| 1 | /* .eh_frame section optimization. |
| 2 | Copyright 2001 Free Software Foundation, Inc. |
| 3 | Written by Jakub Jelinek <jakub@redhat.com>. |
| 4 | |
| 5 | This file is part of BFD, the Binary File Descriptor library. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 2 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ |
| 20 | |
| 21 | #include "bfd.h" |
| 22 | #include "sysdep.h" |
| 23 | #include "libbfd.h" |
| 24 | #include "elf-bfd.h" |
| 25 | #include "elf/dwarf2.h" |
| 26 | |
| 27 | #define EH_FRAME_HDR_SIZE 8 |
| 28 | |
| 29 | struct cie_header |
| 30 | { |
| 31 | unsigned int length; |
| 32 | unsigned int id; |
| 33 | }; |
| 34 | |
| 35 | struct cie |
| 36 | { |
| 37 | struct cie_header hdr; |
| 38 | unsigned char version; |
| 39 | unsigned char augmentation[20]; |
| 40 | unsigned int code_align; |
| 41 | int data_align; |
| 42 | unsigned int ra_column; |
| 43 | unsigned int augmentation_size; |
| 44 | struct elf_link_hash_entry *personality; |
| 45 | unsigned char per_encoding; |
| 46 | unsigned char lsda_encoding; |
| 47 | unsigned char fde_encoding; |
| 48 | unsigned char initial_insn_length; |
| 49 | unsigned char make_relative; |
| 50 | unsigned char initial_instructions[50]; |
| 51 | }; |
| 52 | |
| 53 | struct eh_cie_fde |
| 54 | { |
| 55 | unsigned int offset; |
| 56 | unsigned int size; |
| 57 | asection *sec; |
| 58 | unsigned int new_offset; |
| 59 | unsigned char fde_encoding; |
| 60 | unsigned char cie : 1; |
| 61 | unsigned char removed : 1; |
| 62 | unsigned char make_relative : 1; |
| 63 | }; |
| 64 | |
| 65 | struct eh_frame_sec_info |
| 66 | { |
| 67 | unsigned int count; |
| 68 | unsigned int alloced; |
| 69 | struct eh_cie_fde entry[1]; |
| 70 | }; |
| 71 | |
| 72 | struct eh_frame_array_ent |
| 73 | { |
| 74 | bfd_vma initial_loc; |
| 75 | bfd_vma fde; |
| 76 | }; |
| 77 | |
| 78 | struct eh_frame_hdr_info |
| 79 | { |
| 80 | struct cie last_cie; |
| 81 | asection *last_cie_sec; |
| 82 | unsigned int last_cie_offset; |
| 83 | unsigned int fde_count, array_count; |
| 84 | struct eh_frame_array_ent *array; |
| 85 | /* TRUE if .eh_frame_hdr should contain the sorted search table. |
| 86 | We build it if we successfully read all .eh_frame input sections |
| 87 | and recognize them. */ |
| 88 | boolean table; |
| 89 | boolean strip; |
| 90 | }; |
| 91 | |
| 92 | static bfd_vma read_unsigned_leb128 |
| 93 | PARAMS ((bfd *, char *, unsigned int *)); |
| 94 | static bfd_signed_vma read_signed_leb128 |
| 95 | PARAMS ((bfd *, char *, unsigned int *)); |
| 96 | static int get_DW_EH_PE_width |
| 97 | PARAMS ((int, int)); |
| 98 | static int cie_compare |
| 99 | PARAMS ((struct cie *, struct cie *)); |
| 100 | static int vma_compare |
| 101 | PARAMS ((const PTR a, const PTR b)); |
| 102 | |
| 103 | /* Helper function for reading uleb128 encoded data. */ |
| 104 | |
| 105 | static bfd_vma |
| 106 | read_unsigned_leb128 (abfd, buf, bytes_read_ptr) |
| 107 | bfd *abfd ATTRIBUTE_UNUSED; |
| 108 | char *buf; |
| 109 | unsigned int *bytes_read_ptr; |
| 110 | { |
| 111 | bfd_vma result; |
| 112 | unsigned int num_read; |
| 113 | int shift; |
| 114 | unsigned char byte; |
| 115 | |
| 116 | result = 0; |
| 117 | shift = 0; |
| 118 | num_read = 0; |
| 119 | do |
| 120 | { |
| 121 | byte = bfd_get_8 (abfd, (bfd_byte *) buf); |
| 122 | buf ++; |
| 123 | num_read ++; |
| 124 | result |= (((bfd_vma) byte & 0x7f) << shift); |
| 125 | shift += 7; |
| 126 | } |
| 127 | while (byte & 0x80); |
| 128 | * bytes_read_ptr = num_read; |
| 129 | return result; |
| 130 | } |
| 131 | |
| 132 | /* Helper function for reading sleb128 encoded data. */ |
| 133 | |
| 134 | static bfd_signed_vma |
| 135 | read_signed_leb128 (abfd, buf, bytes_read_ptr) |
| 136 | bfd *abfd ATTRIBUTE_UNUSED; |
| 137 | char *buf; |
| 138 | unsigned int * bytes_read_ptr; |
| 139 | { |
| 140 | bfd_vma result; |
| 141 | int shift; |
| 142 | int num_read; |
| 143 | unsigned char byte; |
| 144 | |
| 145 | result = 0; |
| 146 | shift = 0; |
| 147 | num_read = 0; |
| 148 | do |
| 149 | { |
| 150 | byte = bfd_get_8 (abfd, (bfd_byte *) buf); |
| 151 | buf ++; |
| 152 | num_read ++; |
| 153 | result |= (((bfd_vma) byte & 0x7f) << shift); |
| 154 | shift += 7; |
| 155 | } |
| 156 | while (byte & 0x80); |
| 157 | if (byte & 0x40) |
| 158 | result |= (((bfd_vma) -1) << (shift - 7)) << 7; |
| 159 | * bytes_read_ptr = num_read; |
| 160 | return result; |
| 161 | } |
| 162 | |
| 163 | #define read_uleb128(VAR, BUF) \ |
| 164 | do \ |
| 165 | { \ |
