Use PAGE_NOACCESS for guard pages in Windows.

Up until now we used PAGE_GUARD for guard pages in Windows, which
will raise a STATUS_GUARD_PAGE_VIOLATION exception on first access
and grant regular access afterwards. This behavior is required to
implement automatic stack checking, or more generally to implement
applications that monitor the growth of large dynamic data structures.

However, this is not what we want for our guard pages, which are
used as a security mechanism. What we really want is PAGE_NOACCESS
here, which is the Windows-equivalent of PROT_NONE that we use on
all other platforms.

R=cdn@chromium.org

Review URL: https://codereview.chromium.org/23458022

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16604 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/platform-cygwin.cc

@@ -344,7 +344,7 @@ bool VirtualMemory::Guard(void* address) {
   if (NULL == VirtualAlloc(address,
                            OS::CommitPageSize(),
                            MEM_COMMIT,
-                           PAGE_READONLY | PAGE_GUARD)) {
+                           PAGE_NOACCESS)) {
     return false;
   }
   return true;

src/platform-posix.cc

@@ -152,7 +152,7 @@ void OS::ProtectCode(void* address, const size_t size) {
 void OS::Guard(void* address, const size_t size) {
 #if defined(__CYGWIN__)
   DWORD oldprotect;
-  VirtualProtect(address, size, PAGE_READONLY | PAGE_GUARD, &oldprotect);
+  VirtualProtect(address, size, PAGE_NOACCESS, &oldprotect);
 #else
   mprotect(address, size, PROT_NONE);
 #endif

src/platform-win32.cc

@@ -865,7 +865,7 @@ void OS::ProtectCode(void* address, const size_t size) {
 
 void OS::Guard(void* address, const size_t size) {
   DWORD oldprotect;
-  VirtualProtect(address, size, PAGE_READONLY | PAGE_GUARD, &oldprotect);
+  VirtualProtect(address, size, PAGE_NOACCESS, &oldprotect);
 }
 
 
@@ -1441,7 +1441,7 @@ bool VirtualMemory::Guard(void* address) {
   if (NULL == VirtualAlloc(address,
                            OS::CommitPageSize(),
                            MEM_COMMIT,
-                           PAGE_READONLY | PAGE_GUARD)) {
+                           PAGE_NOACCESS)) {
     return false;
   }
   return true;