/*
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* Copyright (C) 2018 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 "backtrace_helper.h"
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#if defined(__linux__)
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#include <backtrace/Backtrace.h>
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#include <backtrace/BacktraceMap.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include "thread-inl.h"
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#else
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// For UNUSED
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#include "base/macros.h"
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#endif
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namespace art {
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// We only really support libbacktrace on linux which is unfortunate but since this is only for
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// gcstress this isn't a huge deal.
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#if defined(__linux__)
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static const char* kBacktraceCollectorTlsKey = "BacktraceCollectorTlsKey";
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struct BacktraceMapHolder : public TLSData {
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BacktraceMapHolder() : map_(BacktraceMap::Create(getpid())) {}
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std::unique_ptr<BacktraceMap> map_;
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};
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static BacktraceMap* GetMap(Thread* self) {
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BacktraceMapHolder* map_holder =
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reinterpret_cast<BacktraceMapHolder*>(self->GetCustomTLS(kBacktraceCollectorTlsKey));
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if (map_holder == nullptr) {
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map_holder = new BacktraceMapHolder;
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// We don't care about the function names. Turning this off makes everything significantly
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// faster.
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map_holder->map_->SetResolveNames(false);
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// Only created and queried on Thread::Current so no sync needed.
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self->SetCustomTLS(kBacktraceCollectorTlsKey, map_holder);
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}
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return map_holder->map_.get();
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}
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void BacktraceCollector::Collect() {
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std::unique_ptr<Backtrace> backtrace(Backtrace::Create(BACKTRACE_CURRENT_PROCESS,
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BACKTRACE_CURRENT_THREAD,
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GetMap(Thread::Current())));
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backtrace->SetSkipFrames(true);
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if (!backtrace->Unwind(skip_count_, nullptr)) {
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return;
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}
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for (Backtrace::const_iterator it = backtrace->begin();
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max_depth_ > num_frames_ && it != backtrace->end();
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++it) {
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out_frames_[num_frames_++] = static_cast<uintptr_t>(it->pc);
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}
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}
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#else
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#pragma clang diagnostic push
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#pragma clang diagnostic warning "-W#warnings"
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#warning "Backtrace collector is not implemented. GCStress cannot be used."
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#pragma clang diagnostic pop
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// We only have an implementation for linux. On other plaforms just return nothing. This is not
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// really correct but we only use this for hashing and gcstress so it's not too big a deal.
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void BacktraceCollector::Collect() {
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UNUSED(skip_count_);
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UNUSED(out_frames_);
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UNUSED(max_depth_);
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num_frames_ = 0;
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}
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#endif
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} // namespace art
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