| // Copyright 2019 The Cobalt Authors. All Rights Reserved. |
| // |
| // 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 "starboard/elf_loader/relocations.h" |
| |
| #include "starboard/common/log.h" |
| #include "starboard/elf_loader/log.h" |
| |
| namespace starboard { |
| namespace elf_loader { |
| |
| Relocations::Relocations(Addr base_memory_address, |
| DynamicSection* dynamic_section, |
| ExportedSymbols* exported_symbols) |
| : base_memory_address_(base_memory_address), |
| dynamic_section_(dynamic_section), |
| plt_relocations_(0), |
| plt_relocations_size_(0), |
| plt_got_(NULL), |
| relocations_(0), |
| relocations_size_(0), |
| has_text_relocations_(false), |
| has_symbolic_(false), |
| exported_symbols_(exported_symbols) {} |
| |
| bool Relocations::HasTextRelocations() { |
| return has_text_relocations_; |
| } |
| |
| bool Relocations::InitRelocations() { |
| SB_DLOG(INFO) << "InitRelocations: dynamic_count=" |
| << dynamic_section_->GetDynamicTableSize(); |
| const Dyn* dynamic = dynamic_section_->GetDynamicTable(); |
| for (int i = 0; i < dynamic_section_->GetDynamicTableSize(); i++) { |
| Addr dyn_value = dynamic[i].d_un.d_val; |
| uintptr_t dyn_addr = base_memory_address_ + dynamic[i].d_un.d_ptr; |
| Addr tag = dynamic[i].d_tag; |
| SB_DLOG(INFO) << "InitRelocations: tag=" << tag; |
| switch (tag) { |
| #if defined(USE_RELA) |
| case DT_REL: |
| case DT_RELSZ: |
| #else |
| case DT_RELA: |
| case DT_RELASZ: |
| #endif |
| SB_LOG(ERROR) << "unsupported relocation type"; |
| return false; |
| case DT_PLTREL: |
| SB_DLOG(INFO) << " DT_PLTREL value=" << dyn_value; |
| #if defined(USE_RELA) |
| if (dyn_value != DT_RELA) { |
| SB_LOG(ERROR) << "unsupported DT_PLTREL expected DT_RELA"; |
| return false; |
| } |
| #else |
| if (dyn_value != DT_REL) { |
| SB_LOG(ERROR) << "unsupported DT_PLTREL expected DT_REL"; |
| return false; |
| } |
| #endif |
| break; |
| case DT_JMPREL: |
| SB_DLOG(INFO) << " DT_JMPREL addr=0x" << std::hex |
| << (dyn_addr - base_memory_address_); |
| plt_relocations_ = dyn_addr; |
| break; |
| case DT_PLTRELSZ: |
| plt_relocations_size_ = dyn_value; |
| SB_DLOG(INFO) << " DT_PLTRELSZ size=" << dyn_value; |
| break; |
| #if defined(USE_RELA) |
| case DT_RELA: |
| #else |
| case DT_REL: |
| #endif |
| SB_DLOG(INFO) << " " << ((tag == DT_RELA) ? "DT_RELA" : "DT_REL") |
| << " addr=" << std::hex |
| << (dyn_addr - base_memory_address_); |
| if (relocations_) { |
| SB_LOG(ERROR) |
| << "Unsupported DT_RELA/DT_REL combination in dynamic section"; |
| return false; |
| } |
| relocations_ = dyn_addr; |
| break; |
| #if defined(USE_RELA) |
| case DT_RELASZ: |
| #else |
| case DT_RELSZ: |
| #endif |
| SB_DLOG(INFO) << " " << ((tag == DT_RELASZ) ? "DT_RELASZ" : "DT_RELSZ") |
| << " size=" << dyn_value; |
| relocations_size_ = dyn_value; |
| break; |
| case DT_RELR: |
| case DT_RELRSZ: |
| SB_LOG(ERROR) << " DT_RELRSZ NOT IMPELMENTED"; |
| break; |
| case DT_RELRENT: |
| case DT_PLTGOT: |
| SB_DLOG(INFO) << "DT_PLTGOT addr=0x" << std::hex |
| << (dyn_addr - base_memory_address_); |
| plt_got_ = reinterpret_cast<Addr*>(dyn_addr); |
| break; |
| case DT_TEXTREL: |
| SB_DLOG(INFO) << " DT_TEXTREL"; |
| has_text_relocations_ = true; |
| break; |
| case DT_SYMBOLIC: |
| SB_DLOG(INFO) << " DT_SYMBOLIC"; |
| has_symbolic_ = true; |
| break; |
| case DT_FLAGS: |