| 166 | (VAR) = read_unsigned_leb128 (abfd, buf, &leb128_tmp); \ |
| 167 | (BUF) += leb128_tmp; \ |
| 168 | } \ |
| 169 | while (0) |
| 170 | |
| 171 | #define read_sleb128(VAR, BUF) \ |
| 172 | do \ |
| 173 | { \ |
| 174 | (VAR) = read_signed_leb128 (abfd, buf, &leb128_tmp); \ |
| 175 | (BUF) += leb128_tmp; \ |
| 176 | } \ |
| 177 | while (0) |
| 178 | |
| 179 | /* Return 0 if either encoding is variable width, or not yet known to bfd. */ |
| 180 | |
| 181 | static |
| 182 | int get_DW_EH_PE_width (encoding, ptr_size) |
| 183 | int encoding, ptr_size; |
| 184 | { |
| 185 | /* DW_EH_PE_ values of 0x60 and 0x70 weren't defined at the time .eh_frame |
| 186 | was added to bfd. */ |
| 187 | if ((encoding & 0x60) == 0x60) |
| 188 | return 0; |
| 189 | |
| 190 | switch (encoding & 7) |
| 191 | { |
| 192 | case DW_EH_PE_udata2: return 2; |
| 193 | case DW_EH_PE_udata4: return 4; |
| 194 | case DW_EH_PE_udata8: return 8; |
| 195 | case DW_EH_PE_absptr: return ptr_size; |
| 196 | default: |
| 197 | break; |
| 198 | } |
| 199 | |
| 200 | return 0; |
| 201 | } |
| 202 | |
| 203 | /* Return zero if C1 and C2 CIEs can be merged. */ |
| 204 | |
| 205 | static |
| 206 | int cie_compare (c1, c2) |
| 207 | struct cie *c1, *c2; |
| 208 | { |
| 209 | if (c1->hdr.length == c2->hdr.length |
| 210 | && c1->version == c2->version |
| 211 | && strcmp (c1->augmentation, c2->augmentation) == 0 |
| 212 | && strcmp (c1->augmentation, "eh") != 0 |
| 213 | && c1->code_align == c2->code_align |
| 214 | && c1->data_align == c2->data_align |
| 215 | && c1->ra_column == c2->ra_column |
| 216 | && c1->augmentation_size == c2->augmentation_size |
| 217 | && c1->personality == c2->personality |
| 218 | && c1->per_encoding == c2->per_encoding |
| 219 | && c1->lsda_encoding == c2->lsda_encoding |
| 220 | && c1->fde_encoding == c2->fde_encoding |
| 221 | && (c1->initial_insn_length |
| 222 | == c2->initial_insn_length) |
| 223 | && memcmp (c1->initial_instructions, |
| 224 | c2->initial_instructions, |
| 225 | c1->initial_insn_length) == 0) |
| 226 | return 0; |
| 227 | |
| 228 | return 1; |
| 229 | } |
| 230 | |
| 231 | /* This function is called for each input file before the .eh_frame |
| 232 | section is relocated. It discards duplicate CIEs and FDEs for discarded |
| 233 | functions. The function returns true iff any entries have been |
| 234 | deleted. */ |
| 235 | |
| 236 | boolean |
| 237 | _bfd_elf_discard_section_eh_frame (abfd, info, sec, ehdrsec, |
| 238 | reloc_symbol_deleted_p, cookie) |
| 239 | bfd *abfd; |
| 240 | struct bfd_link_info *info; |
| 241 | asection *sec, *ehdrsec; |
| 242 | boolean (*reloc_symbol_deleted_p) (bfd_vma, PTR); |
| 243 | struct elf_reloc_cookie *cookie; |
| 244 | { |
| 245 | bfd_byte *ehbuf = NULL, *buf; |
| 246 | bfd_byte *last_cie, *last_fde; |
| 247 | struct cie_header hdr; |
| 248 | struct cie cie; |
| 249 | struct eh_frame_hdr_info *hdr_info; |
| 250 | struct eh_frame_sec_info *sec_info = NULL; |
| 251 | unsigned int leb128_tmp; |
| 252 | unsigned int cie_usage_count, last_cie_ndx, i, offset, make_relative; |
| 253 | Elf_Internal_Rela *rel; |
| 254 | bfd_size_type new_size; |
| 255 | unsigned int ptr_size; |
| 256 | |
| 257 | if (sec->_raw_size == 0) |
| 258 | { |
| 259 | /* This file does not contain .eh_frame information. */ |
| 260 | return false; |
| 261 | } |
| 262 | |
| 263 | if ((sec->output_section != NULL |
| 264 | && bfd_is_abs_section (sec->output_section))) |
| 265 | { |
| 266 | /* At least one of the sections is being discarded from the |
| 267 | link, so we should just ignore them. */ |
| 268 | return false; |
| 269 | } |
| 270 | |
| 271 | BFD_ASSERT (elf_section_data (ehdrsec)->sec_info_type |
| 272 | == ELF_INFO_TYPE_EH_FRAME_HDR); |
| 273 | hdr_info = (struct eh_frame_hdr_info *) |
| 274 | elf_section_data (ehdrsec)->sec_info; |
| 275 | |
| 276 | /* Read the frame unwind information from abfd. */ |
| 277 | |
| 278 | ehbuf = (bfd_byte *) bfd_malloc (sec->_raw_size); |
| 279 | if (ehbuf == NULL) |
| 280 | goto free_no_table; |
| 281 | |
| 282 | if (! bfd_get_section_contents (abfd, sec, ehbuf, (bfd_vma) 0, |
| 283 | sec->_raw_size)) |
| 284 | goto free_no_table; |
| 285 | |
| 286 | if (sec->_raw_size >= 4 |
| 287 | && bfd_get_32 (abfd, ehbuf) == 0 |
| 288 | && cookie->rel == cookie->relend) |
| 289 | { |
| 290 | /* Empty .eh_frame section. */ |
| 291 | free (ehbuf); |
| 292 | return false; |
| 293 | } |
| 294 | |
| 295 | /* If .eh_frame section size doesn't fit into int, we cannot handle |
