Enhance SafeStackFrameIterator to avoid triggering assertions in debug mode.

src/frames.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 125 matching lines @@
   if (thread_ != NULL) {
     type = ExitFrame::GetStateForFramePointer(Top::c_entry_fp(thread_), &state);
     handler_ = StackHandler::FromAddress(Top::handler(thread_));
   } else {
     ASSERT(fp_ != NULL);
     state.fp = fp_;
     state.sp = sp_;
     state.pc_address =
         reinterpret_cast<Address*>(StandardFrame::ComputePCAddress(fp_));
     type = StackFrame::ComputeType(&state);
-    if (SingletonFor(type) == NULL) return;
   }
+  if (SingletonFor(type) == NULL) return;
   frame_ = SingletonFor(type, &state);
 }
 
 
 StackFrame* StackFrameIterator::SingletonFor(StackFrame::Type type,
                                              StackFrame::State* state) {
   if (type == StackFrame::NONE) return NULL;
   StackFrame* result = SingletonFor(type);
   ASSERT(result != NULL);
   result->state_ = *state;
@@ skipping 38 matching lines @@
     Object* script = JSFunction::cast(frame()->function())->shared()->script();
     // Don't show functions from native scripts to user.
     return (script->IsScript() &&
             Script::TYPE_NATIVE != Script::cast(script)->type()->value());
 }
 
 
 // -------------------------------------------------------------------------
 
 
+bool SafeStackFrameIterator::ExitFrameValidator::IsValidFP(Address fp) {
+  if (!validator_.IsValid(fp)) return false;
+  Address sp = ExitFrame::ComputeStackPointer(fp);
+  if (!validator_.IsValid(sp)) return false;
+  StackFrame::State state;
+  ExitFrame::FillState(fp, sp, &state);
+  if (!validator_.IsValid(reinterpret_cast<Address>(state.pc_address))) {
+    return false;
+  }
+  return *state.pc_address != NULL;
+}
+
+
 SafeStackFrameIterator::SafeStackFrameIterator(
     Address fp, Address sp, Address low_bound, Address high_bound) :
-    maintainer_(), low_bound_(low_bound), high_bound_(high_bound),
-    is_valid_top_(
-        IsWithinBounds(low_bound, high_bound,
-                       Top::c_entry_fp(Top::GetCurrentThread())) &&
-        Top::handler(Top::GetCurrentThread()) != NULL),
+    maintainer_(),
+    stack_validator_(low_bound, high_bound),
+    is_valid_top_(IsValidTop(low_bound, high_bound)),
     is_valid_fp_(IsWithinBounds(low_bound, high_bound, fp)),
     is_working_iterator_(is_valid_top_ || is_valid_fp_),
     iteration_done_(!is_working_iterator_),
     iterator_(is_valid_top_, is_valid_fp_ ? fp : NULL, sp) {
 }
 
 
+bool SafeStackFrameIterator::IsValidTop(Address low_bound, Address high_bound) {
+  Address fp = Top::c_entry_fp(Top::GetCurrentThread());
+  ExitFrameValidator validator(low_bound, high_bound);
+  if (!validator.IsValidFP(fp)) return false;
+  return Top::handler(Top::GetCurrentThread()) != NULL;
+}
+
+
 void SafeStackFrameIterator::Advance() {
   ASSERT(is_working_iterator_);
   ASSERT(!done());
   StackFrame* last_frame = iterator_.frame();
   Address last_sp = last_frame->sp(), last_fp = last_frame->fp();
   // Before advancing to the next stack frame, perform pointer validity tests
   iteration_done_ = !IsValidFrame(last_frame) ||
       !CanIterateHandles(last_frame, iterator_.handler()) ||
       !IsValidCaller(last_frame);
   if (iteration_done_) return;
@@ skipping 21 matching lines @@
 
 
 bool SafeStackFrameIterator::IsValidCaller(StackFrame* frame) {
   StackFrame::State state;
   if (frame->is_entry() || frame->is_entry_construct()) {
     // See EntryFrame::GetCallerState. It computes the caller FP address
     // and calls ExitFrame::GetStateForFramePointer on it. We need to be
     // sure that caller FP address is valid.
     Address caller_fp = Memory::Address_at(
         frame->fp() + EntryFrameConstants::kCallerFPOffset);
-    if (!IsValidStackAddress(caller_fp)) {
-      return false;
-    }
+    ExitFrameValidator validator(stack_validator_);
+    if (!validator.IsValidFP(caller_fp)) return false;
   } else if (frame->is_arguments_adaptor()) {
     // See ArgumentsAdaptorFrame::GetCallerStackPointer. It assumes that
     // the number of arguments is stored on stack as Smi. We need to check
     // that it really an Smi.
     Object* number_of_args = reinterpret_cast<ArgumentsAdaptorFrame*>(frame)->
         GetExpression(0);
     if (!number_of_args->IsSmi()) {
       return false;
     }
   }
@@ skipping 134 matching lines @@
   IteratePc(v, pc_address(), code());
   v->VisitPointer(&code_slot());
 }
 
 
 Address ExitFrame::GetCallerStackPointer() const {
   return fp() + ExitFrameConstants::kCallerSPDisplacement;
 }
 
 
+StackFrame::Type ExitFrame::GetStateForFramePointer(Address fp, State* state) {
+  if (fp == 0) return NONE;
+  Address sp = ComputeStackPointer(fp);
+  FillState(fp, sp, state);
+  ASSERT(*state->pc_address != NULL);
+  return EXIT;
+}
+
+
+void ExitFrame::FillState(Address fp, Address sp, State* state) {
+  state->sp = sp;
+  state->fp = fp;
+  state->pc_address = reinterpret_cast<Address*>(sp - 1 * kPointerSize);
+}
+
+
 Address StandardFrame::GetExpressionAddress(int n) const {
   const int offset = StandardFrameConstants::kExpressionsOffset;
   return fp() + offset - n * kPointerSize;
 }
 
 
 int StandardFrame::ComputeExpressionsCount() const {
   const int offset =
       StandardFrameConstants::kExpressionsOffset + kPointerSize;
   Address base = fp() + offset;
@@ skipping 470 matching lines @@
   ZoneList<StackFrame*> list(10);
   for (StackFrameIterator it; !it.done(); it.Advance()) {
     StackFrame* frame = AllocateFrameCopy(it.frame());
     list.Add(frame);
   }
   return list.ToVector();
 }
 
 
 } }  // namespace v8::internal