| 1 | /* Emulation code used by all ELF targets. |
| 2 | Copyright (C) 1991-2021 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of the GNU Binutils. |
| 5 | |
| 6 | This program is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 3 of the License, or |
| 9 | (at your option) any later version. |
| 10 | |
| 11 | This program is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with this program; if not, write to the Free Software |
| 18 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 19 | MA 02110-1301, USA. */ |
| 20 | |
| 21 | #include "sysdep.h" |
| 22 | #include "bfd.h" |
| 23 | #include "bfdlink.h" |
| 24 | #include "ctf-api.h" |
| 25 | #include "ld.h" |
| 26 | #include "ldmain.h" |
| 27 | #include "ldmisc.h" |
| 28 | #include "ldexp.h" |
| 29 | #include "ldlang.h" |
| 30 | #include "ldctor.h" |
| 31 | #include "elf-bfd.h" |
| 32 | #include "elf/internal.h" |
| 33 | #include "ldelfgen.h" |
| 34 | |
| 35 | /* Info attached to an output_section_statement about input sections, |
| 36 | used when sorting SHF_LINK_ORDER sections. */ |
| 37 | |
| 38 | struct os_sections |
| 39 | { |
| 40 | /* Size allocated for isec. */ |
| 41 | unsigned int alloc; |
| 42 | /* Used entries in isec. */ |
| 43 | unsigned int count; |
| 44 | /* How many are SHF_LINK_ORDER. */ |
| 45 | unsigned int ordered; |
| 46 | /* Input sections attached to this output section. */ |
| 47 | struct os_sections_input { |
| 48 | lang_input_section_type *is; |
| 49 | unsigned int idx; |
| 50 | } isec[1]; |
| 51 | }; |
| 52 | |
| 53 | /* Add IS to data kept for OS. */ |
| 54 | |
| 55 | static bfd_boolean |
| 56 | add_link_order_input_section (lang_input_section_type *is, |
| 57 | lang_output_section_statement_type *os) |
| 58 | { |
| 59 | struct os_sections *os_info = os->data; |
| 60 | asection *s; |
| 61 | |
| 62 | if (os_info == NULL) |
| 63 | { |
| 64 | os_info = xmalloc (sizeof (*os_info) + 63 * sizeof (*os_info->isec)); |
| 65 | os_info->alloc = 64; |
| 66 | os_info->count = 0; |
| 67 | os_info->ordered = 0; |
| 68 | os->data = os_info; |
| 69 | } |
| 70 | if (os_info->count == os_info->alloc) |
| 71 | { |
| 72 | size_t want; |
| 73 | os_info->alloc *= 2; |
| 74 | want = sizeof (*os_info) + (os_info->alloc - 1) * sizeof (*os_info->isec); |
| 75 | os_info = xrealloc (os_info, want); |
| 76 | os->data = os_info; |
| 77 | } |
| 78 | os_info->isec[os_info->count].is = is; |
| 79 | os_info->isec[os_info->count].idx = os_info->count; |
| 80 | os_info->count++; |
| 81 | s = is->section; |
| 82 | if (bfd_get_flavour (s->owner) == bfd_target_elf_flavour |
| 83 | && (s->flags & SEC_LINKER_CREATED) == 0 |
| 84 | && elf_linked_to_section (s) != NULL) |
| 85 | os_info->ordered++; |
| 86 | return FALSE; |
| 87 | } |
| 88 | |
| 89 | /* Run over the linker's statement list, extracting info about input |
| 90 | sections attached to each output section. */ |
| 91 | |
| 92 | static bfd_boolean |
| 93 | link_order_scan (lang_statement_union_type *u, |
| 94 | lang_output_section_statement_type *os) |
| 95 | { |
| 96 | asection *s; |
| 97 | bfd_boolean ret = FALSE; |
| 98 | |
| 99 | for (; u != NULL; u = u->header.next) |
| 100 | { |
| 101 | switch (u->header.type) |
| 102 | { |
| 103 | case lang_wild_statement_enum: |
