* incremental-dump.cc (dump_incremental_inputs): Print dynamic reloc
[binutils.git] / gold / ehframe.cc
blobfbeb8a3787ffb43fd5617a2144666822e1ae5150
1 // ehframe.cc -- handle exception frame sections for gold
3 // Copyright 2006, 2007, 2008, 2010 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.
23 #include "gold.h"
25 #include <cstring>
26 #include <algorithm>
28 #include "elfcpp.h"
29 #include "dwarf.h"
30 #include "symtab.h"
31 #include "reloc.h"
32 #include "ehframe.h"
34 namespace gold
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
40 // frame information.
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
58 // the table.
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),
86 fde_offsets_(),
87 any_unrecognized_eh_frame_sections_(false)
91 // Set the size of the exception frame header.
93 void
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();
100 if (fde_count != 0)
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.
109 void
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);
117 break;
118 #endif
119 #ifdef HAVE_TARGET_32_BIG
120 case Parameters::TARGET_32_BIG:
121 this->do_sized_write<32, true>(of);
122 break;
123 #endif
124 #ifdef HAVE_TARGET_64_LITTLE
125 case Parameters::TARGET_64_LITTLE:
126 this->do_sized_write<64, false>(of);
127 break;
128 #endif
129 #ifdef HAVE_TARGET_64_BIG
130 case Parameters::TARGET_64_BIG:
131 this->do_sized_write<64, true>(of);
132 break;
133 #endif
134 default:
135 gold_unreachable();
139 // Write the data to the file with the right endianness.
141 template<int size, bool big_endian>
142 void
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);
149 // Version number.
150 oview[0] = 1;
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
166 // sorted table.
167 oview[2] = elfcpp::DW_EH_PE_omit;
168 oview[3] = elfcpp::DW_EH_PE_omit;
170 gold_assert(oview_size == 8);
172 else
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_,
189 &fde_addresses);
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();
200 ++p)
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);
206 pfde += 8;
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
218 // FDE's PC.
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)
237 if (size == 32)
238 pc_size = elfcpp::DW_EH_PE_udata4;
239 else if (size == 64)
240 pc_size = elfcpp::DW_EH_PE_udata8;
241 else
242 gold_unreachable();
245 switch (pc_size)
247 case elfcpp::DW_EH_PE_udata2:
248 pc = elfcpp::Swap<16, big_endian>::readval(p);
249 if (is_signed)
250 pc = (pc ^ 0x8000) - 0x8000;
251 break;
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;
257 break;
259 case elfcpp::DW_EH_PE_udata8:
260 gold_assert(size == 64);
261 pc = elfcpp::Swap_unaligned<64, big_endian>::readval(p);
262 break;
264 default:
265 // All other cases were rejected in Eh_frame::read_cie.
266 gold_unreachable();
269 switch (fde_encoding & 0xf0)
271 case 0:
272 break;
274 case elfcpp::DW_EH_PE_pcrel:
275 pc += eh_frame_address + fde_offset + 8;
276 break;
278 default:
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.
281 gold_unreachable();
284 return pc;
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>
294 void
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,
304 eh_frame_size);
306 for (Fde_offsets::const_iterator p = fde_offsets->begin();
307 p != fde_offsets->end();
308 ++p)
310 typename elfcpp::Elf_types<size>::Elf_Addr fde_pc;
311 fde_pc = this->get_fde_pc<size, big_endian>(eh_frame_address,
312 eh_frame_contents,
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);
320 // Class Fde.
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. Record the FDE pc for
325 // EH_FRAME_HDR. Return the new offset.
327 template<int size, bool big_endian>
328 section_offset_type
329 Fde::write(unsigned char* oview, section_offset_type offset,
330 unsigned int addralign, section_offset_type cie_offset,
331 unsigned char fde_encoding, Eh_frame_hdr* eh_frame_hdr)
333 gold_assert((offset & (addralign - 1)) == 0);
335 size_t length = this->contents_.length();
337 // We add 8 when getting the aligned length to account for the
338 // length word and the CIE offset.
339 size_t aligned_full_length = align_address(length + 8, addralign);
341 // Write the length of the FDE as a 32-bit word. The length word
342 // does not include the four bytes of the length word itself, but it
343 // does include the offset to the CIE.
