tools/objtool/check.c

   1 /*
   2  * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <string.h>
  19 #include <stdlib.h>
  20
  21 #include "builtin.h"
  22 #include "check.h"
  23 #include "elf.h"
  24 #include "special.h"
  25 #include "arch.h"
  26 #include "warn.h"
  27
  28 #include <linux/hashtable.h>
  29 #include <linux/kernel.h>
  30
  31 struct alternative {
  32         struct list_head list;
  33         struct instruction *insn;
  34 };
  35
  36 const char *objname;
  37 struct cfi_state initial_func_cfi;
  38
  39 struct instruction *find_insn(struct objtool_file *file,
  40                               struct section *sec, unsigned long offset)
  41 {
  42         struct instruction *insn;
  43
  44         hash_for_each_possible(file->insn_hash, insn, hash, offset)
  45                 if (insn->sec == sec && insn->offset == offset)
  46                         return insn;
  47
  48         return NULL;
  49 }
  50
  51 static struct instruction *next_insn_same_sec(struct objtool_file *file,
  52                                               struct instruction *insn)
  53 {
  54         struct instruction *next = list_next_entry(insn, list);
  55
  56         if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
  57                 return NULL;
  58
  59         return next;
  60 }
  61
  62 static struct instruction *next_insn_same_func(struct objtool_file *file,
  63                                                struct instruction *insn)
  64 {
  65         struct instruction *next = list_next_entry(insn, list);
  66         struct symbol *func = insn->func;
  67
  68         if (!func)
  69                 return NULL;
  70
  71         if (&next->list != &file->insn_list && next->func == func)
  72                 return next;
  73
  74         /* Check if we're already in the subfunction: */
  75         if (func == func->cfunc)
  76                 return NULL;
  77
  78         /* Move to the subfunction: */
  79         return find_insn(file, func->cfunc->sec, func->cfunc->offset);
  80 }
  81
  82 #define func_for_each_insn_all(file, func, insn)                        \
  83         for (insn = find_insn(file, func->sec, func->offset);           \
  84              insn;                                                      \
  85              insn = next_insn_same_func(file, insn))
  86
  87 #define func_for_each_insn(file, func, insn)                            \
  88         for (insn = find_insn(file, func->sec, func->offset);           \
  89              insn && &insn->list != &file->insn_list &&                 \
  90                 insn->sec == func->sec &&                               \
  91                 insn->offset < func->offset + func->len;                \
  92              insn = list_next_entry(insn, list))
  93
  94 #define func_for_each_insn_continue_reverse(file, func, insn)           \
  95         for (insn = list_prev_entry(insn, list);                        \
  96              &insn->list != &file->insn_list &&                         \
  97                 insn->sec == func->sec && insn->offset >= func->offset; \
  98              insn = list_prev_entry(insn, list))
  99
 100 #define sec_for_each_insn_from(file, insn)                              \
 101         for (; insn; insn = next_insn_same_sec(file, insn))
 102
 103 #define sec_for_each_insn_continue(file, insn)                          \
 104         for (insn = next_insn_same_sec(file, insn); insn;               \
 105              insn = next_insn_same_sec(file, insn))
 106
 107 /*
 108  * Check if the function has been manually whitelisted with the
 109  * STACK_FRAME_NON_STANDARD macro, or if it should be automatically whitelisted
 110  * due to its use of a context switching instruction.
 111  */
 112 static bool ignore_func(struct objtool_file *file, struct symbol *func)
 113 {
 114         struct rela *rela;
 115
 116         /* check for STACK_FRAME_NON_STANDARD */
 117         if (file->whitelist && file->whitelist->rela)
 118                 list_for_each_entry(rela, &file->whitelist->rela->rela_list, list) {
 119                         if (rela->sym->type == STT_SECTION &&
 120                             rela->sym->sec == func->sec &&
 121                             rela->addend == func->offset)
 122                                 return true;
 123                         if (rela->sym->type == STT_FUNC && rela->sym == func)
 124                                 return true;
 125                 }
 126
 127         return false;
 128 }
 129
 130 /*
 131  * This checks to see if the given function is a "noreturn" function.
 132  *
 133  * For global functions which are outside the scope of this object file, we
 134  * have to keep a manual list of them.
 135  *
 136  * For local functions, we have to detect them manually by simply looking for
 137  * the lack of a return instruction.
 138  *
 139  * Returns:
 140  *  -1: error
 141  *   0: no dead end
 142  *   1: dead end
 143  */
 144 static int __dead_end_function(struct objtool_file *file, struct symbol *func,
 145                                int recursion)
 146 {
 147         int i;
 148         struct instruction *insn;
 149         bool empty = true;
 150
 151         /*
 152          * Unfortunately these have to be hard coded because the noreturn
 153          * attribute isn't provided in ELF data.
 154          */
 155         static const char * const global_noreturns[] = {
 156                 "__stack_chk_fail",
 157                 "panic",
 158                 "do_exit",
 159                 "do_task_dead",
 160                 "__module_put_and_exit",
 161                 "complete_and_exit",
 162                 "kvm_spurious_fault",
 163                 "__reiserfs_panic",
 164                 "lbug_with_loc",
 165                 "fortify_panic",
 166         };
 167
 168         if (func->bind == STB_WEAK)
 169                 return 0;
 170
 171         if (func->bind == STB_GLOBAL)
 172                 for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
 173                         if (!strcmp(func->name, global_noreturns[i]))
 174                                 return 1;
 175
 176         if (!func->len)
 177                 return 0;
 178
 179         insn = find_insn(file, func->sec, func->offset);
 180         if (!insn->func)
 181                 return 0;
 182
 183         func_for_each_insn_all(file, func, insn) {
 184                 empty = false;
 185
 186                 if (insn->type == INSN_RETURN)
 187                         return 0;
 188         }
 189
 190         if (empty)
 191                 return 0;
 192
 193         /*
 194          * A function can have a sibling call instead of a return.  In that
 195          * case, the function's dead-end status depends on whether the target
 196          * of the sibling call returns.
 197          */
 198         func_for_each_insn_all(file, func, insn) {
 199                 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
 200                         struct instruction *dest = insn->jump_dest;
 201
 202                         if (!dest)
 203                                 /* sibling call to another file */
 204                                 return 0;
 205
 206                         if (dest->func && dest->func->pfunc != insn->func->pfunc) {
 207
 208                                 /* local sibling call */
 209                                 if (recursion == 5) {
 210                                         WARN_FUNC("infinite recursion (objtool bug!)",
 211                                                   dest->sec, dest->offset);
 212                                         return -1;
 213                                 }
 214
 215                                 return __dead_end_function(file, dest->func,
 216                                                            recursion + 1);
 217                         }
 218                 }
 219
 220                 if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts))
 221                         /* sibling call */
 222                         return 0;
 223         }
 224
 225         return 1;
 226 }
 227
 228 static int dead_end_function(struct objtool_file *file, struct symbol *func)
 229 {
 230         return __dead_end_function(file, func, 0);
 231 }
 232
 233 static void clear_insn_state(struct insn_state *state)
 234 {
 235         int i;
 236
 237         memset(state, 0, sizeof(*state));
 238         state->cfa.base = CFI_UNDEFINED;
 239         for (i = 0; i < CFI_NUM_REGS; i++) {
 240                 state->regs[i].base = CFI_UNDEFINED;
 241                 state->vals[i].base = CFI_UNDEFINED;
 242         }
 243         state->drap_reg = CFI_UNDEFINED;
 244         state->drap_offset = -1;
 245 }
 246
 247 /*
 248  * Call the arch-specific instruction decoder for all the instructions and add
 249  * them to the global instruction list.
 250  */
 251 static int decode_instructions(struct objtool_file *file)
 252 {
 253         struct section *sec;
 254         struct symbol *func;
 255         unsigned long offset;
 256         struct instruction *insn;
 257         int ret;
 258
 259         for_each_sec(file, sec) {
 260
 261                 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
 262                         continue;
 263
 264                 if (strcmp(sec->name, ".altinstr_replacement") &&
 265                     strcmp(sec->name, ".altinstr_aux") &&
 266                     strncmp(sec->name, ".discard.", 9))
 267                         sec->text = true;
 268
 269                 for (offset = 0; offset < sec->len; offset += insn->len) {
 270                         insn = malloc(sizeof(*insn));
 271                         if (!insn) {
 272                                 WARN("malloc failed");
 273                                 return -1;
 274                         }
 275                         memset(insn, 0, sizeof(*insn));
 276                         INIT_LIST_HEAD(&insn->alts);
 277                         clear_insn_state(&insn->state);
 278
 279                         insn->sec = sec;
 280                         insn->offset = offset;
 281
 282                         ret = arch_decode_instruction(file->elf, sec, offset,
 283                                                       sec->len - offset,
 284                                                       &insn->len, &insn->type,
 285                                                       &insn->immediate,
 286                                                       &insn->stack_op);
 287                         if (ret)
 288                                 goto err;
 289
 290                         if (!insn->type || insn->type > INSN_LAST) {
 291                                 WARN_FUNC("invalid instruction type %d",
 292                                           insn->sec, insn->offset, insn->type);
 293                                 ret = -1;
 294                                 goto err;
 295                         }
 296
 297                         hash_add(file->insn_hash, &insn->hash, insn->offset);
 298                         list_add_tail(&insn->list, &file->insn_list);
 299                 }
 300
 301                 list_for_each_entry(func, &sec->symbol_list, list) {
 302                         if (func->type != STT_FUNC)
 303                                 continue;
 304
 305                         if (!find_insn(file, sec, func->offset)) {
 306                                 WARN("%s(): can't find starting instruction",
 307                                      func->name);
 308                                 return -1;
 309                         }
 310
 311                         func_for_each_insn(file, func, insn)
 312                                 if (!insn->func)
 313                                         insn->func = func;
 314                 }
 315         }
 316
 317         return 0;
 318
 319 err:
 320         free(insn);
 321         return ret;
 322 }
 323
 324 /*
 325  * Mark "ud2" instructions and manually annotated dead ends.
