Sanitize access to gdbarch on the SDT probe API (and fix ARM bug)

This patch sanitizes the access to gdbarch made by various functions of
the SDT probe API.  Before this patch, gdbarch was being accessed via
the probe's objfile; however, this proved to cause a bug on 32-bit ARM
targets because during the parsing of the probe's arguments the code
needed to access some pseudo-registers of the architecture, and this
information is not fully correct on the objfile's gdbarch.

Basically, the approach taken was to instead pass the current/selected
frame to the parsing and evaluation functions, so that they can extract
the gdbarch directly from the frame.  It solved the ARM bug reported
above, and also contributed to make the API cleaner.

Tested on x86_64 and 32-bit ARM.

2013-12-11  Sergio Durigan Junior  <sergiodj@redhat.com>

	* break-catch-throw.c (fetch_probe_arguments): Pass selected frame
	to get_probe_argument_count and evaluate_probe_argument.
	* probe.c (get_probe_argument_count): Adjust declaration to accept
	frame.  Pass frame to probe_ops's get_probe_argument_count.
	(evaluate_probe_argument): Likewise, for evaluate_probe_argument.
	(probe_safe_evaluate_at_pc): Pass frame to
	get_probe_argument_count and evaluate_probe_argument.
	* probe.h (struct probe_ops) <get_probe_argument_count,
	evaluate_probe_argument>: Adjust declarations to accept frame.
	(get_probe_argument_count, evaluate_probe_argument): Likewise.
	* solib-svr4.c (solib_event_probe_action): Get current frame.
	Pass it to get_probe_argument_count.
	(svr4_handle_solib_event): Get current frame.  Pass it to
	get_probe_argument_count and evaluate_probe_argument.
	* stap-probe.c (stap_parse_probe_arguments): Adjust declaration to
	accept gdbarch.  Do not obtain it from the probe's objfile.
	(stap_get_probe_argument_count): Adjust declaration to accept
	frame.  Obtain gdbarch from the frame.  Call generic
	can_evaluate_probe_arguments.  Pass gdbarch to
	stap_parse_probe_arguments.
	(stap_get_arg): Adjust declaration to accept gdbarch.  Pass it to
	stap_parse_probe_arguments.
	(stap_evaluate_probe_argument): Adjust declaration to accept
	frame.  Obtain gdbarch from the frame.  Pass gdbarch to
	stap_get_arg.
	(stap_compile_to_ax): Pass agent_expr's gdbarch to stap_get_arg.
	(compute_probe_arg): Obtain gdbarch from frame.  Pass frame to
	get_probe_argument_count and evaluate_probe_argument.

1 files changed, 17 insertions, 13 deletions

diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c
index e09d5d6..33d4569 100644
--- a/gdb/stap-probe.c
+++ b/gdb/stap-probe.c
@@ -914,10 +914,9 @@ stap_parse_argument (const char **arg, struct type *atype,
    this information.  */
 
 static void
-stap_parse_probe_arguments (struct stap_probe *probe)
+stap_parse_probe_arguments (struct stap_probe *probe, struct gdbarch *gdbarch)
 {
   const char *cur;
-  struct gdbarch *gdbarch = get_objfile_arch (probe->p.objfile);
 
   gdb_assert (!probe->args_parsed);
   cur = probe->args_u.text;
@@ -1002,16 +1001,18 @@ stap_parse_probe_arguments (struct stap_probe *probe)
    argument string.  */
 
 static unsigned
-stap_get_probe_argument_count (struct probe *probe_generic)
+stap_get_probe_argument_count (struct probe *probe_generic,
+			       struct frame_info *frame)
 {
   struct stap_probe *probe = (struct stap_probe *) probe_generic;
+  struct gdbarch *gdbarch = get_frame_arch (frame);
 
   gdb_assert (probe_generic->pops == &stap_probe_ops);
 
