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objtool: Support addition to set CFA base
[linux-block.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
43a4525f 9#include "builtin.h"
0decf1f8
MH		 10#include "cfi.h"
11#include "arch.h"
dcc914f4 12#include "check.h"
dcc914f4 13#include "special.h"
dcc914f4 14#include "warn.h"
0f1441b4 15#include "arch_elf.h"
dcc914f4 16
ee819aed 17#include <linux/objtool.h>
dcc914f4
JP		 18#include <linux/hashtable.h>
19#include <linux/kernel.h>
1e7e4788 20#include <linux/static_call_types.h>
dcc914f4 21
e6da9567
JP		 22#define FAKE_JUMP_OFFSET -1
23
dcc914f4
JP		 24struct alternative {
25 struct list_head list;
26 struct instruction *insn;
764eef4b 27 bool skip_orig;
dcc914f4
JP		 28};
29
a3608f59 30struct cfi_init_state initial_func_cfi;
dcc914f4 31
627fce14
JP		 32struct instruction *find_insn(struct objtool_file *file,
33 struct section *sec, unsigned long offset)
dcc914f4
JP		 34{
35 struct instruction *insn;
36
87ecb582 37 hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
dcc914f4
JP		 38 if (insn->sec == sec && insn->offset == offset)
39 return insn;
87ecb582 40 }
dcc914f4
JP		 41
42 return NULL;
43}
44
45static struct instruction *next_insn_same_sec(struct objtool_file *file,
46 struct instruction *insn)
47{
48 struct instruction *next = list_next_entry(insn, list);
49
baa41469 50 if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
dcc914f4
JP		 51 return NULL;
52
53 return next;
54}
55
13810435
JP		 56static struct instruction *next_insn_same_func(struct objtool_file *file,
57 struct instruction *insn)
58{
59 struct instruction *next = list_next_entry(insn, list);
60 struct symbol *func = insn->func;
61
62 if (!func)
63 return NULL;
64
65 if (&next->list != &file->insn_list && next->func == func)
66 return next;
67
68 /* Check if we're already in the subfunction: */
69 if (func == func->cfunc)
70 return NULL;
71
72 /* Move to the subfunction: */
73 return find_insn(file, func->cfunc->sec, func->cfunc->offset);
74}
75
1119d265
JP		 76static struct instruction *prev_insn_same_sym(struct objtool_file *file,
77 struct instruction *insn)
78{
79 struct instruction *prev = list_prev_entry(insn, list);
80
81 if (&prev->list != &file->insn_list && prev->func == insn->func)
82 return prev;
83
84 return NULL;
85}
86
f0f70adb 87#define func_for_each_insn(file, func, insn) \
13810435
JP		 88 for (insn = find_insn(file, func->sec, func->offset); \
89 insn; \
90 insn = next_insn_same_func(file, insn))
91
dbf4aeb0
PZ		 92#define sym_for_each_insn(file, sym, insn) \
93 for (insn = find_insn(file, sym->sec, sym->offset); \
dcc914f4 94 insn && &insn->list != &file->insn_list && \
dbf4aeb0
PZ		 95 insn->sec == sym->sec && \
96 insn->offset < sym->offset + sym->len; \
dcc914f4
JP		 97 insn = list_next_entry(insn, list))
98
dbf4aeb0 99#define sym_for_each_insn_continue_reverse(file, sym, insn) \
dcc914f4
JP		 100 for (insn = list_prev_entry(insn, list); \
101 &insn->list != &file->insn_list && \
dbf4aeb0 102 insn->sec == sym->sec && insn->offset >= sym->offset; \
dcc914f4
JP		 103 insn = list_prev_entry(insn, list))
104
105#define sec_for_each_insn_from(file, insn) \
106 for (; insn; insn = next_insn_same_sec(file, insn))
107
baa41469
JP		 108#define sec_for_each_insn_continue(file, insn) \
109 for (insn = next_insn_same_sec(file, insn); insn; \
110 insn = next_insn_same_sec(file, insn))
dcc914f4 111
0c1ddd33
JP		 112static bool is_sibling_call(struct instruction *insn)
113{
114 /* An indirect jump is either a sibling call or a jump to a table. */
115 if (insn->type == INSN_JUMP_DYNAMIC)
116 return list_empty(&insn->alts);
117
a2296140 118 if (!is_static_jump(insn))
0c1ddd33
JP		 119 return false;
120
121 /* add_jump_destinations() sets insn->call_dest for sibling calls. */
122 return !!insn->call_dest;
123}
124
dcc914f4
JP		 125/*
126 * This checks to see if the given function is a "noreturn" function.
127 *
128 * For global functions which are outside the scope of this object file, we
129 * have to keep a manual list of them.
130 *
131 * For local functions, we have to detect them manually by simply looking for
132 * the lack of a return instruction.
dcc914f4 133 */
8e25c9f8
JP		 134static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
135 int recursion)
dcc914f4
JP		 136{
137 int i;
138 struct instruction *insn;
139 bool empty = true;
140
141 /*
142 * Unfortunately these have to be hard coded because the noreturn
143 * attribute isn't provided in ELF data.
144 */
145 static const char * const global_noreturns[] = {
146 "__stack_chk_fail",
147 "panic",
148 "do_exit",
149 "do_task_dead",
150 "__module_put_and_exit",
151 "complete_and_exit",
dcc914f4
JP		 152 "__reiserfs_panic",
153 "lbug_with_loc",
154 "fortify_panic",
b394d468 155 "usercopy_abort",
684fb246 156 "machine_real_restart",
4fa5ecda 157 "rewind_stack_do_exit",
33adf80f 158 "kunit_try_catch_throw",
dcc914f4
JP		 159 };
160
c9bab22b
JP		 161 if (!func)
162 return false;
163
dcc914f4 164 if (func->bind == STB_WEAK)
8e25c9f8 165 return false;
dcc914f4
JP		 166
167 if (func->bind == STB_GLOBAL)
168 for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
169 if (!strcmp(func->name, global_noreturns[i]))
8e25c9f8 170 return true;
dcc914f4 171
13810435 172 if (!func->len)
8e25c9f8 173 return false;
dcc914f4 174
13810435
JP		 175 insn = find_insn(file, func->sec, func->offset);
176 if (!insn->func)
8e25c9f8 177 return false;
13810435 178
f0f70adb 179 func_for_each_insn(file, func, insn) {
dcc914f4
JP		 180 empty = false;
181
182 if (insn->type == INSN_RETURN)
8e25c9f8 183 return false;
dcc914f4
JP		 184 }
185
186 if (empty)
8e25c9f8 187 return false;
dcc914f4
JP		 188
189 /*
190 * A function can have a sibling call instead of a return. In that
191 * case, the function's dead-end status depends on whether the target
192 * of the sibling call returns.
193 */
f0f70adb 194 func_for_each_insn(file, func, insn) {
0c1ddd33 195 if (is_sibling_call(insn)) {
dcc914f4 196 struct instruction *dest = insn->jump_dest;
dcc914f4
JP		 197
198 if (!dest)
199 /* sibling call to another file */
8e25c9f8 200 return false;
dcc914f4 201
0c1ddd33
JP		 202 /* local sibling call */
203 if (recursion == 5) {
204 /*
205 * Infinite recursion: two functions have
206 * sibling calls to each other. This is a very
207 * rare case. It means they aren't dead ends.
208 */
209 return false;
dcc914f4 210 }
dcc914f4 211
0c1ddd33
JP		 212 return __dead_end_function(file, dest->func, recursion+1);
213 }
dcc914f4
JP		 214 }
215
8e25c9f8 216 return true;
dcc914f4
JP		 217}
218
8e25c9f8 219static bool dead_end_function(struct objtool_file *file, struct symbol *func)
dcc914f4
JP		 220{
221 return __dead_end_function(file, func, 0);
222}
223
e7c0219b 224static void init_cfi_state(struct cfi_state *cfi)
baa41469
JP		 225{
226 int i;
227
dd88a0a0 228 for (i = 0; i < CFI_NUM_REGS; i++) {
e7c0219b
PZ		 229 cfi->regs[i].base = CFI_UNDEFINED;
230 cfi->vals[i].base = CFI_UNDEFINED;
dd88a0a0 231 }
e7c0219b
PZ		 232 cfi->cfa.base = CFI_UNDEFINED;
233 cfi->drap_reg = CFI_UNDEFINED;
234 cfi->drap_offset = -1;
235}
236
932f8e98 237static void init_insn_state(struct insn_state *state, struct section *sec)
e7c0219b
PZ		 238{
239 memset(state, 0, sizeof(*state));
240 init_cfi_state(&state->cfi);
932f8e98
PZ		 241
242 /*
243 * We need the full vmlinux for noinstr validation, otherwise we can
244 * not correctly determine insn->call_dest->sec (external symbols do
245 * not have a section).
246 */
247 if (vmlinux && sec)
248 state->noinstr = sec->noinstr;
baa41469
JP		 249}
250
dcc914f4
JP		 251/*
252 * Call the arch-specific instruction decoder for all the instructions and add
253 * them to the global instruction list.
254 */
255static int decode_instructions(struct objtool_file *file)
256{
257 struct section *sec;
258 struct symbol *func;
259 unsigned long offset;
260 struct instruction *insn;
1e11f3fd 261 unsigned long nr_insns = 0;
dcc914f4
JP		 262 int ret;
263
baa41469 264 for_each_sec(file, sec) {
dcc914f4
JP		 265
266 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
267 continue;
268
627fce14
JP		 269 if (strcmp(sec->name, ".altinstr_replacement") &&
270 strcmp(sec->name, ".altinstr_aux") &&
271 strncmp(sec->name, ".discard.", 9))
272 sec->text = true;
273
0cc9ac8d
TG		 274 if (!strcmp(sec->name, ".noinstr.text") ||
275 !strcmp(sec->name, ".entry.text"))
c4a33939
PZ		 276 sec->noinstr = true;
277
dcc914f4
JP		 278 for (offset = 0; offset < sec->len; offset += insn->len) {
279 insn = malloc(sizeof(*insn));
baa41469
JP		 280 if (!insn) {
281 WARN("malloc failed");
282 return -1;
283 }
dcc914f4 284 memset(insn, 0, sizeof(*insn));
dcc914f4 285 INIT_LIST_HEAD(&insn->alts);
65ea47dc 286 INIT_LIST_HEAD(&insn->stack_ops);
e7c0219b 287 init_cfi_state(&insn->cfi);
baa41469 288
dcc914f4
JP		 289 insn->sec = sec;
290 insn->offset = offset;
291
292 ret = arch_decode_instruction(file->elf, sec, offset,
293 sec->len - offset,
294 &insn->len, &insn->type,
baa41469 295 &insn->immediate,
65ea47dc 296 &insn->stack_ops);
dcc914f4 297 if (ret)
b7037983 298 goto err;
dcc914f4 299
87ecb582 300 hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
dcc914f4 301 list_add_tail(&insn->list, &file->insn_list);
1e11f3fd 302 nr_insns++;
dcc914f4
JP		 303 }
304
305 list_for_each_entry(func, &sec->symbol_list, list) {
e10cd8fe 306 if (func->type != STT_FUNC || func->alias != func)
dcc914f4
JP		 307 continue;
308
309 if (!find_insn(file, sec, func->offset)) {
310 WARN("%s(): can't find starting instruction",
311 func->name);
312 return -1;
313 }
314
dbf4aeb0 315 sym_for_each_insn(file, func, insn)
e10cd8fe 316 insn->func = func;
dcc914f4
JP		 317 }
318 }
319
1e11f3fd
PZ		 320 if (stats)
321 printf("nr_insns: %lu\n", nr_insns);
322
dcc914f4 323 return 0;
b7037983
KB		 324
325err:
326 free(insn);
327 return ret;
dcc914f4
JP		 328}
329
6b5dd716
ST		 330static struct instruction *find_last_insn(struct objtool_file *file,
331 struct section *sec)
332{
333 struct instruction *insn = NULL;
334 unsigned int offset;
335 unsigned int end = (sec->len > 10) ? sec->len - 10 : 0;
336
337 for (offset = sec->len - 1; offset >= end && !insn; offset--)
338 insn = find_insn(file, sec, offset);
339
340 return insn;
341}
342
dcc914f4 343/*
649ea4d5 344 * Mark "ud2" instructions and manually annotated dead ends.
dcc914f4
JP		 345 */
346static int add_dead_ends(struct objtool_file *file)
347{
348 struct section *sec;
f1974222 349 struct reloc *reloc;
dcc914f4 350 struct instruction *insn;
dcc914f4 351
649ea4d5
JP		 352 /*
353 * By default, "ud2" is a dead end unless otherwise annotated, because
354 * GCC 7 inserts it for certain divide-by-zero cases.
355 */
356 for_each_insn(file, insn)
357 if (insn->type == INSN_BUG)
358 insn->dead_end = true;
359
360 /*
361 * Check for manually annotated dead ends.
