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.

gdb/common/btrace-common.h

@@ -58,7 +58,10 @@ enum btrace_format
 
   /* Branch trace is in Branch Trace Store (BTS) format.
      Actually, the format is a sequence of blocks derived from BTS.  */
-  BTRACE_FORMAT_BTS
+  BTRACE_FORMAT_BTS,
+
+  /* Branch trace is in Intel(R) Processor Trace format.  */
+  BTRACE_FORMAT_PT
 };
 
 /* An enumeration of cpu vendors.  */
@@ -97,6 +100,14 @@ struct btrace_config_bts
   unsigned int size;
 };
 
+/* An Intel(R) Processor Trace configuration.  */
+
+struct btrace_config_pt
+{
+  /* The size of the branch trace buffer in bytes.  */
+  unsigned int size;
+};
+
 /* A branch tracing configuration.
 
    This describes the requested configuration as well as the actually
@@ -111,6 +122,9 @@ struct btrace_config
 
   /* The BTS format configuration.  */
   struct btrace_config_bts bts;
+
+  /* The Intel(R) Processor Trace format configuration.  */
+  struct btrace_config_pt pt;
 };
 
 /* Branch trace in BTS format.  */
@@ -121,6 +135,26 @@ struct btrace_data_bts
   VEC (btrace_block_s) *blocks;
 };
 
+/* Configuration information to go with the trace data.  */
+struct btrace_data_pt_config
+{
+  /* The processor on which the trace has been collected.  */
+  struct btrace_cpu cpu;
+};
+
+/* Branch trace in Intel(R) Processor Trace format.  */
+struct btrace_data_pt
+{
+  /* Some configuration information to go with the data.  */
+  struct btrace_data_pt_config config;
+
+  /* The trace data.  */
+  gdb_byte *data;
+
+  /* The size of DATA in bytes.  */
+  unsigned long size;
+};
+
 /* The branch trace data.  */
 struct btrace_data
 {
@@ -130,6 +164,9 @@ struct btrace_data
   {
     /* Format == BTRACE_FORMAT_BTS.  */
     struct btrace_data_bts bts;
+
+    /* Format == BTRACE_FORMAT_PT.  */
+    struct btrace_data_pt pt;
   } variant;
 };