Ensure that executable pages are properly guarded.

src/platform-macos.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 411 matching lines @@
 bool VirtualMemory::IsReserved() {
   return address_ != NULL;
 }
 
 
 bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
   return CommitRegion(address, size, is_executable);
 }
 
 
+bool VirtualMemory::Guard(void* address) {
+  OS::Guard(address, OS::CommitPageSize());
+  return true;
+}
+
+
 bool VirtualMemory::CommitRegion(void* address,
                                  size_t size,
                                  bool is_executable) {
   int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
   if (MAP_FAILED == mmap(address,
                          size,
                          prot,
                          MAP_PRIVATE | MAP_ANON | MAP_FIXED,
                          kMmapFd,
                          kMmapFdOffset)) {
@@ skipping 444 matching lines @@
 
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SamplerThread::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal