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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 | ||
92e059d8 | 17 | // Layout_task_runner methods. |
a2fb1b05 ILT |
18 | |
19 | // Lay out the sections. This is called after all the input objects | |
20 | // have been read. | |
21 | ||
22 | void | |
92e059d8 | 23 | Layout_task_runner::run(Workqueue* workqueue) |
a2fb1b05 | 24 | { |
12e14209 ILT |
25 | off_t file_size = this->layout_->finalize(this->input_objects_, |
26 | this->symtab_); | |
61ba1cf9 ILT |
27 | |
28 | // Now we know the final size of the output file and we know where | |
29 | // each piece of information goes. | |
30 | Output_file* of = new Output_file(this->options_); | |
31 | of->open(file_size); | |
32 | ||
33 | // Queue up the final set of tasks. | |
34 | gold::queue_final_tasks(this->options_, this->input_objects_, | |
12e14209 | 35 | this->symtab_, this->layout_, workqueue, of); |
a2fb1b05 ILT |
36 | } |
37 | ||
38 | // Layout methods. | |
39 | ||
54dc6425 | 40 | Layout::Layout(const General_options& options) |
61ba1cf9 ILT |
41 | : options_(options), last_shndx_(0), namepool_(), sympool_(), signatures_(), |
42 | section_name_map_(), segment_list_(), section_list_(), | |
92e059d8 | 43 | special_output_list_(), tls_segment_(NULL) |
54dc6425 ILT |
44 | { |
45 | // Make space for more than enough segments for a typical file. | |
46 | // This is just for efficiency--it's OK if we wind up needing more. | |
47 | segment_list_.reserve(12); | |
48 | } | |
49 | ||
a2fb1b05 ILT |
50 | // Hash a key we use to look up an output section mapping. |
51 | ||
52 | size_t | |
53 | Layout::Hash_key::operator()(const Layout::Key& k) const | |
54 | { | |
55 | return reinterpret_cast<size_t>(k.first) + k.second.first + k.second.second; | |
56 | } | |
57 | ||
58 | // Whether to include this section in the link. | |
59 | ||
60 | template<int size, bool big_endian> | |
61 | bool | |
62 | Layout::include_section(Object*, const char*, | |
63 | const elfcpp::Shdr<size, big_endian>& shdr) | |
64 | { | |
65 | // Some section types are never linked. Some are only linked when | |
66 | // doing a relocateable link. | |
67 | switch (shdr.get_sh_type()) | |
68 | { | |
69 | case elfcpp::SHT_NULL: | |
70 | case elfcpp::SHT_SYMTAB: | |
71 | case elfcpp::SHT_DYNSYM: | |
72 | case elfcpp::SHT_STRTAB: | |
73 | case elfcpp::SHT_HASH: | |
74 | case elfcpp::SHT_DYNAMIC: | |
75 | case elfcpp::SHT_SYMTAB_SHNDX: | |
76 | return false; | |
77 | ||
78 | case elfcpp::SHT_RELA: | |
79 | case elfcpp::SHT_REL: | |
80 | case elfcpp::SHT_GROUP: | |
81 | return this->options_.is_relocatable(); | |
82 | ||
83 | default: | |
84 | // FIXME: Handle stripping debug sections here. | |
85 | return true; | |
86 | } | |
87 | } | |
88 | ||
89 | // Return the output section to use for input section NAME, with | |
90 | // header HEADER, from object OBJECT. Set *OFF to the offset of this | |
91 | // input section without the output section. | |
92 | ||
93 | template<int size, bool big_endian> | |
94 | Output_section* | |
95 | Layout::layout(Object* object, const char* name, | |
96 | const elfcpp::Shdr<size, big_endian>& shdr, off_t* off) | |
97 | { | |
61ba1cf9 ILT |
98 | // We discard empty input sections. |
99 | if (shdr.get_sh_size() == 0) | |
100 | return NULL; | |
101 | ||
a2fb1b05 ILT |
102 | if (!this->include_section(object, name, shdr)) |
103 | return NULL; | |
104 | ||
105 | // Unless we are doing a relocateable link, .gnu.linkonce sections | |
106 | // are laid out as though they were named for the sections are | |
107 | // placed into. | |
108 | if (!this->options_.is_relocatable() && Layout::is_linkonce(name)) | |
109 | name = Layout::linkonce_output_name(name); | |
110 | ||
111 | // FIXME: Handle SHF_OS_NONCONFORMING here. | |
112 | ||
113 | // Canonicalize the section name. | |
114 | name = this->namepool_.add(name); | |
115 | ||
116 | // Find the output section. The output section is selected based on | |
117 | // the section name, type, and flags. | |
118 | ||
119 | // FIXME: If we want to do relaxation, we need to modify this | |
