Add the gdb remote target operations for branch tracing.

We define the following packets:

  Qbtrace:bts         enable branch tracing for the current thread
                      returns "OK" or "Enn"

  Qbtrace:off         disable branch tracing for the current thread
                      returns "OK" or "Enn"

  qXfer:btrace:read   read the full branch trace data for the current thread

gdb/
	* target.h (enum target_object): Add TARGET_OBJECT_BTRACE.
	* remote.c: Include btrace.h.
	(struct btrace_target_info): New struct.
	(remote_supports_btrace): New function.
	(send_Qbtrace): New function.
	(remote_enable_btrace): New function.
	(remote_disable_btrace): New function.
	(remote_teardown_btrace): New function.
	(remote_read_btrace): New function.
	(init_remote_ops): Add btrace ops.
	(enum <unnamed>): Add btrace packets.
	(struct protocol_feature remote_protocol_features[]): Add btrace packets.
	(_initialize_remote): Add packet configuration for branch tracing.

gdbserver/
	* target.h (struct target_ops): Add btrace ops.
	(target_supports_btrace): New macro.
	(target_enable_btrace): New macro.
	(target_disable_btrace): New macro.
	(target_read_btrace): New macro.
	* gdbthread.h (struct thread_info): Add btrace field.
	* server.c: Include btrace-common.h.
	(handle_btrace_general_set): New function.
	(handle_btrace_enable): New function.
	(handle_btrace_disable): New function.
	(handle_general_set): Call handle_btrace_general_set.
	(handle_qxfer_btrace): New function.
	(struct qxfer qxfer_packets[]): Add btrace entry.
	* inferiors.c (remove_thread): Disable btrace.
	* linux-low: Include linux-btrace.h.
	(linux_low_enable_btrace): New function.
	(linux_low_read_btrace): New function.
	(linux_target_ops): Add btrace ops.
	* configure.srv (i[34567]86-*-linux*): Add linux-btrace.o.
	Add srv_linux_btrace=yes.
	(x86_64-*-linux*): Add linux-btrace.o.
	Add srv_linux_btrace=yes.
	* configure.ac: Define HAVE_LINUX_BTRACE.
	* config.in: Regenerated.
	* configure: Regenerated.

1 files changed, 161 insertions, 0 deletions

diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index 9592c69..6bb36d8 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -28,6 +28,7 @@
 #include <signal.h>
 #endif
 #include "gdb_wait.h"
+#include "btrace-common.h"
 
 /* The thread set with an `Hc' packet.  `Hc' is deprecated in favor of
    `vCont'.  Note the multi-process extensions made `vCont' a
@@ -396,6 +397,88 @@ write_qxfer_response (char *buf, const void *data, int len, int is_more)
 			       PBUFSIZ - 2) + 1;
 }
 
+/* Handle btrace enabling.  */
+
+static const char *
+handle_btrace_enable (struct thread_info *thread)
+{
+  if (thread->btrace != NULL)
+    return "E.Btrace already enabled.";
+
+  thread->btrace = target_enable_btrace (thread->entry.id);
+  if (thread->btrace == NULL)
+    return "E.Could not enable btrace.";
+
+  return NULL;
+}
+
+/* Handle btrace disabling.  */
+
+static const char *
+handle_btrace_disable (struct thread_info *thread)
+{
+
+  if (thread->btrace == NULL)
+    return "E.Branch tracing not enabled.";
+
+  if (target_disable_btrace (thread->btrace) != 0)
+    return "E.Could not disable branch tracing.";
+
+  thread->btrace = NULL;
+  return NULL;
+}
+
+/* Handle the "Qbtrace" packet.  */
+
+static int
+handle_btrace_general_set (char *own_buf)
+{
+  struct thread_info *thread;
+  const char *err;
+  char *op;
+
+  if (strncmp ("Qbtrace:", own_buf, strlen ("Qbtrace:")) != 0)
+    return 0;
+
+  op = own_buf + strlen ("Qbtrace:");
+
+  if (!target_supports_btrace ())
+    {
+      strcpy (own_buf, "E.Target does not support branch tracing.");
+      return -1;
+    }
+
+  if (ptid_equal (general_thread, null_ptid)
+      || ptid_equal (general_thread, minus_one_ptid))
+    {
+      strcpy (own_buf, "E.Must select a single thread.");
+      return -1;
+    }
+
+  thread = find_thread_ptid (general_thread);
+  if (thread == NULL)
+    {
+      strcpy (own_buf, "E.No such thread.");
+      return -1;
+    }
+
+  err = NULL;
+
+  if (strcmp (op, "bts") == 0)
+    err = handle_btrace_enable (thread);
+  else if (strcmp (op, "off") == 0)
+    err = handle_btrace_disable (thread);
+  else
+    err = "E.Bad Qbtrace operation. Use bts or off.";
+
+  if (err != 0)
+    strcpy (own_buf, err);
+  else
+    write_ok (own_buf);
+
+  return 1;
+}
+
 /* Handle all of the extended 'Q' packets.  */
 
