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/gdbserver/server.c

@@ -408,6 +408,23 @@ handle_btrace_enable_bts (struct thread_info *thread)
   return NULL;
 }
 
+/* Handle btrace enabling in Intel(R) Processor Trace format.  */
+
+static const char *
+handle_btrace_enable_pt (struct thread_info *thread)
+{
+  if (thread->btrace != NULL)
+    return "E.Btrace already enabled.";
+
+  current_btrace_conf.format = BTRACE_FORMAT_PT;
+  thread->btrace = target_enable_btrace (thread->entry.id,
+					 &current_btrace_conf);
+  if (thread->btrace == NULL)
+    return "E.Could not enable btrace.";
+
+  return NULL;
+}
+
 /* Handle btrace disabling.  */
 
 static const char *
@@ -456,10 +473,12 @@ handle_btrace_general_set (char *own_buf)
 
   if (strcmp (op, "bts") == 0)
     err = handle_btrace_enable_bts (thread);
+  else if (strcmp (op, "pt") == 0)
+    err = handle_btrace_enable_pt (thread);
   else if (strcmp (op, "off") == 0)
     err = handle_btrace_disable (thread);
   else
-    err = "E.Bad Qbtrace operation. Use bts or off.";
+    err = "E.Bad Qbtrace operation. Use bts, pt, or off.";
 
   if (err != 0)
     strcpy (own_buf, err);
@@ -511,6 +530,21 @@ handle_btrace_conf_general_set (char *own_buf)
 
       current_btrace_conf.bts.size = (unsigned int) size;
     }
+  else if (strncmp (op, "pt:size=", strlen ("pt:size=")) == 0)
+    {
+      unsigned long size;
+      char *endp = NULL;
+
+      errno = 0;
+      size = strtoul (op + strlen ("pt:size="), &endp, 16);
+      if (endp == NULL || *endp != 0 || errno != 0 || size > UINT_MAX)
+	{
+	  strcpy (own_buf, "E.Bad size value.");
+	  return -1;
+	}
+
+      current_btrace_conf.pt.size = (unsigned int) size;
+    }
   else
     {
       strcpy (own_buf, "E.Bad Qbtrace configuration option.");
@@ -1871,12 +1905,25 @@ crc32 (CORE_ADDR base, int len, unsigned int crc)
 static void
 supported_btrace_packets (char *buf)
 {
+  int btrace_supported = 0;
+
   if (target_supports_btrace (BTRACE_FORMAT_BTS))
     {
       strcat (buf, ";Qbtrace:bts+");
       strcat (buf, ";Qbtrace-conf:bts:size+");
+
+      btrace_supported = 1;
     }
-  else
+
+  if (target_supports_btrace (BTRACE_FORMAT_PT))
+    {
+      strcat (buf, ";Qbtrace:pt+");
+      strcat (buf, ";Qbtrace-conf:pt:size+");
+
+      btrace_supported = 1;
+    }
+
+  if (!btrace_supported)
     return;
 
   strcat (buf, ";Qbtrace:off+");