 326  */
 327 static int add_dead_ends(struct objtool_file *file)
 328 {
 329         struct section *sec;
 330         struct rela *rela;
 331         struct instruction *insn;
 332         bool found;
 333
 334         /*
 335          * By default, "ud2" is a dead end unless otherwise annotated, because
 336          * GCC 7 inserts it for certain divide-by-zero cases.
 337          */
 338         for_each_insn(file, insn)
 339                 if (insn->type == INSN_BUG)
 340                         insn->dead_end = true;
 341
 342         /*
 343          * Check for manually annotated dead ends.
 344          */
 345         sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
 346         if (!sec)
 347                 goto reachable;
 348
 349         list_for_each_entry(rela, &sec->rela_list, list) {
 350                 if (rela->sym->type != STT_SECTION) {
 351                         WARN("unexpected relocation symbol type in %s", sec->name);
 352                         return -1;
 353                 }
 354                 insn = find_insn(file, rela->sym->sec, rela->addend);
 355                 if (insn)
 356                         insn = list_prev_entry(insn, list);
 357                 else if (rela->addend == rela->sym->sec->len) {
 358                         found = false;
 359                         list_for_each_entry_reverse(insn, &file->insn_list, list) {
 360                                 if (insn->sec == rela->sym->sec) {
 361                                         found = true;
 362                                         break;
 363                                 }
 364                         }
 365
 366                         if (!found) {
 367                                 WARN("can't find unreachable insn at %s+0x%x",
 368                                      rela->sym->sec->name, rela->addend);
 369                                 return -1;
 370                         }
 371                 } else {
 372                         WARN("can't find unreachable insn at %s+0x%x",
 373                              rela->sym->sec->name, rela->addend);
 374                         return -1;
 375                 }
 376
 377                 insn->dead_end = true;
 378         }
 379
 380 reachable:
 381         /*
 382          * These manually annotated reachable checks are needed for GCC 4.4,
 383          * where the Linux unreachable() macro isn't supported.  In that case
 384          * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
 385          * not a dead end.
 386          */
 387         sec = find_section_by_name(file->elf, ".rela.discard.reachable");
 388         if (!sec)
 389                 return 0;
 390
 391         list_for_each_entry(rela, &sec->rela_list, list) {
 392                 if (rela->sym->type != STT_SECTION) {
 393                         WARN("unexpected relocation symbol type in %s", sec->name);
 394                         return -1;
 395                 }
 396                 insn = find_insn(file, rela->sym->sec, rela->addend);
 397                 if (insn)
 398                         insn = list_prev_entry(insn, list);
 399                 else if (rela->addend == rela->sym->sec->len) {
 400                         found = false;
 401                         list_for_each_entry_reverse(insn, &file->insn_list, list) {
 402                                 if (insn->sec == rela->sym->sec) {
 403                                         found = true;
 404                                         break;
 405                                 }
 406                         }
 407
 408                         if (!found) {
 409                                 WARN("can't find reachable insn at %s+0x%x",
 410                                      rela->sym->sec->name, rela->addend);
 411                                 return -1;
 412                         }
 413                 } else {
 414                         WARN("can't find reachable insn at %s+0x%x",
 415                              rela->sym->sec->name, rela->addend);
 416                         return -1;
 417                 }
 418
 419                 insn->dead_end = false;
 420         }
 421
 422         return 0;
 423 }
 424
 425 /*
 426  * Warnings shouldn't be reported for ignored functions.
 427  */
 428 static void add_ignores(struct objtool_file *file)
 429 {
 430         struct instruction *insn;
 431         struct section *sec;
 432         struct symbol *func;
 433
 434         for_each_sec(file, sec) {
 435                 list_for_each_entry(func, &sec->symbol_list, list) {
 436                         if (func->type != STT_FUNC)
 437                                 continue;
 438
 439                         if (!ignore_func(file, func))
 440                                 continue;
 441
 442                         func_for_each_insn_all(file, func, insn)
 443                                 insn->ignore = true;
 444                 }
 445         }
 446 }
 447
 448 /*
 449  * FIXME: For now, just ignore any alternatives which add retpolines.  This is
 450  * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
 451  * But it at least allows objtool to understand the control flow *around* the
 452  * retpoline.
 453  */
 454 static int add_nospec_ignores(struct objtool_file *file)
 455 {
 456         struct section *sec;
 457         struct rela *rela;
 458         struct instruction *insn;
 459
 460         sec = find_section_by_name(file->elf, ".rela.discard.nospec");
 461         if (!sec)
 462                 return 0;
 463
 464         list_for_each_entry(rela, &sec->rela_list, list) {
 465                 if (rela->sym->type != STT_SECTION) {
 466                         WARN("unexpected relocation symbol type in %s", sec->name);
 467                         return -1;
 468                 }
 469
 470                 insn = find_insn(file, rela->sym->sec, rela->addend);
 471                 if (!insn) {
 472                         WARN("bad .discard.nospec entry");
 473                         return -1;
 474                 }
 475
 476                 insn->ignore_alts = true;
 477         }
 478
 479         return 0;
 480 }
 481
 482 /*
 483  * Find the destination instructions for all jumps.
 484  */
 485 static int add_jump_destinations(struct objtool_file *file)
 486 {
 487         struct instruction *insn;
 488         struct rela *rela;
 489         struct section *dest_sec;
 490         unsigned long dest_off;
 491
 492         for_each_insn(file, insn) {
 493                 if (insn->type != INSN_JUMP_CONDITIONAL &&
 494                     insn->type != INSN_JUMP_UNCONDITIONAL)
 495                         continue;
 496
 497                 if (insn->ignore)
 498                         continue;
 499
 500                 rela = find_rela_by_dest_range(insn->sec, insn->offset,
 501                                                insn->len);
 502                 if (!rela) {
 503                         dest_sec = insn->sec;
 504                         dest_off = insn->offset + insn->len + insn->immediate;
 505                 } else if (rela->sym->type == STT_SECTION) {
 506                         dest_sec = rela->sym->sec;
 507                         dest_off = rela->addend + 4;
 508                 } else if (rela->sym->sec->idx) {
 509                         dest_sec = rela->sym->sec;
 510                         dest_off = rela->sym->sym.st_value + rela->addend + 4;
 511                 } else if (strstr(rela->sym->name, "_indirect_thunk_")) {
 512                         /*
 513                          * Retpoline jumps are really dynamic jumps in
 514                          * disguise, so convert them accordingly.
 515                          */
 516                         insn->type = INSN_JUMP_DYNAMIC;
 517                         insn->retpoline_safe = true;
 518                         continue;
 519                 } else {
 520                         /* sibling call */
 521                         insn->jump_dest = 0;
 522                         continue;
 523                 }
 524
 525                 insn->jump_dest = find_insn(file, dest_sec, dest_off);
 526                 if (!insn->jump_dest) {
 527
 528                         /*
 529                          * This is a special case where an alt instruction
 530                          * jumps past the end of the section.  These are
 531                          * handled later in handle_group_alt().
 532                          */
 533                         if (!strcmp(insn->sec->name, ".altinstr_replacement"))
 534                                 continue;
 535
 536                         WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
 537                                   insn->sec, insn->offset, dest_sec->name,
 538                                   dest_off);
 539                         return -1;
 540                 }
 541         }
 542
 543         return 0;
 544 }
 545
 546 /*
 547  * Find the destination instructions for all calls.