362 */
dcc914f4
JP		 363 sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
364 if (!sec)
649ea4d5 365 goto reachable;
dcc914f4 366
f1974222
MH		 367 list_for_each_entry(reloc, &sec->reloc_list, list) {
368 if (reloc->sym->type != STT_SECTION) {
dcc914f4
JP		 369 WARN("unexpected relocation symbol type in %s", sec->name);
370 return -1;
371 }
f1974222 372 insn = find_insn(file, reloc->sym->sec, reloc->addend);
dcc914f4
JP		 373 if (insn)
374 insn = list_prev_entry(insn, list);
f1974222
MH		 375 else if (reloc->addend == reloc->sym->sec->len) {
376 insn = find_last_insn(file, reloc->sym->sec);
6b5dd716 377 if (!insn) {
dcc914f4 378 WARN("can't find unreachable insn at %s+0x%x",
f1974222 379 reloc->sym->sec->name, reloc->addend);
dcc914f4
JP		 380 return -1;
381 }
382 } else {
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
388 insn->dead_end = true;
389 }
390
649ea4d5
JP		 391reachable:
392 /*
393 * These manually annotated reachable checks are needed for GCC 4.4,
394 * where the Linux unreachable() macro isn't supported. In that case
395 * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
396 * not a dead end.
397 */
398 sec = find_section_by_name(file->elf, ".rela.discard.reachable");
399 if (!sec)
400 return 0;
401
f1974222
MH		 402 list_for_each_entry(reloc, &sec->reloc_list, list) {
403 if (reloc->sym->type != STT_SECTION) {
649ea4d5
JP		 404 WARN("unexpected relocation symbol type in %s", sec->name);
405 return -1;
406 }
f1974222 407 insn = find_insn(file, reloc->sym->sec, reloc->addend);
649ea4d5
JP		 408 if (insn)
409 insn = list_prev_entry(insn, list);
f1974222
MH		 410 else if (reloc->addend == reloc->sym->sec->len) {
411 insn = find_last_insn(file, reloc->sym->sec);
6b5dd716 412 if (!insn) {
649ea4d5 413 WARN("can't find reachable insn at %s+0x%x",
f1974222 414 reloc->sym->sec->name, reloc->addend);
649ea4d5
JP		 415 return -1;
416 }
417 } else {
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
423 insn->dead_end = false;
424 }
425
dcc914f4
JP		 426 return 0;
427}
428
1e7e4788
JP		 429static int create_static_call_sections(struct objtool_file *file)
430{
431 struct section *sec, *reloc_sec;
432 struct reloc *reloc;
433 struct static_call_site *site;
434 struct instruction *insn;
435 struct symbol *key_sym;
436 char *key_name, *tmp;
437 int idx;
438
439 sec = find_section_by_name(file->elf, ".static_call_sites");
440 if (sec) {
441 INIT_LIST_HEAD(&file->static_call_list);
442 WARN("file already has .static_call_sites section, skipping");
443 return 0;
444 }
445
446 if (list_empty(&file->static_call_list))
447 return 0;
448
449 idx = 0;
450 list_for_each_entry(insn, &file->static_call_list, static_call_node)
451 idx++;
452
453 sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
454 sizeof(struct static_call_site), idx);
455 if (!sec)
456 return -1;
457
458 reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
459 if (!reloc_sec)
460 return -1;
461
462 idx = 0;
463 list_for_each_entry(insn, &file->static_call_list, static_call_node) {
464
465 site = (struct static_call_site *)sec->data->d_buf + idx;
466 memset(site, 0, sizeof(struct static_call_site));
467
468 /* populate reloc for 'addr' */
469 reloc = malloc(sizeof(*reloc));
44f6a7c0 470
1e7e4788
JP		 471 if (!reloc) {
472 perror("malloc");
473 return -1;
474 }
475 memset(reloc, 0, sizeof(*reloc));
44f6a7c0
JP		 476
477 insn_to_reloc_sym_addend(insn->sec, insn->offset, reloc);
478 if (!reloc->sym) {
479 WARN_FUNC("static call tramp: missing containing symbol",
480 insn->sec, insn->offset);
481 return -1;
482 }
483
1e7e4788
JP		 484 reloc->type = R_X86_64_PC32;
485 reloc->offset = idx * sizeof(struct static_call_site);
486 reloc->sec = reloc_sec;
487 elf_add_reloc(file->elf, reloc);
488
489 /* find key symbol */
490 key_name = strdup(insn->call_dest->name);
491 if (!key_name) {
492 perror("strdup");
493 return -1;
494 }
495 if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
496 STATIC_CALL_TRAMP_PREFIX_LEN)) {
497 WARN("static_call: trampoline name malformed: %s", key_name);
498 return -1;
499 }
500 tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
501 memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
502
503 key_sym = find_symbol_by_name(file->elf, tmp);
504 if (!key_sym) {
505 WARN("static_call: can't find static_call_key symbol: %s", tmp);
506 return -1;
507 }
508 free(key_name);
509
510 /* populate reloc for 'key' */
511 reloc = malloc(sizeof(*reloc));
512 if (!reloc) {
513 perror("malloc");
514 return -1;
515 }
516 memset(reloc, 0, sizeof(*reloc));
517 reloc->sym = key_sym;
5b06fd3b 518 reloc->addend = is_sibling_call(insn) ? STATIC_CALL_SITE_TAIL : 0;
1e7e4788
JP		 519 reloc->type = R_X86_64_PC32;
520 reloc->offset = idx * sizeof(struct static_call_site) + 4;
521 reloc->sec = reloc_sec;
522 elf_add_reloc(file->elf, reloc);
523
524 idx++;
525 }
526
527 if (elf_rebuild_reloc_section(file->elf, reloc_sec))
528 return -1;
529
530 return 0;
531}
532
dcc914f4
JP		 533/*
534 * Warnings shouldn't be reported for ignored functions.
535 */
536static void add_ignores(struct objtool_file *file)
537{
538 struct instruction *insn;
539 struct section *sec;
540 struct symbol *func;
f1974222 541 struct reloc *reloc;
dcc914f4 542
aaf5c623
PZ		 543 sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
544 if (!sec)
545 return;
dcc914f4 546
f1974222
MH		 547 list_for_each_entry(reloc, &sec->reloc_list, list) {
548 switch (reloc->sym->type) {
aaf5c623 549 case STT_FUNC:
f1974222 550 func = reloc->sym;
aaf5c623
PZ		 551 break;
552
553 case STT_SECTION:
f1974222 554 func = find_func_by_offset(reloc->sym->sec, reloc->addend);
7acfe531 555 if (!func)
dcc914f4 556 continue;
aaf5c623 557 break;
dcc914f4 558
aaf5c623 559 default:
f1974222 560 WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type);
aaf5c623 561 continue;
dcc914f4 562 }
aaf5c623 563
f0f70adb 564 func_for_each_insn(file, func, insn)
aaf5c623 565 insn->ignore = true;
dcc914f4
JP		 566 }
567}
568
ea24213d
PZ		 569/*
570 * This is a whitelist of functions that is allowed to be called with AC set.
571 * The list is meant to be minimal and only contains compiler instrumentation
572 * ABI and a few functions used to implement *_{to,from}_user() functions.
573 *
574 * These functions must not directly change AC, but may PUSHF/POPF.
575 */
576static const char *uaccess_safe_builtin[] = {
577 /* KASAN */
578 "kasan_report",
579 "check_memory_region",
580 /* KASAN out-of-line */
581 "__asan_loadN_noabort",
582 "__asan_load1_noabort",
583 "__asan_load2_noabort",
584 "__asan_load4_noabort",
585 "__asan_load8_noabort",
586 "__asan_load16_noabort",
587 "__asan_storeN_noabort",
588 "__asan_store1_noabort",
589 "__asan_store2_noabort",
590 "__asan_store4_noabort",
591 "__asan_store8_noabort",
592 "__asan_store16_noabort",
b0b8e56b
JH		 593 "__kasan_check_read",
594 "__kasan_check_write",
ea24213d
PZ		 595 /* KASAN in-line */
596 "__asan_report_load_n_noabort",
597 "__asan_report_load1_noabort",
598 "__asan_report_load2_noabort",
599 "__asan_report_load4_noabort",
600 "__asan_report_load8_noabort",
601 "__asan_report_load16_noabort",
602 "__asan_report_store_n_noabort",
603 "__asan_report_store1_noabort",
604 "__asan_report_store2_noabort",
605 "__asan_report_store4_noabort",
606 "__asan_report_store8_noabort",
607 "__asan_report_store16_noabort",
5f5c9712 608 /* KCSAN */
9967683c 609 "__kcsan_check_access",
5f5c9712
ME		 610 "kcsan_found_watchpoint",
611 "kcsan_setup_watchpoint",
9967683c 612 "kcsan_check_scoped_accesses",
50a19ad4
ME		 613 "kcsan_disable_current",
614 "kcsan_enable_current_nowarn",
5f5c9712
ME		 615 /* KCSAN/TSAN */
616 "__tsan_func_entry",
617 "__tsan_func_exit",
618 "__tsan_read_range",
619 "__tsan_write_range",
620 "__tsan_read1",
621 "__tsan_read2",
622 "__tsan_read4",
623 "__tsan_read8",
624 "__tsan_read16",
625 "__tsan_write1",
626 "__tsan_write2",
627 "__tsan_write4",
628 "__tsan_write8",
629 "__tsan_write16",
a81b3759
ME		 630 "__tsan_read_write1",
631 "__tsan_read_write2",
632 "__tsan_read_write4",
633 "__tsan_read_write8",
634 "__tsan_read_write16",
883957b1
ME		 635 "__tsan_atomic8_load",
636 "__tsan_atomic16_load",
637 "__tsan_atomic32_load",
638 "__tsan_atomic64_load",
639 "__tsan_atomic8_store",
640 "__tsan_atomic16_store",
641 "__tsan_atomic32_store",
642 "__tsan_atomic64_store",
643 "__tsan_atomic8_exchange",
644 "__tsan_atomic16_exchange",
645 "__tsan_atomic32_exchange",
646 "__tsan_atomic64_exchange",
647 "__tsan_atomic8_fetch_add",
648 "__tsan_atomic16_fetch_add",
649 "__tsan_atomic32_fetch_add",
650 "__tsan_atomic64_fetch_add",
651 "__tsan_atomic8_fetch_sub",
652 "__tsan_atomic16_fetch_sub",
653 "__tsan_atomic32_fetch_sub",
654 "__tsan_atomic64_fetch_sub",
655 "__tsan_atomic8_fetch_and",
656 "__tsan_atomic16_fetch_and",
657 "__tsan_atomic32_fetch_and",
658 "__tsan_atomic64_fetch_and",
659 "__tsan_atomic8_fetch_or",
660 "__tsan_atomic16_fetch_or",
661 "__tsan_atomic32_fetch_or",
662 "__tsan_atomic64_fetch_or",
663 "__tsan_atomic8_fetch_xor",
664 "__tsan_atomic16_fetch_xor",
665 "__tsan_atomic32_fetch_xor",
666 "__tsan_atomic64_fetch_xor",
667 "__tsan_atomic8_fetch_nand",
668 "__tsan_atomic16_fetch_nand",
669 "__tsan_atomic32_fetch_nand",
670 "__tsan_atomic64_fetch_nand",
671 "__tsan_atomic8_compare_exchange_strong",
672 "__tsan_atomic16_compare_exchange_strong",
673 "__tsan_atomic32_compare_exchange_strong",
674 "__tsan_atomic64_compare_exchange_strong",
675 "__tsan_atomic8_compare_exchange_weak",
676 "__tsan_atomic16_compare_exchange_weak",
677 "__tsan_atomic32_compare_exchange_weak",
678 "__tsan_atomic64_compare_exchange_weak",
679 "__tsan_atomic8_compare_exchange_val",
680 "__tsan_atomic16_compare_exchange_val",
681 "__tsan_atomic32_compare_exchange_val",
682 "__tsan_atomic64_compare_exchange_val",
683 "__tsan_atomic_thread_fence",
684 "__tsan_atomic_signal_fence",
ea24213d
PZ		 685 /* KCOV */
686 "write_comp_data",
ae033f08 687 "check_kcov_mode",
ea24213d
PZ		 688 "__sanitizer_cov_trace_pc",
689 "__sanitizer_cov_trace_const_cmp1",
690 "__sanitizer_cov_trace_const_cmp2",
691 "__sanitizer_cov_trace_const_cmp4",
692 "__sanitizer_cov_trace_const_cmp8",
693 "__sanitizer_cov_trace_cmp1",
694 "__sanitizer_cov_trace_cmp2",
695 "__sanitizer_cov_trace_cmp4",
696 "__sanitizer_cov_trace_cmp8",
36b1c700 697 "__sanitizer_cov_trace_switch",
ea24213d
PZ		 698 /* UBSAN */
699 "ubsan_type_mismatch_common",
700 "__ubsan_handle_type_mismatch",
701 "__ubsan_handle_type_mismatch_v1",
9a50dcaf 702 "__ubsan_handle_shift_out_of_bounds",
ea24213d
PZ		 703 /* misc */
704 "csum_partial_copy_generic",
ec6347bb
DW		 705 "copy_mc_fragile",
706 "copy_mc_fragile_handle_tail",
5da8e4a6 707 "copy_mc_enhanced_fast_string",
ea24213d
PZ		 708 "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
709 NULL
710};
711
712static void add_uaccess_safe(struct objtool_file *file)
713{
714 struct symbol *func;
715 const char **name;
716
717 if (!uaccess)
718 return;
719
720 for (name = uaccess_safe_builtin; *name; name++) {
721 func = find_symbol_by_name(file->elf, *name);
722 if (!func)
723 continue;
724
e10cd8fe 725 func->uaccess_safe = true;
dcc914f4
JP		 726 }
727}
728
258c7605
JP		 729/*
730 * FIXME: For now, just ignore any alternatives which add retpolines. This is
731 * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
732 * But it at least allows objtool to understand the control flow *around* the
733 * retpoline.
