1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
12 #include <objtool/builtin.h>
13 #include <objtool/cfi.h>
14 #include <objtool/arch.h>
15 #include <objtool/check.h>
16 #include <objtool/special.h>
17 #include <objtool/warn.h>
18 #include <objtool/endianness.h>
20 #include <linux/objtool.h>
21 #include <linux/hashtable.h>
22 #include <linux/kernel.h>
23 #include <linux/static_call_types.h>
26 struct list_head list;
27 struct instruction *insn;
31 static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
33 static struct cfi_init_state initial_func_cfi;
34 static struct cfi_state init_cfi;
35 static struct cfi_state func_cfi;
37 struct instruction *find_insn(struct objtool_file *file,
38 struct section *sec, unsigned long offset)
40 struct instruction *insn;
42 hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
43 if (insn->sec == sec && insn->offset == offset)
50 static struct instruction *next_insn_same_sec(struct objtool_file *file,
51 struct instruction *insn)
53 struct instruction *next = list_next_entry(insn, list);
55 if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
61 static struct instruction *next_insn_same_func(struct objtool_file *file,
62 struct instruction *insn)
64 struct instruction *next = list_next_entry(insn, list);
65 struct symbol *func = insn->func;
70 if (&next->list != &file->insn_list && next->func == func)
73 /* Check if we're already in the subfunction: */
74 if (func == func->cfunc)
77 /* Move to the subfunction: */
78 return find_insn(file, func->cfunc->sec, func->cfunc->offset);
81 static struct instruction *prev_insn_same_sym(struct objtool_file *file,
82 struct instruction *insn)
84 struct instruction *prev = list_prev_entry(insn, list);
86 if (&prev->list != &file->insn_list && prev->func == insn->func)
92 #define func_for_each_insn(file, func, insn) \
93 for (insn = find_insn(file, func->sec, func->offset); \
95 insn = next_insn_same_func(file, insn))
97 #define sym_for_each_insn(file, sym, insn) \
98 for (insn = find_insn(file, sym->sec, sym->offset); \
99 insn && &insn->list != &file->insn_list && \
100 insn->sec == sym->sec && \
101 insn->offset < sym->offset + sym->len; \
102 insn = list_next_entry(insn, list))
104 #define sym_for_each_insn_continue_reverse(file, sym, insn) \
105 for (insn = list_prev_entry(insn, list); \
106 &insn->list != &file->insn_list && \
107 insn->sec == sym->sec && insn->offset >= sym->offset; \
108 insn = list_prev_entry(insn, list))
110 #define sec_for_each_insn_from(file, insn) \
111 for (; insn; insn = next_insn_same_sec(file, insn))
113 #define sec_for_each_insn_continue(file, insn) \
114 for (insn = next_insn_same_sec(file, insn); insn; \
115 insn = next_insn_same_sec(file, insn))
117 static bool is_jump_table_jump(struct instruction *insn)
119 struct alt_group *alt_group = insn->alt_group;
121 if (insn->jump_table)
124 /* Retpoline alternative for a jump table? */
125 return alt_group && alt_group->orig_group &&
126 alt_group->orig_group->first_insn->jump_table;
129 static bool is_sibling_call(struct instruction *insn)
132 * Assume only ELF functions can make sibling calls. This ensures
133 * sibling call detection consistency between vmlinux.o and individual
139 /* An indirect jump is either a sibling call or a jump to a table. */
140 if (insn->type == INSN_JUMP_DYNAMIC)
141 return !is_jump_table_jump(insn);
143 /* add_jump_destinations() sets insn->call_dest for sibling calls. */
144 return (is_static_jump(insn) && insn->call_dest);
148 * This checks to see if the given function is a "noreturn" function.
150 * For global functions which are outside the scope of this object file, we
151 * have to keep a manual list of them.
153 * For local functions, we have to detect them manually by simply looking for
154 * the lack of a return instruction.
156 static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
160 struct instruction *insn;
164 * Unfortunately these have to be hard coded because the noreturn
165 * attribute isn't provided in ELF data. Keep 'em sorted.
167 static const char * const global_noreturns[] = {
169 "__module_put_and_kthread_exit",
172 "__ubsan_handle_builtin_unreachable",
173 "cpu_bringup_and_idle",
178 "ex_handler_msr_mce",
180 "kthread_complete_and_exit",
182 "kunit_try_catch_throw",
184 "machine_real_restart",
187 "rewind_stack_and_make_dead",
198 if (func->bind == STB_WEAK)
201 if (func->bind == STB_GLOBAL)
202 for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
203 if (!strcmp(func->name, global_noreturns[i]))
209 insn = find_insn(file, func->sec, func->offset);
210 if (!insn || !insn->func)
213 func_for_each_insn(file, func, insn) {
216 if (insn->type == INSN_RETURN)
224 * A function can have a sibling call instead of a return. In that
225 * case, the function's dead-end status depends on whether the target
226 * of the sibling call returns.