| if (dyn_value & DF_TEXTREL) |
| has_text_relocations_ = true; |
| if (dyn_value & DF_SYMBOLIC) |
| has_symbolic_ = true; |
| |
| SB_DLOG(INFO) << " DT_FLAGS has_text_relocations=" |
| << has_text_relocations_ |
| << " has_symbolic=" << has_symbolic_; |
| |
| break; |
| default: |
| break; |
| } |
| } |
| |
| return true; |
| } |
| |
| bool Relocations::ApplyAllRelocations() { |
| SB_DLOG(INFO) << "Applying regular relocations"; |
| if (!ApplyRelocations(reinterpret_cast<rel_t*>(relocations_), |
| relocations_size_ / sizeof(rel_t))) { |
| SB_LOG(ERROR) << "regular relocations failed"; |
| return false; |
| } |
| |
| SB_DLOG(INFO) << "Applying PLT relocations"; |
| if (!ApplyRelocations(reinterpret_cast<rel_t*>(plt_relocations_), |
| plt_relocations_size_ / sizeof(rel_t))) { |
| SB_LOG(ERROR) << "PLT relocations failed"; |
| return false; |
| } |
| return true; |
| } |
| |
| bool Relocations::ApplyRelocations(const rel_t* rel, size_t rel_count) { |
| SB_DLOG(INFO) << "rel=" << std::hex << rel << std::dec |
| << " rel_count=" << rel_count; |
| |
| if (!rel) |
| return true; |
| |
| for (size_t rel_n = 0; rel_n < rel_count; rel++, rel_n++) { |
| SB_DLOG(INFO) << " Relocation " << rel_n + 1 << " of " << rel_count; |
| |
| if (!ApplyRelocation(rel)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| bool Relocations::ApplyRelocation(const rel_t* rel) { |
| const Word rel_type = ELF_R_TYPE(rel->r_info); |
| const Word rel_symbol = ELF_R_SYM(rel->r_info); |
| |
| Addr sym_addr = 0; |
| Addr reloc = static_cast<Addr>(rel->r_offset + base_memory_address_); |
| SB_DLOG(INFO) << " offset=0x" << std::hex << rel->r_offset |
| << " type=" << std::dec << rel_type << " reloc=0x" << std::hex |
| << reloc << " symbol=" << rel_symbol; |
| |
| if (rel_type == 0) |
| return true; |
| |
| if (rel_symbol != 0) { |
| if (!ResolveSymbol(rel_type, rel_symbol, reloc, &sym_addr)) { |
| SB_LOG(ERROR) << "Failed to resolve symbol: " << rel_symbol; |
| return false; |
| } |
| } |
| |
| return ApplyResolvedReloc(rel, sym_addr); |
| } |
| |
| #if defined(USE_RELA) |
| bool Relocations::ApplyResolvedReloc(const Rela* rela, Addr sym_addr) { |
| const Word rela_type = ELF_R_TYPE(rela->r_info); |
| const Sword addend = rela->r_addend; |
| const Addr reloc = static_cast<Addr>(rela->r_offset + base_memory_address_); |
| |
| SB_DLOG(INFO) << " rela reloc=0x" << std::hex << reloc << " offset=0x" |
| << rela->r_offset << " type=" << std::dec << rela_type |
| << " addend=0x" << std::hex << addend; |
| Addr* target = reinterpret_cast<Addr*>(reloc); |
| switch (rela_type) { |
| #if SB_IS(ARCH_ARM64) |
| case R_AARCH64_JUMP_SLOT: |
| SB_DLOG(INFO) << " R_AARCH64_JUMP_SLOT target=" << std::hex << target |
| << " addr=" << (sym_addr + addend); |
| *target = sym_addr + addend; |
| break; |
| |
| case R_AARCH64_GLOB_DAT: |
| SB_DLOG(INFO) << " R_AARCH64_GLOB_DAT target=" << std::hex << target |
| << " addr=" << (sym_addr + addend); |
| *target = sym_addr + addend; |
| break; |
| |
| case R_AARCH64_ABS64: |
| SB_DLOG(INFO) << " R_AARCH64_ABS64 target=" << std::hex << target << " " |
| << *target << " addr=" << sym_addr + addend; |
| *target += sym_addr + addend; |
| break; |
| |
| case R_AARCH64_RELATIVE: |
| SB_DLOG(INFO) << " R_AARCH64_RELATIVE target=" << std::hex << target |
| << " " << *target |
| << " bias=" << base_memory_address_ + addend; |
