]> git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blame - tools/objtool/check.c
projects / mirror_ubuntu-jammy-kernel.git / blame
? search:
summary | shortlog | log | commit | commitdiff | tree
blob | blame (incremental) | history | HEAD
x86/retpoline: Simplify retpolines
[mirror_ubuntu-jammy-kernel.git] / tools / objtool / check.c
CommitLineData
1ccea77e 1// SPDX-License-Identifier: GPL-2.0-or-later
dcc914f4
JP		 2/*
3 * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
dcc914f4
JP		 4 */
5
6#include <string.h>
7#include <stdlib.h>
8
7786032e
VG		 9#include <arch/elf.h>
10#include <objtool/builtin.h>
11#include <objtool/cfi.h>
12#include <objtool/arch.h>
13#include <objtool/check.h>
14#include <objtool/special.h>
15#include <objtool/warn.h>
16#include <objtool/endianness.h>
dcc914f4 17
ee819aed 18#include <linux/objtool.h>
dcc914f4
JP		 19#include <linux/hashtable.h>
20#include <linux/kernel.h>
1e7e4788 21#include <linux/static_call_types.h>
dcc914f4 22
dcc914f4
JP		 23struct alternative {
24 struct list_head list;
25 struct instruction *insn;
764eef4b 26 bool skip_orig;
dcc914f4
JP		 27};
28
a3608f59 29struct cfi_init_state initial_func_cfi;
dcc914f4 30
627fce14
JP		 31struct instruction *find_insn(struct objtool_file *file,
32 struct section *sec, unsigned long offset)
dcc914f4
JP		 33{
34 struct instruction *insn;
35
87ecb582 36 hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
dcc914f4
JP		 37 if (insn->sec == sec && insn->offset == offset)
38 return insn;
87ecb582 39 }
dcc914f4
JP		 40
41 return NULL;
42}
43
44static struct instruction *next_insn_same_sec(struct objtool_file *file,
45 struct instruction *insn)
46{
47 struct instruction *next = list_next_entry(insn, list);
48
baa41469 49 if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
dcc914f4
JP		 50 return NULL;
51
52 return next;
53}
54
13810435
JP		 55static struct instruction *next_insn_same_func(struct objtool_file *file,
56 struct instruction *insn)
57{
58 struct instruction *next = list_next_entry(insn, list);
59 struct symbol *func = insn->func;
60
61 if (!func)
62 return NULL;
63
64 if (&next->list != &file->insn_list && next->func == func)
65 return next;
66
67 /* Check if we're already in the subfunction: */
68 if (func == func->cfunc)
69 return NULL;
70
71 /* Move to the subfunction: */
72 return find_insn(file, func->cfunc->sec, func->cfunc->offset);
73}
74
1119d265
JP		 75static struct instruction *prev_insn_same_sym(struct objtool_file *file,
76 struct instruction *insn)
77{
78 struct instruction *prev = list_prev_entry(insn, list);
79
80 if (&prev->list != &file->insn_list && prev->func == insn->func)
81 return prev;
82
83 return NULL;
84}
85
f0f70adb 86#define func_for_each_insn(file, func, insn) \
13810435
JP		 87 for (insn = find_insn(file, func->sec, func->offset); \
88 insn; \
89 insn = next_insn_same_func(file, insn))
90
dbf4aeb0
PZ		 91#define sym_for_each_insn(file, sym, insn) \
92 for (insn = find_insn(file, sym->sec, sym->offset); \
dcc914f4 93 insn && &insn->list != &file->insn_list && \
dbf4aeb0
PZ		 94 insn->sec == sym->sec && \
95 insn->offset < sym->offset + sym->len; \
dcc914f4
JP		 96 insn = list_next_entry(insn, list))
97
dbf4aeb0 98#define sym_for_each_insn_continue_reverse(file, sym, insn) \
dcc914f4
JP		 99 for (insn = list_prev_entry(insn, list); \
100 &insn->list != &file->insn_list && \
dbf4aeb0 101 insn->sec == sym->sec && insn->offset >= sym->offset; \
dcc914f4
JP		 102 insn = list_prev_entry(insn, list))
103
104#define sec_for_each_insn_from(file, insn) \
105 for (; insn; insn = next_insn_same_sec(file, insn))
106
baa41469
JP		 107#define sec_for_each_insn_continue(file, insn) \
108 for (insn = next_insn_same_sec(file, insn); insn; \
109 insn = next_insn_same_sec(file, insn))
dcc914f4 110
0c1ddd33
JP		 111static bool is_sibling_call(struct instruction *insn)
112{
ecf11ba4
JP		 113 /*
114 * Assume only ELF functions can make sibling calls. This ensures
115 * sibling call detection consistency between vmlinux.o and individual
116 * objects.
117 */
118 if (!insn->func)
119 return false;
120
0c1ddd33
JP		 121 /* An indirect jump is either a sibling call or a jump to a table. */
122 if (insn->type == INSN_JUMP_DYNAMIC)
123 return list_empty(&insn->alts);
124
0c1ddd33 125 /* add_jump_destinations() sets insn->call_dest for sibling calls. */
ecf11ba4 126 return (is_static_jump(insn) && insn->call_dest);
0c1ddd33
JP		 127}
128
dcc914f4
JP		 129/*
130 * This checks to see if the given function is a "noreturn" function.
131 *
132 * For global functions which are outside the scope of this object file, we
133 * have to keep a manual list of them.
134 *
135 * For local functions, we have to detect them manually by simply looking for
136 * the lack of a return instruction.
dcc914f4 137 */
8e25c9f8
JP		 138static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
139 int recursion)
dcc914f4
JP		 140{
141 int i;
142 struct instruction *insn;
143 bool empty = true;
144
145 /*
146 * Unfortunately these have to be hard coded because the noreturn
147 * attribute isn't provided in ELF data.
148 */
149 static const char * const global_noreturns[] = {
150 "__stack_chk_fail",
151 "panic",
152 "do_exit",
153 "do_task_dead",
154 "__module_put_and_exit",
155 "complete_and_exit",
dcc914f4
JP		 156 "__reiserfs_panic",
157 "lbug_with_loc",
158 "fortify_panic",
b394d468 159 "usercopy_abort",
684fb246 160 "machine_real_restart",
4fa5ecda 161 "rewind_stack_do_exit",
33adf80f 162 "kunit_try_catch_throw",
c26acfbb 163 "xen_start_kernel",
dcc914f4
JP		 164 };
165
c9bab22b
JP		 166 if (!func)
167 return false;
168
dcc914f4 169 if (func->bind == STB_WEAK)
8e25c9f8 170 return false;
dcc914f4
JP		 171
172 if (func->bind == STB_GLOBAL)
173 for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
174 if (!strcmp(func->name, global_noreturns[i]))
8e25c9f8 175 return true;
dcc914f4 176
13810435 177 if (!func->len)
8e25c9f8 178 return false;
dcc914f4 179
13810435
JP		 180 insn = find_insn(file, func->sec, func->offset);
181 if (!insn->func)
8e25c9f8 182 return false;
13810435 183
f0f70adb 184 func_for_each_insn(file, func, insn) {
dcc914f4
JP		 185 empty = false;
186
187 if (insn->type == INSN_RETURN)
8e25c9f8 188 return false;
dcc914f4
JP		 189 }
190
191 if (empty)
8e25c9f8 192 return false;
dcc914f4
JP		 193
194 /*
195 * A function can have a sibling call instead of a return. In that
196 * case, the function's dead-end status depends on whether the target
197 * of the sibling call returns.
198 */
f0f70adb 199 func_for_each_insn(file, func, insn) {
0c1ddd33 200 if (is_sibling_call(insn)) {
dcc914f4 201 struct instruction *dest = insn->jump_dest;
dcc914f4
JP		 202
203 if (!dest)
204 /* sibling call to another file */
8e25c9f8 205 return false;
dcc914f4 206
0c1ddd33
JP		 207 /* local sibling call */
208 if (recursion == 5) {
209 /*
210 * Infinite recursion: two functions have
211 * sibling calls to each other. This is a very
212 * rare case. It means they aren't dead ends.
213 */
214 return false;
dcc914f4 215 }
dcc914f4 216
0c1ddd33
JP		 217 return __dead_end_function(file, dest->func, recursion+1);
218 }
dcc914f4
JP		 219 }
220
8e25c9f8 221 return true;
dcc914f4
JP		 222}
223
8e25c9f8 224static bool dead_end_function(struct objtool_file *file, struct symbol *func)
dcc914f4
JP		 225{
226 return __dead_end_function(file, func, 0);
227}
228
e7c0219b 229static void init_cfi_state(struct cfi_state *cfi)
baa41469
JP		 230{
231 int i;
232
dd88a0a0 233 for (i = 0; i < CFI_NUM_REGS; i++) {
e7c0219b
PZ		 234 cfi->regs[i].base = CFI_UNDEFINED;
235 cfi->vals[i].base = CFI_UNDEFINED;
dd88a0a0 236 }
e7c0219b
PZ		 237 cfi->cfa.base = CFI_UNDEFINED;
238 cfi->drap_reg = CFI_UNDEFINED;
239 cfi->drap_offset = -1;
240}
241
932f8e98 242static void init_insn_state(struct insn_state *state, struct section *sec)
e7c0219b
PZ		 243{
244 memset(state, 0, sizeof(*state));
245 init_cfi_state(&state->cfi);
932f8e98
PZ		 246
247 /*
248 * We need the full vmlinux for noinstr validation, otherwise we can
249 * not correctly determine insn->call_dest->sec (external symbols do
250 * not have a section).
251 */
41425ebe 252 if (vmlinux && noinstr && sec)
932f8e98 253 state->noinstr = sec->noinstr;
baa41469
JP		 254}
255
dcc914f4
JP		 256/*
257 * Call the arch-specific instruction decoder for all the instructions and add
258 * them to the global instruction list.
259 */
260static int decode_instructions(struct objtool_file *file)
261{
262 struct section *sec;
263 struct symbol *func;
264 unsigned long offset;
265 struct instruction *insn;
1e11f3fd 266 unsigned long nr_insns = 0;
dcc914f4
JP		 267 int ret;
268
baa41469 269 for_each_sec(file, sec) {
dcc914f4
JP		 270
271 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
272 continue;
273
627fce14
JP		 274 if (strcmp(sec->name, ".altinstr_replacement") &&
275 strcmp(sec->name, ".altinstr_aux") &&
276 strncmp(sec->name, ".discard.", 9))
277 sec->text = true;
278
0cc9ac8d
TG		 279 if (!strcmp(sec->name, ".noinstr.text") ||
280 !strcmp(sec->name, ".entry.text"))
c4a33939
PZ		 281 sec->noinstr = true;
282
dcc914f4
JP		 283 for (offset = 0; offset < sec->len; offset += insn->len) {
284 insn = malloc(sizeof(*insn));
baa41469
JP		 285 if (!insn) {
286 WARN("malloc failed");
287 return -1;
288 }
dcc914f4 289 memset(insn, 0, sizeof(*insn));
dcc914f4 290 INIT_LIST_HEAD(&insn->alts);
65ea47dc 291 INIT_LIST_HEAD(&insn->stack_ops);
e7c0219b 292 init_cfi_state(&insn->cfi);
baa41469 293
dcc914f4
JP		 294 insn->sec = sec;
295 insn->offset = offset;
296
297 ret = arch_decode_instruction(file->elf, sec, offset,
298 sec->len - offset,
299 &insn->len, &insn->type,
baa41469 300 &insn->immediate,
65ea47dc 301 &insn->stack_ops);
dcc914f4 302 if (ret)
b7037983 303 goto err;
dcc914f4 304
87ecb582 305 hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
dcc914f4 306 list_add_tail(&insn->list, &file->insn_list);
1e11f3fd 307 nr_insns++;
dcc914f4
JP		 308 }
309
310 list_for_each_entry(func, &sec->symbol_list, list) {
e10cd8fe 311 if (func->type != STT_FUNC || func->alias != func)
dcc914f4
JP		 312 continue;
313
314 if (!find_insn(file, sec, func->offset)) {
315 WARN("%s(): can't find starting instruction",
316 func->name);
317 return -1;
318 }
319
dbf4aeb0 320 sym_for_each_insn(file, func, insn)
e10cd8fe 321 insn->func = func;
dcc914f4
JP		 322 }
323 }
324
1e11f3fd
PZ		 325 if (stats)
326 printf("nr_insns: %lu\n", nr_insns);
327
dcc914f4 328 return 0;
b7037983
KB		 329
330err:
331 free(insn);
332 return ret;
dcc914f4
JP		 333}
334
6b5dd716
ST		 335static struct instruction *find_last_insn(struct objtool_file *file,
336 struct section *sec)
337{
338 struct instruction *insn = NULL;
339 unsigned int offset;
340 unsigned int end = (sec->len > 10) ? sec->len - 10 : 0;
341
342 for (offset = sec->len - 1; offset >= end && !insn; offset--)
343 insn = find_insn(file, sec, offset);
344
345 return insn;
346}
347
dcc914f4 348/*
649ea4d5 349 * Mark "ud2" instructions and manually annotated dead ends.
dcc914f4
JP		 350 */
351static int add_dead_ends(struct objtool_file *file)
352{
353 struct section *sec;
f1974222 354 struct reloc *reloc;
dcc914f4 355 struct instruction *insn;
dcc914f4 356
649ea4d5
JP		 357 /*
358 * By default, "ud2" is a dead end unless otherwise annotated, because
359 * GCC 7 inserts it for certain divide-by-zero cases.
360 */
361 for_each_insn(file, insn)
362 if (insn->type == INSN_BUG)
363 insn->dead_end = true;
364
365 /*
366 * Check for manually annotated dead ends.
367 */
dcc914f4
JP		 368 sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
369 if (!sec)
649ea4d5 370 goto reachable;
dcc914f4 371
f1974222
MH		 372 list_for_each_entry(reloc, &sec->reloc_list, list) {
373 if (reloc->sym->type != STT_SECTION) {
dcc914f4
JP		 374 WARN("unexpected relocation symbol type in %s", sec->name);
375 return -1;
376 }
f1974222 377 insn = find_insn(file, reloc->sym->sec, reloc->addend);
dcc914f4
JP		 378 if (insn)
379 insn = list_prev_entry(insn, list);
f1974222
MH		 380 else if (reloc->addend == reloc->sym->sec->len) {
381 insn = find_last_insn(file, reloc->sym->sec);
6b5dd716 382 if (!insn) {
dcc914f4 383 WARN("can't find unreachable insn at %s+0x%x",
f1974222 384 reloc->sym->sec->name, reloc->addend);
dcc914f4
JP		 385 return -1;
386 }
387 } else {
388 WARN("can't find unreachable insn at %s+0x%x",
f1974222 389 reloc->sym->sec->name, reloc->addend);
dcc914f4
JP		 390 return -1;
391 }
392
393 insn->dead_end = true;
394 }
395
649ea4d5
JP		 396reachable:
397 /*
398 * These manually annotated reachable checks are needed for GCC 4.4,
399 * where the Linux unreachable() macro isn't supported. In that case
400 * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
401 * not a dead end.
