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.

1 files changed, 106 insertions, 34 deletions

diff --git a/gdb/nat/linux-btrace.c b/gdb/nat/linux-btrace.c
index 5b22661..e827e92 100644
--- a/gdb/nat/linux-btrace.c
+++ b/gdb/nat/linux-btrace.c
@@ -90,8 +90,8 @@ perf_event_is_kernel_addr (const struct btrace_target_info *tinfo,
 /* Check whether a perf event record should be skipped.  */
 
 static inline int
-perf_event_skip_record (const struct btrace_target_info *tinfo,
-			const struct perf_event_bts *bts)
+perf_event_skip_bts_record (const struct btrace_target_info *tinfo,
+			    const struct perf_event_bts *bts)
 {
   /* The hardware may report branches from kernel into user space.  Branches
      from user into kernel space will be suppressed.  We filter the former to
@@ -194,7 +194,7 @@ perf_event_read_bts (struct btrace_target_info* tinfo, const uint8_t *begin,
 	  break;
 	}
 
-      if (perf_event_skip_record (tinfo, &psample->bts))
+      if (perf_event_skip_bts_record (tinfo, &psample->bts))
 	continue;
 
       /* We found a valid sample, so we can complete the current block.  */
@@ -395,39 +395,42 @@ linux_supports_btrace (struct target_ops *ops, enum btrace_format format)
   internal_error (__FILE__, __LINE__, _("Unknown branch trace format"));
 }
 
-/* See linux-btrace.h.  */
+/* Enable branch tracing in BTS format.  */
 
-struct btrace_target_info *
-linux_enable_btrace (ptid_t ptid)
+static struct btrace_target_info *
+linux_enable_bts (ptid_t ptid, const struct btrace_config *conf)
 {
   struct perf_event_mmap_page *header;
   struct btrace_target_info *tinfo;
+  struct btrace_tinfo_bts *bts;
   int pid, pg;
 
   tinfo = xzalloc (sizeof (*tinfo));
   tinfo->ptid = ptid;
+  tinfo->ptr_bits = 0;
 
-  tinfo->attr.size = sizeof (tinfo->attr);
-  tinfo->attr.type = PERF_TYPE_HARDWARE;
-  tinfo->attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS;
-  tinfo->attr.sample_period = 1;
+  tinfo->conf.format = BTRACE_FORMAT_BTS;
+  bts = &tinfo->variant.bts;
 
-  /* We sample from and to address.  */
-  tinfo->attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR;
+  bts->attr.size = sizeof (bts->attr);
+  bts->attr.type = PERF_TYPE_HARDWARE;
+  bts->attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS;
+  bts->attr.sample_period = 1;
 
-  tinfo->attr.exclude_kernel = 1;
-  tinfo->attr.exclude_hv = 1;
-  tinfo->attr.exclude_idle = 1;
+  /* We sample from and to address.  */
+  bts->attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR;
 
-  tinfo->ptr_bits = 0;
+  bts->attr.exclude_kernel = 1;
+  bts->attr.exclude_hv = 1;
+  bts->attr.exclude_idle = 1;
 
   pid = ptid_get_lwp (ptid);
   if (pid == 0)
     pid = ptid_get_pid (ptid);
 
   errno = 0;
-  tinfo->file = syscall (SYS_perf_event_open, &tinfo->attr, pid, -1, -1, 0);
-  if (tinfo->file < 0)
+  bts->file = syscall (SYS_perf_event_open, &bts->attr, pid, -1, -1, 0);
+  if (bts->file < 0)
     goto err;
 
   /* We try to allocate as much buffer as we can get.
@@ -437,7 +440,7 @@ linux_enable_btrace (ptid_t ptid)
     {
       /* The number of pages we request needs to be a power of two.  */
       header = mmap (NULL, ((1 << pg) + 1) * PAGE_SIZE, PROT_READ, MAP_SHARED,
-		     tinfo->file, 0);
+		     bts->file, 0);
       if (header != MAP_FAILED)
 	break;
     }
@@ -445,17 +448,17 @@ linux_enable_btrace (ptid_t ptid)
   if (header == MAP_FAILED)
     goto err_file;
 
-  tinfo->header = header;
-  tinfo->bts.mem = ((const uint8_t *) header) + PAGE_SIZE;
-  tinfo->bts.size = (1 << pg) * PAGE_SIZE;
-  tinfo->bts.data_head = &header->data_head;
-  tinfo->bts.last_head = 0;
+  bts->header = header;
+  bts->bts.mem = ((const uint8_t *) header) + PAGE_SIZE;
+  bts->bts.size = (1 << pg) * PAGE_SIZE;
+  bts->bts.data_head = &header->data_head;
+  bts->bts.last_head = 0;
 
   return tinfo;
 
  err_file:
   /* We were not able to allocate any buffer.  */
-  close (tinfo->file);
+  close (bts->file);
 
  err:
   xfree (tinfo);
@@ -464,16 +467,60 @@ linux_enable_btrace (ptid_t ptid)
 