228 func_for_each_insn(file, func, insn) {
229 if (is_sibling_call(insn)) {
230 struct instruction *dest = insn->jump_dest;
233 /* sibling call to another file */
236 /* local sibling call */
237 if (recursion == 5) {
239 * Infinite recursion: two functions have
240 * sibling calls to each other. This is a very
241 * rare case. It means they aren't dead ends.
246 return __dead_end_function(file, dest->func, recursion+1);
253 static bool dead_end_function(struct objtool_file *file, struct symbol *func)
255 return __dead_end_function(file, func, 0);
258 static void init_cfi_state(struct cfi_state *cfi)
262 for (i = 0; i < CFI_NUM_REGS; i++) {
263 cfi->regs[i].base = CFI_UNDEFINED;
264 cfi->vals[i].base = CFI_UNDEFINED;
266 cfi->cfa.base = CFI_UNDEFINED;
267 cfi->drap_reg = CFI_UNDEFINED;
268 cfi->drap_offset = -1;
271 static void init_insn_state(struct objtool_file *file, struct insn_state *state,
274 memset(state, 0, sizeof(*state));
275 init_cfi_state(&state->cfi);
278 * We need the full vmlinux for noinstr validation, otherwise we can
279 * not correctly determine insn->call_dest->sec (external symbols do
280 * not have a section).
282 if (opts.link && opts.noinstr && sec)
283 state->noinstr = sec->noinstr;
286 static struct cfi_state *cfi_alloc(void)
288 struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1);
290 WARN("calloc failed");
298 static struct hlist_head *cfi_hash;
300 static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2)
302 return memcmp((void *)cfi1 + sizeof(cfi1->hash),
303 (void *)cfi2 + sizeof(cfi2->hash),
304 sizeof(struct cfi_state) - sizeof(struct hlist_node));
307 static inline u32 cfi_key(struct cfi_state *cfi)
309 return jhash((void *)cfi + sizeof(cfi->hash),
310 sizeof(*cfi) - sizeof(cfi->hash), 0);
313 static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi)
315 struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
316 struct cfi_state *obj;
318 hlist_for_each_entry(obj, head, hash) {
319 if (!cficmp(cfi, obj)) {
327 hlist_add_head(&obj->hash, head);
332 static void cfi_hash_add(struct cfi_state *cfi)
334 struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
336 hlist_add_head(&cfi->hash, head);
339 static void *cfi_hash_alloc(unsigned long size)
341 cfi_bits = max(10, ilog2(size));
342 cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits,
343 PROT_READ|PROT_WRITE,
344 MAP_PRIVATE|MAP_ANON, -1, 0);
345 if (cfi_hash == (void *)-1L) {
346 WARN("mmap fail cfi_hash");
348 } else if (opts.stats) {
349 printf("cfi_bits: %d\n", cfi_bits);
355 static unsigned long nr_insns;
356 static unsigned long nr_insns_visited;
359 * Call the arch-specific instruction decoder for all the instructions and add
360 * them to the global instruction list.
362 static int decode_instructions(struct objtool_file *file)
366 unsigned long offset;
367 struct instruction *insn;
370 for_each_sec(file, sec) {
372 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
375 if (strcmp(sec->name, ".altinstr_replacement") &&
376 strcmp(sec->name, ".altinstr_aux") &&
377 strncmp(sec->name, ".discard.", 9))
380 if (!strcmp(sec->name, ".noinstr.text") ||
381 !strcmp(sec->name, ".entry.text") ||
382 !strncmp(sec->name, ".text.__x86.", 12))
385 for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
386 insn = malloc(sizeof(*insn));
388 WARN("malloc failed");
391 memset(insn, 0, sizeof(*insn));
392 INIT_LIST_HEAD(&insn->alts);
393 INIT_LIST_HEAD(&insn->stack_ops);
394 INIT_LIST_HEAD(&insn->call_node);
397 insn->offset = offset;
399 ret = arch_decode_instruction(file, sec, offset,
400 sec->sh.sh_size - offset,
401 &insn->len, &insn->type,
408 * By default, "ud2" is a dead end unless otherwise
409 * annotated, because GCC 7 inserts it for certain
410 * divide-by-zero cases.
412 if (insn->type == INSN_BUG)
413 insn->dead_end = true;
415 hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
416 list_add_tail(&insn->list, &file->insn_list);
420 list_for_each_entry(func, &sec->symbol_list, list) {
421 if (func->type != STT_FUNC || func->alias != func)
424 if (!find_insn(file, sec, func->offset)) {
425 WARN("%s(): can't find starting instruction",
430 sym_for_each_insn(file, func, insn) {
432 if (insn->type == INSN_ENDBR && list_empty(&insn->call_node)) {
433 if (insn->offset == insn->func->offset) {
434 list_add_tail(&insn->call_node, &file->endbr_list);
437 file->nr_endbr_int++;
445 printf("nr_insns: %lu\n", nr_insns);
455 * Read the pv_ops[] .data table to find the static initialized values.
