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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 | |
4117d768 ILT |
237 | Eh_frame_hdr::get_fde_pc( |
238 | typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address, | |
239 | const unsigned char* eh_frame_contents, | |
240 | off_t fde_offset, | |
241 | unsigned char fde_encoding) | |
730cdc88 ILT |
242 | { |
243 | // The FDE starts with a 4 byte length and a 4 byte offset to the | |
244 | // CIE. The PC follows. | |
245 | const unsigned char* p = eh_frame_contents + fde_offset + 8; | |
246 | ||
247 | typename elfcpp::Elf_types<size>::Elf_Addr pc; | |
248 | bool is_signed = (fde_encoding & elfcpp::DW_EH_PE_signed) != 0; | |
249 | int pc_size = fde_encoding & 7; | |
250 | if (pc_size == elfcpp::DW_EH_PE_absptr) | |
251 | { | |
252 | if (size == 32) | |
253 | pc_size = elfcpp::DW_EH_PE_udata4; | |
254 | else if (size == 64) | |
255 | pc_size = elfcpp::DW_EH_PE_udata8; | |
256 | else | |
257 | gold_unreachable(); | |
258 | } | |
259 | ||
260 | switch (pc_size) | |
261 | { | |
262 | case elfcpp::DW_EH_PE_udata2: | |
263 | pc = elfcpp::Swap<16, big_endian>::readval(p); | |
264 | if (is_signed) | |
265 | pc = (pc ^ 0x8000) - 0x8000; | |
266 | break; | |
267 | ||
268 | case elfcpp::DW_EH_PE_udata4: | |
269 | pc = elfcpp::Swap<32, big_endian>::readval(p); | |
270 | if (size > 32 && is_signed) | |
271 | pc = (pc ^ 0x80000000) - 0x80000000; | |
272 | break; | |
273 | ||
274 | case elfcpp::DW_EH_PE_udata8: | |
275 | gold_assert(size == 64); | |
276 | pc = elfcpp::Swap_unaligned<64, big_endian>::readval(p); | |
277 | break; | |
278 | ||
279 | default: | |
4117d768 ILT |
280 | // All other cases were rejected in Eh_frame::read_cie. |
281 | gold_unreachable(); | |
282 | } | |
283 | ||
284 | switch (fde_encoding & 0xf0) | |
285 | { | |
286 | case 0: | |
287 | break; | |
288 | ||
289 | case elfcpp::DW_EH_PE_pcrel: | |
290 | pc += eh_frame_address + fde_offset + 8; | |
291 | break; | |
292 | ||
293 | default: | |
294 | // If other cases arise, then we have to handle them, or we have | |
295 | // to reject them by returning false in Eh_frame::read_cie. | |
730cdc88 ILT |
296 | gold_unreachable(); |
297 | } | |
298 | ||
299 | return pc; | |
300 | } | |
301 | ||
302 | // Given an array of FDE offsets in the .eh_frame section, return an | |
303 | // array of offsets from the exception frame header to the FDE's | |
304 | // output PC and to the output address of the FDE itself. We get the | |
305 | // FDE's PC by actually looking in the .eh_frame section we just wrote | |
306 | // to the output file. | |
307 | ||
308 | template<int size, bool big_endian> | |
309 | void | |
310 | Eh_frame_hdr::get_fde_addresses(Output_file* of, | |
311 | const Fde_offsets* fde_offsets, | |
312 | Fde_addresses<size>* fde_addresses) | |
313 | { | |
314 | typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address; | |
315 | eh_frame_address = this->eh_frame_section_->address(); | |
316 | off_t eh_frame_offset = this->eh_frame_section_->offset(); | |
317 | off_t eh_frame_size = this->eh_frame_section_->data_size(); | |
318 | const unsigned char* eh_frame_contents = of->get_input_view(eh_frame_offset, | |
319 | eh_frame_size); | |
320 | ||
321 | for (Fde_offsets::const_iterator p = fde_offsets->begin(); | |
322 | p != fde_offsets->end(); | |
323 | ++p) | |
324 | { | |
325 | typename elfcpp::Elf_types<size>::Elf_Addr fde_pc; | |
4117d768 ILT |
326 | fde_pc = this->get_fde_pc<size, big_endian>(eh_frame_address, |
327 | eh_frame_contents, | |
730cdc88 ILT |
328 | p->first, p->second); |
329 | fde_addresses->push_back(fde_pc, eh_frame_address + p->first); | |
330 | } | |
331 | ||
332 | of->free_input_view(eh_frame_offset, eh_frame_size, eh_frame_contents); | |
333 | } | |
334 | ||
335 | // Class Fde. | |
336 | ||
337 | // Write the FDE to OVIEW starting at OFFSET. CIE_OFFSET is the | |
338 | // offset of the CIE in OVIEW. FDE_ENCODING is the encoding, from the | |