402 */
403 sec = find_section_by_name(file->elf, ".rela.discard.reachable");
404 if (!sec)
405 return 0;
406
f1974222
MH		 407 list_for_each_entry(reloc, &sec->reloc_list, list) {
408 if (reloc->sym->type != STT_SECTION) {
649ea4d5
JP		 409 WARN("unexpected relocation symbol type in %s", sec->name);
410 return -1;
411 }
f1974222 412 insn = find_insn(file, reloc->sym->sec, reloc->addend);
649ea4d5
JP		 413 if (insn)
414 insn = list_prev_entry(insn, list);
f1974222
MH		 415 else if (reloc->addend == reloc->sym->sec->len) {
416 insn = find_last_insn(file, reloc->sym->sec);
6b5dd716 417 if (!insn) {
649ea4d5 418 WARN("can't find reachable insn at %s+0x%x",
f1974222 419 reloc->sym->sec->name, reloc->addend);
649ea4d5
JP		 420 return -1;
421 }
422 } else {
423 WARN("can't find reachable insn at %s+0x%x",
f1974222 424 reloc->sym->sec->name, reloc->addend);
649ea4d5
JP		 425 return -1;
426 }
427
428 insn->dead_end = false;
429 }
430
dcc914f4
JP		 431 return 0;
432}
433
1e7e4788
JP		 434static int create_static_call_sections(struct objtool_file *file)
435{
436 struct section *sec, *reloc_sec;
437 struct reloc *reloc;
438 struct static_call_site *site;
439 struct instruction *insn;
440 struct symbol *key_sym;
441 char *key_name, *tmp;
442 int idx;
443
444 sec = find_section_by_name(file->elf, ".static_call_sites");
445 if (sec) {
446 INIT_LIST_HEAD(&file->static_call_list);
447 WARN("file already has .static_call_sites section, skipping");
448 return 0;
449 }
450
451 if (list_empty(&file->static_call_list))
452 return 0;
453
454 idx = 0;
455 list_for_each_entry(insn, &file->static_call_list, static_call_node)
456 idx++;
457
458 sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
459 sizeof(struct static_call_site), idx);
460 if (!sec)
461 return -1;
462
463 reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
464 if (!reloc_sec)
465 return -1;
466
467 idx = 0;
468 list_for_each_entry(insn, &file->static_call_list, static_call_node) {
469
470 site = (struct static_call_site *)sec->data->d_buf + idx;
471 memset(site, 0, sizeof(struct static_call_site));
472
473 /* populate reloc for 'addr' */
474 reloc = malloc(sizeof(*reloc));
44f6a7c0 475
1e7e4788
JP		 476 if (!reloc) {
477 perror("malloc");
478 return -1;
479 }
480 memset(reloc, 0, sizeof(*reloc));
44f6a7c0
JP		 481
482 insn_to_reloc_sym_addend(insn->sec, insn->offset, reloc);
483 if (!reloc->sym) {
484 WARN_FUNC("static call tramp: missing containing symbol",
485 insn->sec, insn->offset);
486 return -1;
487 }
488
1e7e4788
JP		 489 reloc->type = R_X86_64_PC32;
490 reloc->offset = idx * sizeof(struct static_call_site);
491 reloc->sec = reloc_sec;
492 elf_add_reloc(file->elf, reloc);
493
494 /* find key symbol */
495 key_name = strdup(insn->call_dest->name);
496 if (!key_name) {
497 perror("strdup");
498 return -1;
499 }
500 if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
501 STATIC_CALL_TRAMP_PREFIX_LEN)) {
502 WARN("static_call: trampoline name malformed: %s", key_name);
503 return -1;
504 }
505 tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
506 memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
507
508 key_sym = find_symbol_by_name(file->elf, tmp);
509 if (!key_sym) {
73f44fe1
JP		 510 if (!module) {
511 WARN("static_call: can't find static_call_key symbol: %s", tmp);
512 return -1;
513 }
514
515 /*
516 * For modules(), the key might not be exported, which
517 * means the module can make static calls but isn't
518 * allowed to change them.
519 *
520 * In that case we temporarily set the key to be the
521 * trampoline address. This is fixed up in
522 * static_call_add_module().
523 */
524 key_sym = insn->call_dest;
1e7e4788
JP		 525 }
526 free(key_name);
527
528 /* populate reloc for 'key' */
529 reloc = malloc(sizeof(*reloc));
530 if (!reloc) {
531 perror("malloc");
532 return -1;
533 }
534 memset(reloc, 0, sizeof(*reloc));
535 reloc->sym = key_sym;
5b06fd3b 536 reloc->addend = is_sibling_call(insn) ? STATIC_CALL_SITE_TAIL : 0;
1e7e4788
JP		 537 reloc->type = R_X86_64_PC32;
538 reloc->offset = idx * sizeof(struct static_call_site) + 4;
539 reloc->sec = reloc_sec;
540 elf_add_reloc(file->elf, reloc);
541
542 idx++;
543 }
544
545 if (elf_rebuild_reloc_section(file->elf, reloc_sec))
546 return -1;
547
548 return 0;
549}
550
99d00215
PZ		 551static int create_mcount_loc_sections(struct objtool_file *file)
552{
553 struct section *sec, *reloc_sec;
554 struct reloc *reloc;
555 unsigned long *loc;
556 struct instruction *insn;
557 int idx;
558
559 sec = find_section_by_name(file->elf, "__mcount_loc");
560 if (sec) {
561 INIT_LIST_HEAD(&file->mcount_loc_list);
562 WARN("file already has __mcount_loc section, skipping");
563 return 0;
564 }
565
566 if (list_empty(&file->mcount_loc_list))
567 return 0;
568
569 idx = 0;
570 list_for_each_entry(insn, &file->mcount_loc_list, mcount_loc_node)
571 idx++;
572
573 sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx);
574 if (!sec)
575 return -1;
576
577 reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
578 if (!reloc_sec)
579 return -1;
580
581 idx = 0;
582 list_for_each_entry(insn, &file->mcount_loc_list, mcount_loc_node) {
583
584 loc = (unsigned long *)sec->data->d_buf + idx;
585 memset(loc, 0, sizeof(unsigned long));
586
587 reloc = malloc(sizeof(*reloc));
588 if (!reloc) {
589 perror("malloc");
590 return -1;
591 }
592 memset(reloc, 0, sizeof(*reloc));
593
18a14575
ST		 594 if (insn->sec->sym) {
595 reloc->sym = insn->sec->sym;
596 reloc->addend = insn->offset;
597 } else {
598 reloc->sym = find_symbol_containing(insn->sec, insn->offset);
599
600 if (!reloc->sym) {
601 WARN("missing symbol for insn at offset 0x%lx\n",
602 insn->offset);
603 return -1;
604 }
605
606 reloc->addend = insn->offset - reloc->sym->offset;
607 }
608
99d00215
PZ		 609 reloc->type = R_X86_64_64;
610 reloc->offset = idx * sizeof(unsigned long);
611 reloc->sec = reloc_sec;
612 elf_add_reloc(file->elf, reloc);
613
614 idx++;
615 }
616
617 if (elf_rebuild_reloc_section(file->elf, reloc_sec))
618 return -1;
619
620 return 0;
621}
622
dcc914f4
JP		 623/*
624 * Warnings shouldn't be reported for ignored functions.
625 */
626static void add_ignores(struct objtool_file *file)
627{
628 struct instruction *insn;
629 struct section *sec;
630 struct symbol *func;
f1974222 631 struct reloc *reloc;
dcc914f4 632
aaf5c623
PZ		 633 sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
634 if (!sec)
635 return;
dcc914f4 636
f1974222
MH		 637 list_for_each_entry(reloc, &sec->reloc_list, list) {
638 switch (reloc->sym->type) {
aaf5c623 639 case STT_FUNC:
f1974222 640 func = reloc->sym;
aaf5c623
PZ		 641 break;
642
643 case STT_SECTION:
f1974222 644 func = find_func_by_offset(reloc->sym->sec, reloc->addend);
7acfe531 645 if (!func)
dcc914f4 646 continue;
aaf5c623 647 break;
dcc914f4 648
aaf5c623 649 default:
f1974222 650 WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type);
aaf5c623 651 continue;
dcc914f4 652 }
aaf5c623 653
f0f70adb 654 func_for_each_insn(file, func, insn)
aaf5c623 655 insn->ignore = true;
dcc914f4
JP		 656 }
657}
658
ea24213d
PZ		 659/*
660 * This is a whitelist of functions that is allowed to be called with AC set.
661 * The list is meant to be minimal and only contains compiler instrumentation
662 * ABI and a few functions used to implement *_{to,from}_user() functions.
663 *
664 * These functions must not directly change AC, but may PUSHF/POPF.
665 */
666static const char *uaccess_safe_builtin[] = {
667 /* KASAN */
668 "kasan_report",
f00748bf 669 "kasan_check_range",
ea24213d
PZ		 670 /* KASAN out-of-line */
671 "__asan_loadN_noabort",
672 "__asan_load1_noabort",
673 "__asan_load2_noabort",
674 "__asan_load4_noabort",
675 "__asan_load8_noabort",
676 "__asan_load16_noabort",
677 "__asan_storeN_noabort",
678 "__asan_store1_noabort",
679 "__asan_store2_noabort",
680 "__asan_store4_noabort",
681 "__asan_store8_noabort",
682 "__asan_store16_noabort",
b0b8e56b
JH		 683 "__kasan_check_read",
684 "__kasan_check_write",
ea24213d
PZ		 685 /* KASAN in-line */
686 "__asan_report_load_n_noabort",
687 "__asan_report_load1_noabort",
688 "__asan_report_load2_noabort",
689 "__asan_report_load4_noabort",
690 "__asan_report_load8_noabort",
691 "__asan_report_load16_noabort",
692 "__asan_report_store_n_noabort",
693 "__asan_report_store1_noabort",
694 "__asan_report_store2_noabort",
695 "__asan_report_store4_noabort",
696 "__asan_report_store8_noabort",
697 "__asan_report_store16_noabort",
5f5c9712 698 /* KCSAN */
9967683c 699 "__kcsan_check_access",
5f5c9712
ME		 700 "kcsan_found_watchpoint",
701 "kcsan_setup_watchpoint",
9967683c 702 "kcsan_check_scoped_accesses",
50a19ad4
ME		 703 "kcsan_disable_current",
704 "kcsan_enable_current_nowarn",
5f5c9712
ME		 705 /* KCSAN/TSAN */
706 "__tsan_func_entry",
707 "__tsan_func_exit",
708 "__tsan_read_range",
709 "__tsan_write_range",
710 "__tsan_read1",
711 "__tsan_read2",
712 "__tsan_read4",
713 "__tsan_read8",
714 "__tsan_read16",
715 "__tsan_write1",
716 "__tsan_write2",
717 "__tsan_write4",
718 "__tsan_write8",
719 "__tsan_write16",
a81b3759
ME		 720 "__tsan_read_write1",
721 "__tsan_read_write2",
722 "__tsan_read_write4",
723 "__tsan_read_write8",
724 "__tsan_read_write16",
883957b1
ME		 725 "__tsan_atomic8_load",
726 "__tsan_atomic16_load",
727 "__tsan_atomic32_load",
728 "__tsan_atomic64_load",
729 "__tsan_atomic8_store",
730 "__tsan_atomic16_store",
731 "__tsan_atomic32_store",
732 "__tsan_atomic64_store",
733 "__tsan_atomic8_exchange",
734 "__tsan_atomic16_exchange",
735 "__tsan_atomic32_exchange",
736 "__tsan_atomic64_exchange",
737 "__tsan_atomic8_fetch_add",
738 "__tsan_atomic16_fetch_add",
739 "__tsan_atomic32_fetch_add",
740 "__tsan_atomic64_fetch_add",
741 "__tsan_atomic8_fetch_sub",
742 "__tsan_atomic16_fetch_sub",
743 "__tsan_atomic32_fetch_sub",
744 "__tsan_atomic64_fetch_sub",
745 "__tsan_atomic8_fetch_and",
746 "__tsan_atomic16_fetch_and",
747 "__tsan_atomic32_fetch_and",
748 "__tsan_atomic64_fetch_and",
749 "__tsan_atomic8_fetch_or",
750 "__tsan_atomic16_fetch_or",
751 "__tsan_atomic32_fetch_or",
752 "__tsan_atomic64_fetch_or",
753 "__tsan_atomic8_fetch_xor",
754 "__tsan_atomic16_fetch_xor",
755 "__tsan_atomic32_fetch_xor",
756 "__tsan_atomic64_fetch_xor",
757 "__tsan_atomic8_fetch_nand",
758 "__tsan_atomic16_fetch_nand",
759 "__tsan_atomic32_fetch_nand",
760 "__tsan_atomic64_fetch_nand",
761 "__tsan_atomic8_compare_exchange_strong",
762 "__tsan_atomic16_compare_exchange_strong",
763 "__tsan_atomic32_compare_exchange_strong",
764 "__tsan_atomic64_compare_exchange_strong",
765 "__tsan_atomic8_compare_exchange_weak",
766 "__tsan_atomic16_compare_exchange_weak",
767 "__tsan_atomic32_compare_exchange_weak",
768 "__tsan_atomic64_compare_exchange_weak",
769 "__tsan_atomic8_compare_exchange_val",
770 "__tsan_atomic16_compare_exchange_val",
771 "__tsan_atomic32_compare_exchange_val",
772 "__tsan_atomic64_compare_exchange_val",
773 "__tsan_atomic_thread_fence",
774 "__tsan_atomic_signal_fence",
ea24213d
PZ		 775 /* KCOV */
776 "write_comp_data",
ae033f08 777 "check_kcov_mode",
ea24213d
PZ		 778 "__sanitizer_cov_trace_pc",
779 "__sanitizer_cov_trace_const_cmp1",
780 "__sanitizer_cov_trace_const_cmp2",
781 "__sanitizer_cov_trace_const_cmp4",
782 "__sanitizer_cov_trace_const_cmp8",
783 "__sanitizer_cov_trace_cmp1",
784 "__sanitizer_cov_trace_cmp2",
785 "__sanitizer_cov_trace_cmp4",
786 "__sanitizer_cov_trace_cmp8",
36b1c700 787 "__sanitizer_cov_trace_switch",
ea24213d
PZ		 788 /* UBSAN */
789 "ubsan_type_mismatch_common",
790 "__ubsan_handle_type_mismatch",
791 "__ubsan_handle_type_mismatch_v1",
9a50dcaf 792 "__ubsan_handle_shift_out_of_bounds",
ea24213d
PZ		 793 /* misc */
794 "csum_partial_copy_generic",
ec6347bb
DW		 795 "copy_mc_fragile",
796 "copy_mc_fragile_handle_tail",
5da8e4a6 797 "copy_mc_enhanced_fast_string",
ea24213d
PZ		 798 "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
799 NULL
800};
801
802static void add_uaccess_safe(struct objtool_file *file)
803{
804 struct symbol *func;
805 const char **name;
806
807 if (!uaccess)
808 return;
809
810 for (name = uaccess_safe_builtin; *name; name++) {
811 func = find_symbol_by_name(file->elf, *name);
812 if (!func)
813 continue;
814
e10cd8fe 815 func->uaccess_safe = true;
dcc914f4
JP		 816 }
817}
818
258c7605
JP		 819/*
820 * FIXME: For now, just ignore any alternatives which add retpolines. This is
821 * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
822 * But it at least allows objtool to understand the control flow *around* the
823 * retpoline.
824 */
ff05ab23 825static int add_ignore_alternatives(struct objtool_file *file)
258c7605
JP		 826{
827 struct section *sec;
f1974222 828 struct reloc *reloc;
258c7605
JP		 829 struct instruction *insn;
830
ff05ab23 831 sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
258c7605
JP		 832 if (!sec)
833 return 0;
834
f1974222
MH		 835 list_for_each_entry(reloc, &sec->reloc_list, list) {
836 if (reloc->sym->type != STT_SECTION) {
258c7605
JP		 837 WARN("unexpected relocation symbol type in %s", sec->name);
838 return -1;
839 }
840
f1974222 841 insn = find_insn(file, reloc->sym->sec, reloc->addend);
258c7605 842 if (!insn) {
ff05ab23 843 WARN("bad .discard.ignore_alts entry");
258c7605
JP		 844 return -1;
845 }
846
847 insn->ignore_alts = true;
848 }
849
850 return 0;
851}
852
dcc914f4
JP		 853/*
854 * Find the destination instructions for all jumps.
855 */
856static int add_jump_destinations(struct objtool_file *file)
857{
858 struct instruction *insn;
f1974222 859 struct reloc *reloc;
dcc914f4
JP		 860 struct section *dest_sec;
861 unsigned long dest_off;
862
863 for_each_insn(file, insn) {
a2296140 864 if (!is_static_jump(insn))
dcc914f4
JP		 865 continue;
866
f1974222 867 reloc = find_reloc_by_dest_range(file->elf, insn->sec,
ecf11ba4 868 insn->offset, insn->len);
f1974222 869 if (!reloc) {
dcc914f4 870 dest_sec = insn->sec;
bfb08f22 871 dest_off = arch_jump_destination(insn);
f1974222
MH		 872 } else if (reloc->sym->type == STT_SECTION) {
873 dest_sec = reloc->sym->sec;
874 dest_off = arch_dest_reloc_offset(reloc->addend);
11925185 875 } else if (!strncmp(reloc->sym->name, "__x86_indirect_thunk_", 21)) {
39b73533
JP		 876 /*
877 * Retpoline jumps are really dynamic jumps in
878 * disguise, so convert them accordingly.
879 */
b68b9907
JP		 880 if (insn->type == INSN_JUMP_UNCONDITIONAL)
881 insn->type = INSN_JUMP_DYNAMIC;
882 else
883 insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
884
b5bc2231 885 insn->retpoline_safe = true;
39b73533 886 continue;
ecf11ba4
JP		 887 } else if (insn->func) {
888 /* internal or external sibling call (with reloc) */
f1974222 889 insn->call_dest = reloc->sym;
5b06fd3b
PZ		 890 if (insn->call_dest->static_call_tramp) {
891 list_add_tail(&insn->static_call_node,
892 &file->static_call_list);
893 }
dcc914f4 894 continue;
ecf11ba4
JP		 895 } else if (reloc->sym->sec->idx) {
896 dest_sec = reloc->sym->sec;
897 dest_off = reloc->sym->sym.st_value +
898 arch_dest_reloc_offset(reloc->addend);
899 } else {
900 /* non-func asm code jumping to another file */
901 continue;
dcc914f4
JP		 902 }
903
904 insn->jump_dest = find_insn(file, dest_sec, dest_off);
905 if (!insn->jump_dest) {
906
907 /*
908 * This is a special case where an alt instruction
909 * jumps past the end of the section. These are
910 * handled later in handle_group_alt().
911 */
912 if (!strcmp(insn->sec->name, ".altinstr_replacement"))
913 continue;
914
915 WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
916 insn->sec, insn->offset, dest_sec->name,
917 dest_off);
918 return -1;
919 }
cd77849a
JP		 920
921 /*
54262aa2 922 * Cross-function jump.
cd77849a
JP		 923 */
924 if (insn->func && insn->jump_dest->func &&
54262aa2
PZ		 925 insn->func != insn->jump_dest->func) {
926
927 /*
928 * For GCC 8+, create parent/child links for any cold
929 * subfunctions. This is _mostly_ redundant with a
930 * similar initialization in read_symbols().
931 *
932 * If a function has aliases, we want the *first* such
933 * function in the symbol table to be the subfunction's
934 * parent. In that case we overwrite the
935 * initialization done in read_symbols().
936 *
937 * However this code can't completely replace the
938 * read_symbols() code because this doesn't detect the
939 * case where the parent function's only reference to a
e7c2bc37 940 * subfunction is through a jump table.
54262aa2 941 */
34ca59e1
JP		 942 if (!strstr(insn->func->name, ".cold") &&
943 strstr(insn->jump_dest->func->name, ".cold")) {
54262aa2
PZ		 944 insn->func->cfunc = insn->jump_dest->func;
945 insn->jump_dest->func->pfunc = insn->func;
946
947 } else if (insn->jump_dest->func->pfunc != insn->func->pfunc &&
948 insn->jump_dest->offset == insn->jump_dest->func->offset) {
949
ecf11ba4 950 /* internal sibling call (without reloc) */
54262aa2 951 insn->call_dest = insn->jump_dest->func;
5b06fd3b
PZ		 952 if (insn->call_dest->static_call_tramp) {
953 list_add_tail(&insn->static_call_node,
954 &file->static_call_list);
955 }
54262aa2 956 }
cd77849a 957 }
dcc914f4
JP		 958 }
959
960 return 0;
961}
962
8aa8eb2a
AC		 963static void remove_insn_ops(struct instruction *insn)
964{
965 struct stack_op *op, *tmp;
966
967 list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
968 list_del(&op->list);
969 free(op);
970 }
971}
972
2b232a22
JT		 973static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
974{
975 struct symbol *call_dest;
976
977 call_dest = find_func_by_offset(sec, offset);
978 if (!call_dest)
979 call_dest = find_symbol_by_offset(sec, offset);
980
981 return call_dest;
982}
983
dcc914f4
JP		 984/*
985 * Find the destination instructions for all calls.
986 */
987static int add_call_destinations(struct objtool_file *file)
988{
989 struct instruction *insn;
990 unsigned long dest_off;
f1974222 991 struct reloc *reloc;
dcc914f4
JP		 992
993 for_each_insn(file, insn) {
994 if (insn->type != INSN_CALL)
995 continue;
996
f1974222 997 reloc = find_reloc_by_dest_range(file->elf, insn->sec,
8b5fa6bc 998 insn->offset, insn->len);
f1974222 999 if (!reloc) {
bfb08f22 1000 dest_off = arch_jump_destination(insn);
2b232a22 1001 insn->call_dest = find_call_destination(insn->sec, dest_off);
a845c7cf 1002
7acfe531
JP		 1003 if (insn->ignore)
1004 continue;
1005
1006 if (!insn->call_dest) {
8aa8eb2a 1007 WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);
dcc914f4
JP		 1008 return -1;
1009 }
a845c7cf 1010
7acfe531
JP		 1011 if (insn->func && insn->call_dest->type != STT_FUNC) {
1012 WARN_FUNC("unsupported call to non-function",
1013 insn->sec, insn->offset);
1014 return -1;
1015 }
1016
f1974222
MH		 1017 } else if (reloc->sym->type == STT_SECTION) {
1018 dest_off = arch_dest_reloc_offset(reloc->addend);
2b232a22
JT		 1019 insn->call_dest = find_call_destination(reloc->sym->sec,
1020 dest_off);
7acfe531 1021 if (!insn->call_dest) {
bfb08f22 1022 WARN_FUNC("can't find call dest symbol at %s+0x%lx",
dcc914f4 1023 insn->sec, insn->offset,
f1974222 1024 reloc->sym->sec->name,
bfb08f22 1025 dest_off);
dcc914f4
JP		 1026 return -1;
1027 }
1028 } else
f1974222 1029 insn->call_dest = reloc->sym;
8aa8eb2a 1030
0f1441b4
PZ		 1031 /*
1032 * Many compilers cannot disable KCOV with a function attribute
1033 * so they need a little help, NOP out any KCOV calls from noinstr
1034 * text.
1035 */
1036 if (insn->sec->noinstr &&
1037 !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) {
d832c005
PZ		 1038 if (reloc) {
1039 reloc->type = R_NONE;
1040 elf_write_reloc(file->elf, reloc);
0f1441b4
PZ		 1041 }
1042
1043 elf_write_insn(file->elf, insn->sec,
1044 insn->offset, insn->len,
1045 arch_nop_insn(insn->len));
1046 insn->type = INSN_NOP;
1047 }
1048
99d00215
PZ		 1049 if (mcount && !strcmp(insn->call_dest->name, "__fentry__")) {
1050 if (reloc) {
1051 reloc->type = R_NONE;
1052 elf_write_reloc(file->elf, reloc);
1053 }
1054
1055 elf_write_insn(file->elf, insn->sec,
1056 insn->offset, insn->len,
1057 arch_nop_insn(insn->len));
1058
1059 insn->type = INSN_NOP;
1060
1061 list_add_tail(&insn->mcount_loc_node,
1062 &file->mcount_loc_list);
1063 }
1064
8aa8eb2a
AC		 1065 /*
1066 * Whatever stack impact regular CALLs have, should be undone
1067 * by the RETURN of the called function.
1068 *
1069 * Annotated intra-function calls retain the stack_ops but
1070 * are converted to JUMP, see read_intra_function_calls().
1071 */
1072 remove_insn_ops(insn);
dcc914f4
JP		 1073 }
1074
1075 return 0;
1076}
1077
1078/*
c9c324dc
JP		 1079 * The .alternatives section requires some extra special care over and above
1080 * other special sections because alternatives are patched in place.
dcc914f4
JP		 1081 */
1082static int handle_group_alt(struct objtool_file *file,
1083 struct special_alt *special_alt,
1084 struct instruction *orig_insn,
1085 struct instruction **new_insn)
1086{
c9c324dc 1087 struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL;
b23cc71c 1088 struct alt_group *orig_alt_group, *new_alt_group;
dcc914f4
JP		 1089 unsigned long dest_off;
1090
b23cc71c
JP		 1091
1092 orig_alt_group = malloc(sizeof(*orig_alt_group));
1093 if (!orig_alt_group) {
1094 WARN("malloc failed");
1095 return -1;
1096 }
c9c324dc
JP		 1097 orig_alt_group->cfi = calloc(special_alt->orig_len,
1098 sizeof(struct cfi_state *));
1099 if (!orig_alt_group->cfi) {
1100 WARN("calloc failed");
1101 return -1;
1102 }
1103
dcc914f4
JP		 1104 last_orig_insn = NULL;
1105 insn = orig_insn;
1106 sec_for_each_insn_from(file, insn) {
1107 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
1108 break;
1109
b23cc71c 1110 insn->alt_group = orig_alt_group;
dcc914f4
JP		 1111 last_orig_insn = insn;
1112 }
b23cc71c
JP		 1113 orig_alt_group->orig_group = NULL;
1114 orig_alt_group->first_insn = orig_insn;
1115 orig_alt_group->last_insn = last_orig_insn;
dcc914f4 1116
17bc3391 1117
c9c324dc
JP		 1118 new_alt_group = malloc(sizeof(*new_alt_group));
1119 if (!new_alt_group) {
1120 WARN("malloc failed");
1121 return -1;
dcc914f4 1122 }
dcc914f4 1123
c9c324dc
JP		 1124 if (special_alt->new_len < special_alt->orig_len) {
1125 /*
1126 * Insert a fake nop at the end to make the replacement
1127 * alt_group the same size as the original. This is needed to
1128 * allow propagate_alt_cfi() to do its magic. When the last
1129 * instruction affects the stack, the instruction after it (the
1130 * nop) will propagate the new state to the shared CFI array.
