1 // ehframe.cc -- handle exception frame sections for gold
3 // Copyright 2006, 2007, 2008, 2010, 2011 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
37 // This file handles generation of the exception frame header that
38 // gcc's runtime support libraries use to find unwind information at
39 // runtime. This file also handles discarding duplicate exception
42 // The exception frame header starts with four bytes:
44 // 0: The version number, currently 1.
46 // 1: The encoding of the pointer to the exception frames. This can
47 // be any DWARF unwind encoding (DW_EH_PE_*). It is normally a 4
48 // byte PC relative offset (DW_EH_PE_pcrel | DW_EH_PE_sdata4).
50 // 2: The encoding of the count of the number of FDE pointers in the
51 // lookup table. This can be any DWARF unwind encoding, and in
52 // particular can be DW_EH_PE_omit if the count is omitted. It is
53 // normally a 4 byte unsigned count (DW_EH_PE_udata4).
55 // 3: The encoding of the lookup table entries. Currently gcc's
56 // libraries will only support DW_EH_PE_datarel | DW_EH_PE_sdata4,
57 // which means that the values are 4 byte offsets from the start of
60 // The exception frame header is followed by a pointer to the contents
61 // of the exception frame section (.eh_frame). This pointer is
62 // encoded as specified in the byte at offset 1 of the header (i.e.,
63 // it is normally a 4 byte PC relative offset).
65 // If there is a lookup table, this is followed by the count of the
66 // number of FDE pointers, encoded as specified in the byte at offset
67 // 2 of the header (i.e., normally a 4 byte unsigned integer).
69 // This is followed by the table, which should start at an 4-byte
70 // aligned address in memory. Each entry in the table is 8 bytes.
71 // Each entry represents an FDE. The first four bytes of each entry
72 // are an offset to the starting PC for the FDE. The last four bytes
73 // of each entry are an offset to the FDE data. The offsets are from
74 // the start of the exception frame header information. The entries
75 // are in sorted order by starting PC.
77 const int eh_frame_hdr_size = 4;
79 // Construct the exception frame header.
81 Eh_frame_hdr::Eh_frame_hdr(Output_section* eh_frame_section,
82 const Eh_frame* eh_frame_data)
83 : Output_section_data(4),
84 eh_frame_section_(eh_frame_section),
85 eh_frame_data_(eh_frame_data),
87 any_unrecognized_eh_frame_sections_(false)
91 // Set the size of the exception frame header.
94 Eh_frame_hdr::set_final_data_size()
96 unsigned int data_size = eh_frame_hdr_size + 4;
97 if (!this->any_unrecognized_eh_frame_sections_)
99 unsigned int fde_count = this->eh_frame_data_->fde_count();
101 data_size += 4 + 8 * fde_count;
102 this->fde_offsets_.reserve(fde_count);
104 this->set_data_size(data_size);
107 // Write the data to the file.
110 Eh_frame_hdr::do_write(Output_file* of)
112 switch (parameters->size_and_endianness())
114 #ifdef HAVE_TARGET_32_LITTLE
115 case Parameters::TARGET_32_LITTLE:
116 this->do_sized_write<32, false>(of);
119 #ifdef HAVE_TARGET_32_BIG
120 case Parameters::TARGET_32_BIG:
121 this->do_sized_write<32, true>(of);
124 #ifdef HAVE_TARGET_64_LITTLE
125 case Parameters::TARGET_64_LITTLE:
126 this->do_sized_write<64, false>(of);
129 #ifdef HAVE_TARGET_64_BIG
130 case Parameters::TARGET_64_BIG:
131 this->do_sized_write<64, true>(of);
139 // Write the data to the file with the right endianness.
141 template<int size, bool big_endian>
143 Eh_frame_hdr::do_sized_write(Output_file* of)
145 const off_t off = this->offset();
146 const off_t oview_size = this->data_size();
147 unsigned char* const oview = of->get_output_view(off, oview_size);
152 // Write out a 4 byte PC relative offset to the address of the
153 // .eh_frame section.
