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3151305a ILT |
1 | // ehframe.h -- handle exception frame sections for gold -*- C++ -*- |
2 | ||
07a60597 | 3 | // Copyright 2006, 2007, 2008, 2010, 2011 Free Software Foundation, Inc. |
3151305a ILT |
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 | #ifndef GOLD_EHFRAME_H | |
24 | #define GOLD_EHFRAME_H | |
25 | ||
1cac254c ILT |
26 | #include <map> |
27 | #include <set> | |
28 | #include <vector> | |
29 | ||
3151305a | 30 | #include "output.h" |
730cdc88 | 31 | #include "merge.h" |
3151305a ILT |
32 | |
33 | namespace gold | |
34 | { | |
35 | ||
730cdc88 ILT |
36 | template<int size, bool big_endian> |
37 | class Track_relocs; | |
38 | ||
39 | class Eh_frame; | |
40 | ||
3151305a ILT |
41 | // This class manages the .eh_frame_hdr section, which holds the data |
42 | // for the PT_GNU_EH_FRAME segment. gcc's unwind support code uses | |
43 | // the PT_GNU_EH_FRAME segment to find the list of FDEs. This saves | |
44 | // the time required to register the exception handlers at startup | |
45 | // time and when a shared object is loaded, and the time required to | |
46 | // deregister the exception handlers when a shared object is unloaded. | |
47 | ||
3151305a ILT |
48 | class Eh_frame_hdr : public Output_section_data |
49 | { | |
50 | public: | |
730cdc88 ILT |
51 | Eh_frame_hdr(Output_section* eh_frame_section, const Eh_frame*); |
52 | ||
53 | // Record that we found an unrecognized .eh_frame section. | |
54 | void | |
55 | found_unrecognized_eh_frame_section() | |
56 | { this->any_unrecognized_eh_frame_sections_ = true; } | |
57 | ||
58 | // Record an FDE. | |
59 | void | |
8383303e | 60 | record_fde(section_offset_type fde_offset, unsigned char fde_encoding) |
730cdc88 ILT |
61 | { |
62 | if (!this->any_unrecognized_eh_frame_sections_) | |
63 | this->fde_offsets_.push_back(std::make_pair(fde_offset, fde_encoding)); | |
64 | } | |
3151305a | 65 | |
7d9e3d98 | 66 | protected: |
3151305a ILT |
67 | // Set the final data size. |
68 | void | |
27bc2bce | 69 | set_final_data_size(); |
3151305a ILT |
70 | |
71 | // Write the data to the file. | |
72 | void | |
73 | do_write(Output_file*); | |
74 | ||
7d9e3d98 ILT |
75 | // Write to a map file. |
76 | void | |
77 | do_print_to_mapfile(Mapfile* mapfile) const | |
78 | { mapfile->print_output_data(this, _("** eh_frame_hdr")); } | |
79 | ||
3151305a | 80 | private: |
730cdc88 ILT |
81 | // Write the data to the file with the right endianness. |
82 | template<int size, bool big_endian> | |
83 | void | |
84 | do_sized_write(Output_file*); | |
85 | ||
86 | // The data we record for one FDE: the offset of the FDE within the | |
87 | // .eh_frame section, and the FDE encoding. | |
8383303e | 88 | typedef std::pair<section_offset_type, unsigned char> Fde_offset; |
730cdc88 ILT |
89 | |
90 | // The list of information we record for an FDE. | |
91 | typedef std::vector<Fde_offset> Fde_offsets; | |
92 | ||
93 | // When writing out the header, we convert the FDE offsets into FDE | |
94 | // addresses. This is a list of pairs of the offset from the header | |
95 | // to the FDE PC and to the FDE itself. | |
96 | template<int size> | |
97 | class Fde_addresses | |
98 | { | |
99 | public: | |
100 | typedef typename elfcpp::Elf_types<size>::Elf_Addr Address; | |
101 | typedef typename std::pair<Address, Address> Fde_address; | |
102 | typedef typename std::vector<Fde_address> Fde_address_list; | |
103 | typedef typename Fde_address_list::iterator iterator; | |
104 | ||
105 | Fde_addresses(unsigned int reserve) | |
106 | : fde_addresses_() | |
107 | { this->fde_addresses_.reserve(reserve); } | |
108 | ||
109 | void | |
110 | push_back(Address pc_address, Address fde_address) | |
111 | { | |
112 | this->fde_addresses_.push_back(std::make_pair(pc_address, fde_address)); | |
113 | } | |
114 | ||
