tools/objtool/check.c

   1 /*
   2  * Copyright (C) 2015-2017 Josh Poimboeuf <[email protected]>
   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                 "usercopy_abort",
 167                 "machine_real_restart",
 168         };
 169
 170         if (func->bind == STB_WEAK)
 171                 return 0;
 172
 173         if (func->bind == STB_GLOBAL)
 174                 for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
 175                         if (!strcmp(func->name, global_noreturns[i]))
 176                                 return 1;
 177
 178         if (!func->len)
 179                 return 0;
 180
 181         insn = find_insn(file, func->sec, func->offset);
 182         if (!insn->func)
 183                 return 0;
 184
 185         func_for_each_insn_all(file, func, insn) {
 186                 empty = false;
 187
 188                 if (insn->type == INSN_RETURN)
 189                         return 0;
 190         }
 191
 192         if (empty)
 193                 return 0;
 194
 195         /*
 196          * A function can have a sibling call instead of a return.  In that
 197          * case, the function's dead-end status depends on whether the target
 198          * of the sibling call returns.
 199          */
 200         func_for_each_insn_all(file, func, insn) {
 201                 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
 202                         struct instruction *dest = insn->jump_dest;
 203
 204                         if (!dest)
 205                                 /* sibling call to another file */
 206                                 return 0;
 207
 208                         if (dest->func && dest->func->pfunc != insn->func->pfunc) {
 209
 210                                 /* local sibling call */
 211                                 if (recursion == 5) {
 212                                         /*
 213                                          * Infinite recursion: two functions
 214                                          * have sibling calls to each other.
 215                                          * This is a very rare case.  It means
 216                                          * they aren't dead ends.
 217                                          */
 218                                         return 0;
 219                                 }
 220
 221                                 return __dead_end_function(file, dest->func,
 222                                                            recursion + 1);
 223                         }
 224                 }
 225
 226                 if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts))
 227                         /* sibling call */
 228                         return 0;
 229         }
 230
 231         return 1;
 232 }
 233
 234 static int dead_end_function(struct objtool_file *file, struct symbol *func)
 235 {
 236         return __dead_end_function(file, func, 0);
 237 }
 238
 239 static void clear_insn_state(struct insn_state *state)
 240 {
 241         int i;
 242
 243         memset(state, 0, sizeof(*state));
 244         state->cfa.base = CFI_UNDEFINED;
 245         for (i = 0; i < CFI_NUM_REGS; i++) {
 246                 state->regs[i].base = CFI_UNDEFINED;
 247                 state->vals[i].base = CFI_UNDEFINED;
 248         }
 249         state->drap_reg = CFI_UNDEFINED;
 250         state->drap_offset = -1;
 251 }
 252
 253 /*
 254  * Call the arch-specific instruction decoder for all the instructions and add
 255  * them to the global instruction list.
 256  */
 257 static int decode_instructions(struct objtool_file *file)
 258 {
 259         struct section *sec;
 260         struct symbol *func;
 261         unsigned long offset;
 262         struct instruction *insn;
 263         int ret;
 264
 265         for_each_sec(file, sec) {
 266
 267                 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
 268                         continue;
 269
 270                 if (strcmp(sec->name, ".altinstr_replacement") &&
 271                     strcmp(sec->name, ".altinstr_aux") &&
 272                     strncmp(sec->name, ".discard.", 9))
 273                         sec->text = true;
 274
 275                 for (offset = 0; offset < sec->len; offset += insn->len) {
 276                         insn = malloc(sizeof(*insn));
 277                         if (!insn) {
 278                                 WARN("malloc failed");
 279                                 return -1;
 280                         }
 281                         memset(insn, 0, sizeof(*insn));
 282                         INIT_LIST_HEAD(&insn->alts);
 283                         clear_insn_state(&insn->state);
 284
 285                         insn->sec = sec;
 286                         insn->offset = offset;
 287
 288                         ret = arch_decode_instruction(file->elf, sec, offset,
 289                                                       sec->len - offset,
 290                                                       &insn->len, &insn->type,
 291                                                       &insn->immediate,
 292                                                       &insn->stack_op);
 293                         if (ret)
 294                                 goto err;
 295
 296                         if (!insn->type || insn->type > INSN_LAST) {
 297                                 WARN_FUNC("invalid instruction type %d",
 298                                           insn->sec, insn->offset, insn->type);
 299                                 ret = -1;
 300                                 goto err;
 301                         }
 302
 303                         hash_add(file->insn_hash, &insn->hash, insn->offset);
 304                         list_add_tail(&insn->list, &file->insn_list);
 305                 }
 306
 307                 list_for_each_entry(func, &sec->symbol_list, list) {
 308                         if (func->type != STT_FUNC)
 309                                 continue;
 310
 311                         if (!find_insn(file, sec, func->offset)) {
 312                                 WARN("%s(): can't find starting instruction",
 313                                      func->name);
 314                                 return -1;
 315                         }
 316
 317                         func_for_each_insn(file, func, insn)
 318                                 if (!insn->func)
 319                                         insn->func = func;
 320                 }
 321         }
 322
 323         return 0;
 324
 325 err:
 326         free(insn);
 327         return ret;
 328 }
 329
 330 /*
 331  * Mark "ud2" instructions and manually annotated dead ends.
 332  */
 333 static int add_dead_ends(struct objtool_file *file)
 334 {
 335         struct section *sec;
 336         struct rela *rela;
 337         struct instruction *insn;
 338         bool found;
 339
 340         /*
 341          * By default, "ud2" is a dead end unless otherwise annotated, because
 342          * GCC 7 inserts it for certain divide-by-zero cases.
 343          */
 344         for_each_insn(file, insn)
 345                 if (insn->type == INSN_BUG)
 346                         insn->dead_end = true;
 347
 348         /*
 349          * Check for manually annotated dead ends.
 350          */
 351         sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
 352         if (!sec)
 353                 goto reachable;
 354
 355         list_for_each_entry(rela, &sec->rela_list, list) {
 356                 if (rela->sym->type != STT_SECTION) {
 357                         WARN("unexpected relocation symbol type in %s", sec->name);
 358                         return -1;
 359                 }
 360                 insn = find_insn(file, rela->sym->sec, rela->addend);
 361                 if (insn)
 362                         insn = list_prev_entry(insn, list);
 363                 else if (rela->addend == rela->sym->sec->len) {
 364                         found = false;
 365                         list_for_each_entry_reverse(insn, &file->insn_list, list) {
 366                                 if (insn->sec == rela->sym->sec) {
 367                                         found = true;
 368                                         break;
 369                                 }
 370                         }
 371
 372                         if (!found) {
 373                                 WARN("can't find unreachable insn at %s+0x%x",
 374                                      rela->sym->sec->name, rela->addend);
 375                                 return -1;
 376                         }
 377                 } else {
 378                         WARN("can't find unreachable insn at %s+0x%x",
 379                              rela->sym->sec->name, rela->addend);
 380                         return -1;
 381                 }
 382
 383                 insn->dead_end = true;
 384         }
 385
 386 reachable:
 387         /*
 388          * These manually annotated reachable checks are needed for GCC 4.4,
 389          * where the Linux unreachable() macro isn't supported.  In that case
 390          * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
 391          * not a dead end.
 392          */
 393         sec = find_section_by_name(file->elf, ".rela.discard.reachable");
 394         if (!sec)
 395                 return 0;
 396
 397         list_for_each_entry(rela, &sec->rela_list, list) {
 398                 if (rela->sym->type != STT_SECTION) {
 399                         WARN("unexpected relocation symbol type in %s", sec->name);
 400                         return -1;
 401                 }
 402                 insn = find_insn(file, rela->sym->sec, rela->addend);
 403                 if (insn)
 404                         insn = list_prev_entry(insn, list);
 405                 else if (rela->addend == rela->sym->sec->len) {
 406                         found = false;
 407                         list_for_each_entry_reverse(insn, &file->insn_list, list) {
 408                                 if (insn->sec == rela->sym->sec) {
 409                                         found = true;
 410                                         break;
 411                                 }
 412                         }
 413
 414                         if (!found) {
 415                                 WARN("can't find reachable insn at %s+0x%x",
 416                                      rela->sym->sec->name, rela->addend);
 417                                 return -1;
 418                         }
 419                 } else {
 420                         WARN("can't find reachable insn at %s+0x%x",
 421                              rela->sym->sec->name, rela->addend);
 422                         return -1;
 423                 }
 424
 425                 insn->dead_end = false;
 426         }
 427
 428         return 0;
 429 }
 430
 431 /*
 432  * Warnings shouldn't be reported for ignored functions.