154 oview[1] = elfcpp::DW_EH_PE_pcrel | elfcpp::DW_EH_PE_sdata4;
155 uint64_t eh_frame_address = this->eh_frame_section_->address();
156 uint64_t eh_frame_hdr_address = this->address();
157 uint64_t eh_frame_offset = (eh_frame_address -
158 (eh_frame_hdr_address + 4));
159 elfcpp::Swap<32, big_endian>::writeval(oview + 4, eh_frame_offset);
161 if (this->any_unrecognized_eh_frame_sections_
162 || this->fde_offsets_.empty())
164 // There are no FDEs, or we didn't recognize the format of the
165 // some of the .eh_frame sections, so we can't write out the
167 oview[2] = elfcpp::DW_EH_PE_omit;
168 oview[3] = elfcpp::DW_EH_PE_omit;
170 gold_assert(oview_size == 8);
174 oview[2] = elfcpp::DW_EH_PE_udata4;
175 oview[3] = elfcpp::DW_EH_PE_datarel | elfcpp::DW_EH_PE_sdata4;
177 elfcpp::Swap<32, big_endian>::writeval(oview + 8,
178 this->fde_offsets_.size());
180 // We have the offsets of the FDEs in the .eh_frame section. We
181 // couldn't easily get the PC values before, as they depend on
182 // relocations which are, of course, target specific. This code
183 // is run after all those relocations have been applied to the
184 // output file. Here we read the output file again to find the
185 // PC values. Then we sort the list and write it out.
187 Fde_addresses<size> fde_addresses(this->fde_offsets_.size());
188 this->get_fde_addresses<size, big_endian>(of, &this->fde_offsets_,
191 std::sort(fde_addresses.begin(), fde_addresses.end(),
192 Fde_address_compare<size>());
194 typename elfcpp::Elf_types<size>::Elf_Addr output_address;
195 output_address = this->address();
197 unsigned char* pfde = oview + 12;
198 for (typename Fde_addresses<size>::iterator p = fde_addresses.begin();
199 p != fde_addresses.end();
202 elfcpp::Swap<32, big_endian>::writeval(pfde,
203 p->first - output_address);
204 elfcpp::Swap<32, big_endian>::writeval(pfde + 4,
205 p->second - output_address);
209 gold_assert(pfde - oview == oview_size);
212 of->write_output_view(off, oview_size, oview);
215 // Given the offset FDE_OFFSET of an FDE in the .eh_frame section, and
216 // the contents of the .eh_frame section EH_FRAME_CONTENTS, where the
217 // FDE's encoding is FDE_ENCODING, return the output address of the
220 template<int size, bool big_endian>
221 typename elfcpp::Elf_types<size>::Elf_Addr
222 Eh_frame_hdr::get_fde_pc(
223 typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address,
224 const unsigned char* eh_frame_contents,
225 section_offset_type fde_offset,
226 unsigned char fde_encoding)
228 // The FDE starts with a 4 byte length and a 4 byte offset to the
229 // CIE. The PC follows.
230 const unsigned char* p = eh_frame_contents + fde_offset + 8;
232 typename elfcpp::Elf_types<size>::Elf_Addr pc;
233 bool is_signed = (fde_encoding & elfcpp::DW_EH_PE_signed) != 0;
234 int pc_size = fde_encoding & 7;
235 if (pc_size == elfcpp::DW_EH_PE_absptr)
238 pc_size = elfcpp::DW_EH_PE_udata4;
240 pc_size = elfcpp::DW_EH_PE_udata8;
247 case elfcpp::DW_EH_PE_udata2:
248 pc = elfcpp::Swap<16, big_endian>::readval(p);
250 pc = (pc ^ 0x8000) - 0x8000;
253 case elfcpp::DW_EH_PE_udata4:
254 pc = elfcpp::Swap<32, big_endian>::readval(p);
255 if (size > 32 && is_signed)
256 pc = (pc ^ 0x80000000) - 0x80000000;
259 case elfcpp::DW_EH_PE_udata8:
260 gold_assert(size == 64);
261 pc = elfcpp::Swap_unaligned<64, big_endian>::readval(p);
265 // All other cases were rejected in Eh_frame::read_cie.
269 switch (fde_encoding & 0xf0)
274 case elfcpp::DW_EH_PE_pcrel:
275 pc += eh_frame_address + fde_offset + 8;
279 // If other cases arise, then we have to handle them, or we have
280 // to reject them by returning false in Eh_frame::read_cie.
