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>
32 struct list_head list;
33 struct instruction *insn;
37 struct cfi_state initial_func_cfi;
39 struct instruction *find_insn(struct objtool_file *file,
40 struct section *sec, unsigned long offset)
42 struct instruction *insn;
44 hash_for_each_possible(file->insn_hash, insn, hash, offset)
45 if (insn->sec == sec && insn->offset == offset)
51 static struct instruction *next_insn_same_sec(struct objtool_file *file,
52 struct instruction *insn)
54 struct instruction *next = list_next_entry(insn, list);
56 if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
62 #define func_for_each_insn(file, func, insn) \
63 for (insn = find_insn(file, func->sec, func->offset); \
64 insn && &insn->list != &file->insn_list && \
65 insn->sec == func->sec && \
66 insn->offset < func->offset + func->len; \
67 insn = list_next_entry(insn, list))
69 #define func_for_each_insn_continue_reverse(file, func, insn) \
70 for (insn = list_prev_entry(insn, list); \
71 &insn->list != &file->insn_list && \
72 insn->sec == func->sec && insn->offset >= func->offset; \
73 insn = list_prev_entry(insn, list))
75 #define sec_for_each_insn_from(file, insn) \
76 for (; insn; insn = next_insn_same_sec(file, insn))
78 #define sec_for_each_insn_continue(file, insn) \
79 for (insn = next_insn_same_sec(file, insn); insn; \
80 insn = next_insn_same_sec(file, insn))
83 * Check if the function has been manually whitelisted with the
84 * STACK_FRAME_NON_STANDARD macro, or if it should be automatically whitelisted
85 * due to its use of a context switching instruction.
87 static bool ignore_func(struct objtool_file *file, struct symbol *func)
91 /* check for STACK_FRAME_NON_STANDARD */
92 if (file->whitelist && file->whitelist->rela)
93 list_for_each_entry(rela, &file->whitelist->rela->rela_list, list) {
94 if (rela->sym->type == STT_SECTION &&
95 rela->sym->sec == func->sec &&
96 rela->addend == func->offset)
98 if (rela->sym->type == STT_FUNC && rela->sym == func)
106 * This checks to see if the given function is a "noreturn" function.
108 * For global functions which are outside the scope of this object file, we
109 * have to keep a manual list of them.
111 * For local functions, we have to detect them manually by simply looking for
112 * the lack of a return instruction.
119 static int __dead_end_function(struct objtool_file *file, struct symbol *func,
123 struct instruction *insn;
127 * Unfortunately these have to be hard coded because the noreturn
128 * attribute isn't provided in ELF data.
130 static const char * const global_noreturns[] = {
135 "__module_put_and_exit",
137 "kvm_spurious_fault",
144 if (func->bind == STB_WEAK)
147 if (func->bind == STB_GLOBAL)
148 for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
149 if (!strcmp(func->name, global_noreturns[i]))
155 func_for_each_insn(file, func, insn) {
158 if (insn->type == INSN_RETURN)
166 * A function can have a sibling call instead of a return. In that
167 * case, the function's dead-end status depends on whether the target
168 * of the sibling call returns.
170 func_for_each_insn(file, func, insn) {
171 if (insn->sec != func->sec ||
172 insn->offset >= func->offset + func->len)
175 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
176 struct instruction *dest = insn->jump_dest;
177 struct symbol *dest_func;
180 /* sibling call to another file */
183 if (dest->sec != func->sec ||
184 dest->offset < func->offset ||
185 dest->offset >= func->offset + func->len) {
186 /* local sibling call */
187 dest_func = find_symbol_by_offset(dest->sec,
192 if (recursion == 5) {
193 WARN_FUNC("infinite recursion (objtool bug!)",
194 dest->sec, dest->offset);
198 return __dead_end_function(file, dest_func,
203 if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts))
211 static int dead_end_function(struct objtool_file *file, struct symbol *func)
213 return __dead_end_function(file, func, 0);
216 static void clear_insn_state(struct insn_state *state)
220 memset(state, 0, sizeof(*state));
221 state->cfa.base = CFI_UNDEFINED;
222 for (i = 0; i < CFI_NUM_REGS; i++) {
223 state->regs[i].base = CFI_UNDEFINED;
224 state->vals[i].base = CFI_UNDEFINED;
226 state->drap_reg = CFI_UNDEFINED;
227 state->drap_offset = -1;
231 * Call the arch-specific instruction decoder for all the instructions and add
232 * them to the global instruction list.
234 static int decode_instructions(struct objtool_file *file)
238 unsigned long offset;
239 struct instruction *insn;
242 for_each_sec(file, sec) {
244 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
247 if (strcmp(sec->name, ".altinstr_replacement") &&
248 strcmp(sec->name, ".altinstr_aux") &&
249 strncmp(sec->name, ".discard.", 9))
252 for (offset = 0; offset < sec->len; offset += insn->len) {
253 insn = malloc(sizeof(*insn));
255 WARN("malloc failed");
258 memset(insn, 0, sizeof(*insn));
259 INIT_LIST_HEAD(&insn->alts);
260 clear_insn_state(&insn->state);
263 insn->offset = offset;
265 ret = arch_decode_instruction(file->elf, sec, offset,
267 &insn->len, &insn->type,
273 if (!insn->type || insn->type > INSN_LAST) {
274 WARN_FUNC("invalid instruction type %d",
275 insn->sec, insn->offset, insn->type);
280 hash_add(file->insn_hash, &insn->hash, insn->offset);
281 list_add_tail(&insn->list, &file->insn_list);
284 list_for_each_entry(func, &sec->symbol_list, list) {
285 if (func->type != STT_FUNC)
288 if (!find_insn(file, sec, func->offset)) {
289 WARN("%s(): can't find starting instruction",
294 func_for_each_insn(file, func, insn)
308 * Mark "ud2" instructions and manually annotated dead ends.