339 | // CIE. Record the FDE pc for EH_FRAME_HDR. Return the new offset. | |
340 | ||
341 | template<int size, bool big_endian> | |
342 | off_t | |
343 | Fde::write(unsigned char* oview, off_t offset, off_t cie_offset, | |
344 | unsigned char fde_encoding, Eh_frame_hdr* eh_frame_hdr) | |
345 | { | |
346 | size_t length = this->contents_.length(); | |
347 | ||
348 | // Write the length of the FDE as a 32-bit word. The length word | |
349 | // does not include the four bytes of the length word itself, but it | |
350 | // does include the offset to the CIE. | |
351 | elfcpp::Swap<32, big_endian>::writeval(oview + offset, | |
352 | length + 4); | |
353 | ||
354 | // Write the offset to the CIE as a 32-bit word. This is the | |
355 | // difference between the address of the offset word itself and the | |
356 | // CIE address. | |
357 | elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, | |
358 | offset + 4 - cie_offset); | |
359 | ||
360 | // Copy the rest of the FDE. Note that this is run before | |
361 | // relocation processing is done on this section, so the relocations | |
362 | // will later be applied to the FDE data. | |
363 | memcpy(oview + offset + 8, this->contents_.data(), length); | |
364 | ||
365 | // Tell the exception frame header about this FDE. | |
366 | if (eh_frame_hdr != NULL) | |
367 | eh_frame_hdr->record_fde(offset, fde_encoding); | |
368 | ||
369 | return offset + length + 8; | |
370 | } | |
371 | ||
372 | // Class Cie. | |
373 | ||
374 | // Destructor. | |
375 | ||
376 | Cie::~Cie() | |
377 | { | |
378 | for (std::vector<Fde*>::iterator p = this->fdes_.begin(); | |
379 | p != this->fdes_.end(); | |
380 | ++p) | |
381 | delete *p; | |
382 | } | |
383 | ||
384 | // Set the output offset of a CIE. Return the new output offset. | |
385 | ||
386 | off_t | |
387 | Cie::set_output_offset(off_t output_offset, unsigned int addralign, | |
388 | Merge_map* merge_map) | |
389 | { | |
390 | size_t length = this->contents_.length(); | |
391 | gold_assert((length & (addralign - 1)) == 0); | |
392 | // Add 4 for length and 4 for zero CIE identifier tag. | |
393 | length += 8; | |
394 | ||
395 | merge_map->add_mapping(this->object_, this->shndx_, this->input_offset_, | |
396 | length, output_offset); | |
397 | ||
398 | for (std::vector<Fde*>::const_iterator p = this->fdes_.begin(); | |
399 | p != this->fdes_.end(); | |
400 | ++p) | |
401 | { | |
402 | (*p)->add_mapping(output_offset + length, merge_map); | |
403 | ||
404 | size_t fde_length = (*p)->length(); | |
405 | gold_assert((fde_length & (addralign - 1)) == 0); | |
406 | length += fde_length; | |
407 | } | |
408 | ||
409 | return output_offset + length; | |
410 | } | |
411 | ||
412 | // Write the CIE to OVIEW starting at OFFSET. EH_FRAME_HDR is for FDE | |
413 | // recording. Return the new offset. | |
414 | ||
415 | template<int size, bool big_endian> | |
416 | off_t | |
417 | Cie::write(unsigned char* oview, off_t offset, Eh_frame_hdr* eh_frame_hdr) | |
418 | { | |
419 | off_t cie_offset = offset; | |
420 | ||
421 | size_t length = this->contents_.length(); | |
422 | ||
423 | // Write the length of the CIE as a 32-bit word. The length word | |
424 | // does not include the four bytes of the length word itself. | |
425 | elfcpp::Swap<32, big_endian>::writeval(oview + offset, length + 4); | |
426 | ||
427 | // Write the tag which marks this as a CIE: a 32-bit zero. | |
428 | elfcpp::Swap<32, big_endian>::writeval(oview + offset + 4, 0); | |
429 | ||
430 | // Write out the CIE data. | |
431 | memcpy(oview + offset + 8, this->contents_.data(), length); | |
432 | offset += length + 8; | |
433 | ||
434 | // Write out the associated FDEs. | |
435 | unsigned char fde_encoding = this->fde_encoding_; | |
436 | for (std::vector<Fde*>::const_iterator p = this->fdes_.begin(); | |
437 | p != this->fdes_.end(); | |
438 | ++p) | |
439 | offset = (*p)->write<size, big_endian>(oview, offset, cie_offset, | |
440 | fde_encoding, eh_frame_hdr); | |
441 | ||
442 | return offset; | |
443 | } | |