734 */
ff05ab23 735static int add_ignore_alternatives(struct objtool_file *file)
258c7605
JP		 736{
737 struct section *sec;
f1974222 738 struct reloc *reloc;
258c7605
JP		 739 struct instruction *insn;
740
ff05ab23 741 sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
258c7605
JP		 742 if (!sec)
743 return 0;
744
f1974222
MH		 745 list_for_each_entry(reloc, &sec->reloc_list, list) {
746 if (reloc->sym->type != STT_SECTION) {
258c7605
JP		 747 WARN("unexpected relocation symbol type in %s", sec->name);
748 return -1;
749 }
750
f1974222 751 insn = find_insn(file, reloc->sym->sec, reloc->addend);
258c7605 752 if (!insn) {
ff05ab23 753 WARN("bad .discard.ignore_alts entry");
258c7605
JP		 754 return -1;
755 }
756
757 insn->ignore_alts = true;
758 }
759
760 return 0;
761}
762
dcc914f4
JP		 763/*
764 * Find the destination instructions for all jumps.
765 */
766static int add_jump_destinations(struct objtool_file *file)
767{
768 struct instruction *insn;
f1974222 769 struct reloc *reloc;
dcc914f4
JP		 770 struct section *dest_sec;
771 unsigned long dest_off;
772
773 for_each_insn(file, insn) {
a2296140 774 if (!is_static_jump(insn))
dcc914f4
JP		 775 continue;
776
db6c6a0d 777 if (insn->offset == FAKE_JUMP_OFFSET)
dcc914f4
JP		 778 continue;
779
f1974222 780 reloc = find_reloc_by_dest_range(file->elf, insn->sec,
8b5fa6bc 781 insn->offset, insn->len);
f1974222 782 if (!reloc) {
dcc914f4 783 dest_sec = insn->sec;
bfb08f22 784 dest_off = arch_jump_destination(insn);
f1974222
MH		 785 } else if (reloc->sym->type == STT_SECTION) {
786 dest_sec = reloc->sym->sec;
787 dest_off = arch_dest_reloc_offset(reloc->addend);
788 } else if (reloc->sym->sec->idx) {
789 dest_sec = reloc->sym->sec;
790 dest_off = reloc->sym->sym.st_value +
791 arch_dest_reloc_offset(reloc->addend);
792 } else if (strstr(reloc->sym->name, "_indirect_thunk_")) {
39b73533
JP		 793 /*
794 * Retpoline jumps are really dynamic jumps in
795 * disguise, so convert them accordingly.
796 */
b68b9907
JP		 797 if (insn->type == INSN_JUMP_UNCONDITIONAL)
798 insn->type = INSN_JUMP_DYNAMIC;
799 else
800 insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
801
b5bc2231 802 insn->retpoline_safe = true;
39b73533 803 continue;
dcc914f4 804 } else {
0c1ddd33 805 /* external sibling call */
f1974222 806 insn->call_dest = reloc->sym;
5b06fd3b
PZ		 807 if (insn->call_dest->static_call_tramp) {
808 list_add_tail(&insn->static_call_node,
809 &file->static_call_list);
810 }
dcc914f4
JP		 811 continue;
812 }
813
814 insn->jump_dest = find_insn(file, dest_sec, dest_off);
815 if (!insn->jump_dest) {
816
817 /*
818 * This is a special case where an alt instruction
819 * jumps past the end of the section. These are
820 * handled later in handle_group_alt().
821 */
822 if (!strcmp(insn->sec->name, ".altinstr_replacement"))
823 continue;
824
825 WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
826 insn->sec, insn->offset, dest_sec->name,
827 dest_off);
828 return -1;
829 }
cd77849a
JP		 830
831 /*
54262aa2 832 * Cross-function jump.
cd77849a
JP		 833 */
834 if (insn->func && insn->jump_dest->func &&
54262aa2
PZ		 835 insn->func != insn->jump_dest->func) {
836
837 /*
838 * For GCC 8+, create parent/child links for any cold
839 * subfunctions. This is _mostly_ redundant with a
840 * similar initialization in read_symbols().
841 *
842 * If a function has aliases, we want the *first* such
843 * function in the symbol table to be the subfunction's
844 * parent. In that case we overwrite the
845 * initialization done in read_symbols().
846 *
847 * However this code can't completely replace the
848 * read_symbols() code because this doesn't detect the
849 * case where the parent function's only reference to a
e7c2bc37 850 * subfunction is through a jump table.
54262aa2
PZ		 851 */
852 if (!strstr(insn->func->name, ".cold.") &&
853 strstr(insn->jump_dest->func->name, ".cold.")) {
854 insn->func->cfunc = insn->jump_dest->func;
855 insn->jump_dest->func->pfunc = insn->func;
856
857 } else if (insn->jump_dest->func->pfunc != insn->func->pfunc &&
858 insn->jump_dest->offset == insn->jump_dest->func->offset) {
859
0c1ddd33 860 /* internal sibling call */
54262aa2 861 insn->call_dest = insn->jump_dest->func;
5b06fd3b
PZ		 862 if (insn->call_dest->static_call_tramp) {
863 list_add_tail(&insn->static_call_node,
864 &file->static_call_list);
865 }
54262aa2 866 }
cd77849a 867 }
dcc914f4
JP		 868 }
869
870 return 0;
871}
872
8aa8eb2a
AC		 873static void remove_insn_ops(struct instruction *insn)
874{
875 struct stack_op *op, *tmp;
876
877 list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
878 list_del(&op->list);
879 free(op);
880 }
881}
882
2b232a22
JT		 883static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
884{
885 struct symbol *call_dest;
886
887 call_dest = find_func_by_offset(sec, offset);
888 if (!call_dest)
889 call_dest = find_symbol_by_offset(sec, offset);
890
891 return call_dest;
892}
893
dcc914f4
JP		 894/*
895 * Find the destination instructions for all calls.
896 */
897static int add_call_destinations(struct objtool_file *file)
898{
899 struct instruction *insn;
900 unsigned long dest_off;
f1974222 901 struct reloc *reloc;
dcc914f4
JP		 902
903 for_each_insn(file, insn) {
904 if (insn->type != INSN_CALL)
905 continue;
906
f1974222 907 reloc = find_reloc_by_dest_range(file->elf, insn->sec,
8b5fa6bc 908 insn->offset, insn->len);
f1974222 909 if (!reloc) {
bfb08f22 910 dest_off = arch_jump_destination(insn);
2b232a22 911 insn->call_dest = find_call_destination(insn->sec, dest_off);
a845c7cf 912
7acfe531
JP		 913 if (insn->ignore)
914 continue;
915
916 if (!insn->call_dest) {
8aa8eb2a 917 WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);
dcc914f4
JP		 918 return -1;
919 }
a845c7cf 920
7acfe531
JP		 921 if (insn->func && insn->call_dest->type != STT_FUNC) {
922 WARN_FUNC("unsupported call to non-function",
923 insn->sec, insn->offset);
924 return -1;
925 }
926
f1974222
MH		 927 } else if (reloc->sym->type == STT_SECTION) {
928 dest_off = arch_dest_reloc_offset(reloc->addend);
2b232a22
JT		 929 insn->call_dest = find_call_destination(reloc->sym->sec,
930 dest_off);
7acfe531 931 if (!insn->call_dest) {
bfb08f22 932 WARN_FUNC("can't find call dest symbol at %s+0x%lx",
dcc914f4 933 insn->sec, insn->offset,
f1974222 934 reloc->sym->sec->name,
bfb08f22 935 dest_off);
dcc914f4
JP		 936 return -1;
937 }
938 } else
f1974222 939 insn->call_dest = reloc->sym;
8aa8eb2a 940
0f1441b4
PZ		 941 /*
942 * Many compilers cannot disable KCOV with a function attribute
943 * so they need a little help, NOP out any KCOV calls from noinstr
944 * text.
945 */
946 if (insn->sec->noinstr &&
947 !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) {
d832c005
PZ		 948 if (reloc) {
949 reloc->type = R_NONE;
950 elf_write_reloc(file->elf, reloc);
0f1441b4
PZ		 951 }
952
953 elf_write_insn(file->elf, insn->sec,
954 insn->offset, insn->len,
955 arch_nop_insn(insn->len));
956 insn->type = INSN_NOP;
957 }
958
8aa8eb2a
AC		 959 /*
960 * Whatever stack impact regular CALLs have, should be undone
961 * by the RETURN of the called function.
962 *
963 * Annotated intra-function calls retain the stack_ops but
964 * are converted to JUMP, see read_intra_function_calls().
965 */
966 remove_insn_ops(insn);
dcc914f4
JP		 967 }
968
969 return 0;
970}
971
972/*
973 * The .alternatives section requires some extra special care, over and above
974 * what other special sections require:
975 *
976 * 1. Because alternatives are patched in-place, we need to insert a fake jump
977 * instruction at the end so that validate_branch() skips all the original
978 * replaced instructions when validating the new instruction path.
979 *
980 * 2. An added wrinkle is that the new instruction length might be zero. In
981 * that case the old instructions are replaced with noops. We simulate that
982 * by creating a fake jump as the only new instruction.
983 *
984 * 3. In some cases, the alternative section includes an instruction which
985 * conditionally jumps to the _end_ of the entry. We have to modify these
986 * jumps' destinations to point back to .text rather than the end of the
987 * entry in .altinstr_replacement.
dcc914f4
JP		 988 */
989static int handle_group_alt(struct objtool_file *file,
990 struct special_alt *special_alt,
991 struct instruction *orig_insn,
992 struct instruction **new_insn)
993{
13fab06d 994 static unsigned int alt_group_next_index = 1;
17bc3391 995 struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL;
13fab06d 996 unsigned int alt_group = alt_group_next_index++;
dcc914f4
JP		 997 unsigned long dest_off;
998
999 last_orig_insn = NULL;
1000 insn = orig_insn;
1001 sec_for_each_insn_from(file, insn) {
1002 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
1003 break;
1004
13fab06d 1005 insn->alt_group = alt_group;
dcc914f4
JP		 1006 last_orig_insn = insn;
1007 }
1008
17bc3391
JP		 1009 if (next_insn_same_sec(file, last_orig_insn)) {
1010 fake_jump = malloc(sizeof(*fake_jump));
1011 if (!fake_jump) {
1012 WARN("malloc failed");
1013 return -1;
1014 }
1015 memset(fake_jump, 0, sizeof(*fake_jump));
1016 INIT_LIST_HEAD(&fake_jump->alts);
65ea47dc 1017 INIT_LIST_HEAD(&fake_jump->stack_ops);
e7c0219b 1018 init_cfi_state(&fake_jump->cfi);
17bc3391
JP		 1019
1020 fake_jump->sec = special_alt->new_sec;
e6da9567 1021 fake_jump->offset = FAKE_JUMP_OFFSET;
17bc3391
JP		 1022 fake_jump->type = INSN_JUMP_UNCONDITIONAL;
1023 fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
e6da9567 1024 fake_jump->func = orig_insn->func;
dcc914f4 1025 }
dcc914f4
JP		 1026
1027 if (!special_alt->new_len) {
17bc3391
JP		 1028 if (!fake_jump) {
1029 WARN("%s: empty alternative at end of section",
1030 special_alt->orig_sec->name);
1031 return -1;
1032 }
1033
dcc914f4
JP		 1034 *new_insn = fake_jump;
1035 return 0;
1036 }
1037
1038 last_new_insn = NULL;
13fab06d 1039 alt_group = alt_group_next_index++;
dcc914f4
JP		 1040 insn = *new_insn;
1041 sec_for_each_insn_from(file, insn) {
45245f51
JT		 1042 struct reloc *alt_reloc;
1043
dcc914f4
JP		 1044 if (insn->offset >= special_alt->new_off + special_alt->new_len)
1045 break;
1046
1047 last_new_insn = insn;
1048
a845c7cf 1049 insn->ignore = orig_insn->ignore_alts;
a4d09dde 1050 insn->func = orig_insn->func;
13fab06d 1051 insn->alt_group = alt_group;
a845c7cf 1052
dc419723
JP		 1053 /*
1054 * Since alternative replacement code is copy/pasted by the
1055 * kernel after applying relocations, generally such code can't
1056 * have relative-address relocation references to outside the
1057 * .altinstr_replacement section, unless the arch's
1058 * alternatives code can adjust the relative offsets
1059 * accordingly.
dc419723 1060 */
45245f51
JT		 1061 alt_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
1062 insn->offset, insn->len);
1063 if (alt_reloc &&
1064 !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
dc419723
JP		 1065
1066 WARN_FUNC("unsupported relocation in alternatives section",
1067 insn->sec, insn->offset);
1068 return -1;
1069 }
1070
a2296140 1071 if (!is_static_jump(insn))
dcc914f4
JP		 1072 continue;
1073
1074 if (!insn->immediate)
1075 continue;
1076
bfb08f22 1077 dest_off = arch_jump_destination(insn);
17bc3391
JP		 1078 if (dest_off == special_alt->new_off + special_alt->new_len) {
1079 if (!fake_jump) {
1080 WARN("%s: alternative jump to end of section",
1081 special_alt->orig_sec->name);
1082 return -1;
1083 }
dcc914f4 1084 insn->jump_dest = fake_jump;
17bc3391 1085 }
dcc914f4
JP		 1086
1087 if (!insn->jump_dest) {
1088 WARN_FUNC("can't find alternative jump destination",
1089 insn->sec, insn->offset);
1090 return -1;
1091 }
1092 }
1093
1094 if (!last_new_insn) {
1095 WARN_FUNC("can't find last new alternative instruction",
1096 special_alt->new_sec, special_alt->new_off);
1097 return -1;
1098 }
1099
17bc3391
JP		 1100 if (fake_jump)
1101 list_add(&fake_jump->list, &last_new_insn->list);
dcc914f4
JP		 1102
1103 return 0;
1104}
1105
1106/*
1107 * A jump table entry can either convert a nop to a jump or a jump to a nop.
