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 || !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_volatile_read1",
1003         "__tsan_volatile_read2",
1004         "__tsan_volatile_read4",
1005         "__tsan_volatile_read8",
1006         "__tsan_volatile_read16",
1007         "__tsan_volatile_write1",
1008         "__tsan_volatile_write2",
1009         "__tsan_volatile_write4",
1010         "__tsan_volatile_write8",
1011         "__tsan_volatile_write16",
1012         "__tsan_atomic8_load",
1013         "__tsan_atomic16_load",
1014         "__tsan_atomic32_load",
1015         "__tsan_atomic64_load",
1016         "__tsan_atomic8_store",
1017         "__tsan_atomic16_store",
1018         "__tsan_atomic32_store",
1019         "__tsan_atomic64_store",
1020         "__tsan_atomic8_exchange",
1021         "__tsan_atomic16_exchange",
1022         "__tsan_atomic32_exchange",
1023         "__tsan_atomic64_exchange",
1024         "__tsan_atomic8_fetch_add",
1025         "__tsan_atomic16_fetch_add",
1026         "__tsan_atomic32_fetch_add",
1027         "__tsan_atomic64_fetch_add",
1028         "__tsan_atomic8_fetch_sub",
1029         "__tsan_atomic16_fetch_sub",
1030         "__tsan_atomic32_fetch_sub",
1031         "__tsan_atomic64_fetch_sub",
1032         "__tsan_atomic8_fetch_and",
1033         "__tsan_atomic16_fetch_and",
1034         "__tsan_atomic32_fetch_and",
1035         "__tsan_atomic64_fetch_and",
1036         "__tsan_atomic8_fetch_or",
1037         "__tsan_atomic16_fetch_or",
1038         "__tsan_atomic32_fetch_or",
1039         "__tsan_atomic64_fetch_or",
1040         "__tsan_atomic8_fetch_xor",
1041         "__tsan_atomic16_fetch_xor",
1042         "__tsan_atomic32_fetch_xor",
1043         "__tsan_atomic64_fetch_xor",
1044         "__tsan_atomic8_fetch_nand",
1045         "__tsan_atomic16_fetch_nand",
1046         "__tsan_atomic32_fetch_nand",
1047         "__tsan_atomic64_fetch_nand",
1048         "__tsan_atomic8_compare_exchange_strong",
1049         "__tsan_atomic16_compare_exchange_strong",
1050         "__tsan_atomic32_compare_exchange_strong",
1051         "__tsan_atomic64_compare_exchange_strong",
1052         "__tsan_atomic8_compare_exchange_weak",
1053         "__tsan_atomic16_compare_exchange_weak",
1054         "__tsan_atomic32_compare_exchange_weak",
1055         "__tsan_atomic64_compare_exchange_weak",
1056         "__tsan_atomic8_compare_exchange_val",
1057         "__tsan_atomic16_compare_exchange_val",
1058         "__tsan_atomic32_compare_exchange_val",
1059         "__tsan_atomic64_compare_exchange_val",
1060         "__tsan_atomic_thread_fence",
1061         "__tsan_atomic_signal_fence",
1062         /* KCOV */
1063         "write_comp_data",
1064         "check_kcov_mode",
1065         "__sanitizer_cov_trace_pc",
1066         "__sanitizer_cov_trace_const_cmp1",
1067         "__sanitizer_cov_trace_const_cmp2",
1068         "__sanitizer_cov_trace_const_cmp4",
1069         "__sanitizer_cov_trace_const_cmp8",
1070         "__sanitizer_cov_trace_cmp1",
1071         "__sanitizer_cov_trace_cmp2",
1072         "__sanitizer_cov_trace_cmp4",
1073         "__sanitizer_cov_trace_cmp8",
1074         "__sanitizer_cov_trace_switch",
1075         /* KMSAN */
1076         "kmsan_copy_to_user",
1077         "kmsan_report",
1078         "kmsan_unpoison_entry_regs",
1079         "kmsan_unpoison_memory",
1080         "__msan_chain_origin",
1081         "__msan_get_context_state",
1082         "__msan_instrument_asm_store",
1083         "__msan_metadata_ptr_for_load_1",
1084         "__msan_metadata_ptr_for_load_2",
1085         "__msan_metadata_ptr_for_load_4",
1086         "__msan_metadata_ptr_for_load_8",
1087         "__msan_metadata_ptr_for_load_n",
1088         "__msan_metadata_ptr_for_store_1",
1089         "__msan_metadata_ptr_for_store_2",
1090         "__msan_metadata_ptr_for_store_4",
1091         "__msan_metadata_ptr_for_store_8",
1092         "__msan_metadata_ptr_for_store_n",
1093         "__msan_poison_alloca",
1094         "__msan_warning",
1095         /* UBSAN */
1096         "ubsan_type_mismatch_common",
1097         "__ubsan_handle_type_mismatch",
1098         "__ubsan_handle_type_mismatch_v1",
1099         "__ubsan_handle_shift_out_of_bounds",
1100         /* misc */
1101         "csum_partial_copy_generic",
1102         "copy_mc_fragile",
1103         "copy_mc_fragile_handle_tail",
1104         "copy_mc_enhanced_fast_string",
1105         "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
1106         "clear_user_erms",
1107         "clear_user_rep_good",
1108         "clear_user_original",
1109         NULL
1110 };
1111
1112 static void add_uaccess_safe(struct objtool_file *file)
1113 {
1114         struct symbol *func;
1115         const char **name;
1116
1117         if (!opts.uaccess)
1118                 return;
1119
1120         for (name = uaccess_safe_builtin; *name; name++) {
1121                 func = find_symbol_by_name(file->elf, *name);
1122                 if (!func)
1123                         continue;
1124
1125                 func->uaccess_safe = true;
1126         }
1127 }
1128
1129 /*
1130  * FIXME: For now, just ignore any alternatives which add retpolines.  This is
1131  * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
1132  * But it at least allows objtool to understand the control flow *around* the
1133  * retpoline.
1134  */
1135 static int add_ignore_alternatives(struct objtool_file *file)
1136 {
1137         struct section *sec;
1138         struct reloc *reloc;
1139         struct instruction *insn;
1140
1141         sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
1142         if (!sec)
1143                 return 0;
1144
1145         list_for_each_entry(reloc, &sec->reloc_list, list) {
1146                 if (reloc->sym->type != STT_SECTION) {
1147                         WARN("unexpected relocation symbol type in %s", sec->name);
1148                         return -1;
1149                 }
1150
1151                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
1152                 if (!insn) {
1153                         WARN("bad .discard.ignore_alts entry");
1154                         return -1;
1155                 }
1156
1157                 insn->ignore_alts = true;
1158         }
1159
1160         return 0;
1161 }
1162
1163 __weak bool arch_is_retpoline(struct symbol *sym)
1164 {
1165         return false;
1166 }
1167
1168 __weak bool arch_is_rethunk(struct symbol *sym)
1169 {
1170         return false;
1171 }
1172
1173 #define NEGATIVE_RELOC  ((void *)-1L)
1174
1175 static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
1176 {
1177         if (insn->reloc == NEGATIVE_RELOC)
1178                 return NULL;
1179
1180         if (!insn->reloc) {
1181                 if (!file)
1182                         return NULL;
1183
1184                 insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
1185                                                        insn->offset, insn->len);
1186                 if (!insn->reloc) {
1187                         insn->reloc = NEGATIVE_RELOC;
1188                         return NULL;
1189                 }
1190         }
1191
1192         return insn->reloc;
1193 }
1194
1195 static void remove_insn_ops(struct instruction *insn)
1196 {
1197         struct stack_op *op, *tmp;
1198
1199         list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
1200                 list_del(&op->list);
1201                 free(op);
1202         }
1203 }
1204
1205 static void annotate_call_site(struct objtool_file *file,
1206                                struct instruction *insn, bool sibling)
1207 {
1208         struct reloc *reloc = insn_reloc(file, insn);
1209         struct symbol *sym = insn->call_dest;
1210
1211         if (!sym)
1212                 sym = reloc->sym;
1213
1214         /*
1215          * Alternative replacement code is just template code which is
1216          * sometimes copied to the original instruction. For now, don't
1217          * annotate it. (In the future we might consider annotating the
1218          * original instruction if/when it ever makes sense to do so.)
1219          */
1220         if (!strcmp(insn->sec->name, ".altinstr_replacement"))
1221                 return;
1222
1223         if (sym->static_call_tramp) {
1224                 list_add_tail(&insn->call_node, &file->static_call_list);
1225                 return;
1226         }
1227
1228         if (sym->retpoline_thunk) {
1229                 list_add_tail(&insn->call_node, &file->retpoline_call_list);
1230                 return;
1231         }
1232
1233         /*
1234          * Many compilers cannot disable KCOV or sanitizer calls with a function
1235          * attribute so they need a little help, NOP out any such calls from
1236          * noinstr text.
1237          */
1238         if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
1239                 if (reloc) {
1240                         reloc->type = R_NONE;
1241                         elf_write_reloc(file->elf, reloc);
1242                 }
1243
1244                 elf_write_insn(file->elf, insn->sec,
1245                                insn->offset, insn->len,
1246                                sibling ? arch_ret_insn(insn->len)
1247                                        : arch_nop_insn(insn->len));
1248
1249                 insn->type = sibling ? INSN_RETURN : INSN_NOP;
1250
1251                 if (sibling) {
1252                         /*
1253                          * We've replaced the tail-call JMP insn by two new
1254                          * insn: RET; INT3, except we only have a single struct
1255                          * insn here. Mark it retpoline_safe to avoid the SLS
1256                          * warning, instead of adding another insn.
1257                          */
1258                         insn->retpoline_safe = true;
1259                 }
1260
1261                 return;
1262         }
1263
1264         if (opts.mcount && sym->fentry) {
1265                 if (sibling)
1266                         WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset);
1267
1268                 if (reloc) {
1269                         reloc->type = R_NONE;
1270                         elf_write_reloc(file->elf, reloc);
1271                 }
1272
1273                 elf_write_insn(file->elf, insn->sec,
1274                                insn->offset, insn->len,
1275                                arch_nop_insn(insn->len));
1276
1277                 insn->type = INSN_NOP;
1278
1279                 list_add_tail(&insn->call_node, &file->mcount_loc_list);
1280                 return;
1281         }
1282
1283         if (!sibling && dead_end_function(file, sym))
1284                 insn->dead_end = true;
1285 }
1286
1287 static void add_call_dest(struct objtool_file *file, struct instruction *insn,
1288                           struct symbol *dest, bool sibling)
1289 {
1290         insn->call_dest = dest;
1291         if (!dest)
1292                 return;
1293
1294         /*
1295          * Whatever stack impact regular CALLs have, should be undone
1296          * by the RETURN of the called function.
1297          *
1298          * Annotated intra-function calls retain the stack_ops but
1299          * are converted to JUMP, see read_intra_function_calls().
1300          */
1301         remove_insn_ops(insn);
1302
1303         annotate_call_site(file, insn, sibling);
1304 }
1305
1306 static void add_retpoline_call(struct objtool_file *file, struct instruction *insn)
1307 {
1308         /*
1309          * Retpoline calls/jumps are really dynamic calls/jumps in disguise,
1310          * so convert them accordingly.
1311          */
1312         switch (insn->type) {
1313         case INSN_CALL:
1314                 insn->type = INSN_CALL_DYNAMIC;
1315                 break;
1316         case INSN_JUMP_UNCONDITIONAL:
1317                 insn->type = INSN_JUMP_DYNAMIC;
1318                 break;
1319         case INSN_JUMP_CONDITIONAL:
1320                 insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
1321                 break;
1322         default:
1323                 return;
1324         }
1325
1326         insn->retpoline_safe = true;
1327
1328         /*
1329          * Whatever stack impact regular CALLs have, should be undone
1330          * by the RETURN of the called function.
1331          *
1332          * Annotated intra-function calls retain the stack_ops but
1333          * are converted to JUMP, see read_intra_function_calls().
1334          */
1335         remove_insn_ops(insn);
1336
1337         annotate_call_site(file, insn, false);
1338 }
1339
1340 static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
1341 {
1342         /*
1343          * Return thunk tail calls are really just returns in disguise,
1344          * so convert them accordingly.
1345          */
1346         insn->type = INSN_RETURN;
1347         insn->retpoline_safe = true;
1348
1349         if (add)
1350                 list_add_tail(&insn->call_node, &file->return_thunk_list);
1351 }
1352
1353 static bool same_function(struct instruction *insn1, struct instruction *insn2)
1354 {
1355         return insn1->func->pfunc == insn2->func->pfunc;
1356 }
1357
1358 static bool is_first_func_insn(struct objtool_file *file, struct instruction *insn)
1359 {
1360         if (insn->offset == insn->func->offset)
1361                 return true;
1362
1363         if (opts.ibt) {
1364                 struct instruction *prev = prev_insn_same_sym(file, insn);
1365
1366                 if (prev && prev->type == INSN_ENDBR &&
1367                     insn->offset == insn->func->offset + prev->len)
1368                         return true;
1369         }
1370
1371         return false;
1372 }
1373
1374 /*
1375  * Find the destination instructions for all jumps.
