2 * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see <http://www.gnu.org/licenses/>.
28 #include <linux/hashtable.h>
29 #include <linux/kernel.h>
31 #define FAKE_JUMP_OFFSET -1
34 struct list_head list;
35 struct instruction *insn;
39 struct cfi_state initial_func_cfi;
41 struct instruction *find_insn(struct objtool_file *file,
42 struct section *sec, unsigned long offset)
44 struct instruction *insn;
46 hash_for_each_possible(file->insn_hash, insn, hash, offset)
47 if (insn->sec == sec && insn->offset == offset)
53 static struct instruction *next_insn_same_sec(struct objtool_file *file,
54 struct instruction *insn)
56 struct instruction *next = list_next_entry(insn, list);
58 if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
64 static struct instruction *next_insn_same_func(struct objtool_file *file,
65 struct instruction *insn)
67 struct instruction *next = list_next_entry(insn, list);
68 struct symbol *func = insn->func;
73 if (&next->list != &file->insn_list && next->func == func)
76 /* Check if we're already in the subfunction: */
77 if (func == func->cfunc)
80 /* Move to the subfunction: */
81 return find_insn(file, func->cfunc->sec, func->cfunc->offset);
84 #define func_for_each_insn_all(file, func, insn) \
85 for (insn = find_insn(file, func->sec, func->offset); \
87 insn = next_insn_same_func(file, insn))
89 #define func_for_each_insn(file, func, insn) \
90 for (insn = find_insn(file, func->sec, func->offset); \
91 insn && &insn->list != &file->insn_list && \
92 insn->sec == func->sec && \
93 insn->offset < func->offset + func->len; \
94 insn = list_next_entry(insn, list))
96 #define func_for_each_insn_continue_reverse(file, func, insn) \
97 for (insn = list_prev_entry(insn, list); \
98 &insn->list != &file->insn_list && \
99 insn->sec == func->sec && insn->offset >= func->offset; \
100 insn = list_prev_entry(insn, list))
102 #define sec_for_each_insn_from(file, insn) \
103 for (; insn; insn = next_insn_same_sec(file, insn))
105 #define sec_for_each_insn_continue(file, insn) \
106 for (insn = next_insn_same_sec(file, insn); insn; \
107 insn = next_insn_same_sec(file, insn))
110 * Check if the function has been manually whitelisted with the
111 * STACK_FRAME_NON_STANDARD macro, or if it should be automatically whitelisted
112 * due to its use of a context switching instruction.
114 static bool ignore_func(struct objtool_file *file, struct symbol *func)
118 /* check for STACK_FRAME_NON_STANDARD */
119 if (file->whitelist && file->whitelist->rela)
120 list_for_each_entry(rela, &file->whitelist->rela->rela_list, list) {
121 if (rela->sym->type == STT_SECTION &&
122 rela->sym->sec == func->sec &&
123 rela->addend == func->offset)
125 if (rela->sym->type == STT_FUNC && rela->sym == func)
133 * This checks to see if the given function is a "noreturn" function.
135 * For global functions which are outside the scope of this object file, we
136 * have to keep a manual list of them.
138 * For local functions, we have to detect them manually by simply looking for
139 * the lack of a return instruction.
146 static int __dead_end_function(struct objtool_file *file, struct symbol *func,
150 struct instruction *insn;
154 * Unfortunately these have to be hard coded because the noreturn
155 * attribute isn't provided in ELF data.
157 static const char * const global_noreturns[] = {
162 "__module_put_and_exit",
164 "kvm_spurious_fault",
168 "machine_real_restart",
169 "rewind_stack_do_exit",
172 if (func->bind == STB_WEAK)
175 if (func->bind == STB_GLOBAL)
176 for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
177 if (!strcmp(func->name, global_noreturns[i]))
183 insn = find_insn(file, func->sec, func->offset);
187 func_for_each_insn_all(file, func, insn) {
190 if (insn->type == INSN_RETURN)
198 * A function can have a sibling call instead of a return. In that
199 * case, the function's dead-end status depends on whether the target
200 * of the sibling call returns.
202 func_for_each_insn_all(file, func, insn) {
203 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
204 struct instruction *dest = insn->jump_dest;
207 /* sibling call to another file */
210 if (dest->func && dest->func->pfunc != insn->func->pfunc) {
212 /* local sibling call */
213 if (recursion == 5) {
215 * Infinite recursion: two functions
216 * have sibling calls to each other.
217 * This is a very rare case. It means
218 * they aren't dead ends.
223 return __dead_end_function(file, dest->func,
228 if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts))
236 static int dead_end_function(struct objtool_file *file, struct symbol *func)
238 return __dead_end_function(file, func, 0);
241 static void clear_insn_state(struct insn_state *state)
245 memset(state, 0, sizeof(*state));
246 state->cfa.base = CFI_UNDEFINED;
247 for (i = 0; i < CFI_NUM_REGS; i++) {
248 state->regs[i].base = CFI_UNDEFINED;
249 state->vals[i].base = CFI_UNDEFINED;
251 state->drap_reg = CFI_UNDEFINED;
252 state->drap_offset = -1;
256 * Call the arch-specific instruction decoder for all the instructions and add
257 * them to the global instruction list.
259 static int decode_instructions(struct objtool_file *file)
263 unsigned long offset;
264 struct instruction *insn;
267 for_each_sec(file, sec) {
269 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
272 if (strcmp(sec->name, ".altinstr_replacement") &&
273 strcmp(sec->name, ".altinstr_aux") &&
274 strncmp(sec->name, ".discard.", 9))
277 for (offset = 0; offset < sec->len; offset += insn->len) {
278 insn = malloc(sizeof(*insn));
280 WARN("malloc failed");
283 memset(insn, 0, sizeof(*insn));
284 INIT_LIST_HEAD(&insn->alts);
285 clear_insn_state(&insn->state);
288 insn->offset = offset;
290 ret = arch_decode_instruction(file->elf, sec, offset,
292 &insn->len, &insn->type,
298 if (!insn->type || insn->type > INSN_LAST) {
299 WARN_FUNC("invalid instruction type %d",
300 insn->sec, insn->offset, insn->type);
305 hash_add(file->insn_hash, &insn->hash, insn->offset);
306 list_add_tail(&insn->list, &file->insn_list);
309 list_for_each_entry(func, &sec->symbol_list, list) {
310 if (func->type != STT_FUNC)
313 if (!find_insn(file, sec, func->offset)) {
314 WARN("%s(): can't find starting instruction",
319 func_for_each_insn(file, func, insn)
333 * Mark "ud2" instructions and manually annotated dead ends.
