tools/objtool/check.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
   4  */
   5
   6 #include <string.h>
   7 #include <stdlib.h>
   8 #include <inttypes.h>
   9 #include <sys/mman.h>
  10
  11 #include <arch/elf.h>
  12 #include <objtool/builtin.h>
  13 #include <objtool/cfi.h>
  14 #include <objtool/arch.h>
  15 #include <objtool/check.h>
  16 #include <objtool/special.h>
  17 #include <objtool/warn.h>
  18 #include <objtool/endianness.h>
  19
  20 #include <linux/objtool.h>
  21 #include <linux/hashtable.h>
  22 #include <linux/kernel.h>
  23 #include <linux/static_call_types.h>
  24
  25 struct alternative {
  26         struct list_head list;
  27         struct instruction *insn;
  28         bool skip_orig;
  29 };
  30
  31 static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
  32
  33 static struct cfi_init_state initial_func_cfi;
  34 static struct cfi_state init_cfi;
  35 static struct cfi_state func_cfi;
  36
  37 struct instruction *find_insn(struct objtool_file *file,
  38                               struct section *sec, unsigned long offset)
  39 {
  40         struct instruction *insn;
  41
  42         hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
  43                 if (insn->sec == sec && insn->offset == offset)
  44                         return insn;
  45         }
  46
  47         return NULL;
  48 }
  49
  50 static struct instruction *next_insn_same_sec(struct objtool_file *file,
  51                                               struct instruction *insn)
  52 {
  53         struct instruction *next = list_next_entry(insn, list);
  54
  55         if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
  56                 return NULL;
  57
  58         return next;
  59 }
  60
  61 static struct instruction *next_insn_same_func(struct objtool_file *file,
  62                                                struct instruction *insn)
  63 {
  64         struct instruction *next = list_next_entry(insn, list);
  65         struct symbol *func = insn->func;
  66
  67         if (!func)
  68                 return NULL;
  69
  70         if (&next->list != &file->insn_list && next->func == func)
  71                 return next;
  72
  73         /* Check if we're already in the subfunction: */
  74         if (func == func->cfunc)
  75                 return NULL;
  76
  77         /* Move to the subfunction: */
  78         return find_insn(file, func->cfunc->sec, func->cfunc->offset);
  79 }
  80
  81 static struct instruction *prev_insn_same_sym(struct objtool_file *file,
  82                                                struct instruction *insn)
  83 {
  84         struct instruction *prev = list_prev_entry(insn, list);
  85
  86         if (&prev->list != &file->insn_list && prev->func == insn->func)
  87                 return prev;
  88
  89         return NULL;
  90 }
  91
  92 #define func_for_each_insn(file, func, insn)                            \
  93         for (insn = find_insn(file, func->sec, func->offset);           \
  94              insn;                                                      \
  95              insn = next_insn_same_func(file, insn))
  96
  97 #define sym_for_each_insn(file, sym, insn)                              \
  98         for (insn = find_insn(file, sym->sec, sym->offset);             \
  99              insn && &insn->list != &file->insn_list &&                 \
 100                 insn->sec == sym->sec &&                                \
 101                 insn->offset < sym->offset + sym->len;                  \
 102              insn = list_next_entry(insn, list))
 103
 104 #define sym_for_each_insn_continue_reverse(file, sym, insn)             \
 105         for (insn = list_prev_entry(insn, list);                        \
 106              &insn->list != &file->insn_list &&                         \
 107                 insn->sec == sym->sec && insn->offset >= sym->offset;   \
 108              insn = list_prev_entry(insn, list))
 109
 110 #define sec_for_each_insn_from(file, insn)                              \
 111         for (; insn; insn = next_insn_same_sec(file, insn))
 112
 113 #define sec_for_each_insn_continue(file, insn)                          \
 114         for (insn = next_insn_same_sec(file, insn); insn;               \
 115              insn = next_insn_same_sec(file, insn))
 116
 117 static bool is_jump_table_jump(struct instruction *insn)
 118 {
 119         struct alt_group *alt_group = insn->alt_group;
 120
 121         if (insn->jump_table)
 122                 return true;
 123
 124         /* Retpoline alternative for a jump table? */
 125         return alt_group && alt_group->orig_group &&
 126                alt_group->orig_group->first_insn->jump_table;
 127 }
 128
 129 static bool is_sibling_call(struct instruction *insn)
 130 {
 131         /*
 132          * Assume only ELF functions can make sibling calls.  This ensures
 133          * sibling call detection consistency between vmlinux.o and individual
 134          * objects.
 135          */
 136         if (!insn->func)
 137                 return false;
 138
 139         /* An indirect jump is either a sibling call or a jump to a table. */
 140         if (insn->type == INSN_JUMP_DYNAMIC)
 141                 return !is_jump_table_jump(insn);
 142
 143         /* add_jump_destinations() sets insn->call_dest for sibling calls. */
 144         return (is_static_jump(insn) && insn->call_dest);
 145 }
 146
 147 /*
 148  * This checks to see if the given function is a "noreturn" function.
 149  *
 150  * For global functions which are outside the scope of this object file, we
 151  * have to keep a manual list of them.
 152  *
 153  * For local functions, we have to detect them manually by simply looking for
 154  * the lack of a return instruction.
 155  */
 156 static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 157                                 int recursion)
 158 {
 159         int i;
 160         struct instruction *insn;
 161         bool empty = true;
 162
 163         /*
 164          * Unfortunately these have to be hard coded because the noreturn
 165          * attribute isn't provided in ELF data. Keep 'em sorted.
 166          */
 167         static const char * const global_noreturns[] = {
 168                 "__invalid_creds",
 169                 "__module_put_and_kthread_exit",
 170                 "__reiserfs_panic",
 171                 "__stack_chk_fail",
 172                 "__ubsan_handle_builtin_unreachable",
 173                 "cpu_bringup_and_idle",
 174                 "cpu_startup_entry",
 175                 "do_exit",
 176                 "do_group_exit",
 177                 "do_task_dead",
 178                 "ex_handler_msr_mce",
 179                 "fortify_panic",
 180                 "kthread_complete_and_exit",
 181                 "kthread_exit",
 182                 "kunit_try_catch_throw",
 183                 "lbug_with_loc",
 184                 "machine_real_restart",
 185                 "make_task_dead",
 186                 "panic",
 187                 "rewind_stack_and_make_dead",
 188                 "sev_es_terminate",
 189                 "snp_abort",
 190                 "stop_this_cpu",
 191                 "usercopy_abort",
 192                 "xen_start_kernel",
 193         };
 194
 195         if (!func)
 196                 return false;
 197
 198         if (func->bind == STB_WEAK)
 199                 return false;
 200
 201         if (func->bind == STB_GLOBAL)
 202                 for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
 203                         if (!strcmp(func->name, global_noreturns[i]))
 204                                 return true;
 205
 206         if (!func->len)
 207                 return false;
 208
 209         insn = find_insn(file, func->sec, func->offset);
 210         if (!insn->func)
 211                 return false;
 212
 213         func_for_each_insn(file, func, insn) {
 214                 empty = false;
 215
 216                 if (insn->type == INSN_RETURN)
 217                         return false;
 218         }
 219
 220         if (empty)
 221                 return false;
 222
 223         /*
 224          * A function can have a sibling call instead of a return.  In that
 225          * case, the function's dead-end status depends on whether the target
 226          * of the sibling call returns.
 227          */
 228         func_for_each_insn(file, func, insn) {
 229                 if (is_sibling_call(insn)) {
 230                         struct instruction *dest = insn->jump_dest;
 231
 232                         if (!dest)
 233                                 /* sibling call to another file */
 234                                 return false;
 235
 236                         /* local sibling call */
 237                         if (recursion == 5) {
 238                                 /*
 239                                  * Infinite recursion: two functions have
 240                                  * sibling calls to each other.  This is a very
 241                                  * rare case.  It means they aren't dead ends.
 242                                  */
 243                                 return false;
 244                         }
 245
 246                         return __dead_end_function(file, dest->func, recursion+1);
 247                 }
 248         }
 249
 250         return true;
 251 }
 252
 253 static bool dead_end_function(struct objtool_file *file, struct symbol *func)
 254 {
 255         return __dead_end_function(file, func, 0);
 256 }
 257
 258 static void init_cfi_state(struct cfi_state *cfi)
 259 {
 260         int i;
 261
 262         for (i = 0; i < CFI_NUM_REGS; i++) {
 263                 cfi->regs[i].base = CFI_UNDEFINED;
 264                 cfi->vals[i].base = CFI_UNDEFINED;
 265         }
 266         cfi->cfa.base = CFI_UNDEFINED;
 267         cfi->drap_reg = CFI_UNDEFINED;
 268         cfi->drap_offset = -1;
 269 }
 270
 271 static void init_insn_state(struct objtool_file *file, struct insn_state *state,
 272                             struct section *sec)
 273 {
 274         memset(state, 0, sizeof(*state));
 275         init_cfi_state(&state->cfi);
 276
 277         /*
 278          * We need the full vmlinux for noinstr validation, otherwise we can
 279          * not correctly determine insn->call_dest->sec (external symbols do
 280          * not have a section).
 281          */
 282         if (opts.link && opts.noinstr && sec)
 283                 state->noinstr = sec->noinstr;
 284 }
 285
 286 static struct cfi_state *cfi_alloc(void)
 287 {
 288         struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1);
 289         if (!cfi) {
 290                 WARN("calloc failed");
 291                 exit(1);
 292         }
 293         nr_cfi++;
 294         return cfi;
 295 }
 296
 297 static int cfi_bits;
 298 static struct hlist_head *cfi_hash;
 299
 300 static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2)
 301 {
 302         return memcmp((void *)cfi1 + sizeof(cfi1->hash),
 303                       (void *)cfi2 + sizeof(cfi2->hash),
 304                       sizeof(struct cfi_state) - sizeof(struct hlist_node));
 305 }
 306
 307 static inline u32 cfi_key(struct cfi_state *cfi)
 308 {
 309         return jhash((void *)cfi + sizeof(cfi->hash),
 310                      sizeof(*cfi) - sizeof(cfi->hash), 0);
 311 }
 312
 313 static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi)
 314 {
 315         struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
 316         struct cfi_state *obj;
 317
 318         hlist_for_each_entry(obj, head, hash) {
 319                 if (!cficmp(cfi, obj)) {
 320                         nr_cfi_cache++;
 321                         return obj;
 322                 }
 323         }
 324
 325         obj = cfi_alloc();
 326         *obj = *cfi;
 327         hlist_add_head(&obj->hash, head);
 328
 329         return obj;
 330 }
 331
 332 static void cfi_hash_add(struct cfi_state *cfi)
 333 {
 334         struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
 335
 336         hlist_add_head(&cfi->hash, head);
 337 }
 338
 339 static void *cfi_hash_alloc(unsigned long size)
 340 {
 341         cfi_bits = max(10, ilog2(size));
 342         cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits,
 343                         PROT_READ|PROT_WRITE,
 344                         MAP_PRIVATE|MAP_ANON, -1, 0);
 345         if (cfi_hash == (void *)-1L) {
 346                 WARN("mmap fail cfi_hash");
 347                 cfi_hash = NULL;
 348         }  else if (opts.stats) {
 349                 printf("cfi_bits: %d\n", cfi_bits);
 350         }
 351
 352         return cfi_hash;
 353 }
 354
 355 static unsigned long nr_insns;
 356 static unsigned long nr_insns_visited;
 357
 358 /*
 359  * Call the arch-specific instruction decoder for all the instructions and add
 360  * them to the global instruction list.
 361  */
 362 static int decode_instructions(struct objtool_file *file)
 363 {
 364         struct section *sec;
 365         struct symbol *func;
 366         unsigned long offset;
 367         struct instruction *insn;
 368         int ret;
 369
 370         for_each_sec(file, sec) {
 371
 372                 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
 373                         continue;
 374
 375                 if (strcmp(sec->name, ".altinstr_replacement") &&
 376                     strcmp(sec->name, ".altinstr_aux") &&
 377                     strncmp(sec->name, ".discard.", 9))
 378                         sec->text = true;
 379
 380                 if (!strcmp(sec->name, ".noinstr.text") ||
 381                     !strcmp(sec->name, ".entry.text") ||
 382                     !strncmp(sec->name, ".text.__x86.", 12))
 383                         sec->noinstr = true;
 384
 385                 for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
 386                         insn = malloc(sizeof(*insn));
 387                         if (!insn) {
 388                                 WARN("malloc failed");
 389                                 return -1;
 390                         }
 391                         memset(insn, 0, sizeof(*insn));
 392                         INIT_LIST_HEAD(&insn->alts);
 393                         INIT_LIST_HEAD(&insn->stack_ops);
 394                         INIT_LIST_HEAD(&insn->call_node);
 395
 396                         insn->sec = sec;
 397                         insn->offset = offset;
 398
 399                         ret = arch_decode_instruction(file, sec, offset,
 400                                                       sec->sh.sh_size - offset,
 401                                                       &insn->len, &insn->type,
 402                                                       &insn->immediate,
 403                                                       &insn->stack_ops);
 404                         if (ret)
 405                                 goto err;
 406
 407                         /*
 408                          * By default, "ud2" is a dead end unless otherwise
 409                          * annotated, because GCC 7 inserts it for certain
 410                          * divide-by-zero cases.
 411                          */
 412                         if (insn->type == INSN_BUG)
 413                                 insn->dead_end = true;
 414
 415                         hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
 416                         list_add_tail(&insn->list, &file->insn_list);
 417                         nr_insns++;
 418                 }
 419
 420                 list_for_each_entry(func, &sec->symbol_list, list) {
 421                         if (func->type != STT_FUNC || func->alias != func)
 422                                 continue;
 423
 424                         if (!find_insn(file, sec, func->offset)) {
 425                                 WARN("%s(): can't find starting instruction",
 426                                      func->name);
 427                                 return -1;
 428                         }
 429
 430                         sym_for_each_insn(file, func, insn) {
 431                                 insn->func = func;
 432                                 if (insn->type == INSN_ENDBR && list_empty(&insn->call_node)) {
 433                                         if (insn->offset == insn->func->offset) {
 434                                                 list_add_tail(&insn->call_node, &file->endbr_list);
 435                                                 file->nr_endbr++;
 436                                         } else {
 437                                                 file->nr_endbr_int++;
 438                                         }
 439                                 }
 440                         }
 441                 }
 442         }
 443
 444         if (opts.stats)
 445                 printf("nr_insns: %lu\n", nr_insns);
 446
 447         return 0;
 448
 449 err:
 450         free(insn);
 451         return ret;
 452 }
 453
 454 /*
 455  * Read the pv_ops[] .data table to find the static initialized values.
 456  */
 457 static int add_pv_ops(struct objtool_file *file, const char *symname)
 458 {
 459         struct symbol *sym, *func;
 460         unsigned long off, end;
 461         struct reloc *rel;
 462         int idx;
 463
 464         sym = find_symbol_by_name(file->elf, symname);
 465         if (!sym)
 466                 return 0;
 467
 468         off = sym->offset;
 469         end = off + sym->len;
 470         for (;;) {
 471                 rel = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off);
 472                 if (!rel)
 473                         break;
 474
 475                 func = rel->sym;
 476                 if (func->type == STT_SECTION)
 477                         func = find_symbol_by_offset(rel->sym->sec, rel->addend);
 478
 479                 idx = (rel->offset - sym->offset) / sizeof(unsigned long);
 480
 481                 objtool_pv_add(file, idx, func);
 482
 483                 off = rel->offset + 1;
 484                 if (off > end)
 485                         break;
 486         }
 487
 488         return 0;
 489 }
 490
 491 /*
 492  * Allocate and initialize file->pv_ops[].
 493  */
 494 static int init_pv_ops(struct objtool_file *file)
 495 {
 496         static const char *pv_ops_tables[] = {
 497                 "pv_ops",
 498                 "xen_cpu_ops",
 499                 "xen_irq_ops",
 500                 "xen_mmu_ops",
 501                 NULL,
 502         };
 503         const char *pv_ops;
 504         struct symbol *sym;
 505         int idx, nr;
 506
 507         if (!opts.noinstr)
 508                 return 0;
 509
 510         file->pv_ops = NULL;
 511
 512         sym = find_symbol_by_name(file->elf, "pv_ops");
 513         if (!sym)
 514                 return 0;
 515
 516         nr = sym->len / sizeof(unsigned long);
 517         file->pv_ops = calloc(sizeof(struct pv_state), nr);
 518         if (!file->pv_ops)
 519                 return -1;
 520
 521         for (idx = 0; idx < nr; idx++)
 522                 INIT_LIST_HEAD(&file->pv_ops[idx].targets);
 523
 524         for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++)
 525                 add_pv_ops(file, pv_ops);
 526
 527         return 0;
 528 }
 529
 530 static struct instruction *find_last_insn(struct objtool_file *file,
 531                                           struct section *sec)
 532 {
 533         struct instruction *insn = NULL;
 534         unsigned int offset;
 535         unsigned int end = (sec->sh.sh_size > 10) ? sec->sh.sh_size - 10 : 0;
 536
 537         for (offset = sec->sh.sh_size - 1; offset >= end && !insn; offset--)
 538                 insn = find_insn(file, sec, offset);
 539
 540         return insn;
 541 }
 542
 543 /*
 544  * Mark "ud2" instructions and manually annotated dead ends.