1131 */
1132 nop = malloc(sizeof(*nop));
1133 if (!nop) {
1134 WARN("malloc failed");
17bc3391
JP		 1135 return -1;
1136 }
c9c324dc
JP		 1137 memset(nop, 0, sizeof(*nop));
1138 INIT_LIST_HEAD(&nop->alts);
1139 INIT_LIST_HEAD(&nop->stack_ops);
1140 init_cfi_state(&nop->cfi);
1141
1142 nop->sec = special_alt->new_sec;
1143 nop->offset = special_alt->new_off + special_alt->new_len;
1144 nop->len = special_alt->orig_len - special_alt->new_len;
1145 nop->type = INSN_NOP;
1146 nop->func = orig_insn->func;
1147 nop->alt_group = new_alt_group;
1148 nop->ignore = orig_insn->ignore_alts;
dcc914f4 1149 }
17bc3391 1150
c9c324dc
JP		 1151 if (!special_alt->new_len) {
1152 *new_insn = nop;
1153 goto end;
dcc914f4
JP		 1154 }
1155
dcc914f4
JP		 1156 insn = *new_insn;
1157 sec_for_each_insn_from(file, insn) {
45245f51
JT		 1158 struct reloc *alt_reloc;
1159
dcc914f4
JP		 1160 if (insn->offset >= special_alt->new_off + special_alt->new_len)
1161 break;
1162
1163 last_new_insn = insn;
1164
a845c7cf 1165 insn->ignore = orig_insn->ignore_alts;
a4d09dde 1166 insn->func = orig_insn->func;
b23cc71c 1167 insn->alt_group = new_alt_group;
a845c7cf 1168
dc419723
JP		 1169 /*
1170 * Since alternative replacement code is copy/pasted by the
1171 * kernel after applying relocations, generally such code can't
1172 * have relative-address relocation references to outside the
1173 * .altinstr_replacement section, unless the arch's
1174 * alternatives code can adjust the relative offsets
1175 * accordingly.
dc419723 1176 */
45245f51
JT		 1177 alt_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
1178 insn->offset, insn->len);
1179 if (alt_reloc &&
1180 !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
dc419723
JP		 1181
1182 WARN_FUNC("unsupported relocation in alternatives section",
1183 insn->sec, insn->offset);
1184 return -1;
1185 }
1186
a2296140 1187 if (!is_static_jump(insn))
dcc914f4
JP		 1188 continue;
1189
1190 if (!insn->immediate)
1191 continue;
1192
bfb08f22 1193 dest_off = arch_jump_destination(insn);
c9c324dc
JP		 1194 if (dest_off == special_alt->new_off + special_alt->new_len)
1195 insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
dcc914f4
JP		 1196
1197 if (!insn->jump_dest) {
1198 WARN_FUNC("can't find alternative jump destination",
1199 insn->sec, insn->offset);
1200 return -1;
1201 }
1202 }
1203
1204 if (!last_new_insn) {
1205 WARN_FUNC("can't find last new alternative instruction",
1206 special_alt->new_sec, special_alt->new_off);
1207 return -1;
1208 }
1209
c9c324dc
JP		 1210 if (nop)
1211 list_add(&nop->list, &last_new_insn->list);
1212end:
b23cc71c
JP		 1213 new_alt_group->orig_group = orig_alt_group;
1214 new_alt_group->first_insn = *new_insn;
c9c324dc
JP		 1215 new_alt_group->last_insn = nop ? : last_new_insn;
1216 new_alt_group->cfi = orig_alt_group->cfi;
dcc914f4
JP		 1217 return 0;
1218}
1219
1220/*
1221 * A jump table entry can either convert a nop to a jump or a jump to a nop.
1222 * If the original instruction is a jump, make the alt entry an effective nop
1223 * by just skipping the original instruction.
1224 */
1225static int handle_jump_alt(struct objtool_file *file,
1226 struct special_alt *special_alt,
1227 struct instruction *orig_insn,
1228 struct instruction **new_insn)
1229{
1230 if (orig_insn->type == INSN_NOP)
1231 return 0;
1232
1233 if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) {
1234 WARN_FUNC("unsupported instruction at jump label",
1235 orig_insn->sec, orig_insn->offset);
1236 return -1;
1237 }
1238
1239 *new_insn = list_next_entry(orig_insn, list);
1240 return 0;
1241}
1242
1243/*
1244 * Read all the special sections which have alternate instructions which can be
1245 * patched in or redirected to at runtime. Each instruction having alternate
1246 * instruction(s) has them added to its insn->alts list, which will be
1247 * traversed in validate_branch().
1248 */
1249static int add_special_section_alts(struct objtool_file *file)
1250{
1251 struct list_head special_alts;
1252 struct instruction *orig_insn, *new_insn;
1253 struct special_alt *special_alt, *tmp;
1254 struct alternative *alt;
1255 int ret;
1256
1257 ret = special_get_alts(file->elf, &special_alts);
1258 if (ret)
1259 return ret;
1260
1261 list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
dcc914f4
JP		 1262
1263 orig_insn = find_insn(file, special_alt->orig_sec,
1264 special_alt->orig_off);
1265 if (!orig_insn) {
1266 WARN_FUNC("special: can't find orig instruction",
1267 special_alt->orig_sec, special_alt->orig_off);
1268 ret = -1;
1269 goto out;
1270 }
1271
1272 new_insn = NULL;
1273 if (!special_alt->group || special_alt->new_len) {
1274 new_insn = find_insn(file, special_alt->new_sec,
1275 special_alt->new_off);
1276 if (!new_insn) {
1277 WARN_FUNC("special: can't find new instruction",
1278 special_alt->new_sec,
1279 special_alt->new_off);
1280 ret = -1;
1281 goto out;
1282 }
1283 }
1284
1285 if (special_alt->group) {
7170cf47
JT		 1286 if (!special_alt->orig_len) {
1287 WARN_FUNC("empty alternative entry",
1288 orig_insn->sec, orig_insn->offset);
1289 continue;
1290 }
1291
dcc914f4
JP		 1292 ret = handle_group_alt(file, special_alt, orig_insn,
1293 &new_insn);
1294 if (ret)
1295 goto out;
1296 } else if (special_alt->jump_or_nop) {
1297 ret = handle_jump_alt(file, special_alt, orig_insn,
1298 &new_insn);
1299 if (ret)
1300 goto out;
1301 }
1302
258c7605
JP		 1303 alt = malloc(sizeof(*alt));
1304 if (!alt) {
1305 WARN("malloc failed");
1306 ret = -1;
1307 goto out;
1308 }
1309
dcc914f4 1310 alt->insn = new_insn;
764eef4b 1311 alt->skip_orig = special_alt->skip_orig;
ea24213d 1312 orig_insn->ignore_alts |= special_alt->skip_alt;
dcc914f4
JP		 1313 list_add_tail(&alt->list, &orig_insn->alts);
1314
1315 list_del(&special_alt->list);
1316 free(special_alt);
1317 }
1318
1319out:
1320 return ret;
1321}
1322
e7c2bc37 1323static int add_jump_table(struct objtool_file *file, struct instruction *insn,
f1974222 1324 struct reloc *table)
dcc914f4 1325{
f1974222 1326 struct reloc *reloc = table;
e7c2bc37 1327 struct instruction *dest_insn;
dcc914f4 1328 struct alternative *alt;
fd35c88b
JP		 1329 struct symbol *pfunc = insn->func->pfunc;
1330 unsigned int prev_offset = 0;
dcc914f4 1331
e7c2bc37 1332 /*
f1974222 1333 * Each @reloc is a switch table relocation which points to the target
e7c2bc37
JP		 1334 * instruction.
1335 */
f1974222 1336 list_for_each_entry_from(reloc, &table->sec->reloc_list, list) {
bd98c813
JH		 1337
1338 /* Check for the end of the table: */
f1974222 1339 if (reloc != table && reloc->jump_table_start)
dcc914f4
JP		 1340 break;
1341
e7c2bc37 1342 /* Make sure the table entries are consecutive: */
f1974222 1343 if (prev_offset && reloc->offset != prev_offset + 8)
fd35c88b
JP		 1344 break;
1345
1346 /* Detect function pointers from contiguous objects: */
f1974222
MH		 1347 if (reloc->sym->sec == pfunc->sec &&
1348 reloc->addend == pfunc->offset)
fd35c88b
JP		 1349 break;
1350
f1974222 1351 dest_insn = find_insn(file, reloc->sym->sec, reloc->addend);
e7c2bc37 1352 if (!dest_insn)
dcc914f4
JP		 1353 break;
1354
e7c2bc37 1355 /* Make sure the destination is in the same function: */
e65050b9 1356 if (!dest_insn->func || dest_insn->func->pfunc != pfunc)
13810435 1357 break;
dcc914f4
JP		 1358
1359 alt = malloc(sizeof(*alt));
1360 if (!alt) {
1361 WARN("malloc failed");
1362 return -1;
1363 }
1364
e7c2bc37 1365 alt->insn = dest_insn;
dcc914f4 1366 list_add_tail(&alt->list, &insn->alts);
f1974222 1367 prev_offset = reloc->offset;
fd35c88b
JP		 1368 }
1369
1370 if (!prev_offset) {
1371 WARN_FUNC("can't find switch jump table",
1372 insn->sec, insn->offset);
1373 return -1;
dcc914f4
JP		 1374 }
1375
1376 return 0;
1377}
1378
1379/*
d871f7b5
RG		 1380 * find_jump_table() - Given a dynamic jump, find the switch jump table
1381 * associated with it.
dcc914f4 1382 */
f1974222 1383static struct reloc *find_jump_table(struct objtool_file *file,
dcc914f4
JP		 1384 struct symbol *func,
1385 struct instruction *insn)
1386{
d871f7b5 1387 struct reloc *table_reloc;
113d4bc9 1388 struct instruction *dest_insn, *orig_insn = insn;
dcc914f4 1389
99ce7962
PZ		 1390 /*
1391 * Backward search using the @first_jump_src links, these help avoid
1392 * much of the 'in between' code. Which avoids us getting confused by
1393 * it.
1394 */
7dec80cc 1395 for (;
1119d265
JP		 1396 insn && insn->func && insn->func->pfunc == func;
1397 insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
99ce7962 1398
7dec80cc 1399 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
dcc914f4
JP		 1400 break;
1401
1402 /* allow small jumps within the range */
1403 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
1404 insn->jump_dest &&
1405 (insn->jump_dest->offset <= insn->offset ||
1406 insn->jump_dest->offset > orig_insn->offset))
1407 break;
1408
d871f7b5 1409 table_reloc = arch_find_switch_table(file, insn);
f1974222 1410 if (!table_reloc)
e7c2bc37 1411 continue;
f1974222 1412 dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
113d4bc9
JP		 1413 if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
1414 continue;
7dec80cc 1415
f1974222 1416 return table_reloc;
dcc914f4
JP		 1417 }
1418
1419 return NULL;
1420}
1421
bd98c813
JH		 1422/*
1423 * First pass: Mark the head of each jump table so that in the next pass,
1424 * we know when a given jump table ends and the next one starts.
1425 */
1426static void mark_func_jump_tables(struct objtool_file *file,
1427 struct symbol *func)
dcc914f4 1428{
bd98c813 1429 struct instruction *insn, *last = NULL;
f1974222 1430 struct reloc *reloc;
dcc914f4 1431
f0f70adb 1432 func_for_each_insn(file, func, insn) {
99ce7962
PZ		 1433 if (!last)
1434 last = insn;
1435
1436 /*
1437 * Store back-pointers for unconditional forward jumps such
e7c2bc37 1438 * that find_jump_table() can back-track using those and
99ce7962
PZ		 1439 * avoid some potentially confusing code.
1440 */
1441 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
1442 insn->offset > last->offset &&
1443 insn->jump_dest->offset > insn->offset &&
1444 !insn->jump_dest->first_jump_src) {
1445
1446 insn->jump_dest->first_jump_src = insn;
1447 last = insn->jump_dest;
1448 }
1449
dcc914f4
JP		 1450 if (insn->type != INSN_JUMP_DYNAMIC)
1451 continue;
1452
f1974222
MH		 1453 reloc = find_jump_table(file, func, insn);
1454 if (reloc) {
1455 reloc->jump_table_start = true;
1456 insn->jump_table = reloc;
dcc914f4 1457 }
dcc914f4 1458 }
bd98c813
JH		 1459}
1460
1461static int add_func_jump_tables(struct objtool_file *file,
1462 struct symbol *func)
1463{
1464 struct instruction *insn;
1465 int ret;
1466
f0f70adb 1467 func_for_each_insn(file, func, insn) {
bd98c813
JH		 1468 if (!insn->jump_table)
1469 continue;
dcc914f4 1470
bd98c813 1471 ret = add_jump_table(file, insn, insn->jump_table);
dcc914f4
JP		 1472 if (ret)
1473 return ret;
1474 }
1475
1476 return 0;
1477}
1478
1479/*
1480 * For some switch statements, gcc generates a jump table in the .rodata
1481 * section which contains a list of addresses within the function to jump to.
1482 * This finds these jump tables and adds them to the insn->alts lists.