120 | // algorithm. We also build a list of input sections for each | |
121 | // output section. Then we relax all the input sections. Then we | |
122 | // walk down the list and adjust all the offsets. | |
123 | ||
124 | elfcpp::Elf_Word type = shdr.get_sh_type(); | |
125 | elfcpp::Elf_Xword flags = shdr.get_sh_flags(); | |
126 | const Key key(name, std::make_pair(type, flags)); | |
127 | const std::pair<Key, Output_section*> v(key, NULL); | |
128 | std::pair<Section_name_map::iterator, bool> ins( | |
129 | this->section_name_map_.insert(v)); | |
130 | ||
131 | Output_section* os; | |
132 | if (!ins.second) | |
133 | os = ins.first->second; | |
134 | else | |
135 | { | |
136 | // This is the first time we've seen this name/type/flags | |
137 | // combination. | |
138 | os = this->make_output_section(name, type, flags); | |
139 | ins.first->second = os; | |
140 | } | |
141 | ||
142 | // FIXME: Handle SHF_LINK_ORDER somewhere. | |
143 | ||
144 | *off = os->add_input_section(object, name, shdr); | |
145 | ||
146 | return os; | |
147 | } | |
148 | ||
a2fb1b05 ILT |
149 | // Map section flags to segment flags. |
150 | ||
151 | elfcpp::Elf_Word | |
152 | Layout::section_flags_to_segment(elfcpp::Elf_Xword flags) | |
153 | { | |
154 | elfcpp::Elf_Word ret = elfcpp::PF_R; | |
155 | if ((flags & elfcpp::SHF_WRITE) != 0) | |
156 | ret |= elfcpp::PF_W; | |
157 | if ((flags & elfcpp::SHF_EXECINSTR) != 0) | |
158 | ret |= elfcpp::PF_X; | |
159 | return ret; | |
160 | } | |
161 | ||
162 | // Make a new Output_section, and attach it to segments as | |
163 | // appropriate. | |
164 | ||
165 | Output_section* | |
166 | Layout::make_output_section(const char* name, elfcpp::Elf_Word type, | |
167 | elfcpp::Elf_Xword flags) | |
168 | { | |
61ba1cf9 ILT |
169 | ++this->last_shndx_; |
170 | Output_section* os = new Output_section(name, type, flags, | |
171 | this->last_shndx_); | |
a2fb1b05 ILT |
172 | |
173 | if ((flags & elfcpp::SHF_ALLOC) == 0) | |
174 | this->section_list_.push_back(os); | |
175 | else | |
176 | { | |
177 | // This output section goes into a PT_LOAD segment. | |
178 | ||
179 | elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags); | |
180 | ||
181 | // The only thing we really care about for PT_LOAD segments is | |
182 | // whether or not they are writable, so that is how we search | |
183 | // for them. People who need segments sorted on some other | |
184 | // basis will have to wait until we implement a mechanism for | |
185 | // them to describe the segments they want. | |
186 | ||
187 | Segment_list::const_iterator p; | |
188 | for (p = this->segment_list_.begin(); | |
189 | p != this->segment_list_.end(); | |
190 | ++p) | |
191 | { | |
192 | if ((*p)->type() == elfcpp::PT_LOAD | |
193 | && ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W)) | |
194 | { | |
75f65a3e | 195 | (*p)->add_output_section(os, seg_flags); |
a2fb1b05 ILT |
196 | break; |
197 | } | |
198 | } | |
199 | ||
200 | if (p == this->segment_list_.end()) | |
201 | { | |
202 | Output_segment* oseg = new Output_segment(elfcpp::PT_LOAD, | |
203 | seg_flags); | |
204 | this->segment_list_.push_back(oseg); | |
75f65a3e | 205 | oseg->add_output_section(os, seg_flags); |
a2fb1b05 ILT |
206 | } |
207 | ||
208 | // If we see a loadable SHT_NOTE section, we create a PT_NOTE | |
209 | // segment. | |
210 | if (type == elfcpp::SHT_NOTE) | |
211 | { | |
212 | // See if we already have an equivalent PT_NOTE segment. | |
213 | for (p = this->segment_list_.begin(); | |
214 | p != segment_list_.end(); | |
215 | ++p) | |
216 | { | |
217 | if ((*p)->type() == elfcpp::PT_NOTE | |
218 | && (((*p)->flags() & elfcpp::PF_W) | |
219 | == (seg_flags & elfcpp::PF_W))) | |
220 | { | |
75f65a3e | 221 | (*p)->add_output_section(os, seg_flags); |
a2fb1b05 ILT |
222 | break; |
223 | } | |
224 | } | |
225 | ||
226 | if (p == this->segment_list_.end()) | |
227 | { | |
228 | Output_segment* oseg = new Output_segment(elfcpp::PT_NOTE, | |
229 | seg_flags); | |
230 | this->segment_list_.push_back(oseg); | |
75f65a3e | 231 | oseg->add_output_section(os, seg_flags); |
