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.

3 files changed, 137 insertions, 9 deletions

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index eea8be5..081d305 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,13 @@
+2015-07-02  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* 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".
+
 2015-06-29  Pierre Langlois  <pierre.langlois@arm.com>
 
 	* linux-aarch64-low.c (aarch64_supports_z_point_type): Enable for
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index 3774d170..7bb9f7f 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -21,6 +21,7 @@
 #include "nat/linux-osdata.h"
 #include "agent.h"
 #include "tdesc.h"
+#include "rsp-low.h"
 
 #include "nat/linux-nat.h"
 #include "nat/linux-waitpid.h"
@@ -6461,6 +6462,55 @@ linux_low_disable_btrace (struct btrace_target_info *tinfo)
   return (err == BTRACE_ERR_NONE ? 0 : -1);
 }
 
+/* Encode an Intel(R) Processor Trace configuration.  */
+
+static void
+linux_low_encode_pt_config (struct buffer *buffer,
+			    const struct btrace_data_pt_config *config)
+{
+  buffer_grow_str (buffer, "<pt-config>\n");
+
+  switch (config->cpu.vendor)
+    {
+    case CV_INTEL:
+      buffer_xml_printf (buffer, "<cpu vendor=\"GenuineIntel\" family=\"%u\" "
+			 "model=\"%u\" stepping=\"%u\"/>\n",
+			 config->cpu.family, config->cpu.model,
+			 config->cpu.stepping);
+      break;
+
+    default:
+      break;
+    }
+
+  buffer_grow_str (buffer, "</pt-config>\n");
+}
+
+/* Encode a raw buffer.  */
+
+static void
+linux_low_encode_raw (struct buffer *buffer, const gdb_byte *data,
+		      unsigned int size)
+{
+  if (size == 0)
+    return;
+
+  /* We use hex encoding - see common/rsp-low.h.  */
+  buffer_grow_str (buffer, "<raw>\n");
+
+  while (size-- > 0)
+    {
+      char elem[2];
+
+      elem[0] = tohex ((*data >> 4) & 0xf);
+      elem[1] = tohex (*data++ & 0xf);
+
+      buffer_grow (buffer, elem, 2);
+    }
+
+  buffer_grow_str (buffer, "</raw>\n");
+}
+
 /* See to_read_btrace target method.  */
 
 static int
@@ -6482,15 +6532,14 @@ linux_low_read_btrace (struct btrace_target_info *tinfo, struct buffer *buffer,
       else
 	buffer_grow_str0 (buffer, "E.Generic Error.");
 
-      btrace_data_fini (&btrace);
-      return -1;
+      goto err;
     }
 
   switch (btrace.format)
     {
     case BTRACE_FORMAT_NONE:
       buffer_grow_str0 (buffer, "E.No Trace.");
-      break;
+      goto err;
 
     case BTRACE_FORMAT_BTS:
       buffer_grow_str (buffer, "<!DOCTYPE btrace SYSTEM \"btrace.dtd\">\n");
@@ -6505,15 +6554,31 @@ linux_low_read_btrace (struct btrace_target_info *tinfo, struct buffer *buffer,
       buffer_grow_str0 (buffer, "</btrace>\n");
       break;
 
-    default:
-      buffer_grow_str0 (buffer, "E.Unknown Trace Format.");
+    case BTRACE_FORMAT_PT:
+      buffer_grow_str (buffer, "<!DOCTYPE btrace SYSTEM \"btrace.dtd\">\n");
+      buffer_grow_str (buffer, "<btrace version=\"1.0\">\n");
+      buffer_grow_str (buffer, "<pt>\n");
+
+      linux_low_encode_pt_config (buffer, &btrace.variant.pt.config);
 
-      btrace_data_fini (&btrace);
-      return -1;
+      linux_low_encode_raw (buffer, btrace.variant.pt.data,
+			    btrace.variant.pt.size);
+
+      buffer_grow_str (buffer, "</pt>\n");
+      buffer_grow_str0 (buffer, "</btrace>\n");
+      break;
+
+    default:
+      buffer_grow_str0 (buffer, "E.Unsupported Trace Format.");
+      goto err;
     }
 
   btrace_data_fini (&btrace);
   return 0;
+
+err:
+  btrace_data_fini (&btrace);
+  return -1;
 }
 
 /* See to_btrace_conf target method.  */
@@ -6540,6 +6605,12 @@ linux_low_btrace_conf (const struct btrace_target_info *tinfo,
 	  buffer_xml_printf (buffer, " size=\"0x%x\"", conf->bts.size);
 	  buffer_xml_printf (buffer, " />\n");
 	  break;
+
+	case BTRACE_FORMAT_PT:
+	  buffer_xml_printf (buffer, "<pt");
+	  buffer_xml_printf (buffer, " size=\"0x%x\"", conf->pt.size);
+	  buffer_xml_printf (buffer, "/>\n");
+	  break;
 	}
     }
 
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index c9effc2..7e388dd 100644
--- a/gdb/gdbserver/server.c
+++ b/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+");