310 static int add_dead_ends(struct objtool_file *file)
314 struct instruction *insn;
318 * By default, "ud2" is a dead end unless otherwise annotated, because
319 * GCC 7 inserts it for certain divide-by-zero cases.
321 for_each_insn(file, insn)
322 if (insn->type == INSN_BUG)
323 insn->dead_end = true;
326 * Check for manually annotated dead ends.
328 sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
332 list_for_each_entry(rela, &sec->rela_list, list) {
333 if (rela->sym->type != STT_SECTION) {
334 WARN("unexpected relocation symbol type in %s", sec->name);
337 insn = find_insn(file, rela->sym->sec, rela->addend);
339 insn = list_prev_entry(insn, list);
340 else if (rela->addend == rela->sym->sec->len) {
342 list_for_each_entry_reverse(insn, &file->insn_list, list) {
343 if (insn->sec == rela->sym->sec) {
350 WARN("can't find unreachable insn at %s+0x%x",
351 rela->sym->sec->name, rela->addend);
355 WARN("can't find unreachable insn at %s+0x%x",
356 rela->sym->sec->name, rela->addend);
360 insn->dead_end = true;
365 * These manually annotated reachable checks are needed for GCC 4.4,
366 * where the Linux unreachable() macro isn't supported. In that case
367 * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
370 sec = find_section_by_name(file->elf, ".rela.discard.reachable");
374 list_for_each_entry(rela, &sec->rela_list, list) {
375 if (rela->sym->type != STT_SECTION) {
376 WARN("unexpected relocation symbol type in %s", sec->name);
379 insn = find_insn(file, rela->sym->sec, rela->addend);
381 insn = list_prev_entry(insn, list);
382 else if (rela->addend == rela->sym->sec->len) {
384 list_for_each_entry_reverse(insn, &file->insn_list, list) {
385 if (insn->sec == rela->sym->sec) {
392 WARN("can't find reachable insn at %s+0x%x",
393 rela->sym->sec->name, rela->addend);
397 WARN("can't find reachable insn at %s+0x%x",
398 rela->sym->sec->name, rela->addend);
402 insn->dead_end = false;
409 * Warnings shouldn't be reported for ignored functions.
411 static void add_ignores(struct objtool_file *file)
413 struct instruction *insn;
417 for_each_sec(file, sec) {
418 list_for_each_entry(func, &sec->symbol_list, list) {
419 if (func->type != STT_FUNC)
422 if (!ignore_func(file, func))
425 func_for_each_insn(file, func, insn)
432 * FIXME: For now, just ignore any alternatives which add retpolines. This is
433 * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
434 * But it at least allows objtool to understand the control flow *around* the
437 static int add_nospec_ignores(struct objtool_file *file)
441 struct instruction *insn;
443 sec = find_section_by_name(file->elf, ".rela.discard.nospec");
447 list_for_each_entry(rela, &sec->rela_list, list) {
448 if (rela->sym->type != STT_SECTION) {
449 WARN("unexpected relocation symbol type in %s", sec->name);
453 insn = find_insn(file, rela->sym->sec, rela->addend);
455 WARN("bad .discard.nospec entry");
459 insn->ignore_alts = true;
466 * Find the destination instructions for all jumps.
468 static int add_jump_destinations(struct objtool_file *file)
470 struct instruction *insn;
472 struct section *dest_sec;
473 unsigned long dest_off;
475 for_each_insn(file, insn) {
476 if (insn->type != INSN_JUMP_CONDITIONAL &&
477 insn->type != INSN_JUMP_UNCONDITIONAL)
483 rela = find_rela_by_dest_range(insn->sec, insn->offset,
486 dest_sec = insn->sec;
487 dest_off = insn->offset + insn->len + insn->immediate;
488 } else if (rela->sym->type == STT_SECTION) {
489 dest_sec = rela->sym->sec;
490 dest_off = rela->addend + 4;
491 } else if (rela->sym->sec->idx) {
492 dest_sec = rela->sym->sec;
493 dest_off = rela->sym->sym.st_value + rela->addend + 4;
494 } else if (strstr(rela->sym->name, "_indirect_thunk_")) {
496 * Retpoline jumps are really dynamic jumps in
497 * disguise, so convert them accordingly.
499 insn->type = INSN_JUMP_DYNAMIC;
500 insn->retpoline_safe = true;
508 insn->jump_dest = find_insn(file, dest_sec, dest_off);
509 if (!insn->jump_dest) {
512 * This is a special case where an alt instruction
513 * jumps past the end of the section. These are
514 * handled later in handle_group_alt().
516 if (!strcmp(insn->sec->name, ".altinstr_replacement"))
519 WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
520 insn->sec, insn->offset, dest_sec->name,
530 * Find the destination instructions for all calls.
532 static int add_call_destinations(struct objtool_file *file)
534 struct instruction *insn;
535 unsigned long dest_off;
538 for_each_insn(file, insn) {
539 if (insn->type != INSN_CALL)
542 rela = find_rela_by_dest_range(insn->sec, insn->offset,
545 dest_off = insn->offset + insn->len + insn->immediate;
546 insn->call_dest = find_symbol_by_offset(insn->sec,
549 if (!insn->call_dest && !insn->ignore) {
550 WARN_FUNC("unsupported intra-function call",
551 insn->sec, insn->offset);
553 WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE.");
557 } else if (rela->sym->type == STT_SECTION) {
558 insn->call_dest = find_symbol_by_offset(rela->sym->sec,
560 if (!insn->call_dest ||
561 insn->call_dest->type != STT_FUNC) {
562 WARN_FUNC("can't find call dest symbol at %s+0x%x",
563 insn->sec, insn->offset,
564 rela->sym->sec->name,
569 insn->call_dest = rela->sym;
576 * The .alternatives section requires some extra special care, over and above
577 * what other special sections require:
579 * 1. Because alternatives are patched in-place, we need to insert a fake jump
580 * instruction at the end so that validate_branch() skips all the original
581 * replaced instructions when validating the new instruction path.