1483 */
e7c2bc37 1484static int add_jump_table_alts(struct objtool_file *file)
dcc914f4
JP		 1485{
1486 struct section *sec;
1487 struct symbol *func;
1488 int ret;
1489
4a60aa05 1490 if (!file->rodata)
dcc914f4
JP		 1491 return 0;
1492
baa41469 1493 for_each_sec(file, sec) {
dcc914f4
JP		 1494 list_for_each_entry(func, &sec->symbol_list, list) {
1495 if (func->type != STT_FUNC)
1496 continue;
1497
bd98c813 1498 mark_func_jump_tables(file, func);
e7c2bc37 1499 ret = add_func_jump_tables(file, func);
dcc914f4
JP		 1500 if (ret)
1501 return ret;
1502 }
1503 }
1504
1505 return 0;
1506}
1507
b735bd3e
JP		 1508static void set_func_state(struct cfi_state *state)
1509{
1510 state->cfa = initial_func_cfi.cfa;
1511 memcpy(&state->regs, &initial_func_cfi.regs,
1512 CFI_NUM_REGS * sizeof(struct cfi_reg));
1513 state->stack_size = initial_func_cfi.cfa.offset;
1514}
1515
39358a03
JP		 1516static int read_unwind_hints(struct objtool_file *file)
1517{
f1974222
MH		 1518 struct section *sec, *relocsec;
1519 struct reloc *reloc;
39358a03
JP		 1520 struct unwind_hint *hint;
1521 struct instruction *insn;
39358a03
JP		 1522 int i;
1523
1524 sec = find_section_by_name(file->elf, ".discard.unwind_hints");
1525 if (!sec)
1526 return 0;
1527
f1974222
MH		 1528 relocsec = sec->reloc;
1529 if (!relocsec) {
39358a03
JP		 1530 WARN("missing .rela.discard.unwind_hints section");
1531 return -1;
1532 }
1533
1534 if (sec->len % sizeof(struct unwind_hint)) {
1535 WARN("struct unwind_hint size mismatch");
1536 return -1;
1537 }
1538
1539 file->hints = true;
1540
1541 for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) {
1542 hint = (struct unwind_hint *)sec->data->d_buf + i;
1543
f1974222
MH		 1544 reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
1545 if (!reloc) {
1546 WARN("can't find reloc for unwind_hints[%d]", i);
39358a03
JP		 1547 return -1;
1548 }
1549
f1974222 1550 insn = find_insn(file, reloc->sym->sec, reloc->addend);
39358a03
JP		 1551 if (!insn) {
1552 WARN("can't find insn for unwind_hints[%d]", i);
1553 return -1;
1554 }
1555
b735bd3e 1556 insn->hint = true;
39358a03 1557
b735bd3e
JP		 1558 if (hint->type == UNWIND_HINT_TYPE_FUNC) {
1559 set_func_state(&insn->cfi);
39358a03
JP		 1560 continue;
1561 }
1562
edea9e6b 1563 if (arch_decode_hint_reg(insn, hint->sp_reg)) {
39358a03
JP		 1564 WARN_FUNC("unsupported unwind_hint sp base reg %d",
1565 insn->sec, insn->offset, hint->sp_reg);
1566 return -1;
1567 }
1568
b735bd3e 1569 insn->cfi.cfa.offset = bswap_if_needed(hint->sp_offset);
e7c0219b
PZ		 1570 insn->cfi.type = hint->type;
1571 insn->cfi.end = hint->end;
39358a03
JP		 1572 }
1573
1574 return 0;
1575}
1576
b5bc2231
PZ		 1577static int read_retpoline_hints(struct objtool_file *file)
1578{
63474dc4 1579 struct section *sec;
b5bc2231 1580 struct instruction *insn;
f1974222 1581 struct reloc *reloc;
b5bc2231 1582
63474dc4 1583 sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
b5bc2231
PZ		 1584 if (!sec)
1585 return 0;
1586
f1974222
MH		 1587 list_for_each_entry(reloc, &sec->reloc_list, list) {
1588 if (reloc->sym->type != STT_SECTION) {
63474dc4 1589 WARN("unexpected relocation symbol type in %s", sec->name);
b5bc2231
PZ		 1590 return -1;
1591 }
1592
f1974222 1593 insn = find_insn(file, reloc->sym->sec, reloc->addend);
b5bc2231 1594 if (!insn) {
63474dc4 1595 WARN("bad .discard.retpoline_safe entry");
b5bc2231
PZ		 1596 return -1;
1597 }
1598
1599 if (insn->type != INSN_JUMP_DYNAMIC &&
1600 insn->type != INSN_CALL_DYNAMIC) {
63474dc4 1601 WARN_FUNC("retpoline_safe hint not an indirect jump/call",
b5bc2231
PZ		 1602 insn->sec, insn->offset);
1603 return -1;
1604 }
1605
1606 insn->retpoline_safe = true;
1607 }
1608
1609 return 0;
1610}
1611
c4a33939
PZ		 1612static int read_instr_hints(struct objtool_file *file)
1613{
1614 struct section *sec;
1615 struct instruction *insn;
f1974222 1616 struct reloc *reloc;
c4a33939
PZ		 1617
1618 sec = find_section_by_name(file->elf, ".rela.discard.instr_end");
1619 if (!sec)
1620 return 0;
1621
f1974222
MH		 1622 list_for_each_entry(reloc, &sec->reloc_list, list) {
1623 if (reloc->sym->type != STT_SECTION) {
c4a33939
PZ		 1624 WARN("unexpected relocation symbol type in %s", sec->name);
1625 return -1;
1626 }
1627
f1974222 1628 insn = find_insn(file, reloc->sym->sec, reloc->addend);
c4a33939
PZ		 1629 if (!insn) {
1630 WARN("bad .discard.instr_end entry");
1631 return -1;
1632 }
1633
1634 insn->instr--;
1635 }
1636
1637 sec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
1638 if (!sec)
1639 return 0;
1640
f1974222
MH		 1641 list_for_each_entry(reloc, &sec->reloc_list, list) {
1642 if (reloc->sym->type != STT_SECTION) {
c4a33939
PZ		 1643 WARN("unexpected relocation symbol type in %s", sec->name);
1644 return -1;
1645 }
1646
f1974222 1647 insn = find_insn(file, reloc->sym->sec, reloc->addend);
c4a33939
PZ		 1648 if (!insn) {
1649 WARN("bad .discard.instr_begin entry");
1650 return -1;
1651 }
1652
1653 insn->instr++;
1654 }
1655
1656 return 0;
1657}
1658
8aa8eb2a
AC		 1659static int read_intra_function_calls(struct objtool_file *file)
1660{
1661 struct instruction *insn;
1662 struct section *sec;
f1974222 1663 struct reloc *reloc;
8aa8eb2a
AC		 1664
1665 sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
1666 if (!sec)
1667 return 0;
1668
f1974222 1669 list_for_each_entry(reloc, &sec->reloc_list, list) {
8aa8eb2a
AC		 1670 unsigned long dest_off;
1671
f1974222 1672 if (reloc->sym->type != STT_SECTION) {
8aa8eb2a
AC		 1673 WARN("unexpected relocation symbol type in %s",
1674 sec->name);
1675 return -1;
1676 }
1677
f1974222 1678 insn = find_insn(file, reloc->sym->sec, reloc->addend);
8aa8eb2a
AC		 1679 if (!insn) {
1680 WARN("bad .discard.intra_function_call entry");
1681 return -1;
1682 }
1683
1684 if (insn->type != INSN_CALL) {
1685 WARN_FUNC("intra_function_call not a direct call",
1686 insn->sec, insn->offset);
1687 return -1;
1688 }
1689
1690 /*
1691 * Treat intra-function CALLs as JMPs, but with a stack_op.
1692 * See add_call_destinations(), which strips stack_ops from
1693 * normal CALLs.
1694 */
1695 insn->type = INSN_JUMP_UNCONDITIONAL;
1696
1697 dest_off = insn->offset + insn->len + insn->immediate;
1698 insn->jump_dest = find_insn(file, insn->sec, dest_off);
1699 if (!insn->jump_dest) {
1700 WARN_FUNC("can't find call dest at %s+0x%lx",
1701 insn->sec, insn->offset,
1702 insn->sec->name, dest_off);
1703 return -1;
1704 }
1705 }
1706
1707 return 0;
1708}
1709
1e7e4788
JP		 1710static int read_static_call_tramps(struct objtool_file *file)
1711{
1712 struct section *sec;
1713 struct symbol *func;
1714
1715 for_each_sec(file, sec) {
1716 list_for_each_entry(func, &sec->symbol_list, list) {
1717 if (func->bind == STB_GLOBAL &&
1718 !strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
1719 strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
1720 func->static_call_tramp = true;
1721 }
1722 }
1723
1724 return 0;
1725}
1726
4a60aa05
AX		 1727static void mark_rodata(struct objtool_file *file)
1728{
1729 struct section *sec;
1730 bool found = false;
1731
1732 /*
87b512de
JP		 1733 * Search for the following rodata sections, each of which can
1734 * potentially contain jump tables:
1735 *
1736 * - .rodata: can contain GCC switch tables
1737 * - .rodata.<func>: same, if -fdata-sections is being used
1738 * - .rodata..c_jump_table: contains C annotated jump tables
1739 *
1740 * .rodata.str1.* sections are ignored; they don't contain jump tables.
4a60aa05
AX		 1741 */
1742 for_each_sec(file, sec) {
1ee44470
MS		 1743 if (!strncmp(sec->name, ".rodata", 7) &&
1744 !strstr(sec->name, ".str1.")) {
4a60aa05
AX		 1745 sec->rodata = true;
1746 found = true;
1747 }
1748 }
1749
1750 file->rodata = found;
1751}
1752
dcc914f4
JP		 1753static int decode_sections(struct objtool_file *file)
1754{
1755 int ret;
1756
4a60aa05
AX		 1757 mark_rodata(file);
1758
dcc914f4
JP		 1759 ret = decode_instructions(file);
1760 if (ret)
1761 return ret;
1762
1763 ret = add_dead_ends(file);
1764 if (ret)
1765 return ret;
1766
1767 add_ignores(file);
ea24213d 1768 add_uaccess_safe(file);
dcc914f4 1769
ff05ab23 1770 ret = add_ignore_alternatives(file);
258c7605
JP		 1771 if (ret)
1772 return ret;
1773
5b06fd3b
PZ		 1774 ret = read_static_call_tramps(file);
1775 if (ret)
1776 return ret;
1777
dcc914f4
JP		 1778 ret = add_jump_destinations(file);
1779 if (ret)
1780 return ret;
1781
a845c7cf 1782 ret = add_special_section_alts(file);
dcc914f4
JP		 1783 if (ret)
1784 return ret;
1785
8aa8eb2a
AC		 1786 ret = read_intra_function_calls(file);
1787 if (ret)
1788 return ret;
1789
a845c7cf 1790 ret = add_call_destinations(file);
dcc914f4
JP		 1791 if (ret)
1792 return ret;
1793
e7c2bc37 1794 ret = add_jump_table_alts(file);
dcc914f4
JP		 1795 if (ret)
1796 return ret;
1797
39358a03
JP		 1798 ret = read_unwind_hints(file);
1799 if (ret)
1800 return ret;
1801
b5bc2231
PZ		 1802 ret = read_retpoline_hints(file);
1803 if (ret)
1804 return ret;
1805
c4a33939
PZ		 1806 ret = read_instr_hints(file);
1807 if (ret)
1808 return ret;
1809
dcc914f4
JP		 1810 return 0;
1811}
1812
1813static bool is_fentry_call(struct instruction *insn)
1814{
87cf61fe 1815 if (insn->type == INSN_CALL && insn->call_dest &&
dcc914f4
JP		 1816 insn->call_dest->type == STT_NOTYPE &&
1817 !strcmp(insn->call_dest->name, "__fentry__"))
1818 return true;
1819
1820 return false;
1821}
1822
e25eea89 1823static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
dcc914f4 1824{
e7c0219b 1825 struct cfi_state *cfi = &state->cfi;
baa41469
JP		 1826 int i;
1827
e7c0219b 1828 if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
e25eea89
PZ		 1829 return true;
1830
b735bd3e 1831 if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
baa41469
JP		 1832 return true;
1833
b735bd3e 1834 if (cfi->stack_size != initial_func_cfi.cfa.offset)
e25eea89
PZ		 1835 return true;
1836
1837 for (i = 0; i < CFI_NUM_REGS; i++) {
e7c0219b
PZ		 1838 if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
1839 cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
baa41469 1840 return true;
e25eea89 1841 }
baa41469
JP		 1842
1843 return false;
1844}
1845
fb084fde
JT		 1846static bool check_reg_frame_pos(const struct cfi_reg *reg,
1847 int expected_offset)
1848{
1849 return reg->base == CFI_CFA &&
1850 reg->offset == expected_offset;
1851}
1852
baa41469
JP		 1853static bool has_valid_stack_frame(struct insn_state *state)
1854{
e7c0219b
PZ		 1855 struct cfi_state *cfi = &state->cfi;
1856
fb084fde
JT		 1857 if (cfi->cfa.base == CFI_BP &&
1858 check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
1859 check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
baa41469
JP		 1860 return true;
1861
e7c0219b 1862 if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
baa41469
JP		 1863 return true;
1864
1865 return false;
dcc914f4
JP		 1866}
1867
e7c0219b
PZ		 1868static int update_cfi_state_regs(struct instruction *insn,
1869 struct cfi_state *cfi,
65ea47dc 1870 struct stack_op *op)
627fce14 1871{
e7c0219b 1872 struct cfi_reg *cfa = &cfi->cfa;
627fce14 1873
d8dd25a4 1874 if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
627fce14
JP		 1875 return 0;
1876
1877 /* push */
ea24213d 1878 if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
627fce14
JP		 1879 cfa->offset += 8;
1880
1881 /* pop */
ea24213d 1882 if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
627fce14
JP		 1883 cfa->offset -= 8;
1884
1885 /* add immediate to sp */
1886 if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
1887 op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
1888 cfa->offset -= op->src.offset;
1889
1890 return 0;
1891}
1892
e7c0219b 1893static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
dcc914f4 1894{
bf4d1a83 1895 if (arch_callee_saved_reg(reg) &&
e7c0219b
PZ		 1896 cfi->regs[reg].base == CFI_UNDEFINED) {
1897 cfi->regs[reg].base = base;
1898 cfi->regs[reg].offset = offset;
baa41469 1899 }
dcc914f4
JP		 1900}
1901
e7c0219b 1902static void restore_reg(struct cfi_state *cfi, unsigned char reg)
dcc914f4 1903{
e7c0219b
PZ		 1904 cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
1905 cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
baa41469
JP		 1906}
1907
1908/*
1909 * A note about DRAP stack alignment:
1910 *
1911 * GCC has the concept of a DRAP register, which is used to help keep track of
1912 * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
1913 * register. The typical DRAP pattern is:
1914 *
1915 * 4c 8d 54 24 08 lea 0x8(%rsp),%r10
1916 * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
1917 * 41 ff 72 f8 pushq -0x8(%r10)
1918 * 55 push %rbp
1919 * 48 89 e5 mov %rsp,%rbp
1920 * (more pushes)
1921 * 41 52 push %r10
1922 * ...
1923 * 41 5a pop %r10
1924 * (more pops)
1925 * 5d pop %rbp
1926 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1927 * c3 retq
1928 *
1929 * There are some variations in the epilogues, like:
1930 *
1931 * 5b pop %rbx
1932 * 41 5a pop %r10
1933 * 41 5c pop %r12
1934 * 41 5d pop %r13
1935 * 41 5e pop %r14
1936 * c9 leaveq
1937 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1938 * c3 retq
1939 *
1940 * and:
1941 *
1942 * 4c 8b 55 e8 mov -0x18(%rbp),%r10
1943 * 48 8b 5d e0 mov -0x20(%rbp),%rbx
1944 * 4c 8b 65 f0 mov -0x10(%rbp),%r12
1945 * 4c 8b 6d f8 mov -0x8(%rbp),%r13
1946 * c9 leaveq
1947 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1948 * c3 retq
1949 *
1950 * Sometimes r13 is used as the DRAP register, in which case it's saved and
1951 * restored beforehand:
1952 *
1953 * 41 55 push %r13
1954 * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
1955 * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
1956 * ...