| 296 | it (it would need to use 64-bit .eh_frame format anyway). */ |
| 297 | if (sec->_raw_size != (unsigned int) sec->_raw_size) |
| 298 | goto free_no_table; |
| 299 | |
| 300 | ptr_size = (elf_elfheader (abfd)->e_ident[EI_CLASS] |
| 301 | == ELFCLASS64) ? 8 : 4; |
| 302 | buf = ehbuf; |
| 303 | last_cie = NULL; |
| 304 | last_cie_ndx = 0; |
| 305 | memset (&cie, 0, sizeof (cie)); |
| 306 | cie_usage_count = 0; |
| 307 | new_size = sec->_raw_size; |
| 308 | make_relative = hdr_info->last_cie.make_relative; |
| 309 | sec_info = bfd_zmalloc (sizeof (struct eh_frame_sec_info) |
| 310 | + 99 * sizeof (struct eh_cie_fde)); |
| 311 | if (sec_info == NULL) |
| 312 | goto free_no_table; |
| 313 | sec_info->alloced = 100; |
| 314 | |
| 315 | #define ENSURE_NO_RELOCS(buf) \ |
| 316 | if (cookie->rel < cookie->relend \ |
| 317 | && (cookie->rel->r_offset \ |
| 318 | < (bfd_size_type) ((buf) - ehbuf))) \ |
| 319 | goto free_no_table |
| 320 | |
| 321 | #define SKIP_RELOCS(buf) \ |
| 322 | while (cookie->rel < cookie->relend \ |
| 323 | && (cookie->rel->r_offset \ |
| 324 | < (bfd_size_type) ((buf) - ehbuf))) \ |
| 325 | cookie->rel++ |
| 326 | |
| 327 | #define GET_RELOC(buf) \ |
| 328 | ((cookie->rel < cookie->relend \ |
| 329 | && (cookie->rel->r_offset \ |
| 330 | == (bfd_size_type) ((buf) - ehbuf))) \ |
| 331 | ? cookie->rel : NULL) |
| 332 | |
| 333 | for (;;) |
| 334 | { |
| 335 | unsigned char *aug; |
| 336 | |
| 337 | if (sec_info->count == sec_info->alloced) |
| 338 | { |
| 339 | sec_info = bfd_realloc (sec_info, |
| 340 | sizeof (struct eh_frame_sec_info) |
| 341 | + (sec_info->alloced + 99) |
| 342 | * sizeof (struct eh_cie_fde)); |
| 343 | if (sec_info == NULL) |
| 344 | goto free_no_table; |
| 345 | |
| 346 | memset (&sec_info->entry[sec_info->alloced], 0, |
| 347 | 100 * sizeof (struct eh_cie_fde)); |
| 348 | sec_info->alloced += 100; |
| 349 | } |
| 350 | |
| 351 | last_fde = buf; |
| 352 | /* If we are at the end of the section, we still need to decide |
| 353 | on whether to output or discard last encountered CIE (if any). */ |
| 354 | if ((bfd_size_type) (buf - ehbuf) == sec->_raw_size) |
| 355 | hdr.id = (unsigned int) -1; |
| 356 | else |
| 357 | { |
| 358 | if ((bfd_size_type) (buf + 4 - ehbuf) > sec->_raw_size) |
| 359 | /* No space for CIE/FDE header length. */ |
| 360 | goto free_no_table; |
| 361 | |
| 362 | hdr.length = bfd_get_32 (abfd, buf); |
| 363 | if (hdr.length == 0xffffffff) |
| 364 | /* 64-bit .eh_frame is not supported. */ |
| 365 | goto free_no_table; |
| 366 | buf += 4; |
| 367 | if ((buf - ehbuf) + hdr.length > sec->_raw_size) |
| 368 | /* CIE/FDE not contained fully in this .eh_frame input section. */ |
| 369 | goto free_no_table; |
| 370 | |
| 371 | sec_info->entry[sec_info->count].offset = last_fde - ehbuf; |
| 372 | sec_info->entry[sec_info->count].size = 4 + hdr.length; |
| 373 | |
| 374 | if (hdr.length == 0) |
| 375 | { |
| 376 | /* CIE with length 0 must be only the last in the section. */ |
| 377 | if ((bfd_size_type) (buf - ehbuf) < sec->_raw_size) |
| 378 | goto free_no_table; |
| 379 | ENSURE_NO_RELOCS (buf); |
| 380 | sec_info->count++; |
| 381 | /* Now just finish last encountered CIE processing and break |
| 382 | the loop. */ |
| 383 | hdr.id = (unsigned int) -1; |
| 384 | } |
| 385 | else |
| 386 | { |
| 387 | hdr.id = bfd_get_32 (abfd, buf); |
| 388 | buf += 4; |
| 389 | if (hdr.id == (unsigned int) -1) |
| 390 | goto free_no_table; |
| 391 | } |
| 392 | } |
| 393 | |
| 394 | if (hdr.id == 0 || hdr.id == (unsigned int) -1) |
| 395 | { |
| 396 | unsigned int initial_insn_length; |
| 397 | |
| 398 | /* CIE */ |
| 399 | if (last_cie != NULL) |
| 400 | { |
| 401 | /* Now check if this CIE is identical to last CIE, in which case |
| 402 | we can remove it, provided we adjust all FDEs. |
| 403 | Also, it can be removed if we have removed all FDEs using |
| 404 | that. */ |
| 405 | if (cie_compare (&cie, &hdr_info->last_cie) == 0 |
| 406 | || cie_usage_count == 0) |
| 407 | { |
| 408 | new_size -= cie.hdr.length + 4; |
| 409 | sec_info->entry[last_cie_ndx].removed = 1; |
| 410 | sec_info->entry[last_cie_ndx].sec = hdr_info->last_cie_sec; |
| 411 | sec_info->entry[last_cie_ndx].new_offset |
| 412 | = hdr_info->last_cie_offset; |
| 413 | } |
| 414 | else |
| 415 | { |
| 416 | hdr_info->last_cie = cie; |
| 417 | hdr_info->last_cie_sec = sec; |
| 418 | hdr_info->last_cie_offset = last_cie - ehbuf; |
| 419 | sec_info->entry[last_cie_ndx].make_relative |
| 420 | = cie.make_relative; |
| 421 | } |
| 422 | } |
