Enable check for DEP / NX page protection

src/trusted/platform_qualify/arch/x86_64/nacl_dep_qualify.c

-/*
- * Copyright 2010 The Native Client Authors.  All rights reserved.
- * Use of this source code is governed by a BSD-style license that can
- * be found in the LICENSE file.
- */
-
-#include <stddef.h>
-
-#if !NACL_WINDOWS /* stdint is neither available nor needed on Windows */
-#include <stdint.h>
-#endif
-
-#include "native_client/src/trusted/platform_qualify/nacl_dep_qualify.h"
-#include "native_client/src/include/nacl_macros.h"
-
-/* Assembled equivalent of "ret" */
-#define INST_RET 0xC3
-
-int NaClCheckDEP() {
-  /*
-   * We require DEP, so forward this call to the OS-specific check routine.
-   */
-  return NaClAttemptToExecuteData();
-}
-
-nacl_void_thunk NaClGenerateThunk(char *buf, size_t size_in_bytes) {
-  /*
-   * Place a "ret" at buf.
-   */
-  if (size_in_bytes < 1) return 0;
-
-  *buf = (char) INST_RET;
-
-  /*
-   * ISO C prevents a direct data->function cast, because the pointers aren't
-   * guaranteed to be the same size.  For our platforms this is fine, but we
-   * verify at compile time anyway before tricking the compiler:
-   */
-  NACL_ASSERT_SAME_SIZE(char *, nacl_void_thunk);
-  return (nacl_void_thunk) (uintptr_t) buf;
-}