444 | ||
445 | // We track all the CIEs we see, and merge them when possible. This | |
446 | // works because each FDE holds an offset to the relevant CIE: we | |
447 | // rewrite the FDEs to point to the merged CIE. This is worthwhile | |
448 | // because in a typical C++ program many FDEs in many different object | |
449 | // files will use the same CIE. | |
450 | ||
451 | // An equality operator for Cie. | |
452 | ||
453 | bool | |
454 | operator==(const Cie& cie1, const Cie& cie2) | |
455 | { | |
456 | return (cie1.personality_name_ == cie2.personality_name_ | |
457 | && cie1.contents_ == cie2.contents_); | |
458 | } | |
459 | ||
460 | // A less-than operator for Cie. | |
461 | ||
462 | bool | |
463 | operator<(const Cie& cie1, const Cie& cie2) | |
464 | { | |
465 | if (cie1.personality_name_ != cie2.personality_name_) | |
466 | return cie1.personality_name_ < cie2.personality_name_; | |
467 | return cie1.contents_ < cie2.contents_; | |
468 | } | |
469 | ||
470 | // Class Eh_frame. | |
471 | ||
472 | Eh_frame::Eh_frame() | |
473 | : Output_section_data(Output_data::default_alignment()), | |
474 | eh_frame_hdr_(NULL), | |
475 | cie_offsets_(), | |
476 | unmergeable_cie_offsets_(), | |
477 | merge_map_() | |
478 | { | |
479 | } | |
480 | ||
481 | // Skip an LEB128, updating *PP to point to the next character. | |
482 | // Return false if we ran off the end of the string. | |
483 | ||
484 | bool | |
485 | Eh_frame::skip_leb128(const unsigned char** pp, const unsigned char* pend) | |
486 | { | |
487 | const unsigned char* p; | |
488 | for (p = *pp; p < pend; ++p) | |
489 | { | |
490 | if ((*p & 0x80) == 0) | |
491 | { | |
492 | *pp = p + 1; | |
493 | return true; | |
494 | } | |
495 | } | |
496 | return false; | |
497 | } | |
498 | ||
499 | // Add input section SHNDX in OBJECT to an exception frame section. | |
500 | // SYMBOLS is the contents of the symbol table section (size | |
501 | // SYMBOLS_SIZE), SYMBOL_NAMES is the symbol names section (size | |
502 | // SYMBOL_NAMES_SIZE). RELOC_SHNDX is the index of a relocation | |
503 | // section applying to SHNDX, or 0 if none, or -1U if more than one. | |
504 | // RELOC_TYPE is the type of the reloc section if there is one, either | |
505 | // SHT_REL or SHT_RELA. We try to parse the input exception frame | |
506 | // data into our data structures. If we can't do it, we return false | |
507 | // to mean that the section should be handled as a normal input | |
508 | // section. | |
509 | ||
510 | template<int size, bool big_endian> | |
511 | bool | |
512 | Eh_frame::add_ehframe_input_section( | |
513 | Sized_relobj<size, big_endian>* object, | |
514 | const unsigned char* symbols, | |
515 | off_t symbols_size, | |
516 | const unsigned char* symbol_names, | |
517 | off_t symbol_names_size, | |
518 | unsigned int shndx, | |
519 | unsigned int reloc_shndx, | |
520 | unsigned int reloc_type) | |
521 | { | |
522 | // Get the section contents. | |
523 | off_t contents_len; | |
524 | const unsigned char* pcontents = object->section_contents(shndx, | |
525 | &contents_len, | |
526 | false); | |
527 | if (contents_len == 0) | |
528 | return false; | |
529 | ||
530 | // If this is the marker section for the end of the data, then | |
531 | // return false to force it to be handled as an ordinary input | |
532 | // section. If we don't do this, we won't correctly handle the case | |
533 | // of unrecognized .eh_frame sections. | |
534 | if (contents_len == 4 | |
535 | && elfcpp::Swap<32, big_endian>::readval(pcontents) == 0) | |
536 | return false; | |
537 | ||
538 | New_cies new_cies; | |
539 | if (!this->do_add_ehframe_input_section(object, symbols, symbols_size, | |
540 | symbol_names, symbol_names_size, | |
541 | shndx, reloc_shndx, | |
542 | reloc_type, pcontents, | |
543 | contents_len, &new_cies)) | |
544 | { | |
545 | this->eh_frame_hdr_->found_unrecognized_eh_frame_section(); | |
546 | ||
547 | for (New_cies::iterator p = new_cies.begin(); | |
548 | p != new_cies.end(); | |
549 | ++p) | |
550 | delete p->first; | |
551 | ||
552 | return false; | |
553 | } | |
554 | ||
555 | // Now that we know we are using this section, record any new CIEs | |
556 | // that we found. | |
557 | for (New_cies::const_iterator p = new_cies.begin(); | |
558 | p != new_cies.end(); | |
559 | ++p) | |
560 | { | |
561 | uint64_t zero = 0; | |
562 | if (p->second) | |
563 | this->cie_offsets_.insert(std::make_pair(p->first, zero)); | |
564 | else | |
565 | this->unmergeable_cie_offsets_.push_back(std::make_pair(p->first, | |
566 | zero)); | |
567 | } | |
568 | ||
569 | return true; | |
570 | } | |
571 | ||
572 | // The bulk of the implementation of add_ehframe_input_section. | |
573 | ||
574 | template<int size, bool big_endian> | |
575 | bool | |
576 | Eh_frame::do_add_ehframe_input_section( | |
577 | Sized_relobj<size, big_endian>* object, | |
578 | const unsigned char* symbols, | |
579 | off_t symbols_size, | |
580 | const unsigned char* symbol_names, | |
581 | off_t symbol_names_size, | |
582 | unsigned int shndx, | |
583 | unsigned int reloc_shndx, | |
584 | unsigned int reloc_type, | |
585 | const unsigned char* pcontents, | |
586 | off_t contents_len, | |
587 | New_cies* new_cies) | |
588 | { | |
589 | typedef typename elfcpp::Elf_types<size>::Elf_Addr Address; | |
590 | Track_relocs<size, big_endian> relocs; | |
591 | ||
592 | const unsigned char* p = pcontents; | |
593 | const unsigned char* pend = p + contents_len; | |
594 | ||
595 | // Get the contents of the reloc section if any. | |
596 | if (!relocs.initialize(object, reloc_shndx, reloc_type)) | |
597 | return false; | |
598 | ||
599 | // Keep track of which CIEs are at which offsets. | |
600 | Offsets_to_cie cies; | |
601 | ||
602 | while (p < pend) | |
603 | { | |
604 | if (pend - p < 4) | |
605 | return false; | |
606 | ||
607 | // There shouldn't be any relocations here. | |
608 | if (relocs.advance(p + 4 - pcontents) > 0) | |
609 | return false; | |
610 | ||
611 | unsigned int len = elfcpp::Swap<32, big_endian>::readval(p); | |
612 | p += 4; | |
613 | if (len == 0) | |
614 | { | |
615 | // We should only find a zero-length entry at the end of the | |
616 | // section. | |
617 | if (p < pend) | |
618 | return false; | |
619 | break; | |
620 | } | |
621 | // We don't support a 64-bit .eh_frame. | |
622 | if (len == 0xffffffff) | |
623 | return false; | |
624 | if (static_cast<unsigned int>(pend - p) < len) | |
625 | return false; | |
626 | ||
627 | const unsigned char* const pentend = p + len; | |
628 | ||
629 | if (pend - p < 4) | |
630 | return false; | |
631 | if (relocs.advance(p + 4 - pcontents) > 0) | |
632 | return false; | |
633 | ||
634 | unsigned int id = elfcpp::Swap<32, big_endian>::readval(p); | |
635 | p += 4; | |
636 | ||
637 | if (id == 0) | |
638 | { | |
639 | // CIE. | |
640 | if (!this->read_cie(object, shndx, symbols, symbols_size, | |
641 | symbol_names, symbol_names_size, | |
642 | pcontents, p, pentend, &relocs, &cies, | |
643 | new_cies)) | |
644 | return false; | |
645 | } | |
646 | else | |
647 | { | |
648 | // FDE. | |
649 | if (!this->read_fde(object, shndx, symbols, symbols_size, | |
650 | pcontents, id, p, pentend, &relocs, &cies)) | |
651 | return false; | |
652 | } | |
653 | ||
654 | p = pentend; | |
655 | } | |
656 | ||
657 | return true; | |
658 | } | |
659 | ||
660 | // Read a CIE. Return false if we can't parse the information. | |
661 | ||
662 | template<int size, bool big_endian> | |
663 | bool | |
664 | Eh_frame::read_cie(Sized_relobj<size, big_endian>* object, | |
665 | unsigned int shndx, | |
666 | const unsigned char* symbols, | |
667 | off_t symbols_size, | |
668 | const unsigned char* symbol_names, | |
669 | off_t symbol_names_size, | |
670 | const unsigned char* pcontents, | |
671 | const unsigned char* pcie, | |
672 | const unsigned char *pcieend, | |
673 | Track_relocs<size, big_endian>* relocs, | |
674 | Offsets_to_cie* cies, | |
675 | New_cies* new_cies) | |
676 | { | |