 545  */
 546 static int add_dead_ends(struct objtool_file *file)
 547 {
 548         struct section *sec;
 549         struct reloc *reloc;
 550         struct instruction *insn;
 551
 552         /*
 553          * Check for manually annotated dead ends.
 554          */
 555         sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
 556         if (!sec)
 557                 goto reachable;
 558
 559         list_for_each_entry(reloc, &sec->reloc_list, list) {
 560                 if (reloc->sym->type != STT_SECTION) {
 561                         WARN("unexpected relocation symbol type in %s", sec->name);
 562                         return -1;
 563                 }
 564                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
 565                 if (insn)
 566                         insn = list_prev_entry(insn, list);
 567                 else if (reloc->addend == reloc->sym->sec->sh.sh_size) {
 568                         insn = find_last_insn(file, reloc->sym->sec);
 569                         if (!insn) {
 570                                 WARN("can't find unreachable insn at %s+0x%" PRIx64,
 571                                      reloc->sym->sec->name, reloc->addend);
 572                                 return -1;
 573                         }
 574                 } else {
 575                         WARN("can't find unreachable insn at %s+0x%" PRIx64,
 576                              reloc->sym->sec->name, reloc->addend);
 577                         return -1;
 578                 }
 579
 580                 insn->dead_end = true;
 581         }
 582
 583 reachable:
 584         /*
 585          * These manually annotated reachable checks are needed for GCC 4.4,
 586          * where the Linux unreachable() macro isn't supported.  In that case
 587          * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
 588          * not a dead end.
 589          */
 590         sec = find_section_by_name(file->elf, ".rela.discard.reachable");
 591         if (!sec)
 592                 return 0;
 593
 594         list_for_each_entry(reloc, &sec->reloc_list, list) {
 595                 if (reloc->sym->type != STT_SECTION) {
 596                         WARN("unexpected relocation symbol type in %s", sec->name);
 597                         return -1;
 598                 }
 599                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
 600                 if (insn)
 601                         insn = list_prev_entry(insn, list);
 602                 else if (reloc->addend == reloc->sym->sec->sh.sh_size) {
 603                         insn = find_last_insn(file, reloc->sym->sec);
 604                         if (!insn) {
 605                                 WARN("can't find reachable insn at %s+0x%" PRIx64,
 606                                      reloc->sym->sec->name, reloc->addend);
 607                                 return -1;
 608                         }
 609                 } else {
 610                         WARN("can't find reachable insn at %s+0x%" PRIx64,
 611                              reloc->sym->sec->name, reloc->addend);
 612                         return -1;
 613                 }
 614
 615                 insn->dead_end = false;
 616         }
 617
 618         return 0;
 619 }
 620
 621 static int create_static_call_sections(struct objtool_file *file)
 622 {
 623         struct section *sec;
 624         struct static_call_site *site;
 625         struct instruction *insn;
 626         struct symbol *key_sym;
 627         char *key_name, *tmp;
 628         int idx;
 629
 630         sec = find_section_by_name(file->elf, ".static_call_sites");
 631         if (sec) {
 632                 INIT_LIST_HEAD(&file->static_call_list);
 633                 WARN("file already has .static_call_sites section, skipping");
 634                 return 0;
 635         }
 636
 637         if (list_empty(&file->static_call_list))
 638                 return 0;
 639
 640         idx = 0;
 641         list_for_each_entry(insn, &file->static_call_list, call_node)
 642                 idx++;
 643
 644         sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
 645                                  sizeof(struct static_call_site), idx);
 646         if (!sec)
 647                 return -1;
 648
 649         idx = 0;
 650         list_for_each_entry(insn, &file->static_call_list, call_node) {
 651
 652                 site = (struct static_call_site *)sec->data->d_buf + idx;
 653                 memset(site, 0, sizeof(struct static_call_site));
 654
 655                 /* populate reloc for 'addr' */
 656                 if (elf_add_reloc_to_insn(file->elf, sec,
 657                                           idx * sizeof(struct static_call_site),
 658                                           R_X86_64_PC32,
 659                                           insn->sec, insn->offset))
 660                         return -1;
 661
 662                 /* find key symbol */
 663                 key_name = strdup(insn->call_dest->name);
 664                 if (!key_name) {
 665                         perror("strdup");
 666                         return -1;
 667                 }
 668                 if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
 669                             STATIC_CALL_TRAMP_PREFIX_LEN)) {
 670                         WARN("static_call: trampoline name malformed: %s", key_name);
 671                         return -1;
 672                 }
 673                 tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
 674                 memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
 675
 676                 key_sym = find_symbol_by_name(file->elf, tmp);
 677                 if (!key_sym) {
 678                         if (!opts.module) {
 679                                 WARN("static_call: can't find static_call_key symbol: %s", tmp);
 680                                 return -1;
 681                         }
 682
 683                         /*
 684                          * For modules(), the key might not be exported, which
 685                          * means the module can make static calls but isn't
 686                          * allowed to change them.
 687                          *
 688                          * In that case we temporarily set the key to be the
 689                          * trampoline address.  This is fixed up in
 690                          * static_call_add_module().
 691                          */
 692                         key_sym = insn->call_dest;
 693                 }
 694                 free(key_name);
 695
 696                 /* populate reloc for 'key' */
 697                 if (elf_add_reloc(file->elf, sec,
 698                                   idx * sizeof(struct static_call_site) + 4,
 699                                   R_X86_64_PC32, key_sym,
 700                                   is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
 701                         return -1;
 702
 703                 idx++;
 704         }
 705
 706         return 0;
 707 }
 708
 709 static int create_retpoline_sites_sections(struct objtool_file *file)
 710 {
 711         struct instruction *insn;
 712         struct section *sec;
 713         int idx;
 714
 715         sec = find_section_by_name(file->elf, ".retpoline_sites");
 716         if (sec) {
 717                 WARN("file already has .retpoline_sites, skipping");
 718                 return 0;
 719         }
 720
 721         idx = 0;
 722         list_for_each_entry(insn, &file->retpoline_call_list, call_node)
 723                 idx++;
 724
 725         if (!idx)
 726                 return 0;
 727
 728         sec = elf_create_section(file->elf, ".retpoline_sites", 0,
 729                                  sizeof(int), idx);
 730         if (!sec) {
 731                 WARN("elf_create_section: .retpoline_sites");
 732                 return -1;
 733         }
 734
 735         idx = 0;
 736         list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
 737
 738                 int *site = (int *)sec->data->d_buf + idx;
 739                 *site = 0;
 740
 741                 if (elf_add_reloc_to_insn(file->elf, sec,
 742                                           idx * sizeof(int),
 743                                           R_X86_64_PC32,
 744                                           insn->sec, insn->offset)) {
 745                         WARN("elf_add_reloc_to_insn: .retpoline_sites");
 746                         return -1;
 747                 }
 748
 749                 idx++;
 750         }
 751
 752         return 0;
 753 }
 754
 755 static int create_return_sites_sections(struct objtool_file *file)
 756 {
 757         struct instruction *insn;
 758         struct section *sec;
 759         int idx;
 760
 761         sec = find_section_by_name(file->elf, ".return_sites");
 762         if (sec) {
 763                 WARN("file already has .return_sites, skipping");
 764                 return 0;
 765         }
 766
 767         idx = 0;
 768         list_for_each_entry(insn, &file->return_thunk_list, call_node)
 769                 idx++;
 770
 771         if (!idx)
 772                 return 0;
 773
 774         sec = elf_create_section(file->elf, ".return_sites", 0,
 775                                  sizeof(int), idx);
 776         if (!sec) {
 777                 WARN("elf_create_section: .return_sites");
 778                 return -1;
 779         }
 780
 781         idx = 0;
 782         list_for_each_entry(insn, &file->return_thunk_list, call_node) {
 783
 784                 int *site = (int *)sec->data->d_buf + idx;
 785                 *site = 0;
 786
 787                 if (elf_add_reloc_to_insn(file->elf, sec,
 788                                           idx * sizeof(int),
 789                                           R_X86_64_PC32,
 790                                           insn->sec, insn->offset)) {
 791                         WARN("elf_add_reloc_to_insn: .return_sites");
 792                         return -1;
 793                 }
 794
 795                 idx++;
 796         }
 797
 798         return 0;
 799 }
 800
 801 static int create_ibt_endbr_seal_sections(struct objtool_file *file)
 802 {
 803         struct instruction *insn;
 804         struct section *sec;
 805         int idx;
 806
 807         sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
 808         if (sec) {
 809                 WARN("file already has .ibt_endbr_seal, skipping");
 810                 return 0;
 811         }
 812
 813         idx = 0;
 814         list_for_each_entry(insn, &file->endbr_list, call_node)
 815                 idx++;
 816
 817         if (opts.stats) {
 818                 printf("ibt: ENDBR at function start: %d\n", file->nr_endbr);
 819                 printf("ibt: ENDBR inside functions:  %d\n", file->nr_endbr_int);
 820                 printf("ibt: superfluous ENDBR:       %d\n", idx);
 821         }
 822
 823         if (!idx)
 824                 return 0;
 825
 826         sec = elf_create_section(file->elf, ".ibt_endbr_seal", 0,
 827                                  sizeof(int), idx);
 828         if (!sec) {
 829                 WARN("elf_create_section: .ibt_endbr_seal");
 830                 return -1;
 831         }
 832
 833         idx = 0;
 834         list_for_each_entry(insn, &file->endbr_list, call_node) {
 835
 836                 int *site = (int *)sec->data->d_buf + idx;
 837                 *site = 0;
 838
 839                 if (elf_add_reloc_to_insn(file->elf, sec,
 840                                           idx * sizeof(int),
 841                                           R_X86_64_PC32,
 842                                           insn->sec, insn->offset)) {
 843                         WARN("elf_add_reloc_to_insn: .ibt_endbr_seal");
 844                         return -1;
 845                 }
 846
 847                 idx++;
 848         }
 849
 850         return 0;
 851 }
 852
 853 static int create_mcount_loc_sections(struct objtool_file *file)
 854 {
 855         struct section *sec;
 856         unsigned long *loc;
 857         struct instruction *insn;
 858         int idx;
 859
 860         sec = find_section_by_name(file->elf, "__mcount_loc");
 861         if (sec) {
 862                 INIT_LIST_HEAD(&file->mcount_loc_list);
 863                 WARN("file already has __mcount_loc section, skipping");
 864                 return 0;
 865         }
 866
 867         if (list_empty(&file->mcount_loc_list))
 868                 return 0;
 869
 870         idx = 0;
 871         list_for_each_entry(insn, &file->mcount_loc_list, call_node)
 872                 idx++;
 873
 874         sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx);
 875         if (!sec)
 876                 return -1;
 877
 878         idx = 0;
 879         list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
 880
 881                 loc = (unsigned long *)sec->data->d_buf + idx;
 882                 memset(loc, 0, sizeof(unsigned long));
 883
 884                 if (elf_add_reloc_to_insn(file->elf, sec,
 885                                           idx * sizeof(unsigned long),
 886                                           R_X86_64_64,
 887                                           insn->sec, insn->offset))
 888                         return -1;
 889
 890                 idx++;
 891         }
 892
 893         return 0;
 894 }
 895
 896 /*
 897  * Warnings shouldn't be reported for ignored functions.
 898  */
 899 static void add_ignores(struct objtool_file *file)
 900 {
 901         struct instruction *insn;
 902         struct section *sec;
 903         struct symbol *func;
 904         struct reloc *reloc;
 905
 906         sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
 907         if (!sec)
 908                 return;
 909
 910         list_for_each_entry(reloc, &sec->reloc_list, list) {
 911                 switch (reloc->sym->type) {
 912                 case STT_FUNC:
 913                         func = reloc->sym;
 914                         break;
 915
 916                 case STT_SECTION:
 917                         func = find_func_by_offset(reloc->sym->sec, reloc->addend);
 918                         if (!func)
 919                                 continue;
 920                         break;
 921
 922                 default:
 923                         WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type);
 924                         continue;
 925                 }
 926
 927                 func_for_each_insn(file, func, insn)
 928                         insn->ignore = true;
 929         }
 930 }
 931
 932 /*
 933  * This is a whitelist of functions that is allowed to be called with AC set.
 934  * The list is meant to be minimal and only contains compiler instrumentation
 935  * ABI and a few functions used to implement *_{to,from}_user() functions.
 936  *
 937  * These functions must not directly change AC, but may PUSHF/POPF.
 938  */
 939 static const char *uaccess_safe_builtin[] = {
 940         /* KASAN */
 941         "kasan_report",
 942         "kasan_check_range",
 943         /* KASAN out-of-line */
 944         "__asan_loadN_noabort",
 945         "__asan_load1_noabort",
 946         "__asan_load2_noabort",
 947         "__asan_load4_noabort",
 948         "__asan_load8_noabort",
 949         "__asan_load16_noabort",
 950         "__asan_storeN_noabort",
 951         "__asan_store1_noabort",
 952         "__asan_store2_noabort",
 953         "__asan_store4_noabort",
 954         "__asan_store8_noabort",
 955         "__asan_store16_noabort",
 956         "__kasan_check_read",
 957         "__kasan_check_write",
 958         /* KASAN in-line */
 959         "__asan_report_load_n_noabort",
 960         "__asan_report_load1_noabort",
 961         "__asan_report_load2_noabort",
 962         "__asan_report_load4_noabort",
 963         "__asan_report_load8_noabort",
 964         "__asan_report_load16_noabort",
 965         "__asan_report_store_n_noabort",
 966         "__asan_report_store1_noabort",
 967         "__asan_report_store2_noabort",
 968         "__asan_report_store4_noabort",
 969         "__asan_report_store8_noabort",
 970         "__asan_report_store16_noabort",
 971         /* KCSAN */
 972         "__kcsan_check_access",
 973         "__kcsan_mb",
 974         "__kcsan_wmb",
 975         "__kcsan_rmb",
 976         "__kcsan_release",
 977         "kcsan_found_watchpoint",
 978         "kcsan_setup_watchpoint",
 979         "kcsan_check_scoped_accesses",
 980         "kcsan_disable_current",
 981         "kcsan_enable_current_nowarn",
 982         /* KCSAN/TSAN */
 983         "__tsan_func_entry",
 984         "__tsan_func_exit",
 985         "__tsan_read_range",
 986         "__tsan_write_range",
 987         "__tsan_read1",
 988         "__tsan_read2",
 989         "__tsan_read4",
 990         "__tsan_read8",
 991         "__tsan_read16",
 992         "__tsan_write1",
 993         "__tsan_write2",
 994         "__tsan_write4",
 995         "__tsan_write8",
 996         "__tsan_write16",
 997         "__tsan_read_write1",
 998         "__tsan_read_write2",
 999         "__tsan_read_write4",
1000         "__tsan_read_write8",
1001         "__tsan_read_write16",
1002         "__tsan_atomic8_load",
1003         "__tsan_atomic16_load",
1004         "__tsan_atomic32_load",
1005         "__tsan_atomic64_load",
1006         "__tsan_atomic8_store",
1007         "__tsan_atomic16_store",
1008         "__tsan_atomic32_store",
1009         "__tsan_atomic64_store",
1010         "__tsan_atomic8_exchange",
1011         "__tsan_atomic16_exchange",
1012         "__tsan_atomic32_exchange",
1013         "__tsan_atomic64_exchange",
1014         "__tsan_atomic8_fetch_add",
1015         "__tsan_atomic16_fetch_add",
1016         "__tsan_atomic32_fetch_add",
1017         "__tsan_atomic64_fetch_add",
1018         "__tsan_atomic8_fetch_sub",
1019         "__tsan_atomic16_fetch_sub",
1020         "__tsan_atomic32_fetch_sub",
1021         "__tsan_atomic64_fetch_sub",
1022         "__tsan_atomic8_fetch_and",
1023         "__tsan_atomic16_fetch_and",
1024         "__tsan_atomic32_fetch_and",
1025         "__tsan_atomic64_fetch_and",
1026         "__tsan_atomic8_fetch_or",
1027         "__tsan_atomic16_fetch_or",
1028         "__tsan_atomic32_fetch_or",
1029         "__tsan_atomic64_fetch_or",
1030         "__tsan_atomic8_fetch_xor",
1031         "__tsan_atomic16_fetch_xor",
1032         "__tsan_atomic32_fetch_xor",
1033         "__tsan_atomic64_fetch_xor",
1034         "__tsan_atomic8_fetch_nand",
1035         "__tsan_atomic16_fetch_nand",
1036         "__tsan_atomic32_fetch_nand",
1037         "__tsan_atomic64_fetch_nand",
1038         "__tsan_atomic8_compare_exchange_strong",
1039         "__tsan_atomic16_compare_exchange_strong",
1040         "__tsan_atomic32_compare_exchange_strong",
1041         "__tsan_atomic64_compare_exchange_strong",
1042         "__tsan_atomic8_compare_exchange_weak",
1043         "__tsan_atomic16_compare_exchange_weak",
1044         "__tsan_atomic32_compare_exchange_weak",
1045         "__tsan_atomic64_compare_exchange_weak",
1046         "__tsan_atomic8_compare_exchange_val",
1047         "__tsan_atomic16_compare_exchange_val",
1048         "__tsan_atomic32_compare_exchange_val",
1049         "__tsan_atomic64_compare_exchange_val",
1050         "__tsan_atomic_thread_fence",
1051         "__tsan_atomic_signal_fence",
1052         /* KCOV */
1053         "write_comp_data",
1054         "check_kcov_mode",
1055         "__sanitizer_cov_trace_pc",
1056         "__sanitizer_cov_trace_const_cmp1",
1057         "__sanitizer_cov_trace_const_cmp2",
1058         "__sanitizer_cov_trace_const_cmp4",
1059         "__sanitizer_cov_trace_const_cmp8",
1060         "__sanitizer_cov_trace_cmp1",
1061         "__sanitizer_cov_trace_cmp2",
1062         "__sanitizer_cov_trace_cmp4",
1063         "__sanitizer_cov_trace_cmp8",
1064         "__sanitizer_cov_trace_switch",
1065         /* KMSAN */
1066         "kmsan_copy_to_user",
1067         "kmsan_report",
1068         "kmsan_unpoison_entry_regs",
1069         "kmsan_unpoison_memory",
1070         "__msan_chain_origin",
1071         "__msan_get_context_state",
1072         "__msan_instrument_asm_store",
1073         "__msan_metadata_ptr_for_load_1",
1074         "__msan_metadata_ptr_for_load_2",
1075         "__msan_metadata_ptr_for_load_4",
1076         "__msan_metadata_ptr_for_load_8",
1077         "__msan_metadata_ptr_for_load_n",
1078         "__msan_metadata_ptr_for_store_1",
1079         "__msan_metadata_ptr_for_store_2",
1080         "__msan_metadata_ptr_for_store_4",
1081         "__msan_metadata_ptr_for_store_8",
1082         "__msan_metadata_ptr_for_store_n",
1083         "__msan_poison_alloca",
1084         "__msan_warning",
1085         /* UBSAN */
1086         "ubsan_type_mismatch_common",
1087         "__ubsan_handle_type_mismatch",
1088         "__ubsan_handle_type_mismatch_v1",
1089         "__ubsan_handle_shift_out_of_bounds",
1090         /* misc */
1091         "csum_partial_copy_generic",
1092         "copy_mc_fragile",
1093         "copy_mc_fragile_handle_tail",
1094         "copy_mc_enhanced_fast_string",
1095         "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
1096         "clear_user_erms",
1097         "clear_user_rep_good",
1098         "clear_user_original",
1099         NULL
1100 };
1101
1102 static void add_uaccess_safe(struct objtool_file *file)
1103 {
1104         struct symbol *func;
1105         const char **name;
1106
1107         if (!opts.uaccess)
1108                 return;
1109
1110         for (name = uaccess_safe_builtin; *name; name++) {
1111                 func = find_symbol_by_name(file->elf, *name);
1112                 if (!func)
1113                         continue;
1114
1115                 func->uaccess_safe = true;
1116         }
1117 }
1118
1119 /*
1120  * FIXME: For now, just ignore any alternatives which add retpolines.  This is
1121  * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
1122  * But it at least allows objtool to understand the control flow *around* the
1123  * retpoline.