287 // Given an array of FDE offsets in the .eh_frame section, return an
288 // array of offsets from the exception frame header to the FDE's
289 // output PC and to the output address of the FDE itself. We get the
290 // FDE's PC by actually looking in the .eh_frame section we just wrote
291 // to the output file.
293 template<int size, bool big_endian>
295 Eh_frame_hdr::get_fde_addresses(Output_file* of,
296 const Fde_offsets* fde_offsets,
297 Fde_addresses<size>* fde_addresses)
299 typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address;
300 eh_frame_address = this->eh_frame_section_->address();
301 off_t eh_frame_offset = this->eh_frame_section_->offset();
302 off_t eh_frame_size = this->eh_frame_section_->data_size();
303 const unsigned char* eh_frame_contents = of->get_input_view(eh_frame_offset,
306 for (Fde_offsets::const_iterator p = fde_offsets->begin();
307 p != fde_offsets->end();
310 typename elfcpp::Elf_types<size>::Elf_Addr fde_pc;
311 fde_pc = this->get_fde_pc<size, big_endian>(eh_frame_address,
313 p->first, p->second);
314 fde_addresses->push_back(fde_pc, eh_frame_address + p->first);
317 of->free_input_view(eh_frame_offset, eh_frame_size, eh_frame_contents);
322 // Write the FDE to OVIEW starting at OFFSET. CIE_OFFSET is the
323 // offset of the CIE in OVIEW. FDE_ENCODING is the encoding, from the
324 // CIE. ADDRALIGN is the required alignment. ADDRESS is the virtual
325 // address of OVIEW. Record the FDE pc for EH_FRAME_HDR. Return the
328 template<int size, bool big_endian>
330 Fde::write(unsigned char* oview, section_offset_type offset,
331 uint64_t address, unsigned int addralign,
332 section_offset_type cie_offset, unsigned char fde_encoding,
333 Eh_frame_hdr* eh_frame_hdr)
335 gold_assert((offset & (addralign - 1)) == 0);
337 size_t length = this->contents_.length();
339 // We add 8 when getting the aligned length to account for the
340 // length word and the CIE offset.
341 size_t aligned_full_length = align_address(length + 8, addralign);
343 // Write the length of the FDE as a 32-bit word. The length word
344 // does not include the four bytes of the length word itself, but it
345 // does include the offset to the CIE.
346 elfcpp::Swap<32, big_endian>::writeval(oview + offset,
347 aligned_full_length - 4);
349 // Write the offset to the CIE as a 32-bit word. This is the
350 // difference between the address of the offset word itself and the
352 elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4,
353 offset + 4 - cie_offset);
355 // Copy the rest of the FDE. Note that this is run before
356 // relocation processing is done on this section, so the relocations
357 // will later be applied to the FDE data.
358 memcpy(oview + offset + 8, this->contents_.data(), length);
360 // If this FDE is associated with a PLT, fill in the PLT's address
362 if (this->object_ == NULL)
364 gold_assert(memcmp(oview + offset + 8, "\0\0\0\0\0\0\0\0", 8) == 0);
365 Output_data* plt = this->u_.from_linker.plt;
366 uint64_t poffset = plt->address() - (address + offset + 8);
367 int32_t spoffset = static_cast<int32_t>(poffset);
368 off_t psize = plt->data_size();
369 uint32_t upsize = static_cast<uint32_t>(psize);
370 if (static_cast<uint64_t>(static_cast<int64_t>(spoffset)) != poffset
371 || static_cast<off_t>(upsize) != psize)
372 gold_warning(_("overflow in PLT unwind data; "
373 "unwinding through PLT may fail"));
374 elfcpp::Swap<32, big_endian>::writeval(oview + offset + 8, spoffset);
375 elfcpp::Swap<32, big_endian>::writeval(oview + offset + 12, upsize);
378 if (aligned_full_length > length + 8)
379 memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8));
381 // Tell the exception frame header about this FDE.
382 if (eh_frame_hdr != NULL)
383 eh_frame_hdr->record_fde(offset, fde_encoding);
385 return offset + aligned_full_length;
394 for (std::vector<Fde*>::iterator p = this->fdes_.begin();
395 p != this->fdes_.end();
400 // Set the output offset of a CIE. Return the new output offset.