1957 * 49 8d 65 f0 lea -0x10(%r13),%rsp
1958 * 41 5d pop %r13
1959 * c3 retq
1960 */
e7c0219b 1961static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
65ea47dc 1962 struct stack_op *op)
baa41469 1963{
e7c0219b
PZ		 1964 struct cfi_reg *cfa = &cfi->cfa;
1965 struct cfi_reg *regs = cfi->regs;
baa41469
JP		 1966
1967 /* stack operations don't make sense with an undefined CFA */
1968 if (cfa->base == CFI_UNDEFINED) {
1969 if (insn->func) {
1970 WARN_FUNC("undefined stack state", insn->sec, insn->offset);
1971 return -1;
1972 }
1973 return 0;
1974 }
1975
ee819aed
JT		 1976 if (cfi->type == UNWIND_HINT_TYPE_REGS ||
1977 cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
e7c0219b 1978 return update_cfi_state_regs(insn, cfi, op);
627fce14 1979
baa41469
JP		 1980 switch (op->dest.type) {
1981
1982 case OP_DEST_REG:
1983 switch (op->src.type) {
1984
1985 case OP_SRC_REG:
0d0970ee
JP		 1986 if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
1987 cfa->base == CFI_SP &&
fb084fde 1988 check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {
0d0970ee
JP		 1989
1990 /* mov %rsp, %rbp */
1991 cfa->base = op->dest.reg;
e7c0219b 1992 cfi->bp_scratch = false;
0d0970ee 1993 }
dd88a0a0 1994
0d0970ee 1995 else if (op->src.reg == CFI_SP &&
e7c0219b 1996 op->dest.reg == CFI_BP && cfi->drap) {
dd88a0a0 1997
0d0970ee
JP		 1998 /* drap: mov %rsp, %rbp */
1999 regs[CFI_BP].base = CFI_BP;
e7c0219b
PZ		 2000 regs[CFI_BP].offset = -cfi->stack_size;
2001 cfi->bp_scratch = false;
0d0970ee 2002 }
dd88a0a0 2003
0d0970ee
JP		 2004 else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2005
2006 /*
2007 * mov %rsp, %reg
2008 *
2009 * This is needed for the rare case where GCC
2010 * does:
2011 *
2012 * mov %rsp, %rax
2013 * ...
2014 * mov %rax, %rsp
2015 */
e7c0219b
PZ		 2016 cfi->vals[op->dest.reg].base = CFI_CFA;
2017 cfi->vals[op->dest.reg].offset = -cfi->stack_size;
dd88a0a0
JP		 2018 }
2019
3c1f0583
JP		 2020 else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
2021 cfa->base == CFI_BP) {
2022
2023 /*
2024 * mov %rbp, %rsp
2025 *
2026 * Restore the original stack pointer (Clang).
2027 */
e7c0219b 2028 cfi->stack_size = -cfi->regs[CFI_BP].offset;
3c1f0583
JP		 2029 }
2030
dd88a0a0
JP		 2031 else if (op->dest.reg == cfa->base) {
2032
2033 /* mov %reg, %rsp */
2034 if (cfa->base == CFI_SP &&
e7c0219b 2035 cfi->vals[op->src.reg].base == CFI_CFA) {
dd88a0a0
JP		 2036
2037 /*
2038 * This is needed for the rare case
2039 * where GCC does something dumb like:
2040 *
2041 * lea 0x8(%rsp), %rcx
2042 * ...
2043 * mov %rcx, %rsp
2044 */
e7c0219b
PZ		 2045 cfa->offset = -cfi->vals[op->src.reg].offset;
2046 cfi->stack_size = cfa->offset;
dd88a0a0 2047
aafeb14e
PZ		 2048 } else if (cfa->base == CFI_SP &&
2049 cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2050 cfi->vals[op->src.reg].offset == cfa->offset) {
2051
2052 /*
2053 * Stack swizzle:
2054 *
2055 * 1: mov %rsp, (%[tos])
2056 * 2: mov %[tos], %rsp
2057 * ...
2058 * 3: pop %rsp
2059 *
2060 * Where:
2061 *
2062 * 1 - places a pointer to the previous
2063 * stack at the Top-of-Stack of the
2064 * new stack.
2065 *
2066 * 2 - switches to the new stack.
2067 *
2068 * 3 - pops the Top-of-Stack to restore
2069 * the original stack.
2070 *
2071 * Note: we set base to SP_INDIRECT
2072 * here and preserve offset. Therefore
2073 * when the unwinder reaches ToS it
2074 * will dereference SP and then add the
2075 * offset to find the next frame, IOW:
2076 * (%rsp) + offset.
2077 */
2078 cfa->base = CFI_SP_INDIRECT;
2079
dd88a0a0
JP		 2080 } else {
2081 cfa->base = CFI_UNDEFINED;
2082 cfa->offset = 0;
2083 }
baa41469
JP		 2084 }
2085
724c8a23
PZ		 2086 else if (op->dest.reg == CFI_SP &&
2087 cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2088 cfi->vals[op->src.reg].offset == cfa->offset) {
2089
2090 /*
2091 * The same stack swizzle case 2) as above. But
2092 * because we can't change cfa->base, case 3)
2093 * will become a regular POP. Pretend we're a
2094 * PUSH so things don't go unbalanced.
2095 */
2096 cfi->stack_size += 8;
2097 }
2098
2099
baa41469
JP		 2100 break;
2101
2102 case OP_SRC_ADD:
2103 if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
2104
2105 /* add imm, %rsp */
e7c0219b 2106 cfi->stack_size -= op->src.offset;
baa41469
JP		 2107 if (cfa->base == CFI_SP)
2108 cfa->offset -= op->src.offset;
2109 break;
2110 }
2111
2112 if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
2113
2114 /* lea disp(%rbp), %rsp */
e7c0219b 2115 cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
baa41469
JP		 2116 break;
2117 }
2118
468af56a
JT		 2119 if (!cfi->drap && op->src.reg == CFI_SP &&
2120 op->dest.reg == CFI_BP && cfa->base == CFI_SP &&
2121 check_reg_frame_pos(&regs[CFI_BP], -cfa->offset + op->src.offset)) {
2122
2123 /* lea disp(%rsp), %rbp */
2124 cfa->base = CFI_BP;
2125 cfa->offset -= op->src.offset;
2126 cfi->bp_scratch = false;
2127 break;
2128 }
2129
dd88a0a0 2130 if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
baa41469
JP		 2131
2132 /* drap: lea disp(%rsp), %drap */
e7c0219b 2133 cfi->drap_reg = op->dest.reg;
dd88a0a0
JP		 2134
2135 /*
2136 * lea disp(%rsp), %reg
2137 *
2138 * This is needed for the rare case where GCC
2139 * does something dumb like:
2140 *
2141 * lea 0x8(%rsp), %rcx
2142 * ...
2143 * mov %rcx, %rsp
2144 */
e7c0219b
PZ		 2145 cfi->vals[op->dest.reg].base = CFI_CFA;
2146 cfi->vals[op->dest.reg].offset = \
2147 -cfi->stack_size + op->src.offset;
dd88a0a0 2148
baa41469
JP		 2149 break;
2150 }
2151
e7c0219b
PZ		 2152 if (cfi->drap && op->dest.reg == CFI_SP &&
2153 op->src.reg == cfi->drap_reg) {
baa41469
JP		 2154
2155 /* drap: lea disp(%drap), %rsp */
2156 cfa->base = CFI_SP;
e7c0219b
PZ		 2157 cfa->offset = cfi->stack_size = -op->src.offset;
2158 cfi->drap_reg = CFI_UNDEFINED;
2159 cfi->drap = false;
baa41469
JP		 2160 break;
2161 }
2162
e7c0219b 2163 if (op->dest.reg == cfi->cfa.base) {
baa41469
JP		 2164 WARN_FUNC("unsupported stack register modification",
2165 insn->sec, insn->offset);
2166 return -1;
2167 }
2168
2169 break;
2170
2171 case OP_SRC_AND:
2172 if (op->dest.reg != CFI_SP ||
e7c0219b
PZ		 2173 (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
2174 (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
baa41469
JP		 2175 WARN_FUNC("unsupported stack pointer realignment",
2176 insn->sec, insn->offset);
2177 return -1;
2178 }
2179
e7c0219b 2180 if (cfi->drap_reg != CFI_UNDEFINED) {
baa41469 2181 /* drap: and imm, %rsp */
e7c0219b
PZ		 2182 cfa->base = cfi->drap_reg;
2183 cfa->offset = cfi->stack_size = 0;
2184 cfi->drap = true;
baa41469
JP		 2185 }
2186
2187 /*
2188 * Older versions of GCC (4.8ish) realign the stack
2189 * without DRAP, with a frame pointer.
2190 */
2191
2192 break;
2193
2194 case OP_SRC_POP:
ea24213d 2195 case OP_SRC_POPF:
aafeb14e
PZ		 2196 if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
2197
2198 /* pop %rsp; # restore from a stack swizzle */
2199 cfa->base = CFI_SP;
2200 break;
2201 }
2202
e7c0219b 2203 if (!cfi->drap && op->dest.reg == cfa->base) {
baa41469
JP		 2204
2205 /* pop %rbp */
2206 cfa->base = CFI_SP;
2207 }
2208
e7c0219b
PZ		 2209 if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
2210 op->dest.reg == cfi->drap_reg &&
2211 cfi->drap_offset == -cfi->stack_size) {
baa41469 2212
bf4d1a83 2213 /* drap: pop %drap */
e7c0219b 2214 cfa->base = cfi->drap_reg;
bf4d1a83 2215 cfa->offset = 0;
e7c0219b 2216 cfi->drap_offset = -1;
baa41469 2217
e7c0219b 2218 } else if (regs[op->dest.reg].offset == -cfi->stack_size) {
baa41469 2219
bf4d1a83 2220 /* pop %reg */
e7c0219b 2221 restore_reg(cfi, op->dest.reg);
baa41469
JP		 2222 }
2223
e7c0219b 2224 cfi->stack_size -= 8;
baa41469
JP		 2225 if (cfa->base == CFI_SP)
2226 cfa->offset -= 8;
2227
2228 break;
2229
2230 case OP_SRC_REG_INDIRECT:
201ef5a9
JT		 2231 if (!cfi->drap && op->dest.reg == cfa->base &&
2232 op->dest.reg == CFI_BP) {
2233
2234 /* mov disp(%rsp), %rbp */
2235 cfa->base = CFI_SP;
2236 cfa->offset = cfi->stack_size;
2237 }
2238
e7c0219b
PZ		 2239 if (cfi->drap && op->src.reg == CFI_BP &&
2240 op->src.offset == cfi->drap_offset) {
bf4d1a83
JP		 2241
2242 /* drap: mov disp(%rbp), %drap */
e7c0219b 2243 cfa->base = cfi->drap_reg;
bf4d1a83 2244 cfa->offset = 0;
e7c0219b 2245 cfi->drap_offset = -1;
bf4d1a83
JP		 2246 }
2247
e7c0219b 2248 if (cfi->drap && op->src.reg == CFI_BP &&
baa41469
JP		 2249 op->src.offset == regs[op->dest.reg].offset) {
2250
2251 /* drap: mov disp(%rbp), %reg */
e7c0219b 2252 restore_reg(cfi, op->dest.reg);
baa41469
JP		 2253
2254 } else if (op->src.reg == cfa->base &&
2255 op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
2256
2257 /* mov disp(%rbp), %reg */
2258 /* mov disp(%rsp), %reg */
e7c0219b 2259 restore_reg(cfi, op->dest.reg);
201ef5a9
JT		 2260
2261 } else if (op->src.reg == CFI_SP &&
2262 op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
2263
2264 /* mov disp(%rsp), %reg */
2265 restore_reg(cfi, op->dest.reg);
baa41469
JP		 2266 }
2267
2268 break;
2269
2270 default:
2271 WARN_FUNC("unknown stack-related instruction",
2272 insn->sec, insn->offset);
2273 return -1;
2274 }
2275
2276 break;
2277
2278 case OP_DEST_PUSH:
ea24213d 2279 case OP_DEST_PUSHF:
e7c0219b 2280 cfi->stack_size += 8;
baa41469
JP		 2281 if (cfa->base == CFI_SP)
2282 cfa->offset += 8;
2283
2284 if (op->src.type != OP_SRC_REG)
2285 break;
2286
e7c0219b
PZ		 2287 if (cfi->drap) {
2288 if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
baa41469
JP		 2289
2290 /* drap: push %drap */
2291 cfa->base = CFI_BP_INDIRECT;
e7c0219b 2292 cfa->offset = -cfi->stack_size;
baa41469 2293
bf4d1a83 2294 /* save drap so we know when to restore it */
e7c0219b 2295 cfi->drap_offset = -cfi->stack_size;
baa41469 2296
e7c0219b 2297 } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
baa41469
JP		 2298
2299 /* drap: push %rbp */
e7c0219b 2300 cfi->stack_size = 0;
baa41469 2301
f4f80398 2302 } else {
baa41469
JP		 2303
2304 /* drap: push %reg */
e7c0219b 2305 save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
baa41469
JP		 2306 }
2307
2308 } else {
2309
2310 /* push %reg */
e7c0219b 2311 save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
baa41469
JP		 2312 }
2313
2314 /* detect when asm code uses rbp as a scratch register */
867ac9d7 2315 if (!no_fp && insn->func && op->src.reg == CFI_BP &&
baa41469 2316 cfa->base != CFI_BP)
e7c0219b 2317 cfi->bp_scratch = true;
baa41469
JP		 2318 break;
2319
2320 case OP_DEST_REG_INDIRECT:
2321
e7c0219b
PZ		 2322 if (cfi->drap) {
2323 if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
baa41469
JP		 2324
2325 /* drap: mov %drap, disp(%rbp) */
2326 cfa->base = CFI_BP_INDIRECT;
2327 cfa->offset = op->dest.offset;
2328
bf4d1a83 2329 /* save drap offset so we know when to restore it */
e7c0219b 2330 cfi->drap_offset = op->dest.offset;
f4f80398 2331 } else {
baa41469
JP		 2332
2333 /* drap: mov reg, disp(%rbp) */
e7c0219b 2334 save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
baa41469
JP		 2335 }
2336
2337 } else if (op->dest.reg == cfa->base) {
2338
2339 /* mov reg, disp(%rbp) */
2340 /* mov reg, disp(%rsp) */
e7c0219b
PZ		 2341 save_reg(cfi, op->src.reg, CFI_CFA,
2342 op->dest.offset - cfi->cfa.offset);
201ef5a9
JT		 2343
2344 } else if (op->dest.reg == CFI_SP) {
2345
2346 /* mov reg, disp(%rsp) */
2347 save_reg(cfi, op->src.reg, CFI_CFA,
2348 op->dest.offset - cfi->stack_size);
aafeb14e
PZ		 2349
2350 } else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
2351
2352 /* mov %rsp, (%reg); # setup a stack swizzle. */
2353 cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
2354 cfi->vals[op->dest.reg].offset = cfa->offset;
baa41469
JP		 2355 }
2356
2357 break;
2358
2359 case OP_DEST_LEAVE:
e7c0219b
PZ		 2360 if ((!cfi->drap && cfa->base != CFI_BP) ||
2361 (cfi->drap && cfa->base != cfi->drap_reg)) {
baa41469
JP		 2362 WARN_FUNC("leave instruction with modified stack frame",
2363 insn->sec, insn->offset);
2364 return -1;
2365 }
2366
2367 /* leave (mov %rbp, %rsp; pop %rbp) */
2368
e7c0219b
PZ		 2369 cfi->stack_size = -cfi->regs[CFI_BP].offset - 8;
2370 restore_reg(cfi, CFI_BP);
baa41469 2371
e7c0219b 2372 if (!cfi->drap) {
baa41469
JP		 2373 cfa->base = CFI_SP;
2374 cfa->offset -= 8;
2375 }
2376
2377 break;
2378
2379 case OP_DEST_MEM:
ea24213d 2380 if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
baa41469
JP		 2381 WARN_FUNC("unknown stack-related memory operation",
2382 insn->sec, insn->offset);
2383 return -1;
2384 }
2385
2386 /* pop mem */
e7c0219b 2387 cfi->stack_size -= 8;
baa41469
JP		 2388 if (cfa->base == CFI_SP)
2389 cfa->offset -= 8;
2390
2391 break;
2392
2393 default:
2394 WARN_FUNC("unknown stack-related instruction",
2395 insn->sec, insn->offset);
2396 return -1;
2397 }
2398
2399 return 0;
2400}
2401
c9c324dc
JP		 2402/*
2403 * The stack layouts of alternatives instructions can sometimes diverge when
2404 * they have stack modifications. That's fine as long as the potential stack
2405 * layouts don't conflict at any given potential instruction boundary.
