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Merge tag 'vfs-6.7.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
[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>
22682a07 8#include <inttypes.h>
8b946cc3 9#include <sys/mman.h>
dcc914f4 10
7786032e
VG		 11#include <objtool/builtin.h>
12#include <objtool/cfi.h>
13#include <objtool/arch.h>
14#include <objtool/check.h>
15#include <objtool/special.h>
16#include <objtool/warn.h>
17#include <objtool/endianness.h>
dcc914f4 18
f7515d9f 19#include <linux/objtool_types.h>
dcc914f4
JP		 20#include <linux/hashtable.h>
21#include <linux/kernel.h>
1e7e4788 22#include <linux/static_call_types.h>
dcc914f4 23
dcc914f4 24struct alternative {
d5406654 25 struct alternative *next;
dcc914f4 26 struct instruction *insn;
764eef4b 27 bool skip_orig;
dcc914f4
JP		 28};
29
8b946cc3
PZ		 30static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
31
32static struct cfi_init_state initial_func_cfi;
33static struct cfi_state init_cfi;
34static struct cfi_state func_cfi;
1e4b6191 35static struct cfi_state force_undefined_cfi;
dcc914f4 36
627fce14
JP		 37struct instruction *find_insn(struct objtool_file *file,
38 struct section *sec, unsigned long offset)
dcc914f4
JP		 39{
40 struct instruction *insn;
41
87ecb582 42 hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
dcc914f4
JP		 43 if (insn->sec == sec && insn->offset == offset)
44 return insn;
87ecb582 45 }
dcc914f4
JP		 46
47 return NULL;
48}
49
1c34496e
PZ		 50struct instruction *next_insn_same_sec(struct objtool_file *file,
51 struct instruction *insn)
dcc914f4 52{
1c34496e
PZ		 53 if (insn->idx == INSN_CHUNK_MAX)
54 return find_insn(file, insn->sec, insn->offset + insn->len);
dcc914f4 55
1c34496e
PZ		 56 insn++;
57 if (!insn->len)
dcc914f4
JP		 58 return NULL;
59
1c34496e 60 return insn;
dcc914f4
JP		 61}
62
13810435
JP		 63static struct instruction *next_insn_same_func(struct objtool_file *file,
64 struct instruction *insn)
65{
1c34496e 66 struct instruction *next = next_insn_same_sec(file, insn);
dbcdbdfd 67 struct symbol *func = insn_func(insn);
13810435
JP		 68
69 if (!func)
70 return NULL;
71
1c34496e 72 if (next && insn_func(next) == func)
13810435
JP		 73 return next;
74
75 /* Check if we're already in the subfunction: */
76 if (func == func->cfunc)
77 return NULL;
78
79 /* Move to the subfunction: */
80 return find_insn(file, func->cfunc->sec, func->cfunc->offset);
81}
82
1c34496e
PZ		 83static struct instruction *prev_insn_same_sec(struct objtool_file *file,
84 struct instruction *insn)
85{
86 if (insn->idx == 0) {
87 if (insn->prev_len)
88 return find_insn(file, insn->sec, insn->offset - insn->prev_len);
89 return NULL;
90 }
91
92 return insn - 1;
93}
94
1119d265 95static struct instruction *prev_insn_same_sym(struct objtool_file *file,
1c34496e 96 struct instruction *insn)
1119d265 97{
1c34496e 98 struct instruction *prev = prev_insn_same_sec(file, insn);
1119d265 99
1c34496e 100 if (prev && insn_func(prev) == insn_func(insn))
1119d265
JP		 101 return prev;
102
103 return NULL;
104}
105
1c34496e
PZ		 106#define for_each_insn(file, insn) \
107 for (struct section *__sec, *__fake = (struct section *)1; \
108 __fake; __fake = NULL) \
109 for_each_sec(file, __sec) \
110 sec_for_each_insn(file, __sec, insn)
111
f0f70adb 112#define func_for_each_insn(file, func, insn) \
13810435
JP		 113 for (insn = find_insn(file, func->sec, func->offset); \
114 insn; \
115 insn = next_insn_same_func(file, insn))
116
dbf4aeb0
PZ		 117#define sym_for_each_insn(file, sym, insn) \
118 for (insn = find_insn(file, sym->sec, sym->offset); \
1c34496e
PZ		 119 insn && insn->offset < sym->offset + sym->len; \
120 insn = next_insn_same_sec(file, insn))
dcc914f4 121
dbf4aeb0 122#define sym_for_each_insn_continue_reverse(file, sym, insn) \
1c34496e
PZ		 123 for (insn = prev_insn_same_sec(file, insn); \
124 insn && insn->offset >= sym->offset; \
125 insn = prev_insn_same_sec(file, insn))
dcc914f4
JP		 126
127#define sec_for_each_insn_from(file, insn) \
128 for (; insn; insn = next_insn_same_sec(file, insn))
129
baa41469
JP		 130#define sec_for_each_insn_continue(file, insn) \
131 for (insn = next_insn_same_sec(file, insn); insn; \
132 insn = next_insn_same_sec(file, insn))
dcc914f4 133
c6f5dc28
PZ		 134static inline struct symbol *insn_call_dest(struct instruction *insn)
135{
136 if (insn->type == INSN_JUMP_DYNAMIC ||
137 insn->type == INSN_CALL_DYNAMIC)
138 return NULL;
139
140 return insn->_call_dest;
141}
142
143static inline struct reloc *insn_jump_table(struct instruction *insn)
144{
145 if (insn->type == INSN_JUMP_DYNAMIC ||
146 insn->type == INSN_CALL_DYNAMIC)
147 return insn->_jump_table;
148
149 return NULL;
150}
151
99033461
JP		 152static bool is_jump_table_jump(struct instruction *insn)
153{
154 struct alt_group *alt_group = insn->alt_group;
155
c6f5dc28 156 if (insn_jump_table(insn))
99033461
JP		 157 return true;
158
159 /* Retpoline alternative for a jump table? */
160 return alt_group && alt_group->orig_group &&
c6f5dc28 161 insn_jump_table(alt_group->orig_group->first_insn);
99033461
JP		 162}
163
0c1ddd33
JP		 164static bool is_sibling_call(struct instruction *insn)
165{
ecf11ba4 166 /*
5a9c361a 167 * Assume only STT_FUNC calls have jump-tables.
ecf11ba4 168 */
5a9c361a
PZ		 169 if (insn_func(insn)) {
170 /* An indirect jump is either a sibling call or a jump to a table. */
171 if (insn->type == INSN_JUMP_DYNAMIC)
172 return !is_jump_table_jump(insn);
173 }
0c1ddd33 174
c6f5dc28
PZ		 175 /* add_jump_destinations() sets insn_call_dest(insn) for sibling calls. */
176 return (is_static_jump(insn) && insn_call_dest(insn));
0c1ddd33
JP		 177}
178
dcc914f4
JP		 179/*
180 * This checks to see if the given function is a "noreturn" function.
181 *
182 * For global functions which are outside the scope of this object file, we
183 * have to keep a manual list of them.
184 *
185 * For local functions, we have to detect them manually by simply looking for
186 * the lack of a return instruction.
dcc914f4 187 */
8e25c9f8
JP		 188static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
189 int recursion)
dcc914f4
JP		 190{
191 int i;
192 struct instruction *insn;
193 bool empty = true;
194
6245ce4a 195#define NORETURN(func) __stringify(func),
dcc914f4 196 static const char * const global_noreturns[] = {
6245ce4a 197#include "noreturns.h"
dcc914f4 198 };
6245ce4a 199#undef NORETURN
dcc914f4 200
c9bab22b
JP		 201 if (!func)
202 return false;
203
1c47c875 204 if (func->bind == STB_GLOBAL || func->bind == STB_WEAK)
dcc914f4
JP		 205 for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
206 if (!strcmp(func->name, global_noreturns[i]))
8e25c9f8 207 return true;
dcc914f4 208
1c47c875
JP		 209 if (func->bind == STB_WEAK)
210 return false;
211
13810435 212 if (!func->len)
8e25c9f8 213 return false;
dcc914f4 214
13810435 215 insn = find_insn(file, func->sec, func->offset);
5f6e430f 216 if (!insn || !insn_func(insn))
8e25c9f8 217 return false;
13810435 218
f0f70adb 219 func_for_each_insn(file, func, insn) {
dcc914f4
JP		 220 empty = false;
221
222 if (insn->type == INSN_RETURN)
8e25c9f8 223 return false;
dcc914f4
JP		 224 }
225
226 if (empty)
8e25c9f8 227 return false;
dcc914f4
JP		 228
229 /*
230 * A function can have a sibling call instead of a return. In that
231 * case, the function's dead-end status depends on whether the target
232 * of the sibling call returns.
233 */
f0f70adb 234 func_for_each_insn(file, func, insn) {
0c1ddd33 235 if (is_sibling_call(insn)) {
dcc914f4 236 struct instruction *dest = insn->jump_dest;
dcc914f4
JP		 237
238 if (!dest)
239 /* sibling call to another file */
8e25c9f8 240 return false;
dcc914f4 241
0c1ddd33
JP		 242 /* local sibling call */
243 if (recursion == 5) {
244 /*
245 * Infinite recursion: two functions have
246 * sibling calls to each other. This is a very
247 * rare case. It means they aren't dead ends.
248 */
249 return false;
dcc914f4 250 }
dcc914f4 251
dbcdbdfd 252 return __dead_end_function(file, insn_func(dest), recursion+1);
0c1ddd33 253 }
dcc914f4
JP		 254 }
255
8e25c9f8 256 return true;
dcc914f4
JP		 257}
258
8e25c9f8 259static bool dead_end_function(struct objtool_file *file, struct symbol *func)
dcc914f4
JP		 260{
261 return __dead_end_function(file, func, 0);
262}
263
e7c0219b 264static void init_cfi_state(struct cfi_state *cfi)
baa41469
JP		 265{
266 int i;
267
dd88a0a0 268 for (i = 0; i < CFI_NUM_REGS; i++) {
e7c0219b
PZ		 269 cfi->regs[i].base = CFI_UNDEFINED;
270 cfi->vals[i].base = CFI_UNDEFINED;
dd88a0a0 271 }
e7c0219b
PZ		 272 cfi->cfa.base = CFI_UNDEFINED;
273 cfi->drap_reg = CFI_UNDEFINED;
274 cfi->drap_offset = -1;
275}
276
753da417
JP		 277static void init_insn_state(struct objtool_file *file, struct insn_state *state,
278 struct section *sec)
e7c0219b
PZ		 279{
280 memset(state, 0, sizeof(*state));
281 init_cfi_state(&state->cfi);
932f8e98
PZ		 282
283 /*
284 * We need the full vmlinux for noinstr validation, otherwise we can
c6f5dc28
PZ		 285 * not correctly determine insn_call_dest(insn)->sec (external symbols
286 * do not have a section).
932f8e98 287 */
753da417 288 if (opts.link && opts.noinstr && sec)
932f8e98 289 state->noinstr = sec->noinstr;
baa41469
JP		 290}
291
8b946cc3
PZ		 292static struct cfi_state *cfi_alloc(void)
293{
294 struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1);
295 if (!cfi) {
296 WARN("calloc failed");
297 exit(1);
298 }
299 nr_cfi++;
300 return cfi;
301}
302
303static int cfi_bits;
304static struct hlist_head *cfi_hash;
305
306static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2)
307{
308 return memcmp((void *)cfi1 + sizeof(cfi1->hash),
309 (void *)cfi2 + sizeof(cfi2->hash),
310 sizeof(struct cfi_state) - sizeof(struct hlist_node));
311}
312
313static inline u32 cfi_key(struct cfi_state *cfi)
314{
315 return jhash((void *)cfi + sizeof(cfi->hash),
316 sizeof(*cfi) - sizeof(cfi->hash), 0);
317}
318
319static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi)
320{
321 struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
322 struct cfi_state *obj;
323
324 hlist_for_each_entry(obj, head, hash) {
325 if (!cficmp(cfi, obj)) {
326 nr_cfi_cache++;
327 return obj;
328 }
329 }
330
331 obj = cfi_alloc();
332 *obj = *cfi;
333 hlist_add_head(&obj->hash, head);
334
335 return obj;
336}
337
338static void cfi_hash_add(struct cfi_state *cfi)
339{
340 struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
341
342 hlist_add_head(&cfi->hash, head);
343}
344
345static void *cfi_hash_alloc(unsigned long size)
346{
347 cfi_bits = max(10, ilog2(size));
348 cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits,
349 PROT_READ|PROT_WRITE,
350 MAP_PRIVATE|MAP_ANON, -1, 0);
351 if (cfi_hash == (void *)-1L) {
352 WARN("mmap fail cfi_hash");
353 cfi_hash = NULL;
2daf7fab 354 } else if (opts.stats) {
8b946cc3
PZ		 355 printf("cfi_bits: %d\n", cfi_bits);
356 }
357
358 return cfi_hash;
359}
360
361static unsigned long nr_insns;
362static unsigned long nr_insns_visited;
363
dcc914f4
JP		 364/*
365 * Call the arch-specific instruction decoder for all the instructions and add
366 * them to the global instruction list.
367 */
368static int decode_instructions(struct objtool_file *file)
369{
370 struct section *sec;
371 struct symbol *func;
372 unsigned long offset;
373 struct instruction *insn;
374 int ret;
375
baa41469 376 for_each_sec(file, sec) {
1c34496e
PZ		 377 struct instruction *insns = NULL;
378 u8 prev_len = 0;
379 u8 idx = 0;
dcc914f4
JP		 380
381 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
382 continue;
383
627fce14
JP		 384 if (strcmp(sec->name, ".altinstr_replacement") &&
385 strcmp(sec->name, ".altinstr_aux") &&
386 strncmp(sec->name, ".discard.", 9))
387 sec->text = true;
388
0cc9ac8d 389 if (!strcmp(sec->name, ".noinstr.text") ||
951ddecf 390 !strcmp(sec->name, ".entry.text") ||
2b5a0e42 391 !strcmp(sec->name, ".cpuidle.text") ||
79cd2a11 392 !strncmp(sec->name, ".text..__x86.", 13))
c4a33939
PZ		 393 sec->noinstr = true;
394
6644ee84
PZ		 395 /*
396 * .init.text code is ran before userspace and thus doesn't
397 * strictly need retpolines, except for modules which are
398 * loaded late, they very much do need retpoline in their
399 * .init.text
400 */
401 if (!strcmp(sec->name, ".init.text") && !opts.module)
402 sec->init = true;
403
fe255fe6 404 for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
1c34496e
PZ		 405 if (!insns || idx == INSN_CHUNK_MAX) {
406 insns = calloc(sizeof(*insn), INSN_CHUNK_SIZE);
407 if (!insns) {
408 WARN("malloc failed");
409 return -1;
410 }
411 idx = 0;
412 } else {
413 idx++;
baa41469 414 }
1c34496e
PZ		 415 insn = &insns[idx];
416 insn->idx = idx;
baa41469 417
1c34496e 418 INIT_LIST_HEAD(&insn->call_node);
dcc914f4
JP		 419 insn->sec = sec;
420 insn->offset = offset;
1c34496e 421 insn->prev_len = prev_len;
dcc914f4 422
db2b0c5d 423 ret = arch_decode_instruction(file, sec, offset,
fe255fe6 424 sec->sh.sh_size - offset,
20a55463 425 insn);
dcc914f4 426 if (ret)
1c34496e
PZ		 427 return ret;
428
429 prev_len = insn->len;
dcc914f4 430
0e5b613b
PZ		 431 /*
432 * By default, "ud2" is a dead end unless otherwise
433 * annotated, because GCC 7 inserts it for certain
434 * divide-by-zero cases.
435 */
436 if (insn->type == INSN_BUG)
437 insn->dead_end = true;
438
87ecb582 439 hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
1e11f3fd 440 nr_insns++;
dcc914f4
JP		 441 }
442
1c34496e
PZ		 443// printf("%s: last chunk used: %d\n", sec->name, (int)idx);
444
9290e772 445 sec_for_each_sym(sec, func) {
dbcdbdfd
PZ		 446 if (func->type != STT_NOTYPE && func->type != STT_FUNC)
447 continue;
448
cad90e53
NP		 449 if (func->offset == sec->sh.sh_size) {
450 /* Heuristic: likely an "end" symbol */
451 if (func->type == STT_NOTYPE)
452 continue;
453 WARN("%s(): STT_FUNC at end of section",
454 func->name);
455 return -1;
456 }
457
4ae68b26 458 if (func->embedded_insn || func->alias != func)
dcc914f4
JP		 459 continue;
460
461 if (!find_insn(file, sec, func->offset)) {
462 WARN("%s(): can't find starting instruction",
463 func->name);
464 return -1;
465 }
466
08f87a93 467 sym_for_each_insn(file, func, insn) {
dbcdbdfd
PZ		 468 insn->sym = func;
469 if (func->type == STT_FUNC &&
470 insn->type == INSN_ENDBR &&
471 list_empty(&insn->call_node)) {
472 if (insn->offset == func->offset) {
89bc853e 473 list_add_tail(&insn->call_node, &file->endbr_list);
08f87a93
PZ		 474 file->nr_endbr++;
475 } else {
476 file->nr_endbr_int++;
477 }
478 }
479 }
dcc914f4
JP		 480 }
481 }
482
2daf7fab 483 if (opts.stats)
1e11f3fd
PZ		 484 printf("nr_insns: %lu\n", nr_insns);
485
dcc914f4
JP		 486 return 0;
487}
488
db2b0c5d
PZ		 489/*
490 * Read the pv_ops[] .data table to find the static initialized values.
491 */
492static int add_pv_ops(struct objtool_file *file, const char *symname)
493{
494 struct symbol *sym, *func;
495 unsigned long off, end;
a5bd6236 496 struct reloc *reloc;
db2b0c5d
PZ		 497 int idx;
498
499 sym = find_symbol_by_name(file->elf, symname);
500 if (!sym)
501 return 0;
502
503 off = sym->offset;
504 end = off + sym->len;
505 for (;;) {
a5bd6236
JP		 506 reloc = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off);
507 if (!reloc)
db2b0c5d
PZ		 508 break;
509
a5bd6236 510 func = reloc->sym;
db2b0c5d 511 if (func->type == STT_SECTION)
0696b6e3
JP		 512 func = find_symbol_by_offset(reloc->sym->sec,
513 reloc_addend(reloc));
db2b0c5d 514
e4cbb9b8 515 idx = (reloc_offset(reloc) - sym->offset) / sizeof(unsigned long);
db2b0c5d
PZ		 516
517 objtool_pv_add(file, idx, func);
518
e4cbb9b8 519 off = reloc_offset(reloc) + 1;
db2b0c5d
PZ		 520 if (off > end)
521 break;
522 }
523
524 return 0;
525}
526
527/*
528 * Allocate and initialize file->pv_ops[].
529 */
530static int init_pv_ops(struct objtool_file *file)
531{
532 static const char *pv_ops_tables[] = {
533 "pv_ops",
534 "xen_cpu_ops",
535 "xen_irq_ops",
536 "xen_mmu_ops",
537 NULL,
538 };
539 const char *pv_ops;
540 struct symbol *sym;
541 int idx, nr;
542
2daf7fab 543 if (!opts.noinstr)
db2b0c5d
PZ		 544 return 0;
545
546 file->pv_ops = NULL;
547
548 sym = find_symbol_by_name(file->elf, "pv_ops");
549 if (!sym)
550 return 0;
551
552 nr = sym->len / sizeof(unsigned long);
553 file->pv_ops = calloc(sizeof(struct pv_state), nr);
554 if (!file->pv_ops)
555 return -1;
556
557 for (idx = 0; idx < nr; idx++)
558 INIT_LIST_HEAD(&file->pv_ops[idx].targets);
559
560 for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++)
561 add_pv_ops(file, pv_ops);
562
563 return 0;
564}
565
6b5dd716
ST		 566static struct instruction *find_last_insn(struct objtool_file *file,
567 struct section *sec)
568{
569 struct instruction *insn = NULL;
570 unsigned int offset;
fe255fe6 571 unsigned int end = (sec->sh.sh_size > 10) ? sec->sh.sh_size - 10 : 0;
6b5dd716 572
fe255fe6 573 for (offset = sec->sh.sh_size - 1; offset >= end && !insn; offset--)
6b5dd716
ST		 574 insn = find_insn(file, sec, offset);
575
576 return insn;
577}
578
dcc914f4 579/*
649ea4d5 580 * Mark "ud2" instructions and manually annotated dead ends.
dcc914f4
JP		 581 */
582static int add_dead_ends(struct objtool_file *file)
583{
a5bd6236 584 struct section *rsec;
f1974222 585 struct reloc *reloc;
dcc914f4 586 struct instruction *insn;
0696b6e3 587 s64 addend;
dcc914f4 588
649ea4d5
JP		 589 /*
590 * Check for manually annotated dead ends.
591 */
a5bd6236
JP		 592 rsec = find_section_by_name(file->elf, ".rela.discard.unreachable");
593 if (!rsec)
649ea4d5 594 goto reachable;
dcc914f4 595
caa4a6b7 596 for_each_reloc(rsec, reloc) {
0696b6e3 597
f1974222 598 if (reloc->sym->type != STT_SECTION) {
a5bd6236 599 WARN("unexpected relocation symbol type in %s", rsec->name);
dcc914f4
JP		 600 return -1;
601 }
0696b6e3
JP		 602
603 addend = reloc_addend(reloc);
604
605 insn = find_insn(file, reloc->sym->sec, addend);
dcc914f4 606 if (insn)
1c34496e 607 insn = prev_insn_same_sec(file, insn);
0696b6e3 608 else if (addend == reloc->sym->sec->sh.sh_size) {
f1974222 609 insn = find_last_insn(file, reloc->sym->sec);
6b5dd716 610 if (!insn) {
22682a07 611 WARN("can't find unreachable insn at %s+0x%" PRIx64,
0696b6e3 612 reloc->sym->sec->name, addend);
dcc914f4
JP		 613 return -1;
614 }
615 } else {
22682a07 616 WARN("can't find unreachable insn at %s+0x%" PRIx64,
0696b6e3 617 reloc->sym->sec->name, addend);
dcc914f4
JP		 618 return -1;
619 }
620
621 insn->dead_end = true;
622 }
623
649ea4d5
JP		 624reachable:
625 /*
626 * These manually annotated reachable checks are needed for GCC 4.4,
627 * where the Linux unreachable() macro isn't supported. In that case
628 * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
629 * not a dead end.