a2fb1b05 ILT |
232 | } |
233 | } | |
54dc6425 ILT |
234 | |
235 | // If we see a loadable SHF_TLS section, we create a PT_TLS | |
92e059d8 | 236 | // segment. There can only be one such segment. |
54dc6425 ILT |
237 | if ((flags & elfcpp::SHF_TLS) != 0) |
238 | { | |
92e059d8 | 239 | if (this->tls_segment_ == NULL) |
54dc6425 | 240 | { |
92e059d8 ILT |
241 | this->tls_segment_ = new Output_segment(elfcpp::PT_TLS, |
242 | seg_flags); | |
243 | this->segment_list_.push_back(this->tls_segment_); | |
54dc6425 | 244 | } |
92e059d8 | 245 | this->tls_segment_->add_output_section(os, seg_flags); |
54dc6425 | 246 | } |
a2fb1b05 ILT |
247 | } |
248 | ||
249 | return os; | |
250 | } | |
251 | ||
75f65a3e ILT |
252 | // Find the first read-only PT_LOAD segment, creating one if |
253 | // necessary. | |
54dc6425 | 254 | |
75f65a3e ILT |
255 | Output_segment* |
256 | Layout::find_first_load_seg() | |
54dc6425 | 257 | { |
75f65a3e ILT |
258 | for (Segment_list::const_iterator p = this->segment_list_.begin(); |
259 | p != this->segment_list_.end(); | |
260 | ++p) | |
261 | { | |
262 | if ((*p)->type() == elfcpp::PT_LOAD | |
263 | && ((*p)->flags() & elfcpp::PF_R) != 0 | |
264 | && ((*p)->flags() & elfcpp::PF_W) == 0) | |
265 | return *p; | |
266 | } | |
267 | ||
268 | Output_segment* load_seg = new Output_segment(elfcpp::PT_LOAD, elfcpp::PF_R); | |
269 | this->segment_list_.push_back(load_seg); | |
270 | return load_seg; | |
54dc6425 ILT |
271 | } |
272 | ||
273 | // Finalize the layout. When this is called, we have created all the | |
274 | // output sections and all the output segments which are based on | |
275 | // input sections. We have several things to do, and we have to do | |
276 | // them in the right order, so that we get the right results correctly | |
277 | // and efficiently. | |
278 | ||
279 | // 1) Finalize the list of output segments and create the segment | |
280 | // table header. | |
281 | ||
282 | // 2) Finalize the dynamic symbol table and associated sections. | |
283 | ||
284 | // 3) Determine the final file offset of all the output segments. | |
285 | ||
286 | // 4) Determine the final file offset of all the SHF_ALLOC output | |
287 | // sections. | |
288 | ||
75f65a3e ILT |
289 | // 5) Create the symbol table sections and the section name table |
290 | // section. | |
291 | ||
292 | // 6) Finalize the symbol table: set symbol values to their final | |
54dc6425 ILT |
293 | // value and make a final determination of which symbols are going |
294 | // into the output symbol table. | |
295 | ||
54dc6425 ILT |
296 | // 7) Create the section table header. |
297 | ||
298 | // 8) Determine the final file offset of all the output sections which | |
299 | // are not SHF_ALLOC, including the section table header. | |
300 | ||
301 | // 9) Finalize the ELF file header. | |
302 | ||
75f65a3e ILT |
303 | // This function returns the size of the output file. |
304 | ||
305 | off_t | |
306 | Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab) | |
54dc6425 ILT |
307 | { |
308 | if (input_objects->any_dynamic()) | |
309 | { | |
310 | // If there are any dynamic objects in the link, then we need | |
311 | // some additional segments: PT_PHDRS, PT_INTERP, and | |
312 | // PT_DYNAMIC. We also need to finalize the dynamic symbol | |
313 | // table and create the dynamic hash table. | |
314 | abort(); | |
315 | } | |
316 | ||
317 | // FIXME: Handle PT_GNU_STACK. | |
318 | ||
75f65a3e ILT |
319 | Output_segment* load_seg = this->find_first_load_seg(); |
320 | ||
321 | // Lay out the segment headers. | |
322 | int size = input_objects->target()->get_size(); | |
61ba1cf9 | 323 | bool big_endian = input_objects->target()->is_big_endian(); |
75f65a3e | 324 | Output_segment_headers* segment_headers; |
61ba1cf9 ILT |
325 | segment_headers = new Output_segment_headers(size, big_endian, |
326 | this->segment_list_); | |
75f65a3e | 327 | load_seg->add_initial_output_data(segment_headers); |
61ba1cf9 | 328 | this->special_output_list_.push_back(segment_headers); |
75f65a3e ILT |
329 | // FIXME: Attach them to PT_PHDRS if necessary. |