677 | bool mergeable = true; | |
678 | ||
679 | // We need to find the personality routine if there is one, since we | |
680 | // can only merge CIEs which use the same routine. We also need to | |
681 | // find the FDE encoding if there is one, so that we can read the PC | |
682 | // from the FDE. | |
683 | ||
684 | const unsigned char* p = pcie; | |
685 | ||
686 | if (pcieend - p < 1) | |
687 | return false; | |
688 | unsigned char version = *p++; | |
689 | if (version != 1 && version != 3) | |
690 | return false; | |
691 | ||
692 | const unsigned char* paug = p; | |
693 | const void* paugendv = memchr(p, '\0', pcieend - p); | |
694 | const unsigned char* paugend = static_cast<const unsigned char*>(paugendv); | |
695 | if (paugend == NULL) | |
696 | return false; | |
697 | p = paugend + 1; | |
698 | ||
699 | if (paug[0] == 'e' && paug[1] == 'h') | |
700 | { | |
701 | // This is a CIE from gcc before version 3.0. We can't merge | |
702 | // these. We can still read the FDEs. | |
703 | mergeable = false; | |
704 | paug += 2; | |
705 | if (*paug != '\0') | |
706 | return false; | |
707 | if (pcieend - p < size / 8) | |
708 | return false; | |
709 | p += size / 8; | |
710 | } | |
711 | ||
712 | // Skip the code alignment. | |
713 | if (!skip_leb128(&p, pcieend)) | |
714 | return false; | |
715 | ||
716 | // Skip the data alignment. | |
717 | if (!skip_leb128(&p, pcieend)) | |
718 | return false; | |
719 | ||
720 | // Skip the return column. | |
721 | if (version == 1) | |
722 | { | |
723 | if (pcieend - p < 1) | |
724 | return false; | |
725 | ++p; | |
726 | } | |
727 | else | |
728 | { | |
729 | if (!skip_leb128(&p, pcieend)) | |
730 | return false; | |
731 | } | |
732 | ||
733 | if (*paug == 'z') | |
734 | { | |
735 | ++paug; | |
736 | // Skip the augmentation size. | |
737 | if (!skip_leb128(&p, pcieend)) | |
738 | return false; | |
739 | } | |
740 | ||
741 | unsigned char fde_encoding = elfcpp::DW_EH_PE_absptr; | |
742 | int per_offset = -1; | |
743 | while (*paug != '\0') | |
744 | { | |
745 | switch (*paug) | |
746 | { | |
747 | case 'L': // LSDA encoding. | |
748 | if (pcieend - p < 1) | |
749 | return false; | |
750 | ++p; | |
751 | break; | |
752 | ||
753 | case 'R': // FDE encoding. | |
754 | if (pcieend - p < 1) | |
755 | return false; | |
756 | fde_encoding = *p; | |
757 | switch (fde_encoding & 7) | |
758 | { | |
759 | case elfcpp::DW_EH_PE_absptr: | |
760 | case elfcpp::DW_EH_PE_udata2: | |
761 | case elfcpp::DW_EH_PE_udata4: | |
762 | case elfcpp::DW_EH_PE_udata8: | |
763 | break; | |
764 | default: | |
4117d768 ILT |
765 | // We don't expect to see any other cases here, and |
766 | // we're not prepared to handle them. | |
730cdc88 ILT |
767 | return false; |
768 | } | |
769 | ++p; | |
770 | break; | |
771 | ||
772 | case 'S': | |
773 | break; | |
774 | ||
775 | case 'P': | |
776 | // Personality encoding. | |
777 | { | |
778 | if (pcieend - p < 1) | |
779 | return false; | |
780 | unsigned char per_encoding = *p; | |
781 | ++p; | |
782 | ||
783 | if ((per_encoding & 0x60) == 0x60) | |
784 | return false; | |
785 | unsigned int per_width; | |
786 | switch (per_encoding & 7) | |
787 | { | |
788 | case elfcpp::DW_EH_PE_udata2: | |
789 | per_width = 2; | |
790 | break; | |
791 | case elfcpp::DW_EH_PE_udata4: | |
792 | per_width = 4; | |
793 | break; | |
794 | case elfcpp::DW_EH_PE_udata8: | |
795 | per_width = 8; | |
796 | break; | |
797 | case elfcpp::DW_EH_PE_absptr: | |
798 | per_width = size / 8; | |
799 | break; | |
800 | default: | |
801 | return false; | |
802 | } | |
803 | ||
804 | if ((per_encoding & 0xf0) == elfcpp::DW_EH_PE_aligned) | |
805 | { | |
806 | unsigned int len = p - pcie; | |
807 | len += per_width - 1; | |
808 | len &= ~ (per_width - 1); | |
809 | if (static_cast<unsigned int>(pcieend - p) < len) | |
810 | return false; | |
811 | p += len; | |
812 | } | |
813 | ||
814 | per_offset = p - pcontents; | |
815 | ||
816 | if (static_cast<unsigned int>(pcieend - p) < per_width) | |
817 | return false; | |