 433  */
 434 static void add_ignores(struct objtool_file *file)
 435 {
 436         struct instruction *insn;
 437         struct section *sec;
 438         struct symbol *func;
 439
 440         for_each_sec(file, sec) {
 441                 list_for_each_entry(func, &sec->symbol_list, list) {
 442                         if (func->type != STT_FUNC)
 443                                 continue;
 444
 445                         if (!ignore_func(file, func))
 446                                 continue;
 447
 448                         func_for_each_insn_all(file, func, insn)
 449                                 insn->ignore = true;
 450                 }
 451         }
 452 }
 453
 454 /*
 455  * FIXME: For now, just ignore any alternatives which add retpolines.  This is
 456  * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
 457  * But it at least allows objtool to understand the control flow *around* the
 458  * retpoline.
 459  */
 460 static int add_nospec_ignores(struct objtool_file *file)
 461 {
 462         struct section *sec;
 463         struct rela *rela;
 464         struct instruction *insn;
 465
 466         sec = find_section_by_name(file->elf, ".rela.discard.nospec");
 467         if (!sec)
 468                 return 0;
 469
 470         list_for_each_entry(rela, &sec->rela_list, list) {
 471                 if (rela->sym->type != STT_SECTION) {
 472                         WARN("unexpected relocation symbol type in %s", sec->name);
 473                         return -1;
 474                 }
 475
 476                 insn = find_insn(file, rela->sym->sec, rela->addend);
 477                 if (!insn) {
 478                         WARN("bad .discard.nospec entry");
 479                         return -1;
 480                 }
 481
 482                 insn->ignore_alts = true;
 483         }
 484
 485         return 0;
 486 }
 487
 488 /*
 489  * Find the destination instructions for all jumps.
 490  */
 491 static int add_jump_destinations(struct objtool_file *file)
 492 {
 493         struct instruction *insn;
 494         struct rela *rela;
 495         struct section *dest_sec;
 496         unsigned long dest_off;
 497
 498         for_each_insn(file, insn) {
 499                 if (insn->type != INSN_JUMP_CONDITIONAL &&
 500                     insn->type != INSN_JUMP_UNCONDITIONAL)
 501                         continue;
 502
 503                 if (insn->ignore)
 504                         continue;
 505
 506                 rela = find_rela_by_dest_range(insn->sec, insn->offset,
 507                                                insn->len);
 508                 if (!rela) {
 509                         dest_sec = insn->sec;
 510                         dest_off = insn->offset + insn->len + insn->immediate;
 511                 } else if (rela->sym->type == STT_SECTION) {
 512                         dest_sec = rela->sym->sec;
 513                         dest_off = rela->addend + 4;
 514                 } else if (rela->sym->sec->idx) {
 515                         dest_sec = rela->sym->sec;
 516                         dest_off = rela->sym->sym.st_value + rela->addend + 4;
 517                 } else if (strstr(rela->sym->name, "_indirect_thunk_")) {
 518                         /*
 519                          * Retpoline jumps are really dynamic jumps in
 520                          * disguise, so convert them accordingly.
 521                          */
 522                         insn->type = INSN_JUMP_DYNAMIC;
 523                         insn->retpoline_safe = true;
 524                         continue;
 525                 } else {
 526                         /* sibling call */
 527                         insn->jump_dest = 0;
 528                         continue;
 529                 }
 530
 531                 insn->jump_dest = find_insn(file, dest_sec, dest_off);
 532                 if (!insn->jump_dest) {
 533
 534                         /*
 535                          * This is a special case where an alt instruction
 536                          * jumps past the end of the section.  These are
 537                          * handled later in handle_group_alt().
 538                          */
 539                         if (!strcmp(insn->sec->name, ".altinstr_replacement"))
 540                                 continue;
 541
 542                         WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
 543                                   insn->sec, insn->offset, dest_sec->name,
 544                                   dest_off);
 545                         return -1;
 546                 }
 547
 548                 /*
 549                  * For GCC 8+, create parent/child links for any cold
 550                  * subfunctions.  This is _mostly_ redundant with a similar
 551                  * initialization in read_symbols().
 552                  *
 553                  * If a function has aliases, we want the *first* such function
 554                  * in the symbol table to be the subfunction's parent.  In that
 555                  * case we overwrite the initialization done in read_symbols().
 556                  *
 557                  * However this code can't completely replace the
 558                  * read_symbols() code because this doesn't detect the case
 559                  * where the parent function's only reference to a subfunction
 560                  * is through a switch table.
 561                  */
 562                 if (insn->func && insn->jump_dest->func &&
 563                     insn->func != insn->jump_dest->func &&
 564                     !strstr(insn->func->name, ".cold.") &&
 565                     strstr(insn->jump_dest->func->name, ".cold.")) {
 566                         insn->func->cfunc = insn->jump_dest->func;
 567                         insn->jump_dest->func->pfunc = insn->func;
 568                 }
 569         }
 570
 571         return 0;
 572 }
 573
 574 /*
 575  * Find the destination instructions for all calls.
 576  */
 577 static int add_call_destinations(struct objtool_file *file)
 578 {
 579         struct instruction *insn;
 580         unsigned long dest_off;
 581         struct rela *rela;
 582
 583         for_each_insn(file, insn) {
 584                 if (insn->type != INSN_CALL)
 585                         continue;
 586
 587                 rela = find_rela_by_dest_range(insn->sec, insn->offset,
 588                                                insn->len);
 589                 if (!rela) {
 590                         dest_off = insn->offset + insn->len + insn->immediate;
 591                         insn->call_dest = find_symbol_by_offset(insn->sec,
 592                                                                 dest_off);
 593
 594                         if (!insn->call_dest && !insn->ignore) {
 595                                 WARN_FUNC("unsupported intra-function call",
 596                                           insn->sec, insn->offset);
 597                                 if (retpoline)
 598                                         WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE.");
 599                                 return -1;
 600                         }
 601
 602                 } else if (rela->sym->type == STT_SECTION) {
 603                         insn->call_dest = find_symbol_by_offset(rela->sym->sec,
 604                                                                 rela->addend+4);
 605                         if (!insn->call_dest ||
 606                             insn->call_dest->type != STT_FUNC) {
 607                                 WARN_FUNC("can't find call dest symbol at %s+0x%x",
 608                                           insn->sec, insn->offset,
 609                                           rela->sym->sec->name,
 610                                           rela->addend + 4);
 611                                 return -1;
 612                         }
 613                 } else
 614                         insn->call_dest = rela->sym;
 615         }
 616
 617         return 0;
 618 }
 619
 620 /*
 621  * The .alternatives section requires some extra special care, over and above
 622  * what other special sections require:
 623  *
 624  * 1. Because alternatives are patched in-place, we need to insert a fake jump
 625  *    instruction at the end so that validate_branch() skips all the original
 626  *    replaced instructions when validating the new instruction path.
 627  *
 628  * 2. An added wrinkle is that the new instruction length might be zero.  In
 629  *    that case the old instructions are replaced with noops.  We simulate that
 630  *    by creating a fake jump as the only new instruction.
 631  *
 632  * 3. In some cases, the alternative section includes an instruction which
 633  *    conditionally jumps to the _end_ of the entry.  We have to modify these
 634  *    jumps' destinations to point back to .text rather than the end of the
 635  *    entry in .altinstr_replacement.
 636  *
 637  * 4. It has been requested that we don't validate the !POPCNT feature path
 638  *    which is a "very very small percentage of machines".
