1 // ehframe.cc -- handle exception frame sections for gold
3 // Copyright 2006, 2007, 2008, 2010, 2011, 2012 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
& 0x70)
274 case elfcpp::DW_EH_PE_pcrel
:
275 pc
+= eh_frame_address
+ fde_offset
+ 8;
278 case elfcpp::DW_EH_PE_datarel
:
279 pc
+= parameters
->target().ehframe_datarel_base();
283 // If other cases arise, then we have to handle them, or we have
284 // to reject them by returning false in Eh_frame::read_cie.
288 gold_assert((fde_encoding
& elfcpp::DW_EH_PE_indirect
) == 0);
293 // Given an array of FDE offsets in the .eh_frame section, return an
294 // array of offsets from the exception frame header to the FDE's
295 // output PC and to the output address of the FDE itself. We get the
296 // FDE's PC by actually looking in the .eh_frame section we just wrote
297 // to the output file.
299 template<int size
, bool big_endian
>
301 Eh_frame_hdr::get_fde_addresses(Output_file
* of
,
302 const Fde_offsets
* fde_offsets
,
303 Fde_addresses
<size
>* fde_addresses
)
305 typename
elfcpp::Elf_types
<size
>::Elf_Addr eh_frame_address
;
306 eh_frame_address
= this->eh_frame_section_
->address();
307 off_t eh_frame_offset
= this->eh_frame_section_
->offset();
308 off_t eh_frame_size
= this->eh_frame_section_
->data_size();
309 const unsigned char* eh_frame_contents
= of
->get_input_view(eh_frame_offset
,
312 for (Fde_offsets::const_iterator p
= fde_offsets
->begin();
313 p
!= fde_offsets
->end();
316 typename
elfcpp::Elf_types
<size
>::Elf_Addr fde_pc
;
317 fde_pc
= this->get_fde_pc
<size
, big_endian
>(eh_frame_address
,
319 p
->first
, p
->second
);
320 fde_addresses
->push_back(fde_pc
, eh_frame_address
+ p
->first
);
323 of
->free_input_view(eh_frame_offset
, eh_frame_size
, eh_frame_contents
);
328 // Write the FDE to OVIEW starting at OFFSET. CIE_OFFSET is the
329 // offset of the CIE in OVIEW. FDE_ENCODING is the encoding, from the
330 // CIE. ADDRALIGN is the required alignment. ADDRESS is the virtual
331 // address of OVIEW. Record the FDE pc for EH_FRAME_HDR. Return the
334 template<int size
, bool big_endian
>
336 Fde::write(unsigned char* oview
, section_offset_type offset
,
337 uint64_t address
, unsigned int addralign
,
338 section_offset_type cie_offset
, unsigned char fde_encoding
,
339 Eh_frame_hdr
* eh_frame_hdr
)
341 gold_assert((offset
& (addralign
- 1)) == 0);
343 size_t length
= this->contents_
.length();
345 // We add 8 when getting the aligned length to account for the
346 // length word and the CIE offset.
347 size_t aligned_full_length
= align_address(length
+ 8, addralign
);
349 // Write the length of the FDE as a 32-bit word. The length word
350 // does not include the four bytes of the length word itself, but it
351 // does include the offset to the CIE.
352 elfcpp::Swap
<32, big_endian
>::writeval(oview
+ offset
,
353 aligned_full_length
- 4);
355 // Write the offset to the CIE as a 32-bit word. This is the
356 // difference between the address of the offset word itself and the
358 elfcpp::Swap
<32, big_endian
>::writeval(oview
+ offset
+ 4,
359 offset
+ 4 - cie_offset
);
361 // Copy the rest of the FDE. Note that this is run before
362 // relocation processing is done on this section, so the relocations
363 // will later be applied to the FDE data.