818 | p += per_width; | |
819 | } | |
820 | break; | |
821 | ||
822 | default: | |
823 | return false; | |
824 | } | |
825 | ||
826 | ++paug; | |
827 | } | |
828 | ||
829 | const char* personality_name = ""; | |
830 | if (per_offset != -1) | |
831 | { | |
832 | if (relocs->advance(per_offset) > 0) | |
833 | return false; | |
834 | if (relocs->next_offset() != per_offset) | |
835 | return false; | |
836 | ||
837 | unsigned int personality_symndx = relocs->next_symndx(); | |
838 | if (personality_symndx == -1U) | |
839 | return false; | |
840 | ||
841 | if (personality_symndx < object->local_symbol_count()) | |
842 | { | |
843 | // We can only merge this CIE if the personality routine is | |
844 | // a global symbol. We can still read the FDEs. | |
845 | mergeable = false; | |
846 | } | |
847 | else | |
848 | { | |
849 | const int sym_size = elfcpp::Elf_sizes<size>::sym_size; | |
850 | if (personality_symndx >= symbols_size / sym_size) | |
851 | return false; | |
852 | elfcpp::Sym<size, big_endian> sym(symbols | |
853 | + (personality_symndx * sym_size)); | |
854 | unsigned int name_offset = sym.get_st_name(); | |
855 | if (name_offset >= symbol_names_size) | |
856 | return false; | |
857 | personality_name = (reinterpret_cast<const char*>(symbol_names) | |
858 | + name_offset); | |
859 | } | |
860 | ||
861 | int r = relocs->advance(per_offset + 1); | |
862 | gold_assert(r == 1); | |
863 | } | |
864 | ||
865 | if (relocs->advance(pcieend - pcontents) > 0) | |
866 | return false; | |
867 | ||
868 | Cie cie(object, shndx, (pcie - 8) - pcontents, fde_encoding, | |
869 | personality_name, pcie, pcieend - pcie); | |
870 | Cie* cie_pointer = NULL; | |
871 | if (mergeable) | |
872 | { | |
873 | Cie_offsets::iterator find_cie = this->cie_offsets_.find(&cie); | |
874 | if (find_cie != this->cie_offsets_.end()) | |
875 | cie_pointer = find_cie->first; | |
876 | else | |
877 | { | |
878 | // See if we already saw this CIE in this object file. | |
879 | for (New_cies::const_iterator pc = new_cies->begin(); | |
880 | pc != new_cies->end(); | |
881 | ++pc) | |
882 | { | |
883 | if (*(pc->first) == cie) | |
884 | { | |
885 | cie_pointer = pc->first; | |
886 | break; | |
887 | } | |
888 | } | |
889 | } | |
890 | } | |
891 | ||
892 | if (cie_pointer == NULL) | |
893 | { | |
894 | cie_pointer = new Cie(cie); | |
895 | new_cies->push_back(std::make_pair(cie_pointer, mergeable)); | |
896 | } | |
897 | else | |
898 | { | |
899 | // We are deleting this CIE. Record that in our mapping from | |
900 | // input sections to the output section. At this point we don't | |
901 | // know for sure that we are doing a special mapping for this | |
902 | // input section, but that's OK--if we don't do a special | |
903 | // mapping, nobody will ever ask for the mapping we add here. | |
904 | this->merge_map_.add_mapping(object, shndx, (pcie - 8) - pcontents, | |
905 | pcieend - (pcie - 8), -1); | |
906 | } | |
907 | ||
908 | // Record this CIE plus the offset in the input section. | |
909 | cies->insert(std::make_pair(pcie - pcontents, cie_pointer)); | |
910 | ||
911 | return true; | |
912 | } | |
913 | ||
914 | // Read an FDE. Return false if we can't parse the information. | |
915 | ||
916 | template<int size, bool big_endian> | |
917 | bool | |
918 | Eh_frame::read_fde(Sized_relobj<size, big_endian>* object, | |
919 | unsigned int shndx, | |
920 | const unsigned char* symbols, | |
921 | off_t symbols_size, | |
922 | const unsigned char* pcontents, | |
923 | unsigned int offset, | |
924 | const unsigned char* pfde, | |
925 | const unsigned char *pfdeend, | |
926 | Track_relocs<size, big_endian>* relocs, | |
927 | Offsets_to_cie* cies) | |
928 | { | |
929 | // OFFSET is the distance between the 4 bytes before PFDE to the | |
930 | // start of the CIE. The offset we recorded for the CIE is 8 bytes | |
931 | // after the start of the CIE--after the length and the zero tag. | |
932 | unsigned int cie_offset = (pfde - 4 - pcontents) - offset + 8; | |