| 104 | if (link_order_scan (u->wild_statement.children.head, os)) |
| 105 | ret = TRUE; |
| 106 | break; |
| 107 | case lang_constructors_statement_enum: |
| 108 | if (link_order_scan (constructor_list.head, os)) |
| 109 | ret = TRUE; |
| 110 | break; |
| 111 | case lang_output_section_statement_enum: |
| 112 | if (u->output_section_statement.constraint != -1 |
| 113 | && link_order_scan (u->output_section_statement.children.head, |
| 114 | &u->output_section_statement)) |
| 115 | ret = TRUE; |
| 116 | break; |
| 117 | case lang_group_statement_enum: |
| 118 | if (link_order_scan (u->group_statement.children.head, os)) |
| 119 | ret = TRUE; |
| 120 | break; |
| 121 | case lang_input_section_enum: |
| 122 | s = u->input_section.section; |
| 123 | if (s->output_section != NULL |
| 124 | && s->output_section->owner == link_info.output_bfd |
| 125 | && (s->output_section->flags & SEC_EXCLUDE) == 0 |
| 126 | && ((s->output_section->flags & SEC_HAS_CONTENTS) != 0 |
| 127 | || ((s->output_section->flags & (SEC_LOAD | SEC_THREAD_LOCAL)) |
| 128 | == (SEC_LOAD | SEC_THREAD_LOCAL)))) |
| 129 | if (add_link_order_input_section (&u->input_section, os)) |
| 130 | ret = TRUE; |
| 131 | break; |
| 132 | default: |
| 133 | break; |
| 134 | } |
| 135 | } |
| 136 | return ret; |
| 137 | } |
| 138 | |
| 139 | /* Compare two sections based on the locations of the sections they are |
| 140 | linked to. Used by fixup_link_order. */ |
| 141 | |
| 142 | static int |
| 143 | compare_link_order (const void *a, const void *b) |
| 144 | { |
| 145 | const struct os_sections_input *ai = a; |
| 146 | const struct os_sections_input *bi = b; |
| 147 | asection *asec = NULL; |
| 148 | asection *bsec = NULL; |
| 149 | bfd_vma apos, bpos; |
| 150 | |
| 151 | if (bfd_get_flavour (ai->is->section->owner) == bfd_target_elf_flavour) |
| 152 | asec = elf_linked_to_section (ai->is->section); |
| 153 | if (bfd_get_flavour (bi->is->section->owner) == bfd_target_elf_flavour) |
| 154 | bsec = elf_linked_to_section (bi->is->section); |
| 155 | |
| 156 | /* Place unordered sections before ordered sections. */ |
| 157 | if (asec == NULL || bsec == NULL) |
| 158 | { |
| 159 | if (bsec != NULL) |
| 160 | return -1; |
| 161 | else if (asec != NULL) |
| 162 | return 1; |
| 163 | return ai->idx - bi->idx; |
| 164 | } |
| 165 | |
| 166 | apos = asec->output_section->lma + asec->output_offset; |
| 167 | bpos = bsec->output_section->lma + bsec->output_offset; |
| 168 | |
| 169 | if (apos < bpos) |
| 170 | return -1; |
| 171 | else if (apos > bpos) |
| 172 | return 1; |
| 173 | |
| 174 | /* The only way we should get matching LMAs is when the first of two |
| 175 | sections has zero size. */ |
| 176 | if (asec->size < bsec->size) |
| 177 | return -1; |
| 178 | else if (asec->size > bsec->size) |
| 179 | return 1; |
| 180 | |
| 181 | /* If they are both zero size then they almost certainly have the same |
| 182 | VMA and thus are not ordered with respect to each other. Test VMA |
| 183 | anyway, and fall back to id to make the result reproducible across |
| 184 | qsort implementations. */ |
| 185 | apos = asec->output_section->vma + asec->output_offset; |
| 186 | bpos = bsec->output_section->vma + bsec->output_offset; |
