[SCM] archer-sergiodj-stap: implement longjmp probes this is still untested

[SCM] archer-sergiodj-stap: implement longjmp probes this is still untested

[tromey]

The branch, archer-sergiodj-stap has been updated
       via  8fed9947347921e703b14558a062699a1ba8b563 (commit)
      from  d909b1c3af91be2fe436ed45662a8301cbd6c86d (commit)

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- Log -----------------------------------------------------------------
commit 8fed9947347921e703b14558a062699a1ba8b563
Author: Tom Tromey <tromey@redhat.com>
Date:   Thu Mar 17 07:57:48 2011 -0600

    implement longjmp probes
    this is still untested

-----------------------------------------------------------------------

Summary of changes:
 gdb/breakpoint.c |   31 +++++++++++++++++++++++++++++--
 gdb/infrun.c     |   31 +++++++++++++------------------
 gdb/stap-probe.c |   25 +++++++++++++++++++++++++
 gdb/stap-probe.h |    6 ++++++
 4 files changed, 73 insertions(+), 20 deletions(-)

First 500 lines of diff:
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 353b051..2126875 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -2113,6 +2113,9 @@ struct breakpoint_objfile_data
   /* Minimal symbol(s) for "longjmp", "siglongjmp", etc. (if any).  */
   struct minimal_symbol *longjmp_msym[NUM_LONGJMP_NAMES];
 
+  /* SystemTap probe point for longjmp (if any).  */
+  const struct stap_probe *longjmp_probe;
+
   /* Minimal symbol for "std::terminate()" (if any).  */
   struct minimal_symbol *terminate_msym;
 
@@ -2125,6 +2128,9 @@ struct breakpoint_objfile_data
 
 static const struct objfile_data *breakpoint_objfile_key;
 
+/* SystemTap probe not found sentinel.  */
+static const struct stap_probe probe_not_found;
+
 /* Minimal symbol not found sentinel.  */
 static struct minimal_symbol msym_not_found;
 
@@ -2232,6 +2238,29 @@ create_longjmp_master_breakpoint (void)
 
       bp_objfile_data = get_breakpoint_objfile_data (objfile);
 
+      if (bp_objfile_data->longjmp_probe != &probe_not_found)
+	{
+	  if (bp_objfile_data->longjmp_probe == NULL)
+	    bp_objfile_data->longjmp_probe
+	      = find_probe_in_objfile (objfile, "libc", "longjmp");
+
+	  if (bp_objfile_data->longjmp_probe)
+	    {
+	      struct breakpoint *b;
+	      struct gdbarch *gdbarch = get_objfile_arch (objfile);
+
+	      b = create_internal_breakpoint (gdbarch,
+					      bp_objfile_data->longjmp_probe->address,
+					      bp_longjmp_master);
+	      b->addr_string = xstrdup ("probe:libc:longjmp");
+	      b->enable_state = bp_disabled;
+
+	      continue;
+	    }
+	  else
+	    bp_objfile_data->longjmp_probe = &probe_not_found;
+	}
+
       for (i = 0; i < NUM_LONGJMP_NAMES; i++)
 	{
 	  struct breakpoint *b;
@@ -2328,8 +2357,6 @@ create_std_terminate_master_breakpoint (void)
 void
 create_exception_master_breakpoint (void)
 {
-  static struct stap_probe probe_not_found;
-
   struct objfile *objfile;
   const char *const func_name = "_Unwind_DebugHook";
 
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 0779215..751c9ef 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -4166,9 +4166,17 @@ process_event_stop_test:
 
 	if (what.is_longjmp)
 	  {
-	    if (!gdbarch_get_longjmp_target_p (gdbarch)
-		|| !gdbarch_get_longjmp_target (gdbarch,
-						frame, &jmp_buf_pc))
+	    struct value *arg_value;
+
+	    /* If we set the longjmp breakpoint via a SystemTap probe,
+	       then use it to extract the arguments.  The destination
+	       PC is the third argument to the probe.  */
+	    arg_value = stap_safe_evaluate_at_pc (frame, 2);
+	    if (arg_value)
+	      jmp_buf_pc = value_as_address (arg_value);
+	    else if (!gdbarch_get_longjmp_target_p (gdbarch)
+		     || !gdbarch_get_longjmp_target (gdbarch,
+						     frame, &jmp_buf_pc))
 	      {
 		if (debug_infrun)
 		  fprintf_unfiltered (gdb_stdlog,
@@ -5269,27 +5277,14 @@ insert_exception_resume_from_probe (struct thread_info *tp,
 				    struct objfile *objfile,
 				    struct frame_info *frame)
 {
-  int n_probes;
   struct value *arg_value;
   CORE_ADDR handler;
   struct breakpoint *bp;
 
-  /* This is really a "can't happen", but we are paranoid.  */
-  if (!objfile->sf || !objfile->sf->sym_probe_fns)
+  arg_value = stap_safe_evaluate_at_pc (frame, 1);
+  if (!arg_value)
     return;
 
-  n_probes
-    = objfile->sf->sym_probe_fns->sym_get_probe_argument_count (objfile,
-								probe);
-  if (n_probes < 2)
-    return;
- 
-  /* We are interested in the second argument to the probe.  */
-  arg_value
-    = objfile->sf->sym_probe_fns->sym_evaluate_probe_argument (objfile,
-							       probe,
-							       frame,
-							       1);
   handler = value_as_address (arg_value);
 
   if (debug_infrun)
diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c
index dd86b62..90c6c4f 100644
--- a/gdb/stap-probe.c
+++ b/gdb/stap-probe.c
@@ -1160,6 +1160,31 @@ stap_evaluate_probe_argument (struct objfile *objfile,
   return stap_evaluate_probe_argument_1 (objfile, probe, frame, n);
 }
 
+/* See documentation in stap-probe.h.  */
+
+struct value *
+stap_safe_evaluate_at_pc (struct frame_info *frame, int n)
+{
+  const struct stap_probe *probe;
+  struct objfile *objfile;
+  int n_probes;
+
+  probe = find_probe_by_pc (get_frame_pc (frame), &objfile);
+  if (!probe)
+    return NULL;
+  gdb_assert (objfile->sf && objfile->sf->sym_probe_fns);
+
+  n_probes
+    = objfile->sf->sym_probe_fns->sym_get_probe_argument_count (objfile,
+								probe);
+  if (n >= n_probes)
+    return NULL;
+
+  return objfile->sf->sym_probe_fns->sym_evaluate_probe_argument (objfile,
+								  probe,
+								  frame,
+								  n);
+}
 
 void
 stap_free_parsed_args (struct stap_args_info *parsed_args)
diff --git a/gdb/stap-probe.h b/gdb/stap-probe.h
index a2c9b30..f6e67c2 100644
--- a/gdb/stap-probe.h
+++ b/gdb/stap-probe.h
@@ -86,4 +86,10 @@ extern struct value *stap_evaluate_probe_argument (struct objfile *objfile,
 						   struct frame_info *frame,
 						   int n);
 
+/* A convenience function that finds a probe at the PC in FRAME and
+   evaluates argument N.  If there is no probe at that location, or if
+   the probe does not have enough arguments, this returns NULL.  */
+extern struct value *stap_safe_evaluate_at_pc (struct frame_info *frame,
+					       int n);
+
 #endif /* !defined (STAP_PROBE_H) */


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