330 | ||
331 | // Lay out the file header. | |
332 | Output_file_header* file_header; | |
333 | file_header = new Output_file_header(size, | |
61ba1cf9 | 334 | big_endian, |
75f65a3e ILT |
335 | this->options_, |
336 | input_objects->target(), | |
337 | symtab, | |
338 | segment_headers); | |
339 | load_seg->add_initial_output_data(file_header); | |
61ba1cf9 | 340 | this->special_output_list_.push_back(file_header); |
75f65a3e ILT |
341 | |
342 | // Set the file offsets of all the segments. | |
343 | off_t off = this->set_segment_offsets(input_objects->target(), load_seg); | |
344 | ||
345 | // Create the symbol table sections. | |
346 | // FIXME: We don't need to do this if we are stripping symbols. | |
347 | Output_section* osymtab; | |
348 | Output_section* ostrtab; | |
61ba1cf9 ILT |
349 | this->create_symtab_sections(size, input_objects, symtab, &off, |
350 | &osymtab, &ostrtab); | |
75f65a3e ILT |
351 | |
352 | // Create the .shstrtab section. | |
353 | Output_section* shstrtab_section = this->create_shstrtab(); | |
354 | ||
355 | // Set the file offsets of all the sections not associated with | |
356 | // segments. | |
357 | off = this->set_section_offsets(off); | |
358 | ||
359 | // Create the section table header. | |
61ba1cf9 | 360 | Output_section_headers* oshdrs = this->create_shdrs(size, big_endian, &off); |
75f65a3e ILT |
361 | |
362 | file_header->set_section_info(oshdrs, shstrtab_section); | |
363 | ||
364 | // Now we know exactly where everything goes in the output file. | |
365 | ||
366 | return off; | |
367 | } | |
368 | ||
369 | // Return whether SEG1 should be before SEG2 in the output file. This | |
370 | // is based entirely on the segment type and flags. When this is | |
371 | // called the segment addresses has normally not yet been set. | |
372 | ||
373 | bool | |
374 | Layout::segment_precedes(const Output_segment* seg1, | |
375 | const Output_segment* seg2) | |
376 | { | |
377 | elfcpp::Elf_Word type1 = seg1->type(); | |
378 | elfcpp::Elf_Word type2 = seg2->type(); | |
379 | ||
380 | // The single PT_PHDR segment is required to precede any loadable | |
381 | // segment. We simply make it always first. | |
382 | if (type1 == elfcpp::PT_PHDR) | |
383 | { | |
384 | assert(type2 != elfcpp::PT_PHDR); | |
385 | return true; | |
386 | } | |
387 | if (type2 == elfcpp::PT_PHDR) | |
388 | return false; | |
389 | ||
390 | // The single PT_INTERP segment is required to precede any loadable | |
391 | // segment. We simply make it always second. | |
392 | if (type1 == elfcpp::PT_INTERP) | |
393 | { | |
394 | assert(type2 != elfcpp::PT_INTERP); | |
395 | return true; | |
396 | } | |
397 | if (type2 == elfcpp::PT_INTERP) | |
398 | return false; | |
399 | ||
400 | // We then put PT_LOAD segments before any other segments. | |
401 | if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD) | |
402 | return true; | |
403 | if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD) | |
404 | return false; | |
405 | ||
92e059d8 ILT |
406 | // We put the PT_TLS segment last, because that is where the dynamic |
407 | // linker expects to find it (this is just for efficiency; other | |
408 | // positions would also work correctly). | |
409 | if (type1 == elfcpp::PT_TLS && type2 != elfcpp::PT_TLS) | |
410 | return false; | |
411 | if (type2 == elfcpp::PT_TLS && type1 != elfcpp::PT_TLS) | |
412 | return true; | |
413 | ||
75f65a3e ILT |
414 | const elfcpp::Elf_Word flags1 = seg1->flags(); |
415 | const elfcpp::Elf_Word flags2 = seg2->flags(); | |
416 | ||
417 | // The order of non-PT_LOAD segments is unimportant. We simply sort | |
418 | // by the numeric segment type and flags values. There should not | |
419 | // be more than one segment with the same type and flags. | |
420 | if (type1 != elfcpp::PT_LOAD) | |
421 | { | |
422 | if (type1 != type2) | |
423 | return type1 < type2; | |
424 | assert(flags1 != flags2); | |
425 | return flags1 < flags2; | |
426 | } | |
427 | ||
428 | // We sort PT_LOAD segments based on the flags. Readonly segments | |