 639  */
 640 static int handle_group_alt(struct objtool_file *file,
 641                             struct special_alt *special_alt,
 642                             struct instruction *orig_insn,
 643                             struct instruction **new_insn)
 644 {
 645         struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL;
 646         unsigned long dest_off;
 647
 648         last_orig_insn = NULL;
 649         insn = orig_insn;
 650         sec_for_each_insn_from(file, insn) {
 651                 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
 652                         break;
 653
 654                 if (special_alt->skip_orig)
 655                         insn->type = INSN_NOP;
 656
 657                 insn->alt_group = true;
 658                 last_orig_insn = insn;
 659         }
 660
 661         if (next_insn_same_sec(file, last_orig_insn)) {
 662                 fake_jump = malloc(sizeof(*fake_jump));
 663                 if (!fake_jump) {
 664                         WARN("malloc failed");
 665                         return -1;
 666                 }
 667                 memset(fake_jump, 0, sizeof(*fake_jump));
 668                 INIT_LIST_HEAD(&fake_jump->alts);
 669                 clear_insn_state(&fake_jump->state);
 670
 671                 fake_jump->sec = special_alt->new_sec;
 672                 fake_jump->offset = -1;
 673                 fake_jump->type = INSN_JUMP_UNCONDITIONAL;
 674                 fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
 675                 fake_jump->ignore = true;
 676         }
 677
 678         if (!special_alt->new_len) {
 679                 if (!fake_jump) {
 680                         WARN("%s: empty alternative at end of section",
 681                              special_alt->orig_sec->name);
 682                         return -1;
 683                 }
 684
 685                 *new_insn = fake_jump;
 686                 return 0;
 687         }
 688
 689         last_new_insn = NULL;
 690         insn = *new_insn;
 691         sec_for_each_insn_from(file, insn) {
 692                 if (insn->offset >= special_alt->new_off + special_alt->new_len)
 693                         break;
 694
 695                 last_new_insn = insn;
 696
 697                 insn->ignore = orig_insn->ignore_alts;
 698
 699                 if (insn->type != INSN_JUMP_CONDITIONAL &&
 700                     insn->type != INSN_JUMP_UNCONDITIONAL)
 701                         continue;
 702
 703                 if (!insn->immediate)
 704                         continue;
 705
 706                 dest_off = insn->offset + insn->len + insn->immediate;
 707                 if (dest_off == special_alt->new_off + special_alt->new_len) {
 708                         if (!fake_jump) {
 709                                 WARN("%s: alternative jump to end of section",
 710                                      special_alt->orig_sec->name);
 711                                 return -1;
 712                         }
 713                         insn->jump_dest = fake_jump;
 714                 }
 715
 716                 if (!insn->jump_dest) {
 717                         WARN_FUNC("can't find alternative jump destination",
 718                                   insn->sec, insn->offset);
 719                         return -1;
 720                 }
 721         }
 722
 723         if (!last_new_insn) {
 724                 WARN_FUNC("can't find last new alternative instruction",
 725                           special_alt->new_sec, special_alt->new_off);
 726                 return -1;
 727         }
 728
 729         if (fake_jump)
 730                 list_add(&fake_jump->list, &last_new_insn->list);
 731
 732         return 0;
 733 }
 734
 735 /*
 736  * A jump table entry can either convert a nop to a jump or a jump to a nop.
 737  * If the original instruction is a jump, make the alt entry an effective nop
 738  * by just skipping the original instruction.
 739  */
 740 static int handle_jump_alt(struct objtool_file *file,
 741                            struct special_alt *special_alt,
 742                            struct instruction *orig_insn,
 743                            struct instruction **new_insn)
 744 {
 745         if (orig_insn->type == INSN_NOP)
 746                 return 0;
 747
 748         if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) {
 749                 WARN_FUNC("unsupported instruction at jump label",
 750                           orig_insn->sec, orig_insn->offset);
 751                 return -1;
 752         }
 753
 754         *new_insn = list_next_entry(orig_insn, list);
 755         return 0;
 756 }
 757
 758 /*
 759  * Read all the special sections which have alternate instructions which can be
 760  * patched in or redirected to at runtime.  Each instruction having alternate
 761  * instruction(s) has them added to its insn->alts list, which will be
 762  * traversed in validate_branch().
 763  */
 764 static int add_special_section_alts(struct objtool_file *file)
 765 {
 766         struct list_head special_alts;
 767         struct instruction *orig_insn, *new_insn;
 768         struct special_alt *special_alt, *tmp;
 769         struct alternative *alt;
 770         int ret;
 771
 772         ret = special_get_alts(file->elf, &special_alts);
 773         if (ret)
 774                 return ret;
 775
 776         list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
 777
 778                 orig_insn = find_insn(file, special_alt->orig_sec,
 779                                       special_alt->orig_off);
 780                 if (!orig_insn) {
 781                         WARN_FUNC("special: can't find orig instruction",
 782                                   special_alt->orig_sec, special_alt->orig_off);
 783                         ret = -1;
 784                         goto out;
 785                 }
 786
 787                 new_insn = NULL;
 788                 if (!special_alt->group || special_alt->new_len) {
 789                         new_insn = find_insn(file, special_alt->new_sec,
 790                                              special_alt->new_off);
 791                         if (!new_insn) {
 792                                 WARN_FUNC("special: can't find new instruction",
 793                                           special_alt->new_sec,
 794                                           special_alt->new_off);
 795                                 ret = -1;
 796                                 goto out;
 797                         }
 798                 }
 799
 800                 if (special_alt->group) {
 801                         ret = handle_group_alt(file, special_alt, orig_insn,
 802                                                &new_insn);
 803                         if (ret)
 804                                 goto out;
 805                 } else if (special_alt->jump_or_nop) {
 806                         ret = handle_jump_alt(file, special_alt, orig_insn,
 807                                               &new_insn);
 808                         if (ret)
 809                                 goto out;
 810                 }
 811
 812                 alt = malloc(sizeof(*alt));
 813                 if (!alt) {
 814                         WARN("malloc failed");
 815                         ret = -1;
 816                         goto out;
 817                 }
 818
 819                 alt->insn = new_insn;
 820                 list_add_tail(&alt->list, &orig_insn->alts);
 821
 822                 list_del(&special_alt->list);
 823                 free(special_alt);
 824         }
 825
 826 out:
 827         return ret;
 828 }
 829
 830 static int add_switch_table(struct objtool_file *file, struct instruction *insn,
 831                             struct rela *table, struct rela *next_table)
 832 {
 833         struct rela *rela = table;
 834         struct instruction *alt_insn;
 835         struct alternative *alt;
 836         struct symbol *pfunc = insn->func->pfunc;
 837         unsigned int prev_offset = 0;
 838
 839         list_for_each_entry_from(rela, &table->rela_sec->rela_list, list) {
 840                 if (rela == next_table)
 841                         break;
 842
 843                 /* Make sure the switch table entries are consecutive: */
 844                 if (prev_offset && rela->offset != prev_offset + 8)
 845                         break;
 846
 847                 /* Detect function pointers from contiguous objects: */
 848                 if (rela->sym->sec == pfunc->sec &&
 849                     rela->addend == pfunc->offset)
 850                         break;
 851
 852                 alt_insn = find_insn(file, rela->sym->sec, rela->addend);
 853                 if (!alt_insn)
 854                         break;
 855
 856                 /* Make sure the jmp dest is in the function or subfunction: */
 857                 if (alt_insn->func->pfunc != pfunc)
 858                         break;
 859
 860                 alt = malloc(sizeof(*alt));
 861                 if (!alt) {
 862                         WARN("malloc failed");
 863                         return -1;
 864                 }
 865
 866                 alt->insn = alt_insn;
 867                 list_add_tail(&alt->list, &insn->alts);
 868                 prev_offset = rela->offset;
 869         }
 870
 871         if (!prev_offset) {
 872                 WARN_FUNC("can't find switch jump table",
 873                           insn->sec, insn->offset);
 874                 return -1;
 875         }
 876
 877         return 0;
 878 }
 879
 880 /*
 881  * find_switch_table() - Given a dynamic jump, find the switch jump table in
 882  * .rodata associated with it.
 883  *
 884  * There are 3 basic patterns:
 885  *
 886  * 1. jmpq *[rodata addr](,%reg,8)
 887  *
 888  *    This is the most common case by far.  It jumps to an address in a simple
 889  *    jump table which is stored in .rodata.
 890  *
 891  * 2. jmpq *[rodata addr](%rip)
 892  *
 893  *    This is caused by a rare GCC quirk, currently only seen in three driver
 894  *    functions in the kernel, only with certain obscure non-distro configs.
 895  *
 896  *    As part of an optimization, GCC makes a copy of an existing switch jump
 897  *    table, modifies it, and then hard-codes the jump (albeit with an indirect
 898  *    jump) to use a single entry in the table.  The rest of the jump table and
 899  *    some of its jump targets remain as dead code.
 900  *
 901  *    In such a case we can just crudely ignore all unreachable instruction
 902  *    warnings for the entire object file.  Ideally we would just ignore them
 903  *    for the function, but that would require redesigning the code quite a
 904  *    bit.  And honestly that's just not worth doing: unreachable instruction
 905  *    warnings are of questionable value anyway, and this is such a rare issue.
 906  *
 907  * 3. mov [rodata addr],%reg1
 908  *    ... some instructions ...
 909  *    jmpq *(%reg1,%reg2,8)
 910  *
 911  *    This is a fairly uncommon pattern which is new for GCC 6.  As of this
 912  *    writing, there are 11 occurrences of it in the allmodconfig kernel.
 913  *
 914  *    As of GCC 7 there are quite a few more of these and the 'in between' code
 915  *    is significant. Esp. with KASAN enabled some of the code between the mov
 916  *    and jmpq uses .rodata itself, which can confuse things.
 917  *
 918  *    TODO: Once we have DWARF CFI and smarter instruction decoding logic,
 919  *    ensure the same register is used in the mov and jump instructions.
