| /* |
| * Copyright (C) 2012 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 "elf_fixup.h" |
| |
| #include <inttypes.h> |
| #include <memory> |
| |
| #include "base/logging.h" |
| #include "base/stringprintf.h" |
| #include "elf_file.h" |
| #include "elf_writer.h" |
| |
| namespace art { |
| |
| static const bool DEBUG_FIXUP = false; |
| |
| bool ElfFixup::Fixup(File* file, uintptr_t oat_data_begin) { |
| std::string error_msg; |
| std::unique_ptr<ElfFile> elf_file(ElfFile::Open(file, true, false, &error_msg)); |
| CHECK(elf_file.get() != nullptr) << error_msg; |
| |
| // Lookup "oatdata" symbol address. |
| Elf32_Addr oatdata_address = ElfWriter::GetOatDataAddress(elf_file.get()); |
| Elf32_Off base_address = oat_data_begin - oatdata_address; |
| |
| if (!FixupDynamic(*elf_file.get(), base_address)) { |
| LOG(WARNING) << "Failed fo fixup .dynamic in " << file->GetPath(); |
| return false; |
| } |
| if (!FixupSectionHeaders(*elf_file.get(), base_address)) { |
| LOG(WARNING) << "Failed fo fixup section headers in " << file->GetPath(); |
| return false; |
| } |
| if (!FixupProgramHeaders(*elf_file.get(), base_address)) { |
| LOG(WARNING) << "Failed fo fixup program headers in " << file->GetPath(); |
| return false; |
| } |
| if (!FixupSymbols(*elf_file.get(), base_address, true)) { |
| LOG(WARNING) << "Failed fo fixup .dynsym in " << file->GetPath(); |
| return false; |
| } |
| if (!FixupSymbols(*elf_file.get(), base_address, false)) { |
| LOG(WARNING) << "Failed fo fixup .symtab in " << file->GetPath(); |
| return false; |
| } |
| if (!FixupRelocations(*elf_file.get(), base_address)) { |
| LOG(WARNING) << "Failed fo fixup .rel.dyn in " << file->GetPath(); |
| return false; |
| } |
| return true; |
| } |
| |
| |
| bool ElfFixup::FixupDynamic(ElfFile& elf_file, uintptr_t base_address) { |
| for (Elf32_Word i = 0; i < elf_file.GetDynamicNum(); i++) { |
| Elf32_Dyn& elf_dyn = elf_file.GetDynamic(i); |
| Elf32_Word d_tag = elf_dyn.d_tag; |
| if (IsDynamicSectionPointer(d_tag, elf_file.GetHeader().e_machine)) { |
| uint32_t d_ptr = elf_dyn.d_un.d_ptr; |
| if (DEBUG_FIXUP) { |
| LOG(INFO) << StringPrintf("In %s moving Elf32_Dyn[%d] from 0x%08x to 0x%08" PRIxPTR, |
| elf_file.GetFile().GetPath().c_str(), i, |
| d_ptr, d_ptr + base_address); |
| } |
| d_ptr += base_address; |
| elf_dyn.d_un.d_ptr = d_ptr; |
| } |
| } |
| return true; |
| } |
| |
| bool ElfFixup::FixupSectionHeaders(ElfFile& elf_file, uintptr_t base_address) { |
| for (Elf32_Word i = 0; i < elf_file.GetSectionHeaderNum(); i++) { |
| Elf32_Shdr& sh = elf_file.GetSectionHeader(i); |
| // 0 implies that the section will not exist in the memory of the process |
| if (sh.sh_addr == 0) { |
| continue; |
| } |
| if (DEBUG_FIXUP) { |
| LOG(INFO) << StringPrintf("In %s moving Elf32_Shdr[%d] from 0x%08x to 0x%08" PRIxPTR, |
| elf_file.GetFile().GetPath().c_str(), i, |
| sh.sh_addr, sh.sh_addr + base_address); |
| } |
| sh.sh_addr += base_address; |
| } |