115 | iterator | |
116 | begin() | |
117 | { return this->fde_addresses_.begin(); } | |
118 | ||
119 | iterator | |
120 | end() | |
121 | { return this->fde_addresses_.end(); } | |
122 | ||
123 | private: | |
124 | Fde_address_list fde_addresses_; | |
125 | }; | |
126 | ||
127 | // Compare Fde_address objects. | |
128 | template<int size> | |
129 | struct Fde_address_compare | |
130 | { | |
131 | bool | |
132 | operator()(const typename Fde_addresses<size>::Fde_address& f1, | |
133 | const typename Fde_addresses<size>::Fde_address& f2) const | |
134 | { return f1.first < f2.first; } | |
135 | }; | |
136 | ||
137 | // Return the PC to which an FDE refers. | |
138 | template<int size, bool big_endian> | |
139 | typename elfcpp::Elf_types<size>::Elf_Addr | |
4117d768 ILT |
140 | get_fde_pc(typename elfcpp::Elf_types<size>::Elf_Addr eh_frame_address, |
141 | const unsigned char* eh_frame_contents, | |
8383303e | 142 | section_offset_type fde_offset, unsigned char fde_encoding); |
730cdc88 ILT |
143 | |
144 | // Convert Fde_offsets to Fde_addresses. | |
145 | template<int size, bool big_endian> | |
146 | void | |
147 | get_fde_addresses(Output_file* of, | |
148 | const Fde_offsets* fde_offsets, | |
149 | Fde_addresses<size>* fde_addresses); | |
150 | ||
3151305a ILT |
151 | // The .eh_frame section. |
152 | Output_section* eh_frame_section_; | |
730cdc88 ILT |
153 | // The .eh_frame section data. |
154 | const Eh_frame* eh_frame_data_; | |
155 | // Data from the FDEs in the .eh_frame sections. | |
156 | Fde_offsets fde_offsets_; | |
157 | // Whether we found any .eh_frame sections which we could not | |
158 | // process. | |
159 | bool any_unrecognized_eh_frame_sections_; | |
160 | }; | |
161 | ||
162 | // This class holds an FDE. | |
163 | ||
164 | class Fde | |
165 | { | |
166 | public: | |
8383303e | 167 | Fde(Relobj* object, unsigned int shndx, section_offset_type input_offset, |
2ea97941 | 168 | const unsigned char* contents, size_t length) |
07a60597 | 169 | : object_(object), |
2ea97941 | 170 | contents_(reinterpret_cast<const char*>(contents), length) |
07a60597 ILT |
171 | { |
172 | this->u_.from_object.shndx = shndx; | |
173 | this->u_.from_object.input_offset = input_offset; | |
174 | } | |
175 | ||
176 | // Create an FDE associated with a PLT. | |
177 | Fde(Output_data* plt, const unsigned char* contents, size_t length) | |
178 | : object_(NULL), | |
179 | contents_(reinterpret_cast<const char*>(contents), length) | |
180 | { this->u_.from_linker.plt = plt; } | |
730cdc88 ILT |
181 | |
182 | // Return the length of this FDE. Add 4 for the length and 4 for | |
183 | // the offset to the CIE. | |
184 | size_t | |
185 | length() const | |
186 | { return this->contents_.length() + 8; } | |
187 | ||
07a60597 ILT |
188 | // Add a mapping for this FDE to MERGE_MAP, so that relocations |
189 | // against the FDE are applied to right part of the output file. | |
730cdc88 | 190 | void |
8383303e | 191 | add_mapping(section_offset_type output_offset, Merge_map* merge_map) const |
730cdc88 | 192 | { |
07a60597 ILT |
193 | if (this->object_ != NULL) |
194 | merge_map->add_mapping(this->object_, this->u_.from_object.shndx, | |
195 | this->u_.from_object.input_offset, this->length(), | |
196 | output_offset); | |
730cdc88 ILT |
197 | } |
198 | ||
199 | // Write the FDE to OVIEW starting at OFFSET. FDE_ENCODING is the | |
935e8877 | 200 | // encoding, from the CIE. Round up the bytes to ADDRALIGN if |
07a60597 ILT |
201 | // necessary. ADDRESS is the virtual address of OVIEW. Record the |
202 | // FDE in EH_FRAME_HDR. Return the new offset. | |
730cdc88 | 203 | template<int size, bool big_endian> |
8383303e ILT |
204 | section_offset_type |
205 | write(unsigned char* oview, section_offset_type offset, | |
07a60597 ILT |
206 | uint64_t address, unsigned int addralign, |
207 | section_offset_type cie_offset, unsigned char fde_encoding, | |