630 */
a5bd6236
JP		 631 rsec = find_section_by_name(file->elf, ".rela.discard.reachable");
632 if (!rsec)
649ea4d5
JP		 633 return 0;
634
caa4a6b7 635 for_each_reloc(rsec, reloc) {
0696b6e3 636
f1974222 637 if (reloc->sym->type != STT_SECTION) {
a5bd6236 638 WARN("unexpected relocation symbol type in %s", rsec->name);
649ea4d5
JP		 639 return -1;
640 }
0696b6e3
JP		 641
642 addend = reloc_addend(reloc);
643
644 insn = find_insn(file, reloc->sym->sec, addend);
649ea4d5 645 if (insn)
1c34496e 646 insn = prev_insn_same_sec(file, insn);
0696b6e3 647 else if (addend == reloc->sym->sec->sh.sh_size) {
f1974222 648 insn = find_last_insn(file, reloc->sym->sec);
6b5dd716 649 if (!insn) {
22682a07 650 WARN("can't find reachable insn at %s+0x%" PRIx64,
0696b6e3 651 reloc->sym->sec->name, addend);
649ea4d5
JP		 652 return -1;
653 }
654 } else {
22682a07 655 WARN("can't find reachable insn at %s+0x%" PRIx64,
0696b6e3 656 reloc->sym->sec->name, addend);
649ea4d5
JP		 657 return -1;
658 }
659
660 insn->dead_end = false;
661 }
662
dcc914f4
JP		 663 return 0;
664}
665
1e7e4788
JP		 666static int create_static_call_sections(struct objtool_file *file)
667{
1e7e4788 668 struct static_call_site *site;
6342a20e 669 struct section *sec;
1e7e4788
JP		 670 struct instruction *insn;
671 struct symbol *key_sym;
672 char *key_name, *tmp;
673 int idx;
674
675 sec = find_section_by_name(file->elf, ".static_call_sites");
676 if (sec) {
677 INIT_LIST_HEAD(&file->static_call_list);
678 WARN("file already has .static_call_sites section, skipping");
679 return 0;
680 }
681
682 if (list_empty(&file->static_call_list))
683 return 0;
684
685 idx = 0;
43d5430a 686 list_for_each_entry(insn, &file->static_call_list, call_node)
1e7e4788
JP		 687 idx++;
688
6342a20e
JP		 689 sec = elf_create_section_pair(file->elf, ".static_call_sites",
690 sizeof(*site), idx, idx * 2);
1e7e4788
JP		 691 if (!sec)
692 return -1;
693
6342a20e 694 /* Allow modules to modify the low bits of static_call_site::key */
2707579d
JP		 695 sec->sh.sh_flags |= SHF_WRITE;
696
1e7e4788 697 idx = 0;
43d5430a 698 list_for_each_entry(insn, &file->static_call_list, call_node) {
1e7e4788 699
1e7e4788 700 /* populate reloc for 'addr' */
6342a20e
JP		 701 if (!elf_init_reloc_text_sym(file->elf, sec,
702 idx * sizeof(*site), idx * 2,
703 insn->sec, insn->offset))
44f6a7c0 704 return -1;
1e7e4788
JP		 705
706 /* find key symbol */
c6f5dc28 707 key_name = strdup(insn_call_dest(insn)->name);
1e7e4788
JP		 708 if (!key_name) {
709 perror("strdup");
710 return -1;
711 }
712 if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
713 STATIC_CALL_TRAMP_PREFIX_LEN)) {
714 WARN("static_call: trampoline name malformed: %s", key_name);
3da73f10 715 free(key_name);
1e7e4788
JP		 716 return -1;
717 }
718 tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
719 memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
720
721 key_sym = find_symbol_by_name(file->elf, tmp);
722 if (!key_sym) {
2daf7fab 723 if (!opts.module) {
73f44fe1 724 WARN("static_call: can't find static_call_key symbol: %s", tmp);
3da73f10 725 free(key_name);
73f44fe1
JP		 726 return -1;
727 }
728
729 /*
730 * For modules(), the key might not be exported, which
731 * means the module can make static calls but isn't
732 * allowed to change them.
733 *
734 * In that case we temporarily set the key to be the
735 * trampoline address. This is fixed up in
736 * static_call_add_module().
737 */
c6f5dc28 738 key_sym = insn_call_dest(insn);
1e7e4788
JP		 739 }
740 free(key_name);
741
742 /* populate reloc for 'key' */
6342a20e
JP		 743 if (!elf_init_reloc_data_sym(file->elf, sec,
744 idx * sizeof(*site) + 4,
745 (idx * 2) + 1, key_sym,
746 is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
1e7e4788 747 return -1;
1e7e4788
JP		 748
749 idx++;
750 }
751
1e7e4788
JP		 752 return 0;
753}
754
134ab5bd
PZ		 755static int create_retpoline_sites_sections(struct objtool_file *file)
756{
757 struct instruction *insn;
758 struct section *sec;
759 int idx;
760
761 sec = find_section_by_name(file->elf, ".retpoline_sites");
762 if (sec) {
763 WARN("file already has .retpoline_sites, skipping");
764 return 0;
765 }
766
767 idx = 0;
768 list_for_each_entry(insn, &file->retpoline_call_list, call_node)
769 idx++;
770
771 if (!idx)
772 return 0;
773
6342a20e
JP		 774 sec = elf_create_section_pair(file->elf, ".retpoline_sites",
775 sizeof(int), idx, idx);
776 if (!sec)
134ab5bd 777 return -1;
134ab5bd
PZ		 778
779 idx = 0;
780 list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
781
6342a20e
JP		 782 if (!elf_init_reloc_text_sym(file->elf, sec,
783 idx * sizeof(int), idx,
784 insn->sec, insn->offset))
134ab5bd 785 return -1;
134ab5bd
PZ		 786
787 idx++;
788 }
789
790 return 0;
791}
792
d9e9d230
PZ		 793static int create_return_sites_sections(struct objtool_file *file)
794{
795 struct instruction *insn;
796 struct section *sec;
797 int idx;
798
799 sec = find_section_by_name(file->elf, ".return_sites");
800 if (sec) {
801 WARN("file already has .return_sites, skipping");
802 return 0;
803 }
804
805 idx = 0;
806 list_for_each_entry(insn, &file->return_thunk_list, call_node)
807 idx++;
808
809 if (!idx)
810 return 0;
811
6342a20e
JP		 812 sec = elf_create_section_pair(file->elf, ".return_sites",
813 sizeof(int), idx, idx);
814 if (!sec)
d9e9d230 815 return -1;
d9e9d230
PZ		 816
817 idx = 0;
818 list_for_each_entry(insn, &file->return_thunk_list, call_node) {
819
6342a20e
JP		 820 if (!elf_init_reloc_text_sym(file->elf, sec,
821 idx * sizeof(int), idx,
822 insn->sec, insn->offset))
d9e9d230 823 return -1;
d9e9d230
PZ		 824
825 idx++;
826 }
827
828 return 0;
829}
830
89bc853e
PZ		 831static int create_ibt_endbr_seal_sections(struct objtool_file *file)
832{
833 struct instruction *insn;
834 struct section *sec;
835 int idx;
836
837 sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
838 if (sec) {
839 WARN("file already has .ibt_endbr_seal, skipping");
840 return 0;
841 }
842
843 idx = 0;
844 list_for_each_entry(insn, &file->endbr_list, call_node)
845 idx++;
846
2daf7fab 847 if (opts.stats) {
89bc853e
PZ		 848 printf("ibt: ENDBR at function start: %d\n", file->nr_endbr);
849 printf("ibt: ENDBR inside functions: %d\n", file->nr_endbr_int);
850 printf("ibt: superfluous ENDBR: %d\n", idx);
851 }
852
853 if (!idx)
854 return 0;
855
6342a20e
JP		 856 sec = elf_create_section_pair(file->elf, ".ibt_endbr_seal",
857 sizeof(int), idx, idx);
858 if (!sec)
89bc853e 859 return -1;
89bc853e
PZ		 860
861 idx = 0;
862 list_for_each_entry(insn, &file->endbr_list, call_node) {
863
864 int *site = (int *)sec->data->d_buf + idx;
03d7a105 865 struct symbol *sym = insn->sym;
89bc853e
PZ		 866 *site = 0;
867
03d7a105
MK		 868 if (opts.module && sym && sym->type == STT_FUNC &&
869 insn->offset == sym->offset &&
870 (!strcmp(sym->name, "init_module") ||
871 !strcmp(sym->name, "cleanup_module")))
872 WARN("%s(): not an indirect call target", sym->name);
873
6342a20e
JP		 874 if (!elf_init_reloc_text_sym(file->elf, sec,
875 idx * sizeof(int), idx,
876 insn->sec, insn->offset))
89bc853e 877 return -1;
89bc853e
PZ		 878
879 idx++;
880 }
881
882 return 0;
883}
884
9a479f76
PZ		 885static int create_cfi_sections(struct objtool_file *file)
886{
9290e772 887 struct section *sec;
9a479f76 888 struct symbol *sym;
9a479f76
PZ		 889 int idx;
890
891 sec = find_section_by_name(file->elf, ".cfi_sites");
892 if (sec) {
893 INIT_LIST_HEAD(&file->call_list);
894 WARN("file already has .cfi_sites section, skipping");
895 return 0;
896 }
897
898 idx = 0;
9290e772
JP		 899 for_each_sym(file, sym) {
900 if (sym->type != STT_FUNC)
9a479f76
PZ		 901 continue;
902
9290e772
JP		 903 if (strncmp(sym->name, "__cfi_", 6))
904 continue;
9a479f76 905
9290e772 906 idx++;
9a479f76
PZ		 907 }
908
6342a20e
JP		 909 sec = elf_create_section_pair(file->elf, ".cfi_sites",
910 sizeof(unsigned int), idx, idx);
9a479f76
PZ		 911 if (!sec)
912 return -1;
913
914 idx = 0;
9290e772
JP		 915 for_each_sym(file, sym) {
916 if (sym->type != STT_FUNC)
9a479f76
PZ		 917 continue;
918
9290e772
JP		 919 if (strncmp(sym->name, "__cfi_", 6))
920 continue;
9a479f76 921
6342a20e
JP		 922 if (!elf_init_reloc_text_sym(file->elf, sec,
923 idx * sizeof(unsigned int), idx,
924 sym->sec, sym->offset))
9290e772 925 return -1;
9a479f76 926
9290e772 927 idx++;
9a479f76
PZ		 928 }
929
930 return 0;
931}
932
99d00215
PZ		 933static int create_mcount_loc_sections(struct objtool_file *file)
934{
53257a97 935 size_t addr_size = elf_addr_size(file->elf);
99d00215 936 struct instruction *insn;
86ea7f36 937 struct section *sec;
99d00215
PZ		 938 int idx;
939
940 sec = find_section_by_name(file->elf, "__mcount_loc");
941 if (sec) {
942 INIT_LIST_HEAD(&file->mcount_loc_list);
943 WARN("file already has __mcount_loc section, skipping");
944 return 0;
945 }
946
947 if (list_empty(&file->mcount_loc_list))
948 return 0;
949
950 idx = 0;
c509331b 951 list_for_each_entry(insn, &file->mcount_loc_list, call_node)
99d00215
PZ		 952 idx++;
953
6342a20e
JP		 954 sec = elf_create_section_pair(file->elf, "__mcount_loc", addr_size,
955 idx, idx);
99d00215
PZ		 956 if (!sec)
957 return -1;
958
53257a97 959 sec->sh.sh_addralign = addr_size;
86ea7f36 960
99d00215 961 idx = 0;
c509331b 962 list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
99d00215 963
6342a20e 964 struct reloc *reloc;
99d00215 965
6342a20e
JP		 966 reloc = elf_init_reloc_text_sym(file->elf, sec, idx * addr_size, idx,
967 insn->sec, insn->offset);
968 if (!reloc)
99d00215 969 return -1;
99d00215 970
ec24b927 971 set_reloc_type(file->elf, reloc, addr_size == 8 ? R_ABS64 : R_ABS32);
6342a20e
JP		 972
973 idx++;
99d00215
PZ		 974 }
975
99d00215
PZ		 976 return 0;
977}
978
00abd384
PZ		 979static int create_direct_call_sections(struct objtool_file *file)
980{
981 struct instruction *insn;
982 struct section *sec;
00abd384
PZ		 983 int idx;
984
985 sec = find_section_by_name(file->elf, ".call_sites");
986 if (sec) {
987 INIT_LIST_HEAD(&file->call_list);
988 WARN("file already has .call_sites section, skipping");
989 return 0;
990 }
991
992 if (list_empty(&file->call_list))
993 return 0;
994
995 idx = 0;
996 list_for_each_entry(insn, &file->call_list, call_node)
997 idx++;
998
6342a20e
JP		 999 sec = elf_create_section_pair(file->elf, ".call_sites",
1000 sizeof(unsigned int), idx, idx);
00abd384
PZ		 1001 if (!sec)
1002 return -1;
1003
1004 idx = 0;
1005 list_for_each_entry(insn, &file->call_list, call_node) {
1006
6342a20e
JP		 1007 if (!elf_init_reloc_text_sym(file->elf, sec,
1008 idx * sizeof(unsigned int), idx,
1009 insn->sec, insn->offset))
00abd384
PZ		 1010 return -1;
1011
1012 idx++;
1013 }
1014
1015 return 0;
1016}
1017
dcc914f4
JP		 1018/*
1019 * Warnings shouldn't be reported for ignored functions.
1020 */
1021static void add_ignores(struct objtool_file *file)
1022{
1023 struct instruction *insn;
a5bd6236 1024 struct section *rsec;
dcc914f4 1025 struct symbol *func;
f1974222 1026 struct reloc *reloc;
dcc914f4 1027
a5bd6236
JP		 1028 rsec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
1029 if (!rsec)
aaf5c623 1030 return;
dcc914f4 1031
caa4a6b7 1032 for_each_reloc(rsec, reloc) {
f1974222 1033 switch (reloc->sym->type) {
aaf5c623 1034 case STT_FUNC:
f1974222 1035 func = reloc->sym;
aaf5c623
PZ		 1036 break;
1037
1038 case STT_SECTION:
0696b6e3 1039 func = find_func_by_offset(reloc->sym->sec, reloc_addend(reloc));
7acfe531 1040 if (!func)
dcc914f4 1041 continue;
aaf5c623 1042 break;
dcc914f4 1043
aaf5c623 1044 default:
a5bd6236
JP		 1045 WARN("unexpected relocation symbol type in %s: %d",
1046 rsec->name, reloc->sym->type);
aaf5c623 1047 continue;
dcc914f4 1048 }
aaf5c623 1049
f0f70adb 1050 func_for_each_insn(file, func, insn)
aaf5c623 1051 insn->ignore = true;
dcc914f4
JP		 1052 }
1053}
1054
ea24213d
PZ		 1055/*
1056 * This is a whitelist of functions that is allowed to be called with AC set.
1057 * The list is meant to be minimal and only contains compiler instrumentation
1058 * ABI and a few functions used to implement *_{to,from}_user() functions.
1059 *
1060 * These functions must not directly change AC, but may PUSHF/POPF.
1061 */
1062static const char *uaccess_safe_builtin[] = {
1063 /* KASAN */
1064 "kasan_report",
f00748bf 1065 "kasan_check_range",
ea24213d
PZ		 1066 /* KASAN out-of-line */
1067 "__asan_loadN_noabort",
1068 "__asan_load1_noabort",
1069 "__asan_load2_noabort",
1070 "__asan_load4_noabort",
1071 "__asan_load8_noabort",
1072 "__asan_load16_noabort",
1073 "__asan_storeN_noabort",
1074 "__asan_store1_noabort",
1075 "__asan_store2_noabort",
1076 "__asan_store4_noabort",
1077 "__asan_store8_noabort",
1078 "__asan_store16_noabort",
b0b8e56b
JH		 1079 "__kasan_check_read",
1080 "__kasan_check_write",
ea24213d
PZ		 1081 /* KASAN in-line */
1082 "__asan_report_load_n_noabort",
1083 "__asan_report_load1_noabort",
1084 "__asan_report_load2_noabort",
1085 "__asan_report_load4_noabort",
1086 "__asan_report_load8_noabort",
1087 "__asan_report_load16_noabort",
1088 "__asan_report_store_n_noabort",
1089 "__asan_report_store1_noabort",
1090 "__asan_report_store2_noabort",
1091 "__asan_report_store4_noabort",
1092 "__asan_report_store8_noabort",
1093 "__asan_report_store16_noabort",
5f5c9712 1094 /* KCSAN */
9967683c 1095 "__kcsan_check_access",
0525bd82
ME		 1096 "__kcsan_mb",
1097 "__kcsan_wmb",
1098 "__kcsan_rmb",
1099 "__kcsan_release",
5f5c9712
ME		 1100 "kcsan_found_watchpoint",
1101 "kcsan_setup_watchpoint",
9967683c 1102 "kcsan_check_scoped_accesses",
50a19ad4
ME		 1103 "kcsan_disable_current",
1104 "kcsan_enable_current_nowarn",
5f5c9712
ME		 1105 /* KCSAN/TSAN */
1106 "__tsan_func_entry",
1107 "__tsan_func_exit",
1108 "__tsan_read_range",
1109 "__tsan_write_range",
1110 "__tsan_read1",
1111 "__tsan_read2",
1112 "__tsan_read4",
1113 "__tsan_read8",
1114 "__tsan_read16",
1115 "__tsan_write1",
1116 "__tsan_write2",
1117 "__tsan_write4",
1118 "__tsan_write8",
1119 "__tsan_write16",
a81b3759
ME		 1120 "__tsan_read_write1",
1121 "__tsan_read_write2",
1122 "__tsan_read_write4",
1123 "__tsan_read_write8",
1124 "__tsan_read_write16",
63646fcb
ME		 1125 "__tsan_volatile_read1",
1126 "__tsan_volatile_read2",
1127 "__tsan_volatile_read4",
1128 "__tsan_volatile_read8",
1129 "__tsan_volatile_read16",
1130 "__tsan_volatile_write1",
1131 "__tsan_volatile_write2",
1132 "__tsan_volatile_write4",
1133 "__tsan_volatile_write8",
1134 "__tsan_volatile_write16",
883957b1
ME		 1135 "__tsan_atomic8_load",
1136 "__tsan_atomic16_load",
1137 "__tsan_atomic32_load",
1138 "__tsan_atomic64_load",
1139 "__tsan_atomic8_store",
1140 "__tsan_atomic16_store",
1141 "__tsan_atomic32_store",
1142 "__tsan_atomic64_store",
1143 "__tsan_atomic8_exchange",
1144 "__tsan_atomic16_exchange",
1145 "__tsan_atomic32_exchange",
1146 "__tsan_atomic64_exchange",
1147 "__tsan_atomic8_fetch_add",
1148 "__tsan_atomic16_fetch_add",
1149 "__tsan_atomic32_fetch_add",
1150 "__tsan_atomic64_fetch_add",
1151 "__tsan_atomic8_fetch_sub",
1152 "__tsan_atomic16_fetch_sub",
1153 "__tsan_atomic32_fetch_sub",
1154 "__tsan_atomic64_fetch_sub",
1155 "__tsan_atomic8_fetch_and",
1156 "__tsan_atomic16_fetch_and",
1157 "__tsan_atomic32_fetch_and",
1158 "__tsan_atomic64_fetch_and",
1159 "__tsan_atomic8_fetch_or",
1160 "__tsan_atomic16_fetch_or",
1161 "__tsan_atomic32_fetch_or",
1162 "__tsan_atomic64_fetch_or",
1163 "__tsan_atomic8_fetch_xor",
1164 "__tsan_atomic16_fetch_xor",
1165 "__tsan_atomic32_fetch_xor",
1166 "__tsan_atomic64_fetch_xor",
1167 "__tsan_atomic8_fetch_nand",
1168 "__tsan_atomic16_fetch_nand",
1169 "__tsan_atomic32_fetch_nand",
1170 "__tsan_atomic64_fetch_nand",
1171 "__tsan_atomic8_compare_exchange_strong",
1172 "__tsan_atomic16_compare_exchange_strong",
1173 "__tsan_atomic32_compare_exchange_strong",
1174 "__tsan_atomic64_compare_exchange_strong",
1175 "__tsan_atomic8_compare_exchange_weak",
1176 "__tsan_atomic16_compare_exchange_weak",
1177 "__tsan_atomic32_compare_exchange_weak",
1178 "__tsan_atomic64_compare_exchange_weak",
1179 "__tsan_atomic8_compare_exchange_val",
1180 "__tsan_atomic16_compare_exchange_val",
1181 "__tsan_atomic32_compare_exchange_val",
1182 "__tsan_atomic64_compare_exchange_val",
1183 "__tsan_atomic_thread_fence",
1184 "__tsan_atomic_signal_fence",
d5d46924
AB		 1185 "__tsan_unaligned_read16",
1186 "__tsan_unaligned_write16",
ea24213d
PZ		 1187 /* KCOV */
1188 "write_comp_data",
ae033f08 1189 "check_kcov_mode",
ea24213d
PZ		 1190 "__sanitizer_cov_trace_pc",
1191 "__sanitizer_cov_trace_const_cmp1",
1192 "__sanitizer_cov_trace_const_cmp2",
1193 "__sanitizer_cov_trace_const_cmp4",
1194 "__sanitizer_cov_trace_const_cmp8",
1195 "__sanitizer_cov_trace_cmp1",
1196 "__sanitizer_cov_trace_cmp2",
1197 "__sanitizer_cov_trace_cmp4",
1198 "__sanitizer_cov_trace_cmp8",
36b1c700 1199 "__sanitizer_cov_trace_switch",
40b22c9d
AP		 1200 /* KMSAN */
1201 "kmsan_copy_to_user",
1202 "kmsan_report",
1203 "kmsan_unpoison_entry_regs",
1204 "kmsan_unpoison_memory",
1205 "__msan_chain_origin",
1206 "__msan_get_context_state",
1207 "__msan_instrument_asm_store",
1208 "__msan_metadata_ptr_for_load_1",
1209 "__msan_metadata_ptr_for_load_2",
1210 "__msan_metadata_ptr_for_load_4",
1211 "__msan_metadata_ptr_for_load_8",
1212 "__msan_metadata_ptr_for_load_n",
1213 "__msan_metadata_ptr_for_store_1",
1214 "__msan_metadata_ptr_for_store_2",
1215 "__msan_metadata_ptr_for_store_4",
1216 "__msan_metadata_ptr_for_store_8",
1217 "__msan_metadata_ptr_for_store_n",
1218 "__msan_poison_alloca",
1219 "__msan_warning",
ea24213d
PZ		 1220 /* UBSAN */
1221 "ubsan_type_mismatch_common",
1222 "__ubsan_handle_type_mismatch",
1223 "__ubsan_handle_type_mismatch_v1",
9a50dcaf 1224 "__ubsan_handle_shift_out_of_bounds",
f18b0d7e 1225 "__ubsan_handle_load_invalid_value",
7f530fba
JP		 1226 /* STACKLEAK */
1227 "stackleak_track_stack",
ea24213d
PZ		 1228 /* misc */
1229 "csum_partial_copy_generic",
ec6347bb
DW		 1230 "copy_mc_fragile",
1231 "copy_mc_fragile_handle_tail",
5da8e4a6 1232 "copy_mc_enhanced_fast_string",
ea24213d 1233 "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
8c9b6a88 1234 "rep_stos_alternative",
427fda2c 1235 "rep_movs_alternative",
3639a535 1236 "__copy_user_nocache",
ea24213d
PZ		 1237 NULL
1238};
1239
1240static void add_uaccess_safe(struct objtool_file *file)
1241{
1242 struct symbol *func;
1243 const char **name;
1244
2daf7fab 1245 if (!opts.uaccess)
ea24213d
PZ		 1246 return;
1247
1248 for (name = uaccess_safe_builtin; *name; name++) {
1249 func = find_symbol_by_name(file->elf, *name);
1250 if (!func)
1251 continue;
1252
e10cd8fe 1253 func->uaccess_safe = true;
dcc914f4
JP		 1254 }
1255}
1256
258c7605
JP		 1257/*
1258 * FIXME: For now, just ignore any alternatives which add retpolines. This is
1259 * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
1260 * But it at least allows objtool to understand the control flow *around* the
1261 * retpoline.