344 elfcpp::Swap<32, big_endian>::writeval(oview + offset,
345 aligned_full_length - 4);
347 // Write the offset to the CIE as a 32-bit word. This is the
348 // difference between the address of the offset word itself and the
349 // CIE address.
350 elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4,
351 offset + 4 - cie_offset);
353 // Copy the rest of the FDE. Note that this is run before
354 // relocation processing is done on this section, so the relocations
355 // will later be applied to the FDE data.
356 memcpy(oview + offset + 8, this->contents_.data(), length);
358 if (aligned_full_length > length + 8)
359 memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8));
361 // Tell the exception frame header about this FDE.
362 if (eh_frame_hdr != NULL)
363 eh_frame_hdr->record_fde(offset, fde_encoding);
365 return offset + aligned_full_length;
368 // Class Cie.
370 // Destructor.
372 Cie::~Cie()
374 for (std::vector<Fde*>::iterator p = this->fdes_.begin();
375 p != this->fdes_.end();
376 ++p)
377 delete *p;
380 // Set the output offset of a CIE. Return the new output offset.
382 section_offset_type
383 Cie::set_output_offset(section_offset_type output_offset,
384 unsigned int addralign,
385 Merge_map* merge_map)
387 size_t length = this->contents_.length();
389 // Add 4 for length and 4 for zero CIE identifier tag.
390 length += 8;
392 merge_map->add_mapping(this->object_, this->shndx_, this->input_offset_,
393 length, output_offset);
395 length = align_address(length, addralign);
397 for (std::vector<Fde*>::const_iterator p = this->fdes_.begin();
398 p != this->fdes_.end();
399 ++p)
401 (*p)->add_mapping(output_offset + length, merge_map);
403 size_t fde_length = (*p)->length();
404 fde_length = align_address(fde_length, addralign);
405 length += fde_length;
408 return output_offset + length;
411 // Write the CIE to OVIEW starting at OFFSET. EH_FRAME_HDR is for FDE
412 // recording. Round up the bytes to ADDRALIGN. Return the new
413 // offset.
415 template<int size, bool big_endian>
416 section_offset_type
417 Cie::write(unsigned char* oview, section_offset_type offset,
418 unsigned int addralign, Eh_frame_hdr* eh_frame_hdr)
420 gold_assert((offset & (addralign - 1)) == 0);
422 section_offset_type cie_offset = offset;
424 size_t length = this->contents_.length();
426 // We add 8 when getting the aligned length to account for the
427 // length word and the CIE tag.
428 size_t aligned_full_length = align_address(length + 8, addralign);
430 // Write the length of the CIE as a 32-bit word. The length word
431 // does not include the four bytes of the length word itself.
432 elfcpp::Swap<32, big_endian>::writeval(oview + offset,
433 aligned_full_length - 4);
435 // Write the tag which marks this as a CIE: a 32-bit zero.
436 elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, 0);
438 // Write out the CIE data.
439 memcpy(oview + offset + 8, this->contents_.data(), length);
441 if (aligned_full_length > length + 8)
442 memset(oview + offset + length + 8, 0, aligned_full_length - (length + 8));
444 offset += aligned_full_length;
446 // Write out the associated FDEs.
447 unsigned char fde_encoding = this->fde_encoding_;
448 for (std::vector<Fde*>::const_iterator p = this->fdes_.begin();
449 p != this->fdes_.end();
450 ++p)
451 offset = (*p)->write<size, big_endian>(oview, offset, addralign,
452 cie_offset, fde_encoding,
453 eh_frame_hdr);
455 return offset;
458 // We track all the CIEs we see, and merge them when possible. This
459 // works because each FDE holds an offset to the relevant CIE: we
460 // rewrite the FDEs to point to the merged CIE. This is worthwhile
461 // because in a typical C++ program many FDEs in many different object
462 // files will use the same CIE.
464 // An equality operator for Cie.
466 bool
467 operator==(const Cie& cie1, const Cie& cie2)
469 return (cie1.personality_name_ == cie2.personality_name_
470 && cie1.contents_ == cie2.contents_);
473 // A less-than operator for Cie.
475 bool
476 operator<(const Cie& cie1, const Cie& cie2)
478 if (cie1.personality_name_ != cie2.personality_name_)
479 return cie1.personality_name_ < cie2.personality_name_;
480 return cie1.contents_ < cie2.contents_;
483 // Class Eh_frame.
