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// ehframe.cc -- handle exception frame sections for gold // Copyright 2006, 2007, 2008 Free Software Foundation, Inc. // Written by Ian Lance Taylor <iant@google.com>. // This file is part of gold. // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3 of the License, or // (at your option) any later version. // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, // MA 02110-1301, USA. #include "gold.h" #include <cstring> #include <algorithm> #include "elfcpp.h" #include "dwarf.h" #include "symtab.h" #include "reloc.h" #include "ehframe.h" namespace gold { // This file handles generation of the exception frame header that // gcc's runtime support libraries use to find unwind information at // runtime. This file also handles discarding duplicate exception // frame information. // The exception frame header starts with four bytes: // 0: The version number, currently 1. // 1: The encoding of the pointer to the exception frames. This can // be any DWARF unwind encoding (DW_EH_PE_*). It is normally a 4 // byte PC relative offset (DW_EH_PE_pcrel | DW_EH_PE_sdata4). // 2: The encoding of the count of the number of FDE pointers in the // lookup table. This can be any DWARF unwind encoding, and in // particular can be DW_EH_PE_omit if the count is omitted. It is // normally a 4 byte unsigned count (DW_EH_PE_udata4). // 3: The encoding of the lookup table entries. Currently gcc's // libraries will only support DW_EH_PE_datarel | DW_EH_PE_sdata4, // which means that the values are 4 byte offsets from the start of // the table. // The exception frame header is followed by a pointer to the contents // of the exception frame section (.eh_frame). This pointer is // encoded as specified in the byte at offset 1 of the header (i.e., // it is normally a 4 byte PC relative offset). // If there is a lookup table, this is followed by the count of the // number of FDE pointers, encoded as specified in the byte at offset // 2 of the header (i.e., normally a 4 byte unsigned integer). // This is followed by the table, which should start at an 4-byte // aligned address in memory. Each entry in the table is 8 bytes. // Each entry represents an FDE. The first four bytes of each entry // are an offset to the starting PC for the FDE. The last four bytes // of each entry are an offset to the FDE data. The offsets are from // the start of the exception frame header information. The entries // are in sorted order by starting PC. const int eh_frame_hdr_size = 4; // Construct the exception frame header. Eh_frame_hdr::Eh_frame_hdr(Output_section* eh_frame_section, const Eh_frame* eh_frame_data) : Output_section_data(4), eh_frame_section_(eh_frame_section), eh_frame_data_(eh_frame_data), fde_offsets_(), any_unrecognized_eh_frame_sections_(false) { } // Set the size of the exception frame header. void Eh_frame_hdr::set_final_data_size() { unsigned int data_size = eh_frame_hdr_size + 4; if (!this->any_unrecognized_eh_frame_sections_) { unsigned int fde_count = this->eh_frame_data_->fde_count(); if (fde_count != 0) data_size += 4 + 8 * fde_count; this->fde_offsets_.reserve(fde_count); } this->set_data_size(data_size); } // Write the data to the flie. void Eh_frame_hdr::do_write(Output_file* of) { switch (parameters->size_and_endianness()) { #ifdef HAVE_TARGET_32_LITTLE case Parameters::TARGET_32_LITTLE: this->do_sized_write<32, false>(of); break; #endif #ifdef HAVE_TARGET_32_BIG case Parameters::TARGET_32_BIG: this->do_sized_write<32, true>(of); break; #endif #ifdef HAVE_TARGET_64_LITTLE case Parameters::TARGET_64_LITTLE: this->do_sized_write<64, false>(of); break; #endif #ifdef HAVE_TARGET_64_BIG case Parameters::TARGET_64_BIG: this->do_sized_write<64, true>(of); break; #endif default: gold_unreachable(); } } // Write