1262 */
ff05ab23 1263static int add_ignore_alternatives(struct objtool_file *file)
258c7605 1264{
a5bd6236 1265 struct section *rsec;
f1974222 1266 struct reloc *reloc;
258c7605
JP		 1267 struct instruction *insn;
1268
a5bd6236
JP		 1269 rsec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
1270 if (!rsec)
258c7605
JP		 1271 return 0;
1272
caa4a6b7 1273 for_each_reloc(rsec, reloc) {
f1974222 1274 if (reloc->sym->type != STT_SECTION) {
a5bd6236 1275 WARN("unexpected relocation symbol type in %s", rsec->name);
258c7605
JP		 1276 return -1;
1277 }
1278
0696b6e3 1279 insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
258c7605 1280 if (!insn) {
ff05ab23 1281 WARN("bad .discard.ignore_alts entry");
258c7605
JP		 1282 return -1;
1283 }
1284
1285 insn->ignore_alts = true;
1286 }
1287
1288 return 0;
1289}
1290
4ae68b26
PZ		 1291/*
1292 * Symbols that replace INSN_CALL_DYNAMIC, every (tail) call to such a symbol
1293 * will be added to the .retpoline_sites section.
1294 */
530b4ddd
PZ		 1295__weak bool arch_is_retpoline(struct symbol *sym)
1296{
1297 return false;
1298}
1299
4ae68b26
PZ		 1300/*
1301 * Symbols that replace INSN_RETURN, every (tail) call to such a symbol
1302 * will be added to the .return_sites section.
1303 */
d9e9d230
PZ		 1304__weak bool arch_is_rethunk(struct symbol *sym)
1305{
1306 return false;
1307}
1308
4ae68b26
PZ		 1309/*
1310 * Symbols that are embedded inside other instructions, because sometimes crazy
1311 * code exists. These are mostly ignored for validation purposes.
1312 */
1313__weak bool arch_is_embedded_insn(struct symbol *sym)
1314{
1315 return false;
1316}
1317
7bd2a600
PZ		 1318static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
1319{
0932dbe1
PZ		 1320 struct reloc *reloc;
1321
1322 if (insn->no_reloc)
7bd2a600
PZ		 1323 return NULL;
1324
0932dbe1
PZ		 1325 if (!file)
1326 return NULL;
db2b0c5d 1327
0932dbe1
PZ		 1328 reloc = find_reloc_by_dest_range(file->elf, insn->sec,
1329 insn->offset, insn->len);
1330 if (!reloc) {
1331 insn->no_reloc = 1;
1332 return NULL;
7bd2a600
PZ		 1333 }
1334
0932dbe1 1335 return reloc;
7bd2a600
PZ		 1336}
1337
f56dae88
PZ		 1338static void remove_insn_ops(struct instruction *insn)
1339{
3ee88df1 1340 struct stack_op *op, *next;
f56dae88 1341
3ee88df1
PZ		 1342 for (op = insn->stack_ops; op; op = next) {
1343 next = op->next;
f56dae88
PZ		 1344 free(op);
1345 }
3ee88df1 1346 insn->stack_ops = NULL;
f56dae88
PZ		 1347}
1348
dd003ede
PZ		 1349static void annotate_call_site(struct objtool_file *file,
1350 struct instruction *insn, bool sibling)
f56dae88
PZ		 1351{
1352 struct reloc *reloc = insn_reloc(file, insn);
c6f5dc28 1353 struct symbol *sym = insn_call_dest(insn);
f56dae88 1354
dd003ede
PZ		 1355 if (!sym)
1356 sym = reloc->sym;
1357
1358 /*
1359 * Alternative replacement code is just template code which is
1360 * sometimes copied to the original instruction. For now, don't
1361 * annotate it. (In the future we might consider annotating the
1362 * original instruction if/when it ever makes sense to do so.)
1363 */
1364 if (!strcmp(insn->sec->name, ".altinstr_replacement"))
f56dae88
PZ		 1365 return;
1366
dd003ede
PZ		 1367 if (sym->static_call_tramp) {
1368 list_add_tail(&insn->call_node, &file->static_call_list);
1369 return;
f56dae88
PZ		 1370 }
1371
134ab5bd
PZ		 1372 if (sym->retpoline_thunk) {
1373 list_add_tail(&insn->call_node, &file->retpoline_call_list);
1374 return;
1375 }
1376
f56dae88 1377 /*
05098119
ME		 1378 * Many compilers cannot disable KCOV or sanitizer calls with a function
1379 * attribute so they need a little help, NOP out any such calls from
1380 * noinstr text.
f56dae88 1381 */
22102f45 1382 if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
ec24b927
JP		 1383 if (reloc)
1384 set_reloc_type(file->elf, reloc, R_NONE);
f56dae88
PZ		 1385
1386 elf_write_insn(file->elf, insn->sec,
1387 insn->offset, insn->len,
1388 sibling ? arch_ret_insn(insn->len)
1389 : arch_nop_insn(insn->len));
1390
1391 insn->type = sibling ? INSN_RETURN : INSN_NOP;
7a53f408
PZ		 1392
1393 if (sibling) {
1394 /*
1395 * We've replaced the tail-call JMP insn by two new
1396 * insn: RET; INT3, except we only have a single struct
1397 * insn here. Mark it retpoline_safe to avoid the SLS
1398 * warning, instead of adding another insn.
1399 */
1400 insn->retpoline_safe = true;
1401 }
1402
dd003ede 1403 return;
f56dae88
PZ		 1404 }
1405
2daf7fab 1406 if (opts.mcount && sym->fentry) {
f56dae88 1407 if (sibling)
246b2c85 1408 WARN_INSN(insn, "tail call to __fentry__ !?!?");
280981d6 1409 if (opts.mnop) {
ec24b927
JP		 1410 if (reloc)
1411 set_reloc_type(file->elf, reloc, R_NONE);
f56dae88 1412
280981d6
SV		 1413 elf_write_insn(file->elf, insn->sec,
1414 insn->offset, insn->len,
1415 arch_nop_insn(insn->len));
f56dae88 1416
280981d6
SV		 1417 insn->type = INSN_NOP;
1418 }
f56dae88 1419
c509331b 1420 list_add_tail(&insn->call_node, &file->mcount_loc_list);
dd003ede 1421 return;
f56dae88 1422 }
0e5b613b 1423
00abd384
PZ		 1424 if (insn->type == INSN_CALL && !insn->sec->init)
1425 list_add_tail(&insn->call_node, &file->call_list);
1426
0e5b613b
PZ		 1427 if (!sibling && dead_end_function(file, sym))
1428 insn->dead_end = true;
dd003ede
PZ		 1429}
1430
1431static void add_call_dest(struct objtool_file *file, struct instruction *insn,
1432 struct symbol *dest, bool sibling)
1433{
c6f5dc28 1434 insn->_call_dest = dest;
dd003ede
PZ		 1435 if (!dest)
1436 return;
f56dae88
PZ		 1437
1438 /*
1439 * Whatever stack impact regular CALLs have, should be undone
1440 * by the RETURN of the called function.
1441 *
1442 * Annotated intra-function calls retain the stack_ops but
1443 * are converted to JUMP, see read_intra_function_calls().
1444 */
1445 remove_insn_ops(insn);
dd003ede
PZ		 1446
1447 annotate_call_site(file, insn, sibling);
f56dae88
PZ		 1448}
1449
134ab5bd
PZ		 1450static void add_retpoline_call(struct objtool_file *file, struct instruction *insn)
1451{
1452 /*
1453 * Retpoline calls/jumps are really dynamic calls/jumps in disguise,
1454 * so convert them accordingly.
1455 */
1456 switch (insn->type) {
1457 case INSN_CALL:
1458 insn->type = INSN_CALL_DYNAMIC;
1459 break;
1460 case INSN_JUMP_UNCONDITIONAL:
1461 insn->type = INSN_JUMP_DYNAMIC;
1462 break;
1463 case INSN_JUMP_CONDITIONAL:
1464 insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
1465 break;
1466 default:
1467 return;
1468 }
1469
1470 insn->retpoline_safe = true;
1471
1472 /*
1473 * Whatever stack impact regular CALLs have, should be undone
1474 * by the RETURN of the called function.
1475 *
1476 * Annotated intra-function calls retain the stack_ops but
1477 * are converted to JUMP, see read_intra_function_calls().
1478 */
1479 remove_insn_ops(insn);
1480
1481 annotate_call_site(file, insn, false);
1482}
08f87a93 1483
a149180f 1484static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
d9e9d230
PZ		 1485{
1486 /*
1487 * Return thunk tail calls are really just returns in disguise,
1488 * so convert them accordingly.
1489 */
1490 insn->type = INSN_RETURN;
1491 insn->retpoline_safe = true;
1492
a149180f
PZ		 1493 if (add)
1494 list_add_tail(&insn->call_node, &file->return_thunk_list);
d9e9d230
PZ		 1495}
1496
5a9c361a
PZ		 1497static bool is_first_func_insn(struct objtool_file *file,
1498 struct instruction *insn, struct symbol *sym)
08f87a93 1499{
5a9c361a 1500 if (insn->offset == sym->offset)
d139bca4
PZ		 1501 return true;
1502
5a9c361a 1503 /* Allow direct CALL/JMP past ENDBR */
2daf7fab 1504 if (opts.ibt) {
d139bca4
PZ		 1505 struct instruction *prev = prev_insn_same_sym(file, insn);
1506
1507 if (prev && prev->type == INSN_ENDBR &&
5a9c361a 1508 insn->offset == sym->offset + prev->len)
d139bca4
PZ		 1509 return true;
1510 }
1511
1512 return false;
08f87a93
PZ		 1513}
1514
5a9c361a
PZ		 1515/*
1516 * A sibling call is a tail-call to another symbol -- to differentiate from a
1517 * recursive tail-call which is to the same symbol.
1518 */
1519static bool jump_is_sibling_call(struct objtool_file *file,
1520 struct instruction *from, struct instruction *to)
1521{
1522 struct symbol *fs = from->sym;
1523 struct symbol *ts = to->sym;
1524
1525 /* Not a sibling call if from/to a symbol hole */
1526 if (!fs || !ts)
1527 return false;
1528
1529 /* Not a sibling call if not targeting the start of a symbol. */
1530 if (!is_first_func_insn(file, to, ts))
1531 return false;
1532
1533 /* Disallow sibling calls into STT_NOTYPE */
1534 if (ts->type == STT_NOTYPE)
1535 return false;
1536
1537 /* Must not be self to be a sibling */
1538 return fs->pfunc != ts->pfunc;
1539}
1540
dcc914f4
JP		 1541/*
1542 * Find the destination instructions for all jumps.
1543 */
1544static int add_jump_destinations(struct objtool_file *file)
1545{
26ff6041 1546 struct instruction *insn, *jump_dest;
f1974222 1547 struct reloc *reloc;
dcc914f4
JP		 1548 struct section *dest_sec;
1549 unsigned long dest_off;
1550
1551 for_each_insn(file, insn) {
34c861e8
JP		 1552 if (insn->jump_dest) {
1553 /*
1554 * handle_group_alt() may have previously set
1555 * 'jump_dest' for some alternatives.
1556 */
1557 continue;
1558 }
a2296140 1559 if (!is_static_jump(insn))
dcc914f4
JP		 1560 continue;
1561
7bd2a600 1562 reloc = insn_reloc(file, insn);
f1974222 1563 if (!reloc) {
dcc914f4 1564 dest_sec = insn->sec;
bfb08f22 1565 dest_off = arch_jump_destination(insn);
f1974222
MH		 1566 } else if (reloc->sym->type == STT_SECTION) {
1567 dest_sec = reloc->sym->sec;
0696b6e3 1568 dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
1739c66e 1569 } else if (reloc->sym->retpoline_thunk) {
134ab5bd 1570 add_retpoline_call(file, insn);
39b73533 1571 continue;
d9e9d230 1572 } else if (reloc->sym->return_thunk) {
a149180f 1573 add_return_call(file, insn, true);
d9e9d230 1574 continue;
dbcdbdfd 1575 } else if (insn_func(insn)) {
26ff6041
JP		 1576 /*
1577 * External sibling call or internal sibling call with
1578 * STT_FUNC reloc.
1579 */
f56dae88 1580 add_call_dest(file, insn, reloc->sym, true);
dcc914f4 1581 continue;
ecf11ba4
JP		 1582 } else if (reloc->sym->sec->idx) {
1583 dest_sec = reloc->sym->sec;
1584 dest_off = reloc->sym->sym.st_value +
0696b6e3 1585 arch_dest_reloc_offset(reloc_addend(reloc));
ecf11ba4
JP		 1586 } else {
1587 /* non-func asm code jumping to another file */
1588 continue;
dcc914f4
JP		 1589 }
1590
26ff6041
JP		 1591 jump_dest = find_insn(file, dest_sec, dest_off);
1592 if (!jump_dest) {
a149180f
PZ		 1593 struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
1594
1595 /*
d025b7ba 1596 * This is a special case for retbleed_untrain_ret().
a149180f
PZ		 1597 * It jumps to __x86_return_thunk(), but objtool
1598 * can't find the thunk's starting RET
1599 * instruction, because the RET is also in the
1600 * middle of another instruction. Objtool only
1601 * knows about the outer instruction.
1602 */
4ae68b26 1603 if (sym && sym->embedded_insn) {
a149180f
PZ		 1604 add_return_call(file, insn, false);
1605 continue;
1606 }
1607
246b2c85
JP		 1608 WARN_INSN(insn, "can't find jump dest instruction at %s+0x%lx",
1609 dest_sec->name, dest_off);
dcc914f4
JP		 1610 return -1;
1611 }
cd77849a
JP		 1612
1613 /*
54262aa2 1614 * Cross-function jump.
cd77849a 1615 */
dbcdbdfd
PZ		 1616 if (insn_func(insn) && insn_func(jump_dest) &&
1617 insn_func(insn) != insn_func(jump_dest)) {
54262aa2
PZ		 1618
1619 /*
1620 * For GCC 8+, create parent/child links for any cold
1621 * subfunctions. This is _mostly_ redundant with a
1622 * similar initialization in read_symbols().
1623 *
1624 * If a function has aliases, we want the *first* such
1625 * function in the symbol table to be the subfunction's
1626 * parent. In that case we overwrite the
1627 * initialization done in read_symbols().
1628 *
1629 * However this code can't completely replace the
1630 * read_symbols() code because this doesn't detect the
1631 * case where the parent function's only reference to a
e7c2bc37 1632 * subfunction is through a jump table.
54262aa2 1633 */
dbcdbdfd
PZ		 1634 if (!strstr(insn_func(insn)->name, ".cold") &&
1635 strstr(insn_func(jump_dest)->name, ".cold")) {
1636 insn_func(insn)->cfunc = insn_func(jump_dest);
1637 insn_func(jump_dest)->pfunc = insn_func(insn);
54262aa2 1638 }
cd77849a 1639 }
26ff6041 1640
5a9c361a
PZ		 1641 if (jump_is_sibling_call(file, insn, jump_dest)) {
1642 /*
1643 * Internal sibling call without reloc or with
1644 * STT_SECTION reloc.
1645 */
1646 add_call_dest(file, insn, insn_func(jump_dest), true);
1647 continue;
1648 }
1649
26ff6041 1650 insn->jump_dest = jump_dest;
dcc914f4
JP		 1651 }
1652
1653 return 0;
1654}
1655
2b232a22
JT		 1656static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
1657{
1658 struct symbol *call_dest;
1659
1660 call_dest = find_func_by_offset(sec, offset);
1661 if (!call_dest)
1662 call_dest = find_symbol_by_offset(sec, offset);
1663
1664 return call_dest;
1665}
1666
dcc914f4
JP		 1667/*
1668 * Find the destination instructions for all calls.
1669 */
1670static int add_call_destinations(struct objtool_file *file)
1671{
1672 struct instruction *insn;
1673 unsigned long dest_off;
f56dae88 1674 struct symbol *dest;
f1974222 1675 struct reloc *reloc;
dcc914f4
JP		 1676
1677 for_each_insn(file, insn) {
1678 if (insn->type != INSN_CALL)
1679 continue;
1680
7bd2a600 1681 reloc = insn_reloc(file, insn);
f1974222 1682 if (!reloc) {
bfb08f22 1683 dest_off = arch_jump_destination(insn);
f56dae88
PZ		 1684 dest = find_call_destination(insn->sec, dest_off);
1685
1686 add_call_dest(file, insn, dest, false);
a845c7cf 1687
7acfe531
JP		 1688 if (insn->ignore)
1689 continue;
1690
c6f5dc28 1691 if (!insn_call_dest(insn)) {
246b2c85 1692 WARN_INSN(insn, "unannotated intra-function call");
dcc914f4
JP		 1693 return -1;
1694 }
a845c7cf 1695
c6f5dc28 1696 if (insn_func(insn) && insn_call_dest(insn)->type != STT_FUNC) {
246b2c85 1697 WARN_INSN(insn, "unsupported call to non-function");
7acfe531
JP		 1698 return -1;
1699 }
1700
f1974222 1701 } else if (reloc->sym->type == STT_SECTION) {
0696b6e3 1702 dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
f56dae88
PZ		 1703 dest = find_call_destination(reloc->sym->sec, dest_off);
1704 if (!dest) {
246b2c85
JP		 1705 WARN_INSN(insn, "can't find call dest symbol at %s+0x%lx",
1706 reloc->sym->sec->name, dest_off);
dcc914f4
JP		 1707 return -1;
1708 }
bcb1b6ff 1709
f56dae88
PZ		 1710 add_call_dest(file, insn, dest, false);
1711
1739c66e 1712 } else if (reloc->sym->retpoline_thunk) {
134ab5bd 1713 add_retpoline_call(file, insn);
bcb1b6ff 1714
dcc914f4 1715 } else
f56dae88 1716 add_call_dest(file, insn, reloc->sym, false);
dcc914f4
JP		 1717 }
1718
1719 return 0;
1720}
1721
1722/*
c9c324dc
JP		 1723 * The .alternatives section requires some extra special care over and above
1724 * other special sections because alternatives are patched in place.
dcc914f4
JP		 1725 */
1726static int handle_group_alt(struct objtool_file *file,
1727 struct special_alt *special_alt,
1728 struct instruction *orig_insn,
1729 struct instruction **new_insn)
1730{
a706bb08 1731 struct instruction *last_new_insn = NULL, *insn, *nop = NULL;
b23cc71c 1732 struct alt_group *orig_alt_group, *new_alt_group;
dcc914f4
JP		 1733 unsigned long dest_off;
1734
a706bb08 1735 orig_alt_group = orig_insn->alt_group;
b23cc71c 1736 if (!orig_alt_group) {
a706bb08 1737 struct instruction *last_orig_insn = NULL;
c9c324dc 1738
a706bb08
PZ		 1739 orig_alt_group = malloc(sizeof(*orig_alt_group));
1740 if (!orig_alt_group) {
1741 WARN("malloc failed");
1742 return -1;
1743 }
1744 orig_alt_group->cfi = calloc(special_alt->orig_len,
1745 sizeof(struct cfi_state *));
1746 if (!orig_alt_group->cfi) {
1747 WARN("calloc failed");
1748 return -1;
1749 }
dcc914f4 1750
a706bb08
PZ		 1751 insn = orig_insn;
1752 sec_for_each_insn_from(file, insn) {
1753 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
1754 break;
dcc914f4 1755
a706bb08
PZ		 1756 insn->alt_group = orig_alt_group;
1757 last_orig_insn = insn;
1758 }
1759 orig_alt_group->orig_group = NULL;
1760 orig_alt_group->first_insn = orig_insn;
1761 orig_alt_group->last_insn = last_orig_insn;
1c34496e 1762 orig_alt_group->nop = NULL;
a706bb08
PZ		 1763 } else {
1764 if (orig_alt_group->last_insn->offset + orig_alt_group->last_insn->len -
1765 orig_alt_group->first_insn->offset != special_alt->orig_len) {
246b2c85 1766 WARN_INSN(orig_insn, "weirdly overlapping alternative! %ld != %d",
a706bb08
PZ		 1767 orig_alt_group->last_insn->offset +
1768 orig_alt_group->last_insn->len -
1769 orig_alt_group->first_insn->offset,
1770 special_alt->orig_len);
1771 return -1;
1772 }
1773 }
17bc3391 1774
c9c324dc
JP		 1775 new_alt_group = malloc(sizeof(*new_alt_group));
1776 if (!new_alt_group) {
1777 WARN("malloc failed");
1778 return -1;
dcc914f4 1779 }
dcc914f4 1780
c9c324dc
JP		 1781 if (special_alt->new_len < special_alt->orig_len) {
1782 /*
1783 * Insert a fake nop at the end to make the replacement
1784 * alt_group the same size as the original. This is needed to
1785 * allow propagate_alt_cfi() to do its magic. When the last
1786 * instruction affects the stack, the instruction after it (the
1787 * nop) will propagate the new state to the shared CFI array.
