- Add the ability to protect VirtualMemory.

runtime/vm/pages.cc

 // 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.
 
 #include "vm/pages.h"
 
 #include "platform/assert.h"
 #include "vm/gc_marker.h"
 #include "vm/gc_sweeper.h"
 #include "vm/object.h"
@@ skipping 69 matching lines @@
     if (raw_obj->FindObject(visitor)) {
       return raw_obj;  // Found object, return it.
     }
     obj_addr += raw_obj->Size();
   }
   ASSERT(obj_addr == end_addr);
   return Object::null();
 }
 
 
+void HeapPage::Protect(VirtualMemory::Protection mode) {
+  memory_->Protect(mode);
+}
+
+
 PageSpace::PageSpace(Heap* heap, intptr_t max_capacity, bool is_executable)
     : freelist_(),
       heap_(heap),
       pages_(NULL),
       pages_tail_(NULL),
       large_pages_(NULL),
       bump_page_(NULL),
       max_capacity_(max_capacity),
       capacity_(0),
       in_use_(0),
@@ skipping 233 matching lines @@
     RawObject* obj = page->FindObject(visitor);
     if (obj != Object::null()) {
       return obj;
     }
     page = page->next();
   }
   return Object::null();
 }
 
 
+void PageSpace::Protect(VirtualMemory::Protection mode) {
+  HeapPage* page = pages_;
+  while (page != NULL) {
+    page->Protect(mode);
+    page = page->next();
+  }
+  page = large_pages_;
+  while (page != NULL) {
+    page->Protect(mode);
+    page = page->next();
+  }

[siva, 2012/07/27 01:55:00]

How does this work in the face of heap growth?

i.e we called heap()->Protect(kReadWrite);

how does it then work when we grow the heap.

[Ivan Posva, 2012/07/27 18:02:56]

A read-write heap should be able to grow a read-only heap should be caught at
allocation time.

+}
+
+
 void PageSpace::MarkSweep(bool invoke_api_callbacks) {
   // MarkSweep is not reentrant. Make sure that is the case.
   ASSERT(!sweeping_);
   sweeping_ = true;
   Isolate* isolate = Isolate::Current();
   NoHandleScope no_handles(isolate);
 
   if (FLAG_print_free_list_before_gc) {
     freelist_.Print();
   }
@@ skipping 194 matching lines @@
     return 0;
   } else {
     ASSERT(total_time >= gc_time);
     int result= static_cast<int>((static_cast<double>(gc_time) /
                              static_cast<double>(total_time)) * 100);
     return result;
   }
 }
 
 }  // namespace dart