485 Eh_frame::Eh_frame()
486 : Output_section_data(Output_data::default_alignment()),
487 eh_frame_hdr_(NULL),
488 cie_offsets_(),
489 unmergeable_cie_offsets_(),
490 merge_map_(),
491 mappings_are_done_(false),
492 final_data_size_(0)
496 // Skip an LEB128, updating *PP to point to the next character.
497 // Return false if we ran off the end of the string.
499 bool
500 Eh_frame::skip_leb128(const unsigned char** pp, const unsigned char* pend)
502 const unsigned char* p;
503 for (p = *pp; p < pend; ++p)
505 if ((*p & 0x80) == 0)
507 *pp = p + 1;
508 return true;
511 return false;
514 // Add input section SHNDX in OBJECT to an exception frame section.
515 // SYMBOLS is the contents of the symbol table section (size
516 // SYMBOLS_SIZE), SYMBOL_NAMES is the symbol names section (size
517 // SYMBOL_NAMES_SIZE). RELOC_SHNDX is the index of a relocation
518 // section applying to SHNDX, or 0 if none, or -1U if more than one.
519 // RELOC_TYPE is the type of the reloc section if there is one, either
520 // SHT_REL or SHT_RELA. We try to parse the input exception frame
521 // data into our data structures. If we can't do it, we return false
522 // to mean that the section should be handled as a normal input
523 // section.
525 template<int size, bool big_endian>
526 bool
527 Eh_frame::add_ehframe_input_section(
528 Sized_relobj_file<size, big_endian>* object,
529 const unsigned char* symbols,
530 section_size_type symbols_size,
531 const unsigned char* symbol_names,
532 section_size_type symbol_names_size,
533 unsigned int shndx,
534 unsigned int reloc_shndx,
535 unsigned int reloc_type)
537 // Get the section contents.
538 section_size_type contents_len;
539 const unsigned char* pcontents = object->section_contents(shndx,
540 &contents_len,
541 false);
542 if (contents_len == 0)
543 return false;
545 // If this is the marker section for the end of the data, then
546 // return false to force it to be handled as an ordinary input
547 // section. If we don't do this, we won't correctly handle the case
548 // of unrecognized .eh_frame sections.
549 if (contents_len == 4
550 && elfcpp::Swap<32, big_endian>::readval(pcontents) == 0)
551 return false;
553 New_cies new_cies;
554 if (!this->do_add_ehframe_input_section(object, symbols, symbols_size,
555 symbol_names, symbol_names_size,
556 shndx, reloc_shndx,
557 reloc_type, pcontents,
558 contents_len, &new_cies))
560 if (this->eh_frame_hdr_ != NULL)
561 this->eh_frame_hdr_->found_unrecognized_eh_frame_section();
563 for (New_cies::iterator p = new_cies.begin();
564 p != new_cies.end();
565 ++p)
566 delete p->first;
568 return false;
571 // Now that we know we are using this section, record any new CIEs
572 // that we found.
573 for (New_cies::const_iterator p = new_cies.begin();
574 p != new_cies.end();
575 ++p)
577 if (p->second)
578 this->cie_offsets_.insert(p->first);
579 else
580 this->unmergeable_cie_offsets_.push_back(p->first);
583 return true;
586 // The bulk of the implementation of add_ehframe_input_section.
588 template<int size, bool big_endian>
589 bool
590 Eh_frame::do_add_ehframe_input_section(
591 Sized_relobj_file<size, big_endian>* object,
592 const unsigned char* symbols,
593 section_size_type symbols_size,
594 const unsigned char* symbol_names,
595 section_size_type symbol_names_size,
596 unsigned int shndx,
597 unsigned int reloc_shndx,
598 unsigned int reloc_type,
599 const unsigned char* pcontents,
600 section_size_type contents_len,
601 New_cies* new_cies)
603 typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
604 Track_relocs<size, big_endian> relocs;
606 const unsigned char* p = pcontents;
607 const unsigned char* pend = p + contents_len;
609 // Get the contents of the reloc section if any.
610 if (!relocs.initialize(object, reloc_shndx, reloc_type))
611 return false;
613 // Keep track of which CIEs are at which offsets.