583 * 2. An added wrinkle is that the new instruction length might be zero. In
584 * that case the old instructions are replaced with noops. We simulate that
585 * by creating a fake jump as the only new instruction.
587 * 3. In some cases, the alternative section includes an instruction which
588 * conditionally jumps to the _end_ of the entry. We have to modify these
589 * jumps' destinations to point back to .text rather than the end of the
590 * entry in .altinstr_replacement.
592 * 4. It has been requested that we don't validate the !POPCNT feature path
593 * which is a "very very small percentage of machines".
595 static int handle_group_alt(struct objtool_file *file,
596 struct special_alt *special_alt,
597 struct instruction *orig_insn,
598 struct instruction **new_insn)
600 struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL;
601 unsigned long dest_off;
603 last_orig_insn = NULL;
605 sec_for_each_insn_from(file, insn) {
606 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
609 if (special_alt->skip_orig)
610 insn->type = INSN_NOP;
612 insn->alt_group = true;
613 last_orig_insn = insn;
616 if (next_insn_same_sec(file, last_orig_insn)) {
617 fake_jump = malloc(sizeof(*fake_jump));
619 WARN("malloc failed");
622 memset(fake_jump, 0, sizeof(*fake_jump));
623 INIT_LIST_HEAD(&fake_jump->alts);
624 clear_insn_state(&fake_jump->state);
626 fake_jump->sec = special_alt->new_sec;
627 fake_jump->offset = -1;
628 fake_jump->type = INSN_JUMP_UNCONDITIONAL;
629 fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
630 fake_jump->ignore = true;
633 if (!special_alt->new_len) {
635 WARN("%s: empty alternative at end of section",
636 special_alt->orig_sec->name);
640 *new_insn = fake_jump;
644 last_new_insn = NULL;
646 sec_for_each_insn_from(file, insn) {
647 if (insn->offset >= special_alt->new_off + special_alt->new_len)
650 last_new_insn = insn;
652 insn->ignore = orig_insn->ignore_alts;
654 if (insn->type != INSN_JUMP_CONDITIONAL &&
655 insn->type != INSN_JUMP_UNCONDITIONAL)
658 if (!insn->immediate)
661 dest_off = insn->offset + insn->len + insn->immediate;
662 if (dest_off == special_alt->new_off + special_alt->new_len) {
664 WARN("%s: alternative jump to end of section",
665 special_alt->orig_sec->name);
668 insn->jump_dest = fake_jump;
671 if (!insn->jump_dest) {
672 WARN_FUNC("can't find alternative jump destination",
673 insn->sec, insn->offset);
678 if (!last_new_insn) {
679 WARN_FUNC("can't find last new alternative instruction",
680 special_alt->new_sec, special_alt->new_off);
685 list_add(&fake_jump->list, &last_new_insn->list);
691 * A jump table entry can either convert a nop to a jump or a jump to a nop.
692 * If the original instruction is a jump, make the alt entry an effective nop
693 * by just skipping the original instruction.
695 static int handle_jump_alt(struct objtool_file *file,
696 struct special_alt *special_alt,
697 struct instruction *orig_insn,
698 struct instruction **new_insn)
700 if (orig_insn->type == INSN_NOP)
703 if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) {
704 WARN_FUNC("unsupported instruction at jump label",
705 orig_insn->sec, orig_insn->offset);
709 *new_insn = list_next_entry(orig_insn, list);
714 * Read all the special sections which have alternate instructions which can be
715 * patched in or redirected to at runtime. Each instruction having alternate
716 * instruction(s) has them added to its insn->alts list, which will be
717 * traversed in validate_branch().
719 static int add_special_section_alts(struct objtool_file *file)
721 struct list_head special_alts;
722 struct instruction *orig_insn, *new_insn;
723 struct special_alt *special_alt, *tmp;
724 struct alternative *alt;
727 ret = special_get_alts(file->elf, &special_alts);
731 list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
733 orig_insn = find_insn(file, special_alt->orig_sec,
734 special_alt->orig_off);
736 WARN_FUNC("special: can't find orig instruction",
737 special_alt->orig_sec, special_alt->orig_off);
743 if (!special_alt->group || special_alt->new_len) {
744 new_insn = find_insn(file, special_alt->new_sec,
745 special_alt->new_off);
747 WARN_FUNC("special: can't find new instruction",
748 special_alt->new_sec,
749 special_alt->new_off);
755 if (special_alt->group) {
756 ret = handle_group_alt(file, special_alt, orig_insn,
760 } else if (special_alt->jump_or_nop) {
761 ret = handle_jump_alt(file, special_alt, orig_insn,
767 alt = malloc(sizeof(*alt));
769 WARN("malloc failed");
774 alt->insn = new_insn;
775 list_add_tail(&alt->list, &orig_insn->alts);
777 list_del(&special_alt->list);
785 static int add_switch_table(struct objtool_file *file, struct symbol *func,
786 struct instruction *insn, struct rela *table,
787 struct rela *next_table)
789 struct rela *rela = table;
790 struct instruction *alt_insn;
791 struct alternative *alt;
793 list_for_each_entry_from(rela, &file->rodata->rela->rela_list, list) {
794 if (rela == next_table)
797 if (rela->sym->sec != insn->sec ||
798 rela->addend <= func->offset ||
799 rela->addend >= func->offset + func->len)
802 alt_insn = find_insn(file, insn->sec, rela->addend);
804 WARN("%s: can't find instruction at %s+0x%x",
805 file->rodata->rela->name, insn->sec->name,
810 alt = malloc(sizeof(*alt));
812 WARN("malloc failed");
816 alt->insn = alt_insn;
817 list_add_tail(&alt->list, &insn->alts);
824 * find_switch_table() - Given a dynamic jump, find the switch jump table in
825 * .rodata associated with it.
