Landing: Write protect executable pages in the VM.

runtime/vm/code_patcher.h

 // 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.
 // Class for patching compiled code.
 
 #ifndef VM_CODE_PATCHER_H_
 #define VM_CODE_PATCHER_H_
 
 #include "vm/allocation.h"
 
 namespace dart {
 
 // Forward declaration.
 class Array;
 class Code;
 class ExternalLabel;
 class Function;
 class ICData;
 class RawArray;
 class RawFunction;
 class RawICData;
 class RawObject;
 class String;
 
+
+// Stack-allocated class to create a scope where the specified region
+// [address, addresss + size] has write access enabled. This is used
+// when patching generated code. Access is reset to read-execute in
+// the destructor of this scope.
+class WritableInstructionsScope : public ValueObject {
+ public:
+  WritableInstructionsScope(uword address, intptr_t size);
+  ~WritableInstructionsScope();
+
+ private:
+  const uword address_;
+  const intptr_t size_;
+};
+
+
 class CodePatcher : public AllStatic {
  public:
   // Dart static calls have a distinct, machine-dependent code pattern.
 
   // Patch static call before return_address in given code to the new target.
   static void PatchStaticCallAt(uword return_address,
                                 const Code& code,
                                 uword new_target_address);
 
   // Patch instance call before return_address in given code to the new target.
@@ skipping 42 matching lines @@
 
   static RawObject* GetEdgeCounterAt(uword pc, const Code& code);
 
   static int32_t GetPoolOffsetAt(uword return_address);
   static void SetPoolOffsetAt(uword return_address, int32_t offset);
 };
 
 }  // namespace dart
 
 #endif  // VM_CODE_PATCHER_H_