1376  */
1377 static int add_jump_destinations(struct objtool_file *file)
1378 {
1379         struct instruction *insn, *jump_dest;
1380         struct reloc *reloc;
1381         struct section *dest_sec;
1382         unsigned long dest_off;
1383
1384         for_each_insn(file, insn) {
1385                 if (insn->jump_dest) {
1386                         /*
1387                          * handle_group_alt() may have previously set
1388                          * 'jump_dest' for some alternatives.
1389                          */
1390                         continue;
1391                 }
1392                 if (!is_static_jump(insn))
1393                         continue;
1394
1395                 reloc = insn_reloc(file, insn);
1396                 if (!reloc) {
1397                         dest_sec = insn->sec;
1398                         dest_off = arch_jump_destination(insn);
1399                 } else if (reloc->sym->type == STT_SECTION) {
1400                         dest_sec = reloc->sym->sec;
1401                         dest_off = arch_dest_reloc_offset(reloc->addend);
1402                 } else if (reloc->sym->retpoline_thunk) {
1403                         add_retpoline_call(file, insn);
1404                         continue;
1405                 } else if (reloc->sym->return_thunk) {
1406                         add_return_call(file, insn, true);
1407                         continue;
1408                 } else if (insn->func) {
1409                         /*
1410                          * External sibling call or internal sibling call with
1411                          * STT_FUNC reloc.
1412                          */
1413                         add_call_dest(file, insn, reloc->sym, true);
1414                         continue;
1415                 } else if (reloc->sym->sec->idx) {
1416                         dest_sec = reloc->sym->sec;
1417                         dest_off = reloc->sym->sym.st_value +
1418                                    arch_dest_reloc_offset(reloc->addend);
1419                 } else {
1420                         /* non-func asm code jumping to another file */
1421                         continue;
1422                 }
1423
1424                 jump_dest = find_insn(file, dest_sec, dest_off);
1425                 if (!jump_dest) {
1426                         struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
1427
1428                         /*
1429                          * This is a special case for zen_untrain_ret().
1430                          * It jumps to __x86_return_thunk(), but objtool
1431                          * can't find the thunk's starting RET
1432                          * instruction, because the RET is also in the
1433                          * middle of another instruction.  Objtool only
1434                          * knows about the outer instruction.
1435                          */
1436                         if (sym && sym->return_thunk) {
1437                                 add_return_call(file, insn, false);
1438                                 continue;
1439                         }
1440
1441                         WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
1442                                   insn->sec, insn->offset, dest_sec->name,
1443                                   dest_off);
1444                         return -1;
1445                 }
1446
1447                 /*
1448                  * Cross-function jump.
1449                  */
1450                 if (insn->func && jump_dest->func &&
1451                     insn->func != jump_dest->func) {
1452
1453                         /*
1454                          * For GCC 8+, create parent/child links for any cold
1455                          * subfunctions.  This is _mostly_ redundant with a
1456                          * similar initialization in read_symbols().
1457                          *
1458                          * If a function has aliases, we want the *first* such
1459                          * function in the symbol table to be the subfunction's
1460                          * parent.  In that case we overwrite the
1461                          * initialization done in read_symbols().
1462                          *
1463                          * However this code can't completely replace the
1464                          * read_symbols() code because this doesn't detect the
1465                          * case where the parent function's only reference to a
1466                          * subfunction is through a jump table.
1467                          */
1468                         if (!strstr(insn->func->name, ".cold") &&
1469                             strstr(jump_dest->func->name, ".cold")) {
1470                                 insn->func->cfunc = jump_dest->func;
1471                                 jump_dest->func->pfunc = insn->func;
1472
1473                         } else if (!same_function(insn, jump_dest) &&
1474                                    is_first_func_insn(file, jump_dest)) {
1475                                 /*
1476                                  * Internal sibling call without reloc or with
1477                                  * STT_SECTION reloc.
1478                                  */
1479                                 add_call_dest(file, insn, jump_dest->func, true);
1480                                 continue;
1481                         }
1482                 }
1483
1484                 insn->jump_dest = jump_dest;
1485         }
1486
1487         return 0;
1488 }
1489
1490 static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
1491 {
1492         struct symbol *call_dest;
1493
1494         call_dest = find_func_by_offset(sec, offset);
1495         if (!call_dest)
1496                 call_dest = find_symbol_by_offset(sec, offset);
1497
1498         return call_dest;
1499 }
1500
1501 /*
1502  * Find the destination instructions for all calls.
1503  */
1504 static int add_call_destinations(struct objtool_file *file)
1505 {
1506         struct instruction *insn;
1507         unsigned long dest_off;
1508         struct symbol *dest;
1509         struct reloc *reloc;
1510
1511         for_each_insn(file, insn) {
1512                 if (insn->type != INSN_CALL)
1513                         continue;
1514
1515                 reloc = insn_reloc(file, insn);
1516                 if (!reloc) {
1517                         dest_off = arch_jump_destination(insn);
1518                         dest = find_call_destination(insn->sec, dest_off);
1519
1520                         add_call_dest(file, insn, dest, false);
1521
1522                         if (insn->ignore)
1523                                 continue;
1524
1525                         if (!insn->call_dest) {
1526                                 WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);
1527                                 return -1;
1528                         }
1529
1530                         if (insn->func && insn->call_dest->type != STT_FUNC) {
1531                                 WARN_FUNC("unsupported call to non-function",
1532                                           insn->sec, insn->offset);
1533                                 return -1;
1534                         }
1535
1536                 } else if (reloc->sym->type == STT_SECTION) {
1537                         dest_off = arch_dest_reloc_offset(reloc->addend);
1538                         dest = find_call_destination(reloc->sym->sec, dest_off);
1539                         if (!dest) {
1540                                 WARN_FUNC("can't find call dest symbol at %s+0x%lx",
1541                                           insn->sec, insn->offset,
1542                                           reloc->sym->sec->name,
1543                                           dest_off);
1544                                 return -1;
1545                         }
1546
1547                         add_call_dest(file, insn, dest, false);
1548
1549                 } else if (reloc->sym->retpoline_thunk) {
1550                         add_retpoline_call(file, insn);
1551
1552                 } else
1553                         add_call_dest(file, insn, reloc->sym, false);
1554         }
1555
1556         return 0;
1557 }
1558
1559 /*
1560  * The .alternatives section requires some extra special care over and above
1561  * other special sections because alternatives are patched in place.
1562  */
1563 static int handle_group_alt(struct objtool_file *file,
1564                             struct special_alt *special_alt,
1565                             struct instruction *orig_insn,
1566                             struct instruction **new_insn)
1567 {
1568         struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL;
1569         struct alt_group *orig_alt_group, *new_alt_group;
1570         unsigned long dest_off;
1571
1572
1573         orig_alt_group = malloc(sizeof(*orig_alt_group));
1574         if (!orig_alt_group) {
1575                 WARN("malloc failed");
1576                 return -1;
1577         }
1578         orig_alt_group->cfi = calloc(special_alt->orig_len,
1579                                      sizeof(struct cfi_state *));
1580         if (!orig_alt_group->cfi) {
1581                 WARN("calloc failed");
1582                 return -1;
1583         }
1584
1585         last_orig_insn = NULL;
1586         insn = orig_insn;
1587         sec_for_each_insn_from(file, insn) {
1588                 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
1589                         break;
1590
1591                 insn->alt_group = orig_alt_group;
1592                 last_orig_insn = insn;
1593         }
1594         orig_alt_group->orig_group = NULL;
1595         orig_alt_group->first_insn = orig_insn;
1596         orig_alt_group->last_insn = last_orig_insn;
1597
1598
1599         new_alt_group = malloc(sizeof(*new_alt_group));
1600         if (!new_alt_group) {
1601                 WARN("malloc failed");
1602                 return -1;
1603         }
1604
1605         if (special_alt->new_len < special_alt->orig_len) {
1606                 /*
1607                  * Insert a fake nop at the end to make the replacement
1608                  * alt_group the same size as the original.  This is needed to
1609                  * allow propagate_alt_cfi() to do its magic.  When the last
1610                  * instruction affects the stack, the instruction after it (the
1611                  * nop) will propagate the new state to the shared CFI array.
1612                  */
1613                 nop = malloc(sizeof(*nop));
1614                 if (!nop) {
1615                         WARN("malloc failed");
1616                         return -1;
1617                 }
1618                 memset(nop, 0, sizeof(*nop));
1619                 INIT_LIST_HEAD(&nop->alts);
1620                 INIT_LIST_HEAD(&nop->stack_ops);
1621
1622                 nop->sec = special_alt->new_sec;
1623                 nop->offset = special_alt->new_off + special_alt->new_len;
1624                 nop->len = special_alt->orig_len - special_alt->new_len;
1625                 nop->type = INSN_NOP;
1626                 nop->func = orig_insn->func;
1627                 nop->alt_group = new_alt_group;
1628                 nop->ignore = orig_insn->ignore_alts;
1629         }
1630
1631         if (!special_alt->new_len) {
1632                 *new_insn = nop;
1633                 goto end;
1634         }
1635
1636         insn = *new_insn;
1637         sec_for_each_insn_from(file, insn) {
1638                 struct reloc *alt_reloc;
1639
1640                 if (insn->offset >= special_alt->new_off + special_alt->new_len)
1641                         break;
1642
1643                 last_new_insn = insn;
1644
1645                 insn->ignore = orig_insn->ignore_alts;
1646                 insn->func = orig_insn->func;
1647                 insn->alt_group = new_alt_group;
1648
1649                 /*
1650                  * Since alternative replacement code is copy/pasted by the
1651                  * kernel after applying relocations, generally such code can't
1652                  * have relative-address relocation references to outside the
1653                  * .altinstr_replacement section, unless the arch's
1654                  * alternatives code can adjust the relative offsets
1655                  * accordingly.
1656                  */
1657                 alt_reloc = insn_reloc(file, insn);
1658                 if (alt_reloc &&
1659                     !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
1660
1661                         WARN_FUNC("unsupported relocation in alternatives section",
1662                                   insn->sec, insn->offset);
1663                         return -1;
1664                 }
1665
1666                 if (!is_static_jump(insn))
1667                         continue;
1668
1669                 if (!insn->immediate)
1670                         continue;
1671
1672                 dest_off = arch_jump_destination(insn);
1673                 if (dest_off == special_alt->new_off + special_alt->new_len) {
1674                         insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
1675                         if (!insn->jump_dest) {
1676                                 WARN_FUNC("can't find alternative jump destination",
1677                                           insn->sec, insn->offset);
1678                                 return -1;
1679                         }
1680                 }
1681         }
1682
1683         if (!last_new_insn) {
1684                 WARN_FUNC("can't find last new alternative instruction",
1685                           special_alt->new_sec, special_alt->new_off);
1686                 return -1;
1687         }
1688
1689         if (nop)
1690                 list_add(&nop->list, &last_new_insn->list);
1691 end:
1692         new_alt_group->orig_group = orig_alt_group;
1693         new_alt_group->first_insn = *new_insn;
1694         new_alt_group->last_insn = nop ? : last_new_insn;
1695         new_alt_group->cfi = orig_alt_group->cfi;
1696         return 0;
1697 }
1698
1699 /*
1700  * A jump table entry can either convert a nop to a jump or a jump to a nop.
1701  * If the original instruction is a jump, make the alt entry an effective nop
1702  * by just skipping the original instruction.
1703  */
1704 static int handle_jump_alt(struct objtool_file *file,
1705                            struct special_alt *special_alt,
1706                            struct instruction *orig_insn,
1707                            struct instruction **new_insn)
1708 {
1709         if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
1710             orig_insn->type != INSN_NOP) {
1711
1712                 WARN_FUNC("unsupported instruction at jump label",
1713                           orig_insn->sec, orig_insn->offset);
1714                 return -1;
1715         }
1716
1717         if (opts.hack_jump_label && special_alt->key_addend & 2) {
1718                 struct reloc *reloc = insn_reloc(file, orig_insn);
1719
1720                 if (reloc) {
1721                         reloc->type = R_NONE;
1722                         elf_write_reloc(file->elf, reloc);
1723                 }
1724                 elf_write_insn(file->elf, orig_insn->sec,
1725                                orig_insn->offset, orig_insn->len,
1726                                arch_nop_insn(orig_insn->len));
1727                 orig_insn->type = INSN_NOP;
1728         }
1729
1730         if (orig_insn->type == INSN_NOP) {
1731                 if (orig_insn->len == 2)
1732                         file->jl_nop_short++;
1733                 else
1734                         file->jl_nop_long++;
1735
1736                 return 0;
1737         }
1738
1739         if (orig_insn->len == 2)
1740                 file->jl_short++;
1741         else
1742                 file->jl_long++;
1743
1744         *new_insn = list_next_entry(orig_insn, list);
1745         return 0;
1746 }
1747
1748 /*
1749  * Read all the special sections which have alternate instructions which can be
1750  * patched in or redirected to at runtime.  Each instruction having alternate
1751  * instruction(s) has them added to its insn->alts list, which will be
1752  * traversed in validate_branch().