457 static int add_pv_ops(struct objtool_file *file, const char *symname)
459 struct symbol *sym, *func;
460 unsigned long off, end;
464 sym = find_symbol_by_name(file->elf, symname);
469 end = off + sym->len;
471 rel = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off);
476 if (func->type == STT_SECTION)
477 func = find_symbol_by_offset(rel->sym->sec, rel->addend);
479 idx = (rel->offset - sym->offset) / sizeof(unsigned long);
481 objtool_pv_add(file, idx, func);
483 off = rel->offset + 1;
492 * Allocate and initialize file->pv_ops[].
494 static int init_pv_ops(struct objtool_file *file)
496 static const char *pv_ops_tables[] = {
512 sym = find_symbol_by_name(file->elf, "pv_ops");
516 nr = sym->len / sizeof(unsigned long);
517 file->pv_ops = calloc(sizeof(struct pv_state), nr);
521 for (idx = 0; idx < nr; idx++)
522 INIT_LIST_HEAD(&file->pv_ops[idx].targets);
524 for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++)
525 add_pv_ops(file, pv_ops);
530 static struct instruction *find_last_insn(struct objtool_file *file,
533 struct instruction *insn = NULL;
535 unsigned int end = (sec->sh.sh_size > 10) ? sec->sh.sh_size - 10 : 0;
537 for (offset = sec->sh.sh_size - 1; offset >= end && !insn; offset--)
538 insn = find_insn(file, sec, offset);
544 * Mark "ud2" instructions and manually annotated dead ends.
546 static int add_dead_ends(struct objtool_file *file)
550 struct instruction *insn;
553 * Check for manually annotated dead ends.
555 sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
559 list_for_each_entry(reloc, &sec->reloc_list, list) {
560 if (reloc->sym->type != STT_SECTION) {
561 WARN("unexpected relocation symbol type in %s", sec->name);
564 insn = find_insn(file, reloc->sym->sec, reloc->addend);
566 insn = list_prev_entry(insn, list);
567 else if (reloc->addend == reloc->sym->sec->sh.sh_size) {
568 insn = find_last_insn(file, reloc->sym->sec);
570 WARN("can't find unreachable insn at %s+0x%" PRIx64,
571 reloc->sym->sec->name, reloc->addend);
575 WARN("can't find unreachable insn at %s+0x%" PRIx64,
576 reloc->sym->sec->name, reloc->addend);
580 insn->dead_end = true;
585 * These manually annotated reachable checks are needed for GCC 4.4,
586 * where the Linux unreachable() macro isn't supported. In that case
587 * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
590 sec = find_section_by_name(file->elf, ".rela.discard.reachable");
594 list_for_each_entry(reloc, &sec->reloc_list, list) {
595 if (reloc->sym->type != STT_SECTION) {
596 WARN("unexpected relocation symbol type in %s", sec->name);
599 insn = find_insn(file, reloc->sym->sec, reloc->addend);
601 insn = list_prev_entry(insn, list);
602 else if (reloc->addend == reloc->sym->sec->sh.sh_size) {
603 insn = find_last_insn(file, reloc->sym->sec);
605 WARN("can't find reachable insn at %s+0x%" PRIx64,
606 reloc->sym->sec->name, reloc->addend);
610 WARN("can't find reachable insn at %s+0x%" PRIx64,
611 reloc->sym->sec->name, reloc->addend);
615 insn->dead_end = false;
621 static int create_static_call_sections(struct objtool_file *file)
624 struct static_call_site *site;
625 struct instruction *insn;
626 struct symbol *key_sym;
627 char *key_name, *tmp;
630 sec = find_section_by_name(file->elf, ".static_call_sites");
632 INIT_LIST_HEAD(&file->static_call_list);
633 WARN("file already has .static_call_sites section, skipping");
637 if (list_empty(&file->static_call_list))
641 list_for_each_entry(insn, &file->static_call_list, call_node)
644 sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
645 sizeof(struct static_call_site), idx);
650 list_for_each_entry(insn, &file->static_call_list, call_node) {
652 site = (struct static_call_site *)sec->data->d_buf + idx;
653 memset(site, 0, sizeof(struct static_call_site));
655 /* populate reloc for 'addr' */
656 if (elf_add_reloc_to_insn(file->elf, sec,
657 idx * sizeof(struct static_call_site),
659 insn->sec, insn->offset))
662 /* find key symbol */
663 key_name = strdup(insn->call_dest->name);
668 if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
669 STATIC_CALL_TRAMP_PREFIX_LEN)) {
670 WARN("static_call: trampoline name malformed: %s", key_name);
674 tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
675 memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
677 key_sym = find_symbol_by_name(file->elf, tmp);
680 WARN("static_call: can't find static_call_key symbol: %s", tmp);
686 * For modules(), the key might not be exported, which
687 * means the module can make static calls but isn't
688 * allowed to change them.
690 * In that case we temporarily set the key to be the
691 * trampoline address. This is fixed up in
692 * static_call_add_module().