403 Cie::set_output_offset(section_offset_type output_offset,
404 unsigned int addralign,
405 Merge_map* merge_map)
407 size_t length = this->contents_.length();
409 // Add 4 for length and 4 for zero CIE identifier tag.
412 if (this->object_ != NULL)
414 // Add a mapping so that relocations are applied correctly.
415 merge_map->add_mapping(this->object_, this->shndx_, this->input_offset_,
416 length, output_offset);
419 length = align_address(length, addralign);
421 for (std::vector<Fde*>::const_iterator p = this->fdes_.begin();
422 p != this->fdes_.end();
425 (*p)->add_mapping(output_offset + length, merge_map);
427 size_t fde_length = (*p)->length();
428 fde_length = align_address(fde_length, addralign);
429 length += fde_length;
432 return output_offset + length;
435 // Write the CIE to OVIEW starting at OFFSET. EH_FRAME_HDR is for FDE
436 // recording. Round up the bytes to ADDRALIGN. Return the new
439 template<int size, bool big_endian>
441 Cie::write(unsigned char* oview, section_offset_type offset,
442 uint64_t address, unsigned int addralign,
443 Eh_frame_hdr* eh_frame_hdr)
445 gold_assert((offset & (addralign - 1)) == 0);
447 section_offset_type cie_offset = offset;
449 size_t length = this->contents_.length();
451 // We add 8 when getting the aligned length to account for the
452 // length word and the CIE tag.
453 size_t aligned_full_length = align_address(length + 8, addralign);
455 // Write the length of the CIE as a 32-bit word. The length word
456 // does not include the four bytes of the length word itself.
457 elfcpp::Swap<32, big_endian>::writeval(oview + offset,
458 aligned_full_length - 4);
460 // Write the tag which marks this as a CIE: a 32-bit zero.
461 elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, 0);
463 // Write out the CIE data.
464 memcpy(oview + offset + 8, this->contents_.data(), length);
466 if (aligned_full_length > length + 8)
467 memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8));
469 offset += aligned_full_length;
471 // Write out the associated FDEs.
472 unsigned char fde_encoding = this->fde_encoding_;
473 for (std::vector<Fde*>::const_iterator p = this->fdes_.begin();
474 p != this->fdes_.end();
476 offset = (*p)->write<size, big_endian>(oview, offset, address, addralign,
477 cie_offset, fde_encoding,
483 // We track all the CIEs we see, and merge them when possible. This
484 // works because each FDE holds an offset to the relevant CIE: we
485 // rewrite the FDEs to point to the merged CIE. This is worthwhile
486 // because in a typical C++ program many FDEs in many different object
487 // files will use the same CIE.
489 // An equality operator for Cie.
492 operator==(const Cie& cie1, const Cie& cie2)
494 return (cie1.personality_name_ == cie2.personality_name_
495 && cie1.contents_ == cie2.contents_);
498 // A less-than operator for Cie.
501 operator<(const Cie& cie1, const Cie& cie2)
503 if (cie1.personality_name_ != cie2.personality_name_)
504 return cie1.personality_name_ < cie2.personality_name_;
505 return cie1.contents_ < cie2.contents_;
511 : Output_section_data(Output_data::default_alignment()),
514 unmergeable_cie_offsets_(),
516 mappings_are_done_(false),
521 // Skip an LEB128, updating *PP to point to the next character.
522 // Return false if we ran off the end of the string.
525 Eh_frame::skip_leb128(const unsigned char** pp, const unsigned char* pend)
527 const unsigned char* p;
528 for (p = *pp; p < pend; ++p)
530 if ((*p & 0x80) == 0)
539 // Add input section SHNDX in OBJECT to an exception frame section.
540 // SYMBOLS is the contents of the symbol table section (size
541 // SYMBOLS_SIZE), SYMBOL_NAMES is the symbol names section (size
542 // SYMBOL_NAMES_SIZE). RELOC_SHNDX is the index of a relocation
543 // section applying to SHNDX, or 0 if none, or -1U if more than one.
