Remove nacl_user[] array lookup from syscall code path on x86-64 and MIPS

src/trusted/service_runtime/linux/thread_suspension.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.
  */
 #include "native_client/src/trusted/service_runtime/linux/android_compat.h"
 
 #include <errno.h>
 #include <linux/futex.h>
 #include <signal.h>
@@ skipping 62 matching lines @@
       /* We have been asked to suspend, so wait. */
       FutexWait(&natp->suspend_state, state);
     } else {
       NaClLog(LOG_FATAL, "NaClAppThreadSetSuspendState: Unexpected state: %i\n",
               state);
     }
   }
 }
 
 static void HandleSuspendSignal(struct NaClSignalContext *regs) {
-  uint32_t tls_idx = NaClTlsGetIdx();
-  struct NaClAppThread *natp = NaClAppThreadGetFromIndex(tls_idx);
+  struct NaClAppThread *natp = NaClTlsGetCurrentThread();
   struct NaClSignalContext *suspended_registers =
       &natp->suspended_registers->context;
 
   /* Sanity check. */
   if (natp->suspend_state != (NACL_APP_THREAD_UNTRUSTED |
                               NACL_APP_THREAD_SUSPENDING)) {
     NaClSignalErrorMessage("HandleSuspendSignal: "
                            "Unexpected suspend_state\n");
     NaClAbort();
   }
@@ skipping 213 matching lines @@
                                  NACL_APP_THREAD_SUSPENDING));
 
   if (natp->fault_signal == 0) {
     return 0;
   }
   *signal = natp->fault_signal;
   natp->fault_signal = 0;
   AtomicIncrement(&natp->nap->faulted_thread_count, -1);
   return 1;
 }