1753  */
1754 static int add_special_section_alts(struct objtool_file *file)
1755 {
1756         struct list_head special_alts;
1757         struct instruction *orig_insn, *new_insn;
1758         struct special_alt *special_alt, *tmp;
1759         struct alternative *alt;
1760         int ret;
1761
1762         ret = special_get_alts(file->elf, &special_alts);
1763         if (ret)
1764                 return ret;
1765
1766         list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
1767
1768                 orig_insn = find_insn(file, special_alt->orig_sec,
1769                                       special_alt->orig_off);
1770                 if (!orig_insn) {
1771                         WARN_FUNC("special: can't find orig instruction",
1772                                   special_alt->orig_sec, special_alt->orig_off);
1773                         ret = -1;
1774                         goto out;
1775                 }
1776
1777                 new_insn = NULL;
1778                 if (!special_alt->group || special_alt->new_len) {
1779                         new_insn = find_insn(file, special_alt->new_sec,
1780                                              special_alt->new_off);
1781                         if (!new_insn) {
1782                                 WARN_FUNC("special: can't find new instruction",
1783                                           special_alt->new_sec,
1784                                           special_alt->new_off);
1785                                 ret = -1;
1786                                 goto out;
1787                         }
1788                 }
1789
1790                 if (special_alt->group) {
1791                         if (!special_alt->orig_len) {
1792                                 WARN_FUNC("empty alternative entry",
1793                                           orig_insn->sec, orig_insn->offset);
1794                                 continue;
1795                         }
1796
1797                         ret = handle_group_alt(file, special_alt, orig_insn,
1798                                                &new_insn);
1799                         if (ret)
1800                                 goto out;
1801                 } else if (special_alt->jump_or_nop) {
1802                         ret = handle_jump_alt(file, special_alt, orig_insn,
1803                                               &new_insn);
1804                         if (ret)
1805                                 goto out;
1806                 }
1807
1808                 alt = malloc(sizeof(*alt));
1809                 if (!alt) {
1810                         WARN("malloc failed");
1811                         ret = -1;
1812                         goto out;
1813                 }
1814
1815                 alt->insn = new_insn;
1816                 alt->skip_orig = special_alt->skip_orig;
1817                 orig_insn->ignore_alts |= special_alt->skip_alt;
1818                 list_add_tail(&alt->list, &orig_insn->alts);
1819
1820                 list_del(&special_alt->list);
1821                 free(special_alt);
1822         }
1823
1824         if (opts.stats) {
1825                 printf("jl\\\tNOP\tJMP\n");
1826                 printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
1827                 printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
1828         }
1829
1830 out:
1831         return ret;
1832 }
1833
1834 static int add_jump_table(struct objtool_file *file, struct instruction *insn,
1835                             struct reloc *table)
1836 {
1837         struct reloc *reloc = table;
1838         struct instruction *dest_insn;
1839         struct alternative *alt;
1840         struct symbol *pfunc = insn->func->pfunc;
1841         unsigned int prev_offset = 0;
1842
1843         /*
1844          * Each @reloc is a switch table relocation which points to the target
1845          * instruction.
1846          */
1847         list_for_each_entry_from(reloc, &table->sec->reloc_list, list) {
1848
1849                 /* Check for the end of the table: */
1850                 if (reloc != table && reloc->jump_table_start)
1851                         break;
1852
1853                 /* Make sure the table entries are consecutive: */
1854                 if (prev_offset && reloc->offset != prev_offset + 8)
1855                         break;
1856
1857                 /* Detect function pointers from contiguous objects: */
1858                 if (reloc->sym->sec == pfunc->sec &&
1859                     reloc->addend == pfunc->offset)
1860                         break;
1861
1862                 dest_insn = find_insn(file, reloc->sym->sec, reloc->addend);
1863                 if (!dest_insn)
1864                         break;
1865
1866                 /* Make sure the destination is in the same function: */
1867                 if (!dest_insn->func || dest_insn->func->pfunc != pfunc)
1868                         break;
1869
1870                 alt = malloc(sizeof(*alt));
1871                 if (!alt) {
1872                         WARN("malloc failed");
1873                         return -1;
1874                 }
1875
1876                 alt->insn = dest_insn;
1877                 list_add_tail(&alt->list, &insn->alts);
1878                 prev_offset = reloc->offset;
1879         }
1880
1881         if (!prev_offset) {
1882                 WARN_FUNC("can't find switch jump table",
1883                           insn->sec, insn->offset);
1884                 return -1;
1885         }
1886
1887         return 0;
1888 }
1889
1890 /*
1891  * find_jump_table() - Given a dynamic jump, find the switch jump table
1892  * associated with it.
1893  */
1894 static struct reloc *find_jump_table(struct objtool_file *file,
1895                                       struct symbol *func,
1896                                       struct instruction *insn)
1897 {
1898         struct reloc *table_reloc;
1899         struct instruction *dest_insn, *orig_insn = insn;
1900
1901         /*
1902          * Backward search using the @first_jump_src links, these help avoid
1903          * much of the 'in between' code. Which avoids us getting confused by
1904          * it.
1905          */
1906         for (;
1907              insn && insn->func && insn->func->pfunc == func;
1908              insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
1909
1910                 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
1911                         break;
1912
1913                 /* allow small jumps within the range */
1914                 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
1915                     insn->jump_dest &&
1916                     (insn->jump_dest->offset <= insn->offset ||
1917                      insn->jump_dest->offset > orig_insn->offset))
1918                     break;
1919
1920                 table_reloc = arch_find_switch_table(file, insn);
1921                 if (!table_reloc)
1922                         continue;
1923                 dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
1924                 if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
1925                         continue;
1926
1927                 return table_reloc;
1928         }
1929
1930         return NULL;
1931 }
1932
1933 /*
1934  * First pass: Mark the head of each jump table so that in the next pass,
1935  * we know when a given jump table ends and the next one starts.
1936  */
1937 static void mark_func_jump_tables(struct objtool_file *file,
1938                                     struct symbol *func)
1939 {
1940         struct instruction *insn, *last = NULL;
1941         struct reloc *reloc;
1942
1943         func_for_each_insn(file, func, insn) {
1944                 if (!last)
1945                         last = insn;
1946
1947                 /*
1948                  * Store back-pointers for unconditional forward jumps such
1949                  * that find_jump_table() can back-track using those and
1950                  * avoid some potentially confusing code.
1951                  */
1952                 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
1953                     insn->offset > last->offset &&
1954                     insn->jump_dest->offset > insn->offset &&
1955                     !insn->jump_dest->first_jump_src) {
1956
1957                         insn->jump_dest->first_jump_src = insn;
1958                         last = insn->jump_dest;
1959                 }
1960
1961                 if (insn->type != INSN_JUMP_DYNAMIC)
1962                         continue;
1963
1964                 reloc = find_jump_table(file, func, insn);
1965                 if (reloc) {
1966                         reloc->jump_table_start = true;
1967                         insn->jump_table = reloc;
1968                 }
1969         }
1970 }
1971
1972 static int add_func_jump_tables(struct objtool_file *file,
1973                                   struct symbol *func)
1974 {
1975         struct instruction *insn;
1976         int ret;
1977
1978         func_for_each_insn(file, func, insn) {
1979                 if (!insn->jump_table)
1980                         continue;
1981
1982                 ret = add_jump_table(file, insn, insn->jump_table);
1983                 if (ret)
1984                         return ret;
1985         }
1986
1987         return 0;
1988 }
1989
1990 /*
1991  * For some switch statements, gcc generates a jump table in the .rodata
1992  * section which contains a list of addresses within the function to jump to.
1993  * This finds these jump tables and adds them to the insn->alts lists.
1994  */
1995 static int add_jump_table_alts(struct objtool_file *file)
1996 {
1997         struct section *sec;
1998         struct symbol *func;
1999         int ret;
2000
2001         if (!file->rodata)
2002                 return 0;
2003
2004         for_each_sec(file, sec) {
2005                 list_for_each_entry(func, &sec->symbol_list, list) {
2006                         if (func->type != STT_FUNC)
2007                                 continue;
2008
2009                         mark_func_jump_tables(file, func);
2010                         ret = add_func_jump_tables(file, func);
2011                         if (ret)
2012                                 return ret;
2013                 }
2014         }
2015
2016         return 0;
2017 }
2018
2019 static void set_func_state(struct cfi_state *state)
2020 {
2021         state->cfa = initial_func_cfi.cfa;
2022         memcpy(&state->regs, &initial_func_cfi.regs,
2023                CFI_NUM_REGS * sizeof(struct cfi_reg));
2024         state->stack_size = initial_func_cfi.cfa.offset;
2025 }
2026
2027 static int read_unwind_hints(struct objtool_file *file)
2028 {
2029         struct cfi_state cfi = init_cfi;
2030         struct section *sec, *relocsec;
2031         struct unwind_hint *hint;
2032         struct instruction *insn;
2033         struct reloc *reloc;
2034         int i;
2035
2036         sec = find_section_by_name(file->elf, ".discard.unwind_hints");
2037         if (!sec)
2038                 return 0;
2039
2040         relocsec = sec->reloc;
2041         if (!relocsec) {
2042                 WARN("missing .rela.discard.unwind_hints section");
2043                 return -1;
2044         }
2045
2046         if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
2047                 WARN("struct unwind_hint size mismatch");
2048                 return -1;
2049         }
2050
2051         file->hints = true;
2052
2053         for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
2054                 hint = (struct unwind_hint *)sec->data->d_buf + i;
2055
2056                 reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
2057                 if (!reloc) {
2058                         WARN("can't find reloc for unwind_hints[%d]", i);
2059                         return -1;
2060                 }
2061
2062                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2063                 if (!insn) {
2064                         WARN("can't find insn for unwind_hints[%d]", i);
2065                         return -1;
2066                 }
2067
2068                 insn->hint = true;
2069
2070                 if (hint->type == UNWIND_HINT_TYPE_SAVE) {
2071                         insn->hint = false;
2072                         insn->save = true;
2073                         continue;
2074                 }
2075
2076                 if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
2077                         insn->restore = true;
2078                         continue;
2079                 }
2080
2081                 if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
2082                         struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
2083
2084                         if (sym && sym->bind == STB_GLOBAL) {
2085                                 if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
2086                                         WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR",
2087                                                   insn->sec, insn->offset);
2088                                 }
2089
2090                                 insn->entry = 1;
2091                         }
2092                 }
2093
2094                 if (hint->type == UNWIND_HINT_TYPE_ENTRY) {
2095                         hint->type = UNWIND_HINT_TYPE_CALL;
2096                         insn->entry = 1;
2097                 }
2098
2099                 if (hint->type == UNWIND_HINT_TYPE_FUNC) {
2100                         insn->cfi = &func_cfi;
2101                         continue;
2102                 }
2103
2104                 if (insn->cfi)
2105                         cfi = *(insn->cfi);
2106
2107                 if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
2108                         WARN_FUNC("unsupported unwind_hint sp base reg %d",
2109                                   insn->sec, insn->offset, hint->sp_reg);
2110                         return -1;
2111                 }
2112
2113                 cfi.cfa.offset = bswap_if_needed(hint->sp_offset);
2114                 cfi.type = hint->type;
2115                 cfi.end = hint->end;
2116
2117                 insn->cfi = cfi_hash_find_or_add(&cfi);
2118         }
2119
2120         return 0;
2121 }
2122
2123 static int read_noendbr_hints(struct objtool_file *file)
2124 {
2125         struct section *sec;
2126         struct instruction *insn;
2127         struct reloc *reloc;
2128
2129         sec = find_section_by_name(file->elf, ".rela.discard.noendbr");
2130         if (!sec)
2131                 return 0;
2132
2133         list_for_each_entry(reloc, &sec->reloc_list, list) {
2134                 insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend);
2135                 if (!insn) {
2136                         WARN("bad .discard.noendbr entry");
2137                         return -1;
2138                 }
2139
2140                 insn->noendbr = 1;
2141         }
2142
2143         return 0;
2144 }
2145
2146 static int read_retpoline_hints(struct objtool_file *file)
2147 {
2148         struct section *sec;
2149         struct instruction *insn;
2150         struct reloc *reloc;
2151
2152         sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
2153         if (!sec)
2154                 return 0;
2155
2156         list_for_each_entry(reloc, &sec->reloc_list, list) {
2157                 if (reloc->sym->type != STT_SECTION) {
2158                         WARN("unexpected relocation symbol type in %s", sec->name);
2159                         return -1;
2160                 }
2161
2162                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2163                 if (!insn) {
2164                         WARN("bad .discard.retpoline_safe entry");
2165                         return -1;
2166                 }
2167
2168                 if (insn->type != INSN_JUMP_DYNAMIC &&
2169                     insn->type != INSN_CALL_DYNAMIC &&
2170                     insn->type != INSN_RETURN &&
2171                     insn->type != INSN_NOP) {
2172                         WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret/nop",
2173                                   insn->sec, insn->offset);
2174                         return -1;
2175                 }
2176
2177                 insn->retpoline_safe = true;
2178         }
2179
2180         return 0;
2181 }
2182
2183 static int read_instr_hints(struct objtool_file *file)
2184 {
2185         struct section *sec;
2186         struct instruction *insn;
2187         struct reloc *reloc;
2188
2189         sec = find_section_by_name(file->elf, ".rela.discard.instr_end");
2190         if (!sec)
2191                 return 0;
2192
2193         list_for_each_entry(reloc, &sec->reloc_list, list) {
2194                 if (reloc->sym->type != STT_SECTION) {
2195                         WARN("unexpected relocation symbol type in %s", sec->name);
2196                         return -1;
2197                 }
2198
2199                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2200                 if (!insn) {
2201                         WARN("bad .discard.instr_end entry");
2202                         return -1;
2203                 }
2204
2205                 insn->instr--;
2206         }
2207
2208         sec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
2209         if (!sec)
2210                 return 0;
2211
2212         list_for_each_entry(reloc, &sec->reloc_list, list) {
2213                 if (reloc->sym->type != STT_SECTION) {
2214                         WARN("unexpected relocation symbol type in %s", sec->name);
2215                         return -1;
2216                 }
2217
2218                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2219                 if (!insn) {
2220                         WARN("bad .discard.instr_begin entry");
2221                         return -1;
2222                 }
2223
2224                 insn->instr++;
2225         }
2226
2227         return 0;
2228 }
2229
2230 static int read_intra_function_calls(struct objtool_file *file)
2231 {
2232         struct instruction *insn;
2233         struct section *sec;
2234         struct reloc *reloc;
2235
2236         sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
2237         if (!sec)
2238                 return 0;
2239
2240         list_for_each_entry(reloc, &sec->reloc_list, list) {
2241                 unsigned long dest_off;
2242
2243                 if (reloc->sym->type != STT_SECTION) {
2244                         WARN("unexpected relocation symbol type in %s",
2245                              sec->name);
2246                         return -1;
2247                 }
2248
2249                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2250                 if (!insn) {
2251                         WARN("bad .discard.intra_function_call entry");
2252                         return -1;
2253                 }
2254
2255                 if (insn->type != INSN_CALL) {
2256                         WARN_FUNC("intra_function_call not a direct call",
2257                                   insn->sec, insn->offset);
2258                         return -1;
2259                 }
2260
2261                 /*
2262                  * Treat intra-function CALLs as JMPs, but with a stack_op.