1788 */
1789 nop = malloc(sizeof(*nop));
1790 if (!nop) {
1791 WARN("malloc failed");
17bc3391
JP		 1792 return -1;
1793 }
c9c324dc 1794 memset(nop, 0, sizeof(*nop));
c9c324dc
JP		 1795
1796 nop->sec = special_alt->new_sec;
1797 nop->offset = special_alt->new_off + special_alt->new_len;
1798 nop->len = special_alt->orig_len - special_alt->new_len;
1799 nop->type = INSN_NOP;
dbcdbdfd 1800 nop->sym = orig_insn->sym;
c9c324dc
JP		 1801 nop->alt_group = new_alt_group;
1802 nop->ignore = orig_insn->ignore_alts;
dcc914f4 1803 }
17bc3391 1804
c9c324dc
JP		 1805 if (!special_alt->new_len) {
1806 *new_insn = nop;
1807 goto end;
dcc914f4
JP		 1808 }
1809
dcc914f4
JP		 1810 insn = *new_insn;
1811 sec_for_each_insn_from(file, insn) {
45245f51
JT		 1812 struct reloc *alt_reloc;
1813
dcc914f4
JP		 1814 if (insn->offset >= special_alt->new_off + special_alt->new_len)
1815 break;
1816
1817 last_new_insn = insn;
1818
a845c7cf 1819 insn->ignore = orig_insn->ignore_alts;
dbcdbdfd 1820 insn->sym = orig_insn->sym;
b23cc71c 1821 insn->alt_group = new_alt_group;
a845c7cf 1822
dc419723
JP		 1823 /*
1824 * Since alternative replacement code is copy/pasted by the
1825 * kernel after applying relocations, generally such code can't
1826 * have relative-address relocation references to outside the
1827 * .altinstr_replacement section, unless the arch's
1828 * alternatives code can adjust the relative offsets
1829 * accordingly.
dc419723 1830 */
7bd2a600 1831 alt_reloc = insn_reloc(file, insn);
61c6065e 1832 if (alt_reloc && arch_pc_relative_reloc(alt_reloc) &&
45245f51 1833 !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
dc419723 1834
246b2c85 1835 WARN_INSN(insn, "unsupported relocation in alternatives section");
dc419723
JP		 1836 return -1;
1837 }
1838
a2296140 1839 if (!is_static_jump(insn))
dcc914f4
JP		 1840 continue;
1841
1842 if (!insn->immediate)
1843 continue;
1844
bfb08f22 1845 dest_off = arch_jump_destination(insn);
34c861e8 1846 if (dest_off == special_alt->new_off + special_alt->new_len) {
a706bb08 1847 insn->jump_dest = next_insn_same_sec(file, orig_alt_group->last_insn);
34c861e8 1848 if (!insn->jump_dest) {
246b2c85 1849 WARN_INSN(insn, "can't find alternative jump destination");
34c861e8
JP		 1850 return -1;
1851 }
dcc914f4
JP		 1852 }
1853 }
1854
1855 if (!last_new_insn) {
1856 WARN_FUNC("can't find last new alternative instruction",
1857 special_alt->new_sec, special_alt->new_off);
1858 return -1;
1859 }
1860
c9c324dc 1861end:
b23cc71c
JP		 1862 new_alt_group->orig_group = orig_alt_group;
1863 new_alt_group->first_insn = *new_insn;
1c34496e
PZ		 1864 new_alt_group->last_insn = last_new_insn;
1865 new_alt_group->nop = nop;
c9c324dc 1866 new_alt_group->cfi = orig_alt_group->cfi;
dcc914f4
JP		 1867 return 0;
1868}
1869
1870/*
1871 * A jump table entry can either convert a nop to a jump or a jump to a nop.
1872 * If the original instruction is a jump, make the alt entry an effective nop
1873 * by just skipping the original instruction.
1874 */
1875static int handle_jump_alt(struct objtool_file *file,
1876 struct special_alt *special_alt,
1877 struct instruction *orig_insn,
1878 struct instruction **new_insn)
1879{
48001d26
PZ		 1880 if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
1881 orig_insn->type != INSN_NOP) {
e2d9494b 1882
246b2c85 1883 WARN_INSN(orig_insn, "unsupported instruction at jump label");
dcc914f4
JP		 1884 return -1;
1885 }
1886
4ab7674f 1887 if (opts.hack_jump_label && special_alt->key_addend & 2) {
6d37b83c
PZ		 1888 struct reloc *reloc = insn_reloc(file, orig_insn);
1889
ec24b927
JP		 1890 if (reloc)
1891 set_reloc_type(file->elf, reloc, R_NONE);
6d37b83c
PZ		 1892 elf_write_insn(file->elf, orig_insn->sec,
1893 orig_insn->offset, orig_insn->len,
1894 arch_nop_insn(orig_insn->len));
1895 orig_insn->type = INSN_NOP;
48001d26
PZ		 1896 }
1897
1898 if (orig_insn->type == INSN_NOP) {
1899 if (orig_insn->len == 2)
1900 file->jl_nop_short++;
1901 else
1902 file->jl_nop_long++;
1903
1904 return 0;
6d37b83c
PZ		 1905 }
1906
e2d9494b
PZ		 1907 if (orig_insn->len == 2)
1908 file->jl_short++;
1909 else
1910 file->jl_long++;
1911
1c34496e 1912 *new_insn = next_insn_same_sec(file, orig_insn);
dcc914f4
JP		 1913 return 0;
1914}
1915
1916/*
1917 * Read all the special sections which have alternate instructions which can be
1918 * patched in or redirected to at runtime. Each instruction having alternate
1919 * instruction(s) has them added to its insn->alts list, which will be
1920 * traversed in validate_branch().
1921 */
1922static int add_special_section_alts(struct objtool_file *file)
1923{
1924 struct list_head special_alts;
1925 struct instruction *orig_insn, *new_insn;
1926 struct special_alt *special_alt, *tmp;
1927 struct alternative *alt;
1928 int ret;
1929
1930 ret = special_get_alts(file->elf, &special_alts);
1931 if (ret)
1932 return ret;
1933
1934 list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
dcc914f4
JP		 1935
1936 orig_insn = find_insn(file, special_alt->orig_sec,
1937 special_alt->orig_off);
1938 if (!orig_insn) {
1939 WARN_FUNC("special: can't find orig instruction",
1940 special_alt->orig_sec, special_alt->orig_off);
1941 ret = -1;
1942 goto out;
1943 }
1944
1945 new_insn = NULL;
1946 if (!special_alt->group || special_alt->new_len) {
1947 new_insn = find_insn(file, special_alt->new_sec,
1948 special_alt->new_off);
1949 if (!new_insn) {
1950 WARN_FUNC("special: can't find new instruction",
1951 special_alt->new_sec,
1952 special_alt->new_off);
1953 ret = -1;
1954 goto out;
1955 }
1956 }
1957
1958 if (special_alt->group) {
7170cf47 1959 if (!special_alt->orig_len) {
246b2c85 1960 WARN_INSN(orig_insn, "empty alternative entry");
7170cf47
JT		 1961 continue;
1962 }
1963
dcc914f4
JP		 1964 ret = handle_group_alt(file, special_alt, orig_insn,
1965 &new_insn);
1966 if (ret)
1967 goto out;
1968 } else if (special_alt->jump_or_nop) {
1969 ret = handle_jump_alt(file, special_alt, orig_insn,
1970 &new_insn);
1971 if (ret)
1972 goto out;
1973 }
1974
258c7605
JP		 1975 alt = malloc(sizeof(*alt));
1976 if (!alt) {
1977 WARN("malloc failed");
1978 ret = -1;
1979 goto out;
1980 }
1981
dcc914f4 1982 alt->insn = new_insn;
764eef4b 1983 alt->skip_orig = special_alt->skip_orig;
ea24213d 1984 orig_insn->ignore_alts |= special_alt->skip_alt;
d5406654
PZ		 1985 alt->next = orig_insn->alts;
1986 orig_insn->alts = alt;
dcc914f4
JP		 1987
1988 list_del(&special_alt->list);
1989 free(special_alt);
1990 }
1991
2daf7fab 1992 if (opts.stats) {
e2d9494b
PZ		 1993 printf("jl\\\tNOP\tJMP\n");
1994 printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
1995 printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
1996 }
1997
dcc914f4
JP		 1998out:
1999 return ret;
2000}
2001
e7c2bc37 2002static int add_jump_table(struct objtool_file *file, struct instruction *insn,
be2f0b1e 2003 struct reloc *next_table)
dcc914f4 2004{
dbcdbdfd 2005 struct symbol *pfunc = insn_func(insn)->pfunc;
be2f0b1e
JP		 2006 struct reloc *table = insn_jump_table(insn);
2007 struct instruction *dest_insn;
fd35c88b 2008 unsigned int prev_offset = 0;
be2f0b1e
JP		 2009 struct reloc *reloc = table;
2010 struct alternative *alt;
dcc914f4 2011
e7c2bc37 2012 /*
f1974222 2013 * Each @reloc is a switch table relocation which points to the target
e7c2bc37
JP		 2014 * instruction.
2015 */
caa4a6b7 2016 for_each_reloc_from(table->sec, reloc) {
bd98c813
JH		 2017
2018 /* Check for the end of the table: */
be2f0b1e 2019 if (reloc != table && reloc == next_table)
dcc914f4
JP		 2020 break;
2021
e7c2bc37 2022 /* Make sure the table entries are consecutive: */
e4cbb9b8 2023 if (prev_offset && reloc_offset(reloc) != prev_offset + 8)
fd35c88b
JP		 2024 break;
2025
2026 /* Detect function pointers from contiguous objects: */
f1974222 2027 if (reloc->sym->sec == pfunc->sec &&
0696b6e3 2028 reloc_addend(reloc) == pfunc->offset)
fd35c88b
JP		 2029 break;
2030
0696b6e3 2031 dest_insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
e7c2bc37 2032 if (!dest_insn)
dcc914f4
JP		 2033 break;
2034
e7c2bc37 2035 /* Make sure the destination is in the same function: */
dbcdbdfd 2036 if (!insn_func(dest_insn) || insn_func(dest_insn)->pfunc != pfunc)
13810435 2037 break;
dcc914f4
JP		 2038
2039 alt = malloc(sizeof(*alt));
2040 if (!alt) {
2041 WARN("malloc failed");
2042 return -1;
2043 }
2044
e7c2bc37 2045 alt->insn = dest_insn;
d5406654
PZ		 2046 alt->next = insn->alts;
2047 insn->alts = alt;
e4cbb9b8 2048 prev_offset = reloc_offset(reloc);
fd35c88b
JP		 2049 }
2050
2051 if (!prev_offset) {
246b2c85 2052 WARN_INSN(insn, "can't find switch jump table");
fd35c88b 2053 return -1;
dcc914f4
JP		 2054 }
2055
2056 return 0;
2057}
2058
2059/*
d871f7b5
RG		 2060 * find_jump_table() - Given a dynamic jump, find the switch jump table
2061 * associated with it.
dcc914f4 2062 */
f1974222 2063static struct reloc *find_jump_table(struct objtool_file *file,
dcc914f4
JP		 2064 struct symbol *func,
2065 struct instruction *insn)
2066{
d871f7b5 2067 struct reloc *table_reloc;
113d4bc9 2068 struct instruction *dest_insn, *orig_insn = insn;
dcc914f4 2069
99ce7962
PZ		 2070 /*
2071 * Backward search using the @first_jump_src links, these help avoid
2072 * much of the 'in between' code. Which avoids us getting confused by
2073 * it.
2074 */
7dec80cc 2075 for (;
dbcdbdfd 2076 insn && insn_func(insn) && insn_func(insn)->pfunc == func;
1119d265 2077 insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
99ce7962 2078
7dec80cc 2079 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
dcc914f4
JP		 2080 break;
2081
2082 /* allow small jumps within the range */
2083 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
2084 insn->jump_dest &&
2085 (insn->jump_dest->offset <= insn->offset ||
2086 insn->jump_dest->offset > orig_insn->offset))
2087 break;
2088
d871f7b5 2089 table_reloc = arch_find_switch_table(file, insn);
f1974222 2090 if (!table_reloc)
e7c2bc37 2091 continue;
0696b6e3 2092 dest_insn = find_insn(file, table_reloc->sym->sec, reloc_addend(table_reloc));
dbcdbdfd 2093 if (!dest_insn || !insn_func(dest_insn) || insn_func(dest_insn)->pfunc != func)
113d4bc9 2094 continue;
7dec80cc 2095
f1974222 2096 return table_reloc;
dcc914f4
JP		 2097 }
2098
2099 return NULL;
2100}
2101
bd98c813
JH		 2102/*
2103 * First pass: Mark the head of each jump table so that in the next pass,
2104 * we know when a given jump table ends and the next one starts.
2105 */
2106static void mark_func_jump_tables(struct objtool_file *file,
2107 struct symbol *func)
dcc914f4 2108{
bd98c813 2109 struct instruction *insn, *last = NULL;
f1974222 2110 struct reloc *reloc;
dcc914f4 2111
f0f70adb 2112 func_for_each_insn(file, func, insn) {
99ce7962
PZ		 2113 if (!last)
2114 last = insn;
2115
2116 /*
2117 * Store back-pointers for unconditional forward jumps such
e7c2bc37 2118 * that find_jump_table() can back-track using those and
99ce7962
PZ		 2119 * avoid some potentially confusing code.
2120 */
2121 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
2122 insn->offset > last->offset &&
2123 insn->jump_dest->offset > insn->offset &&
2124 !insn->jump_dest->first_jump_src) {
2125
2126 insn->jump_dest->first_jump_src = insn;
2127 last = insn->jump_dest;
2128 }
2129
dcc914f4
JP		 2130 if (insn->type != INSN_JUMP_DYNAMIC)
2131 continue;
2132
f1974222 2133 reloc = find_jump_table(file, func, insn);
be2f0b1e 2134 if (reloc)
c6f5dc28 2135 insn->_jump_table = reloc;
dcc914f4 2136 }
bd98c813
JH		 2137}
2138
2139static int add_func_jump_tables(struct objtool_file *file,
2140 struct symbol *func)
2141{
be2f0b1e
JP		 2142 struct instruction *insn, *insn_t1 = NULL, *insn_t2;
2143 int ret = 0;
bd98c813 2144
f0f70adb 2145 func_for_each_insn(file, func, insn) {
c6f5dc28 2146 if (!insn_jump_table(insn))
bd98c813 2147 continue;
dcc914f4 2148
be2f0b1e
JP		 2149 if (!insn_t1) {
2150 insn_t1 = insn;
2151 continue;
2152 }
2153
2154 insn_t2 = insn;
2155
2156 ret = add_jump_table(file, insn_t1, insn_jump_table(insn_t2));
dcc914f4
JP		 2157 if (ret)
2158 return ret;
be2f0b1e
JP		 2159
2160 insn_t1 = insn_t2;
dcc914f4
JP		 2161 }
2162
be2f0b1e
JP		 2163 if (insn_t1)
2164 ret = add_jump_table(file, insn_t1, NULL);
2165
2166 return ret;
dcc914f4
JP		 2167}
2168
2169/*
2170 * For some switch statements, gcc generates a jump table in the .rodata
2171 * section which contains a list of addresses within the function to jump to.
2172 * This finds these jump tables and adds them to the insn->alts lists.
2173 */
e7c2bc37 2174static int add_jump_table_alts(struct objtool_file *file)
dcc914f4 2175{
dcc914f4
JP		 2176 struct symbol *func;
2177 int ret;
2178
4a60aa05 2179 if (!file->rodata)
dcc914f4
JP		 2180 return 0;
2181
9290e772
JP		 2182 for_each_sym(file, func) {
2183 if (func->type != STT_FUNC)
2184 continue;
dcc914f4 2185
9290e772
JP		 2186 mark_func_jump_tables(file, func);
2187 ret = add_func_jump_tables(file, func);
2188 if (ret)
2189 return ret;
dcc914f4
JP		 2190 }
2191
2192 return 0;
2193}
2194
b735bd3e
JP		 2195static void set_func_state(struct cfi_state *state)
2196{
2197 state->cfa = initial_func_cfi.cfa;
2198 memcpy(&state->regs, &initial_func_cfi.regs,
2199 CFI_NUM_REGS * sizeof(struct cfi_reg));
2200 state->stack_size = initial_func_cfi.cfa.offset;
fb799447 2201 state->type = UNWIND_HINT_TYPE_CALL;
b735bd3e
JP		 2202}
2203
39358a03
JP		 2204static int read_unwind_hints(struct objtool_file *file)
2205{
8b946cc3 2206 struct cfi_state cfi = init_cfi;
a5bd6236 2207 struct section *sec;
39358a03
JP		 2208 struct unwind_hint *hint;
2209 struct instruction *insn;
8b946cc3 2210 struct reloc *reloc;
39358a03
JP		 2211 int i;
2212
2213 sec = find_section_by_name(file->elf, ".discard.unwind_hints");
2214 if (!sec)
2215 return 0;
2216
a5bd6236 2217 if (!sec->rsec) {
39358a03
JP		 2218 WARN("missing .rela.discard.unwind_hints section");
2219 return -1;
2220 }
2221
fe255fe6 2222 if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
39358a03
JP		 2223 WARN("struct unwind_hint size mismatch");
2224 return -1;
2225 }
2226
2227 file->hints = true;
2228
fe255fe6 2229 for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
39358a03
JP		 2230 hint = (struct unwind_hint *)sec->data->d_buf + i;
2231
f1974222
MH		 2232 reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
2233 if (!reloc) {
2234 WARN("can't find reloc for unwind_hints[%d]", i);
39358a03
JP		 2235 return -1;
2236 }
2237
0696b6e3 2238 insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
39358a03
JP		 2239 if (!insn) {
2240 WARN("can't find insn for unwind_hints[%d]", i);
2241 return -1;
2242 }
2243
b735bd3e 2244 insn->hint = true;
39358a03 2245
1e4b6191
JP		 2246 if (hint->type == UNWIND_HINT_TYPE_UNDEFINED) {
2247 insn->cfi = &force_undefined_cfi;
2248 continue;
2249 }
2250
8faea26e
JP		 2251 if (hint->type == UNWIND_HINT_TYPE_SAVE) {
2252 insn->hint = false;
2253 insn->save = true;
2254 continue;
2255 }
2256
2257 if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
2258 insn->restore = true;
2259 continue;
2260 }
2261
a09a6e23 2262 if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
08f87a93
PZ		 2263 struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
2264
a09a6e23
PZ		 2265 if (sym && sym->bind == STB_GLOBAL) {
2266 if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
246b2c85 2267 WARN_INSN(insn, "UNWIND_HINT_IRET_REGS without ENDBR");
a09a6e23 2268 }
08f87a93
PZ		 2269 }
2270 }
2271
b735bd3e 2272 if (hint->type == UNWIND_HINT_TYPE_FUNC) {
8b946cc3 2273 insn->cfi = &func_cfi;
39358a03
JP		 2274 continue;
2275 }
2276
8b946cc3
PZ		 2277 if (insn->cfi)
2278 cfi = *(insn->cfi);
2279
2280 if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
246b2c85 2281 WARN_INSN(insn, "unsupported unwind_hint sp base reg %d", hint->sp_reg);
39358a03
JP		 2282 return -1;
2283 }
2284
0646c28b 2285 cfi.cfa.offset = bswap_if_needed(file->elf, hint->sp_offset);
8b946cc3 2286 cfi.type = hint->type;
00c8f01c 2287 cfi.signal = hint->signal;
8b946cc3
PZ		 2288
2289 insn->cfi = cfi_hash_find_or_add(&cfi);
39358a03
JP		 2290 }
2291
2292 return 0;
2293}
2294
96db4a98
PZ		 2295static int read_noendbr_hints(struct objtool_file *file)
2296{
96db4a98 2297 struct instruction *insn;
a5bd6236 2298 struct section *rsec;
96db4a98
PZ		 2299 struct reloc *reloc;
2300
a5bd6236
JP		 2301 rsec = find_section_by_name(file->elf, ".rela.discard.noendbr");
2302 if (!rsec)
96db4a98
PZ		 2303 return 0;
2304
caa4a6b7 2305 for_each_reloc(rsec, reloc) {
0696b6e3
JP		 2306 insn = find_insn(file, reloc->sym->sec,
2307 reloc->sym->offset + reloc_addend(reloc));
96db4a98
PZ		 2308 if (!insn) {
2309 WARN("bad .discard.noendbr entry");
2310 return -1;
2311 }
2312
2313 insn->noendbr = 1;
2314 }
2315
2316 return 0;
2317}
2318
b5bc2231
PZ		 2319static int read_retpoline_hints(struct objtool_file *file)
2320{
a5bd6236 2321 struct section *rsec;
b5bc2231 2322 struct instruction *insn;
f1974222 2323 struct reloc *reloc;
b5bc2231 2324
a5bd6236
JP		 2325 rsec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
2326 if (!rsec)
b5bc2231
PZ		 2327 return 0;
2328
caa4a6b7 2329 for_each_reloc(rsec, reloc) {
f1974222 2330 if (reloc->sym->type != STT_SECTION) {
a5bd6236 2331 WARN("unexpected relocation symbol type in %s", rsec->name);
b5bc2231
PZ		 2332 return -1;
2333 }
2334
0696b6e3 2335 insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
b5bc2231 2336 if (!insn) {
63474dc4 2337 WARN("bad .discard.retpoline_safe entry");
b5bc2231
PZ		 2338 return -1;
2339 }
2340
2341 if (insn->type != INSN_JUMP_DYNAMIC &&
9bb2ec60 2342 insn->type != INSN_CALL_DYNAMIC &&
a09a6e23
PZ		 2343 insn->type != INSN_RETURN &&
2344 insn->type != INSN_NOP) {
246b2c85 2345 WARN_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
b5bc2231
PZ		 2346 return -1;
2347 }
2348
2349 insn->retpoline_safe = true;
2350 }
2351
2352 return 0;
2353}
2354
c4a33939
PZ		 2355static int read_instr_hints(struct objtool_file *file)
2356{
a5bd6236 2357 struct section *rsec;
c4a33939 2358 struct instruction *insn;
f1974222 2359 struct reloc *reloc;
c4a33939 2360
a5bd6236
JP		 2361 rsec = find_section_by_name(file->elf, ".rela.discard.instr_end");
2362 if (!rsec)
c4a33939
PZ		 2363 return 0;
2364
caa4a6b7 2365 for_each_reloc(rsec, reloc) {
f1974222 2366 if (reloc->sym->type != STT_SECTION) {
a5bd6236 2367 WARN("unexpected relocation symbol type in %s", rsec->name);
c4a33939
PZ		 2368 return -1;
2369 }
2370
0696b6e3 2371 insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
c4a33939
PZ		 2372 if (!insn) {
2373 WARN("bad .discard.instr_end entry");
2374 return -1;
2375 }
2376
2377 insn->instr--;
2378 }
2379
a5bd6236
JP		 2380 rsec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
2381 if (!rsec)
c4a33939
PZ		 2382 return 0;
2383
caa4a6b7 2384 for_each_reloc(rsec, reloc) {
f1974222 2385 if (reloc->sym->type != STT_SECTION) {
a5bd6236 2386 WARN("unexpected relocation symbol type in %s", rsec->name);
c4a33939
PZ		 2387 return -1;
2388 }
2389
0696b6e3 2390 insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
c4a33939
PZ		 2391 if (!insn) {
2392 WARN("bad .discard.instr_begin entry");
2393 return -1;
2394 }
2395
2396 insn->instr++;
2397 }
2398
2399 return 0;
2400}
2401
4708ea14
JP		 2402static int read_validate_unret_hints(struct objtool_file *file)
2403{
a5bd6236 2404 struct section *rsec;
4708ea14
JP		 2405 struct instruction *insn;
2406 struct reloc *reloc;
2407
a5bd6236
JP		 2408 rsec = find_section_by_name(file->elf, ".rela.discard.validate_unret");
2409 if (!rsec)
4708ea14
JP		 2410 return 0;
2411
caa4a6b7 2412 for_each_reloc(rsec, reloc) {
4708ea14 2413 if (reloc->sym->type != STT_SECTION) {
a5bd6236 2414 WARN("unexpected relocation symbol type in %s", rsec->name);
4708ea14
JP		 2415 return -1;
2416 }
2417
0696b6e3 2418 insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
4708ea14
JP		 2419 if (!insn) {
2420 WARN("bad .discard.instr_end entry");
2421 return -1;
2422 }
2423 insn->unret = 1;
2424 }
2425
2426 return 0;
2427}
2428
2429
8aa8eb2a
AC		 2430static int read_intra_function_calls(struct objtool_file *file)
2431{
2432 struct instruction *insn;
a5bd6236 2433 struct section *rsec;
f1974222 2434 struct reloc *reloc;
8aa8eb2a 2435
a5bd6236
JP		 2436 rsec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
2437 if (!rsec)
8aa8eb2a
AC		 2438 return 0;
2439
caa4a6b7 2440 for_each_reloc(rsec, reloc) {
8aa8eb2a
AC		 2441 unsigned long dest_off;
2442
f1974222 2443 if (reloc->sym->type != STT_SECTION) {
8aa8eb2a 2444 WARN("unexpected relocation symbol type in %s",
a5bd6236 2445 rsec->name);
8aa8eb2a
AC		 2446 return -1;
2447 }
2448
0696b6e3 2449 insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
8aa8eb2a
AC		 2450 if (!insn) {
2451 WARN("bad .discard.intra_function_call entry");
2452 return -1;
2453 }
2454
2455 if (insn->type != INSN_CALL) {
246b2c85 2456 WARN_INSN(insn, "intra_function_call not a direct call");
8aa8eb2a
AC		 2457 return -1;
2458 }
2459
2460 /*
2461 * Treat intra-function CALLs as JMPs, but with a stack_op.