364 memcpy(oview
+ offset
+ 8, this->contents_
.data(), length
);
366 // If this FDE is associated with a PLT, fill in the PLT's address
368 if (this->object_
== NULL
)
370 gold_assert(memcmp(oview
+ offset
+ 8, "\0\0\0\0\0\0\0\0", 8) == 0);
373 parameters
->target().plt_fde_location(this->u_
.from_linker
.plt
,
376 uint64_t poffset
= paddress
- (address
+ offset
+ 8);
377 int32_t spoffset
= static_cast<int32_t>(poffset
);
378 uint32_t upsize
= static_cast<uint32_t>(psize
);
379 if (static_cast<uint64_t>(static_cast<int64_t>(spoffset
)) != poffset
380 || static_cast<off_t
>(upsize
) != psize
)
381 gold_warning(_("overflow in PLT unwind data; "
382 "unwinding through PLT may fail"));
383 elfcpp::Swap
<32, big_endian
>::writeval(oview
+ offset
+ 8, spoffset
);
384 elfcpp::Swap
<32, big_endian
>::writeval(oview
+ offset
+ 12, upsize
);
387 if (aligned_full_length
> length
+ 8)
388 memset(oview
+ offset
+ length
+ 8, 0, aligned_full_length
- (length
+ 8));
390 // Tell the exception frame header about this FDE.
391 if (eh_frame_hdr
!= NULL
)
392 eh_frame_hdr
->record_fde(offset
, fde_encoding
);
394 return offset
+ aligned_full_length
;
403 for (std::vector
<Fde
*>::iterator p
= this->fdes_
.begin();
404 p
!= this->fdes_
.end();
409 // Set the output offset of a CIE. Return the new output offset.
412 Cie::set_output_offset(section_offset_type output_offset
,
413 unsigned int addralign
,
414 Merge_map
* merge_map
)
416 size_t length
= this->contents_
.length();
418 // Add 4 for length and 4 for zero CIE identifier tag.
421 if (this->object_
!= NULL
)
423 // Add a mapping so that relocations are applied correctly.
424 merge_map
->add_mapping(this->object_
, this->shndx_
, this->input_offset_
,
425 length
, output_offset
);
428 length
= align_address(length
, addralign
);
430 for (std::vector
<Fde
*>::const_iterator p
= this->fdes_
.begin();
431 p
!= this->fdes_
.end();
434 (*p
)->add_mapping(output_offset
+ length
, merge_map
);
436 size_t fde_length
= (*p
)->length();
437 fde_length
= align_address(fde_length
, addralign
);
438 length
+= fde_length
;
441 return output_offset
+ length
;
444 // A FDE plus some info from a CIE to allow later writing of the FDE.
448 Post_fde(Fde
* f
, section_offset_type cie_off
, unsigned char encoding
)
449 : fde(f
), cie_offset(cie_off
), fde_encoding(encoding
)
453 section_offset_type cie_offset
;
454 unsigned char fde_encoding
;
457 // Write the CIE to OVIEW starting at OFFSET. Round up the bytes to
458 // ADDRALIGN. ADDRESS is the virtual address of OVIEW.
459 // EH_FRAME_HDR is the exception frame header for FDE recording.
460 // POST_FDES stashes FDEs created after mappings were done, for later
461 // writing. Return the new offset.
463 template<int size
, bool big_endian
>
465 Cie::write(unsigned char* oview
, section_offset_type offset
,
466 uint64_t address
, unsigned int addralign
,
467 Eh_frame_hdr
* eh_frame_hdr
, Post_fdes
* post_fdes
)
469 gold_assert((offset
& (addralign
- 1)) == 0);
471 section_offset_type cie_offset
= offset
;
473 size_t length
= this->contents_
.length();
475 // We add 8 when getting the aligned length to account for the
476 // length word and the CIE tag.
477 size_t aligned_full_length
= align_address(length
+ 8, addralign
);
479 // Write the length of the CIE as a 32-bit word. The length word
480 // does not include the four bytes of the length word itself.
481 elfcpp::Swap
<32, big_endian
>::writeval(oview
+ offset
,
482 aligned_full_length
- 4);
484 // Write the tag which marks this as a CIE: a 32-bit zero.
485 elfcpp::Swap
<32, big_endian
>::writeval(oview
+ offset
+ 4, 0);
487 // Write out the CIE data.
488 memcpy(oview
+ offset
+ 8, this->contents_
.data(), length
);
490 if (aligned_full_length
> length
+ 8)
491 memset(oview
+ offset
+ length
+ 8, 0, aligned_full_length
- (length
+ 8));
493 offset
+= aligned_full_length
;
495 // Write out the associated FDEs.