| 423 | |
| 424 | if (hdr.id == (unsigned int) -1) |
| 425 | break; |
| 426 | |
| 427 | last_cie_ndx = sec_info->count; |
| 428 | sec_info->entry[sec_info->count].cie = 1; |
| 429 | |
| 430 | cie_usage_count = 0; |
| 431 | memset (&cie, 0, sizeof (cie)); |
| 432 | cie.hdr = hdr; |
| 433 | cie.version = *buf++; |
| 434 | |
| 435 | /* Cannot handle unknown versions. */ |
| 436 | if (cie.version != 1) |
| 437 | goto free_no_table; |
| 438 | if (strlen (buf) > sizeof (cie.augmentation) - 1) |
| 439 | goto free_no_table; |
| 440 | |
| 441 | strcpy (cie.augmentation, buf); |
| 442 | buf = strchr (buf, '\0') + 1; |
| 443 | ENSURE_NO_RELOCS (buf); |
| 444 | if (buf[0] == 'e' && buf[1] == 'h') |
| 445 | { |
| 446 | /* GCC < 3.0 .eh_frame CIE */ |
| 447 | /* We cannot merge "eh" CIEs because __EXCEPTION_TABLE__ |
| 448 | is private to each CIE, so we don't need it for anything. |
| 449 | Just skip it. */ |
| 450 | buf += ptr_size; |
| 451 | SKIP_RELOCS (buf); |
| 452 | } |
| 453 | read_uleb128 (cie.code_align, buf); |
| 454 | read_sleb128 (cie.data_align, buf); |
| 455 | read_uleb128 (cie.ra_column, buf); |
| 456 | ENSURE_NO_RELOCS (buf); |
| 457 | cie.lsda_encoding = DW_EH_PE_omit; |
| 458 | cie.fde_encoding = DW_EH_PE_omit; |
| 459 | cie.per_encoding = DW_EH_PE_omit; |
| 460 | aug = cie.augmentation; |
| 461 | if (aug[0] != 'e' || aug[1] != 'h') |
| 462 | { |
| 463 | if (*aug == 'z') |
| 464 | { |
| 465 | aug++; |
| 466 | read_uleb128 (cie.augmentation_size, buf); |
| 467 | ENSURE_NO_RELOCS (buf); |
| 468 | } |
| 469 | |
| 470 | while (*aug != '\0') |
| 471 | switch (*aug++) |
| 472 | { |
| 473 | case 'L': |
| 474 | cie.lsda_encoding = *buf++; |
| 475 | ENSURE_NO_RELOCS (buf); |
| 476 | if (get_DW_EH_PE_width (cie.lsda_encoding, ptr_size) == 0) |
| 477 | goto free_no_table; |
| 478 | break; |
| 479 | case 'R': |
| 480 | cie.fde_encoding = *buf++; |
| 481 | ENSURE_NO_RELOCS (buf); |
| 482 | if (get_DW_EH_PE_width (cie.fde_encoding, ptr_size) == 0) |
| 483 | goto free_no_table; |
| 484 | break; |
| 485 | case 'P': |
| 486 | { |
| 487 | int per_width; |
| 488 | |
| 489 | cie.per_encoding = *buf++; |
| 490 | per_width = get_DW_EH_PE_width (cie.per_encoding, |
| 491 | ptr_size); |
| 492 | if (per_width == 0) |
| 493 | goto free_no_table; |
| 494 | if ((cie.per_encoding & 0xf0) == DW_EH_PE_aligned) |
| 495 | buf = (ehbuf |
| 496 | + ((buf - ehbuf + per_width - 1) |
| 497 | & ~((bfd_size_type) per_width - 1))); |
| 498 | ENSURE_NO_RELOCS (buf); |
| 499 | rel = GET_RELOC (buf); |
| 500 | /* Ensure we have a reloc here, against |
| 501 | a global symbol. */ |
| 502 | if (rel != NULL) |
| 503 | { |
| 504 | unsigned long r_symndx; |
| 505 | |
| 506 | #ifdef BFD64 |
| 507 | if (ptr_size == 8) |
| 508 | r_symndx = ELF64_R_SYM (cookie->rel->r_info); |
| 509 | else |
| 510 | #endif |
| 511 | r_symndx = ELF32_R_SYM (cookie->rel->r_info); |
| 512 | if (r_symndx >= cookie->locsymcount) |
| 513 | { |
| 514 | struct elf_link_hash_entry *h; |
| 515 | |
| 516 | r_symndx -= cookie->extsymoff; |
| 517 | h = cookie->sym_hashes[r_symndx]; |
| 518 | |
| 519 | while (h->root.type == bfd_link_hash_indirect |
| 520 | || h->root.type == bfd_link_hash_warning) |
| 521 | h = (struct elf_link_hash_entry *) |
| 522 | h->root.u.i.link; |
| 523 | |
| 524 | cie.personality = h; |
| 525 | } |
| 526 | cookie->rel++; |
| 527 | } |
| 528 | buf += per_width; |
| 529 | } |
| 530 | break; |
| 531 | default: |
| 532 | /* Unrecognized augmentation. Better bail out. */ |
| 533 | goto free_no_table; |
| 534 | } |
| 535 | } |
| 536 | |
| 537 | /* For shared libraries, try to get rid of as many RELATIVE relocs |
| 538 | as possible. |
| 539 | FIXME: For this to work, ELF backends need to perform the |
| 540 | relocation if omitting dynamic relocs, not skip it. */ |
| 541 | if (0 |
| 542 | && info->shared |
| 543 | && (cie.fde_encoding & 0xf0) == DW_EH_PE_absptr) |
| 544 | cie.make_relative = 1; |
| 545 | |
| 546 | /* If FDE encoding was not specified, it defaults to |
| 547 | DW_EH_absptr. */ |
| 548 | if (cie.fde_encoding == DW_EH_PE_omit) |
| 549 | cie.fde_encoding = DW_EH_PE_absptr; |
| 550 | |
| 551 | initial_insn_length = cie.hdr.length - (buf - last_fde - 4); |
| 552 | if (initial_insn_length <= 50) |
| 553 | { |
| 554 | cie.initial_insn_length = initial_insn_length; |
| 555 | memcpy (cie.initial_instructions, buf, initial_insn_length); |
| 556 | } |
| 557 | buf += initial_insn_length; |
| 558 | ENSURE_NO_RELOCS (buf); |
| 559 | last_cie = last_fde; |
| 560 | } |
| 561 | else |