2462 * See add_call_destinations(), which strips stack_ops from
2463 * normal CALLs.
2464 */
2465 insn->type = INSN_JUMP_UNCONDITIONAL;
2466
7b3e3186 2467 dest_off = arch_jump_destination(insn);
8aa8eb2a
AC		 2468 insn->jump_dest = find_insn(file, insn->sec, dest_off);
2469 if (!insn->jump_dest) {
246b2c85 2470 WARN_INSN(insn, "can't find call dest at %s+0x%lx",
8aa8eb2a
AC		 2471 insn->sec->name, dest_off);
2472 return -1;
2473 }
2474 }
2475
2476 return 0;
2477}
2478
05098119
ME		 2479/*
2480 * Return true if name matches an instrumentation function, where calls to that
2481 * function from noinstr code can safely be removed, but compilers won't do so.
2482 */
2483static bool is_profiling_func(const char *name)
2484{
2485 /*
2486 * Many compilers cannot disable KCOV with a function attribute.
2487 */
2488 if (!strncmp(name, "__sanitizer_cov_", 16))
2489 return true;
2490
2491 /*
2492 * Some compilers currently do not remove __tsan_func_entry/exit nor
2493 * __tsan_atomic_signal_fence (used for barrier instrumentation) with
2494 * the __no_sanitize_thread attribute, remove them. Once the kernel's
2495 * minimum Clang version is 14.0, this can be removed.
2496 */
2497 if (!strncmp(name, "__tsan_func_", 12) ||
2498 !strcmp(name, "__tsan_atomic_signal_fence"))
2499 return true;
2500
2501 return false;
2502}
2503
1739c66e 2504static int classify_symbols(struct objtool_file *file)
1e7e4788 2505{
1e7e4788
JP		 2506 struct symbol *func;
2507
9290e772
JP		 2508 for_each_sym(file, func) {
2509 if (func->bind != STB_GLOBAL)
2510 continue;
1739c66e 2511
9290e772
JP		 2512 if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
2513 strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
2514 func->static_call_tramp = true;
1739c66e 2515
9290e772
JP		 2516 if (arch_is_retpoline(func))
2517 func->retpoline_thunk = true;
1739c66e 2518
9290e772
JP		 2519 if (arch_is_rethunk(func))
2520 func->return_thunk = true;
d9e9d230 2521
4ae68b26
PZ		 2522 if (arch_is_embedded_insn(func))
2523 func->embedded_insn = true;
2524
9290e772
JP		 2525 if (arch_ftrace_match(func->name))
2526 func->fentry = true;
1739c66e 2527
9290e772
JP		 2528 if (is_profiling_func(func->name))
2529 func->profiling_func = true;
1e7e4788
JP		 2530 }
2531
2532 return 0;
2533}
2534
4a60aa05
AX		 2535static void mark_rodata(struct objtool_file *file)
2536{
2537 struct section *sec;
2538 bool found = false;
2539
2540 /*
87b512de
JP		 2541 * Search for the following rodata sections, each of which can
2542 * potentially contain jump tables:
2543 *
2544 * - .rodata: can contain GCC switch tables
2545 * - .rodata.<func>: same, if -fdata-sections is being used
2546 * - .rodata..c_jump_table: contains C annotated jump tables
2547 *
2548 * .rodata.str1.* sections are ignored; they don't contain jump tables.
4a60aa05
AX		 2549 */
2550 for_each_sec(file, sec) {
1ee44470
MS		 2551 if (!strncmp(sec->name, ".rodata", 7) &&
2552 !strstr(sec->name, ".str1.")) {
4a60aa05
AX		 2553 sec->rodata = true;
2554 found = true;
2555 }
2556 }
2557
2558 file->rodata = found;
2559}
2560
dcc914f4
JP		 2561static int decode_sections(struct objtool_file *file)
2562{
2563 int ret;
2564
4a60aa05
AX		 2565 mark_rodata(file);
2566
db2b0c5d
PZ		 2567 ret = init_pv_ops(file);
2568 if (ret)
2569 return ret;
2570
dbcdbdfd
PZ		 2571 /*
2572 * Must be before add_{jump_call}_destination.
2573 */
2574 ret = classify_symbols(file);
2575 if (ret)
2576 return ret;
2577
dcc914f4
JP		 2578 ret = decode_instructions(file);
2579 if (ret)
2580 return ret;
2581
dcc914f4 2582 add_ignores(file);
ea24213d 2583 add_uaccess_safe(file);
dcc914f4 2584
ff05ab23 2585 ret = add_ignore_alternatives(file);
258c7605
JP		 2586 if (ret)
2587 return ret;
2588
08f87a93
PZ		 2589 /*
2590 * Must be before read_unwind_hints() since that needs insn->noendbr.
2591 */
96db4a98
PZ		 2592 ret = read_noendbr_hints(file);
2593 if (ret)
2594 return ret;
2595
43d5430a 2596 /*
34c861e8
JP		 2597 * Must be before add_jump_destinations(), which depends on 'func'
2598 * being set for alternatives, to enable proper sibling call detection.
43d5430a 2599 */
de6fbced
SV		 2600 if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr) {
2601 ret = add_special_section_alts(file);
2602 if (ret)
2603 return ret;
2604 }
dcc914f4 2605
34c861e8 2606 ret = add_jump_destinations(file);
dcc914f4
JP		 2607 if (ret)
2608 return ret;
2609
a958c4fe
PZ		 2610 /*
2611 * Must be before add_call_destination(); it changes INSN_CALL to
2612 * INSN_JUMP.
2613 */
8aa8eb2a
AC		 2614 ret = read_intra_function_calls(file);
2615 if (ret)
2616 return ret;
2617
a845c7cf 2618 ret = add_call_destinations(file);
dcc914f4
JP		 2619 if (ret)
2620 return ret;
2621
0e5b613b
PZ		 2622 /*
2623 * Must be after add_call_destinations() such that it can override
2624 * dead_end_function() marks.
2625 */
2626 ret = add_dead_ends(file);
2627 if (ret)
2628 return ret;
2629
e7c2bc37 2630 ret = add_jump_table_alts(file);
dcc914f4
JP		 2631 if (ret)
2632 return ret;
2633
39358a03
JP		 2634 ret = read_unwind_hints(file);
2635 if (ret)
2636 return ret;
2637
b5bc2231
PZ		 2638 ret = read_retpoline_hints(file);
2639 if (ret)
2640 return ret;
2641
c4a33939
PZ		 2642 ret = read_instr_hints(file);
2643 if (ret)
2644 return ret;
2645
4708ea14
JP		 2646 ret = read_validate_unret_hints(file);
2647 if (ret)
2648 return ret;
2649
dcc914f4
JP		 2650 return 0;
2651}
2652
dbf46008 2653static bool is_special_call(struct instruction *insn)
dcc914f4 2654{
dbf46008
PZ		 2655 if (insn->type == INSN_CALL) {
2656 struct symbol *dest = insn_call_dest(insn);
2657
2658 if (!dest)
2659 return false;
2660
2661 if (dest->fentry || dest->embedded_insn)
2662 return true;
2663 }
dcc914f4
JP		 2664
2665 return false;
2666}
2667
e25eea89 2668static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
dcc914f4 2669{
e7c0219b 2670 struct cfi_state *cfi = &state->cfi;
baa41469
JP		 2671 int i;
2672
e7c0219b 2673 if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
e25eea89
PZ		 2674 return true;
2675
b735bd3e 2676 if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
baa41469
JP		 2677 return true;
2678
b735bd3e 2679 if (cfi->stack_size != initial_func_cfi.cfa.offset)
e25eea89
PZ		 2680 return true;
2681
2682 for (i = 0; i < CFI_NUM_REGS; i++) {
e7c0219b
PZ		 2683 if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
2684 cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
baa41469 2685 return true;
e25eea89 2686 }
baa41469
JP		 2687
2688 return false;
2689}
2690
fb084fde
JT		 2691static bool check_reg_frame_pos(const struct cfi_reg *reg,
2692 int expected_offset)
2693{
2694 return reg->base == CFI_CFA &&
2695 reg->offset == expected_offset;
2696}
2697
baa41469
JP		 2698static bool has_valid_stack_frame(struct insn_state *state)
2699{
e7c0219b
PZ		 2700 struct cfi_state *cfi = &state->cfi;
2701
fb084fde
JT		 2702 if (cfi->cfa.base == CFI_BP &&
2703 check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
2704 check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
baa41469
JP		 2705 return true;
2706
e7c0219b 2707 if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
baa41469
JP		 2708 return true;
2709
2710 return false;
dcc914f4
JP		 2711}
2712
e7c0219b
PZ		 2713static int update_cfi_state_regs(struct instruction *insn,
2714 struct cfi_state *cfi,
65ea47dc 2715 struct stack_op *op)
627fce14 2716{
e7c0219b 2717 struct cfi_reg *cfa = &cfi->cfa;
627fce14 2718
d8dd25a4 2719 if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
627fce14
JP		 2720 return 0;
2721
2722 /* push */
ea24213d 2723 if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
627fce14
JP		 2724 cfa->offset += 8;
2725
2726 /* pop */
ea24213d 2727 if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
627fce14
JP		 2728 cfa->offset -= 8;
2729
2730 /* add immediate to sp */
2731 if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
2732 op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
2733 cfa->offset -= op->src.offset;
2734
2735 return 0;
2736}
2737
e7c0219b 2738static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
dcc914f4 2739{
bf4d1a83 2740 if (arch_callee_saved_reg(reg) &&
e7c0219b
PZ		 2741 cfi->regs[reg].base == CFI_UNDEFINED) {
2742 cfi->regs[reg].base = base;
2743 cfi->regs[reg].offset = offset;
baa41469 2744 }
dcc914f4
JP		 2745}
2746
e7c0219b 2747static void restore_reg(struct cfi_state *cfi, unsigned char reg)
dcc914f4 2748{
e7c0219b
PZ		 2749 cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
2750 cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
baa41469
JP		 2751}
2752
2753/*
2754 * A note about DRAP stack alignment:
2755 *
2756 * GCC has the concept of a DRAP register, which is used to help keep track of
2757 * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
2758 * register. The typical DRAP pattern is:
2759 *
2760 * 4c 8d 54 24 08 lea 0x8(%rsp),%r10
2761 * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
2762 * 41 ff 72 f8 pushq -0x8(%r10)
2763 * 55 push %rbp
2764 * 48 89 e5 mov %rsp,%rbp
2765 * (more pushes)
2766 * 41 52 push %r10
2767 * ...
2768 * 41 5a pop %r10
2769 * (more pops)
2770 * 5d pop %rbp
2771 * 49 8d 62 f8 lea -0x8(%r10),%rsp
2772 * c3 retq
2773 *
2774 * There are some variations in the epilogues, like:
2775 *
2776 * 5b pop %rbx
2777 * 41 5a pop %r10
2778 * 41 5c pop %r12
2779 * 41 5d pop %r13
2780 * 41 5e pop %r14
2781 * c9 leaveq
2782 * 49 8d 62 f8 lea -0x8(%r10),%rsp
2783 * c3 retq
2784 *
2785 * and:
2786 *
2787 * 4c 8b 55 e8 mov -0x18(%rbp),%r10
2788 * 48 8b 5d e0 mov -0x20(%rbp),%rbx
2789 * 4c 8b 65 f0 mov -0x10(%rbp),%r12
2790 * 4c 8b 6d f8 mov -0x8(%rbp),%r13
2791 * c9 leaveq
2792 * 49 8d 62 f8 lea -0x8(%r10),%rsp
2793 * c3 retq
2794 *
2795 * Sometimes r13 is used as the DRAP register, in which case it's saved and
2796 * restored beforehand:
2797 *
2798 * 41 55 push %r13
2799 * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
2800 * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
2801 * ...
2802 * 49 8d 65 f0 lea -0x10(%r13),%rsp
2803 * 41 5d pop %r13
2804 * c3 retq
2805 */
d54dba41
PZ		 2806static int update_cfi_state(struct instruction *insn,
2807 struct instruction *next_insn,
2808 struct cfi_state *cfi, struct stack_op *op)
baa41469 2809{
e7c0219b
PZ		 2810 struct cfi_reg *cfa = &cfi->cfa;
2811 struct cfi_reg *regs = cfi->regs;
baa41469 2812
1e4b6191
JP		 2813 /* ignore UNWIND_HINT_UNDEFINED regions */
2814 if (cfi->force_undefined)
2815 return 0;
2816
baa41469
JP		 2817 /* stack operations don't make sense with an undefined CFA */
2818 if (cfa->base == CFI_UNDEFINED) {
dbcdbdfd 2819 if (insn_func(insn)) {
246b2c85 2820 WARN_INSN(insn, "undefined stack state");
baa41469
JP		 2821 return -1;
2822 }
2823 return 0;
2824 }
2825
ee819aed
JT		 2826 if (cfi->type == UNWIND_HINT_TYPE_REGS ||
2827 cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
e7c0219b 2828 return update_cfi_state_regs(insn, cfi, op);
627fce14 2829
baa41469
JP		 2830 switch (op->dest.type) {
2831
2832 case OP_DEST_REG:
2833 switch (op->src.type) {
2834
2835 case OP_SRC_REG:
0d0970ee
JP		 2836 if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
2837 cfa->base == CFI_SP &&
fb084fde 2838 check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {
0d0970ee
JP		 2839
2840 /* mov %rsp, %rbp */
2841 cfa->base = op->dest.reg;
e7c0219b 2842 cfi->bp_scratch = false;
0d0970ee 2843 }
dd88a0a0 2844
0d0970ee 2845 else if (op->src.reg == CFI_SP &&
e7c0219b 2846 op->dest.reg == CFI_BP && cfi->drap) {
dd88a0a0 2847
0d0970ee
JP		 2848 /* drap: mov %rsp, %rbp */
2849 regs[CFI_BP].base = CFI_BP;
e7c0219b
PZ		 2850 regs[CFI_BP].offset = -cfi->stack_size;
2851 cfi->bp_scratch = false;
0d0970ee 2852 }
dd88a0a0 2853
0d0970ee
JP		 2854 else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2855
2856 /*
2857 * mov %rsp, %reg
2858 *
2859 * This is needed for the rare case where GCC
2860 * does:
2861 *
2862 * mov %rsp, %rax
2863 * ...
2864 * mov %rax, %rsp
2865 */
e7c0219b
PZ		 2866 cfi->vals[op->dest.reg].base = CFI_CFA;
2867 cfi->vals[op->dest.reg].offset = -cfi->stack_size;
dd88a0a0
JP		 2868 }
2869
3c1f0583 2870 else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
ffc7e74f 2871 (cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {
3c1f0583
JP		 2872
2873 /*
2874 * mov %rbp, %rsp
2875 *
2876 * Restore the original stack pointer (Clang).
2877 */
e7c0219b 2878 cfi->stack_size = -cfi->regs[CFI_BP].offset;
3c1f0583
JP		 2879 }
2880
dd88a0a0
JP		 2881 else if (op->dest.reg == cfa->base) {
2882
2883 /* mov %reg, %rsp */
2884 if (cfa->base == CFI_SP &&
e7c0219b 2885 cfi->vals[op->src.reg].base == CFI_CFA) {
dd88a0a0
JP		 2886
2887 /*
2888 * This is needed for the rare case
2889 * where GCC does something dumb like:
2890 *
2891 * lea 0x8(%rsp), %rcx
2892 * ...
2893 * mov %rcx, %rsp
2894 */
e7c0219b
PZ		 2895 cfa->offset = -cfi->vals[op->src.reg].offset;
2896 cfi->stack_size = cfa->offset;
dd88a0a0 2897
aafeb14e
PZ		 2898 } else if (cfa->base == CFI_SP &&
2899 cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2900 cfi->vals[op->src.reg].offset == cfa->offset) {
2901
2902 /*
2903 * Stack swizzle:
2904 *
2905 * 1: mov %rsp, (%[tos])
2906 * 2: mov %[tos], %rsp
2907 * ...
2908 * 3: pop %rsp
2909 *
2910 * Where:
2911 *
2912 * 1 - places a pointer to the previous
2913 * stack at the Top-of-Stack of the
2914 * new stack.
2915 *
2916 * 2 - switches to the new stack.
2917 *
2918 * 3 - pops the Top-of-Stack to restore
2919 * the original stack.
2920 *
2921 * Note: we set base to SP_INDIRECT
2922 * here and preserve offset. Therefore
2923 * when the unwinder reaches ToS it
2924 * will dereference SP and then add the
2925 * offset to find the next frame, IOW:
2926 * (%rsp) + offset.
2927 */
2928 cfa->base = CFI_SP_INDIRECT;
2929
dd88a0a0
JP		 2930 } else {
2931 cfa->base = CFI_UNDEFINED;
2932 cfa->offset = 0;
2933 }
baa41469
JP		 2934 }
2935
724c8a23
PZ		 2936 else if (op->dest.reg == CFI_SP &&
2937 cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2938 cfi->vals[op->src.reg].offset == cfa->offset) {
2939
2940 /*
2941 * The same stack swizzle case 2) as above. But
2942 * because we can't change cfa->base, case 3)
2943 * will become a regular POP. Pretend we're a
2944 * PUSH so things don't go unbalanced.
2945 */
2946 cfi->stack_size += 8;
2947 }
2948
2949
baa41469
JP		 2950 break;
2951
2952 case OP_SRC_ADD:
2953 if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
2954
2955 /* add imm, %rsp */
e7c0219b 2956 cfi->stack_size -= op->src.offset;
baa41469
JP		 2957 if (cfa->base == CFI_SP)
2958 cfa->offset -= op->src.offset;
2959 break;
2960 }
2961
2962 if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
2963
2964 /* lea disp(%rbp), %rsp */
e7c0219b 2965 cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
baa41469
JP		 2966 break;
2967 }
2968
dd88a0a0 2969 if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
baa41469
JP		 2970
2971 /* drap: lea disp(%rsp), %drap */
e7c0219b 2972 cfi->drap_reg = op->dest.reg;
dd88a0a0
JP		 2973
2974 /*
2975 * lea disp(%rsp), %reg
2976 *
2977 * This is needed for the rare case where GCC
2978 * does something dumb like:
2979 *
2980 * lea 0x8(%rsp), %rcx
2981 * ...
2982 * mov %rcx, %rsp
2983 */
e7c0219b
PZ		 2984 cfi->vals[op->dest.reg].base = CFI_CFA;
2985 cfi->vals[op->dest.reg].offset = \
2986 -cfi->stack_size + op->src.offset;
dd88a0a0 2987
baa41469
JP		 2988 break;
2989 }
2990
e7c0219b
PZ		 2991 if (cfi->drap && op->dest.reg == CFI_SP &&
2992 op->src.reg == cfi->drap_reg) {
baa41469
JP		 2993
2994 /* drap: lea disp(%drap), %rsp */
2995 cfa->base = CFI_SP;
e7c0219b
PZ		 2996 cfa->offset = cfi->stack_size = -op->src.offset;
2997 cfi->drap_reg = CFI_UNDEFINED;
2998 cfi->drap = false;
baa41469
JP		 2999 break;
3000 }
3001
d54dba41 3002 if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
246b2c85 3003 WARN_INSN(insn, "unsupported stack register modification");
baa41469
JP		 3004 return -1;
3005 }
3006
3007 break;
3008
3009 case OP_SRC_AND:
3010 if (op->dest.reg != CFI_SP ||
e7c0219b
PZ		 3011 (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
3012 (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
246b2c85 3013 WARN_INSN(insn, "unsupported stack pointer realignment");
baa41469
JP		 3014 return -1;
3015 }
3016
e7c0219b 3017 if (cfi->drap_reg != CFI_UNDEFINED) {
baa41469 3018 /* drap: and imm, %rsp */
e7c0219b
PZ		 3019 cfa->base = cfi->drap_reg;
3020 cfa->offset = cfi->stack_size = 0;
3021 cfi->drap = true;
baa41469
JP		 3022 }
3023
3024 /*
3025 * Older versions of GCC (4.8ish) realign the stack
3026 * without DRAP, with a frame pointer.