496 unsigned char fde_encoding
= this->fde_encoding_
;
497 for (std::vector
<Fde
*>::const_iterator p
= this->fdes_
.begin();
498 p
!= this->fdes_
.end();
501 if ((*p
)->post_map())
502 post_fdes
->push_back(new Post_fde(*p
, cie_offset
, fde_encoding
));
504 offset
= (*p
)->write
<size
, big_endian
>(oview
, offset
, address
,
505 addralign
, cie_offset
,
506 fde_encoding
, eh_frame_hdr
);
512 // We track all the CIEs we see, and merge them when possible. This
513 // works because each FDE holds an offset to the relevant CIE: we
514 // rewrite the FDEs to point to the merged CIE. This is worthwhile
515 // because in a typical C++ program many FDEs in many different object
516 // files will use the same CIE.
518 // An equality operator for Cie.
521 operator==(const Cie
& cie1
, const Cie
& cie2
)
523 return (cie1
.personality_name_
== cie2
.personality_name_
524 && cie1
.contents_
== cie2
.contents_
);
527 // A less-than operator for Cie.
530 operator<(const Cie
& cie1
, const Cie
& cie2
)
532 if (cie1
.personality_name_
!= cie2
.personality_name_
)
533 return cie1
.personality_name_
< cie2
.personality_name_
;
534 return cie1
.contents_
< cie2
.contents_
;
540 : Output_section_data(Output_data::default_alignment()),
543 unmergeable_cie_offsets_(),
545 mappings_are_done_(false),
550 // Skip an LEB128, updating *PP to point to the next character.
551 // Return false if we ran off the end of the string.
554 Eh_frame::skip_leb128(const unsigned char** pp
, const unsigned char* pend
)
556 const unsigned char* p
;
557 for (p
= *pp
; p
< pend
; ++p
)
559 if ((*p
& 0x80) == 0)
568 // Add input section SHNDX in OBJECT to an exception frame section.
569 // SYMBOLS is the contents of the symbol table section (size
570 // SYMBOLS_SIZE), SYMBOL_NAMES is the symbol names section (size
571 // SYMBOL_NAMES_SIZE). RELOC_SHNDX is the index of a relocation
572 // section applying to SHNDX, or 0 if none, or -1U if more than one.
573 // RELOC_TYPE is the type of the reloc section if there is one, either
574 // SHT_REL or SHT_RELA. We try to parse the input exception frame
575 // data into our data structures. If we can't do it, we return false
576 // to mean that the section should be handled as a normal input
579 template<int size
, bool big_endian
>
581 Eh_frame::add_ehframe_input_section(
582 Sized_relobj_file
<size
, big_endian
>* object
,
583 const unsigned char* symbols
,
584 section_size_type symbols_size
,
585 const unsigned char* symbol_names
,
586 section_size_type symbol_names_size
,
588 unsigned int reloc_shndx
,
589 unsigned int reloc_type
)
591 // Get the section contents.
592 section_size_type contents_len
;
593 const unsigned char* pcontents
= object
->section_contents(shndx
,
596 if (contents_len
== 0)
599 // If this is the marker section for the end of the data, then
600 // return false to force it to be handled as an ordinary input
601 // section. If we don't do this, we won't correctly handle the case
602 // of unrecognized .eh_frame sections.
603 if (contents_len
== 4
604 && elfcpp::Swap
<32, big_endian
>::readval(pcontents
) == 0)
608 if (!this->do_add_ehframe_input_section(object
, symbols
, symbols_size
,
609 symbol_names
, symbol_names_size
,
611 reloc_type
, pcontents
,
612 contents_len
, &new_cies
))
614 if (this->eh_frame_hdr_
!= NULL
)
615 this->eh_frame_hdr_
->found_unrecognized_eh_frame_section();
617 for (New_cies::iterator p
= new_cies
.begin();
625 // Now that we know we are using this section, record any new CIEs
627 for (New_cies::const_iterator p
= new_cies
.begin();
632 this->cie_offsets_
.insert(p
->first
);
634 this->unmergeable_cie_offsets_
.push_back(p
->first
);
640 // The bulk of the implementation of add_ehframe_input_section.