2406 *
2407 * Flatten the CFIs of the different alternative code streams (both original
2408 * and replacement) into a single shared CFI array which can be used to detect
2409 * conflicts and nicely feed a linear array of ORC entries to the unwinder.
2410 */
2411static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
65ea47dc 2412{
c9c324dc
JP		 2413 struct cfi_state **alt_cfi;
2414 int group_off;
65ea47dc 2415
c9c324dc
JP		 2416 if (!insn->alt_group)
2417 return 0;
65ea47dc 2418
c9c324dc
JP		 2419 alt_cfi = insn->alt_group->cfi;
2420 group_off = insn->offset - insn->alt_group->first_insn->offset;
65ea47dc 2421
c9c324dc
JP		 2422 if (!alt_cfi[group_off]) {
2423 alt_cfi[group_off] = &insn->cfi;
2424 } else {
2425 if (memcmp(alt_cfi[group_off], &insn->cfi, sizeof(struct cfi_state))) {
2426 WARN_FUNC("stack layout conflict in alternatives",
2427 insn->sec, insn->offset);
ab3852ab
PZ		 2428 return -1;
2429 }
c9c324dc
JP		 2430 }
2431
2432 return 0;
2433}
2434
2435static int handle_insn_ops(struct instruction *insn, struct insn_state *state)
2436{
2437 struct stack_op *op;
2438
2439 list_for_each_entry(op, &insn->stack_ops, list) {
2440
2441 if (update_cfi_state(insn, &state->cfi, op))
2442 return 1;
ab3852ab 2443
ba08abca
PZ		 2444 if (!insn->alt_group)
2445 continue;
2446
65ea47dc
JT		 2447 if (op->dest.type == OP_DEST_PUSHF) {
2448 if (!state->uaccess_stack) {
2449 state->uaccess_stack = 1;
2450 } else if (state->uaccess_stack >> 31) {
2451 WARN_FUNC("PUSHF stack exhausted",
2452 insn->sec, insn->offset);
2453 return 1;
2454 }
2455 state->uaccess_stack <<= 1;
2456 state->uaccess_stack |= state->uaccess;
2457 }
2458
2459 if (op->src.type == OP_SRC_POPF) {
2460 if (state->uaccess_stack) {
2461 state->uaccess = state->uaccess_stack & 1;
2462 state->uaccess_stack >>= 1;
2463 if (state->uaccess_stack == 1)
2464 state->uaccess_stack = 0;
2465 }
2466 }
2467 }
2468
2469 return 0;
2470}
2471
e7c0219b 2472static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
baa41469 2473{
e7c0219b 2474 struct cfi_state *cfi1 = &insn->cfi;
baa41469
JP		 2475 int i;
2476
e7c0219b
PZ		 2477 if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
2478
baa41469
JP		 2479 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
2480 insn->sec, insn->offset,
e7c0219b
PZ		 2481 cfi1->cfa.base, cfi1->cfa.offset,
2482 cfi2->cfa.base, cfi2->cfa.offset);
baa41469 2483
e7c0219b 2484 } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
baa41469 2485 for (i = 0; i < CFI_NUM_REGS; i++) {
e7c0219b 2486 if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
baa41469
JP		 2487 sizeof(struct cfi_reg)))
2488 continue;
2489
2490 WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
2491 insn->sec, insn->offset,
e7c0219b
PZ		 2492 i, cfi1->regs[i].base, cfi1->regs[i].offset,
2493 i, cfi2->regs[i].base, cfi2->regs[i].offset);
baa41469
JP		 2494 break;
2495 }
2496
e7c0219b
PZ		 2497 } else if (cfi1->type != cfi2->type) {
2498
627fce14 2499 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
e7c0219b
PZ		 2500 insn->sec, insn->offset, cfi1->type, cfi2->type);
2501
2502 } else if (cfi1->drap != cfi2->drap ||
2503 (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
2504 (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
627fce14 2505
bf4d1a83 2506 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
baa41469 2507 insn->sec, insn->offset,
e7c0219b
PZ		 2508 cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
2509 cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
baa41469
JP		 2510
2511 } else
2512 return true;
2513
2514 return false;
dcc914f4
JP		 2515}
2516
ea24213d
PZ		 2517static inline bool func_uaccess_safe(struct symbol *func)
2518{
2519 if (func)
e10cd8fe 2520 return func->uaccess_safe;
ea24213d
PZ		 2521
2522 return false;
2523}
2524
0c1ddd33 2525static inline const char *call_dest_name(struct instruction *insn)
ea24213d
PZ		 2526{
2527 if (insn->call_dest)
2528 return insn->call_dest->name;
2529
2530 return "{dynamic}";
2531}
2532
6b643a07
PZ		 2533static inline bool noinstr_call_dest(struct symbol *func)
2534{
2535 /*
2536 * We can't deal with indirect function calls at present;
2537 * assume they're instrumented.
2538 */
2539 if (!func)
2540 return false;
2541
2542 /*
2543 * If the symbol is from a noinstr section; we good.
2544 */
2545 if (func->sec->noinstr)
2546 return true;
2547
2548 /*
2549 * The __ubsan_handle_*() calls are like WARN(), they only happen when
2550 * something 'BAD' happened. At the risk of taking the machine down,
2551 * let them proceed to get the message out.
2552 */
2553 if (!strncmp(func->name, "__ubsan_handle_", 15))
2554 return true;
2555
2556 return false;
2557}
2558
ea24213d
PZ		 2559static int validate_call(struct instruction *insn, struct insn_state *state)
2560{
c4a33939 2561 if (state->noinstr && state->instr <= 0 &&
6b643a07 2562 !noinstr_call_dest(insn->call_dest)) {
c4a33939
PZ		 2563 WARN_FUNC("call to %s() leaves .noinstr.text section",
2564 insn->sec, insn->offset, call_dest_name(insn));
2565 return 1;
2566 }
2567
ea24213d
PZ		 2568 if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
2569 WARN_FUNC("call to %s() with UACCESS enabled",
0c1ddd33 2570 insn->sec, insn->offset, call_dest_name(insn));
ea24213d
PZ		 2571 return 1;
2572 }
2573
2f0f9e9a
PZ		 2574 if (state->df) {
2575 WARN_FUNC("call to %s() with DF set",
0c1ddd33 2576 insn->sec, insn->offset, call_dest_name(insn));
2f0f9e9a
PZ		 2577 return 1;
2578 }
2579
ea24213d
PZ		 2580 return 0;
2581}
2582
54262aa2
PZ		 2583static int validate_sibling_call(struct instruction *insn, struct insn_state *state)
2584{
e25eea89 2585 if (has_modified_stack_frame(insn, state)) {
54262aa2
PZ		 2586 WARN_FUNC("sibling call from callable instruction with modified stack frame",
2587 insn->sec, insn->offset);
2588 return 1;
2589 }
2590
ea24213d 2591 return validate_call(insn, state);
54262aa2
PZ		 2592}
2593
a92e92d1
PZ		 2594static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
2595{
c4a33939
PZ		 2596 if (state->noinstr && state->instr > 0) {
2597 WARN_FUNC("return with instrumentation enabled",
2598 insn->sec, insn->offset);
2599 return 1;
2600 }
2601
a92e92d1
PZ		 2602 if (state->uaccess && !func_uaccess_safe(func)) {
2603 WARN_FUNC("return with UACCESS enabled",
2604 insn->sec, insn->offset);
2605 return 1;
2606 }
2607
2608 if (!state->uaccess && func_uaccess_safe(func)) {
2609 WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function",
2610 insn->sec, insn->offset);
2611 return 1;
2612 }
2613
2614 if (state->df) {
2615 WARN_FUNC("return with DF set",
2616 insn->sec, insn->offset);
2617 return 1;
2618 }
2619
e25eea89 2620 if (func && has_modified_stack_frame(insn, state)) {
a92e92d1
PZ		 2621 WARN_FUNC("return with modified stack frame",
2622 insn->sec, insn->offset);
2623 return 1;
2624 }
2625
e7c0219b 2626 if (state->cfi.bp_scratch) {
b2966952
JP		 2627 WARN_FUNC("BP used as a scratch register",
2628 insn->sec, insn->offset);
a92e92d1
PZ		 2629 return 1;
2630 }
2631
2632 return 0;
2633}
2634
c9c324dc
JP		 2635static struct instruction *next_insn_to_validate(struct objtool_file *file,
2636 struct instruction *insn)
7117f16b 2637{
b23cc71c 2638 struct alt_group *alt_group = insn->alt_group;
7117f16b 2639
c9c324dc
JP		 2640 /*
2641 * Simulate the fact that alternatives are patched in-place. When the
2642 * end of a replacement alt_group is reached, redirect objtool flow to
2643 * the end of the original alt_group.
2644 */
2645 if (alt_group && insn == alt_group->last_insn && alt_group->orig_group)
2646 return next_insn_same_sec(file, alt_group->orig_group->last_insn);
2647
2648 return next_insn_same_sec(file, insn);
7117f16b
PZ		 2649}
2650
dcc914f4
JP		 2651/*
2652 * Follow the branch starting at the given instruction, and recursively follow
2653 * any other branches (jumps). Meanwhile, track the frame pointer state at
2654 * each instruction and validate all the rules described in
2655 * tools/objtool/Documentation/stack-validation.txt.
