platform_system_core/libunwindstack/Global.cpp
Christopher Ferris df683b7439 Fix support finding global variables.
The code was not properly getting the variable addresses and using
the offset and address fields of the .data section.

Fix all of that, and update the tests.

Bug: 145162678

Test: Unit tests pass.
Test: ./art/test/run-test --dex2oat-jobs 4 --host --prebuild --compact-dex-level fast --jit --no-relocate --runtime-option -Xcheck:jni  137-cfi
Test: ./art/test/testrunner/testrunner.py -t 137 --host
Change-Id: Ic61c4487334fd2273cda9c56eb1a3b525a03edb7
2019-12-03 17:35:00 -08:00

101 lines
3 KiB
C++

/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdint.h>
#include <string.h>
#include <sys/mman.h>
#include <string>
#include <vector>
#include <unwindstack/Global.h>
#include <unwindstack/MapInfo.h>
#include <unwindstack/Maps.h>
#include <unwindstack/Memory.h>
namespace unwindstack {
Global::Global(std::shared_ptr<Memory>& memory) : memory_(memory) {}
Global::Global(std::shared_ptr<Memory>& memory, std::vector<std::string>& search_libs)
: memory_(memory), search_libs_(search_libs) {}
void Global::SetArch(ArchEnum arch) {
if (arch_ == ARCH_UNKNOWN) {
arch_ = arch;
ProcessArch();
}
}
bool Global::Searchable(const std::string& name) {
if (search_libs_.empty()) {
return true;
}
if (name.empty()) {
return false;
}
const char* base_name = basename(name.c_str());
for (const std::string& lib : search_libs_) {
if (base_name == lib) {
return true;
}
}
return false;
}
void Global::FindAndReadVariable(Maps* maps, const char* var_str) {
std::string variable(var_str);
// When looking for global variables, do not arbitrarily search every
// readable map. Instead look for a specific pattern that must exist.
// The pattern should be a readable map, followed by a read-write
// map with a non-zero offset.
// For example:
// f0000-f1000 0 r-- /system/lib/libc.so
// f1000-f2000 1000 r-x /system/lib/libc.so
// f2000-f3000 2000 rw- /system/lib/libc.so
// This also works:
// f0000-f2000 0 r-- /system/lib/libc.so
// f2000-f3000 2000 rw- /system/lib/libc.so
MapInfo* map_start = nullptr;
for (const auto& info : *maps) {
if (map_start != nullptr && map_start->name == info->name) {
if (info->offset != 0 &&
(info->flags & (PROT_READ | PROT_WRITE)) == (PROT_READ | PROT_WRITE)) {
Elf* elf = map_start->GetElf(memory_, arch());
uint64_t ptr;
if (elf->GetGlobalVariableOffset(variable, &ptr) && ptr != 0) {
uint64_t offset_end = info->offset + info->end - info->start;
if (ptr >= info->offset && ptr < offset_end) {
ptr = info->start + ptr - info->offset;
if (ReadVariableData(ptr)) {
break;
}
}
}
map_start = nullptr;
}
} else {
map_start = nullptr;
}
if (map_start == nullptr && (info->flags & PROT_READ) && info->offset == 0 &&
Searchable(info->name)) {
map_start = info.get();
}
}
}
} // namespace unwindstack