694 key_sym = insn->call_dest;
698 /* populate reloc for 'key' */
699 if (elf_add_reloc(file->elf, sec,
700 idx * sizeof(struct static_call_site) + 4,
701 R_X86_64_PC32, key_sym,
702 is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
711 static int create_retpoline_sites_sections(struct objtool_file *file)
713 struct instruction *insn;
717 sec = find_section_by_name(file->elf, ".retpoline_sites");
719 WARN("file already has .retpoline_sites, skipping");
724 list_for_each_entry(insn, &file->retpoline_call_list, call_node)
730 sec = elf_create_section(file->elf, ".retpoline_sites", 0,
733 WARN("elf_create_section: .retpoline_sites");
738 list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
740 int *site = (int *)sec->data->d_buf + idx;
743 if (elf_add_reloc_to_insn(file->elf, sec,
746 insn->sec, insn->offset)) {
747 WARN("elf_add_reloc_to_insn: .retpoline_sites");
757 static int create_return_sites_sections(struct objtool_file *file)
759 struct instruction *insn;
763 sec = find_section_by_name(file->elf, ".return_sites");
765 WARN("file already has .return_sites, skipping");
770 list_for_each_entry(insn, &file->return_thunk_list, call_node)
776 sec = elf_create_section(file->elf, ".return_sites", 0,
779 WARN("elf_create_section: .return_sites");
784 list_for_each_entry(insn, &file->return_thunk_list, call_node) {
786 int *site = (int *)sec->data->d_buf + idx;
789 if (elf_add_reloc_to_insn(file->elf, sec,
792 insn->sec, insn->offset)) {
793 WARN("elf_add_reloc_to_insn: .return_sites");
803 static int create_ibt_endbr_seal_sections(struct objtool_file *file)
805 struct instruction *insn;
809 sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
811 WARN("file already has .ibt_endbr_seal, skipping");
816 list_for_each_entry(insn, &file->endbr_list, call_node)
820 printf("ibt: ENDBR at function start: %d\n", file->nr_endbr);
821 printf("ibt: ENDBR inside functions: %d\n", file->nr_endbr_int);
822 printf("ibt: superfluous ENDBR: %d\n", idx);
828 sec = elf_create_section(file->elf, ".ibt_endbr_seal", 0,
831 WARN("elf_create_section: .ibt_endbr_seal");
836 list_for_each_entry(insn, &file->endbr_list, call_node) {
838 int *site = (int *)sec->data->d_buf + idx;
841 if (elf_add_reloc_to_insn(file->elf, sec,
844 insn->sec, insn->offset)) {
845 WARN("elf_add_reloc_to_insn: .ibt_endbr_seal");
855 static int create_mcount_loc_sections(struct objtool_file *file)
859 struct instruction *insn;
862 sec = find_section_by_name(file->elf, "__mcount_loc");
864 INIT_LIST_HEAD(&file->mcount_loc_list);
865 WARN("file already has __mcount_loc section, skipping");
869 if (list_empty(&file->mcount_loc_list))
873 list_for_each_entry(insn, &file->mcount_loc_list, call_node)
876 sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx);
881 list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
883 loc = (unsigned long *)sec->data->d_buf + idx;
884 memset(loc, 0, sizeof(unsigned long));
886 if (elf_add_reloc_to_insn(file->elf, sec,
887 idx * sizeof(unsigned long),
889 insn->sec, insn->offset))
899 * Warnings shouldn't be reported for ignored functions.
901 static void add_ignores(struct objtool_file *file)
903 struct instruction *insn;
908 sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
912 list_for_each_entry(reloc, &sec->reloc_list, list) {
913 switch (reloc->sym->type) {
919 func = find_func_by_offset(reloc->sym->sec, reloc->addend);
925 WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type);
929 func_for_each_insn(file, func, insn)
935 * This is a whitelist of functions that is allowed to be called with AC set.
936 * The list is meant to be minimal and only contains compiler instrumentation
937 * ABI and a few functions used to implement *_{to,from}_user() functions.
939 * These functions must not directly change AC, but may PUSHF/POPF.