1108 * If the original instruction is a jump, make the alt entry an effective nop
1109 * by just skipping the original instruction.
1110 */
1111static int handle_jump_alt(struct objtool_file *file,
1112 struct special_alt *special_alt,
1113 struct instruction *orig_insn,
1114 struct instruction **new_insn)
1115{
1116 if (orig_insn->type == INSN_NOP)
1117 return 0;
1118
1119 if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) {
1120 WARN_FUNC("unsupported instruction at jump label",
1121 orig_insn->sec, orig_insn->offset);
1122 return -1;
1123 }
1124
1125 *new_insn = list_next_entry(orig_insn, list);
1126 return 0;
1127}
1128
1129/*
1130 * Read all the special sections which have alternate instructions which can be
1131 * patched in or redirected to at runtime. Each instruction having alternate
1132 * instruction(s) has them added to its insn->alts list, which will be
1133 * traversed in validate_branch().
1134 */
1135static int add_special_section_alts(struct objtool_file *file)
1136{
1137 struct list_head special_alts;
1138 struct instruction *orig_insn, *new_insn;
1139 struct special_alt *special_alt, *tmp;
1140 struct alternative *alt;
1141 int ret;
1142
1143 ret = special_get_alts(file->elf, &special_alts);
1144 if (ret)
1145 return ret;
1146
1147 list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
dcc914f4
JP		 1148
1149 orig_insn = find_insn(file, special_alt->orig_sec,
1150 special_alt->orig_off);
1151 if (!orig_insn) {
1152 WARN_FUNC("special: can't find orig instruction",
1153 special_alt->orig_sec, special_alt->orig_off);
1154 ret = -1;
1155 goto out;
1156 }
1157
1158 new_insn = NULL;
1159 if (!special_alt->group || special_alt->new_len) {
1160 new_insn = find_insn(file, special_alt->new_sec,
1161 special_alt->new_off);
1162 if (!new_insn) {
1163 WARN_FUNC("special: can't find new instruction",
1164 special_alt->new_sec,
1165 special_alt->new_off);
1166 ret = -1;
1167 goto out;
1168 }
1169 }
1170
1171 if (special_alt->group) {
7170cf47
JT		 1172 if (!special_alt->orig_len) {
1173 WARN_FUNC("empty alternative entry",
1174 orig_insn->sec, orig_insn->offset);
1175 continue;
1176 }
1177
dcc914f4
JP		 1178 ret = handle_group_alt(file, special_alt, orig_insn,
1179 &new_insn);
1180 if (ret)
1181 goto out;
1182 } else if (special_alt->jump_or_nop) {
1183 ret = handle_jump_alt(file, special_alt, orig_insn,
1184 &new_insn);
1185 if (ret)
1186 goto out;
1187 }
1188
258c7605
JP		 1189 alt = malloc(sizeof(*alt));
1190 if (!alt) {
1191 WARN("malloc failed");
1192 ret = -1;
1193 goto out;
1194 }
1195
dcc914f4 1196 alt->insn = new_insn;
764eef4b 1197 alt->skip_orig = special_alt->skip_orig;
ea24213d 1198 orig_insn->ignore_alts |= special_alt->skip_alt;
dcc914f4
JP		 1199 list_add_tail(&alt->list, &orig_insn->alts);
1200
1201 list_del(&special_alt->list);
1202 free(special_alt);
1203 }
1204
1205out:
1206 return ret;
1207}
1208
e7c2bc37 1209static int add_jump_table(struct objtool_file *file, struct instruction *insn,
f1974222 1210 struct reloc *table)
dcc914f4 1211{
f1974222 1212 struct reloc *reloc = table;
e7c2bc37 1213 struct instruction *dest_insn;
dcc914f4 1214 struct alternative *alt;
fd35c88b
JP		 1215 struct symbol *pfunc = insn->func->pfunc;
1216 unsigned int prev_offset = 0;
dcc914f4 1217
e7c2bc37 1218 /*
f1974222 1219 * Each @reloc is a switch table relocation which points to the target
e7c2bc37
JP		 1220 * instruction.
1221 */
f1974222 1222 list_for_each_entry_from(reloc, &table->sec->reloc_list, list) {
bd98c813
JH		 1223
1224 /* Check for the end of the table: */
f1974222 1225 if (reloc != table && reloc->jump_table_start)
dcc914f4
JP		 1226 break;
1227
e7c2bc37 1228 /* Make sure the table entries are consecutive: */
f1974222 1229 if (prev_offset && reloc->offset != prev_offset + 8)
fd35c88b
JP		 1230 break;
1231
1232 /* Detect function pointers from contiguous objects: */
f1974222
MH		 1233 if (reloc->sym->sec == pfunc->sec &&
1234 reloc->addend == pfunc->offset)
fd35c88b
JP		 1235 break;
1236
f1974222 1237 dest_insn = find_insn(file, reloc->sym->sec, reloc->addend);
e7c2bc37 1238 if (!dest_insn)
dcc914f4
JP		 1239 break;
1240
e7c2bc37 1241 /* Make sure the destination is in the same function: */
e65050b9 1242 if (!dest_insn->func || dest_insn->func->pfunc != pfunc)
13810435 1243 break;
dcc914f4
JP		 1244
1245 alt = malloc(sizeof(*alt));
1246 if (!alt) {
1247 WARN("malloc failed");
1248 return -1;
1249 }
1250
e7c2bc37 1251 alt->insn = dest_insn;
dcc914f4 1252 list_add_tail(&alt->list, &insn->alts);
f1974222 1253 prev_offset = reloc->offset;
fd35c88b
JP		 1254 }
1255
1256 if (!prev_offset) {
1257 WARN_FUNC("can't find switch jump table",
1258 insn->sec, insn->offset);
1259 return -1;
dcc914f4
JP		 1260 }
1261
1262 return 0;
1263}
1264
1265/*
d871f7b5
RG		 1266 * find_jump_table() - Given a dynamic jump, find the switch jump table
1267 * associated with it.
dcc914f4 1268 */
f1974222 1269static struct reloc *find_jump_table(struct objtool_file *file,
dcc914f4
JP		 1270 struct symbol *func,
1271 struct instruction *insn)
1272{
d871f7b5 1273 struct reloc *table_reloc;
113d4bc9 1274 struct instruction *dest_insn, *orig_insn = insn;
dcc914f4 1275
99ce7962
PZ		 1276 /*
1277 * Backward search using the @first_jump_src links, these help avoid
1278 * much of the 'in between' code. Which avoids us getting confused by
1279 * it.
1280 */
7dec80cc 1281 for (;
1119d265
JP		 1282 insn && insn->func && insn->func->pfunc == func;
1283 insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
99ce7962 1284
7dec80cc 1285 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
dcc914f4
JP		 1286 break;
1287
1288 /* allow small jumps within the range */
1289 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
1290 insn->jump_dest &&
1291 (insn->jump_dest->offset <= insn->offset ||
1292 insn->jump_dest->offset > orig_insn->offset))
1293 break;
1294
d871f7b5 1295 table_reloc = arch_find_switch_table(file, insn);
f1974222 1296 if (!table_reloc)
e7c2bc37 1297 continue;
f1974222 1298 dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
113d4bc9
JP		 1299 if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
1300 continue;
7dec80cc 1301
f1974222 1302 return table_reloc;
dcc914f4
JP		 1303 }
1304
1305 return NULL;
1306}
1307
bd98c813
JH		 1308/*
1309 * First pass: Mark the head of each jump table so that in the next pass,
1310 * we know when a given jump table ends and the next one starts.
1311 */
1312static void mark_func_jump_tables(struct objtool_file *file,
1313 struct symbol *func)
dcc914f4 1314{
bd98c813 1315 struct instruction *insn, *last = NULL;
f1974222 1316 struct reloc *reloc;
dcc914f4 1317
f0f70adb 1318 func_for_each_insn(file, func, insn) {
99ce7962
PZ		 1319 if (!last)
1320 last = insn;
1321
1322 /*
1323 * Store back-pointers for unconditional forward jumps such
e7c2bc37 1324 * that find_jump_table() can back-track using those and
99ce7962
PZ		 1325 * avoid some potentially confusing code.
1326 */
1327 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
1328 insn->offset > last->offset &&
1329 insn->jump_dest->offset > insn->offset &&
1330 !insn->jump_dest->first_jump_src) {
1331
1332 insn->jump_dest->first_jump_src = insn;
1333 last = insn->jump_dest;
1334 }
1335
dcc914f4
JP		 1336 if (insn->type != INSN_JUMP_DYNAMIC)
1337 continue;
1338
f1974222
MH		 1339 reloc = find_jump_table(file, func, insn);
1340 if (reloc) {
1341 reloc->jump_table_start = true;
1342 insn->jump_table = reloc;
dcc914f4 1343 }
dcc914f4 1344 }
bd98c813
JH		 1345}
1346
1347static int add_func_jump_tables(struct objtool_file *file,
1348 struct symbol *func)
1349{
1350 struct instruction *insn;
1351 int ret;
1352
f0f70adb 1353 func_for_each_insn(file, func, insn) {
bd98c813
JH		 1354 if (!insn->jump_table)
1355 continue;
dcc914f4 1356
bd98c813 1357 ret = add_jump_table(file, insn, insn->jump_table);
dcc914f4
JP		 1358 if (ret)
1359 return ret;
1360 }
1361
1362 return 0;
1363}
1364
1365/*
1366 * For some switch statements, gcc generates a jump table in the .rodata
1367 * section which contains a list of addresses within the function to jump to.
1368 * This finds these jump tables and adds them to the insn->alts lists.