642 template<int size
, bool big_endian
>
644 Eh_frame::do_add_ehframe_input_section(
645 Sized_relobj_file
<size
, big_endian
>* object
,
646 const unsigned char* symbols
,
647 section_size_type symbols_size
,
648 const unsigned char* symbol_names
,
649 section_size_type symbol_names_size
,
651 unsigned int reloc_shndx
,
652 unsigned int reloc_type
,
653 const unsigned char* pcontents
,
654 section_size_type contents_len
,
657 Track_relocs
<size
, big_endian
> relocs
;
659 const unsigned char* p
= pcontents
;
660 const unsigned char* pend
= p
+ contents_len
;
662 // Get the contents of the reloc section if any.
663 if (!relocs
.initialize(object
, reloc_shndx
, reloc_type
))
666 // Keep track of which CIEs are at which offsets.
674 // There shouldn't be any relocations here.
675 if (relocs
.advance(p
+ 4 - pcontents
) > 0)
678 unsigned int len
= elfcpp::Swap
<32, big_endian
>::readval(p
);
682 // We should only find a zero-length entry at the end of the
688 // We don't support a 64-bit .eh_frame.
689 if (len
== 0xffffffff)
691 if (static_cast<unsigned int>(pend
- p
) < len
)
694 const unsigned char* const pentend
= p
+ len
;
698 if (relocs
.advance(p
+ 4 - pcontents
) > 0)
701 unsigned int id
= elfcpp::Swap
<32, big_endian
>::readval(p
);
707 if (!this->read_cie(object
, shndx
, symbols
, symbols_size
,
708 symbol_names
, symbol_names_size
,
709 pcontents
, p
, pentend
, &relocs
, &cies
,
716 if (!this->read_fde(object
, shndx
, symbols
, symbols_size
,
717 pcontents
, id
, p
, pentend
, &relocs
, &cies
))
727 // Read a CIE. Return false if we can't parse the information.
729 template<int size
, bool big_endian
>
731 Eh_frame::read_cie(Sized_relobj_file
<size
, big_endian
>* object
,
733 const unsigned char* symbols
,
734 section_size_type symbols_size
,
735 const unsigned char* symbol_names
,
736 section_size_type symbol_names_size
,
737 const unsigned char* pcontents
,
738 const unsigned char* pcie
,
739 const unsigned char* pcieend
,
740 Track_relocs
<size
, big_endian
>* relocs
,
741 Offsets_to_cie
* cies
,
744 bool mergeable
= true;
746 // We need to find the personality routine if there is one, since we
747 // can only merge CIEs which use the same routine. We also need to
748 // find the FDE encoding if there is one, so that we can read the PC
751 const unsigned char* p
= pcie
;
755 unsigned char version
= *p
++;
756 if (version
!= 1 && version
!= 3)
759 const unsigned char* paug
= p
;
760 const void* paugendv
= memchr(p
, '\0', pcieend
- p
);
761 const unsigned char* paugend
= static_cast<const unsigned char*>(paugendv
);
766 if (paug
[0] == 'e' && paug
[1] == 'h')
768 // This is a CIE from gcc before version 3.0. We can't merge
769 // these. We can still read the FDEs.
774 if (pcieend
- p
< size
/ 8)
779 // Skip the code alignment.
780 if (!skip_leb128(&p
, pcieend
))
783 // Skip the data alignment.
784 if (!skip_leb128(&p
, pcieend
))
787 // Skip the return column.
796 if (!skip_leb128(&p
, pcieend
))
803 // Skip the augmentation size.
804 if (!skip_leb128(&p
, pcieend
))
808 unsigned char fde_encoding
= elfcpp::DW_EH_PE_absptr
;
810 while (*paug
!= '\0')
814 case 'L': // LSDA encoding.
820 case 'R': // FDE encoding.
824 switch (fde_encoding
& 7)
826 case elfcpp::DW_EH_PE_absptr
:
827 case elfcpp::DW_EH_PE_udata2
:
828 case elfcpp::DW_EH_PE_udata4
:
829 case elfcpp::DW_EH_PE_udata8
:
832 // We don't expect to see any other cases here, and
833 // we're not prepared to handle them.
843 // Personality encoding.