1124  */
1125 static int add_ignore_alternatives(struct objtool_file *file)
1126 {
1127         struct section *sec;
1128         struct reloc *reloc;
1129         struct instruction *insn;
1130
1131         sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
1132         if (!sec)
1133                 return 0;
1134
1135         list_for_each_entry(reloc, &sec->reloc_list, list) {
1136                 if (reloc->sym->type != STT_SECTION) {
1137                         WARN("unexpected relocation symbol type in %s", sec->name);
1138                         return -1;
1139                 }
1140
1141                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
1142                 if (!insn) {
1143                         WARN("bad .discard.ignore_alts entry");
1144                         return -1;
1145                 }
1146
1147                 insn->ignore_alts = true;
1148         }
1149
1150         return 0;
1151 }
1152
1153 __weak bool arch_is_retpoline(struct symbol *sym)
1154 {
1155         return false;
1156 }
1157
1158 __weak bool arch_is_rethunk(struct symbol *sym)
1159 {
1160         return false;
1161 }
1162
1163 #define NEGATIVE_RELOC  ((void *)-1L)
1164
1165 static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
1166 {
1167         if (insn->reloc == NEGATIVE_RELOC)
1168                 return NULL;
1169
1170         if (!insn->reloc) {
1171                 if (!file)
1172                         return NULL;
1173
1174                 insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
1175                                                        insn->offset, insn->len);
1176                 if (!insn->reloc) {
1177                         insn->reloc = NEGATIVE_RELOC;
1178                         return NULL;
1179                 }
1180         }
1181
1182         return insn->reloc;
1183 }
1184
1185 static void remove_insn_ops(struct instruction *insn)
1186 {
1187         struct stack_op *op, *tmp;
1188
1189         list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
1190                 list_del(&op->list);
1191                 free(op);
1192         }
1193 }
1194
1195 static void annotate_call_site(struct objtool_file *file,
1196                                struct instruction *insn, bool sibling)
1197 {
1198         struct reloc *reloc = insn_reloc(file, insn);
1199         struct symbol *sym = insn->call_dest;
1200
1201         if (!sym)
1202                 sym = reloc->sym;
1203
1204         /*
1205          * Alternative replacement code is just template code which is
1206          * sometimes copied to the original instruction. For now, don't
1207          * annotate it. (In the future we might consider annotating the
1208          * original instruction if/when it ever makes sense to do so.)
1209          */
1210         if (!strcmp(insn->sec->name, ".altinstr_replacement"))
1211                 return;
1212
1213         if (sym->static_call_tramp) {
1214                 list_add_tail(&insn->call_node, &file->static_call_list);
1215                 return;
1216         }
1217
1218         if (sym->retpoline_thunk) {
1219                 list_add_tail(&insn->call_node, &file->retpoline_call_list);
1220                 return;
1221         }
1222
1223         /*
1224          * Many compilers cannot disable KCOV or sanitizer calls with a function
1225          * attribute so they need a little help, NOP out any such calls from
1226          * noinstr text.
1227          */
1228         if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
1229                 if (reloc) {
1230                         reloc->type = R_NONE;
1231                         elf_write_reloc(file->elf, reloc);
1232                 }
1233
1234                 elf_write_insn(file->elf, insn->sec,
1235                                insn->offset, insn->len,
1236                                sibling ? arch_ret_insn(insn->len)
1237                                        : arch_nop_insn(insn->len));
1238
1239                 insn->type = sibling ? INSN_RETURN : INSN_NOP;
1240
1241                 if (sibling) {
1242                         /*
1243                          * We've replaced the tail-call JMP insn by two new
1244                          * insn: RET; INT3, except we only have a single struct
1245                          * insn here. Mark it retpoline_safe to avoid the SLS
1246                          * warning, instead of adding another insn.
1247                          */
1248                         insn->retpoline_safe = true;
1249                 }
1250
1251                 return;
1252         }
1253
1254         if (opts.mcount && sym->fentry) {
1255                 if (sibling)
1256                         WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset);
1257
1258                 if (reloc) {
1259                         reloc->type = R_NONE;
1260                         elf_write_reloc(file->elf, reloc);
1261                 }
1262
1263                 elf_write_insn(file->elf, insn->sec,
1264                                insn->offset, insn->len,
1265                                arch_nop_insn(insn->len));
1266
1267                 insn->type = INSN_NOP;
1268
1269                 list_add_tail(&insn->call_node, &file->mcount_loc_list);
1270                 return;
1271         }
1272
1273         if (!sibling && dead_end_function(file, sym))
1274                 insn->dead_end = true;
1275 }
1276
1277 static void add_call_dest(struct objtool_file *file, struct instruction *insn,
1278                           struct symbol *dest, bool sibling)
1279 {
1280         insn->call_dest = dest;
1281         if (!dest)
1282                 return;
1283
1284         /*
1285          * Whatever stack impact regular CALLs have, should be undone
1286          * by the RETURN of the called function.
1287          *
1288          * Annotated intra-function calls retain the stack_ops but
1289          * are converted to JUMP, see read_intra_function_calls().
1290          */
1291         remove_insn_ops(insn);
1292
1293         annotate_call_site(file, insn, sibling);
1294 }
1295
1296 static void add_retpoline_call(struct objtool_file *file, struct instruction *insn)
1297 {
1298         /*
1299          * Retpoline calls/jumps are really dynamic calls/jumps in disguise,
1300          * so convert them accordingly.
1301          */
1302         switch (insn->type) {
1303         case INSN_CALL:
1304                 insn->type = INSN_CALL_DYNAMIC;
1305                 break;
1306         case INSN_JUMP_UNCONDITIONAL:
1307                 insn->type = INSN_JUMP_DYNAMIC;
1308                 break;
1309         case INSN_JUMP_CONDITIONAL:
1310                 insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
1311                 break;
1312         default:
1313                 return;
1314         }
1315
1316         insn->retpoline_safe = true;
1317
1318         /*
1319          * Whatever stack impact regular CALLs have, should be undone
1320          * by the RETURN of the called function.
1321          *
1322          * Annotated intra-function calls retain the stack_ops but
1323          * are converted to JUMP, see read_intra_function_calls().
1324          */
1325         remove_insn_ops(insn);
1326
1327         annotate_call_site(file, insn, false);
1328 }
1329
1330 static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
1331 {
1332         /*
1333          * Return thunk tail calls are really just returns in disguise,
1334          * so convert them accordingly.
1335          */
1336         insn->type = INSN_RETURN;
1337         insn->retpoline_safe = true;
1338
1339         if (add)
1340                 list_add_tail(&insn->call_node, &file->return_thunk_list);
1341 }
1342
1343 static bool same_function(struct instruction *insn1, struct instruction *insn2)
1344 {
1345         return insn1->func->pfunc == insn2->func->pfunc;
1346 }
1347
1348 static bool is_first_func_insn(struct objtool_file *file, struct instruction *insn)
1349 {
1350         if (insn->offset == insn->func->offset)
1351                 return true;
1352
1353         if (opts.ibt) {
1354                 struct instruction *prev = prev_insn_same_sym(file, insn);
1355
1356                 if (prev && prev->type == INSN_ENDBR &&
1357                     insn->offset == insn->func->offset + prev->len)
1358                         return true;
1359         }
1360
1361         return false;
1362 }
1363
1364 /*
1365  * Find the destination instructions for all jumps.
1366  */
1367 static int add_jump_destinations(struct objtool_file *file)
1368 {
1369         struct instruction *insn, *jump_dest;
1370         struct reloc *reloc;
1371         struct section *dest_sec;
1372         unsigned long dest_off;
1373
1374         for_each_insn(file, insn) {
1375                 if (insn->jump_dest) {
1376                         /*
1377                          * handle_group_alt() may have previously set
1378                          * 'jump_dest' for some alternatives.
1379                          */
1380                         continue;
1381                 }
1382                 if (!is_static_jump(insn))
1383                         continue;
1384
1385                 reloc = insn_reloc(file, insn);
1386                 if (!reloc) {
1387                         dest_sec = insn->sec;
1388                         dest_off = arch_jump_destination(insn);
1389                 } else if (reloc->sym->type == STT_SECTION) {
1390                         dest_sec = reloc->sym->sec;
1391                         dest_off = arch_dest_reloc_offset(reloc->addend);
1392                 } else if (reloc->sym->retpoline_thunk) {
1393                         add_retpoline_call(file, insn);
1394                         continue;
1395                 } else if (reloc->sym->return_thunk) {
1396                         add_return_call(file, insn, true);
1397                         continue;
1398                 } else if (insn->func) {
1399                         /*
1400                          * External sibling call or internal sibling call with
1401                          * STT_FUNC reloc.
1402                          */
1403                         add_call_dest(file, insn, reloc->sym, true);
1404                         continue;
1405                 } else if (reloc->sym->sec->idx) {
1406                         dest_sec = reloc->sym->sec;
1407                         dest_off = reloc->sym->sym.st_value +
1408                                    arch_dest_reloc_offset(reloc->addend);
1409                 } else {
1410                         /* non-func asm code jumping to another file */
1411                         continue;
1412                 }
1413
1414                 jump_dest = find_insn(file, dest_sec, dest_off);
1415                 if (!jump_dest) {
1416                         struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
1417
1418                         /*
1419                          * This is a special case for zen_untrain_ret().
1420                          * It jumps to __x86_return_thunk(), but objtool
1421                          * can't find the thunk's starting RET
1422                          * instruction, because the RET is also in the
1423                          * middle of another instruction.  Objtool only
1424                          * knows about the outer instruction.
1425                          */
1426                         if (sym && sym->return_thunk) {
1427                                 add_return_call(file, insn, false);
1428                                 continue;
1429                         }
1430
1431                         WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
1432                                   insn->sec, insn->offset, dest_sec->name,
1433                                   dest_off);
1434                         return -1;
1435                 }
1436
1437                 /*
1438                  * Cross-function jump.
1439                  */
1440                 if (insn->func && jump_dest->func &&
1441                     insn->func != jump_dest->func) {
1442
1443                         /*
1444                          * For GCC 8+, create parent/child links for any cold
1445                          * subfunctions.  This is _mostly_ redundant with a
1446                          * similar initialization in read_symbols().
1447                          *
1448                          * If a function has aliases, we want the *first* such
1449                          * function in the symbol table to be the subfunction's
1450                          * parent.  In that case we overwrite the
1451                          * initialization done in read_symbols().
1452                          *
1453                          * However this code can't completely replace the
1454                          * read_symbols() code because this doesn't detect the
1455                          * case where the parent function's only reference to a
1456                          * subfunction is through a jump table.
1457                          */
1458                         if (!strstr(insn->func->name, ".cold") &&
1459                             strstr(jump_dest->func->name, ".cold")) {
1460                                 insn->func->cfunc = jump_dest->func;
1461                                 jump_dest->func->pfunc = insn->func;
1462
1463                         } else if (!same_function(insn, jump_dest) &&
1464                                    is_first_func_insn(file, jump_dest)) {
1465                                 /*
1466                                  * Internal sibling call without reloc or with
1467                                  * STT_SECTION reloc.
1468                                  */
1469                                 add_call_dest(file, insn, jump_dest->func, true);
1470                                 continue;
1471                         }
1472                 }
1473
1474                 insn->jump_dest = jump_dest;
1475         }
1476
1477         return 0;
1478 }
1479
1480 static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
1481 {
1482         struct symbol *call_dest;
1483
1484         call_dest = find_func_by_offset(sec, offset);
1485         if (!call_dest)
1486                 call_dest = find_symbol_by_offset(sec, offset);
1487
1488         return call_dest;
1489 }
1490
1491 /*
1492  * Find the destination instructions for all calls.
1493  */
1494 static int add_call_destinations(struct objtool_file *file)
1495 {
1496         struct instruction *insn;
1497         unsigned long dest_off;
1498         struct symbol *dest;
1499         struct reloc *reloc;
1500
1501         for_each_insn(file, insn) {
1502                 if (insn->type != INSN_CALL)
1503                         continue;
1504
1505                 reloc = insn_reloc(file, insn);
1506                 if (!reloc) {
1507                         dest_off = arch_jump_destination(insn);
1508                         dest = find_call_destination(insn->sec, dest_off);
1509
1510                         add_call_dest(file, insn, dest, false);
1511
1512                         if (insn->ignore)
1513                                 continue;
1514
1515                         if (!insn->call_dest) {
1516                                 WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);
1517                                 return -1;
1518                         }
1519
1520                         if (insn->func && insn->call_dest->type != STT_FUNC) {
1521                                 WARN_FUNC("unsupported call to non-function",
1522                                           insn->sec, insn->offset);
1523                                 return -1;
1524                         }
1525
1526                 } else if (reloc->sym->type == STT_SECTION) {
1527                         dest_off = arch_dest_reloc_offset(reloc->addend);
1528                         dest = find_call_destination(reloc->sym->sec, dest_off);
1529                         if (!dest) {
1530                                 WARN_FUNC("can't find call dest symbol at %s+0x%lx",
1531                                           insn->sec, insn->offset,
1532                                           reloc->sym->sec->name,
1533                                           dest_off);
1534                                 return -1;
1535                         }
1536
1537                         add_call_dest(file, insn, dest, false);
1538
1539                 } else if (reloc->sym->retpoline_thunk) {
1540                         add_retpoline_call(file, insn);
1541
1542                 } else
1543                         add_call_dest(file, insn, reloc->sym, false);
1544         }
1545
1546         return 0;
1547 }
1548
1549 /*
1550  * The .alternatives section requires some extra special care over and above
1551  * other special sections because alternatives are patched in place.