 920  *
 921  *    NOTE: RETPOLINE made it harder still to decode dynamic jumps.
 922  */
 923 static struct rela *find_switch_table(struct objtool_file *file,
 924                                       struct symbol *func,
 925                                       struct instruction *insn)
 926 {
 927         struct rela *text_rela, *rodata_rela;
 928         struct instruction *orig_insn = insn;
 929         struct section *rodata_sec;
 930         unsigned long table_offset;
 931
 932         /*
 933          * Backward search using the @first_jump_src links, these help avoid
 934          * much of the 'in between' code. Which avoids us getting confused by
 935          * it.
 936          */
 937         for (;
 938              &insn->list != &file->insn_list &&
 939              insn->sec == func->sec &&
 940              insn->offset >= func->offset;
 941
 942              insn = insn->first_jump_src ?: list_prev_entry(insn, list)) {
 943
 944                 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
 945                         break;
 946
 947                 /* allow small jumps within the range */
 948                 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
 949                     insn->jump_dest &&
 950                     (insn->jump_dest->offset <= insn->offset ||
 951                      insn->jump_dest->offset > orig_insn->offset))
 952                     break;
 953
 954                 /* look for a relocation which references .rodata */
 955                 text_rela = find_rela_by_dest_range(insn->sec, insn->offset,
 956                                                     insn->len);
 957                 if (!text_rela || text_rela->sym->type != STT_SECTION ||
 958                     !text_rela->sym->sec->rodata)
 959                         continue;
 960
 961                 table_offset = text_rela->addend;
 962                 rodata_sec = text_rela->sym->sec;
 963
 964                 if (text_rela->type == R_X86_64_PC32)
 965                         table_offset += 4;
 966
 967                 /*
 968                  * Make sure the .rodata address isn't associated with a
 969                  * symbol.  gcc jump tables are anonymous data.
 970                  */
 971                 if (find_symbol_containing(rodata_sec, table_offset))
 972                         continue;
 973
 974                 rodata_rela = find_rela_by_dest(rodata_sec, table_offset);
 975                 if (rodata_rela) {
 976                         /*
 977                          * Use of RIP-relative switch jumps is quite rare, and
 978                          * indicates a rare GCC quirk/bug which can leave dead
 979                          * code behind.
 980                          */
 981                         if (text_rela->type == R_X86_64_PC32)
 982                                 file->ignore_unreachables = true;
 983
 984                         return rodata_rela;
 985                 }
 986         }
 987
 988         return NULL;
 989 }
 990
 991
 992 static int add_func_switch_tables(struct objtool_file *file,
 993                                   struct symbol *func)
 994 {
 995         struct instruction *insn, *last = NULL, *prev_jump = NULL;
 996         struct rela *rela, *prev_rela = NULL;
 997         int ret;
 998
 999         func_for_each_insn_all(file, func, insn) {
1000                 if (!last)
1001                         last = insn;
1002
1003                 /*
1004                  * Store back-pointers for unconditional forward jumps such
1005                  * that find_switch_table() can back-track using those and
1006                  * avoid some potentially confusing code.
1007                  */
1008                 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
1009                     insn->offset > last->offset &&
1010                     insn->jump_dest->offset > insn->offset &&
1011                     !insn->jump_dest->first_jump_src) {
1012
1013                         insn->jump_dest->first_jump_src = insn;
1014                         last = insn->jump_dest;
1015                 }
1016
1017                 if (insn->type != INSN_JUMP_DYNAMIC)
1018                         continue;
1019
1020                 rela = find_switch_table(file, func, insn);
1021                 if (!rela)
1022                         continue;
1023
1024                 /*
1025                  * We found a switch table, but we don't know yet how big it
1026                  * is.  Don't add it until we reach the end of the function or
1027                  * the beginning of another switch table in the same function.
1028                  */
1029                 if (prev_jump) {
1030                         ret = add_switch_table(file, prev_jump, prev_rela, rela);
1031                         if (ret)
1032                                 return ret;
1033                 }
1034
1035                 prev_jump = insn;
1036                 prev_rela = rela;
1037         }
1038
1039         if (prev_jump) {
1040                 ret = add_switch_table(file, prev_jump, prev_rela, NULL);
1041                 if (ret)
1042                         return ret;
1043         }
1044
1045         return 0;
1046 }
1047
1048 /*
1049  * For some switch statements, gcc generates a jump table in the .rodata
1050  * section which contains a list of addresses within the function to jump to.
1051  * This finds these jump tables and adds them to the insn->alts lists.
1052  */
1053 static int add_switch_table_alts(struct objtool_file *file)
1054 {
1055         struct section *sec;
1056         struct symbol *func;
1057         int ret;
1058
1059         if (!file->rodata)
1060                 return 0;
1061
1062         for_each_sec(file, sec) {
1063                 list_for_each_entry(func, &sec->symbol_list, list) {
1064                         if (func->type != STT_FUNC)
1065                                 continue;
1066
1067                         ret = add_func_switch_tables(file, func);
1068                         if (ret)
1069                                 return ret;
1070                 }
1071         }
1072
1073         return 0;
1074 }
1075
1076 static int read_unwind_hints(struct objtool_file *file)
1077 {
1078         struct section *sec, *relasec;
1079         struct rela *rela;
1080         struct unwind_hint *hint;
1081         struct instruction *insn;
1082         struct cfi_reg *cfa;
1083         int i;
1084
1085         sec = find_section_by_name(file->elf, ".discard.unwind_hints");
1086         if (!sec)
1087                 return 0;
1088
1089         relasec = sec->rela;
1090         if (!relasec) {
1091                 WARN("missing .rela.discard.unwind_hints section");
1092                 return -1;
1093         }
1094
1095         if (sec->len % sizeof(struct unwind_hint)) {
1096                 WARN("struct unwind_hint size mismatch");
1097                 return -1;
1098         }
1099
1100         file->hints = true;
1101
1102         for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) {
1103                 hint = (struct unwind_hint *)sec->data->d_buf + i;
1104
1105                 rela = find_rela_by_dest(sec, i * sizeof(*hint));
1106                 if (!rela) {
1107                         WARN("can't find rela for unwind_hints[%d]", i);
1108                         return -1;
1109                 }
1110
1111                 insn = find_insn(file, rela->sym->sec, rela->addend);
1112                 if (!insn) {
1113                         WARN("can't find insn for unwind_hints[%d]", i);
1114                         return -1;
1115                 }
1116
1117                 cfa = &insn->state.cfa;
1118
1119                 if (hint->type == UNWIND_HINT_TYPE_SAVE) {
1120                         insn->save = true;
1121                         continue;
1122
1123                 } else if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
1124                         insn->restore = true;
1125                         insn->hint = true;
1126                         continue;
1127                 }
1128
1129                 insn->hint = true;
1130
1131                 switch (hint->sp_reg) {
1132                 case ORC_REG_UNDEFINED:
1133                         cfa->base = CFI_UNDEFINED;
1134                         break;
1135                 case ORC_REG_SP:
1136                         cfa->base = CFI_SP;
1137                         break;
1138                 case ORC_REG_BP:
1139                         cfa->base = CFI_BP;
1140                         break;
1141                 case ORC_REG_SP_INDIRECT:
1142                         cfa->base = CFI_SP_INDIRECT;
1143                         break;
1144                 case ORC_REG_R10:
1145                         cfa->base = CFI_R10;
1146                         break;
1147                 case ORC_REG_R13:
1148                         cfa->base = CFI_R13;
1149                         break;
1150                 case ORC_REG_DI:
1151                         cfa->base = CFI_DI;
1152                         break;
1153                 case ORC_REG_DX:
1154                         cfa->base = CFI_DX;
1155                         break;
1156                 default:
1157                         WARN_FUNC("unsupported unwind_hint sp base reg %d",
1158                                   insn->sec, insn->offset, hint->sp_reg);
1159                         return -1;
1160                 }
1161
1162                 cfa->offset = hint->sp_offset;
1163                 insn->state.type = hint->type;
1164                 insn->state.end = hint->end;
1165         }
1166
1167         return 0;
1168 }
1169
1170 static int read_retpoline_hints(struct objtool_file *file)
1171 {
1172         struct section *sec;
1173         struct instruction *insn;
1174         struct rela *rela;
1175
1176         sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
1177         if (!sec)
1178                 return 0;
1179
1180         list_for_each_entry(rela, &sec->rela_list, list) {
1181                 if (rela->sym->type != STT_SECTION) {
1182                         WARN("unexpected relocation symbol type in %s", sec->name);
1183                         return -1;
1184                 }
1185
1186                 insn = find_insn(file, rela->sym->sec, rela->addend);
1187                 if (!insn) {
1188                         WARN("bad .discard.retpoline_safe entry");
1189                         return -1;
1190                 }
1191
1192                 if (insn->type != INSN_JUMP_DYNAMIC &&
1193                     insn->type != INSN_CALL_DYNAMIC) {
1194                         WARN_FUNC("retpoline_safe hint not an indirect jump/call",
1195                                   insn->sec, insn->offset);
1196                         return -1;
1197                 }
1198
1199                 insn->retpoline_safe = true;
1200         }
1201
1202         return 0;
1203 }
1204
1205 static void mark_rodata(struct objtool_file *file)
1206 {
1207         struct section *sec;
1208         bool found = false;
1209
1210         /*
1211          * This searches for the .rodata section or multiple .rodata.func_name
1212          * sections if -fdata-sections is being used. The .str.1.1 and .str.1.8
1213          * rodata sections are ignored as they don't contain jump tables.