941 static const char *uaccess_safe_builtin[] = {
945 /* KASAN out-of-line */
946 "__asan_loadN_noabort",
947 "__asan_load1_noabort",
948 "__asan_load2_noabort",
949 "__asan_load4_noabort",
950 "__asan_load8_noabort",
951 "__asan_load16_noabort",
952 "__asan_storeN_noabort",
953 "__asan_store1_noabort",
954 "__asan_store2_noabort",
955 "__asan_store4_noabort",
956 "__asan_store8_noabort",
957 "__asan_store16_noabort",
958 "__kasan_check_read",
959 "__kasan_check_write",
961 "__asan_report_load_n_noabort",
962 "__asan_report_load1_noabort",
963 "__asan_report_load2_noabort",
964 "__asan_report_load4_noabort",
965 "__asan_report_load8_noabort",
966 "__asan_report_load16_noabort",
967 "__asan_report_store_n_noabort",
968 "__asan_report_store1_noabort",
969 "__asan_report_store2_noabort",
970 "__asan_report_store4_noabort",
971 "__asan_report_store8_noabort",
972 "__asan_report_store16_noabort",
974 "__kcsan_check_access",
979 "kcsan_found_watchpoint",
980 "kcsan_setup_watchpoint",
981 "kcsan_check_scoped_accesses",
982 "kcsan_disable_current",
983 "kcsan_enable_current_nowarn",
988 "__tsan_write_range",
999 "__tsan_read_write1",
1000 "__tsan_read_write2",
1001 "__tsan_read_write4",
1002 "__tsan_read_write8",
1003 "__tsan_read_write16",
1004 "__tsan_volatile_read1",
1005 "__tsan_volatile_read2",
1006 "__tsan_volatile_read4",
1007 "__tsan_volatile_read8",
1008 "__tsan_volatile_read16",
1009 "__tsan_volatile_write1",
1010 "__tsan_volatile_write2",
1011 "__tsan_volatile_write4",
1012 "__tsan_volatile_write8",
1013 "__tsan_volatile_write16",
1014 "__tsan_atomic8_load",
1015 "__tsan_atomic16_load",
1016 "__tsan_atomic32_load",
1017 "__tsan_atomic64_load",
1018 "__tsan_atomic8_store",
1019 "__tsan_atomic16_store",
1020 "__tsan_atomic32_store",
1021 "__tsan_atomic64_store",
1022 "__tsan_atomic8_exchange",
1023 "__tsan_atomic16_exchange",
1024 "__tsan_atomic32_exchange",
1025 "__tsan_atomic64_exchange",
1026 "__tsan_atomic8_fetch_add",
1027 "__tsan_atomic16_fetch_add",
1028 "__tsan_atomic32_fetch_add",
1029 "__tsan_atomic64_fetch_add",
1030 "__tsan_atomic8_fetch_sub",
1031 "__tsan_atomic16_fetch_sub",
1032 "__tsan_atomic32_fetch_sub",
1033 "__tsan_atomic64_fetch_sub",
1034 "__tsan_atomic8_fetch_and",
1035 "__tsan_atomic16_fetch_and",
1036 "__tsan_atomic32_fetch_and",
1037 "__tsan_atomic64_fetch_and",
1038 "__tsan_atomic8_fetch_or",
1039 "__tsan_atomic16_fetch_or",
1040 "__tsan_atomic32_fetch_or",
1041 "__tsan_atomic64_fetch_or",
1042 "__tsan_atomic8_fetch_xor",
1043 "__tsan_atomic16_fetch_xor",
1044 "__tsan_atomic32_fetch_xor",
1045 "__tsan_atomic64_fetch_xor",
1046 "__tsan_atomic8_fetch_nand",
1047 "__tsan_atomic16_fetch_nand",
1048 "__tsan_atomic32_fetch_nand",
1049 "__tsan_atomic64_fetch_nand",
1050 "__tsan_atomic8_compare_exchange_strong",
1051 "__tsan_atomic16_compare_exchange_strong",
1052 "__tsan_atomic32_compare_exchange_strong",
1053 "__tsan_atomic64_compare_exchange_strong",
1054 "__tsan_atomic8_compare_exchange_weak",
1055 "__tsan_atomic16_compare_exchange_weak",
1056 "__tsan_atomic32_compare_exchange_weak",
1057 "__tsan_atomic64_compare_exchange_weak",
1058 "__tsan_atomic8_compare_exchange_val",
1059 "__tsan_atomic16_compare_exchange_val",
1060 "__tsan_atomic32_compare_exchange_val",
1061 "__tsan_atomic64_compare_exchange_val",
1062 "__tsan_atomic_thread_fence",
1063 "__tsan_atomic_signal_fence",
1064 "__tsan_unaligned_read16",
1065 "__tsan_unaligned_write16",
1069 "__sanitizer_cov_trace_pc",
1070 "__sanitizer_cov_trace_const_cmp1",
1071 "__sanitizer_cov_trace_const_cmp2",
1072 "__sanitizer_cov_trace_const_cmp4",
1073 "__sanitizer_cov_trace_const_cmp8",
1074 "__sanitizer_cov_trace_cmp1",
1075 "__sanitizer_cov_trace_cmp2",
1076 "__sanitizer_cov_trace_cmp4",
1077 "__sanitizer_cov_trace_cmp8",
1078 "__sanitizer_cov_trace_switch",
1080 "kmsan_copy_to_user",
1082 "kmsan_unpoison_entry_regs",
1083 "kmsan_unpoison_memory",
1084 "__msan_chain_origin",
1085 "__msan_get_context_state",
1086 "__msan_instrument_asm_store",
1087 "__msan_metadata_ptr_for_load_1",
1088 "__msan_metadata_ptr_for_load_2",
1089 "__msan_metadata_ptr_for_load_4",
1090 "__msan_metadata_ptr_for_load_8",
1091 "__msan_metadata_ptr_for_load_n",
1092 "__msan_metadata_ptr_for_store_1",
1093 "__msan_metadata_ptr_for_store_2",
1094 "__msan_metadata_ptr_for_store_4",
1095 "__msan_metadata_ptr_for_store_8",
1096 "__msan_metadata_ptr_for_store_n",
1097 "__msan_poison_alloca",
1100 "ubsan_type_mismatch_common",