   if (!probe->args_parsed)
     {
-      if (probe_generic->pops->can_evaluate_probe_arguments (probe_generic))
-	stap_parse_probe_arguments (probe);
+      if (can_evaluate_probe_arguments (probe_generic))
+	stap_parse_probe_arguments (probe, gdbarch);
       else
 	{
 	  static int have_warned_stap_incomplete = 0;
@@ -1072,10 +1073,10 @@ stap_is_operator (const char *op)
 }
 
 static struct stap_probe_arg *
-stap_get_arg (struct stap_probe *probe, unsigned n)
+stap_get_arg (struct stap_probe *probe, unsigned n, struct gdbarch *gdbarch)
 {
   if (!probe->args_parsed)
-    stap_parse_probe_arguments (probe);
+    stap_parse_probe_arguments (probe, gdbarch);
 
   return VEC_index (stap_probe_arg_s, probe->args_u.vec, n);
 }
@@ -1098,15 +1099,17 @@ stap_can_evaluate_probe_arguments (struct probe *probe_generic)
    corresponding to it.  Assertion is thrown if N does not exist.  */
 
 static struct value *
-stap_evaluate_probe_argument (struct probe *probe_generic, unsigned n)
+stap_evaluate_probe_argument (struct probe *probe_generic, unsigned n,
+			      struct frame_info *frame)
 {
   struct stap_probe *stap_probe = (struct stap_probe *) probe_generic;
+  struct gdbarch *gdbarch = get_frame_arch (frame);
   struct stap_probe_arg *arg;
   int pos = 0;
 
   gdb_assert (probe_generic->pops == &stap_probe_ops);
 
-  arg = stap_get_arg (stap_probe, n);
+  arg = stap_get_arg (stap_probe, n, gdbarch);
   return evaluate_subexp_standard (arg->atype, arg->aexpr, &pos, EVAL_NORMAL);
 }
 
@@ -1123,7 +1126,7 @@ stap_compile_to_ax (struct probe *probe_generic, struct agent_expr *expr,
 
   gdb_assert (probe_generic->pops == &stap_probe_ops);
 
-  arg = stap_get_arg (stap_probe, n);
+  arg = stap_get_arg (stap_probe, n, expr->gdbarch);
 
   pc = arg->aexpr->elts;
   gen_expr (arg->aexpr, &pc, expr, value);
@@ -1177,7 +1180,7 @@ compute_probe_arg (struct gdbarch *arch, struct internalvar *ivar,
   if (pc_probe == NULL)
     error (_("No SystemTap probe at PC %s"), core_addr_to_string (pc));
 
-  n_args = get_probe_argument_count (pc_probe);
+  n_args = get_probe_argument_count (pc_probe, frame);
   if (sel == -1)
     return value_from_longest (builtin_type (arch)->builtin_int, n_args);
 
@@ -1185,7 +1188,7 @@ compute_probe_arg (struct gdbarch *arch, struct internalvar *ivar,
     error (_("Invalid probe argument %d -- probe has %u arguments available"),
 	   sel, n_args);
 
-  return evaluate_probe_argument (pc_probe, sel);
+  return evaluate_probe_argument (pc_probe, sel, frame);
 }
 
 /* This is called to compile one of the $_probe_arg* convenience
@@ -1200,6 +1203,7 @@ compile_probe_arg (struct internalvar *ivar, struct agent_expr *expr,
   struct probe *pc_probe;
   const struct sym_probe_fns *pc_probe_fns;
   int n_args;
+  struct frame_info *frame = get_selected_frame (NULL);
 
   /* SEL == -1 means "_probe_argc".  */
   gdb_assert (sel >= -1);
@@ -1208,7 +1212,7 @@ compile_probe_arg (struct internalvar *ivar, struct agent_expr *expr,
   if (pc_probe == NULL)
     error (_("No SystemTap probe at PC %s"), core_addr_to_string (pc));
 
-  n_args = get_probe_argument_count (pc_probe);
+  n_args = get_probe_argument_count (pc_probe, frame);
 
   if (sel == -1)
     {