827 * There are 3 basic patterns:
829 * 1. jmpq *[rodata addr](,%reg,8)
831 * This is the most common case by far. It jumps to an address in a simple
832 * jump table which is stored in .rodata.
834 * 2. jmpq *[rodata addr](%rip)
836 * This is caused by a rare GCC quirk, currently only seen in three driver
837 * functions in the kernel, only with certain obscure non-distro configs.
839 * As part of an optimization, GCC makes a copy of an existing switch jump
840 * table, modifies it, and then hard-codes the jump (albeit with an indirect
841 * jump) to use a single entry in the table. The rest of the jump table and
842 * some of its jump targets remain as dead code.
844 * In such a case we can just crudely ignore all unreachable instruction
845 * warnings for the entire object file. Ideally we would just ignore them
846 * for the function, but that would require redesigning the code quite a
847 * bit. And honestly that's just not worth doing: unreachable instruction
848 * warnings are of questionable value anyway, and this is such a rare issue.
850 * 3. mov [rodata addr],%reg1
851 * ... some instructions ...
852 * jmpq *(%reg1,%reg2,8)
854 * This is a fairly uncommon pattern which is new for GCC 6. As of this
855 * writing, there are 11 occurrences of it in the allmodconfig kernel.
857 * As of GCC 7 there are quite a few more of these and the 'in between' code
858 * is significant. Esp. with KASAN enabled some of the code between the mov
859 * and jmpq uses .rodata itself, which can confuse things.
861 * TODO: Once we have DWARF CFI and smarter instruction decoding logic,
862 * ensure the same register is used in the mov and jump instructions.
864 * NOTE: RETPOLINE made it harder still to decode dynamic jumps.
866 static struct rela *find_switch_table(struct objtool_file *file,
868 struct instruction *insn)
870 struct rela *text_rela, *rodata_rela;
871 struct instruction *orig_insn = insn;
873 text_rela = find_rela_by_dest_range(insn->sec, insn->offset, insn->len);
874 if (text_rela && text_rela->sym == file->rodata->sym) {
876 rodata_rela = find_rela_by_dest(file->rodata,
882 rodata_rela = find_rela_by_dest(file->rodata,
883 text_rela->addend + 4);
887 file->ignore_unreachables = true;
893 * Backward search using the @first_jump_src links, these help avoid
894 * much of the 'in between' code. Which avoids us getting confused by
897 for (insn = list_prev_entry(insn, list);
899 &insn->list != &file->insn_list &&
900 insn->sec == func->sec &&
901 insn->offset >= func->offset;
903 insn = insn->first_jump_src ?: list_prev_entry(insn, list)) {
905 if (insn->type == INSN_JUMP_DYNAMIC)
908 /* allow small jumps within the range */
909 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
911 (insn->jump_dest->offset <= insn->offset ||
912 insn->jump_dest->offset > orig_insn->offset))
915 /* look for a relocation which references .rodata */
916 text_rela = find_rela_by_dest_range(insn->sec, insn->offset,
918 if (!text_rela || text_rela->sym != file->rodata->sym)
922 * Make sure the .rodata address isn't associated with a
923 * symbol. gcc jump tables are anonymous data.
925 if (find_symbol_containing(file->rodata, text_rela->addend))
928 rodata_rela = find_rela_by_dest(file->rodata, text_rela->addend);
939 static int add_func_switch_tables(struct objtool_file *file,
942 struct instruction *insn, *last = NULL, *prev_jump = NULL;
943 struct rela *rela, *prev_rela = NULL;
946 func_for_each_insn(file, func, insn) {
951 * Store back-pointers for unconditional forward jumps such
952 * that find_switch_table() can back-track using those and
953 * avoid some potentially confusing code.
955 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
956 insn->offset > last->offset &&
957 insn->jump_dest->offset > insn->offset &&
958 !insn->jump_dest->first_jump_src) {
960 insn->jump_dest->first_jump_src = insn;
961 last = insn->jump_dest;
964 if (insn->type != INSN_JUMP_DYNAMIC)
967 rela = find_switch_table(file, func, insn);
972 * We found a switch table, but we don't know yet how big it
973 * is. Don't add it until we reach the end of the function or
974 * the beginning of another switch table in the same function.
977 ret = add_switch_table(file, func, prev_jump, prev_rela,
988 ret = add_switch_table(file, func, prev_jump, prev_rela, NULL);
997 * For some switch statements, gcc generates a jump table in the .rodata
998 * section which contains a list of addresses within the function to jump to.
999 * This finds these jump tables and adds them to the insn->alts lists.
