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a2fb1b05 ILT |
1 | // layout.cc -- lay out output file sections for gold |
2 | ||
3 | #include "gold.h" | |
4 | ||
5 | #include <cassert> | |
6 | #include <cstring> | |
54dc6425 | 7 | #include <algorithm> |
a2fb1b05 ILT |
8 | #include <iostream> |
9 | #include <utility> | |
10 | ||
11 | #include "output.h" | |
12 | #include "layout.h" | |
13 | ||
14 | namespace gold | |
15 | { | |
16 | ||
17 | // Layout_task methods. | |
18 | ||
19 | Layout_task::~Layout_task() | |
20 | { | |
21 | } | |
22 | ||
23 | // This task can be run when it is unblocked. | |
24 | ||
25 | Task::Is_runnable_type | |
26 | Layout_task::is_runnable(Workqueue*) | |
27 | { | |
28 | if (this->this_blocker_->is_blocked()) | |
29 | return IS_BLOCKED; | |
30 | return IS_RUNNABLE; | |
31 | } | |
32 | ||
33 | // We don't need to hold any locks for the duration of this task. In | |
34 | // fact this task will be the only one running. | |
35 | ||
36 | Task_locker* | |
37 | Layout_task::locks(Workqueue*) | |
38 | { | |
39 | return NULL; | |
40 | } | |
41 | ||
42 | // Lay out the sections. This is called after all the input objects | |
43 | // have been read. | |
44 | ||
45 | void | |
61ba1cf9 | 46 | Layout_task::run(Workqueue* workqueue) |
a2fb1b05 | 47 | { |
12e14209 ILT |
48 | off_t file_size = this->layout_->finalize(this->input_objects_, |
49 | this->symtab_); | |
61ba1cf9 ILT |
50 | |
51 | // Now we know the final size of the output file and we know where | |
52 | // each piece of information goes. | |
53 | Output_file* of = new Output_file(this->options_); | |
54 | of->open(file_size); | |
55 | ||
56 | // Queue up the final set of tasks. | |
57 | gold::queue_final_tasks(this->options_, this->input_objects_, | |
12e14209 | 58 | this->symtab_, this->layout_, workqueue, of); |
a2fb1b05 ILT |
59 | } |
60 | ||
61 | // Layout methods. | |
62 | ||
54dc6425 | 63 | Layout::Layout(const General_options& options) |
61ba1cf9 ILT |
64 | : options_(options), last_shndx_(0), namepool_(), sympool_(), signatures_(), |
65 | section_name_map_(), segment_list_(), section_list_(), | |
66 | special_output_list_() | |
54dc6425 ILT |
67 | { |
68 | // Make space for more than enough segments for a typical file. | |
69 | // This is just for efficiency--it's OK if we wind up needing more. | |
70 | segment_list_.reserve(12); | |
71 | } | |
72 | ||
a2fb1b05 ILT |
73 | // Hash a key we use to look up an output section mapping. |
74 | ||
75 | size_t | |
76 | Layout::Hash_key::operator()(const Layout::Key& k) const | |
77 | { | |
78 | return reinterpret_cast<size_t>(k.first) + k.second.first + k.second.second; | |
79 | } | |
80 | ||
81 | // Whether to include this section in the link. | |
82 | ||
83 | template<int size, bool big_endian> | |
84 | bool | |
85 | Layout::include_section(Object*, const char*, | |
86 | const elfcpp::Shdr<size, big_endian>& shdr) | |
87 | { | |
88 | // Some section types are never linked. Some are only linked when | |
89 | // doing a relocateable link. | |
90 | switch (shdr.get_sh_type()) | |
91 | { | |
92 | case elfcpp::SHT_NULL: | |
93 | case elfcpp::SHT_SYMTAB: | |
94 | case elfcpp::SHT_DYNSYM: | |
95 | case elfcpp::SHT_STRTAB: | |
96 | case elfcpp::SHT_HASH: | |
97 | case elfcpp::SHT_DYNAMIC: | |
98 | case elfcpp::SHT_SYMTAB_SHNDX: | |
99 | return false; | |
100 | ||
101 | case elfcpp::SHT_RELA: | |
102 | case elfcpp::SHT_REL: | |
103 | case elfcpp::SHT_GROUP: | |
104 | return this->options_.is_relocatable(); | |
105 | ||
106 | default: | |
107 | // FIXME: Handle stripping debug sections here. | |
108 | return true; | |
109 | } | |
110 | } | |
111 | ||
112 | // Return the output section to use for input section NAME, with | |
113 | // header HEADER, from object OBJECT. Set *OFF to the offset of this | |
114 | // input section without the output section. | |
115 | ||
116 | template<int size, bool big_endian> | |
117 | Output_section* | |
118 | Layout::layout(Object* object, const char* name, | |
119 | const elfcpp::Shdr<size, big_endian>& shdr, off_t* off) | |
120 | { | |
61ba1cf9 ILT |
121 | // We discard empty input sections. |
122 | if (shdr.get_sh_size() == 0) | |
123 | return NULL; | |
124 | ||
a2fb1b05 ILT |