208 | Eh_frame_hdr* eh_frame_hdr); | |
730cdc88 ILT |
209 | |
210 | private: | |
07a60597 ILT |
211 | // The object in which this FDE was seen. This will be NULL for a |
212 | // linker generated FDE. | |
730cdc88 | 213 | Relobj* object_; |
07a60597 ILT |
214 | union |
215 | { | |
216 | // These fields are used if the FDE is from an input object (the | |
217 | // object_ field is not NULL). | |
218 | struct | |
219 | { | |
220 | // Input section index for this FDE. | |
221 | unsigned int shndx; | |
222 | // Offset within the input section for this FDE. | |
223 | section_offset_type input_offset; | |
224 | } from_object; | |
225 | // This field is used if the FDE is generated by the linker (the | |
226 | // object_ field is NULL). | |
227 | struct | |
228 | { | |
229 | // The only linker generated FDEs are for PLT sections, and this | |
230 | // points to the PLT section. | |
231 | Output_data* plt; | |
232 | } from_linker; | |
233 | } u_; | |
730cdc88 ILT |
234 | // FDE data. |
235 | std::string contents_; | |
236 | }; | |
237 | ||
238 | // This class holds a CIE. | |
239 | ||
240 | class Cie | |
241 | { | |
242 | public: | |
8383303e | 243 | Cie(Relobj* object, unsigned int shndx, section_offset_type input_offset, |
730cdc88 ILT |
244 | unsigned char fde_encoding, const char* personality_name, |
245 | const unsigned char* contents, size_t length) | |
246 | : object_(object), | |
247 | shndx_(shndx), | |
248 | input_offset_(input_offset), | |
249 | fde_encoding_(fde_encoding), | |
250 | personality_name_(personality_name), | |
251 | fdes_(), | |
252 | contents_(reinterpret_cast<const char*>(contents), length) | |
253 | { } | |
254 | ||
255 | ~Cie(); | |
256 | ||
257 | // We permit copying a CIE when there are no FDEs. This is | |
258 | // convenient in the code which creates them. | |
259 | Cie(const Cie& cie) | |
260 | : object_(cie.object_), | |
261 | shndx_(cie.shndx_), | |
262 | input_offset_(cie.input_offset_), | |
263 | fde_encoding_(cie.fde_encoding_), | |
264 | personality_name_(cie.personality_name_), | |
265 | fdes_(), | |
266 | contents_(cie.contents_) | |
267 | { gold_assert(cie.fdes_.empty()); } | |
268 | ||
269 | // Add an FDE associated with this CIE. | |
270 | void | |
271 | add_fde(Fde* fde) | |
272 | { this->fdes_.push_back(fde); } | |
273 | ||
274 | // Return the number of FDEs. | |
275 | unsigned int | |
276 | fde_count() const | |
277 | { return this->fdes_.size(); } | |
278 | ||
279 | // Set the output offset of this CIE to OUTPUT_OFFSET. It will be | |
280 | // followed by all its FDEs. ADDRALIGN is the required address | |
281 | // alignment, typically 4 or 8. This updates MERGE_MAP with the | |
282 | // mapping. It returns the new output offset. | |
8383303e ILT |
283 | section_offset_type |
284 | set_output_offset(section_offset_type output_offset, unsigned int addralign, | |
285 | Merge_map*); | |
730cdc88 ILT |
286 | |
287 | // Write the CIE to OVIEW starting at OFFSET. EH_FRAME_HDR is the | |
935e8877 | 288 | // exception frame header for FDE recording. Round up the bytes to |
07a60597 ILT |
289 | // ADDRALIGN. ADDRESS is the virtual address of OVIEW. Return the |
290 | // new offset. | |
730cdc88 | 291 | template<int size, bool big_endian> |
8383303e | 292 | section_offset_type |
07a60597 | 293 | write(unsigned char* oview, section_offset_type offset, uint64_t address, |
935e8877 | 294 | unsigned int addralign, Eh_frame_hdr* eh_frame_hdr); |
730cdc88 ILT |
295 | |
296 | friend bool operator<(const Cie&, const Cie&); | |
297 | friend bool operator==(const Cie&, const Cie&); | |
298 | ||
299 | private: | |
300 | // The class is not assignable. | |
301 | Cie& operator=(const Cie&); | |
302 | ||
07a60597 ILT |
303 | // The object in which this CIE was first seen. This will be NULL |
304 | // for a linker generated CIE. | |