429 | // come before writable segments. Then executable segments come | |
430 | // before non-executable segments. Then the unlikely case of a | |
431 | // non-readable segment comes before the normal case of a readable | |
432 | // segment. If there are multiple segments with the same type and | |
433 | // flags, we require that the address be set, and we sort by | |
434 | // virtual address and then physical address. | |
435 | if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W)) | |
436 | return (flags1 & elfcpp::PF_W) == 0; | |
437 | if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X)) | |
438 | return (flags1 & elfcpp::PF_X) != 0; | |
439 | if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R)) | |
440 | return (flags1 & elfcpp::PF_R) == 0; | |
441 | ||
442 | uint64_t vaddr1 = seg1->vaddr(); | |
443 | uint64_t vaddr2 = seg2->vaddr(); | |
444 | if (vaddr1 != vaddr2) | |
445 | return vaddr1 < vaddr2; | |
446 | ||
447 | uint64_t paddr1 = seg1->paddr(); | |
448 | uint64_t paddr2 = seg2->paddr(); | |
449 | assert(paddr1 != paddr2); | |
450 | return paddr1 < paddr2; | |
451 | } | |
452 | ||
453 | // Set the file offsets of all the segments. They have all been | |
454 | // created. LOAD_SEG must be be laid out first. Return the offset of | |
455 | // the data to follow. | |
456 | ||
457 | off_t | |
458 | Layout::set_segment_offsets(const Target* target, Output_segment* load_seg) | |
459 | { | |
460 | // Sort them into the final order. | |
54dc6425 ILT |
461 | std::sort(this->segment_list_.begin(), this->segment_list_.end(), |
462 | Layout::Compare_segments()); | |
463 | ||
75f65a3e ILT |
464 | // Find the PT_LOAD segments, and set their addresses and offsets |
465 | // and their section's addresses and offsets. | |
466 | uint64_t addr = target->text_segment_address(); | |
467 | off_t off = 0; | |
468 | bool was_readonly = false; | |
469 | for (Segment_list::iterator p = this->segment_list_.begin(); | |
470 | p != this->segment_list_.end(); | |
471 | ++p) | |
472 | { | |
473 | if ((*p)->type() == elfcpp::PT_LOAD) | |
474 | { | |
475 | if (load_seg != NULL && load_seg != *p) | |
476 | abort(); | |
477 | load_seg = NULL; | |
478 | ||
479 | // If the last segment was readonly, and this one is not, | |
480 | // then skip the address forward one page, maintaining the | |
481 | // same position within the page. This lets us store both | |
482 | // segments overlapping on a single page in the file, but | |
483 | // the loader will put them on different pages in memory. | |
484 | ||
485 | uint64_t orig_addr = addr; | |
486 | uint64_t orig_off = off; | |
487 | ||
488 | uint64_t aligned_addr = addr; | |
489 | uint64_t abi_pagesize = target->abi_pagesize(); | |
490 | if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0) | |
491 | { | |
492 | uint64_t align = (*p)->max_data_align(); | |
493 | ||
494 | addr = (addr + align - 1) & ~ (align - 1); | |
495 | aligned_addr = addr; | |
496 | if ((addr & (abi_pagesize - 1)) != 0) | |
497 | addr = addr + abi_pagesize; | |
498 | } | |
499 | ||
500 | off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); | |
501 | uint64_t new_addr = (*p)->set_section_addresses(addr, &off); | |
502 | ||
503 | // Now that we know the size of this segment, we may be able | |
504 | // to save a page in memory, at the cost of wasting some | |
505 | // file space, by instead aligning to the start of a new | |
506 | // page. Here we use the real machine page size rather than | |
507 | // the ABI mandated page size. | |
508 | ||
509 | if (aligned_addr != addr) | |
510 | { | |
511 | uint64_t common_pagesize = target->common_pagesize(); | |
512 | uint64_t first_off = (common_pagesize | |
513 | - (aligned_addr | |
514 | & (common_pagesize - 1))); | |
515 | uint64_t last_off = new_addr & (common_pagesize - 1); | |
516 | if (first_off > 0 | |
517 | && last_off > 0 | |
518 | && ((aligned_addr & ~ (common_pagesize - 1)) | |
519 | != (new_addr & ~ (common_pagesize - 1))) | |
520 | && first_off + last_off <= common_pagesize) | |
521 | { | |
522 | addr = ((aligned_addr + common_pagesize - 1) | |
523 | & ~ (common_pagesize - 1)); | |
