android_system_core/libunwindstack/MapInfo.cpp
Christopher Ferris e69f470933 Multiple bugfixes, small restructuring.
- Move the load bias stored out of ElfInterface into Elf. For the compressed
  sections, the load bias was not the same as the data from the uncompressed
  section.
- Move the initialization of the compressed section into Init. It was too easy
  to forget to call the init of the compressed section.
- Do not automatically add in load bias to the pc before calling ElfInterface
  code. Do all of the pc manipulations in the Elf object.
- Change the interface GetFunctionName code to pass in the load_bias instead
  of modifying the pc inside the code.
- Modify the Step function to pass in the elf offset, not add it to the pc.
  It is necessary to have two different relative values when executing the
  Step: a pc that is relative to the beginning of the elf for the reading data
  the actual instructions when trying to determine if this is in a signal
  frame, and a pc that is relative to the map for finding the appropriate
  unwind information.
- Add a feature to Unwinder so that an unwind can be stopped if it ends up
  in map that has a specified suffix. This is so that the ART unwinding
  code doesn't require skipping the compressed section. Instead, stop at
  if trying to unwind through a known suffix code that means the code is
  in java code. This is important because the compressed section data is
  not only used by the jave compiled code, so that will continue to work.
- Fix tests for restructuring, add new tests for new functionality.

Test: Ran art test 137-cfi using new unwinder as default.
Test: Ran new unit tests.
Change-Id: I42e658c64c5e14f698ba34944a3043afac967884
2017-10-20 11:15:32 -07:00

120 lines
3.2 KiB
C++

/*
* Copyright (C) 2017 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 <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
#include <memory>
#include <string>
#include <unwindstack/Elf.h>
#include <unwindstack/MapInfo.h>
#include <unwindstack/Maps.h>
#include <unwindstack/Memory.h>
namespace unwindstack {
Memory* MapInfo::GetFileMemory() {
std::unique_ptr<MemoryFileAtOffset> memory(new MemoryFileAtOffset);
if (offset == 0) {
if (memory->Init(name, 0)) {
return memory.release();
}
return nullptr;
}
// There are two possibilities when the offset is non-zero.
// - There is an elf file embedded in a file.
// - The whole file is an elf file, and the offset needs to be saved.
//
// Map in just the part of the file for the map. If this is not
// a valid elf, then reinit as if the whole file is an elf file.
// If the offset is a valid elf, then determine the size of the map
// and reinit to that size. This is needed because the dynamic linker
// only maps in a portion of the original elf, and never the symbol
// file data.
uint64_t map_size = end - start;
if (!memory->Init(name, offset, map_size)) {
return nullptr;
}
bool valid;
uint64_t max_size;
Elf::GetInfo(memory.get(), &valid, &max_size);
if (!valid) {
// Init as if the whole file is an elf.
if (memory->Init(name, 0)) {
elf_offset = offset;
return memory.release();
}
return nullptr;
}
if (max_size > map_size) {
if (memory->Init(name, offset, max_size)) {
return memory.release();
}
// Try to reinit using the default map_size.
if (memory->Init(name, offset, map_size)) {
return memory.release();
}
return nullptr;
}
return memory.release();
}
Memory* MapInfo::CreateMemory(const std::shared_ptr<Memory>& process_memory) {
if (end <= start) {
return nullptr;
}
elf_offset = 0;
// Fail on device maps.
if (flags & MAPS_FLAGS_DEVICE_MAP) {
return nullptr;
}
// First try and use the file associated with the info.
if (!name.empty()) {
Memory* memory = GetFileMemory();
if (memory != nullptr) {
return memory;
}
}
// If the map isn't readable, don't bother trying to read from process memory.
if (!(flags & PROT_READ)) {
return nullptr;
}
return new MemoryRange(process_memory, start, end);
}
Elf* MapInfo::GetElf(const std::shared_ptr<Memory>& process_memory, bool init_gnu_debugdata) {
if (elf) {
return elf;
}
elf = new Elf(CreateMemory(process_memory));
elf->Init(init_gnu_debugdata);
// If the init fails, keep the elf around as an invalid object so we
// don't try to reinit the object.
return elf;
}
} // namespace unwindstack