51 lines
1.6 KiB
C++
51 lines
1.6 KiB
C++
/*
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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 <signal.h>
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#include <sys/mman.h>
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#include "base/globals.h"
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#include "base/bit_utils.h"
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#include "thread.h"
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namespace art {
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void Thread::SetUpAlternateSignalStack() {
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// Bionic does this for us.
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}
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void Thread::TearDownAlternateSignalStack() {
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// Bionic does this for us.
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}
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void Thread::MadviseAwayAlternateSignalStack() {
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stack_t old_ss;
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int result = sigaltstack(nullptr, &old_ss);
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CHECK_EQ(result, 0);
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// Only call `madvise()` on enabled page-aligned alternate signal stack. Processes can
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// create different arbitrary alternate signal stacks and we do not want to erroneously
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// `madvise()` away pages that may hold data other than the alternate signal stack.
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if ((old_ss.ss_flags & SS_DISABLE) == 0 &&
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IsAligned<kPageSize>(old_ss.ss_sp) &&
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IsAligned<kPageSize>(old_ss.ss_size)) {
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CHECK_EQ(old_ss.ss_flags & SS_ONSTACK, 0);
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result = madvise(old_ss.ss_sp, old_ss.ss_size, MADV_DONTNEED);
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CHECK_EQ(result, 0);
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}
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}
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} // namespace art
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