335 static int add_dead_ends(struct objtool_file *file)
339 struct instruction *insn;
343 * By default, "ud2" is a dead end unless otherwise annotated, because
344 * GCC 7 inserts it for certain divide-by-zero cases.
346 for_each_insn(file, insn)
347 if (insn->type == INSN_BUG)
348 insn->dead_end = true;
351 * Check for manually annotated dead ends.
353 sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
357 list_for_each_entry(rela, &sec->rela_list, list) {
358 if (rela->sym->type != STT_SECTION) {
359 WARN("unexpected relocation symbol type in %s", sec->name);
362 insn = find_insn(file, rela->sym->sec, rela->addend);
364 insn = list_prev_entry(insn, list);
365 else if (rela->addend == rela->sym->sec->len) {
367 list_for_each_entry_reverse(insn, &file->insn_list, list) {
368 if (insn->sec == rela->sym->sec) {
375 WARN("can't find unreachable insn at %s+0x%x",
376 rela->sym->sec->name, rela->addend);
380 WARN("can't find unreachable insn at %s+0x%x",
381 rela->sym->sec->name, rela->addend);
385 insn->dead_end = true;
390 * These manually annotated reachable checks are needed for GCC 4.4,
391 * where the Linux unreachable() macro isn't supported. In that case
392 * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
395 sec = find_section_by_name(file->elf, ".rela.discard.reachable");
399 list_for_each_entry(rela, &sec->rela_list, list) {
400 if (rela->sym->type != STT_SECTION) {
401 WARN("unexpected relocation symbol type in %s", sec->name);
404 insn = find_insn(file, rela->sym->sec, rela->addend);
406 insn = list_prev_entry(insn, list);
407 else if (rela->addend == rela->sym->sec->len) {
409 list_for_each_entry_reverse(insn, &file->insn_list, list) {
410 if (insn->sec == rela->sym->sec) {
417 WARN("can't find reachable insn at %s+0x%x",
418 rela->sym->sec->name, rela->addend);
422 WARN("can't find reachable insn at %s+0x%x",
423 rela->sym->sec->name, rela->addend);
427 insn->dead_end = false;
434 * Warnings shouldn't be reported for ignored functions.
436 static void add_ignores(struct objtool_file *file)
438 struct instruction *insn;
442 for_each_sec(file, sec) {
443 list_for_each_entry(func, &sec->symbol_list, list) {
444 if (func->type != STT_FUNC)
447 if (!ignore_func(file, func))
450 func_for_each_insn_all(file, func, insn)
457 * FIXME: For now, just ignore any alternatives which add retpolines. This is
458 * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
459 * But it at least allows objtool to understand the control flow *around* the
462 static int add_nospec_ignores(struct objtool_file *file)
466 struct instruction *insn;
468 sec = find_section_by_name(file->elf, ".rela.discard.nospec");
472 list_for_each_entry(rela, &sec->rela_list, list) {
473 if (rela->sym->type != STT_SECTION) {
474 WARN("unexpected relocation symbol type in %s", sec->name);
478 insn = find_insn(file, rela->sym->sec, rela->addend);
480 WARN("bad .discard.nospec entry");
484 insn->ignore_alts = true;
491 * Find the destination instructions for all jumps.
493 static int add_jump_destinations(struct objtool_file *file)
495 struct instruction *insn;
497 struct section *dest_sec;
498 unsigned long dest_off;
500 for_each_insn(file, insn) {
501 if (insn->type != INSN_JUMP_CONDITIONAL &&
502 insn->type != INSN_JUMP_UNCONDITIONAL)
505 if (insn->offset == FAKE_JUMP_OFFSET)
508 rela = find_rela_by_dest_range(insn->sec, insn->offset,
511 dest_sec = insn->sec;
512 dest_off = insn->offset + insn->len + insn->immediate;
513 } else if (rela->sym->type == STT_SECTION) {
514 dest_sec = rela->sym->sec;
515 dest_off = rela->addend + 4;
516 } else if (rela->sym->sec->idx) {
517 dest_sec = rela->sym->sec;
518 dest_off = rela->sym->sym.st_value + rela->addend + 4;
519 } else if (strstr(rela->sym->name, "_indirect_thunk_")) {
521 * Retpoline jumps are really dynamic jumps in
522 * disguise, so convert them accordingly.
524 insn->type = INSN_JUMP_DYNAMIC;
525 insn->retpoline_safe = true;
533 insn->jump_dest = find_insn(file, dest_sec, dest_off);
534 if (!insn->jump_dest) {
537 * This is a special case where an alt instruction
538 * jumps past the end of the section. These are
539 * handled later in handle_group_alt().
541 if (!strcmp(insn->sec->name, ".altinstr_replacement"))
544 WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
545 insn->sec, insn->offset, dest_sec->name,
555 * Find the destination instructions for all calls.
557 static int add_call_destinations(struct objtool_file *file)
559 struct instruction *insn;
560 unsigned long dest_off;
563 for_each_insn(file, insn) {
564 if (insn->type != INSN_CALL)
567 rela = find_rela_by_dest_range(insn->sec, insn->offset,
570 dest_off = insn->offset + insn->len + insn->immediate;
571 insn->call_dest = find_symbol_by_offset(insn->sec,
574 if (!insn->call_dest && !insn->ignore) {
575 WARN_FUNC("unsupported intra-function call",
576 insn->sec, insn->offset);
578 WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE.");
582 } else if (rela->sym->type == STT_SECTION) {
583 insn->call_dest = find_symbol_by_offset(rela->sym->sec,
585 if (!insn->call_dest ||
586 insn->call_dest->type != STT_FUNC) {
587 WARN_FUNC("can't find call dest symbol at %s+0x%x",
588 insn->sec, insn->offset,
589 rela->sym->sec->name,
594 insn->call_dest = rela->sym;
601 * The .alternatives section requires some extra special care, over and above
602 * what other special sections require:
604 * 1. Because alternatives are patched in-place, we need to insert a fake jump
605 * instruction at the end so that validate_branch() skips all the original
606 * replaced instructions when validating the new instruction path.
