1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "thread.h"
18
19namespace art {
20
21void Thread::SetNativePriority(int) {
22  // Do nothing.
23}
24
25int Thread::GetNativePriority() {
26  return kNormThreadPriority;
27}
28
29static void SigAltStack(stack_t* new_stack, stack_t* old_stack) {
30  if (sigaltstack(new_stack, old_stack) == -1) {
31    PLOG(FATAL) << "sigaltstack failed";
32  }
33}
34
35void Thread::SetUpAlternateSignalStack() {
36  // Create and set an alternate signal stack.
37  stack_t ss;
38  ss.ss_sp = new uint8_t[SIGSTKSZ];
39  ss.ss_size = SIGSTKSZ;
40  ss.ss_flags = 0;
41  CHECK(ss.ss_sp != NULL);
42  SigAltStack(&ss, NULL);
43
44  // Double-check that it worked.
45  ss.ss_sp = NULL;
46  SigAltStack(NULL, &ss);
47  VLOG(threads) << "Alternate signal stack is " << PrettySize(ss.ss_size) << " at " << ss.ss_sp;
48}
49
50void Thread::TearDownAlternateSignalStack() {
51  // Get the pointer so we can free the memory.
52  stack_t ss;
53  SigAltStack(NULL, &ss);
54  uint8_t* allocated_signal_stack = reinterpret_cast<uint8_t*>(ss.ss_sp);
55
56  // Tell the kernel to stop using it.
57  ss.ss_sp = NULL;
58  ss.ss_flags = SS_DISABLE;
59  ss.ss_size = SIGSTKSZ;  // Avoid ENOMEM failure with Mac OS' buggy libc.
60  SigAltStack(&ss, NULL);
61
62  // Free it.
63  delete[] allocated_signal_stack;
64}
65
66}  // namespace art
67