1001 static int add_switch_table_alts(struct objtool_file *file)
1003 struct section *sec;
1004 struct symbol *func;
1007 if (!file->rodata || !file->rodata->rela)
1010 for_each_sec(file, sec) {
1011 list_for_each_entry(func, &sec->symbol_list, list) {
1012 if (func->type != STT_FUNC)
1015 ret = add_func_switch_tables(file, func);
1024 static int read_unwind_hints(struct objtool_file *file)
1026 struct section *sec, *relasec;
1028 struct unwind_hint *hint;
1029 struct instruction *insn;
1030 struct cfi_reg *cfa;
1033 sec = find_section_by_name(file->elf, ".discard.unwind_hints");
1037 relasec = sec->rela;
1039 WARN("missing .rela.discard.unwind_hints section");
1043 if (sec->len % sizeof(struct unwind_hint)) {
1044 WARN("struct unwind_hint size mismatch");
1050 for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) {
1051 hint = (struct unwind_hint *)sec->data->d_buf + i;
1053 rela = find_rela_by_dest(sec, i * sizeof(*hint));
1055 WARN("can't find rela for unwind_hints[%d]", i);
1059 insn = find_insn(file, rela->sym->sec, rela->addend);
1061 WARN("can't find insn for unwind_hints[%d]", i);
1065 cfa = &insn->state.cfa;
1067 if (hint->type == UNWIND_HINT_TYPE_SAVE) {
1071 } else if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
1072 insn->restore = true;
1079 switch (hint->sp_reg) {
1080 case ORC_REG_UNDEFINED:
1081 cfa->base = CFI_UNDEFINED;
1089 case ORC_REG_SP_INDIRECT:
1090 cfa->base = CFI_SP_INDIRECT;
1093 cfa->base = CFI_R10;
1096 cfa->base = CFI_R13;
1105 WARN_FUNC("unsupported unwind_hint sp base reg %d",
1106 insn->sec, insn->offset, hint->sp_reg);
1110 cfa->offset = hint->sp_offset;
1111 insn->state.type = hint->type;
1117 static int read_retpoline_hints(struct objtool_file *file)
1119 struct section *sec;
1120 struct instruction *insn;
1123 sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
1127 list_for_each_entry(rela, &sec->rela_list, list) {
1128 if (rela->sym->type != STT_SECTION) {
1129 WARN("unexpected relocation symbol type in %s", sec->name);
1133 insn = find_insn(file, rela->sym->sec, rela->addend);
1135 WARN("bad .discard.retpoline_safe entry");
1139 if (insn->type != INSN_JUMP_DYNAMIC &&
1140 insn->type != INSN_CALL_DYNAMIC) {
1141 WARN_FUNC("retpoline_safe hint not an indirect jump/call",
1142 insn->sec, insn->offset);
1146 insn->retpoline_safe = true;
1152 static int decode_sections(struct objtool_file *file)
1156 ret = decode_instructions(file);
1160 ret = add_dead_ends(file);
1166 ret = add_nospec_ignores(file);
1170 ret = add_jump_destinations(file);
1174 ret = add_special_section_alts(file);
1178 ret = add_call_destinations(file);
1182 ret = add_switch_table_alts(file);
1186 ret = read_unwind_hints(file);
1190 ret = read_retpoline_hints(file);
1197 static bool is_fentry_call(struct instruction *insn)
1199 if (insn->type == INSN_CALL &&
1200 insn->call_dest->type == STT_NOTYPE &&
1201 !strcmp(insn->call_dest->name, "__fentry__"))
1207 static bool has_modified_stack_frame(struct insn_state *state)
1211 if (state->cfa.base != initial_func_cfi.cfa.base ||
1212 state->cfa.offset != initial_func_cfi.cfa.offset ||
1213 state->stack_size != initial_func_cfi.cfa.offset ||
1217 for (i = 0; i < CFI_NUM_REGS; i++)
1218 if (state->regs[i].base != initial_func_cfi.regs[i].base ||
1219 state->regs[i].offset != initial_func_cfi.regs[i].offset)
1225 static bool has_valid_stack_frame(struct insn_state *state)
1227 if (state->cfa.base == CFI_BP && state->regs[CFI_BP].base == CFI_CFA &&
1228 state->regs[CFI_BP].offset == -16)
1231 if (state->drap && state->regs[CFI_BP].base == CFI_BP)
1237 static int update_insn_state_regs(struct instruction *insn, struct insn_state *state)
1239 struct cfi_reg *cfa = &state->cfa;
1240 struct stack_op *op = &insn->stack_op;
1242 if (cfa->base != CFI_SP)
1246 if (op->dest.type == OP_DEST_PUSH)
1250 if (op->src.type == OP_SRC_POP)
1253 /* add immediate to sp */
1254 if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
1255 op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
1256 cfa->offset -= op->src.offset;
1261 static void save_reg(struct insn_state *state, unsigned char reg, int base,
1264 if (arch_callee_saved_reg(reg) &&
1265 state->regs[reg].base == CFI_UNDEFINED) {
1266 state->regs[reg].base = base;
1267 state->regs[reg].offset = offset;
1271 static void restore_reg(struct insn_state *state, unsigned char reg)
1273 state->regs[reg].base = CFI_UNDEFINED;
1274 state->regs[reg].offset = 0;
1278 * A note about DRAP stack alignment:
1280 * GCC has the concept of a DRAP register, which is used to help keep track of
1281 * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
1282 * register. The typical DRAP pattern is:
1284 * 4c 8d 54 24 08 lea 0x8(%rsp),%r10
1285 * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
1286 * 41 ff 72 f8 pushq -0x8(%r10)
1288 * 48 89 e5 mov %rsp,%rbp
1295 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1298 * There are some variations in the epilogues, like:
1306 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1311 * 4c 8b 55 e8 mov -0x18(%rbp),%r10
1312 * 48 8b 5d e0 mov -0x20(%rbp),%rbx
1313 * 4c 8b 65 f0 mov -0x10(%rbp),%r12
1314 * 4c 8b 6d f8 mov -0x8(%rbp),%r13
1316 * 49 8d 62 f8 lea -0x8(%r10),%rsp
1319 * Sometimes r13 is used as the DRAP register, in which case it's saved and
1320 * restored beforehand:
1323 * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
1324 * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
1326 * 49 8d 65 f0 lea -0x10(%r13),%rsp
1330 static int update_insn_state(struct instruction *insn, struct insn_state *state)
1332 struct stack_op *op = &insn->stack_op;
1333 struct cfi_reg *cfa = &state->cfa;
1334 struct cfi_reg *regs = state->regs;
1336 /* stack operations don't make sense with an undefined CFA */
1337 if (cfa->base == CFI_UNDEFINED) {
1339 WARN_FUNC("undefined stack state", insn->sec, insn->offset);
1345 if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET)
1346 return update_insn_state_regs(insn, state);
1348 switch (op->dest.type) {
1351 switch (op->src.type) {
1354 if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
1355 cfa->base == CFI_SP &&
1356 regs[CFI_BP].base == CFI_CFA &&
1357 regs[CFI_BP].offset == -cfa->offset) {
1359 /* mov %rsp, %rbp */
1360 cfa->base = op->dest.reg;
1361 state->bp_scratch = false;
1364 else if (op->src.reg == CFI_SP &&
1365 op->dest.reg == CFI_BP && state->drap) {
1367 /* drap: mov %rsp, %rbp */
1368 regs[CFI_BP].base = CFI_BP;
1369 regs[CFI_BP].offset = -state->stack_size;
1370 state->bp_scratch = false;
1373 else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
1378 * This is needed for the rare case where GCC
1385 state->vals[op->dest.reg].base = CFI_CFA;
1386 state->vals[op->dest.reg].offset = -state->stack_size;
1389 else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
1390 cfa->base == CFI_BP) {
1395 * Restore the original stack pointer (Clang).