608 * 2. An added wrinkle is that the new instruction length might be zero. In
609 * that case the old instructions are replaced with noops. We simulate that
610 * by creating a fake jump as the only new instruction.
612 * 3. In some cases, the alternative section includes an instruction which
613 * conditionally jumps to the _end_ of the entry. We have to modify these
614 * jumps' destinations to point back to .text rather than the end of the
615 * entry in .altinstr_replacement.
617 * 4. It has been requested that we don't validate the !POPCNT feature path
618 * which is a "very very small percentage of machines".
620 static int handle_group_alt(struct objtool_file *file,
621 struct special_alt *special_alt,
622 struct instruction *orig_insn,
623 struct instruction **new_insn)
625 struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL;
626 unsigned long dest_off;
628 last_orig_insn = NULL;
630 sec_for_each_insn_from(file, insn) {
631 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
634 if (special_alt->skip_orig)
635 insn->type = INSN_NOP;
637 insn->alt_group = true;
638 last_orig_insn = insn;
641 if (next_insn_same_sec(file, last_orig_insn)) {
642 fake_jump = malloc(sizeof(*fake_jump));
644 WARN("malloc failed");
647 memset(fake_jump, 0, sizeof(*fake_jump));
648 INIT_LIST_HEAD(&fake_jump->alts);
649 clear_insn_state(&fake_jump->state);
651 fake_jump->sec = special_alt->new_sec;
652 fake_jump->offset = FAKE_JUMP_OFFSET;
653 fake_jump->type = INSN_JUMP_UNCONDITIONAL;
654 fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
655 fake_jump->func = orig_insn->func;
658 if (!special_alt->new_len) {
660 WARN("%s: empty alternative at end of section",
661 special_alt->orig_sec->name);
665 *new_insn = fake_jump;
669 last_new_insn = NULL;
671 sec_for_each_insn_from(file, insn) {
672 if (insn->offset >= special_alt->new_off + special_alt->new_len)
675 last_new_insn = insn;
677 insn->ignore = orig_insn->ignore_alts;
679 if (insn->type != INSN_JUMP_CONDITIONAL &&
680 insn->type != INSN_JUMP_UNCONDITIONAL)
683 if (!insn->immediate)
686 dest_off = insn->offset + insn->len + insn->immediate;
687 if (dest_off == special_alt->new_off + special_alt->new_len) {
689 WARN("%s: alternative jump to end of section",
690 special_alt->orig_sec->name);
693 insn->jump_dest = fake_jump;
696 if (!insn->jump_dest) {
697 WARN_FUNC("can't find alternative jump destination",
698 insn->sec, insn->offset);
703 if (!last_new_insn) {
704 WARN_FUNC("can't find last new alternative instruction",
705 special_alt->new_sec, special_alt->new_off);
710 list_add(&fake_jump->list, &last_new_insn->list);
716 * A jump table entry can either convert a nop to a jump or a jump to a nop.
717 * If the original instruction is a jump, make the alt entry an effective nop
718 * by just skipping the original instruction.
720 static int handle_jump_alt(struct objtool_file *file,
721 struct special_alt *special_alt,
722 struct instruction *orig_insn,
723 struct instruction **new_insn)
725 if (orig_insn->type == INSN_NOP)
728 if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) {
729 WARN_FUNC("unsupported instruction at jump label",
730 orig_insn->sec, orig_insn->offset);
734 *new_insn = list_next_entry(orig_insn, list);
739 * Read all the special sections which have alternate instructions which can be
740 * patched in or redirected to at runtime. Each instruction having alternate
741 * instruction(s) has them added to its insn->alts list, which will be
742 * traversed in validate_branch().
744 static int add_special_section_alts(struct objtool_file *file)
746 struct list_head special_alts;
747 struct instruction *orig_insn, *new_insn;
748 struct special_alt *special_alt, *tmp;
749 struct alternative *alt;
752 ret = special_get_alts(file->elf, &special_alts);
756 list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
758 orig_insn = find_insn(file, special_alt->orig_sec,
759 special_alt->orig_off);
761 WARN_FUNC("special: can't find orig instruction",
762 special_alt->orig_sec, special_alt->orig_off);
768 if (!special_alt->group || special_alt->new_len) {
769 new_insn = find_insn(file, special_alt->new_sec,
770 special_alt->new_off);
772 WARN_FUNC("special: can't find new instruction",
773 special_alt->new_sec,
774 special_alt->new_off);
780 if (special_alt->group) {
781 if (!special_alt->orig_len) {
782 WARN_FUNC("empty alternative entry",
783 orig_insn->sec, orig_insn->offset);
787 ret = handle_group_alt(file, special_alt, orig_insn,
791 } else if (special_alt->jump_or_nop) {
792 ret = handle_jump_alt(file, special_alt, orig_insn,
798 alt = malloc(sizeof(*alt));
800 WARN("malloc failed");
805 alt->insn = new_insn;
806 list_add_tail(&alt->list, &orig_insn->alts);
808 list_del(&special_alt->list);
816 static int add_switch_table(struct objtool_file *file, struct instruction *insn,
817 struct rela *table, struct rela *next_table)
819 struct rela *rela = table;
820 struct instruction *alt_insn;
821 struct alternative *alt;
822 struct symbol *pfunc = insn->func->pfunc;
823 unsigned int prev_offset = 0;
825 list_for_each_entry_from(rela, &file->rodata->rela->rela_list, list) {
826 if (rela == next_table)
829 /* Make sure the switch table entries are consecutive: */
830 if (prev_offset && rela->offset != prev_offset + 8)
833 /* Detect function pointers from contiguous objects: */
834 if (rela->sym->sec == pfunc->sec &&
835 rela->addend == pfunc->offset)
838 alt_insn = find_insn(file, rela->sym->sec, rela->addend);
842 /* Make sure the jmp dest is in the function or subfunction: */
843 if (alt_insn->func->pfunc != pfunc)
846 alt = malloc(sizeof(*alt));
848 WARN("malloc failed");
852 alt->insn = alt_insn;
853 list_add_tail(&alt->list, &insn->alts);
854 prev_offset = rela->offset;
858 WARN_FUNC("can't find switch jump table",
859 insn->sec, insn->offset);
867 * find_switch_table() - Given a dynamic jump, find the switch jump table in
868 * .rodata associated with it.
