Don't modify memory access right when changing data in debug stub.

tests/gdb/nacl.scons

 # -*- python -*-
 # 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.
 
 Import('env')
 
 if 'TRUSTED_ENV' not in env:
   Return()
 
@@ skipping 50 matching lines @@
 
 node = env.CommandTest(
     'gdb_step_from_func_start.out',
     command=['${PYTHON}', env.File('step_from_func_start.py')],
     osenv=env_vars + ['GDB_TEST_GUEST=%s' % gdb_test_guest.abspath],
     extra_deps=[sel_ldr, irt, gdb_test_guest])
 
 env.AddNodeToTestSuite(node, ['large_tests'],
                        'run_gdb_step_from_func_start_test')
 
+node = env.CommandTest(
+    'gdb_call.out',
+    command=['${PYTHON}', env.File('call.py')],

[Mark Seaborn, 2012/08/30 16:55:57]

Nit: "call" is a bit generic.  Can you call this something like "call_from_gdb"
or "manufactured_call"?  Something to indicate that GDB is doing something a
little scary when it hijacks a thread and modifies its registers to run a
function of its choosing. :-)

[halyavin, 2012/08/31 08:01:24]

Done.

+    osenv=env_vars + ['GDB_TEST_GUEST=%s' % gdb_test_guest.abspath],
+    extra_deps=[sel_ldr, irt, gdb_test_guest])
+
+env.AddNodeToTestSuite(node, ['large_tests'],
+                       'run_gdb_call_test')
+
 # GDB treats multithreaded programs specially. Provide distinct nexe for
 # multithreaded tests to isolate multiple threads-specific issues.
 gdb_test_guest_thread = env.ComponentProgram(
     'gdb_test_guest_thread', 'gdb_test_guest_thread.c',
     EXTRA_LIBS=['${PTHREAD_LIBS}', '${NONIRT_LIBS}'])
 
 node = env.CommandTest(
     'gdb_break_continue_thread.out',
     command=['${PYTHON}', env.File('break_continue_thread.py')],
     osenv=env_vars + ['GDB_TEST_GUEST=%s' % gdb_test_guest_thread.abspath],
     extra_deps=[sel_ldr, irt, gdb_test_guest_thread])
 
 env.AddNodeToTestSuite(node, ['large_tests'],
                        'run_gdb_break_continue_thread_test')
 
 node = env.CommandTest(
     'gdb_syscall_thread.out',
     command=['${PYTHON}', env.File('syscall_thread.py')],
     osenv=env_vars + ['GDB_TEST_GUEST=%s' % gdb_test_guest_thread.abspath],
     extra_deps=[sel_ldr, irt, gdb_test_guest_thread])
 
 env.AddNodeToTestSuite(node, ['large_tests'],
                        'run_gdb_syscall_thread_test')