730cdc88 | 305 | Relobj* object_; |
07a60597 ILT |
306 | // Input section index for this CIE. This will be 0 for a linker |
307 | // generated CIE. | |
730cdc88 | 308 | unsigned int shndx_; |
07a60597 ILT |
309 | // Offset within the input section for this CIE. This will be 0 for |
310 | // a linker generated CIE. | |
8383303e | 311 | section_offset_type input_offset_; |
730cdc88 ILT |
312 | // The encoding of the FDE. This is a DW_EH_PE code. |
313 | unsigned char fde_encoding_; | |
314 | // The name of the personality routine. This will be the name of a | |
315 | // global symbol, or will be the empty string. | |
316 | std::string personality_name_; | |
317 | // List of FDEs. | |
318 | std::vector<Fde*> fdes_; | |
319 | // CIE data. | |
320 | std::string contents_; | |
321 | }; | |
322 | ||
323 | extern bool operator<(const Cie&, const Cie&); | |
324 | extern bool operator==(const Cie&, const Cie&); | |
325 | ||
326 | // This class manages .eh_frame sections. It discards duplicate | |
327 | // exception information. | |
328 | ||
329 | class Eh_frame : public Output_section_data | |
330 | { | |
331 | public: | |
332 | Eh_frame(); | |
333 | ||
334 | // Record the associated Eh_frame_hdr, if any. | |
335 | void | |
336 | set_eh_frame_hdr(Eh_frame_hdr* hdr) | |
337 | { this->eh_frame_hdr_ = hdr; } | |
338 | ||
339 | // Add the input section SHNDX in OBJECT. SYMBOLS is the contents | |
340 | // of the symbol table section (size SYMBOLS_SIZE), SYMBOL_NAMES is | |
341 | // the symbol names section (size SYMBOL_NAMES_SIZE). RELOC_SHNDX | |
342 | // is the relocation section if any (0 for none, -1U for multiple). | |
343 | // RELOC_TYPE is the type of the relocation section if any. This | |
344 | // returns whether the section was incorporated into the .eh_frame | |
345 | // data. | |
346 | template<int size, bool big_endian> | |
347 | bool | |
6fa2a40b | 348 | add_ehframe_input_section(Sized_relobj_file<size, big_endian>* object, |
730cdc88 | 349 | const unsigned char* symbols, |
8383303e | 350 | section_size_type symbols_size, |
730cdc88 | 351 | const unsigned char* symbol_names, |
8383303e | 352 | section_size_type symbol_names_size, |
730cdc88 ILT |
353 | unsigned int shndx, unsigned int reloc_shndx, |
354 | unsigned int reloc_type); | |
355 | ||
07a60597 ILT |
356 | // Add a CIE and an FDE for a PLT section, to permit unwinding |
357 | // through a PLT. The FDE data should start with 8 bytes of zero, | |
358 | // which will be replaced by a 4 byte PC relative reference to the | |
359 | // address of PLT and a 4 byte size of PLT. | |
360 | void | |
361 | add_ehframe_for_plt(Output_data* plt, const unsigned char* cie_data, | |
362 | size_t cie_length, const unsigned char* fde_data, | |
363 | size_t fde_length); | |
364 | ||
730cdc88 ILT |
365 | // Return the number of FDEs. |
366 | unsigned int | |
367 | fde_count() const; | |
368 | ||
7d9e3d98 | 369 | protected: |
730cdc88 ILT |
370 | // Set the final data size. |
371 | void | |
27bc2bce | 372 | set_final_data_size(); |
730cdc88 ILT |
373 | |
374 | // Return the output address for an input address. | |
375 | bool | |
8383303e ILT |
376 | do_output_offset(const Relobj*, unsigned int shndx, |
377 | section_offset_type offset, | |
378 | section_offset_type* poutput) const; | |
730cdc88 | 379 | |
a9a60db6 ILT |
380 | // Return whether this is the merge section for an input section. |
381 | bool | |
382 | do_is_merge_section_for(const Relobj*, unsigned int shndx) const; | |
383 | ||
730cdc88 ILT |
384 | // Write the data to the file. |
385 | void | |
386 | do_write(Output_file*); | |
387 | ||
7d9e3d98 ILT |
388 | // Write to a map file. |
389 | void | |
390 | do_print_to_mapfile(Mapfile* mapfile) const | |
391 | { mapfile->print_output_data(this, _("** eh_frame")); } | |
392 | ||
730cdc88 ILT |
393 | private: |
394 | // The comparison routine for the CIE map. | |