870 * There are 3 basic patterns:
872 * 1. jmpq *[rodata addr](,%reg,8)
874 * This is the most common case by far. It jumps to an address in a simple
875 * jump table which is stored in .rodata.
877 * 2. jmpq *[rodata addr](%rip)
879 * This is caused by a rare GCC quirk, currently only seen in three driver
880 * functions in the kernel, only with certain obscure non-distro configs.
882 * As part of an optimization, GCC makes a copy of an existing switch jump
883 * table, modifies it, and then hard-codes the jump (albeit with an indirect
884 * jump) to use a single entry in the table. The rest of the jump table and
885 * some of its jump targets remain as dead code.
887 * In such a case we can just crudely ignore all unreachable instruction
888 * warnings for the entire object file. Ideally we would just ignore them
889 * for the function, but that would require redesigning the code quite a
890 * bit. And honestly that's just not worth doing: unreachable instruction
891 * warnings are of questionable value anyway, and this is such a rare issue.
893 * 3. mov [rodata addr],%reg1
894 * ... some instructions ...
895 * jmpq *(%reg1,%reg2,8)
897 * This is a fairly uncommon pattern which is new for GCC 6. As of this
898 * writing, there are 11 occurrences of it in the allmodconfig kernel.
900 * As of GCC 7 there are quite a few more of these and the 'in between' code
901 * is significant. Esp. with KASAN enabled some of the code between the mov
902 * and jmpq uses .rodata itself, which can confuse things.
904 * TODO: Once we have DWARF CFI and smarter instruction decoding logic,
905 * ensure the same register is used in the mov and jump instructions.
907 * NOTE: RETPOLINE made it harder still to decode dynamic jumps.
909 static struct rela *find_switch_table(struct objtool_file *file,
911 struct instruction *insn)
913 struct rela *text_rela, *rodata_rela;
914 struct instruction *orig_insn = insn;
915 unsigned long table_offset;
918 * Backward search using the @first_jump_src links, these help avoid
919 * much of the 'in between' code. Which avoids us getting confused by
923 &insn->list != &file->insn_list && insn->func && insn->func->pfunc == func;
924 insn = insn->first_jump_src ?: list_prev_entry(insn, list)) {
926 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
929 /* allow small jumps within the range */
930 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
932 (insn->jump_dest->offset <= insn->offset ||
933 insn->jump_dest->offset > orig_insn->offset))
936 /* look for a relocation which references .rodata */
937 text_rela = find_rela_by_dest_range(insn->sec, insn->offset,
939 if (!text_rela || text_rela->sym != file->rodata->sym)
942 table_offset = text_rela->addend;
943 if (text_rela->type == R_X86_64_PC32)
947 * Make sure the .rodata address isn't associated with a
948 * symbol. gcc jump tables are anonymous data.
950 if (find_symbol_containing(file->rodata, table_offset))
953 rodata_rela = find_rela_by_dest(file->rodata, table_offset);
956 * Use of RIP-relative switch jumps is quite rare, and
957 * indicates a rare GCC quirk/bug which can leave dead
960 if (text_rela->type == R_X86_64_PC32)
961 file->ignore_unreachables = true;
971 static int add_func_switch_tables(struct objtool_file *file,
974 struct instruction *insn, *last = NULL, *prev_jump = NULL;
975 struct rela *rela, *prev_rela = NULL;
978 func_for_each_insn_all(file, func, insn) {
983 * Store back-pointers for unconditional forward jumps such
984 * that find_switch_table() can back-track using those and
985 * avoid some potentially confusing code.
987 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
988 insn->offset > last->offset &&
989 insn->jump_dest->offset > insn->offset &&
990 !insn->jump_dest->first_jump_src) {
992 insn->jump_dest->first_jump_src = insn;
993 last = insn->jump_dest;
996 if (insn->type != INSN_JUMP_DYNAMIC)
999 rela = find_switch_table(file, func, insn);
1004 * We found a switch table, but we don't know yet how big it
1005 * is. Don't add it until we reach the end of the function or
1006 * the beginning of another switch table in the same function.
1009 ret = add_switch_table(file, prev_jump, prev_rela, rela);
1019 ret = add_switch_table(file, prev_jump, prev_rela, NULL);
1028 * For some switch statements, gcc generates a jump table in the .rodata
1029 * section which contains a list of addresses within the function to jump to.
1030 * This finds these jump tables and adds them to the insn->alts lists.
