): Support BTRACE_FORMAT_PT.
	(cmd_record_btrace_pt_start): New.
	(cmd_record_btrace_start): Support BTRACE_FORMAT_PT.
	(cmd_set_record_btrace_pt, cmd_show_record_btrace_pt): New.
	(_initialize_record_btrace): Add new commands.
	* remote.c (PACKET_Qbtrace_pt, PACKET_Qbtrace_conf_pt_size): New.
	(remote_protocol_features): Add "Qbtrace:pt".
	Add "Qbtrace-conf:pt:size".
	(remote_supports_btrace): Support BTRACE_FORMAT_PT.
	(btrace_sync_conf): Support PACKET_Qbtrace_conf_pt_size.
	(remote_enable_btrace): Support BTRACE_FORMAT_PT.
	(_initialize_remote): Add new commands.

gdbserver/
	* linux-low.c: Include "rsp-low.h"
	(linux_low_encode_pt_config, linux_low_encode_raw): New.
	(linux_low_read_btrace): Support BTRACE_FORMAT_PT.
	(linux_low_btrace_conf): Support BTRACE_FORMAT_PT.
	(handle_btrace_enable_pt): New.
	(handle_btrace_general_set): Support "pt".
	(handle_btrace_conf_general_set): Support "pt:size".

doc/
	* gdb.texinfo (Process Record and Replay): Spell out that variables
	and registers are not available during btrace replay.
	Describe the new "record btrace pt" command.
	Describe the new "set|show record btrace pt buffer-size" options.
	(General Query Packets): Describe the new Qbtrace:pt and
	Qbtrace-conf:pt:size packets.
	Expand "bts" to "Branch Trace Store".
	Update the branch trace DTD.

2 files changed, 126 insertions, 8 deletions

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index e0beb7f..6d898f3 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,14 @@
+2015-07-02  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* gdb.texinfo (Process Record and Replay): Spell out that variables
+	and registers are not available during btrace replay.
+	Describe the new "record btrace pt" command.
+	Describe the new "set|show record btrace pt buffer-size" options.
+	(General Query Packets): Describe the new Qbtrace:pt and
+	Qbtrace-conf:pt:size packets.
+	Expand "bts" to "Branch Trace Store".
+	Update the branch trace DTD.
+
 2015-06-26  Patrick Palka  <patrick@parcs.ath.cx>
 
 	* gdb.texinfo (Command History): Document the new option
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 20a9563..a19ee6d 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -6417,12 +6417,16 @@ For architecture environments that support process record and replay,
 @kindex record full
 @kindex record btrace
 @kindex record btrace bts
+@kindex record btrace pt
 @kindex record bts
+@kindex record pt
 @kindex rec
 @kindex rec full
 @kindex rec btrace
 @kindex rec btrace bts
+@kindex rec btrace pt
 @kindex rec bts
+@kindex rec pt
 @item record @var{method}
 This command starts the process record and replay target.  The
 recording method can be specified as parameter.  Without a parameter
@@ -6438,8 +6442,9 @@ execution.
 @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.
+be overwritten when the buffer is full.  It allows limited reverse
+execution.  Variables and registers are not available during reverse
+execution.
 
 The recording format can be specified as parameter.  Without a parameter
 the command chooses the recording format.  The following recording
@@ -6451,6 +6456,21 @@ formats are available:
 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.
+
+@item pt
+@cindex Intel(R) Processor Trace
+Use the @dfn{Intel(R) Processor Trace} recording format.  In this
+format, the processor stores the execution trace in a compressed form
+that is afterwards decoded by @value{GDBN}.
+
+The trace can be recorded with very low overhead.  The compressed
+trace format also allows small trace buffers to already contain a big
+number of instructions compared to @acronym{BTS}.
+
+Decoding the recorded execution trace, on the other hand, is more
+expensive than decoding @acronym{BTS} trace.  This is mostly due to the
+increased number of instructions to process.  You should increase the
+buffer-size with care.
 @end table
 
 Not all recording formats may be available on all processors.
@@ -6461,9 +6481,6 @@ already running.  Therefore, you need first to start the process with
 the @kbd{run} or @kbd{start} commands, and then start the recording
 with the @kbd{record @var{method}} command.
 
-Both @code{record @var{method}} and @code{rec @var{method}} are
-aliases of @code{target record-@var{method}}.
-
 @cindex displaced stepping, and process record and replay
 Displaced stepping (@pxref{Maintenance Commands,, displaced stepping})
 will be automatically disabled when process record and replay target
@@ -6629,6 +6646,29 @@ also need longer to process the branch trace data before it can be used.
 Show the current setting of the requested ring buffer size for branch
 tracing in @acronym{BTS} format.
 