1552  */
1553 static int handle_group_alt(struct objtool_file *file,
1554                             struct special_alt *special_alt,
1555                             struct instruction *orig_insn,
1556                             struct instruction **new_insn)
1557 {
1558         struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL;
1559         struct alt_group *orig_alt_group, *new_alt_group;
1560         unsigned long dest_off;
1561
1562
1563         orig_alt_group = malloc(sizeof(*orig_alt_group));
1564         if (!orig_alt_group) {
1565                 WARN("malloc failed");
1566                 return -1;
1567         }
1568         orig_alt_group->cfi = calloc(special_alt->orig_len,
1569                                      sizeof(struct cfi_state *));
1570         if (!orig_alt_group->cfi) {
1571                 WARN("calloc failed");
1572                 return -1;
1573         }
1574
1575         last_orig_insn = NULL;
1576         insn = orig_insn;
1577         sec_for_each_insn_from(file, insn) {
1578                 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
1579                         break;
1580
1581                 insn->alt_group = orig_alt_group;
1582                 last_orig_insn = insn;
1583         }
1584         orig_alt_group->orig_group = NULL;
1585         orig_alt_group->first_insn = orig_insn;
1586         orig_alt_group->last_insn = last_orig_insn;
1587
1588
1589         new_alt_group = malloc(sizeof(*new_alt_group));
1590         if (!new_alt_group) {
1591                 WARN("malloc failed");
1592                 return -1;
1593         }
1594
1595         if (special_alt->new_len < special_alt->orig_len) {
1596                 /*
1597                  * Insert a fake nop at the end to make the replacement
1598                  * alt_group the same size as the original.  This is needed to
1599                  * allow propagate_alt_cfi() to do its magic.  When the last
1600                  * instruction affects the stack, the instruction after it (the
1601                  * nop) will propagate the new state to the shared CFI array.
1602                  */
1603                 nop = malloc(sizeof(*nop));
1604                 if (!nop) {
1605                         WARN("malloc failed");
1606                         return -1;
1607                 }
1608                 memset(nop, 0, sizeof(*nop));
1609                 INIT_LIST_HEAD(&nop->alts);
1610                 INIT_LIST_HEAD(&nop->stack_ops);
1611
1612                 nop->sec = special_alt->new_sec;
1613                 nop->offset = special_alt->new_off + special_alt->new_len;
1614                 nop->len = special_alt->orig_len - special_alt->new_len;
1615                 nop->type = INSN_NOP;
1616                 nop->func = orig_insn->func;
1617                 nop->alt_group = new_alt_group;
1618                 nop->ignore = orig_insn->ignore_alts;
1619         }
1620
1621         if (!special_alt->new_len) {
1622                 *new_insn = nop;
1623                 goto end;
1624         }
1625
1626         insn = *new_insn;
1627         sec_for_each_insn_from(file, insn) {
1628                 struct reloc *alt_reloc;
1629
1630                 if (insn->offset >= special_alt->new_off + special_alt->new_len)
1631                         break;
1632
1633                 last_new_insn = insn;
1634
1635                 insn->ignore = orig_insn->ignore_alts;
1636                 insn->func = orig_insn->func;
1637                 insn->alt_group = new_alt_group;
1638
1639                 /*
1640                  * Since alternative replacement code is copy/pasted by the
1641                  * kernel after applying relocations, generally such code can't
1642                  * have relative-address relocation references to outside the
1643                  * .altinstr_replacement section, unless the arch's
1644                  * alternatives code can adjust the relative offsets
1645                  * accordingly.
1646                  */
1647                 alt_reloc = insn_reloc(file, insn);
1648                 if (alt_reloc &&
1649                     !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
1650
1651                         WARN_FUNC("unsupported relocation in alternatives section",
1652                                   insn->sec, insn->offset);
1653                         return -1;
1654                 }
1655
1656                 if (!is_static_jump(insn))
1657                         continue;
1658
1659                 if (!insn->immediate)
1660                         continue;
1661
1662                 dest_off = arch_jump_destination(insn);
1663                 if (dest_off == special_alt->new_off + special_alt->new_len) {
1664                         insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
1665                         if (!insn->jump_dest) {
1666                                 WARN_FUNC("can't find alternative jump destination",
1667                                           insn->sec, insn->offset);
1668                                 return -1;
1669                         }
1670                 }
1671         }
1672
1673         if (!last_new_insn) {
1674                 WARN_FUNC("can't find last new alternative instruction",
1675                           special_alt->new_sec, special_alt->new_off);
1676                 return -1;
1677         }
1678
1679         if (nop)
1680                 list_add(&nop->list, &last_new_insn->list);
1681 end:
1682         new_alt_group->orig_group = orig_alt_group;
1683         new_alt_group->first_insn = *new_insn;
1684         new_alt_group->last_insn = nop ? : last_new_insn;
1685         new_alt_group->cfi = orig_alt_group->cfi;
1686         return 0;
1687 }
1688
1689 /*
1690  * A jump table entry can either convert a nop to a jump or a jump to a nop.
1691  * If the original instruction is a jump, make the alt entry an effective nop
1692  * by just skipping the original instruction.
1693  */
1694 static int handle_jump_alt(struct objtool_file *file,
1695                            struct special_alt *special_alt,
1696                            struct instruction *orig_insn,
1697                            struct instruction **new_insn)
1698 {
1699         if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
1700             orig_insn->type != INSN_NOP) {
1701
1702                 WARN_FUNC("unsupported instruction at jump label",
1703                           orig_insn->sec, orig_insn->offset);
1704                 return -1;
1705         }
1706
1707         if (opts.hack_jump_label && special_alt->key_addend & 2) {
1708                 struct reloc *reloc = insn_reloc(file, orig_insn);
1709
1710                 if (reloc) {
1711                         reloc->type = R_NONE;
1712                         elf_write_reloc(file->elf, reloc);
1713                 }
1714                 elf_write_insn(file->elf, orig_insn->sec,
1715                                orig_insn->offset, orig_insn->len,
1716                                arch_nop_insn(orig_insn->len));
1717                 orig_insn->type = INSN_NOP;
1718         }
1719
1720         if (orig_insn->type == INSN_NOP) {
1721                 if (orig_insn->len == 2)
1722                         file->jl_nop_short++;
1723                 else
1724                         file->jl_nop_long++;
1725
1726                 return 0;
1727         }
1728
1729         if (orig_insn->len == 2)
1730                 file->jl_short++;
1731         else
1732                 file->jl_long++;
1733
1734         *new_insn = list_next_entry(orig_insn, list);
1735         return 0;
1736 }
1737
1738 /*
1739  * Read all the special sections which have alternate instructions which can be
1740  * patched in or redirected to at runtime.  Each instruction having alternate
1741  * instruction(s) has them added to its insn->alts list, which will be
1742  * traversed in validate_branch().
1743  */
1744 static int add_special_section_alts(struct objtool_file *file)
1745 {
1746         struct list_head special_alts;
1747         struct instruction *orig_insn, *new_insn;
1748         struct special_alt *special_alt, *tmp;
1749         struct alternative *alt;
1750         int ret;
1751
1752         ret = special_get_alts(file->elf, &special_alts);
1753         if (ret)
1754                 return ret;
1755
1756         list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
1757
1758                 orig_insn = find_insn(file, special_alt->orig_sec,
1759                                       special_alt->orig_off);
1760                 if (!orig_insn) {
1761                         WARN_FUNC("special: can't find orig instruction",
1762                                   special_alt->orig_sec, special_alt->orig_off);
1763                         ret = -1;
1764                         goto out;
1765                 }
1766
1767                 new_insn = NULL;
1768                 if (!special_alt->group || special_alt->new_len) {
1769                         new_insn = find_insn(file, special_alt->new_sec,
1770                                              special_alt->new_off);
1771                         if (!new_insn) {
1772                                 WARN_FUNC("special: can't find new instruction",
1773                                           special_alt->new_sec,
1774                                           special_alt->new_off);
1775                                 ret = -1;
1776                                 goto out;
1777                         }
1778                 }
1779
1780                 if (special_alt->group) {
1781                         if (!special_alt->orig_len) {
1782                                 WARN_FUNC("empty alternative entry",
1783                                           orig_insn->sec, orig_insn->offset);
1784                                 continue;
1785                         }
1786
1787                         ret = handle_group_alt(file, special_alt, orig_insn,
1788                                                &new_insn);
1789                         if (ret)
1790                                 goto out;
1791                 } else if (special_alt->jump_or_nop) {
1792                         ret = handle_jump_alt(file, special_alt, orig_insn,
1793                                               &new_insn);
1794                         if (ret)
1795                                 goto out;
1796                 }
1797
1798                 alt = malloc(sizeof(*alt));
1799                 if (!alt) {
1800                         WARN("malloc failed");
1801                         ret = -1;
1802                         goto out;
1803                 }
1804
1805                 alt->insn = new_insn;
1806                 alt->skip_orig = special_alt->skip_orig;
1807                 orig_insn->ignore_alts |= special_alt->skip_alt;
1808                 list_add_tail(&alt->list, &orig_insn->alts);
1809
1810                 list_del(&special_alt->list);
1811                 free(special_alt);
1812         }
1813
1814         if (opts.stats) {
1815                 printf("jl\\\tNOP\tJMP\n");
1816                 printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
1817                 printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
1818         }
1819
1820 out:
1821         return ret;
1822 }
1823
1824 static int add_jump_table(struct objtool_file *file, struct instruction *insn,
1825                             struct reloc *table)
1826 {
1827         struct reloc *reloc = table;
1828         struct instruction *dest_insn;
1829         struct alternative *alt;
1830         struct symbol *pfunc = insn->func->pfunc;
1831         unsigned int prev_offset = 0;
1832
1833         /*
1834          * Each @reloc is a switch table relocation which points to the target
1835          * instruction.
1836          */
1837         list_for_each_entry_from(reloc, &table->sec->reloc_list, list) {
1838
1839                 /* Check for the end of the table: */
1840                 if (reloc != table && reloc->jump_table_start)
1841                         break;
1842
1843                 /* Make sure the table entries are consecutive: */
1844                 if (prev_offset && reloc->offset != prev_offset + 8)
1845                         break;
1846
1847                 /* Detect function pointers from contiguous objects: */
1848                 if (reloc->sym->sec == pfunc->sec &&
1849                     reloc->addend == pfunc->offset)
1850                         break;
1851
1852                 dest_insn = find_insn(file, reloc->sym->sec, reloc->addend);
1853                 if (!dest_insn)
1854                         break;
1855
1856                 /* Make sure the destination is in the same function: */
1857                 if (!dest_insn->func || dest_insn->func->pfunc != pfunc)
1858                         break;
1859
1860                 alt = malloc(sizeof(*alt));
1861                 if (!alt) {
1862                         WARN("malloc failed");
1863                         return -1;
1864                 }
1865
1866                 alt->insn = dest_insn;
1867                 list_add_tail(&alt->list, &insn->alts);
1868                 prev_offset = reloc->offset;
1869         }
1870
1871         if (!prev_offset) {
1872                 WARN_FUNC("can't find switch jump table",
1873                           insn->sec, insn->offset);
1874                 return -1;
1875         }
1876
1877         return 0;
1878 }
1879
1880 /*
1881  * find_jump_table() - Given a dynamic jump, find the switch jump table
1882  * associated with it.
1883  */
1884 static struct reloc *find_jump_table(struct objtool_file *file,
1885                                       struct symbol *func,
1886                                       struct instruction *insn)
1887 {
1888         struct reloc *table_reloc;
1889         struct instruction *dest_insn, *orig_insn = insn;
1890
1891         /*
1892          * Backward search using the @first_jump_src links, these help avoid
1893          * much of the 'in between' code. Which avoids us getting confused by
1894          * it.
1895          */
1896         for (;
1897              insn && insn->func && insn->func->pfunc == func;
1898              insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
1899
1900                 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
1901                         break;
1902
1903                 /* allow small jumps within the range */
1904                 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
1905                     insn->jump_dest &&
1906                     (insn->jump_dest->offset <= insn->offset ||
1907                      insn->jump_dest->offset > orig_insn->offset))
1908                     break;
1909
1910                 table_reloc = arch_find_switch_table(file, insn);
1911                 if (!table_reloc)
1912                         continue;
1913                 dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
1914                 if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
1915                         continue;
1916
1917                 return table_reloc;
1918         }
1919
1920         return NULL;
1921 }
1922
1923 /*
1924  * First pass: Mark the head of each jump table so that in the next pass,
1925  * we know when a given jump table ends and the next one starts.
1926  */
1927 static void mark_func_jump_tables(struct objtool_file *file,
1928                                     struct symbol *func)
1929 {
1930         struct instruction *insn, *last = NULL;
1931         struct reloc *reloc;
1932
1933         func_for_each_insn(file, func, insn) {
1934                 if (!last)
1935                         last = insn;
1936
1937                 /*
1938                  * Store back-pointers for unconditional forward jumps such
1939                  * that find_jump_table() can back-track using those and
1940                  * avoid some potentially confusing code.
1941                  */
1942                 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
1943                     insn->offset > last->offset &&
1944                     insn->jump_dest->offset > insn->offset &&
1945                     !insn->jump_dest->first_jump_src) {
1946
1947                         insn->jump_dest->first_jump_src = insn;
1948                         last = insn->jump_dest;
1949                 }
1950
1951                 if (insn->type != INSN_JUMP_DYNAMIC)
1952                         continue;
1953
1954                 reloc = find_jump_table(file, func, insn);
1955                 if (reloc) {
1956                         reloc->jump_table_start = true;
1957                         insn->jump_table = reloc;
1958                 }
1959         }
1960 }
1961
1962 static int add_func_jump_tables(struct objtool_file *file,
1963                                   struct symbol *func)
1964 {
1965         struct instruction *insn;
1966         int ret;
1967
1968         func_for_each_insn(file, func, insn) {
1969                 if (!insn->jump_table)
1970                         continue;
1971
1972                 ret = add_jump_table(file, insn, insn->jump_table);
1973                 if (ret)
1974                         return ret;
1975         }
1976
1977         return 0;
1978 }
1979
1980 /*
1981  * For some switch statements, gcc generates a jump table in the .rodata
1982  * section which contains a list of addresses within the function to jump to.
1983  * This finds these jump tables and adds them to the insn->alts lists.