1397 state->stack_size = -state->regs[CFI_BP].offset;
1400 else if (op->dest.reg == cfa->base) {
1402 /* mov %reg, %rsp */
1403 if (cfa->base == CFI_SP &&
1404 state->vals[op->src.reg].base == CFI_CFA) {
1407 * This is needed for the rare case
1408 * where GCC does something dumb like:
1410 * lea 0x8(%rsp), %rcx
1414 cfa->offset = -state->vals[op->src.reg].offset;
1415 state->stack_size = cfa->offset;
1418 cfa->base = CFI_UNDEFINED;
1426 if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
1429 state->stack_size -= op->src.offset;
1430 if (cfa->base == CFI_SP)
1431 cfa->offset -= op->src.offset;
1435 if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
1437 /* lea disp(%rbp), %rsp */
1438 state->stack_size = -(op->src.offset + regs[CFI_BP].offset);
1442 if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
1444 /* drap: lea disp(%rsp), %drap */
1445 state->drap_reg = op->dest.reg;
1448 * lea disp(%rsp), %reg
1450 * This is needed for the rare case where GCC
1451 * does something dumb like:
1453 * lea 0x8(%rsp), %rcx
1457 state->vals[op->dest.reg].base = CFI_CFA;
1458 state->vals[op->dest.reg].offset = \
1459 -state->stack_size + op->src.offset;
1464 if (state->drap && op->dest.reg == CFI_SP &&
1465 op->src.reg == state->drap_reg) {
1467 /* drap: lea disp(%drap), %rsp */
1469 cfa->offset = state->stack_size = -op->src.offset;
1470 state->drap_reg = CFI_UNDEFINED;
1471 state->drap = false;
1475 if (op->dest.reg == state->cfa.base) {
1476 WARN_FUNC("unsupported stack register modification",
1477 insn->sec, insn->offset);
1484 if (op->dest.reg != CFI_SP ||
1485 (state->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
1486 (state->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
1487 WARN_FUNC("unsupported stack pointer realignment",
1488 insn->sec, insn->offset);
1492 if (state->drap_reg != CFI_UNDEFINED) {
1493 /* drap: and imm, %rsp */
1494 cfa->base = state->drap_reg;
1495 cfa->offset = state->stack_size = 0;
1500 * Older versions of GCC (4.8ish) realign the stack
1501 * without DRAP, with a frame pointer.
1507 if (!state->drap && op->dest.type == OP_DEST_REG &&
1508 op->dest.reg == cfa->base) {
1514 if (state->drap && cfa->base == CFI_BP_INDIRECT &&
1515 op->dest.type == OP_DEST_REG &&
1516 op->dest.reg == state->drap_reg &&
1517 state->drap_offset == -state->stack_size) {
1519 /* drap: pop %drap */
1520 cfa->base = state->drap_reg;
1522 state->drap_offset = -1;
1524 } else if (regs[op->dest.reg].offset == -state->stack_size) {
1527 restore_reg(state, op->dest.reg);
1530 state->stack_size -= 8;
1531 if (cfa->base == CFI_SP)
1536 case OP_SRC_REG_INDIRECT:
1537 if (state->drap && op->src.reg == CFI_BP &&
1538 op->src.offset == state->drap_offset) {
1540 /* drap: mov disp(%rbp), %drap */
1541 cfa->base = state->drap_reg;
1543 state->drap_offset = -1;
1546 if (state->drap && op->src.reg == CFI_BP &&
1547 op->src.offset == regs[op->dest.reg].offset) {
1549 /* drap: mov disp(%rbp), %reg */
1550 restore_reg(state, op->dest.reg);
1552 } else if (op->src.reg == cfa->base &&
1553 op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
1555 /* mov disp(%rbp), %reg */
1556 /* mov disp(%rsp), %reg */
1557 restore_reg(state, op->dest.reg);
1563 WARN_FUNC("unknown stack-related instruction",
1564 insn->sec, insn->offset);
1571 state->stack_size += 8;
1572 if (cfa->base == CFI_SP)
1575 if (op->src.type != OP_SRC_REG)
1579 if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
1581 /* drap: push %drap */
1582 cfa->base = CFI_BP_INDIRECT;
1583 cfa->offset = -state->stack_size;
1585 /* save drap so we know when to restore it */
1586 state->drap_offset = -state->stack_size;
1588 } else if (op->src.reg == CFI_BP && cfa->base == state->drap_reg) {
1590 /* drap: push %rbp */
1591 state->stack_size = 0;
1593 } else if (regs[op->src.reg].base == CFI_UNDEFINED) {
1595 /* drap: push %reg */
1596 save_reg(state, op->src.reg, CFI_BP, -state->stack_size);
1602 save_reg(state, op->src.reg, CFI_CFA, -state->stack_size);
1605 /* detect when asm code uses rbp as a scratch register */