933 | Offsets_to_cie::const_iterator pcie = cies->find(cie_offset); | |
934 | if (pcie == cies->end()) | |
935 | return false; | |
936 | Cie* cie = pcie->second; | |
937 | ||
938 | // The FDE should start with a reloc to the start of the code which | |
939 | // it describes. | |
940 | if (relocs->advance(pfde - pcontents) > 0) | |
941 | return false; | |
942 | ||
943 | if (relocs->next_offset() != pfde - pcontents) | |
944 | return false; | |
945 | ||
946 | unsigned int symndx = relocs->next_symndx(); | |
947 | if (symndx == -1U) | |
948 | return false; | |
949 | ||
950 | // There can be another reloc in the FDE, if the CIE specifies an | |
951 | // LSDA (language specific data area). We currently don't care. We | |
952 | // will care later if we want to optimize the LSDA from an absolute | |
953 | // pointer to a PC relative offset when generating a shared library. | |
954 | relocs->advance(pfdeend - pcontents); | |
955 | ||
956 | unsigned int fde_shndx; | |
957 | const int sym_size = elfcpp::Elf_sizes<size>::sym_size; | |
958 | if (symndx >= symbols_size / sym_size) | |
959 | return false; | |
960 | elfcpp::Sym<size, big_endian> sym(symbols + symndx * sym_size); | |
961 | fde_shndx = sym.get_st_shndx(); | |
962 | ||
963 | if (fde_shndx != elfcpp::SHN_UNDEF | |
964 | && fde_shndx < object->shnum() | |
965 | && !object->is_section_included(fde_shndx)) | |
966 | { | |
967 | // This FDE applies to a section which we are discarding. We | |
968 | // can discard this FDE. | |
969 | this->merge_map_.add_mapping(object, shndx, (pfde - 8) - pcontents, | |
970 | pfdeend - (pfde - 8), -1); | |
971 | return true; | |
972 | } | |
973 | ||
974 | cie->add_fde(new Fde(object, shndx, (pfde - 8) - pcontents, | |
975 | pfde, pfdeend - pfde)); | |
976 | ||
977 | return true; | |
978 | } | |
979 | ||
980 | // Return the number of FDEs. | |
981 | ||
982 | unsigned int | |
983 | Eh_frame::fde_count() const | |
984 | { | |
985 | unsigned int ret = 0; | |
986 | for (Unmergeable_cie_offsets::const_iterator p = | |
987 | this->unmergeable_cie_offsets_.begin(); | |
988 | p != this->unmergeable_cie_offsets_.end(); | |
989 | ++p) | |
990 | ret += p->first->fde_count(); | |
991 | for (Cie_offsets::const_iterator p = this->cie_offsets_.begin(); | |
992 | p != this->cie_offsets_.end(); | |
993 | ++p) | |
994 | ret += p->first->fde_count(); | |
995 | return ret; | |
996 | } | |
997 | ||
998 | // Set the final data size. | |
999 | ||
1000 | void | |
27bc2bce | 1001 | Eh_frame::set_final_data_size() |
730cdc88 | 1002 | { |
27bc2bce | 1003 | off_t start_file_offset = this->offset(); |
730cdc88 ILT |
1004 | off_t output_offset = 0; |
1005 | ||
1006 | for (Unmergeable_cie_offsets::iterator p = | |
1007 | this->unmergeable_cie_offsets_.begin(); | |
1008 | p != this->unmergeable_cie_offsets_.end(); | |
1009 | ++p) | |
1010 | { | |
1011 | p->second = start_file_offset + output_offset; | |
1012 | output_offset = p->first->set_output_offset(output_offset, | |
1013 | this->addralign(), | |
1014 | &this->merge_map_); | |
1015 | } | |
1016 | ||
1017 | for (Cie_offsets::iterator p = this->cie_offsets_.begin(); | |
1018 | p != this->cie_offsets_.end(); | |
1019 | ++p) | |
1020 | { | |
1021 | p->second = start_file_offset + output_offset; | |
1022 | output_offset = p->first->set_output_offset(output_offset, | |
1023 | this->addralign(), | |
1024 | &this->merge_map_); | |
1025 | } | |
1026 | ||
1027 | gold_assert((output_offset & (this->addralign() - 1)) == 0); | |
1028 | this->set_data_size(output_offset); | |
1029 | } | |
1030 | ||
1031 | // Return an output offset for an input offset. | |
1032 | ||
1033 | bool | |
1034 | Eh_frame::do_output_offset(const Relobj* object, unsigned int shndx, | |
1035 | off_t offset, off_t* poutput) const | |
1036 | { | |
1037 | return this->merge_map_.get_output_offset(object, shndx, offset, poutput); | |
1038 | } | |
1039 | ||
1040 | // Write the data to the output file. | |
1041 | ||
1042 | void | |