125 | if (!this->include_section(object, name, shdr)) |
126 | return NULL; | |
127 | ||
128 | // Unless we are doing a relocateable link, .gnu.linkonce sections | |
129 | // are laid out as though they were named for the sections are | |
130 | // placed into. | |
131 | if (!this->options_.is_relocatable() && Layout::is_linkonce(name)) | |
132 | name = Layout::linkonce_output_name(name); | |
133 | ||
134 | // FIXME: Handle SHF_OS_NONCONFORMING here. | |
135 | ||
136 | // Canonicalize the section name. | |
137 | name = this->namepool_.add(name); | |
138 | ||
139 | // Find the output section. The output section is selected based on | |
140 | // the section name, type, and flags. | |
141 | ||
142 | // FIXME: If we want to do relaxation, we need to modify this | |
143 | // algorithm. We also build a list of input sections for each | |
144 | // output section. Then we relax all the input sections. Then we | |
145 | // walk down the list and adjust all the offsets. | |
146 | ||
147 | elfcpp::Elf_Word type = shdr.get_sh_type(); | |
148 | elfcpp::Elf_Xword flags = shdr.get_sh_flags(); | |
149 | const Key key(name, std::make_pair(type, flags)); | |
150 | const std::pair<Key, Output_section*> v(key, NULL); | |
151 | std::pair<Section_name_map::iterator, bool> ins( | |
152 | this->section_name_map_.insert(v)); | |
153 | ||
154 | Output_section* os; | |
155 | if (!ins.second) | |
156 | os = ins.first->second; | |
157 | else | |
158 | { | |
159 | // This is the first time we've seen this name/type/flags | |
160 | // combination. | |
161 | os = this->make_output_section(name, type, flags); | |
162 | ins.first->second = os; | |
163 | } | |
164 | ||
165 | // FIXME: Handle SHF_LINK_ORDER somewhere. | |
166 | ||
167 | *off = os->add_input_section(object, name, shdr); | |
168 | ||
169 | return os; | |
170 | } | |
171 | ||
a2fb1b05 ILT |
172 | // Map section flags to segment flags. |
173 | ||
174 | elfcpp::Elf_Word | |
175 | Layout::section_flags_to_segment(elfcpp::Elf_Xword flags) | |
176 | { | |
177 | elfcpp::Elf_Word ret = elfcpp::PF_R; | |
178 | if ((flags & elfcpp::SHF_WRITE) != 0) | |
179 | ret |= elfcpp::PF_W; | |
180 | if ((flags & elfcpp::SHF_EXECINSTR) != 0) | |
181 | ret |= elfcpp::PF_X; | |
182 | return ret; | |
183 | } | |
184 | ||
185 | // Make a new Output_section, and attach it to segments as | |
186 | // appropriate. | |
187 | ||
188 | Output_section* | |
189 | Layout::make_output_section(const char* name, elfcpp::Elf_Word type, | |
190 | elfcpp::Elf_Xword flags) | |
191 | { | |
61ba1cf9 ILT |
192 | ++this->last_shndx_; |
193 | Output_section* os = new Output_section(name, type, flags, | |
194 | this->last_shndx_); | |
a2fb1b05 ILT |
195 | |
196 | if ((flags & elfcpp::SHF_ALLOC) == 0) | |
197 | this->section_list_.push_back(os); | |
198 | else | |
199 | { | |
200 | // This output section goes into a PT_LOAD segment. | |
201 | ||
202 | elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags); | |
203 | ||
204 | // The only thing we really care about for PT_LOAD segments is | |
205 | // whether or not they are writable, so that is how we search | |
206 | // for them. People who need segments sorted on some other | |
207 | // basis will have to wait until we implement a mechanism for | |
208 | // them to describe the segments they want. | |
209 | ||
210 | Segment_list::const_iterator p; | |
211 | for (p = this->segment_list_.begin(); | |
212 | p != this->segment_list_.end(); | |
213 | ++p) | |
214 | { | |
215 | if ((*p)->type() == elfcpp::PT_LOAD | |
216 | && ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W)) | |
217 | { | |
75f65a3e | 218 | (*p)->add_output_section(os, seg_flags); |
a2fb1b05 ILT |
219 | break; |
220 | } | |
221 | } | |
222 | ||
223 | if (p == this->segment_list_.end()) | |
224 | { | |
225 | Output_segment* oseg = new Output_segment(elfcpp::PT_LOAD, | |
226 | seg_flags); | |
227 | this->segment_list_.push_back(oseg); | |
75f65a3e | 228 | oseg->add_output_section(os, seg_flags); |
a2fb1b05 ILT |
229 | } |
230 | ||
231 | // If we see a loadable SHT_NOTE section, we create a PT_NOTE | |
232 | // segment. | |
233 | if (type == elfcpp::SHT_NOTE) | |
234 | { | |
235 | // See if we already have an equivalent PT_NOTE segment. | |
236 | for (p = this->segment_list_.begin(); | |