2263                  * See add_call_destinations(), which strips stack_ops from
2264                  * normal CALLs.
2265                  */
2266                 insn->type = INSN_JUMP_UNCONDITIONAL;
2267
2268                 dest_off = arch_jump_destination(insn);
2269                 insn->jump_dest = find_insn(file, insn->sec, dest_off);
2270                 if (!insn->jump_dest) {
2271                         WARN_FUNC("can't find call dest at %s+0x%lx",
2272                                   insn->sec, insn->offset,
2273                                   insn->sec->name, dest_off);
2274                         return -1;
2275                 }
2276         }
2277
2278         return 0;
2279 }
2280
2281 /*
2282  * Return true if name matches an instrumentation function, where calls to that
2283  * function from noinstr code can safely be removed, but compilers won't do so.
2284  */
2285 static bool is_profiling_func(const char *name)
2286 {
2287         /*
2288          * Many compilers cannot disable KCOV with a function attribute.
2289          */
2290         if (!strncmp(name, "__sanitizer_cov_", 16))
2291                 return true;
2292
2293         /*
2294          * Some compilers currently do not remove __tsan_func_entry/exit nor
2295          * __tsan_atomic_signal_fence (used for barrier instrumentation) with
2296          * the __no_sanitize_thread attribute, remove them. Once the kernel's
2297          * minimum Clang version is 14.0, this can be removed.
2298          */
2299         if (!strncmp(name, "__tsan_func_", 12) ||
2300             !strcmp(name, "__tsan_atomic_signal_fence"))
2301                 return true;
2302
2303         return false;
2304 }
2305
2306 static int classify_symbols(struct objtool_file *file)
2307 {
2308         struct section *sec;
2309         struct symbol *func;
2310
2311         for_each_sec(file, sec) {
2312                 list_for_each_entry(func, &sec->symbol_list, list) {
2313                         if (func->bind != STB_GLOBAL)
2314                                 continue;
2315
2316                         if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
2317                                      strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
2318                                 func->static_call_tramp = true;
2319
2320                         if (arch_is_retpoline(func))
2321                                 func->retpoline_thunk = true;
2322
2323                         if (arch_is_rethunk(func))
2324                                 func->return_thunk = true;
2325
2326                         if (!strcmp(func->name, "__fentry__"))
2327                                 func->fentry = true;
2328
2329                         if (is_profiling_func(func->name))
2330                                 func->profiling_func = true;
2331                 }
2332         }
2333
2334         return 0;
2335 }
2336
2337 static void mark_rodata(struct objtool_file *file)
2338 {
2339         struct section *sec;
2340         bool found = false;
2341
2342         /*
2343          * Search for the following rodata sections, each of which can
2344          * potentially contain jump tables:
2345          *
2346          * - .rodata: can contain GCC switch tables
2347          * - .rodata.<func>: same, if -fdata-sections is being used
2348          * - .rodata..c_jump_table: contains C annotated jump tables
2349          *
2350          * .rodata.str1.* sections are ignored; they don't contain jump tables.
2351          */
2352         for_each_sec(file, sec) {
2353                 if (!strncmp(sec->name, ".rodata", 7) &&
2354                     !strstr(sec->name, ".str1.")) {
2355                         sec->rodata = true;
2356                         found = true;
2357                 }
2358         }
2359
2360         file->rodata = found;
2361 }
2362
2363 static int decode_sections(struct objtool_file *file)
2364 {
2365         int ret;
2366
2367         mark_rodata(file);
2368
2369         ret = init_pv_ops(file);
2370         if (ret)
2371                 return ret;
2372
2373         ret = decode_instructions(file);
2374         if (ret)
2375                 return ret;
2376
2377         add_ignores(file);
2378         add_uaccess_safe(file);
2379
2380         ret = add_ignore_alternatives(file);
2381         if (ret)
2382                 return ret;
2383
2384         /*
2385          * Must be before read_unwind_hints() since that needs insn->noendbr.
2386          */
2387         ret = read_noendbr_hints(file);
2388         if (ret)
2389                 return ret;
2390
2391         /*
2392          * Must be before add_{jump_call}_destination.
2393          */
2394         ret = classify_symbols(file);
2395         if (ret)
2396                 return ret;
2397
2398         /*
2399          * Must be before add_jump_destinations(), which depends on 'func'
2400          * being set for alternatives, to enable proper sibling call detection.
2401          */
2402         ret = add_special_section_alts(file);
2403         if (ret)
2404                 return ret;
2405
2406         ret = add_jump_destinations(file);
2407         if (ret)
2408                 return ret;
2409
2410         /*
2411          * Must be before add_call_destination(); it changes INSN_CALL to
2412          * INSN_JUMP.
2413          */
2414         ret = read_intra_function_calls(file);
2415         if (ret)
2416                 return ret;
2417
2418         ret = add_call_destinations(file);
2419         if (ret)
2420                 return ret;
2421
2422         /*
2423          * Must be after add_call_destinations() such that it can override
2424          * dead_end_function() marks.
2425          */
2426         ret = add_dead_ends(file);
2427         if (ret)
2428                 return ret;
2429
2430         ret = add_jump_table_alts(file);
2431         if (ret)
2432                 return ret;
2433
2434         ret = read_unwind_hints(file);
2435         if (ret)
2436                 return ret;
2437
2438         ret = read_retpoline_hints(file);
2439         if (ret)
2440                 return ret;
2441
2442         ret = read_instr_hints(file);
2443         if (ret)
2444                 return ret;
2445
2446         return 0;
2447 }
2448
2449 static bool is_fentry_call(struct instruction *insn)
2450 {
2451         if (insn->type == INSN_CALL &&
2452             insn->call_dest &&
2453             insn->call_dest->fentry)
2454                 return true;
2455
2456         return false;
2457 }
2458
2459 static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
2460 {
2461         struct cfi_state *cfi = &state->cfi;
2462         int i;
2463
2464         if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
2465                 return true;
2466
2467         if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
2468                 return true;
2469
2470         if (cfi->stack_size != initial_func_cfi.cfa.offset)
2471                 return true;
2472
2473         for (i = 0; i < CFI_NUM_REGS; i++) {
2474                 if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
2475                     cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
2476                         return true;
2477         }
2478
2479         return false;
2480 }
2481
2482 static bool check_reg_frame_pos(const struct cfi_reg *reg,
2483                                 int expected_offset)
2484 {
2485         return reg->base == CFI_CFA &&
2486                reg->offset == expected_offset;
2487 }
2488
2489 static bool has_valid_stack_frame(struct insn_state *state)
2490 {
2491         struct cfi_state *cfi = &state->cfi;
2492
2493         if (cfi->cfa.base == CFI_BP &&
2494             check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
2495             check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
2496                 return true;
2497
2498         if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
2499                 return true;
2500
2501         return false;
2502 }
2503
2504 static int update_cfi_state_regs(struct instruction *insn,
2505                                   struct cfi_state *cfi,
2506                                   struct stack_op *op)
2507 {
2508         struct cfi_reg *cfa = &cfi->cfa;
2509
2510         if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
2511                 return 0;
2512
2513         /* push */
2514         if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
2515                 cfa->offset += 8;
2516
2517         /* pop */
2518         if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
2519                 cfa->offset -= 8;
2520
2521         /* add immediate to sp */
2522         if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
2523             op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
2524                 cfa->offset -= op->src.offset;
2525
2526         return 0;
2527 }
2528
2529 static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
2530 {
2531         if (arch_callee_saved_reg(reg) &&
2532             cfi->regs[reg].base == CFI_UNDEFINED) {
2533                 cfi->regs[reg].base = base;
2534                 cfi->regs[reg].offset = offset;
2535         }
2536 }
2537
2538 static void restore_reg(struct cfi_state *cfi, unsigned char reg)
2539 {
2540         cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
2541         cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
2542 }
2543
2544 /*
2545  * A note about DRAP stack alignment:
2546  *
2547  * GCC has the concept of a DRAP register, which is used to help keep track of
2548  * the stack pointer when aligning the stack.  r10 or r13 is used as the DRAP
2549  * register.  The typical DRAP pattern is:
2550  *
2551  *   4c 8d 54 24 08             lea    0x8(%rsp),%r10
2552  *   48 83 e4 c0                and    $0xffffffffffffffc0,%rsp
2553  *   41 ff 72 f8                pushq  -0x8(%r10)
2554  *   55                         push   %rbp
2555  *   48 89 e5                   mov    %rsp,%rbp
2556  *                              (more pushes)
2557  *   41 52                      push   %r10
2558  *                              ...
2559  *   41 5a                      pop    %r10
2560  *                              (more pops)
2561  *   5d                         pop    %rbp
2562  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
2563  *   c3                         retq
2564  *
2565  * There are some variations in the epilogues, like:
2566  *
2567  *   5b                         pop    %rbx
2568  *   41 5a                      pop    %r10
2569  *   41 5c                      pop    %r12
2570  *   41 5d                      pop    %r13
2571  *   41 5e                      pop    %r14
2572  *   c9                         leaveq
2573  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
2574  *   c3                         retq
2575  *
2576  * and:
2577  *
2578  *   4c 8b 55 e8                mov    -0x18(%rbp),%r10
2579  *   48 8b 5d e0                mov    -0x20(%rbp),%rbx
2580  *   4c 8b 65 f0                mov    -0x10(%rbp),%r12
2581  *   4c 8b 6d f8                mov    -0x8(%rbp),%r13
2582  *   c9                         leaveq
2583  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
2584  *   c3                         retq
2585  *
2586  * Sometimes r13 is used as the DRAP register, in which case it's saved and
2587  * restored beforehand:
2588  *
2589  *   41 55                      push   %r13
2590  *   4c 8d 6c 24 10             lea    0x10(%rsp),%r13
2591  *   48 83 e4 f0                and    $0xfffffffffffffff0,%rsp
2592  *                              ...
2593  *   49 8d 65 f0                lea    -0x10(%r13),%rsp
2594  *   41 5d                      pop    %r13
2595  *   c3                         retq
2596  */
2597 static int update_cfi_state(struct instruction *insn,
2598                             struct instruction *next_insn,
2599                             struct cfi_state *cfi, struct stack_op *op)
2600 {
2601         struct cfi_reg *cfa = &cfi->cfa;
2602         struct cfi_reg *regs = cfi->regs;
2603
2604         /* stack operations don't make sense with an undefined CFA */
2605         if (cfa->base == CFI_UNDEFINED) {
2606                 if (insn->func) {
2607                         WARN_FUNC("undefined stack state", insn->sec, insn->offset);
2608                         return -1;
2609                 }
2610                 return 0;
2611         }
2612
2613         if (cfi->type == UNWIND_HINT_TYPE_REGS ||
2614             cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
2615                 return update_cfi_state_regs(insn, cfi, op);
2616
2617         switch (op->dest.type) {
2618
2619         case OP_DEST_REG:
2620                 switch (op->src.type) {
2621
2622                 case OP_SRC_REG:
2623                         if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
2624                             cfa->base == CFI_SP &&
2625                             check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {
2626
2627                                 /* mov %rsp, %rbp */
2628                                 cfa->base = op->dest.reg;
2629                                 cfi->bp_scratch = false;
2630                         }
2631
2632                         else if (op->src.reg == CFI_SP &&
2633                                  op->dest.reg == CFI_BP && cfi->drap) {
2634
2635                                 /* drap: mov %rsp, %rbp */
2636                                 regs[CFI_BP].base = CFI_BP;
2637                                 regs[CFI_BP].offset = -cfi->stack_size;
2638                                 cfi->bp_scratch = false;
2639                         }
2640
2641                         else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2642
2643                                 /*
2644                                  * mov %rsp, %reg
2645                                  *
2646                                  * This is needed for the rare case where GCC
2647                                  * does:
2648                                  *
2649                                  *   mov    %rsp, %rax
2650                                  *   ...