1214          */
1215         for_each_sec(file, sec) {
1216                 if (!strncmp(sec->name, ".rodata", 7) &&
1217                     !strstr(sec->name, ".str1.")) {
1218                         sec->rodata = true;
1219                         found = true;
1220                 }
1221         }
1222
1223         file->rodata = found;
1224 }
1225
1226 static int decode_sections(struct objtool_file *file)
1227 {
1228         int ret;
1229
1230         mark_rodata(file);
1231
1232         ret = decode_instructions(file);
1233         if (ret)
1234                 return ret;
1235
1236         ret = add_dead_ends(file);
1237         if (ret)
1238                 return ret;
1239
1240         add_ignores(file);
1241
1242         ret = add_nospec_ignores(file);
1243         if (ret)
1244                 return ret;
1245
1246         ret = add_jump_destinations(file);
1247         if (ret)
1248                 return ret;
1249
1250         ret = add_special_section_alts(file);
1251         if (ret)
1252                 return ret;
1253
1254         ret = add_call_destinations(file);
1255         if (ret)
1256                 return ret;
1257
1258         ret = add_switch_table_alts(file);
1259         if (ret)
1260                 return ret;
1261
1262         ret = read_unwind_hints(file);
1263         if (ret)
1264                 return ret;
1265
1266         ret = read_retpoline_hints(file);
1267         if (ret)
1268                 return ret;
1269
1270         return 0;
1271 }
1272
1273 static bool is_fentry_call(struct instruction *insn)
1274 {
1275         if (insn->type == INSN_CALL &&
1276             insn->call_dest->type == STT_NOTYPE &&
1277             !strcmp(insn->call_dest->name, "__fentry__"))
1278                 return true;
1279
1280         return false;
1281 }
1282
1283 static bool has_modified_stack_frame(struct insn_state *state)
1284 {
1285         int i;
1286
1287         if (state->cfa.base != initial_func_cfi.cfa.base ||
1288             state->cfa.offset != initial_func_cfi.cfa.offset ||
1289             state->stack_size != initial_func_cfi.cfa.offset ||
1290             state->drap)
1291                 return true;
1292
1293         for (i = 0; i < CFI_NUM_REGS; i++)
1294                 if (state->regs[i].base != initial_func_cfi.regs[i].base ||
1295                     state->regs[i].offset != initial_func_cfi.regs[i].offset)
1296                         return true;
1297
1298         return false;
1299 }
1300
1301 static bool has_valid_stack_frame(struct insn_state *state)
1302 {
1303         if (state->cfa.base == CFI_BP && state->regs[CFI_BP].base == CFI_CFA &&
1304             state->regs[CFI_BP].offset == -16)
1305                 return true;
1306
1307         if (state->drap && state->regs[CFI_BP].base == CFI_BP)
1308                 return true;
1309
1310         return false;
1311 }
1312
1313 static int update_insn_state_regs(struct instruction *insn, struct insn_state *state)
1314 {
1315         struct cfi_reg *cfa = &state->cfa;
1316         struct stack_op *op = &insn->stack_op;
1317
1318         if (cfa->base != CFI_SP)
1319                 return 0;
1320
1321         /* push */
1322         if (op->dest.type == OP_DEST_PUSH)
1323                 cfa->offset += 8;
1324
1325         /* pop */
1326         if (op->src.type == OP_SRC_POP)
1327                 cfa->offset -= 8;
1328
1329         /* add immediate to sp */
1330         if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
1331             op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
1332                 cfa->offset -= op->src.offset;
1333
1334         return 0;
1335 }
1336
1337 static void save_reg(struct insn_state *state, unsigned char reg, int base,
1338                      int offset)
1339 {
1340         if (arch_callee_saved_reg(reg) &&
1341             state->regs[reg].base == CFI_UNDEFINED) {
1342                 state->regs[reg].base = base;
1343                 state->regs[reg].offset = offset;
1344         }
1345 }
1346
1347 static void restore_reg(struct insn_state *state, unsigned char reg)
1348 {
1349         state->regs[reg].base = CFI_UNDEFINED;
1350         state->regs[reg].offset = 0;
1351 }
1352
1353 /*
1354  * A note about DRAP stack alignment:
1355  *
1356  * GCC has the concept of a DRAP register, which is used to help keep track of
1357  * the stack pointer when aligning the stack.  r10 or r13 is used as the DRAP
1358  * register.  The typical DRAP pattern is:
1359  *
1360  *   4c 8d 54 24 08             lea    0x8(%rsp),%r10
1361  *   48 83 e4 c0                and    $0xffffffffffffffc0,%rsp
1362  *   41 ff 72 f8                pushq  -0x8(%r10)
1363  *   55                         push   %rbp
1364  *   48 89 e5                   mov    %rsp,%rbp
1365  *                              (more pushes)
1366  *   41 52                      push   %r10
1367  *                              ...
1368  *   41 5a                      pop    %r10
1369  *                              (more pops)
1370  *   5d                         pop    %rbp
1371  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
1372  *   c3                         retq
1373  *
1374  * There are some variations in the epilogues, like:
1375  *
1376  *   5b                         pop    %rbx
1377  *   41 5a                      pop    %r10
1378  *   41 5c                      pop    %r12
1379  *   41 5d                      pop    %r13
1380  *   41 5e                      pop    %r14
1381  *   c9                         leaveq
1382  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
1383  *   c3                         retq
1384  *
1385  * and:
1386  *
1387  *   4c 8b 55 e8                mov    -0x18(%rbp),%r10
1388  *   48 8b 5d e0                mov    -0x20(%rbp),%rbx
1389  *   4c 8b 65 f0                mov    -0x10(%rbp),%r12
1390  *   4c 8b 6d f8                mov    -0x8(%rbp),%r13
1391  *   c9                         leaveq
1392  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
1393  *   c3                         retq
1394  *
1395  * Sometimes r13 is used as the DRAP register, in which case it's saved and
1396  * restored beforehand:
1397  *
1398  *   41 55                      push   %r13
1399  *   4c 8d 6c 24 10             lea    0x10(%rsp),%r13
1400  *   48 83 e4 f0                and    $0xfffffffffffffff0,%rsp
1401  *                              ...
1402  *   49 8d 65 f0                lea    -0x10(%r13),%rsp
1403  *   41 5d                      pop    %r13
1404  *   c3                         retq
1405  */
1406 static int update_insn_state(struct instruction *insn, struct insn_state *state)
1407 {
1408         struct stack_op *op = &insn->stack_op;
1409         struct cfi_reg *cfa = &state->cfa;
1410         struct cfi_reg *regs = state->regs;
1411
1412         /* stack operations don't make sense with an undefined CFA */
1413         if (cfa->base == CFI_UNDEFINED) {
1414                 if (insn->func) {
1415                         WARN_FUNC("undefined stack state", insn->sec, insn->offset);
1416                         return -1;
1417                 }
1418                 return 0;
1419         }
1420
1421         if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET)
1422                 return update_insn_state_regs(insn, state);
1423
1424         switch (op->dest.type) {
1425
1426         case OP_DEST_REG:
1427                 switch (op->src.type) {
1428
1429                 case OP_SRC_REG:
1430                         if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
1431                             cfa->base == CFI_SP &&
1432                             regs[CFI_BP].base == CFI_CFA &&
1433                             regs[CFI_BP].offset == -cfa->offset) {
1434
1435                                 /* mov %rsp, %rbp */
1436                                 cfa->base = op->dest.reg;
1437                                 state->bp_scratch = false;
1438                         }
1439
1440                         else if (op->src.reg == CFI_SP &&
1441                                  op->dest.reg == CFI_BP && state->drap) {
1442
1443                                 /* drap: mov %rsp, %rbp */
1444                                 regs[CFI_BP].base = CFI_BP;
1445                                 regs[CFI_BP].offset = -state->stack_size;
1446                                 state->bp_scratch = false;
1447                         }
1448
1449                         else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
1450
1451                                 /*
1452                                  * mov %rsp, %reg
1453                                  *
1454                                  * This is needed for the rare case where GCC
1455                                  * does:
1456                                  *
1457                                  *   mov    %rsp, %rax
1458                                  *   ...