847 unsigned char per_encoding
= *p
;
850 if ((per_encoding
& 0x60) == 0x60)
852 unsigned int per_width
;
853 switch (per_encoding
& 7)
855 case elfcpp::DW_EH_PE_udata2
:
858 case elfcpp::DW_EH_PE_udata4
:
861 case elfcpp::DW_EH_PE_udata8
:
864 case elfcpp::DW_EH_PE_absptr
:
865 per_width
= size
/ 8;
871 if ((per_encoding
& 0xf0) == elfcpp::DW_EH_PE_aligned
)
873 unsigned int len
= p
- pcie
;
874 len
+= per_width
- 1;
875 len
&= ~ (per_width
- 1);
876 if (static_cast<unsigned int>(pcieend
- p
) < len
)
881 per_offset
= p
- pcontents
;
883 if (static_cast<unsigned int>(pcieend
- p
) < per_width
)
896 const char* personality_name
= "";
897 if (per_offset
!= -1)
899 if (relocs
->advance(per_offset
) > 0)
901 if (relocs
->next_offset() != per_offset
)
904 unsigned int personality_symndx
= relocs
->next_symndx();
905 if (personality_symndx
== -1U)
908 if (personality_symndx
< object
->local_symbol_count())
910 // We can only merge this CIE if the personality routine is
911 // a global symbol. We can still read the FDEs.
916 const int sym_size
= elfcpp::Elf_sizes
<size
>::sym_size
;
917 if (personality_symndx
>= symbols_size
/ sym_size
)
919 elfcpp::Sym
<size
, big_endian
> sym(symbols
920 + (personality_symndx
* sym_size
));
921 unsigned int name_offset
= sym
.get_st_name();
922 if (name_offset
>= symbol_names_size
)
924 personality_name
= (reinterpret_cast<const char*>(symbol_names
)
928 int r
= relocs
->advance(per_offset
+ 1);
932 if (relocs
->advance(pcieend
- pcontents
) > 0)
935 Cie
cie(object
, shndx
, (pcie
- 8) - pcontents
, fde_encoding
,
936 personality_name
, pcie
, pcieend
- pcie
);
937 Cie
* cie_pointer
= NULL
;
940 Cie_offsets::iterator find_cie
= this->cie_offsets_
.find(&cie
);
941 if (find_cie
!= this->cie_offsets_
.end())
942 cie_pointer
= *find_cie
;
945 // See if we already saw this CIE in this object file.
946 for (New_cies::const_iterator pc
= new_cies
->begin();
947 pc
!= new_cies
->end();
950 if (*(pc
->first
) == cie
)
952 cie_pointer
= pc
->first
;
959 if (cie_pointer
== NULL
)
961 cie_pointer
= new Cie(cie
);
962 new_cies
->push_back(std::make_pair(cie_pointer
, mergeable
));
966 // We are deleting this CIE. Record that in our mapping from
967 // input sections to the output section. At this point we don't
968 // know for sure that we are doing a special mapping for this
969 // input section, but that's OK--if we don't do a special
970 // mapping, nobody will ever ask for the mapping we add here.
971 this->merge_map_
.add_mapping(object
, shndx
, (pcie
- 8) - pcontents
,
972 pcieend
- (pcie
- 8), -1);
975 // Record this CIE plus the offset in the input section.
976 cies
->insert(std::make_pair(pcie
- pcontents
, cie_pointer
));
981 // Read an FDE. Return false if we can't parse the information.
983 template<int size
, bool big_endian
>
985 Eh_frame::read_fde(Sized_relobj_file
<size
, big_endian
>* object
,
987 const unsigned char* symbols
,
988 section_size_type symbols_size
,
989 const unsigned char* pcontents
,
991 const unsigned char* pfde
,
992 const unsigned char* pfdeend
,
993 Track_relocs
<size
, big_endian
>* relocs
,
994 Offsets_to_cie
* cies
)
996 // OFFSET is the distance between the 4 bytes before PFDE to the
997 // start of the CIE. The offset we recorded for the CIE is 8 bytes
998 // after the start of the CIE--after the length and the zero tag.
999 unsigned int cie_offset
= (pfde
- 4 - pcontents
) - offset
+ 8;
1000 Offsets_to_cie::const_iterator pcie
= cies
->find(cie_offset
);
1001 if (pcie
== cies
->end())
1003 Cie
* cie
= pcie
->second
;
1005 // The FDE should start with a reloc to the start of the code which
1007 if (relocs
->advance(pfde
- pcontents
) > 0)
1010 if (relocs
->next_offset() != pfde
- pcontents
)
1013 unsigned int symndx
= relocs
->next_symndx();
1017 // There can be another reloc in the FDE, if the CIE specifies an
1018 // LSDA (language specific data area). We currently don't care. We
1019 // will care later if we want to optimize the LSDA from an absolute
1020 // pointer to a PC relative offset when generating a shared library.