544 // RELOC_TYPE is the type of the reloc section if there is one, either
545 // SHT_REL or SHT_RELA. We try to parse the input exception frame
546 // data into our data structures. If we can't do it, we return false
547 // to mean that the section should be handled as a normal input
550 template<int size, bool big_endian>
552 Eh_frame::add_ehframe_input_section(
553 Sized_relobj_file<size, big_endian>* object,
554 const unsigned char* symbols,
555 section_size_type symbols_size,
556 const unsigned char* symbol_names,
557 section_size_type symbol_names_size,
559 unsigned int reloc_shndx,
560 unsigned int reloc_type)
562 // Get the section contents.
563 section_size_type contents_len;
564 const unsigned char* pcontents = object->section_contents(shndx,
567 if (contents_len == 0)
570 // If this is the marker section for the end of the data, then
571 // return false to force it to be handled as an ordinary input
572 // section. If we don't do this, we won't correctly handle the case
573 // of unrecognized .eh_frame sections.
574 if (contents_len == 4
575 && elfcpp::Swap<32, big_endian>::readval(pcontents) == 0)
579 if (!this->do_add_ehframe_input_section(object, symbols, symbols_size,
580 symbol_names, symbol_names_size,
582 reloc_type, pcontents,
583 contents_len, &new_cies))
585 if (this->eh_frame_hdr_ != NULL)
586 this->eh_frame_hdr_->found_unrecognized_eh_frame_section();
588 for (New_cies::iterator p = new_cies.begin();
596 // Now that we know we are using this section, record any new CIEs
598 for (New_cies::const_iterator p = new_cies.begin();
603 this->cie_offsets_.insert(p->first);
605 this->unmergeable_cie_offsets_.push_back(p->first);
611 // The bulk of the implementation of add_ehframe_input_section.
613 template<int size, bool big_endian>
615 Eh_frame::do_add_ehframe_input_section(
616 Sized_relobj_file<size, big_endian>* object,
617 const unsigned char* symbols,
618 section_size_type symbols_size,
619 const unsigned char* symbol_names,
620 section_size_type symbol_names_size,
622 unsigned int reloc_shndx,
623 unsigned int reloc_type,
624 const unsigned char* pcontents,
625 section_size_type contents_len,
628 typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
629 Track_relocs<size, big_endian> relocs;
631 const unsigned char* p = pcontents;
632 const unsigned char* pend = p + contents_len;
634 // Get the contents of the reloc section if any.
635 if (!relocs.initialize(object, reloc_shndx, reloc_type))
638 // Keep track of which CIEs are at which offsets.
646 // There shouldn't be any relocations here.
647 if (relocs.advance(p + 4 - pcontents) > 0)
650 unsigned int len = elfcpp::Swap<32, big_endian>::readval(p);
654 // We should only find a zero-length entry at the end of the
660 // We don't support a 64-bit .eh_frame.
661 if (len == 0xffffffff)
663 if (static_cast<unsigned int>(pend - p) < len)
666 const unsigned char* const pentend = p + len;
670 if (relocs.advance(p + 4 - pcontents) > 0)
673 unsigned int id = elfcpp::Swap<32, big_endian>::readval(p);
679 if (!this->read_cie(object, shndx, symbols, symbols_size,
680 symbol_names, symbol_names_size,
681 pcontents, p, pentend, &relocs, &cies,
688 if (!this->read_fde(object, shndx, symbols, symbols_size,
689 pcontents, id, p, pentend, &relocs, &cies))
699 // Read a CIE. Return false if we can't parse the information.
701 template<int size, bool big_endian>
703 Eh_frame::read_cie(Sized_relobj_file<size, big_endian>* object,
705 const unsigned char* symbols,
706 section_size_type symbols_size,
707 const unsigned char* symbol_names,
708 section_size_type symbol_names_size,
709 const unsigned char* pcontents,
710 const unsigned char* pcie,
711 const unsigned char* pcieend,
712 Track_relocs<size, big_endian>* relocs,
713 Offsets_to_cie* cies,
716 bool mergeable = true;
718 // We need to find the personality routine if there is one, since we
719 // can only merge CIEs which use the same routine. We also need to
720 // find the FDE encoding if there is one, so that we can read the PC
723 const unsigned char* p = pcie;
727 unsigned char version = *p++;
728 if (version != 1 && version != 3)
731 const unsigned char* paug = p;
732 const void* paugendv = memchr(p, '\0', pcieend - p);
733 const unsigned char* paugend = static_cast<const unsigned char*>(paugendv);
738 if (paug[0] == 'e' && paug[1] == 'h')
740 // This is a CIE from gcc before version 3.0. We can't merge
741 // these. We can still read the FDEs.
