Landing: Write protect executable pages in the VM.

runtime/vm/dart.cc

 // Copyright (c) 2013, 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/dart.h"
 
 #include "vm/code_observers.h"
 #include "vm/cpu.h"
 #include "vm/dart_api_state.h"
 #include "vm/dart_entry.h"
@@ skipping 114 matching lines @@
     Scanner::InitOnce();
     Object::CreateInternalMetaData();
     TargetCPUFeatures::InitOnce();
 #if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
     // Dart VM requires at least SSE2.
     if (!TargetCPUFeatures::sse2_supported()) {
       return "SSE2 is required.";
     }
 #endif
     PremarkingVisitor premarker(vm_isolate_);
+    vm_isolate_->heap()->WriteProtect(false);
     vm_isolate_->heap()->IterateOldObjects(&premarker);
     vm_isolate_->heap()->WriteProtect(true);
   }
   // There is a planned and known asymmetry here: We enter one scope for the VM
   // isolate so that we can allocate the "persistent" scoped handles for the
   // predefined API values (such as Dart_True, Dart_False and Dart_Null).
   Dart_EnterScope();
   Api::InitHandles();
 
   Isolate::SetCurrent(NULL);  // Unregister the VM isolate from this thread.
@@ skipping 127 matching lines @@
   return predefined_handles_->handles_.AllocateScopedHandle();
 }
 
 
 bool Dart::IsReadOnlyHandle(uword address) {
   ASSERT(predefined_handles_ != NULL);
   return predefined_handles_->handles_.IsValidScopedHandle(address);
 }
 
 }  // namespace dart