1021 relocs
->advance(pfdeend
- pcontents
);
1023 unsigned int fde_shndx
;
1024 const int sym_size
= elfcpp::Elf_sizes
<size
>::sym_size
;
1025 if (symndx
>= symbols_size
/ sym_size
)
1027 elfcpp::Sym
<size
, big_endian
> sym(symbols
+ symndx
* sym_size
);
1029 fde_shndx
= object
->adjust_sym_shndx(symndx
, sym
.get_st_shndx(),
1033 && fde_shndx
!= elfcpp::SHN_UNDEF
1034 && fde_shndx
< object
->shnum()
1035 && !object
->is_section_included(fde_shndx
))
1037 // This FDE applies to a section which we are discarding. We
1038 // can discard this FDE.
1039 this->merge_map_
.add_mapping(object
, shndx
, (pfde
- 8) - pcontents
,
1040 pfdeend
- (pfde
- 8), -1);
1044 cie
->add_fde(new Fde(object
, shndx
, (pfde
- 8) - pcontents
,
1045 pfde
, pfdeend
- pfde
));
1050 // Add unwind information for a PLT.
1053 Eh_frame::add_ehframe_for_plt(Output_data
* plt
, const unsigned char* cie_data
,
1054 size_t cie_length
, const unsigned char* fde_data
,
1057 Cie
cie(NULL
, 0, 0, elfcpp::DW_EH_PE_pcrel
| elfcpp::DW_EH_PE_sdata4
, "",
1058 cie_data
, cie_length
);
1059 Cie_offsets::iterator find_cie
= this->cie_offsets_
.find(&cie
);
1061 if (find_cie
!= this->cie_offsets_
.end())
1065 gold_assert(!this->mappings_are_done_
);
1066 pcie
= new Cie(cie
);
1067 this->cie_offsets_
.insert(pcie
);
1070 Fde
* fde
= new Fde(plt
, fde_data
, fde_length
, this->mappings_are_done_
);
1073 if (this->mappings_are_done_
)
1074 this->final_data_size_
+= align_address(fde_length
+ 8, this->addralign());
1077 // Return the number of FDEs.
1080 Eh_frame::fde_count() const
1082 unsigned int ret
= 0;
1083 for (Unmergeable_cie_offsets::const_iterator p
=
1084 this->unmergeable_cie_offsets_
.begin();
1085 p
!= this->unmergeable_cie_offsets_
.end();
1087 ret
+= (*p
)->fde_count();
1088 for (Cie_offsets::const_iterator p
= this->cie_offsets_
.begin();
1089 p
!= this->cie_offsets_
.end();
1091 ret
+= (*p
)->fde_count();
1095 // Set the final data size.
1098 Eh_frame::set_final_data_size()
1100 // We can be called more than once if Layout::set_segment_offsets
1101 // finds a better mapping. We don't want to add all the mappings
1103 if (this->mappings_are_done_
)
1105 this->set_data_size(this->final_data_size_
);
1109 section_offset_type output_offset
= 0;
1111 for (Unmergeable_cie_offsets::iterator p
=
1112 this->unmergeable_cie_offsets_
.begin();
1113 p
!= this->unmergeable_cie_offsets_
.end();
1115 output_offset
= (*p
)->set_output_offset(output_offset
,
1119 for (Cie_offsets::iterator p
= this->cie_offsets_
.begin();
1120 p
!= this->cie_offsets_
.end();
1122 output_offset
= (*p
)->set_output_offset(output_offset
,
1126 this->mappings_are_done_
= true;
1127 this->final_data_size_
= output_offset
;
1129 gold_assert((output_offset
& (this->addralign() - 1)) == 0);
1130 this->set_data_size(output_offset
);
1133 // Return an output offset for an input offset.
1136 Eh_frame::do_output_offset(const Relobj
* object
, unsigned int shndx
,
1137 section_offset_type offset
,
1138 section_offset_type
* poutput
) const
1140 return this->merge_map_
.get_output_offset(object
, shndx
, offset
, poutput
);
1143 // Return whether this is the merge section for an input section.