the data to the file with the right endianness. template<int size, bool big_endian> void Eh_frame_hdr::do_sized_write(Output_file* of) { const off_t off = this->offset(); const off_t oview_size = this->data_size(); unsigned char* const oview = of->get_output_view(off, oview_size); // Version number. oview[0] = 1; // Write out a 4 byte PC relative offset to the address of the // .eh_frame section. oview[1] = elfcpp::DW_EH_PE_pcrel | elfcpp::DW_EH_PE_sdata4; uint64_t eh_frame_address = this->eh_frame_section_->address(); uint64_t eh_frame_hdr_address = this->address(); uint64_t eh_frame_offset = (eh_frame_address - (eh_frame_hdr_address + 4)); elfcpp::Swap<32, big_endian>::writeval(oview + 4, eh_frame_offset); if (this->any_unrecognized_eh_frame_sections_ || this->fde_offsets_.empty()) { // There are no FDEs, or we didn't recognize the format of the // some of the .eh_frame sections, so we can't write out the // sorted table. oview[2] = elfcpp::DW_EH_PE_omit; oview[3] = elfcpp::DW_EH_PE_omit; gold_assert(oview_size == 8); } else { oview[2] = elfcpp::DW_EH_PE_udata4; oview[3] = elfcpp::DW_EH_PE_datarel | elfcpp::DW_EH_PE_sdata4; elfcpp::Swap<32, big_endian>::writeval(oview + 8, this->fde_offsets_.size()); // We have the offsets of the FDEs in the .eh_frame section. We // couldn't easily get the PC values before, as they depend on // relocations which are, of course, target specific. This code // is run after all those relocations have been applied to the // output file. Here we read the output file again to find the // PC values. Then we sort the list and write it out. Fde_addresses<size> fde_addresses(this->fde_offsets_.size()); this->get_fde_addresses<size, big_endian>(of, &this->fde_offsets_, &fde_addresses); std::sort(fde_addresses.begin(), fde_addresses.end(), Fde_address_compare<size>()); typename elfcpp::Elf_types<size>::Elf_Addr output_address; output_address = this->address(); unsigned char* pfde = oview + 12; for (typename Fde_addresses<size>::iterator p = fde_addresses.begin(); p != fde_addresses.end(); ++p) { elfcpp::Swap<32, big_endian>::writeval(pfde, p->first - output_address); elfcpp::Swap<32, big_endian>::writeval(pfde + 4, p->second - output_address); pfde += 8; } gold_assert(pfde - oview == oview_size); } of->write_output_view(off, oview_size, oview); } // Given the offset FDE_OFFSET of an FDE in the .eh_frame section, and // the contents of the .eh_frame section EH_FRAME_CONTENTS, where the // FDE's encoding is FDE_ENCODING, return the output address of the // FDE's PC. template<int size, bool big_endian> typename elfcpp::Elf_types<size>::Elf_Addr Eh_frame_hdr::get_fde_pc( typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address, const unsigned char* eh_frame_contents, section_offset_type fde_offset, unsigned char fde_encoding) { // The FDE starts with a 4 byte length and a 4 byte offset to the // CIE. The PC follows. const unsigned char* p = eh_frame_contents + fde_offset + 8; typename elfcpp::Elf_types<size>::Elf_Addr pc; bool is_signed = (fde_encoding & elfcpp::DW_EH_PE_signed) != 0; int pc_size = fde_encoding & 7; if (pc_size == elfcpp::DW_EH_PE_absptr) { if (size == 32) pc_size = elfcpp::DW_EH_PE_udata4; else if (size == 64) pc_size = elfcpp::DW_EH_PE_udata8; else gold_unreachable(); } switch (pc_size) { case elfcpp::DW_EH_PE_udata2: pc = elfcpp::Swap<16, big_endian>::readval(p); if (is_signed) pc = (pc ^ 0x8000) - 0x8000; break; case elfcpp::DW_EH_PE_udata4: pc = elfcpp::Swap<32, big_endian>::readval(p); if (size > 32 && is_signed) pc = (pc ^ 0x80000000) - 0x80000000; break; case elfcpp::DW_EH_PE_udata8: gold_assert(size == 64); pc = elfcpp::Swap_unaligned<64, big_endian>::readval(p); break; default: // All other cases were rejected in Eh_frame::read_cie. gold_unreachable(); } switch (fde_encoding & 0xf0) { case 0: break; case elfcpp::DW_EH_PE_pcrel: pc += eh_frame_address + fde_offset + 8; break; default: // If other cases arise, then we have to handle them, or we have // to reject them by returning false in Eh_frame::read_cie. gold_unreachable(); } return pc; } // Given an array of FDE offsets in the .eh_frame section, return an // array of offsets from the exception frame header to the FDE's // output PC and to the output address of the FDE itself. We get the // FDE's PC by actually looking in the .eh_frame section we just wrote // to the output file. template<int size, bool big_endian> void Eh_frame_hdr::get_fde_addresses(Output_file* of, const Fde_offsets* fde_offsets, Fde_addresses<size>* fde_addresses) { typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address; eh_frame_address = this->eh_frame_section_->address(); off_t eh_frame_offset = this->eh_frame_section_->offset(); off_t eh_frame_size = this->eh_frame_section_->data_size(); const unsigned char* eh_frame_contents = of->get_input_view(eh_frame_offset, eh_frame_size); for (Fde_offsets::const_iterator p = fde_offsets->begin(); p != fde_offsets->end(); ++p) { typename elfcpp::Elf_types<size>::Elf_Addr fde_pc; fde_pc = this->get_fde_pc<size, big_endian>(eh_frame_address, eh_frame_contents, p->first, p->second); fde_addresses->push_back(fde_pc, eh_frame_address + p->first); } of->free_input_view(eh_frame_offset, eh_frame_size, eh_frame_contents); } // Class Fde. // Write the FDE to OVIEW starting at OFFSET. CIE_OFFSET is the // offset of the CIE in OVIEW. FDE_ENCODING is the encoding, from the // CIE. ADDRALIGN is the required alignment. Record the FDE pc for // EH_FRAME_HDR. Return the new offset. template<int size, bool big_endian> section_offset_type Fde::write(unsigned char* oview, section_offset_type offset, unsigned int addralign, section_offset_type cie_offset, unsigned char fde_encoding, Eh_frame_hdr* eh_frame_hdr) { gold_assert((offset & (addralign - 1)) == 0); size_t length = this->contents_.length(); // We add 8 when getting the aligned length to account for the // length word and the CIE offset. size_t aligned_full_length = align_address(length + 8, addralign); // Write the length of the FDE as a 32-bit word. The length word // does not include the four bytes of the length word itself, but it // does include the offset to the CIE. elfcpp::Swap<32, big_endian>::writeval(oview + offset, aligned_full_length - 4); // Write the offset to the CIE as a 32-bit word. This is the // difference between the address of the offset word itself and the // CIE address. elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, offset + 4 - cie_offset); // Copy the rest of the FDE. Note that this is run before // relocation processing is done on this section, so the relocations // will later be applied to the FDE data. memcpy(oview + offset + 8, this->contents_.data(), length); if (aligned_full_length > length + 8) memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8)); // Tell the exception frame header about this FDE. if (eh_frame_hdr != NULL) eh_frame_hdr->record_fde(offset, fde_encoding); return offset + aligned_full_length; } // Class Cie. // Destructor. Cie::~Cie() { for (std::vector<Fde*>::iterator p = this->fdes_.begin(); p != this->fdes_.end(); ++p) delete *p; } // Set the output offset of a CIE. Return the new output offset. section_offset_type Cie::set_output_offset(section_offset_type output_offset, unsigned int addralign, Merge_map* merge_map) { size_t length = this->contents_.length(); // Add 4 for length and 4 for zero CIE identifier tag. length += 8; merge_map->add_mapping(this->object_, this->shndx_, this->input_offset_, length, output_offset); length = align_address(length, addralign); for (std::vector<Fde*>::const_iterator p = this->fdes_.begin(); p != this->fdes_.end(); ++p) { (*p)->add_mapping(output_offset + length, merge_map); size_t fde_length = (*p)->length(); fde_length = align_address(fde_length, addralign); length += fde_length; } return output_offset + length; } // Write the CIE to OVIEW starting at OFFSET. EH_FRAME_HDR is for FDE // recording. Round up the bytes to ADDRALIGN. Return the new // offset. template<int size, bool big_endian> section_offset_type Cie::write(unsigned char* oview, section_offset_type offset, unsigned int addralign, Eh_frame_hdr* eh_frame_hdr) { gold_assert((offset & (addralign - 1)) == 0); section_offset_type cie_offset = offset; size_t length = this->contents_.length(); // We add 8 when getting the aligned length to account for the // length word and the CIE tag. size_t aligned_full_length = align_address(length + 8, addralign); // Write the length of the CIE as a 32-bit word. The length word // does not include the four bytes of the length word itself. elfcpp::Swap<32, big_endian>::writeval(oview + offset, aligned_full_length - 4); // Write the tag which marks this as a CIE: a 32-bit zero. elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, 0); // Write out the CIE data. memcpy(oview + offset + 8, this->contents_.data(), length); if (aligned_full_length > length + 8) memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8)); offset += aligned_full_length; // Write out the associated FDEs. unsigned char fde_encoding = this->fde_encoding_; for (std::vector<Fde*>::const_iterator p = this->fdes_.begin(); p != this->fdes_.end(); ++p) offset = (*p)->write<size, big_endian>(oview, offset, addralign, cie_offset, fde_encoding, eh_frame_hdr); return offset; } // We track all the CIEs we see, and merge them when possible. This // works because each FDE holds an offset to the relevant CIE: we // rewrite the FDEs to point to the merged CIE. This is worthwhile // because in a typical C++ program many FDEs in many different object // files will use the same CIE. // An equality operator for Cie. bool operator==(const Cie& cie1, const Cie& cie2) { return (cie1.personality_name_ == cie2.personality_name_ && cie1.contents_ == cie2.contents_); } // A less-than operator for Cie. bool operator<(const Cie& cie1, const Cie& cie2) { if (cie1.personality_name_ != cie2.personality_name_) return cie1.personality_name_ < cie2.personality_name_; return cie1.contents_ < cie2.contents_; } // Class Eh_frame. Eh_frame::Eh_frame() : Output_section_data(Output_data::default_alignment()), eh_frame_hdr_(NULL), cie_offsets_(), unmergeable_cie_offsets_(), merge_map_(), mappings_are_done_(false), final_data_size_(0) { } // Skip an LEB128, updating *PP to point to the next character. // Return false if we ran off the end of the string. bool Eh_frame::skip_leb128(const unsigned char** pp, const unsigned char* pend) { const unsigned char* p; for (p = *pp; p < pend; ++p) { if ((*p & 0x80) == 0) { *pp = p + 1; return true; } } return false; } // Add input section SHNDX in OBJECT to an exception frame section. // SYMBOLS is the contents of the symbol table section (size // SYMBOLS_SIZE), SYMBOL_NAMES is the symbol names section (size // SYMBOL_NAMES_SIZE). RELOC_SHNDX is the index of a relocation // section applying to SHNDX, or 0 if none, or -1U if more than one. // RELOC_TYPE is the type of the reloc section if there is one, either // SHT_REL or SHT_RELA. We try to parse the input exception frame // data into our data structures. If we can't do it, we return false // to mean that the section should be handled as a normal input // section. template<int size, bool big_endian> bool Eh_frame::add_ehframe_input_section( Sized_relobj<size, big_endian>* object, const unsigned char* symbols, section_size_type symbols_size, const unsigned