746 if (pcieend - p < size / 8)
751 // Skip the code alignment.
752 if (!skip_leb128(&p, pcieend))
755 // Skip the data alignment.
756 if (!skip_leb128(&p, pcieend))
759 // Skip the return column.
768 if (!skip_leb128(&p, pcieend))
775 // Skip the augmentation size.
776 if (!skip_leb128(&p, pcieend))
780 unsigned char fde_encoding = elfcpp::DW_EH_PE_absptr;
782 while (*paug != '\0')
786 case 'L': // LSDA encoding.
792 case 'R': // FDE encoding.
796 switch (fde_encoding & 7)
798 case elfcpp::DW_EH_PE_absptr:
799 case elfcpp::DW_EH_PE_udata2:
800 case elfcpp::DW_EH_PE_udata4:
801 case elfcpp::DW_EH_PE_udata8:
804 // We don't expect to see any other cases here, and
805 // we're not prepared to handle them.
815 // Personality encoding.
819 unsigned char per_encoding = *p;
822 if ((per_encoding & 0x60) == 0x60)
824 unsigned int per_width;
825 switch (per_encoding & 7)
827 case elfcpp::DW_EH_PE_udata2:
830 case elfcpp::DW_EH_PE_udata4:
833 case elfcpp::DW_EH_PE_udata8:
836 case elfcpp::DW_EH_PE_absptr:
837 per_width = size / 8;
843 if ((per_encoding & 0xf0) == elfcpp::DW_EH_PE_aligned)
845 unsigned int len = p - pcie;
846 len += per_width - 1;
847 len &= ~ (per_width - 1);
848 if (static_cast<unsigned int>(pcieend - p) < len)
853 per_offset = p - pcontents;
855 if (static_cast<unsigned int>(pcieend - p) < per_width)
868 const char* personality_name = "";
869 if (per_offset != -1)
871 if (relocs->advance(per_offset) > 0)
873 if (relocs->next_offset() != per_offset)
876 unsigned int personality_symndx = relocs->next_symndx();
877 if (personality_symndx == -1U)
880 if (personality_symndx < object->local_symbol_count())
882 // We can only merge this CIE if the personality routine is
883 // a global symbol. We can still read the FDEs.
888 const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
889 if (personality_symndx >= symbols_size / sym_size)
891 elfcpp::Sym<size, big_endian> sym(symbols
892 + (personality_symndx * sym_size));
893 unsigned int name_offset = sym.get_st_name();
894 if (name_offset >= symbol_names_size)
896 personality_name = (reinterpret_cast<const char*>(symbol_names)
900 int r = relocs->advance(per_offset + 1);
904 if (relocs->advance(pcieend - pcontents) > 0)
907 Cie cie(object, shndx, (pcie - 8) - pcontents, fde_encoding,
908 personality_name, pcie, pcieend - pcie);
909 Cie* cie_pointer = NULL;
912 Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie);
913 if (find_cie != this->cie_offsets_.end())
914 cie_pointer = *find_cie;
917 // See if we already saw this CIE in this object file.
918 for (New_cies::const_iterator pc = new_cies->begin();
919 pc != new_cies->end();
922 if (*(pc->first) == cie)
924 cie_pointer = pc->first;
931 if (cie_pointer == NULL)
933 cie_pointer = new Cie(cie);
934 new_cies->push_back(std::make_pair(cie_pointer, mergeable));
938 // We are deleting this CIE. Record that in our mapping from
939 // input sections to the output section. At this point we don't
940 // know for sure that we are doing a special mapping for this
941 // input section, but that's OK--if we don't do a special
942 // mapping, nobody will ever ask for the mapping we add here.
943 this->merge_map_.add_mapping(object, shndx, (pcie - 8) - pcontents,
944 pcieend - (pcie - 8), -1);
947 // Record this CIE plus the offset in the input section.
948 cies->insert(std::make_pair(pcie - pcontents, cie_pointer));
953 // Read an FDE. Return false if we can't parse the information.
