Add basic infrastructure for protecting V8's heap when leaving the VM...

src/spaces-inl.h

 // Copyright 2006-2008 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 201 matching lines @@
 }
 
 
 PagedSpace* MemoryAllocator::PageOwner(Page* page) {
   int chunk_id = GetChunkId(page);
   ASSERT(IsValidChunk(chunk_id));
   return chunks_[chunk_id].owner();
 }
 
 
+bool MemoryAllocator::InInitialChunk(Address address) {
+  if (initial_chunk_ == NULL) return false;
+
+  Address start = static_cast<Address>(initial_chunk_->address());
+  return (start <= address) && (address < start + initial_chunk_->size());
+}
+
+
+#ifdef ENABLE_HEAP_PROTECTION
+
+void MemoryAllocator::Protect(Address start, size_t size) {
+  OS::Protect(start, size);
+}
+
+
+void MemoryAllocator::Unprotect(Address start,
+                                size_t size,
+                                Executability executable) {
+  OS::Unprotect(start, size, executable);
+}
+
+
+void MemoryAllocator::ProtectChunkFromPage(Page* page) {
+  int id = GetChunkId(page);
+  OS::Protect(chunks_[id].address(), chunks_[id].size());
+}
+
+
+void MemoryAllocator::UnprotectChunkFromPage(Page* page) {
+  int id = GetChunkId(page);
+  OS::Unprotect(chunks_[id].address(), chunks_[id].size(),
+                chunks_[id].owner()->executable() == EXECUTABLE);
+}
+
+#endif
+
+
 // --------------------------------------------------------------------------
 // PagedSpace
 
 bool PagedSpace::Contains(Address addr) {
   Page* p = Page::FromAddress(addr);
   ASSERT(p->is_valid());
 
   return MemoryAllocator::IsPageInSpace(p, this);
 }
 
@@ skipping 78 matching lines @@
   ASSERT(space->low() <= alloc_info->top
          && alloc_info->top <= space->high()
          && alloc_info->limit == space->high());
 #endif
   return obj;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_INL_H_