3027 */
3028
3029 break;
3030
3031 case OP_SRC_POP:
ea24213d 3032 case OP_SRC_POPF:
aafeb14e
PZ		 3033 if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
3034
3035 /* pop %rsp; # restore from a stack swizzle */
3036 cfa->base = CFI_SP;
3037 break;
3038 }
3039
e7c0219b 3040 if (!cfi->drap && op->dest.reg == cfa->base) {
baa41469
JP		 3041
3042 /* pop %rbp */
3043 cfa->base = CFI_SP;
3044 }
3045
e7c0219b
PZ		 3046 if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
3047 op->dest.reg == cfi->drap_reg &&
3048 cfi->drap_offset == -cfi->stack_size) {
baa41469 3049
bf4d1a83 3050 /* drap: pop %drap */
e7c0219b 3051 cfa->base = cfi->drap_reg;
bf4d1a83 3052 cfa->offset = 0;
e7c0219b 3053 cfi->drap_offset = -1;
baa41469 3054
ffc7e74f 3055 } else if (cfi->stack_size == -regs[op->dest.reg].offset) {
baa41469 3056
bf4d1a83 3057 /* pop %reg */
e7c0219b 3058 restore_reg(cfi, op->dest.reg);
baa41469
JP		 3059 }
3060
e7c0219b 3061 cfi->stack_size -= 8;
baa41469
JP		 3062 if (cfa->base == CFI_SP)
3063 cfa->offset -= 8;
3064
3065 break;
3066
3067 case OP_SRC_REG_INDIRECT:
201ef5a9
JT		 3068 if (!cfi->drap && op->dest.reg == cfa->base &&
3069 op->dest.reg == CFI_BP) {
3070
3071 /* mov disp(%rsp), %rbp */
3072 cfa->base = CFI_SP;
3073 cfa->offset = cfi->stack_size;
3074 }
3075
e7c0219b
PZ		 3076 if (cfi->drap && op->src.reg == CFI_BP &&
3077 op->src.offset == cfi->drap_offset) {
bf4d1a83
JP		 3078
3079 /* drap: mov disp(%rbp), %drap */
e7c0219b 3080 cfa->base = cfi->drap_reg;
bf4d1a83 3081 cfa->offset = 0;
e7c0219b 3082 cfi->drap_offset = -1;
bf4d1a83
JP		 3083 }
3084
e7c0219b 3085 if (cfi->drap && op->src.reg == CFI_BP &&
baa41469
JP		 3086 op->src.offset == regs[op->dest.reg].offset) {
3087
3088 /* drap: mov disp(%rbp), %reg */
e7c0219b 3089 restore_reg(cfi, op->dest.reg);
baa41469
JP		 3090
3091 } else if (op->src.reg == cfa->base &&
3092 op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
3093
3094 /* mov disp(%rbp), %reg */
3095 /* mov disp(%rsp), %reg */
e7c0219b 3096 restore_reg(cfi, op->dest.reg);
201ef5a9
JT		 3097
3098 } else if (op->src.reg == CFI_SP &&
3099 op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
3100
3101 /* mov disp(%rsp), %reg */
3102 restore_reg(cfi, op->dest.reg);
baa41469
JP		 3103 }
3104
3105 break;
3106
3107 default:
246b2c85 3108 WARN_INSN(insn, "unknown stack-related instruction");
baa41469
JP		 3109 return -1;
3110 }
3111
3112 break;
3113
3114 case OP_DEST_PUSH:
ea24213d 3115 case OP_DEST_PUSHF:
e7c0219b 3116 cfi->stack_size += 8;
baa41469
JP		 3117 if (cfa->base == CFI_SP)
3118 cfa->offset += 8;
3119
3120 if (op->src.type != OP_SRC_REG)
3121 break;
3122
e7c0219b
PZ		 3123 if (cfi->drap) {
3124 if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
baa41469
JP		 3125
3126 /* drap: push %drap */
3127 cfa->base = CFI_BP_INDIRECT;
e7c0219b 3128 cfa->offset = -cfi->stack_size;
baa41469 3129
bf4d1a83 3130 /* save drap so we know when to restore it */
e7c0219b 3131 cfi->drap_offset = -cfi->stack_size;
baa41469 3132
e7c0219b 3133 } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
baa41469
JP		 3134
3135 /* drap: push %rbp */
e7c0219b 3136 cfi->stack_size = 0;
baa41469 3137
f4f80398 3138 } else {
baa41469
JP		 3139
3140 /* drap: push %reg */
e7c0219b 3141 save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
baa41469
JP		 3142 }
3143
3144 } else {
3145
3146 /* push %reg */
e7c0219b 3147 save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
baa41469
JP		 3148 }
3149
3150 /* detect when asm code uses rbp as a scratch register */
dbcdbdfd 3151 if (opts.stackval && insn_func(insn) && op->src.reg == CFI_BP &&
baa41469 3152 cfa->base != CFI_BP)
e7c0219b 3153 cfi->bp_scratch = true;
baa41469
JP		 3154 break;
3155
3156 case OP_DEST_REG_INDIRECT:
3157
e7c0219b
PZ		 3158 if (cfi->drap) {
3159 if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
baa41469
JP		 3160
3161 /* drap: mov %drap, disp(%rbp) */
3162 cfa->base = CFI_BP_INDIRECT;
3163 cfa->offset = op->dest.offset;
3164
bf4d1a83 3165 /* save drap offset so we know when to restore it */
e7c0219b 3166 cfi->drap_offset = op->dest.offset;
f4f80398 3167 } else {
baa41469
JP		 3168
3169 /* drap: mov reg, disp(%rbp) */
e7c0219b 3170 save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
baa41469
JP		 3171 }
3172
3173 } else if (op->dest.reg == cfa->base) {
3174
3175 /* mov reg, disp(%rbp) */
3176 /* mov reg, disp(%rsp) */
e7c0219b
PZ		 3177 save_reg(cfi, op->src.reg, CFI_CFA,
3178 op->dest.offset - cfi->cfa.offset);
201ef5a9
JT		 3179
3180 } else if (op->dest.reg == CFI_SP) {
3181
3182 /* mov reg, disp(%rsp) */
3183 save_reg(cfi, op->src.reg, CFI_CFA,
3184 op->dest.offset - cfi->stack_size);
aafeb14e
PZ		 3185
3186 } else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
3187
3188 /* mov %rsp, (%reg); # setup a stack swizzle. */
3189 cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
3190 cfi->vals[op->dest.reg].offset = cfa->offset;
baa41469
JP		 3191 }
3192
3193 break;
3194
baa41469 3195 case OP_DEST_MEM:
ea24213d 3196 if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
246b2c85 3197 WARN_INSN(insn, "unknown stack-related memory operation");
baa41469
JP		 3198 return -1;
3199 }
3200
3201 /* pop mem */
e7c0219b 3202 cfi->stack_size -= 8;
baa41469
JP		 3203 if (cfa->base == CFI_SP)
3204 cfa->offset -= 8;
3205
3206 break;
3207
3208 default:
246b2c85 3209 WARN_INSN(insn, "unknown stack-related instruction");
baa41469
JP		 3210 return -1;
3211 }
3212
3213 return 0;
3214}
3215
c9c324dc
JP		 3216/*
3217 * The stack layouts of alternatives instructions can sometimes diverge when
3218 * they have stack modifications. That's fine as long as the potential stack
3219 * layouts don't conflict at any given potential instruction boundary.
3220 *
3221 * Flatten the CFIs of the different alternative code streams (both original
3222 * and replacement) into a single shared CFI array which can be used to detect
3223 * conflicts and nicely feed a linear array of ORC entries to the unwinder.
3224 */
3225static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
65ea47dc 3226{
c9c324dc
JP		 3227 struct cfi_state **alt_cfi;
3228 int group_off;
65ea47dc 3229
c9c324dc
JP		 3230 if (!insn->alt_group)
3231 return 0;
65ea47dc 3232
8b946cc3
PZ		 3233 if (!insn->cfi) {
3234 WARN("CFI missing");
3235 return -1;
3236 }
3237
c9c324dc
JP		 3238 alt_cfi = insn->alt_group->cfi;
3239 group_off = insn->offset - insn->alt_group->first_insn->offset;
65ea47dc 3240
c9c324dc 3241 if (!alt_cfi[group_off]) {
8b946cc3 3242 alt_cfi[group_off] = insn->cfi;
c9c324dc 3243 } else {
8b946cc3 3244 if (cficmp(alt_cfi[group_off], insn->cfi)) {
a706bb08
PZ		 3245 struct alt_group *orig_group = insn->alt_group->orig_group ?: insn->alt_group;
3246 struct instruction *orig = orig_group->first_insn;
3247 char *where = offstr(insn->sec, insn->offset);
246b2c85 3248 WARN_INSN(orig, "stack layout conflict in alternatives: %s", where);
a706bb08 3249 free(where);
ab3852ab
PZ		 3250 return -1;
3251 }
c9c324dc
JP		 3252 }
3253
3254 return 0;
3255}
3256
d54dba41
PZ		 3257static int handle_insn_ops(struct instruction *insn,
3258 struct instruction *next_insn,
3259 struct insn_state *state)
c9c324dc
JP		 3260{
3261 struct stack_op *op;
3262
3ee88df1 3263 for (op = insn->stack_ops; op; op = op->next) {
c9c324dc 3264
d54dba41 3265 if (update_cfi_state(insn, next_insn, &state->cfi, op))
c9c324dc 3266 return 1;
ab3852ab 3267
ba08abca
PZ		 3268 if (!insn->alt_group)
3269 continue;
3270
65ea47dc
JT		 3271 if (op->dest.type == OP_DEST_PUSHF) {
3272 if (!state->uaccess_stack) {
3273 state->uaccess_stack = 1;
3274 } else if (state->uaccess_stack >> 31) {
246b2c85 3275 WARN_INSN(insn, "PUSHF stack exhausted");
65ea47dc
JT		 3276 return 1;
3277 }
3278 state->uaccess_stack <<= 1;
3279 state->uaccess_stack |= state->uaccess;
3280 }
3281
3282 if (op->src.type == OP_SRC_POPF) {
3283 if (state->uaccess_stack) {
3284 state->uaccess = state->uaccess_stack & 1;
3285 state->uaccess_stack >>= 1;
3286 if (state->uaccess_stack == 1)
3287 state->uaccess_stack = 0;
3288 }
3289 }
3290 }
3291
3292 return 0;
3293}
3294
e7c0219b 3295static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
baa41469 3296{
8b946cc3 3297 struct cfi_state *cfi1 = insn->cfi;
baa41469
JP		 3298 int i;
3299
8b946cc3
PZ		 3300 if (!cfi1) {
3301 WARN("CFI missing");
3302 return false;
3303 }
3304
e7c0219b
PZ		 3305 if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
3306
246b2c85 3307 WARN_INSN(insn, "stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
e7c0219b
PZ		 3308 cfi1->cfa.base, cfi1->cfa.offset,
3309 cfi2->cfa.base, cfi2->cfa.offset);
baa41469 3310
e7c0219b 3311 } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
baa41469 3312 for (i = 0; i < CFI_NUM_REGS; i++) {
e7c0219b 3313 if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
baa41469
JP		 3314 sizeof(struct cfi_reg)))
3315 continue;
3316
246b2c85 3317 WARN_INSN(insn, "stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
e7c0219b
PZ		 3318 i, cfi1->regs[i].base, cfi1->regs[i].offset,
3319 i, cfi2->regs[i].base, cfi2->regs[i].offset);
baa41469
JP		 3320 break;
3321 }
3322
e7c0219b
PZ		 3323 } else if (cfi1->type != cfi2->type) {
3324
246b2c85
JP		 3325 WARN_INSN(insn, "stack state mismatch: type1=%d type2=%d",
3326 cfi1->type, cfi2->type);
e7c0219b
PZ		 3327
3328 } else if (cfi1->drap != cfi2->drap ||
3329 (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
3330 (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
627fce14 3331
246b2c85 3332 WARN_INSN(insn, "stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
e7c0219b
PZ		 3333 cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
3334 cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
baa41469
JP		 3335
3336 } else
3337 return true;
3338
3339 return false;
dcc914f4
JP		 3340}
3341
ea24213d
PZ		 3342static inline bool func_uaccess_safe(struct symbol *func)
3343{
3344 if (func)
e10cd8fe 3345 return func->uaccess_safe;
ea24213d
PZ		 3346
3347 return false;
3348}
3349
0c1ddd33 3350static inline const char *call_dest_name(struct instruction *insn)
ea24213d 3351{
82880283 3352 static char pvname[19];
a5bd6236 3353 struct reloc *reloc;
db2b0c5d
PZ		 3354 int idx;
3355
c6f5dc28
PZ		 3356 if (insn_call_dest(insn))
3357 return insn_call_dest(insn)->name;
ea24213d 3358
a5bd6236
JP		 3359 reloc = insn_reloc(NULL, insn);
3360 if (reloc && !strcmp(reloc->sym->name, "pv_ops")) {
0696b6e3 3361 idx = (reloc_addend(reloc) / sizeof(void *));
db2b0c5d
PZ		 3362 snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
3363 return pvname;
3364 }
3365
ea24213d
PZ		 3366 return "{dynamic}";
3367}
3368
db2b0c5d
PZ		 3369static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
3370{
3371 struct symbol *target;
a5bd6236 3372 struct reloc *reloc;
db2b0c5d
PZ		 3373 int idx;
3374
a5bd6236
JP		 3375 reloc = insn_reloc(file, insn);
3376 if (!reloc || strcmp(reloc->sym->name, "pv_ops"))
db2b0c5d
PZ		 3377 return false;
3378
0696b6e3 3379 idx = (arch_dest_reloc_offset(reloc_addend(reloc)) / sizeof(void *));
db2b0c5d
PZ		 3380
3381 if (file->pv_ops[idx].clean)
3382 return true;
3383
3384 file->pv_ops[idx].clean = true;
3385
3386 list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
3387 if (!target->sec->noinstr) {
3388 WARN("pv_ops[%d]: %s", idx, target->name);
3389 file->pv_ops[idx].clean = false;
3390 }
3391 }
3392
3393 return file->pv_ops[idx].clean;
3394}
3395
3396static inline bool noinstr_call_dest(struct objtool_file *file,
3397 struct instruction *insn,
3398 struct symbol *func)
6b643a07
PZ		 3399{
3400 /*
3401 * We can't deal with indirect function calls at present;
3402 * assume they're instrumented.
3403 */
db2b0c5d
PZ		 3404 if (!func) {
3405 if (file->pv_ops)
3406 return pv_call_dest(file, insn);
3407
6b643a07 3408 return false;
db2b0c5d 3409 }
6b643a07
PZ		 3410
3411 /*
3412 * If the symbol is from a noinstr section; we good.
3413 */
3414 if (func->sec->noinstr)
3415 return true;
3416
2b5a0e42
PZ		 3417 /*
3418 * If the symbol is a static_call trampoline, we can't tell.
3419 */
3420 if (func->static_call_tramp)
3421 return true;
3422
6b643a07
PZ		 3423 /*
3424 * The __ubsan_handle_*() calls are like WARN(), they only happen when
3425 * something 'BAD' happened. At the risk of taking the machine down,
3426 * let them proceed to get the message out.
3427 */
3428 if (!strncmp(func->name, "__ubsan_handle_", 15))
3429 return true;
3430
3431 return false;
3432}
3433
db2b0c5d
PZ		 3434static int validate_call(struct objtool_file *file,
3435 struct instruction *insn,
3436 struct insn_state *state)
ea24213d 3437{
c4a33939 3438 if (state->noinstr && state->instr <= 0 &&
c6f5dc28 3439 !noinstr_call_dest(file, insn, insn_call_dest(insn))) {
246b2c85 3440 WARN_INSN(insn, "call to %s() leaves .noinstr.text section", call_dest_name(insn));
c4a33939
PZ		 3441 return 1;
3442 }
3443
c6f5dc28 3444 if (state->uaccess && !func_uaccess_safe(insn_call_dest(insn))) {
246b2c85 3445 WARN_INSN(insn, "call to %s() with UACCESS enabled", call_dest_name(insn));
ea24213d
PZ		 3446 return 1;
3447 }
3448
2f0f9e9a 3449 if (state->df) {
246b2c85 3450 WARN_INSN(insn, "call to %s() with DF set", call_dest_name(insn));
2f0f9e9a
PZ		 3451 return 1;
3452 }
3453
ea24213d
PZ		 3454 return 0;
3455}
3456
db2b0c5d
PZ		 3457static int validate_sibling_call(struct objtool_file *file,
3458 struct instruction *insn,
3459 struct insn_state *state)
54262aa2 3460{
5a9c361a 3461 if (insn_func(insn) && has_modified_stack_frame(insn, state)) {
246b2c85 3462 WARN_INSN(insn, "sibling call from callable instruction with modified stack frame");
54262aa2
PZ		 3463 return 1;
3464 }
3465
db2b0c5d 3466 return validate_call(file, insn, state);
54262aa2
PZ		 3467}
3468
a92e92d1
PZ		 3469static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
3470{
c4a33939 3471 if (state->noinstr && state->instr > 0) {
246b2c85 3472 WARN_INSN(insn, "return with instrumentation enabled");
c4a33939
PZ		 3473 return 1;
3474 }
3475
a92e92d1 3476 if (state->uaccess && !func_uaccess_safe(func)) {
246b2c85 3477 WARN_INSN(insn, "return with UACCESS enabled");
a92e92d1
PZ		 3478 return 1;
3479 }
3480
3481 if (!state->uaccess && func_uaccess_safe(func)) {
246b2c85 3482 WARN_INSN(insn, "return with UACCESS disabled from a UACCESS-safe function");
a92e92d1
PZ		 3483 return 1;
3484 }
3485
3486 if (state->df) {
246b2c85 3487 WARN_INSN(insn, "return with DF set");
a92e92d1
PZ		 3488 return 1;
3489 }
3490
e25eea89 3491 if (func && has_modified_stack_frame(insn, state)) {
246b2c85 3492 WARN_INSN(insn, "return with modified stack frame");
a92e92d1
PZ		 3493 return 1;
3494 }
3495
e7c0219b 3496 if (state->cfi.bp_scratch) {
246b2c85 3497 WARN_INSN(insn, "BP used as a scratch register");
a92e92d1
PZ		 3498 return 1;
3499 }
3500
3501 return 0;
3502}
3503
c9c324dc
JP		 3504static struct instruction *next_insn_to_validate(struct objtool_file *file,
3505 struct instruction *insn)
7117f16b 3506{
b23cc71c 3507 struct alt_group *alt_group = insn->alt_group;
7117f16b 3508
c9c324dc
JP		 3509 /*
3510 * Simulate the fact that alternatives are patched in-place. When the
3511 * end of a replacement alt_group is reached, redirect objtool flow to
3512 * the end of the original alt_group.
1c34496e
PZ		 3513 *
3514 * insn->alts->insn -> alt_group->first_insn
3515 * ...