2651                                  *   mov    %rax, %rsp
2652                                  */
2653                                 cfi->vals[op->dest.reg].base = CFI_CFA;
2654                                 cfi->vals[op->dest.reg].offset = -cfi->stack_size;
2655                         }
2656
2657                         else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
2658                                  (cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {
2659
2660                                 /*
2661                                  * mov %rbp, %rsp
2662                                  *
2663                                  * Restore the original stack pointer (Clang).
2664                                  */
2665                                 cfi->stack_size = -cfi->regs[CFI_BP].offset;
2666                         }
2667
2668                         else if (op->dest.reg == cfa->base) {
2669
2670                                 /* mov %reg, %rsp */
2671                                 if (cfa->base == CFI_SP &&
2672                                     cfi->vals[op->src.reg].base == CFI_CFA) {
2673
2674                                         /*
2675                                          * This is needed for the rare case
2676                                          * where GCC does something dumb like:
2677                                          *
2678                                          *   lea    0x8(%rsp), %rcx
2679                                          *   ...
2680                                          *   mov    %rcx, %rsp
2681                                          */
2682                                         cfa->offset = -cfi->vals[op->src.reg].offset;
2683                                         cfi->stack_size = cfa->offset;
2684
2685                                 } else if (cfa->base == CFI_SP &&
2686                                            cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2687                                            cfi->vals[op->src.reg].offset == cfa->offset) {
2688
2689                                         /*
2690                                          * Stack swizzle:
2691                                          *
2692                                          * 1: mov %rsp, (%[tos])
2693                                          * 2: mov %[tos], %rsp
2694                                          *    ...
2695                                          * 3: pop %rsp
2696                                          *
2697                                          * Where:
2698                                          *
2699                                          * 1 - places a pointer to the previous
2700                                          *     stack at the Top-of-Stack of the
2701                                          *     new stack.
2702                                          *
2703                                          * 2 - switches to the new stack.
2704                                          *
2705                                          * 3 - pops the Top-of-Stack to restore
2706                                          *     the original stack.
2707                                          *
2708                                          * Note: we set base to SP_INDIRECT
2709                                          * here and preserve offset. Therefore
2710                                          * when the unwinder reaches ToS it
2711                                          * will dereference SP and then add the
2712                                          * offset to find the next frame, IOW:
2713                                          * (%rsp) + offset.
2714                                          */
2715                                         cfa->base = CFI_SP_INDIRECT;
2716
2717                                 } else {
2718                                         cfa->base = CFI_UNDEFINED;
2719                                         cfa->offset = 0;
2720                                 }
2721                         }
2722
2723                         else if (op->dest.reg == CFI_SP &&
2724                                  cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2725                                  cfi->vals[op->src.reg].offset == cfa->offset) {
2726
2727                                 /*
2728                                  * The same stack swizzle case 2) as above. But
2729                                  * because we can't change cfa->base, case 3)
2730                                  * will become a regular POP. Pretend we're a
2731                                  * PUSH so things don't go unbalanced.
2732                                  */
2733                                 cfi->stack_size += 8;
2734                         }
2735
2736
2737                         break;
2738
2739                 case OP_SRC_ADD:
2740                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
2741
2742                                 /* add imm, %rsp */
2743                                 cfi->stack_size -= op->src.offset;
2744                                 if (cfa->base == CFI_SP)
2745                                         cfa->offset -= op->src.offset;
2746                                 break;
2747                         }
2748
2749                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
2750
2751                                 /* lea disp(%rbp), %rsp */
2752                                 cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
2753                                 break;
2754                         }
2755
2756                         if (!cfi->drap && op->src.reg == CFI_SP &&
2757                             op->dest.reg == CFI_BP && cfa->base == CFI_SP &&
2758                             check_reg_frame_pos(&regs[CFI_BP], -cfa->offset + op->src.offset)) {
2759
2760                                 /* lea disp(%rsp), %rbp */
2761                                 cfa->base = CFI_BP;
2762                                 cfa->offset -= op->src.offset;
2763                                 cfi->bp_scratch = false;
2764                                 break;
2765                         }
2766
2767                         if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2768
2769                                 /* drap: lea disp(%rsp), %drap */
2770                                 cfi->drap_reg = op->dest.reg;
2771
2772                                 /*
2773                                  * lea disp(%rsp), %reg
2774                                  *
2775                                  * This is needed for the rare case where GCC
2776                                  * does something dumb like:
2777                                  *
2778                                  *   lea    0x8(%rsp), %rcx
2779                                  *   ...
2780                                  *   mov    %rcx, %rsp
2781                                  */
2782                                 cfi->vals[op->dest.reg].base = CFI_CFA;
2783                                 cfi->vals[op->dest.reg].offset = \
2784                                         -cfi->stack_size + op->src.offset;
2785
2786                                 break;
2787                         }
2788
2789                         if (cfi->drap && op->dest.reg == CFI_SP &&
2790                             op->src.reg == cfi->drap_reg) {
2791
2792                                  /* drap: lea disp(%drap), %rsp */
2793                                 cfa->base = CFI_SP;
2794                                 cfa->offset = cfi->stack_size = -op->src.offset;
2795                                 cfi->drap_reg = CFI_UNDEFINED;
2796                                 cfi->drap = false;
2797                                 break;
2798                         }
2799
2800                         if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
2801                                 WARN_FUNC("unsupported stack register modification",
2802                                           insn->sec, insn->offset);
2803                                 return -1;
2804                         }
2805
2806                         break;
2807
2808                 case OP_SRC_AND:
2809                         if (op->dest.reg != CFI_SP ||
2810                             (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
2811                             (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
2812                                 WARN_FUNC("unsupported stack pointer realignment",
2813                                           insn->sec, insn->offset);
2814                                 return -1;
2815                         }
2816
2817                         if (cfi->drap_reg != CFI_UNDEFINED) {
2818                                 /* drap: and imm, %rsp */
2819                                 cfa->base = cfi->drap_reg;
2820                                 cfa->offset = cfi->stack_size = 0;
2821                                 cfi->drap = true;
2822                         }
2823
2824                         /*
2825                          * Older versions of GCC (4.8ish) realign the stack
2826                          * without DRAP, with a frame pointer.
2827                          */
2828
2829                         break;
2830
2831                 case OP_SRC_POP:
2832                 case OP_SRC_POPF:
2833                         if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
2834
2835                                 /* pop %rsp; # restore from a stack swizzle */
2836                                 cfa->base = CFI_SP;
2837                                 break;
2838                         }
2839
2840                         if (!cfi->drap && op->dest.reg == cfa->base) {
2841
2842                                 /* pop %rbp */
2843                                 cfa->base = CFI_SP;
2844                         }
2845
2846                         if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
2847                             op->dest.reg == cfi->drap_reg &&
2848                             cfi->drap_offset == -cfi->stack_size) {
2849
2850                                 /* drap: pop %drap */
2851                                 cfa->base = cfi->drap_reg;
2852                                 cfa->offset = 0;
2853                                 cfi->drap_offset = -1;
2854
2855                         } else if (cfi->stack_size == -regs[op->dest.reg].offset) {
2856
2857                                 /* pop %reg */
2858                                 restore_reg(cfi, op->dest.reg);
2859                         }
2860
2861                         cfi->stack_size -= 8;
2862                         if (cfa->base == CFI_SP)
2863                                 cfa->offset -= 8;
2864
2865                         break;
2866
2867                 case OP_SRC_REG_INDIRECT:
2868                         if (!cfi->drap && op->dest.reg == cfa->base &&
2869                             op->dest.reg == CFI_BP) {
2870
2871                                 /* mov disp(%rsp), %rbp */
2872                                 cfa->base = CFI_SP;
2873                                 cfa->offset = cfi->stack_size;
2874                         }
2875
2876                         if (cfi->drap && op->src.reg == CFI_BP &&
2877                             op->src.offset == cfi->drap_offset) {
2878
2879                                 /* drap: mov disp(%rbp), %drap */
2880                                 cfa->base = cfi->drap_reg;
2881                                 cfa->offset = 0;
2882                                 cfi->drap_offset = -1;
2883                         }
2884
2885                         if (cfi->drap && op->src.reg == CFI_BP &&
2886                             op->src.offset == regs[op->dest.reg].offset) {
2887
2888                                 /* drap: mov disp(%rbp), %reg */
2889                                 restore_reg(cfi, op->dest.reg);
2890
2891                         } else if (op->src.reg == cfa->base &&
2892                             op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
2893
2894                                 /* mov disp(%rbp), %reg */
2895                                 /* mov disp(%rsp), %reg */
2896                                 restore_reg(cfi, op->dest.reg);
2897
2898                         } else if (op->src.reg == CFI_SP &&
2899                                    op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
2900
2901                                 /* mov disp(%rsp), %reg */
2902                                 restore_reg(cfi, op->dest.reg);
2903                         }
2904
2905                         break;
2906
2907                 default:
2908                         WARN_FUNC("unknown stack-related instruction",
2909                                   insn->sec, insn->offset);
2910                         return -1;
2911                 }
2912
2913                 break;
2914
2915         case OP_DEST_PUSH:
2916         case OP_DEST_PUSHF:
2917                 cfi->stack_size += 8;
2918                 if (cfa->base == CFI_SP)
2919                         cfa->offset += 8;
2920
2921                 if (op->src.type != OP_SRC_REG)
2922                         break;
2923
2924                 if (cfi->drap) {
2925                         if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
2926
2927                                 /* drap: push %drap */
2928                                 cfa->base = CFI_BP_INDIRECT;
2929                                 cfa->offset = -cfi->stack_size;
2930
2931                                 /* save drap so we know when to restore it */
2932                                 cfi->drap_offset = -cfi->stack_size;
2933
2934                         } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
2935
2936                                 /* drap: push %rbp */
2937                                 cfi->stack_size = 0;
2938
2939                         } else {
2940
2941                                 /* drap: push %reg */
2942                                 save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
2943                         }
2944
2945                 } else {
2946
2947                         /* push %reg */
2948                         save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
2949                 }
2950
2951                 /* detect when asm code uses rbp as a scratch register */
2952                 if (opts.stackval && insn->func && op->src.reg == CFI_BP &&
2953                     cfa->base != CFI_BP)
2954                         cfi->bp_scratch = true;
2955                 break;
2956
2957         case OP_DEST_REG_INDIRECT:
2958
2959                 if (cfi->drap) {
2960                         if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
2961
2962                                 /* drap: mov %drap, disp(%rbp) */
2963                                 cfa->base = CFI_BP_INDIRECT;
2964                                 cfa->offset = op->dest.offset;
2965
2966                                 /* save drap offset so we know when to restore it */
2967                                 cfi->drap_offset = op->dest.offset;
2968                         } else {
2969
2970                                 /* drap: mov reg, disp(%rbp) */
2971                                 save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
2972                         }
2973
2974                 } else if (op->dest.reg == cfa->base) {
2975
2976                         /* mov reg, disp(%rbp) */
2977                         /* mov reg, disp(%rsp) */
2978                         save_reg(cfi, op->src.reg, CFI_CFA,
2979                                  op->dest.offset - cfi->cfa.offset);
2980
2981                 } else if (op->dest.reg == CFI_SP) {
2982
2983                         /* mov reg, disp(%rsp) */
2984                         save_reg(cfi, op->src.reg, CFI_CFA,
2985                                  op->dest.offset - cfi->stack_size);
2986
2987                 } else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
2988
2989                         /* mov %rsp, (%reg); # setup a stack swizzle. */
2990                         cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
2991                         cfi->vals[op->dest.reg].offset = cfa->offset;
2992                 }
2993
2994                 break;
2995
2996         case OP_DEST_MEM:
2997                 if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
2998                         WARN_FUNC("unknown stack-related memory operation",
2999                                   insn->sec, insn->offset);
3000                         return -1;
3001                 }
3002
3003                 /* pop mem */
3004                 cfi->stack_size -= 8;
3005                 if (cfa->base == CFI_SP)
3006                         cfa->offset -= 8;
3007
3008                 break;
3009
3010         default:
3011                 WARN_FUNC("unknown stack-related instruction",
3012                           insn->sec, insn->offset);
3013                 return -1;
3014         }
3015
3016         return 0;
3017 }
3018
3019 /*
3020  * The stack layouts of alternatives instructions can sometimes diverge when
3021  * they have stack modifications.  That's fine as long as the potential stack
3022  * layouts don't conflict at any given potential instruction boundary.
3023  *
3024  * Flatten the CFIs of the different alternative code streams (both original
3025  * and replacement) into a single shared CFI array which can be used to detect
3026  * conflicts and nicely feed a linear array of ORC entries to the unwinder.