614 Offsets_to_cie cies;
616 while (p < pend)
618 if (pend - p < 4)
619 return false;
621 // There shouldn't be any relocations here.
622 if (relocs.advance(p + 4 - pcontents) > 0)
623 return false;
625 unsigned int len = elfcpp::Swap<32, big_endian>::readval(p);
626 p += 4;
627 if (len == 0)
629 // We should only find a zero-length entry at the end of the
630 // section.
631 if (p < pend)
632 return false;
633 break;
635 // We don't support a 64-bit .eh_frame.
636 if (len == 0xffffffff)
637 return false;
638 if (static_cast<unsigned int>(pend - p) < len)
639 return false;
641 const unsigned char* const pentend = p + len;
643 if (pend - p < 4)
644 return false;
645 if (relocs.advance(p + 4 - pcontents) > 0)
646 return false;
648 unsigned int id = elfcpp::Swap<32, big_endian>::readval(p);
649 p += 4;
651 if (id == 0)
653 // CIE.
654 if (!this->read_cie(object, shndx, symbols, symbols_size,
655 symbol_names, symbol_names_size,
656 pcontents, p, pentend, &relocs, &cies,
657 new_cies))
658 return false;
660 else
662 // FDE.
663 if (!this->read_fde(object, shndx, symbols, symbols_size,
664 pcontents, id, p, pentend, &relocs, &cies))
665 return false;
668 p = pentend;
671 return true;
674 // Read a CIE. Return false if we can't parse the information.
676 template<int size, bool big_endian>
677 bool
678 Eh_frame::read_cie(Sized_relobj_file<size, big_endian>* object,
679 unsigned int shndx,
680 const unsigned char* symbols,
681 section_size_type symbols_size,
682 const unsigned char* symbol_names,
683 section_size_type symbol_names_size,
684 const unsigned char* pcontents,
685 const unsigned char* pcie,
686 const unsigned char* pcieend,
687 Track_relocs<size, big_endian>* relocs,
688 Offsets_to_cie* cies,
689 New_cies* new_cies)
691 bool mergeable = true;
693 // We need to find the personality routine if there is one, since we
694 // can only merge CIEs which use the same routine. We also need to
695 // find the FDE encoding if there is one, so that we can read the PC
696 // from the FDE.
698 const unsigned char* p = pcie;
700 if (pcieend - p < 1)
701 return false;
702 unsigned char version = *p++;
703 if (version != 1 && version != 3)
704 return false;
706 const unsigned char* paug = p;
707 const void* paugendv = memchr(p, '\0', pcieend - p);
708 const unsigned char* paugend = static_cast<const unsigned char*>(paugendv);
709 if (paugend == NULL)
710 return false;
711 p = paugend + 1;
713 if (paug[0] == 'e' && paug[1] == 'h')
715 // This is a CIE from gcc before version 3.0. We can't merge
716 // these. We can still read the FDEs.
717 mergeable = false;
718 paug += 2;
719 if (*paug != '\0')
720 return false;
721 if (pcieend - p < size / 8)
722 return false;
723 p += size / 8;
726 // Skip the code alignment.
727 if (!skip_leb128(&p, pcieend))
728 return false;
730 // Skip the data alignment.
731 if (!skip_leb128(&p, pcieend))
732 return false;
734 // Skip the return column.
735 if (version == 1)
737 if (pcieend - p < 1)
738 return false;
739 ++p;
741 else
743 if (!skip_leb128(&p, pcieend))
744 return false;
747 if (*paug == 'z')
749 ++paug;
750 // Skip the augmentation size.
751 if (!skip_leb128(&p, pcieend))
752 return false;
755 unsigned char fde_encoding = elfcpp::DW_EH_PE_absptr;
756 int per_offset = -1;
757 while (*paug != '\0')
759 switch (*paug)
761 case 'L': // LSDA encoding.
762 if (pcieend - p < 1)
763 return false;
764 ++p;
765 break;
767 case 'R': // FDE encoding.
768 if (pcieend - p < 1)
769 return false;
770 fde_encoding = *p;
771 switch (fde_encoding & 7)
773 case elfcpp::DW_EH_PE_absptr:
774 case elfcpp::DW_EH_PE_udata2:
775 case elfcpp::DW_EH_PE_udata4:
776 case elfcpp::DW_EH_PE_udata8:
777 break;
778 default:
779 // We don't expect to see any other cases here, and
780 // we're not prepared to handle them.
