Manually randomize the memory addresses for regions of JIT code in the Large ...

src/platform-win32.cc

Index: src/platform-win32.cc
===================================================================
--- src/platform-win32.cc	(revision 5136)
+++ src/platform-win32.cc	(working copy)
@@ -840,10 +840,23 @@
                    bool is_executable) {
   // VirtualAlloc rounds allocated size to page size automatically.
   size_t msize = RoundUp(requested, static_cast<int>(GetPageSize()));
-
+  intptr_t address = NULL;
   // Windows XP SP2 allows Data Excution Prevention (DEP).
   int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
-  LPVOID mbase = VirtualAlloc(NULL, msize, MEM_COMMIT | MEM_RESERVE, prot);
+  // TODO(805): Port to Linux
+  // For exectutable pages try and randomize the allocation address
+  if (prot == PAGE_EXECUTE_READWRITE && msize >= Page::kPageSize) {
+      address = (V8::Random() << kPageSizeBits) | kAllocationRandomAddressMin;
+      address &= kAllocationRandomAddressMax;
+  }
+
+  LPVOID mbase = VirtualAlloc(reinterpret_cast<void *>(address),
+                              msize,
+                              MEM_COMMIT | MEM_RESERVE,
+                              prot);
+  if (mbase == NULL && address != NULL)
+    mbase = VirtualAlloc(NULL, msize, MEM_COMMIT | MEM_RESERVE, prot);
+
   if (mbase == NULL) {
     LOG(StringEvent("OS::Allocate", "VirtualAlloc failed"));
     return NULL;