1043 | Eh_frame::do_write(Output_file* of) | |
1044 | { | |
1045 | const off_t offset = this->offset(); | |
1046 | const off_t oview_size = this->data_size(); | |
1047 | unsigned char* const oview = of->get_output_view(offset, oview_size); | |
1048 | ||
1049 | if (parameters->get_size() == 32) | |
1050 | { | |
1051 | if (!parameters->is_big_endian()) | |
1052 | { | |
1053 | #ifdef HAVE_TARGET_32_LITTLE | |
1054 | this->do_sized_write<32, false>(oview); | |
1055 | #else | |
1056 | gold_unreachable(); | |
1057 | #endif | |
1058 | } | |
1059 | else | |
1060 | { | |
1061 | #ifdef HAVE_TARGET_32_BIG | |
1062 | this->do_sized_write<32, true>(oview); | |
1063 | #else | |
1064 | gold_unreachable(); | |
1065 | #endif | |
1066 | } | |
1067 | } | |
1068 | else if (parameters->get_size() == 64) | |
1069 | { | |
1070 | if (!parameters->is_big_endian()) | |
1071 | { | |
1072 | #ifdef HAVE_TARGET_64_LITTLE | |
1073 | this->do_sized_write<64, false>(oview); | |
1074 | #else | |
1075 | gold_unreachable(); | |
1076 | #endif | |
1077 | } | |
1078 | else | |
1079 | { | |
1080 | #ifdef HAVE_TARGET_64_BIG | |
1081 | this->do_sized_write<64, true>(oview); | |
1082 | #else | |
1083 | gold_unreachable(); | |
1084 | #endif | |
1085 | } | |
1086 | } | |
1087 | else | |
1088 | gold_unreachable(); | |
1089 | ||
1090 | of->write_output_view(offset, oview_size, oview); | |
1091 | } | |
1092 | ||
1093 | // Write the data to the output file--template version. | |
1094 | ||
1095 | template<int size, bool big_endian> | |
1096 | void | |
1097 | Eh_frame::do_sized_write(unsigned char* oview) | |
1098 | { | |
1099 | off_t o = 0; | |
1100 | for (Unmergeable_cie_offsets::iterator p = | |
1101 | this->unmergeable_cie_offsets_.begin(); | |
1102 | p != this->unmergeable_cie_offsets_.end(); | |
1103 | ++p) | |
1104 | o = p->first->write<size, big_endian>(oview, o, this->eh_frame_hdr_); | |
1105 | for (Cie_offsets::iterator p = this->cie_offsets_.begin(); | |
1106 | p != this->cie_offsets_.end(); | |
1107 | ++p) | |
1108 | o = p->first->write<size, big_endian>(oview, o, this->eh_frame_hdr_); | |
1109 | } | |
1110 | ||
1111 | #ifdef HAVE_TARGET_32_LITTLE | |
1112 | template | |
1113 | bool | |
1114 | Eh_frame::add_ehframe_input_section<32, false>( | |
1115 | Sized_relobj<32, false>* object, | |
1116 | const unsigned char* symbols, | |
1117 | off_t symbols_size, | |
1118 | const unsigned char* symbol_names, | |
1119 | off_t symbol_names_size, | |
1120 | unsigned int shndx, | |
1121 | unsigned int reloc_shndx, | |
1122 | unsigned int reloc_type); | |
1123 | #endif | |
1124 | ||
1125 | #ifdef HAVE_TARGET_32_BIG | |
1126 | template | |
1127 | bool | |
1128 | Eh_frame::add_ehframe_input_section<32, true>( | |
1129 | Sized_relobj<32, true>* object, | |
1130 | const unsigned char* symbols, | |
1131 | off_t symbols_size, | |
1132 | const unsigned char* symbol_names, | |
1133 | off_t symbol_names_size, | |
1134 | unsigned int shndx, | |
1135 | unsigned int reloc_shndx, | |
1136 | unsigned int reloc_type); | |
1137 | #endif | |
1138 | ||
1139 | #ifdef HAVE_TARGET_64_LITTLE | |
1140 | template | |
1141 | bool | |
1142 | Eh_frame::add_ehframe_input_section<64, false>( | |
1143 | Sized_relobj<64, false>* object, | |
1144 | const unsigned char* symbols, | |
1145 | off_t symbols_size, | |
1146 | const unsigned char* symbol_names, | |
1147 | off_t symbol_names_size, | |
1148 | unsigned int shndx, | |
1149 | unsigned int reloc_shndx, | |
1150 | unsigned int reloc_type); | |
1151 | #endif | |
1152 | ||
1153 | #ifdef HAVE_TARGET_64_BIG | |
1154 | template | |
1155 | bool | |
1156 | Eh_frame::add_ehframe_input_section<64, true>( | |
1157 | Sized_relobj<64, true>* object, | |
1158 | const unsigned char* symbols, | |
1159 | off_t symbols_size, | |
1160 | const unsigned char* symbol_names, | |
1161 | off_t symbol_names_size, | |
1162 | unsigned int shndx, | |
1163 | unsigned int reloc_shndx, | |
1164 | unsigned int reloc_type); | |
1165 | #endif | |
1166 | ||
3151305a | 1167 | } // End namespace gold. |