 548  */
 549 static int add_call_destinations(struct objtool_file *file)
 550 {
 551         struct instruction *insn;
 552         unsigned long dest_off;
 553         struct rela *rela;
 554
 555         for_each_insn(file, insn) {
 556                 if (insn->type != INSN_CALL)
 557                         continue;
 558
 559                 rela = find_rela_by_dest_range(insn->sec, insn->offset,
 560                                                insn->len);
 561                 if (!rela) {
 562                         dest_off = insn->offset + insn->len + insn->immediate;
 563                         insn->call_dest = find_symbol_by_offset(insn->sec,
 564                                                                 dest_off);
 565
 566                         if (!insn->call_dest && !insn->ignore) {
 567                                 WARN_FUNC("unsupported intra-function call",
 568                                           insn->sec, insn->offset);
 569                                 if (retpoline)
 570                                         WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE.");
 571                                 return -1;
 572                         }
 573
 574                 } else if (rela->sym->type == STT_SECTION) {
 575                         insn->call_dest = find_symbol_by_offset(rela->sym->sec,
 576                                                                 rela->addend+4);
 577                         if (!insn->call_dest ||
 578                             insn->call_dest->type != STT_FUNC) {
 579                                 WARN_FUNC("can't find call dest symbol at %s+0x%x",
 580                                           insn->sec, insn->offset,
 581                                           rela->sym->sec->name,
 582                                           rela->addend + 4);
 583                                 return -1;
 584                         }
 585                 } else
 586                         insn->call_dest = rela->sym;
 587         }
 588
 589         return 0;
 590 }
 591
 592 /*
 593  * The .alternatives section requires some extra special care, over and above
 594  * what other special sections require:
 595  *
 596  * 1. Because alternatives are patched in-place, we need to insert a fake jump
 597  *    instruction at the end so that validate_branch() skips all the original
 598  *    replaced instructions when validating the new instruction path.
 599  *
 600  * 2. An added wrinkle is that the new instruction length might be zero.  In
 601  *    that case the old instructions are replaced with noops.  We simulate that
 602  *    by creating a fake jump as the only new instruction.
 603  *
 604  * 3. In some cases, the alternative section includes an instruction which
 605  *    conditionally jumps to the _end_ of the entry.  We have to modify these
 606  *    jumps' destinations to point back to .text rather than the end of the
 607  *    entry in .altinstr_replacement.
 608  *
 609  * 4. It has been requested that we don't validate the !POPCNT feature path
 610  *    which is a "very very small percentage of machines".
 611  */
 612 static int handle_group_alt(struct objtool_file *file,
 613                             struct special_alt *special_alt,
 614                             struct instruction *orig_insn,
 615                             struct instruction **new_insn)
 616 {
 617         struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL;
 618         unsigned long dest_off;
 619
 620         last_orig_insn = NULL;
 621         insn = orig_insn;
 622         sec_for_each_insn_from(file, insn) {
 623                 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
 624                         break;
 625
 626                 if (special_alt->skip_orig)
 627                         insn->type = INSN_NOP;
 628
 629                 insn->alt_group = true;
 630                 last_orig_insn = insn;
 631         }
 632
 633         if (next_insn_same_sec(file, last_orig_insn)) {
 634                 fake_jump = malloc(sizeof(*fake_jump));
 635                 if (!fake_jump) {
 636                         WARN("malloc failed");
 637                         return -1;
 638                 }
 639                 memset(fake_jump, 0, sizeof(*fake_jump));
 640                 INIT_LIST_HEAD(&fake_jump->alts);
 641                 clear_insn_state(&fake_jump->state);
 642
 643                 fake_jump->sec = special_alt->new_sec;
 644                 fake_jump->offset = -1;
 645                 fake_jump->type = INSN_JUMP_UNCONDITIONAL;
 646                 fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
 647                 fake_jump->ignore = true;
 648         }
 649
 650         if (!special_alt->new_len) {
 651                 if (!fake_jump) {
 652                         WARN("%s: empty alternative at end of section",
 653                              special_alt->orig_sec->name);
 654                         return -1;
 655                 }
 656
 657                 *new_insn = fake_jump;
 658                 return 0;
 659         }
 660
 661         last_new_insn = NULL;
 662         insn = *new_insn;
 663         sec_for_each_insn_from(file, insn) {
 664                 if (insn->offset >= special_alt->new_off + special_alt->new_len)
 665                         break;
 666
 667                 last_new_insn = insn;
 668
 669                 insn->ignore = orig_insn->ignore_alts;
 670
 671                 if (insn->type != INSN_JUMP_CONDITIONAL &&
 672                     insn->type != INSN_JUMP_UNCONDITIONAL)
 673                         continue;
 674
 675                 if (!insn->immediate)
 676                         continue;
 677
 678                 dest_off = insn->offset + insn->len + insn->immediate;
 679                 if (dest_off == special_alt->new_off + special_alt->new_len) {
 680                         if (!fake_jump) {
 681                                 WARN("%s: alternative jump to end of section",
 682                                      special_alt->orig_sec->name);
 683                                 return -1;
 684                         }
 685                         insn->jump_dest = fake_jump;
 686                 }
 687
 688                 if (!insn->jump_dest) {
 689                         WARN_FUNC("can't find alternative jump destination",
 690                                   insn->sec, insn->offset);
 691                         return -1;
 692                 }
 693         }
 694
 695         if (!last_new_insn) {
 696                 WARN_FUNC("can't find last new alternative instruction",
 697                           special_alt->new_sec, special_alt->new_off);
 698                 return -1;
 699         }
 700
 701         if (fake_jump)
 702                 list_add(&fake_jump->list, &last_new_insn->list);
 703
 704         return 0;
 705 }
 706
 707 /*
 708  * A jump table entry can either convert a nop to a jump or a jump to a nop.
 709  * If the original instruction is a jump, make the alt entry an effective nop
 710  * by just skipping the original instruction.
 711  */
 712 static int handle_jump_alt(struct objtool_file *file,
 713                            struct special_alt *special_alt,
 714                            struct instruction *orig_insn,
 715                            struct instruction **new_insn)
 716 {
 717         if (orig_insn->type == INSN_NOP)
 718                 return 0;
 719
 720         if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) {
 721                 WARN_FUNC("unsupported instruction at jump label",
 722                           orig_insn->sec, orig_insn->offset);
 723                 return -1;
 724         }
 725
 726         *new_insn = list_next_entry(orig_insn, list);
 727         return 0;
 728 }
 729
 730 /*
 731  * Read all the special sections which have alternate instructions which can be
 732  * patched in or redirected to at runtime.  Each instruction having alternate
 733  * instruction(s) has them added to its insn->alts list, which will be
 734  * traversed in validate_branch().
 735  */
 736 static int add_special_section_alts(struct objtool_file *file)
 737 {
 738         struct list_head special_alts;
 739         struct instruction *orig_insn, *new_insn;
 740         struct special_alt *special_alt, *tmp;
 741         struct alternative *alt;
 742         int ret;
 743
 744         ret = special_get_alts(file->elf, &special_alts);
 745         if (ret)
 746                 return ret;
 747
 748         list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
 749
 750                 orig_insn = find_insn(file, special_alt->orig_sec,
 751                                       special_alt->orig_off);
 752                 if (!orig_insn) {
 753                         WARN_FUNC("special: can't find orig instruction",
 754                                   special_alt->orig_sec, special_alt->orig_off);
 755                         ret = -1;
 756                         goto out;
 757                 }
 758
 759                 new_insn = NULL;
 760                 if (!special_alt->group || special_alt->new_len) {
 761                         new_insn = find_insn(file, special_alt->new_sec,
 762                                              special_alt->new_off);
 763                         if (!new_insn) {
 764                                 WARN_FUNC("special: can't find new instruction",
 765                                           special_alt->new_sec,
 766                                           special_alt->new_off);
 767                                 ret = -1;
 768                                 goto out;
 769                         }
 770                 }
 771
 772                 if (special_alt->group) {
 773                         ret = handle_group_alt(file, special_alt, orig_insn,
 774                                                &new_insn);
 775                         if (ret)
 776                                 goto out;
 777                 } else if (special_alt->jump_or_nop) {
 778                         ret = handle_jump_alt(file, special_alt, orig_insn,
 779                                               &new_insn);
 780                         if (ret)
 781                                 goto out;
 782                 }
 783
 784                 alt = malloc(sizeof(*alt));
 785                 if (!alt) {
 786                         WARN("malloc failed");
 787                         ret = -1;
 788                         goto out;
 789                 }
 790
 791                 alt->insn = new_insn;
 792                 list_add_tail(&alt->list, &orig_insn->alts);
 793
 794                 list_del(&special_alt->list);
 795                 free(special_alt);
 796         }
 797
 798 out:
 799         return ret;
 800 }
 801
 802 static int add_switch_table(struct objtool_file *file, struct instruction *insn,
 803                             struct rela *table, struct rela *next_table)
 804 {
 805         struct rela *rela = table;
 806         struct instruction *alt_insn;
 807         struct alternative *alt;
 808         struct symbol *pfunc = insn->func->pfunc;
 809         unsigned int prev_offset = 0;
 810
 811         list_for_each_entry_from(rela, &file->rodata->rela->rela_list, list) {
 812                 if (rela == next_table)
 813                         break;
 814
 815                 /* Make sure the switch table entries are consecutive: */
 816                 if (prev_offset && rela->offset != prev_offset + 8)
 817                         break;
 818
 819                 /* Detect function pointers from contiguous objects: */
 820                 if (rela->sym->sec == pfunc->sec &&
 821                     rela->addend == pfunc->offset)
 822                         break;
 823
 824                 alt_insn = find_insn(file, rela->sym->sec, rela->addend);
 825                 if (!alt_insn)
 826                         break;
 827
 828                 /* Make sure the jmp dest is in the function or subfunction: */
 829                 if (alt_insn->func->pfunc != pfunc)
 830                         break;
 831
 832                 alt = malloc(sizeof(*alt));
 833                 if (!alt) {
 834                         WARN("malloc failed");
 835                         return -1;
 836                 }
 837
 838                 alt->insn = alt_insn;
 839                 list_add_tail(&alt->list, &insn->alts);
 840                 prev_offset = rela->offset;
 841         }
 842
 843         if (!prev_offset) {
 844                 WARN_FUNC("can't find switch jump table",
 845                           insn->sec, insn->offset);
 846                 return -1;
 847         }
 848
 849         return 0;
 850 }
 851
 852 /*
 853  * find_switch_table() - Given a dynamic jump, find the switch jump table in
 854  * .rodata associated with it.