| 562 | { |
| 563 | /* Ensure this FDE uses the last CIE encountered. */ |
| 564 | if (last_cie == NULL |
| 565 | || hdr.id != (unsigned int) (buf - 4 - last_cie)) |
| 566 | goto free_no_table; |
| 567 | |
| 568 | ENSURE_NO_RELOCS (buf); |
| 569 | rel = GET_RELOC (buf); |
| 570 | if (rel == NULL) |
| 571 | /* This should not happen. */ |
| 572 | goto free_no_table; |
| 573 | if ((*reloc_symbol_deleted_p) (buf - ehbuf, cookie)) |
| 574 | { |
| 575 | cookie->rel = rel; |
| 576 | /* This is a FDE against discarded section, it should |
| 577 | be deleted. */ |
| 578 | new_size -= hdr.length + 4; |
| 579 | sec_info->entry[sec_info->count].removed = 1; |
| 580 | } |
| 581 | else |
| 582 | { |
| 583 | cie_usage_count++; |
| 584 | hdr_info->fde_count++; |
| 585 | } |
| 586 | cookie->rel = rel; |
| 587 | buf = last_fde + 4 + hdr.length; |
| 588 | SKIP_RELOCS (buf); |
| 589 | } |
| 590 | |
| 591 | sec_info->entry[sec_info->count].fde_encoding = cie.fde_encoding; |
| 592 | sec_info->count++; |
| 593 | } |
| 594 | |
| 595 | elf_section_data (sec)->sec_info = sec_info; |
| 596 | elf_section_data (sec)->sec_info_type = ELF_INFO_TYPE_EH_FRAME; |
| 597 | |
| 598 | /* Ok, now we can assign new offsets. */ |
| 599 | offset = 0; |
| 600 | last_cie_ndx = 0; |
| 601 | for (i = 0; i < sec_info->count; i++) |
| 602 | { |
| 603 | if (! sec_info->entry[i].removed) |
| 604 | { |
| 605 | sec_info->entry[i].new_offset = offset; |
| 606 | offset += sec_info->entry[i].size; |
| 607 | if (sec_info->entry[i].cie) |
| 608 | { |
| 609 | last_cie_ndx = i; |
| 610 | make_relative = sec_info->entry[i].make_relative; |
| 611 | } |
| 612 | else |
| 613 | sec_info->entry[i].make_relative = make_relative; |
| 614 | } |
| 615 | else if (sec_info->entry[i].cie && sec_info->entry[i].sec == sec) |
| 616 | { |
| 617 | /* Need to adjust new_offset too. */ |
| 618 | BFD_ASSERT (sec_info->entry[last_cie_ndx].offset |
| 619 | == sec_info->entry[i].new_offset); |
| 620 | sec_info->entry[i].new_offset |
| 621 | = sec_info->entry[last_cie_ndx].new_offset; |
| 622 | } |
| 623 | } |
| 624 | if (hdr_info->last_cie_sec == sec) |
| 625 | { |
| 626 | BFD_ASSERT (sec_info->entry[last_cie_ndx].offset |
| 627 | == hdr_info->last_cie_offset); |
| 628 | hdr_info->last_cie_offset = sec_info->entry[last_cie_ndx].new_offset; |
| 629 | } |
| 630 | |
| 631 | /* Shrink the sec as needed. */ |
| 632 | |
| 633 | sec->_cooked_size = new_size; |
| 634 | if (sec->_cooked_size == 0) |
| 635 | sec->flags |= SEC_EXCLUDE; |
| 636 | |
| 637 | free (ehbuf); |
| 638 | return new_size != sec->_raw_size; |
| 639 | |
| 640 | free_no_table: |
| 641 | if (ehbuf) |
| 642 | free (ehbuf); |
| 643 | if (sec_info) |
| 644 | free (sec_info); |
| 645 | hdr_info->table = false; |
| 646 | hdr_info->last_cie.hdr.length = 0; |
| 647 | return false; |
| 648 | } |
| 649 | |
| 650 | /* This function is called for .eh_frame_hdr section after |
| 651 | _bfd_elf_discard_section_eh_frame has been called on all .eh_frame |
| 652 | input sections. It finalizes the size of .eh_frame_hdr section. */ |
| 653 | |
| 654 | boolean |
| 655 | _bfd_elf_discard_section_eh_frame_hdr (abfd, info, sec) |
| 656 | bfd *abfd; |
| 657 | struct bfd_link_info *info; |
| 658 | asection *sec; |
| 659 | { |
| 660 | struct eh_frame_hdr_info *hdr_info; |
| 661 | unsigned int ptr_size; |
| 662 | |
| 663 | ptr_size = (elf_elfheader (abfd)->e_ident[EI_CLASS] |
| 664 | == ELFCLASS64) ? 8 : 4; |
| 665 | |
| 666 | if ((elf_section_data (sec)->sec_info_type |
| 667 | != ELF_INFO_TYPE_EH_FRAME_HDR) |
| 668 | || ! info->eh_frame_hdr) |
| 669 | { |
| 670 | _bfd_strip_section_from_output (info, sec); |
| 671 | return false; |
| 672 | } |
| 673 | |
| 674 | hdr_info = (struct eh_frame_hdr_info *) |
| 675 | elf_section_data (sec)->sec_info; |
| 676 | if (hdr_info->strip) |
| 677 | return false; |
| 678 | sec->_cooked_size = EH_FRAME_HDR_SIZE; |
| 679 | if (hdr_info->table) |
| 680 | sec->_cooked_size += 4 + hdr_info->fde_count * 8; |
| 681 | |
| 682 | /* Request program headers to be recalculated. */ |
| 683 | elf_tdata (abfd)->program_header_size = 0; |
| 684 | elf_tdata (abfd)->eh_frame_hdr = true; |
| 685 | return true; |
| 686 | } |
| 687 | |
| 688 | /* This function is called from size_dynamic_sections. |
| 689 | It needs to decide whether .eh_frame_hdr should be output or not, |
| 690 | because later on it is too late for calling _bfd_strip_section_from_output, |
| 691 | since dynamic symbol table has been sized. */ |
| 692 | |
| 693 | boolean |