1032 static int add_switch_table_alts(struct objtool_file *file)
1034 struct section *sec;
1035 struct symbol *func;
1038 if (!file->rodata || !file->rodata->rela)
1041 for_each_sec(file, sec) {
1042 list_for_each_entry(func, &sec->symbol_list, list) {
1043 if (func->type != STT_FUNC)
1046 ret = add_func_switch_tables(file, func);
1055 static int read_unwind_hints(struct objtool_file *file)
1057 struct section *sec, *relasec;
1059 struct unwind_hint *hint;
1060 struct instruction *insn;
1061 struct cfi_reg *cfa;
1064 sec = find_section_by_name(file->elf, ".discard.unwind_hints");
1068 relasec = sec->rela;
1070 WARN("missing .rela.discard.unwind_hints section");
1074 if (sec->len % sizeof(struct unwind_hint)) {
1075 WARN("struct unwind_hint size mismatch");
1081 for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) {
1082 hint = (struct unwind_hint *)sec->data->d_buf + i;
1084 rela = find_rela_by_dest(sec, i * sizeof(*hint));
1086 WARN("can't find rela for unwind_hints[%d]", i);
1090 insn = find_insn(file, rela->sym->sec, rela->addend);
1092 WARN("can't find insn for unwind_hints[%d]", i);
1096 cfa = &insn->state.cfa;
1098 if (hint->type == UNWIND_HINT_TYPE_SAVE) {
1102 } else if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
1103 insn->restore = true;
1110 switch (hint->sp_reg) {
1111 case ORC_REG_UNDEFINED:
1112 cfa->base = CFI_UNDEFINED;
1120 case ORC_REG_SP_INDIRECT:
1121 cfa->base = CFI_SP_INDIRECT;
1124 cfa->base = CFI_R10;
1127 cfa->base = CFI_R13;
1136 WARN_FUNC("unsupported unwind_hint sp base reg %d",
1137 insn->sec, insn->offset, hint->sp_reg);
1141 cfa->offset = hint->sp_offset;
1142 insn->state.type = hint->type;
1148 static int read_retpoline_hints(struct objtool_file *file)
1150 struct section *sec;
1151 struct instruction *insn;
1154 sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
1158 list_for_each_entry(rela, &sec->rela_list, list) {
1159 if (rela->sym->type != STT_SECTION) {
1160 WARN("unexpected relocation symbol type in %s", sec->name);
1164 insn = find_insn(file, rela->sym->sec, rela->addend);
1166 WARN("bad .discard.retpoline_safe entry");
1170 if (insn->type != INSN_JUMP_DYNAMIC &&
1171 insn->type != INSN_CALL_DYNAMIC) {
1172 WARN_FUNC("retpoline_safe hint not an indirect jump/call",
1173 insn->sec, insn->offset);
1177 insn->retpoline_safe = true;
1183 static int decode_sections(struct objtool_file *file)
1187 ret = decode_instructions(file);
1191 ret = add_dead_ends(file);
1197 ret = add_nospec_ignores(file);
1201 ret = add_jump_destinations(file);
1205 ret = add_special_section_alts(file);
1209 ret = add_call_destinations(file);
1213 ret = add_switch_table_alts(file);
1217 ret = read_unwind_hints(file);
1221 ret = read_retpoline_hints(file);
1228 static bool is_fentry_call(struct instruction *insn)
1230 if (insn->type == INSN_CALL &&
1231 insn->call_dest->type == STT_NOTYPE &&
1232 !strcmp(insn->call_dest->name, "__fentry__"))
1238 static bool has_modified_stack_frame(struct insn_state *state)
1242 if (state->cfa.base != initial_func_cfi.cfa.base ||
1243 state->cfa.offset != initial_func_cfi.cfa.offset ||
1244 state->stack_size != initial_func_cfi.cfa.offset ||
1248 for (i = 0; i < CFI_NUM_REGS; i++)
1249 if (state->regs[i].base != initial_func_cfi.regs[i].base ||
1250 state->regs[i].offset != initial_func_cfi.regs[i].offset)
1256 static bool has_valid_stack_frame(struct insn_state *state)
1258 if (state->cfa.base == CFI_BP && state->regs[CFI_BP].base == CFI_CFA &&
1259 state->regs[CFI_BP].offset == -16)
1262 if (state->drap && state->regs[CFI_BP].base == CFI_BP)
1268 static int update_insn_state_regs(struct instruction *insn, struct insn_state *state)
1270 struct cfi_reg *cfa = &state->cfa;
1271 struct stack_op *op = &insn->stack_op;
1273 if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
1277 if (op->dest.type == OP_DEST_PUSH)
1281 if (op->src.type == OP_SRC_POP)
1284 /* add immediate to sp */
1285 if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
1286 op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
1287 cfa->offset -= op->src.offset;
1292 static void save_reg(struct insn_state *state, unsigned char reg, int base,
1295 if (arch_callee_saved_reg(reg) &&
1296 state->regs[reg].base == CFI_UNDEFINED) {
1297 state->regs[reg].base = base;
1298 state->regs[reg].offset = offset;
1302 static void restore_reg(struct insn_state *state, unsigned char reg)
1304 state->regs[reg].base = CFI_UNDEFINED;
1305 state->regs[reg].offset = 0;
1309 * A note about DRAP stack alignment:
1311 * GCC has the concept of a DRAP register, which is used to help keep track of
1312 * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
1313 * register. The typical DRAP pattern is:
1315 * 4c 8d 54 24 08 lea 0x8(%rsp),%r10
1316 * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
1317 * 41 ff 72 f8 pushq -0x8(%r10)
1319 * 48 89 e5 mov %rsp,%rbp
1326 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1329 * There are some variations in the epilogues, like:
1337 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1342 * 4c 8b 55 e8 mov -0x18(%rbp),%r10
1343 * 48 8b 5d e0 mov -0x20(%rbp),%rbx
1344 * 4c 8b 65 f0 mov -0x10(%rbp),%r12
1345 * 4c 8b 6d f8 mov -0x8(%rbp),%r13
1347 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1350 * Sometimes r13 is used as the DRAP register, in which case it's saved and
1351 * restored beforehand:
1354 * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
1355 * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
1357 * 49 8d 65 f0 lea -0x10(%r13),%rsp
1361 static int update_insn_state(struct instruction *insn, struct insn_state *state)
1363 struct stack_op *op = &insn->stack_op;
1364 struct cfi_reg *cfa = &state->cfa;
1365 struct cfi_reg *regs = state->regs;
1367 /* stack operations don't make sense with an undefined CFA */
1368 if (cfa->base == CFI_UNDEFINED) {
1370 WARN_FUNC("undefined stack state", insn->sec, insn->offset);
1376 if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET)
1377 return update_insn_state_regs(insn, state);
1379 switch (op->dest.type) {
1382 switch (op->src.type) {
1385 if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
1386 cfa->base == CFI_SP &&
1387 regs[CFI_BP].base == CFI_CFA &&
1388 regs[CFI_BP].offset == -cfa->offset) {
1390 /* mov %rsp, %rbp */
1391 cfa->base = op->dest.reg;
1392 state->bp_scratch = false;
1395 else if (op->src.reg == CFI_SP &&
1396 op->dest.reg == CFI_BP && state->drap) {
1398 /* drap: mov %rsp, %rbp */
1399 regs[CFI_BP].base = CFI_BP;
1400 regs[CFI_BP].offset = -state->stack_size;
1401 state->bp_scratch = false;
1404 else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
1409 * This is needed for the rare case where GCC
1416 state->vals[op->dest.reg].base = CFI_CFA;
1417 state->vals[op->dest.reg].offset = -state->stack_size;
1420 else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
1421 cfa->base == CFI_BP) {
1426 * Restore the original stack pointer (Clang).