781 return false;
783 ++p;
784 break;
786 case 'S':
787 break;
789 case 'P':
790 // Personality encoding.
792 if (pcieend - p < 1)
793 return false;
794 unsigned char per_encoding = *p;
795 ++p;
797 if ((per_encoding & 0x60) == 0x60)
798 return false;
799 unsigned int per_width;
800 switch (per_encoding & 7)
802 case elfcpp::DW_EH_PE_udata2:
803 per_width = 2;
804 break;
805 case elfcpp::DW_EH_PE_udata4:
806 per_width = 4;
807 break;
808 case elfcpp::DW_EH_PE_udata8:
809 per_width = 8;
810 break;
811 case elfcpp::DW_EH_PE_absptr:
812 per_width = size / 8;
813 break;
814 default:
815 return false;
818 if ((per_encoding & 0xf0) == elfcpp::DW_EH_PE_aligned)
820 unsigned int len = p - pcie;
821 len += per_width - 1;
822 len &= ~ (per_width - 1);
823 if (static_cast<unsigned int>(pcieend - p) < len)
824 return false;
825 p += len;
828 per_offset = p - pcontents;
830 if (static_cast<unsigned int>(pcieend - p) < per_width)
831 return false;
832 p += per_width;
834 break;
836 default:
837 return false;
840 ++paug;
843 const char* personality_name = "";
844 if (per_offset != -1)
846 if (relocs->advance(per_offset) > 0)
847 return false;
848 if (relocs->next_offset() != per_offset)
849 return false;
851 unsigned int personality_symndx = relocs->next_symndx();
852 if (personality_symndx == -1U)
853 return false;
855 if (personality_symndx < object->local_symbol_count())
857 // We can only merge this CIE if the personality routine is
858 // a global symbol. We can still read the FDEs.
859 mergeable = false;
861 else
863 const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
864 if (personality_symndx >= symbols_size / sym_size)
865 return false;
866 elfcpp::Sym<size, big_endian> sym(symbols
867 + (personality_symndx * sym_size));
868 unsigned int name_offset = sym.get_st_name();
869 if (name_offset >= symbol_names_size)
870 return false;
871 personality_name = (reinterpret_cast<const char*>(symbol_names)
872 + name_offset);
875 int r = relocs->advance(per_offset + 1);
876 gold_assert(r == 1);
879 if (relocs->advance(pcieend - pcontents) > 0)
880 return false;
882 Cie cie(object, shndx, (pcie - 8) - pcontents, fde_encoding,
883 personality_name, pcie, pcieend - pcie);
884 Cie* cie_pointer = NULL;
885 if (mergeable)
887 Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie);
888 if (find_cie != this->cie_offsets_.end())
889 cie_pointer = *find_cie;
890 else
892 // See if we already saw this CIE in this object file.
893 for (New_cies::const_iterator pc = new_cies->begin();
894 pc != new_cies->end();
895 ++pc)
897 if (*(pc->first) == cie)
899 cie_pointer = pc->first;
900 break;
906 if (cie_pointer == NULL)
908 cie_pointer = new Cie(cie);
909 new_cies->push_back(std::make_pair(cie_pointer, mergeable));
911 else
913 // We are deleting this CIE. Record that in our mapping from
914 // input sections to the output section. At this point we don't
915 // know for sure that we are doing a special mapping for this
916 // input section, but that's OK--if we don't do a special
917 // mapping, nobody will ever ask for the mapping we add here.
918 this->merge_map_.add_mapping(object, shndx, (pcie - 8) - pcontents,
919 pcieend - (pcie - 8), -1);
922 // Record this CIE plus the offset in the input section.
923 cies->insert(std::make_pair(pcie - pcontents, cie_pointer));
925 return true;
928 // Read an FDE. Return false if we can't parse the information.
930 template<int size, bool big_endian>
931 bool
932 Eh_frame::read_fde(Sized_relobj_file<size, big_endian>* object,
933 unsigned int shndx,
934 const unsigned char* symbols,
935 section_size_type symbols_size,
936 const unsigned char* pcontents,
937 unsigned int offset,
938 const unsigned char* pfde,
939 const unsigned char* pfdeend,
940 Track_relocs<size, big_endian>* relocs,
941 Offsets_to_cie* cies)
943 // OFFSET is the distance between the 4 bytes before PFDE to the
944 // start of the CIE. The offset we recorded for the CIE is 8 bytes
945 // after the start of the CIE--after the length and the zero tag.
