- Add the ability to protect VirtualMemory.

runtime/vm/pages.cc

Index: runtime/vm/pages.cc
===================================================================
--- runtime/vm/pages.cc	(revision 9969)
+++ runtime/vm/pages.cc	(working copy)
@@ -87,6 +87,11 @@
 }
 
 
+void HeapPage::Protect(VirtualMemory::Protection mode) {
+  memory_->Protect(mode);
+}
+
+
 PageSpace::PageSpace(Heap* heap, intptr_t max_capacity, bool is_executable)
     : freelist_(),
       heap_(heap),
@@ -340,6 +345,20 @@
 }
 
 
+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_);