3516 * alt_group->last_insn
3517 * [alt_group->nop] -> next(orig_group->last_insn)
c9c324dc 3518 */
1c34496e
PZ		 3519 if (alt_group) {
3520 if (alt_group->nop) {
3521 /* ->nop implies ->orig_group */
3522 if (insn == alt_group->last_insn)
3523 return alt_group->nop;
3524 if (insn == alt_group->nop)
3525 goto next_orig;
3526 }
3527 if (insn == alt_group->last_insn && alt_group->orig_group)
3528 goto next_orig;
3529 }
c9c324dc
JP		 3530
3531 return next_insn_same_sec(file, insn);
1c34496e
PZ		 3532
3533next_orig:
3534 return next_insn_same_sec(file, alt_group->orig_group->last_insn);
7117f16b
PZ		 3535}
3536
dcc914f4
JP		 3537/*
3538 * Follow the branch starting at the given instruction, and recursively follow
3539 * any other branches (jumps). Meanwhile, track the frame pointer state at
3540 * each instruction and validate all the rules described in
d6a21f2d 3541 * tools/objtool/Documentation/objtool.txt.
dcc914f4 3542 */
c705cecc 3543static int validate_branch(struct objtool_file *file, struct symbol *func,
b7460462 3544 struct instruction *insn, struct insn_state state)
dcc914f4
JP		 3545{
3546 struct alternative *alt;
8b946cc3 3547 struct instruction *next_insn, *prev_insn = NULL;
dcc914f4 3548 struct section *sec;
882a0db9 3549 u8 visited;
dcc914f4
JP		 3550 int ret;
3551
dcc914f4 3552 sec = insn->sec;
dcc914f4 3553
dcc914f4 3554 while (1) {
c9c324dc 3555 next_insn = next_insn_to_validate(file, insn);
39358a03 3556
dbcdbdfd 3557 if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
3c68a92d 3558 /* Ignore KCFI type preambles, which always fall through */
9f2899fe
PZ		 3559 if (!strncmp(func->name, "__cfi_", 6) ||
3560 !strncmp(func->name, "__pfx_", 6))
3c68a92d
ST		 3561 return 0;
3562
ee97638b 3563 WARN("%s() falls through to next function %s()",
dbcdbdfd 3564 func->name, insn_func(insn)->name);
ee97638b 3565 return 1;
dcc914f4
JP		 3566 }
3567
4855022a 3568 if (func && insn->ignore) {
246b2c85 3569 WARN_INSN(insn, "BUG: why am I validating an ignored function?");
12b25729 3570 return 1;
4855022a
JP		 3571 }
3572
a09a6e23
PZ		 3573 visited = VISITED_BRANCH << state.uaccess;
3574 if (insn->visited & VISITED_BRANCH_MASK) {
e7c0219b 3575 if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
dcc914f4 3576 return 1;
dcc914f4 3577
882a0db9 3578 if (insn->visited & visited)
ea24213d 3579 return 0;
8b946cc3
PZ		 3580 } else {
3581 nr_insns_visited++;
dcc914f4
JP		 3582 }
3583
c4a33939
PZ		 3584 if (state.noinstr)
3585 state.instr += insn->instr;
3586
8b946cc3 3587 if (insn->hint) {
8faea26e
JP		 3588 if (insn->restore) {
3589 struct instruction *save_insn, *i;
3590
3591 i = insn;
3592 save_insn = NULL;
3593
3594 sym_for_each_insn_continue_reverse(file, func, i) {
3595 if (i->save) {
3596 save_insn = i;
3597 break;
3598 }
3599 }
3600
3601 if (!save_insn) {
246b2c85 3602 WARN_INSN(insn, "no corresponding CFI save for CFI restore");
8faea26e
JP		 3603 return 1;
3604 }
3605
3606 if (!save_insn->visited) {
246b2c85 3607 WARN_INSN(insn, "objtool isn't smart enough to handle this CFI save/restore combo");
8faea26e
JP		 3608 return 1;
3609 }
3610
3611 insn->cfi = save_insn->cfi;
3612 nr_cfi_reused++;
3613 }
3614
8b946cc3
PZ		 3615 state.cfi = *insn->cfi;
3616 } else {
3617 /* XXX track if we actually changed state.cfi */
3618
3619 if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {
3620 insn->cfi = prev_insn->cfi;
3621 nr_cfi_reused++;
3622 } else {
3623 insn->cfi = cfi_hash_find_or_add(&state.cfi);
3624 }
3625 }
dcc914f4 3626
882a0db9 3627 insn->visited |= visited;
baa41469 3628
c9c324dc
JP		 3629 if (propagate_alt_cfi(file, insn))
3630 return 1;
3631
d5406654 3632 if (!insn->ignore_alts && insn->alts) {
764eef4b
PZ		 3633 bool skip_orig = false;
3634
d5406654 3635 for (alt = insn->alts; alt; alt = alt->next) {
764eef4b
PZ		 3636 if (alt->skip_orig)
3637 skip_orig = true;
3638
c705cecc 3639 ret = validate_branch(file, func, alt->insn, state);
7697eee3 3640 if (ret) {
ced23d2e 3641 BT_INSN(insn, "(alt)");
7697eee3
PZ		 3642 return ret;
3643 }
a845c7cf 3644 }
764eef4b
PZ		 3645
3646 if (skip_orig)
3647 return 0;
dcc914f4
JP		 3648 }
3649
d54dba41 3650 if (handle_insn_ops(insn, next_insn, &state))
60041bcd
PZ		 3651 return 1;
3652
dcc914f4
JP		 3653 switch (insn->type) {
3654
dcc914f4 3655 case INSN_RETURN:
a92e92d1 3656 return validate_return(func, insn, &state);
dcc914f4
JP		 3657
3658 case INSN_CALL:
ea24213d 3659 case INSN_CALL_DYNAMIC:
db2b0c5d 3660 ret = validate_call(file, insn, &state);
ea24213d
PZ		 3661 if (ret)
3662 return ret;
dcc914f4 3663
dbf46008 3664 if (opts.stackval && func && !is_special_call(insn) &&
c9bab22b 3665 !has_valid_stack_frame(&state)) {
246b2c85 3666 WARN_INSN(insn, "call without frame pointer save/setup");
dcc914f4
JP		 3667 return 1;
3668 }
c9bab22b 3669
0e5b613b 3670 if (insn->dead_end)
c9bab22b
JP		 3671 return 0;
3672
dcc914f4
JP		 3673 break;
3674
3675 case INSN_JUMP_CONDITIONAL:
3676 case INSN_JUMP_UNCONDITIONAL:
ecf11ba4 3677 if (is_sibling_call(insn)) {
db2b0c5d 3678 ret = validate_sibling_call(file, insn, &state);
dcc914f4 3679 if (ret)
54262aa2 3680 return ret;
4855022a 3681
0c1ddd33 3682 } else if (insn->jump_dest) {
c705cecc
JP		 3683 ret = validate_branch(file, func,
3684 insn->jump_dest, state);
7697eee3 3685 if (ret) {
ced23d2e 3686 BT_INSN(insn, "(branch)");
7697eee3
PZ		 3687 return ret;
3688 }
4855022a 3689 }
dcc914f4
JP		 3690
3691 if (insn->type == INSN_JUMP_UNCONDITIONAL)
3692 return 0;
3693
3694 break;
3695
3696 case INSN_JUMP_DYNAMIC:
b68b9907 3697 case INSN_JUMP_DYNAMIC_CONDITIONAL:
ecf11ba4 3698 if (is_sibling_call(insn)) {
db2b0c5d 3699 ret = validate_sibling_call(file, insn, &state);
54262aa2
PZ		 3700 if (ret)
3701 return ret;
dcc914f4
JP		 3702 }
3703
b68b9907
JP		 3704 if (insn->type == INSN_JUMP_DYNAMIC)
3705 return 0;
3706
3707 break;
dcc914f4 3708
39358a03
JP		 3709 case INSN_CONTEXT_SWITCH:
3710 if (func && (!next_insn || !next_insn->hint)) {
246b2c85 3711 WARN_INSN(insn, "unsupported instruction in callable function");
39358a03
JP		 3712 return 1;
3713 }
3714 return 0;
3715
ea24213d
PZ		 3716 case INSN_STAC:
3717 if (state.uaccess) {
246b2c85 3718 WARN_INSN(insn, "recursive UACCESS enable");
ea24213d
PZ		 3719 return 1;
3720 }
3721
3722 state.uaccess = true;
3723 break;
3724
3725 case INSN_CLAC:
c705cecc 3726 if (!state.uaccess && func) {
246b2c85 3727 WARN_INSN(insn, "redundant UACCESS disable");
ea24213d
PZ		 3728 return 1;
3729 }
3730
3731 if (func_uaccess_safe(func) && !state.uaccess_stack) {
246b2c85 3732 WARN_INSN(insn, "UACCESS-safe disables UACCESS");
ea24213d
PZ		 3733 return 1;
3734 }
3735
3736 state.uaccess = false;
baa41469
JP		 3737 break;
3738
2f0f9e9a 3739 case INSN_STD:
6f567c93 3740 if (state.df) {
246b2c85 3741 WARN_INSN(insn, "recursive STD");
6f567c93
JP		 3742 return 1;
3743 }
2f0f9e9a
PZ		 3744
3745 state.df = true;
3746 break;
3747
3748 case INSN_CLD:
6f567c93 3749 if (!state.df && func) {
246b2c85 3750 WARN_INSN(insn, "redundant CLD");
6f567c93
JP		 3751 return 1;
3752 }
2f0f9e9a
PZ		 3753
3754 state.df = false;
baa41469
JP		 3755 break;
3756
dcc914f4
JP		 3757 default:
3758 break;
3759 }
3760
3761 if (insn->dead_end)
3762 return 0;
3763
00d96180 3764 if (!next_insn) {
e7c0219b 3765 if (state.cfi.cfa.base == CFI_UNDEFINED)
00d96180 3766 return 0;
dcc914f4
JP		 3767 WARN("%s: unexpected end of section", sec->name);
3768 return 1;
3769 }
00d96180 3770
8b946cc3 3771 prev_insn = insn;
00d96180 3772 insn = next_insn;
dcc914f4
JP		 3773 }
3774
3775 return 0;
3776}
3777
1c34496e
PZ		 3778static int validate_unwind_hint(struct objtool_file *file,
3779 struct instruction *insn,
3780 struct insn_state *state)
3781{
3782 if (insn->hint && !insn->visited && !insn->ignore) {
3783 int ret = validate_branch(file, insn_func(insn), insn, *state);
ced23d2e
JP		 3784 if (ret)
3785 BT_INSN(insn, "<=== (hint)");
1c34496e
PZ		 3786 return ret;
3787 }
3788
3789 return 0;
3790}
3791
932f8e98 3792static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
39358a03
JP		 3793{
3794 struct instruction *insn;
39358a03 3795 struct insn_state state;
1c34496e 3796 int warnings = 0;
39358a03
JP		 3797
3798 if (!file->hints)
3799 return 0;
3800
753da417 3801 init_insn_state(file, &state, sec);
39358a03 3802
932f8e98 3803 if (sec) {
1c34496e
PZ		 3804 sec_for_each_insn(file, sec, insn)
3805 warnings += validate_unwind_hint(file, insn, &state);
932f8e98 3806 } else {
1c34496e
PZ		 3807 for_each_insn(file, insn)
3808 warnings += validate_unwind_hint(file, insn, &state);
39358a03
JP		 3809 }
3810
3811 return warnings;
3812}
3813
a09a6e23
PZ		 3814/*
3815 * Validate rethunk entry constraint: must untrain RET before the first RET.
3816 *
4708ea14 3817 * Follow every branch (intra-function) and ensure VALIDATE_UNRET_END comes
a09a6e23
PZ		 3818 * before an actual RET instruction.
3819 */
4708ea14 3820static int validate_unret(struct objtool_file *file, struct instruction *insn)
a09a6e23
PZ		 3821{
3822 struct instruction *next, *dest;
d49d1666 3823 int ret;
a09a6e23
PZ		 3824
3825 for (;;) {
3826 next = next_insn_to_validate(file, insn);
3827
4708ea14 3828 if (insn->visited & VISITED_UNRET)
a09a6e23
PZ		 3829 return 0;
3830
4708ea14 3831 insn->visited |= VISITED_UNRET;
a09a6e23 3832
d5406654 3833 if (!insn->ignore_alts && insn->alts) {
a09a6e23
PZ		 3834 struct alternative *alt;
3835 bool skip_orig = false;
3836
d5406654 3837 for (alt = insn->alts; alt; alt = alt->next) {
a09a6e23
PZ		 3838 if (alt->skip_orig)
3839 skip_orig = true;
3840
4708ea14 3841 ret = validate_unret(file, alt->insn);
a09a6e23 3842 if (ret) {
ced23d2e 3843 BT_INSN(insn, "(alt)");
a09a6e23
PZ		 3844 return ret;
3845 }
3846 }
3847
3848 if (skip_orig)
3849 return 0;
3850 }
3851
3852 switch (insn->type) {
3853
3854 case INSN_CALL_DYNAMIC:
3855 case INSN_JUMP_DYNAMIC:
3856 case INSN_JUMP_DYNAMIC_CONDITIONAL:
246b2c85 3857 WARN_INSN(insn, "early indirect call");
a09a6e23
PZ		 3858 return 1;
3859
3860 case INSN_JUMP_UNCONDITIONAL:
3861 case INSN_JUMP_CONDITIONAL:
3862 if (!is_sibling_call(insn)) {
3863 if (!insn->jump_dest) {
246b2c85 3864 WARN_INSN(insn, "unresolved jump target after linking?!?");
a09a6e23
PZ		 3865 return -1;
3866 }
4708ea14 3867 ret = validate_unret(file, insn->jump_dest);
a09a6e23 3868 if (ret) {
ced23d2e
JP		 3869 BT_INSN(insn, "(branch%s)",
3870 insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
a09a6e23
PZ		 3871 return ret;
3872 }
3873
3874 if (insn->type == INSN_JUMP_UNCONDITIONAL)
3875 return 0;
3876
3877 break;
3878 }
3879
3880 /* fallthrough */
3881 case INSN_CALL:
c6f5dc28
PZ		 3882 dest = find_insn(file, insn_call_dest(insn)->sec,
3883 insn_call_dest(insn)->offset);
a09a6e23
PZ		 3884 if (!dest) {
3885 WARN("Unresolved function after linking!?: %s",
c6f5dc28 3886 insn_call_dest(insn)->name);
a09a6e23
PZ		 3887 return -1;
3888 }
3889
4708ea14 3890 ret = validate_unret(file, dest);
a09a6e23 3891 if (ret) {
ced23d2e 3892 BT_INSN(insn, "(call)");
a09a6e23
PZ		 3893 return ret;
3894 }
3895 /*
3896 * If a call returns without error, it must have seen UNTRAIN_RET.
3897 * Therefore any non-error return is a success.
3898 */
3899 return 0;
3900
3901 case INSN_RETURN:
246b2c85 3902 WARN_INSN(insn, "RET before UNTRAIN");
a09a6e23
PZ		 3903 return 1;
3904
3905 case INSN_NOP:
3906 if (insn->retpoline_safe)
3907 return 0;
3908 break;
3909
3910 default:
3911 break;
3912 }
3913
3914 if (!next) {
246b2c85 3915 WARN_INSN(insn, "teh end!");
a09a6e23
PZ		 3916 return -1;
3917 }
3918 insn = next;
3919 }
3920
d49d1666 3921 return 0;
a09a6e23
PZ		 3922}
3923
3924/*
4708ea14
JP		 3925 * Validate that all branches starting at VALIDATE_UNRET_BEGIN encounter
3926 * VALIDATE_UNRET_END before RET.
a09a6e23 3927 */
4708ea14 3928static int validate_unrets(struct objtool_file *file)
a09a6e23
PZ		 3929{
3930 struct instruction *insn;
3931 int ret, warnings = 0;
3932
3933 for_each_insn(file, insn) {
4708ea14 3934 if (!insn->unret)
a09a6e23
PZ		 3935 continue;
3936
4708ea14 3937 ret = validate_unret(file, insn);
a09a6e23 3938 if (ret < 0) {
246b2c85 3939 WARN_INSN(insn, "Failed UNRET validation");
a09a6e23
PZ		 3940 return ret;
3941 }
3942 warnings += ret;
3943 }
3944
3945 return warnings;
3946}
3947
b5bc2231
PZ		 3948static int validate_retpoline(struct objtool_file *file)
3949{
3950 struct instruction *insn;
3951 int warnings = 0;
3952
3953 for_each_insn(file, insn) {
3954 if (insn->type != INSN_JUMP_DYNAMIC &&
9bb2ec60
PZ		 3955 insn->type != INSN_CALL_DYNAMIC &&
3956 insn->type != INSN_RETURN)
b5bc2231
PZ		 3957 continue;
3958
3959 if (insn->retpoline_safe)
3960 continue;
3961
6644ee84 3962 if (insn->sec->init)
ca41b97e
PZ		 3963 continue;
3964
9bb2ec60 3965 if (insn->type == INSN_RETURN) {
f43b9876 3966 if (opts.rethunk) {
246b2c85 3967 WARN_INSN(insn, "'naked' return found in RETHUNK build");
f43b9876
PZ		 3968 } else
3969 continue;
9bb2ec60 3970 } else {
246b2c85 3971 WARN_INSN(insn, "indirect %s found in RETPOLINE build",
9bb2ec60
PZ		 3972 insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
3973 }
b5bc2231
PZ		 3974
3975 warnings++;
3976 }
3977
3978 return warnings;
3979}
3980
dcc914f4
JP		 3981static bool is_kasan_insn(struct instruction *insn)
3982{
3983 return (insn->type == INSN_CALL &&
c6f5dc28 3984 !strcmp(insn_call_dest(insn)->name, "__asan_handle_no_return"));
dcc914f4
JP		 3985}
3986
3987static bool is_ubsan_insn(struct instruction *insn)
3988{
3989 return (insn->type == INSN_CALL &&
c6f5dc28 3990 !strcmp(insn_call_dest(insn)->name,
dcc914f4
JP		 3991 "__ubsan_handle_builtin_unreachable"));
3992}
3993
14db1f0a 3994static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
dcc914f4
JP		 3995{
3996 int i;
14db1f0a 3997 struct instruction *prev_insn;
dcc914f4 3998
1ffbe4e9 3999 if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
baa41469
JP		 4000 return true;
4001
4002 /*
82a8954a 4003 * Ignore alternative replacement instructions. This can happen
0e2bb2bc 4004 * when a whitelisted function uses one of the ALTERNATIVE macros.
baa41469 4005 */
82a8954a 4006 if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
0e2bb2bc 4007 !strcmp(insn->sec->name, ".altinstr_aux"))
dcc914f4
JP		 4008 return true;
4009
4adb2368 4010 /*
753da417 4011 * Whole archive runs might encounter dead code from weak symbols.
4adb2368
PZ		 4012 * This is where the linker will have dropped the weak symbol in
4013 * favour of a regular symbol, but leaves the code in place.
4014 *
4015 * In this case we'll find a piece of code (whole function) that is not
4016 * covered by a !section symbol. Ignore them.
4017 */
dbcdbdfd 4018 if (opts.link && !insn_func(insn)) {
4adb2368
PZ		 4019 int size = find_symbol_hole_containing(insn->sec, insn->offset);
4020 unsigned long end = insn->offset + size;
4021
4022 if (!size) /* not a hole */
4023 return false;
4024
4025 if (size < 0) /* hole until the end */
4026 return true;
4027
4028 sec_for_each_insn_continue(file, insn) {
4029 /*
4030 * If we reach a visited instruction at or before the
4031 * end of the hole, ignore the unreachable.
4032 */
4033 if (insn->visited)
4034 return true;
4035
4036 if (insn->offset >= end)
4037 break;
4038
4039 /*
4040 * If this hole jumps to a .cold function, mark it ignore too.
4041 */
dbcdbdfd
PZ		 4042 if (insn->jump_dest && insn_func(insn->jump_dest) &&
4043 strstr(insn_func(insn->jump_dest)->name, ".cold")) {
4adb2368 4044 struct instruction *dest = insn->jump_dest;
dbcdbdfd 4045 func_for_each_insn(file, insn_func(dest), dest)
4adb2368
PZ		 4046 dest->ignore = true;
4047 }
4048 }
4049
4050 return false;
4051 }
4052
dbcdbdfd 4053 if (!insn_func(insn))
bd841d61
JP		 4054 return false;
4055
dbcdbdfd 4056 if (insn_func(insn)->static_call_tramp)
2105a927
PZ		 4057 return true;
4058
bd841d61
JP		 4059 /*
4060 * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
4061 * __builtin_unreachable(). The BUG() macro has an unreachable() after
4062 * the UD2, which causes GCC's undefined trap logic to emit another UD2
4063 * (or occasionally a JMP to UD2).
14db1f0a
IH		 4064 *
4065 * It may also insert a UD2 after calling a __noreturn function.
bd841d61 4066 */
1c34496e 4067 prev_insn = prev_insn_same_sec(file, insn);
6126ed5d 4068 if (prev_insn->dead_end &&
bd841d61
JP		 4069 (insn->type == INSN_BUG ||
4070 (insn->type == INSN_JUMP_UNCONDITIONAL &&
4071 insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
4072 return true;
4073
dcc914f4
JP		 4074 /*
4075 * Check if this (or a subsequent) instruction is related to
4076 * CONFIG_UBSAN or CONFIG_KASAN.
4077 *
4078 * End the search at 5 instructions to avoid going into the weeds.
4079 */
4080 for (i = 0; i < 5; i++) {
4081
4082 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
4083 return true;
4084
fe24e271
JP		 4085 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
4086 if (insn->jump_dest &&
dbcdbdfd 4087 insn_func(insn->jump_dest) == insn_func(insn)) {
fe24e271
JP		 4088 insn = insn->jump_dest;
4089 continue;
4090 }
4091
4092 break;
dcc914f4
JP		 4093 }
4094
dbcdbdfd 4095 if (insn->offset + insn->len >= insn_func(insn)->offset + insn_func(insn)->len)
dcc914f4 4096 break;
fe24e271 4097
1c34496e 4098 insn = next_insn_same_sec(file, insn);
dcc914f4
JP		 4099 }
4100
4101 return false;
4102}
4103
bd456a1b 4104static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
9f2899fe 4105{
bd456a1b 4106 struct instruction *insn, *prev;
5743654f 4107 struct cfi_state *cfi;
9f2899fe 4108
bd456a1b
JP		 4109 insn = find_insn(file, func->sec, func->offset);
4110 if (!insn)
4111 return -1;
9f2899fe 4112
bd456a1b
JP		 4113 for (prev = prev_insn_same_sec(file, insn);
4114 prev;
4115 prev = prev_insn_same_sec(file, prev)) {
4116 u64 offset;
9f2899fe
PZ		 4117
4118 if (prev->type != INSN_NOP)
bd456a1b 4119 return -1;
9f2899fe
PZ		 4120
4121 offset = func->offset - prev->offset;
bd456a1b
JP		 4122
4123 if (offset > opts.prefix)
4124 return -1;
4125
4126 if (offset < opts.prefix)
4127 continue;
4128
4129 elf_create_prefix_symbol(file->elf, func, opts.prefix);
4130 break;
9f2899fe
PZ		 4131 }
4132
bd456a1b
JP		 4133 if (!prev)
4134 return -1;
4135
5743654f
JP		 4136 if (!insn->cfi) {
4137 /*
4138 * This can happen if stack validation isn't enabled or the
4139 * function is annotated with STACK_FRAME_NON_STANDARD.