955 template<int size, bool big_endian>
957 Eh_frame::read_fde(Sized_relobj_file<size, big_endian>* object,
959 const unsigned char* symbols,
960 section_size_type symbols_size,
961 const unsigned char* pcontents,
963 const unsigned char* pfde,
964 const unsigned char* pfdeend,
965 Track_relocs<size, big_endian>* relocs,
966 Offsets_to_cie* cies)
968 // OFFSET is the distance between the 4 bytes before PFDE to the
969 // start of the CIE. The offset we recorded for the CIE is 8 bytes
970 // after the start of the CIE--after the length and the zero tag.
971 unsigned int cie_offset = (pfde - 4 - pcontents) - offset + 8;
972 Offsets_to_cie::const_iterator pcie = cies->find(cie_offset);
973 if (pcie == cies->end())
975 Cie* cie = pcie->second;
977 // The FDE should start with a reloc to the start of the code which
979 if (relocs->advance(pfde - pcontents) > 0)
982 if (relocs->next_offset() != pfde - pcontents)
985 unsigned int symndx = relocs->next_symndx();
989 // There can be another reloc in the FDE, if the CIE specifies an
990 // LSDA (language specific data area). We currently don't care. We
991 // will care later if we want to optimize the LSDA from an absolute
992 // pointer to a PC relative offset when generating a shared library.
993 relocs->advance(pfdeend - pcontents);
995 unsigned int fde_shndx;
996 const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
997 if (symndx >= symbols_size / sym_size)
999 elfcpp::Sym<size, big_endian> sym(symbols + symndx * sym_size);
1001 fde_shndx = object->adjust_sym_shndx(symndx, sym.get_st_shndx(),
1005 && fde_shndx != elfcpp::SHN_UNDEF
1006 && fde_shndx < object->shnum()
1007 && !object->is_section_included(fde_shndx))
1009 // This FDE applies to a section which we are discarding. We
1010 // can discard this FDE.
1011 this->merge_map_.add_mapping(object, shndx, (pfde - 8) - pcontents,
1012 pfdeend - (pfde - 8), -1);
1016 cie->add_fde(new Fde(object, shndx, (pfde - 8) - pcontents,
1017 pfde, pfdeend - pfde));
1022 // Add unwind information for a PLT.
1025 Eh_frame::add_ehframe_for_plt(Output_data* plt, const unsigned char* cie_data,
1026 size_t cie_length, const unsigned char* fde_data,
1029 Cie cie(NULL, 0, 0, elfcpp::DW_EH_PE_pcrel | elfcpp::DW_EH_PE_sdata4, "",
1030 cie_data, cie_length);
1031 Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie);
1033 if (find_cie != this->cie_offsets_.end())
1037 pcie = new Cie(cie);
1038 this->cie_offsets_.insert(pcie);
1041 Fde* fde = new Fde(plt, fde_data, fde_length);
1045 // Return the number of FDEs.
1048 Eh_frame::fde_count() const
1050 unsigned int ret = 0;
1051 for (Unmergeable_cie_offsets::const_iterator p =
1052 this->unmergeable_cie_offsets_.begin();
1053 p != this->unmergeable_cie_offsets_.end();
1055 ret += (*p)->fde_count();
1056 for (Cie_offsets::const_iterator p = this->cie_offsets_.begin();
1057 p != this->cie_offsets_.end();
1059 ret += (*p)->fde_count();
1063 // Set the final data size.
1066 Eh_frame::set_final_data_size()
1068 // We can be called more than once if Layout::set_segment_offsets
1069 // finds a better mapping. We don't want to add all the mappings
1071 if (this->mappings_are_done_)
1073 this->set_data_size(this->final_data_size_);
1077 section_offset_type output_offset = 0;
1079 for (Unmergeable_cie_offsets::iterator p =
1080 this->unmergeable_cie_offsets_.begin();
1081 p != this->unmergeable_cie_offsets_.end();
1083 output_offset = (*p)->set_output_offset(output_offset,
1087 for (Cie_offsets::iterator p = this->cie_offsets_.begin();
1088 p != this->cie_offsets_.end();
1090 output_offset = (*p)->set_output_offset(output_offset,
1094 this->mappings_are_done_ = true;
1095 this->final_data_size_ = output_offset;
1097 gold_assert((output_offset & (this->addralign() - 1)) == 0);
1098 this->set_data_size(output_offset);
1101 // Return an output offset for an input offset.