1606 if (!no_fp && insn->func && op->src.reg == CFI_BP &&
1607 cfa->base != CFI_BP)
1608 state->bp_scratch = true;
1611 case OP_DEST_REG_INDIRECT:
1614 if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
1616 /* drap: mov %drap, disp(%rbp) */
1617 cfa->base = CFI_BP_INDIRECT;
1618 cfa->offset = op->dest.offset;
1620 /* save drap offset so we know when to restore it */
1621 state->drap_offset = op->dest.offset;
1624 else if (regs[op->src.reg].base == CFI_UNDEFINED) {
1626 /* drap: mov reg, disp(%rbp) */
1627 save_reg(state, op->src.reg, CFI_BP, op->dest.offset);
1630 } else if (op->dest.reg == cfa->base) {
1632 /* mov reg, disp(%rbp) */
1633 /* mov reg, disp(%rsp) */
1634 save_reg(state, op->src.reg, CFI_CFA,
1635 op->dest.offset - state->cfa.offset);
1641 if ((!state->drap && cfa->base != CFI_BP) ||
1642 (state->drap && cfa->base != state->drap_reg)) {
1643 WARN_FUNC("leave instruction with modified stack frame",
1644 insn->sec, insn->offset);
1648 /* leave (mov %rbp, %rsp; pop %rbp) */
1650 state->stack_size = -state->regs[CFI_BP].offset - 8;
1651 restore_reg(state, CFI_BP);
1661 if (op->src.type != OP_SRC_POP) {
1662 WARN_FUNC("unknown stack-related memory operation",
1663 insn->sec, insn->offset);
1668 state->stack_size -= 8;
1669 if (cfa->base == CFI_SP)
1675 WARN_FUNC("unknown stack-related instruction",
1676 insn->sec, insn->offset);
1683 static bool insn_state_match(struct instruction *insn, struct insn_state *state)
1685 struct insn_state *state1 = &insn->state, *state2 = state;
1688 if (memcmp(&state1->cfa, &state2->cfa, sizeof(state1->cfa))) {
1689 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
1690 insn->sec, insn->offset,
1691 state1->cfa.base, state1->cfa.offset,
1692 state2->cfa.base, state2->cfa.offset);
1694 } else if (memcmp(&state1->regs, &state2->regs, sizeof(state1->regs))) {
1695 for (i = 0; i < CFI_NUM_REGS; i++) {
1696 if (!memcmp(&state1->regs[i], &state2->regs[i],
1697 sizeof(struct cfi_reg)))
1700 WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
1701 insn->sec, insn->offset,
1702 i, state1->regs[i].base, state1->regs[i].offset,
1703 i, state2->regs[i].base, state2->regs[i].offset);
1707 } else if (state1->type != state2->type) {
1708 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
1709 insn->sec, insn->offset, state1->type, state2->type);
1711 } else if (state1->drap != state2->drap ||
1712 (state1->drap && state1->drap_reg != state2->drap_reg) ||
1713 (state1->drap && state1->drap_offset != state2->drap_offset)) {
1714 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
1715 insn->sec, insn->offset,
1716 state1->drap, state1->drap_reg, state1->drap_offset,
1717 state2->drap, state2->drap_reg, state2->drap_offset);
1726 * Follow the branch starting at the given instruction, and recursively follow
1727 * any other branches (jumps). Meanwhile, track the frame pointer state at
1728 * each instruction and validate all the rules described in
1729 * tools/objtool/Documentation/stack-validation.txt.
1731 static int validate_branch(struct objtool_file *file, struct instruction *first,
1732 struct insn_state state)
1734 struct alternative *alt;
1735 struct instruction *insn, *next_insn;
1736 struct section *sec;
1737 struct symbol *func = NULL;
1743 if (insn->alt_group && list_empty(&insn->alts)) {
1744 WARN_FUNC("don't know how to handle branch to middle of alternative instruction group",
1750 next_insn = next_insn_same_sec(file, insn);
1753 if (file->c_file && func && insn->func && func != insn->func) {
1754 WARN("%s() falls through to next function %s()",
1755 func->name, insn->func->name);
1762 if (func && insn->ignore) {
1763 WARN_FUNC("BUG: why am I validating an ignored function?",
1768 if (insn->visited) {
1769 if (!insn->hint && !insn_state_match(insn, &state))
1776 if (insn->restore) {
1777 struct instruction *save_insn, *i;
1781 func_for_each_insn_continue_reverse(file, func, i) {
1789 WARN_FUNC("no corresponding CFI save for CFI restore",
1794 if (!save_insn->visited) {
1796 * Oops, no state to copy yet.