237 | p != segment_list_.end(); | |
238 | ++p) | |
239 | { | |
240 | if ((*p)->type() == elfcpp::PT_NOTE | |
241 | && (((*p)->flags() & elfcpp::PF_W) | |
242 | == (seg_flags & elfcpp::PF_W))) | |
243 | { | |
75f65a3e | 244 | (*p)->add_output_section(os, seg_flags); |
a2fb1b05 ILT |
245 | break; |
246 | } | |
247 | } | |
248 | ||
249 | if (p == this->segment_list_.end()) | |
250 | { | |
251 | Output_segment* oseg = new Output_segment(elfcpp::PT_NOTE, | |
252 | seg_flags); | |
253 | this->segment_list_.push_back(oseg); | |
75f65a3e | 254 | oseg->add_output_section(os, seg_flags); |
a2fb1b05 ILT |
255 | } |
256 | } | |
54dc6425 ILT |
257 | |
258 | // If we see a loadable SHF_TLS section, we create a PT_TLS | |
259 | // segment. | |
260 | if ((flags & elfcpp::SHF_TLS) != 0) | |
261 | { | |
262 | // See if we already have an equivalent PT_TLS segment. | |
263 | for (p = this->segment_list_.begin(); | |
264 | p != segment_list_.end(); | |
265 | ++p) | |
266 | { | |
267 | if ((*p)->type() == elfcpp::PT_TLS | |
268 | && (((*p)->flags() & elfcpp::PF_W) | |
269 | == (seg_flags & elfcpp::PF_W))) | |
270 | { | |
75f65a3e | 271 | (*p)->add_output_section(os, seg_flags); |
54dc6425 ILT |
272 | break; |
273 | } | |
274 | } | |
275 | ||
276 | if (p == this->segment_list_.end()) | |
277 | { | |
278 | Output_segment* oseg = new Output_segment(elfcpp::PT_TLS, | |
279 | seg_flags); | |
280 | this->segment_list_.push_back(oseg); | |
75f65a3e | 281 | oseg->add_output_section(os, seg_flags); |
54dc6425 ILT |
282 | } |
283 | } | |
a2fb1b05 ILT |
284 | } |
285 | ||
286 | return os; | |
287 | } | |
288 | ||
75f65a3e ILT |
289 | // Find the first read-only PT_LOAD segment, creating one if |
290 | // necessary. | |
54dc6425 | 291 | |
75f65a3e ILT |
292 | Output_segment* |
293 | Layout::find_first_load_seg() | |
54dc6425 | 294 | { |
75f65a3e ILT |
295 | for (Segment_list::const_iterator p = this->segment_list_.begin(); |
296 | p != this->segment_list_.end(); | |
297 | ++p) | |
298 | { | |
299 | if ((*p)->type() == elfcpp::PT_LOAD | |
300 | && ((*p)->flags() & elfcpp::PF_R) != 0 | |
301 | && ((*p)->flags() & elfcpp::PF_W) == 0) | |
302 | return *p; | |
303 | } | |
304 | ||
305 | Output_segment* load_seg = new Output_segment(elfcpp::PT_LOAD, elfcpp::PF_R); | |
306 | this->segment_list_.push_back(load_seg); | |
307 | return load_seg; | |
54dc6425 ILT |
308 | } |
309 | ||
310 | // Finalize the layout. When this is called, we have created all the | |
311 | // output sections and all the output segments which are based on | |
312 | // input sections. We have several things to do, and we have to do | |
313 | // them in the right order, so that we get the right results correctly | |
314 | // and efficiently. | |
315 | ||
316 | // 1) Finalize the list of output segments and create the segment | |
317 | // table header. | |
318 | ||
319 | // 2) Finalize the dynamic symbol table and associated sections. | |
320 | ||
321 | // 3) Determine the final file offset of all the output segments. | |
322 | ||
323 | // 4) Determine the final file offset of all the SHF_ALLOC output | |
324 | // sections. | |
325 | ||
75f65a3e ILT |
326 | // 5) Create the symbol table sections and the section name table |
327 | // section. | |
328 | ||
329 | // 6) Finalize the symbol table: set symbol values to their final | |
54dc6425 ILT |
330 | // value and make a final determination of which symbols are going |
331 | // into the output symbol table. | |
332 | ||
54dc6425 ILT |
333 | // 7) Create the section table header. |
334 | ||
335 | // 8) Determine the final file offset of all the output sections which | |
336 | // are not SHF_ALLOC, including the section table header. | |
337 | ||
338 | // 9) Finalize the ELF file header. | |
339 | ||
75f65a3e ILT |
340 | // This function returns the size of the output file. |
341 | ||
342 | off_t | |
343 | Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab) | |
54dc6425 ILT |
344 | { |
345 | if (input_objects->any_dynamic()) | |
346 | { | |
347 | // If there are any dynamic objects in the link, then we need | |
348 | // some additional segments: PT_PHDRS, PT_INTERP, and | |
349 | // PT_DYNAMIC. We also need to finalize the dynamic symbol | |