524 | off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); | |
525 | new_addr = (*p)->set_section_addresses(addr, &off); | |
526 | } | |
527 | } | |
528 | ||
529 | addr = new_addr; | |
530 | ||
531 | if (((*p)->flags() & elfcpp::PF_W) == 0) | |
532 | was_readonly = true; | |
533 | } | |
534 | } | |
535 | ||
536 | // Handle the non-PT_LOAD segments, setting their offsets from their | |
537 | // section's offsets. | |
538 | for (Segment_list::iterator p = this->segment_list_.begin(); | |
539 | p != this->segment_list_.end(); | |
540 | ++p) | |
541 | { | |
542 | if ((*p)->type() != elfcpp::PT_LOAD) | |
543 | (*p)->set_offset(); | |
544 | } | |
545 | ||
546 | return off; | |
547 | } | |
548 | ||
549 | // Set the file offset of all the sections not associated with a | |
550 | // segment. | |
551 | ||
552 | off_t | |
553 | Layout::set_section_offsets(off_t off) | |
554 | { | |
555 | for (Layout::Section_list::iterator p = this->section_list_.begin(); | |
556 | p != this->section_list_.end(); | |
557 | ++p) | |
558 | { | |
61ba1cf9 ILT |
559 | if ((*p)->offset() != -1) |
560 | continue; | |
75f65a3e | 561 | uint64_t addralign = (*p)->addralign(); |
61ba1cf9 ILT |
562 | if (addralign != 0) |
563 | off = (off + addralign - 1) & ~ (addralign - 1); | |
75f65a3e ILT |
564 | (*p)->set_address(0, off); |
565 | off += (*p)->data_size(); | |
566 | } | |
567 | return off; | |
568 | } | |
569 | ||
570 | // Create the symbol table sections. | |
571 | ||
572 | void | |
61ba1cf9 | 573 | Layout::create_symtab_sections(int size, const Input_objects* input_objects, |
75f65a3e | 574 | Symbol_table* symtab, |
61ba1cf9 | 575 | off_t* poff, |
75f65a3e ILT |
576 | Output_section** posymtab, |
577 | Output_section** postrtab) | |
578 | { | |
61ba1cf9 ILT |
579 | int symsize; |
580 | unsigned int align; | |
581 | if (size == 32) | |
582 | { | |
583 | symsize = elfcpp::Elf_sizes<32>::sym_size; | |
584 | align = 4; | |
585 | } | |
586 | else if (size == 64) | |
587 | { | |
588 | symsize = elfcpp::Elf_sizes<64>::sym_size; | |
589 | align = 8; | |
590 | } | |
591 | else | |
592 | abort(); | |
593 | ||
594 | off_t off = *poff; | |
595 | off = (off + align - 1) & ~ (align - 1); | |
596 | off_t startoff = off; | |
597 | ||
598 | // Save space for the dummy symbol at the start of the section. We | |
599 | // never bother to write this out--it will just be left as zero. | |
600 | off += symsize; | |
601 | ||
75f65a3e ILT |
602 | for (Input_objects::Object_list::const_iterator p = input_objects->begin(); |
603 | p != input_objects->end(); | |
604 | ++p) | |
605 | { | |
606 | Task_lock_obj<Object> tlo(**p); | |
607 | off = (*p)->finalize_local_symbols(off, &this->sympool_); | |
608 | } | |
609 | ||
61ba1cf9 ILT |
610 | unsigned int local_symcount = (off - startoff) / symsize; |
611 | assert(local_symcount * symsize == off - startoff); | |
612 | ||
75f65a3e ILT |
613 | off = symtab->finalize(off, &this->sympool_); |
614 | ||
61ba1cf9 ILT |
615 | this->sympool_.set_string_offsets(); |
616 | ||
617 | ++this->last_shndx_; | |
618 | const char* symtab_name = this->namepool_.add(".symtab"); | |
619 | Output_section* osymtab = new Output_section_symtab(symtab_name, | |
620 | off - startoff, | |
621 | this->last_shndx_); | |
622 | this->section_list_.push_back(osymtab); | |
623 | ||
624 | ++this->last_shndx_; | |
625 | const char* strtab_name = this->namepool_.add(".strtab"); | |
626 | Output_section *ostrtab = new Output_section_strtab(strtab_name, | |
627 | &this->sympool_, | |
628 | this->last_shndx_); | |
629 | this->section_list_.push_back(ostrtab); | |
630 | this->special_output_list_.push_back(ostrtab); | |
631 | ||
632 | osymtab->set_address(0, startoff); | |
633 | osymtab->set_link(ostrtab->shndx()); | |
634 | osymtab->set_info(local_symcount); | |
635 | osymtab->set_entsize(symsize); | |
636 | osymtab->set_addralign(align); | |
637 | ||
638 | *poff = off; | |
639 | *posymtab = osymtab; | |
640 | *postrtab = ostrtab; | |
75f65a3e ILT |
641 | } |
642 | ||
643 | // Create the .shstrtab section, which holds the names of the | |