 /* See linux-btrace.h.  */
 
-enum btrace_error
-linux_disable_btrace (struct btrace_target_info *tinfo)
+struct btrace_target_info *
+linux_enable_btrace (ptid_t ptid, const struct btrace_config *conf)
+{
+  struct btrace_target_info *tinfo;
+
+  tinfo = NULL;
+  switch (conf->format)
+    {
+    case BTRACE_FORMAT_NONE:
+      break;
+
+    case BTRACE_FORMAT_BTS:
+      tinfo = linux_enable_bts (ptid, conf);
+      break;
+    }
+
+  return tinfo;
+}
+
+/* Disable BTS tracing.  */
+
+static enum btrace_error
+linux_disable_bts (struct btrace_tinfo_bts *tinfo)
 {
   munmap((void *) tinfo->header, tinfo->bts.size + PAGE_SIZE);
   close (tinfo->file);
-  xfree (tinfo);
 
   return BTRACE_ERR_NONE;
 }
 
+/* See linux-btrace.h.  */
+
+enum btrace_error
+linux_disable_btrace (struct btrace_target_info *tinfo)
+{
+  enum btrace_error errcode;
+
+  errcode = BTRACE_ERR_NOT_SUPPORTED;
+  switch (tinfo->conf.format)
+    {
+    case BTRACE_FORMAT_NONE:
+      break;
+
+    case BTRACE_FORMAT_BTS:
+      errcode = linux_disable_bts (&tinfo->variant.bts);
+      break;
+    }
+
+  if (errcode == BTRACE_ERR_NONE)
+    xfree (tinfo);
+
+  return errcode;
+}
+
 /* Read branch trace data in BTS format for the thread given by TINFO into
    BTRACE using the TYPE reading method.  */
 
@@ -487,7 +534,7 @@ linux_read_bts (struct btrace_data_bts *btrace,
   unsigned long long data_head, data_tail, buffer_size, size;
   unsigned int retries = 5;
 
-  pevent = &tinfo->bts;
+  pevent = &tinfo->variant.bts.bts;
 
   /* For delta reads, we return at least the partial last block containing
      the current PC.  */
@@ -570,11 +617,28 @@ linux_read_btrace (struct btrace_data *btrace,
 		   struct btrace_target_info *tinfo,
 		   enum btrace_read_type type)
 {
-  /* We read btrace in BTS format.  */
-  btrace->format = BTRACE_FORMAT_BTS;
-  btrace->variant.bts.blocks = NULL;
+  switch (tinfo->conf.format)
+    {
+    case BTRACE_FORMAT_NONE:
+      return BTRACE_ERR_NOT_SUPPORTED;
+
+    case BTRACE_FORMAT_BTS:
+      /* We read btrace in BTS format.  */
+      btrace->format = BTRACE_FORMAT_BTS;
+      btrace->variant.bts.blocks = NULL;
+
+      return linux_read_bts (&btrace->variant.bts, tinfo, type);
+    }
+
+  internal_error (__FILE__, __LINE__, _("Unkown branch trace format."));
+}
+
+/* See linux-btrace.h.  */
 
-  return linux_read_bts (&btrace->variant.bts, tinfo, type);
+const struct btrace_config *
+linux_btrace_conf (const struct btrace_target_info *tinfo)
+{
+  return &tinfo->conf;
 }
 
 #else /* !HAVE_LINUX_PERF_EVENT_H */
@@ -590,7 +654,7 @@ linux_supports_btrace (struct target_ops *ops, enum btrace_format format)
 /* See linux-btrace.h.  */
 
 struct btrace_target_info *
-linux_enable_btrace (ptid_t ptid)
+linux_enable_btrace (ptid_t ptid, const struct btrace_config *conf)
 {
   return NULL;
 }
@@ -613,4 +677,12 @@ linux_read_btrace (struct btrace_data *btrace,
   return BTRACE_ERR_NOT_SUPPORTED;
 }
 
+/* See linux-btrace.h.  */
+
+const struct btrace_config *
+linux_btrace_conf (const struct btrace_target_info *tinfo)
+{
+  return NULL;
+}
+
 #endif /* !HAVE_LINUX_PERF_EVENT_H */