thread_linux.cc revision b0f05b9654eb005bc8c8e15f615a7f5a312f640c
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 35// The default SIGSTKSZ on linux is 8K. If we do any logging in a signal 36// handler this is too small. We allocate 16K instead. 37static constexpr int kHostAltSigStackSize = 16*1024; // 16K signal stack. 38 39void Thread::SetUpAlternateSignalStack() { 40 // Create and set an alternate signal stack. 41#ifdef HAVE_ANDROID_OS 42 LOG(FATAL) << "Invalid use of alternate signal stack on Android"; 43#endif 44 stack_t ss; 45 ss.ss_sp = new uint8_t[kHostAltSigStackSize]; 46 ss.ss_size = kHostAltSigStackSize; 47 ss.ss_flags = 0; 48 CHECK(ss.ss_sp != NULL); 49 SigAltStack(&ss, NULL); 50 51 // Double-check that it worked. 52 ss.ss_sp = NULL; 53 SigAltStack(NULL, &ss); 54 VLOG(threads) << "Alternate signal stack is " << PrettySize(ss.ss_size) << " at " << ss.ss_sp; 55} 56 57void Thread::TearDownAlternateSignalStack() { 58 // Get the pointer so we can free the memory. 59 stack_t ss; 60 SigAltStack(NULL, &ss); 61 uint8_t* allocated_signal_stack = reinterpret_cast<uint8_t*>(ss.ss_sp); 62 63 // Tell the kernel to stop using it. 64 ss.ss_sp = NULL; 65 ss.ss_flags = SS_DISABLE; 66 ss.ss_size = kHostAltSigStackSize; // Avoid ENOMEM failure with Mac OS' buggy libc. 67 SigAltStack(&ss, NULL); 68 69 // Free it. 70 delete[] allocated_signal_stack; 71} 72 73} // namespace art 74