644 | // sections. At the time this is called, we have created all the | |
645 | // output sections except .shstrtab itself. | |
646 | ||
647 | Output_section* | |
648 | Layout::create_shstrtab() | |
649 | { | |
650 | // FIXME: We don't need to create a .shstrtab section if we are | |
651 | // stripping everything. | |
652 | ||
653 | const char* name = this->namepool_.add(".shstrtab"); | |
654 | ||
61ba1cf9 ILT |
655 | this->namepool_.set_string_offsets(); |
656 | ||
657 | ++this->last_shndx_; | |
75f65a3e | 658 | Output_section* os = new Output_section_strtab(name, |
61ba1cf9 ILT |
659 | &this->namepool_, |
660 | this->last_shndx_); | |
75f65a3e ILT |
661 | |
662 | this->section_list_.push_back(os); | |
61ba1cf9 | 663 | this->special_output_list_.push_back(os); |
75f65a3e ILT |
664 | |
665 | return os; | |
666 | } | |
667 | ||
668 | // Create the section headers. SIZE is 32 or 64. OFF is the file | |
669 | // offset. | |
670 | ||
671 | Output_section_headers* | |
61ba1cf9 | 672 | Layout::create_shdrs(int size, bool big_endian, off_t* poff) |
75f65a3e ILT |
673 | { |
674 | Output_section_headers* oshdrs; | |
61ba1cf9 ILT |
675 | oshdrs = new Output_section_headers(size, big_endian, this->segment_list_, |
676 | this->section_list_, | |
677 | &this->namepool_); | |
75f65a3e | 678 | uint64_t addralign = oshdrs->addralign(); |
61ba1cf9 | 679 | off_t off = (*poff + addralign - 1) & ~ (addralign - 1); |
75f65a3e | 680 | oshdrs->set_address(0, off); |
61ba1cf9 ILT |
681 | off += oshdrs->data_size(); |
682 | *poff = off; | |
683 | this->special_output_list_.push_back(oshdrs); | |
75f65a3e | 684 | return oshdrs; |
54dc6425 ILT |
685 | } |
686 | ||
a2fb1b05 ILT |
687 | // The mapping of .gnu.linkonce section names to real section names. |
688 | ||
689 | #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t } | |
690 | const Layout::Linkonce_mapping Layout::linkonce_mapping[] = | |
691 | { | |
692 | MAPPING_INIT("d.rel.ro", ".data.rel.ro"), // Must be before "d". | |
693 | MAPPING_INIT("t", ".text"), | |
694 | MAPPING_INIT("r", ".rodata"), | |
695 | MAPPING_INIT("d", ".data"), | |
696 | MAPPING_INIT("b", ".bss"), | |
697 | MAPPING_INIT("s", ".sdata"), | |
698 | MAPPING_INIT("sb", ".sbss"), | |
699 | MAPPING_INIT("s2", ".sdata2"), | |
700 | MAPPING_INIT("sb2", ".sbss2"), | |
701 | MAPPING_INIT("wi", ".debug_info"), | |
702 | MAPPING_INIT("td", ".tdata"), | |
703 | MAPPING_INIT("tb", ".tbss"), | |
704 | MAPPING_INIT("lr", ".lrodata"), | |
705 | MAPPING_INIT("l", ".ldata"), | |
706 | MAPPING_INIT("lb", ".lbss"), | |
707 | }; | |
708 | #undef MAPPING_INIT | |
709 | ||
710 | const int Layout::linkonce_mapping_count = | |
711 | sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]); | |
712 | ||
713 | // Return the name of the output section to use for a .gnu.linkonce | |
714 | // section. This is based on the default ELF linker script of the old | |
715 | // GNU linker. For example, we map a name like ".gnu.linkonce.t.foo" | |
716 | // to ".text". | |
717 | ||
718 | const char* | |
719 | Layout::linkonce_output_name(const char* name) | |
720 | { | |
721 | const char* s = name + sizeof(".gnu.linkonce") - 1; | |
722 | if (*s != '.') | |
723 | return name; | |
724 | ++s; | |
725 | const Linkonce_mapping* plm = linkonce_mapping; | |
726 | for (int i = 0; i < linkonce_mapping_count; ++i, ++plm) | |
727 | { | |
728 | if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.') | |
729 | return plm->to; | |
730 | } | |
731 | return name; | |
732 | } | |
733 | ||
734 | // Record the signature of a comdat section, and return whether to | |
735 | // include it in the link. If GROUP is true, this is a regular | |
736 | // section group. If GROUP is false, this is a group signature | |
737 | // derived from the name of a linkonce section. We want linkonce | |
738 | // signatures and group signatures to block each other, but we don't | |
739 | // want a linkonce signature to block another linkonce signature. | |
740 | ||
741 | bool | |
742 | Layout::add_comdat(const char* signature, bool group) | |
743 | { | |