 855  *
 856  * There are 3 basic patterns:
 857  *
 858  * 1. jmpq *[rodata addr](,%reg,8)
 859  *
 860  *    This is the most common case by far.  It jumps to an address in a simple
 861  *    jump table which is stored in .rodata.
 862  *
 863  * 2. jmpq *[rodata addr](%rip)
 864  *
 865  *    This is caused by a rare GCC quirk, currently only seen in three driver
 866  *    functions in the kernel, only with certain obscure non-distro configs.
 867  *
 868  *    As part of an optimization, GCC makes a copy of an existing switch jump
 869  *    table, modifies it, and then hard-codes the jump (albeit with an indirect
 870  *    jump) to use a single entry in the table.  The rest of the jump table and
 871  *    some of its jump targets remain as dead code.
 872  *
 873  *    In such a case we can just crudely ignore all unreachable instruction
 874  *    warnings for the entire object file.  Ideally we would just ignore them
 875  *    for the function, but that would require redesigning the code quite a
 876  *    bit.  And honestly that's just not worth doing: unreachable instruction
 877  *    warnings are of questionable value anyway, and this is such a rare issue.
 878  *
 879  * 3. mov [rodata addr],%reg1
 880  *    ... some instructions ...
 881  *    jmpq *(%reg1,%reg2,8)
 882  *
 883  *    This is a fairly uncommon pattern which is new for GCC 6.  As of this
 884  *    writing, there are 11 occurrences of it in the allmodconfig kernel.
 885  *
 886  *    As of GCC 7 there are quite a few more of these and the 'in between' code
 887  *    is significant. Esp. with KASAN enabled some of the code between the mov
 888  *    and jmpq uses .rodata itself, which can confuse things.
 889  *
 890  *    TODO: Once we have DWARF CFI and smarter instruction decoding logic,
 891  *    ensure the same register is used in the mov and jump instructions.
 892  *
 893  *    NOTE: RETPOLINE made it harder still to decode dynamic jumps.
 894  */
 895 static struct rela *find_switch_table(struct objtool_file *file,
 896                                       struct symbol *func,
 897                                       struct instruction *insn)
 898 {
 899         struct rela *text_rela, *rodata_rela;
 900         struct instruction *orig_insn = insn;
 901         unsigned long table_offset;
 902
 903         /*
 904          * Backward search using the @first_jump_src links, these help avoid
 905          * much of the 'in between' code. Which avoids us getting confused by
 906          * it.
 907          */
 908         for (;
 909              &insn->list != &file->insn_list &&
 910              insn->sec == func->sec &&
 911              insn->offset >= func->offset;
 912
 913              insn = insn->first_jump_src ?: list_prev_entry(insn, list)) {
 914
 915                 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
 916                         break;
 917
 918                 /* allow small jumps within the range */
 919                 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
 920                     insn->jump_dest &&
 921                     (insn->jump_dest->offset <= insn->offset ||
 922                      insn->jump_dest->offset > orig_insn->offset))
 923                     break;
 924
 925                 /* look for a relocation which references .rodata */
 926                 text_rela = find_rela_by_dest_range(insn->sec, insn->offset,
 927                                                     insn->len);
 928                 if (!text_rela || text_rela->sym != file->rodata->sym)
 929                         continue;
 930
 931                 table_offset = text_rela->addend;
 932                 if (text_rela->type == R_X86_64_PC32)
 933                         table_offset += 4;
 934
 935                 /*
 936                  * Make sure the .rodata address isn't associated with a
 937                  * symbol.  gcc jump tables are anonymous data.
 938                  */
 939                 if (find_symbol_containing(file->rodata, table_offset))
 940                         continue;
 941
 942                 rodata_rela = find_rela_by_dest(file->rodata, table_offset);
 943                 if (rodata_rela) {
 944                         /*
 945                          * Use of RIP-relative switch jumps is quite rare, and
 946                          * indicates a rare GCC quirk/bug which can leave dead
 947                          * code behind.
 948                          */
 949                         if (text_rela->type == R_X86_64_PC32)
 950                                 file->ignore_unreachables = true;
 951
 952                         return rodata_rela;
 953                 }
 954         }
 955
 956         return NULL;
 957 }
 958
 959
 960 static int add_func_switch_tables(struct objtool_file *file,
 961                                   struct symbol *func)
 962 {
 963         struct instruction *insn, *last = NULL, *prev_jump = NULL;
 964         struct rela *rela, *prev_rela = NULL;
 965         int ret;
 966
 967         func_for_each_insn_all(file, func, insn) {
 968                 if (!last)
 969                         last = insn;
 970
 971                 /*
 972                  * Store back-pointers for unconditional forward jumps such
 973                  * that find_switch_table() can back-track using those and
 974                  * avoid some potentially confusing code.
 975                  */
 976                 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
 977                     insn->offset > last->offset &&
 978                     insn->jump_dest->offset > insn->offset &&
 979                     !insn->jump_dest->first_jump_src) {
 980
 981                         insn->jump_dest->first_jump_src = insn;
 982                         last = insn->jump_dest;
 983                 }
 984
 985                 if (insn->type != INSN_JUMP_DYNAMIC)
 986                         continue;
 987
 988                 rela = find_switch_table(file, func, insn);
 989                 if (!rela)
 990                         continue;
 991
 992                 /*
 993                  * We found a switch table, but we don't know yet how big it
 994                  * is.  Don't add it until we reach the end of the function or
 995                  * the beginning of another switch table in the same function.
 996                  */
 997                 if (prev_jump) {
 998                         ret = add_switch_table(file, prev_jump, prev_rela, rela);
 999                         if (ret)
1000                                 return ret;
1001                 }
1002
1003                 prev_jump = insn;
1004                 prev_rela = rela;
1005         }
1006
1007         if (prev_jump) {
1008                 ret = add_switch_table(file, prev_jump, prev_rela, NULL);
1009                 if (ret)
1010                         return ret;
1011         }
1012
1013         return 0;
1014 }
1015
1016 /*
1017  * For some switch statements, gcc generates a jump table in the .rodata
1018  * section which contains a list of addresses within the function to jump to.
1019  * This finds these jump tables and adds them to the insn->alts lists.
