Write protect executable pages in the VM.

runtime/vm/assembler.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/assembler.h"
 
 #include "platform/utils.h"
 #include "vm/cpu.h"
 #include "vm/heap.h"
 #include "vm/memory_region.h"
@@ skipping 131 matching lines @@
   }
 
   void Process(const MemoryRegion& region, intptr_t position) {
     // Patch the handle into the code. Once the instructions are installed into
     // a raw code object and the pointer offsets are setup, the handle is
     // resolved.
     region.Store<const Object*>(position, &object_);
     pointer_offsets_->Add(position);
   }
 
+  virtual bool IsPointerOffset() const { return true; }
+
  private:
   ZoneGrowableArray<intptr_t>* pointer_offsets_;
   const Object& object_;
 };
 
 
+intptr_t AssemblerBuffer::CountPointerOffsets() const {
+  intptr_t count = 0;
+  AssemblerFixup* current = fixup_;
+  while (current != NULL) {
+    if (current->IsPointerOffset()) ++count;
+    current = current->previous_;
+  }
+  return count;
+}
+
+
 void AssemblerBuffer::EmitObject(const Object& object) {
   // Since we are going to store the handle as part of the fixup information
   // the handle needs to be a zone handle.
   ASSERT(object.IsNotTemporaryScopedHandle());
   ASSERT(object.IsOld());
   EmitFixup(new PatchCodeWithHandle(pointer_offsets_, object));
   cursor_ += kWordSize;  // Reserve space for pointer.
 }
 
 
@@ skipping 45 matching lines @@
 
   for (intptr_t i = 0; i < comments_.length(); i++) {
     comments.SetPCOffsetAt(i, comments_[i]->pc_offset());
     comments.SetCommentAt(i, comments_[i]->comment());
   }
 
   return comments;
 }
 
 }  // namespace dart