104 lines
3.1 KiB
C++
104 lines
3.1 KiB
C++
/*
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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 <stdint.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <string>
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#include <vector>
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#include <unwindstack/Global.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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Global::Global(std::shared_ptr<Memory>& memory) : memory_(memory) {}
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Global::Global(std::shared_ptr<Memory>& memory, std::vector<std::string>& search_libs)
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: memory_(memory), search_libs_(search_libs) {}
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void Global::SetArch(ArchEnum arch) {
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if (arch_ == ARCH_UNKNOWN) {
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arch_ = arch;
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ProcessArch();
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}
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}
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uint64_t Global::GetVariableOffset(MapInfo* info, const std::string& variable) {
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if (!search_libs_.empty()) {
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bool found = false;
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const char* lib = basename(info->name.c_str());
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for (const std::string& name : search_libs_) {
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if (name == lib) {
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found = true;
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break;
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}
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}
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if (!found) {
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return 0;
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}
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}
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Elf* elf = info->GetElf(memory_, arch());
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uint64_t ptr;
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// Find first non-empty list (libraries might be loaded multiple times).
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if (elf->GetGlobalVariable(variable, &ptr) && ptr != 0) {
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return ptr + info->start;
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}
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return 0;
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}
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void Global::FindAndReadVariable(Maps* maps, const char* var_str) {
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std::string variable(var_str);
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// When looking for global variables, do not arbitrarily search every
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// readable map. Instead look for a specific pattern that must exist.
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// The pattern should be a readable map, followed by a read-write
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// map with a non-zero offset.
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// For example:
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// f0000-f1000 0 r-- /system/lib/libc.so
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// f1000-f2000 1000 r-x /system/lib/libc.so
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// f2000-f3000 2000 rw- /system/lib/libc.so
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// This also works:
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// f0000-f2000 0 r-- /system/lib/libc.so
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// f2000-f3000 2000 rw- /system/lib/libc.so
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MapInfo* map_start = nullptr;
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for (MapInfo* info : *maps) {
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if (map_start != nullptr) {
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if (map_start->name == info->name) {
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if (info->offset != 0 &&
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(info->flags & (PROT_READ | PROT_WRITE)) == (PROT_READ | PROT_WRITE)) {
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uint64_t ptr = GetVariableOffset(map_start, variable);
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if (ptr != 0 && ReadVariableData(ptr)) {
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break;
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} else {
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// Failed to find the global variable, do not bother trying again.
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map_start = nullptr;
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}
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}
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} else {
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map_start = nullptr;
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}
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}
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if (map_start == nullptr && (info->flags & PROT_READ) && info->offset == 0 &&
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!info->name.empty()) {
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map_start = info;
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}
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}
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}
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} // namespace unwindstack
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