350 | // table and create the dynamic hash table. | |
351 | abort(); | |
352 | } | |
353 | ||
354 | // FIXME: Handle PT_GNU_STACK. | |
355 | ||
75f65a3e ILT |
356 | Output_segment* load_seg = this->find_first_load_seg(); |
357 | ||
358 | // Lay out the segment headers. | |
359 | int size = input_objects->target()->get_size(); | |
61ba1cf9 | 360 | bool big_endian = input_objects->target()->is_big_endian(); |
75f65a3e | 361 | Output_segment_headers* segment_headers; |
61ba1cf9 ILT |
362 | segment_headers = new Output_segment_headers(size, big_endian, |
363 | this->segment_list_); | |
75f65a3e | 364 | load_seg->add_initial_output_data(segment_headers); |
61ba1cf9 | 365 | this->special_output_list_.push_back(segment_headers); |
75f65a3e ILT |
366 | // FIXME: Attach them to PT_PHDRS if necessary. |
367 | ||
368 | // Lay out the file header. | |
369 | Output_file_header* file_header; | |
370 | file_header = new Output_file_header(size, | |
61ba1cf9 | 371 | big_endian, |
75f65a3e ILT |
372 | this->options_, |
373 | input_objects->target(), | |
374 | symtab, | |
375 | segment_headers); | |
376 | load_seg->add_initial_output_data(file_header); | |
61ba1cf9 | 377 | this->special_output_list_.push_back(file_header); |
75f65a3e ILT |
378 | |
379 | // Set the file offsets of all the segments. | |
380 | off_t off = this->set_segment_offsets(input_objects->target(), load_seg); | |
381 | ||
382 | // Create the symbol table sections. | |
383 | // FIXME: We don't need to do this if we are stripping symbols. | |
384 | Output_section* osymtab; | |
385 | Output_section* ostrtab; | |
61ba1cf9 ILT |
386 | this->create_symtab_sections(size, input_objects, symtab, &off, |
387 | &osymtab, &ostrtab); | |
75f65a3e ILT |
388 | |
389 | // Create the .shstrtab section. | |
390 | Output_section* shstrtab_section = this->create_shstrtab(); | |
391 | ||
392 | // Set the file offsets of all the sections not associated with | |
393 | // segments. | |
394 | off = this->set_section_offsets(off); | |
395 | ||
396 | // Create the section table header. | |
61ba1cf9 | 397 | Output_section_headers* oshdrs = this->create_shdrs(size, big_endian, &off); |
75f65a3e ILT |
398 | |
399 | file_header->set_section_info(oshdrs, shstrtab_section); | |
400 | ||
401 | // Now we know exactly where everything goes in the output file. | |
402 | ||
403 | return off; | |
404 | } | |
405 | ||
406 | // Return whether SEG1 should be before SEG2 in the output file. This | |
407 | // is based entirely on the segment type and flags. When this is | |
408 | // called the segment addresses has normally not yet been set. | |
409 | ||
410 | bool | |
411 | Layout::segment_precedes(const Output_segment* seg1, | |
412 | const Output_segment* seg2) | |
413 | { | |
414 | elfcpp::Elf_Word type1 = seg1->type(); | |
415 | elfcpp::Elf_Word type2 = seg2->type(); | |
416 | ||
417 | // The single PT_PHDR segment is required to precede any loadable | |
418 | // segment. We simply make it always first. | |
419 | if (type1 == elfcpp::PT_PHDR) | |
420 | { | |
421 | assert(type2 != elfcpp::PT_PHDR); | |
422 | return true; | |
423 | } | |
424 | if (type2 == elfcpp::PT_PHDR) | |
425 | return false; | |
426 | ||
427 | // The single PT_INTERP segment is required to precede any loadable | |
428 | // segment. We simply make it always second. | |
429 | if (type1 == elfcpp::PT_INTERP) | |
430 | { | |
431 | assert(type2 != elfcpp::PT_INTERP); | |
432 | return true; | |
433 | } | |
434 | if (type2 == elfcpp::PT_INTERP) | |
435 | return false; | |
436 | ||
437 | // We then put PT_LOAD segments before any other segments. | |
438 | if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD) | |
439 | return true; | |
440 | if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD) | |
441 | return false; | |
442 | ||
443 | const elfcpp::Elf_Word flags1 = seg1->flags(); | |
444 | const elfcpp::Elf_Word flags2 = seg2->flags(); | |
445 | ||
446 | // The order of non-PT_LOAD segments is unimportant. We simply sort | |
447 | // by the numeric segment type and flags values. There should not | |
448 | // be more than one segment with the same type and flags. | |
449 | if (type1 != elfcpp::PT_LOAD) | |
450 | { | |
451 | if (type1 != type2) | |
452 | return type1 < type2; | |
