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3151305a ILT |
1 | // ehframe.cc -- handle exception frame sections for gold |
2 | ||
3 | // Copyright 2006, 2007 Free Software Foundation, Inc. | |
4 | // Written by Ian Lance Taylor <iant@google.com>. | |
5 | ||
6 | // This file is part of gold. | |
7 | ||
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. | |
12 | ||
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. | |
17 | ||
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. | |
22 | ||
23 | #include "gold.h" | |
24 | ||
730cdc88 ILT |
25 | #include <cstring> |
26 | #include <algorithm> | |
27 | ||
3151305a ILT |
28 | #include "elfcpp.h" |
29 | #include "dwarf.h" | |
730cdc88 ILT |
30 | #include "symtab.h" |
31 | #include "reloc.h" | |
3151305a ILT |
32 | #include "ehframe.h" |
33 | ||
34 | namespace gold | |
35 | { | |
36 | ||
37 | // This file handles generation of the exception frame header that | |
38 | // gcc's runtime support libraries use to find unwind information at | |
730cdc88 ILT |
39 | // runtime. This file also handles discarding duplicate exception |
40 | // frame information. | |
3151305a ILT |
41 | |
42 | // The exception frame header starts with four bytes: | |
43 | ||
44 | // 0: The version number, currently 1. | |
45 | ||
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). | |
49 | ||
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). | |
54 | ||
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. | |
59 | ||
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). | |
64 | ||
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). | |
68 | ||
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. | |
76 | ||
3151305a ILT |
77 | const int eh_frame_hdr_size = 4; |
78 | ||
79 | // Construct the exception frame header. | |
80 | ||
730cdc88 ILT |
81 | Eh_frame_hdr::Eh_frame_hdr(Output_section* eh_frame_section, |
82 | const Eh_frame* eh_frame_data) | |
3151305a | 83 | : Output_section_data(4), |
730cdc88 ILT |
84 | eh_frame_section_(eh_frame_section), |
85 | eh_frame_data_(eh_frame_data), | |
86 | fde_offsets_(), | |
87 | any_unrecognized_eh_frame_sections_(false) | |
3151305a ILT |
88 | { |
89 | } | |
90 | ||
27bc2bce | 91 | // Set the size of the exception frame header. |
3151305a ILT |
92 | |
93 | void | |
27bc2bce | 94 | Eh_frame_hdr::set_final_data_size() |
3151305a | 95 | { |
730cdc88 ILT |
96 | unsigned int data_size = eh_frame_hdr_size + 4; |
97 | if (!this->any_unrecognized_eh_frame_sections_) | |
98 | { | |
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); | |
103 | } | |
104 | this->set_data_size(data_size); | |
3151305a ILT |
105 | } |
106 | ||
107 | // Write the data to the flie. | |
108 | ||
109 | void | |
110 | Eh_frame_hdr::do_write(Output_file* of) | |
730cdc88 ILT |
111 | { |
112 | if (parameters->get_size() == 32) | |
113 | { | |
114 | if (!parameters->is_big_endian()) | |
115 | { | |
116 | #ifdef HAVE_TARGET_32_LITTLE | |
117 | this->do_sized_write<32, false>(of); | |
118 | #else | |
119 | gold_unreachable(); | |
120 | #endif | |
121 | } | |
122 | else | |
123 | { | |
124 | #ifdef HAVE_TARGET_32_BIG | |
125 | this->do_sized_write<32, true>(of); | |
126 | #else | |
127 | gold_unreachable(); | |
128 | #endif | |
129 | } | |
130 | } | |
131 | else if (parameters->get_size() == 64) | |
132 | { | |
133 | if (!parameters->is_big_endian()) | |
134 | { | |
135 | #ifdef HAVE_TARGET_64_LITTLE | |
136 | this->do_sized_write<64, false>(of); | |
137 | #else | |
138 | gold_unreachable(); | |
139 | #endif | |
140 | } | |
141 | else | |
142 | { | |
143 | #ifdef HAVE_TARGET_64_BIG | |
144 | this->do_sized_write<64, true>(of); | |
145 | #else | |
146 | gold_unreachable(); | |
147 | #endif | |
148 | } | |
149 | } | |
150 | else | |
151 | gold_unreachable(); | |
152 | } | |
153 | ||
154 | // Write the data to the file with the right endianness. | |
155 | ||
156 | template<int size, bool big_endian> | |
157 | void | |
158 | Eh_frame_hdr::do_sized_write(Output_file* of) | |
3151305a ILT |
159 | { |
160 | const off_t off = this->offset(); | |
161 | const off_t oview_size = this->data_size(); | |
162 | unsigned char* const oview = of->get_output_view(off, oview_size); | |
163 | ||
164 | // Version number. | |
165 | oview[0] = 1; | |
166 | ||
167 | // Write out a 4 byte PC relative offset to the address of the | |
168 | // .eh_frame section. | |
169 | oview[1] = elfcpp::DW_EH_PE_pcrel | elfcpp::DW_EH_PE_sdata4; | |
170 | uint64_t eh_frame_address = this->eh_frame_section_->address(); | |
171 | uint64_t eh_frame_hdr_address = this->address(); | |
172 | uint64_t eh_frame_offset = (eh_frame_address - | |
173 | (eh_frame_hdr_address + 4)); | |
730cdc88 ILT |
174 | elfcpp::Swap<32, big_endian>::writeval(oview + 4, eh_frame_offset); |
175 | ||