2656 */
c705cecc 2657static int validate_branch(struct objtool_file *file, struct symbol *func,
b7460462 2658 struct instruction *insn, struct insn_state state)
dcc914f4
JP		 2659{
2660 struct alternative *alt;
b7460462 2661 struct instruction *next_insn;
dcc914f4 2662 struct section *sec;
882a0db9 2663 u8 visited;
dcc914f4
JP		 2664 int ret;
2665
dcc914f4 2666 sec = insn->sec;
dcc914f4 2667
dcc914f4 2668 while (1) {
c9c324dc 2669 next_insn = next_insn_to_validate(file, insn);
39358a03 2670
13810435 2671 if (file->c_file && func && insn->func && func != insn->func->pfunc) {
ee97638b
JP		 2672 WARN("%s() falls through to next function %s()",
2673 func->name, insn->func->name);
2674 return 1;
dcc914f4
JP		 2675 }
2676
4855022a
JP		 2677 if (func && insn->ignore) {
2678 WARN_FUNC("BUG: why am I validating an ignored function?",
2679 sec, insn->offset);
12b25729 2680 return 1;
4855022a
JP		 2681 }
2682
882a0db9 2683 visited = 1 << state.uaccess;
dcc914f4 2684 if (insn->visited) {
e7c0219b 2685 if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
dcc914f4 2686 return 1;
dcc914f4 2687
882a0db9 2688 if (insn->visited & visited)
ea24213d 2689 return 0;
dcc914f4
JP		 2690 }
2691
c4a33939
PZ		 2692 if (state.noinstr)
2693 state.instr += insn->instr;
2694
c536ed2f 2695 if (insn->hint)
e7c0219b 2696 state.cfi = insn->cfi;
c536ed2f 2697 else
e7c0219b 2698 insn->cfi = state.cfi;
dcc914f4 2699
882a0db9 2700 insn->visited |= visited;
baa41469 2701
c9c324dc
JP		 2702 if (propagate_alt_cfi(file, insn))
2703 return 1;
2704
7117f16b 2705 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
764eef4b
PZ		 2706 bool skip_orig = false;
2707
a845c7cf 2708 list_for_each_entry(alt, &insn->alts, list) {
764eef4b
PZ		 2709 if (alt->skip_orig)
2710 skip_orig = true;
2711
c705cecc 2712 ret = validate_branch(file, func, alt->insn, state);
7697eee3
PZ		 2713 if (ret) {
2714 if (backtrace)
2715 BT_FUNC("(alt)", insn);
2716 return ret;
2717 }
a845c7cf 2718 }
764eef4b
PZ		 2719
2720 if (skip_orig)
2721 return 0;
dcc914f4
JP		 2722 }
2723
60041bcd
PZ		 2724 if (handle_insn_ops(insn, &state))
2725 return 1;
2726
dcc914f4
JP		 2727 switch (insn->type) {
2728
dcc914f4 2729 case INSN_RETURN:
a92e92d1 2730 return validate_return(func, insn, &state);
dcc914f4
JP		 2731
2732 case INSN_CALL:
ea24213d
PZ		 2733 case INSN_CALL_DYNAMIC:
2734 ret = validate_call(insn, &state);
2735 if (ret)
2736 return ret;
dcc914f4 2737
c9bab22b
JP		 2738 if (!no_fp && func && !is_fentry_call(insn) &&
2739 !has_valid_stack_frame(&state)) {
dcc914f4
JP		 2740 WARN_FUNC("call without frame pointer save/setup",
2741 sec, insn->offset);
2742 return 1;
2743 }
c9bab22b
JP		 2744
2745 if (dead_end_function(file, insn->call_dest))
2746 return 0;
2747
1e7e4788
JP		 2748 if (insn->type == INSN_CALL && insn->call_dest->static_call_tramp) {
2749 list_add_tail(&insn->static_call_node,
2750 &file->static_call_list);
2751 }
2752
dcc914f4
JP		 2753 break;
2754
2755 case INSN_JUMP_CONDITIONAL:
2756 case INSN_JUMP_UNCONDITIONAL:
ecf11ba4 2757 if (is_sibling_call(insn)) {
54262aa2 2758 ret = validate_sibling_call(insn, &state);
dcc914f4 2759 if (ret)
54262aa2 2760 return ret;
4855022a 2761
0c1ddd33 2762 } else if (insn->jump_dest) {
c705cecc
JP		 2763 ret = validate_branch(file, func,
2764 insn->jump_dest, state);
7697eee3
PZ		 2765 if (ret) {
2766 if (backtrace)
2767 BT_FUNC("(branch)", insn);
2768 return ret;
2769 }
4855022a 2770 }
dcc914f4
JP		 2771
2772 if (insn->type == INSN_JUMP_UNCONDITIONAL)
2773 return 0;
2774
2775 break;
2776
2777 case INSN_JUMP_DYNAMIC:
b68b9907 2778 case INSN_JUMP_DYNAMIC_CONDITIONAL:
ecf11ba4 2779 if (is_sibling_call(insn)) {
54262aa2
PZ		 2780 ret = validate_sibling_call(insn, &state);
2781 if (ret)
2782 return ret;
dcc914f4
JP		 2783 }
2784
b68b9907
JP		 2785 if (insn->type == INSN_JUMP_DYNAMIC)
2786 return 0;
2787
2788 break;
dcc914f4 2789
39358a03
JP		 2790 case INSN_CONTEXT_SWITCH:
2791 if (func && (!next_insn || !next_insn->hint)) {
2792 WARN_FUNC("unsupported instruction in callable function",
2793 sec, insn->offset);
2794 return 1;
2795 }
2796 return 0;
2797
ea24213d
PZ		 2798 case INSN_STAC:
2799 if (state.uaccess) {
2800 WARN_FUNC("recursive UACCESS enable", sec, insn->offset);
2801 return 1;
2802 }
2803
2804 state.uaccess = true;
2805 break;
2806
2807 case INSN_CLAC:
c705cecc 2808 if (!state.uaccess && func) {
ea24213d
PZ		 2809 WARN_FUNC("redundant UACCESS disable", sec, insn->offset);
2810 return 1;
2811 }
2812
2813 if (func_uaccess_safe(func) && !state.uaccess_stack) {
2814 WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset);
2815 return 1;
2816 }
2817
2818 state.uaccess = false;
baa41469
JP		 2819 break;
2820
2f0f9e9a 2821 case INSN_STD:
6f567c93 2822 if (state.df) {
2f0f9e9a 2823 WARN_FUNC("recursive STD", sec, insn->offset);
6f567c93
JP		 2824 return 1;
2825 }
2f0f9e9a
PZ		 2826
2827 state.df = true;
2828 break;
2829
2830 case INSN_CLD:
6f567c93 2831 if (!state.df && func) {
2f0f9e9a 2832 WARN_FUNC("redundant CLD", sec, insn->offset);
6f567c93
JP		 2833 return 1;
2834 }
2f0f9e9a
PZ		 2835
2836 state.df = false;
baa41469
JP		 2837 break;
2838
dcc914f4
JP		 2839 default:
2840 break;
2841 }
2842
2843 if (insn->dead_end)
2844 return 0;
2845
00d96180 2846 if (!next_insn) {
e7c0219b 2847 if (state.cfi.cfa.base == CFI_UNDEFINED)
00d96180 2848 return 0;
dcc914f4
JP		 2849 WARN("%s: unexpected end of section", sec->name);
2850 return 1;
2851 }
00d96180
JP		 2852
2853 insn = next_insn;
dcc914f4
JP		 2854 }
2855
2856 return 0;
2857}
2858
932f8e98 2859static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
39358a03
JP		 2860{
2861 struct instruction *insn;
39358a03 2862 struct insn_state state;
932f8e98 2863 int ret, warnings = 0;
39358a03
JP		 2864
2865 if (!file->hints)
2866 return 0;
2867
932f8e98 2868 init_insn_state(&state, sec);
39358a03 2869
932f8e98
PZ		 2870 if (sec) {
2871 insn = find_insn(file, sec, 0);
2872 if (!insn)
2873 return 0;
2874 } else {
2875 insn = list_first_entry(&file->insn_list, typeof(*insn), list);
2876 }
2877
2878 while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
39358a03 2879 if (insn->hint && !insn->visited) {
c705cecc 2880 ret = validate_branch(file, insn->func, insn, state);
7697eee3
PZ		 2881 if (ret && backtrace)
2882 BT_FUNC("<=== (hint)", insn);
39358a03
JP		 2883 warnings += ret;
2884 }
932f8e98
PZ		 2885
2886 insn = list_next_entry(insn, list);
39358a03
JP		 2887 }
2888
2889 return warnings;
2890}
2891
b5bc2231
PZ		 2892static int validate_retpoline(struct objtool_file *file)
2893{
2894 struct instruction *insn;
2895 int warnings = 0;
2896
2897 for_each_insn(file, insn) {
2898 if (insn->type != INSN_JUMP_DYNAMIC &&
2899 insn->type != INSN_CALL_DYNAMIC)
2900 continue;
2901
2902 if (insn->retpoline_safe)
2903 continue;
2904
ca41b97e
PZ		 2905 /*
2906 * .init.text code is ran before userspace and thus doesn't
2907 * strictly need retpolines, except for modules which are
2908 * loaded late, they very much do need retpoline in their
2909 * .init.text
2910 */
2911 if (!strcmp(insn->sec->name, ".init.text") && !module)
2912 continue;
2913
b5bc2231
PZ		 2914 WARN_FUNC("indirect %s found in RETPOLINE build",
2915 insn->sec, insn->offset,
2916 insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
2917
2918 warnings++;
2919 }
2920
2921 return warnings;
2922}
2923
dcc914f4
JP		 2924static bool is_kasan_insn(struct instruction *insn)
2925{
2926 return (insn->type == INSN_CALL &&
2927 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
2928}
2929
2930static bool is_ubsan_insn(struct instruction *insn)
2931{
2932 return (insn->type == INSN_CALL &&
2933 !strcmp(insn->call_dest->name,
2934 "__ubsan_handle_builtin_unreachable"));
2935}
2936
14db1f0a 2937static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
dcc914f4
JP		 2938{
2939 int i;
14db1f0a 2940 struct instruction *prev_insn;
dcc914f4 2941
baa41469
JP		 2942 if (insn->ignore || insn->type == INSN_NOP)
2943 return true;
2944
2945 /*
2946 * Ignore any unused exceptions. This can happen when a whitelisted
2947 * function has an exception table entry.
0e2bb2bc
JP		 2948 *
2949 * Also ignore alternative replacement instructions. This can happen
2950 * when a whitelisted function uses one of the ALTERNATIVE macros.
baa41469 2951 */
0e2bb2bc
JP		 2952 if (!strcmp(insn->sec->name, ".fixup") ||
2953 !strcmp(insn->sec->name, ".altinstr_replacement") ||
2954 !strcmp(insn->sec->name, ".altinstr_aux"))
dcc914f4
JP		 2955 return true;
2956
bd841d61
JP		 2957 if (!insn->func)
2958 return false;
2959
2960 /*
2961 * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
2962 * __builtin_unreachable(). The BUG() macro has an unreachable() after
2963 * the UD2, which causes GCC's undefined trap logic to emit another UD2
2964 * (or occasionally a JMP to UD2).
14db1f0a
IH		 2965 *
2966 * It may also insert a UD2 after calling a __noreturn function.
bd841d61 2967 */
14db1f0a
IH		 2968 prev_insn = list_prev_entry(insn, list);
2969 if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&
bd841d61
JP		 2970 (insn->type == INSN_BUG ||
2971 (insn->type == INSN_JUMP_UNCONDITIONAL &&
2972 insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
2973 return true;
2974
dcc914f4
JP		 2975 /*
2976 * Check if this (or a subsequent) instruction is related to
2977 * CONFIG_UBSAN or CONFIG_KASAN.
2978 *
2979 * End the search at 5 instructions to avoid going into the weeds.
2980 */
2981 for (i = 0; i < 5; i++) {
2982
2983 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
2984 return true;
2985
fe24e271
JP		 2986 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
2987 if (insn->jump_dest &&
2988 insn->jump_dest->func == insn->func) {
2989 insn = insn->jump_dest;
2990 continue;
2991 }
2992
2993 break;
dcc914f4
JP		 2994 }
2995
baa41469 2996 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
dcc914f4 2997 break;
fe24e271 2998
dcc914f4
JP		 2999 insn = list_next_entry(insn, list);
3000 }
3001
3002 return false;
3003}
3004
4b5e2e7f
PZ		 3005static int validate_symbol(struct objtool_file *file, struct section *sec,
3006 struct symbol *sym, struct insn_state *state)
dcc914f4 3007{
dcc914f4 3008 struct instruction *insn;
4b5e2e7f
PZ		 3009 int ret;
3010
3011 if (!sym->len) {
3012 WARN("%s() is missing an ELF size annotation", sym->name);
3013 return 1;
3014 }
3015
3016 if (sym->pfunc != sym || sym->alias != sym)
3017 return 0;
3018
3019 insn = find_insn(file, sec, sym->offset);
3020 if (!insn || insn->ignore || insn->visited)
3021 return 0;
3022
3023 state->uaccess = sym->uaccess_safe;
3024
3025 ret = validate_branch(file, insn->func, insn, *state);
3026 if (ret && backtrace)
3027 BT_FUNC("<=== (sym)", insn);
3028 return ret;
3029}
3030
3031static int validate_section(struct objtool_file *file, struct section *sec)
3032{
baa41469 3033 struct insn_state state;
4b5e2e7f
PZ		 3034 struct symbol *func;
3035 int warnings = 0;
dcc914f4 3036
350994bf
PZ		 3037 list_for_each_entry(func, &sec->symbol_list, list) {
3038 if (func->type != STT_FUNC)
3039 continue;
e10cd8fe 3040
932f8e98 3041 init_insn_state(&state, sec);
b735bd3e 3042 set_func_state(&state.cfi);
0699e551 3043
4b5e2e7f 3044 warnings += validate_symbol(file, sec, func, &state);
dcc914f4
JP		 3045 }
3046
dcc914f4
JP		 3047 return warnings;
3048}
3049
c4a33939
PZ		 3050static int validate_vmlinux_functions(struct objtool_file *file)
3051{
3052 struct section *sec;
932f8e98 3053 int warnings = 0;
c4a33939
PZ		 3054
3055 sec = find_section_by_name(file->elf, ".noinstr.text");
0cc9ac8d
TG		 3056 if (sec) {
3057 warnings += validate_section(file, sec);
3058 warnings += validate_unwind_hints(file, sec);
3059 }
c4a33939 3060
0cc9ac8d
TG		 3061 sec = find_section_by_name(file->elf, ".entry.text");
3062 if (sec) {
3063 warnings += validate_section(file, sec);
3064 warnings += validate_unwind_hints(file, sec);
3065 }
932f8e98
PZ		 3066
3067 return warnings;
c4a33939
PZ		 3068}
3069
350994bf
PZ		 3070static int validate_functions(struct objtool_file *file)
3071{
3072 struct section *sec;
3073 int warnings = 0;
3074
da837bd6
PZ		 3075 for_each_sec(file, sec) {
3076 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
3077 continue;
3078
350994bf 3079 warnings += validate_section(file, sec);
da837bd6 3080 }
350994bf
PZ		 3081
3082 return warnings;
3083}
3084
baa41469 3085static int validate_reachable_instructions(struct objtool_file *file)
dcc914f4
JP		 3086{
3087 struct instruction *insn;
baa41469
JP		 3088
3089 if (file->ignore_unreachables)
3090 return 0;
dcc914f4
JP		 3091
3092 for_each_insn(file, insn) {
14db1f0a 3093 if (insn->visited || ignore_unreachable_insn(file, insn))
baa41469
JP		 3094 continue;
3095
baa41469
JP		 3096 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
3097 return 1;
dcc914f4
JP		 3098 }
3099
baa41469 3100 return 0;
dcc914f4
JP		 3101}
3102
d44becb9 3103int check(struct objtool_file *file)
dcc914f4 3104{
dcc914f4
JP		 3105 int ret, warnings = 0;
3106
baa41469
JP		 3107 arch_initial_func_cfi_state(&initial_func_cfi);
3108
6545eb03 3109 ret = decode_sections(file);
dcc914f4
JP		 3110 if (ret < 0)
3111 goto out;
3112 warnings += ret;
3113
6545eb03 3114 if (list_empty(&file->insn_list))
dcc914f4 3115 goto out;
dcc914f4 3116
c4a33939 3117 if (vmlinux && !validate_dup) {
6545eb03 3118 ret = validate_vmlinux_functions(file);
c4a33939
PZ		 3119 if (ret < 0)
3120 goto out;
3121
3122 warnings += ret;
3123 goto out;
3124 }
3125
b5bc2231 3126 if (retpoline) {
6545eb03 3127 ret = validate_retpoline(file);
b5bc2231
PZ		 3128 if (ret < 0)
3129 return ret;
3130 warnings += ret;
3131 }
3132
6545eb03 3133 ret = validate_functions(file);
dcc914f4
JP		 3134 if (ret < 0)
3135 goto out;
3136 warnings += ret;
3137
6545eb03 3138 ret = validate_unwind_hints(file, NULL);
39358a03
JP		 3139 if (ret < 0)
3140 goto out;
3141 warnings += ret;
3142
baa41469 3143 if (!warnings) {
6545eb03 3144 ret = validate_reachable_instructions(file);
baa41469
JP		 3145 if (ret < 0)
3146 goto out;
3147 warnings += ret;
3148 }
3149
6545eb03 3150 ret = create_static_call_sections(file);
1e7e4788
JP		 3151 if (ret < 0)
3152 goto out;
3153 warnings += ret;
3154
99d00215
PZ		 3155 if (mcount) {
3156 ret = create_mcount_loc_sections(file);
3157 if (ret < 0)
3158 goto out;
3159 warnings += ret;
3160 }
3161
dcc914f4 3162out:
655cf865
JP		 3163 /*
3164 * For now, don't fail the kernel build on fatal warnings. These
3165 * errors are still fairly common due to the growing matrix of
3166 * supported toolchains and their recent pace of change.
3167 */
dcc914f4
JP		 3168 return 0;
3169}
Ubuntu Jammy Linux kernel mirror