| 694 | _bfd_elf_maybe_strip_eh_frame_hdr (info) |
| 695 | struct bfd_link_info *info; |
| 696 | { |
| 697 | asection *sec, *o; |
| 698 | bfd *abfd; |
| 699 | struct eh_frame_hdr_info *hdr_info; |
| 700 | |
| 701 | sec = bfd_get_section_by_name (elf_hash_table (info)->dynobj, ".eh_frame_hdr"); |
| 702 | if (sec == NULL) |
| 703 | return true; |
| 704 | |
| 705 | hdr_info |
| 706 | = bfd_zmalloc (sizeof (struct eh_frame_hdr_info)); |
| 707 | if (hdr_info == NULL) |
| 708 | return false; |
| 709 | |
| 710 | elf_section_data (sec)->sec_info = hdr_info; |
| 711 | elf_section_data (sec)->sec_info_type = ELF_INFO_TYPE_EH_FRAME_HDR; |
| 712 | |
| 713 | abfd = NULL; |
| 714 | if (info->eh_frame_hdr) |
| 715 | for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next) |
| 716 | { |
| 717 | /* Count only sections which have at least a single CIE or FDE. |
| 718 | There cannot be any CIE or FDE <= 8 bytes. */ |
| 719 | o = bfd_get_section_by_name (abfd, ".eh_frame"); |
| 720 | if (o && o->_raw_size > 8) |
| 721 | break; |
| 722 | } |
| 723 | |
| 724 | if (abfd == NULL) |
| 725 | { |
| 726 | _bfd_strip_section_from_output (info, sec); |
| 727 | hdr_info->strip = true; |
| 728 | } |
| 729 | else |
| 730 | hdr_info->table = true; |
| 731 | return true; |
| 732 | } |
| 733 | |
| 734 | /* Adjust an address in the .eh_frame section. Given OFFSET within |
| 735 | SEC, this returns the new offset in the adjusted .eh_frame section, |
| 736 | or -1 if the address refers to a CIE/FDE which has been removed |
| 737 | or to offset with dynamic relocation which is no longer needed. */ |
| 738 | |
| 739 | bfd_vma |
| 740 | _bfd_elf_eh_frame_section_offset (output_bfd, sec, offset) |
| 741 | bfd *output_bfd ATTRIBUTE_UNUSED; |
| 742 | asection *sec; |
| 743 | bfd_vma offset; |
| 744 | { |
| 745 | struct eh_frame_sec_info *sec_info; |
| 746 | unsigned int lo, hi, mid; |
| 747 | |
| 748 | if (elf_section_data (sec)->sec_info_type != ELF_INFO_TYPE_EH_FRAME) |
| 749 | return offset; |
| 750 | sec_info = (struct eh_frame_sec_info *) |
| 751 | elf_section_data (sec)->sec_info; |
| 752 | |
| 753 | if (offset >= sec->_raw_size) |
| 754 | return offset - (sec->_cooked_size - sec->_raw_size); |
| 755 | |
| 756 | lo = 0; |
| 757 | hi = sec_info->count; |
| 758 | mid = 0; |
| 759 | while (lo < hi) |
| 760 | { |
| 761 | mid = (lo + hi) / 2; |
| 762 | if (offset < sec_info->entry[mid].offset) |
| 763 | hi = mid; |
| 764 | else if (offset |
| 765 | >= sec_info->entry[mid].offset + sec_info->entry[mid].size) |
| 766 | lo = mid + 1; |
| 767 | else |
| 768 | break; |
| 769 | } |
| 770 | |
| 771 | BFD_ASSERT (lo < hi); |
| 772 | |
| 773 | /* FDE or CIE was removed. */ |
| 774 | if (sec_info->entry[mid].removed) |
| 775 | return (bfd_vma) -1; |
| 776 | |
| 777 | /* If converting to DW_EH_PE_pcrel, there will be no need for run-time |
| 778 | relocation against FDE's initial_location field. */ |
| 779 | if (sec_info->entry[mid].make_relative |
| 780 | && ! sec_info->entry[mid].cie |
| 781 | && offset == sec_info->entry[mid].offset + 8) |
| 782 | return (bfd_vma) -1; |
| 783 | |
| 784 | return (offset |
| 785 | + (sec_info->entry[mid].new_offset - sec_info->entry[mid].offset)); |
| 786 | } |
| 787 | |
| 788 | /* Write out .eh_frame section. This is called with the relocated |
| 789 | contents. */ |
| 790 | |
| 791 | boolean |
| 792 | _bfd_elf_write_section_eh_frame (abfd, sec, ehdrsec, contents) |
| 793 | bfd *abfd; |
| 794 | asection *sec, *ehdrsec; |
| 795 | bfd_byte *contents; |
| 796 | { |
| 797 | struct eh_frame_sec_info *sec_info; |
| 798 | struct eh_frame_hdr_info *hdr_info; |
| 799 | unsigned int i; |
| 800 | bfd_byte *p, *buf; |
| 801 | unsigned int leb128_tmp; |
| 802 | unsigned int cie_offset = 0; |
| 803 | unsigned int ptr_size; |
| 804 | |
| 805 | ptr_size = (elf_elfheader (sec->owner)->e_ident[EI_CLASS] |
| 806 | == ELFCLASS64) ? 8 : 4; |
| 807 | |
| 808 | if (elf_section_data (sec)->sec_info_type != ELF_INFO_TYPE_EH_FRAME) |
| 809 | return bfd_set_section_contents (abfd, sec->output_section, |
| 810 | contents, |
| 811 | (file_ptr) sec->output_offset, |
| 812 | sec->_raw_size); |
| 813 | sec_info = (struct eh_frame_sec_info *) |
| 814 | elf_section_data (sec)->sec_info; |
| 815 | hdr_info = NULL; |
| 816 | if (ehdrsec |
| 817 | && (elf_section_data (ehdrsec)->sec_info_type |
| 818 | == ELF_INFO_TYPE_EH_FRAME_HDR)) |
| 819 | { |
| 820 | hdr_info = (struct eh_frame_hdr_info *) |
| 821 | elf_section_data (ehdrsec)->sec_info; |
| 822 | if (hdr_info->table && hdr_info->array == NULL) |