1459                                  *   mov    %rax, %rsp
1460                                  */
1461                                 state->vals[op->dest.reg].base = CFI_CFA;
1462                                 state->vals[op->dest.reg].offset = -state->stack_size;
1463                         }
1464
1465                         else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
1466                                  cfa->base == CFI_BP) {
1467
1468                                 /*
1469                                  * mov %rbp, %rsp
1470                                  *
1471                                  * Restore the original stack pointer (Clang).
1472                                  */
1473                                 state->stack_size = -state->regs[CFI_BP].offset;
1474                         }
1475
1476                         else if (op->dest.reg == cfa->base) {
1477
1478                                 /* mov %reg, %rsp */
1479                                 if (cfa->base == CFI_SP &&
1480                                     state->vals[op->src.reg].base == CFI_CFA) {
1481
1482                                         /*
1483                                          * This is needed for the rare case
1484                                          * where GCC does something dumb like:
1485                                          *
1486                                          *   lea    0x8(%rsp), %rcx
1487                                          *   ...
1488                                          *   mov    %rcx, %rsp
1489                                          */
1490                                         cfa->offset = -state->vals[op->src.reg].offset;
1491                                         state->stack_size = cfa->offset;
1492
1493                                 } else {
1494                                         cfa->base = CFI_UNDEFINED;
1495                                         cfa->offset = 0;
1496                                 }
1497                         }
1498
1499                         break;
1500
1501                 case OP_SRC_ADD:
1502                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
1503
1504                                 /* add imm, %rsp */
1505                                 state->stack_size -= op->src.offset;
1506                                 if (cfa->base == CFI_SP)
1507                                         cfa->offset -= op->src.offset;
1508                                 break;
1509                         }
1510
1511                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
1512
1513                                 /* lea disp(%rbp), %rsp */
1514                                 state->stack_size = -(op->src.offset + regs[CFI_BP].offset);
1515                                 break;
1516                         }
1517
1518                         if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
1519
1520                                 /* drap: lea disp(%rsp), %drap */
1521                                 state->drap_reg = op->dest.reg;
1522
1523                                 /*
1524                                  * lea disp(%rsp), %reg
1525                                  *
1526                                  * This is needed for the rare case where GCC
1527                                  * does something dumb like:
1528                                  *
1529                                  *   lea    0x8(%rsp), %rcx
1530                                  *   ...
1531                                  *   mov    %rcx, %rsp
1532                                  */
1533                                 state->vals[op->dest.reg].base = CFI_CFA;
1534                                 state->vals[op->dest.reg].offset = \
1535                                         -state->stack_size + op->src.offset;
1536
1537                                 break;
1538                         }
1539
1540                         if (state->drap && op->dest.reg == CFI_SP &&
1541                             op->src.reg == state->drap_reg) {
1542
1543                                  /* drap: lea disp(%drap), %rsp */
1544                                 cfa->base = CFI_SP;
1545                                 cfa->offset = state->stack_size = -op->src.offset;
1546                                 state->drap_reg = CFI_UNDEFINED;
1547                                 state->drap = false;
1548                                 break;
1549                         }
1550
1551                         if (op->dest.reg == state->cfa.base) {
1552                                 WARN_FUNC("unsupported stack register modification",
1553                                           insn->sec, insn->offset);
1554                                 return -1;
1555                         }
1556
1557                         break;
1558
1559                 case OP_SRC_AND:
1560                         if (op->dest.reg != CFI_SP ||
1561                             (state->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
1562                             (state->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
1563                                 WARN_FUNC("unsupported stack pointer realignment",
1564                                           insn->sec, insn->offset);
1565                                 return -1;
1566                         }
1567
1568                         if (state->drap_reg != CFI_UNDEFINED) {
1569                                 /* drap: and imm, %rsp */
1570                                 cfa->base = state->drap_reg;
1571                                 cfa->offset = state->stack_size = 0;
1572                                 state->drap = true;
1573                         }
1574
1575                         /*
1576                          * Older versions of GCC (4.8ish) realign the stack
1577                          * without DRAP, with a frame pointer.
1578                          */
1579
1580                         break;
1581
1582                 case OP_SRC_POP:
1583                         if (!state->drap && op->dest.type == OP_DEST_REG &&
1584                             op->dest.reg == cfa->base) {
1585
1586                                 /* pop %rbp */
1587                                 cfa->base = CFI_SP;
1588                         }
1589
1590                         if (state->drap && cfa->base == CFI_BP_INDIRECT &&
1591                             op->dest.type == OP_DEST_REG &&
1592                             op->dest.reg == state->drap_reg &&
1593                             state->drap_offset == -state->stack_size) {
1594
1595                                 /* drap: pop %drap */
1596                                 cfa->base = state->drap_reg;
1597                                 cfa->offset = 0;
1598                                 state->drap_offset = -1;
1599
1600                         } else if (regs[op->dest.reg].offset == -state->stack_size) {
1601
1602                                 /* pop %reg */
1603                                 restore_reg(state, op->dest.reg);
1604                         }
1605
1606                         state->stack_size -= 8;
1607                         if (cfa->base == CFI_SP)
1608                                 cfa->offset -= 8;
1609
1610                         break;
1611
1612                 case OP_SRC_REG_INDIRECT:
1613                         if (state->drap && op->src.reg == CFI_BP &&
1614                             op->src.offset == state->drap_offset) {
1615
1616                                 /* drap: mov disp(%rbp), %drap */
1617                                 cfa->base = state->drap_reg;
1618                                 cfa->offset = 0;
1619                                 state->drap_offset = -1;
1620                         }
1621
1622                         if (state->drap && op->src.reg == CFI_BP &&
1623                             op->src.offset == regs[op->dest.reg].offset) {
1624
1625                                 /* drap: mov disp(%rbp), %reg */
1626                                 restore_reg(state, op->dest.reg);
1627
1628                         } else if (op->src.reg == cfa->base &&
1629                             op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
1630
1631                                 /* mov disp(%rbp), %reg */
1632                                 /* mov disp(%rsp), %reg */
1633                                 restore_reg(state, op->dest.reg);
1634                         }
1635
1636                         break;
1637
1638                 default:
1639                         WARN_FUNC("unknown stack-related instruction",
1640                                   insn->sec, insn->offset);
1641                         return -1;
1642                 }
1643
1644                 break;
1645
1646         case OP_DEST_PUSH:
1647                 state->stack_size += 8;
1648                 if (cfa->base == CFI_SP)
1649                         cfa->offset += 8;
1650
1651                 if (op->src.type != OP_SRC_REG)
1652                         break;
1653
1654                 if (state->drap) {
1655                         if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
1656
1657                                 /* drap: push %drap */
1658                                 cfa->base = CFI_BP_INDIRECT;
1659                                 cfa->offset = -state->stack_size;
1660
1661                                 /* save drap so we know when to restore it */
1662                                 state->drap_offset = -state->stack_size;
1663
1664                         } else if (op->src.reg == CFI_BP && cfa->base == state->drap_reg) {
1665
1666                                 /* drap: push %rbp */
1667                                 state->stack_size = 0;
1668
1669                         } else if (regs[op->src.reg].base == CFI_UNDEFINED) {
1670
1671                                 /* drap: push %reg */
1672                                 save_reg(state, op->src.reg, CFI_BP, -state->stack_size);
1673                         }
1674
1675                 } else {
1676
1677                         /* push %reg */
1678                         save_reg(state, op->src.reg, CFI_CFA, -state->stack_size);
1679                 }
1680
1681                 /* detect when asm code uses rbp as a scratch register */
1682                 if (!no_fp && insn->func && op->src.reg == CFI_BP &&
1683                     cfa->base != CFI_BP)
1684                         state->bp_scratch = true;
1685                 break;
1686
1687         case OP_DEST_REG_INDIRECT:
1688
1689                 if (state->drap) {
1690                         if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
1691
1692                                 /* drap: mov %drap, disp(%rbp) */
1693                                 cfa->base = CFI_BP_INDIRECT;
1694                                 cfa->offset = op->dest.offset;