176 | if (this->any_unrecognized_eh_frame_sections_ | |
177 | || this->fde_offsets_.empty()) | |
178 | { | |
179 | // There are no FDEs, or we didn't recognize the format of the | |
180 | // some of the .eh_frame sections, so we can't write out the | |
181 | // sorted table. | |
182 | oview[2] = elfcpp::DW_EH_PE_omit; | |
183 | oview[3] = elfcpp::DW_EH_PE_omit; | |
184 | ||
185 | gold_assert(oview_size == 8); | |
186 | } | |
3151305a | 187 | else |
730cdc88 ILT |
188 | { |
189 | oview[2] = elfcpp::DW_EH_PE_udata4; | |
190 | oview[3] = elfcpp::DW_EH_PE_datarel | elfcpp::DW_EH_PE_sdata4; | |
191 | ||
192 | elfcpp::Swap<32, big_endian>::writeval(oview + 8, | |
193 | this->fde_offsets_.size()); | |
194 | ||
195 | // We have the offsets of the FDEs in the .eh_frame section. We | |
196 | // couldn't easily get the PC values before, as they depend on | |
197 | // relocations which are, of course, target specific. This code | |
198 | // is run after all those relocations have been applied to the | |
199 | // output file. Here we read the output file again to find the | |
200 | // PC values. Then we sort the list and write it out. | |
3151305a | 201 | |
730cdc88 ILT |
202 | Fde_addresses<size> fde_addresses(this->fde_offsets_.size()); |
203 | this->get_fde_addresses<size, big_endian>(of, &this->fde_offsets_, | |
204 | &fde_addresses); | |
3151305a | 205 | |
730cdc88 ILT |
206 | std::sort(fde_addresses.begin(), fde_addresses.end(), |
207 | Fde_address_compare<size>()); | |
208 | ||
209 | typename elfcpp::Elf_types<size>::Elf_Addr output_address; | |
210 | output_address = this->address(); | |
211 | ||
212 | unsigned char* pfde = oview + 12; | |
213 | for (typename Fde_addresses<size>::iterator p = fde_addresses.begin(); | |
214 | p != fde_addresses.end(); | |
215 | ++p) | |
216 | { | |
217 | elfcpp::Swap<32, big_endian>::writeval(pfde, | |
218 | p->first - output_address); | |
219 | elfcpp::Swap<32, big_endian>::writeval(pfde + 4, | |
220 | p->second - output_address); | |
221 | pfde += 8; | |
222 | } | |
223 | ||
224 | gold_assert(pfde - oview == oview_size); | |
225 | } | |
3151305a ILT |
226 | |
227 | of->write_output_view(off, oview_size, oview); | |
228 | } | |
229 | ||
730cdc88 ILT |
230 | // Given the offset FDE_OFFSET of an FDE in the .eh_frame section, and |
231 | // the contents of the .eh_frame section EH_FRAME_CONTENTS, where the | |
232 | // FDE's encoding is FDE_ENCODING, return the output address of the | |
233 | // FDE's PC. | |
234 | ||
235 | template<int size, bool big_endian> | |
236 | typename elfcpp::Elf_types<size>::Elf_Addr | |
237 | Eh_frame_hdr::get_fde_pc(const unsigned char* eh_frame_contents, | |
238 | off_t fde_offset, unsigned char fde_encoding) | |
239 | { | |
240 | // The FDE starts with a 4 byte length and a 4 byte offset to the | |
241 | // CIE. The PC follows. | |
242 | const unsigned char* p = eh_frame_contents + fde_offset + 8; | |
243 | ||
244 | typename elfcpp::Elf_types<size>::Elf_Addr pc; | |
245 | bool is_signed = (fde_encoding & elfcpp::DW_EH_PE_signed) != 0; | |
246 | int pc_size = fde_encoding & 7; | |
247 | if (pc_size == elfcpp::DW_EH_PE_absptr) | |
248 | { | |
249 | if (size == 32) | |
250 | pc_size = elfcpp::DW_EH_PE_udata4; | |
251 | else if (size == 64) | |
252 | pc_size = elfcpp::DW_EH_PE_udata8; | |
253 | else | |
254 | gold_unreachable(); | |
255 | } | |
256 | ||
257 | switch (pc_size) | |
258 | { | |
259 | case elfcpp::DW_EH_PE_udata2: | |
260 | pc = elfcpp::Swap<16, big_endian>::readval(p); | |
261 | if (is_signed) | |
262 | pc = (pc ^ 0x8000) - 0x8000; | |
263 | break; | |
264 | ||
265 | case elfcpp::DW_EH_PE_udata4: | |
266 | pc = elfcpp::Swap<32, big_endian>::readval(p); | |
267 | if (size > 32 && is_signed) | |
268 | pc = (pc ^ 0x80000000) - 0x80000000; | |
269 | break; | |
270 | ||
271 | case elfcpp::DW_EH_PE_udata8: | |
272 | gold_assert(size == 64); | |
273 | pc = elfcpp::Swap_unaligned<64, big_endian>::readval(p); | |
274 | break; | |
275 | ||
276 | default: | |
277 | gold_unreachable(); | |
278 | } | |
279 | ||
280 | return pc; | |
281 | } | |
282 | ||
283 | // Given an array of FDE offsets in the .eh_frame section, return an | |
284 | // array of offsets from the exception frame header to the FDE's | |
285 | // output PC and to the output address of the FDE itself. We get the | |
286 | // FDE's PC by actually looking in the .eh_frame section we just wrote | |
287 | // to the output file. | |
288 | ||
289 | template<int size, bool big_endian> | |
290 | void | |
291 | Eh_frame_hdr::get_fde_addresses(Output_file* of, | |
292 | const Fde_offsets* fde_offsets, | |
293 | Fde_addresses<size>* fde_addresses) | |
294 | { | |
295 | typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address; | |
296 | eh_frame_address = this->eh_frame_section_->address(); | |