1101 "__ubsan_handle_type_mismatch",
1102 "__ubsan_handle_type_mismatch_v1",
1103 "__ubsan_handle_shift_out_of_bounds",
1105 "csum_partial_copy_generic",
1107 "copy_mc_fragile_handle_tail",
1108 "copy_mc_enhanced_fast_string",
1109 "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
1111 "clear_user_rep_good",
1112 "clear_user_original",
1116 static void add_uaccess_safe(struct objtool_file *file)
1118 struct symbol *func;
1124 for (name = uaccess_safe_builtin; *name; name++) {
1125 func = find_symbol_by_name(file->elf, *name);
1129 func->uaccess_safe = true;
1134 * FIXME: For now, just ignore any alternatives which add retpolines. This is
1135 * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
1136 * But it at least allows objtool to understand the control flow *around* the
1139 static int add_ignore_alternatives(struct objtool_file *file)
1141 struct section *sec;
1142 struct reloc *reloc;
1143 struct instruction *insn;
1145 sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
1149 list_for_each_entry(reloc, &sec->reloc_list, list) {
1150 if (reloc->sym->type != STT_SECTION) {
1151 WARN("unexpected relocation symbol type in %s", sec->name);
1155 insn = find_insn(file, reloc->sym->sec, reloc->addend);
1157 WARN("bad .discard.ignore_alts entry");
1161 insn->ignore_alts = true;
1167 __weak bool arch_is_retpoline(struct symbol *sym)
1172 __weak bool arch_is_rethunk(struct symbol *sym)
1177 #define NEGATIVE_RELOC ((void *)-1L)
1179 static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
1181 if (insn->reloc == NEGATIVE_RELOC)
1188 insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
1189 insn->offset, insn->len);
1191 insn->reloc = NEGATIVE_RELOC;
1199 static void remove_insn_ops(struct instruction *insn)
1201 struct stack_op *op, *tmp;
1203 list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
1204 list_del(&op->list);
1209 static void annotate_call_site(struct objtool_file *file,
1210 struct instruction *insn, bool sibling)
1212 struct reloc *reloc = insn_reloc(file, insn);
1213 struct symbol *sym = insn->call_dest;
1219 * Alternative replacement code is just template code which is
1220 * sometimes copied to the original instruction. For now, don't
1221 * annotate it. (In the future we might consider annotating the
1222 * original instruction if/when it ever makes sense to do so.)
1224 if (!strcmp(insn->sec->name, ".altinstr_replacement"))
1227 if (sym->static_call_tramp) {
1228 list_add_tail(&insn->call_node, &file->static_call_list);
1232 if (sym->retpoline_thunk) {
1233 list_add_tail(&insn->call_node, &file->retpoline_call_list);
1238 * Many compilers cannot disable KCOV or sanitizer calls with a function
1239 * attribute so they need a little help, NOP out any such calls from
1242 if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
1244 reloc->type = R_NONE;
1245 elf_write_reloc(file->elf, reloc);
1248 elf_write_insn(file->elf, insn->sec,
1249 insn->offset, insn->len,
1250 sibling ? arch_ret_insn(insn->len)
1251 : arch_nop_insn(insn->len));
1253 insn->type = sibling ? INSN_RETURN : INSN_NOP;
1257 * We've replaced the tail-call JMP insn by two new
1258 * insn: RET; INT3, except we only have a single struct
1259 * insn here. Mark it retpoline_safe to avoid the SLS
1260 * warning, instead of adding another insn.
1262 insn->retpoline_safe = true;
1268 if (opts.mcount && sym->fentry) {
1270 WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset);
1273 reloc->type = R_NONE;
1274 elf_write_reloc(file->elf, reloc);
1277 elf_write_insn(file->elf, insn->sec,
1278 insn->offset, insn->len,
1279 arch_nop_insn(insn->len));
1281 insn->type = INSN_NOP;
1283 list_add_tail(&insn->call_node, &file->mcount_loc_list);
1287 if (!sibling && dead_end_function(file, sym))
1288 insn->dead_end = true;
1291 static void add_call_dest(struct objtool_file *file, struct instruction *insn,
1292 struct symbol *dest, bool sibling)
1294 insn->call_dest = dest;
1299 * Whatever stack impact regular CALLs have, should be undone
1300 * by the RETURN of the called function.
1302 * Annotated intra-function calls retain the stack_ops but
1303 * are converted to JUMP, see read_intra_function_calls().
1305 remove_insn_ops(insn);
1307 annotate_call_site(file, insn, sibling);
1310 static void add_retpoline_call(struct objtool_file *file, struct instruction *insn)
1313 * Retpoline calls/jumps are really dynamic calls/jumps in disguise,
1314 * so convert them accordingly.