1695
1696                                 /* save drap offset so we know when to restore it */
1697                                 state->drap_offset = op->dest.offset;
1698                         }
1699
1700                         else if (regs[op->src.reg].base == CFI_UNDEFINED) {
1701
1702                                 /* drap: mov reg, disp(%rbp) */
1703                                 save_reg(state, op->src.reg, CFI_BP, op->dest.offset);
1704                         }
1705
1706                 } else if (op->dest.reg == cfa->base) {
1707
1708                         /* mov reg, disp(%rbp) */
1709                         /* mov reg, disp(%rsp) */
1710                         save_reg(state, op->src.reg, CFI_CFA,
1711                                  op->dest.offset - state->cfa.offset);
1712                 }
1713
1714                 break;
1715
1716         case OP_DEST_LEAVE:
1717                 if ((!state->drap && cfa->base != CFI_BP) ||
1718                     (state->drap && cfa->base != state->drap_reg)) {
1719                         WARN_FUNC("leave instruction with modified stack frame",
1720                                   insn->sec, insn->offset);
1721                         return -1;
1722                 }
1723
1724                 /* leave (mov %rbp, %rsp; pop %rbp) */
1725
1726                 state->stack_size = -state->regs[CFI_BP].offset - 8;
1727                 restore_reg(state, CFI_BP);
1728
1729                 if (!state->drap) {
1730                         cfa->base = CFI_SP;
1731                         cfa->offset -= 8;
1732                 }
1733
1734                 break;
1735
1736         case OP_DEST_MEM:
1737                 if (op->src.type != OP_SRC_POP) {
1738                         WARN_FUNC("unknown stack-related memory operation",
1739                                   insn->sec, insn->offset);
1740                         return -1;
1741                 }
1742
1743                 /* pop mem */
1744                 state->stack_size -= 8;
1745                 if (cfa->base == CFI_SP)
1746                         cfa->offset -= 8;
1747
1748                 break;
1749
1750         default:
1751                 WARN_FUNC("unknown stack-related instruction",
1752                           insn->sec, insn->offset);
1753                 return -1;
1754         }
1755
1756         return 0;
1757 }
1758
1759 static bool insn_state_match(struct instruction *insn, struct insn_state *state)
1760 {
1761         struct insn_state *state1 = &insn->state, *state2 = state;
1762         int i;
1763
1764         if (memcmp(&state1->cfa, &state2->cfa, sizeof(state1->cfa))) {
1765                 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
1766                           insn->sec, insn->offset,
1767                           state1->cfa.base, state1->cfa.offset,
1768                           state2->cfa.base, state2->cfa.offset);
1769
1770         } else if (memcmp(&state1->regs, &state2->regs, sizeof(state1->regs))) {
1771                 for (i = 0; i < CFI_NUM_REGS; i++) {
1772                         if (!memcmp(&state1->regs[i], &state2->regs[i],
1773                                     sizeof(struct cfi_reg)))
1774                                 continue;
1775
1776                         WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
1777                                   insn->sec, insn->offset,
1778                                   i, state1->regs[i].base, state1->regs[i].offset,
1779                                   i, state2->regs[i].base, state2->regs[i].offset);
1780                         break;
1781                 }
1782
1783         } else if (state1->type != state2->type) {
1784                 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
1785                           insn->sec, insn->offset, state1->type, state2->type);
1786
1787         } else if (state1->drap != state2->drap ||
1788                  (state1->drap && state1->drap_reg != state2->drap_reg) ||
1789                  (state1->drap && state1->drap_offset != state2->drap_offset)) {
1790                 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
1791                           insn->sec, insn->offset,
1792                           state1->drap, state1->drap_reg, state1->drap_offset,
1793                           state2->drap, state2->drap_reg, state2->drap_offset);
1794
1795         } else
1796                 return true;
1797
1798         return false;
1799 }
1800
1801 /*
1802  * Follow the branch starting at the given instruction, and recursively follow
1803  * any other branches (jumps).  Meanwhile, track the frame pointer state at
1804  * each instruction and validate all the rules described in
1805  * tools/objtool/Documentation/stack-validation.txt.
1806  */
1807 static int validate_branch(struct objtool_file *file, struct instruction *first,
1808                            struct insn_state state)
1809 {
1810         struct alternative *alt;
1811         struct instruction *insn, *next_insn;
1812         struct section *sec;
1813         struct symbol *func = NULL;
1814         int ret;
1815
1816         insn = first;
1817         sec = insn->sec;
1818
1819         if (insn->alt_group && list_empty(&insn->alts)) {
1820                 WARN_FUNC("don't know how to handle branch to middle of alternative instruction group",
1821                           sec, insn->offset);
1822                 return 1;
1823         }
1824
1825         while (1) {
1826                 next_insn = next_insn_same_sec(file, insn);
1827
1828                 if (file->c_file && func && insn->func && func != insn->func->pfunc) {
1829                         WARN("%s() falls through to next function %s()",
1830                              func->name, insn->func->name);
1831                         return 1;
1832                 }
1833
1834                 func = insn->func ? insn->func->pfunc : NULL;
1835
1836                 if (func && insn->ignore) {
1837                         WARN_FUNC("BUG: why am I validating an ignored function?",
1838                                   sec, insn->offset);
1839                         return 1;
1840                 }
1841
1842                 if (insn->visited) {
1843                         if (!insn->hint && !insn_state_match(insn, &state))
1844                                 return 1;
1845
1846                         return 0;
1847                 }
1848
1849                 if (insn->hint) {
1850                         if (insn->restore) {
1851                                 struct instruction *save_insn, *i;
1852
1853                                 i = insn;
1854                                 save_insn = NULL;
1855                                 func_for_each_insn_continue_reverse(file, insn->func, i) {
1856                                         if (i->save) {
1857                                                 save_insn = i;
1858                                                 break;
1859                                         }
1860                                 }
1861
1862                                 if (!save_insn) {
1863                                         WARN_FUNC("no corresponding CFI save for CFI restore",
1864                                                   sec, insn->offset);
1865                                         return 1;
1866                                 }
1867
1868                                 if (!save_insn->visited) {
1869                                         /*
1870                                          * Oops, no state to copy yet.
1871                                          * Hopefully we can reach this
1872                                          * instruction from another branch
1873                                          * after the save insn has been
1874                                          * visited.
1875                                          */
1876                                         if (insn == first)
1877                                                 return 0;
1878
1879                                         WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
1880                                                   sec, insn->offset);
1881                                         return 1;
1882                                 }
1883
1884                                 insn->state = save_insn->state;
1885                         }
1886
1887                         state = insn->state;
1888
1889                 } else
1890                         insn->state = state;
1891
1892                 insn->visited = true;
1893
1894                 if (!insn->ignore_alts) {
1895                         list_for_each_entry(alt, &insn->alts, list) {
1896                                 ret = validate_branch(file, alt->insn, state);
1897                                 if (ret)
1898                                         return 1;
1899                         }
1900                 }
1901
1902                 switch (insn->type) {
1903
1904                 case INSN_RETURN:
1905                         if (func && has_modified_stack_frame(&state)) {
1906                                 WARN_FUNC("return with modified stack frame",
1907                                           sec, insn->offset);
1908                                 return 1;
1909                         }
1910
1911                         if (state.bp_scratch) {
1912                                 WARN("%s uses BP as a scratch register",
1913                                      insn->func->name);
1914                                 return 1;
1915                         }
1916
1917                         return 0;
1918
1919                 case INSN_CALL:
1920                         if (is_fentry_call(insn))
1921                                 break;
1922
1923                         ret = dead_end_function(file, insn->call_dest);
1924                         if (ret == 1)
1925                                 return 0;
1926                         if (ret == -1)
1927                                 return 1;
1928
1929                         /* fallthrough */
1930                 case INSN_CALL_DYNAMIC:
1931                         if (!no_fp && func && !has_valid_stack_frame(&state)) {
1932                                 WARN_FUNC("call without frame pointer save/setup",
1933                                           sec, insn->offset);
1934                                 return 1;
1935                         }
1936                         break;
1937
1938                 case INSN_JUMP_CONDITIONAL:
1939                 case INSN_JUMP_UNCONDITIONAL:
1940                         if (insn->jump_dest &&
1941                             (!func || !insn->jump_dest->func ||
1942                              insn->jump_dest->func->pfunc == func)) {
1943                                 ret = validate_branch(file, insn->jump_dest,
1944                                                       state);