297 | off_t eh_frame_offset = this->eh_frame_section_->offset(); | |
298 | off_t eh_frame_size = this->eh_frame_section_->data_size(); | |
299 | const unsigned char* eh_frame_contents = of->get_input_view(eh_frame_offset, | |
300 | eh_frame_size); | |
301 | ||
302 | for (Fde_offsets::const_iterator p = fde_offsets->begin(); | |
303 | p != fde_offsets->end(); | |
304 | ++p) | |
305 | { | |
306 | typename elfcpp::Elf_types<size>::Elf_Addr fde_pc; | |
307 | fde_pc = this->get_fde_pc<size, big_endian>(eh_frame_contents, | |
308 | p->first, p->second); | |
309 | fde_addresses->push_back(fde_pc, eh_frame_address + p->first); | |
310 | } | |
311 | ||
312 | of->free_input_view(eh_frame_offset, eh_frame_size, eh_frame_contents); | |
313 | } | |
314 | ||
315 | // Class Fde. | |
316 | ||
317 | // Write the FDE to OVIEW starting at OFFSET. CIE_OFFSET is the | |
318 | // offset of the CIE in OVIEW. FDE_ENCODING is the encoding, from the | |
319 | // CIE. Record the FDE pc for EH_FRAME_HDR. Return the new offset. | |
320 | ||
321 | template<int size, bool big_endian> | |
322 | off_t | |
323 | Fde::write(unsigned char* oview, off_t offset, off_t cie_offset, | |
324 | unsigned char fde_encoding, Eh_frame_hdr* eh_frame_hdr) | |
325 | { | |
326 | size_t length = this->contents_.length(); | |
327 | ||
328 | // Write the length of the FDE as a 32-bit word. The length word | |
329 | // does not include the four bytes of the length word itself, but it | |
330 | // does include the offset to the CIE. | |
331 | elfcpp::Swap<32, big_endian>::writeval(oview + offset, | |
332 | length + 4); | |
333 | ||
334 | // Write the offset to the CIE as a 32-bit word. This is the | |
335 | // difference between the address of the offset word itself and the | |
336 | // CIE address. | |
337 | elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, | |
338 | offset + 4 - cie_offset); | |
339 | ||
340 | // Copy the rest of the FDE. Note that this is run before | |
341 | // relocation processing is done on this section, so the relocations | |
342 | // will later be applied to the FDE data. | |
343 | memcpy(oview + offset + 8, this->contents_.data(), length); | |
344 | ||
345 | // Tell the exception frame header about this FDE. | |
346 | if (eh_frame_hdr != NULL) | |
347 | eh_frame_hdr->record_fde(offset, fde_encoding); | |
348 | ||
349 | return offset + length + 8; | |
350 | } | |
351 | ||
352 | // Class Cie. | |
353 | ||
354 | // Destructor. | |
355 | ||
356 | Cie::~Cie() | |
357 | { | |
358 | for (std::vector<Fde*>::iterator p = this->fdes_.begin(); | |
359 | p != this->fdes_.end(); | |
360 | ++p) | |
361 | delete *p; | |
362 | } | |
363 | ||
364 | // Set the output offset of a CIE. Return the new output offset. | |
365 | ||
366 | off_t | |
367 | Cie::set_output_offset(off_t output_offset, unsigned int addralign, | |
368 | Merge_map* merge_map) | |
369 | { | |
370 | size_t length = this->contents_.length(); | |
371 | gold_assert((length & (addralign - 1)) == 0); | |
372 | // Add 4 for length and 4 for zero CIE identifier tag. | |
373 | length += 8; | |
374 | ||
375 | merge_map->add_mapping(this->object_, this->shndx_, this->input_offset_, | |
376 | length, output_offset); | |
377 | ||
378 | for (std::vector<Fde*>::const_iterator p = this->fdes_.begin(); | |
379 | p != this->fdes_.end(); | |
380 | ++p) | |
381 | { | |
382 | (*p)->add_mapping(output_offset + length, merge_map); | |
383 | ||
384 | size_t fde_length = (*p)->length(); | |
385 | gold_assert((fde_length & (addralign - 1)) == 0); | |
386 | length += fde_length; | |
387 | } | |
388 | ||
389 | return output_offset + length; | |
390 | } | |
391 | ||
392 | // Write the CIE to OVIEW starting at OFFSET. EH_FRAME_HDR is for FDE | |
393 | // recording. Return the new offset. | |
394 | ||
395 | template<int size, bool big_endian> | |
396 | off_t | |
397 | Cie::write(unsigned char* oview, off_t offset, Eh_frame_hdr* eh_frame_hdr) | |
398 | { | |
399 | off_t cie_offset = offset; | |
400 | ||
401 | size_t length = this->contents_.length(); | |
402 | ||
403 | // Write the length of the CIE as a 32-bit word. The length word | |
404 | // does not include the four bytes of the length word itself. | |
405 | elfcpp::Swap<32, big_endian>::writeval(oview + offset, length + 4); | |
406 | ||
407 | // Write the tag which marks this as a CIE: a 32-bit zero. | |
408 | elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, 0); | |
409 | ||
410 | // Write out the CIE data. | |
411 | memcpy(oview + offset + 8, this->contents_.data(), length); | |
412 | offset += length + 8; | |
413 | ||
414 | // Write out the associated FDEs. | |
415 | unsigned char fde_encoding = this->fde_encoding_; | |
416 | for (std::vector<Fde*>::const_iterator p = this->fdes_.begin(); | |
417 | p != this->fdes_.end(); | |