| *target = base_memory_address_ + addend; |
| break; |
| #endif |
| |
| #if SB_IS(ARCH_X64) |
| case R_X86_64_JMP_SLOT: |
| SB_DLOG(INFO) << " R_X86_64_JMP_SLOT target=" << std::hex << target |
| << " addr=" << (sym_addr + addend); |
| *target = sym_addr + addend; |
| break; |
| |
| case R_X86_64_GLOB_DAT: |
| SB_DLOG(INFO) << " R_X86_64_GLOB_DAT target=" << std::hex << target |
| << " addr=" << (sym_addr + addend); |
| |
| *target = sym_addr + addend; |
| break; |
| |
| case R_X86_64_RELATIVE: |
| SB_DLOG(INFO) << " R_X86_64_RELATIVE target=" << std::hex << target |
| << " " << *target |
| << " bias=" << base_memory_address_ + addend; |
| *target = base_memory_address_ + addend; |
| break; |
| |
| case R_X86_64_64: |
| *target = sym_addr + addend; |
| break; |
| |
| case R_X86_64_PC32: |
| *target = sym_addr + (addend - reloc); |
| break; |
| #endif |
| |
| default: |
| SB_LOG(ERROR) << "Invalid relocation type: " << rela_type; |
| return false; |
| } |
| |
| return true; |
| } |
| #else |
| bool Relocations::ApplyResolvedReloc(const Rel* rel, Addr sym_addr) { |
| const Word rel_type = ELF_R_TYPE(rel->r_info); |
| const Addr reloc = static_cast<Addr>(rel->r_offset + base_memory_address_); |
| |
| SB_DLOG(INFO) << " rel reloc=0x" << std::hex << reloc << " offset=0x" |
| << rel->r_offset << " type=" << std::dec << rel_type; |
| |
| Addr* target = reinterpret_cast<Addr*>(reloc); |
| switch (rel_type) { |
| #if SB_IS(ARCH_ARM) |
| case R_ARM_JUMP_SLOT: |
| SB_DLOG(INFO) << " R_ARM_JUMP_SLOT target=" << std::hex << target |
| << " addr=" << sym_addr; |
| *target = sym_addr; |
| break; |
| |
| case R_ARM_GLOB_DAT: |
| SB_DLOG(INFO) << " R_ARM_GLOB_DAT target=" << std::hex << target |
| << " addr=" << sym_addr; |
| *target = sym_addr; |
| break; |
| |
| case R_ARM_ABS32: |
| SB_DLOG(INFO) << " R_ARM_ABS32 target=" << std::hex << target << " " |
| << *target << " addr=" << sym_addr; |
| *target += sym_addr; |
| break; |
| |
| case R_ARM_REL32: |
| SB_DLOG(INFO) << " R_ARM_REL32 target=" << std::hex << target << " " |
| << *target << " addr=" << sym_addr |
| << " offset=" << rel->r_offset; |
| *target += sym_addr - rel->r_offset; |
| break; |
| |
| case R_ARM_RELATIVE: |
| SB_DLOG(INFO) << " RR_ARM_RELATIVE target=" << std::hex << target << " " |
| << *target << " bias=" << base_memory_address_; |
| *target += base_memory_address_; |
| break; |
| #endif |
| |
| #if SB_IS(ARCH_X86) |
| case R_386_JMP_SLOT: |
| SB_DLOG(INFO) << " R_386_JMP_SLOT target=" << std::hex << target |
| << " addr=" << sym_addr; |
| |
| *target = sym_addr; |
| break; |
| |
| case R_386_GLOB_DAT: |
| SB_DLOG(INFO) << " R_386_GLOB_DAT target=" << std::hex << target |
| << " addr=" << sym_addr; |
| *target = sym_addr; |
| |
| break; |
| |
| case R_386_RELATIVE: |
| SB_DLOG(INFO) << " R_386_RELATIVE target=" << std::hex << target << " " |
| << *target << " bias=" << base_memory_address_; |
| |
| *target += base_memory_address_; |
| break; |
| |
| case R_386_32: |
| SB_DLOG(INFO) << " R_386_32 target=" << std::hex << target << " " |
| << *target << " addr=" << sym_addr; |
| *target += sym_addr; |
| break; |
| |
| case R_386_PC32: |
| SB_DLOG(INFO) << " R_386_PC32 target=" << std::hex << target << " " |
| << *target << " addr=" << sym_addr << " reloc=" << reloc; |
| *target += (sym_addr - reloc); |