1984  */
1985 static int add_jump_table_alts(struct objtool_file *file)
1986 {
1987         struct section *sec;
1988         struct symbol *func;
1989         int ret;
1990
1991         if (!file->rodata)
1992                 return 0;
1993
1994         for_each_sec(file, sec) {
1995                 list_for_each_entry(func, &sec->symbol_list, list) {
1996                         if (func->type != STT_FUNC)
1997                                 continue;
1998
1999                         mark_func_jump_tables(file, func);
2000                         ret = add_func_jump_tables(file, func);
2001                         if (ret)
2002                                 return ret;
2003                 }
2004         }
2005
2006         return 0;
2007 }
2008
2009 static void set_func_state(struct cfi_state *state)
2010 {
2011         state->cfa = initial_func_cfi.cfa;
2012         memcpy(&state->regs, &initial_func_cfi.regs,
2013                CFI_NUM_REGS * sizeof(struct cfi_reg));
2014         state->stack_size = initial_func_cfi.cfa.offset;
2015 }
2016
2017 static int read_unwind_hints(struct objtool_file *file)
2018 {
2019         struct cfi_state cfi = init_cfi;
2020         struct section *sec, *relocsec;
2021         struct unwind_hint *hint;
2022         struct instruction *insn;
2023         struct reloc *reloc;
2024         int i;
2025
2026         sec = find_section_by_name(file->elf, ".discard.unwind_hints");
2027         if (!sec)
2028                 return 0;
2029
2030         relocsec = sec->reloc;
2031         if (!relocsec) {
2032                 WARN("missing .rela.discard.unwind_hints section");
2033                 return -1;
2034         }
2035
2036         if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
2037                 WARN("struct unwind_hint size mismatch");
2038                 return -1;
2039         }
2040
2041         file->hints = true;
2042
2043         for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
2044                 hint = (struct unwind_hint *)sec->data->d_buf + i;
2045
2046                 reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
2047                 if (!reloc) {
2048                         WARN("can't find reloc for unwind_hints[%d]", i);
2049                         return -1;
2050                 }
2051
2052                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2053                 if (!insn) {
2054                         WARN("can't find insn for unwind_hints[%d]", i);
2055                         return -1;
2056                 }
2057
2058                 insn->hint = true;
2059
2060                 if (hint->type == UNWIND_HINT_TYPE_SAVE) {
2061                         insn->hint = false;
2062                         insn->save = true;
2063                         continue;
2064                 }
2065
2066                 if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
2067                         insn->restore = true;
2068                         continue;
2069                 }
2070
2071                 if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
2072                         struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
2073
2074                         if (sym && sym->bind == STB_GLOBAL) {
2075                                 if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
2076                                         WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR",
2077                                                   insn->sec, insn->offset);
2078                                 }
2079
2080                                 insn->entry = 1;
2081                         }
2082                 }
2083
2084                 if (hint->type == UNWIND_HINT_TYPE_ENTRY) {
2085                         hint->type = UNWIND_HINT_TYPE_CALL;
2086                         insn->entry = 1;
2087                 }
2088
2089                 if (hint->type == UNWIND_HINT_TYPE_FUNC) {
2090                         insn->cfi = &func_cfi;
2091                         continue;
2092                 }
2093
2094                 if (insn->cfi)
2095                         cfi = *(insn->cfi);
2096
2097                 if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
2098                         WARN_FUNC("unsupported unwind_hint sp base reg %d",
2099                                   insn->sec, insn->offset, hint->sp_reg);
2100                         return -1;
2101                 }
2102
2103                 cfi.cfa.offset = bswap_if_needed(hint->sp_offset);
2104                 cfi.type = hint->type;
2105                 cfi.end = hint->end;
2106
2107                 insn->cfi = cfi_hash_find_or_add(&cfi);
2108         }
2109
2110         return 0;
2111 }
2112
2113 static int read_noendbr_hints(struct objtool_file *file)
2114 {
2115         struct section *sec;
2116         struct instruction *insn;
2117         struct reloc *reloc;
2118
2119         sec = find_section_by_name(file->elf, ".rela.discard.noendbr");
2120         if (!sec)
2121                 return 0;
2122
2123         list_for_each_entry(reloc, &sec->reloc_list, list) {
2124                 insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend);
2125                 if (!insn) {
2126                         WARN("bad .discard.noendbr entry");
2127                         return -1;
2128                 }
2129
2130                 insn->noendbr = 1;
2131         }
2132
2133         return 0;
2134 }
2135
2136 static int read_retpoline_hints(struct objtool_file *file)
2137 {
2138         struct section *sec;
2139         struct instruction *insn;
2140         struct reloc *reloc;
2141
2142         sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
2143         if (!sec)
2144                 return 0;
2145
2146         list_for_each_entry(reloc, &sec->reloc_list, list) {
2147                 if (reloc->sym->type != STT_SECTION) {
2148                         WARN("unexpected relocation symbol type in %s", sec->name);
2149                         return -1;
2150                 }
2151
2152                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2153                 if (!insn) {
2154                         WARN("bad .discard.retpoline_safe entry");
2155                         return -1;
2156                 }
2157
2158                 if (insn->type != INSN_JUMP_DYNAMIC &&
2159                     insn->type != INSN_CALL_DYNAMIC &&
2160                     insn->type != INSN_RETURN &&
2161                     insn->type != INSN_NOP) {
2162                         WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret/nop",
2163                                   insn->sec, insn->offset);
2164                         return -1;
2165                 }
2166
2167                 insn->retpoline_safe = true;
2168         }
2169
2170         return 0;
2171 }
2172
2173 static int read_instr_hints(struct objtool_file *file)
2174 {
2175         struct section *sec;
2176         struct instruction *insn;
2177         struct reloc *reloc;
2178
2179         sec = find_section_by_name(file->elf, ".rela.discard.instr_end");
2180         if (!sec)
2181                 return 0;
2182
2183         list_for_each_entry(reloc, &sec->reloc_list, list) {
2184                 if (reloc->sym->type != STT_SECTION) {
2185                         WARN("unexpected relocation symbol type in %s", sec->name);
2186                         return -1;
2187                 }
2188
2189                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2190                 if (!insn) {
2191                         WARN("bad .discard.instr_end entry");
2192                         return -1;
2193                 }
2194
2195                 insn->instr--;
2196         }
2197
2198         sec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
2199         if (!sec)
2200                 return 0;
2201
2202         list_for_each_entry(reloc, &sec->reloc_list, list) {
2203                 if (reloc->sym->type != STT_SECTION) {
2204                         WARN("unexpected relocation symbol type in %s", sec->name);
2205                         return -1;
2206                 }
2207
2208                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2209                 if (!insn) {
2210                         WARN("bad .discard.instr_begin entry");
2211                         return -1;
2212                 }
2213
2214                 insn->instr++;
2215         }
2216
2217         return 0;
2218 }
2219
2220 static int read_intra_function_calls(struct objtool_file *file)
2221 {
2222         struct instruction *insn;
2223         struct section *sec;
2224         struct reloc *reloc;
2225
2226         sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
2227         if (!sec)
2228                 return 0;
2229
2230         list_for_each_entry(reloc, &sec->reloc_list, list) {
2231                 unsigned long dest_off;
2232
2233                 if (reloc->sym->type != STT_SECTION) {
2234                         WARN("unexpected relocation symbol type in %s",
2235                              sec->name);
2236                         return -1;
2237                 }
2238
2239                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2240                 if (!insn) {
2241                         WARN("bad .discard.intra_function_call entry");
2242                         return -1;
2243                 }
2244
2245                 if (insn->type != INSN_CALL) {
2246                         WARN_FUNC("intra_function_call not a direct call",
2247                                   insn->sec, insn->offset);
2248                         return -1;
2249                 }
2250
2251                 /*
2252                  * Treat intra-function CALLs as JMPs, but with a stack_op.
2253                  * See add_call_destinations(), which strips stack_ops from
2254                  * normal CALLs.
2255                  */
2256                 insn->type = INSN_JUMP_UNCONDITIONAL;
2257
2258                 dest_off = arch_jump_destination(insn);
2259                 insn->jump_dest = find_insn(file, insn->sec, dest_off);
2260                 if (!insn->jump_dest) {
2261                         WARN_FUNC("can't find call dest at %s+0x%lx",
2262                                   insn->sec, insn->offset,
2263                                   insn->sec->name, dest_off);
2264                         return -1;
2265                 }
2266         }
2267
2268         return 0;
2269 }
2270
2271 /*
2272  * Return true if name matches an instrumentation function, where calls to that
2273  * function from noinstr code can safely be removed, but compilers won't do so.
2274  */
2275 static bool is_profiling_func(const char *name)
2276 {
2277         /*
2278          * Many compilers cannot disable KCOV with a function attribute.
2279          */
2280         if (!strncmp(name, "__sanitizer_cov_", 16))
2281                 return true;
2282
2283         /*
2284          * Some compilers currently do not remove __tsan_func_entry/exit nor
2285          * __tsan_atomic_signal_fence (used for barrier instrumentation) with
2286          * the __no_sanitize_thread attribute, remove them. Once the kernel's
2287          * minimum Clang version is 14.0, this can be removed.
2288          */
2289         if (!strncmp(name, "__tsan_func_", 12) ||
2290             !strcmp(name, "__tsan_atomic_signal_fence"))
2291                 return true;
2292
2293         return false;
2294 }
2295
2296 static int classify_symbols(struct objtool_file *file)
2297 {
2298         struct section *sec;
2299         struct symbol *func;
2300
2301         for_each_sec(file, sec) {
2302                 list_for_each_entry(func, &sec->symbol_list, list) {
2303                         if (func->bind != STB_GLOBAL)
2304                                 continue;
2305
2306                         if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
2307                                      strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
2308                                 func->static_call_tramp = true;
2309
2310                         if (arch_is_retpoline(func))
2311                                 func->retpoline_thunk = true;
2312
2313                         if (arch_is_rethunk(func))
2314                                 func->return_thunk = true;
2315
2316                         if (!strcmp(func->name, "__fentry__"))
2317                                 func->fentry = true;
2318
2319                         if (is_profiling_func(func->name))
2320                                 func->profiling_func = true;
2321                 }
2322         }
2323
2324         return 0;
2325 }
2326
2327 static void mark_rodata(struct objtool_file *file)
2328 {
2329         struct section *sec;
2330         bool found = false;
2331
2332         /*
2333          * Search for the following rodata sections, each of which can
2334          * potentially contain jump tables:
2335          *
2336          * - .rodata: can contain GCC switch tables
2337          * - .rodata.<func>: same, if -fdata-sections is being used
2338          * - .rodata..c_jump_table: contains C annotated jump tables
2339          *
2340          * .rodata.str1.* sections are ignored; they don't contain jump tables.
2341          */
2342         for_each_sec(file, sec) {
2343                 if (!strncmp(sec->name, ".rodata", 7) &&
2344                     !strstr(sec->name, ".str1.")) {
2345                         sec->rodata = true;
2346                         found = true;
2347                 }
2348         }
2349
2350         file->rodata = found;
2351 }
2352
2353 static int decode_sections(struct objtool_file *file)
2354 {
2355         int ret;
2356
2357         mark_rodata(file);
2358
2359         ret = init_pv_ops(file);
2360         if (ret)
2361                 return ret;
2362
2363         ret = decode_instructions(file);
2364         if (ret)
2365                 return ret;
2366
2367         add_ignores(file);
2368         add_uaccess_safe(file);
2369
2370         ret = add_ignore_alternatives(file);
2371         if (ret)
2372                 return ret;
2373
2374         /*
2375          * Must be before read_unwind_hints() since that needs insn->noendbr.
2376          */
2377         ret = read_noendbr_hints(file);
2378         if (ret)
2379                 return ret;
2380
2381         /*
2382          * Must be before add_{jump_call}_destination.
2383          */
2384         ret = classify_symbols(file);
2385         if (ret)
2386                 return ret;
2387
2388         /*
2389          * Must be before add_jump_destinations(), which depends on 'func'
2390          * being set for alternatives, to enable proper sibling call detection.
2391          */
2392         ret = add_special_section_alts(file);
2393         if (ret)
2394                 return ret;
2395
2396         ret = add_jump_destinations(file);
2397         if (ret)
2398                 return ret;
2399
2400         /*
2401          * Must be before add_call_destination(); it changes INSN_CALL to
2402          * INSN_JUMP.
2403          */
2404         ret = read_intra_function_calls(file);
2405         if (ret)
2406                 return ret;
2407
2408         ret = add_call_destinations(file);
2409         if (ret)
2410                 return ret;
2411
2412         /*
2413          * Must be after add_call_destinations() such that it can override
2414          * dead_end_function() marks.
2415          */
2416         ret = add_dead_ends(file);
2417         if (ret)
2418                 return ret;
2419
2420         ret = add_jump_table_alts(file);
2421         if (ret)
2422                 return ret;
2423
2424         ret = read_unwind_hints(file);
2425         if (ret)
2426                 return ret;
2427
2428         ret = read_retpoline_hints(file);
2429         if (ret)
2430                 return ret;
2431
2432         ret = read_instr_hints(file);
2433         if (ret)
2434                 return ret;
2435
2436         return 0;
2437 }
2438
2439 static bool is_fentry_call(struct instruction *insn)
2440 {
2441         if (insn->type == INSN_CALL &&
2442             insn->call_dest &&
2443             insn->call_dest->fentry)
2444                 return true;
2445
2446         return false;
2447 }
2448
2449 static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
2450 {
2451         struct cfi_state *cfi = &state->cfi;
2452         int i;
2453
2454         if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
2455                 return true;
2456
2457         if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
2458                 return true;
2459
2460         if (cfi->stack_size != initial_func_cfi.cfa.offset)
2461                 return true;
2462
2463         for (i = 0; i < CFI_NUM_REGS; i++) {
2464                 if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
2465                     cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
2466                         return true;
2467         }
2468
2469         return false;
2470 }
2471
2472 static bool check_reg_frame_pos(const struct cfi_reg *reg,
2473                                 int expected_offset)
2474 {
2475         return reg->base == CFI_CFA &&
2476                reg->offset == expected_offset;
2477 }
2478
2479 static bool has_valid_stack_frame(struct insn_state *state)
2480 {
2481         struct cfi_state *cfi = &state->cfi;
2482
2483         if (cfi->cfa.base == CFI_BP &&
2484             check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
2485             check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
2486                 return true;
2487
2488         if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
2489                 return true;
2490
2491         return false;
2492 }
2493
2494 static int update_cfi_state_regs(struct instruction *insn,
2495                                   struct cfi_state *cfi,
2496                                   struct stack_op *op)
2497 {
2498         struct cfi_reg *cfa = &cfi->cfa;
2499
2500         if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
2501                 return 0;
2502
2503         /* push */
2504         if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
2505                 cfa->offset += 8;
2506
2507         /* pop */
2508         if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
2509                 cfa->offset -= 8;
2510
2511         /* add immediate to sp */
2512         if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
2513             op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
2514                 cfa->offset -= op->src.offset;
2515
2516         return 0;
2517 }
2518
2519 static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
2520 {
2521         if (arch_callee_saved_reg(reg) &&
2522             cfi->regs[reg].base == CFI_UNDEFINED) {
2523                 cfi->regs[reg].base = base;
2524                 cfi->regs[reg].offset = offset;
2525         }
2526 }
2527
2528 static void restore_reg(struct cfi_state *cfi, unsigned char reg)
2529 {
2530         cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
2531         cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
2532 }
2533
2534 /*
2535  * A note about DRAP stack alignment:
2536  *
2537  * GCC has the concept of a DRAP register, which is used to help keep track of
2538  * the stack pointer when aligning the stack.  r10 or r13 is used as the DRAP
2539  * register.  The typical DRAP pattern is:
2540  *
2541  *   4c 8d 54 24 08             lea    0x8(%rsp),%r10
2542  *   48 83 e4 c0                and    $0xffffffffffffffc0,%rsp
2543  *   41 ff 72 f8                pushq  -0x8(%r10)
2544  *   55                         push   %rbp
2545  *   48 89 e5                   mov    %rsp,%rbp
2546  *                              (more pushes)
2547  *   41 52                      push   %r10
2548  *                              ...
2549  *   41 5a                      pop    %r10
2550  *                              (more pops)
2551  *   5d                         pop    %rbp
2552  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
2553  *   c3                         retq
2554  *
2555  * There are some variations in the epilogues, like:
2556  *
2557  *   5b                         pop    %rbx
2558  *   41 5a                      pop    %r10
2559  *   41 5c                      pop    %r12
2560  *   41 5d                      pop    %r13
2561  *   41 5e                      pop    %r14
2562  *   c9                         leaveq
2563  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
2564  *   c3                         retq
2565  *
2566  * and:
2567  *
2568  *   4c 8b 55 e8                mov    -0x18(%rbp),%r10
2569  *   48 8b 5d e0                mov    -0x20(%rbp),%rbx
2570  *   4c 8b 65 f0                mov    -0x10(%rbp),%r12
2571  *   4c 8b 6d f8                mov    -0x8(%rbp),%r13
2572  *   c9                         leaveq
2573  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
2574  *   c3                         retq
2575  *
2576  * Sometimes r13 is used as the DRAP register, in which case it's saved and
2577  * restored beforehand:
2578  *
2579  *   41 55                      push   %r13
2580  *   4c 8d 6c 24 10             lea    0x10(%rsp),%r13
2581  *   48 83 e4 f0                and    $0xfffffffffffffff0,%rsp
2582  *                              ...
2583  *   49 8d 65 f0                lea    -0x10(%r13),%rsp
2584  *   41 5d                      pop    %r13
2585  *   c3                         retq
2586  */
2587 static int update_cfi_state(struct instruction *insn,
2588                             struct instruction *next_insn,
2589                             struct cfi_state *cfi, struct stack_op *op)
2590 {
2591         struct cfi_reg *cfa = &cfi->cfa;
2592         struct cfi_reg *regs = cfi->regs;
2593
2594         /* stack operations don't make sense with an undefined CFA */
2595         if (cfa->base == CFI_UNDEFINED) {
2596                 if (insn->func) {
2597                         WARN_FUNC("undefined stack state", insn->sec, insn->offset);
2598                         return -1;
2599                 }
2600                 return 0;
2601         }
2602
2603         if (cfi->type == UNWIND_HINT_TYPE_REGS ||
2604             cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
2605                 return update_cfi_state_regs(insn, cfi, op);
2606
2607         switch (op->dest.type) {
2608
2609         case OP_DEST_REG:
2610                 switch (op->src.type) {
2611
2612                 case OP_SRC_REG:
2613                         if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
2614                             cfa->base == CFI_SP &&
2615                             check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {
2616
2617                                 /* mov %rsp, %rbp */
2618                                 cfa->base = op->dest.reg;
2619                                 cfi->bp_scratch = false;
2620                         }
2621
2622                         else if (op->src.reg == CFI_SP &&
2623                                  op->dest.reg == CFI_BP && cfi->drap) {
2624
2625                                 /* drap: mov %rsp, %rbp */
2626                                 regs[CFI_BP].base = CFI_BP;
2627                                 regs[CFI_BP].offset = -cfi->stack_size;
2628                                 cfi->bp_scratch = false;
2629                         }
2630
2631                         else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2632
2633                                 /*
2634                                  * mov %rsp, %reg
2635                                  *
2636                                  * This is needed for the rare case where GCC
2637                                  * does:
2638                                  *
2639                                  *   mov    %rsp, %rax
2640                                  *   ...
2641                                  *   mov    %rax, %rsp
2642                                  */
2643                                 cfi->vals[op->dest.reg].base = CFI_CFA;
2644                                 cfi->vals[op->dest.reg].offset = -cfi->stack_size;
2645                         }
2646
2647                         else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
2648                                  (cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {
2649
2650                                 /*
2651                                  * mov %rbp, %rsp
2652                                  *
2653                                  * Restore the original stack pointer (Clang).
2654                                  */
2655                                 cfi->stack_size = -cfi->regs[CFI_BP].offset;
2656                         }
2657
2658                         else if (op->dest.reg == cfa->base) {
2659
2660                                 /* mov %reg, %rsp */
2661                                 if (cfa->base == CFI_SP &&
2662                                     cfi->vals[op->src.reg].base == CFI_CFA) {
2663
2664                                         /*
2665                                          * This is needed for the rare case
2666                                          * where GCC does something dumb like:
2667                                          *
2668                                          *   lea    0x8(%rsp), %rcx
2669                                          *   ...
2670                                          *   mov    %rcx, %rsp
2671                                          */
2672                                         cfa->offset = -cfi->vals[op->src.reg].offset;
2673                                         cfi->stack_size = cfa->offset;
2674
2675                                 } else if (cfa->base == CFI_SP &&
2676                                            cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2677                                            cfi->vals[op->src.reg].offset == cfa->offset) {
2678
2679                                         /*
2680                                          * Stack swizzle:
2681                                          *
2682                                          * 1: mov %rsp, (%[tos])
2683                                          * 2: mov %[tos], %rsp
2684                                          *    ...