453 | assert(flags1 != flags2); | |
454 | return flags1 < flags2; | |
455 | } | |
456 | ||
457 | // We sort PT_LOAD segments based on the flags. Readonly segments | |
458 | // come before writable segments. Then executable segments come | |
459 | // before non-executable segments. Then the unlikely case of a | |
460 | // non-readable segment comes before the normal case of a readable | |
461 | // segment. If there are multiple segments with the same type and | |
462 | // flags, we require that the address be set, and we sort by | |
463 | // virtual address and then physical address. | |
464 | if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W)) | |
465 | return (flags1 & elfcpp::PF_W) == 0; | |
466 | if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X)) | |
467 | return (flags1 & elfcpp::PF_X) != 0; | |
468 | if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R)) | |
469 | return (flags1 & elfcpp::PF_R) == 0; | |
470 | ||
471 | uint64_t vaddr1 = seg1->vaddr(); | |
472 | uint64_t vaddr2 = seg2->vaddr(); | |
473 | if (vaddr1 != vaddr2) | |
474 | return vaddr1 < vaddr2; | |
475 | ||
476 | uint64_t paddr1 = seg1->paddr(); | |
477 | uint64_t paddr2 = seg2->paddr(); | |
478 | assert(paddr1 != paddr2); | |
479 | return paddr1 < paddr2; | |
480 | } | |
481 | ||
482 | // Set the file offsets of all the segments. They have all been | |
483 | // created. LOAD_SEG must be be laid out first. Return the offset of | |
484 | // the data to follow. | |
485 | ||
486 | off_t | |
487 | Layout::set_segment_offsets(const Target* target, Output_segment* load_seg) | |
488 | { | |
489 | // Sort them into the final order. | |
54dc6425 ILT |
490 | std::sort(this->segment_list_.begin(), this->segment_list_.end(), |
491 | Layout::Compare_segments()); | |
492 | ||
75f65a3e ILT |
493 | // Find the PT_LOAD segments, and set their addresses and offsets |
494 | // and their section's addresses and offsets. | |
495 | uint64_t addr = target->text_segment_address(); | |
496 | off_t off = 0; | |
497 | bool was_readonly = false; | |
498 | for (Segment_list::iterator p = this->segment_list_.begin(); | |
499 | p != this->segment_list_.end(); | |
500 | ++p) | |
501 | { | |
502 | if ((*p)->type() == elfcpp::PT_LOAD) | |
503 | { | |
504 | if (load_seg != NULL && load_seg != *p) | |
505 | abort(); | |
506 | load_seg = NULL; | |
507 | ||
508 | // If the last segment was readonly, and this one is not, | |
509 | // then skip the address forward one page, maintaining the | |
510 | // same position within the page. This lets us store both | |
511 | // segments overlapping on a single page in the file, but | |
512 | // the loader will put them on different pages in memory. | |
513 | ||
514 | uint64_t orig_addr = addr; | |
515 | uint64_t orig_off = off; | |
516 | ||
517 | uint64_t aligned_addr = addr; | |
518 | uint64_t abi_pagesize = target->abi_pagesize(); | |
519 | if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0) | |
520 | { | |
521 | uint64_t align = (*p)->max_data_align(); | |
522 | ||
523 | addr = (addr + align - 1) & ~ (align - 1); | |
524 | aligned_addr = addr; | |
525 | if ((addr & (abi_pagesize - 1)) != 0) | |
526 | addr = addr + abi_pagesize; | |
527 | } | |
528 | ||
529 | off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); | |
530 | uint64_t new_addr = (*p)->set_section_addresses(addr, &off); | |
531 | ||
532 | // Now that we know the size of this segment, we may be able | |
533 | // to save a page in memory, at the cost of wasting some | |
534 | // file space, by instead aligning to the start of a new | |
535 | // page. Here we use the real machine page size rather than | |
536 | // the ABI mandated page size. | |
537 | ||
538 | if (aligned_addr != addr) | |
539 | { | |
540 | uint64_t common_pagesize = target->common_pagesize(); | |
541 | uint64_t first_off = (common_pagesize | |
542 | - (aligned_addr | |
543 | & (common_pagesize - 1))); | |
544 | uint64_t last_off = new_addr & (common_pagesize - 1); | |
545 | if (first_off > 0 | |
546 | && last_off > 0 | |
547 | && ((aligned_addr & ~ (common_pagesize - 1)) | |
548 | != (new_addr & ~ (common_pagesize - 1))) | |
549 | && first_off + last_off <= common_pagesize) | |
550 | { | |