1369 */
e7c2bc37 1370static int add_jump_table_alts(struct objtool_file *file)
dcc914f4
JP		 1371{
1372 struct section *sec;
1373 struct symbol *func;
1374 int ret;
1375
4a60aa05 1376 if (!file->rodata)
dcc914f4
JP		 1377 return 0;
1378
baa41469 1379 for_each_sec(file, sec) {
dcc914f4
JP		 1380 list_for_each_entry(func, &sec->symbol_list, list) {
1381 if (func->type != STT_FUNC)
1382 continue;
1383
bd98c813 1384 mark_func_jump_tables(file, func);
e7c2bc37 1385 ret = add_func_jump_tables(file, func);
dcc914f4
JP		 1386 if (ret)
1387 return ret;
1388 }
1389 }
1390
1391 return 0;
1392}
1393
39358a03
JP		 1394static int read_unwind_hints(struct objtool_file *file)
1395{
f1974222
MH		 1396 struct section *sec, *relocsec;
1397 struct reloc *reloc;
39358a03
JP		 1398 struct unwind_hint *hint;
1399 struct instruction *insn;
1400 struct cfi_reg *cfa;
1401 int i;
1402
1403 sec = find_section_by_name(file->elf, ".discard.unwind_hints");
1404 if (!sec)
1405 return 0;
1406
f1974222
MH		 1407 relocsec = sec->reloc;
1408 if (!relocsec) {
39358a03
JP		 1409 WARN("missing .rela.discard.unwind_hints section");
1410 return -1;
1411 }
1412
1413 if (sec->len % sizeof(struct unwind_hint)) {
1414 WARN("struct unwind_hint size mismatch");
1415 return -1;
1416 }
1417
1418 file->hints = true;
1419
1420 for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) {
1421 hint = (struct unwind_hint *)sec->data->d_buf + i;
1422
f1974222
MH		 1423 reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
1424 if (!reloc) {
1425 WARN("can't find reloc for unwind_hints[%d]", i);
39358a03
JP		 1426 return -1;
1427 }
1428
f1974222 1429 insn = find_insn(file, reloc->sym->sec, reloc->addend);
39358a03
JP		 1430 if (!insn) {
1431 WARN("can't find insn for unwind_hints[%d]", i);
1432 return -1;
1433 }
1434
e7c0219b 1435 cfa = &insn->cfi.cfa;
39358a03 1436
c536ed2f 1437 if (hint->type == UNWIND_HINT_TYPE_RET_OFFSET) {
e25eea89 1438 insn->ret_offset = hint->sp_offset;
39358a03
JP		 1439 continue;
1440 }
1441
1442 insn->hint = true;
1443
edea9e6b 1444 if (arch_decode_hint_reg(insn, hint->sp_reg)) {
39358a03
JP		 1445 WARN_FUNC("unsupported unwind_hint sp base reg %d",
1446 insn->sec, insn->offset, hint->sp_reg);
1447 return -1;
1448 }
1449
1450 cfa->offset = hint->sp_offset;
e7c0219b
PZ		 1451 insn->cfi.type = hint->type;
1452 insn->cfi.end = hint->end;
39358a03
JP		 1453 }
1454
1455 return 0;
1456}
1457
b5bc2231
PZ		 1458static int read_retpoline_hints(struct objtool_file *file)
1459{
63474dc4 1460 struct section *sec;
b5bc2231 1461 struct instruction *insn;
f1974222 1462 struct reloc *reloc;
b5bc2231 1463
63474dc4 1464 sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
b5bc2231
PZ		 1465 if (!sec)
1466 return 0;
1467
f1974222
MH		 1468 list_for_each_entry(reloc, &sec->reloc_list, list) {
1469 if (reloc->sym->type != STT_SECTION) {
63474dc4 1470 WARN("unexpected relocation symbol type in %s", sec->name);
b5bc2231
PZ		 1471 return -1;
1472 }
1473
f1974222 1474 insn = find_insn(file, reloc->sym->sec, reloc->addend);
b5bc2231 1475 if (!insn) {
63474dc4 1476 WARN("bad .discard.retpoline_safe entry");
b5bc2231
PZ		 1477 return -1;
1478 }
1479
1480 if (insn->type != INSN_JUMP_DYNAMIC &&
1481 insn->type != INSN_CALL_DYNAMIC) {
63474dc4 1482 WARN_FUNC("retpoline_safe hint not an indirect jump/call",
b5bc2231
PZ		 1483 insn->sec, insn->offset);
1484 return -1;
1485 }
1486
1487 insn->retpoline_safe = true;
1488 }
1489
1490 return 0;
1491}
1492
c4a33939
PZ		 1493static int read_instr_hints(struct objtool_file *file)
1494{
1495 struct section *sec;
1496 struct instruction *insn;
f1974222 1497 struct reloc *reloc;
c4a33939
PZ		 1498
1499 sec = find_section_by_name(file->elf, ".rela.discard.instr_end");
1500 if (!sec)
1501 return 0;
1502
f1974222
MH		 1503 list_for_each_entry(reloc, &sec->reloc_list, list) {
1504 if (reloc->sym->type != STT_SECTION) {
c4a33939
PZ		 1505 WARN("unexpected relocation symbol type in %s", sec->name);
1506 return -1;
1507 }
1508
f1974222 1509 insn = find_insn(file, reloc->sym->sec, reloc->addend);
c4a33939
PZ		 1510 if (!insn) {
1511 WARN("bad .discard.instr_end entry");
1512 return -1;
1513 }
1514
1515 insn->instr--;
1516 }
1517
1518 sec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
1519 if (!sec)
1520 return 0;
1521
f1974222
MH		 1522 list_for_each_entry(reloc, &sec->reloc_list, list) {
1523 if (reloc->sym->type != STT_SECTION) {
c4a33939
PZ		 1524 WARN("unexpected relocation symbol type in %s", sec->name);
1525 return -1;
1526 }
1527
f1974222 1528 insn = find_insn(file, reloc->sym->sec, reloc->addend);
c4a33939
PZ		 1529 if (!insn) {
1530 WARN("bad .discard.instr_begin entry");
1531 return -1;
1532 }
1533
1534 insn->instr++;
1535 }
1536
1537 return 0;
1538}
1539
8aa8eb2a
AC		 1540static int read_intra_function_calls(struct objtool_file *file)
1541{
1542 struct instruction *insn;
1543 struct section *sec;
f1974222 1544 struct reloc *reloc;
8aa8eb2a
AC		 1545
1546 sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
1547 if (!sec)
1548 return 0;
1549
f1974222 1550 list_for_each_entry(reloc, &sec->reloc_list, list) {
8aa8eb2a
AC		 1551 unsigned long dest_off;
1552
f1974222 1553 if (reloc->sym->type != STT_SECTION) {
8aa8eb2a
AC		 1554 WARN("unexpected relocation symbol type in %s",
1555 sec->name);
1556 return -1;
1557 }
1558
f1974222 1559 insn = find_insn(file, reloc->sym->sec, reloc->addend);
8aa8eb2a
AC		 1560 if (!insn) {
1561 WARN("bad .discard.intra_function_call entry");
1562 return -1;
1563 }
1564
1565 if (insn->type != INSN_CALL) {
1566 WARN_FUNC("intra_function_call not a direct call",
1567 insn->sec, insn->offset);
1568 return -1;
1569 }
1570
1571 /*
1572 * Treat intra-function CALLs as JMPs, but with a stack_op.
1573 * See add_call_destinations(), which strips stack_ops from
1574 * normal CALLs.
1575 */
1576 insn->type = INSN_JUMP_UNCONDITIONAL;
1577
1578 dest_off = insn->offset + insn->len + insn->immediate;
1579 insn->jump_dest = find_insn(file, insn->sec, dest_off);
1580 if (!insn->jump_dest) {
1581 WARN_FUNC("can't find call dest at %s+0x%lx",
1582 insn->sec, insn->offset,
1583 insn->sec->name, dest_off);
1584 return -1;
1585 }
1586 }
1587
1588 return 0;
1589}
1590
1e7e4788
JP		 1591static int read_static_call_tramps(struct objtool_file *file)
1592{
1593 struct section *sec;
1594 struct symbol *func;
1595
1596 for_each_sec(file, sec) {
1597 list_for_each_entry(func, &sec->symbol_list, list) {
1598 if (func->bind == STB_GLOBAL &&
1599 !strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
1600 strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
1601 func->static_call_tramp = true;
1602 }
1603 }
1604
1605 return 0;
1606}
1607
4a60aa05
AX		 1608static void mark_rodata(struct objtool_file *file)
1609{
1610 struct section *sec;
1611 bool found = false;
1612
1613 /*
87b512de
JP		 1614 * Search for the following rodata sections, each of which can
1615 * potentially contain jump tables:
1616 *
1617 * - .rodata: can contain GCC switch tables
1618 * - .rodata.<func>: same, if -fdata-sections is being used
1619 * - .rodata..c_jump_table: contains C annotated jump tables
1620 *
1621 * .rodata.str1.* sections are ignored; they don't contain jump tables.
4a60aa05
AX		 1622 */
1623 for_each_sec(file, sec) {
1ee44470
MS		 1624 if (!strncmp(sec->name, ".rodata", 7) &&
1625 !strstr(sec->name, ".str1.")) {
4a60aa05
AX		 1626 sec->rodata = true;
1627 found = true;
1628 }
1629 }
1630
1631 file->rodata = found;
1632}
1633
dcc914f4
JP		 1634static int decode_sections(struct objtool_file *file)
1635{
1636 int ret;
1637
4a60aa05
AX		 1638 mark_rodata(file);
1639
dcc914f4
JP		 1640 ret = decode_instructions(file);
1641 if (ret)
1642 return ret;
1643
1644 ret = add_dead_ends(file);
1645 if (ret)
1646 return ret;
1647
1648 add_ignores(file);
ea24213d 1649 add_uaccess_safe(file);
dcc914f4 1650
ff05ab23 1651 ret = add_ignore_alternatives(file);
258c7605
JP		 1652 if (ret)
1653 return ret;
1654
5b06fd3b
PZ		 1655 ret = read_static_call_tramps(file);
1656 if (ret)
1657 return ret;
1658
dcc914f4
JP		 1659 ret = add_jump_destinations(file);
1660 if (ret)
1661 return ret;
1662
a845c7cf 1663 ret = add_special_section_alts(file);
dcc914f4
JP		 1664 if (ret)
1665 return ret;
1666
8aa8eb2a
AC		 1667 ret = read_intra_function_calls(file);
1668 if (ret)
1669 return ret;
1670
a845c7cf 1671 ret = add_call_destinations(file);
dcc914f4
JP		 1672 if (ret)
1673 return ret;
1674
e7c2bc37 1675 ret = add_jump_table_alts(file);
dcc914f4
JP		 1676 if (ret)
1677 return ret;
1678
39358a03
JP		 1679 ret = read_unwind_hints(file);
1680 if (ret)
1681 return ret;
1682
b5bc2231
PZ		 1683 ret = read_retpoline_hints(file);
1684 if (ret)
1685 return ret;
1686
c4a33939
PZ		 1687 ret = read_instr_hints(file);
1688 if (ret)
1689 return ret;
1690
dcc914f4
JP		 1691 return 0;
1692}
1693
1694static bool is_fentry_call(struct instruction *insn)
1695{
87cf61fe 1696 if (insn->type == INSN_CALL && insn->call_dest &&
dcc914f4
JP		 1697 insn->call_dest->type == STT_NOTYPE &&
1698 !strcmp(insn->call_dest->name, "__fentry__"))
1699 return true;
1700
1701 return false;
1702}
1703
e25eea89 1704static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
dcc914f4 1705{
e25eea89 1706 u8 ret_offset = insn->ret_offset;
e7c0219b 1707 struct cfi_state *cfi = &state->cfi;
baa41469
JP		 1708 int i;
1709
e7c0219b 1710 if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
e25eea89
PZ		 1711 return true;
1712
e7c0219b 1713 if (cfi->cfa.offset != initial_func_cfi.cfa.offset + ret_offset)
baa41469
JP		 1714 return true;
1715
e7c0219b 1716 if (cfi->stack_size != initial_func_cfi.cfa.offset + ret_offset)
e25eea89
PZ		 1717 return true;
1718
c721b3f8
AC		 1719 /*
1720 * If there is a ret offset hint then don't check registers
1721 * because a callee-saved register might have been pushed on
1722 * the stack.
1723 */
1724 if (ret_offset)
1725 return false;
1726
e25eea89 1727 for (i = 0; i < CFI_NUM_REGS; i++) {
e7c0219b
PZ		 1728 if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
1729 cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
baa41469 1730 return true;
e25eea89 1731 }
baa41469
JP		 1732
1733 return false;
1734}
1735
fb084fde
JT		 1736static bool check_reg_frame_pos(const struct cfi_reg *reg,
1737 int expected_offset)
1738{
1739 return reg->base == CFI_CFA &&
1740 reg->offset == expected_offset;
1741}
1742
baa41469
JP		 1743static bool has_valid_stack_frame(struct insn_state *state)
1744{
e7c0219b
PZ		 1745 struct cfi_state *cfi = &state->cfi;
1746
fb084fde
JT		 1747 if (cfi->cfa.base == CFI_BP &&
1748 check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
1749 check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
baa41469
JP		 1750 return true;
1751
e7c0219b 1752 if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
baa41469
JP		 1753 return true;
1754
1755 return false;
dcc914f4
JP		 1756}
1757
e7c0219b
PZ		 1758static int update_cfi_state_regs(struct instruction *insn,
1759 struct cfi_state *cfi,
65ea47dc 1760 struct stack_op *op)
627fce14 1761{
e7c0219b 1762 struct cfi_reg *cfa = &cfi->cfa;
627fce14 1763
d8dd25a4 1764 if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
627fce14
JP		 1765 return 0;
1766
1767 /* push */
ea24213d 1768 if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
627fce14
JP		 1769 cfa->offset += 8;
1770
1771 /* pop */
ea24213d 1772 if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
627fce14
JP		 1773 cfa->offset -= 8;
1774
1775 /* add immediate to sp */
1776 if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
1777 op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
1778 cfa->offset -= op->src.offset;
1779
1780 return 0;
1781}
1782
e7c0219b 1783static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
dcc914f4 1784{
bf4d1a83 1785 if (arch_callee_saved_reg(reg) &&
e7c0219b
PZ		 1786 cfi->regs[reg].base == CFI_UNDEFINED) {
1787 cfi->regs[reg].base = base;
1788 cfi->regs[reg].offset = offset;
baa41469 1789 }
dcc914f4
JP		 1790}
1791
e7c0219b 1792static void restore_reg(struct cfi_state *cfi, unsigned char reg)
dcc914f4 1793{
e7c0219b
PZ		 1794 cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
1795 cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
baa41469
JP		 1796}
1797
1798/*
1799 * A note about DRAP stack alignment:
1800 *
1801 * GCC has the concept of a DRAP register, which is used to help keep track of
1802 * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
1803 * register. The typical DRAP pattern is:
1804 *
1805 * 4c 8d 54 24 08 lea 0x8(%rsp),%r10
1806 * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
1807 * 41 ff 72 f8 pushq -0x8(%r10)
1808 * 55 push %rbp
1809 * 48 89 e5 mov %rsp,%rbp
1810 * (more pushes)
1811 * 41 52 push %r10
1812 * ...
1813 * 41 5a pop %r10
1814 * (more pops)
1815 * 5d pop %rbp
1816 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1817 * c3 retq
1818 *
1819 * There are some variations in the epilogues, like:
1820 *
1821 * 5b pop %rbx
1822 * 41 5a pop %r10
1823 * 41 5c pop %r12
1824 * 41 5d pop %r13
1825 * 41 5e pop %r14
1826 * c9 leaveq
1827 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1828 * c3 retq
1829 *
1830 * and:
1831 *
1832 * 4c 8b 55 e8 mov -0x18(%rbp),%r10
1833 * 48 8b 5d e0 mov -0x20(%rbp),%rbx
1834 * 4c 8b 65 f0 mov -0x10(%rbp),%r12
1835 * 4c 8b 6d f8 mov -0x8(%rbp),%r13
1836 * c9 leaveq
1837 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1838 * c3 retq
1839 *
1840 * Sometimes r13 is used as the DRAP register, in which case it's saved and
1841 * restored beforehand:
1842 *
1843 * 41 55 push %r13
1844 * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
1845 * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
1846 * ...