| break; |
| #endif |
| |
| default: |
| SB_LOG(ERROR) << "Invalid relocation type: " << rel_type; |
| return false; |
| } |
| |
| return true; |
| } |
| #endif |
| |
| RelocationType Relocations::GetRelocationType(Word r_type) { |
| switch (r_type) { |
| #if SB_IS(ARCH_ARM) |
| case R_ARM_JUMP_SLOT: |
| case R_ARM_GLOB_DAT: |
| case R_ARM_ABS32: |
| return RELOCATION_TYPE_ABSOLUTE; |
| |
| case R_ARM_REL32: |
| case R_ARM_RELATIVE: |
| return RELOCATION_TYPE_RELATIVE; |
| |
| case R_ARM_COPY: |
| return RELOCATION_TYPE_COPY; |
| #endif |
| |
| #if SB_IS(ARCH_ARM64) |
| case R_AARCH64_JUMP_SLOT: |
| case R_AARCH64_GLOB_DAT: |
| case R_AARCH64_ABS64: |
| return RELOCATION_TYPE_ABSOLUTE; |
| |
| case R_AARCH64_RELATIVE: |
| return RELOCATION_TYPE_RELATIVE; |
| |
| case R_AARCH64_COPY: |
| return RELOCATION_TYPE_COPY; |
| #endif |
| |
| #if SB_IS(ARCH_X86) |
| case R_386_JMP_SLOT: |
| case R_386_GLOB_DAT: |
| case R_386_32: |
| return RELOCATION_TYPE_ABSOLUTE; |
| |
| case R_386_RELATIVE: |
| return RELOCATION_TYPE_RELATIVE; |
| |
| case R_386_PC32: |
| return RELOCATION_TYPE_PC_RELATIVE; |
| #endif |
| |
| #if SB_IS(ARCH_X64) |
| case R_X86_64_JMP_SLOT: |
| case R_X86_64_GLOB_DAT: |
| case R_X86_64_64: |
| return RELOCATION_TYPE_ABSOLUTE; |
| |
| case R_X86_64_RELATIVE: |
| return RELOCATION_TYPE_RELATIVE; |
| |
| case R_X86_64_PC32: |
| return RELOCATION_TYPE_PC_RELATIVE; |
| #endif |
| default: |
| return RELOCATION_TYPE_UNKNOWN; |
| } |
| } |
| |
| bool Relocations::ResolveSymbol(Word rel_type, |
| Word rel_symbol, |
| Addr reloc, |
| Addr* sym_addr) { |
| const char* sym_name = dynamic_section_->LookupNameById(rel_symbol); |
| SB_DLOG(INFO) << "Resolve: " << sym_name; |
| const void* address = NULL; |
| |
| const Sym* sym = dynamic_section_->LookupByName(sym_name); |
| if (sym) { |
| address = reinterpret_cast<void*>(base_memory_address_ + sym->st_value); |
| } else { |
| address = exported_symbols_->Lookup(sym_name); |
| } |
| |
| SB_DLOG(INFO) << "Resolve: address=0x" << std::hex << address; |
| |
| if (address) { |
| // The symbol was found, so compute its address. |
| *sym_addr = reinterpret_cast<Addr>(address); |
| return true; |
| } |
| |
| // The symbol was not found. Normally this is an error except |
| // if this is a weak reference. |
| if (!dynamic_section_->IsWeakById(rel_symbol)) { |
| SB_LOG(ERROR) << "Could not find symbol: " << sym_name; |
| return false; |
| } |
| |
| // IHI0044C AAELF 4.5.1.1: |
| // Libraries are not searched to resolve weak references. |
| // It is not an error for a weak reference to remain |
| // unsatisfied. |
| // |
| // During linking, the value of an undefined weak reference is: |
| // - Zero if the relocation type is absolute |
| // - The address of the place if the relocation is pc-relative |
| // - The address of nominal base address if the relocation |
| // type is base-relative. |
| RelocationType r = GetRelocationType(rel_type); |
| if (r == RELOCATION_TYPE_ABSOLUTE || r == RELOCATION_TYPE_RELATIVE) { |
| *sym_addr = 0; |
| return true; |
| } |
| |
| if (r == RELOCATION_TYPE_PC_RELATIVE) { |
| *sym_addr = reloc; |
| return true; |
| } |
| |
| SB_LOG(ERROR) << "Invalid weak relocation type (" << r |
| << ") for unknown symbol '" << sym_name << "'"; |
| return false; |
| } |
| } // namespace elf_loader |
| } // namespace starboard |
