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