418 | ++p) | |
419 | offset = (*p)->write<size, big_endian>(oview, offset, cie_offset, | |
420 | fde_encoding, eh_frame_hdr); | |
421 | ||
422 | return offset; | |
423 | } | |
424 | ||
425 | // We track all the CIEs we see, and merge them when possible. This | |
426 | // works because each FDE holds an offset to the relevant CIE: we | |
427 | // rewrite the FDEs to point to the merged CIE. This is worthwhile | |
428 | // because in a typical C++ program many FDEs in many different object | |
429 | // files will use the same CIE. | |
430 | ||
431 | // An equality operator for Cie. | |
432 | ||
433 | bool | |
434 | operator==(const Cie& cie1, const Cie& cie2) | |
435 | { | |
436 | return (cie1.personality_name_ == cie2.personality_name_ | |
437 | && cie1.contents_ == cie2.contents_); | |
438 | } | |
439 | ||
440 | // A less-than operator for Cie. | |
441 | ||
442 | bool | |
443 | operator<(const Cie& cie1, const Cie& cie2) | |
444 | { | |
445 | if (cie1.personality_name_ != cie2.personality_name_) | |
446 | return cie1.personality_name_ < cie2.personality_name_; | |
447 | return cie1.contents_ < cie2.contents_; | |
448 | } | |
449 | ||
450 | // Class Eh_frame. | |
451 | ||
452 | Eh_frame::Eh_frame() | |
453 | : Output_section_data(Output_data::default_alignment()), | |
454 | eh_frame_hdr_(NULL), | |
455 | cie_offsets_(), | |
456 | unmergeable_cie_offsets_(), | |
457 | merge_map_() | |
458 | { | |
459 | } | |
460 | ||
461 | // Skip an LEB128, updating *PP to point to the next character. | |
462 | // Return false if we ran off the end of the string. | |
463 | ||
464 | bool | |
465 | Eh_frame::skip_leb128(const unsigned char** pp, const unsigned char* pend) | |
466 | { | |
467 | const unsigned char* p; | |
468 | for (p = *pp; p < pend; ++p) | |
469 | { | |
470 | if ((*p & 0x80) == 0) | |
471 | { | |
472 | *pp = p + 1; | |
473 | return true; | |
474 | } | |
475 | } | |
476 | return false; | |
477 | } | |
478 | ||
479 | // Add input section SHNDX in OBJECT to an exception frame section. | |
480 | // SYMBOLS is the contents of the symbol table section (size | |
481 | // SYMBOLS_SIZE), SYMBOL_NAMES is the symbol names section (size | |
482 | // SYMBOL_NAMES_SIZE). RELOC_SHNDX is the index of a relocation | |
483 | // section applying to SHNDX, or 0 if none, or -1U if more than one. | |
484 | // RELOC_TYPE is the type of the reloc section if there is one, either | |
485 | // SHT_REL or SHT_RELA. We try to parse the input exception frame | |
486 | // data into our data structures. If we can't do it, we return false | |
487 | // to mean that the section should be handled as a normal input | |
488 | // section. | |
489 | ||
490 | template<int size, bool big_endian> | |
491 | bool | |
492 | Eh_frame::add_ehframe_input_section( | |
493 | Sized_relobj<size, big_endian>* object, | |
494 | const unsigned char* symbols, | |
495 | off_t symbols_size, | |
496 | const unsigned char* symbol_names, | |
497 | off_t symbol_names_size, | |
498 | unsigned int shndx, | |
499 | unsigned int reloc_shndx, | |
500 | unsigned int reloc_type) | |
501 | { | |
502 | // Get the section contents. | |
503 | off_t contents_len; | |
504 | const unsigned char* pcontents = object->section_contents(shndx, | |
505 | &contents_len, | |
506 | false); | |
507 | if (contents_len == 0) | |
508 | return false; | |
509 | ||
510 | // If this is the marker section for the end of the data, then | |
511 | // return false to force it to be handled as an ordinary input | |
512 | // section. If we don't do this, we won't correctly handle the case | |
513 | // of unrecognized .eh_frame sections. | |
514 | if (contents_len == 4 | |
515 | && elfcpp::Swap<32, big_endian>::readval(pcontents) == 0) | |
516 | return false; | |
517 | ||
518 | New_cies new_cies; | |
519 | if (!this->do_add_ehframe_input_section(object, symbols, symbols_size, | |
520 | symbol_names, symbol_names_size, | |
521 | shndx, reloc_shndx, | |
522 | reloc_type, pcontents, | |
523 | contents_len, &new_cies)) | |
524 | { | |
525 | this->eh_frame_hdr_->found_unrecognized_eh_frame_section(); | |
526 | ||
527 | for (New_cies::iterator p = new_cies.begin(); | |
528 | p != new_cies.end(); | |
529 | ++p) | |
530 | delete p->first; | |
531 | ||
532 | return false; | |
533 | } | |
534 | ||
535 | // Now that we know we are using this section, record any new CIEs | |
536 | // that we found. | |
537 | for (New_cies::const_iterator p = new_cies.begin(); | |
538 | p != new_cies.end(); | |
539 | ++p) | |
540 | { | |
541 | uint64_t zero = 0; | |
542 | if (p->second) | |
543 | this->cie_offsets_.insert(std::make_pair(p->first, zero)); | |
544 | else | |
545 | this->unmergeable_cie_offsets_.push_back(std::make_pair(p->first, | |
546 | zero)); | |
547 | } | |
548 | ||
549 | return true; | |
550 | } | |
551 | ||