1797 * Hopefully we can reach this
1798 * instruction from another branch
1799 * after the save insn has been
1805 WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
1810 insn->state = save_insn->state;
1813 state = insn->state;
1816 insn->state = state;
1818 insn->visited = true;
1820 if (!insn->ignore_alts) {
1821 list_for_each_entry(alt, &insn->alts, list) {
1822 ret = validate_branch(file, alt->insn, state);
1828 switch (insn->type) {
1831 if (func && has_modified_stack_frame(&state)) {
1832 WARN_FUNC("return with modified stack frame",
1837 if (state.bp_scratch) {
1838 WARN("%s uses BP as a scratch register",
1846 if (is_fentry_call(insn))
1849 ret = dead_end_function(file, insn->call_dest);
1856 case INSN_CALL_DYNAMIC:
1857 if (!no_fp && func && !has_valid_stack_frame(&state)) {
1858 WARN_FUNC("call without frame pointer save/setup",
1864 case INSN_JUMP_CONDITIONAL:
1865 case INSN_JUMP_UNCONDITIONAL:
1866 if (insn->jump_dest &&
1867 (!func || !insn->jump_dest->func ||
1868 func == insn->jump_dest->func)) {
1869 ret = validate_branch(file, insn->jump_dest,
1874 } else if (func && has_modified_stack_frame(&state)) {
1875 WARN_FUNC("sibling call from callable instruction with modified stack frame",
1880 if (insn->type == INSN_JUMP_UNCONDITIONAL)
1885 case INSN_JUMP_DYNAMIC:
1886 if (func && list_empty(&insn->alts) &&
1887 has_modified_stack_frame(&state)) {
1888 WARN_FUNC("sibling call from callable instruction with modified stack frame",
1895 case INSN_CONTEXT_SWITCH:
1896 if (func && (!next_insn || !next_insn->hint)) {
1897 WARN_FUNC("unsupported instruction in callable function",
1904 if (update_insn_state(insn, &state))
1917 if (state.cfa.base == CFI_UNDEFINED)
1919 WARN("%s: unexpected end of section", sec->name);
1929 static int validate_unwind_hints(struct objtool_file *file)
1931 struct instruction *insn;
1932 int ret, warnings = 0;
1933 struct insn_state state;
1938 clear_insn_state(&state);
1940 for_each_insn(file, insn) {
1941 if (insn->hint && !insn->visited) {
1942 ret = validate_branch(file, insn, state);
1950 static int validate_retpoline(struct objtool_file *file)
1952 struct instruction *insn;
1955 for_each_insn(file, insn) {
1956 if (insn->type != INSN_JUMP_DYNAMIC &&
1957 insn->type != INSN_CALL_DYNAMIC)
1960 if (insn->retpoline_safe)
1964 * .init.text code is ran before userspace and thus doesn't
1965 * strictly need retpolines, except for modules which are
1966 * loaded late, they very much do need retpoline in their
1969 if (!strcmp(insn->sec->name, ".init.text") && !module)
1972 WARN_FUNC("indirect %s found in RETPOLINE build",
1973 insn->sec, insn->offset,
1974 insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
1982 static bool is_kasan_insn(struct instruction *insn)
1984 return (insn->type == INSN_CALL &&
1985 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
1988 static bool is_ubsan_insn(struct instruction *insn)
1990 return (insn->type == INSN_CALL &&
1991 !strcmp(insn->call_dest->name,
1992 "__ubsan_handle_builtin_unreachable"));
1995 static bool ignore_unreachable_insn(struct instruction *insn)
1999 if (insn->ignore || insn->type == INSN_NOP)
2003 * Ignore any unused exceptions. This can happen when a whitelisted
2004 * function has an exception table entry.
2006 * Also ignore alternative replacement instructions. This can happen
2007 * when a whitelisted function uses one of the ALTERNATIVE macros.
2009 if (!strcmp(insn->sec->name, ".fixup") ||
2010 !strcmp(insn->sec->name, ".altinstr_replacement") ||
2011 !strcmp(insn->sec->name, ".altinstr_aux"))
2015 * Check if this (or a subsequent) instruction is related to
2016 * CONFIG_UBSAN or CONFIG_KASAN.
2018 * End the search at 5 instructions to avoid going into the weeds.
2022 for (i = 0; i < 5; i++) {
2024 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
2027 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
2028 if (insn->jump_dest &&
2029 insn->jump_dest->func == insn->func) {
2030 insn = insn->jump_dest;
2037 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
2040 insn = list_next_entry(insn, list);
2046 static int validate_functions(struct objtool_file *file)
2048 struct section *sec;
2049 struct symbol *func;
2050 struct instruction *insn;
2051 struct insn_state state;
2052 int ret, warnings = 0;
2054 clear_insn_state(&state);
2056 state.cfa = initial_func_cfi.cfa;
2057 memcpy(&state.regs, &initial_func_cfi.regs,
2058 CFI_NUM_REGS * sizeof(struct cfi_reg));
2059 state.stack_size = initial_func_cfi.cfa.offset;
2061 for_each_sec(file, sec) {
2062 list_for_each_entry(func, &sec->symbol_list, list) {
2063 if (func->type != STT_FUNC)
2066 insn = find_insn(file, sec, func->offset);
2067 if (!insn || insn->ignore)
2070 ret = validate_branch(file, insn, state);
2078 static int validate_reachable_instructions(struct objtool_file *file)
2080 struct instruction *insn;
2082 if (file->ignore_unreachables)
2085 for_each_insn(file, insn) {
2086 if (insn->visited || ignore_unreachable_insn(insn))
2089 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
2096 static void cleanup(struct objtool_file *file)
2098 struct instruction *insn, *tmpinsn;
2099 struct alternative *alt, *tmpalt;
2101 list_for_each_entry_safe(insn, tmpinsn, &file->insn_list, list) {
2102 list_for_each_entry_safe(alt, tmpalt, &insn->alts, list) {
2103 list_del(&alt->list);
2106 list_del(&insn->list);
2107 hash_del(&insn->hash);
2110 elf_close(file->elf);
2113 int check(const char *_objname, bool orc)
2115 struct objtool_file file;
2116 int ret, warnings = 0;
2120 file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY);
2124 INIT_LIST_HEAD(&file.insn_list);
2125 hash_init(file.insn_hash);
2126 file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard");
2127 file.rodata = find_section_by_name(file.elf, ".rodata");
2128 file.c_file = find_section_by_name(file.elf, ".comment");
2129 file.ignore_unreachables = no_unreachable;
2132 arch_initial_func_cfi_state(&initial_func_cfi);
2134 ret = decode_sections(&file);
2139 if (list_empty(&file.insn_list))
2143 ret = validate_retpoline(&file);
2149 ret = validate_functions(&file);
2154 ret = validate_unwind_hints(&file);
2160 ret = validate_reachable_instructions(&file);
2167 ret = create_orc(&file);
2171 ret = create_orc_sections(&file);
2175 ret = elf_write(file.elf);
2183 /* ignore warnings for now until we get all the code cleaned up */
2184 if (ret || warnings)