2685                                          * 3: pop %rsp
2686                                          *
2687                                          * Where:
2688                                          *
2689                                          * 1 - places a pointer to the previous
2690                                          *     stack at the Top-of-Stack of the
2691                                          *     new stack.
2692                                          *
2693                                          * 2 - switches to the new stack.
2694                                          *
2695                                          * 3 - pops the Top-of-Stack to restore
2696                                          *     the original stack.
2697                                          *
2698                                          * Note: we set base to SP_INDIRECT
2699                                          * here and preserve offset. Therefore
2700                                          * when the unwinder reaches ToS it
2701                                          * will dereference SP and then add the
2702                                          * offset to find the next frame, IOW:
2703                                          * (%rsp) + offset.
2704                                          */
2705                                         cfa->base = CFI_SP_INDIRECT;
2706
2707                                 } else {
2708                                         cfa->base = CFI_UNDEFINED;
2709                                         cfa->offset = 0;
2710                                 }
2711                         }
2712
2713                         else if (op->dest.reg == CFI_SP &&
2714                                  cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2715                                  cfi->vals[op->src.reg].offset == cfa->offset) {
2716
2717                                 /*
2718                                  * The same stack swizzle case 2) as above. But
2719                                  * because we can't change cfa->base, case 3)
2720                                  * will become a regular POP. Pretend we're a
2721                                  * PUSH so things don't go unbalanced.
2722                                  */
2723                                 cfi->stack_size += 8;
2724                         }
2725
2726
2727                         break;
2728
2729                 case OP_SRC_ADD:
2730                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
2731
2732                                 /* add imm, %rsp */
2733                                 cfi->stack_size -= op->src.offset;
2734                                 if (cfa->base == CFI_SP)
2735                                         cfa->offset -= op->src.offset;
2736                                 break;
2737                         }
2738
2739                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
2740
2741                                 /* lea disp(%rbp), %rsp */
2742                                 cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
2743                                 break;
2744                         }
2745
2746                         if (!cfi->drap && op->src.reg == CFI_SP &&
2747                             op->dest.reg == CFI_BP && cfa->base == CFI_SP &&
2748                             check_reg_frame_pos(&regs[CFI_BP], -cfa->offset + op->src.offset)) {
2749
2750                                 /* lea disp(%rsp), %rbp */
2751                                 cfa->base = CFI_BP;
2752                                 cfa->offset -= op->src.offset;
2753                                 cfi->bp_scratch = false;
2754                                 break;
2755                         }
2756
2757                         if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2758
2759                                 /* drap: lea disp(%rsp), %drap */
2760                                 cfi->drap_reg = op->dest.reg;
2761
2762                                 /*
2763                                  * lea disp(%rsp), %reg
2764                                  *
2765                                  * This is needed for the rare case where GCC
2766                                  * does something dumb like:
2767                                  *
2768                                  *   lea    0x8(%rsp), %rcx
2769                                  *   ...
2770                                  *   mov    %rcx, %rsp
2771                                  */
2772                                 cfi->vals[op->dest.reg].base = CFI_CFA;
2773                                 cfi->vals[op->dest.reg].offset = \
2774                                         -cfi->stack_size + op->src.offset;
2775
2776                                 break;
2777                         }
2778
2779                         if (cfi->drap && op->dest.reg == CFI_SP &&
2780                             op->src.reg == cfi->drap_reg) {
2781
2782                                  /* drap: lea disp(%drap), %rsp */
2783                                 cfa->base = CFI_SP;
2784                                 cfa->offset = cfi->stack_size = -op->src.offset;
2785                                 cfi->drap_reg = CFI_UNDEFINED;
2786                                 cfi->drap = false;
2787                                 break;
2788                         }
2789
2790                         if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
2791                                 WARN_FUNC("unsupported stack register modification",
2792                                           insn->sec, insn->offset);
2793                                 return -1;
2794                         }
2795
2796                         break;
2797
2798                 case OP_SRC_AND:
2799                         if (op->dest.reg != CFI_SP ||
2800                             (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
2801                             (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
2802                                 WARN_FUNC("unsupported stack pointer realignment",
2803                                           insn->sec, insn->offset);
2804                                 return -1;
2805                         }
2806
2807                         if (cfi->drap_reg != CFI_UNDEFINED) {
2808                                 /* drap: and imm, %rsp */
2809                                 cfa->base = cfi->drap_reg;
2810                                 cfa->offset = cfi->stack_size = 0;
2811                                 cfi->drap = true;
2812                         }
2813
2814                         /*
2815                          * Older versions of GCC (4.8ish) realign the stack
2816                          * without DRAP, with a frame pointer.
2817                          */
2818
2819                         break;
2820
2821                 case OP_SRC_POP:
2822                 case OP_SRC_POPF:
2823                         if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
2824
2825                                 /* pop %rsp; # restore from a stack swizzle */
2826                                 cfa->base = CFI_SP;
2827                                 break;
2828                         }
2829
2830                         if (!cfi->drap && op->dest.reg == cfa->base) {
2831
2832                                 /* pop %rbp */
2833                                 cfa->base = CFI_SP;
2834                         }
2835
2836                         if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
2837                             op->dest.reg == cfi->drap_reg &&
2838                             cfi->drap_offset == -cfi->stack_size) {
2839
2840                                 /* drap: pop %drap */
2841                                 cfa->base = cfi->drap_reg;
2842                                 cfa->offset = 0;
2843                                 cfi->drap_offset = -1;
2844
2845                         } else if (cfi->stack_size == -regs[op->dest.reg].offset) {
2846
2847                                 /* pop %reg */
2848                                 restore_reg(cfi, op->dest.reg);
2849                         }
2850
2851                         cfi->stack_size -= 8;
2852                         if (cfa->base == CFI_SP)
2853                                 cfa->offset -= 8;
2854
2855                         break;
2856
2857                 case OP_SRC_REG_INDIRECT:
2858                         if (!cfi->drap && op->dest.reg == cfa->base &&
2859                             op->dest.reg == CFI_BP) {
2860
2861                                 /* mov disp(%rsp), %rbp */
2862                                 cfa->base = CFI_SP;
2863                                 cfa->offset = cfi->stack_size;
2864                         }
2865
2866                         if (cfi->drap && op->src.reg == CFI_BP &&
2867                             op->src.offset == cfi->drap_offset) {
2868
2869                                 /* drap: mov disp(%rbp), %drap */
2870                                 cfa->base = cfi->drap_reg;
2871                                 cfa->offset = 0;
2872                                 cfi->drap_offset = -1;
2873                         }
2874
2875                         if (cfi->drap && op->src.reg == CFI_BP &&
2876                             op->src.offset == regs[op->dest.reg].offset) {
2877
2878                                 /* drap: mov disp(%rbp), %reg */
2879                                 restore_reg(cfi, op->dest.reg);
2880
2881                         } else if (op->src.reg == cfa->base &&
2882                             op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
2883
2884                                 /* mov disp(%rbp), %reg */
2885                                 /* mov disp(%rsp), %reg */
2886                                 restore_reg(cfi, op->dest.reg);
2887
2888                         } else if (op->src.reg == CFI_SP &&
2889                                    op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
2890
2891                                 /* mov disp(%rsp), %reg */
2892                                 restore_reg(cfi, op->dest.reg);
2893                         }
2894
2895                         break;
2896
2897                 default:
2898                         WARN_FUNC("unknown stack-related instruction",
2899                                   insn->sec, insn->offset);
2900                         return -1;
2901                 }
2902
2903                 break;
2904
2905         case OP_DEST_PUSH:
2906         case OP_DEST_PUSHF:
2907                 cfi->stack_size += 8;
2908                 if (cfa->base == CFI_SP)
2909                         cfa->offset += 8;
2910
2911                 if (op->src.type != OP_SRC_REG)
2912                         break;
2913
2914                 if (cfi->drap) {
2915                         if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
2916
2917                                 /* drap: push %drap */
2918                                 cfa->base = CFI_BP_INDIRECT;
2919                                 cfa->offset = -cfi->stack_size;
2920
2921                                 /* save drap so we know when to restore it */
2922                                 cfi->drap_offset = -cfi->stack_size;
2923
2924                         } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
2925
2926                                 /* drap: push %rbp */
2927                                 cfi->stack_size = 0;
2928
2929                         } else {
2930
2931                                 /* drap: push %reg */
2932                                 save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
2933                         }
2934
2935                 } else {
2936
2937                         /* push %reg */
2938                         save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
2939                 }
2940
2941                 /* detect when asm code uses rbp as a scratch register */
2942                 if (opts.stackval && insn->func && op->src.reg == CFI_BP &&
2943                     cfa->base != CFI_BP)
2944                         cfi->bp_scratch = true;
2945                 break;
2946
2947         case OP_DEST_REG_INDIRECT:
2948
2949                 if (cfi->drap) {
2950                         if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
2951
2952                                 /* drap: mov %drap, disp(%rbp) */
2953                                 cfa->base = CFI_BP_INDIRECT;
2954                                 cfa->offset = op->dest.offset;
2955
2956                                 /* save drap offset so we know when to restore it */
2957                                 cfi->drap_offset = op->dest.offset;
2958                         } else {
2959
2960                                 /* drap: mov reg, disp(%rbp) */
2961                                 save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
2962                         }
2963
2964                 } else if (op->dest.reg == cfa->base) {
2965
2966                         /* mov reg, disp(%rbp) */
2967                         /* mov reg, disp(%rsp) */
2968                         save_reg(cfi, op->src.reg, CFI_CFA,
2969                                  op->dest.offset - cfi->cfa.offset);
2970
2971                 } else if (op->dest.reg == CFI_SP) {
2972
2973                         /* mov reg, disp(%rsp) */
2974                         save_reg(cfi, op->src.reg, CFI_CFA,
2975                                  op->dest.offset - cfi->stack_size);
2976
2977                 } else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
2978
2979                         /* mov %rsp, (%reg); # setup a stack swizzle. */
2980                         cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
2981                         cfi->vals[op->dest.reg].offset = cfa->offset;
2982                 }
2983
2984                 break;
2985
2986         case OP_DEST_MEM:
2987                 if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
2988                         WARN_FUNC("unknown stack-related memory operation",
2989                                   insn->sec, insn->offset);
2990                         return -1;
2991                 }
2992
2993                 /* pop mem */
2994                 cfi->stack_size -= 8;
2995                 if (cfa->base == CFI_SP)
2996                         cfa->offset -= 8;
2997
2998                 break;
2999
3000         default:
3001                 WARN_FUNC("unknown stack-related instruction",
3002                           insn->sec, insn->offset);
3003                 return -1;
3004         }
3005
3006         return 0;
3007 }
3008
3009 /*
3010  * The stack layouts of alternatives instructions can sometimes diverge when
3011  * they have stack modifications.  That's fine as long as the potential stack
3012  * layouts don't conflict at any given potential instruction boundary.
3013  *
3014  * Flatten the CFIs of the different alternative code streams (both original
3015  * and replacement) into a single shared CFI array which can be used to detect
3016  * conflicts and nicely feed a linear array of ORC entries to the unwinder.
3017  */
3018 static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
3019 {
3020         struct cfi_state **alt_cfi;
3021         int group_off;
3022
3023         if (!insn->alt_group)
3024                 return 0;
3025
3026         if (!insn->cfi) {
3027                 WARN("CFI missing");
3028                 return -1;
3029         }
3030
3031         alt_cfi = insn->alt_group->cfi;
3032         group_off = insn->offset - insn->alt_group->first_insn->offset;
3033
3034         if (!alt_cfi[group_off]) {
3035                 alt_cfi[group_off] = insn->cfi;
3036         } else {
3037                 if (cficmp(alt_cfi[group_off], insn->cfi)) {
3038                         WARN_FUNC("stack layout conflict in alternatives",
3039                                   insn->sec, insn->offset);
3040                         return -1;
3041                 }
3042         }
3043
3044         return 0;
3045 }
3046
3047 static int handle_insn_ops(struct instruction *insn,
3048                            struct instruction *next_insn,
3049                            struct insn_state *state)
3050 {
3051         struct stack_op *op;
3052
3053         list_for_each_entry(op, &insn->stack_ops, list) {
3054
3055                 if (update_cfi_state(insn, next_insn, &state->cfi, op))
3056                         return 1;
3057
3058                 if (!insn->alt_group)
3059                         continue;
3060
3061                 if (op->dest.type == OP_DEST_PUSHF) {
3062                         if (!state->uaccess_stack) {
3063                                 state->uaccess_stack = 1;
3064                         } else if (state->uaccess_stack >> 31) {
3065                                 WARN_FUNC("PUSHF stack exhausted",
3066                                           insn->sec, insn->offset);
3067                                 return 1;
3068                         }
3069                         state->uaccess_stack <<= 1;
3070                         state->uaccess_stack  |= state->uaccess;
3071                 }
3072
3073                 if (op->src.type == OP_SRC_POPF) {
3074                         if (state->uaccess_stack) {
3075                                 state->uaccess = state->uaccess_stack & 1;
3076                                 state->uaccess_stack >>= 1;
3077                                 if (state->uaccess_stack == 1)
3078                                         state->uaccess_stack = 0;
3079                         }
3080                 }
3081         }
3082
3083         return 0;
3084 }
3085
3086 static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
3087 {
3088         struct cfi_state *cfi1 = insn->cfi;
3089         int i;
3090
3091         if (!cfi1) {
3092                 WARN("CFI missing");
3093                 return false;
3094         }
3095
3096         if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
3097
3098                 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
3099                           insn->sec, insn->offset,
3100                           cfi1->cfa.base, cfi1->cfa.offset,
3101                           cfi2->cfa.base, cfi2->cfa.offset);
3102
3103         } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
3104                 for (i = 0; i < CFI_NUM_REGS; i++) {
3105                         if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
3106                                     sizeof(struct cfi_reg)))
3107                                 continue;
3108
3109                         WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
3110                                   insn->sec, insn->offset,
3111                                   i, cfi1->regs[i].base, cfi1->regs[i].offset,
3112                                   i, cfi2->regs[i].base, cfi2->regs[i].offset);
3113                         break;
3114                 }
3115
3116         } else if (cfi1->type != cfi2->type) {
3117
3118                 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
3119                           insn->sec, insn->offset, cfi1->type, cfi2->type);
3120
3121         } else if (cfi1->drap != cfi2->drap ||
3122                    (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
3123                    (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
3124
3125                 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
3126                           insn->sec, insn->offset,
3127                           cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
3128                           cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
3129
3130         } else
3131                 return true;
3132
3133         return false;
3134 }
3135
3136 static inline bool func_uaccess_safe(struct symbol *func)
3137 {
3138         if (func)
3139                 return func->uaccess_safe;
3140
3141         return false;
3142 }
3143
3144 static inline const char *call_dest_name(struct instruction *insn)
3145 {
3146         static char pvname[19];
3147         struct reloc *rel;
3148         int idx;
3149
3150         if (insn->call_dest)
3151                 return insn->call_dest->name;
3152
3153         rel = insn_reloc(NULL, insn);
3154         if (rel && !strcmp(rel->sym->name, "pv_ops")) {
3155                 idx = (rel->addend / sizeof(void *));
3156                 snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
3157                 return pvname;
3158         }
3159
3160         return "{dynamic}";
3161 }
3162
3163 static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
3164 {
3165         struct symbol *target;
3166         struct reloc *rel;
3167         int idx;
3168
3169         rel = insn_reloc(file, insn);
3170         if (!rel || strcmp(rel->sym->name, "pv_ops"))
3171                 return false;
3172
3173         idx = (arch_dest_reloc_offset(rel->addend) / sizeof(void *));
3174
3175         if (file->pv_ops[idx].clean)
3176                 return true;
3177
3178         file->pv_ops[idx].clean = true;
3179
3180         list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
3181                 if (!target->sec->noinstr) {
3182                         WARN("pv_ops[%d]: %s", idx, target->name);
3183                         file->pv_ops[idx].clean = false;
3184                 }
3185         }
3186
3187         return file->pv_ops[idx].clean;
3188 }
3189
3190 static inline bool noinstr_call_dest(struct objtool_file *file,
3191                                      struct instruction *insn,
3192                                      struct symbol *func)
3193 {
3194         /*
3195          * We can't deal with indirect function calls at present;
3196          * assume they're instrumented.
3197          */
3198         if (!func) {
3199                 if (file->pv_ops)
3200                         return pv_call_dest(file, insn);
3201
3202                 return false;
3203         }
3204
3205         /*
3206          * If the symbol is from a noinstr section; we good.
3207          */
3208         if (func->sec->noinstr)
3209                 return true;
3210
3211         /*
3212          * The __ubsan_handle_*() calls are like WARN(), they only happen when
3213          * something 'BAD' happened. At the risk of taking the machine down,
3214          * let them proceed to get the message out.