1428 state->stack_size = -state->regs[CFI_BP].offset;
1431 else if (op->dest.reg == cfa->base) {
1433 /* mov %reg, %rsp */
1434 if (cfa->base == CFI_SP &&
1435 state->vals[op->src.reg].base == CFI_CFA) {
1438 * This is needed for the rare case
1439 * where GCC does something dumb like:
1441 * lea 0x8(%rsp), %rcx
1445 cfa->offset = -state->vals[op->src.reg].offset;
1446 state->stack_size = cfa->offset;
1449 cfa->base = CFI_UNDEFINED;
1457 if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
1460 state->stack_size -= op->src.offset;
1461 if (cfa->base == CFI_SP)
1462 cfa->offset -= op->src.offset;
1466 if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
1468 /* lea disp(%rbp), %rsp */
1469 state->stack_size = -(op->src.offset + regs[CFI_BP].offset);
1473 if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
1475 /* drap: lea disp(%rsp), %drap */
1476 state->drap_reg = op->dest.reg;
1479 * lea disp(%rsp), %reg
1481 * This is needed for the rare case where GCC
1482 * does something dumb like:
1484 * lea 0x8(%rsp), %rcx
1488 state->vals[op->dest.reg].base = CFI_CFA;
1489 state->vals[op->dest.reg].offset = \
1490 -state->stack_size + op->src.offset;
1495 if (state->drap && op->dest.reg == CFI_SP &&
1496 op->src.reg == state->drap_reg) {
1498 /* drap: lea disp(%drap), %rsp */
1500 cfa->offset = state->stack_size = -op->src.offset;
1501 state->drap_reg = CFI_UNDEFINED;
1502 state->drap = false;
1506 if (op->dest.reg == state->cfa.base) {
1507 WARN_FUNC("unsupported stack register modification",
1508 insn->sec, insn->offset);
1515 if (op->dest.reg != CFI_SP ||
1516 (state->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
1517 (state->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
1518 WARN_FUNC("unsupported stack pointer realignment",
1519 insn->sec, insn->offset);
1523 if (state->drap_reg != CFI_UNDEFINED) {
1524 /* drap: and imm, %rsp */
1525 cfa->base = state->drap_reg;
1526 cfa->offset = state->stack_size = 0;
1531 * Older versions of GCC (4.8ish) realign the stack
1532 * without DRAP, with a frame pointer.
1538 if (!state->drap && op->dest.type == OP_DEST_REG &&
1539 op->dest.reg == cfa->base) {
1545 if (state->drap && cfa->base == CFI_BP_INDIRECT &&
1546 op->dest.type == OP_DEST_REG &&
1547 op->dest.reg == state->drap_reg &&
1548 state->drap_offset == -state->stack_size) {
1550 /* drap: pop %drap */
1551 cfa->base = state->drap_reg;
1553 state->drap_offset = -1;
1555 } else if (regs[op->dest.reg].offset == -state->stack_size) {
1558 restore_reg(state, op->dest.reg);
1561 state->stack_size -= 8;
1562 if (cfa->base == CFI_SP)
1567 case OP_SRC_REG_INDIRECT:
1568 if (state->drap && op->src.reg == CFI_BP &&
1569 op->src.offset == state->drap_offset) {
1571 /* drap: mov disp(%rbp), %drap */
1572 cfa->base = state->drap_reg;
1574 state->drap_offset = -1;
1577 if (state->drap && op->src.reg == CFI_BP &&
1578 op->src.offset == regs[op->dest.reg].offset) {
1580 /* drap: mov disp(%rbp), %reg */
1581 restore_reg(state, op->dest.reg);
1583 } else if (op->src.reg == cfa->base &&
1584 op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
1586 /* mov disp(%rbp), %reg */
1587 /* mov disp(%rsp), %reg */
1588 restore_reg(state, op->dest.reg);
1594 WARN_FUNC("unknown stack-related instruction",
1595 insn->sec, insn->offset);
1602 state->stack_size += 8;
1603 if (cfa->base == CFI_SP)
1606 if (op->src.type != OP_SRC_REG)
1610 if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
1612 /* drap: push %drap */
1613 cfa->base = CFI_BP_INDIRECT;
1614 cfa->offset = -state->stack_size;
1616 /* save drap so we know when to restore it */
1617 state->drap_offset = -state->stack_size;
1619 } else if (op->src.reg == CFI_BP && cfa->base == state->drap_reg) {
1621 /* drap: push %rbp */
1622 state->stack_size = 0;
1624 } else if (regs[op->src.reg].base == CFI_UNDEFINED) {
1626 /* drap: push %reg */
1627 save_reg(state, op->src.reg, CFI_BP, -state->stack_size);
1633 save_reg(state, op->src.reg, CFI_CFA, -state->stack_size);
1636 /* detect when asm code uses rbp as a scratch register */