1020  */
1021 static int add_switch_table_alts(struct objtool_file *file)
1022 {
1023         struct section *sec;
1024         struct symbol *func;
1025         int ret;
1026
1027         if (!file->rodata || !file->rodata->rela)
1028                 return 0;
1029
1030         for_each_sec(file, sec) {
1031                 list_for_each_entry(func, &sec->symbol_list, list) {
1032                         if (func->type != STT_FUNC)
1033                                 continue;
1034
1035                         ret = add_func_switch_tables(file, func);
1036                         if (ret)
1037                                 return ret;
1038                 }
1039         }
1040
1041         return 0;
1042 }
1043
1044 static int read_unwind_hints(struct objtool_file *file)
1045 {
1046         struct section *sec, *relasec;
1047         struct rela *rela;
1048         struct unwind_hint *hint;
1049         struct instruction *insn;
1050         struct cfi_reg *cfa;
1051         int i;
1052
1053         sec = find_section_by_name(file->elf, ".discard.unwind_hints");
1054         if (!sec)
1055                 return 0;
1056
1057         relasec = sec->rela;
1058         if (!relasec) {
1059                 WARN("missing .rela.discard.unwind_hints section");
1060                 return -1;
1061         }
1062
1063         if (sec->len % sizeof(struct unwind_hint)) {
1064                 WARN("struct unwind_hint size mismatch");
1065                 return -1;
1066         }
1067
1068         file->hints = true;
1069
1070         for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) {
1071                 hint = (struct unwind_hint *)sec->data->d_buf + i;
1072
1073                 rela = find_rela_by_dest(sec, i * sizeof(*hint));
1074                 if (!rela) {
1075                         WARN("can't find rela for unwind_hints[%d]", i);
1076                         return -1;
1077                 }
1078
1079                 insn = find_insn(file, rela->sym->sec, rela->addend);
1080                 if (!insn) {
1081                         WARN("can't find insn for unwind_hints[%d]", i);
1082                         return -1;
1083                 }
1084
1085                 cfa = &insn->state.cfa;
1086
1087                 if (hint->type == UNWIND_HINT_TYPE_SAVE) {
1088                         insn->save = true;
1089                         continue;
1090
1091                 } else if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
1092                         insn->restore = true;
1093                         insn->hint = true;
1094                         continue;
1095                 }
1096
1097                 insn->hint = true;
1098
1099                 switch (hint->sp_reg) {
1100                 case ORC_REG_UNDEFINED:
1101                         cfa->base = CFI_UNDEFINED;
1102                         break;
1103                 case ORC_REG_SP:
1104                         cfa->base = CFI_SP;
1105                         break;
1106                 case ORC_REG_BP:
1107                         cfa->base = CFI_BP;
1108                         break;
1109                 case ORC_REG_SP_INDIRECT:
1110                         cfa->base = CFI_SP_INDIRECT;
1111                         break;
1112                 case ORC_REG_R10:
1113                         cfa->base = CFI_R10;
1114                         break;
1115                 case ORC_REG_R13:
1116                         cfa->base = CFI_R13;
1117                         break;
1118                 case ORC_REG_DI:
1119                         cfa->base = CFI_DI;
1120                         break;
1121                 case ORC_REG_DX:
1122                         cfa->base = CFI_DX;
1123                         break;
1124                 default:
1125                         WARN_FUNC("unsupported unwind_hint sp base reg %d",
1126                                   insn->sec, insn->offset, hint->sp_reg);
1127                         return -1;
1128                 }
1129
1130                 cfa->offset = hint->sp_offset;
1131                 insn->state.type = hint->type;
1132         }
1133
1134         return 0;
1135 }
1136
1137 static int read_retpoline_hints(struct objtool_file *file)
1138 {
1139         struct section *sec;
1140         struct instruction *insn;
1141         struct rela *rela;
1142
1143         sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
1144         if (!sec)
1145                 return 0;
1146
1147         list_for_each_entry(rela, &sec->rela_list, list) {
1148                 if (rela->sym->type != STT_SECTION) {
1149                         WARN("unexpected relocation symbol type in %s", sec->name);
1150                         return -1;
1151                 }
1152
1153                 insn = find_insn(file, rela->sym->sec, rela->addend);
1154                 if (!insn) {
1155                         WARN("bad .discard.retpoline_safe entry");
1156                         return -1;
1157                 }
1158
1159                 if (insn->type != INSN_JUMP_DYNAMIC &&
1160                     insn->type != INSN_CALL_DYNAMIC) {
1161                         WARN_FUNC("retpoline_safe hint not an indirect jump/call",
1162                                   insn->sec, insn->offset);
1163                         return -1;
1164                 }
1165
1166                 insn->retpoline_safe = true;
1167         }
1168
1169         return 0;
1170 }
1171
1172 static int decode_sections(struct objtool_file *file)
1173 {
1174         int ret;
1175
1176         ret = decode_instructions(file);
1177         if (ret)
1178                 return ret;
1179
1180         ret = add_dead_ends(file);
1181         if (ret)
1182                 return ret;
1183
1184         add_ignores(file);
1185
1186         ret = add_nospec_ignores(file);
1187         if (ret)
1188                 return ret;
1189
1190         ret = add_jump_destinations(file);
1191         if (ret)
1192                 return ret;
1193
1194         ret = add_special_section_alts(file);
1195         if (ret)
1196                 return ret;
1197
1198         ret = add_call_destinations(file);
1199         if (ret)
1200                 return ret;
1201
1202         ret = add_switch_table_alts(file);
1203         if (ret)
1204                 return ret;
1205
1206         ret = read_unwind_hints(file);
1207         if (ret)
1208                 return ret;
1209
1210         ret = read_retpoline_hints(file);
1211         if (ret)
1212                 return ret;
1213
1214         return 0;
1215 }
1216
1217 static bool is_fentry_call(struct instruction *insn)
1218 {
1219         if (insn->type == INSN_CALL &&
1220             insn->call_dest->type == STT_NOTYPE &&
1221             !strcmp(insn->call_dest->name, "__fentry__"))
1222                 return true;
1223
1224         return false;
1225 }
1226
1227 static bool has_modified_stack_frame(struct insn_state *state)
1228 {
1229         int i;
1230
1231         if (state->cfa.base != initial_func_cfi.cfa.base ||
1232             state->cfa.offset != initial_func_cfi.cfa.offset ||
1233             state->stack_size != initial_func_cfi.cfa.offset ||
1234             state->drap)
1235                 return true;
1236
1237         for (i = 0; i < CFI_NUM_REGS; i++)
1238                 if (state->regs[i].base != initial_func_cfi.regs[i].base ||
1239                     state->regs[i].offset != initial_func_cfi.regs[i].offset)
1240                         return true;
1241
1242         return false;
1243 }
1244
1245 static bool has_valid_stack_frame(struct insn_state *state)
1246 {
1247         if (state->cfa.base == CFI_BP && state->regs[CFI_BP].base == CFI_CFA &&
1248             state->regs[CFI_BP].offset == -16)
1249                 return true;
1250
1251         if (state->drap && state->regs[CFI_BP].base == CFI_BP)
1252                 return true;
1253
1254         return false;
1255 }
1256
1257 static int update_insn_state_regs(struct instruction *insn, struct insn_state *state)
1258 {
1259         struct cfi_reg *cfa = &state->cfa;
1260         struct stack_op *op = &insn->stack_op;
1261
1262         if (cfa->base != CFI_SP)
1263                 return 0;
1264
1265         /* push */
1266         if (op->dest.type == OP_DEST_PUSH)
1267                 cfa->offset += 8;
1268
1269         /* pop */
1270         if (op->src.type == OP_SRC_POP)
1271                 cfa->offset -= 8;
1272
1273         /* add immediate to sp */
1274         if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
1275             op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
1276                 cfa->offset -= op->src.offset;
1277
1278         return 0;
1279 }
1280
1281 static void save_reg(struct insn_state *state, unsigned char reg, int base,
1282                      int offset)
1283 {
1284         if (arch_callee_saved_reg(reg) &&
1285             state->regs[reg].base == CFI_UNDEFINED) {
1286                 state->regs[reg].base = base;
1287                 state->regs[reg].offset = offset;
1288         }
1289 }
1290
1291 static void restore_reg(struct insn_state *state, unsigned char reg)
1292 {
1293         state->regs[reg].base = CFI_UNDEFINED;
1294         state->regs[reg].offset = 0;
1295 }
1296
1297 /*
1298  * A note about DRAP stack alignment:
1299  *
1300  * GCC has the concept of a DRAP register, which is used to help keep track of
1301  * the stack pointer when aligning the stack.  r10 or r13 is used as the DRAP
1302  * register.  The typical DRAP pattern is:
1303  *
1304  *   4c 8d 54 24 08             lea    0x8(%rsp),%r10
1305  *   48 83 e4 c0                and    $0xffffffffffffffc0,%rsp
1306  *   41 ff 72 f8                pushq  -0x8(%r10)
1307  *   55                         push   %rbp
1308  *   48 89 e5                   mov    %rsp,%rbp
1309  *                              (more pushes)
1310  *   41 52                      push   %r10
1311  *                              ...
1312  *   41 5a                      pop    %r10
1313  *                              (more pops)
1314  *   5d                         pop    %rbp
1315  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
1316  *   c3                         retq
1317  *
1318  * There are some variations in the epilogues, like:
1319  *
1320  *   5b                         pop    %rbx
1321  *   41 5a                      pop    %r10
1322  *   41 5c                      pop    %r12
1323  *   41 5d                      pop    %r13
1324  *   41 5e                      pop    %r14
1325  *   c9                         leaveq
1326  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
1327  *   c3                         retq
1328  *
1329  * and:
1330  *
1331  *   4c 8b 55 e8                mov    -0x18(%rbp),%r10
1332  *   48 8b 5d e0                mov    -0x20(%rbp),%rbx
1333  *   4c 8b 65 f0                mov    -0x10(%rbp),%r12
1334  *   4c 8b 6d f8                mov    -0x8(%rbp),%r13
1335  *   c9                         leaveq
1336  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
1337  *   c3                         retq
1338  *
1339  * Sometimes r13 is used as the DRAP register, in which case it's saved and
1340  * restored beforehand:
1341  *
1342  *   41 55                      push   %r13
1343  *   4c 8d 6c 24 10             lea    0x10(%rsp),%r13
1344  *   48 83 e4 f0                and    $0xfffffffffffffff0,%rsp
1345  *                              ...