3215          */
3216         if (!strncmp(func->name, "__ubsan_handle_", 15))
3217                 return true;
3218
3219         return false;
3220 }
3221
3222 static int validate_call(struct objtool_file *file,
3223                          struct instruction *insn,
3224                          struct insn_state *state)
3225 {
3226         if (state->noinstr && state->instr <= 0 &&
3227             !noinstr_call_dest(file, insn, insn->call_dest)) {
3228                 WARN_FUNC("call to %s() leaves .noinstr.text section",
3229                                 insn->sec, insn->offset, call_dest_name(insn));
3230                 return 1;
3231         }
3232
3233         if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
3234                 WARN_FUNC("call to %s() with UACCESS enabled",
3235                                 insn->sec, insn->offset, call_dest_name(insn));
3236                 return 1;
3237         }
3238
3239         if (state->df) {
3240                 WARN_FUNC("call to %s() with DF set",
3241                                 insn->sec, insn->offset, call_dest_name(insn));
3242                 return 1;
3243         }
3244
3245         return 0;
3246 }
3247
3248 static int validate_sibling_call(struct objtool_file *file,
3249                                  struct instruction *insn,
3250                                  struct insn_state *state)
3251 {
3252         if (has_modified_stack_frame(insn, state)) {
3253                 WARN_FUNC("sibling call from callable instruction with modified stack frame",
3254                                 insn->sec, insn->offset);
3255                 return 1;
3256         }
3257
3258         return validate_call(file, insn, state);
3259 }
3260
3261 static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
3262 {
3263         if (state->noinstr && state->instr > 0) {
3264                 WARN_FUNC("return with instrumentation enabled",
3265                           insn->sec, insn->offset);
3266                 return 1;
3267         }
3268
3269         if (state->uaccess && !func_uaccess_safe(func)) {
3270                 WARN_FUNC("return with UACCESS enabled",
3271                           insn->sec, insn->offset);
3272                 return 1;
3273         }
3274
3275         if (!state->uaccess && func_uaccess_safe(func)) {
3276                 WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function",
3277                           insn->sec, insn->offset);
3278                 return 1;
3279         }
3280
3281         if (state->df) {
3282                 WARN_FUNC("return with DF set",
3283                           insn->sec, insn->offset);
3284                 return 1;
3285         }
3286
3287         if (func && has_modified_stack_frame(insn, state)) {
3288                 WARN_FUNC("return with modified stack frame",
3289                           insn->sec, insn->offset);
3290                 return 1;
3291         }
3292
3293         if (state->cfi.bp_scratch) {
3294                 WARN_FUNC("BP used as a scratch register",
3295                           insn->sec, insn->offset);
3296                 return 1;
3297         }
3298
3299         return 0;
3300 }
3301
3302 static struct instruction *next_insn_to_validate(struct objtool_file *file,
3303                                                  struct instruction *insn)
3304 {
3305         struct alt_group *alt_group = insn->alt_group;
3306
3307         /*
3308          * Simulate the fact that alternatives are patched in-place.  When the
3309          * end of a replacement alt_group is reached, redirect objtool flow to
3310          * the end of the original alt_group.
3311          */
3312         if (alt_group && insn == alt_group->last_insn && alt_group->orig_group)
3313                 return next_insn_same_sec(file, alt_group->orig_group->last_insn);
3314
3315         return next_insn_same_sec(file, insn);
3316 }
3317
3318 /*
3319  * Follow the branch starting at the given instruction, and recursively follow
3320  * any other branches (jumps).  Meanwhile, track the frame pointer state at
3321  * each instruction and validate all the rules described in
3322  * tools/objtool/Documentation/objtool.txt.
3323  */
3324 static int validate_branch(struct objtool_file *file, struct symbol *func,
3325                            struct instruction *insn, struct insn_state state)
3326 {
3327         struct alternative *alt;
3328         struct instruction *next_insn, *prev_insn = NULL;
3329         struct section *sec;
3330         u8 visited;
3331         int ret;
3332
3333         sec = insn->sec;
3334
3335         while (1) {
3336                 next_insn = next_insn_to_validate(file, insn);
3337
3338                 if (func && insn->func && func != insn->func->pfunc) {
3339                         /* Ignore KCFI type preambles, which always fall through */
3340                         if (!strncmp(func->name, "__cfi_", 6))
3341                                 return 0;
3342
3343                         WARN("%s() falls through to next function %s()",
3344                              func->name, insn->func->name);
3345                         return 1;
3346                 }
3347
3348                 if (func && insn->ignore) {
3349                         WARN_FUNC("BUG: why am I validating an ignored function?",
3350                                   sec, insn->offset);
3351                         return 1;
3352                 }
3353
3354                 visited = VISITED_BRANCH << state.uaccess;
3355                 if (insn->visited & VISITED_BRANCH_MASK) {
3356                         if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
3357                                 return 1;
3358
3359                         if (insn->visited & visited)
3360                                 return 0;
3361                 } else {
3362                         nr_insns_visited++;
3363                 }
3364
3365                 if (state.noinstr)
3366                         state.instr += insn->instr;
3367
3368                 if (insn->hint) {
3369                         if (insn->restore) {
3370                                 struct instruction *save_insn, *i;
3371
3372                                 i = insn;
3373                                 save_insn = NULL;
3374
3375                                 sym_for_each_insn_continue_reverse(file, func, i) {
3376                                         if (i->save) {
3377                                                 save_insn = i;
3378                                                 break;
3379                                         }
3380                                 }
3381
3382                                 if (!save_insn) {
3383                                         WARN_FUNC("no corresponding CFI save for CFI restore",
3384                                                   sec, insn->offset);
3385                                         return 1;
3386                                 }
3387
3388                                 if (!save_insn->visited) {
3389                                         WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
3390                                                   sec, insn->offset);
3391                                         return 1;
3392                                 }
3393
3394                                 insn->cfi = save_insn->cfi;
3395                                 nr_cfi_reused++;
3396                         }
3397
3398                         state.cfi = *insn->cfi;
3399                 } else {
3400                         /* XXX track if we actually changed state.cfi */
3401
3402                         if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {
3403                                 insn->cfi = prev_insn->cfi;
3404                                 nr_cfi_reused++;
3405                         } else {
3406                                 insn->cfi = cfi_hash_find_or_add(&state.cfi);
3407                         }
3408                 }
3409
3410                 insn->visited |= visited;
3411
3412                 if (propagate_alt_cfi(file, insn))
3413                         return 1;
3414
3415                 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
3416                         bool skip_orig = false;
3417
3418                         list_for_each_entry(alt, &insn->alts, list) {
3419                                 if (alt->skip_orig)
3420                                         skip_orig = true;
3421
3422                                 ret = validate_branch(file, func, alt->insn, state);
3423                                 if (ret) {
3424                                         if (opts.backtrace)
3425                                                 BT_FUNC("(alt)", insn);
3426                                         return ret;
3427                                 }
3428                         }
3429
3430                         if (skip_orig)
3431                                 return 0;
3432                 }
3433
3434                 if (handle_insn_ops(insn, next_insn, &state))
3435                         return 1;
3436
3437                 switch (insn->type) {
3438
3439                 case INSN_RETURN:
3440                         return validate_return(func, insn, &state);
3441
3442                 case INSN_CALL:
3443                 case INSN_CALL_DYNAMIC:
3444                         ret = validate_call(file, insn, &state);
3445                         if (ret)
3446                                 return ret;
3447
3448                         if (opts.stackval && func && !is_fentry_call(insn) &&
3449                             !has_valid_stack_frame(&state)) {
3450                                 WARN_FUNC("call without frame pointer save/setup",
3451                                           sec, insn->offset);
3452                                 return 1;
3453                         }
3454
3455                         if (insn->dead_end)
3456                                 return 0;
3457
3458                         break;
3459
3460                 case INSN_JUMP_CONDITIONAL:
3461                 case INSN_JUMP_UNCONDITIONAL:
3462                         if (is_sibling_call(insn)) {
3463                                 ret = validate_sibling_call(file, insn, &state);
3464                                 if (ret)
3465                                         return ret;
3466
3467                         } else if (insn->jump_dest) {
3468                                 ret = validate_branch(file, func,
3469                                                       insn->jump_dest, state);
3470                                 if (ret) {
3471                                         if (opts.backtrace)
3472                                                 BT_FUNC("(branch)", insn);
3473                                         return ret;
3474                                 }
3475                         }
3476
3477                         if (insn->type == INSN_JUMP_UNCONDITIONAL)
3478                                 return 0;
3479
3480                         break;
3481
3482                 case INSN_JUMP_DYNAMIC:
3483                 case INSN_JUMP_DYNAMIC_CONDITIONAL:
3484                         if (is_sibling_call(insn)) {
3485                                 ret = validate_sibling_call(file, insn, &state);
3486                                 if (ret)
3487                                         return ret;
3488                         }
3489
3490                         if (insn->type == INSN_JUMP_DYNAMIC)
3491                                 return 0;
3492
3493                         break;
3494
3495                 case INSN_CONTEXT_SWITCH:
3496                         if (func && (!next_insn || !next_insn->hint)) {
3497                                 WARN_FUNC("unsupported instruction in callable function",
3498                                           sec, insn->offset);
3499                                 return 1;
3500                         }
3501                         return 0;
3502
3503                 case INSN_STAC:
3504                         if (state.uaccess) {
3505                                 WARN_FUNC("recursive UACCESS enable", sec, insn->offset);
3506                                 return 1;
3507                         }
3508
3509                         state.uaccess = true;
3510                         break;
3511
3512                 case INSN_CLAC:
3513                         if (!state.uaccess && func) {
3514                                 WARN_FUNC("redundant UACCESS disable", sec, insn->offset);
3515                                 return 1;
3516                         }
3517
3518                         if (func_uaccess_safe(func) && !state.uaccess_stack) {
3519                                 WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset);
3520                                 return 1;
3521                         }
3522
3523                         state.uaccess = false;
3524                         break;
3525
3526                 case INSN_STD:
3527                         if (state.df) {
3528                                 WARN_FUNC("recursive STD", sec, insn->offset);
3529                                 return 1;
3530                         }
3531
3532                         state.df = true;
3533                         break;
3534
3535                 case INSN_CLD:
3536                         if (!state.df && func) {
3537                                 WARN_FUNC("redundant CLD", sec, insn->offset);
3538                                 return 1;
3539                         }
3540
3541                         state.df = false;
3542                         break;
3543
3544                 default:
3545                         break;
3546                 }
3547
3548                 if (insn->dead_end)
3549                         return 0;
3550
3551                 if (!next_insn) {
3552                         if (state.cfi.cfa.base == CFI_UNDEFINED)
3553                                 return 0;
3554                         WARN("%s: unexpected end of section", sec->name);
3555                         return 1;
3556                 }
3557
3558                 prev_insn = insn;
3559                 insn = next_insn;
3560         }
3561
3562         return 0;
3563 }
3564
3565 static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
3566 {
3567         struct instruction *insn;
3568         struct insn_state state;
3569         int ret, warnings = 0;
3570
3571         if (!file->hints)
3572                 return 0;
3573
3574         init_insn_state(file, &state, sec);
3575
3576         if (sec) {
3577                 insn = find_insn(file, sec, 0);
3578                 if (!insn)
3579                         return 0;
3580         } else {
3581                 insn = list_first_entry(&file->insn_list, typeof(*insn), list);
3582         }
3583
3584         while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
3585                 if (insn->hint && !insn->visited && !insn->ignore) {
3586                         ret = validate_branch(file, insn->func, insn, state);
3587                         if (ret && opts.backtrace)
3588                                 BT_FUNC("<=== (hint)", insn);
3589                         warnings += ret;
3590                 }
3591
3592                 insn = list_next_entry(insn, list);
3593         }
3594
3595         return warnings;
3596 }
3597
3598 /*
3599  * Validate rethunk entry constraint: must untrain RET before the first RET.
3600  *
3601  * Follow every branch (intra-function) and ensure ANNOTATE_UNRET_END comes
3602  * before an actual RET instruction.
3603  */
3604 static int validate_entry(struct objtool_file *file, struct instruction *insn)
3605 {
3606         struct instruction *next, *dest;
3607         int ret, warnings = 0;
3608
3609         for (;;) {
3610                 next = next_insn_to_validate(file, insn);
3611
3612                 if (insn->visited & VISITED_ENTRY)
3613                         return 0;
3614
3615                 insn->visited |= VISITED_ENTRY;
3616
3617                 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
3618                         struct alternative *alt;
3619                         bool skip_orig = false;
3620
3621                         list_for_each_entry(alt, &insn->alts, list) {
3622                                 if (alt->skip_orig)
3623                                         skip_orig = true;
3624
3625                                 ret = validate_entry(file, alt->insn);
3626                                 if (ret) {
3627                                         if (opts.backtrace)
3628                                                 BT_FUNC("(alt)", insn);
3629                                         return ret;
3630                                 }
3631                         }
3632
3633                         if (skip_orig)
3634                                 return 0;
3635                 }
3636
3637                 switch (insn->type) {
3638
3639                 case INSN_CALL_DYNAMIC:
3640                 case INSN_JUMP_DYNAMIC:
3641                 case INSN_JUMP_DYNAMIC_CONDITIONAL:
3642                         WARN_FUNC("early indirect call", insn->sec, insn->offset);
3643                         return 1;
3644
3645                 case INSN_JUMP_UNCONDITIONAL:
3646                 case INSN_JUMP_CONDITIONAL:
3647                         if (!is_sibling_call(insn)) {
3648                                 if (!insn->jump_dest) {
3649                                         WARN_FUNC("unresolved jump target after linking?!?",
3650                                                   insn->sec, insn->offset);
3651                                         return -1;
3652                                 }
3653                                 ret = validate_entry(file, insn->jump_dest);
3654                                 if (ret) {
3655                                         if (opts.backtrace) {
3656                                                 BT_FUNC("(branch%s)", insn,
3657                                                         insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
3658                                         }
3659                                         return ret;
3660                                 }
3661
3662                                 if (insn->type == INSN_JUMP_UNCONDITIONAL)
3663                                         return 0;
3664
3665                                 break;
3666                         }
3667
3668                         /* fallthrough */
3669                 case INSN_CALL:
3670                         dest = find_insn(file, insn->call_dest->sec,
3671                                          insn->call_dest->offset);
3672                         if (!dest) {
3673                                 WARN("Unresolved function after linking!?: %s",
3674                                      insn->call_dest->name);
3675                                 return -1;
3676                         }
3677
3678                         ret = validate_entry(file, dest);
3679                         if (ret) {
3680                                 if (opts.backtrace)
3681                                         BT_FUNC("(call)", insn);
3682                                 return ret;
3683                         }
3684                         /*
3685                          * If a call returns without error, it must have seen UNTRAIN_RET.
3686                          * Therefore any non-error return is a success.
3687                          */
3688                         return 0;
3689
3690                 case INSN_RETURN:
3691                         WARN_FUNC("RET before UNTRAIN", insn->sec, insn->offset);
3692                         return 1;
3693
3694                 case INSN_NOP:
3695                         if (insn->retpoline_safe)
3696                                 return 0;
3697                         break;
3698
3699                 default:
3700                         break;
3701                 }
3702
3703                 if (!next) {
3704                         WARN_FUNC("teh end!", insn->sec, insn->offset);
3705                         return -1;
3706                 }
3707                 insn = next;
3708         }
3709
3710         return warnings;
3711 }
3712
3713 /*
3714  * Validate that all branches starting at 'insn->entry' encounter UNRET_END
3715  * before RET.
3716  */
3717 static int validate_unret(struct objtool_file *file)
3718 {
3719         struct instruction *insn;
3720         int ret, warnings = 0;
3721
3722         for_each_insn(file, insn) {
3723                 if (!insn->entry)
3724                         continue;
3725
3726                 ret = validate_entry(file, insn);
3727                 if (ret < 0) {
3728                         WARN_FUNC("Failed UNRET validation", insn->sec, insn->offset);
3729                         return ret;
3730                 }
3731                 warnings += ret;
3732         }
3733
3734         return warnings;
3735 }
3736
3737 static int validate_retpoline(struct objtool_file *file)
3738 {
3739         struct instruction *insn;
3740         int warnings = 0;
3741
3742         for_each_insn(file, insn) {
3743                 if (insn->type != INSN_JUMP_DYNAMIC &&
3744                     insn->type != INSN_CALL_DYNAMIC &&
3745                     insn->type != INSN_RETURN)
3746                         continue;
3747
3748                 if (insn->retpoline_safe)
3749                         continue;
3750
3751                 /*
3752                  * .init.text code is ran before userspace and thus doesn't
3753                  * strictly need retpolines, except for modules which are
3754                  * loaded late, they very much do need retpoline in their
3755                  * .init.text
3756                  */
3757                 if (!strcmp(insn->sec->name, ".init.text") && !opts.module)
3758                         continue;
3759
3760                 if (insn->type == INSN_RETURN) {
3761                         if (opts.rethunk) {
3762                                 WARN_FUNC("'naked' return found in RETHUNK build",
3763                                           insn->sec, insn->offset);
3764                         } else
3765                                 continue;
3766                 } else {
3767                         WARN_FUNC("indirect %s found in RETPOLINE build",
3768                                   insn->sec, insn->offset,
3769                                   insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
3770                 }
3771
3772                 warnings++;
3773         }
3774
3775         return warnings;
3776 }
3777
3778 static bool is_kasan_insn(struct instruction *insn)
3779 {
3780         return (insn->type == INSN_CALL &&
3781                 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
3782 }
3783
3784 static bool is_ubsan_insn(struct instruction *insn)
3785 {
3786         return (insn->type == INSN_CALL &&
3787                 !strcmp(insn->call_dest->name,
3788                         "__ubsan_handle_builtin_unreachable"));
3789 }
3790
3791 static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
3792 {
3793         int i;
3794         struct instruction *prev_insn;
3795
3796         if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
3797                 return true;
3798
3799         /*
3800          * Ignore alternative replacement instructions.  This can happen
3801          * when a whitelisted function uses one of the ALTERNATIVE macros.