946 unsigned int cie_offset = (pfde - 4 - pcontents) - offset + 8;
947 Offsets_to_cie::const_iterator pcie = cies->find(cie_offset);
948 if (pcie == cies->end())
949 return false;
950 Cie* cie = pcie->second;
952 // The FDE should start with a reloc to the start of the code which
953 // it describes.
954 if (relocs->advance(pfde - pcontents) > 0)
955 return false;
957 if (relocs->next_offset() != pfde - pcontents)
958 return false;
960 unsigned int symndx = relocs->next_symndx();
961 if (symndx == -1U)
962 return false;
964 // There can be another reloc in the FDE, if the CIE specifies an
965 // LSDA (language specific data area). We currently don't care. We
966 // will care later if we want to optimize the LSDA from an absolute
967 // pointer to a PC relative offset when generating a shared library.
968 relocs->advance(pfdeend - pcontents);
970 unsigned int fde_shndx;
971 const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
972 if (symndx >= symbols_size / sym_size)
973 return false;
974 elfcpp::Sym<size, big_endian> sym(symbols + symndx * sym_size);
975 bool is_ordinary;
976 fde_shndx = object->adjust_sym_shndx(symndx, sym.get_st_shndx(),
977 &is_ordinary);
979 if (is_ordinary
980 && fde_shndx != elfcpp::SHN_UNDEF
981 && fde_shndx < object->shnum()
982 && !object->is_section_included(fde_shndx))
984 // This FDE applies to a section which we are discarding. We
985 // can discard this FDE.
986 this->merge_map_.add_mapping(object, shndx, (pfde - 8) - pcontents,
987 pfdeend - (pfde - 8), -1);
988 return true;
991 cie->add_fde(new Fde(object, shndx, (pfde - 8) - pcontents,
992 pfde, pfdeend - pfde));
994 return true;
997 // Return the number of FDEs.
999 unsigned int
1000 Eh_frame::fde_count() const
1002 unsigned int ret = 0;
1003 for (Unmergeable_cie_offsets::const_iterator p =
1004 this->unmergeable_cie_offsets_.begin();
1005 p != this->unmergeable_cie_offsets_.end();
1006 ++p)
1007 ret += (*p)->fde_count();
1008 for (Cie_offsets::const_iterator p = this->cie_offsets_.begin();
1009 p != this->cie_offsets_.end();
1010 ++p)
1011 ret += (*p)->fde_count();
1012 return ret;
1015 // Set the final data size.
1017 void
1018 Eh_frame::set_final_data_size()
1020 // We can be called more than once if Layout::set_segment_offsets
1021 // finds a better mapping. We don't want to add all the mappings
1022 // again.
1023 if (this->mappings_are_done_)
1025 this->set_data_size(this->final_data_size_);
1026 return;
1029 section_offset_type output_offset = 0;
1031 for (Unmergeable_cie_offsets::iterator p =
1032 this->unmergeable_cie_offsets_.begin();
1033 p != this->unmergeable_cie_offsets_.end();
1034 ++p)
1035 output_offset = (*p)->set_output_offset(output_offset,
1036 this->addralign(),
1037 &this->merge_map_);
1039 for (Cie_offsets::iterator p = this->cie_offsets_.begin();
1040 p != this->cie_offsets_.end();
1041 ++p)
1042 output_offset = (*p)->set_output_offset(output_offset,
1043 this->addralign(),
1044 &this->merge_map_);
1046 this->mappings_are_done_ = true;
1047 this->final_data_size_ = output_offset;
1049 gold_assert((output_offset & (this->addralign() - 1)) == 0);
1050 this->set_data_size(output_offset);
1053 // Return an output offset for an input offset.
1055 bool
1056 Eh_frame::do_output_offset(const Relobj* object, unsigned int shndx,
1057 section_offset_type offset,
1058 section_offset_type* poutput) const
1060 return this->merge_map_.get_output_offset(object, shndx, offset, poutput);
1063 // Return whether this is the merge section for an input section.