1945                                 if (ret)
1946                                         return 1;
1947
1948                         } else if (func && has_modified_stack_frame(&state)) {
1949                                 WARN_FUNC("sibling call from callable instruction with modified stack frame",
1950                                           sec, insn->offset);
1951                                 return 1;
1952                         }
1953
1954                         if (insn->type == INSN_JUMP_UNCONDITIONAL)
1955                                 return 0;
1956
1957                         break;
1958
1959                 case INSN_JUMP_DYNAMIC:
1960                         if (func && list_empty(&insn->alts) &&
1961                             has_modified_stack_frame(&state)) {
1962                                 WARN_FUNC("sibling call from callable instruction with modified stack frame",
1963                                           sec, insn->offset);
1964                                 return 1;
1965                         }
1966
1967                         return 0;
1968
1969                 case INSN_CONTEXT_SWITCH:
1970                         if (func && (!next_insn || !next_insn->hint)) {
1971                                 WARN_FUNC("unsupported instruction in callable function",
1972                                           sec, insn->offset);
1973                                 return 1;
1974                         }
1975                         return 0;
1976
1977                 case INSN_STACK:
1978                         if (update_insn_state(insn, &state))
1979                                 return 1;
1980
1981                         break;
1982
1983                 default:
1984                         break;
1985                 }
1986
1987                 if (insn->dead_end)
1988                         return 0;
1989
1990                 if (!next_insn) {
1991                         if (state.cfa.base == CFI_UNDEFINED)
1992                                 return 0;
1993                         WARN("%s: unexpected end of section", sec->name);
1994                         return 1;
1995                 }
1996
1997                 insn = next_insn;
1998         }
1999
2000         return 0;
2001 }
2002
2003 static int validate_unwind_hints(struct objtool_file *file)
2004 {
2005         struct instruction *insn;
2006         int ret, warnings = 0;
2007         struct insn_state state;
2008
2009         if (!file->hints)
2010                 return 0;
2011
2012         clear_insn_state(&state);
2013
2014         for_each_insn(file, insn) {
2015                 if (insn->hint && !insn->visited) {
2016                         ret = validate_branch(file, insn, state);
2017                         warnings += ret;
2018                 }
2019         }
2020
2021         return warnings;
2022 }
2023
2024 static int validate_retpoline(struct objtool_file *file)
2025 {
2026         struct instruction *insn;
2027         int warnings = 0;
2028
2029         for_each_insn(file, insn) {
2030                 if (insn->type != INSN_JUMP_DYNAMIC &&
2031                     insn->type != INSN_CALL_DYNAMIC)
2032                         continue;
2033
2034                 if (insn->retpoline_safe)
2035                         continue;
2036
2037                 /*
2038                  * .init.text code is ran before userspace and thus doesn't
2039                  * strictly need retpolines, except for modules which are
2040                  * loaded late, they very much do need retpoline in their
2041                  * .init.text
2042                  */
2043                 if (!strcmp(insn->sec->name, ".init.text") && !module)
2044                         continue;
2045
2046                 WARN_FUNC("indirect %s found in RETPOLINE build",
2047                           insn->sec, insn->offset,
2048                           insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
2049
2050                 warnings++;
2051         }
2052
2053         return warnings;
2054 }
2055
2056 static bool is_kasan_insn(struct instruction *insn)
2057 {
2058         return (insn->type == INSN_CALL &&
2059                 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
2060 }
2061
2062 static bool is_ubsan_insn(struct instruction *insn)
2063 {
2064         return (insn->type == INSN_CALL &&
2065                 !strcmp(insn->call_dest->name,
2066                         "__ubsan_handle_builtin_unreachable"));
2067 }
2068
2069 static bool ignore_unreachable_insn(struct instruction *insn)
2070 {
2071         int i;
2072
2073         if (insn->ignore || insn->type == INSN_NOP)
2074                 return true;
2075
2076         /*
2077          * Ignore any unused exceptions.  This can happen when a whitelisted
2078          * function has an exception table entry.
2079          *
2080          * Also ignore alternative replacement instructions.  This can happen
2081          * when a whitelisted function uses one of the ALTERNATIVE macros.
2082          */
2083         if (!strcmp(insn->sec->name, ".fixup") ||
2084             !strcmp(insn->sec->name, ".altinstr_replacement") ||
2085             !strcmp(insn->sec->name, ".altinstr_aux"))
2086                 return true;
2087
2088         /*
2089          * Check if this (or a subsequent) instruction is related to
2090          * CONFIG_UBSAN or CONFIG_KASAN.
2091          *
2092          * End the search at 5 instructions to avoid going into the weeds.
2093          */
2094         if (!insn->func)
2095                 return false;
2096         for (i = 0; i < 5; i++) {
2097
2098                 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
2099                         return true;
2100
2101                 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
2102                         if (insn->jump_dest &&
2103                             insn->jump_dest->func == insn->func) {
2104                                 insn = insn->jump_dest;
2105                                 continue;
2106                         }
2107
2108                         break;
2109                 }
2110
2111                 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
2112                         break;
2113
2114                 insn = list_next_entry(insn, list);
2115         }
2116
2117         return false;
2118 }
2119
2120 static int validate_functions(struct objtool_file *file)
2121 {
2122         struct section *sec;
2123         struct symbol *func;
2124         struct instruction *insn;
2125         struct insn_state state;
2126         int ret, warnings = 0;
2127
2128         clear_insn_state(&state);
2129
2130         state.cfa = initial_func_cfi.cfa;
2131         memcpy(&state.regs, &initial_func_cfi.regs,
2132                CFI_NUM_REGS * sizeof(struct cfi_reg));
2133         state.stack_size = initial_func_cfi.cfa.offset;
2134
2135         for_each_sec(file, sec) {
2136                 list_for_each_entry(func, &sec->symbol_list, list) {
2137                         if (func->type != STT_FUNC || func->pfunc != func)
2138                                 continue;
2139
2140                         insn = find_insn(file, sec, func->offset);
2141                         if (!insn || insn->ignore)
2142                                 continue;
2143
2144                         ret = validate_branch(file, insn, state);
2145                         warnings += ret;
2146                 }
2147         }
2148
2149         return warnings;
2150 }
2151
2152 static int validate_reachable_instructions(struct objtool_file *file)
2153 {
2154         struct instruction *insn;
2155
2156         if (file->ignore_unreachables)
2157                 return 0;
2158
2159         for_each_insn(file, insn) {
2160                 if (insn->visited || ignore_unreachable_insn(insn))
2161                         continue;
2162
2163                 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
2164                 return 1;
2165         }
2166
2167         return 0;
2168 }
2169
2170 static void cleanup(struct objtool_file *file)
2171 {
2172         struct instruction *insn, *tmpinsn;
2173         struct alternative *alt, *tmpalt;
2174
2175         list_for_each_entry_safe(insn, tmpinsn, &file->insn_list, list) {
2176                 list_for_each_entry_safe(alt, tmpalt, &insn->alts, list) {
2177                         list_del(&alt->list);
2178                         free(alt);
2179                 }
2180                 list_del(&insn->list);
2181                 hash_del(&insn->hash);
2182                 free(insn);
2183         }
2184         elf_close(file->elf);
2185 }
2186
2187 int check(const char *_objname, bool orc)
2188 {
2189         struct objtool_file file;
2190         int ret, warnings = 0;
2191
2192         objname = _objname;
2193
2194         file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY);
2195         if (!file.elf)
2196                 return 1;
2197
2198         INIT_LIST_HEAD(&file.insn_list);
2199         hash_init(file.insn_hash);
2200         file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard");
2201         file.c_file = find_section_by_name(file.elf, ".comment");
2202         file.ignore_unreachables = no_unreachable;
2203         file.hints = false;
2204
2205         arch_initial_func_cfi_state(&initial_func_cfi);
2206
2207         ret = decode_sections(&file);
2208         if (ret < 0)
2209                 goto out;
2210         warnings += ret;
2211
2212         if (list_empty(&file.insn_list))
2213                 goto out;
2214
2215         if (retpoline) {
2216                 ret = validate_retpoline(&file);
2217                 if (ret < 0)
2218                         return ret;
2219                 warnings += ret;
2220         }
2221
2222         ret = validate_functions(&file);
2223         if (ret < 0)
2224                 goto out;
2225         warnings += ret;
2226
2227         ret = validate_unwind_hints(&file);
2228         if (ret < 0)
2229                 goto out;
2230         warnings += ret;
2231
2232         if (!warnings) {
2233                 ret = validate_reachable_instructions(&file);
2234                 if (ret < 0)
2235                         goto out;
2236                 warnings += ret;
2237         }
2238
2239         if (orc) {
2240                 ret = create_orc(&file);
2241                 if (ret < 0)
2242                         goto out;
2243
2244                 ret = create_orc_sections(&file);
2245                 if (ret < 0)
2246                         goto out;
2247
2248                 ret = elf_write(file.elf);
2249                 if (ret < 0)
2250                         goto out;
2251         }
2252
2253 out:
2254         cleanup(&file);
2255
2256         /* ignore warnings for now until we get all the code cleaned up */
2257         if (ret || warnings)
2258                 return 0;
2259         return 0;
2260 }