be788d891d
Add a mutex in MapInfo, and a mutex in Elf. Lock the creation of an Elf file using the MapInfo mutex, and lock when calling Step, GetFunctionName, or GetSoname since they can modify information in the object. It might be beneficial to use a fine grained lock in the future. Change the Maps object to contain a vector of MapInfo pointers rather than the total objects. This avoids copying this data around. Add a test to libbacktrace to verify that sharing a map while doing unwinds in different threads works. Add concurrency tests in libunwindstack to verify the locking works. Add always inline to the RegsGetLocal arm and aarch64 functions. I had a case where clang did not inline the code, so make sure this is specified. Bug: 68813077 Test: New unit tests to cover the case. Passes all unit tests. Test: Ran a monkey test while dumping bugreports and verified that Test: no crashes in libunwind. Test: Remove the locking and verified that all of the concurrenty tests fail. Change-Id: I769e728c676f6bdae9e64ce4cdc03b6749beae03
124 lines
3.3 KiB
C++
124 lines
3.3 KiB
C++
/*
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* Copyright (C) 2017 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 <sys/mman.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <memory>
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#include <mutex>
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#include <string>
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#include <unwindstack/Elf.h>
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#include <unwindstack/MapInfo.h>
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#include <unwindstack/Maps.h>
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#include <unwindstack/Memory.h>
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namespace unwindstack {
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Memory* MapInfo::GetFileMemory() {
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std::unique_ptr<MemoryFileAtOffset> memory(new MemoryFileAtOffset);
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if (offset == 0) {
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if (memory->Init(name, 0)) {
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return memory.release();
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}
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return nullptr;
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}
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// There are two possibilities when the offset is non-zero.
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// - There is an elf file embedded in a file.
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// - The whole file is an elf file, and the offset needs to be saved.
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//
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// Map in just the part of the file for the map. If this is not
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// a valid elf, then reinit as if the whole file is an elf file.
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// If the offset is a valid elf, then determine the size of the map
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// and reinit to that size. This is needed because the dynamic linker
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// only maps in a portion of the original elf, and never the symbol
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// file data.
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uint64_t map_size = end - start;
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if (!memory->Init(name, offset, map_size)) {
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return nullptr;
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}
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bool valid;
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uint64_t max_size;
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Elf::GetInfo(memory.get(), &valid, &max_size);
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if (!valid) {
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// Init as if the whole file is an elf.
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if (memory->Init(name, 0)) {
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elf_offset = offset;
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return memory.release();
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}
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return nullptr;
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}
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if (max_size > map_size) {
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if (memory->Init(name, offset, max_size)) {
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return memory.release();
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}
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// Try to reinit using the default map_size.
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if (memory->Init(name, offset, map_size)) {
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return memory.release();
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}
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return nullptr;
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}
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return memory.release();
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}
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Memory* MapInfo::CreateMemory(const std::shared_ptr<Memory>& process_memory) {
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if (end <= start) {
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return nullptr;
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}
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elf_offset = 0;
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// Fail on device maps.
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if (flags & MAPS_FLAGS_DEVICE_MAP) {
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return nullptr;
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}
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// First try and use the file associated with the info.
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if (!name.empty()) {
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Memory* memory = GetFileMemory();
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if (memory != nullptr) {
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return memory;
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}
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}
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// If the map isn't readable, don't bother trying to read from process memory.
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if (!(flags & PROT_READ)) {
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return nullptr;
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}
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return new MemoryRange(process_memory, start, end);
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}
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Elf* MapInfo::GetElf(const std::shared_ptr<Memory>& process_memory, bool init_gnu_debugdata) {
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// Make sure no other thread is trying to add the elf to this map.
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std::lock_guard<std::mutex> guard(mutex_);
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if (elf) {
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return elf;
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}
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elf = new Elf(CreateMemory(process_memory));
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elf->Init(init_gnu_debugdata);
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// If the init fails, keep the elf around as an invalid object so we
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// don't try to reinit the object.
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return elf;
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}
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} // namespace unwindstack
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