1637 if (!no_fp && insn->func && op->src.reg == CFI_BP &&
1638 cfa->base != CFI_BP)
1639 state->bp_scratch = true;
1642 case OP_DEST_REG_INDIRECT:
1645 if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
1647 /* drap: mov %drap, disp(%rbp) */
1648 cfa->base = CFI_BP_INDIRECT;
1649 cfa->offset = op->dest.offset;
1651 /* save drap offset so we know when to restore it */
1652 state->drap_offset = op->dest.offset;
1655 else if (regs[op->src.reg].base == CFI_UNDEFINED) {
1657 /* drap: mov reg, disp(%rbp) */
1658 save_reg(state, op->src.reg, CFI_BP, op->dest.offset);
1661 } else if (op->dest.reg == cfa->base) {
1663 /* mov reg, disp(%rbp) */
1664 /* mov reg, disp(%rsp) */
1665 save_reg(state, op->src.reg, CFI_CFA,
1666 op->dest.offset - state->cfa.offset);
1672 if ((!state->drap && cfa->base != CFI_BP) ||
1673 (state->drap && cfa->base != state->drap_reg)) {
1674 WARN_FUNC("leave instruction with modified stack frame",
1675 insn->sec, insn->offset);
1679 /* leave (mov %rbp, %rsp; pop %rbp) */
1681 state->stack_size = -state->regs[CFI_BP].offset - 8;
1682 restore_reg(state, CFI_BP);
1692 if (op->src.type != OP_SRC_POP) {
1693 WARN_FUNC("unknown stack-related memory operation",
1694 insn->sec, insn->offset);
1699 state->stack_size -= 8;
1700 if (cfa->base == CFI_SP)
1706 WARN_FUNC("unknown stack-related instruction",
1707 insn->sec, insn->offset);
1714 static bool insn_state_match(struct instruction *insn, struct insn_state *state)
1716 struct insn_state *state1 = &insn->state, *state2 = state;
1719 if (memcmp(&state1->cfa, &state2->cfa, sizeof(state1->cfa))) {
1720 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
1721 insn->sec, insn->offset,
1722 state1->cfa.base, state1->cfa.offset,
1723 state2->cfa.base, state2->cfa.offset);
1725 } else if (memcmp(&state1->regs, &state2->regs, sizeof(state1->regs))) {
1726 for (i = 0; i < CFI_NUM_REGS; i++) {
1727 if (!memcmp(&state1->regs[i], &state2->regs[i],
1728 sizeof(struct cfi_reg)))
1731 WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
1732 insn->sec, insn->offset,
1733 i, state1->regs[i].base, state1->regs[i].offset,
1734 i, state2->regs[i].base, state2->regs[i].offset);
1738 } else if (state1->type != state2->type) {
1739 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
1740 insn->sec, insn->offset, state1->type, state2->type);
1742 } else if (state1->drap != state2->drap ||
1743 (state1->drap && state1->drap_reg != state2->drap_reg) ||
1744 (state1->drap && state1->drap_offset != state2->drap_offset)) {
1745 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
1746 insn->sec, insn->offset,
1747 state1->drap, state1->drap_reg, state1->drap_offset,
1748 state2->drap, state2->drap_reg, state2->drap_offset);
1757 * Follow the branch starting at the given instruction, and recursively follow
1758 * any other branches (jumps). Meanwhile, track the frame pointer state at
1759 * each instruction and validate all the rules described in
1760 * tools/objtool/Documentation/stack-validation.txt.
1762 static int validate_branch(struct objtool_file *file, struct instruction *first,
1763 struct insn_state state)
1765 struct alternative *alt;
1766 struct instruction *insn, *next_insn;
1767 struct section *sec;
1768 struct symbol *func = NULL;
1774 if (insn->alt_group && list_empty(&insn->alts)) {
1775 WARN_FUNC("don't know how to handle branch to middle of alternative instruction group",
1781 next_insn = next_insn_same_sec(file, insn);
1783 if (file->c_file && func && insn->func && func != insn->func->pfunc) {
1784 WARN("%s() falls through to next function %s()",
1785 func->name, insn->func->name);
1790 func = insn->func->pfunc;
1792 if (func && insn->ignore) {
1793 WARN_FUNC("BUG: why am I validating an ignored function?",
1798 if (insn->visited) {
1799 if (!insn->hint && !insn_state_match(insn, &state))
1806 if (insn->restore) {
1807 struct instruction *save_insn, *i;
1811 func_for_each_insn_continue_reverse(file, insn->func, i) {
1819 WARN_FUNC("no corresponding CFI save for CFI restore",
1824 if (!save_insn->visited) {
1826 * Oops, no state to copy yet.