1346  *   49 8d 65 f0                lea    -0x10(%r13),%rsp
1347  *   41 5d                      pop    %r13
1348  *   c3                         retq
1349  */
1350 static int update_insn_state(struct instruction *insn, struct insn_state *state)
1351 {
1352         struct stack_op *op = &insn->stack_op;
1353         struct cfi_reg *cfa = &state->cfa;
1354         struct cfi_reg *regs = state->regs;
1355
1356         /* stack operations don't make sense with an undefined CFA */
1357         if (cfa->base == CFI_UNDEFINED) {
1358                 if (insn->func) {
1359                         WARN_FUNC("undefined stack state", insn->sec, insn->offset);
1360                         return -1;
1361                 }
1362                 return 0;
1363         }
1364
1365         if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET)
1366                 return update_insn_state_regs(insn, state);
1367
1368         switch (op->dest.type) {
1369
1370         case OP_DEST_REG:
1371                 switch (op->src.type) {
1372
1373                 case OP_SRC_REG:
1374                         if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
1375                             cfa->base == CFI_SP &&
1376                             regs[CFI_BP].base == CFI_CFA &&
1377                             regs[CFI_BP].offset == -cfa->offset) {
1378
1379                                 /* mov %rsp, %rbp */
1380                                 cfa->base = op->dest.reg;
1381                                 state->bp_scratch = false;
1382                         }
1383
1384                         else if (op->src.reg == CFI_SP &&
1385                                  op->dest.reg == CFI_BP && state->drap) {
1386
1387                                 /* drap: mov %rsp, %rbp */
1388                                 regs[CFI_BP].base = CFI_BP;
1389                                 regs[CFI_BP].offset = -state->stack_size;
1390                                 state->bp_scratch = false;
1391                         }
1392
1393                         else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
1394
1395                                 /*
1396                                  * mov %rsp, %reg
1397                                  *
1398                                  * This is needed for the rare case where GCC
1399                                  * does:
1400                                  *
1401                                  *   mov    %rsp, %rax
1402                                  *   ...
1403                                  *   mov    %rax, %rsp
1404                                  */
1405                                 state->vals[op->dest.reg].base = CFI_CFA;
1406                                 state->vals[op->dest.reg].offset = -state->stack_size;
1407                         }
1408
1409                         else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
1410                                  cfa->base == CFI_BP) {
1411
1412                                 /*
1413                                  * mov %rbp, %rsp
1414                                  *
1415                                  * Restore the original stack pointer (Clang).
1416                                  */
1417                                 state->stack_size = -state->regs[CFI_BP].offset;
1418                         }
1419
1420                         else if (op->dest.reg == cfa->base) {
1421
1422                                 /* mov %reg, %rsp */
1423                                 if (cfa->base == CFI_SP &&
1424                                     state->vals[op->src.reg].base == CFI_CFA) {
1425
1426                                         /*
1427                                          * This is needed for the rare case
1428                                          * where GCC does something dumb like:
1429                                          *
1430                                          *   lea    0x8(%rsp), %rcx
1431                                          *   ...
1432                                          *   mov    %rcx, %rsp
1433                                          */
1434                                         cfa->offset = -state->vals[op->src.reg].offset;
1435                                         state->stack_size = cfa->offset;
1436
1437                                 } else {
1438                                         cfa->base = CFI_UNDEFINED;
1439                                         cfa->offset = 0;
1440                                 }
1441                         }
1442
1443                         break;
1444
1445                 case OP_SRC_ADD:
1446                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
1447
1448                                 /* add imm, %rsp */
1449                                 state->stack_size -= op->src.offset;
1450                                 if (cfa->base == CFI_SP)
1451                                         cfa->offset -= op->src.offset;
1452                                 break;
1453                         }
1454
1455                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
1456
1457                                 /* lea disp(%rbp), %rsp */
1458                                 state->stack_size = -(op->src.offset + regs[CFI_BP].offset);
1459                                 break;
1460                         }
1461
1462                         if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
1463
1464                                 /* drap: lea disp(%rsp), %drap */
1465                                 state->drap_reg = op->dest.reg;
1466
1467                                 /*
1468                                  * lea disp(%rsp), %reg
1469                                  *
1470                                  * This is needed for the rare case where GCC
1471                                  * does something dumb like:
1472                                  *
1473                                  *   lea    0x8(%rsp), %rcx
1474                                  *   ...
1475                                  *   mov    %rcx, %rsp
1476                                  */
1477                                 state->vals[op->dest.reg].base = CFI_CFA;
1478                                 state->vals[op->dest.reg].offset = \
1479                                         -state->stack_size + op->src.offset;
1480
1481                                 break;
1482                         }
1483
1484                         if (state->drap && op->dest.reg == CFI_SP &&
1485                             op->src.reg == state->drap_reg) {
1486
1487                                  /* drap: lea disp(%drap), %rsp */
1488                                 cfa->base = CFI_SP;
1489                                 cfa->offset = state->stack_size = -op->src.offset;
1490                                 state->drap_reg = CFI_UNDEFINED;
1491                                 state->drap = false;
1492                                 break;
1493                         }
1494
1495                         if (op->dest.reg == state->cfa.base) {
1496                                 WARN_FUNC("unsupported stack register modification",
1497                                           insn->sec, insn->offset);
1498                                 return -1;
1499                         }
1500
1501                         break;
1502
1503                 case OP_SRC_AND:
1504                         if (op->dest.reg != CFI_SP ||
1505                             (state->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
1506                             (state->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
1507                                 WARN_FUNC("unsupported stack pointer realignment",
1508                                           insn->sec, insn->offset);
1509                                 return -1;
1510                         }
1511
1512                         if (state->drap_reg != CFI_UNDEFINED) {
1513                                 /* drap: and imm, %rsp */
1514                                 cfa->base = state->drap_reg;
1515                                 cfa->offset = state->stack_size = 0;
1516                                 state->drap = true;
1517                         }
1518
1519                         /*
1520                          * Older versions of GCC (4.8ish) realign the stack
1521                          * without DRAP, with a frame pointer.
1522                          */
1523
1524                         break;
1525
1526                 case OP_SRC_POP:
1527                         if (!state->drap && op->dest.type == OP_DEST_REG &&
1528                             op->dest.reg == cfa->base) {
1529
1530                                 /* pop %rbp */
1531                                 cfa->base = CFI_SP;
1532                         }
1533
1534                         if (state->drap && cfa->base == CFI_BP_INDIRECT &&
1535                             op->dest.type == OP_DEST_REG &&
1536                             op->dest.reg == state->drap_reg &&
1537                             state->drap_offset == -state->stack_size) {
1538
1539                                 /* drap: pop %drap */
1540                                 cfa->base = state->drap_reg;
1541                                 cfa->offset = 0;
1542                                 state->drap_offset = -1;
1543
1544                         } else if (regs[op->dest.reg].offset == -state->stack_size) {
1545
1546                                 /* pop %reg */
1547                                 restore_reg(state, op->dest.reg);
1548                         }
1549
1550                         state->stack_size -= 8;
1551                         if (cfa->base == CFI_SP)
1552                                 cfa->offset -= 8;
1553
1554                         break;
1555
1556                 case OP_SRC_REG_INDIRECT:
1557                         if (state->drap && op->src.reg == CFI_BP &&
1558                             op->src.offset == state->drap_offset) {
1559
1560                                 /* drap: mov disp(%rbp), %drap */
1561                                 cfa->base = state->drap_reg;
1562                                 cfa->offset = 0;
1563                                 state->drap_offset = -1;
1564                         }
1565
1566                         if (state->drap && op->src.reg == CFI_BP &&
1567                             op->src.offset == regs[op->dest.reg].offset) {
1568
1569                                 /* drap: mov disp(%rbp), %reg */
1570                                 restore_reg(state, op->dest.reg);
1571