| return true; |
| } |
| |
| bool ElfFixup::FixupProgramHeaders(ElfFile& elf_file, uintptr_t base_address) { |
| // TODO: ELFObjectFile doesn't have give to Elf32_Phdr, so we do that ourselves for now. |
| for (Elf32_Word i = 0; i < elf_file.GetProgramHeaderNum(); i++) { |
| Elf32_Phdr& ph = elf_file.GetProgramHeader(i); |
| CHECK_EQ(ph.p_vaddr, ph.p_paddr) << elf_file.GetFile().GetPath() << " i=" << i; |
| CHECK((ph.p_align == 0) || (0 == ((ph.p_vaddr - ph.p_offset) & (ph.p_align - 1)))) |
| << elf_file.GetFile().GetPath() << " i=" << i; |
| if (DEBUG_FIXUP) { |
| LOG(INFO) << StringPrintf("In %s moving Elf32_Phdr[%d] from 0x%08x to 0x%08" PRIxPTR, |
| elf_file.GetFile().GetPath().c_str(), i, |
| ph.p_vaddr, ph.p_vaddr + base_address); |
| } |
| ph.p_vaddr += base_address; |
| ph.p_paddr += base_address; |
| CHECK((ph.p_align == 0) || (0 == ((ph.p_vaddr - ph.p_offset) & (ph.p_align - 1)))) |
| << elf_file.GetFile().GetPath() << " i=" << i; |
| } |
| return true; |
| } |
| |
| bool ElfFixup::FixupSymbols(ElfFile& elf_file, uintptr_t base_address, bool dynamic) { |
| Elf32_Word section_type = dynamic ? SHT_DYNSYM : SHT_SYMTAB; |
| // TODO: Unfortunate ELFObjectFile has protected symbol access, so use ElfFile |
| Elf32_Shdr* symbol_section = elf_file.FindSectionByType(section_type); |
| if (symbol_section == NULL) { |
| // file is missing optional .symtab |
| CHECK(!dynamic) << elf_file.GetFile().GetPath(); |
| return true; |
| } |
| for (uint32_t i = 0; i < elf_file.GetSymbolNum(*symbol_section); i++) { |
| Elf32_Sym& symbol = elf_file.GetSymbol(section_type, i); |
| if (symbol.st_value != 0) { |
| if (DEBUG_FIXUP) { |
| LOG(INFO) << StringPrintf("In %s moving Elf32_Sym[%d] from 0x%08x to 0x%08" PRIxPTR, |
| elf_file.GetFile().GetPath().c_str(), i, |
| symbol.st_value, symbol.st_value + base_address); |
| } |
| symbol.st_value += base_address; |
| } |
| } |
| return true; |
| } |
| |
| bool ElfFixup::FixupRelocations(ElfFile& elf_file, uintptr_t base_address) { |
| for (Elf32_Word i = 0; i < elf_file.GetSectionHeaderNum(); i++) { |
| Elf32_Shdr& sh = elf_file.GetSectionHeader(i); |
| if (sh.sh_type == SHT_REL) { |
| for (uint32_t i = 0; i < elf_file.GetRelNum(sh); i++) { |
| Elf32_Rel& rel = elf_file.GetRel(sh, i); |
| if (DEBUG_FIXUP) { |
| LOG(INFO) << StringPrintf("In %s moving Elf32_Rel[%d] from 0x%08x to 0x%08" PRIxPTR, |
| elf_file.GetFile().GetPath().c_str(), i, |
| rel.r_offset, rel.r_offset + base_address); |
| } |
| rel.r_offset += base_address; |
| } |
| } else if (sh.sh_type == SHT_RELA) { |
| for (uint32_t i = 0; i < elf_file.GetRelaNum(sh); i++) { |
| Elf32_Rela& rela = elf_file.GetRela(sh, i); |
| if (DEBUG_FIXUP) { |
| LOG(INFO) << StringPrintf("In %s moving Elf32_Rela[%d] from 0x%08x to 0x%08" PRIxPTR, |
| elf_file.GetFile().GetPath().c_str(), i, |
| rela.r_offset, rela.r_offset + base_address); |
| } |
| rela.r_offset += base_address; |
| } |
| } |
| } |
| return true; |
| } |
| |
| } // namespace art |