3027  */
3028 static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
3029 {
3030         struct cfi_state **alt_cfi;
3031         int group_off;
3032
3033         if (!insn->alt_group)
3034                 return 0;
3035
3036         if (!insn->cfi) {
3037                 WARN("CFI missing");
3038                 return -1;
3039         }
3040
3041         alt_cfi = insn->alt_group->cfi;
3042         group_off = insn->offset - insn->alt_group->first_insn->offset;
3043
3044         if (!alt_cfi[group_off]) {
3045                 alt_cfi[group_off] = insn->cfi;
3046         } else {
3047                 if (cficmp(alt_cfi[group_off], insn->cfi)) {
3048                         WARN_FUNC("stack layout conflict in alternatives",
3049                                   insn->sec, insn->offset);
3050                         return -1;
3051                 }
3052         }
3053
3054         return 0;
3055 }
3056
3057 static int handle_insn_ops(struct instruction *insn,
3058                            struct instruction *next_insn,
3059                            struct insn_state *state)
3060 {
3061         struct stack_op *op;
3062
3063         list_for_each_entry(op, &insn->stack_ops, list) {
3064
3065                 if (update_cfi_state(insn, next_insn, &state->cfi, op))
3066                         return 1;
3067
3068                 if (!insn->alt_group)
3069                         continue;
3070
3071                 if (op->dest.type == OP_DEST_PUSHF) {
3072                         if (!state->uaccess_stack) {
3073                                 state->uaccess_stack = 1;
3074                         } else if (state->uaccess_stack >> 31) {
3075                                 WARN_FUNC("PUSHF stack exhausted",
3076                                           insn->sec, insn->offset);
3077                                 return 1;
3078                         }
3079                         state->uaccess_stack <<= 1;
3080                         state->uaccess_stack  |= state->uaccess;
3081                 }
3082
3083                 if (op->src.type == OP_SRC_POPF) {
3084                         if (state->uaccess_stack) {
3085                                 state->uaccess = state->uaccess_stack & 1;
3086                                 state->uaccess_stack >>= 1;
3087                                 if (state->uaccess_stack == 1)
3088                                         state->uaccess_stack = 0;
3089                         }
3090                 }
3091         }
3092
3093         return 0;
3094 }
3095
3096 static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
3097 {
3098         struct cfi_state *cfi1 = insn->cfi;
3099         int i;
3100
3101         if (!cfi1) {
3102                 WARN("CFI missing");
3103                 return false;
3104         }
3105
3106         if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
3107
3108                 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
3109                           insn->sec, insn->offset,
3110                           cfi1->cfa.base, cfi1->cfa.offset,
3111                           cfi2->cfa.base, cfi2->cfa.offset);
3112
3113         } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
3114                 for (i = 0; i < CFI_NUM_REGS; i++) {
3115                         if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
3116                                     sizeof(struct cfi_reg)))
3117                                 continue;
3118
3119                         WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
3120                                   insn->sec, insn->offset,
3121                                   i, cfi1->regs[i].base, cfi1->regs[i].offset,
3122                                   i, cfi2->regs[i].base, cfi2->regs[i].offset);
3123                         break;
3124                 }
3125
3126         } else if (cfi1->type != cfi2->type) {
3127
3128                 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
3129                           insn->sec, insn->offset, cfi1->type, cfi2->type);
3130
3131         } else if (cfi1->drap != cfi2->drap ||
3132                    (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
3133                    (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
3134
3135                 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
3136                           insn->sec, insn->offset,
3137                           cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
3138                           cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
3139
3140         } else
3141                 return true;
3142
3143         return false;
3144 }
3145
3146 static inline bool func_uaccess_safe(struct symbol *func)
3147 {
3148         if (func)
3149                 return func->uaccess_safe;
3150
3151         return false;
3152 }
3153
3154 static inline const char *call_dest_name(struct instruction *insn)
3155 {
3156         static char pvname[19];
3157         struct reloc *rel;
3158         int idx;
3159
3160         if (insn->call_dest)
3161                 return insn->call_dest->name;
3162
3163         rel = insn_reloc(NULL, insn);
3164         if (rel && !strcmp(rel->sym->name, "pv_ops")) {
3165                 idx = (rel->addend / sizeof(void *));
3166                 snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
3167                 return pvname;
3168         }
3169
3170         return "{dynamic}";
3171 }
3172
3173 static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
3174 {
3175         struct symbol *target;
3176         struct reloc *rel;
3177         int idx;
3178
3179         rel = insn_reloc(file, insn);
3180         if (!rel || strcmp(rel->sym->name, "pv_ops"))
3181                 return false;
3182
3183         idx = (arch_dest_reloc_offset(rel->addend) / sizeof(void *));
3184
3185         if (file->pv_ops[idx].clean)
3186                 return true;
3187
3188         file->pv_ops[idx].clean = true;
3189
3190         list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
3191                 if (!target->sec->noinstr) {
3192                         WARN("pv_ops[%d]: %s", idx, target->name);
3193                         file->pv_ops[idx].clean = false;
3194                 }
3195         }
3196
3197         return file->pv_ops[idx].clean;
3198 }
3199
3200 static inline bool noinstr_call_dest(struct objtool_file *file,
3201                                      struct instruction *insn,
3202                                      struct symbol *func)
3203 {
3204         /*
3205          * We can't deal with indirect function calls at present;
3206          * assume they're instrumented.
3207          */
3208         if (!func) {
3209                 if (file->pv_ops)
3210                         return pv_call_dest(file, insn);
3211
3212                 return false;
3213         }
3214
3215         /*
3216          * If the symbol is from a noinstr section; we good.
3217          */
3218         if (func->sec->noinstr)
3219                 return true;
3220
3221         /*
3222          * The __ubsan_handle_*() calls are like WARN(), they only happen when
3223          * something 'BAD' happened. At the risk of taking the machine down,
3224          * let them proceed to get the message out.
3225          */
3226         if (!strncmp(func->name, "__ubsan_handle_", 15))
3227                 return true;
3228
3229         return false;
3230 }
3231
3232 static int validate_call(struct objtool_file *file,
3233                          struct instruction *insn,
3234                          struct insn_state *state)
3235 {
3236         if (state->noinstr && state->instr <= 0 &&
3237             !noinstr_call_dest(file, insn, insn->call_dest)) {
3238                 WARN_FUNC("call to %s() leaves .noinstr.text section",
3239                                 insn->sec, insn->offset, call_dest_name(insn));
3240                 return 1;
3241         }
3242
3243         if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
3244                 WARN_FUNC("call to %s() with UACCESS enabled",
3245                                 insn->sec, insn->offset, call_dest_name(insn));
3246                 return 1;
3247         }
3248
3249         if (state->df) {
3250                 WARN_FUNC("call to %s() with DF set",
3251                                 insn->sec, insn->offset, call_dest_name(insn));
3252                 return 1;
3253         }
3254
3255         return 0;
3256 }
3257
3258 static int validate_sibling_call(struct objtool_file *file,
3259                                  struct instruction *insn,
3260                                  struct insn_state *state)
3261 {
3262         if (has_modified_stack_frame(insn, state)) {
3263                 WARN_FUNC("sibling call from callable instruction with modified stack frame",
3264                                 insn->sec, insn->offset);
3265                 return 1;
3266         }
3267
3268         return validate_call(file, insn, state);
3269 }
3270
3271 static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
3272 {
3273         if (state->noinstr && state->instr > 0) {
3274                 WARN_FUNC("return with instrumentation enabled",
3275                           insn->sec, insn->offset);
3276                 return 1;
3277         }
3278
3279         if (state->uaccess && !func_uaccess_safe(func)) {
3280                 WARN_FUNC("return with UACCESS enabled",
3281                           insn->sec, insn->offset);
3282                 return 1;
3283         }
3284
3285         if (!state->uaccess && func_uaccess_safe(func)) {
3286                 WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function",
3287                           insn->sec, insn->offset);
3288                 return 1;
3289         }
3290
3291         if (state->df) {
3292                 WARN_FUNC("return with DF set",
3293                           insn->sec, insn->offset);
3294                 return 1;
3295         }
3296
3297         if (func && has_modified_stack_frame(insn, state)) {
3298                 WARN_FUNC("return with modified stack frame",
3299                           insn->sec, insn->offset);
3300                 return 1;
3301         }
3302
3303         if (state->cfi.bp_scratch) {
3304                 WARN_FUNC("BP used as a scratch register",
3305                           insn->sec, insn->offset);
3306                 return 1;
3307         }
3308
3309         return 0;
3310 }
3311
3312 static struct instruction *next_insn_to_validate(struct objtool_file *file,
3313                                                  struct instruction *insn)
3314 {
3315         struct alt_group *alt_group = insn->alt_group;
3316
3317         /*
3318          * Simulate the fact that alternatives are patched in-place.  When the
3319          * end of a replacement alt_group is reached, redirect objtool flow to
3320          * the end of the original alt_group.
3321          */
3322         if (alt_group && insn == alt_group->last_insn && alt_group->orig_group)
3323                 return next_insn_same_sec(file, alt_group->orig_group->last_insn);
3324
3325         return next_insn_same_sec(file, insn);
3326 }
3327
3328 /*
3329  * Follow the branch starting at the given instruction, and recursively follow
3330  * any other branches (jumps).  Meanwhile, track the frame pointer state at
3331  * each instruction and validate all the rules described in
3332  * tools/objtool/Documentation/objtool.txt.
3333  */
3334 static int validate_branch(struct objtool_file *file, struct symbol *func,
3335                            struct instruction *insn, struct insn_state state)
3336 {
3337         struct alternative *alt;
3338         struct instruction *next_insn, *prev_insn = NULL;
3339         struct section *sec;
3340         u8 visited;
3341         int ret;
3342
3343         sec = insn->sec;
3344
3345         while (1) {
3346                 next_insn = next_insn_to_validate(file, insn);
3347
3348                 if (func && insn->func && func != insn->func->pfunc) {
3349                         /* Ignore KCFI type preambles, which always fall through */
3350                         if (!strncmp(func->name, "__cfi_", 6))
3351                                 return 0;
3352
3353                         WARN("%s() falls through to next function %s()",
3354                              func->name, insn->func->name);
3355                         return 1;
3356                 }
3357
3358                 if (func && insn->ignore) {
3359                         WARN_FUNC("BUG: why am I validating an ignored function?",
3360                                   sec, insn->offset);
3361                         return 1;
3362                 }
3363
3364                 visited = VISITED_BRANCH << state.uaccess;
3365                 if (insn->visited & VISITED_BRANCH_MASK) {
3366                         if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
3367                                 return 1;
3368
3369                         if (insn->visited & visited)
3370                                 return 0;
3371                 } else {
3372                         nr_insns_visited++;
3373                 }
3374
3375                 if (state.noinstr)
3376                         state.instr += insn->instr;
3377
3378                 if (insn->hint) {
3379                         if (insn->restore) {
3380                                 struct instruction *save_insn, *i;
3381
3382                                 i = insn;
3383                                 save_insn = NULL;
3384
3385                                 sym_for_each_insn_continue_reverse(file, func, i) {
3386                                         if (i->save) {
3387                                                 save_insn = i;
3388                                                 break;
3389                                         }
3390                                 }
3391
3392                                 if (!save_insn) {
3393                                         WARN_FUNC("no corresponding CFI save for CFI restore",
3394                                                   sec, insn->offset);
3395                                         return 1;
3396                                 }
3397
3398                                 if (!save_insn->visited) {
3399                                         WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
3400                                                   sec, insn->offset);
3401                                         return 1;
3402                                 }
3403
3404                                 insn->cfi = save_insn->cfi;
3405                                 nr_cfi_reused++;
3406                         }
3407
3408                         state.cfi = *insn->cfi;
3409                 } else {
3410                         /* XXX track if we actually changed state.cfi */
3411
3412                         if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {
3413                                 insn->cfi = prev_insn->cfi;
3414                                 nr_cfi_reused++;
3415                         } else {
3416                                 insn->cfi = cfi_hash_find_or_add(&state.cfi);
3417                         }
3418                 }
3419
3420                 insn->visited |= visited;
3421
3422                 if (propagate_alt_cfi(file, insn))
3423                         return 1;
3424
3425                 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
3426                         bool skip_orig = false;
3427
3428                         list_for_each_entry(alt, &insn->alts, list) {
3429                                 if (alt->skip_orig)
3430                                         skip_orig = true;
3431
3432                                 ret = validate_branch(file, func, alt->insn, state);
3433                                 if (ret) {
3434                                         if (opts.backtrace)
3435                                                 BT_FUNC("(alt)", insn);
3436                                         return ret;
3437                                 }
3438                         }
3439
3440                         if (skip_orig)
3441                                 return 0;
3442                 }
3443
3444                 if (handle_insn_ops(insn, next_insn, &state))
3445                         return 1;
3446
3447                 switch (insn->type) {
3448
3449                 case INSN_RETURN:
3450                         return validate_return(func, insn, &state);
3451
3452                 case INSN_CALL:
3453                 case INSN_CALL_DYNAMIC:
3454                         ret = validate_call(file, insn, &state);
3455                         if (ret)
3456                                 return ret;
3457
3458                         if (opts.stackval && func && !is_fentry_call(insn) &&
3459                             !has_valid_stack_frame(&state)) {
3460                                 WARN_FUNC("call without frame pointer save/setup",
3461                                           sec, insn->offset);
3462                                 return 1;
3463                         }
3464
3465                         if (insn->dead_end)
3466                                 return 0;
3467
3468                         break;
3469
3470                 case INSN_JUMP_CONDITIONAL:
3471                 case INSN_JUMP_UNCONDITIONAL:
3472                         if (is_sibling_call(insn)) {
3473                                 ret = validate_sibling_call(file, insn, &state);
3474                                 if (ret)
3475                                         return ret;
3476
3477                         } else if (insn->jump_dest) {
3478                                 ret = validate_branch(file, func,
3479                                                       insn->jump_dest, state);
3480                                 if (ret) {
3481                                         if (opts.backtrace)
3482                                                 BT_FUNC("(branch)", insn);
3483                                         return ret;
3484                                 }
3485                         }
3486
3487                         if (insn->type == INSN_JUMP_UNCONDITIONAL)
3488                                 return 0;
3489
3490                         break;
3491
3492                 case INSN_JUMP_DYNAMIC:
3493                 case INSN_JUMP_DYNAMIC_CONDITIONAL:
3494                         if (is_sibling_call(insn)) {
3495                                 ret = validate_sibling_call(file, insn, &state);
3496                                 if (ret)
3497                                         return ret;
3498                         }
3499
3500                         if (insn->type == INSN_JUMP_DYNAMIC)
3501                                 return 0;
3502
3503                         break;
3504
3505                 case INSN_CONTEXT_SWITCH:
3506                         if (func && (!next_insn || !next_insn->hint)) {
3507                                 WARN_FUNC("unsupported instruction in callable function",
3508                                           sec, insn->offset);
3509                                 return 1;
3510                         }
3511                         return 0;
3512
3513                 case INSN_STAC:
3514                         if (state.uaccess) {
3515                                 WARN_FUNC("recursive UACCESS enable", sec, insn->offset);
3516                                 return 1;
3517                         }
3518
3519                         state.uaccess = true;
3520                         break;
3521
3522                 case INSN_CLAC:
3523                         if (!state.uaccess && func) {
3524                                 WARN_FUNC("redundant UACCESS disable", sec, insn->offset);
3525                                 return 1;
3526                         }
3527
3528                         if (func_uaccess_safe(func) && !state.uaccess_stack) {
3529                                 WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset);
3530                                 return 1;
3531                         }
3532
3533                         state.uaccess = false;
3534                         break;
3535
3536                 case INSN_STD:
3537                         if (state.df) {
3538                                 WARN_FUNC("recursive STD", sec, insn->offset);
3539                                 return 1;
3540                         }
3541
3542                         state.df = true;
3543                         break;
3544
3545                 case INSN_CLD:
3546                         if (!state.df && func) {
3547                                 WARN_FUNC("redundant CLD", sec, insn->offset);
3548                                 return 1;
3549                         }
3550
3551                         state.df = false;
3552                         break;
3553
3554                 default:
3555                         break;
3556                 }
3557
3558                 if (insn->dead_end)
3559                         return 0;
3560
3561                 if (!next_insn) {
3562                         if (state.cfi.cfa.base == CFI_UNDEFINED)
3563                                 return 0;
3564                         WARN("%s: unexpected end of section", sec->name);
3565                         return 1;
3566                 }
3567
3568                 prev_insn = insn;
3569                 insn = next_insn;
3570         }
3571
3572         return 0;
3573 }
3574
3575 static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
3576 {
3577         struct instruction *insn;
3578         struct insn_state state;
3579         int ret, warnings = 0;
3580
3581         if (!file->hints)
3582                 return 0;
3583
3584         init_insn_state(file, &state, sec);
3585
3586         if (sec) {
3587                 insn = find_insn(file, sec, 0);
3588                 if (!insn)
3589                         return 0;
3590         } else {
3591                 insn = list_first_entry(&file->insn_list, typeof(*insn), list);
3592         }
3593
3594         while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
3595                 if (insn->hint && !insn->visited && !insn->ignore) {
3596                         ret = validate_branch(file, insn->func, insn, state);
3597                         if (ret && opts.backtrace)
3598                                 BT_FUNC("<=== (hint)", insn);
3599                         warnings += ret;
3600                 }
3601
3602                 insn = list_next_entry(insn, list);
3603         }
3604
3605         return warnings;
3606 }
3607
3608 /*
3609  * Validate rethunk entry constraint: must untrain RET before the first RET.
