Ensure that executable pages are properly guarded.

src/platform-cygwin.cc

 // Copyright 2012 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 337 matching lines @@
   return true;
 }
 
 
 bool VirtualMemory::Uncommit(void* address, size_t size) {
   ASSERT(IsReserved());
   return VirtualFree(address, size, MEM_DECOMMIT) != false;
 }
 
 
+bool VirtualMemory::Guard(void* address) {
+  if (NULL == VirtualAlloc(address,
+                           OS::CommitPageSize(),
+                           MEM_COMMIT,
+                           PAGE_READONLY | PAGE_GUARD)) {

[Erik Corry, 2012/02/23 12:00:40]

Can we not map it with no permissions at all, instead of read only?

+    return false;
+  }
+  return true;
+}
+
+
 class Thread::PlatformData : public Malloced {
  public:
   PlatformData() : thread_(kNoThread) {}
   pthread_t thread_;  // Thread handle for pthread.
 };
 
 
 
 
 Thread::Thread(const Options& options)
@@ skipping 382 matching lines @@
 
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SamplerThread::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal