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.", 13))
 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                         free(key_name);
 672                         return -1;
 673                 }
 674                 tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
 675                 memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
 676
 677                 key_sym = find_symbol_by_name(file->elf, tmp);
 678                 if (!key_sym) {
 679                         if (!opts.module) {
 680                                 WARN("static_call: can't find static_call_key symbol: %s", tmp);
 681                                 free(key_name);
 682                                 return -1;
 683                         }
 684
 685                         /*
 686                          * For modules(), the key might not be exported, which
 687                          * means the module can make static calls but isn't
 688                          * allowed to change them.
 689                          *
 690                          * In that case we temporarily set the key to be the
 691                          * trampoline address.  This is fixed up in
 692                          * static_call_add_module().
 693                          */
 694                         key_sym = insn->call_dest;
 695                 }
 696                 free(key_name);
 697
 698                 /* populate reloc for 'key' */
 699                 if (elf_add_reloc(file->elf, sec,
 700                                   idx * sizeof(struct static_call_site) + 4,
 701                                   R_X86_64_PC32, key_sym,
 702                                   is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
 703                         return -1;
 704
 705                 idx++;
 706         }
 707
 708         return 0;
 709 }
 710
 711 static int create_retpoline_sites_sections(struct objtool_file *file)
 712 {
 713         struct instruction *insn;
 714         struct section *sec;
 715         int idx;
 716
 717         sec = find_section_by_name(file->elf, ".retpoline_sites");
 718         if (sec) {
 719                 WARN("file already has .retpoline_sites, skipping");
 720                 return 0;
 721         }
 722
 723         idx = 0;
 724         list_for_each_entry(insn, &file->retpoline_call_list, call_node)
 725                 idx++;
 726
 727         if (!idx)
 728                 return 0;
 729
 730         sec = elf_create_section(file->elf, ".retpoline_sites", 0,
 731                                  sizeof(int), idx);
 732         if (!sec) {
 733                 WARN("elf_create_section: .retpoline_sites");
 734                 return -1;
 735         }
 736
 737         idx = 0;
 738         list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
 739
 740                 int *site = (int *)sec->data->d_buf + idx;
 741                 *site = 0;
 742
 743                 if (elf_add_reloc_to_insn(file->elf, sec,
 744                                           idx * sizeof(int),
 745                                           R_X86_64_PC32,
 746                                           insn->sec, insn->offset)) {
 747                         WARN("elf_add_reloc_to_insn: .retpoline_sites");
 748                         return -1;
 749                 }
 750
 751                 idx++;
 752         }
 753
 754         return 0;
 755 }
 756
 757 static int create_return_sites_sections(struct objtool_file *file)
 758 {
 759         struct instruction *insn;
 760         struct section *sec;
 761         int idx;
 762
 763         sec = find_section_by_name(file->elf, ".return_sites");
 764         if (sec) {
 765                 WARN("file already has .return_sites, skipping");
 766                 return 0;
 767         }
 768
 769         idx = 0;
 770         list_for_each_entry(insn, &file->return_thunk_list, call_node)
 771                 idx++;
 772
 773         if (!idx)
 774                 return 0;
 775
 776         sec = elf_create_section(file->elf, ".return_sites", 0,
 777                                  sizeof(int), idx);
 778         if (!sec) {
 779                 WARN("elf_create_section: .return_sites");
 780                 return -1;
 781         }
 782
 783         idx = 0;
 784         list_for_each_entry(insn, &file->return_thunk_list, call_node) {
 785
 786                 int *site = (int *)sec->data->d_buf + idx;
 787                 *site = 0;
 788
 789                 if (elf_add_reloc_to_insn(file->elf, sec,
 790                                           idx * sizeof(int),
 791                                           R_X86_64_PC32,
 792                                           insn->sec, insn->offset)) {
 793                         WARN("elf_add_reloc_to_insn: .return_sites");
 794                         return -1;
 795                 }
 796
 797                 idx++;
 798         }
 799
 800         return 0;
 801 }
 802
 803 static int create_ibt_endbr_seal_sections(struct objtool_file *file)
 804 {
 805         struct instruction *insn;
 806         struct section *sec;
 807         int idx;
 808
 809         sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
 810         if (sec) {
 811                 WARN("file already has .ibt_endbr_seal, skipping");
 812                 return 0;
 813         }
 814
 815         idx = 0;
 816         list_for_each_entry(insn, &file->endbr_list, call_node)
 817                 idx++;
 818
 819         if (opts.stats) {
 820                 printf("ibt: ENDBR at function start: %d\n", file->nr_endbr);
 821                 printf("ibt: ENDBR inside functions:  %d\n", file->nr_endbr_int);
 822                 printf("ibt: superfluous ENDBR:       %d\n", idx);
 823         }
 824
 825         if (!idx)
 826                 return 0;
 827
 828         sec = elf_create_section(file->elf, ".ibt_endbr_seal", 0,
 829                                  sizeof(int), idx);
 830         if (!sec) {
 831                 WARN("elf_create_section: .ibt_endbr_seal");
 832                 return -1;
 833         }
 834
 835         idx = 0;
 836         list_for_each_entry(insn, &file->endbr_list, call_node) {
 837
 838                 int *site = (int *)sec->data->d_buf + idx;
 839                 *site = 0;
 840
 841                 if (elf_add_reloc_to_insn(file->elf, sec,
 842                                           idx * sizeof(int),
 843                                           R_X86_64_PC32,
 844                                           insn->sec, insn->offset)) {
 845                         WARN("elf_add_reloc_to_insn: .ibt_endbr_seal");
 846                         return -1;
 847                 }
 848
 849                 idx++;
 850         }
 851
 852         return 0;
 853 }
 854
 855 static int create_mcount_loc_sections(struct objtool_file *file)
 856 {
 857         struct section *sec;
 858         unsigned long *loc;
 859         struct instruction *insn;
 860         int idx;
 861
 862         sec = find_section_by_name(file->elf, "__mcount_loc");
 863         if (sec) {
 864                 INIT_LIST_HEAD(&file->mcount_loc_list);
 865                 WARN("file already has __mcount_loc section, skipping");
 866                 return 0;
 867         }
 868
 869         if (list_empty(&file->mcount_loc_list))
 870                 return 0;
 871
 872         idx = 0;
 873         list_for_each_entry(insn, &file->mcount_loc_list, call_node)
 874                 idx++;
 875
 876         sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx);
 877         if (!sec)
 878                 return -1;
 879
 880         idx = 0;
 881         list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
 882
 883                 loc = (unsigned long *)sec->data->d_buf + idx;
 884                 memset(loc, 0, sizeof(unsigned long));
 885
 886                 if (elf_add_reloc_to_insn(file->elf, sec,
 887                                           idx * sizeof(unsigned long),
 888                                           R_X86_64_64,
 889                                           insn->sec, insn->offset))
 890                         return -1;
 891
 892                 idx++;
 893         }
 894
 895         return 0;
 896 }
 897
 898 /*
 899  * Warnings shouldn't be reported for ignored functions.
 900  */
 901 static void add_ignores(struct objtool_file *file)
 902 {
 903         struct instruction *insn;
 904         struct section *sec;
 905         struct symbol *func;
 906         struct reloc *reloc;
 907
 908         sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
 909         if (!sec)
 910                 return;
 911
 912         list_for_each_entry(reloc, &sec->reloc_list, list) {
 913                 switch (reloc->sym->type) {
 914                 case STT_FUNC:
 915                         func = reloc->sym;
 916                         break;
 917
 918                 case STT_SECTION:
 919                         func = find_func_by_offset(reloc->sym->sec, reloc->addend);
 920                         if (!func)
 921                                 continue;
 922                         break;
 923
 924                 default:
 925                         WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type);
 926                         continue;
 927                 }
 928
 929                 func_for_each_insn(file, func, insn)
 930                         insn->ignore = true;
 931         }
 932 }
 933
 934 /*
 935  * This is a whitelist of functions that is allowed to be called with AC set.
 936  * The list is meant to be minimal and only contains compiler instrumentation
 937  * ABI and a few functions used to implement *_{to,from}_user() functions.
 938  *
 939  * These functions must not directly change AC, but may PUSHF/POPF.
 940  */
 941 static const char *uaccess_safe_builtin[] = {
 942         /* KASAN */
 943         "kasan_report",
 944         "kasan_check_range",
 945         /* KASAN out-of-line */
 946         "__asan_loadN_noabort",
 947         "__asan_load1_noabort",
 948         "__asan_load2_noabort",
 949         "__asan_load4_noabort",
 950         "__asan_load8_noabort",
 951         "__asan_load16_noabort",
 952         "__asan_storeN_noabort",
 953         "__asan_store1_noabort",
 954         "__asan_store2_noabort",
 955         "__asan_store4_noabort",
 956         "__asan_store8_noabort",
 957         "__asan_store16_noabort",
 958         "__kasan_check_read",
 959         "__kasan_check_write",
 960         /* KASAN in-line */
 961         "__asan_report_load_n_noabort",
 962         "__asan_report_load1_noabort",
 963         "__asan_report_load2_noabort",
 964         "__asan_report_load4_noabort",
 965         "__asan_report_load8_noabort",
 966         "__asan_report_load16_noabort",
 967         "__asan_report_store_n_noabort",
 968         "__asan_report_store1_noabort",
 969         "__asan_report_store2_noabort",
 970         "__asan_report_store4_noabort",
 971         "__asan_report_store8_noabort",
 972         "__asan_report_store16_noabort",
 973         /* KCSAN */
 974         "__kcsan_check_access",
 975         "__kcsan_mb",
 976         "__kcsan_wmb",
 977         "__kcsan_rmb",
 978         "__kcsan_release",
 979         "kcsan_found_watchpoint",
 980         "kcsan_setup_watchpoint",
 981         "kcsan_check_scoped_accesses",
 982         "kcsan_disable_current",
 983         "kcsan_enable_current_nowarn",
 984         /* KCSAN/TSAN */
 985         "__tsan_func_entry",
 986         "__tsan_func_exit",
 987         "__tsan_read_range",
 988         "__tsan_write_range",
 989         "__tsan_read1",
 990         "__tsan_read2",
 991         "__tsan_read4",
 992         "__tsan_read8",
 993         "__tsan_read16",
 994         "__tsan_write1",
 995         "__tsan_write2",
 996         "__tsan_write4",
 997         "__tsan_write8",
 998         "__tsan_write16",
 999         "__tsan_read_write1",
1000         "__tsan_read_write2",
1001         "__tsan_read_write4",
1002         "__tsan_read_write8",
1003         "__tsan_read_write16",
1004         "__tsan_volatile_read1",
1005         "__tsan_volatile_read2",
1006         "__tsan_volatile_read4",
1007         "__tsan_volatile_read8",
1008         "__tsan_volatile_read16",
1009         "__tsan_volatile_write1",
1010         "__tsan_volatile_write2",
1011         "__tsan_volatile_write4",
1012         "__tsan_volatile_write8",
1013         "__tsan_volatile_write16",
1014         "__tsan_atomic8_load",
1015         "__tsan_atomic16_load",
1016         "__tsan_atomic32_load",
1017         "__tsan_atomic64_load",
1018         "__tsan_atomic8_store",
1019         "__tsan_atomic16_store",
1020         "__tsan_atomic32_store",
1021         "__tsan_atomic64_store",
1022         "__tsan_atomic8_exchange",
1023         "__tsan_atomic16_exchange",
1024         "__tsan_atomic32_exchange",
1025         "__tsan_atomic64_exchange",
1026         "__tsan_atomic8_fetch_add",
1027         "__tsan_atomic16_fetch_add",
1028         "__tsan_atomic32_fetch_add",
1029         "__tsan_atomic64_fetch_add",
1030         "__tsan_atomic8_fetch_sub",
1031         "__tsan_atomic16_fetch_sub",
1032         "__tsan_atomic32_fetch_sub",
1033         "__tsan_atomic64_fetch_sub",
1034         "__tsan_atomic8_fetch_and",
1035         "__tsan_atomic16_fetch_and",
1036         "__tsan_atomic32_fetch_and",
1037         "__tsan_atomic64_fetch_and",
1038         "__tsan_atomic8_fetch_or",
1039         "__tsan_atomic16_fetch_or",
1040         "__tsan_atomic32_fetch_or",
1041         "__tsan_atomic64_fetch_or",
1042         "__tsan_atomic8_fetch_xor",
1043         "__tsan_atomic16_fetch_xor",
1044         "__tsan_atomic32_fetch_xor",
1045         "__tsan_atomic64_fetch_xor",
1046         "__tsan_atomic8_fetch_nand",
1047         "__tsan_atomic16_fetch_nand",
1048         "__tsan_atomic32_fetch_nand",
1049         "__tsan_atomic64_fetch_nand",
1050         "__tsan_atomic8_compare_exchange_strong",
1051         "__tsan_atomic16_compare_exchange_strong",
1052         "__tsan_atomic32_compare_exchange_strong",
1053         "__tsan_atomic64_compare_exchange_strong",
1054         "__tsan_atomic8_compare_exchange_weak",
1055         "__tsan_atomic16_compare_exchange_weak",
1056         "__tsan_atomic32_compare_exchange_weak",
1057         "__tsan_atomic64_compare_exchange_weak",
1058         "__tsan_atomic8_compare_exchange_val",
1059         "__tsan_atomic16_compare_exchange_val",
1060         "__tsan_atomic32_compare_exchange_val",
1061         "__tsan_atomic64_compare_exchange_val",
1062         "__tsan_atomic_thread_fence",
1063         "__tsan_atomic_signal_fence",
1064         "__tsan_unaligned_read16",
1065         "__tsan_unaligned_write16",
1066         /* KCOV */
1067         "write_comp_data",
1068         "check_kcov_mode",
1069         "__sanitizer_cov_trace_pc",
1070         "__sanitizer_cov_trace_const_cmp1",
1071         "__sanitizer_cov_trace_const_cmp2",
1072         "__sanitizer_cov_trace_const_cmp4",
1073         "__sanitizer_cov_trace_const_cmp8",
1074         "__sanitizer_cov_trace_cmp1",
1075         "__sanitizer_cov_trace_cmp2",
1076         "__sanitizer_cov_trace_cmp4",
1077         "__sanitizer_cov_trace_cmp8",
1078         "__sanitizer_cov_trace_switch",
1079         /* KMSAN */
1080         "kmsan_copy_to_user",
1081         "kmsan_report",
1082         "kmsan_unpoison_entry_regs",
1083         "kmsan_unpoison_memory",
1084         "__msan_chain_origin",
1085         "__msan_get_context_state",
1086         "__msan_instrument_asm_store",
1087         "__msan_metadata_ptr_for_load_1",
1088         "__msan_metadata_ptr_for_load_2",
1089         "__msan_metadata_ptr_for_load_4",
1090         "__msan_metadata_ptr_for_load_8",
1091         "__msan_metadata_ptr_for_load_n",
1092         "__msan_metadata_ptr_for_store_1",
1093         "__msan_metadata_ptr_for_store_2",
1094         "__msan_metadata_ptr_for_store_4",
1095         "__msan_metadata_ptr_for_store_8",
1096         "__msan_metadata_ptr_for_store_n",
1097         "__msan_poison_alloca",
1098         "__msan_warning",
1099         /* UBSAN */
1100         "ubsan_type_mismatch_common",
1101         "__ubsan_handle_type_mismatch",
1102         "__ubsan_handle_type_mismatch_v1",
1103         "__ubsan_handle_shift_out_of_bounds",
1104         /* misc */
1105         "csum_partial_copy_generic",
1106         "copy_mc_fragile",
1107         "copy_mc_fragile_handle_tail",
1108         "copy_mc_enhanced_fast_string",
1109         "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
1110         "clear_user_erms",
1111         "clear_user_rep_good",
1112         "clear_user_original",
1113         NULL
1114 };
1115
1116 static void add_uaccess_safe(struct objtool_file *file)
1117 {
1118         struct symbol *func;
1119         const char **name;
1120
1121         if (!opts.uaccess)
1122                 return;
1123
1124         for (name = uaccess_safe_builtin; *name; name++) {
1125                 func = find_symbol_by_name(file->elf, *name);
1126                 if (!func)
1127                         continue;
1128
1129                 func->uaccess_safe = true;
1130         }
1131 }
1132
1133 /*
1134  * FIXME: For now, just ignore any alternatives which add retpolines.  This is
1135  * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
1136  * But it at least allows objtool to understand the control flow *around* the
1137  * retpoline.
1138  */
1139 static int add_ignore_alternatives(struct objtool_file *file)
1140 {
1141         struct section *sec;
1142         struct reloc *reloc;
1143         struct instruction *insn;
1144
1145         sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
1146         if (!sec)
1147                 return 0;
1148
1149         list_for_each_entry(reloc, &sec->reloc_list, list) {
1150                 if (reloc->sym->type != STT_SECTION) {
1151                         WARN("unexpected relocation symbol type in %s", sec->name);
1152                         return -1;
1153                 }
1154
1155                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
1156                 if (!insn) {
1157                         WARN("bad .discard.ignore_alts entry");
1158                         return -1;
1159                 }
1160
1161                 insn->ignore_alts = true;
1162         }
1163
1164         return 0;
1165 }
1166
1167 /*
1168  * Symbols that replace INSN_CALL_DYNAMIC, every (tail) call to such a symbol
1169  * will be added to the .retpoline_sites section.
1170  */
1171 __weak bool arch_is_retpoline(struct symbol *sym)
1172 {
1173         return false;
1174 }
1175
1176 /*
1177  * Symbols that replace INSN_RETURN, every (tail) call to such a symbol
1178  * will be added to the .return_sites section.
1179  */
1180 __weak bool arch_is_rethunk(struct symbol *sym)
1181 {
1182         return false;
1183 }
1184
1185 /*
1186  * Symbols that are embedded inside other instructions, because sometimes crazy
1187  * code exists. These are mostly ignored for validation purposes.
1188  */
1189 __weak bool arch_is_embedded_insn(struct symbol *sym)
1190 {
1191         return false;
1192 }
1193
1194 #define NEGATIVE_RELOC  ((void *)-1L)
1195
1196 static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
1197 {
1198         if (insn->reloc == NEGATIVE_RELOC)
1199                 return NULL;
1200
1201         if (!insn->reloc) {
1202                 if (!file)
1203                         return NULL;
1204
1205                 insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
1206                                                        insn->offset, insn->len);
1207                 if (!insn->reloc) {
1208                         insn->reloc = NEGATIVE_RELOC;
1209                         return NULL;
1210                 }
1211         }
1212
1213         return insn->reloc;
1214 }
1215
1216 static void remove_insn_ops(struct instruction *insn)
1217 {
1218         struct stack_op *op, *tmp;
1219
1220         list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
1221                 list_del(&op->list);
1222                 free(op);
1223         }
1224 }
1225
1226 static void annotate_call_site(struct objtool_file *file,
1227                                struct instruction *insn, bool sibling)
1228 {
1229         struct reloc *reloc = insn_reloc(file, insn);
1230         struct symbol *sym = insn->call_dest;
1231
1232         if (!sym)
1233                 sym = reloc->sym;
1234
1235         /*
1236          * Alternative replacement code is just template code which is
1237          * sometimes copied to the original instruction. For now, don't
1238          * annotate it. (In the future we might consider annotating the
1239          * original instruction if/when it ever makes sense to do so.)
1240          */
1241         if (!strcmp(insn->sec->name, ".altinstr_replacement"))
1242                 return;
1243
1244         if (sym->static_call_tramp) {
1245                 list_add_tail(&insn->call_node, &file->static_call_list);
1246                 return;
1247         }
1248
1249         if (sym->retpoline_thunk) {
1250                 list_add_tail(&insn->call_node, &file->retpoline_call_list);
1251                 return;
1252         }
1253
1254         /*
1255          * Many compilers cannot disable KCOV or sanitizer calls with a function
1256          * attribute so they need a little help, NOP out any such calls from
1257          * noinstr text.
1258          */
1259         if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
1260                 if (reloc) {
1261                         reloc->type = R_NONE;
1262                         elf_write_reloc(file->elf, reloc);
1263                 }
1264
1265                 elf_write_insn(file->elf, insn->sec,
1266                                insn->offset, insn->len,
1267                                sibling ? arch_ret_insn(insn->len)
1268                                        : arch_nop_insn(insn->len));
1269
1270                 insn->type = sibling ? INSN_RETURN : INSN_NOP;
1271
1272                 if (sibling) {
1273                         /*
1274                          * We've replaced the tail-call JMP insn by two new
1275                          * insn: RET; INT3, except we only have a single struct
1276                          * insn here. Mark it retpoline_safe to avoid the SLS
1277                          * warning, instead of adding another insn.
1278                          */
1279                         insn->retpoline_safe = true;
1280                 }
1281
1282                 return;
1283         }
1284
1285         if (opts.mcount && sym->fentry) {
1286                 if (sibling)
1287                         WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset);
1288
1289                 if (reloc) {
1290                         reloc->type = R_NONE;
1291                         elf_write_reloc(file->elf, reloc);
1292                 }
1293
1294                 elf_write_insn(file->elf, insn->sec,
1295                                insn->offset, insn->len,
1296                                arch_nop_insn(insn->len));
1297
1298                 insn->type = INSN_NOP;
1299
1300                 list_add_tail(&insn->call_node, &file->mcount_loc_list);
1301                 return;
1302         }
1303
1304         if (!sibling && dead_end_function(file, sym))
1305                 insn->dead_end = true;
1306 }
1307
1308 static void add_call_dest(struct objtool_file *file, struct instruction *insn,
1309                           struct symbol *dest, bool sibling)
1310 {
1311         insn->call_dest = dest;
1312         if (!dest)
1313                 return;
1314
1315         /*
1316          * Whatever stack impact regular CALLs have, should be undone
1317          * by the RETURN of the called function.
1318          *
1319          * Annotated intra-function calls retain the stack_ops but
1320          * are converted to JUMP, see read_intra_function_calls().
1321          */
1322         remove_insn_ops(insn);
1323
1324         annotate_call_site(file, insn, sibling);
1325 }
1326
1327 static void add_retpoline_call(struct objtool_file *file, struct instruction *insn)
1328 {
1329         /*
1330          * Retpoline calls/jumps are really dynamic calls/jumps in disguise,
1331          * so convert them accordingly.
1332          */
1333         switch (insn->type) {
1334         case INSN_CALL:
1335                 insn->type = INSN_CALL_DYNAMIC;
1336                 break;
1337         case INSN_JUMP_UNCONDITIONAL:
1338                 insn->type = INSN_JUMP_DYNAMIC;
1339                 break;
1340         case INSN_JUMP_CONDITIONAL:
1341                 insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
1342                 break;
1343         default:
1344                 return;
1345         }
1346
1347         insn->retpoline_safe = true;
1348
1349         /*
1350          * Whatever stack impact regular CALLs have, should be undone
1351          * by the RETURN of the called function.
1352          *
1353          * Annotated intra-function calls retain the stack_ops but
1354          * are converted to JUMP, see read_intra_function_calls().
1355          */
1356         remove_insn_ops(insn);
1357
1358         annotate_call_site(file, insn, false);
1359 }
1360
1361 static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
1362 {
1363         /*
1364          * Return thunk tail calls are really just returns in disguise,
1365          * so convert them accordingly.
1366          */
1367         insn->type = INSN_RETURN;
1368         insn->retpoline_safe = true;
1369
1370         if (add)
1371                 list_add_tail(&insn->call_node, &file->return_thunk_list);
1372 }
1373
1374 static bool same_function(struct instruction *insn1, struct instruction *insn2)
1375 {
1376         return insn1->func->pfunc == insn2->func->pfunc;
1377 }
1378
1379 static bool is_first_func_insn(struct objtool_file *file, struct instruction *insn)
1380 {
1381         if (insn->offset == insn->func->offset)
1382                 return true;
1383
1384         if (opts.ibt) {
1385                 struct instruction *prev = prev_insn_same_sym(file, insn);
1386
1387                 if (prev && prev->type == INSN_ENDBR &&
1388                     insn->offset == insn->func->offset + prev->len)
1389                         return true;
1390         }
1391
1392         return false;
1393 }
1394
1395 /*
1396  * Find the destination instructions for all jumps.
1397  */
1398 static int add_jump_destinations(struct objtool_file *file)
1399 {
1400         struct instruction *insn, *jump_dest;
1401         struct reloc *reloc;
1402         struct section *dest_sec;
1403         unsigned long dest_off;
1404
1405         for_each_insn(file, insn) {
1406                 if (insn->jump_dest) {
1407                         /*
1408                          * handle_group_alt() may have previously set
1409                          * 'jump_dest' for some alternatives.
1410                          */
1411                         continue;
1412                 }
1413                 if (!is_static_jump(insn))
1414                         continue;
1415
1416                 reloc = insn_reloc(file, insn);
1417                 if (!reloc) {
1418                         dest_sec = insn->sec;
1419                         dest_off = arch_jump_destination(insn);
1420                 } else if (reloc->sym->type == STT_SECTION) {
1421                         dest_sec = reloc->sym->sec;
1422                         dest_off = arch_dest_reloc_offset(reloc->addend);
1423                 } else if (reloc->sym->retpoline_thunk) {
1424                         add_retpoline_call(file, insn);
1425                         continue;
1426                 } else if (reloc->sym->return_thunk) {
1427                         add_return_call(file, insn, true);
1428                         continue;
1429                 } else if (insn->func) {
1430                         /*
1431                          * External sibling call or internal sibling call with
1432                          * STT_FUNC reloc.
1433                          */
1434                         add_call_dest(file, insn, reloc->sym, true);
1435                         continue;
1436                 } else if (reloc->sym->sec->idx) {
1437                         dest_sec = reloc->sym->sec;
1438                         dest_off = reloc->sym->sym.st_value +
1439                                    arch_dest_reloc_offset(reloc->addend);
1440                 } else {
1441                         /* non-func asm code jumping to another file */
1442                         continue;
1443                 }
1444
1445                 jump_dest = find_insn(file, dest_sec, dest_off);
1446                 if (!jump_dest) {
1447                         struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
1448
1449                         /*
1450                          * This is a special case for retbleed_untrain_ret().
1451                          * It jumps to __x86_return_thunk(), but objtool
1452                          * can't find the thunk's starting RET
1453                          * instruction, because the RET is also in the
1454                          * middle of another instruction.  Objtool only
1455                          * knows about the outer instruction.
1456                          */
1457                         if (sym && sym->embedded_insn) {
1458                                 add_return_call(file, insn, false);
1459                                 continue;
1460                         }
1461
1462                         WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
1463                                   insn->sec, insn->offset, dest_sec->name,
1464                                   dest_off);
1465                         return -1;
1466                 }
1467
1468                 /*
1469                  * Cross-function jump.
1470                  */
1471                 if (insn->func && jump_dest->func &&
1472                     insn->func != jump_dest->func) {
1473
1474                         /*
1475                          * For GCC 8+, create parent/child links for any cold
1476                          * subfunctions.  This is _mostly_ redundant with a
1477                          * similar initialization in read_symbols().
1478                          *
1479                          * If a function has aliases, we want the *first* such
1480                          * function in the symbol table to be the subfunction's
1481                          * parent.  In that case we overwrite the
1482                          * initialization done in read_symbols().
1483                          *
1484                          * However this code can't completely replace the
1485                          * read_symbols() code because this doesn't detect the
1486                          * case where the parent function's only reference to a
1487                          * subfunction is through a jump table.
1488                          */
1489                         if (!strstr(insn->func->name, ".cold") &&
1490                             strstr(jump_dest->func->name, ".cold")) {
1491                                 insn->func->cfunc = jump_dest->func;
1492                                 jump_dest->func->pfunc = insn->func;
1493
1494                         } else if (!same_function(insn, jump_dest) &&
1495                                    is_first_func_insn(file, jump_dest)) {
1496                                 /*
1497                                  * Internal sibling call without reloc or with
1498                                  * STT_SECTION reloc.
1499                                  */
1500                                 add_call_dest(file, insn, jump_dest->func, true);
1501                                 continue;
1502                         }
1503                 }
1504
1505                 insn->jump_dest = jump_dest;
1506         }
1507
1508         return 0;
1509 }
1510
1511 static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
1512 {
1513         struct symbol *call_dest;
1514
1515         call_dest = find_func_by_offset(sec, offset);
1516         if (!call_dest)
1517                 call_dest = find_symbol_by_offset(sec, offset);
1518
1519         return call_dest;
1520 }
1521
1522 /*
1523  * Find the destination instructions for all calls.
1524  */
1525 static int add_call_destinations(struct objtool_file *file)
1526 {
1527         struct instruction *insn;
1528         unsigned long dest_off;
1529         struct symbol *dest;
1530         struct reloc *reloc;
1531
1532         for_each_insn(file, insn) {
1533                 if (insn->type != INSN_CALL)
1534                         continue;
1535
1536                 reloc = insn_reloc(file, insn);
1537                 if (!reloc) {
1538                         dest_off = arch_jump_destination(insn);
1539                         dest = find_call_destination(insn->sec, dest_off);
1540
1541                         add_call_dest(file, insn, dest, false);
1542
1543                         if (insn->ignore)
1544                                 continue;
1545
1546                         if (!insn->call_dest) {
1547                                 WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);
1548                                 return -1;
1549                         }
1550
1551                         if (insn->func && insn->call_dest->type != STT_FUNC) {
1552                                 WARN_FUNC("unsupported call to non-function",
1553                                           insn->sec, insn->offset);
1554                                 return -1;
1555                         }
1556
1557                 } else if (reloc->sym->type == STT_SECTION) {
1558                         dest_off = arch_dest_reloc_offset(reloc->addend);
1559                         dest = find_call_destination(reloc->sym->sec, dest_off);
1560                         if (!dest) {
1561                                 WARN_FUNC("can't find call dest symbol at %s+0x%lx",
1562                                           insn->sec, insn->offset,
1563                                           reloc->sym->sec->name,
1564                                           dest_off);
1565                                 return -1;
1566                         }
1567
1568                         add_call_dest(file, insn, dest, false);
1569
1570                 } else if (reloc->sym->retpoline_thunk) {
1571                         add_retpoline_call(file, insn);
1572
1573                 } else
1574                         add_call_dest(file, insn, reloc->sym, false);
1575         }
1576
1577         return 0;
1578 }
1579
1580 /*
1581  * The .alternatives section requires some extra special care over and above
1582  * other special sections because alternatives are patched in place.
1583  */
1584 static int handle_group_alt(struct objtool_file *file,
1585                             struct special_alt *special_alt,
1586                             struct instruction *orig_insn,
1587                             struct instruction **new_insn)
1588 {
1589         struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL;
1590         struct alt_group *orig_alt_group, *new_alt_group;
1591         unsigned long dest_off;
1592
1593
1594         orig_alt_group = malloc(sizeof(*orig_alt_group));
1595         if (!orig_alt_group) {
1596                 WARN("malloc failed");
1597                 return -1;
1598         }
1599         orig_alt_group->cfi = calloc(special_alt->orig_len,
1600                                      sizeof(struct cfi_state *));
1601         if (!orig_alt_group->cfi) {
1602                 WARN("calloc failed");
1603                 return -1;
1604         }
1605
1606         last_orig_insn = NULL;
1607         insn = orig_insn;
1608         sec_for_each_insn_from(file, insn) {
1609                 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
1610                         break;
1611
1612                 insn->alt_group = orig_alt_group;
1613                 last_orig_insn = insn;
1614         }
1615         orig_alt_group->orig_group = NULL;
1616         orig_alt_group->first_insn = orig_insn;
1617         orig_alt_group->last_insn = last_orig_insn;
1618
1619
1620         new_alt_group = malloc(sizeof(*new_alt_group));
1621         if (!new_alt_group) {
1622                 WARN("malloc failed");
1623                 return -1;
1624         }
1625
1626         if (special_alt->new_len < special_alt->orig_len) {
1627                 /*
1628                  * Insert a fake nop at the end to make the replacement
1629                  * alt_group the same size as the original.  This is needed to
1630                  * allow propagate_alt_cfi() to do its magic.  When the last
1631                  * instruction affects the stack, the instruction after it (the
1632                  * nop) will propagate the new state to the shared CFI array.
1633                  */
1634                 nop = malloc(sizeof(*nop));
1635                 if (!nop) {
1636                         WARN("malloc failed");
1637                         return -1;
1638                 }
1639                 memset(nop, 0, sizeof(*nop));
1640                 INIT_LIST_HEAD(&nop->alts);
1641                 INIT_LIST_HEAD(&nop->stack_ops);
1642
1643                 nop->sec = special_alt->new_sec;
1644                 nop->offset = special_alt->new_off + special_alt->new_len;
1645                 nop->len = special_alt->orig_len - special_alt->new_len;
1646                 nop->type = INSN_NOP;
1647                 nop->func = orig_insn->func;
1648                 nop->alt_group = new_alt_group;
1649                 nop->ignore = orig_insn->ignore_alts;
1650         }
1651
1652         if (!special_alt->new_len) {
1653                 *new_insn = nop;
1654                 goto end;
1655         }
1656
1657         insn = *new_insn;
1658         sec_for_each_insn_from(file, insn) {
1659                 struct reloc *alt_reloc;
1660
1661                 if (insn->offset >= special_alt->new_off + special_alt->new_len)
1662                         break;
1663
1664                 last_new_insn = insn;
1665
1666                 insn->ignore = orig_insn->ignore_alts;
1667                 insn->func = orig_insn->func;
1668                 insn->alt_group = new_alt_group;
1669
1670                 /*
1671                  * Since alternative replacement code is copy/pasted by the
1672                  * kernel after applying relocations, generally such code can't
1673                  * have relative-address relocation references to outside the
1674                  * .altinstr_replacement section, unless the arch's
1675                  * alternatives code can adjust the relative offsets
1676                  * accordingly.
1677                  */
1678                 alt_reloc = insn_reloc(file, insn);
1679                 if (alt_reloc &&
1680                     !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
1681
1682                         WARN_FUNC("unsupported relocation in alternatives section",
1683                                   insn->sec, insn->offset);
1684                         return -1;
1685                 }
1686
1687                 if (!is_static_jump(insn))
1688                         continue;
1689
1690                 if (!insn->immediate)
1691                         continue;
1692
1693                 dest_off = arch_jump_destination(insn);
1694                 if (dest_off == special_alt->new_off + special_alt->new_len) {
1695                         insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
1696                         if (!insn->jump_dest) {
1697                                 WARN_FUNC("can't find alternative jump destination",
1698                                           insn->sec, insn->offset);
1699                                 return -1;
1700                         }
1701                 }
1702         }
1703
1704         if (!last_new_insn) {
1705                 WARN_FUNC("can't find last new alternative instruction",
1706                           special_alt->new_sec, special_alt->new_off);
1707                 return -1;
1708         }
1709
1710         if (nop)
1711                 list_add(&nop->list, &last_new_insn->list);
1712 end:
1713         new_alt_group->orig_group = orig_alt_group;
1714         new_alt_group->first_insn = *new_insn;
1715         new_alt_group->last_insn = nop ? : last_new_insn;
1716         new_alt_group->cfi = orig_alt_group->cfi;
1717         return 0;
1718 }
1719
1720 /*
1721  * A jump table entry can either convert a nop to a jump or a jump to a nop.
1722  * If the original instruction is a jump, make the alt entry an effective nop
1723  * by just skipping the original instruction.
1724  */
1725 static int handle_jump_alt(struct objtool_file *file,
1726                            struct special_alt *special_alt,
1727                            struct instruction *orig_insn,
1728                            struct instruction **new_insn)
1729 {
1730         if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
1731             orig_insn->type != INSN_NOP) {
1732
1733                 WARN_FUNC("unsupported instruction at jump label",
1734                           orig_insn->sec, orig_insn->offset);
1735                 return -1;
1736         }
1737
1738         if (opts.hack_jump_label && special_alt->key_addend & 2) {
1739                 struct reloc *reloc = insn_reloc(file, orig_insn);
1740
1741                 if (reloc) {
1742                         reloc->type = R_NONE;
1743                         elf_write_reloc(file->elf, reloc);
1744                 }
1745                 elf_write_insn(file->elf, orig_insn->sec,
1746                                orig_insn->offset, orig_insn->len,
1747                                arch_nop_insn(orig_insn->len));
1748                 orig_insn->type = INSN_NOP;
1749         }
1750
1751         if (orig_insn->type == INSN_NOP) {
1752                 if (orig_insn->len == 2)
1753                         file->jl_nop_short++;
1754                 else
1755                         file->jl_nop_long++;
1756
1757                 return 0;
1758         }
1759
1760         if (orig_insn->len == 2)
1761                 file->jl_short++;
1762         else
1763                 file->jl_long++;
1764
1765         *new_insn = list_next_entry(orig_insn, list);
1766         return 0;
1767 }
1768
1769 /*
1770  * Read all the special sections which have alternate instructions which can be
1771  * patched in or redirected to at runtime.  Each instruction having alternate
1772  * instruction(s) has them added to its insn->alts list, which will be
1773  * traversed in validate_branch().
1774  */
1775 static int add_special_section_alts(struct objtool_file *file)
1776 {
1777         struct list_head special_alts;
1778         struct instruction *orig_insn, *new_insn;
1779         struct special_alt *special_alt, *tmp;
1780         struct alternative *alt;
1781         int ret;
1782
1783         ret = special_get_alts(file->elf, &special_alts);
1784         if (ret)
1785                 return ret;
1786
1787         list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
1788
1789                 orig_insn = find_insn(file, special_alt->orig_sec,
1790                                       special_alt->orig_off);
1791                 if (!orig_insn) {
1792                         WARN_FUNC("special: can't find orig instruction",
1793                                   special_alt->orig_sec, special_alt->orig_off);
1794                         ret = -1;
1795                         goto out;
1796                 }
1797
1798                 new_insn = NULL;
1799                 if (!special_alt->group || special_alt->new_len) {
1800                         new_insn = find_insn(file, special_alt->new_sec,
1801                                              special_alt->new_off);
1802                         if (!new_insn) {
1803                                 WARN_FUNC("special: can't find new instruction",
1804                                           special_alt->new_sec,
1805                                           special_alt->new_off);
1806                                 ret = -1;
1807                                 goto out;
1808                         }
1809                 }
1810
1811                 if (special_alt->group) {
1812                         if (!special_alt->orig_len) {
1813                                 WARN_FUNC("empty alternative entry",
1814                                           orig_insn->sec, orig_insn->offset);
1815                                 continue;
1816                         }
1817
1818                         ret = handle_group_alt(file, special_alt, orig_insn,
1819                                                &new_insn);
1820                         if (ret)
1821                                 goto out;
1822                 } else if (special_alt->jump_or_nop) {
1823                         ret = handle_jump_alt(file, special_alt, orig_insn,
1824                                               &new_insn);
1825                         if (ret)
1826                                 goto out;
1827                 }
1828
1829                 alt = malloc(sizeof(*alt));
1830                 if (!alt) {
1831                         WARN("malloc failed");
1832                         ret = -1;
1833                         goto out;
1834                 }
1835
1836                 alt->insn = new_insn;
1837                 alt->skip_orig = special_alt->skip_orig;
1838                 orig_insn->ignore_alts |= special_alt->skip_alt;
1839                 list_add_tail(&alt->list, &orig_insn->alts);
1840
1841                 list_del(&special_alt->list);
1842                 free(special_alt);
1843         }
1844
1845         if (opts.stats) {
1846                 printf("jl\\\tNOP\tJMP\n");
1847                 printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
1848                 printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
1849         }
1850
1851 out:
1852         return ret;
1853 }
1854
1855 static int add_jump_table(struct objtool_file *file, struct instruction *insn,
1856                             struct reloc *table)
1857 {
1858         struct reloc *reloc = table;
1859         struct instruction *dest_insn;
1860         struct alternative *alt;
1861         struct symbol *pfunc = insn->func->pfunc;
1862         unsigned int prev_offset = 0;
1863
1864         /*
1865          * Each @reloc is a switch table relocation which points to the target
1866          * instruction.
1867          */
1868         list_for_each_entry_from(reloc, &table->sec->reloc_list, list) {
1869
1870                 /* Check for the end of the table: */
1871                 if (reloc != table && reloc->jump_table_start)
1872                         break;
1873
1874                 /* Make sure the table entries are consecutive: */
1875                 if (prev_offset && reloc->offset != prev_offset + 8)
1876                         break;
1877
1878                 /* Detect function pointers from contiguous objects: */
1879                 if (reloc->sym->sec == pfunc->sec &&
1880                     reloc->addend == pfunc->offset)
1881                         break;
1882
1883                 dest_insn = find_insn(file, reloc->sym->sec, reloc->addend);
1884                 if (!dest_insn)
1885                         break;
1886
1887                 /* Make sure the destination is in the same function: */
1888                 if (!dest_insn->func || dest_insn->func->pfunc != pfunc)
1889                         break;
1890
1891                 alt = malloc(sizeof(*alt));
1892                 if (!alt) {
1893                         WARN("malloc failed");
1894                         return -1;
1895                 }
1896
1897                 alt->insn = dest_insn;
1898                 list_add_tail(&alt->list, &insn->alts);
1899                 prev_offset = reloc->offset;
1900         }
1901
1902         if (!prev_offset) {
1903                 WARN_FUNC("can't find switch jump table",
1904                           insn->sec, insn->offset);
1905                 return -1;
1906         }
1907
1908         return 0;
1909 }
1910
1911 /*
1912  * find_jump_table() - Given a dynamic jump, find the switch jump table
1913  * associated with it.
1914  */
1915 static struct reloc *find_jump_table(struct objtool_file *file,
1916                                       struct symbol *func,
1917                                       struct instruction *insn)
1918 {
1919         struct reloc *table_reloc;
1920         struct instruction *dest_insn, *orig_insn = insn;
1921
1922         /*
1923          * Backward search using the @first_jump_src links, these help avoid
1924          * much of the 'in between' code. Which avoids us getting confused by
1925          * it.
1926          */
1927         for (;
1928              insn && insn->func && insn->func->pfunc == func;
1929              insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
1930
1931                 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
1932                         break;
1933
1934                 /* allow small jumps within the range */
1935                 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
1936                     insn->jump_dest &&
1937                     (insn->jump_dest->offset <= insn->offset ||
1938                      insn->jump_dest->offset > orig_insn->offset))
1939                     break;
1940
1941                 table_reloc = arch_find_switch_table(file, insn);
1942                 if (!table_reloc)
1943                         continue;
1944                 dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
1945                 if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
1946                         continue;
1947
1948                 return table_reloc;
1949         }
1950
1951         return NULL;
1952 }
1953
1954 /*
1955  * First pass: Mark the head of each jump table so that in the next pass,
1956  * we know when a given jump table ends and the next one starts.
1957  */
1958 static void mark_func_jump_tables(struct objtool_file *file,
1959                                     struct symbol *func)
1960 {
1961         struct instruction *insn, *last = NULL;
1962         struct reloc *reloc;
1963
1964         func_for_each_insn(file, func, insn) {
1965                 if (!last)
1966                         last = insn;
1967
1968                 /*
1969                  * Store back-pointers for unconditional forward jumps such
1970                  * that find_jump_table() can back-track using those and
1971                  * avoid some potentially confusing code.
1972                  */
1973                 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
1974                     insn->offset > last->offset &&
1975                     insn->jump_dest->offset > insn->offset &&
1976                     !insn->jump_dest->first_jump_src) {
1977
1978                         insn->jump_dest->first_jump_src = insn;
1979                         last = insn->jump_dest;
1980                 }
1981
1982                 if (insn->type != INSN_JUMP_DYNAMIC)
1983                         continue;
1984
1985                 reloc = find_jump_table(file, func, insn);
1986                 if (reloc) {
1987                         reloc->jump_table_start = true;
1988                         insn->jump_table = reloc;
1989                 }
1990         }
1991 }
1992
1993 static int add_func_jump_tables(struct objtool_file *file,
1994                                   struct symbol *func)
1995 {
1996         struct instruction *insn;
1997         int ret;
1998
1999         func_for_each_insn(file, func, insn) {
2000                 if (!insn->jump_table)
2001                         continue;
2002
2003                 ret = add_jump_table(file, insn, insn->jump_table);
2004                 if (ret)
2005                         return ret;
2006         }
2007
2008         return 0;
2009 }
2010
2011 /*
2012  * For some switch statements, gcc generates a jump table in the .rodata
2013  * section which contains a list of addresses within the function to jump to.
2014  * This finds these jump tables and adds them to the insn->alts lists.
2015  */
2016 static int add_jump_table_alts(struct objtool_file *file)
2017 {
2018         struct section *sec;
2019         struct symbol *func;
2020         int ret;
2021
2022         if (!file->rodata)
2023                 return 0;
2024
2025         for_each_sec(file, sec) {
2026                 list_for_each_entry(func, &sec->symbol_list, list) {
2027                         if (func->type != STT_FUNC)
2028                                 continue;
2029
2030                         mark_func_jump_tables(file, func);
2031                         ret = add_func_jump_tables(file, func);
2032                         if (ret)
2033                                 return ret;
2034                 }
2035         }
2036
2037         return 0;
2038 }
2039
2040 static void set_func_state(struct cfi_state *state)
2041 {
2042         state->cfa = initial_func_cfi.cfa;
2043         memcpy(&state->regs, &initial_func_cfi.regs,
2044                CFI_NUM_REGS * sizeof(struct cfi_reg));
2045         state->stack_size = initial_func_cfi.cfa.offset;
2046 }
2047
2048 static int read_unwind_hints(struct objtool_file *file)
2049 {
2050         struct cfi_state cfi = init_cfi;
2051         struct section *sec, *relocsec;
2052         struct unwind_hint *hint;
2053         struct instruction *insn;
2054         struct reloc *reloc;
2055         int i;
2056
2057         sec = find_section_by_name(file->elf, ".discard.unwind_hints");
2058         if (!sec)
2059                 return 0;
2060
2061         relocsec = sec->reloc;
2062         if (!relocsec) {
2063                 WARN("missing .rela.discard.unwind_hints section");
2064                 return -1;
2065         }
2066
2067         if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
2068                 WARN("struct unwind_hint size mismatch");
2069                 return -1;
2070         }
2071
2072         file->hints = true;
2073
2074         for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
2075                 hint = (struct unwind_hint *)sec->data->d_buf + i;
2076
2077                 reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
2078                 if (!reloc) {
2079                         WARN("can't find reloc for unwind_hints[%d]", i);
2080                         return -1;
2081                 }
2082
2083                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2084                 if (!insn) {
2085                         WARN("can't find insn for unwind_hints[%d]", i);
2086                         return -1;
2087                 }
2088
2089                 insn->hint = true;
2090
2091                 if (hint->type == UNWIND_HINT_TYPE_SAVE) {
2092                         insn->hint = false;
2093                         insn->save = true;
2094                         continue;
2095                 }
2096
2097                 if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
2098                         insn->restore = true;
2099                         continue;
2100                 }
2101
2102                 if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
2103                         struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
2104
2105                         if (sym && sym->bind == STB_GLOBAL) {
2106                                 if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
2107                                         WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR",
2108                                                   insn->sec, insn->offset);
2109                                 }
2110
2111                                 insn->entry = 1;
2112                         }
2113                 }
2114
2115                 if (hint->type == UNWIND_HINT_TYPE_ENTRY) {
2116                         hint->type = UNWIND_HINT_TYPE_CALL;
2117                         insn->entry = 1;
2118                 }
2119
2120                 if (hint->type == UNWIND_HINT_TYPE_FUNC) {
2121                         insn->cfi = &func_cfi;
2122                         continue;
2123                 }
2124
2125                 if (insn->cfi)
2126                         cfi = *(insn->cfi);
2127
2128                 if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
2129                         WARN_FUNC("unsupported unwind_hint sp base reg %d",
2130                                   insn->sec, insn->offset, hint->sp_reg);
2131                         return -1;
2132                 }
2133
2134                 cfi.cfa.offset = bswap_if_needed(hint->sp_offset);
2135                 cfi.type = hint->type;
2136                 cfi.end = hint->end;
2137
2138                 insn->cfi = cfi_hash_find_or_add(&cfi);
2139         }
2140
2141         return 0;
2142 }
2143
2144 static int read_noendbr_hints(struct objtool_file *file)
2145 {
2146         struct section *sec;
2147         struct instruction *insn;
2148         struct reloc *reloc;
2149
2150         sec = find_section_by_name(file->elf, ".rela.discard.noendbr");
2151         if (!sec)
2152                 return 0;
2153
2154         list_for_each_entry(reloc, &sec->reloc_list, list) {
2155                 insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend);
2156                 if (!insn) {
2157                         WARN("bad .discard.noendbr entry");
2158                         return -1;
2159                 }
2160
2161                 insn->noendbr = 1;
2162         }
2163
2164         return 0;
2165 }
2166
2167 static int read_retpoline_hints(struct objtool_file *file)
2168 {
2169         struct section *sec;
2170         struct instruction *insn;
2171         struct reloc *reloc;
2172
2173         sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
2174         if (!sec)
2175                 return 0;
2176
2177         list_for_each_entry(reloc, &sec->reloc_list, list) {
2178                 if (reloc->sym->type != STT_SECTION) {
2179                         WARN("unexpected relocation symbol type in %s", sec->name);
2180                         return -1;
2181                 }
2182
2183                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2184                 if (!insn) {
2185                         WARN("bad .discard.retpoline_safe entry");
2186                         return -1;
2187                 }
2188
2189                 if (insn->type != INSN_JUMP_DYNAMIC &&
2190                     insn->type != INSN_CALL_DYNAMIC &&
2191                     insn->type != INSN_RETURN &&
2192                     insn->type != INSN_NOP) {
2193                         WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret/nop",
2194                                   insn->sec, insn->offset);
2195                         return -1;
2196                 }
2197
2198                 insn->retpoline_safe = true;
2199         }
2200
2201         return 0;
2202 }
2203
2204 static int read_instr_hints(struct objtool_file *file)
2205 {
2206         struct section *sec;
2207         struct instruction *insn;
2208         struct reloc *reloc;
2209
2210         sec = find_section_by_name(file->elf, ".rela.discard.instr_end");
2211         if (!sec)
2212                 return 0;
2213
2214         list_for_each_entry(reloc, &sec->reloc_list, list) {
2215                 if (reloc->sym->type != STT_SECTION) {
2216                         WARN("unexpected relocation symbol type in %s", sec->name);
2217                         return -1;
2218                 }
2219
2220                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2221                 if (!insn) {
2222                         WARN("bad .discard.instr_end entry");
2223                         return -1;
2224                 }
2225
2226                 insn->instr--;
2227         }
2228
2229         sec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
2230         if (!sec)
2231                 return 0;
2232
2233         list_for_each_entry(reloc, &sec->reloc_list, list) {
2234                 if (reloc->sym->type != STT_SECTION) {
2235                         WARN("unexpected relocation symbol type in %s", sec->name);
2236                         return -1;
2237                 }
2238
2239                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2240                 if (!insn) {
2241                         WARN("bad .discard.instr_begin entry");
2242                         return -1;
2243                 }
2244
2245                 insn->instr++;
2246         }
2247
2248         return 0;
2249 }
2250
2251 static int read_intra_function_calls(struct objtool_file *file)
2252 {
2253         struct instruction *insn;
2254         struct section *sec;
2255         struct reloc *reloc;
2256
2257         sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
2258         if (!sec)
2259                 return 0;
2260
2261         list_for_each_entry(reloc, &sec->reloc_list, list) {
2262                 unsigned long dest_off;
2263
2264                 if (reloc->sym->type != STT_SECTION) {
2265                         WARN("unexpected relocation symbol type in %s",
2266                              sec->name);
2267                         return -1;
2268                 }
2269
2270                 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2271                 if (!insn) {
2272                         WARN("bad .discard.intra_function_call entry");
2273                         return -1;
2274                 }
2275
2276                 if (insn->type != INSN_CALL) {
2277                         WARN_FUNC("intra_function_call not a direct call",
2278                                   insn->sec, insn->offset);
2279                         return -1;
2280                 }
2281
2282                 /*
2283                  * Treat intra-function CALLs as JMPs, but with a stack_op.
2284                  * See add_call_destinations(), which strips stack_ops from
2285                  * normal CALLs.
2286                  */
2287                 insn->type = INSN_JUMP_UNCONDITIONAL;
2288
2289                 dest_off = arch_jump_destination(insn);
2290                 insn->jump_dest = find_insn(file, insn->sec, dest_off);
2291                 if (!insn->jump_dest) {
2292                         WARN_FUNC("can't find call dest at %s+0x%lx",
2293                                   insn->sec, insn->offset,
2294                                   insn->sec->name, dest_off);
2295                         return -1;
2296                 }
2297         }
2298
2299         return 0;
2300 }
2301
2302 /*
2303  * Return true if name matches an instrumentation function, where calls to that
2304  * function from noinstr code can safely be removed, but compilers won't do so.
2305  */
2306 static bool is_profiling_func(const char *name)
2307 {
2308         /*
2309          * Many compilers cannot disable KCOV with a function attribute.
2310          */
2311         if (!strncmp(name, "__sanitizer_cov_", 16))
2312                 return true;
2313
2314         /*
2315          * Some compilers currently do not remove __tsan_func_entry/exit nor
2316          * __tsan_atomic_signal_fence (used for barrier instrumentation) with
2317          * the __no_sanitize_thread attribute, remove them. Once the kernel's
2318          * minimum Clang version is 14.0, this can be removed.
2319          */
2320         if (!strncmp(name, "__tsan_func_", 12) ||
2321             !strcmp(name, "__tsan_atomic_signal_fence"))
2322                 return true;
2323
2324         return false;
2325 }
2326
2327 static int classify_symbols(struct objtool_file *file)
2328 {
2329         struct section *sec;
2330         struct symbol *func;
2331
2332         for_each_sec(file, sec) {
2333                 list_for_each_entry(func, &sec->symbol_list, list) {
2334                         if (func->bind != STB_GLOBAL)
2335                                 continue;
2336
2337                         if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
2338                                      strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
2339                                 func->static_call_tramp = true;
2340
2341                         if (arch_is_retpoline(func))
2342                                 func->retpoline_thunk = true;
2343
2344                         if (arch_is_rethunk(func))
2345                                 func->return_thunk = true;
2346
2347                         if (arch_is_embedded_insn(func))
2348                                 func->embedded_insn = true;
2349
2350                         if (!strcmp(func->name, "__fentry__"))
2351                                 func->fentry = true;
2352
2353                         if (is_profiling_func(func->name))
2354                                 func->profiling_func = true;
2355                 }
2356         }
2357
2358         return 0;
2359 }
2360
2361 static void mark_rodata(struct objtool_file *file)
2362 {
2363         struct section *sec;
2364         bool found = false;
2365
2366         /*
2367          * Search for the following rodata sections, each of which can
2368          * potentially contain jump tables:
2369          *
2370          * - .rodata: can contain GCC switch tables
2371          * - .rodata.<func>: same, if -fdata-sections is being used
2372          * - .rodata..c_jump_table: contains C annotated jump tables
2373          *
2374          * .rodata.str1.* sections are ignored; they don't contain jump tables.
2375          */
2376         for_each_sec(file, sec) {
2377                 if (!strncmp(sec->name, ".rodata", 7) &&
2378                     !strstr(sec->name, ".str1.")) {
2379                         sec->rodata = true;
2380                         found = true;
2381                 }
2382         }
2383
2384         file->rodata = found;
2385 }
2386
2387 static int decode_sections(struct objtool_file *file)
2388 {
2389         int ret;
2390
2391         mark_rodata(file);
2392
2393         ret = init_pv_ops(file);
2394         if (ret)
2395                 return ret;
2396
2397         ret = decode_instructions(file);
2398         if (ret)
2399                 return ret;
2400
2401         add_ignores(file);
2402         add_uaccess_safe(file);
2403
2404         ret = add_ignore_alternatives(file);
2405         if (ret)
2406                 return ret;
2407
2408         /*
2409          * Must be before read_unwind_hints() since that needs insn->noendbr.
2410          */
2411         ret = read_noendbr_hints(file);
2412         if (ret)
2413                 return ret;
2414
2415         /*
2416          * Must be before add_{jump_call}_destination.
2417          */
2418         ret = classify_symbols(file);
2419         if (ret)
2420                 return ret;
2421
2422         /*
2423          * Must be before add_jump_destinations(), which depends on 'func'
2424          * being set for alternatives, to enable proper sibling call detection.
2425          */
2426         ret = add_special_section_alts(file);
2427         if (ret)
2428                 return ret;
2429
2430         ret = add_jump_destinations(file);
2431         if (ret)
2432                 return ret;
2433
2434         /*
2435          * Must be before add_call_destination(); it changes INSN_CALL to
2436          * INSN_JUMP.
2437          */
2438         ret = read_intra_function_calls(file);
2439         if (ret)
2440                 return ret;
2441
2442         ret = add_call_destinations(file);
2443         if (ret)
2444                 return ret;
2445
2446         /*
2447          * Must be after add_call_destinations() such that it can override
2448          * dead_end_function() marks.
2449          */
2450         ret = add_dead_ends(file);
2451         if (ret)
2452                 return ret;
2453
2454         ret = add_jump_table_alts(file);
2455         if (ret)
2456                 return ret;
2457
2458         ret = read_unwind_hints(file);
2459         if (ret)
2460                 return ret;
2461
2462         ret = read_retpoline_hints(file);
2463         if (ret)
2464                 return ret;
2465
2466         ret = read_instr_hints(file);
2467         if (ret)
2468                 return ret;
2469
2470         return 0;
2471 }
2472
2473 static bool is_special_call(struct instruction *insn)
2474 {
2475         if (insn->type == INSN_CALL) {
2476                 struct symbol *dest = insn->call_dest;
2477
2478                 if (!dest)
2479                         return false;
2480
2481                 if (dest->fentry || dest->embedded_insn)
2482                         return true;
2483         }
2484
2485         return false;
2486 }
2487
2488 static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
2489 {
2490         struct cfi_state *cfi = &state->cfi;
2491         int i;
2492
2493         if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
2494                 return true;
2495
2496         if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
2497                 return true;
2498
2499         if (cfi->stack_size != initial_func_cfi.cfa.offset)
2500                 return true;
2501
2502         for (i = 0; i < CFI_NUM_REGS; i++) {
2503                 if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
2504                     cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
2505                         return true;
2506         }
2507
2508         return false;
2509 }
2510
2511 static bool check_reg_frame_pos(const struct cfi_reg *reg,
2512                                 int expected_offset)
2513 {
2514         return reg->base == CFI_CFA &&
2515                reg->offset == expected_offset;
2516 }
2517
2518 static bool has_valid_stack_frame(struct insn_state *state)
2519 {
2520         struct cfi_state *cfi = &state->cfi;
2521
2522         if (cfi->cfa.base == CFI_BP &&
2523             check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
2524             check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
2525                 return true;
2526
2527         if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
2528                 return true;
2529
2530         return false;
2531 }
2532
2533 static int update_cfi_state_regs(struct instruction *insn,
2534                                   struct cfi_state *cfi,
2535                                   struct stack_op *op)
2536 {
2537         struct cfi_reg *cfa = &cfi->cfa;
2538
2539         if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
2540                 return 0;
2541
2542         /* push */
2543         if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
2544                 cfa->offset += 8;
2545
2546         /* pop */
2547         if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
2548                 cfa->offset -= 8;
2549
2550         /* add immediate to sp */
2551         if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
2552             op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
2553                 cfa->offset -= op->src.offset;
2554
2555         return 0;
2556 }
2557
2558 static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
2559 {
2560         if (arch_callee_saved_reg(reg) &&
2561             cfi->regs[reg].base == CFI_UNDEFINED) {
2562                 cfi->regs[reg].base = base;
2563                 cfi->regs[reg].offset = offset;
2564         }
2565 }
2566
2567 static void restore_reg(struct cfi_state *cfi, unsigned char reg)
2568 {
2569         cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
2570         cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
2571 }
2572
2573 /*
2574  * A note about DRAP stack alignment:
2575  *
2576  * GCC has the concept of a DRAP register, which is used to help keep track of
2577  * the stack pointer when aligning the stack.  r10 or r13 is used as the DRAP
2578  * register.  The typical DRAP pattern is:
2579  *
2580  *   4c 8d 54 24 08             lea    0x8(%rsp),%r10
2581  *   48 83 e4 c0                and    $0xffffffffffffffc0,%rsp
2582  *   41 ff 72 f8                pushq  -0x8(%r10)
2583  *   55                         push   %rbp
2584  *   48 89 e5                   mov    %rsp,%rbp
2585  *                              (more pushes)
2586  *   41 52                      push   %r10
2587  *                              ...
2588  *   41 5a                      pop    %r10
2589  *                              (more pops)
2590  *   5d                         pop    %rbp
2591  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
2592  *   c3                         retq
2593  *
2594  * There are some variations in the epilogues, like:
2595  *
2596  *   5b                         pop    %rbx
2597  *   41 5a                      pop    %r10
2598  *   41 5c                      pop    %r12
2599  *   41 5d                      pop    %r13
2600  *   41 5e                      pop    %r14
2601  *   c9                         leaveq
2602  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
2603  *   c3                         retq
2604  *
2605  * and:
2606  *
2607  *   4c 8b 55 e8                mov    -0x18(%rbp),%r10
2608  *   48 8b 5d e0                mov    -0x20(%rbp),%rbx
2609  *   4c 8b 65 f0                mov    -0x10(%rbp),%r12
2610  *   4c 8b 6d f8                mov    -0x8(%rbp),%r13
2611  *   c9                         leaveq
2612  *   49 8d 62 f8                lea    -0x8(%r10),%rsp
2613  *   c3                         retq
2614  *
2615  * Sometimes r13 is used as the DRAP register, in which case it's saved and
2616  * restored beforehand:
2617  *
2618  *   41 55                      push   %r13
2619  *   4c 8d 6c 24 10             lea    0x10(%rsp),%r13
2620  *   48 83 e4 f0                and    $0xfffffffffffffff0,%rsp
2621  *                              ...
2622  *   49 8d 65 f0                lea    -0x10(%r13),%rsp
2623  *   41 5d                      pop    %r13
2624  *   c3                         retq
2625  */
2626 static int update_cfi_state(struct instruction *insn,
2627                             struct instruction *next_insn,
2628                             struct cfi_state *cfi, struct stack_op *op)
2629 {
2630         struct cfi_reg *cfa = &cfi->cfa;
2631         struct cfi_reg *regs = cfi->regs;
2632
2633         /* stack operations don't make sense with an undefined CFA */
2634         if (cfa->base == CFI_UNDEFINED) {
2635                 if (insn->func) {
2636                         WARN_FUNC("undefined stack state", insn->sec, insn->offset);
2637                         return -1;
2638                 }
2639                 return 0;
2640         }
2641
2642         if (cfi->type == UNWIND_HINT_TYPE_REGS ||
2643             cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
2644                 return update_cfi_state_regs(insn, cfi, op);
2645
2646         switch (op->dest.type) {
2647
2648         case OP_DEST_REG:
2649                 switch (op->src.type) {
2650
2651                 case OP_SRC_REG:
2652                         if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
2653                             cfa->base == CFI_SP &&
2654                             check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {
2655
2656                                 /* mov %rsp, %rbp */
2657                                 cfa->base = op->dest.reg;
2658                                 cfi->bp_scratch = false;
2659                         }
2660
2661                         else if (op->src.reg == CFI_SP &&
2662                                  op->dest.reg == CFI_BP && cfi->drap) {
2663
2664                                 /* drap: mov %rsp, %rbp */
2665                                 regs[CFI_BP].base = CFI_BP;
2666                                 regs[CFI_BP].offset = -cfi->stack_size;
2667                                 cfi->bp_scratch = false;
2668                         }
2669
2670                         else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2671
2672                                 /*
2673                                  * mov %rsp, %reg
2674                                  *
2675                                  * This is needed for the rare case where GCC
2676                                  * does:
2677                                  *
2678                                  *   mov    %rsp, %rax
2679                                  *   ...
2680                                  *   mov    %rax, %rsp
2681                                  */
2682                                 cfi->vals[op->dest.reg].base = CFI_CFA;
2683                                 cfi->vals[op->dest.reg].offset = -cfi->stack_size;
2684                         }
2685
2686                         else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
2687                                  (cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {
2688
2689                                 /*
2690                                  * mov %rbp, %rsp
2691                                  *
2692                                  * Restore the original stack pointer (Clang).
2693                                  */
2694                                 cfi->stack_size = -cfi->regs[CFI_BP].offset;
2695                         }
2696
2697                         else if (op->dest.reg == cfa->base) {
2698
2699                                 /* mov %reg, %rsp */
2700                                 if (cfa->base == CFI_SP &&
2701                                     cfi->vals[op->src.reg].base == CFI_CFA) {
2702
2703                                         /*
2704                                          * This is needed for the rare case
2705                                          * where GCC does something dumb like:
2706                                          *
2707                                          *   lea    0x8(%rsp), %rcx
2708                                          *   ...
2709                                          *   mov    %rcx, %rsp
2710                                          */
2711                                         cfa->offset = -cfi->vals[op->src.reg].offset;
2712                                         cfi->stack_size = cfa->offset;
2713
2714                                 } else if (cfa->base == CFI_SP &&
2715                                            cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2716                                            cfi->vals[op->src.reg].offset == cfa->offset) {
2717
2718                                         /*
2719                                          * Stack swizzle:
2720                                          *
2721                                          * 1: mov %rsp, (%[tos])
2722                                          * 2: mov %[tos], %rsp
2723                                          *    ...
2724                                          * 3: pop %rsp
2725                                          *
2726                                          * Where:
2727                                          *
2728                                          * 1 - places a pointer to the previous
2729                                          *     stack at the Top-of-Stack of the
2730                                          *     new stack.
2731                                          *
2732                                          * 2 - switches to the new stack.
2733                                          *
2734                                          * 3 - pops the Top-of-Stack to restore
2735                                          *     the original stack.
2736                                          *
2737                                          * Note: we set base to SP_INDIRECT
2738                                          * here and preserve offset. Therefore
2739                                          * when the unwinder reaches ToS it
2740                                          * will dereference SP and then add the
2741                                          * offset to find the next frame, IOW:
2742                                          * (%rsp) + offset.
2743                                          */
2744                                         cfa->base = CFI_SP_INDIRECT;
2745
2746                                 } else {
2747                                         cfa->base = CFI_UNDEFINED;
2748                                         cfa->offset = 0;
2749                                 }
2750                         }
2751
2752                         else if (op->dest.reg == CFI_SP &&
2753                                  cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2754                                  cfi->vals[op->src.reg].offset == cfa->offset) {
2755
2756                                 /*
2757                                  * The same stack swizzle case 2) as above. But
2758                                  * because we can't change cfa->base, case 3)
2759                                  * will become a regular POP. Pretend we're a
2760                                  * PUSH so things don't go unbalanced.
2761                                  */
2762                                 cfi->stack_size += 8;
2763                         }
2764
2765
2766                         break;
2767
2768                 case OP_SRC_ADD:
2769                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
2770
2771                                 /* add imm, %rsp */
2772                                 cfi->stack_size -= op->src.offset;
2773                                 if (cfa->base == CFI_SP)
2774                                         cfa->offset -= op->src.offset;
2775                                 break;
2776                         }
2777
2778                         if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
2779
2780                                 /* lea disp(%rbp), %rsp */
2781                                 cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
2782                                 break;
2783                         }
2784
2785                         if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2786
2787                                 /* drap: lea disp(%rsp), %drap */
2788                                 cfi->drap_reg = op->dest.reg;
2789
2790                                 /*
2791                                  * lea disp(%rsp), %reg
2792                                  *
2793                                  * This is needed for the rare case where GCC
2794                                  * does something dumb like:
2795                                  *
2796                                  *   lea    0x8(%rsp), %rcx
2797                                  *   ...
2798                                  *   mov    %rcx, %rsp
2799                                  */
2800                                 cfi->vals[op->dest.reg].base = CFI_CFA;
2801                                 cfi->vals[op->dest.reg].offset = \
2802                                         -cfi->stack_size + op->src.offset;
2803
2804                                 break;
2805                         }
2806
2807                         if (cfi->drap && op->dest.reg == CFI_SP &&
2808                             op->src.reg == cfi->drap_reg) {
2809
2810                                  /* drap: lea disp(%drap), %rsp */
2811                                 cfa->base = CFI_SP;
2812                                 cfa->offset = cfi->stack_size = -op->src.offset;
2813                                 cfi->drap_reg = CFI_UNDEFINED;
2814                                 cfi->drap = false;
2815                                 break;
2816                         }
2817
2818                         if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
2819                                 WARN_FUNC("unsupported stack register modification",
2820                                           insn->sec, insn->offset);
2821                                 return -1;
2822                         }
2823
2824                         break;
2825
2826                 case OP_SRC_AND:
2827                         if (op->dest.reg != CFI_SP ||
2828                             (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
2829                             (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
2830                                 WARN_FUNC("unsupported stack pointer realignment",
2831                                           insn->sec, insn->offset);
2832                                 return -1;
2833                         }
2834
2835                         if (cfi->drap_reg != CFI_UNDEFINED) {
2836                                 /* drap: and imm, %rsp */
2837                                 cfa->base = cfi->drap_reg;
2838                                 cfa->offset = cfi->stack_size = 0;
2839                                 cfi->drap = true;
2840                         }
2841
2842                         /*
2843                          * Older versions of GCC (4.8ish) realign the stack
2844                          * without DRAP, with a frame pointer.
2845                          */
2846
2847                         break;
2848
2849                 case OP_SRC_POP:
2850                 case OP_SRC_POPF:
2851                         if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
2852
2853                                 /* pop %rsp; # restore from a stack swizzle */
2854                                 cfa->base = CFI_SP;
2855                                 break;
2856                         }
2857
2858                         if (!cfi->drap && op->dest.reg == cfa->base) {
2859
2860                                 /* pop %rbp */
2861                                 cfa->base = CFI_SP;
2862                         }
2863
2864                         if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
2865                             op->dest.reg == cfi->drap_reg &&
2866                             cfi->drap_offset == -cfi->stack_size) {
2867
2868                                 /* drap: pop %drap */
2869                                 cfa->base = cfi->drap_reg;
2870                                 cfa->offset = 0;
2871                                 cfi->drap_offset = -1;
2872
2873                         } else if (cfi->stack_size == -regs[op->dest.reg].offset) {
2874
2875                                 /* pop %reg */
2876                                 restore_reg(cfi, op->dest.reg);
2877                         }
2878
2879                         cfi->stack_size -= 8;
2880                         if (cfa->base == CFI_SP)
2881                                 cfa->offset -= 8;
2882
2883                         break;
2884
2885                 case OP_SRC_REG_INDIRECT:
2886                         if (!cfi->drap && op->dest.reg == cfa->base &&
2887                             op->dest.reg == CFI_BP) {
2888
2889                                 /* mov disp(%rsp), %rbp */
2890                                 cfa->base = CFI_SP;
2891                                 cfa->offset = cfi->stack_size;
2892                         }
2893
2894                         if (cfi->drap && op->src.reg == CFI_BP &&
2895                             op->src.offset == cfi->drap_offset) {
2896
2897                                 /* drap: mov disp(%rbp), %drap */
2898                                 cfa->base = cfi->drap_reg;
2899                                 cfa->offset = 0;
2900                                 cfi->drap_offset = -1;
2901                         }
2902
2903                         if (cfi->drap && op->src.reg == CFI_BP &&
2904                             op->src.offset == regs[op->dest.reg].offset) {
2905
2906                                 /* drap: mov disp(%rbp), %reg */
2907                                 restore_reg(cfi, op->dest.reg);
2908
2909                         } else if (op->src.reg == cfa->base &&
2910                             op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
2911
2912                                 /* mov disp(%rbp), %reg */
2913                                 /* mov disp(%rsp), %reg */
2914                                 restore_reg(cfi, op->dest.reg);
2915
2916                         } else if (op->src.reg == CFI_SP &&
2917                                    op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
2918
2919                                 /* mov disp(%rsp), %reg */
2920                                 restore_reg(cfi, op->dest.reg);
2921                         }
2922
2923                         break;
2924
2925                 default:
2926                         WARN_FUNC("unknown stack-related instruction",
2927                                   insn->sec, insn->offset);
2928                         return -1;
2929                 }
2930
2931                 break;
2932
2933         case OP_DEST_PUSH:
2934         case OP_DEST_PUSHF:
2935                 cfi->stack_size += 8;
2936                 if (cfa->base == CFI_SP)
2937                         cfa->offset += 8;
2938
2939                 if (op->src.type != OP_SRC_REG)
2940                         break;
2941
2942                 if (cfi->drap) {
2943                         if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
2944
2945                                 /* drap: push %drap */
2946                                 cfa->base = CFI_BP_INDIRECT;
2947                                 cfa->offset = -cfi->stack_size;
2948
2949                                 /* save drap so we know when to restore it */
2950                                 cfi->drap_offset = -cfi->stack_size;
2951
2952                         } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
2953
2954                                 /* drap: push %rbp */
2955                                 cfi->stack_size = 0;
2956
2957                         } else {
2958
2959                                 /* drap: push %reg */
2960                                 save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
2961                         }
2962
2963                 } else {
2964
2965                         /* push %reg */
2966                         save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
2967                 }
2968
2969                 /* detect when asm code uses rbp as a scratch register */
2970                 if (opts.stackval && insn->func && op->src.reg == CFI_BP &&
2971                     cfa->base != CFI_BP)
2972                         cfi->bp_scratch = true;
2973                 break;
2974
2975         case OP_DEST_REG_INDIRECT:
2976
2977                 if (cfi->drap) {
2978                         if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
2979
2980                                 /* drap: mov %drap, disp(%rbp) */
2981                                 cfa->base = CFI_BP_INDIRECT;
2982                                 cfa->offset = op->dest.offset;
2983
2984                                 /* save drap offset so we know when to restore it */
2985                                 cfi->drap_offset = op->dest.offset;
2986                         } else {
2987
2988                                 /* drap: mov reg, disp(%rbp) */
2989                                 save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
2990                         }
2991
2992                 } else if (op->dest.reg == cfa->base) {
2993
2994                         /* mov reg, disp(%rbp) */
2995                         /* mov reg, disp(%rsp) */
2996                         save_reg(cfi, op->src.reg, CFI_CFA,
2997                                  op->dest.offset - cfi->cfa.offset);
2998
2999                 } else if (op->dest.reg == CFI_SP) {
3000
3001                         /* mov reg, disp(%rsp) */
3002                         save_reg(cfi, op->src.reg, CFI_CFA,
3003                                  op->dest.offset - cfi->stack_size);
3004
3005                 } else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
3006
3007                         /* mov %rsp, (%reg); # setup a stack swizzle. */
3008                         cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
3009                         cfi->vals[op->dest.reg].offset = cfa->offset;
3010                 }
3011
3012                 break;
3013
3014         case OP_DEST_MEM:
3015                 if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
3016                         WARN_FUNC("unknown stack-related memory operation",
3017                                   insn->sec, insn->offset);
3018                         return -1;
3019                 }
3020
3021                 /* pop mem */
3022                 cfi->stack_size -= 8;
3023                 if (cfa->base == CFI_SP)
3024                         cfa->offset -= 8;
3025
3026                 break;
3027
3028         default:
3029                 WARN_FUNC("unknown stack-related instruction",
3030                           insn->sec, insn->offset);
3031                 return -1;
3032         }
3033
3034         return 0;
3035 }
3036
3037 /*
3038  * The stack layouts of alternatives instructions can sometimes diverge when
3039  * they have stack modifications.  That's fine as long as the potential stack
3040  * layouts don't conflict at any given potential instruction boundary.
3041  *
3042  * Flatten the CFIs of the different alternative code streams (both original
3043  * and replacement) into a single shared CFI array which can be used to detect
3044  * conflicts and nicely feed a linear array of ORC entries to the unwinder.
3045  */
3046 static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
3047 {
3048         struct cfi_state **alt_cfi;
3049         int group_off;
3050
3051         if (!insn->alt_group)
3052                 return 0;
3053
3054         if (!insn->cfi) {
3055                 WARN("CFI missing");
3056                 return -1;
3057         }
3058
3059         alt_cfi = insn->alt_group->cfi;
3060         group_off = insn->offset - insn->alt_group->first_insn->offset;
3061
3062         if (!alt_cfi[group_off]) {
3063                 alt_cfi[group_off] = insn->cfi;
3064         } else {
3065                 if (cficmp(alt_cfi[group_off], insn->cfi)) {
3066                         WARN_FUNC("stack layout conflict in alternatives",
3067                                   insn->sec, insn->offset);
3068                         return -1;
3069                 }
3070         }
3071
3072         return 0;
3073 }
3074
3075 static int handle_insn_ops(struct instruction *insn,
3076                            struct instruction *next_insn,
3077                            struct insn_state *state)
3078 {
3079         struct stack_op *op;
3080
3081         list_for_each_entry(op, &insn->stack_ops, list) {
3082
3083                 if (update_cfi_state(insn, next_insn, &state->cfi, op))
3084                         return 1;
3085
3086                 if (!insn->alt_group)
3087                         continue;
3088
3089                 if (op->dest.type == OP_DEST_PUSHF) {
3090                         if (!state->uaccess_stack) {
3091                                 state->uaccess_stack = 1;
3092                         } else if (state->uaccess_stack >> 31) {
3093                                 WARN_FUNC("PUSHF stack exhausted",
3094                                           insn->sec, insn->offset);
3095                                 return 1;
3096                         }
3097                         state->uaccess_stack <<= 1;
3098                         state->uaccess_stack  |= state->uaccess;
3099                 }
3100
3101                 if (op->src.type == OP_SRC_POPF) {
3102                         if (state->uaccess_stack) {
3103                                 state->uaccess = state->uaccess_stack & 1;
3104                                 state->uaccess_stack >>= 1;
3105                                 if (state->uaccess_stack == 1)
3106                                         state->uaccess_stack = 0;
3107                         }
3108                 }
3109         }
3110
3111         return 0;
3112 }
3113
3114 static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
3115 {
3116         struct cfi_state *cfi1 = insn->cfi;
3117         int i;
3118
3119         if (!cfi1) {
3120                 WARN("CFI missing");
3121                 return false;
3122         }
3123
3124         if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
3125
3126                 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
3127                           insn->sec, insn->offset,
3128                           cfi1->cfa.base, cfi1->cfa.offset,
3129                           cfi2->cfa.base, cfi2->cfa.offset);
3130
3131         } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
3132                 for (i = 0; i < CFI_NUM_REGS; i++) {
3133                         if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
3134                                     sizeof(struct cfi_reg)))
3135                                 continue;
3136
3137                         WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
3138                                   insn->sec, insn->offset,
3139                                   i, cfi1->regs[i].base, cfi1->regs[i].offset,
3140                                   i, cfi2->regs[i].base, cfi2->regs[i].offset);
3141                         break;
3142                 }
3143
3144         } else if (cfi1->type != cfi2->type) {
3145
3146                 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
3147                           insn->sec, insn->offset, cfi1->type, cfi2->type);
3148
3149         } else if (cfi1->drap != cfi2->drap ||
3150                    (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
3151                    (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
3152
3153                 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
3154                           insn->sec, insn->offset,
3155                           cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
3156                           cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
3157
3158         } else
3159                 return true;
3160
3161         return false;
3162 }
3163
3164 static inline bool func_uaccess_safe(struct symbol *func)
3165 {
3166         if (func)
3167                 return func->uaccess_safe;
3168
3169         return false;
3170 }
3171
3172 static inline const char *call_dest_name(struct instruction *insn)
3173 {
3174         static char pvname[19];
3175         struct reloc *rel;
3176         int idx;
3177
3178         if (insn->call_dest)
3179                 return insn->call_dest->name;
3180
3181         rel = insn_reloc(NULL, insn);
3182         if (rel && !strcmp(rel->sym->name, "pv_ops")) {
3183                 idx = (rel->addend / sizeof(void *));
3184                 snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
3185                 return pvname;
3186         }
3187
3188         return "{dynamic}";
3189 }
3190
3191 static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
3192 {
3193         struct symbol *target;
3194         struct reloc *rel;
3195         int idx;
3196
3197         rel = insn_reloc(file, insn);
3198         if (!rel || strcmp(rel->sym->name, "pv_ops"))
3199                 return false;
3200
3201         idx = (arch_dest_reloc_offset(rel->addend) / sizeof(void *));
3202
3203         if (file->pv_ops[idx].clean)
3204                 return true;
3205
3206         file->pv_ops[idx].clean = true;
3207
3208         list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
3209                 if (!target->sec->noinstr) {
3210                         WARN("pv_ops[%d]: %s", idx, target->name);
3211                         file->pv_ops[idx].clean = false;
3212                 }
3213         }
3214
3215         return file->pv_ops[idx].clean;
3216 }
3217
3218 static inline bool noinstr_call_dest(struct objtool_file *file,
3219                                      struct instruction *insn,
3220                                      struct symbol *func)
3221 {
3222         /*
3223          * We can't deal with indirect function calls at present;
3224          * assume they're instrumented.
3225          */
3226         if (!func) {
3227                 if (file->pv_ops)
3228                         return pv_call_dest(file, insn);
3229
3230                 return false;
3231         }
3232
3233         /*
3234          * If the symbol is from a noinstr section; we good.
3235          */
3236         if (func->sec->noinstr)
3237                 return true;
3238
3239         /*
3240          * The __ubsan_handle_*() calls are like WARN(), they only happen when
3241          * something 'BAD' happened. At the risk of taking the machine down,
3242          * let them proceed to get the message out.
3243          */
3244         if (!strncmp(func->name, "__ubsan_handle_", 15))
3245                 return true;
3246
3247         return false;
3248 }
3249
3250 static int validate_call(struct objtool_file *file,
3251                          struct instruction *insn,
3252                          struct insn_state *state)
3253 {
3254         if (state->noinstr && state->instr <= 0 &&
3255             !noinstr_call_dest(file, insn, insn->call_dest)) {
3256                 WARN_FUNC("call to %s() leaves .noinstr.text section",
3257                                 insn->sec, insn->offset, call_dest_name(insn));
3258                 return 1;
3259         }
3260
3261         if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
3262                 WARN_FUNC("call to %s() with UACCESS enabled",
3263                                 insn->sec, insn->offset, call_dest_name(insn));
3264                 return 1;
3265         }
3266
3267         if (state->df) {
3268                 WARN_FUNC("call to %s() with DF set",
3269                                 insn->sec, insn->offset, call_dest_name(insn));
3270                 return 1;
3271         }
3272
3273         return 0;
3274 }
3275
3276 static int validate_sibling_call(struct objtool_file *file,
3277                                  struct instruction *insn,
3278                                  struct insn_state *state)
3279 {
3280         if (has_modified_stack_frame(insn, state)) {
3281                 WARN_FUNC("sibling call from callable instruction with modified stack frame",
3282                                 insn->sec, insn->offset);
3283                 return 1;
3284         }
3285
3286         return validate_call(file, insn, state);
3287 }
3288
3289 static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
3290 {
3291         if (state->noinstr && state->instr > 0) {
3292                 WARN_FUNC("return with instrumentation enabled",
3293                           insn->sec, insn->offset);
3294                 return 1;
3295         }
3296
3297         if (state->uaccess && !func_uaccess_safe(func)) {
3298                 WARN_FUNC("return with UACCESS enabled",
3299                           insn->sec, insn->offset);
3300                 return 1;
3301         }
3302
3303         if (!state->uaccess && func_uaccess_safe(func)) {
3304                 WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function",
3305                           insn->sec, insn->offset);
3306                 return 1;
3307         }
3308
3309         if (state->df) {
3310                 WARN_FUNC("return with DF set",
3311                           insn->sec, insn->offset);
3312                 return 1;
3313         }
3314
3315         if (func && has_modified_stack_frame(insn, state)) {
3316                 WARN_FUNC("return with modified stack frame",
3317                           insn->sec, insn->offset);
3318                 return 1;
3319         }
3320
3321         if (state->cfi.bp_scratch) {
3322                 WARN_FUNC("BP used as a scratch register",
3323                           insn->sec, insn->offset);
3324                 return 1;
3325         }
3326
3327         return 0;
3328 }
3329
3330 static struct instruction *next_insn_to_validate(struct objtool_file *file,
3331                                                  struct instruction *insn)
3332 {
3333         struct alt_group *alt_group = insn->alt_group;
3334
3335         /*
3336          * Simulate the fact that alternatives are patched in-place.  When the
3337          * end of a replacement alt_group is reached, redirect objtool flow to
3338          * the end of the original alt_group.
3339          */
3340         if (alt_group && insn == alt_group->last_insn && alt_group->orig_group)
3341                 return next_insn_same_sec(file, alt_group->orig_group->last_insn);
3342
3343         return next_insn_same_sec(file, insn);
3344 }
3345
3346 /*
3347  * Follow the branch starting at the given instruction, and recursively follow
3348  * any other branches (jumps).  Meanwhile, track the frame pointer state at
3349  * each instruction and validate all the rules described in
3350  * tools/objtool/Documentation/objtool.txt.