3610  *
3611  * Follow every branch (intra-function) and ensure ANNOTATE_UNRET_END comes
3612  * before an actual RET instruction.
3613  */
3614 static int validate_entry(struct objtool_file *file, struct instruction *insn)
3615 {
3616         struct instruction *next, *dest;
3617         int ret, warnings = 0;
3618
3619         for (;;) {
3620                 next = next_insn_to_validate(file, insn);
3621
3622                 if (insn->visited & VISITED_ENTRY)
3623                         return 0;
3624
3625                 insn->visited |= VISITED_ENTRY;
3626
3627                 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
3628                         struct alternative *alt;
3629                         bool skip_orig = false;
3630
3631                         list_for_each_entry(alt, &insn->alts, list) {
3632                                 if (alt->skip_orig)
3633                                         skip_orig = true;
3634
3635                                 ret = validate_entry(file, alt->insn);
3636                                 if (ret) {
3637                                         if (opts.backtrace)
3638                                                 BT_FUNC("(alt)", insn);
3639                                         return ret;
3640                                 }
3641                         }
3642
3643                         if (skip_orig)
3644                                 return 0;
3645                 }
3646
3647                 switch (insn->type) {
3648
3649                 case INSN_CALL_DYNAMIC:
3650                 case INSN_JUMP_DYNAMIC:
3651                 case INSN_JUMP_DYNAMIC_CONDITIONAL:
3652                         WARN_FUNC("early indirect call", insn->sec, insn->offset);
3653                         return 1;
3654
3655                 case INSN_JUMP_UNCONDITIONAL:
3656                 case INSN_JUMP_CONDITIONAL:
3657                         if (!is_sibling_call(insn)) {
3658                                 if (!insn->jump_dest) {
3659                                         WARN_FUNC("unresolved jump target after linking?!?",
3660                                                   insn->sec, insn->offset);
3661                                         return -1;
3662                                 }
3663                                 ret = validate_entry(file, insn->jump_dest);
3664                                 if (ret) {
3665                                         if (opts.backtrace) {
3666                                                 BT_FUNC("(branch%s)", insn,
3667                                                         insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
3668                                         }
3669                                         return ret;
3670                                 }
3671
3672                                 if (insn->type == INSN_JUMP_UNCONDITIONAL)
3673                                         return 0;
3674
3675                                 break;
3676                         }
3677
3678                         /* fallthrough */
3679                 case INSN_CALL:
3680                         dest = find_insn(file, insn->call_dest->sec,
3681                                          insn->call_dest->offset);
3682                         if (!dest) {
3683                                 WARN("Unresolved function after linking!?: %s",
3684                                      insn->call_dest->name);
3685                                 return -1;
3686                         }
3687
3688                         ret = validate_entry(file, dest);
3689                         if (ret) {
3690                                 if (opts.backtrace)
3691                                         BT_FUNC("(call)", insn);
3692                                 return ret;
3693                         }
3694                         /*
3695                          * If a call returns without error, it must have seen UNTRAIN_RET.
3696                          * Therefore any non-error return is a success.
3697                          */
3698                         return 0;
3699
3700                 case INSN_RETURN:
3701                         WARN_FUNC("RET before UNTRAIN", insn->sec, insn->offset);
3702                         return 1;
3703
3704                 case INSN_NOP:
3705                         if (insn->retpoline_safe)
3706                                 return 0;
3707                         break;
3708
3709                 default:
3710                         break;
3711                 }
3712
3713                 if (!next) {
3714                         WARN_FUNC("teh end!", insn->sec, insn->offset);
3715                         return -1;
3716                 }
3717                 insn = next;
3718         }
3719
3720         return warnings;
3721 }
3722
3723 /*
3724  * Validate that all branches starting at 'insn->entry' encounter UNRET_END
3725  * before RET.
3726  */
3727 static int validate_unret(struct objtool_file *file)
3728 {
3729         struct instruction *insn;
3730         int ret, warnings = 0;
3731
3732         for_each_insn(file, insn) {
3733                 if (!insn->entry)
3734                         continue;
3735
3736                 ret = validate_entry(file, insn);
3737                 if (ret < 0) {
3738                         WARN_FUNC("Failed UNRET validation", insn->sec, insn->offset);
3739                         return ret;
3740                 }
3741                 warnings += ret;
3742         }
3743
3744         return warnings;
3745 }
3746
3747 static int validate_retpoline(struct objtool_file *file)
3748 {
3749         struct instruction *insn;
3750         int warnings = 0;
3751
3752         for_each_insn(file, insn) {
3753                 if (insn->type != INSN_JUMP_DYNAMIC &&
3754                     insn->type != INSN_CALL_DYNAMIC &&
3755                     insn->type != INSN_RETURN)
3756                         continue;
3757
3758                 if (insn->retpoline_safe)
3759                         continue;
3760
3761                 /*
3762                  * .init.text code is ran before userspace and thus doesn't
3763                  * strictly need retpolines, except for modules which are
3764                  * loaded late, they very much do need retpoline in their
3765                  * .init.text
3766                  */
3767                 if (!strcmp(insn->sec->name, ".init.text") && !opts.module)
3768                         continue;
3769
3770                 if (insn->type == INSN_RETURN) {
3771                         if (opts.rethunk) {
3772                                 WARN_FUNC("'naked' return found in RETHUNK build",
3773                                           insn->sec, insn->offset);
3774                         } else
3775                                 continue;
3776                 } else {
3777                         WARN_FUNC("indirect %s found in RETPOLINE build",
3778                                   insn->sec, insn->offset,
3779                                   insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
3780                 }
3781
3782                 warnings++;
3783         }
3784
3785         return warnings;
3786 }
3787
3788 static bool is_kasan_insn(struct instruction *insn)
3789 {
3790         return (insn->type == INSN_CALL &&
3791                 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
3792 }
3793
3794 static bool is_ubsan_insn(struct instruction *insn)
3795 {
3796         return (insn->type == INSN_CALL &&
3797                 !strcmp(insn->call_dest->name,
3798                         "__ubsan_handle_builtin_unreachable"));
3799 }
3800
3801 static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
3802 {
3803         int i;
3804         struct instruction *prev_insn;
3805
3806         if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
3807                 return true;
3808
3809         /*
3810          * Ignore alternative replacement instructions.  This can happen
3811          * when a whitelisted function uses one of the ALTERNATIVE macros.
3812          */
3813         if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
3814             !strcmp(insn->sec->name, ".altinstr_aux"))
3815                 return true;
3816
3817         /*
3818          * Whole archive runs might encounter dead code from weak symbols.
3819          * This is where the linker will have dropped the weak symbol in
3820          * favour of a regular symbol, but leaves the code in place.
3821          *
3822          * In this case we'll find a piece of code (whole function) that is not
3823          * covered by a !section symbol. Ignore them.
3824          */
3825         if (opts.link && !insn->func) {
3826                 int size = find_symbol_hole_containing(insn->sec, insn->offset);
3827                 unsigned long end = insn->offset + size;
3828
3829                 if (!size) /* not a hole */
3830                         return false;
3831
3832                 if (size < 0) /* hole until the end */
3833                         return true;
3834
3835                 sec_for_each_insn_continue(file, insn) {
3836                         /*
3837                          * If we reach a visited instruction at or before the
3838                          * end of the hole, ignore the unreachable.
3839                          */
3840                         if (insn->visited)
3841                                 return true;
3842
3843                         if (insn->offset >= end)
3844                                 break;
3845
3846                         /*
3847                          * If this hole jumps to a .cold function, mark it ignore too.
3848                          */
3849                         if (insn->jump_dest && insn->jump_dest->func &&
3850                             strstr(insn->jump_dest->func->name, ".cold")) {
3851                                 struct instruction *dest = insn->jump_dest;
3852                                 func_for_each_insn(file, dest->func, dest)
3853                                         dest->ignore = true;
3854                         }
3855                 }
3856
3857                 return false;
3858         }
3859
3860         if (!insn->func)
3861                 return false;
3862
3863         if (insn->func->static_call_tramp)
3864                 return true;
3865
3866         /*
3867          * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
3868          * __builtin_unreachable().  The BUG() macro has an unreachable() after
3869          * the UD2, which causes GCC's undefined trap logic to emit another UD2
3870          * (or occasionally a JMP to UD2).
3871          *
3872          * It may also insert a UD2 after calling a __noreturn function.
3873          */
3874         prev_insn = list_prev_entry(insn, list);
3875         if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&
3876             (insn->type == INSN_BUG ||
3877              (insn->type == INSN_JUMP_UNCONDITIONAL &&
3878               insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
3879                 return true;
3880
3881         /*
3882          * Check if this (or a subsequent) instruction is related to
3883          * CONFIG_UBSAN or CONFIG_KASAN.
3884          *
3885          * End the search at 5 instructions to avoid going into the weeds.