| 187 | if (apos < bpos) |
| 188 | return -1; |
| 189 | else if (apos > bpos) |
| 190 | return 1; |
| 191 | |
| 192 | return asec->id - bsec->id; |
| 193 | } |
| 194 | |
| 195 | /* Rearrange sections with SHF_LINK_ORDER into the same order as their |
| 196 | linked sections. */ |
| 197 | |
| 198 | static bfd_boolean |
| 199 | fixup_link_order (lang_output_section_statement_type *os) |
| 200 | { |
| 201 | struct os_sections *os_info = os->data; |
| 202 | unsigned int i, j; |
| 203 | lang_input_section_type **orig_is; |
| 204 | asection **save_s; |
| 205 | |
| 206 | for (i = 0; i < os_info->count; i = j) |
| 207 | { |
| 208 | /* Normally a linker script will select SHF_LINK_ORDER sections |
| 209 | with an input section wildcard something like the following: |
| 210 | *(.IA_64.unwind* .gnu.linkonce.ia64unw.*) |
| 211 | However if some other random sections are smashed into an |
| 212 | output section, or if SHF_LINK_ORDER are split up by the |
| 213 | linker script, then we only want to sort sections matching a |
| 214 | given wildcard. That's the purpose of the pattern test. */ |
| 215 | for (j = i + 1; j < os_info->count; j++) |
| 216 | if (os_info->isec[j].is->pattern != os_info->isec[i].is->pattern) |
| 217 | break; |
| 218 | if (j - i > 1) |
| 219 | qsort (&os_info->isec[i], j - i, sizeof (*os_info->isec), |
| 220 | compare_link_order); |
| 221 | } |
| 222 | for (i = 0; i < os_info->count; i++) |
| 223 | if (os_info->isec[i].idx != i) |
| 224 | break; |
| 225 | if (i == os_info->count) |
| 226 | return FALSE; |
| 227 | |
| 228 | /* Now reorder the linker input section statements to reflect the |
| 229 | proper sorting. The is done by rewriting the existing statements |
| 230 | rather than fiddling with lists, since the only thing we need to |
| 231 | change is the bfd section pointer. */ |
| 232 | orig_is = xmalloc (os_info->count * sizeof (*orig_is)); |
| 233 | save_s = xmalloc (os_info->count * sizeof (*save_s)); |
| 234 | for (i = 0; i < os_info->count; i++) |
| 235 | { |
| 236 | orig_is[os_info->isec[i].idx] = os_info->isec[i].is; |
| 237 | save_s[i] = os_info->isec[i].is->section; |
| 238 | } |
| 239 | for (i = 0; i < os_info->count; i++) |
| 240 | if (os_info->isec[i].idx != i) |
| 241 | { |
| 242 | orig_is[i]->section = save_s[i]; |
| 243 | /* Restore os_info to pristine state before the qsort, for the |
| 244 | next pass over sections. */ |
| 245 | os_info->isec[i].is = orig_is[i]; |
| 246 | os_info->isec[i].idx = i; |
| 247 | } |
| 248 | free (save_s); |
| 249 | free (orig_is); |
| 250 | return TRUE; |
| 251 | } |
| 252 | |
| 253 | void |
| 254 | ldelf_map_segments (bfd_boolean need_layout) |
| 255 | { |
| 256 | int tries = 10; |
| 257 | static bfd_boolean done_link_order_scan = FALSE; |
| 258 | |
| 259 | do |
| 260 | { |
| 261 | lang_relax_sections (need_layout); |
| 262 | need_layout = FALSE; |
| 263 | |
| 264 | if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour) |
| 265 | { |
| 266 | lang_output_section_statement_type *os; |
| 267 | if (!done_link_order_scan) |
| 268 | { |
| 269 | link_order_scan (statement_list.head, NULL); |
| 270 | done_link_order_scan = TRUE; |
| 271 | } |
| 272 | for (os = (void *) lang_os_list.head; os != NULL; os = os->next) |