1572                         } else if (op->src.reg == cfa->base &&
1573                             op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
1574
1575                                 /* mov disp(%rbp), %reg */
1576                                 /* mov disp(%rsp), %reg */
1577                                 restore_reg(state, op->dest.reg);
1578                         }
1579
1580                         break;
1581
1582                 default:
1583                         WARN_FUNC("unknown stack-related instruction",
1584                                   insn->sec, insn->offset);
1585                         return -1;
1586                 }
1587
1588                 break;
1589
1590         case OP_DEST_PUSH:
1591                 state->stack_size += 8;
1592                 if (cfa->base == CFI_SP)
1593                         cfa->offset += 8;
1594
1595                 if (op->src.type != OP_SRC_REG)
1596                         break;
1597
1598                 if (state->drap) {
1599                         if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
1600
1601                                 /* drap: push %drap */
1602                                 cfa->base = CFI_BP_INDIRECT;
1603                                 cfa->offset = -state->stack_size;
1604
1605                                 /* save drap so we know when to restore it */
1606                                 state->drap_offset = -state->stack_size;
1607
1608                         } else if (op->src.reg == CFI_BP && cfa->base == state->drap_reg) {
1609
1610                                 /* drap: push %rbp */
1611                                 state->stack_size = 0;
1612
1613                         } else if (regs[op->src.reg].base == CFI_UNDEFINED) {
1614
1615                                 /* drap: push %reg */
1616                                 save_reg(state, op->src.reg, CFI_BP, -state->stack_size);
1617                         }
1618
1619                 } else {
1620
1621                         /* push %reg */
1622                         save_reg(state, op->src.reg, CFI_CFA, -state->stack_size);
1623                 }
1624
1625                 /* detect when asm code uses rbp as a scratch register */
1626                 if (!no_fp && insn->func && op->src.reg == CFI_BP &&
1627                     cfa->base != CFI_BP)
1628                         state->bp_scratch = true;
1629                 break;
1630
1631         case OP_DEST_REG_INDIRECT:
1632
1633                 if (state->drap) {
1634                         if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
1635
1636                                 /* drap: mov %drap, disp(%rbp) */
1637                                 cfa->base = CFI_BP_INDIRECT;
1638                                 cfa->offset = op->dest.offset;
1639
1640                                 /* save drap offset so we know when to restore it */
1641                                 state->drap_offset = op->dest.offset;
1642                         }
1643
1644                         else if (regs[op->src.reg].base == CFI_UNDEFINED) {
1645
1646                                 /* drap: mov reg, disp(%rbp) */
1647                                 save_reg(state, op->src.reg, CFI_BP, op->dest.offset);
1648                         }
1649
1650                 } else if (op->dest.reg == cfa->base) {
1651
1652                         /* mov reg, disp(%rbp) */
1653                         /* mov reg, disp(%rsp) */
1654                         save_reg(state, op->src.reg, CFI_CFA,
1655                                  op->dest.offset - state->cfa.offset);
1656                 }
1657
1658                 break;
1659
1660         case OP_DEST_LEAVE:
1661                 if ((!state->drap && cfa->base != CFI_BP) ||
1662                     (state->drap && cfa->base != state->drap_reg)) {
1663                         WARN_FUNC("leave instruction with modified stack frame",
1664                                   insn->sec, insn->offset);
1665                         return -1;
1666                 }
1667
1668                 /* leave (mov %rbp, %rsp; pop %rbp) */
1669
1670                 state->stack_size = -state->regs[CFI_BP].offset - 8;
1671                 restore_reg(state, CFI_BP);
1672
1673                 if (!state->drap) {
1674                         cfa->base = CFI_SP;
1675                         cfa->offset -= 8;
1676                 }
1677
1678                 break;
1679
1680         case OP_DEST_MEM:
1681                 if (op->src.type != OP_SRC_POP) {
1682                         WARN_FUNC("unknown stack-related memory operation",
1683                                   insn->sec, insn->offset);
1684                         return -1;
1685                 }
1686
1687                 /* pop mem */
1688                 state->stack_size -= 8;
1689                 if (cfa->base == CFI_SP)
1690                         cfa->offset -= 8;
1691
1692                 break;
1693
1694         default:
1695                 WARN_FUNC("unknown stack-related instruction",
1696                           insn->sec, insn->offset);
1697                 return -1;
1698         }
1699
1700         return 0;
1701 }
1702
1703 static bool insn_state_match(struct instruction *insn, struct insn_state *state)
1704 {
1705         struct insn_state *state1 = &insn->state, *state2 = state;
1706         int i;
1707
1708         if (memcmp(&state1->cfa, &state2->cfa, sizeof(state1->cfa))) {
1709                 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
1710                           insn->sec, insn->offset,
1711                           state1->cfa.base, state1->cfa.offset,
1712                           state2->cfa.base, state2->cfa.offset);
1713
1714         } else if (memcmp(&state1->regs, &state2->regs, sizeof(state1->regs))) {
1715                 for (i = 0; i < CFI_NUM_REGS; i++) {
1716                         if (!memcmp(&state1->regs[i], &state2->regs[i],
1717                                     sizeof(struct cfi_reg)))
1718                                 continue;
1719
1720                         WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
1721                                   insn->sec, insn->offset,
1722                                   i, state1->regs[i].base, state1->regs[i].offset,
1723                                   i, state2->regs[i].base, state2->regs[i].offset);
1724                         break;
1725                 }
1726
1727         } else if (state1->type != state2->type) {
1728                 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
1729                           insn->sec, insn->offset, state1->type, state2->type);
1730
1731         } else if (state1->drap != state2->drap ||
1732                  (state1->drap && state1->drap_reg != state2->drap_reg) ||
1733                  (state1->drap && state1->drap_offset != state2->drap_offset)) {
1734                 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
1735                           insn->sec, insn->offset,
1736                           state1->drap, state1->drap_reg, state1->drap_offset,
1737                           state2->drap, state2->drap_reg, state2->drap_offset);
1738
1739         } else
1740                 return true;
1741
1742         return false;
1743 }
1744
1745 /*
1746  * Follow the branch starting at the given instruction, and recursively follow
1747  * any other branches (jumps).  Meanwhile, track the frame pointer state at
1748  * each instruction and validate all the rules described in
1749  * tools/objtool/Documentation/stack-validation.txt.
1750  */
1751 static int validate_branch(struct objtool_file *file, struct instruction *first,
1752                            struct insn_state state)
1753 {
1754         struct alternative *alt;
1755         struct instruction *insn, *next_insn;
1756         struct section *sec;
1757         struct symbol *func = NULL;
1758         int ret;
1759
1760         insn = first;
1761         sec = insn->sec;
1762
1763         if (insn->alt_group && list_empty(&insn->alts)) {
1764                 WARN_FUNC("don't know how to handle branch to middle of alternative instruction group",
1765                           sec, insn->offset);
1766                 return 1;
1767         }
1768
1769         while (1) {
1770                 next_insn = next_insn_same_sec(file, insn);
1771
1772                 if (file->c_file && func && insn->func && func != insn->func->pfunc) {
1773                         WARN("%s() falls through to next function %s()",
1774                              func->name, insn->func->name);
1775                         return 1;
1776                 }
1777
1778                 func = insn->func ? insn->func->pfunc : NULL;
1779
1780                 if (func && insn->ignore) {
1781                         WARN_FUNC("BUG: why am I validating an ignored function?",
1782                                   sec, insn->offset);
1783                         return 1;
1784                 }
1785
1786                 if (insn->visited) {
1787                         if (!insn->hint && !insn_state_match(insn, &state))
1788                                 return 1;
1789
1790                         return 0;
1791                 }
1792
1793                 if (insn->hint) {
1794                         if (insn->restore) {
1795                                 struct instruction *save_insn, *i;
1796
1797                                 i = insn;
1798                                 save_insn = NULL;
1799                                 func_for_each_insn_continue_reverse(file, insn->func, i) {
1800                                         if (i->save) {
1801                                                 save_insn = i;
1802                                                 break;
1803                                         }
1804                                 }
1805
1806                                 if (!save_insn) {
1807                                         WARN_FUNC("no corresponding CFI save for CFI restore",
1808                                                   sec, insn->offset);
1809                                         return 1;
1810                                 }
1811
1812                                 if (!save_insn->visited) {
1813                                         /*
1814                                          * Oops, no state to copy yet.
1815                                          * Hopefully we can reach this
1816                                          * instruction from another branch
1817                                          * after the save insn has been
1818                                          * visited.