1316 switch (insn->type) {
1318 insn->type = INSN_CALL_DYNAMIC;
1320 case INSN_JUMP_UNCONDITIONAL:
1321 insn->type = INSN_JUMP_DYNAMIC;
1323 case INSN_JUMP_CONDITIONAL:
1324 insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
1330 insn->retpoline_safe = true;
1333 * Whatever stack impact regular CALLs have, should be undone
1334 * by the RETURN of the called function.
1336 * Annotated intra-function calls retain the stack_ops but
1337 * are converted to JUMP, see read_intra_function_calls().
1339 remove_insn_ops(insn);
1341 annotate_call_site(file, insn, false);
1344 static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
1347 * Return thunk tail calls are really just returns in disguise,
1348 * so convert them accordingly.
1350 insn->type = INSN_RETURN;
1351 insn->retpoline_safe = true;
1354 list_add_tail(&insn->call_node, &file->return_thunk_list);
1357 static bool same_function(struct instruction *insn1, struct instruction *insn2)
1359 return insn1->func->pfunc == insn2->func->pfunc;
1362 static bool is_first_func_insn(struct objtool_file *file, struct instruction *insn)
1364 if (insn->offset == insn->func->offset)
1368 struct instruction *prev = prev_insn_same_sym(file, insn);
1370 if (prev && prev->type == INSN_ENDBR &&
1371 insn->offset == insn->func->offset + prev->len)
1379 * Find the destination instructions for all jumps.
1381 static int add_jump_destinations(struct objtool_file *file)
1383 struct instruction *insn, *jump_dest;
1384 struct reloc *reloc;
1385 struct section *dest_sec;
1386 unsigned long dest_off;
1388 for_each_insn(file, insn) {
1389 if (insn->jump_dest) {
1391 * handle_group_alt() may have previously set
1392 * 'jump_dest' for some alternatives.
1396 if (!is_static_jump(insn))
1399 reloc = insn_reloc(file, insn);
1401 dest_sec = insn->sec;
1402 dest_off = arch_jump_destination(insn);
1403 } else if (reloc->sym->type == STT_SECTION) {
1404 dest_sec = reloc->sym->sec;
1405 dest_off = arch_dest_reloc_offset(reloc->addend);
1406 } else if (reloc->sym->retpoline_thunk) {
1407 add_retpoline_call(file, insn);
1409 } else if (reloc->sym->return_thunk) {
1410 add_return_call(file, insn, true);
1412 } else if (insn->func) {
1414 * External sibling call or internal sibling call with
1417 add_call_dest(file, insn, reloc->sym, true);
1419 } else if (reloc->sym->sec->idx) {
1420 dest_sec = reloc->sym->sec;
1421 dest_off = reloc->sym->sym.st_value +
1422 arch_dest_reloc_offset(reloc->addend);
1424 /* non-func asm code jumping to another file */
1428 jump_dest = find_insn(file, dest_sec, dest_off);
1430 struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
1433 * This is a special case for zen_untrain_ret().
1434 * It jumps to __x86_return_thunk(), but objtool
1435 * can't find the thunk's starting RET
1436 * instruction, because the RET is also in the
1437 * middle of another instruction. Objtool only
1438 * knows about the outer instruction.
1440 if (sym && sym->return_thunk) {
1441 add_return_call(file, insn, false);
1445 WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
1446 insn->sec, insn->offset, dest_sec->name,
1452 * Cross-function jump.
1454 if (insn->func && jump_dest->func &&
1455 insn->func != jump_dest->func) {
1458 * For GCC 8+, create parent/child links for any cold
1459 * subfunctions. This is _mostly_ redundant with a
1460 * similar initialization in read_symbols().
1462 * If a function has aliases, we want the *first* such
1463 * function in the symbol table to be the subfunction's
1464 * parent. In that case we overwrite the
1465 * initialization done in read_symbols().
1467 * However this code can't completely replace the
1468 * read_symbols() code because this doesn't detect the
1469 * case where the parent function's only reference to a
1470 * subfunction is through a jump table.
1472 if (!strstr(insn->func->name, ".cold") &&
1473 strstr(jump_dest->func->name, ".cold")) {
1474 insn->func->cfunc = jump_dest->func;
1475 jump_dest->func->pfunc = insn->func;
1477 } else if (!same_function(insn, jump_dest) &&
1478 is_first_func_insn(file, jump_dest)) {
1480 * Internal sibling call without reloc or with
1481 * STT_SECTION reloc.
1483 add_call_dest(file, insn, jump_dest->func, true);
1488 insn->jump_dest = jump_dest;
1494 static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
1496 struct symbol *call_dest;
1498 call_dest = find_func_by_offset(sec, offset);
1500 call_dest = find_symbol_by_offset(sec, offset);
1506 * Find the destination instructions for all calls.