char* symbol_names, section_size_type symbol_names_size, unsigned int shndx, unsigned int reloc_shndx, unsigned int reloc_type) { // Get the section contents. section_size_type contents_len; const unsigned char* pcontents = object->section_contents(shndx, &contents_len, false); if (contents_len == 0) return false; // If this is the marker section for the end of the data, then // return false to force it to be handled as an ordinary input // section. If we don't do this, we won't correctly handle the case // of unrecognized .eh_frame sections. if (contents_len == 4 && elfcpp::Swap<32, big_endian>::readval(pcontents) == 0) return false; New_cies new_cies; if (!this->do_add_ehframe_input_section(object, symbols, symbols_size, symbol_names, symbol_names_size, shndx, reloc_shndx, reloc_type, pcontents, contents_len, &new_cies)) { if (this->eh_frame_hdr_ != NULL) this->eh_frame_hdr_->found_unrecognized_eh_frame_section(); for (New_cies::iterator p = new_cies.begin(); p != new_cies.end(); ++p) delete p->first; return false; } // Now that we know we are using this section, record any new CIEs // that we found. for (New_cies::const_iterator p = new_cies.begin(); p != new_cies.end(); ++p) { if (p->second) this->cie_offsets_.insert(p->first); else this->unmergeable_cie_offsets_.push_back(p->first); } return true; } // The bulk of the implementation of add_ehframe_input_section. template<int size, bool big_endian> bool Eh_frame::do_add_ehframe_input_section( Sized_relobj<size, big_endian>* object, const unsigned char* symbols, section_size_type symbols_size, const unsigned char* symbol_names, section_size_type symbol_names_size, unsigned int shndx, unsigned int reloc_shndx, unsigned int reloc_type, const unsigned char* pcontents, section_size_type contents_len, New_cies* new_cies) { typedef typename elfcpp::Elf_types<size>::Elf_Addr Address; Track_relocs<size, big_endian> relocs; const unsigned char* p = pcontents; const unsigned char* pend = p + contents_len; // Get the contents of the reloc section if any. if (!relocs.initialize(object, reloc_shndx, reloc_type)) return false; // Keep track of which CIEs are at which offsets. Offsets_to_cie cies; while (p < pend) { if (pend - p < 4) return false; // There shouldn't be any relocations here. if (relocs.advance(p + 4 - pcontents) > 0) return false; unsigned int len = elfcpp::Swap<32, big_endian>::readval(p); p += 4; if (len == 0) { // We should only find a zero-length entry at the end of the // section. if (p < pend) return false; break; } // We don't support a 64-bit .eh_frame. if (len == 0xffffffff) return false; if (static_cast<unsigned int>(pend - p) < len) return false; const unsigned char* const pentend = p + len; if (pend - p < 4) return false; if (relocs.advance(p + 4 - pcontents) > 0) return false; unsigned int id = elfcpp::Swap<32, big_endian>::readval(p); p += 4; if (id == 0) { // CIE. if (!this->read_cie(object, shndx, symbols, symbols_size, symbol_names, symbol_names_size, pcontents, p, pentend, &relocs, &cies, new_cies)) return false; } else { // FDE. if (!this->read_fde(object, shndx, symbols, symbols_size, pcontents, id, p, pentend, &relocs, &cies)) return false; } p = pentend; } return true; } // Read a CIE. Return false if we can't parse the information. template<int size, bool big_endian> bool Eh_frame::read_cie(Sized_relobj<size, big_endian>* object, unsigned int shndx, const unsigned char* symbols, section_size_type symbols_size, const unsigned char* symbol_names, section_size_type symbol_names_size, const unsigned char* pcontents, const unsigned char* pcie, const unsigned char *pcieend, Track_relocs<size, big_endian>* relocs, Offsets_to_cie* cies, New_cies* new_cies) { bool mergeable = true; // We need to find the personality routine if there is one, since we // can only merge CIEs