744 | std::string sig(signature); | |
745 | std::pair<Signatures::iterator, bool> ins( | |
746 | this->signatures_.insert(std::make_pair(signature, group))); | |
747 | ||
748 | if (ins.second) | |
749 | { | |
750 | // This is the first time we've seen this signature. | |
751 | return true; | |
752 | } | |
753 | ||
754 | if (ins.first->second) | |
755 | { | |
756 | // We've already seen a real section group with this signature. | |
757 | return false; | |
758 | } | |
759 | else if (group) | |
760 | { | |
761 | // This is a real section group, and we've already seen a | |
762 | // linkonce section with tihs signature. Record that we've seen | |
763 | // a section group, and don't include this section group. | |
764 | ins.first->second = true; | |
765 | return false; | |
766 | } | |
767 | else | |
768 | { | |
769 | // We've already seen a linkonce section and this is a linkonce | |
770 | // section. These don't block each other--this may be the same | |
771 | // symbol name with different section types. | |
772 | return true; | |
773 | } | |
774 | } | |
775 | ||
61ba1cf9 ILT |
776 | // Write out data not associated with a section or the symbol table. |
777 | ||
778 | void | |
779 | Layout::write_data(Output_file* of) const | |
780 | { | |
781 | for (Data_list::const_iterator p = this->special_output_list_.begin(); | |
782 | p != this->special_output_list_.end(); | |
783 | ++p) | |
784 | (*p)->write(of); | |
785 | } | |
786 | ||
787 | // Write_data_task methods. | |
788 | ||
789 | // We can always run this task. | |
790 | ||
791 | Task::Is_runnable_type | |
792 | Write_data_task::is_runnable(Workqueue*) | |
793 | { | |
794 | return IS_RUNNABLE; | |
795 | } | |
796 | ||
797 | // We need to unlock FINAL_BLOCKER when finished. | |
798 | ||
799 | Task_locker* | |
800 | Write_data_task::locks(Workqueue* workqueue) | |
801 | { | |
802 | return new Task_locker_block(*this->final_blocker_, workqueue); | |
803 | } | |
804 | ||
805 | // Run the task--write out the data. | |
806 | ||
807 | void | |
808 | Write_data_task::run(Workqueue*) | |
809 | { | |
810 | this->layout_->write_data(this->of_); | |
811 | } | |
812 | ||
813 | // Write_symbols_task methods. | |
814 | ||
815 | // We can always run this task. | |
816 | ||
817 | Task::Is_runnable_type | |
818 | Write_symbols_task::is_runnable(Workqueue*) | |
819 | { | |
820 | return IS_RUNNABLE; | |
821 | } | |
822 | ||
823 | // We need to unlock FINAL_BLOCKER when finished. | |
824 | ||
825 | Task_locker* | |
826 | Write_symbols_task::locks(Workqueue* workqueue) | |
827 | { | |
828 | return new Task_locker_block(*this->final_blocker_, workqueue); | |
829 | } | |
830 | ||
831 | // Run the task--write out the symbols. | |
832 | ||
833 | void | |
834 | Write_symbols_task::run(Workqueue*) | |
835 | { | |
836 | this->symtab_->write_globals(this->target_, this->sympool_, this->of_); | |
837 | } | |
838 | ||
92e059d8 | 839 | // Close_task_runner methods. |
61ba1cf9 ILT |
840 | |
841 | // Run the task--close the file. | |
842 | ||
843 | void | |
92e059d8 | 844 | Close_task_runner::run(Workqueue*) |
61ba1cf9 ILT |
845 | { |
846 | this->of_->close(); | |
847 | } | |
848 | ||
a2fb1b05 ILT |
849 | // Instantiate the templates we need. We could use the configure |
850 | // script to restrict this to only the ones for implemented targets. | |
851 | ||
852 | template | |
853 | Output_section* | |
854 | Layout::layout<32, false>(Object* object, const char* name, | |
855 | const elfcpp::Shdr<32, false>& shdr, off_t*); | |
856 | ||
857 | template | |
858 | Output_section* | |
859 | Layout::layout<32, true>(Object* object, const char* name, | |
860 | const elfcpp::Shdr<32, true>& shdr, off_t*); | |
861 | ||
862 | template | |
863 | Output_section* | |
864 | Layout::layout<64, false>(Object* object, const char* name, | |
865 | const elfcpp::Shdr<64, false>& shdr, off_t*); | |
866 | ||
867 | template | |
868 | Output_section* | |
869 | Layout::layout<64, true>(Object* object, const char* name, | |
870 | const elfcpp::Shdr<64, true>& shdr, off_t*); | |
871 | ||
872 | ||
873 | } // End namespace gold. |