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74 lines
2.2 KiB
74 lines
2.2 KiB
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "thread.h"
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#include <signal.h>
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#include "base/logging.h" // For VLOG.
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#include "base/utils.h"
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namespace art {
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static void SigAltStack(stack_t* new_stack, stack_t* old_stack) {
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if (sigaltstack(new_stack, old_stack) == -1) {
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PLOG(FATAL) << "sigaltstack failed";
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}
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}
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// The default SIGSTKSZ on linux is 8K. If we do any logging in a signal
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// handler or do a stack unwind, this is too small. We allocate 32K
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// instead of the minimum signal stack size.
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// TODO: We shouldn't do logging (with locks) in signal handlers.
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static constexpr int kHostAltSigStackSize =
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32 * KB < MINSIGSTKSZ ? MINSIGSTKSZ : 32 * KB;
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void Thread::SetUpAlternateSignalStack() {
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// Create and set an alternate signal stack.
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#ifdef ART_TARGET_ANDROID
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LOG(FATAL) << "Invalid use of alternate signal stack on Android";
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#endif
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stack_t ss;
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ss.ss_sp = new uint8_t[kHostAltSigStackSize];
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ss.ss_size = kHostAltSigStackSize;
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ss.ss_flags = 0;
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CHECK(ss.ss_sp != nullptr);
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SigAltStack(&ss, nullptr);
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// Double-check that it worked.
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ss.ss_sp = nullptr;
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SigAltStack(nullptr, &ss);
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VLOG(threads) << "Alternate signal stack is " << PrettySize(ss.ss_size) << " at " << ss.ss_sp;
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}
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void Thread::TearDownAlternateSignalStack() {
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// Get the pointer so we can free the memory.
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stack_t ss;
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SigAltStack(nullptr, &ss);
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uint8_t* allocated_signal_stack = reinterpret_cast<uint8_t*>(ss.ss_sp);
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// Tell the kernel to stop using it.
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ss.ss_sp = nullptr;
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ss.ss_flags = SS_DISABLE;
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ss.ss_size = kHostAltSigStackSize; // Avoid ENOMEM failure with Mac OS' buggy libc.
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SigAltStack(&ss, nullptr);
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// Free it.
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delete[] allocated_signal_stack;
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}
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} // namespace art
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