3351  */
3352 static int validate_branch(struct objtool_file *file, struct symbol *func,
3353                            struct instruction *insn, struct insn_state state)
3354 {
3355         struct alternative *alt;
3356         struct instruction *next_insn, *prev_insn = NULL;
3357         struct section *sec;
3358         u8 visited;
3359         int ret;
3360
3361         sec = insn->sec;
3362
3363         while (1) {
3364                 next_insn = next_insn_to_validate(file, insn);
3365
3366                 if (func && insn->func && func != insn->func->pfunc) {
3367                         /* Ignore KCFI type preambles, which always fall through */
3368                         if (!strncmp(func->name, "__cfi_", 6))
3369                                 return 0;
3370
3371                         WARN("%s() falls through to next function %s()",
3372                              func->name, insn->func->name);
3373                         return 1;
3374                 }
3375
3376                 if (func && insn->ignore) {
3377                         WARN_FUNC("BUG: why am I validating an ignored function?",
3378                                   sec, insn->offset);
3379                         return 1;
3380                 }
3381
3382                 visited = VISITED_BRANCH << state.uaccess;
3383                 if (insn->visited & VISITED_BRANCH_MASK) {
3384                         if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
3385                                 return 1;
3386
3387                         if (insn->visited & visited)
3388                                 return 0;
3389                 } else {
3390                         nr_insns_visited++;
3391                 }
3392
3393                 if (state.noinstr)
3394                         state.instr += insn->instr;
3395
3396                 if (insn->hint) {
3397                         if (insn->restore) {
3398                                 struct instruction *save_insn, *i;
3399
3400                                 i = insn;
3401                                 save_insn = NULL;
3402
3403                                 sym_for_each_insn_continue_reverse(file, func, i) {
3404                                         if (i->save) {
3405                                                 save_insn = i;
3406                                                 break;
3407                                         }
3408                                 }
3409
3410                                 if (!save_insn) {
3411                                         WARN_FUNC("no corresponding CFI save for CFI restore",
3412                                                   sec, insn->offset);
3413                                         return 1;
3414                                 }
3415
3416                                 if (!save_insn->visited) {
3417                                         WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
3418                                                   sec, insn->offset);
3419                                         return 1;
3420                                 }
3421
3422                                 insn->cfi = save_insn->cfi;
3423                                 nr_cfi_reused++;
3424                         }
3425
3426                         state.cfi = *insn->cfi;
3427                 } else {
3428                         /* XXX track if we actually changed state.cfi */
3429
3430                         if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {
3431                                 insn->cfi = prev_insn->cfi;
3432                                 nr_cfi_reused++;
3433                         } else {
3434                                 insn->cfi = cfi_hash_find_or_add(&state.cfi);
3435                         }
3436                 }
3437
3438                 insn->visited |= visited;
3439
3440                 if (propagate_alt_cfi(file, insn))
3441                         return 1;
3442
3443                 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
3444                         bool skip_orig = false;
3445
3446                         list_for_each_entry(alt, &insn->alts, list) {
3447                                 if (alt->skip_orig)
3448                                         skip_orig = true;
3449
3450                                 ret = validate_branch(file, func, alt->insn, state);
3451                                 if (ret) {
3452                                         if (opts.backtrace)
3453                                                 BT_FUNC("(alt)", insn);
3454                                         return ret;
3455                                 }
3456                         }
3457
3458                         if (skip_orig)
3459                                 return 0;
3460                 }
3461
3462                 if (handle_insn_ops(insn, next_insn, &state))
3463                         return 1;
3464
3465                 switch (insn->type) {
3466
3467                 case INSN_RETURN:
3468                         return validate_return(func, insn, &state);
3469
3470                 case INSN_CALL:
3471                 case INSN_CALL_DYNAMIC:
3472                         ret = validate_call(file, insn, &state);
3473                         if (ret)
3474                                 return ret;
3475
3476                         if (opts.stackval && func && !is_special_call(insn) &&
3477                             !has_valid_stack_frame(&state)) {
3478                                 WARN_FUNC("call without frame pointer save/setup",
3479                                           sec, insn->offset);
3480                                 return 1;
3481                         }
3482
3483                         if (insn->dead_end)
3484                                 return 0;
3485
3486                         break;
3487
3488                 case INSN_JUMP_CONDITIONAL:
3489                 case INSN_JUMP_UNCONDITIONAL:
3490                         if (is_sibling_call(insn)) {
3491                                 ret = validate_sibling_call(file, insn, &state);
3492                                 if (ret)
3493                                         return ret;
3494
3495                         } else if (insn->jump_dest) {
3496                                 ret = validate_branch(file, func,
3497                                                       insn->jump_dest, state);
3498                                 if (ret) {
3499                                         if (opts.backtrace)
3500                                                 BT_FUNC("(branch)", insn);
3501                                         return ret;
3502                                 }
3503                         }
3504
3505                         if (insn->type == INSN_JUMP_UNCONDITIONAL)
3506                                 return 0;
3507
3508                         break;
3509
3510                 case INSN_JUMP_DYNAMIC:
3511                 case INSN_JUMP_DYNAMIC_CONDITIONAL:
3512                         if (is_sibling_call(insn)) {
3513                                 ret = validate_sibling_call(file, insn, &state);
3514                                 if (ret)
3515                                         return ret;
3516                         }
3517
3518                         if (insn->type == INSN_JUMP_DYNAMIC)
3519                                 return 0;
3520
3521                         break;
3522
3523                 case INSN_CONTEXT_SWITCH:
3524                         if (func && (!next_insn || !next_insn->hint)) {
3525                                 WARN_FUNC("unsupported instruction in callable function",
3526                                           sec, insn->offset);
3527                                 return 1;
3528                         }
3529                         return 0;
3530
3531                 case INSN_STAC:
3532                         if (state.uaccess) {
3533                                 WARN_FUNC("recursive UACCESS enable", sec, insn->offset);
3534                                 return 1;
3535                         }
3536
3537                         state.uaccess = true;
3538                         break;
3539
3540                 case INSN_CLAC:
3541                         if (!state.uaccess && func) {
3542                                 WARN_FUNC("redundant UACCESS disable", sec, insn->offset);
3543                                 return 1;
3544                         }
3545
3546                         if (func_uaccess_safe(func) && !state.uaccess_stack) {
3547                                 WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset);
3548                                 return 1;
3549                         }
3550
3551                         state.uaccess = false;
3552                         break;
3553
3554                 case INSN_STD:
3555                         if (state.df) {
3556                                 WARN_FUNC("recursive STD", sec, insn->offset);
3557                                 return 1;
3558                         }
3559
3560                         state.df = true;
3561                         break;
3562
3563                 case INSN_CLD:
3564                         if (!state.df && func) {
3565                                 WARN_FUNC("redundant CLD", sec, insn->offset);
3566                                 return 1;
3567                         }
3568
3569                         state.df = false;
3570                         break;
3571
3572                 default:
3573                         break;
3574                 }
3575
3576                 if (insn->dead_end)
3577                         return 0;
3578
3579                 if (!next_insn) {
3580                         if (state.cfi.cfa.base == CFI_UNDEFINED)
3581                                 return 0;
3582                         WARN("%s: unexpected end of section", sec->name);
3583                         return 1;
3584                 }
3585
3586                 prev_insn = insn;
3587                 insn = next_insn;
3588         }
3589
3590         return 0;
3591 }
3592
3593 static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
3594 {
3595         struct instruction *insn;
3596         struct insn_state state;
3597         int ret, warnings = 0;
3598
3599         if (!file->hints)
3600                 return 0;
3601
3602         init_insn_state(file, &state, sec);
3603
3604         if (sec) {
3605                 insn = find_insn(file, sec, 0);
3606                 if (!insn)
3607                         return 0;
3608         } else {
3609                 insn = list_first_entry(&file->insn_list, typeof(*insn), list);
3610         }
3611
3612         while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
3613                 if (insn->hint && !insn->visited && !insn->ignore) {
3614                         ret = validate_branch(file, insn->func, insn, state);
3615                         if (ret && opts.backtrace)
3616                                 BT_FUNC("<=== (hint)", insn);
3617                         warnings += ret;
3618                 }
3619
3620                 insn = list_next_entry(insn, list);
3621         }
3622
3623         return warnings;
3624 }
3625
3626 /*
3627  * Validate rethunk entry constraint: must untrain RET before the first RET.
3628  *
3629  * Follow every branch (intra-function) and ensure ANNOTATE_UNRET_END comes
3630  * before an actual RET instruction.
3631  */
3632 static int validate_entry(struct objtool_file *file, struct instruction *insn)
3633 {
3634         struct instruction *next, *dest;
3635         int ret, warnings = 0;
3636
3637         for (;;) {
3638                 next = next_insn_to_validate(file, insn);
3639
3640                 if (insn->visited & VISITED_ENTRY)
3641                         return 0;
3642
3643                 insn->visited |= VISITED_ENTRY;
3644
3645                 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
3646                         struct alternative *alt;
3647                         bool skip_orig = false;
3648
3649                         list_for_each_entry(alt, &insn->alts, list) {
3650                                 if (alt->skip_orig)
3651                                         skip_orig = true;
3652
3653                                 ret = validate_entry(file, alt->insn);
3654                                 if (ret) {
3655                                         if (opts.backtrace)
3656                                                 BT_FUNC("(alt)", insn);
3657                                         return ret;
3658                                 }
3659                         }
3660
3661                         if (skip_orig)
3662                                 return 0;
3663                 }
3664
3665                 switch (insn->type) {
3666
3667                 case INSN_CALL_DYNAMIC:
3668                 case INSN_JUMP_DYNAMIC:
3669                 case INSN_JUMP_DYNAMIC_CONDITIONAL:
3670                         WARN_FUNC("early indirect call", insn->sec, insn->offset);
3671                         return 1;
3672
3673                 case INSN_JUMP_UNCONDITIONAL:
3674                 case INSN_JUMP_CONDITIONAL:
3675                         if (!is_sibling_call(insn)) {
3676                                 if (!insn->jump_dest) {
3677                                         WARN_FUNC("unresolved jump target after linking?!?",
3678                                                   insn->sec, insn->offset);
3679                                         return -1;
3680                                 }
3681                                 ret = validate_entry(file, insn->jump_dest);
3682                                 if (ret) {
3683                                         if (opts.backtrace) {
3684                                                 BT_FUNC("(branch%s)", insn,
3685                                                         insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
3686                                         }
3687                                         return ret;
3688                                 }
3689
3690                                 if (insn->type == INSN_JUMP_UNCONDITIONAL)
3691                                         return 0;
3692
3693                                 break;
3694                         }
3695
3696                         /* fallthrough */
3697                 case INSN_CALL:
3698                         dest = find_insn(file, insn->call_dest->sec,
3699                                          insn->call_dest->offset);
3700                         if (!dest) {
3701                                 WARN("Unresolved function after linking!?: %s",
3702                                      insn->call_dest->name);
3703                                 return -1;
3704                         }
3705
3706                         ret = validate_entry(file, dest);
3707                         if (ret) {
3708                                 if (opts.backtrace)
3709                                         BT_FUNC("(call)", insn);
3710                                 return ret;
3711                         }
3712                         /*
3713                          * If a call returns without error, it must have seen UNTRAIN_RET.
3714                          * Therefore any non-error return is a success.
3715                          */
3716                         return 0;
3717
3718                 case INSN_RETURN:
3719                         WARN_FUNC("RET before UNTRAIN", insn->sec, insn->offset);
3720                         return 1;
3721
3722                 case INSN_NOP:
3723                         if (insn->retpoline_safe)
3724                                 return 0;
3725                         break;
3726
3727                 default:
3728                         break;
3729                 }
3730
3731                 if (!next) {
3732                         WARN_FUNC("teh end!", insn->sec, insn->offset);
3733                         return -1;
3734                 }
3735                 insn = next;
3736         }
3737
3738         return warnings;
3739 }
3740
3741 /*
3742  * Validate that all branches starting at 'insn->entry' encounter UNRET_END
3743  * before RET.
3744  */
3745 static int validate_unret(struct objtool_file *file)
3746 {
3747         struct instruction *insn;
3748         int ret, warnings = 0;
3749
3750         for_each_insn(file, insn) {
3751                 if (!insn->entry)
3752                         continue;
3753
3754                 ret = validate_entry(file, insn);
3755                 if (ret < 0) {
3756                         WARN_FUNC("Failed UNRET validation", insn->sec, insn->offset);
3757                         return ret;
3758                 }
3759                 warnings += ret;
3760         }
3761
3762         return warnings;
3763 }
3764
3765 static int validate_retpoline(struct objtool_file *file)
3766 {
3767         struct instruction *insn;
3768         int warnings = 0;
3769
3770         for_each_insn(file, insn) {
3771                 if (insn->type != INSN_JUMP_DYNAMIC &&
3772                     insn->type != INSN_CALL_DYNAMIC &&
3773                     insn->type != INSN_RETURN)
3774                         continue;
3775
3776                 if (insn->retpoline_safe)
3777                         continue;
3778
3779                 /*
3780                  * .init.text code is ran before userspace and thus doesn't
3781                  * strictly need retpolines, except for modules which are
3782                  * loaded late, they very much do need retpoline in their
3783                  * .init.text
3784                  */
3785                 if (!strcmp(insn->sec->name, ".init.text") && !opts.module)
3786                         continue;
3787
3788                 if (insn->type == INSN_RETURN) {
3789                         if (opts.rethunk) {
3790                                 WARN_FUNC("'naked' return found in RETHUNK build",
3791                                           insn->sec, insn->offset);
3792                         } else
3793                                 continue;
3794                 } else {
3795                         WARN_FUNC("indirect %s found in RETPOLINE build",
3796                                   insn->sec, insn->offset,
3797                                   insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
3798                 }
3799
3800                 warnings++;
3801         }
3802
3803         return warnings;
3804 }
3805
3806 static bool is_kasan_insn(struct instruction *insn)
3807 {
3808         return (insn->type == INSN_CALL &&
3809                 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
3810 }
3811
3812 static bool is_ubsan_insn(struct instruction *insn)
3813 {
3814         return (insn->type == INSN_CALL &&
3815                 !strcmp(insn->call_dest->name,
3816                         "__ubsan_handle_builtin_unreachable"));
3817 }
3818
3819 static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
3820 {
3821         int i;
3822         struct instruction *prev_insn;
3823
3824         if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
3825                 return true;
3826
3827         /*
3828          * Ignore alternative replacement instructions.  This can happen
3829          * when a whitelisted function uses one of the ALTERNATIVE macros.
3830          */
3831         if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
3832             !strcmp(insn->sec->name, ".altinstr_aux"))
3833                 return true;
3834
3835         /*
3836          * Whole archive runs might encounter dead code from weak symbols.
3837          * This is where the linker will have dropped the weak symbol in
3838          * favour of a regular symbol, but leaves the code in place.
3839          *
3840          * In this case we'll find a piece of code (whole function) that is not
3841          * covered by a !section symbol. Ignore them.
3842          */
3843         if (opts.link && !insn->func) {
3844                 int size = find_symbol_hole_containing(insn->sec, insn->offset);
3845                 unsigned long end = insn->offset + size;
3846
3847                 if (!size) /* not a hole */
3848                         return false;
3849
3850                 if (size < 0) /* hole until the end */
3851                         return true;
3852
3853                 sec_for_each_insn_continue(file, insn) {
3854                         /*
3855                          * If we reach a visited instruction at or before the
3856                          * end of the hole, ignore the unreachable.
3857                          */
3858                         if (insn->visited)
3859                                 return true;
3860
3861                         if (insn->offset >= end)
3862                                 break;
3863
3864                         /*
3865                          * If this hole jumps to a .cold function, mark it ignore too.
3866                          */
3867                         if (insn->jump_dest && insn->jump_dest->func &&
3868                             strstr(insn->jump_dest->func->name, ".cold")) {
3869                                 struct instruction *dest = insn->jump_dest;
3870                                 func_for_each_insn(file, dest->func, dest)
3871                                         dest->ignore = true;
3872                         }
3873                 }
3874
3875                 return false;
3876         }
3877
3878         if (!insn->func)
3879                 return false;
3880
3881         if (insn->func->static_call_tramp)
3882                 return true;
3883
3884         /*
3885          * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
3886          * __builtin_unreachable().  The BUG() macro has an unreachable() after
3887          * the UD2, which causes GCC's undefined trap logic to emit another UD2
3888          * (or occasionally a JMP to UD2).
3889          *
3890          * It may also insert a UD2 after calling a __noreturn function.