1847 * 49 8d 65 f0 lea -0x10(%r13),%rsp
1848 * 41 5d pop %r13
1849 * c3 retq
1850 */
e7c0219b 1851static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
65ea47dc 1852 struct stack_op *op)
baa41469 1853{
e7c0219b
PZ		 1854 struct cfi_reg *cfa = &cfi->cfa;
1855 struct cfi_reg *regs = cfi->regs;
baa41469
JP		 1856
1857 /* stack operations don't make sense with an undefined CFA */
1858 if (cfa->base == CFI_UNDEFINED) {
1859 if (insn->func) {
1860 WARN_FUNC("undefined stack state", insn->sec, insn->offset);
1861 return -1;
1862 }
1863 return 0;
1864 }
1865
ee819aed
JT		 1866 if (cfi->type == UNWIND_HINT_TYPE_REGS ||
1867 cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
e7c0219b 1868 return update_cfi_state_regs(insn, cfi, op);
627fce14 1869
baa41469
JP		 1870 switch (op->dest.type) {
1871
1872 case OP_DEST_REG:
1873 switch (op->src.type) {
1874
1875 case OP_SRC_REG:
0d0970ee
JP		 1876 if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
1877 cfa->base == CFI_SP &&
fb084fde 1878 check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {
0d0970ee
JP		 1879
1880 /* mov %rsp, %rbp */
1881 cfa->base = op->dest.reg;
e7c0219b 1882 cfi->bp_scratch = false;
0d0970ee 1883 }
dd88a0a0 1884
0d0970ee 1885 else if (op->src.reg == CFI_SP &&
e7c0219b 1886 op->dest.reg == CFI_BP && cfi->drap) {
dd88a0a0 1887
0d0970ee
JP		 1888 /* drap: mov %rsp, %rbp */
1889 regs[CFI_BP].base = CFI_BP;
e7c0219b
PZ		 1890 regs[CFI_BP].offset = -cfi->stack_size;
1891 cfi->bp_scratch = false;
0d0970ee 1892 }
dd88a0a0 1893
0d0970ee
JP		 1894 else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
1895
1896 /*
1897 * mov %rsp, %reg
1898 *
1899 * This is needed for the rare case where GCC
1900 * does:
1901 *
1902 * mov %rsp, %rax
1903 * ...
1904 * mov %rax, %rsp
1905 */
e7c0219b
PZ		 1906 cfi->vals[op->dest.reg].base = CFI_CFA;
1907 cfi->vals[op->dest.reg].offset = -cfi->stack_size;
dd88a0a0
JP		 1908 }
1909
3c1f0583
JP		 1910 else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
1911 cfa->base == CFI_BP) {
1912
1913 /*
1914 * mov %rbp, %rsp
1915 *
1916 * Restore the original stack pointer (Clang).
1917 */
e7c0219b 1918 cfi->stack_size = -cfi->regs[CFI_BP].offset;
3c1f0583
JP		 1919 }
1920
dd88a0a0
JP		 1921 else if (op->dest.reg == cfa->base) {
1922
1923 /* mov %reg, %rsp */
1924 if (cfa->base == CFI_SP &&
e7c0219b 1925 cfi->vals[op->src.reg].base == CFI_CFA) {
dd88a0a0
JP		 1926
1927 /*
1928 * This is needed for the rare case
1929 * where GCC does something dumb like:
1930 *
1931 * lea 0x8(%rsp), %rcx
1932 * ...
1933 * mov %rcx, %rsp
1934 */
e7c0219b
PZ		 1935 cfa->offset = -cfi->vals[op->src.reg].offset;
1936 cfi->stack_size = cfa->offset;
dd88a0a0
JP		 1937
1938 } else {
1939 cfa->base = CFI_UNDEFINED;
1940 cfa->offset = 0;
1941 }
baa41469
JP		 1942 }
1943
1944 break;
1945
1946 case OP_SRC_ADD:
1947 if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
1948
1949 /* add imm, %rsp */
e7c0219b 1950 cfi->stack_size -= op->src.offset;
baa41469
JP		 1951 if (cfa->base == CFI_SP)
1952 cfa->offset -= op->src.offset;
1953 break;
1954 }
1955
1956 if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
1957
1958 /* lea disp(%rbp), %rsp */
e7c0219b 1959 cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
baa41469
JP		 1960 break;
1961 }
1962
468af56a
JT		 1963 if (!cfi->drap && op->src.reg == CFI_SP &&
1964 op->dest.reg == CFI_BP && cfa->base == CFI_SP &&
1965 check_reg_frame_pos(&regs[CFI_BP], -cfa->offset + op->src.offset)) {
1966
1967 /* lea disp(%rsp), %rbp */
1968 cfa->base = CFI_BP;
1969 cfa->offset -= op->src.offset;
1970 cfi->bp_scratch = false;
1971 break;
1972 }
1973
dd88a0a0 1974 if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
baa41469
JP		 1975
1976 /* drap: lea disp(%rsp), %drap */
e7c0219b 1977 cfi->drap_reg = op->dest.reg;
dd88a0a0
JP		 1978
1979 /*
1980 * lea disp(%rsp), %reg
1981 *
1982 * This is needed for the rare case where GCC
1983 * does something dumb like:
1984 *
1985 * lea 0x8(%rsp), %rcx
1986 * ...
1987 * mov %rcx, %rsp
1988 */
e7c0219b
PZ		 1989 cfi->vals[op->dest.reg].base = CFI_CFA;
1990 cfi->vals[op->dest.reg].offset = \
1991 -cfi->stack_size + op->src.offset;
dd88a0a0 1992
baa41469
JP		 1993 break;
1994 }
1995
e7c0219b
PZ		 1996 if (cfi->drap && op->dest.reg == CFI_SP &&
1997 op->src.reg == cfi->drap_reg) {
baa41469
JP		 1998
1999 /* drap: lea disp(%drap), %rsp */
2000 cfa->base = CFI_SP;
e7c0219b
PZ		 2001 cfa->offset = cfi->stack_size = -op->src.offset;
2002 cfi->drap_reg = CFI_UNDEFINED;
2003 cfi->drap = false;
baa41469
JP		 2004 break;
2005 }
2006
e7c0219b 2007 if (op->dest.reg == cfi->cfa.base) {
baa41469
JP		 2008 WARN_FUNC("unsupported stack register modification",
2009 insn->sec, insn->offset);
2010 return -1;
2011 }
2012
2013 break;
2014
2015 case OP_SRC_AND:
2016 if (op->dest.reg != CFI_SP ||
e7c0219b
PZ		 2017 (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
2018 (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
baa41469
JP		 2019 WARN_FUNC("unsupported stack pointer realignment",
2020 insn->sec, insn->offset);
2021 return -1;
2022 }
2023
e7c0219b 2024 if (cfi->drap_reg != CFI_UNDEFINED) {
baa41469 2025 /* drap: and imm, %rsp */
e7c0219b
PZ		 2026 cfa->base = cfi->drap_reg;
2027 cfa->offset = cfi->stack_size = 0;
2028 cfi->drap = true;
baa41469
JP		 2029 }
2030
2031 /*
2032 * Older versions of GCC (4.8ish) realign the stack
2033 * without DRAP, with a frame pointer.
2034 */
2035
2036 break;
2037
2038 case OP_SRC_POP:
ea24213d 2039 case OP_SRC_POPF:
e7c0219b 2040 if (!cfi->drap && op->dest.reg == cfa->base) {
baa41469
JP		 2041
2042 /* pop %rbp */
2043 cfa->base = CFI_SP;
2044 }
2045
e7c0219b
PZ		 2046 if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
2047 op->dest.reg == cfi->drap_reg &&
2048 cfi->drap_offset == -cfi->stack_size) {
baa41469 2049
bf4d1a83 2050 /* drap: pop %drap */
e7c0219b 2051 cfa->base = cfi->drap_reg;
bf4d1a83 2052 cfa->offset = 0;
e7c0219b 2053 cfi->drap_offset = -1;
baa41469 2054
e7c0219b 2055 } else if (regs[op->dest.reg].offset == -cfi->stack_size) {
baa41469 2056
bf4d1a83 2057 /* pop %reg */
e7c0219b 2058 restore_reg(cfi, op->dest.reg);
baa41469
JP		 2059 }
2060
e7c0219b 2061 cfi->stack_size -= 8;
baa41469
JP		 2062 if (cfa->base == CFI_SP)
2063 cfa->offset -= 8;
2064
2065 break;
2066
2067 case OP_SRC_REG_INDIRECT:
e7c0219b
PZ		 2068 if (cfi->drap && op->src.reg == CFI_BP &&
2069 op->src.offset == cfi->drap_offset) {
bf4d1a83
JP		 2070
2071 /* drap: mov disp(%rbp), %drap */
e7c0219b 2072 cfa->base = cfi->drap_reg;
bf4d1a83 2073 cfa->offset = 0;
e7c0219b 2074 cfi->drap_offset = -1;
bf4d1a83
JP		 2075 }
2076
e7c0219b 2077 if (cfi->drap && op->src.reg == CFI_BP &&
baa41469
JP		 2078 op->src.offset == regs[op->dest.reg].offset) {
2079
2080 /* drap: mov disp(%rbp), %reg */
e7c0219b 2081 restore_reg(cfi, op->dest.reg);
baa41469
JP		 2082
2083 } else if (op->src.reg == cfa->base &&
2084 op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
2085
2086 /* mov disp(%rbp), %reg */
2087 /* mov disp(%rsp), %reg */
e7c0219b 2088 restore_reg(cfi, op->dest.reg);
baa41469
JP		 2089 }
2090
2091 break;
2092
2093 default:
2094 WARN_FUNC("unknown stack-related instruction",
2095 insn->sec, insn->offset);
2096 return -1;
2097 }
2098
2099 break;
2100
2101 case OP_DEST_PUSH:
ea24213d 2102 case OP_DEST_PUSHF:
e7c0219b 2103 cfi->stack_size += 8;
baa41469
JP		 2104 if (cfa->base == CFI_SP)
2105 cfa->offset += 8;
2106
2107 if (op->src.type != OP_SRC_REG)
2108 break;
2109
e7c0219b
PZ		 2110 if (cfi->drap) {
2111 if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
baa41469
JP		 2112
2113 /* drap: push %drap */
2114 cfa->base = CFI_BP_INDIRECT;
e7c0219b 2115 cfa->offset = -cfi->stack_size;
baa41469 2116
bf4d1a83 2117 /* save drap so we know when to restore it */
e7c0219b 2118 cfi->drap_offset = -cfi->stack_size;
baa41469 2119
e7c0219b 2120 } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
baa41469
JP		 2121
2122 /* drap: push %rbp */
e7c0219b 2123 cfi->stack_size = 0;
baa41469 2124
f4f80398 2125 } else {
baa41469
JP		 2126
2127 /* drap: push %reg */
e7c0219b 2128 save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
baa41469
JP		 2129 }
2130
2131 } else {
2132
2133 /* push %reg */
e7c0219b 2134 save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
baa41469
JP		 2135 }
2136
2137 /* detect when asm code uses rbp as a scratch register */
867ac9d7 2138 if (!no_fp && insn->func && op->src.reg == CFI_BP &&
baa41469 2139 cfa->base != CFI_BP)
e7c0219b 2140 cfi->bp_scratch = true;
baa41469
JP		 2141 break;
2142
2143 case OP_DEST_REG_INDIRECT:
2144
e7c0219b
PZ		 2145 if (cfi->drap) {
2146 if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
baa41469
JP		 2147
2148 /* drap: mov %drap, disp(%rbp) */
2149 cfa->base = CFI_BP_INDIRECT;
2150 cfa->offset = op->dest.offset;
2151
bf4d1a83 2152 /* save drap offset so we know when to restore it */
e7c0219b 2153 cfi->drap_offset = op->dest.offset;
f4f80398 2154 } else {
baa41469
JP		 2155
2156 /* drap: mov reg, disp(%rbp) */
e7c0219b 2157 save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
baa41469
JP		 2158 }
2159
2160 } else if (op->dest.reg == cfa->base) {
2161
2162 /* mov reg, disp(%rbp) */
2163 /* mov reg, disp(%rsp) */
e7c0219b
PZ		 2164 save_reg(cfi, op->src.reg, CFI_CFA,
2165 op->dest.offset - cfi->cfa.offset);
baa41469
JP		 2166 }
2167
2168 break;
2169
2170 case OP_DEST_LEAVE:
e7c0219b
PZ		 2171 if ((!cfi->drap && cfa->base != CFI_BP) ||
2172 (cfi->drap && cfa->base != cfi->drap_reg)) {
baa41469
JP		 2173 WARN_FUNC("leave instruction with modified stack frame",
2174 insn->sec, insn->offset);
2175 return -1;
2176 }
2177
2178 /* leave (mov %rbp, %rsp; pop %rbp) */
2179
e7c0219b
PZ		 2180 cfi->stack_size = -cfi->regs[CFI_BP].offset - 8;
2181 restore_reg(cfi, CFI_BP);
baa41469 2182
e7c0219b 2183 if (!cfi->drap) {
baa41469
JP		 2184 cfa->base = CFI_SP;
2185 cfa->offset -= 8;
2186 }
2187
2188 break;
2189
2190 case OP_DEST_MEM:
ea24213d 2191 if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
baa41469
JP		 2192 WARN_FUNC("unknown stack-related memory operation",
2193 insn->sec, insn->offset);
2194 return -1;
2195 }
2196
2197 /* pop mem */
e7c0219b 2198 cfi->stack_size -= 8;
baa41469
JP		 2199 if (cfa->base == CFI_SP)
2200 cfa->offset -= 8;
2201
2202 break;
2203
2204 default:
2205 WARN_FUNC("unknown stack-related instruction",
2206 insn->sec, insn->offset);
2207 return -1;
2208 }
2209
2210 return 0;
2211}
2212
65ea47dc
JT		 2213static int handle_insn_ops(struct instruction *insn, struct insn_state *state)
2214{
2215 struct stack_op *op;
2216
2217 list_for_each_entry(op, &insn->stack_ops, list) {
ab3852ab 2218 struct cfi_state old_cfi = state->cfi;
65ea47dc
JT		 2219 int res;
2220
e7c0219b 2221 res = update_cfi_state(insn, &state->cfi, op);
65ea47dc
JT		 2222 if (res)
2223 return res;
2224
ab3852ab
PZ		 2225 if (insn->alt_group && memcmp(&state->cfi, &old_cfi, sizeof(struct cfi_state))) {
2226 WARN_FUNC("alternative modifies stack", insn->sec, insn->offset);
2227 return -1;
2228 }
2229
65ea47dc
JT		 2230 if (op->dest.type == OP_DEST_PUSHF) {
2231 if (!state->uaccess_stack) {
2232 state->uaccess_stack = 1;
2233 } else if (state->uaccess_stack >> 31) {
2234 WARN_FUNC("PUSHF stack exhausted",
2235 insn->sec, insn->offset);
2236 return 1;
2237 }
2238 state->uaccess_stack <<= 1;
2239 state->uaccess_stack |= state->uaccess;
2240 }
2241
2242 if (op->src.type == OP_SRC_POPF) {
2243 if (state->uaccess_stack) {
2244 state->uaccess = state->uaccess_stack & 1;
2245 state->uaccess_stack >>= 1;
2246 if (state->uaccess_stack == 1)
2247 state->uaccess_stack = 0;
2248 }
2249 }
2250 }
2251
2252 return 0;
2253}
2254
e7c0219b 2255static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
baa41469 2256{
e7c0219b 2257 struct cfi_state *cfi1 = &insn->cfi;
baa41469
JP		 2258 int i;
2259
e7c0219b
PZ		 2260 if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
2261
baa41469
JP		 2262 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
2263 insn->sec, insn->offset,
e7c0219b
PZ		 2264 cfi1->cfa.base, cfi1->cfa.offset,
2265 cfi2->cfa.base, cfi2->cfa.offset);
baa41469 2266
e7c0219b 2267 } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
baa41469 2268 for (i = 0; i < CFI_NUM_REGS; i++) {
e7c0219b 2269 if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
baa41469
JP		 2270 sizeof(struct cfi_reg)))
2271 continue;
2272
2273 WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
2274 insn->sec, insn->offset,
e7c0219b
PZ		 2275 i, cfi1->regs[i].base, cfi1->regs[i].offset,
2276 i, cfi2->regs[i].base, cfi2->regs[i].offset);
baa41469
JP		 2277 break;
2278 }
2279
e7c0219b
PZ		 2280 } else if (cfi1->type != cfi2->type) {
2281
627fce14 2282 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
e7c0219b
PZ		 2283 insn->sec, insn->offset, cfi1->type, cfi2->type);
2284
2285 } else if (cfi1->drap != cfi2->drap ||
2286 (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
2287 (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
627fce14 2288
bf4d1a83 2289 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
baa41469 2290 insn->sec, insn->offset,
e7c0219b
PZ		 2291 cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
2292 cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
baa41469
JP		 2293
2294 } else
2295 return true;
2296
2297 return false;
dcc914f4
JP		 2298}
2299
ea24213d
PZ		 2300static inline bool func_uaccess_safe(struct symbol *func)
2301{
2302 if (func)
e10cd8fe 2303 return func->uaccess_safe;
ea24213d
PZ		 2304
2305 return false;
2306}
2307
0c1ddd33 2308static inline const char *call_dest_name(struct instruction *insn)
ea24213d
PZ		 2309{
2310 if (insn->call_dest)
2311 return insn->call_dest->name;
2312
2313 return "{dynamic}";
2314}
2315
6b643a07
PZ		 2316static inline bool noinstr_call_dest(struct symbol *func)
2317{
2318 /*
2319 * We can't deal with indirect function calls at present;
2320 * assume they're instrumented.
