/* * 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 #include #include #include #include <7zCrc.h> #include #include #include #include #include #include #include #include "DwarfDebugFrame.h" #include "DwarfEhFrame.h" #include "Symbols.h" namespace unwindstack { ElfInterface::~ElfInterface() { for (auto symbol : symbols_) { delete symbol; } } Memory* ElfInterface::CreateGnuDebugdataMemory() { if (gnu_debugdata_offset_ == 0 || gnu_debugdata_size_ == 0) { return nullptr; } // TODO: Only call these initialization functions once. CrcGenerateTable(); Crc64GenerateTable(); std::vector src(gnu_debugdata_size_); if (!memory_->Read(gnu_debugdata_offset_, src.data(), gnu_debugdata_size_)) { gnu_debugdata_offset_ = 0; gnu_debugdata_size_ = static_cast(-1); return nullptr; } ISzAlloc alloc; CXzUnpacker state; alloc.Alloc = [](void*, size_t size) { return malloc(size); }; alloc.Free = [](void*, void* ptr) { return free(ptr); }; XzUnpacker_Construct(&state, &alloc); std::unique_ptr dst(new MemoryBuffer); int return_val; size_t src_offset = 0; size_t dst_offset = 0; ECoderStatus status; dst->Resize(5 * gnu_debugdata_size_); do { size_t src_remaining = src.size() - src_offset; size_t dst_remaining = dst->Size() - dst_offset; if (dst_remaining < 2 * gnu_debugdata_size_) { dst->Resize(dst->Size() + 2 * gnu_debugdata_size_); dst_remaining += 2 * gnu_debugdata_size_; } return_val = XzUnpacker_Code(&state, dst->GetPtr(dst_offset), &dst_remaining, &src[src_offset], &src_remaining, CODER_FINISH_ANY, &status); src_offset += src_remaining; dst_offset += dst_remaining; } while (return_val == SZ_OK && status == CODER_STATUS_NOT_FINISHED); XzUnpacker_Free(&state); if (return_val != SZ_OK || !XzUnpacker_IsStreamWasFinished(&state)) { gnu_debugdata_offset_ = 0; gnu_debugdata_size_ = static_cast(-1); return nullptr; } // Shrink back down to the exact size. dst->Resize(dst_offset); return dst.release(); } template void ElfInterface::InitHeadersWithTemplate() { if (eh_frame_offset_ != 0) { eh_frame_.reset(new DwarfEhFrame(memory_)); if (!eh_frame_->Init(eh_frame_offset_, eh_frame_size_)) { eh_frame_.reset(nullptr); eh_frame_offset_ = 0; eh_frame_size_ = static_cast(-1); } } if (debug_frame_offset_ != 0) { debug_frame_.reset(new DwarfDebugFrame(memory_)); if (!debug_frame_->Init(debug_frame_offset_, debug_frame_size_)) { debug_frame_.reset(nullptr); debug_frame_offset_ = 0; debug_frame_size_ = static_cast(-1); } } } template bool ElfInterface::ReadAllHeaders() { EhdrType ehdr; if (!memory_->Read(0, &ehdr, sizeof(ehdr))) { return false; } if (!ReadProgramHeaders(ehdr)) { return false; } // We could still potentially unwind without the section header // information, so ignore any errors. if (!ReadSectionHeaders(ehdr)) { log(0, "Malformed section header found, ignoring..."); } return true; } template bool ElfInterface::ReadProgramHeaders(const EhdrType& ehdr) { uint64_t offset = ehdr.e_phoff; for (size_t i = 0; i < ehdr.e_phnum; i++, offset += ehdr.e_phentsize) { PhdrType phdr; if (!memory_->ReadField(offset, &phdr, &phdr.p_type, sizeof(phdr.p_type))) { return false; } if (HandleType(offset, phdr.p_type)) { continue; } switch (phdr.p_type) { case PT_LOAD: { // Get the flags first, if this isn't an executable header, ignore it. if (!memory_->ReadField(offset, &phdr, &phdr.p_flags, sizeof(phdr.p_flags))) { return false; } if ((phdr.p_flags & PF_X) == 0) { continue; } if (!memory_->ReadField(offset, &phdr, &phdr.p_vaddr, sizeof(phdr.p_vaddr))) { return false; } if (!memory_->ReadField(offset, &phdr, &phdr.p_offset, sizeof(phdr.p_offset))) { return false; } if (!memory_->ReadField(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) { return false; } pt_loads_[phdr.p_offset] = LoadInfo{phdr.p_offset, phdr.p_vaddr, static_cast(phdr.p_memsz)}; if (phdr.p_offset == 0) { load_bias_ = phdr.p_vaddr; } break; } case PT_GNU_EH_FRAME: if (!memory_->ReadField(offset, &phdr, &phdr.p_offset, sizeof(phdr.p_offset))) { return false; } eh_frame_offset_ = phdr.p_offset; if (!memory_->ReadField(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) { return false; } eh_frame_size_ = phdr.p_memsz; break; case PT_DYNAMIC: if (!memory_->ReadField(offset, &phdr, &phdr.p_offset, sizeof(phdr.p_offset))) { return false; } dynamic_offset_ = phdr.p_offset; if (!memory_->ReadField(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) { return false; } dynamic_size_ = phdr.p_memsz; break; } } return true; } template bool ElfInterface::ReadSectionHeaders(const EhdrType& ehdr) { uint64_t offset = ehdr.e_shoff; uint64_t sec_offset = 0; uint64_t sec_size = 0; // Get the location of the section header names. // If something is malformed in the header table data, we aren't going // to terminate, we'll simply ignore this part. ShdrType shdr; if (ehdr.e_shstrndx < ehdr.e_shnum) { uint64_t sh_offset = offset + ehdr.e_shstrndx * ehdr.e_shentsize; if (memory_->ReadField(sh_offset, &shdr, &shdr.sh_offset, sizeof(shdr.sh_offset)) && memory_->ReadField(sh_offset, &shdr, &shdr.sh_size, sizeof(shdr.sh_size))) { sec_offset = shdr.sh_offset; sec_size = shdr.sh_size; } } // Skip the first header, it's always going to be NULL. offset += ehdr.e_shentsize; for (size_t i = 1; i < ehdr.e_shnum; i++, offset += ehdr.e_shentsize) { if (!memory_->ReadField(offset, &shdr, &shdr.sh_type, sizeof(shdr.sh_type))) { return false; } if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) { if (!memory_->Read(offset, &shdr, sizeof(shdr))) { return false; } // Need to go get the information about the section that contains // the string terminated names. ShdrType str_shdr; if (shdr.sh_link >= ehdr.e_shnum) { return false; } uint64_t str_offset = ehdr.e_shoff + shdr.sh_link * ehdr.e_shentsize; if (!memory_->ReadField(str_offset, &str_shdr, &str_shdr.sh_type, sizeof(str_shdr.sh_type))) { return false; } if (str_shdr.sh_type != SHT_STRTAB) { return false; } if (!memory_->ReadField(str_offset, &str_shdr, &str_shdr.sh_offset, sizeof(str_shdr.sh_offset))) { return false; } if (!memory_->ReadField(str_offset, &str_shdr, &str_shdr.sh_size, sizeof(str_shdr.sh_size))) { return false; } symbols_.push_back(new Symbols(shdr.sh_offset, shdr.sh_size, shdr.sh_entsize, str_shdr.sh_offset, str_shdr.sh_size)); } else if (shdr.sh_type == SHT_PROGBITS && sec_size != 0) { // Look for the .debug_frame and .gnu_debugdata. if (!memory_->ReadField(offset, &shdr, &shdr.sh_name, sizeof(shdr.sh_name))) { return false; } if (shdr.sh_name < sec_size) { std::string name; if (memory_->ReadString(sec_offset + shdr.sh_name, &name)) { uint64_t* offset_ptr = nullptr; uint64_t* size_ptr = nullptr; if (name == ".debug_frame") { offset_ptr = &debug_frame_offset_; size_ptr = &debug_frame_size_; } else if (name == ".gnu_debugdata") { offset_ptr = &gnu_debugdata_offset_; size_ptr = &gnu_debugdata_size_; } if (offset_ptr != nullptr && memory_->ReadField(offset, &shdr, &shdr.sh_offset, sizeof(shdr.sh_offset)) && memory_->ReadField(offset, &shdr, &shdr.sh_size, sizeof(shdr.sh_size))) { *offset_ptr = shdr.sh_offset; *size_ptr = shdr.sh_size; } } } } } return true; } template bool ElfInterface::GetSonameWithTemplate(std::string* soname) { if (soname_type_ == SONAME_INVALID) { return false; } if (soname_type_ == SONAME_VALID) { *soname = soname_; return true; } soname_type_ = SONAME_INVALID; uint64_t soname_offset = 0; uint64_t strtab_offset = 0; uint64_t strtab_size = 0; // Find the soname location from the dynamic headers section. DynType dyn; uint64_t offset = dynamic_offset_; uint64_t max_offset = offset + dynamic_size_; for (uint64_t offset = dynamic_offset_; offset < max_offset; offset += sizeof(DynType)) { if (!memory_->Read(offset, &dyn, sizeof(dyn))) { return false; } if (dyn.d_tag == DT_STRTAB) { strtab_offset = dyn.d_un.d_ptr; } else if (dyn.d_tag == DT_STRSZ) { strtab_size = dyn.d_un.d_val; } else if (dyn.d_tag == DT_SONAME) { soname_offset = dyn.d_un.d_val; } else if (dyn.d_tag == DT_NULL) { break; } } soname_offset += strtab_offset; if (soname_offset >= strtab_offset + strtab_size) { return false; } if (!memory_->ReadString(soname_offset, &soname_)) { return false; } soname_type_ = SONAME_VALID; *soname = soname_; return true; } template bool ElfInterface::GetFunctionNameWithTemplate(uint64_t addr, std::string* name, uint64_t* func_offset) { if (symbols_.empty()) { return false; } for (const auto symbol : symbols_) { if (symbol->GetName(addr, load_bias_, memory_, name, func_offset)) { return true; } } return false; } bool ElfInterface::Step(uint64_t pc, Regs* regs, Memory* process_memory, bool* finished) { // Need to subtract off the load_bias to get the correct pc. if (pc < load_bias_) { return false; } pc -= load_bias_; // Try the eh_frame first. DwarfSection* eh_frame = eh_frame_.get(); if (eh_frame != nullptr && eh_frame->Step(pc, regs, process_memory, finished)) { return true; } // Try the debug_frame next. DwarfSection* debug_frame = debug_frame_.get(); if (debug_frame != nullptr && debug_frame->Step(pc, regs, process_memory, finished)) { return true; } return false; } // This is an estimation of the size of the elf file using the location // of the section headers and size. This assumes that the section headers // are at the end of the elf file. If the elf has a load bias, the size // will be too large, but this is acceptable. template void ElfInterface::GetMaxSizeWithTemplate(Memory* memory, uint64_t* size) { EhdrType ehdr; if (!memory->Read(0, &ehdr, sizeof(ehdr))) { return; } if (ehdr.e_shnum == 0) { return; } *size = ehdr.e_shoff + ehdr.e_shentsize * ehdr.e_shnum; } // Instantiate all of the needed template functions. template void ElfInterface::InitHeadersWithTemplate(); template void ElfInterface::InitHeadersWithTemplate(); template bool ElfInterface::ReadAllHeaders(); template bool ElfInterface::ReadAllHeaders(); template bool ElfInterface::ReadProgramHeaders(const Elf32_Ehdr&); template bool ElfInterface::ReadProgramHeaders(const Elf64_Ehdr&); template bool ElfInterface::ReadSectionHeaders(const Elf32_Ehdr&); template bool ElfInterface::ReadSectionHeaders(const Elf64_Ehdr&); template bool ElfInterface::GetSonameWithTemplate(std::string*); template bool ElfInterface::GetSonameWithTemplate(std::string*); template bool ElfInterface::GetFunctionNameWithTemplate(uint64_t, std::string*, uint64_t*); template bool ElfInterface::GetFunctionNameWithTemplate(uint64_t, std::string*, uint64_t*); template void ElfInterface::GetMaxSizeWithTemplate(Memory*, uint64_t*); template void ElfInterface::GetMaxSizeWithTemplate(Memory*, uint64_t*); } // namespace unwindstack