1819                                          */
1820                                         if (insn == first)
1821                                                 return 0;
1822
1823                                         WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
1824                                                   sec, insn->offset);
1825                                         return 1;
1826                                 }
1827
1828                                 insn->state = save_insn->state;
1829                         }
1830
1831                         state = insn->state;
1832
1833                 } else
1834                         insn->state = state;
1835
1836                 insn->visited = true;
1837
1838                 if (!insn->ignore_alts) {
1839                         list_for_each_entry(alt, &insn->alts, list) {
1840                                 ret = validate_branch(file, alt->insn, state);
1841                                 if (ret)
1842                                         return 1;
1843                         }
1844                 }
1845
1846                 switch (insn->type) {
1847
1848                 case INSN_RETURN:
1849                         if (func && has_modified_stack_frame(&state)) {
1850                                 WARN_FUNC("return with modified stack frame",
1851                                           sec, insn->offset);
1852                                 return 1;
1853                         }
1854
1855                         if (state.bp_scratch) {
1856                                 WARN("%s uses BP as a scratch register",
1857                                      insn->func->name);
1858                                 return 1;
1859                         }
1860
1861                         return 0;
1862
1863                 case INSN_CALL:
1864                         if (is_fentry_call(insn))
1865                                 break;
1866
1867                         ret = dead_end_function(file, insn->call_dest);
1868                         if (ret == 1)
1869                                 return 0;
1870                         if (ret == -1)
1871                                 return 1;
1872
1873                         /* fallthrough */
1874                 case INSN_CALL_DYNAMIC:
1875                         if (!no_fp && func && !has_valid_stack_frame(&state)) {
1876                                 WARN_FUNC("call without frame pointer save/setup",
1877                                           sec, insn->offset);
1878                                 return 1;
1879                         }
1880                         break;
1881
1882                 case INSN_JUMP_CONDITIONAL:
1883                 case INSN_JUMP_UNCONDITIONAL:
1884                         if (insn->jump_dest &&
1885                             (!func || !insn->jump_dest->func ||
1886                              insn->jump_dest->func->pfunc == func)) {
1887                                 ret = validate_branch(file, insn->jump_dest,
1888                                                       state);
1889                                 if (ret)
1890                                         return 1;
1891
1892                         } else if (func && has_modified_stack_frame(&state)) {
1893                                 WARN_FUNC("sibling call from callable instruction with modified stack frame",
1894                                           sec, insn->offset);
1895                                 return 1;
1896                         }
1897
1898                         if (insn->type == INSN_JUMP_UNCONDITIONAL)
1899                                 return 0;
1900
1901                         break;
1902
1903                 case INSN_JUMP_DYNAMIC:
1904                         if (func && list_empty(&insn->alts) &&
1905                             has_modified_stack_frame(&state)) {
1906                                 WARN_FUNC("sibling call from callable instruction with modified stack frame",
1907                                           sec, insn->offset);
1908                                 return 1;
1909                         }
1910
1911                         return 0;
1912
1913                 case INSN_CONTEXT_SWITCH:
1914                         if (func && (!next_insn || !next_insn->hint)) {
1915                                 WARN_FUNC("unsupported instruction in callable function",
1916                                           sec, insn->offset);
1917                                 return 1;
1918                         }
1919                         return 0;
1920
1921                 case INSN_STACK:
1922                         if (update_insn_state(insn, &state))
1923                                 return 1;
1924
1925                         break;
1926
1927                 default:
1928                         break;
1929                 }
1930
1931                 if (insn->dead_end)
1932                         return 0;
1933
1934                 if (!next_insn) {
1935                         if (state.cfa.base == CFI_UNDEFINED)
1936                                 return 0;
1937                         WARN("%s: unexpected end of section", sec->name);
1938                         return 1;
1939                 }
1940
1941                 insn = next_insn;
1942         }
1943
1944         return 0;
1945 }
1946
1947 static int validate_unwind_hints(struct objtool_file *file)
1948 {
1949         struct instruction *insn;
1950         int ret, warnings = 0;
1951         struct insn_state state;
1952
1953         if (!file->hints)
1954                 return 0;
1955
1956         clear_insn_state(&state);
1957
1958         for_each_insn(file, insn) {
1959                 if (insn->hint && !insn->visited) {
1960                         ret = validate_branch(file, insn, state);
1961                         warnings += ret;
1962                 }
1963         }
1964
1965         return warnings;
1966 }
1967
1968 static int validate_retpoline(struct objtool_file *file)
1969 {
1970         struct instruction *insn;
1971         int warnings = 0;
1972
1973         for_each_insn(file, insn) {
1974                 if (insn->type != INSN_JUMP_DYNAMIC &&
1975                     insn->type != INSN_CALL_DYNAMIC)
1976                         continue;
1977
1978                 if (insn->retpoline_safe)
1979                         continue;
1980
1981                 /*
1982                  * .init.text code is ran before userspace and thus doesn't
1983                  * strictly need retpolines, except for modules which are
1984                  * loaded late, they very much do need retpoline in their
1985                  * .init.text
1986                  */
1987                 if (!strcmp(insn->sec->name, ".init.text") && !module)
1988                         continue;
1989
1990                 WARN_FUNC("indirect %s found in RETPOLINE build",
1991                           insn->sec, insn->offset,
1992                           insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
1993
1994                 warnings++;
1995         }
1996
1997         return warnings;
1998 }
1999
2000 static bool is_kasan_insn(struct instruction *insn)
2001 {
2002         return (insn->type == INSN_CALL &&
2003                 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
2004 }
2005
2006 static bool is_ubsan_insn(struct instruction *insn)
2007 {
2008         return (insn->type == INSN_CALL &&
2009                 !strcmp(insn->call_dest->name,
2010                         "__ubsan_handle_builtin_unreachable"));
2011 }
2012
2013 static bool ignore_unreachable_insn(struct instruction *insn)
2014 {
2015         int i;
2016
2017         if (insn->ignore || insn->type == INSN_NOP)
2018                 return true;
2019
2020         /*
2021          * Ignore any unused exceptions.  This can happen when a whitelisted
2022          * function has an exception table entry.
2023          *
2024          * Also ignore alternative replacement instructions.  This can happen
2025          * when a whitelisted function uses one of the ALTERNATIVE macros.
2026          */
2027         if (!strcmp(insn->sec->name, ".fixup") ||
2028             !strcmp(insn->sec->name, ".altinstr_replacement") ||
2029             !strcmp(insn->sec->name, ".altinstr_aux"))
2030                 return true;
2031
2032         /*
2033          * Check if this (or a subsequent) instruction is related to
2034          * CONFIG_UBSAN or CONFIG_KASAN.
2035          *
2036          * End the search at 5 instructions to avoid going into the weeds.
2037          */
2038         if (!insn->func)
2039                 return false;
2040         for (i = 0; i < 5; i++) {
2041
2042                 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
2043                         return true;
2044
2045                 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
2046                         if (insn->jump_dest &&
2047                             insn->jump_dest->func == insn->func) {
2048                                 insn = insn->jump_dest;
2049                                 continue;
2050                         }
2051
2052                         break;
2053                 }
2054
2055                 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
2056                         break;
2057
2058                 insn = list_next_entry(insn, list);
2059         }
2060
2061         return false;
2062 }
2063
2064 static int validate_functions(struct objtool_file *file)
2065 {
2066         struct section *sec;
2067         struct symbol *func;
2068         struct instruction *insn;
2069         struct insn_state state;
2070         int ret, warnings = 0;
2071
2072         clear_insn_state(&state);
2073
2074         state.cfa = initial_func_cfi.cfa;
2075         memcpy(&state.regs, &initial_func_cfi.regs,
2076                CFI_NUM_REGS * sizeof(struct cfi_reg));
2077         state.stack_size = initial_func_cfi.cfa.offset;
2078
2079         for_each_sec(file, sec) {
2080                 list_for_each_entry(func, &sec->symbol_list, list) {
2081                         if (func->type != STT_FUNC || func->pfunc != func)
2082                                 continue;
2083
2084                         insn = find_insn(file, sec, func->offset);
2085                         if (!insn || insn->ignore)
2086                                 continue;
2087
2088                         ret = validate_branch(file, insn, state);
2089                         warnings += ret;
2090                 }
2091         }
2092
2093         return warnings;
2094 }
2095
2096 static int validate_reachable_instructions(struct objtool_file *file)
2097 {
2098         struct instruction *insn;
2099
2100         if (file->ignore_unreachables)
2101                 return 0;
2102
2103         for_each_insn(file, insn) {
2104                 if (insn->visited || ignore_unreachable_insn(insn))
2105                         continue;
2106
2107                 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
2108                 return 1;
2109         }
2110
2111         return 0;
2112 }
2113
2114 static void cleanup(struct objtool_file *file)
2115 {
2116         struct instruction *insn, *tmpinsn;
2117         struct alternative *alt, *tmpalt;
2118
2119         list_for_each_entry_safe(insn, tmpinsn, &file->insn_list, list) {
2120                 list_for_each_entry_safe(alt, tmpalt, &insn->alts, list) {
2121                         list_del(&alt->list);
2122                         free(alt);
2123                 }
2124                 list_del(&insn->list);
2125                 hash_del(&insn->hash);
2126                 free(insn);
2127         }
2128         elf_close(file->elf);
2129 }
2130
2131 int check(const char *_objname, bool orc)
2132 {
2133         struct objtool_file file;
2134         int ret, warnings = 0;
2135
2136         objname = _objname;
2137
2138         file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY);
2139         if (!file.elf)
2140                 return 1;
2141
2142         INIT_LIST_HEAD(&file.insn_list);
2143         hash_init(file.insn_hash);
2144         file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard");
2145         file.rodata = find_section_by_name(file.elf, ".rodata");
2146         file.c_file = find_section_by_name(file.elf, ".comment");
2147         file.ignore_unreachables = no_unreachable;
2148         file.hints = false;
2149
2150         arch_initial_func_cfi_state(&initial_func_cfi);
2151
2152         ret = decode_sections(&file);
2153         if (ret < 0)
2154                 goto out;
2155         warnings += ret;
2156
2157         if (list_empty(&file.insn_list))
2158                 goto out;
2159
2160         if (retpoline) {
2161                 ret = validate_retpoline(&file);
2162                 if (ret < 0)
2163                         return ret;
2164                 warnings += ret;
2165         }
2166
2167         ret = validate_functions(&file);
2168         if (ret < 0)
2169                 goto out;
2170         warnings += ret;
2171
2172         ret = validate_unwind_hints(&file);
2173         if (ret < 0)
2174                 goto out;
2175         warnings += ret;
2176
2177         if (!warnings) {
2178                 ret = validate_reachable_instructions(&file);
2179                 if (ret < 0)
2180                         goto out;
2181                 warnings += ret;
2182         }
2183
2184         if (orc) {
2185                 ret = create_orc(&file);
2186                 if (ret < 0)
2187                         goto out;
2188
2189                 ret = create_orc_sections(&file);
2190                 if (ret < 0)
2191                         goto out;
2192
2193                 ret = elf_write(file.elf);
2194                 if (ret < 0)
2195                         goto out;
2196         }
2197
2198 out:
2199         cleanup(&file);
2200
2201         /* ignore warnings for now until we get all the code cleaned up */
2202         if (ret || warnings)
2203                 return 0;
2204         return 0;
2205 }