range stepping: gdbserver (x86 GNU/Linux)

This patch adds support for range stepping to GDBserver, teaching it
about vCont;r.

It'd be easy to enable this for all hardware single-step targets
without needing the linux_target_ops hook, however, at least PPC needs
special care, due to the fact that PPC atomic sequences can't be
hardware single-stepped through, a thing which GDBserver doesn't know
about.  So this leaves the support limited to x86/x86_64.

gdb/
2013-05-23  Pedro Alves  <palves@redhat.com>

	* NEWS: Mention GDBserver range stepping support.

gdb/gdbserver/
2013-05-23  Yao Qi  <yao@codesourcery.com>
	    Pedro Alves  <palves@redhat.com>

	* linux-low.c (lwp_in_step_range): New function.
	(linux_wait_1): If the thread was range stepping and stopped
	outside the stepping range, report the stop to GDB.  Otherwise,
	continue stepping.  Add range stepping debug output.
	(linux_set_resume_request): Copy the step range from the resume
	request to the lwp.
	(linux_supports_range_stepping): New.
	(linux_target_ops) <supports_range_stepping>: Set to
	linux_supports_range_stepping.
	* linux-low.h (struct linux_target_ops)
	<supports_range_stepping>: New field.
	(struct lwp_info) <step_range_start, step_range_end>: New fields.
	* linux-x86-low.c (x86_supports_range_stepping): New.
	(the_low_target) <supports_range_stepping>: Set to
	x86_supports_range_stepping.
	* server.c (handle_v_cont): Handle 'r' action.
	(handle_v_requests): Append ";r" if the target supports range
	stepping.
	* target.h (struct thread_resume) <step_range_start,
	step_range_end>: New fields.
	(struct target_ops) <supports_range_stepping>:
	New field.
	(target_supports_range_stepping): New macro.

1 files changed, 23 insertions, 1 deletions

diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index 6bb36d87c37..1083aa9e56e 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -2042,8 +2042,12 @@ handle_v_cont (char *own_buf)
     {
       p++;
 
+      memset (&resume_info[i], 0, sizeof resume_info[i]);
+
       if (p[0] == 's' || p[0] == 'S')
 	resume_info[i].kind = resume_step;
+      else if (p[0] == 'r')
+	resume_info[i].kind = resume_step;
       else if (p[0] == 'c' || p[0] == 'C')
 	resume_info[i].kind = resume_continue;
       else if (p[0] == 't')
@@ -2063,9 +2067,22 @@ handle_v_cont (char *own_buf)
 	    goto err;
 	  resume_info[i].sig = gdb_signal_to_host (sig);
 	}
+      else if (p[0] == 'r')
+	{
+	  char *p1;
+
+	  p = p + 1;
+	  p1 = strchr (p, ',');
+	  decode_address (&resume_info[i].step_range_start, p, p1 - p);
+
+	  p = p1 + 1;
+	  p1 = strchr (p, ':');
+	  decode_address (&resume_info[i].step_range_end, p, p1 - p);
+
+	  p = p1;
+	}
       else
 	{
-	  resume_info[i].sig = 0;
 	  p = p + 1;
 	}
 
@@ -2311,6 +2328,11 @@ handle_v_requests (char *own_buf, int packet_len, int *new_packet_len)
       if (strncmp (own_buf, "vCont?", 6) == 0)
 	{
 	  strcpy (own_buf, "vCont;c;C;s;S;t");
+	  if (target_supports_range_stepping ())
+	    {
+	      own_buf = own_buf + strlen (own_buf);
+	      strcpy (own_buf, ";r");
+	    }
 	  return;
 	}
     }