1104 Eh_frame::do_output_offset(const Relobj* object, unsigned int shndx,
1105 section_offset_type offset,
1106 section_offset_type* poutput) const
1108 return this->merge_map_.get_output_offset(object, shndx, offset, poutput);
1111 // Return whether this is the merge section for an input section.
1114 Eh_frame::do_is_merge_section_for(const Relobj* object,
1115 unsigned int shndx) const
1117 return this->merge_map_.is_merge_section_for(object, shndx);
1120 // Write the data to the output file.
1123 Eh_frame::do_write(Output_file* of)
1125 const off_t offset = this->offset();
1126 const off_t oview_size = this->data_size();
1127 unsigned char* const oview = of->get_output_view(offset, oview_size);
1129 switch (parameters->size_and_endianness())
1131 #ifdef HAVE_TARGET_32_LITTLE
1132 case Parameters::TARGET_32_LITTLE:
1133 this->do_sized_write<32, false>(oview);
1136 #ifdef HAVE_TARGET_32_BIG
1137 case Parameters::TARGET_32_BIG:
1138 this->do_sized_write<32, true>(oview);
1141 #ifdef HAVE_TARGET_64_LITTLE
1142 case Parameters::TARGET_64_LITTLE:
1143 this->do_sized_write<64, false>(oview);
1146 #ifdef HAVE_TARGET_64_BIG
1147 case Parameters::TARGET_64_BIG:
1148 this->do_sized_write<64, true>(oview);
1155 of->write_output_view(offset, oview_size, oview);
1158 // Write the data to the output file--template version.
1160 template<int size, bool big_endian>
1162 Eh_frame::do_sized_write(unsigned char* oview)
1164 uint64_t address = this->address();
1165 unsigned int addralign = this->addralign();
1166 section_offset_type o = 0;
1167 for (Unmergeable_cie_offsets::iterator p =
1168 this->unmergeable_cie_offsets_.begin();
1169 p != this->unmergeable_cie_offsets_.end();
1171 o = (*p)->write<size, big_endian>(oview, o, address, addralign,
1172 this->eh_frame_hdr_);
1173 for (Cie_offsets::iterator p = this->cie_offsets_.begin();
1174 p != this->cie_offsets_.end();
1176 o = (*p)->write<size, big_endian>(oview, o, address, addralign,
1177 this->eh_frame_hdr_);
1180 #ifdef HAVE_TARGET_32_LITTLE
1183 Eh_frame::add_ehframe_input_section<32, false>(
1184 Sized_relobj_file<32, false>* object,
1185 const unsigned char* symbols,
1186 section_size_type symbols_size,
1187 const unsigned char* symbol_names,
1188 section_size_type symbol_names_size,
1190 unsigned int reloc_shndx,
1191 unsigned int reloc_type);
1194 #ifdef HAVE_TARGET_32_BIG
1197 Eh_frame::add_ehframe_input_section<32, true>(
1198 Sized_relobj_file<32, true>* object,
1199 const unsigned char* symbols,
1200 section_size_type symbols_size,
1201 const unsigned char* symbol_names,
1202 section_size_type symbol_names_size,
1204 unsigned int reloc_shndx,
1205 unsigned int reloc_type);
1208 #ifdef HAVE_TARGET_64_LITTLE
1211 Eh_frame::add_ehframe_input_section<64, false>(
1212 Sized_relobj_file<64, false>* object,
1213 const unsigned char* symbols,
1214 section_size_type symbols_size,
1215 const unsigned char* symbol_names,
1216 section_size_type symbol_names_size,
1218 unsigned int reloc_shndx,
1219 unsigned int reloc_type);
1222 #ifdef HAVE_TARGET_64_BIG
1225 Eh_frame::add_ehframe_input_section<64, true>(
1226 Sized_relobj_file<64, true>* object,
1227 const unsigned char* symbols,
1228 section_size_type symbols_size,
1229 const unsigned char* symbol_names,
1230 section_size_type symbol_names_size,
1232 unsigned int reloc_shndx,
1233 unsigned int reloc_type);
1236 } // End namespace gold.