551 | addr = ((aligned_addr + common_pagesize - 1) | |
552 | & ~ (common_pagesize - 1)); | |
553 | off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); | |
554 | new_addr = (*p)->set_section_addresses(addr, &off); | |
555 | } | |
556 | } | |
557 | ||
558 | addr = new_addr; | |
559 | ||
560 | if (((*p)->flags() & elfcpp::PF_W) == 0) | |
561 | was_readonly = true; | |
562 | } | |
563 | } | |
564 | ||
565 | // Handle the non-PT_LOAD segments, setting their offsets from their | |
566 | // section's offsets. | |
567 | for (Segment_list::iterator p = this->segment_list_.begin(); | |
568 | p != this->segment_list_.end(); | |
569 | ++p) | |
570 | { | |
571 | if ((*p)->type() != elfcpp::PT_LOAD) | |
572 | (*p)->set_offset(); | |
573 | } | |
574 | ||
575 | return off; | |
576 | } | |
577 | ||
578 | // Set the file offset of all the sections not associated with a | |
579 | // segment. | |
580 | ||
581 | off_t | |
582 | Layout::set_section_offsets(off_t off) | |
583 | { | |
584 | for (Layout::Section_list::iterator p = this->section_list_.begin(); | |
585 | p != this->section_list_.end(); | |
586 | ++p) | |
587 | { | |
61ba1cf9 ILT |
588 | if ((*p)->offset() != -1) |
589 | continue; | |
75f65a3e | 590 | uint64_t addralign = (*p)->addralign(); |
61ba1cf9 ILT |
591 | if (addralign != 0) |
592 | off = (off + addralign - 1) & ~ (addralign - 1); | |
75f65a3e ILT |
593 | (*p)->set_address(0, off); |
594 | off += (*p)->data_size(); | |
595 | } | |
596 | return off; | |
597 | } | |
598 | ||
599 | // Create the symbol table sections. | |
600 | ||
601 | void | |
61ba1cf9 | 602 | Layout::create_symtab_sections(int size, const Input_objects* input_objects, |
75f65a3e | 603 | Symbol_table* symtab, |
61ba1cf9 | 604 | off_t* poff, |
75f65a3e ILT |
605 | Output_section** posymtab, |
606 | Output_section** postrtab) | |
607 | { | |
61ba1cf9 ILT |
608 | int symsize; |
609 | unsigned int align; | |
610 | if (size == 32) | |
611 | { | |
612 | symsize = elfcpp::Elf_sizes<32>::sym_size; | |
613 | align = 4; | |
614 | } | |
615 | else if (size == 64) | |
616 | { | |
617 | symsize = elfcpp::Elf_sizes<64>::sym_size; | |
618 | align = 8; | |
619 | } | |
620 | else | |
621 | abort(); | |
622 | ||
623 | off_t off = *poff; | |
624 | off = (off + align - 1) & ~ (align - 1); | |
625 | off_t startoff = off; | |
626 | ||
627 | // Save space for the dummy symbol at the start of the section. We | |
628 | // never bother to write this out--it will just be left as zero. | |
629 | off += symsize; | |
630 | ||
75f65a3e ILT |
631 | for (Input_objects::Object_list::const_iterator p = input_objects->begin(); |
632 | p != input_objects->end(); | |
633 | ++p) | |
634 | { | |
635 | Task_lock_obj<Object> tlo(**p); | |
636 | off = (*p)->finalize_local_symbols(off, &this->sympool_); | |
637 | } | |
638 | ||
61ba1cf9 ILT |
639 | unsigned int local_symcount = (off - startoff) / symsize; |
640 | assert(local_symcount * symsize == off - startoff); | |
641 | ||
75f65a3e ILT |
642 | off = symtab->finalize(off, &this->sympool_); |
643 | ||
61ba1cf9 ILT |
644 | this->sympool_.set_string_offsets(); |
645 | ||
646 | ++this->last_shndx_; | |
647 | const char* symtab_name = this->namepool_.add(".symtab"); | |
648 | Output_section* osymtab = new Output_section_symtab(symtab_name, | |
649 | off - startoff, | |
650 | this->last_shndx_); | |
651 | this->section_list_.push_back(osymtab); | |
652 | ||
653 | ++this->last_shndx_; | |
654 | const char* strtab_name = this->namepool_.add(".strtab"); | |
655 | Output_section *ostrtab = new Output_section_strtab(strtab_name, | |
656 | &this->sympool_, | |
657 | this->last_shndx_); | |
658 | this->section_list_.push_back(ostrtab); | |
659 | this->special_output_list_.push_back(ostrtab); | |
660 | ||
661 | osymtab->set_address(0, startoff); | |
662 | osymtab->set_link(ostrtab->shndx()); | |
663 | osymtab->set_info(local_symcount); | |
664 | osymtab->set_entsize(symsize); | |
665 | osymtab->set_addralign(align); | |
666 | ||
667 | *poff = off; | |
668 | *posymtab = osymtab; | |
669 | *postrtab = ostrtab; | |
75f65a3e ILT |
670 | } |
671 | ||
672 | // Create the .shstrtab section, which holds the names of the | |
673 | // sections. At the time this is called, we have created all the | |