2321 */
2322 if (!func)
2323 return false;
2324
2325 /*
2326 * If the symbol is from a noinstr section; we good.
2327 */
2328 if (func->sec->noinstr)
2329 return true;
2330
2331 /*
2332 * The __ubsan_handle_*() calls are like WARN(), they only happen when
2333 * something 'BAD' happened. At the risk of taking the machine down,
2334 * let them proceed to get the message out.
2335 */
2336 if (!strncmp(func->name, "__ubsan_handle_", 15))
2337 return true;
2338
2339 return false;
2340}
2341
ea24213d
PZ		 2342static int validate_call(struct instruction *insn, struct insn_state *state)
2343{
c4a33939 2344 if (state->noinstr && state->instr <= 0 &&
6b643a07 2345 !noinstr_call_dest(insn->call_dest)) {
c4a33939
PZ		 2346 WARN_FUNC("call to %s() leaves .noinstr.text section",
2347 insn->sec, insn->offset, call_dest_name(insn));
2348 return 1;
2349 }
2350
ea24213d
PZ		 2351 if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
2352 WARN_FUNC("call to %s() with UACCESS enabled",
0c1ddd33 2353 insn->sec, insn->offset, call_dest_name(insn));
ea24213d
PZ		 2354 return 1;
2355 }
2356
2f0f9e9a
PZ		 2357 if (state->df) {
2358 WARN_FUNC("call to %s() with DF set",
0c1ddd33 2359 insn->sec, insn->offset, call_dest_name(insn));
2f0f9e9a
PZ		 2360 return 1;
2361 }
2362
ea24213d
PZ		 2363 return 0;
2364}
2365
54262aa2
PZ		 2366static int validate_sibling_call(struct instruction *insn, struct insn_state *state)
2367{
e25eea89 2368 if (has_modified_stack_frame(insn, state)) {
54262aa2
PZ		 2369 WARN_FUNC("sibling call from callable instruction with modified stack frame",
2370 insn->sec, insn->offset);
2371 return 1;
2372 }
2373
ea24213d 2374 return validate_call(insn, state);
54262aa2
PZ		 2375}
2376
a92e92d1
PZ		 2377static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
2378{
c4a33939
PZ		 2379 if (state->noinstr && state->instr > 0) {
2380 WARN_FUNC("return with instrumentation enabled",
2381 insn->sec, insn->offset);
2382 return 1;
2383 }
2384
a92e92d1
PZ		 2385 if (state->uaccess && !func_uaccess_safe(func)) {
2386 WARN_FUNC("return with UACCESS enabled",
2387 insn->sec, insn->offset);
2388 return 1;
2389 }
2390
2391 if (!state->uaccess && func_uaccess_safe(func)) {
2392 WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function",
2393 insn->sec, insn->offset);
2394 return 1;
2395 }
2396
2397 if (state->df) {
2398 WARN_FUNC("return with DF set",
2399 insn->sec, insn->offset);
2400 return 1;
2401 }
2402
e25eea89 2403 if (func && has_modified_stack_frame(insn, state)) {
a92e92d1
PZ		 2404 WARN_FUNC("return with modified stack frame",
2405 insn->sec, insn->offset);
2406 return 1;
2407 }
2408
e7c0219b 2409 if (state->cfi.bp_scratch) {
b2966952
JP		 2410 WARN_FUNC("BP used as a scratch register",
2411 insn->sec, insn->offset);
a92e92d1
PZ		 2412 return 1;
2413 }
2414
2415 return 0;
2416}
2417
7117f16b
PZ		 2418/*
2419 * Alternatives should not contain any ORC entries, this in turn means they
2420 * should not contain any CFI ops, which implies all instructions should have
2421 * the same same CFI state.
2422 *
2423 * It is possible to constuct alternatives that have unreachable holes that go
2424 * unreported (because they're NOPs), such holes would result in CFI_UNDEFINED
2425 * states which then results in ORC entries, which we just said we didn't want.
2426 *
2427 * Avoid them by copying the CFI entry of the first instruction into the whole
2428 * alternative.
2429 */
2430static void fill_alternative_cfi(struct objtool_file *file, struct instruction *insn)
2431{
2432 struct instruction *first_insn = insn;
2433 int alt_group = insn->alt_group;
2434
2435 sec_for_each_insn_continue(file, insn) {
2436 if (insn->alt_group != alt_group)
2437 break;
2438 insn->cfi = first_insn->cfi;
2439 }
2440}
2441
dcc914f4
JP		 2442/*
2443 * Follow the branch starting at the given instruction, and recursively follow
2444 * any other branches (jumps). Meanwhile, track the frame pointer state at
2445 * each instruction and validate all the rules described in
2446 * tools/objtool/Documentation/stack-validation.txt.
2447 */
c705cecc 2448static int validate_branch(struct objtool_file *file, struct symbol *func,
b7460462 2449 struct instruction *insn, struct insn_state state)
dcc914f4
JP		 2450{
2451 struct alternative *alt;
b7460462 2452 struct instruction *next_insn;
dcc914f4 2453 struct section *sec;
882a0db9 2454 u8 visited;
dcc914f4
JP		 2455 int ret;
2456
dcc914f4 2457 sec = insn->sec;
dcc914f4 2458
dcc914f4 2459 while (1) {
39358a03
JP		 2460 next_insn = next_insn_same_sec(file, insn);
2461
13810435 2462 if (file->c_file && func && insn->func && func != insn->func->pfunc) {
ee97638b
JP		 2463 WARN("%s() falls through to next function %s()",
2464 func->name, insn->func->name);
2465 return 1;
dcc914f4
JP		 2466 }
2467
4855022a
JP		 2468 if (func && insn->ignore) {
2469 WARN_FUNC("BUG: why am I validating an ignored function?",
2470 sec, insn->offset);
12b25729 2471 return 1;
4855022a
JP		 2472 }
2473
882a0db9 2474 visited = 1 << state.uaccess;
dcc914f4 2475 if (insn->visited) {
e7c0219b 2476 if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
dcc914f4 2477 return 1;
dcc914f4 2478
882a0db9 2479 if (insn->visited & visited)
ea24213d 2480 return 0;
dcc914f4
JP		 2481 }
2482
c4a33939
PZ		 2483 if (state.noinstr)
2484 state.instr += insn->instr;
2485
c536ed2f 2486 if (insn->hint)
e7c0219b 2487 state.cfi = insn->cfi;
c536ed2f 2488 else
e7c0219b 2489 insn->cfi = state.cfi;
dcc914f4 2490
882a0db9 2491 insn->visited |= visited;
baa41469 2492
7117f16b 2493 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
764eef4b
PZ		 2494 bool skip_orig = false;
2495
a845c7cf 2496 list_for_each_entry(alt, &insn->alts, list) {
764eef4b
PZ		 2497 if (alt->skip_orig)
2498 skip_orig = true;
2499
c705cecc 2500 ret = validate_branch(file, func, alt->insn, state);
7697eee3
PZ		 2501 if (ret) {
2502 if (backtrace)
2503 BT_FUNC("(alt)", insn);
2504 return ret;
2505 }
a845c7cf 2506 }
764eef4b 2507
7117f16b
PZ		 2508 if (insn->alt_group)
2509 fill_alternative_cfi(file, insn);
2510
764eef4b
PZ		 2511 if (skip_orig)
2512 return 0;
dcc914f4
JP		 2513 }
2514
60041bcd
PZ		 2515 if (handle_insn_ops(insn, &state))
2516 return 1;
2517
dcc914f4
JP		 2518 switch (insn->type) {
2519
dcc914f4 2520 case INSN_RETURN:
a92e92d1 2521 return validate_return(func, insn, &state);
dcc914f4
JP		 2522
2523 case INSN_CALL:
ea24213d
PZ		 2524 case INSN_CALL_DYNAMIC:
2525 ret = validate_call(insn, &state);
2526 if (ret)
2527 return ret;
dcc914f4 2528
c9bab22b
JP		 2529 if (!no_fp && func && !is_fentry_call(insn) &&
2530 !has_valid_stack_frame(&state)) {
dcc914f4
JP		 2531 WARN_FUNC("call without frame pointer save/setup",
2532 sec, insn->offset);
2533 return 1;
2534 }
c9bab22b
JP		 2535
2536 if (dead_end_function(file, insn->call_dest))
2537 return 0;
2538
1e7e4788
JP		 2539 if (insn->type == INSN_CALL && insn->call_dest->static_call_tramp) {
2540 list_add_tail(&insn->static_call_node,
2541 &file->static_call_list);
2542 }
2543
dcc914f4
JP		 2544 break;
2545
2546 case INSN_JUMP_CONDITIONAL:
2547 case INSN_JUMP_UNCONDITIONAL:
0c1ddd33 2548 if (func && is_sibling_call(insn)) {
54262aa2 2549 ret = validate_sibling_call(insn, &state);
dcc914f4 2550 if (ret)
54262aa2 2551 return ret;
4855022a 2552
0c1ddd33 2553 } else if (insn->jump_dest) {
c705cecc
JP		 2554 ret = validate_branch(file, func,
2555 insn->jump_dest, state);
7697eee3
PZ		 2556 if (ret) {
2557 if (backtrace)
2558 BT_FUNC("(branch)", insn);
2559 return ret;
2560 }
4855022a 2561 }
dcc914f4
JP		 2562
2563 if (insn->type == INSN_JUMP_UNCONDITIONAL)
2564 return 0;
2565
2566 break;
2567
2568 case INSN_JUMP_DYNAMIC:
b68b9907 2569 case INSN_JUMP_DYNAMIC_CONDITIONAL:
0c1ddd33 2570 if (func && is_sibling_call(insn)) {
54262aa2
PZ		 2571 ret = validate_sibling_call(insn, &state);
2572 if (ret)
2573 return ret;
dcc914f4
JP		 2574 }
2575
b68b9907
JP		 2576 if (insn->type == INSN_JUMP_DYNAMIC)
2577 return 0;
2578
2579 break;
dcc914f4 2580
39358a03
JP		 2581 case INSN_CONTEXT_SWITCH:
2582 if (func && (!next_insn || !next_insn->hint)) {
2583 WARN_FUNC("unsupported instruction in callable function",
2584 sec, insn->offset);
2585 return 1;
2586 }
2587 return 0;
2588
ea24213d
PZ		 2589 case INSN_STAC:
2590 if (state.uaccess) {
2591 WARN_FUNC("recursive UACCESS enable", sec, insn->offset);
2592 return 1;
2593 }
2594
2595 state.uaccess = true;
2596 break;
2597
2598 case INSN_CLAC:
c705cecc 2599 if (!state.uaccess && func) {
ea24213d
PZ		 2600 WARN_FUNC("redundant UACCESS disable", sec, insn->offset);
2601 return 1;
2602 }
2603
2604 if (func_uaccess_safe(func) && !state.uaccess_stack) {
2605 WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset);
2606 return 1;
2607 }
2608
2609 state.uaccess = false;
baa41469
JP		 2610 break;
2611
2f0f9e9a
PZ		 2612 case INSN_STD:
2613 if (state.df)
2614 WARN_FUNC("recursive STD", sec, insn->offset);
2615
2616 state.df = true;
2617 break;
2618
2619 case INSN_CLD:
c705cecc 2620 if (!state.df && func)
2f0f9e9a
PZ		 2621 WARN_FUNC("redundant CLD", sec, insn->offset);
2622
2623 state.df = false;
baa41469
JP		 2624 break;
2625
dcc914f4
JP		 2626 default:
2627 break;
2628 }
2629
2630 if (insn->dead_end)
2631 return 0;
2632
00d96180 2633 if (!next_insn) {
e7c0219b 2634 if (state.cfi.cfa.base == CFI_UNDEFINED)
00d96180 2635 return 0;
dcc914f4
JP		 2636 WARN("%s: unexpected end of section", sec->name);