4140 */
4141 return 0;
4142 }
4143
4144 /* Propagate insn->cfi to the prefix code */
4145 cfi = cfi_hash_find_or_add(insn->cfi);
4146 for (; prev != insn; prev = next_insn_same_sec(file, prev))
4147 prev->cfi = cfi;
4148
9f2899fe
PZ		 4149 return 0;
4150}
4151
bd456a1b
JP		 4152static int add_prefix_symbols(struct objtool_file *file)
4153{
4154 struct section *sec;
4155 struct symbol *func;
bd456a1b
JP		 4156
4157 for_each_sec(file, sec) {
4158 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
4159 continue;
4160
4161 sec_for_each_sym(sec, func) {
4162 if (func->type != STT_FUNC)
4163 continue;
4164
4165 add_prefix_symbol(file, func);
4166 }
4167 }
4168
d49d1666 4169 return 0;
bd456a1b
JP		 4170}
4171
4b5e2e7f
PZ		 4172static int validate_symbol(struct objtool_file *file, struct section *sec,
4173 struct symbol *sym, struct insn_state *state)
dcc914f4 4174{
dcc914f4 4175 struct instruction *insn;
4b5e2e7f
PZ		 4176 int ret;
4177
4178 if (!sym->len) {
4179 WARN("%s() is missing an ELF size annotation", sym->name);
4180 return 1;
4181 }
4182
4183 if (sym->pfunc != sym || sym->alias != sym)
4184 return 0;
4185
4186 insn = find_insn(file, sec, sym->offset);
4187 if (!insn || insn->ignore || insn->visited)
4188 return 0;
4189
4190 state->uaccess = sym->uaccess_safe;
4191
dbcdbdfd 4192 ret = validate_branch(file, insn_func(insn), insn, *state);
ced23d2e
JP		 4193 if (ret)
4194 BT_INSN(insn, "<=== (sym)");
4b5e2e7f
PZ		 4195 return ret;
4196}
4197
4198static int validate_section(struct objtool_file *file, struct section *sec)
4199{
baa41469 4200 struct insn_state state;
4b5e2e7f
PZ		 4201 struct symbol *func;
4202 int warnings = 0;
dcc914f4 4203
9290e772 4204 sec_for_each_sym(sec, func) {
350994bf
PZ		 4205 if (func->type != STT_FUNC)
4206 continue;
e10cd8fe 4207
753da417 4208 init_insn_state(file, &state, sec);
b735bd3e 4209 set_func_state(&state.cfi);
0699e551 4210
4b5e2e7f 4211 warnings += validate_symbol(file, sec, func, &state);
dcc914f4
JP		 4212 }
4213
dcc914f4
JP		 4214 return warnings;
4215}
4216
753da417 4217static int validate_noinstr_sections(struct objtool_file *file)
c4a33939
PZ		 4218{
4219 struct section *sec;
932f8e98 4220 int warnings = 0;
c4a33939
PZ		 4221
4222 sec = find_section_by_name(file->elf, ".noinstr.text");
0cc9ac8d
TG		 4223 if (sec) {
4224 warnings += validate_section(file, sec);
4225 warnings += validate_unwind_hints(file, sec);
4226 }
c4a33939 4227
0cc9ac8d
TG		 4228 sec = find_section_by_name(file->elf, ".entry.text");
4229 if (sec) {
4230 warnings += validate_section(file, sec);
4231 warnings += validate_unwind_hints(file, sec);
4232 }
932f8e98 4233
2b5a0e42
PZ		 4234 sec = find_section_by_name(file->elf, ".cpuidle.text");
4235 if (sec) {
4236 warnings += validate_section(file, sec);
4237 warnings += validate_unwind_hints(file, sec);
4238 }
4239
932f8e98 4240 return warnings;
c4a33939
PZ		 4241}
4242
350994bf
PZ		 4243static int validate_functions(struct objtool_file *file)
4244{
4245 struct section *sec;
4246 int warnings = 0;
4247
da837bd6
PZ		 4248 for_each_sec(file, sec) {
4249 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
4250 continue;
4251
350994bf 4252 warnings += validate_section(file, sec);
da837bd6 4253 }
350994bf
PZ		 4254
4255 return warnings;
4256}
4257
3c6f9f77 4258static void mark_endbr_used(struct instruction *insn)
08f87a93 4259{
3c6f9f77
JP		 4260 if (!list_empty(&insn->call_node))
4261 list_del_init(&insn->call_node);
4262}
4263
08ef8c40
PZ		 4264static bool noendbr_range(struct objtool_file *file, struct instruction *insn)
4265{
4266 struct symbol *sym = find_symbol_containing(insn->sec, insn->offset-1);
4267 struct instruction *first;
4268
4269 if (!sym)
4270 return false;
4271
4272 first = find_insn(file, sym->sec, sym->offset);
4273 if (!first)
4274 return false;
4275
4276 if (first->type != INSN_ENDBR && !first->noendbr)
4277 return false;
4278
4279 return insn->offset == sym->offset + sym->len;
4280}
4281
3c6f9f77
JP		 4282static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
4283{
4284 struct instruction *dest;
08f87a93 4285 struct reloc *reloc;
3c6f9f77
JP		 4286 unsigned long off;
4287 int warnings = 0;
08f87a93 4288
3c6f9f77
JP		 4289 /*
4290 * Looking for function pointer load relocations. Ignore
4291 * direct/indirect branches:
4292 */
4293 switch (insn->type) {
4294 case INSN_CALL:
4295 case INSN_CALL_DYNAMIC:
4296 case INSN_JUMP_CONDITIONAL:
4297 case INSN_JUMP_UNCONDITIONAL:
4298 case INSN_JUMP_DYNAMIC:
4299 case INSN_JUMP_DYNAMIC_CONDITIONAL:
4300 case INSN_RETURN:
4301 case INSN_NOP:
4302 return 0;
4303 default:
4304 break;
4305 }
08f87a93 4306
3c6f9f77
JP		 4307 for (reloc = insn_reloc(file, insn);
4308 reloc;
4309 reloc = find_reloc_by_dest_range(file->elf, insn->sec,
e4cbb9b8
JP		 4310 reloc_offset(reloc) + 1,
4311 (insn->offset + insn->len) - (reloc_offset(reloc) + 1))) {
08f87a93 4312
3c6f9f77
JP		 4313 /*
4314 * static_call_update() references the trampoline, which
4315 * doesn't have (or need) ENDBR. Skip warning in that case.
4316 */
4317 if (reloc->sym->static_call_tramp)
08f87a93
PZ		 4318 continue;
4319
3c6f9f77 4320 off = reloc->sym->offset;
fcee899d
JP		 4321 if (reloc_type(reloc) == R_X86_64_PC32 ||
4322 reloc_type(reloc) == R_X86_64_PLT32)
0696b6e3 4323 off += arch_dest_reloc_offset(reloc_addend(reloc));
3c6f9f77 4324 else
0696b6e3 4325 off += reloc_addend(reloc);
3c6f9f77
JP		 4326
4327 dest = find_insn(file, reloc->sym->sec, off);
4328 if (!dest)
08f87a93
PZ		 4329 continue;
4330
3c6f9f77
JP		 4331 if (dest->type == INSN_ENDBR) {
4332 mark_endbr_used(dest);
08f87a93 4333 continue;
3c6f9f77 4334 }
08f87a93 4335
72178d5d
JP		 4336 if (insn_func(dest) && insn_func(insn) &&
4337 insn_func(dest)->pfunc == insn_func(insn)->pfunc) {
3c6f9f77
JP		 4338 /*
4339 * Anything from->to self is either _THIS_IP_ or
4340 * IRET-to-self.
4341 *
4342 * There is no sane way to annotate _THIS_IP_ since the
4343 * compiler treats the relocation as a constant and is
4344 * happy to fold in offsets, skewing any annotation we
4345 * do, leading to vast amounts of false-positives.
4346 *
4347 * There's also compiler generated _THIS_IP_ through
4348 * KCOV and such which we have no hope of annotating.
4349 *
4350 * As such, blanket accept self-references without
4351 * issue.
4352 */
08f87a93 4353 continue;
3c6f9f77 4354 }
08f87a93 4355
08ef8c40
PZ		 4356 /*
4357 * Accept anything ANNOTATE_NOENDBR.
4358 */
3c6f9f77 4359 if (dest->noendbr)
08f87a93
PZ		 4360 continue;
4361
08ef8c40
PZ		 4362 /*
4363 * Accept if this is the instruction after a symbol
4364 * that is (no)endbr -- typical code-range usage.
4365 */
4366 if (noendbr_range(file, dest))
4367 continue;
4368
246b2c85 4369 WARN_INSN(insn, "relocation to !ENDBR: %s", offstr(dest->sec, dest->offset));
3c6f9f77
JP		 4370
4371 warnings++;
4372 }
4373
4374 return warnings;
4375}
4376
4377static int validate_ibt_data_reloc(struct objtool_file *file,
4378 struct reloc *reloc)
4379{
4380 struct instruction *dest;
4381
4382 dest = find_insn(file, reloc->sym->sec,
0696b6e3 4383 reloc->sym->offset + reloc_addend(reloc));
3c6f9f77
JP		 4384 if (!dest)
4385 return 0;
4386
4387 if (dest->type == INSN_ENDBR) {
4388 mark_endbr_used(dest);
4389 return 0;
4390 }
4391
4392 if (dest->noendbr)
4393 return 0;
4394
4395 WARN_FUNC("data relocation to !ENDBR: %s",
e4cbb9b8 4396 reloc->sec->base, reloc_offset(reloc),
3c6f9f77
JP		 4397 offstr(dest->sec, dest->offset));
4398
4399 return 1;
4400}
4401
4402/*
4403 * Validate IBT rules and remove used ENDBR instructions from the seal list.
4404 * Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
4405 * NOPs) later, in create_ibt_endbr_seal_sections().
4406 */
4407static int validate_ibt(struct objtool_file *file)
4408{
4409 struct section *sec;
4410 struct reloc *reloc;
4411 struct instruction *insn;
4412 int warnings = 0;
4413
4414 for_each_insn(file, insn)
4415 warnings += validate_ibt_insn(file, insn);
4416
4417 for_each_sec(file, sec) {
4418
4419 /* Already done by validate_ibt_insn() */
4420 if (sec->sh.sh_flags & SHF_EXECINSTR)
08f87a93
PZ		 4421 continue;
4422
a5bd6236 4423 if (!sec->rsec)
3c6f9f77 4424 continue;
08f87a93 4425
3c6f9f77
JP		 4426 /*
4427 * These sections can reference text addresses, but not with
4428 * the intent to indirect branch to them.
4429 */
e27e5bea
JP		 4430 if ((!strncmp(sec->name, ".discard", 8) &&
4431 strcmp(sec->name, ".discard.ibt_endbr_noseal")) ||
3c6f9f77
JP		 4432 !strncmp(sec->name, ".debug", 6) ||
4433 !strcmp(sec->name, ".altinstructions") ||
4434 !strcmp(sec->name, ".ibt_endbr_seal") ||
4435 !strcmp(sec->name, ".orc_unwind_ip") ||
4436 !strcmp(sec->name, ".parainstructions") ||
4437 !strcmp(sec->name, ".retpoline_sites") ||
4438 !strcmp(sec->name, ".smp_locks") ||
4439 !strcmp(sec->name, ".static_call_sites") ||
4440 !strcmp(sec->name, "_error_injection_whitelist") ||
4441 !strcmp(sec->name, "_kprobe_blacklist") ||
4442 !strcmp(sec->name, "__bug_table") ||
4443 !strcmp(sec->name, "__ex_table") ||
4444 !strcmp(sec->name, "__jump_table") ||
3c68a92d 4445 !strcmp(sec->name, "__mcount_loc") ||
0326074f 4446 !strcmp(sec->name, ".kcfi_traps") ||
9440155c 4447 strstr(sec->name, "__patchable_function_entries"))
3c6f9f77 4448 continue;
08f87a93 4449
caa4a6b7 4450 for_each_reloc(sec->rsec, reloc)
3c6f9f77 4451 warnings += validate_ibt_data_reloc(file, reloc);
08f87a93
PZ		 4452 }
4453
3c6f9f77 4454 return warnings;
08f87a93
PZ		 4455}
4456
c2bdd61c
JP		 4457static int validate_sls(struct objtool_file *file)
4458{
4459 struct instruction *insn, *next_insn;
4460 int warnings = 0;
4461
4462 for_each_insn(file, insn) {
4463 next_insn = next_insn_same_sec(file, insn);
4464
4465 if (insn->retpoline_safe)
4466 continue;
4467
4468 switch (insn->type) {
4469 case INSN_RETURN:
4470 if (!next_insn || next_insn->type != INSN_TRAP) {
246b2c85 4471 WARN_INSN(insn, "missing int3 after ret");
c2bdd61c
JP		 4472 warnings++;
4473 }
4474
4475 break;
4476 case INSN_JUMP_DYNAMIC:
4477 if (!next_insn || next_insn->type != INSN_TRAP) {
246b2c85 4478 WARN_INSN(insn, "missing int3 after indirect jump");
c2bdd61c
JP		 4479 warnings++;
4480 }
4481 break;
4482 default:
4483 break;
4484 }
4485 }
4486
4487 return warnings;
4488}
4489
55eeab2a
JP		 4490static bool ignore_noreturn_call(struct instruction *insn)
4491{
4492 struct symbol *call_dest = insn_call_dest(insn);
4493
4494 /*
4495 * FIXME: hack, we need a real noreturn solution
4496 *
4497 * Problem is, exc_double_fault() may or may not return, depending on
4498 * whether CONFIG_X86_ESPFIX64 is set. But objtool has no visibility
4499 * to the kernel config.
4500 *
4501 * Other potential ways to fix it:
4502 *
4503 * - have compiler communicate __noreturn functions somehow
4504 * - remove CONFIG_X86_ESPFIX64
4505 * - read the .config file
4506 * - add a cmdline option
4507 * - create a generic objtool annotation format (vs a bunch of custom
4508 * formats) and annotate it
4509 */
4510 if (!strcmp(call_dest->name, "exc_double_fault")) {
4511 /* prevent further unreachable warnings for the caller */
4512 insn->sym->warned = 1;
4513 return true;
4514 }
4515
4516 return false;
4517}
4518
baa41469 4519static int validate_reachable_instructions(struct objtool_file *file)
dcc914f4 4520{
fedb724c
JP		 4521 struct instruction *insn, *prev_insn;
4522 struct symbol *call_dest;
5e3992fe 4523 int warnings = 0;
baa41469
JP		 4524
4525 if (file->ignore_unreachables)
4526 return 0;
dcc914f4
JP		 4527
4528 for_each_insn(file, insn) {
14db1f0a 4529 if (insn->visited || ignore_unreachable_insn(file, insn))
baa41469
JP		 4530 continue;
4531
fedb724c
JP		 4532 prev_insn = prev_insn_same_sec(file, insn);
4533 if (prev_insn && prev_insn->dead_end) {
4534 call_dest = insn_call_dest(prev_insn);
55eeab2a 4535 if (call_dest && !ignore_noreturn_call(prev_insn)) {
fedb724c
JP		 4536 WARN_INSN(insn, "%s() is missing a __noreturn annotation",
4537 call_dest->name);
4538 warnings++;
4539 continue;
4540 }
4541 }
4542
246b2c85 4543 WARN_INSN(insn, "unreachable instruction");
5e3992fe 4544 warnings++;
dcc914f4
JP		 4545 }
4546
5e3992fe 4547 return warnings;
dcc914f4
JP		 4548}
4549
ca653464
JP		 4550/* 'funcs' is a space-separated list of function names */
4551static int disas_funcs(const char *funcs)
4552{
4553 const char *objdump_str, *cross_compile;
4554 int size, ret;
4555 char *cmd;
4556
4557 cross_compile = getenv("CROSS_COMPILE");
4558
4559 objdump_str = "%sobjdump -wdr %s | gawk -M -v _funcs='%s' '"
4560 "BEGIN { split(_funcs, funcs); }"
4561 "/^$/ { func_match = 0; }"
4562 "/<.*>:/ { "
4563 "f = gensub(/.*<(.*)>:/, \"\\\\1\", 1);"
4564 "for (i in funcs) {"
4565 "if (funcs[i] == f) {"
4566 "func_match = 1;"
4567 "base = strtonum(\"0x\" $1);"
4568 "break;"
4569 "}"
4570 "}"
4571 "}"
4572 "{"
4573 "if (func_match) {"
4574 "addr = strtonum(\"0x\" $1);"
4575 "printf(\"%%04x \", addr - base);"
4576 "print;"
4577 "}"
4578 "}' 1>&2";
4579
4580 /* fake snprintf() to calculate the size */
4581 size = snprintf(NULL, 0, objdump_str, cross_compile, objname, funcs) + 1;
4582 if (size <= 0) {
4583 WARN("objdump string size calculation failed");
4584 return -1;
4585 }
4586
4587 cmd = malloc(size);
4588
4589 /* real snprintf() */
4590 snprintf(cmd, size, objdump_str, cross_compile, objname, funcs);
4591 ret = system(cmd);
4592 if (ret) {
4593 WARN("disassembly failed: %d", ret);
4594 return -1;
4595 }
4596
4597 return 0;
4598}
4599
4600static int disas_warned_funcs(struct objtool_file *file)
4601{
4602 struct symbol *sym;
4603 char *funcs = NULL, *tmp;
4604
4605 for_each_sym(file, sym) {
4606 if (sym->warned) {
4607 if (!funcs) {
4608 funcs = malloc(strlen(sym->name) + 1);
4609 strcpy(funcs, sym->name);
4610 } else {
4611 tmp = malloc(strlen(funcs) + strlen(sym->name) + 2);
4612 sprintf(tmp, "%s %s", funcs, sym->name);
4613 free(funcs);
4614 funcs = tmp;
4615 }
4616 }
4617 }
4618
4619 if (funcs)
4620 disas_funcs(funcs);
4621
4622 return 0;
4623}
4624
d93b5935
JP		 4625struct insn_chunk {
4626 void *addr;
4627 struct insn_chunk *next;
4628};
4629
4630/*
4631 * Reduce peak RSS usage by freeing insns memory before writing the ELF file,
4632 * which can trigger more allocations for .debug_* sections whose data hasn't
4633 * been read yet.
4634 */
4635static void free_insns(struct objtool_file *file)
4636{
4637 struct instruction *insn;
4638 struct insn_chunk *chunks = NULL, *chunk;
4639
4640 for_each_insn(file, insn) {
4641 if (!insn->idx) {
4642 chunk = malloc(sizeof(*chunk));
4643 chunk->addr = insn;
4644 chunk->next = chunks;
4645 chunks = chunk;
4646 }
4647 }
4648
4649 for (chunk = chunks; chunk; chunk = chunk->next)
4650 free(chunk->addr);
4651}
4652
d44becb9 4653int check(struct objtool_file *file)
dcc914f4 4654{
dcc914f4
JP		 4655 int ret, warnings = 0;
4656
baa41469 4657 arch_initial_func_cfi_state(&initial_func_cfi);
8b946cc3
PZ		 4658 init_cfi_state(&init_cfi);
4659 init_cfi_state(&func_cfi);
4660 set_func_state(&func_cfi);
1e4b6191
JP		 4661 init_cfi_state(&force_undefined_cfi);
4662 force_undefined_cfi.force_undefined = true;
8b946cc3
PZ		 4663
4664 if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
4665 goto out;
4666
4667 cfi_hash_add(&init_cfi);
4668 cfi_hash_add(&func_cfi);
baa41469 4669
6545eb03 4670 ret = decode_sections(file);
dcc914f4
JP		 4671 if (ret < 0)
4672 goto out;
8b946cc3 4673
dcc914f4
JP		 4674 warnings += ret;
4675
1c34496e 4676 if (!nr_insns)
dcc914f4 4677 goto out;
dcc914f4 4678
2daf7fab 4679 if (opts.retpoline) {
6545eb03 4680 ret = validate_retpoline(file);
b5bc2231
PZ		 4681 if (ret < 0)
4682 return ret;
4683 warnings += ret;
4684 }
4685
c2bdd61c 4686 if (opts.stackval || opts.orc || opts.uaccess) {
7dce6204
JP		 4687 ret = validate_functions(file);
4688 if (ret < 0)
4689 goto out;
4690 warnings += ret;
39358a03 4691
7dce6204 4692 ret = validate_unwind_hints(file, NULL);
08f87a93
PZ		 4693 if (ret < 0)
4694 goto out;
4695 warnings += ret;
7dce6204
JP		 4696
4697 if (!warnings) {
4698 ret = validate_reachable_instructions(file);
4699 if (ret < 0)
4700 goto out;
4701 warnings += ret;
4702 }
753da417
JP		 4703
4704 } else if (opts.noinstr) {
4705 ret = validate_noinstr_sections(file);
4706 if (ret < 0)
4707 goto out;
4708 warnings += ret;
08f87a93
PZ		 4709 }
4710
a09a6e23
PZ		 4711 if (opts.unret) {
4712 /*
4713 * Must be after validate_branch() and friends, it plays
4714 * further games with insn->visited.
4715 */
4708ea14 4716 ret = validate_unrets(file);
a09a6e23
PZ		 4717 if (ret < 0)
4718 return ret;
4719 warnings += ret;
4720 }
4721
7dce6204
JP		 4722 if (opts.ibt) {
4723 ret = validate_ibt(file);
baa41469
JP		 4724 if (ret < 0)
4725 goto out;
c2bdd61c
JP		 4726 warnings += ret;
4727 }
4728
4729 if (opts.sls) {
4730 ret = validate_sls(file);
4731 if (ret < 0)
4732 goto out;
baa41469
JP		 4733 warnings += ret;
4734 }
4735
26e17689
JP		 4736 if (opts.static_call) {
4737 ret = create_static_call_sections(file);
4738 if (ret < 0)
4739 goto out;
4740 warnings += ret;
4741 }
1e7e4788 4742
2daf7fab 4743 if (opts.retpoline) {
134ab5bd
PZ		 4744 ret = create_retpoline_sites_sections(file);
4745 if (ret < 0)
4746 goto out;
4747 warnings += ret;
4748 }
4749
9a479f76
PZ		 4750 if (opts.cfi) {
4751 ret = create_cfi_sections(file);
4752 if (ret < 0)
4753 goto out;
4754 warnings += ret;
4755 }
4756
f43b9876 4757 if (opts.rethunk) {
d9e9d230
PZ		 4758 ret = create_return_sites_sections(file);
4759 if (ret < 0)
4760 goto out;
4761 warnings += ret;
00abd384 4762
0c0a6d89
PZ		 4763 if (opts.hack_skylake) {
4764 ret = create_direct_call_sections(file);
4765 if (ret < 0)
4766 goto out;
4767 warnings += ret;
4768 }
134ab5bd
PZ		 4769 }
4770
2daf7fab 4771 if (opts.mcount) {
99d00215
PZ		 4772 ret = create_mcount_loc_sections(file);
4773 if (ret < 0)
4774 goto out;
4775 warnings += ret;
4776 }
4777
bd456a1b
JP		 4778 if (opts.prefix) {
4779 ret = add_prefix_symbols(file);
4780 if (ret < 0)
4781 return ret;
4782 warnings += ret;
4783 }
4784
2daf7fab 4785 if (opts.ibt) {
89bc853e
PZ		 4786 ret = create_ibt_endbr_seal_sections(file);
4787 if (ret < 0)
4788 goto out;
4789 warnings += ret;
4790 }
4791
1c34496e 4792 if (opts.orc && nr_insns) {
b51277eb
JP		 4793 ret = orc_create(file);
4794 if (ret < 0)
4795 goto out;
4796 warnings += ret;
4797 }
4798
d93b5935
JP		 4799 free_insns(file);
4800
ca653464
JP		 4801 if (opts.verbose)
4802 disas_warned_funcs(file);
b51277eb 4803
2daf7fab 4804 if (opts.stats) {
8b946cc3
PZ		 4805 printf("nr_insns_visited: %ld\n", nr_insns_visited);
4806 printf("nr_cfi: %ld\n", nr_cfi);
4807 printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
4808 printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
4809 }
4810
dcc914f4 4811out:
655cf865
JP		 4812 /*
4813 * For now, don't fail the kernel build on fatal warnings. These
4814 * errors are still fairly common due to the growing matrix of
4815 * supported toolchains and their recent pace of change.
4816 */
dcc914f4
JP		 4817 return 0;
4818}
Linux 6.x block layer and io_uring tree(s)