| 273 | { |
| 274 | struct os_sections *os_info = os->data; |
| 275 | if (os_info != NULL && os_info->ordered != 0) |
| 276 | { |
| 277 | if (os_info->ordered != os_info->count |
| 278 | && bfd_link_relocatable (&link_info)) |
| 279 | { |
| 280 | einfo (_("%F%P: " |
| 281 | "%pA has both ordered and unordered sections"), |
| 282 | os->bfd_section); |
| 283 | return; |
| 284 | } |
| 285 | if (os_info->count > 1 |
| 286 | && fixup_link_order (os)) |
| 287 | need_layout = TRUE; |
| 288 | } |
| 289 | } |
| 290 | } |
| 291 | |
| 292 | if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour |
| 293 | && !bfd_link_relocatable (&link_info)) |
| 294 | { |
| 295 | bfd_size_type phdr_size; |
| 296 | |
| 297 | phdr_size = elf_program_header_size (link_info.output_bfd); |
| 298 | /* If we don't have user supplied phdrs, throw away any |
| 299 | previous linker generated program headers. */ |
| 300 | if (lang_phdr_list == NULL) |
| 301 | elf_seg_map (link_info.output_bfd) = NULL; |
| 302 | if (!_bfd_elf_map_sections_to_segments (link_info.output_bfd, |
| 303 | &link_info)) |
| 304 | einfo (_("%F%P: map sections to segments failed: %E\n")); |
| 305 | |
| 306 | if (phdr_size != elf_program_header_size (link_info.output_bfd)) |
| 307 | { |
| 308 | if (tries > 6) |
| 309 | /* The first few times we allow any change to |
| 310 | phdr_size . */ |
| 311 | need_layout = TRUE; |
| 312 | else if (phdr_size |
| 313 | < elf_program_header_size (link_info.output_bfd)) |
| 314 | /* After that we only allow the size to grow. */ |
| 315 | need_layout = TRUE; |
| 316 | else |
| 317 | elf_program_header_size (link_info.output_bfd) = phdr_size; |
| 318 | } |
| 319 | } |
| 320 | } |
| 321 | while (need_layout && --tries); |
| 322 | |
| 323 | if (tries == 0) |
| 324 | einfo (_("%F%P: looping in map_segments")); |
| 325 | |
| 326 | if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour |
| 327 | && lang_phdr_list == NULL) |
| 328 | { |
| 329 | /* If we don't have user supplied phdrs, strip zero-sized dynamic |
| 330 | sections and regenerate program headers. */ |
| 331 | const struct elf_backend_data *bed |
| 332 | = get_elf_backend_data (link_info.output_bfd); |
| 333 | if (bed->elf_backend_strip_zero_sized_dynamic_sections |
| 334 | && !bed->elf_backend_strip_zero_sized_dynamic_sections |
| 335 | (&link_info)) |
| 336 | einfo (_("%F%P: failed to strip zero-sized dynamic sections")); |
| 337 | } |
| 338 | } |
| 339 | |
| 340 | #ifdef ENABLE_LIBCTF |
| 341 | /* We want to emit CTF early if and only if we are not targetting ELF with this |
| 342 | invocation. */ |
| 343 | |
| 344 | int |
| 345 | ldelf_emit_ctf_early (void) |
| 346 | { |
| 347 | if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour) |
| 348 | return 0; |
| 349 | return 1; |
| 350 | } |
| 351 | |
| 352 | /* Callbacks used to map from bfd types to libctf types, under libctf's |
| 353 | control. */ |
| 354 | |
| 355 | struct ctf_strtab_iter_cb_arg |
| 356 | { |
| 357 | struct elf_strtab_hash *strtab; |
| 358 | size_t next_i; |
| 359 | size_t next_idx; |
| 360 | }; |
| 361 | |
| 362 | /* Return strings from the strtab to libctf, one by one. Returns NULL when |
| 363 | iteration is complete. */ |
| 364 | |