2637 return 1;
2638 }
00d96180
JP		 2639
2640 insn = next_insn;
dcc914f4
JP		 2641 }
2642
2643 return 0;
2644}
2645
932f8e98 2646static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
39358a03
JP		 2647{
2648 struct instruction *insn;
39358a03 2649 struct insn_state state;
932f8e98 2650 int ret, warnings = 0;
39358a03
JP		 2651
2652 if (!file->hints)
2653 return 0;
2654
932f8e98 2655 init_insn_state(&state, sec);
39358a03 2656
932f8e98
PZ		 2657 if (sec) {
2658 insn = find_insn(file, sec, 0);
2659 if (!insn)
2660 return 0;
2661 } else {
2662 insn = list_first_entry(&file->insn_list, typeof(*insn), list);
2663 }
2664
2665 while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
39358a03 2666 if (insn->hint && !insn->visited) {
c705cecc 2667 ret = validate_branch(file, insn->func, insn, state);
7697eee3
PZ		 2668 if (ret && backtrace)
2669 BT_FUNC("<=== (hint)", insn);
39358a03
JP		 2670 warnings += ret;
2671 }
932f8e98
PZ		 2672
2673 insn = list_next_entry(insn, list);
39358a03
JP		 2674 }
2675
2676 return warnings;
2677}
2678
b5bc2231
PZ		 2679static int validate_retpoline(struct objtool_file *file)
2680{
2681 struct instruction *insn;
2682 int warnings = 0;
2683
2684 for_each_insn(file, insn) {
2685 if (insn->type != INSN_JUMP_DYNAMIC &&
2686 insn->type != INSN_CALL_DYNAMIC)
2687 continue;
2688
2689 if (insn->retpoline_safe)
2690 continue;
2691
ca41b97e
PZ		 2692 /*
2693 * .init.text code is ran before userspace and thus doesn't
2694 * strictly need retpolines, except for modules which are
2695 * loaded late, they very much do need retpoline in their
2696 * .init.text
2697 */
2698 if (!strcmp(insn->sec->name, ".init.text") && !module)
2699 continue;
2700
b5bc2231
PZ		 2701 WARN_FUNC("indirect %s found in RETPOLINE build",
2702 insn->sec, insn->offset,
2703 insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
2704
2705 warnings++;
2706 }
2707
2708 return warnings;
2709}
2710
dcc914f4
JP		 2711static bool is_kasan_insn(struct instruction *insn)
2712{
2713 return (insn->type == INSN_CALL &&
2714 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
2715}
2716
2717static bool is_ubsan_insn(struct instruction *insn)
2718{
2719 return (insn->type == INSN_CALL &&
2720 !strcmp(insn->call_dest->name,
2721 "__ubsan_handle_builtin_unreachable"));
2722}
2723
14db1f0a 2724static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
dcc914f4
JP		 2725{
2726 int i;
14db1f0a 2727 struct instruction *prev_insn;
dcc914f4 2728
baa41469
JP		 2729 if (insn->ignore || insn->type == INSN_NOP)
2730 return true;
2731
2732 /*
2733 * Ignore any unused exceptions. This can happen when a whitelisted
2734 * function has an exception table entry.
0e2bb2bc
JP		 2735 *
2736 * Also ignore alternative replacement instructions. This can happen
2737 * when a whitelisted function uses one of the ALTERNATIVE macros.
baa41469 2738 */
0e2bb2bc
JP		 2739 if (!strcmp(insn->sec->name, ".fixup") ||
2740 !strcmp(insn->sec->name, ".altinstr_replacement") ||
2741 !strcmp(insn->sec->name, ".altinstr_aux"))
dcc914f4
JP		 2742 return true;
2743
fb136219
JT		 2744 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->offset == FAKE_JUMP_OFFSET)
2745 return true;
2746
bd841d61
JP		 2747 if (!insn->func)
2748 return false;
2749
2750 /*
2751 * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
2752 * __builtin_unreachable(). The BUG() macro has an unreachable() after
2753 * the UD2, which causes GCC's undefined trap logic to emit another UD2
2754 * (or occasionally a JMP to UD2).
14db1f0a
IH		 2755 *
2756 * It may also insert a UD2 after calling a __noreturn function.
bd841d61 2757 */
14db1f0a
IH		 2758 prev_insn = list_prev_entry(insn, list);
2759 if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&
bd841d61
JP		 2760 (insn->type == INSN_BUG ||
2761 (insn->type == INSN_JUMP_UNCONDITIONAL &&
2762 insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
2763 return true;
2764
dcc914f4
JP		 2765 /*
2766 * Check if this (or a subsequent) instruction is related to
2767 * CONFIG_UBSAN or CONFIG_KASAN.
2768 *
2769 * End the search at 5 instructions to avoid going into the weeds.
2770 */
2771 for (i = 0; i < 5; i++) {
2772
2773 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
2774 return true;
2775
fe24e271
JP		 2776 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
2777 if (insn->jump_dest &&
2778 insn->jump_dest->func == insn->func) {
2779 insn = insn->jump_dest;
2780 continue;
2781 }
2782
2783 break;
dcc914f4
JP		 2784 }
2785
baa41469 2786 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
dcc914f4 2787 break;
fe24e271 2788
dcc914f4
JP		 2789 insn = list_next_entry(insn, list);
2790 }
2791
2792 return false;
2793}
2794
4b5e2e7f
PZ		 2795static int validate_symbol(struct objtool_file *file, struct section *sec,
2796 struct symbol *sym, struct insn_state *state)
dcc914f4 2797{
dcc914f4 2798 struct instruction *insn;
4b5e2e7f
PZ		 2799 int ret;
2800
2801 if (!sym->len) {
2802 WARN("%s() is missing an ELF size annotation", sym->name);
2803 return 1;
2804 }
2805
2806 if (sym->pfunc != sym || sym->alias != sym)
2807 return 0;
2808
2809 insn = find_insn(file, sec, sym->offset);
2810 if (!insn || insn->ignore || insn->visited)
2811 return 0;
2812
2813 state->uaccess = sym->uaccess_safe;
2814
2815 ret = validate_branch(file, insn->func, insn, *state);
2816 if (ret && backtrace)
2817 BT_FUNC("<=== (sym)", insn);
2818 return ret;
2819}
2820
2821static int validate_section(struct objtool_file *file, struct section *sec)
2822{
baa41469 2823 struct insn_state state;
4b5e2e7f
PZ		 2824 struct symbol *func;
2825 int warnings = 0;
dcc914f4 2826
350994bf
PZ		 2827 list_for_each_entry(func, &sec->symbol_list, list) {
2828 if (func->type != STT_FUNC)
2829 continue;
e10cd8fe 2830
932f8e98 2831 init_insn_state(&state, sec);
e7c0219b
PZ		 2832 state.cfi.cfa = initial_func_cfi.cfa;
2833 memcpy(&state.cfi.regs, &initial_func_cfi.regs,
0699e551 2834 CFI_NUM_REGS * sizeof(struct cfi_reg));
e7c0219b 2835 state.cfi.stack_size = initial_func_cfi.cfa.offset;
0699e551 2836
4b5e2e7f 2837 warnings += validate_symbol(file, sec, func, &state);
dcc914f4
JP		 2838 }
2839
dcc914f4
JP		 2840 return warnings;
2841}
2842
c4a33939
PZ		 2843static int validate_vmlinux_functions(struct objtool_file *file)
2844{
2845 struct section *sec;
932f8e98 2846 int warnings = 0;
c4a33939
PZ		 2847
2848 sec = find_section_by_name(file->elf, ".noinstr.text");
0cc9ac8d
TG		 2849 if (sec) {
2850 warnings += validate_section(file, sec);
2851 warnings += validate_unwind_hints(file, sec);
2852 }
c4a33939 2853
0cc9ac8d
TG		 2854 sec = find_section_by_name(file->elf, ".entry.text");
2855 if (sec) {
2856 warnings += validate_section(file, sec);
2857 warnings += validate_unwind_hints(file, sec);
2858 }
932f8e98
PZ		 2859
2860 return warnings;
c4a33939
PZ		 2861}
2862
350994bf
PZ		 2863static int validate_functions(struct objtool_file *file)
2864{
2865 struct section *sec;
2866 int warnings = 0;
2867
da837bd6
PZ		 2868 for_each_sec(file, sec) {
2869 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
2870 continue;
2871
350994bf 2872 warnings += validate_section(file, sec);
da837bd6 2873 }
350994bf
PZ		 2874
2875 return warnings;
2876}
2877
baa41469 2878static int validate_reachable_instructions(struct objtool_file *file)
dcc914f4
JP		 2879{
2880 struct instruction *insn;
baa41469
JP		 2881
2882 if (file->ignore_unreachables)
2883 return 0;
dcc914f4
JP		 2884
2885 for_each_insn(file, insn) {
14db1f0a 2886 if (insn->visited || ignore_unreachable_insn(file, insn))
baa41469
JP		 2887 continue;
2888
baa41469
JP		 2889 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
2890 return 1;
dcc914f4
JP		 2891 }
2892
baa41469 2893 return 0;
dcc914f4
JP		 2894}
2895
d44becb9 2896int check(struct objtool_file *file)
dcc914f4 2897{
dcc914f4
JP		 2898 int ret, warnings = 0;
2899
baa41469
JP		 2900 arch_initial_func_cfi_state(&initial_func_cfi);
2901
6545eb03 2902 ret = decode_sections(file);
dcc914f4
JP		 2903 if (ret < 0)
2904 goto out;
2905 warnings += ret;
2906
6545eb03 2907 if (list_empty(&file->insn_list))
dcc914f4 2908 goto out;
dcc914f4 2909
c4a33939 2910 if (vmlinux && !validate_dup) {
6545eb03 2911 ret = validate_vmlinux_functions(file);
c4a33939
PZ		 2912 if (ret < 0)
2913 goto out;
2914
2915 warnings += ret;
2916 goto out;
2917 }
2918
b5bc2231 2919 if (retpoline) {
6545eb03 2920 ret = validate_retpoline(file);
b5bc2231
PZ		 2921 if (ret < 0)
2922 return ret;
2923 warnings += ret;
2924 }
2925
6545eb03 2926 ret = validate_functions(file);
dcc914f4
JP		 2927 if (ret < 0)
2928 goto out;
2929 warnings += ret;
2930
6545eb03 2931 ret = validate_unwind_hints(file, NULL);
39358a03
JP		 2932 if (ret < 0)
2933 goto out;
2934 warnings += ret;
2935
baa41469 2936 if (!warnings) {
6545eb03 2937 ret = validate_reachable_instructions(file);
baa41469
JP		 2938 if (ret < 0)
2939 goto out;
2940 warnings += ret;
2941 }
2942
6545eb03 2943 ret = create_static_call_sections(file);
1e7e4788
JP		 2944 if (ret < 0)
2945 goto out;
2946 warnings += ret;
2947
dcc914f4 2948out:
644592d3
JP		 2949 if (ret < 0) {
2950 /*
2951 * Fatal error. The binary is corrupt or otherwise broken in
2952 * some way, or objtool itself is broken. Fail the kernel
2953 * build.
2954 */
2955 return ret;
2956 }
2957
dcc914f4
JP		 2958 return 0;
2959}
Linux 6.x block layer and io_uring tree(s)