1146 Eh_frame::do_is_merge_section_for(const Relobj
* object
,
1147 unsigned int shndx
) const
1149 return this->merge_map_
.is_merge_section_for(object
, shndx
);
1152 // Write the data to the output file.
1155 Eh_frame::do_write(Output_file
* of
)
1157 const off_t offset
= this->offset();
1158 const off_t oview_size
= this->data_size();
1159 unsigned char* const oview
= of
->get_output_view(offset
, oview_size
);
1161 switch (parameters
->size_and_endianness())
1163 #ifdef HAVE_TARGET_32_LITTLE
1164 case Parameters::TARGET_32_LITTLE
:
1165 this->do_sized_write
<32, false>(oview
);
1168 #ifdef HAVE_TARGET_32_BIG
1169 case Parameters::TARGET_32_BIG
:
1170 this->do_sized_write
<32, true>(oview
);
1173 #ifdef HAVE_TARGET_64_LITTLE
1174 case Parameters::TARGET_64_LITTLE
:
1175 this->do_sized_write
<64, false>(oview
);
1178 #ifdef HAVE_TARGET_64_BIG
1179 case Parameters::TARGET_64_BIG
:
1180 this->do_sized_write
<64, true>(oview
);
1187 of
->write_output_view(offset
, oview_size
, oview
);
1190 // Write the data to the output file--template version.
1192 template<int size
, bool big_endian
>
1194 Eh_frame::do_sized_write(unsigned char* oview
)
1196 uint64_t address
= this->address();
1197 unsigned int addralign
= this->addralign();
1198 section_offset_type o
= 0;
1199 Post_fdes post_fdes
;
1200 for (Unmergeable_cie_offsets::iterator p
=
1201 this->unmergeable_cie_offsets_
.begin();
1202 p
!= this->unmergeable_cie_offsets_
.end();
1204 o
= (*p
)->write
<size
, big_endian
>(oview
, o
, address
, addralign
,
1205 this->eh_frame_hdr_
, &post_fdes
);
1206 for (Cie_offsets::iterator p
= this->cie_offsets_
.begin();
1207 p
!= this->cie_offsets_
.end();
1209 o
= (*p
)->write
<size
, big_endian
>(oview
, o
, address
, addralign
,
1210 this->eh_frame_hdr_
, &post_fdes
);
1211 for (Post_fdes::iterator p
= post_fdes
.begin();
1212 p
!= post_fdes
.end();
1215 o
= (*p
)->fde
->write
<size
, big_endian
>(oview
, o
, address
, addralign
,
1218 this->eh_frame_hdr_
);
1223 #ifdef HAVE_TARGET_32_LITTLE
1226 Eh_frame::add_ehframe_input_section
<32, false>(
1227 Sized_relobj_file
<32, false>* object
,
1228 const unsigned char* symbols
,
1229 section_size_type symbols_size
,
1230 const unsigned char* symbol_names
,
1231 section_size_type symbol_names_size
,
1233 unsigned int reloc_shndx
,
1234 unsigned int reloc_type
);
1237 #ifdef HAVE_TARGET_32_BIG
1240 Eh_frame::add_ehframe_input_section
<32, true>(
1241 Sized_relobj_file
<32, true>* object
,
1242 const unsigned char* symbols
,
1243 section_size_type symbols_size
,
1244 const unsigned char* symbol_names
,
1245 section_size_type symbol_names_size
,
1247 unsigned int reloc_shndx
,
1248 unsigned int reloc_type
);
1251 #ifdef HAVE_TARGET_64_LITTLE
1254 Eh_frame::add_ehframe_input_section
<64, false>(
1255 Sized_relobj_file
<64, false>* object
,
1256 const unsigned char* symbols
,
1257 section_size_type symbols_size
,
1258 const unsigned char* symbol_names
,
1259 section_size_type symbol_names_size
,
1261 unsigned int reloc_shndx
,
1262 unsigned int reloc_type
);
1265 #ifdef HAVE_TARGET_64_BIG
1268 Eh_frame::add_ehframe_input_section
<64, true>(
1269 Sized_relobj_file
<64, true>* object
,
1270 const unsigned char* symbols
,
1271 section_size_type symbols_size
,
1272 const unsigned char* symbol_names
,
1273 section_size_type symbol_names_size
,
1275 unsigned int reloc_shndx
,
1276 unsigned int reloc_type
);
1279 } // End namespace gold.