which use the same routine. We also need to // find the FDE encoding if there is one, so that we can read the PC // from the FDE. const unsigned char* p = pcie; if (pcieend - p < 1) return false; unsigned char version = *p++; if (version != 1 && version != 3) return false; const unsigned char* paug = p; const void* paugendv = memchr(p, '\0', pcieend - p); const unsigned char* paugend = static_cast<const unsigned char*>(paugendv); if (paugend == NULL) return false; p = paugend + 1; if (paug[0] == 'e' && paug[1] == 'h') { // This is a CIE from gcc before version 3.0. We can't merge // these. We can still read the FDEs. mergeable = false; paug += 2; if (*paug != '\0') return false; if (pcieend - p < size / 8) return false; p += size / 8; } // Skip the code alignment. if (!skip_leb128(&p, pcieend)) return false; // Skip the data alignment. if (!skip_leb128(&p, pcieend)) return false; // Skip the return column. if (version == 1) { if (pcieend - p < 1) return false; ++p; } else { if (!skip_leb128(&p, pcieend)) return false; } if (*paug == 'z') { ++paug; // Skip the augmentation size. if (!skip_leb128(&p, pcieend)) return false; } unsigned char fde_encoding = elfcpp::DW_EH_PE_absptr; int per_offset = -1; while (*paug != '\0') { switch (*paug) { case 'L': // LSDA encoding. if (pcieend - p < 1) return false; ++p; break; case 'R': // FDE encoding. if (pcieend - p < 1) return false; fde_encoding = *p; switch (fde_encoding & 7) { case elfcpp::DW_EH_PE_absptr: case elfcpp::DW_EH_PE_udata2: case elfcpp::DW_EH_PE_udata4: case elfcpp::DW_EH_PE_udata8: break; default: // We don't expect to see any other cases here, and // we're not prepared to handle them. return false; } ++p; break; case 'S': break; case 'P': // Personality encoding. { if (pcieend - p < 1) return false; unsigned char per_encoding = *p; ++p; if ((per_encoding & 0x60) == 0x60) return false; unsigned int per_width; switch (per_encoding & 7) { case elfcpp::DW_EH_PE_udata2: per_width = 2; break; case elfcpp::DW_EH_PE_udata4: per_width = 4; break; case elfcpp::DW_EH_PE_udata8: per_width = 8; break; case elfcpp::DW_EH_PE_absptr: per_width = size / 8; break; default: return false; } if ((per_encoding & 0xf0) == elfcpp::DW_EH_PE_aligned) { unsigned int len = p - pcie; len += per_width - 1; len &= ~ (per_width - 1); if (static_cast<unsigned int>(pcieend - p) < len) return false; p += len; } per_offset = p - pcontents; if (static_cast<unsigned int>(pcieend - p) < per_width) return false; p += per_width; } break; default: return false; } ++paug; } const char* personality_name = ""; if (per_offset != -1) { if (relocs->advance(per_offset) > 0) return false; if (relocs->next_offset() != per_offset) return false; unsigned int personality_symndx = relocs->next_symndx(); if (personality_symndx == -1U) return false; if (personality_symndx < object->local_symbol_count()) { // We can only merge this CIE if the personality routine is // a global symbol. We can still read the FDEs. mergeable = false; } else { const int sym_size = elfcpp::Elf_sizes<size>::sym_size; if (personality_symndx >= symbols_size / sym_size) return false; elfcpp::Sym<size, big_endian> sym(symbols + (personality_symndx * sym_size)); unsigned int name_offset = sym.get_st_name(); if (name_offset >= symbol_names_size) return false; personality_name = (reinterpret_cast<const char*>(symbol_names) + name_offset); } int r = relocs->advance(per_offset + 1); gold_assert(r == 1); } if (relocs->advance(pcieend - pcontents) > 0) return false; Cie cie(object, shndx, (pcie - 8) - pcontents, fde_encoding, personality_name, pcie, pcieend - pcie); Cie* cie_pointer = NULL; if (mergeable) { Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie); if (find_cie != this->cie_offsets_.end()) cie_pointer = *find_cie; else { // See if we already saw