3886          */
3887         for (i = 0; i < 5; i++) {
3888
3889                 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
3890                         return true;
3891
3892                 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
3893                         if (insn->jump_dest &&
3894                             insn->jump_dest->func == insn->func) {
3895                                 insn = insn->jump_dest;
3896                                 continue;
3897                         }
3898
3899                         break;
3900                 }
3901
3902                 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
3903                         break;
3904
3905                 insn = list_next_entry(insn, list);
3906         }
3907
3908         return false;
3909 }
3910
3911 static int validate_symbol(struct objtool_file *file, struct section *sec,
3912                            struct symbol *sym, struct insn_state *state)
3913 {
3914         struct instruction *insn;
3915         int ret;
3916
3917         if (!sym->len) {
3918                 WARN("%s() is missing an ELF size annotation", sym->name);
3919                 return 1;
3920         }
3921
3922         if (sym->pfunc != sym || sym->alias != sym)
3923                 return 0;
3924
3925         insn = find_insn(file, sec, sym->offset);
3926         if (!insn || insn->ignore || insn->visited)
3927                 return 0;
3928
3929         state->uaccess = sym->uaccess_safe;
3930
3931         ret = validate_branch(file, insn->func, insn, *state);
3932         if (ret && opts.backtrace)
3933                 BT_FUNC("<=== (sym)", insn);
3934         return ret;
3935 }
3936
3937 static int validate_section(struct objtool_file *file, struct section *sec)
3938 {
3939         struct insn_state state;
3940         struct symbol *func;
3941         int warnings = 0;
3942
3943         list_for_each_entry(func, &sec->symbol_list, list) {
3944                 if (func->type != STT_FUNC)
3945                         continue;
3946
3947                 init_insn_state(file, &state, sec);
3948                 set_func_state(&state.cfi);
3949
3950                 warnings += validate_symbol(file, sec, func, &state);
3951         }
3952
3953         return warnings;
3954 }
3955
3956 static int validate_noinstr_sections(struct objtool_file *file)
3957 {
3958         struct section *sec;
3959         int warnings = 0;
3960
3961         sec = find_section_by_name(file->elf, ".noinstr.text");
3962         if (sec) {
3963                 warnings += validate_section(file, sec);
3964                 warnings += validate_unwind_hints(file, sec);
3965         }
3966
3967         sec = find_section_by_name(file->elf, ".entry.text");
3968         if (sec) {
3969                 warnings += validate_section(file, sec);
3970                 warnings += validate_unwind_hints(file, sec);
3971         }
3972
3973         return warnings;
3974 }
3975
3976 static int validate_functions(struct objtool_file *file)
3977 {
3978         struct section *sec;
3979         int warnings = 0;
3980
3981         for_each_sec(file, sec) {
3982                 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
3983                         continue;
3984
3985                 warnings += validate_section(file, sec);
3986         }
3987
3988         return warnings;
3989 }
3990
3991 static void mark_endbr_used(struct instruction *insn)
3992 {
3993         if (!list_empty(&insn->call_node))
3994                 list_del_init(&insn->call_node);
3995 }
3996
3997 static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
3998 {
3999         struct instruction *dest;
4000         struct reloc *reloc;
4001         unsigned long off;
4002         int warnings = 0;
4003
4004         /*
4005          * Looking for function pointer load relocations.  Ignore
4006          * direct/indirect branches:
4007          */
4008         switch (insn->type) {
4009         case INSN_CALL:
4010         case INSN_CALL_DYNAMIC:
4011         case INSN_JUMP_CONDITIONAL:
4012         case INSN_JUMP_UNCONDITIONAL:
4013         case INSN_JUMP_DYNAMIC:
4014         case INSN_JUMP_DYNAMIC_CONDITIONAL:
4015         case INSN_RETURN:
4016         case INSN_NOP:
4017                 return 0;
4018         default:
4019                 break;
4020         }
4021
4022         for (reloc = insn_reloc(file, insn);
4023              reloc;
4024              reloc = find_reloc_by_dest_range(file->elf, insn->sec,
4025                                               reloc->offset + 1,
4026                                               (insn->offset + insn->len) - (reloc->offset + 1))) {
4027
4028                 /*
4029                  * static_call_update() references the trampoline, which
4030                  * doesn't have (or need) ENDBR.  Skip warning in that case.
4031                  */
4032                 if (reloc->sym->static_call_tramp)
4033                         continue;
4034
4035                 off = reloc->sym->offset;
4036                 if (reloc->type == R_X86_64_PC32 || reloc->type == R_X86_64_PLT32)
4037                         off += arch_dest_reloc_offset(reloc->addend);
4038                 else
4039                         off += reloc->addend;
4040
4041                 dest = find_insn(file, reloc->sym->sec, off);
4042                 if (!dest)
4043                         continue;
4044
4045                 if (dest->type == INSN_ENDBR) {
4046                         mark_endbr_used(dest);
4047                         continue;
4048                 }
4049
4050                 if (dest->func && dest->func == insn->func) {
4051                         /*
4052                          * Anything from->to self is either _THIS_IP_ or
4053                          * IRET-to-self.
4054                          *
4055                          * There is no sane way to annotate _THIS_IP_ since the
4056                          * compiler treats the relocation as a constant and is
4057                          * happy to fold in offsets, skewing any annotation we
4058                          * do, leading to vast amounts of false-positives.
4059                          *
4060                          * There's also compiler generated _THIS_IP_ through
4061                          * KCOV and such which we have no hope of annotating.
4062                          *
4063                          * As such, blanket accept self-references without
4064                          * issue.
4065                          */
4066                         continue;
4067                 }
4068
4069                 if (dest->noendbr)
4070                         continue;
4071
4072                 WARN_FUNC("relocation to !ENDBR: %s",
4073                           insn->sec, insn->offset,
4074                           offstr(dest->sec, dest->offset));
4075
4076                 warnings++;
4077         }
4078
4079         return warnings;
4080 }
4081
4082 static int validate_ibt_data_reloc(struct objtool_file *file,
4083                                    struct reloc *reloc)
4084 {
4085         struct instruction *dest;
4086
4087         dest = find_insn(file, reloc->sym->sec,
4088                          reloc->sym->offset + reloc->addend);
4089         if (!dest)
4090                 return 0;
4091
4092         if (dest->type == INSN_ENDBR) {
4093                 mark_endbr_used(dest);
4094                 return 0;
4095         }
4096
4097         if (dest->noendbr)
4098                 return 0;
4099
4100         WARN_FUNC("data relocation to !ENDBR: %s",
4101                   reloc->sec->base, reloc->offset,
4102                   offstr(dest->sec, dest->offset));
4103
4104         return 1;
4105 }
4106
4107 /*
4108  * Validate IBT rules and remove used ENDBR instructions from the seal list.
4109  * Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
4110  * NOPs) later, in create_ibt_endbr_seal_sections().
4111  */
4112 static int validate_ibt(struct objtool_file *file)
4113 {
4114         struct section *sec;
4115         struct reloc *reloc;
4116         struct instruction *insn;
4117         int warnings = 0;
4118
4119         for_each_insn(file, insn)
4120                 warnings += validate_ibt_insn(file, insn);
4121
4122         for_each_sec(file, sec) {
4123
4124                 /* Already done by validate_ibt_insn() */
4125                 if (sec->sh.sh_flags & SHF_EXECINSTR)
4126                         continue;
4127
4128                 if (!sec->reloc)
4129                         continue;
4130
4131                 /*
4132                  * These sections can reference text addresses, but not with
4133                  * the intent to indirect branch to them.
4134                  */
4135                 if ((!strncmp(sec->name, ".discard", 8) &&
4136                      strcmp(sec->name, ".discard.ibt_endbr_noseal"))    ||
4137                     !strncmp(sec->name, ".debug", 6)                    ||
4138                     !strcmp(sec->name, ".altinstructions")              ||
4139                     !strcmp(sec->name, ".ibt_endbr_seal")               ||
4140                     !strcmp(sec->name, ".orc_unwind_ip")                ||
4141                     !strcmp(sec->name, ".parainstructions")             ||
4142                     !strcmp(sec->name, ".retpoline_sites")              ||
4143                     !strcmp(sec->name, ".smp_locks")                    ||
4144                     !strcmp(sec->name, ".static_call_sites")            ||
4145                     !strcmp(sec->name, "_error_injection_whitelist")    ||
4146                     !strcmp(sec->name, "_kprobe_blacklist")             ||
4147                     !strcmp(sec->name, "__bug_table")                   ||
4148                     !strcmp(sec->name, "__ex_table")                    ||
4149                     !strcmp(sec->name, "__jump_table")                  ||
4150                     !strcmp(sec->name, "__mcount_loc")                  ||
4151                     !strcmp(sec->name, ".kcfi_traps")                   ||
4152                     strstr(sec->name, "__patchable_function_entries"))
4153                         continue;
4154
4155                 list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
4156                         warnings += validate_ibt_data_reloc(file, reloc);
4157         }
4158
4159         return warnings;
4160 }
4161
4162 static int validate_sls(struct objtool_file *file)
4163 {
4164         struct instruction *insn, *next_insn;
4165         int warnings = 0;
4166
4167         for_each_insn(file, insn) {
4168                 next_insn = next_insn_same_sec(file, insn);
4169
4170                 if (insn->retpoline_safe)
4171                         continue;
4172
4173                 switch (insn->type) {
4174                 case INSN_RETURN:
4175                         if (!next_insn || next_insn->type != INSN_TRAP) {
4176                                 WARN_FUNC("missing int3 after ret",
4177                                           insn->sec, insn->offset);
4178                                 warnings++;
4179                         }
4180
4181                         break;
4182                 case INSN_JUMP_DYNAMIC:
4183                         if (!next_insn || next_insn->type != INSN_TRAP) {
4184                                 WARN_FUNC("missing int3 after indirect jump",
4185                                           insn->sec, insn->offset);
4186                                 warnings++;
4187                         }
4188                         break;
4189                 default:
4190                         break;
4191                 }
4192         }
4193
4194         return warnings;
4195 }
4196
4197 static int validate_reachable_instructions(struct objtool_file *file)
4198 {
4199         struct instruction *insn;
4200
4201         if (file->ignore_unreachables)
4202                 return 0;
4203
4204         for_each_insn(file, insn) {
4205                 if (insn->visited || ignore_unreachable_insn(file, insn))
4206                         continue;
4207
4208                 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
4209                 return 1;
4210         }
4211
4212         return 0;
4213 }
4214
4215 int check(struct objtool_file *file)
4216 {
4217         int ret, warnings = 0;
4218
4219         arch_initial_func_cfi_state(&initial_func_cfi);
4220         init_cfi_state(&init_cfi);
4221         init_cfi_state(&func_cfi);
4222         set_func_state(&func_cfi);
4223
4224         if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
4225                 goto out;
4226
4227         cfi_hash_add(&init_cfi);
4228         cfi_hash_add(&func_cfi);
4229
4230         ret = decode_sections(file);
4231         if (ret < 0)
4232                 goto out;
4233
4234         warnings += ret;
4235
4236         if (list_empty(&file->insn_list))
4237                 goto out;
4238
4239         if (opts.retpoline) {
4240                 ret = validate_retpoline(file);
4241                 if (ret < 0)
4242                         return ret;
4243                 warnings += ret;
4244         }
4245
4246         if (opts.stackval || opts.orc || opts.uaccess) {
4247                 ret = validate_functions(file);
4248                 if (ret < 0)
4249                         goto out;
4250                 warnings += ret;
4251
4252                 ret = validate_unwind_hints(file, NULL);
4253                 if (ret < 0)
4254                         goto out;
4255                 warnings += ret;
4256
4257                 if (!warnings) {
4258                         ret = validate_reachable_instructions(file);
4259                         if (ret < 0)
4260                                 goto out;
4261                         warnings += ret;
4262                 }
4263
4264         } else if (opts.noinstr) {
4265                 ret = validate_noinstr_sections(file);
4266                 if (ret < 0)
4267                         goto out;
4268                 warnings += ret;
4269         }
4270
4271         if (opts.unret) {
4272                 /*
4273                  * Must be after validate_branch() and friends, it plays
4274                  * further games with insn->visited.
4275                  */
4276                 ret = validate_unret(file);
4277                 if (ret < 0)
4278                         return ret;
4279                 warnings += ret;
4280         }
4281
4282         if (opts.ibt) {
4283                 ret = validate_ibt(file);
4284                 if (ret < 0)
4285                         goto out;
4286                 warnings += ret;
4287         }
4288
4289         if (opts.sls) {
4290                 ret = validate_sls(file);
4291                 if (ret < 0)
4292                         goto out;
4293                 warnings += ret;
4294         }
4295
4296         if (opts.static_call) {
4297                 ret = create_static_call_sections(file);
4298                 if (ret < 0)
4299                         goto out;
4300                 warnings += ret;
4301         }
4302
4303         if (opts.retpoline) {
4304                 ret = create_retpoline_sites_sections(file);
4305                 if (ret < 0)
4306                         goto out;
4307                 warnings += ret;
4308         }
4309
4310         if (opts.rethunk) {
4311                 ret = create_return_sites_sections(file);
4312                 if (ret < 0)
4313                         goto out;
4314                 warnings += ret;
4315         }
4316
4317         if (opts.mcount) {
4318                 ret = create_mcount_loc_sections(file);
4319                 if (ret < 0)
4320                         goto out;
4321                 warnings += ret;
4322         }
4323
4324         if (opts.ibt) {
4325                 ret = create_ibt_endbr_seal_sections(file);
4326                 if (ret < 0)
4327                         goto out;
4328                 warnings += ret;
4329         }
4330
4331         if (opts.orc && !list_empty(&file->insn_list)) {
4332                 ret = orc_create(file);
4333                 if (ret < 0)
4334                         goto out;
4335                 warnings += ret;
4336         }
4337
4338
4339         if (opts.stats) {
4340                 printf("nr_insns_visited: %ld\n", nr_insns_visited);
4341                 printf("nr_cfi: %ld\n", nr_cfi);
4342                 printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
4343                 printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
4344         }
4345
4346 out:
4347         /*
4348          *  For now, don't fail the kernel build on fatal warnings.  These
4349          *  errors are still fairly common due to the growing matrix of
4350          *  supported toolchains and their recent pace of change.
4351          */
4352         return 0;
4353 }