Landing: Write protect executable pages in the VM.

runtime/vm/code_patcher.h

Index: runtime/vm/code_patcher.h
diff --git a/runtime/vm/code_patcher.h b/runtime/vm/code_patcher.h
index 0a7410fbecd1746b912a85be0203b5cff74c1194..10ab117fd42d61f108f15f1f09da5da7bede6c5a 100644
--- a/runtime/vm/code_patcher.h
+++ b/runtime/vm/code_patcher.h
@@ -22,6 +22,22 @@ 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.