1065 bool
1066 Eh_frame::do_is_merge_section_for(const Relobj* object,
1067 unsigned int shndx) const
1069 return this->merge_map_.is_merge_section_for(object, shndx);
1072 // Write the data to the output file.
1074 void
1075 Eh_frame::do_write(Output_file* of)
1077 const off_t offset = this->offset();
1078 const off_t oview_size = this->data_size();
1079 unsigned char* const oview = of->get_output_view(offset, oview_size);
1081 switch (parameters->size_and_endianness())
1083 #ifdef HAVE_TARGET_32_LITTLE
1084 case Parameters::TARGET_32_LITTLE:
1085 this->do_sized_write<32, false>(oview);
1086 break;
1087 #endif
1088 #ifdef HAVE_TARGET_32_BIG
1089 case Parameters::TARGET_32_BIG:
1090 this->do_sized_write<32, true>(oview);
1091 break;
1092 #endif
1093 #ifdef HAVE_TARGET_64_LITTLE
1094 case Parameters::TARGET_64_LITTLE:
1095 this->do_sized_write<64, false>(oview);
1096 break;
1097 #endif
1098 #ifdef HAVE_TARGET_64_BIG
1099 case Parameters::TARGET_64_BIG:
1100 this->do_sized_write<64, true>(oview);
1101 break;
1102 #endif
1103 default:
1104 gold_unreachable();
1107 of->write_output_view(offset, oview_size, oview);
1110 // Write the data to the output file--template version.
1112 template<int size, bool big_endian>
1113 void
1114 Eh_frame::do_sized_write(unsigned char* oview)
1116 unsigned int addralign = this->addralign();
1117 section_offset_type o = 0;
1118 for (Unmergeable_cie_offsets::iterator p =
1119 this->unmergeable_cie_offsets_.begin();
1120 p != this->unmergeable_cie_offsets_.end();
1121 ++p)
1122 o = (*p)->write<size, big_endian>(oview, o, addralign,
1123 this->eh_frame_hdr_);
1124 for (Cie_offsets::iterator p = this->cie_offsets_.begin();
1125 p != this->cie_offsets_.end();
1126 ++p)
1127 o = (*p)->write<size, big_endian>(oview, o, addralign,
1128 this->eh_frame_hdr_);
1131 #ifdef HAVE_TARGET_32_LITTLE
1132 template
1133 bool
1134 Eh_frame::add_ehframe_input_section<32, false>(
1135 Sized_relobj_file<32, false>* object,
1136 const unsigned char* symbols,
1137 section_size_type symbols_size,
1138 const unsigned char* symbol_names,
1139 section_size_type symbol_names_size,
1140 unsigned int shndx,
1141 unsigned int reloc_shndx,
1142 unsigned int reloc_type);
1143 #endif
1145 #ifdef HAVE_TARGET_32_BIG
1146 template
1147 bool
1148 Eh_frame::add_ehframe_input_section<32, true>(
1149 Sized_relobj_file<32, true>* object,
1150 const unsigned char* symbols,
1151 section_size_type symbols_size,
1152 const unsigned char* symbol_names,
1153 section_size_type symbol_names_size,
1154 unsigned int shndx,
1155 unsigned int reloc_shndx,
1156 unsigned int reloc_type);
1157 #endif
1159 #ifdef HAVE_TARGET_64_LITTLE
1160 template
1161 bool
1162 Eh_frame::add_ehframe_input_section<64, false>(
1163 Sized_relobj_file<64, false>* object,
1164 const unsigned char* symbols,
1165 section_size_type symbols_size,
1166 const unsigned char* symbol_names,
1167 section_size_type symbol_names_size,
1168 unsigned int shndx,
1169 unsigned int reloc_shndx,
1170 unsigned int reloc_type);
1171 #endif
1173 #ifdef HAVE_TARGET_64_BIG
1174 template
1175 bool
1176 Eh_frame::add_ehframe_input_section<64, true>(
1177 Sized_relobj_file<64, true>* object,
1178 const unsigned char* symbols,
1179 section_size_type symbols_size,
1180 const unsigned char* symbol_names,
1181 section_size_type symbol_names_size,
1182 unsigned int shndx,
1183 unsigned int reloc_shndx,
1184 unsigned int reloc_type);
1185 #endif
1187 } // End namespace gold.