| 823 | hdr_info->array |
| 824 | = bfd_malloc (hdr_info->fde_count * sizeof(*hdr_info->array)); |
| 825 | if (hdr_info->array == NULL) |
| 826 | hdr_info = NULL; |
| 827 | } |
| 828 | |
| 829 | p = contents; |
| 830 | for (i = 0; i < sec_info->count; ++i) |
| 831 | { |
| 832 | if (sec_info->entry[i].removed) |
| 833 | { |
| 834 | if (sec_info->entry[i].cie) |
| 835 | { |
| 836 | cie_offset = sec_info->entry[i].new_offset; |
| 837 | cie_offset += (sec_info->entry[i].sec->output_section->vma |
| 838 | + sec_info->entry[i].sec->output_offset |
| 839 | - sec->output_section->vma |
| 840 | - sec->output_offset); |
| 841 | } |
| 842 | continue; |
| 843 | } |
| 844 | if (sec_info->entry[i].cie) |
| 845 | { |
| 846 | /* CIE */ |
| 847 | cie_offset = sec_info->entry[i].new_offset; |
| 848 | if (sec_info->entry[i].make_relative) |
| 849 | { |
| 850 | unsigned char *aug; |
| 851 | unsigned int dummy, per_width, per_encoding; |
| 852 | |
| 853 | /* Need to find 'R' augmentation's argument and modify |
| 854 | DW_EH_PE_* value. */ |
| 855 | buf = contents + sec_info->entry[i].offset; |
| 856 | /* Skip length, id and version. */ |
| 857 | buf += 9; |
| 858 | aug = buf; |
| 859 | buf = strchr (buf, '\0') + 1; |
| 860 | read_uleb128 (dummy, buf); |
| 861 | read_sleb128 (dummy, buf); |
| 862 | read_uleb128 (dummy, buf); |
| 863 | if (*aug == 'z') |
| 864 | { |
| 865 | read_uleb128 (dummy, buf); |
| 866 | aug++; |
| 867 | } |
| 868 | |
| 869 | while (*aug != 'R') |
| 870 | switch (*aug++) |
| 871 | { |
| 872 | case 'L': |
| 873 | buf++; |
| 874 | break; |
| 875 | case 'P': |
| 876 | per_encoding = *buf++; |
| 877 | per_width = get_DW_EH_PE_width (per_encoding, |
| 878 | ptr_size); |
| 879 | BFD_ASSERT (per_width != 0); |
| 880 | if ((per_encoding & 0xf0) == DW_EH_PE_aligned) |
| 881 | buf = (contents |
| 882 | + ((buf - contents + per_width - 1) |
| 883 | & ~((bfd_size_type) per_width - 1))); |
| 884 | buf += per_width; |
| 885 | break; |
| 886 | default: |
| 887 | BFD_FAIL (); |
| 888 | } |
| 889 | |
| 890 | BFD_ASSERT (*buf == sec_info->entry[i].fde_encoding); |
| 891 | *buf |= DW_EH_PE_pcrel; |
| 892 | } |
| 893 | } |
| 894 | else |
| 895 | { |
| 896 | /* FDE */ |
| 897 | bfd_vma value = 0, address; |
| 898 | unsigned int fde_width; |
| 899 | |
| 900 | buf = contents + sec_info->entry[i].offset; |
| 901 | /* Skip length. */ |
| 902 | buf += 4; |
| 903 | bfd_put_32 (abfd, |
| 904 | sec_info->entry[i].new_offset + 4 - cie_offset, buf); |
| 905 | buf += 4; |
| 906 | fde_width = get_DW_EH_PE_width (sec_info->entry[i].fde_encoding, |
| 907 | ptr_size); |
| 908 | switch (fde_width) |
| 909 | { |
| 910 | case 2: value = bfd_get_16 (abfd, buf); break; |
| 911 | case 4: value = bfd_get_32 (abfd, buf); break; |
| 912 | case 8: value = bfd_get_64 (abfd, buf); break; |
| 913 | default: BFD_FAIL (); |
| 914 | } |
| 915 | address = value; |
| 916 | switch (sec_info->entry[i].fde_encoding & 0xf0) |
| 917 | { |
| 918 | case DW_EH_PE_indirect: |
| 919 | case DW_EH_PE_textrel: |
| 920 | BFD_ASSERT (hdr_info == NULL); |
| 921 | break; |
| 922 | case DW_EH_PE_datarel: |
| 923 | { |
| 924 | asection *got = bfd_get_section_by_name (abfd, ".got"); |
| 925 | |
| 926 | BFD_ASSERT (got != NULL); |
| 927 | address += got->vma; |
| 928 | } |
| 929 | break; |
| 930 | case DW_EH_PE_pcrel: |
| 931 | value += (sec_info->entry[i].offset |
| 932 | - sec_info->entry[i].new_offset); |
| 933 | address += (sec->output_section->vma + sec->output_offset |
| 934 | + sec_info->entry[i].new_offset + 8); |
| 935 | break; |
| 936 | } |
| 937 | if (sec_info->entry[i].make_relative) |
| 938 | value -= (sec->output_section->vma + sec->output_offset |
| 939 | + sec_info->entry[i].new_offset + 8); |
| 940 | switch (fde_width) |
| 941 | { |
| 942 | case 2: bfd_put_16 (abfd, value, buf); break; |
| 943 | case 4: bfd_put_32 (abfd, value, buf); break; |
| 944 | case 8: bfd_put_64 (abfd, value, buf); break; |
| 945 | } |
| 946 | |
| 947 | if (hdr_info) |
| 948 | { |
| 949 | hdr_info->array[hdr_info->array_count].initial_loc = address; |
| 950 | hdr_info->array[hdr_info->array_count++].fde |
| 951 | = (sec->output_section->vma + sec->output_offset |
| 952 | + sec_info->entry[i].new_offset); |
| 953 | } |
| 954 | } |
| 955 | |
| 956 | BFD_ASSERT (p == contents + sec_info->entry[i].new_offset); |
| 957 | memmove (p, contents + sec_info->entry[i].offset, |
| 958 | sec_info->entry[i].size); |
| 959 | p += sec_info->entry[i].size; |
| 960 | } |
| 961 | |