552 | // The bulk of the implementation of add_ehframe_input_section. | |
553 | ||
554 | template<int size, bool big_endian> | |
555 | bool | |
556 | Eh_frame::do_add_ehframe_input_section( | |
557 | Sized_relobj<size, big_endian>* object, | |
558 | const unsigned char* symbols, | |
559 | off_t symbols_size, | |
560 | const unsigned char* symbol_names, | |
561 | off_t symbol_names_size, | |
562 | unsigned int shndx, | |
563 | unsigned int reloc_shndx, | |
564 | unsigned int reloc_type, | |
565 | const unsigned char* pcontents, | |
566 | off_t contents_len, | |
567 | New_cies* new_cies) | |
568 | { | |
569 | typedef typename elfcpp::Elf_types<size>::Elf_Addr Address; | |
570 | Track_relocs<size, big_endian> relocs; | |
571 | ||
572 | const unsigned char* p = pcontents; | |
573 | const unsigned char* pend = p + contents_len; | |
574 | ||
575 | // Get the contents of the reloc section if any. | |
576 | if (!relocs.initialize(object, reloc_shndx, reloc_type)) | |
577 | return false; | |
578 | ||
579 | // Keep track of which CIEs are at which offsets. | |
580 | Offsets_to_cie cies; | |
581 | ||
582 | while (p < pend) | |
583 | { | |
584 | if (pend - p < 4) | |
585 | return false; | |
586 | ||
587 | // There shouldn't be any relocations here. | |
588 | if (relocs.advance(p + 4 - pcontents) > 0) | |
589 | return false; | |
590 | ||
591 | unsigned int len = elfcpp::Swap<32, big_endian>::readval(p); | |
592 | p += 4; | |
593 | if (len == 0) | |
594 | { | |
595 | // We should only find a zero-length entry at the end of the | |
596 | // section. | |
597 | if (p < pend) | |
598 | return false; | |
599 | break; | |
600 | } | |
601 | // We don't support a 64-bit .eh_frame. | |
602 | if (len == 0xffffffff) | |
603 | return false; | |
604 | if (static_cast<unsigned int>(pend - p) < len) | |
605 | return false; | |
606 | ||
607 | const unsigned char* const pentend = p + len; | |
608 | ||
609 | if (pend - p < 4) | |
610 | return false; | |
611 | if (relocs.advance(p + 4 - pcontents) > 0) | |
612 | return false; | |
613 | ||
614 | unsigned int id = elfcpp::Swap<32, big_endian>::readval(p); | |
615 | p += 4; | |
616 | ||
617 | if (id == 0) | |
618 | { | |
619 | // CIE. | |
620 | if (!this->read_cie(object, shndx, symbols, symbols_size, | |
621 | symbol_names, symbol_names_size, | |
622 | pcontents, p, pentend, &relocs, &cies, | |
623 | new_cies)) | |
624 | return false; | |
625 | } | |
626 | else | |
627 | { | |
628 | // FDE. | |
629 | if (!this->read_fde(object, shndx, symbols, symbols_size, | |
630 | pcontents, id, p, pentend, &relocs, &cies)) | |
631 | return false; | |
632 | } | |
633 | ||
634 | p = pentend; | |
635 | } | |
636 | ||
637 | return true; | |
638 | } | |
639 | ||
640 | // Read a CIE. Return false if we can't parse the information. | |
641 | ||
642 | template<int size, bool big_endian> | |
643 | bool | |
644 | Eh_frame::read_cie(Sized_relobj<size, big_endian>* object, | |
645 | unsigned int shndx, | |
646 | const unsigned char* symbols, | |
647 | off_t symbols_size, | |
648 | const unsigned char* symbol_names, | |
649 | off_t symbol_names_size, | |
650 | const unsigned char* pcontents, | |
651 | const unsigned char* pcie, | |
652 | const unsigned char *pcieend, | |
653 | Track_relocs<size, big_endian>* relocs, | |
654 | Offsets_to_cie* cies, | |
655 | New_cies* new_cies) | |
656 | { | |
657 | bool mergeable = true; | |
658 | ||
659 | // We need to find the personality routine if there is one, since we | |
660 | // can only merge CIEs which use the same routine. We also need to | |
661 | // find the FDE encoding if there is one, so that we can read the PC | |
662 | // from the FDE. | |
663 | ||
664 | const unsigned char* p = pcie; | |
665 | ||
666 | if (pcieend - p < 1) | |
667 | return false; | |
668 | unsigned char version = *p++; | |
669 | if (version != 1 && version != 3) | |
670 | return false; | |
671 | ||
672 | const unsigned char* paug = p; | |
673 | const void* paugendv = memchr(p, '\0', pcieend - p); | |
674 | const unsigned char* paugend = static_cast<const unsigned char*>(paugendv); | |
675 | if (paugend == NULL) | |
676 | return false; | |
677 | p = paugend + 1; | |
678 | ||
679 | if (paug[0] == 'e' && paug[1] == 'h') | |
680 | { | |
681 | // This is a CIE from gcc before version 3.0. We can't merge | |
682 | // these. We can still read the FDEs. | |
683 | mergeable = false; | |
684 | paug += 2; | |
685 | if (*paug != '\0') | |
686 | return false; | |
687 | if (pcieend - p < size / 8) | |
688 | return false; | |
689 | p += size / 8; | |
690 | } | |
691 | ||
692 | // Skip the code alignment. | |
693 | if (!skip_leb128(&p, pcieend)) | |
694 | return false; | |
695 | ||
696 | // Skip the data alignment. | |
697 | if (!skip_leb128(&p, pcieend)) | |
698 | return false; | |
699 | ||
