8254811: JDK-8254158 broke ppc64, s390 builds

Reviewed-by: stuefe, goetz

Author: TheRealMDoerr

src/hotspot/os/posix/os_posix.cpp

@@ -965,8 +965,12 @@ bool os::Posix::handle_stack_overflow(JavaThread* thread, address addr, address
           if (activation.sp() != NULL) {
             overflow_state->disable_stack_reserved_zone();
             if (activation.is_interpreted_frame()) {
-              overflow_state->set_reserved_stack_activation((address)(
-                activation.fp() + frame::interpreter_frame_initial_sp_offset));
+              overflow_state->set_reserved_stack_activation((address)(activation.fp()
+                // Some platforms use frame pointers for interpreter frames, others use initial sp.
+#if !defined(PPC64) && !defined(S390)
+                + frame::interpreter_frame_initial_sp_offset
+#endif
+                ));
             } else {
               overflow_state->set_reserved_stack_activation((address)activation.unextended_sp());
             }

src/hotspot/os_cpu/aix_ppc/os_aix_ppc.cpp

@@ -146,7 +146,7 @@ frame os::fetch_compiled_frame_from_context(const void* ucVoid) {
   const ucontext_t* uc = (const ucontext_t*)ucVoid;
   intptr_t* sp = os::Aix::ucontext_get_sp(uc);
   address lr = ucontext_get_lr(uc);
-  *fr = frame(sp, lr);
+  return frame(sp, lr);
 }
 
 frame os::get_sender_for_C_frame(frame* fr) {