| 962 | BFD_ASSERT ((bfd_size_type) (p - contents) == sec->_cooked_size); |
| 963 | |
| 964 | return bfd_set_section_contents (abfd, sec->output_section, |
| 965 | contents, (file_ptr) sec->output_offset, |
| 966 | sec->_cooked_size); |
| 967 | } |
| 968 | |
| 969 | /* Helper function used to sort .eh_frame_hdr search table by increasing |
| 970 | VMA of FDE initial location. */ |
| 971 | |
| 972 | static int |
| 973 | vma_compare (a, b) |
| 974 | const PTR a; |
| 975 | const PTR b; |
| 976 | { |
| 977 | struct eh_frame_array_ent *p = (struct eh_frame_array_ent *) a; |
| 978 | struct eh_frame_array_ent *q = (struct eh_frame_array_ent *) b; |
| 979 | if (p->initial_loc > q->initial_loc) |
| 980 | return 1; |
| 981 | if (p->initial_loc < q->initial_loc) |
| 982 | return -1; |
| 983 | return 0; |
| 984 | } |
| 985 | |
| 986 | /* Write out .eh_frame_hdr section. This must be called after |
| 987 | _bfd_elf_write_section_eh_frame has been called on all input |
| 988 | .eh_frame sections. |
| 989 | .eh_frame_hdr format: |
| 990 | ubyte version (currently 1) |
| 991 | ubyte eh_frame_ptr_enc (DW_EH_PE_* encoding of pointer to start of |
| 992 | .eh_frame section) |
| 993 | ubyte fde_count_enc (DW_EH_PE_* encoding of total FDE count |
| 994 | number (or DW_EH_PE_omit if there is no |
| 995 | binary search table computed)) |
| 996 | ubyte table_enc (DW_EH_PE_* encoding of binary search table, |
| 997 | or DW_EH_PE_omit if not present. |
| 998 | DW_EH_PE_datarel is using address of |
| 999 | .eh_frame_hdr section start as base) |
| 1000 | [encoded] eh_frame_ptr (pointer to start of .eh_frame section) |
| 1001 | optionally followed by: |
| 1002 | [encoded] fde_count (total number of FDEs in .eh_frame section) |
| 1003 | fde_count x [encoded] initial_loc, fde |
| 1004 | (array of encoded pairs containing |
| 1005 | FDE initial_location field and FDE address, |
| 1006 | sorted by increasing initial_loc) */ |
| 1007 | |
| 1008 | boolean |
| 1009 | _bfd_elf_write_section_eh_frame_hdr (abfd, sec) |
| 1010 | bfd *abfd; |
| 1011 | asection *sec; |
| 1012 | { |
| 1013 | struct eh_frame_hdr_info *hdr_info; |
| 1014 | unsigned int ptr_size; |
| 1015 | bfd_byte *contents; |
| 1016 | asection *eh_frame_sec; |
| 1017 | bfd_size_type size; |
| 1018 | |
| 1019 | ptr_size = (elf_elfheader (sec->owner)->e_ident[EI_CLASS] |
| 1020 | == ELFCLASS64) ? 8 : 4; |
| 1021 | |
| 1022 | BFD_ASSERT (elf_section_data (sec)->sec_info_type |
| 1023 | == ELF_INFO_TYPE_EH_FRAME_HDR); |
| 1024 | hdr_info = (struct eh_frame_hdr_info *) |
| 1025 | elf_section_data (sec)->sec_info; |
| 1026 | size = EH_FRAME_HDR_SIZE; |
| 1027 | if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count) |
| 1028 | size += 4 + hdr_info->fde_count * 8; |
| 1029 | contents = bfd_malloc (size); |
| 1030 | if (contents == NULL) |
| 1031 | return false; |
| 1032 | |
| 1033 | eh_frame_sec = bfd_get_section_by_name (abfd, ".eh_frame"); |
| 1034 | if (eh_frame_sec == NULL) |
| 1035 | return false; |
| 1036 | |
| 1037 | memset (contents, 0, EH_FRAME_HDR_SIZE); |
| 1038 | contents[0] = 1; /* Version */ |
| 1039 | contents[1] = DW_EH_PE_pcrel | DW_EH_PE_sdata4; /* .eh_frame offset */ |
| 1040 | if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count) |
| 1041 | { |
| 1042 | contents[2] = DW_EH_PE_udata4; /* FDE count encoding */ |
| 1043 | contents[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4; /* search table enc */ |
| 1044 | } |
| 1045 | else |
| 1046 | { |
| 1047 | contents[2] = DW_EH_PE_omit; |
| 1048 | contents[3] = DW_EH_PE_omit; |
| 1049 | } |
| 1050 | bfd_put_32 (abfd, eh_frame_sec->vma - sec->output_section->vma - 4, |
| 1051 | contents + 4); |
| 1052 | if (contents[2] != DW_EH_PE_omit) |
| 1053 | { |
| 1054 | unsigned int i; |
| 1055 | |
| 1056 | bfd_put_32 (abfd, hdr_info->fde_count, contents + EH_FRAME_HDR_SIZE); |
| 1057 | qsort (hdr_info->array, hdr_info->fde_count, sizeof (*hdr_info->array), |
| 1058 | vma_compare); |
| 1059 | for (i = 0; i < hdr_info->fde_count; i++) |
| 1060 | { |
| 1061 | bfd_put_32 (abfd, |
| 1062 | hdr_info->array[i].initial_loc |
| 1063 | - sec->output_section->vma, |
| 1064 | contents + EH_FRAME_HDR_SIZE + i * 8 + 4); |
| 1065 | bfd_put_32 (abfd, |
| 1066 | hdr_info->array[i].fde - sec->output_section->vma, |
| 1067 | contents + EH_FRAME_HDR_SIZE + i * 8 + 8); |
| 1068 | } |
| 1069 | } |
| 1070 | |
| 1071 | return bfd_set_section_contents (abfd, sec->output_section, |
| 1072 | contents, (file_ptr) sec->output_offset, |
| 1073 | sec->_cooked_size); |
| 1074 | } |