3802          */
3803         if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
3804             !strcmp(insn->sec->name, ".altinstr_aux"))
3805                 return true;
3806
3807         /*
3808          * Whole archive runs might encounter dead code from weak symbols.
3809          * This is where the linker will have dropped the weak symbol in
3810          * favour of a regular symbol, but leaves the code in place.
3811          *
3812          * In this case we'll find a piece of code (whole function) that is not
3813          * covered by a !section symbol. Ignore them.
3814          */
3815         if (opts.link && !insn->func) {
3816                 int size = find_symbol_hole_containing(insn->sec, insn->offset);
3817                 unsigned long end = insn->offset + size;
3818
3819                 if (!size) /* not a hole */
3820                         return false;
3821
3822                 if (size < 0) /* hole until the end */
3823                         return true;
3824
3825                 sec_for_each_insn_continue(file, insn) {
3826                         /*
3827                          * If we reach a visited instruction at or before the
3828                          * end of the hole, ignore the unreachable.
3829                          */
3830                         if (insn->visited)
3831                                 return true;
3832
3833                         if (insn->offset >= end)
3834                                 break;
3835
3836                         /*
3837                          * If this hole jumps to a .cold function, mark it ignore too.
3838                          */
3839                         if (insn->jump_dest && insn->jump_dest->func &&
3840                             strstr(insn->jump_dest->func->name, ".cold")) {
3841                                 struct instruction *dest = insn->jump_dest;
3842                                 func_for_each_insn(file, dest->func, dest)
3843                                         dest->ignore = true;
3844                         }
3845                 }
3846
3847                 return false;
3848         }
3849
3850         if (!insn->func)
3851                 return false;
3852
3853         if (insn->func->static_call_tramp)
3854                 return true;
3855
3856         /*
3857          * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
3858          * __builtin_unreachable().  The BUG() macro has an unreachable() after
3859          * the UD2, which causes GCC's undefined trap logic to emit another UD2
3860          * (or occasionally a JMP to UD2).
3861          *
3862          * It may also insert a UD2 after calling a __noreturn function.
3863          */
3864         prev_insn = list_prev_entry(insn, list);
3865         if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&
3866             (insn->type == INSN_BUG ||
3867              (insn->type == INSN_JUMP_UNCONDITIONAL &&
3868               insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
3869                 return true;
3870
3871         /*
3872          * Check if this (or a subsequent) instruction is related to
3873          * CONFIG_UBSAN or CONFIG_KASAN.
3874          *
3875          * End the search at 5 instructions to avoid going into the weeds.
3876          */
3877         for (i = 0; i < 5; i++) {
3878
3879                 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
3880                         return true;
3881
3882                 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
3883                         if (insn->jump_dest &&
3884                             insn->jump_dest->func == insn->func) {
3885                                 insn = insn->jump_dest;
3886                                 continue;
3887                         }
3888
3889                         break;
3890                 }
3891
3892                 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
3893                         break;
3894
3895                 insn = list_next_entry(insn, list);
3896         }
3897
3898         return false;
3899 }
3900
3901 static int validate_symbol(struct objtool_file *file, struct section *sec,
3902                            struct symbol *sym, struct insn_state *state)
3903 {
3904         struct instruction *insn;
3905         int ret;
3906
3907         if (!sym->len) {
3908                 WARN("%s() is missing an ELF size annotation", sym->name);
3909                 return 1;
3910         }
3911
3912         if (sym->pfunc != sym || sym->alias != sym)
3913                 return 0;
3914
3915         insn = find_insn(file, sec, sym->offset);
3916         if (!insn || insn->ignore || insn->visited)
3917                 return 0;
3918
3919         state->uaccess = sym->uaccess_safe;
3920
3921         ret = validate_branch(file, insn->func, insn, *state);
3922         if (ret && opts.backtrace)
3923                 BT_FUNC("<=== (sym)", insn);
3924         return ret;
3925 }
3926
3927 static int validate_section(struct objtool_file *file, struct section *sec)
3928 {
3929         struct insn_state state;
3930         struct symbol *func;
3931         int warnings = 0;
3932
3933         list_for_each_entry(func, &sec->symbol_list, list) {
3934                 if (func->type != STT_FUNC)
3935                         continue;
3936
3937                 init_insn_state(file, &state, sec);
3938                 set_func_state(&state.cfi);
3939
3940                 warnings += validate_symbol(file, sec, func, &state);
3941         }
3942
3943         return warnings;
3944 }
3945
3946 static int validate_noinstr_sections(struct objtool_file *file)
3947 {
3948         struct section *sec;
3949         int warnings = 0;
3950
3951         sec = find_section_by_name(file->elf, ".noinstr.text");
3952         if (sec) {
3953                 warnings += validate_section(file, sec);
3954                 warnings += validate_unwind_hints(file, sec);
3955         }
3956
3957         sec = find_section_by_name(file->elf, ".entry.text");
3958         if (sec) {
3959                 warnings += validate_section(file, sec);
3960                 warnings += validate_unwind_hints(file, sec);
3961         }
3962
3963         return warnings;
3964 }
3965
3966 static int validate_functions(struct objtool_file *file)
3967 {
3968         struct section *sec;
3969         int warnings = 0;
3970
3971         for_each_sec(file, sec) {
3972                 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
3973                         continue;
3974
3975                 warnings += validate_section(file, sec);
3976         }
3977
3978         return warnings;
3979 }
3980
3981 static void mark_endbr_used(struct instruction *insn)
3982 {
3983         if (!list_empty(&insn->call_node))
3984                 list_del_init(&insn->call_node);
3985 }
3986
3987 static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
3988 {
3989         struct instruction *dest;
3990         struct reloc *reloc;
3991         unsigned long off;
3992         int warnings = 0;
3993
3994         /*
3995          * Looking for function pointer load relocations.  Ignore
3996          * direct/indirect branches:
3997          */
3998         switch (insn->type) {
3999         case INSN_CALL:
4000         case INSN_CALL_DYNAMIC:
4001         case INSN_JUMP_CONDITIONAL:
4002         case INSN_JUMP_UNCONDITIONAL:
4003         case INSN_JUMP_DYNAMIC:
4004         case INSN_JUMP_DYNAMIC_CONDITIONAL:
4005         case INSN_RETURN:
4006         case INSN_NOP:
4007                 return 0;
4008         default:
4009                 break;
4010         }
4011
4012         for (reloc = insn_reloc(file, insn);
4013              reloc;
4014              reloc = find_reloc_by_dest_range(file->elf, insn->sec,
4015                                               reloc->offset + 1,
4016                                               (insn->offset + insn->len) - (reloc->offset + 1))) {
4017
4018                 /*
4019                  * static_call_update() references the trampoline, which
4020                  * doesn't have (or need) ENDBR.  Skip warning in that case.
4021                  */
4022                 if (reloc->sym->static_call_tramp)
4023                         continue;
4024
4025                 off = reloc->sym->offset;
4026                 if (reloc->type == R_X86_64_PC32 || reloc->type == R_X86_64_PLT32)
4027                         off += arch_dest_reloc_offset(reloc->addend);
4028                 else
4029                         off += reloc->addend;
4030
4031                 dest = find_insn(file, reloc->sym->sec, off);
4032                 if (!dest)
4033                         continue;
4034
4035                 if (dest->type == INSN_ENDBR) {
4036                         mark_endbr_used(dest);
4037                         continue;
4038                 }
4039
4040                 if (dest->func && dest->func == insn->func) {
4041                         /*
4042                          * Anything from->to self is either _THIS_IP_ or
4043                          * IRET-to-self.
4044                          *
4045                          * There is no sane way to annotate _THIS_IP_ since the
4046                          * compiler treats the relocation as a constant and is
4047                          * happy to fold in offsets, skewing any annotation we
4048                          * do, leading to vast amounts of false-positives.
4049                          *
4050                          * There's also compiler generated _THIS_IP_ through
4051                          * KCOV and such which we have no hope of annotating.
4052                          *
4053                          * As such, blanket accept self-references without
4054                          * issue.
4055                          */
4056                         continue;
4057                 }
4058
4059                 if (dest->noendbr)
4060                         continue;
4061
4062                 WARN_FUNC("relocation to !ENDBR: %s",
4063                           insn->sec, insn->offset,
4064                           offstr(dest->sec, dest->offset));
4065
4066                 warnings++;
4067         }
4068
4069         return warnings;
4070 }
4071
4072 static int validate_ibt_data_reloc(struct objtool_file *file,
4073                                    struct reloc *reloc)
4074 {
4075         struct instruction *dest;
4076
4077         dest = find_insn(file, reloc->sym->sec,
4078                          reloc->sym->offset + reloc->addend);
4079         if (!dest)
4080                 return 0;
4081
4082         if (dest->type == INSN_ENDBR) {
4083                 mark_endbr_used(dest);
4084                 return 0;
4085         }
4086
4087         if (dest->noendbr)
4088                 return 0;
4089
4090         WARN_FUNC("data relocation to !ENDBR: %s",
4091                   reloc->sec->base, reloc->offset,
4092                   offstr(dest->sec, dest->offset));
4093
4094         return 1;
4095 }
4096
4097 /*
4098  * Validate IBT rules and remove used ENDBR instructions from the seal list.
4099  * Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
4100  * NOPs) later, in create_ibt_endbr_seal_sections().
4101  */
4102 static int validate_ibt(struct objtool_file *file)
4103 {
4104         struct section *sec;
4105         struct reloc *reloc;
4106         struct instruction *insn;
4107         int warnings = 0;
4108
4109         for_each_insn(file, insn)
4110                 warnings += validate_ibt_insn(file, insn);
4111
4112         for_each_sec(file, sec) {
4113
4114                 /* Already done by validate_ibt_insn() */
4115                 if (sec->sh.sh_flags & SHF_EXECINSTR)
4116                         continue;
4117
4118                 if (!sec->reloc)
4119                         continue;
4120
4121                 /*
4122                  * These sections can reference text addresses, but not with
4123                  * the intent to indirect branch to them.
4124                  */
4125                 if ((!strncmp(sec->name, ".discard", 8) &&
4126                      strcmp(sec->name, ".discard.ibt_endbr_noseal"))    ||
4127                     !strncmp(sec->name, ".debug", 6)                    ||
4128                     !strcmp(sec->name, ".altinstructions")              ||
4129                     !strcmp(sec->name, ".ibt_endbr_seal")               ||
4130                     !strcmp(sec->name, ".orc_unwind_ip")                ||
4131                     !strcmp(sec->name, ".parainstructions")             ||
4132                     !strcmp(sec->name, ".retpoline_sites")              ||
4133                     !strcmp(sec->name, ".smp_locks")                    ||
4134                     !strcmp(sec->name, ".static_call_sites")            ||
4135                     !strcmp(sec->name, "_error_injection_whitelist")    ||
4136                     !strcmp(sec->name, "_kprobe_blacklist")             ||
4137                     !strcmp(sec->name, "__bug_table")                   ||
4138                     !strcmp(sec->name, "__ex_table")                    ||
4139                     !strcmp(sec->name, "__jump_table")                  ||
4140                     !strcmp(sec->name, "__mcount_loc")                  ||
4141                     !strcmp(sec->name, ".kcfi_traps")                   ||
4142                     strstr(sec->name, "__patchable_function_entries"))
4143                         continue;
4144
4145                 list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
4146                         warnings += validate_ibt_data_reloc(file, reloc);
4147         }
4148
4149         return warnings;
4150 }
4151
4152 static int validate_sls(struct objtool_file *file)
4153 {
4154         struct instruction *insn, *next_insn;
4155         int warnings = 0;
4156
4157         for_each_insn(file, insn) {
4158                 next_insn = next_insn_same_sec(file, insn);
4159
4160                 if (insn->retpoline_safe)
4161                         continue;
4162
4163                 switch (insn->type) {
4164                 case INSN_RETURN:
4165                         if (!next_insn || next_insn->type != INSN_TRAP) {
4166                                 WARN_FUNC("missing int3 after ret",
4167                                           insn->sec, insn->offset);
4168                                 warnings++;
4169                         }
4170
4171                         break;
4172                 case INSN_JUMP_DYNAMIC:
4173                         if (!next_insn || next_insn->type != INSN_TRAP) {
4174                                 WARN_FUNC("missing int3 after indirect jump",
4175                                           insn->sec, insn->offset);
4176                                 warnings++;
4177                         }
4178                         break;
4179                 default:
4180                         break;
4181                 }
4182         }
4183
4184         return warnings;
4185 }
4186
4187 static int validate_reachable_instructions(struct objtool_file *file)
4188 {
4189         struct instruction *insn;
4190
4191         if (file->ignore_unreachables)
4192                 return 0;
4193
4194         for_each_insn(file, insn) {
4195                 if (insn->visited || ignore_unreachable_insn(file, insn))
4196                         continue;
4197
4198                 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
4199                 return 1;
4200         }
4201
4202         return 0;
4203 }
4204
4205 int check(struct objtool_file *file)
4206 {
4207         int ret, warnings = 0;
4208
4209         arch_initial_func_cfi_state(&initial_func_cfi);
4210         init_cfi_state(&init_cfi);
4211         init_cfi_state(&func_cfi);
4212         set_func_state(&func_cfi);
4213
4214         if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
4215                 goto out;
4216
4217         cfi_hash_add(&init_cfi);
4218         cfi_hash_add(&func_cfi);
4219
4220         ret = decode_sections(file);
4221         if (ret < 0)
4222                 goto out;
4223
4224         warnings += ret;
4225
4226         if (list_empty(&file->insn_list))
4227                 goto out;
4228
4229         if (opts.retpoline) {
4230                 ret = validate_retpoline(file);
4231                 if (ret < 0)
4232                         return ret;
4233                 warnings += ret;
4234         }
4235
4236         if (opts.stackval || opts.orc || opts.uaccess) {
4237                 ret = validate_functions(file);
4238                 if (ret < 0)
4239                         goto out;
4240                 warnings += ret;
4241
4242                 ret = validate_unwind_hints(file, NULL);
4243                 if (ret < 0)
4244                         goto out;
4245                 warnings += ret;
4246
4247                 if (!warnings) {
4248                         ret = validate_reachable_instructions(file);
4249                         if (ret < 0)
4250                                 goto out;
4251                         warnings += ret;
4252                 }
4253
4254         } else if (opts.noinstr) {
4255                 ret = validate_noinstr_sections(file);
4256                 if (ret < 0)
4257                         goto out;
4258                 warnings += ret;
4259         }
4260
4261         if (opts.unret) {
4262                 /*
4263                  * Must be after validate_branch() and friends, it plays
4264                  * further games with insn->visited.
4265                  */
4266                 ret = validate_unret(file);
4267                 if (ret < 0)
4268                         return ret;
4269                 warnings += ret;
4270         }
4271
4272         if (opts.ibt) {
4273                 ret = validate_ibt(file);
4274                 if (ret < 0)
4275                         goto out;
4276                 warnings += ret;
4277         }
4278
4279         if (opts.sls) {
4280                 ret = validate_sls(file);
4281                 if (ret < 0)
4282                         goto out;
4283                 warnings += ret;
4284         }
4285
4286         if (opts.static_call) {
4287                 ret = create_static_call_sections(file);
4288                 if (ret < 0)
4289                         goto out;
4290                 warnings += ret;
4291         }
4292
4293         if (opts.retpoline) {
4294                 ret = create_retpoline_sites_sections(file);
4295                 if (ret < 0)
4296                         goto out;
4297                 warnings += ret;
4298         }
4299
4300         if (opts.rethunk) {
4301                 ret = create_return_sites_sections(file);
4302                 if (ret < 0)
4303                         goto out;
4304                 warnings += ret;
4305         }
4306
4307         if (opts.mcount) {
4308                 ret = create_mcount_loc_sections(file);
4309                 if (ret < 0)
4310                         goto out;
4311                 warnings += ret;
4312         }
4313
4314         if (opts.ibt) {
4315                 ret = create_ibt_endbr_seal_sections(file);
4316                 if (ret < 0)
4317                         goto out;
4318                 warnings += ret;
4319         }
4320
4321         if (opts.orc && !list_empty(&file->insn_list)) {
4322                 ret = orc_create(file);
4323                 if (ret < 0)
4324                         goto out;
4325                 warnings += ret;
4326         }
4327
4328
4329         if (opts.stats) {
4330                 printf("nr_insns_visited: %ld\n", nr_insns_visited);
4331                 printf("nr_cfi: %ld\n", nr_cfi);
4332                 printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
4333                 printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
4334         }
4335
4336 out:
4337         /*
4338          *  For now, don't fail the kernel build on fatal warnings.  These
4339          *  errors are still fairly common due to the growing matrix of
4340          *  supported toolchains and their recent pace of change.
4341          */
4342         return 0;
4343 }