395 | struct Cie_less | |
396 | { | |
397 | bool | |
398 | operator()(const Cie* cie1, const Cie* cie2) const | |
399 | { return *cie1 < *cie2; } | |
400 | }; | |
401 | ||
1cac254c ILT |
402 | // A set of unique CIEs. |
403 | typedef std::set<Cie*, Cie_less> Cie_offsets; | |
730cdc88 | 404 | |
1cac254c ILT |
405 | // A list of unmergeable CIEs. |
406 | typedef std::vector<Cie*> Unmergeable_cie_offsets; | |
730cdc88 ILT |
407 | |
408 | // A mapping from offsets to CIEs. This is used while reading an | |
409 | // input section. | |
410 | typedef std::map<uint64_t, Cie*> Offsets_to_cie; | |
411 | ||
412 | // A list of CIEs, and a bool indicating whether the CIE is | |
413 | // mergeable. | |
414 | typedef std::vector<std::pair<Cie*, bool> > New_cies; | |
415 | ||
416 | // Skip an LEB128. | |
417 | static bool | |
418 | skip_leb128(const unsigned char**, const unsigned char*); | |
419 | ||
420 | // The implementation of add_ehframe_input_section. | |
421 | template<int size, bool big_endian> | |
422 | bool | |
6fa2a40b | 423 | do_add_ehframe_input_section(Sized_relobj_file<size, big_endian>* object, |
730cdc88 | 424 | const unsigned char* symbols, |
8383303e | 425 | section_size_type symbols_size, |
730cdc88 | 426 | const unsigned char* symbol_names, |
8383303e | 427 | section_size_type symbol_names_size, |
730cdc88 ILT |
428 | unsigned int shndx, |
429 | unsigned int reloc_shndx, | |
430 | unsigned int reloc_type, | |
431 | const unsigned char* pcontents, | |
8383303e | 432 | section_size_type contents_len, |
730cdc88 ILT |
433 | New_cies*); |
434 | ||
435 | // Read a CIE. | |
436 | template<int size, bool big_endian> | |
437 | bool | |
6fa2a40b | 438 | read_cie(Sized_relobj_file<size, big_endian>* object, |
730cdc88 ILT |
439 | unsigned int shndx, |
440 | const unsigned char* symbols, | |
8383303e | 441 | section_size_type symbols_size, |
730cdc88 | 442 | const unsigned char* symbol_names, |
8383303e | 443 | section_size_type symbol_names_size, |
730cdc88 ILT |
444 | const unsigned char* pcontents, |
445 | const unsigned char* pcie, | |
ca09d69a | 446 | const unsigned char* pcieend, |
730cdc88 ILT |
447 | Track_relocs<size, big_endian>* relocs, |
448 | Offsets_to_cie* cies, | |
449 | New_cies* new_cies); | |
450 | ||
451 | // Read an FDE. | |
452 | template<int size, bool big_endian> | |
453 | bool | |
6fa2a40b | 454 | read_fde(Sized_relobj_file<size, big_endian>* object, |
730cdc88 ILT |
455 | unsigned int shndx, |
456 | const unsigned char* symbols, | |
8383303e | 457 | section_size_type symbols_size, |
730cdc88 ILT |
458 | const unsigned char* pcontents, |
459 | unsigned int offset, | |
460 | const unsigned char* pfde, | |
ca09d69a | 461 | const unsigned char* pfdeend, |
730cdc88 ILT |
462 | Track_relocs<size, big_endian>* relocs, |
463 | Offsets_to_cie* cies); | |
464 | ||
465 | // Template version of write function. | |
466 | template<int size, bool big_endian> | |
467 | void | |
468 | do_sized_write(unsigned char* oview); | |
469 | ||
470 | // The exception frame header, if any. | |
471 | Eh_frame_hdr* eh_frame_hdr_; | |
472 | // A mapping from all unique CIEs to their offset in the output | |
473 | // file. | |
474 | Cie_offsets cie_offsets_; | |
475 | // A mapping from unmergeable CIEs to their offset in the output | |
476 | // file. | |
477 | Unmergeable_cie_offsets unmergeable_cie_offsets_; | |
478 | // A mapping from input sections to the output section. | |
479 | Merge_map merge_map_; | |
1d6531cf ILT |
480 | // Whether we have created the mappings to the output section. |
481 | bool mappings_are_done_; | |
482 | // The final data size. This is only set if mappings_are_done_ is | |
483 | // true. | |
484 | section_size_type final_data_size_; | |
3151305a ILT |
485 | }; |
486 | ||
487 | } // End namespace gold. | |
488 | ||
489 | #endif // !defined(GOLD_EHFRAME_H) |