Change BKPT and UDF encodings on ARM.

tests/debug_stub/debugger_test.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 <pthread.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 15 matching lines @@
  * top-level assembly.
  */
 #if defined(__i386__) || defined(__x86_64__)
 __asm__(".pushsection .text, \"ax\", @progbits\n"
         "fault_addr:\n"
         "hlt\n"
         ".popsection\n");
 #elif defined(__arm__)
 __asm__(".pushsection .text, \"ax\", %progbits\n"
         "fault_addr:\n"
-        "bkpt 0x7777\n"
+        "udf 0xede0\n"
         ".popsection\n");
 #else
 # error Update fault_addr for other architectures
 #endif
 
 void set_registers_and_stop() {
   struct NaClSignalContext regs;
   memset(&regs, 0, sizeof(regs));
 
   /*
@@ skipping 133 matching lines @@
   /* We avoid using int3 because of a Mac OS X kernel bug. */
   __asm__("hlt");
 #elif defined(__arm__)
   /*
    * Arrange the breakpoint so that the test can skip over it by
    * jumping to the next bundle.  This means we never have to set the
    * program counter to within a bundle, which could be unsafe,
    * because BKPTs guard data literals in the ARM sandbox.
    */
   __asm__(".p2align 4\n"
-          "bkpt 0x7777\n"
+          "bkpt 0x5bef\n"
           ".p2align 4\n");
 #else
 # error Unsupported architecture
 #endif
 }
 
 void *child_thread_func(void *thread_arg) {
   for (;;) {
     g_child_thread_var++;
     breakpoint();
@@ skipping 43 matching lines @@
   if (strcmp(argv[1], "test_interrupt") == 0) {
     test_interrupt();
     return 0;
   }
   if (strcmp(argv[1], "test_suspending_threads") == 0) {
     test_suspending_threads();
     return 0;
   }
   return 1;
 }