+@kindex set record btrace pt
+@item set record btrace pt buffer-size @var{size}
+@itemx set record btrace pt buffer-size unlimited
+Set the requested ring buffer size for branch tracing in Intel(R)
+Processor Trace format.  Default is 16KB.
+
+If @var{size} is a positive number, then @value{GDBN} will try to
+allocate a buffer of at least @var{size} bytes for each new thread
+that uses the btrace recording method and the Intel(R) Processor Trace
+format.  The actually obtained buffer size may differ from the
+requested @var{size}.  Use the @code{info record} command to see the
+actual buffer size for each thread.
+
+If @var{limit} is @code{unlimited} or zero, @value{GDBN} will try to
+allocate a buffer of 4MB.
+
+Bigger buffers mean longer traces.  On the other hand, @value{GDBN} will
+also need longer to process the branch trace data before it can be used.
+
+@item show record btrace pt buffer-size @var{size}
+Show the current setting of the requested ring buffer size for branch
+tracing in Intel(R) Processor Trace format.
+
 @kindex info record
 @item info record
 Show various statistics about the recording depending on the recording
@@ -6674,6 +6714,12 @@ For the @code{bts} recording format, it also shows:
 @item
 Size of the perf ring buffer.
 @end itemize
+
+For the @code{pt} recording format, it also shows:
+@itemize @bullet
+@item
+Size of the perf ring buffer.
+@end itemize
 @end table
 
 @kindex record delete
@@ -36294,11 +36340,21 @@ These are the currently defined stub features and their properties:
 @tab @samp{-}
 @tab Yes
 
+@item @samp{Qbtrace:pt}
+@tab Yes
+@tab @samp{-}
+@tab Yes
+
 @item @samp{Qbtrace-conf:bts:size}
 @tab Yes
 @tab @samp{-}
 @tab Yes
 
+@item @samp{Qbtrace-conf:pt:size}
+@tab Yes
+@tab @samp{-}
+@tab Yes
+
 @item @samp{QNonStop}
 @tab No
 @tab @samp{-}
@@ -36580,9 +36636,15 @@ The remote stub understands the @samp{Qbtrace:off} packet.
 @item Qbtrace:bts
 The remote stub understands the @samp{Qbtrace:bts} packet.
 
+@item Qbtrace:pt
+The remote stub understands the @samp{Qbtrace:pt} packet.
+
 @item Qbtrace-conf:bts:size
 The remote stub understands the @samp{Qbtrace-conf:bts:size} packet.
 
+@item Qbtrace-conf:pt:size
+The remote stub understands the @samp{Qbtrace-conf:pt:size} packet.
+
 @item swbreak
 The remote stub reports the @samp{swbreak} stop reason for memory
 breakpoints.
@@ -37027,7 +37089,18 @@ A badly formed request or an error was encountered.
 @end table
 
 @item Qbtrace:bts
-Enable branch tracing for the current thread using bts tracing.
+Enable branch tracing for the current thread using Branch Trace Store.
+
+Reply:
+@table @samp
+@item OK
+Branch tracing has been enabled.
+@item E.errtext
+A badly formed request or an error was encountered.
+@end table
+
+@item Qbtrace:pt
+Enable branch tracing for the current thread using Intel(R) Processor Trace.
 
 Reply:
 @table @samp
@@ -37060,6 +37133,18 @@ The ring buffer size has been set.
 A badly formed request or an error was encountered.
 @end table
 
+@item Qbtrace-conf:pt:size=@var{value}
+Set the requested ring buffer size for new threads that use the
+btrace recording method in pt format.
+
+Reply:
+@table @samp
+@item OK
+The ring buffer size has been set.
+@item E.errtext
+A badly formed request or an error was encountered.
+@end table
+
 @end table
 
 @node Architecture-Specific Protocol Details
@@ -39611,12 +39696,24 @@ and ending at @var{end}:
 The formal DTD for the branch trace format is given below:
 
 @smallexample
-<!ELEMENT btrace  (block)* >
+<!ELEMENT btrace  (block* | pt) >
 <!ATTLIST btrace  version CDATA   #FIXED "1.0">
 
 <!ELEMENT block        EMPTY>
 <!ATTLIST block        begin  CDATA   #REQUIRED
                        end    CDATA   #REQUIRED>
+
+<!ELEMENT pt (pt-config?, raw?)>
+
+<!ELEMENT pt-config (cpu?)>
+
+<!ELEMENT cpu EMPTY>
+<!ATTLIST cpu vendor   CDATA #REQUIRED
+              family   CDATA #REQUIRED
+              model    CDATA #REQUIRED
+              stepping CDATA #REQUIRED>
+
+<!ELEMENT raw (#PCDATA)>
 @end smallexample
 
 @node Branch Trace Configuration Format
@@ -39637,6 +39734,13 @@ This thread uses the @dfn{Branch Trace Store} (@acronym{BTS}) format.
 @item size
 The size of the @acronym{BTS} ring buffer in bytes.
 @end table
+@item pt
+This thread uses the @dfn{Intel(R) Processor Trace} (@acronym{Intel(R)
+PT}) format.
+@table @code
+@item size
+The size of the @acronym{Intel(R) PT} ring buffer in bytes.
+@end table
 @end table
 
 @value{GDBN} must be linked with the Expat library to support XML
@@ -39645,11 +39749,14 @@ branch trace configuration discovery.  @xref{Expat}.
 The formal DTD for the branch trace configuration format is given below:
 
 @smallexample
-<!ELEMENT btrace-conf	(bts?)>
+<!ELEMENT btrace-conf	(bts?, pt?)>
 <!ATTLIST btrace-conf	version	CDATA	#FIXED "1.0">
 
 <!ELEMENT bts	EMPTY>
 <!ATTLIST bts	size	CDATA	#IMPLIED>
+
+<!ELEMENT pt	EMPTY>
+<!ATTLIST pt	size	CDATA	#IMPLIED>
 @end smallexample
 
 @include agentexpr.texi