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

src/trusted/service_runtime/nacl_app_thread.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 Server Runtime user thread state.
  */
 
@@ skipping 21 matching lines @@
   NaClSignalStackRegister(natp->signal_stack);
 
   NaClLog(4, "      natp = 0x%016"NACL_PRIxPTR"\n", (uintptr_t) natp);
   NaClLog(4, " prog_ctr  = 0x%016"NACL_PRIxNACL_REG"\n", natp->user.prog_ctr);
   NaClLog(4, "stack_ptr  = 0x%016"NACL_PRIxPTR"\n",
           NaClGetThreadCtxSp(&natp->user));
 
   thread_idx = NaClGetThreadIdx(natp);
   CHECK(0 < thread_idx);
   CHECK(thread_idx < NACL_THREAD_MAX);
-  NaClTlsSetIdx(thread_idx);
+  NaClTlsSetCurrentThread(natp);
   nacl_user[thread_idx] = &natp->user;
 #if NACL_WINDOWS
   nacl_thread_ids[thread_idx] = GetCurrentThreadId();
 #endif
 
   /*
    * We have to hold the threads_mu lock until after thread_num field
    * in this thread has been initialized.  All other threads can only
    * find and examine this natp through the threads table, so the fact
    * that natp is not consistent (no thread_num) will not be visible.
@@ skipping 63 matching lines @@
   thread_idx = NaClGetThreadIdx(natp);
   /*
    * On x86-64 and ARM, clearing nacl_user entry ensures that we will
    * fault if another syscall is made with this thread_idx.  In
    * particular, thread_idx 0 is never used.
    */
   nacl_user[thread_idx] = NULL;
 #if NACL_WINDOWS
   nacl_thread_ids[thread_idx] = 0;
 #endif
+  NaClTlsSetCurrentThread(NULL);
 
   NaClLog(3, " removing thread from thread table\n");
   /* Deallocate the ID natp->thread_num. */
   NaClRemoveThreadMu(nap, natp->thread_num);
   NaClLog(3, " unlocking thread\n");
   NaClXMutexUnlock(&natp->mu);
   NaClLog(3, " unlocking thread table\n");
   NaClXMutexUnlock(&nap->threads_mu);
   NaClLog(3, " unregistering signal stack\n");
   NaClSignalStackUnregister();
@@ skipping 124 matching lines @@
     NaClThreadDtor(&natp->host_thread);
   }
   free(natp->suspended_registers);
   NaClMutexDtor(&natp->suspend_mu);
   NaClSignalStackFree(natp->signal_stack);
   natp->signal_stack = NULL;
   NaClTlsFree(natp);
   NaClMutexDtor(&natp->mu);
   NaClAlignedFree(natp);
 }