 static void
@@ -552,6 +635,9 @@ handle_general_set (char *own_buf)
       return;
     }
 
+  if (handle_btrace_general_set (own_buf))
+    return;
+
   /* Otherwise we didn't know what packet it was.  Say we didn't
      understand it.  */
   own_buf[0] = 0;
@@ -1251,9 +1337,77 @@ handle_qxfer_fdpic (const char *annex, gdb_byte *readbuf,
   return (*the_target->read_loadmap) (annex, offset, readbuf, len);
 }
 
+/* Handle qXfer:btrace:read.  */
+
+static int
+handle_qxfer_btrace (const char *annex,
+		     gdb_byte *readbuf, const gdb_byte *writebuf,
+		     ULONGEST offset, LONGEST len)
+{
+  static struct buffer cache;
+  struct thread_info *thread;
+  int type;
+
+  if (the_target->read_btrace == NULL || writebuf != NULL)
+    return -2;
+
+  if (!target_running ())
+    return -1;
+
+  if (ptid_equal (general_thread, null_ptid)
+      || ptid_equal (general_thread, minus_one_ptid))
+    {
+      strcpy (own_buf, "E.Must select a single thread.");
+      return -3;
+    }
+
+  thread = find_thread_ptid (general_thread);
+  if (thread == NULL)
+    {
+      strcpy (own_buf, "E.No such thread.");
+      return -3;
+    }
+
+  if (thread->btrace == NULL)
+    {
+      strcpy (own_buf, "E.Btrace not enabled.");
+      return -3;
+    }
+
+  if (strcmp (annex, "all") == 0)
+    type = btrace_read_all;
+  else if (strcmp (annex, "new") == 0)
+    type = btrace_read_new;
+  else
+    {
+      strcpy (own_buf, "E.Bad annex.");
+      return -3;
+    }
+
+  if (offset == 0)
+    {
+      buffer_free (&cache);
+
+      target_read_btrace (thread->btrace, &cache, type);
+    }
+  else if (offset > cache.used_size)
+    {
+      buffer_free (&cache);
+      return -3;
+    }
+
+  if (len > cache.used_size - offset)
+    len = cache.used_size - offset;
+
+  memcpy (readbuf, cache.buffer + offset, len);
+
+  return len;
+}
+
 static const struct qxfer qxfer_packets[] =
   {
     { "auxv", handle_qxfer_auxv },
+    { "btrace", handle_qxfer_btrace },
     { "fdpic", handle_qxfer_fdpic},
     { "features", handle_qxfer_features },
     { "libraries", handle_qxfer_libraries },
@@ -1656,6 +1810,13 @@ handle_query (char *own_buf, int packet_len, int *new_packet_len_p)
       if (target_supports_agent ())
 	strcat (own_buf, ";QAgent+");
 
+      if (target_supports_btrace ())
+	{
+	  strcat (own_buf, ";Qbtrace:bts+");
+	  strcat (own_buf, ";Qbtrace:off+");
+	  strcat (own_buf, ";qXfer:btrace:read+");
+	}
+
       return;
     }