674 | // output sections except .shstrtab itself. | |
675 | ||
676 | Output_section* | |
677 | Layout::create_shstrtab() | |
678 | { | |
679 | // FIXME: We don't need to create a .shstrtab section if we are | |
680 | // stripping everything. | |
681 | ||
682 | const char* name = this->namepool_.add(".shstrtab"); | |
683 | ||
61ba1cf9 ILT |
684 | this->namepool_.set_string_offsets(); |
685 | ||
686 | ++this->last_shndx_; | |
75f65a3e | 687 | Output_section* os = new Output_section_strtab(name, |
61ba1cf9 ILT |
688 | &this->namepool_, |
689 | this->last_shndx_); | |
75f65a3e ILT |
690 | |
691 | this->section_list_.push_back(os); | |
61ba1cf9 | 692 | this->special_output_list_.push_back(os); |
75f65a3e ILT |
693 | |
694 | return os; | |
695 | } | |
696 | ||
697 | // Create the section headers. SIZE is 32 or 64. OFF is the file | |
698 | // offset. | |
699 | ||
700 | Output_section_headers* | |
61ba1cf9 | 701 | Layout::create_shdrs(int size, bool big_endian, off_t* poff) |
75f65a3e ILT |
702 | { |
703 | Output_section_headers* oshdrs; | |
61ba1cf9 ILT |
704 | oshdrs = new Output_section_headers(size, big_endian, this->segment_list_, |
705 | this->section_list_, | |
706 | &this->namepool_); | |
75f65a3e | 707 | uint64_t addralign = oshdrs->addralign(); |
61ba1cf9 | 708 | off_t off = (*poff + addralign - 1) & ~ (addralign - 1); |
75f65a3e | 709 | oshdrs->set_address(0, off); |
61ba1cf9 ILT |
710 | off += oshdrs->data_size(); |
711 | *poff = off; | |
712 | this->special_output_list_.push_back(oshdrs); | |
75f65a3e | 713 | return oshdrs; |
54dc6425 ILT |
714 | } |
715 | ||
a2fb1b05 ILT |
716 | // The mapping of .gnu.linkonce section names to real section names. |
717 | ||
718 | #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t } | |
719 | const Layout::Linkonce_mapping Layout::linkonce_mapping[] = | |
720 | { | |
721 | MAPPING_INIT("d.rel.ro", ".data.rel.ro"), // Must be before "d". | |
722 | MAPPING_INIT("t", ".text"), | |
723 | MAPPING_INIT("r", ".rodata"), | |
724 | MAPPING_INIT("d", ".data"), | |
725 | MAPPING_INIT("b", ".bss"), | |
726 | MAPPING_INIT("s", ".sdata"), | |
727 | MAPPING_INIT("sb", ".sbss"), | |
728 | MAPPING_INIT("s2", ".sdata2"), | |
729 | MAPPING_INIT("sb2", ".sbss2"), | |
730 | MAPPING_INIT("wi", ".debug_info"), | |
731 | MAPPING_INIT("td", ".tdata"), | |
732 | MAPPING_INIT("tb", ".tbss"), | |
733 | MAPPING_INIT("lr", ".lrodata"), | |
734 | MAPPING_INIT("l", ".ldata"), | |
735 | MAPPING_INIT("lb", ".lbss"), | |
736 | }; | |
737 | #undef MAPPING_INIT | |
738 | ||
739 | const int Layout::linkonce_mapping_count = | |
740 | sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]); | |
741 | ||
742 | // Return the name of the output section to use for a .gnu.linkonce | |
743 | // section. This is based on the default ELF linker script of the old | |
744 | // GNU linker. For example, we map a name like ".gnu.linkonce.t.foo" | |
745 | // to ".text". | |
746 | ||
747 | const char* | |
748 | Layout::linkonce_output_name(const char* name) | |
749 | { | |
750 | const char* s = name + sizeof(".gnu.linkonce") - 1; | |
751 | if (*s != '.') | |
752 | return name; | |
753 | ++s; | |
754 | const Linkonce_mapping* plm = linkonce_mapping; | |
755 | for (int i = 0; i < linkonce_mapping_count; ++i, ++plm) | |
756 | { | |
757 | if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.') | |
758 | return plm->to; | |
759 | } | |
760 | return name; | |
761 | } | |
762 | ||
763 | // Record the signature of a comdat section, and return whether to | |
764 | // include it in the link. If GROUP is true, this is a regular | |
765 | // section group. If GROUP is false, this is a group signature | |
766 | // derived from the name of a linkonce section. We want linkonce | |
767 | // signatures and group signatures to block each other, but we don't | |
768 | // want a linkonce signature to block another linkonce signature. | |
769 | ||
770 | bool | |
771 | Layout::add_comdat(const char* signature, bool group) | |
772 | { | |
773 | std::string sig(signature); | |
774 | std::pair<Signatures::iterator, bool> ins( | |
775 | this->signatures_.insert(std::make_pair(signature, group))); | |
776 | ||
777 | if (ins.second) | |
778 | { | |
779 | // This is the first time we've seen this signature. | |