| 365 | static const char * |
| 366 | ldelf_ctf_strtab_iter_cb (uint32_t *offset, void *arg_) |
| 367 | { |
| 368 | bfd_size_type off; |
| 369 | const char *ret; |
| 370 | |
| 371 | struct ctf_strtab_iter_cb_arg *arg = |
| 372 | (struct ctf_strtab_iter_cb_arg *) arg_; |
| 373 | |
| 374 | /* There is no zeroth string. */ |
| 375 | if (arg->next_i == 0) |
| 376 | arg->next_i = 1; |
| 377 | |
| 378 | if (arg->next_i >= _bfd_elf_strtab_len (arg->strtab)) |
| 379 | { |
| 380 | arg->next_i = 0; |
| 381 | return NULL; |
| 382 | } |
| 383 | |
| 384 | ret = _bfd_elf_strtab_str (arg->strtab, arg->next_i++, &off); |
| 385 | *offset = off; |
| 386 | |
| 387 | /* If we've overflowed, we cannot share any further strings: the CTF |
| 388 | format cannot encode strings with such high offsets. */ |
| 389 | if (*offset != off) |
| 390 | return NULL; |
| 391 | |
| 392 | return ret; |
| 393 | } |
| 394 | |
| 395 | void |
| 396 | ldelf_acquire_strings_for_ctf |
| 397 | (struct ctf_dict *ctf_output, struct elf_strtab_hash *strtab) |
| 398 | { |
| 399 | struct ctf_strtab_iter_cb_arg args = { strtab, 0, 0 }; |
| 400 | if (!ctf_output) |
| 401 | return; |
| 402 | |
| 403 | if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour) |
| 404 | { |
| 405 | if (ctf_link_add_strtab (ctf_output, ldelf_ctf_strtab_iter_cb, |
| 406 | &args) < 0) |
| 407 | einfo (_("%F%P: warning: CTF strtab association failed; strings will " |
| 408 | "not be shared: %s\n"), |
| 409 | ctf_errmsg (ctf_errno (ctf_output))); |
| 410 | } |
| 411 | } |
| 412 | |
| 413 | void |
| 414 | ldelf_new_dynsym_for_ctf (struct ctf_dict *ctf_output, int symidx, |
| 415 | struct elf_internal_sym *sym) |
| 416 | { |
| 417 | ctf_link_sym_t lsym; |
| 418 | |
| 419 | if (!ctf_output) |
| 420 | return; |
| 421 | |
| 422 | /* New symbol. */ |
| 423 | if (sym != NULL) |
| 424 | { |
| 425 | lsym.st_name = NULL; |
| 426 | lsym.st_nameidx = sym->st_name; |
| 427 | lsym.st_nameidx_set = 1; |
| 428 | lsym.st_symidx = symidx; |
| 429 | lsym.st_shndx = sym->st_shndx; |
| 430 | lsym.st_type = ELF_ST_TYPE (sym->st_info); |
| 431 | lsym.st_value = sym->st_value; |
| 432 | if (ctf_link_add_linker_symbol (ctf_output, &lsym) < 0) |
| 433 | { |
| 434 | einfo (_("%F%P: warning: CTF symbol addition failed; CTF will " |
| 435 | "not be tied to symbols: %s\n"), |
| 436 | ctf_errmsg (ctf_errno (ctf_output))); |
| 437 | } |
| 438 | } |
| 439 | else |
| 440 | { |
| 441 | /* Shuffle all the symbols. */ |
| 442 | |
| 443 | if (ctf_link_shuffle_syms (ctf_output) < 0) |
| 444 | einfo (_("%F%P: warning: CTF symbol shuffling failed; CTF will " |
| 445 | "not be tied to symbols: %s\n"), |
| 446 | ctf_errmsg (ctf_errno (ctf_output))); |
| 447 | } |
| 448 | } |
| 449 | #else |
| 450 | int |
| 451 | ldelf_emit_ctf_early (void) |
| 452 | { |
| 453 | return 0; |
| 454 | } |
| 455 | |
| 456 | void |
| 457 | ldelf_acquire_strings_for_ctf (struct ctf_dict *ctf_output ATTRIBUTE_UNUSED, |
| 458 | struct elf_strtab_hash *strtab ATTRIBUTE_UNUSED) |
| 459 | {} |
| 460 | void |
| 461 | ldelf_new_dynsym_for_ctf (struct ctf_dict *ctf_output ATTRIBUTE_UNUSED, |
| 462 | int symidx ATTRIBUTE_UNUSED, |
| 463 | struct elf_internal_sym *sym ATTRIBUTE_UNUSED) |
| 464 | {} |
| 465 | #endif |