700 | // Skip the return column. | |
701 | if (version == 1) | |
702 | { | |
703 | if (pcieend - p < 1) | |
704 | return false; | |
705 | ++p; | |
706 | } | |
707 | else | |
708 | { | |
709 | if (!skip_leb128(&p, pcieend)) | |
710 | return false; | |
711 | } | |
712 | ||
713 | if (*paug == 'z') | |
714 | { | |
715 | ++paug; | |
716 | // Skip the augmentation size. | |
717 | if (!skip_leb128(&p, pcieend)) | |
718 | return false; | |
719 | } | |
720 | ||
721 | unsigned char fde_encoding = elfcpp::DW_EH_PE_absptr; | |
722 | int per_offset = -1; | |
723 | while (*paug != '\0') | |
724 | { | |
725 | switch (*paug) | |
726 | { | |
727 | case 'L': // LSDA encoding. | |
728 | if (pcieend - p < 1) | |
729 | return false; | |
730 | ++p; | |
731 | break; | |
732 | ||
733 | case 'R': // FDE encoding. | |
734 | if (pcieend - p < 1) | |
735 | return false; | |
736 | fde_encoding = *p; | |
737 | switch (fde_encoding & 7) | |
738 | { | |
739 | case elfcpp::DW_EH_PE_absptr: | |
740 | case elfcpp::DW_EH_PE_udata2: | |
741 | case elfcpp::DW_EH_PE_udata4: | |
742 | case elfcpp::DW_EH_PE_udata8: | |
743 | break; | |
744 | default: | |
745 | return false; | |
746 | } | |
747 | ++p; | |
748 | break; | |
749 | ||
750 | case 'S': | |
751 | break; | |
752 | ||
753 | case 'P': | |
754 | // Personality encoding. | |
755 | { | |
756 | if (pcieend - p < 1) | |
757 | return false; | |
758 | unsigned char per_encoding = *p; | |
759 | ++p; | |
760 | ||
761 | if ((per_encoding & 0x60) == 0x60) | |
762 | return false; | |
763 | unsigned int per_width; | |
764 | switch (per_encoding & 7) | |
765 | { | |
766 | case elfcpp::DW_EH_PE_udata2: | |
767 | per_width = 2; | |
768 | break; | |
769 | case elfcpp::DW_EH_PE_udata4: | |
770 | per_width = 4; | |
771 | break; | |
772 | case elfcpp::DW_EH_PE_udata8: | |
773 | per_width = 8; | |
774 | break; | |
775 | case elfcpp::DW_EH_PE_absptr: | |
776 | per_width = size / 8; | |
777 | break; | |
778 | default: | |
779 | return false; | |
780 | } | |
781 | ||
782 | if ((per_encoding & 0xf0) == elfcpp::DW_EH_PE_aligned) | |
783 | { | |
784 | unsigned int len = p - pcie; | |
785 | len += per_width - 1; | |
786 | len &= ~ (per_width - 1); | |
787 | if (static_cast<unsigned int>(pcieend - p) < len) | |
788 | return false; | |
789 | p += len; | |
790 | } | |
791 | ||
792 | per_offset = p - pcontents; | |
793 | ||
794 | if (static_cast<unsigned int>(pcieend - p) < per_width) | |
795 | return false; | |
796 | p += per_width; | |
797 | } | |
798 | break; | |
799 | ||
800 | default: | |
801 | return false; | |
802 | } | |
803 | ||
804 | ++paug; | |
805 | } | |
806 | ||
807 | const char* personality_name = ""; | |
808 | if (per_offset != -1) | |
809 | { | |
810 | if (relocs->advance(per_offset) > 0) | |
811 | return false; | |
812 | if (relocs->next_offset() != per_offset) | |
813 | return false; | |
814 | ||
815 | unsigned int personality_symndx = relocs->next_symndx(); | |
816 | if (personality_symndx == -1U) | |
817 | return false; | |
818 | ||
819 | if (personality_symndx < object->local_symbol_count()) | |
820 | { | |
821 | // We can only merge this CIE if the personality routine is | |
822 | // a global symbol. We can still read the FDEs. | |
823 | mergeable = false; | |
824 | } | |
825 | else | |
826 | { | |
827 | const int sym_size = elfcpp::Elf_sizes<size>::sym_size; | |
828 | if (personality_symndx >= symbols_size / sym_size) | |
829 | return false; | |
830 | elfcpp::Sym<size, big_endian> sym(symbols | |
831 | + (personality_symndx * sym_size)); | |
832 | unsigned int name_offset = sym.get_st_name(); | |
833 | if (name_offset >= symbol_names_size) | |
834 | return false; | |
835 | personality_name = (reinterpret_cast<const char*>(symbol_names) | |
836 | + name_offset); | |
837 | } | |
838 | ||
839 | int r = relocs->advance(per_offset + 1); | |
840 | gold_assert(r == 1); | |
841 | } | |
842 | ||
843 | if (relocs->advance(pcieend - pcontents) > 0) | |
844 | return false; | |
845 | ||
846 | Cie cie(object, shndx, (pcie - 8) - pcontents, fde_encoding, | |
847 | personality_name, pcie, pcieend - pcie); | |
848 | Cie* cie_pointer = NULL; | |
849 | if (mergeable) | |
850 | { | |
851 | Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie); | |
852 | if (find_cie != this->cie_offsets_.end()) | |
853 | cie_pointer = find_cie->first; | |
854 | else | |
855 | { | |
856 | // See if we already saw this CIE in this object file. | |
857 | for (New_cies::const_iterator pc = new_cies->begin(); | |
858 | pc != new_cies->end(); | |
859 | ++pc) | |
860 | { | |
861 | if (*(pc->first) == cie) | |
862 | { | |
863 | cie_pointer = pc->first; | |
864 | break; | |
865 | } | |
866 | } | |
867 | } | |
868 | } | |
869 | ||
870 | if (cie_pointer == NULL) | |
871 | { | |
872 | cie_pointer = new Cie(cie); | |
