Enable check for DEP / NX page protection

src/trusted/platform_qualify/arch/arm/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>
-#include <stdint.h>
-#include "native_client/src/trusted/platform_qualify/nacl_dep_qualify.h"
-#include "native_client/src/include/nacl_macros.h"
-
-/* Assembled equivalent of "bx lr" */
-#define INST_BX_LR 0xE12FFF1E
-
-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 "bx lr" at the next aligned address after buf.  Instructions
-   * are always little-endian, regardless of data setting.
-   */
-  char *aligned_buf = (char *) (((uintptr_t) buf + 3) & ~3);
-
-  if (aligned_buf + 4 > buf + size_in_bytes) return 0;
-
-  aligned_buf[0] = (char) (INST_BX_LR >> 0);
-  aligned_buf[1] = (char) (INST_BX_LR >> 8);
-  aligned_buf[2] = (char) (INST_BX_LR >> 16);
-  aligned_buf[3] = (char) (INST_BX_LR >> 24);
-
-  /*
-   * 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) aligned_buf;
-}