780 | return true; | |
781 | } | |
782 | ||
783 | if (ins.first->second) | |
784 | { | |
785 | // We've already seen a real section group with this signature. | |
786 | return false; | |
787 | } | |
788 | else if (group) | |
789 | { | |
790 | // This is a real section group, and we've already seen a | |
791 | // linkonce section with tihs signature. Record that we've seen | |
792 | // a section group, and don't include this section group. | |
793 | ins.first->second = true; | |
794 | return false; | |
795 | } | |
796 | else | |
797 | { | |
798 | // We've already seen a linkonce section and this is a linkonce | |
799 | // section. These don't block each other--this may be the same | |
800 | // symbol name with different section types. | |
801 | return true; | |
802 | } | |
803 | } | |
804 | ||
61ba1cf9 ILT |
805 | // Write out data not associated with a section or the symbol table. |
806 | ||
807 | void | |
808 | Layout::write_data(Output_file* of) const | |
809 | { | |
810 | for (Data_list::const_iterator p = this->special_output_list_.begin(); | |
811 | p != this->special_output_list_.end(); | |
812 | ++p) | |
813 | (*p)->write(of); | |
814 | } | |
815 | ||
816 | // Write_data_task methods. | |
817 | ||
818 | // We can always run this task. | |
819 | ||
820 | Task::Is_runnable_type | |
821 | Write_data_task::is_runnable(Workqueue*) | |
822 | { | |
823 | return IS_RUNNABLE; | |
824 | } | |
825 | ||
826 | // We need to unlock FINAL_BLOCKER when finished. | |
827 | ||
828 | Task_locker* | |
829 | Write_data_task::locks(Workqueue* workqueue) | |
830 | { | |
831 | return new Task_locker_block(*this->final_blocker_, workqueue); | |
832 | } | |
833 | ||
834 | // Run the task--write out the data. | |
835 | ||
836 | void | |
837 | Write_data_task::run(Workqueue*) | |
838 | { | |
839 | this->layout_->write_data(this->of_); | |
840 | } | |
841 | ||
842 | // Write_symbols_task methods. | |
843 | ||
844 | // We can always run this task. | |
845 | ||
846 | Task::Is_runnable_type | |
847 | Write_symbols_task::is_runnable(Workqueue*) | |
848 | { | |
849 | return IS_RUNNABLE; | |
850 | } | |
851 | ||
852 | // We need to unlock FINAL_BLOCKER when finished. | |
853 | ||
854 | Task_locker* | |
855 | Write_symbols_task::locks(Workqueue* workqueue) | |
856 | { | |
857 | return new Task_locker_block(*this->final_blocker_, workqueue); | |
858 | } | |
859 | ||
860 | // Run the task--write out the symbols. | |
861 | ||
862 | void | |
863 | Write_symbols_task::run(Workqueue*) | |
864 | { | |
865 | this->symtab_->write_globals(this->target_, this->sympool_, this->of_); | |
866 | } | |
867 | ||
868 | // Close_task methods. | |
869 | ||
870 | // We can't run until FINAL_BLOCKER is unblocked. | |
871 | ||
872 | Task::Is_runnable_type | |
873 | Close_task::is_runnable(Workqueue*) | |
874 | { | |
875 | if (this->final_blocker_->is_blocked()) | |
876 | return IS_BLOCKED; | |
877 | return IS_RUNNABLE; | |
878 | } | |
879 | ||
880 | // We don't lock anything. | |
881 | ||
882 | Task_locker* | |
883 | Close_task::locks(Workqueue*) | |
884 | { | |
885 | return NULL; | |
886 | } | |
887 | ||
888 | // Run the task--close the file. | |
889 | ||
890 | void | |
891 | Close_task::run(Workqueue*) | |
892 | { | |
893 | this->of_->close(); | |
894 | } | |
895 | ||
a2fb1b05 ILT |
896 | // Instantiate the templates we need. We could use the configure |
897 | // script to restrict this to only the ones for implemented targets. | |
898 | ||
899 | template | |
900 | Output_section* | |
901 | Layout::layout<32, false>(Object* object, const char* name, | |
902 | const elfcpp::Shdr<32, false>& shdr, off_t*); | |
903 | ||
904 | template | |
905 | Output_section* | |
906 | Layout::layout<32, true>(Object* object, const char* name, | |
907 | const elfcpp::Shdr<32, true>& shdr, off_t*); | |
908 | ||
909 | template | |
910 | Output_section* | |
911 | Layout::layout<64, false>(Object* object, const char* name, | |
912 | const elfcpp::Shdr<64, false>& shdr, off_t*); | |
913 | ||
914 | template | |
915 | Output_section* | |
916 | Layout::layout<64, true>(Object* object, const char* name, | |
917 | const elfcpp::Shdr<64, true>& shdr, off_t*); | |
918 | ||
919 | ||
920 | } // End namespace gold. |