[MIPS] Make $t8 point to the address of TLS pointers

src/trusted/service_runtime/arch/mips/sel_rt.c

 /*
  * Copyright (c) 2012 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.
  */
 
 /*
  * NaCl Secure Runtime
  */
 #include "native_client/src/include/portability_string.h"
+#include "native_client/src/shared/platform/nacl_global_secure_random.h"
 #include "native_client/src/trusted/service_runtime/nacl_app_thread.h"
 #include "native_client/src/trusted/service_runtime/nacl_signal.h"
 #include "native_client/src/trusted/service_runtime/nacl_tls.h"
 #include "native_client/src/trusted/service_runtime/sel_ldr.h"
 #include "native_client/src/trusted/service_runtime/sel_rt.h"
 #include "native_client/src/trusted/service_runtime/arch/mips/sel_ldr_mips.h"
 
+uint32_t nacl_guard_token;
+
 void NaClInitGlobals(void) {
-   NaClLog(2, "NaClInitGlobals\n");
-  /* intentionally left empty */
+  NaClLog(2, "NaClInitGlobals\n");
+  nacl_guard_token = NaClGlobalSecureRngUint32();
 }
 
 
 int NaClAppThreadInitArchSpecific(struct NaClAppThread *natp,
                                   nacl_reg_t           prog_ctr,
                                   nacl_reg_t           stack_ptr) {
   struct NaClThreadContext *ntcp = &natp->user;
 
   /*
    * We call this function so that it does not appear to be dead code,
    * although it only contains compile-time assertions.
    */
   NaClThreadContextOffsetCheck();
 
   memset((void *)ntcp, 0, sizeof(*ntcp));
   ntcp->stack_ptr = stack_ptr;
   ntcp->prog_ctr = prog_ctr;
   ntcp->tls_idx = NaClTlsAllocate(natp);
   if (ntcp->tls_idx == NACL_TLS_INDEX_INVALID)
     return 0;
+  ntcp->t8 = (uintptr_t) &ntcp->tls_value1;
+  ntcp->guard_token = nacl_guard_token;
 
   NaClLog(4, "user.tls_idx: 0x%08"NACL_PRIxNACL_REG"\n", ntcp->tls_idx);
   NaClLog(4, "user.stack_ptr: 0x%08"NACL_PRIxNACL_REG"\n", ntcp->stack_ptr);
   NaClLog(4, "user.prog_ctr: 0x%08"NACL_PRIxNACL_REG"\n", ntcp->prog_ctr);
 
   return 1;
 }
 
 
 void NaClThreadContextToSignalContext(const struct NaClThreadContext *th_ctx,
@@ skipping 49 matching lines @@
   sig_ctx->t2          = 0;
   sig_ctx->t3          = 0;
   sig_ctx->t4          = 0;
   sig_ctx->t5          = 0;
   sig_ctx->t9          = 0;
   sig_ctx->k0          = 0;
   sig_ctx->k1          = 0;
   sig_ctx->global_ptr  = 0;
   sig_ctx->return_addr = 0;
 }