873 | new_cies->push_back(std::make_pair(cie_pointer, mergeable)); | |
874 | } | |
875 | else | |
876 | { | |
877 | // We are deleting this CIE. Record that in our mapping from | |
878 | // input sections to the output section. At this point we don't | |
879 | // know for sure that we are doing a special mapping for this | |
880 | // input section, but that's OK--if we don't do a special | |
881 | // mapping, nobody will ever ask for the mapping we add here. | |
882 | this->merge_map_.add_mapping(object, shndx, (pcie - 8) - pcontents, | |
883 | pcieend - (pcie - 8), -1); | |
884 | } | |
885 | ||
886 | // Record this CIE plus the offset in the input section. | |
887 | cies->insert(std::make_pair(pcie - pcontents, cie_pointer)); | |
888 | ||
889 | return true; | |
890 | } | |
891 | ||
892 | // Read an FDE. Return false if we can't parse the information. | |
893 | ||
894 | template<int size, bool big_endian> | |
895 | bool | |
896 | Eh_frame::read_fde(Sized_relobj<size, big_endian>* object, | |
897 | unsigned int shndx, | |
898 | const unsigned char* symbols, | |
899 | off_t symbols_size, | |
900 | const unsigned char* pcontents, | |
901 | unsigned int offset, | |
902 | const unsigned char* pfde, | |
903 | const unsigned char *pfdeend, | |
904 | Track_relocs<size, big_endian>* relocs, | |
905 | Offsets_to_cie* cies) | |
906 | { | |
907 | // OFFSET is the distance between the 4 bytes before PFDE to the | |
908 | // start of the CIE. The offset we recorded for the CIE is 8 bytes | |
909 | // after the start of the CIE--after the length and the zero tag. | |
910 | unsigned int cie_offset = (pfde - 4 - pcontents) - offset + 8; | |
911 | Offsets_to_cie::const_iterator pcie = cies->find(cie_offset); | |
912 | if (pcie == cies->end()) | |
913 | return false; | |
914 | Cie* cie = pcie->second; | |
915 | ||
916 | // The FDE should start with a reloc to the start of the code which | |
917 | // it describes. | |
918 | if (relocs->advance(pfde - pcontents) > 0) | |
919 | return false; | |
920 | ||
921 | if (relocs->next_offset() != pfde - pcontents) | |
922 | return false; | |
923 | ||
924 | unsigned int symndx = relocs->next_symndx(); | |
925 | if (symndx == -1U) | |
926 | return false; | |
927 | ||
928 | // There can be another reloc in the FDE, if the CIE specifies an | |
929 | // LSDA (language specific data area). We currently don't care. We | |
930 | // will care later if we want to optimize the LSDA from an absolute | |
931 | // pointer to a PC relative offset when generating a shared library. | |
932 | relocs->advance(pfdeend - pcontents); | |
933 | ||
934 | unsigned int fde_shndx; | |
935 | const int sym_size = elfcpp::Elf_sizes<size>::sym_size; | |
936 | if (symndx >= symbols_size / sym_size) | |
937 | return false; | |
938 | elfcpp::Sym<size, big_endian> sym(symbols + symndx * sym_size); | |
939 | fde_shndx = sym.get_st_shndx(); | |
940 | ||
941 | if (fde_shndx != elfcpp::SHN_UNDEF | |
942 | && fde_shndx < object->shnum() | |
943 | && !object->is_section_included(fde_shndx)) | |
944 | { | |
945 | // This FDE applies to a section which we are discarding. We | |
946 | // can discard this FDE. | |
947 | this->merge_map_.add_mapping(object, shndx, (pfde - 8) - pcontents, | |
948 | pfdeend - (pfde - 8), -1); | |
949 | return true; | |
950 | } | |
951 | ||
952 | cie->add_fde(new Fde(object, shndx, (pfde - 8) - pcontents, | |
953 | pfde, pfdeend - pfde)); | |
954 | ||
955 | return true; | |
956 | } | |
957 | ||
958 | // Return the number of FDEs. | |
959 | ||
960 | unsigned int | |
961 | Eh_frame::fde_count() const | |
962 | { | |
963 | unsigned int ret = 0; | |
964 | for (Unmergeable_cie_offsets::const_iterator p = | |
965 | this->unmergeable_cie_offsets_.begin(); | |
966 | p != this->unmergeable_cie_offsets_.end(); | |
967 | ++p) | |
968 | ret += p->first->fde_count(); | |
969 | for (Cie_offsets::const_iterator p = this->cie_offsets_.begin(); | |
970 | p != this->cie_offsets_.end(); | |
971 | ++p) | |
972 | ret += p->first->fde_count(); | |
973 | return ret; | |
974 | } | |
975 | ||
976 | // Set the final data size. | |
977 | ||
978 | void | |
27bc2bce | 979 | Eh_frame::set_final_data_size() |
730cdc88 | 980 | { |
27bc2bce | 981 | off_t start_file_offset = this->offset(); |
730cdc88 ILT |
982 | off_t output_offset = 0; |
983 | ||
984 | for (Unmergeable_cie_offsets::iterator p = | |
985 | this->unmergeable_cie_offsets_.begin(); | |
986 | p != this->unmergeable_cie_offsets_.end(); | |
987 | ++p) | |
988 | { | |
989 | p->second = start_file_offset + output_offset; | |
990 | output_offset = p->first->set_output_offset(output_offset, | |
991 | this->addralign(), | |
992 | &this->merge_map_); | |
993 | } | |
994 | ||
995 | for (Cie_offsets::iterator p = this->cie_offsets_.begin(); | |
996 | p != this->cie_offsets_.end(); | |
997 | ++p) | |