this CIE in this object file. for (New_cies::const_iterator pc = new_cies->begin(); pc != new_cies->end(); ++pc) { if (*(pc->first) == cie) { cie_pointer = pc->first; break; } } } } if (cie_pointer == NULL) { cie_pointer = new Cie(cie); new_cies->push_back(std::make_pair(cie_pointer, mergeable)); } else { // We are deleting this CIE. Record that in our mapping from // input sections to the output section. At this point we don't // know for sure that we are doing a special mapping for this // input section, but that's OK--if we don't do a special // mapping, nobody will ever ask for the mapping we add here. this->merge_map_.add_mapping(object, shndx, (pcie - 8) - pcontents, pcieend - (pcie - 8), -1); } // Record this CIE plus the offset in the input section. cies->insert(std::make_pair(pcie - pcontents, cie_pointer)); return true; } // Read an FDE. Return false if we can't parse the information. template<int size, bool big_endian> bool Eh_frame::read_fde(Sized_relobj<size, big_endian>* object, unsigned int shndx, const unsigned char* symbols, section_size_type symbols_size, const unsigned char* pcontents, unsigned int offset, const unsigned char* pfde, const unsigned char *pfdeend, Track_relocs<size, big_endian>* relocs, Offsets_to_cie* cies) { // OFFSET is the distance between the 4 bytes before PFDE to the // start of the CIE. The offset we recorded for the CIE is 8 bytes // after the start of the CIE--after the length and the zero tag. unsigned int cie_offset = (pfde - 4 - pcontents) - offset + 8; Offsets_to_cie::const_iterator pcie = cies->find(cie_offset); if (pcie == cies->end()) return false; Cie* cie = pcie->second; // The FDE should start with a reloc to the start of the code which // it describes. if (relocs->advance(pfde - pcontents) > 0) return false; if (relocs->next_offset() != pfde - pcontents) return false; unsigned int symndx = relocs->next_symndx(); if (symndx == -1U) return false; // There can be another reloc in the FDE, if the CIE specifies an // LSDA (language specific data area). We currently don't care. We // will care later if we want to optimize the LSDA from an absolute // pointer to a PC relative offset when generating a shared library. relocs->advance(pfdeend - pcontents); unsigned int fde_shndx; const int sym_size = elfcpp::Elf_sizes<size>::sym_size; if (symndx >= symbols_size / sym_size) return false; elfcpp::Sym<size, big_endian> sym(symbols + symndx * sym_size); bool is_ordinary; fde_shndx = object->adjust_sym_shndx(symndx, sym.get_st_shndx(), &is_ordinary); if (is_ordinary && fde_shndx != elfcpp::SHN_UNDEF && fde_shndx < object->shnum() && !object->is_section_included(fde_shndx)) { // This FDE applies to a section which we are discarding. We // can discard this FDE. this->merge_map_.add_mapping(object, shndx, (pfde - 8) - pcontents, pfdeend - (pfde - 8), -1); return true; } cie->add_fde(new Fde(object, shndx, (pfde - 8) - pcontents, pfde, pfdeend - pfde)); return true; } // Return the number of FDEs. unsigned int Eh_frame::fde_count() const { unsigned int ret = 0; for (Unmergeable_cie_offsets::const_iterator p = this->unmergeable_cie_offsets_.begin(); p != this->unmergeable_cie_offsets_.end(); ++p) ret += (*p)->fde_count(); for (Cie_offsets::const_iterator p = this->cie_offsets_.begin(); p != this->cie_offsets_.end(); ++p) ret += (*p)->fde_count(); return ret; } // Set the final data size. void Eh_frame::set_final_data_size() { // We can be called more than once if Layout::set_segment_offsets // finds a better mapping. We don't want to add all the mappings // again. if (this->mappings_are_done_) { this->set_data_size(this->final_data_size_); return; } section_offset_type output_offset = 0; for (Unmergeable_cie_offsets::iterator p = this->unmergeable_cie_offsets_.begin(); p != this->unmergeable_cie_offsets_.end(); ++p) output_offset = (*p)->set_output_offset(output_offset, this->addralign(), &this->merge_map_); for (Cie_offsets::iterator p = this->cie_offsets_.begin(); p != this->cie_offsets_.end(); ++p) output_offset = (*p)->set_output_offset(output_offset, this->addralign(), &this->merge_map_); this->mappings_are_done_ = true; this->final_data_size_ = output_offset; gold_assert((output_offset & (this->addralign() - 1)) == 0); this->set_data_size(output_offset); } // Return an output offset for an input offset. bool Eh_frame::do_output_offset(const Relobj* object, unsigned int shndx, section_offset_type offset, section_offset_type* poutput) const { return this->merge_map_.get_output_offset(object, shndx, offset, poutput); } // Return whether this is the merge section for an input section. bool Eh_frame::do_is_merge_section_for(const Relobj* object, unsigned int shndx) const { return this->merge_map_.is_merge_section_for(object, shndx); } // Write the data to the output file. void Eh_frame::do_write(Output_file* of) { const off_t offset = this->offset(); const off_t oview_size = this->data_size(); unsigned char* const oview = of->get_output_view(offset, oview_size); switch (parameters->size_and_endianness()) { #ifdef HAVE_TARGET_32_LITTLE case Parameters::TARGET_32_LITTLE: this->do_sized_write<32, false>(oview); break; #endif #ifdef HAVE_TARGET_32_BIG case Parameters::TARGET_32_BIG: this->do_sized_write<32, true>(oview); break; #endif #ifdef HAVE_TARGET_64_LITTLE case Parameters::TARGET_64_LITTLE: this->do_sized_write<64, false>(oview); break; #endif #ifdef HAVE_TARGET_64_BIG case Parameters::TARGET_64_BIG: this->do_sized_write<64, true>(oview); break; #endif default: gold_unreachable(); } of->write_output_view(offset, oview_size, oview); } // Write the data to the output file--template version. template<int size, bool big_endian> void Eh_frame::do_sized_write(unsigned char* oview) { unsigned int addralign = this->addralign(); section_offset_type o = 0; for (Unmergeable_cie_offsets::iterator p = this->unmergeable_cie_offsets_.begin(); p != this->unmergeable_cie_offsets_.end(); ++p) o = (*p)->write<size, big_endian>(oview, o, addralign, this->eh_frame_hdr_); for (Cie_offsets::iterator p = this->cie_offsets_.begin(); p != this->cie_offsets_.end(); ++p) o = (*p)->write<size, big_endian>(oview, o, addralign, this->eh_frame_hdr_); } #ifdef HAVE_TARGET_32_LITTLE template bool Eh_frame::add_ehframe_input_section<32, false>( Sized_relobj<32, false>* object, const unsigned char* symbols, section_size_type symbols_size, const unsigned char* symbol_names, section_size_type symbol_names_size, unsigned int shndx, unsigned int reloc_shndx, unsigned int reloc_type); #endif #ifdef HAVE_TARGET_32_BIG template bool Eh_frame::add_ehframe_input_section<32, true>( Sized_relobj<32, true>* object, const unsigned char* symbols, section_size_type symbols_size, const unsigned char* symbol_names, section_size_type symbol_names_size, unsigned int shndx, unsigned int reloc_shndx, unsigned int reloc_type); #endif #ifdef HAVE_TARGET_64_LITTLE template bool Eh_frame::add_ehframe_input_section<64, false>( Sized_relobj<64, false>* object, const unsigned char* symbols, section_size_type symbols_size, const unsigned char* symbol_names, section_size_type symbol_names_size, unsigned int shndx, unsigned int reloc_shndx, unsigned int reloc_type); #endif #ifdef HAVE_TARGET_64_BIG template bool Eh_frame::add_ehframe_input_section<64, true>( Sized_relobj<64, true>* object, const unsigned char* symbols, section_size_type symbols_size, const unsigned char* symbol_names, section_size_type symbol_names_size, unsigned int shndx, unsigned int reloc_shndx, unsigned int reloc_type); #endif } // End namespace gold.
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