1827 * Hopefully we can reach this
1828 * instruction from another branch
1829 * after the save insn has been
1835 WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
1840 insn->state = save_insn->state;
1843 state = insn->state;
1846 insn->state = state;
1848 insn->visited = true;
1850 if (!insn->ignore_alts) {
1851 list_for_each_entry(alt, &insn->alts, list) {
1852 ret = validate_branch(file, alt->insn, state);
1858 switch (insn->type) {
1861 if (func && has_modified_stack_frame(&state)) {
1862 WARN_FUNC("return with modified stack frame",
1867 if (state.bp_scratch) {
1868 WARN("%s uses BP as a scratch register",
1876 if (is_fentry_call(insn))
1879 ret = dead_end_function(file, insn->call_dest);
1886 case INSN_CALL_DYNAMIC:
1887 if (!no_fp && func && !has_valid_stack_frame(&state)) {
1888 WARN_FUNC("call without frame pointer save/setup",
1894 case INSN_JUMP_CONDITIONAL:
1895 case INSN_JUMP_UNCONDITIONAL:
1896 if (insn->jump_dest &&
1897 (!func || !insn->jump_dest->func ||
1898 insn->jump_dest->func->pfunc == func)) {
1899 ret = validate_branch(file, insn->jump_dest,
1904 } else if (func && has_modified_stack_frame(&state)) {
1905 WARN_FUNC("sibling call from callable instruction with modified stack frame",
1910 if (insn->type == INSN_JUMP_UNCONDITIONAL)
1915 case INSN_JUMP_DYNAMIC:
1916 if (func && list_empty(&insn->alts) &&
1917 has_modified_stack_frame(&state)) {
1918 WARN_FUNC("sibling call from callable instruction with modified stack frame",
1925 case INSN_CONTEXT_SWITCH:
1926 if (func && (!next_insn || !next_insn->hint)) {
1927 WARN_FUNC("unsupported instruction in callable function",
1934 if (update_insn_state(insn, &state))
1947 if (state.cfa.base == CFI_UNDEFINED)
1949 WARN("%s: unexpected end of section", sec->name);
1959 static int validate_unwind_hints(struct objtool_file *file)
1961 struct instruction *insn;
1962 int ret, warnings = 0;
1963 struct insn_state state;
1968 clear_insn_state(&state);
1970 for_each_insn(file, insn) {
1971 if (insn->hint && !insn->visited) {
1972 ret = validate_branch(file, insn, state);
1980 static int validate_retpoline(struct objtool_file *file)
1982 struct instruction *insn;
1985 for_each_insn(file, insn) {
1986 if (insn->type != INSN_JUMP_DYNAMIC &&
1987 insn->type != INSN_CALL_DYNAMIC)
1990 if (insn->retpoline_safe)
1994 * .init.text code is ran before userspace and thus doesn't
1995 * strictly need retpolines, except for modules which are
1996 * loaded late, they very much do need retpoline in their
1999 if (!strcmp(insn->sec->name, ".init.text") && !module)
2002 WARN_FUNC("indirect %s found in RETPOLINE build",
2003 insn->sec, insn->offset,
2004 insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
2012 static bool is_kasan_insn(struct instruction *insn)
2014 return (insn->type == INSN_CALL &&
2015 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
2018 static bool is_ubsan_insn(struct instruction *insn)
2020 return (insn->type == INSN_CALL &&
2021 !strcmp(insn->call_dest->name,
2022 "__ubsan_handle_builtin_unreachable"));
2025 static bool ignore_unreachable_insn(struct instruction *insn)
2029 if (insn->ignore || insn->type == INSN_NOP)
2033 * Ignore any unused exceptions. This can happen when a whitelisted
2034 * function has an exception table entry.
2036 * Also ignore alternative replacement instructions. This can happen
2037 * when a whitelisted function uses one of the ALTERNATIVE macros.
2039 if (!strcmp(insn->sec->name, ".fixup") ||
2040 !strcmp(insn->sec->name, ".altinstr_replacement") ||
2041 !strcmp(insn->sec->name, ".altinstr_aux"))
2048 * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
2049 * __builtin_unreachable(). The BUG() macro has an unreachable() after
2050 * the UD2, which causes GCC's undefined trap logic to emit another UD2
2051 * (or occasionally a JMP to UD2).
2053 if (list_prev_entry(insn, list)->dead_end &&
2054 (insn->type == INSN_BUG ||
2055 (insn->type == INSN_JUMP_UNCONDITIONAL &&
2056 insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
2060 * Check if this (or a subsequent) instruction is related to
2061 * CONFIG_UBSAN or CONFIG_KASAN.
2063 * End the search at 5 instructions to avoid going into the weeds.
2065 for (i = 0; i < 5; i++) {
2067 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
2070 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
2071 if (insn->jump_dest &&
2072 insn->jump_dest->func == insn->func) {
2073 insn = insn->jump_dest;
2080 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
2083 insn = list_next_entry(insn, list);
2089 static int validate_functions(struct objtool_file *file)
2091 struct section *sec;
2092 struct symbol *func;
2093 struct instruction *insn;
2094 struct insn_state state;
2095 int ret, warnings = 0;
2097 clear_insn_state(&state);
2099 state.cfa = initial_func_cfi.cfa;
2100 memcpy(&state.regs, &initial_func_cfi.regs,
2101 CFI_NUM_REGS * sizeof(struct cfi_reg));
2102 state.stack_size = initial_func_cfi.cfa.offset;
2104 for_each_sec(file, sec) {
2105 list_for_each_entry(func, &sec->symbol_list, list) {
2106 if (func->type != STT_FUNC || func->pfunc != func)
2109 insn = find_insn(file, sec, func->offset);
2110 if (!insn || insn->ignore)
2113 ret = validate_branch(file, insn, state);
2121 static int validate_reachable_instructions(struct objtool_file *file)
2123 struct instruction *insn;
2125 if (file->ignore_unreachables)
2128 for_each_insn(file, insn) {
2129 if (insn->visited || ignore_unreachable_insn(insn))
2132 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
2139 static void cleanup(struct objtool_file *file)
2141 struct instruction *insn, *tmpinsn;
2142 struct alternative *alt, *tmpalt;
2144 list_for_each_entry_safe(insn, tmpinsn, &file->insn_list, list) {
2145 list_for_each_entry_safe(alt, tmpalt, &insn->alts, list) {
2146 list_del(&alt->list);
2149 list_del(&insn->list);
2150 hash_del(&insn->hash);
2153 elf_close(file->elf);
2156 static struct objtool_file file;
2158 int check(const char *_objname, bool orc)
2160 int ret, warnings = 0;
2164 file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY);
2168 INIT_LIST_HEAD(&file.insn_list);
2169 hash_init(file.insn_hash);
2170 file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard");
2171 file.rodata = find_section_by_name(file.elf, ".rodata");
2172 file.c_file = find_section_by_name(file.elf, ".comment");
2173 file.ignore_unreachables = no_unreachable;
2176 arch_initial_func_cfi_state(&initial_func_cfi);
2178 ret = decode_sections(&file);
2183 if (list_empty(&file.insn_list))
2187 ret = validate_retpoline(&file);
2193 ret = validate_functions(&file);
2198 ret = validate_unwind_hints(&file);
2204 ret = validate_reachable_instructions(&file);
2211 ret = create_orc(&file);
2215 ret = create_orc_sections(&file);
2219 ret = elf_write(file.elf);
2227 /* ignore warnings for now until we get all the code cleaned up */
2228 if (ret || warnings)