998 | { | |
999 | p->second = start_file_offset + output_offset; | |
1000 | output_offset = p->first->set_output_offset(output_offset, | |
1001 | this->addralign(), | |
1002 | &this->merge_map_); | |
1003 | } | |
1004 | ||
1005 | gold_assert((output_offset & (this->addralign() - 1)) == 0); | |
1006 | this->set_data_size(output_offset); | |
1007 | } | |
1008 | ||
1009 | // Return an output offset for an input offset. | |
1010 | ||
1011 | bool | |
1012 | Eh_frame::do_output_offset(const Relobj* object, unsigned int shndx, | |
1013 | off_t offset, off_t* poutput) const | |
1014 | { | |
1015 | return this->merge_map_.get_output_offset(object, shndx, offset, poutput); | |
1016 | } | |
1017 | ||
1018 | // Write the data to the output file. | |
1019 | ||
1020 | void | |
1021 | Eh_frame::do_write(Output_file* of) | |
1022 | { | |
1023 | const off_t offset = this->offset(); | |
1024 | const off_t oview_size = this->data_size(); | |
1025 | unsigned char* const oview = of->get_output_view(offset, oview_size); | |
1026 | ||
1027 | if (parameters->get_size() == 32) | |
1028 | { | |
1029 | if (!parameters->is_big_endian()) | |
1030 | { | |
1031 | #ifdef HAVE_TARGET_32_LITTLE | |
1032 | this->do_sized_write<32, false>(oview); | |
1033 | #else | |
1034 | gold_unreachable(); | |
1035 | #endif | |
1036 | } | |
1037 | else | |
1038 | { | |
1039 | #ifdef HAVE_TARGET_32_BIG | |
1040 | this->do_sized_write<32, true>(oview); | |
1041 | #else | |
1042 | gold_unreachable(); | |
1043 | #endif | |
1044 | } | |
1045 | } | |
1046 | else if (parameters->get_size() == 64) | |
1047 | { | |
1048 | if (!parameters->is_big_endian()) | |
1049 | { | |
1050 | #ifdef HAVE_TARGET_64_LITTLE | |
1051 | this->do_sized_write<64, false>(oview); | |
1052 | #else | |
1053 | gold_unreachable(); | |
1054 | #endif | |
1055 | } | |
1056 | else | |
1057 | { | |
1058 | #ifdef HAVE_TARGET_64_BIG | |
1059 | this->do_sized_write<64, true>(oview); | |
1060 | #else | |
1061 | gold_unreachable(); | |
1062 | #endif | |
1063 | } | |
1064 | } | |
1065 | else | |
1066 | gold_unreachable(); | |
1067 | ||
1068 | of->write_output_view(offset, oview_size, oview); | |
1069 | } | |
1070 | ||
1071 | // Write the data to the output file--template version. | |
1072 | ||
1073 | template<int size, bool big_endian> | |
1074 | void | |
1075 | Eh_frame::do_sized_write(unsigned char* oview) | |
1076 | { | |
1077 | off_t o = 0; | |
1078 | for (Unmergeable_cie_offsets::iterator p = | |
1079 | this->unmergeable_cie_offsets_.begin(); | |
1080 | p != this->unmergeable_cie_offsets_.end(); | |
1081 | ++p) | |
1082 | o = p->first->write<size, big_endian>(oview, o, this->eh_frame_hdr_); | |
1083 | for (Cie_offsets::iterator p = this->cie_offsets_.begin(); | |
1084 | p != this->cie_offsets_.end(); | |
1085 | ++p) | |
1086 | o = p->first->write<size, big_endian>(oview, o, this->eh_frame_hdr_); | |
1087 | } | |
1088 | ||
1089 | #ifdef HAVE_TARGET_32_LITTLE | |
1090 | template | |
1091 | bool | |
1092 | Eh_frame::add_ehframe_input_section<32, false>( | |
1093 | Sized_relobj<32, false>* object, | |
1094 | const unsigned char* symbols, | |
1095 | off_t symbols_size, | |
1096 | const unsigned char* symbol_names, | |
1097 | off_t symbol_names_size, | |
1098 | unsigned int shndx, | |
1099 | unsigned int reloc_shndx, | |
1100 | unsigned int reloc_type); | |
1101 | #endif | |
1102 | ||
1103 | #ifdef HAVE_TARGET_32_BIG | |
1104 | template | |
1105 | bool | |
1106 | Eh_frame::add_ehframe_input_section<32, true>( | |
1107 | Sized_relobj<32, true>* object, | |
1108 | const unsigned char* symbols, | |
1109 | off_t symbols_size, | |
1110 | const unsigned char* symbol_names, | |
1111 | off_t symbol_names_size, | |
1112 | unsigned int shndx, | |
1113 | unsigned int reloc_shndx, | |
1114 | unsigned int reloc_type); | |
1115 | #endif | |
1116 | ||
1117 | #ifdef HAVE_TARGET_64_LITTLE | |
1118 | template | |
1119 | bool | |
1120 | Eh_frame::add_ehframe_input_section<64, false>( | |
1121 | Sized_relobj<64, false>* object, | |
1122 | const unsigned char* symbols, | |
1123 | off_t symbols_size, | |
1124 | const unsigned char* symbol_names, | |
1125 | off_t symbol_names_size, | |
1126 | unsigned int shndx, | |
1127 | unsigned int reloc_shndx, | |
1128 | unsigned int reloc_type); | |
1129 | #endif | |
1130 | ||
1131 | #ifdef HAVE_TARGET_64_BIG | |
1132 | template | |
1133 | bool | |
1134 | Eh_frame::add_ehframe_input_section<64, true>( | |
1135 | Sized_relobj<64, true>* object, | |
1136 | const unsigned char* symbols, | |
1137 | off_t symbols_size, | |
1138 | const unsigned char* symbol_names, | |
1139 | off_t symbol_names_size, | |
1140 | unsigned int shndx, | |
1141 | unsigned int reloc_shndx, | |
1142 | unsigned int reloc_type); | |
1143 | #endif | |
1144 | ||
3151305a | 1145 | } // End namespace gold. |