Fix problems with finishing a dummy function call on simulators.

[external/binutils.git] / gdb / breakpoint.c

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 7f9e161..1481112 100644 (file)
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -8898,11 +8898,21 @@ add_location_to_breakpoint (struct breakpoint *b,
   set_breakpoint_location_function (loc,
                                    sal->explicit_pc || sal->explicit_line);
 
+  /* While by definition, permanent breakpoints are already present in the
+     code, we don't mark the location as inserted.  Normally one would expect
+     that GDB could rely on that breakpoint instruction to stop the program,
+     thus removing the need to insert its own breakpoint, except that executing
+     the breakpoint instruction can kill the target instead of reporting a
+     SIGTRAP.  E.g., on SPARC, when interrupts are disabled, executing the
+     instruction resets the CPU, so QEMU 2.0.0 for SPARC correspondingly dies
+     with "Trap 0x02 while interrupts disabled, Error state".  Letting the
+     breakpoint be inserted normally results in QEMU knowing about the GDB
+     breakpoint, and thus trap before the breakpoint instruction is executed.
+     (If GDB later needs to continue execution past the permanent breakpoint,
+     it manually increments the PC, thus avoiding executing the breakpoint
+     instruction.)  */
   if (bp_loc_is_permanent (loc))
-    {
-      loc->inserted = 1;
-      loc->permanent = 1;
-    }
+    loc->permanent = 1;
 
   return loc;
 }
@@ -8954,20 +8964,6 @@ bp_loc_is_permanent (struct bp_location *loc)
 
   gdb_assert (loc != NULL);
 
-  /* bp_call_dummy breakpoint locations are usually memory locations
-     where GDB just wrote a breakpoint instruction, making it look
-     as if there is a permanent breakpoint at that location.  Considering
-     it permanent makes GDB rely on that breakpoint instruction to stop
-     the program, thus removing the need to insert its own breakpoint
-     there.  This is normally expected to work, except that some versions
-     of QEMU (Eg: QEMU 2.0.0 for SPARC) just report a fatal problem (Trap
-     0x02 while interrupts disabled, Error state) instead of reporting
-     a SIGTRAP.  QEMU should probably be fixed, but in the interest of
-     compatibility with versions that behave this way, we always consider
-     bp_call_dummy breakpoint locations as non-permanent.  */
-  if (loc->owner->type == bp_call_dummy)
-    return 0;
-
   cleanup = save_current_space_and_thread ();
   switch_to_program_space_and_thread (loc->pspace);
 
@@ -12419,12 +12415,6 @@ update_global_location_list (enum ugll_insert_mode insert_mode)
          continue;
        }
 
-      /* Permanent breakpoint should always be inserted.  */
-      if (loc->permanent && ! loc->inserted)
-       internal_error (__FILE__, __LINE__,
-                       _("allegedly permanent breakpoint is not "
-                       "actually inserted"));
-
       if (b->type == bp_hardware_watchpoint)
        loc_first_p = &wp_loc_first;
       else if (b->type == bp_read_watchpoint)
@@ -12460,12 +12450,6 @@ update_global_location_list (enum ugll_insert_mode insert_mode)
 
       /* Clear the condition modification flag.  */
       loc->condition_changed = condition_unchanged;
-
-      if (loc->inserted && !loc->permanent
-         && (*loc_first_p)->permanent)
-       internal_error (__FILE__, __LINE__,
-                       _("another breakpoint was inserted on top of "
-                       "a permanent breakpoint"));
     }
 
   if (insert_mode == UGLL_INSERT || breakpoints_should_be_inserted_now ())