3891          */
3892         prev_insn = list_prev_entry(insn, list);
3893         if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&
3894             (insn->type == INSN_BUG ||
3895              (insn->type == INSN_JUMP_UNCONDITIONAL &&
3896               insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
3897                 return true;
3898
3899         /*
3900          * Check if this (or a subsequent) instruction is related to
3901          * CONFIG_UBSAN or CONFIG_KASAN.
3902          *
3903          * End the search at 5 instructions to avoid going into the weeds.
3904          */
3905         for (i = 0; i < 5; i++) {
3906
3907                 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
3908                         return true;
3909
3910                 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
3911                         if (insn->jump_dest &&
3912                             insn->jump_dest->func == insn->func) {
3913                                 insn = insn->jump_dest;
3914                                 continue;
3915                         }
3916
3917                         break;
3918                 }
3919
3920                 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
3921                         break;
3922
3923                 insn = list_next_entry(insn, list);
3924         }
3925
3926         return false;
3927 }
3928
3929 static int validate_symbol(struct objtool_file *file, struct section *sec,
3930                            struct symbol *sym, struct insn_state *state)
3931 {
3932         struct instruction *insn;
3933         int ret;
3934
3935         if (!sym->len) {
3936                 WARN("%s() is missing an ELF size annotation", sym->name);
3937                 return 1;
3938         }
3939
3940         if (sym->pfunc != sym || sym->alias != sym)
3941                 return 0;
3942
3943         insn = find_insn(file, sec, sym->offset);
3944         if (!insn || insn->ignore || insn->visited)
3945                 return 0;
3946
3947         state->uaccess = sym->uaccess_safe;
3948
3949         ret = validate_branch(file, insn->func, insn, *state);
3950         if (ret && opts.backtrace)
3951                 BT_FUNC("<=== (sym)", insn);
3952         return ret;
3953 }
3954
3955 static int validate_section(struct objtool_file *file, struct section *sec)
3956 {
3957         struct insn_state state;
3958         struct symbol *func;
3959         int warnings = 0;
3960
3961         list_for_each_entry(func, &sec->symbol_list, list) {
3962                 if (func->type != STT_FUNC)
3963                         continue;
3964
3965                 init_insn_state(file, &state, sec);
3966                 set_func_state(&state.cfi);
3967
3968                 warnings += validate_symbol(file, sec, func, &state);
3969         }
3970
3971         return warnings;
3972 }
3973
3974 static int validate_noinstr_sections(struct objtool_file *file)
3975 {
3976         struct section *sec;
3977         int warnings = 0;
3978
3979         sec = find_section_by_name(file->elf, ".noinstr.text");
3980         if (sec) {
3981                 warnings += validate_section(file, sec);
3982                 warnings += validate_unwind_hints(file, sec);
3983         }
3984
3985         sec = find_section_by_name(file->elf, ".entry.text");
3986         if (sec) {
3987                 warnings += validate_section(file, sec);
3988                 warnings += validate_unwind_hints(file, sec);
3989         }
3990
3991         return warnings;
3992 }
3993
3994 static int validate_functions(struct objtool_file *file)
3995 {
3996         struct section *sec;
3997         int warnings = 0;
3998
3999         for_each_sec(file, sec) {
4000                 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
4001                         continue;
4002
4003                 warnings += validate_section(file, sec);
4004         }
4005
4006         return warnings;
4007 }
4008
4009 static void mark_endbr_used(struct instruction *insn)
4010 {
4011         if (!list_empty(&insn->call_node))
4012                 list_del_init(&insn->call_node);
4013 }
4014
4015 static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
4016 {
4017         struct instruction *dest;
4018         struct reloc *reloc;
4019         unsigned long off;
4020         int warnings = 0;
4021
4022         /*
4023          * Looking for function pointer load relocations.  Ignore
4024          * direct/indirect branches:
4025          */
4026         switch (insn->type) {
4027         case INSN_CALL:
4028         case INSN_CALL_DYNAMIC:
4029         case INSN_JUMP_CONDITIONAL:
4030         case INSN_JUMP_UNCONDITIONAL:
4031         case INSN_JUMP_DYNAMIC:
4032         case INSN_JUMP_DYNAMIC_CONDITIONAL:
4033         case INSN_RETURN:
4034         case INSN_NOP:
4035                 return 0;
4036         default:
4037                 break;
4038         }
4039
4040         for (reloc = insn_reloc(file, insn);
4041              reloc;
4042              reloc = find_reloc_by_dest_range(file->elf, insn->sec,
4043                                               reloc->offset + 1,
4044                                               (insn->offset + insn->len) - (reloc->offset + 1))) {
4045
4046                 /*
4047                  * static_call_update() references the trampoline, which
4048                  * doesn't have (or need) ENDBR.  Skip warning in that case.
4049                  */
4050                 if (reloc->sym->static_call_tramp)
4051                         continue;
4052
4053                 off = reloc->sym->offset;
4054                 if (reloc->type == R_X86_64_PC32 || reloc->type == R_X86_64_PLT32)
4055                         off += arch_dest_reloc_offset(reloc->addend);
4056                 else
4057                         off += reloc->addend;
4058
4059                 dest = find_insn(file, reloc->sym->sec, off);
4060                 if (!dest)
4061                         continue;
4062
4063                 if (dest->type == INSN_ENDBR) {
4064                         mark_endbr_used(dest);
4065                         continue;
4066                 }
4067
4068                 if (dest->func && dest->func == insn->func) {
4069                         /*
4070                          * Anything from->to self is either _THIS_IP_ or
4071                          * IRET-to-self.
4072                          *
4073                          * There is no sane way to annotate _THIS_IP_ since the
4074                          * compiler treats the relocation as a constant and is
4075                          * happy to fold in offsets, skewing any annotation we
4076                          * do, leading to vast amounts of false-positives.
4077                          *
4078                          * There's also compiler generated _THIS_IP_ through
4079                          * KCOV and such which we have no hope of annotating.
4080                          *
4081                          * As such, blanket accept self-references without
4082                          * issue.
4083                          */
4084                         continue;
4085                 }
4086
4087                 if (dest->noendbr)
4088                         continue;
4089
4090                 WARN_FUNC("relocation to !ENDBR: %s",
4091                           insn->sec, insn->offset,
4092                           offstr(dest->sec, dest->offset));
4093
4094                 warnings++;
4095         }
4096
4097         return warnings;
4098 }
4099
4100 static int validate_ibt_data_reloc(struct objtool_file *file,
4101                                    struct reloc *reloc)
4102 {
4103         struct instruction *dest;
4104
4105         dest = find_insn(file, reloc->sym->sec,
4106                          reloc->sym->offset + reloc->addend);
4107         if (!dest)
4108                 return 0;
4109
4110         if (dest->type == INSN_ENDBR) {
4111                 mark_endbr_used(dest);
4112                 return 0;
4113         }
4114
4115         if (dest->noendbr)
4116                 return 0;
4117
4118         WARN_FUNC("data relocation to !ENDBR: %s",
4119                   reloc->sec->base, reloc->offset,
4120                   offstr(dest->sec, dest->offset));
4121
4122         return 1;
4123 }
4124
4125 /*
4126  * Validate IBT rules and remove used ENDBR instructions from the seal list.
4127  * Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
4128  * NOPs) later, in create_ibt_endbr_seal_sections().
4129  */
4130 static int validate_ibt(struct objtool_file *file)
4131 {
4132         struct section *sec;
4133         struct reloc *reloc;
4134         struct instruction *insn;
4135         int warnings = 0;
4136
4137         for_each_insn(file, insn)
4138                 warnings += validate_ibt_insn(file, insn);
4139
4140         for_each_sec(file, sec) {
4141
4142                 /* Already done by validate_ibt_insn() */
4143                 if (sec->sh.sh_flags & SHF_EXECINSTR)
4144                         continue;
4145
4146                 if (!sec->reloc)
4147                         continue;
4148
4149                 /*
4150                  * These sections can reference text addresses, but not with
4151                  * the intent to indirect branch to them.
4152                  */
4153                 if ((!strncmp(sec->name, ".discard", 8) &&
4154                      strcmp(sec->name, ".discard.ibt_endbr_noseal"))    ||
4155                     !strncmp(sec->name, ".debug", 6)                    ||
4156                     !strcmp(sec->name, ".altinstructions")              ||
4157                     !strcmp(sec->name, ".ibt_endbr_seal")               ||
4158                     !strcmp(sec->name, ".orc_unwind_ip")                ||
4159                     !strcmp(sec->name, ".parainstructions")             ||
4160                     !strcmp(sec->name, ".retpoline_sites")              ||
4161                     !strcmp(sec->name, ".smp_locks")                    ||
4162                     !strcmp(sec->name, ".static_call_sites")            ||
4163                     !strcmp(sec->name, "_error_injection_whitelist")    ||
4164                     !strcmp(sec->name, "_kprobe_blacklist")             ||
4165                     !strcmp(sec->name, "__bug_table")                   ||
4166                     !strcmp(sec->name, "__ex_table")                    ||
4167                     !strcmp(sec->name, "__jump_table")                  ||
4168                     !strcmp(sec->name, "__mcount_loc")                  ||
4169                     !strcmp(sec->name, ".kcfi_traps")                   ||
4170                     strstr(sec->name, "__patchable_function_entries"))
4171                         continue;
4172
4173                 list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
4174                         warnings += validate_ibt_data_reloc(file, reloc);
4175         }
4176
4177         return warnings;
4178 }
4179
4180 static int validate_sls(struct objtool_file *file)
4181 {
4182         struct instruction *insn, *next_insn;
4183         int warnings = 0;
4184
4185         for_each_insn(file, insn) {
4186                 next_insn = next_insn_same_sec(file, insn);
4187
4188                 if (insn->retpoline_safe)
4189                         continue;
4190
4191                 switch (insn->type) {
4192                 case INSN_RETURN:
4193                         if (!next_insn || next_insn->type != INSN_TRAP) {
4194                                 WARN_FUNC("missing int3 after ret",
4195                                           insn->sec, insn->offset);
4196                                 warnings++;
4197                         }
4198
4199                         break;
4200                 case INSN_JUMP_DYNAMIC:
4201                         if (!next_insn || next_insn->type != INSN_TRAP) {
4202                                 WARN_FUNC("missing int3 after indirect jump",
4203                                           insn->sec, insn->offset);
4204                                 warnings++;
4205                         }
4206                         break;
4207                 default:
4208                         break;
4209                 }
4210         }
4211
4212         return warnings;
4213 }
4214
4215 static int validate_reachable_instructions(struct objtool_file *file)
4216 {
4217         struct instruction *insn;
4218
4219         if (file->ignore_unreachables)
4220                 return 0;
4221
4222         for_each_insn(file, insn) {
4223                 if (insn->visited || ignore_unreachable_insn(file, insn))
4224                         continue;
4225
4226                 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
4227                 return 1;
4228         }
4229
4230         return 0;
4231 }
4232
4233 int check(struct objtool_file *file)
4234 {
4235         int ret, warnings = 0;
4236
4237         arch_initial_func_cfi_state(&initial_func_cfi);
4238         init_cfi_state(&init_cfi);
4239         init_cfi_state(&func_cfi);
4240         set_func_state(&func_cfi);
4241
4242         if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
4243                 goto out;
4244
4245         cfi_hash_add(&init_cfi);
4246         cfi_hash_add(&func_cfi);
4247
4248         ret = decode_sections(file);
4249         if (ret < 0)
4250                 goto out;
4251
4252         warnings += ret;
4253
4254         if (list_empty(&file->insn_list))
4255                 goto out;
4256
4257         if (opts.retpoline) {
4258                 ret = validate_retpoline(file);
4259                 if (ret < 0)
4260                         return ret;
4261                 warnings += ret;
4262         }
4263
4264         if (opts.stackval || opts.orc || opts.uaccess) {
4265                 ret = validate_functions(file);
4266                 if (ret < 0)
4267                         goto out;
4268                 warnings += ret;
4269
4270                 ret = validate_unwind_hints(file, NULL);
4271                 if (ret < 0)
4272                         goto out;
4273                 warnings += ret;
4274
4275                 if (!warnings) {
4276                         ret = validate_reachable_instructions(file);
4277                         if (ret < 0)
4278                                 goto out;
4279                         warnings += ret;
4280                 }
4281
4282         } else if (opts.noinstr) {
4283                 ret = validate_noinstr_sections(file);
4284                 if (ret < 0)
4285                         goto out;
4286                 warnings += ret;
4287         }
4288
4289         if (opts.unret) {
4290                 /*
4291                  * Must be after validate_branch() and friends, it plays
4292                  * further games with insn->visited.
4293                  */
4294                 ret = validate_unret(file);
4295                 if (ret < 0)
4296                         return ret;
4297                 warnings += ret;
4298         }
4299
4300         if (opts.ibt) {
4301                 ret = validate_ibt(file);
4302                 if (ret < 0)
4303                         goto out;
4304                 warnings += ret;
4305         }
4306
4307         if (opts.sls) {
4308                 ret = validate_sls(file);
4309                 if (ret < 0)
4310                         goto out;
4311                 warnings += ret;
4312         }
4313
4314         if (opts.static_call) {
4315                 ret = create_static_call_sections(file);
4316                 if (ret < 0)
4317                         goto out;
4318                 warnings += ret;
4319         }
4320
4321         if (opts.retpoline) {
4322                 ret = create_retpoline_sites_sections(file);
4323                 if (ret < 0)
4324                         goto out;
4325                 warnings += ret;
4326         }
4327
4328         if (opts.rethunk) {
4329                 ret = create_return_sites_sections(file);
4330                 if (ret < 0)
4331                         goto out;
4332                 warnings += ret;
4333         }
4334
4335         if (opts.mcount) {
4336                 ret = create_mcount_loc_sections(file);
4337                 if (ret < 0)
4338                         goto out;
4339                 warnings += ret;
4340         }
4341
4342         if (opts.ibt) {
4343                 ret = create_ibt_endbr_seal_sections(file);
4344                 if (ret < 0)
4345                         goto out;
4346                 warnings += ret;
4347         }
4348
4349         if (opts.orc && !list_empty(&file->insn_list)) {
4350                 ret = orc_create(file);
4351                 if (ret < 0)
4352                         goto out;
4353                 warnings += ret;
4354         }
4355
4356
4357         if (opts.stats) {
4358                 printf("nr_insns_visited: %ld\n", nr_insns_visited);
4359                 printf("nr_cfi: %ld\n", nr_cfi);
4360                 printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
4361                 printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
4362         }
4363
4364 out:
4365         /*
4366          *  For now, don't fail the kernel build on fatal warnings.  These
4367          *  errors are still fairly common due to the growing matrix of
4368          *  supported toolchains and their recent pace of change.
4369          */
4370         return 0;
4371 }