1508 static int add_call_destinations(struct objtool_file *file)
1510 struct instruction *insn;
1511 unsigned long dest_off;
1512 struct symbol *dest;
1513 struct reloc *reloc;
1515 for_each_insn(file, insn) {
1516 if (insn->type != INSN_CALL)
1519 reloc = insn_reloc(file, insn);
1521 dest_off = arch_jump_destination(insn);
1522 dest = find_call_destination(insn->sec, dest_off);
1524 add_call_dest(file, insn, dest, false);
1529 if (!insn->call_dest) {
1530 WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);
1534 if (insn->func && insn->call_dest->type != STT_FUNC) {
1535 WARN_FUNC("unsupported call to non-function",
1536 insn->sec, insn->offset);
1540 } else if (reloc->sym->type == STT_SECTION) {
1541 dest_off = arch_dest_reloc_offset(reloc->addend);
1542 dest = find_call_destination(reloc->sym->sec, dest_off);
1544 WARN_FUNC("can't find call dest symbol at %s+0x%lx",
1545 insn->sec, insn->offset,
1546 reloc->sym->sec->name,
1551 add_call_dest(file, insn, dest, false);
1553 } else if (reloc->sym->retpoline_thunk) {
1554 add_retpoline_call(file, insn);
1557 add_call_dest(file, insn, reloc->sym, false);
1564 * The .alternatives section requires some extra special care over and above
1565 * other special sections because alternatives are patched in place.
1567 static int handle_group_alt(struct objtool_file *file,
1568 struct special_alt *special_alt,
1569 struct instruction *orig_insn,
1570 struct instruction **new_insn)
1572 struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL;
1573 struct alt_group *orig_alt_group, *new_alt_group;
1574 unsigned long dest_off;
1577 orig_alt_group = malloc(sizeof(*orig_alt_group));
1578 if (!orig_alt_group) {
1579 WARN("malloc failed");
1582 orig_alt_group->cfi = calloc(special_alt->orig_len,
1583 sizeof(struct cfi_state *));
1584 if (!orig_alt_group->cfi) {
1585 WARN("calloc failed");
1589 last_orig_insn = NULL;
1591 sec_for_each_insn_from(file, insn) {
1592 if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
1595 insn->alt_group = orig_alt_group;
1596 last_orig_insn = insn;
1598 orig_alt_group->orig_group = NULL;
1599 orig_alt_group->first_insn = orig_insn;
1600 orig_alt_group->last_insn = last_orig_insn;
1603 new_alt_group = malloc(sizeof(*new_alt_group));
1604 if (!new_alt_group) {
1605 WARN("malloc failed");
1609 if (special_alt->new_len < special_alt->orig_len) {
1611 * Insert a fake nop at the end to make the replacement
1612 * alt_group the same size as the original. This is needed to
1613 * allow propagate_alt_cfi() to do its magic. When the last
1614 * instruction affects the stack, the instruction after it (the
1615 * nop) will propagate the new state to the shared CFI array.
1617 nop = malloc(sizeof(*nop));
1619 WARN("malloc failed");
1622 memset(nop, 0, sizeof(*nop));
1623 INIT_LIST_HEAD(&nop->alts);
1624 INIT_LIST_HEAD(&nop->stack_ops);
1626 nop->sec = special_alt->new_sec;
1627 nop->offset = special_alt->new_off + special_alt->new_len;
1628 nop->len = special_alt->orig_len - special_alt->new_len;
1629 nop->type = INSN_NOP;
1630 nop->func = orig_insn->func;
1631 nop->alt_group = new_alt_group;
1632 nop->ignore = orig_insn->ignore_alts;
1635 if (!special_alt->new_len) {
1641 sec_for_each_insn_from(file, insn) {
1642 struct reloc *alt_reloc;
1644 if (insn->offset >= special_alt->new_off + special_alt->new_len)
1647 last_new_insn = insn;
1649 insn->ignore = orig_insn->ignore_alts;
1650 insn->func = orig_insn->func;
1651 insn->alt_group = new_alt_group;
1654 * Since alternative replacement code is copy/pasted by the
1655 * kernel after applying relocations, generally such code can't
1656 * have relative-address relocation references to outside the
1657 * .altinstr_replacement section, unless the arch's
1658 * alternatives code can adjust the relative offsets
1661 alt_reloc = insn_reloc(file, insn);
1663 !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
1665 WARN_FUNC("unsupported relocation in alternatives section",
1666 insn->sec, insn->offset);
1670 if (!is_static_jump(insn))
1673 if (!insn->immediate)
1676 dest_off = arch_jump_destination(insn);
1677 if (dest_off == special_alt->new_off + special_alt->new_len) {
1678 insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
1679 if (!insn->jump_dest) {
1680 WARN_FUNC("can't find alternative jump destination",
1681 insn->sec, insn->offset);
1687 if (!last_new_insn) {
1688 WARN_FUNC("can't find last new alternative instruction",
1689 special_alt->new_sec, special_alt->new_off);
1694 list_add(&nop->list, &last_new_insn->list);
1696 new_alt_group->orig_group = orig_alt_group;
1697 new_alt_group->first_insn = *new_insn;
1698 new_alt_group->last_insn = nop ? : last_new_insn;
1699 new_alt_group->cfi = orig_alt_group->cfi;
1704 * A jump table entry can either convert a nop to a jump or a jump to a nop.
1705 * If the original instruction is a jump, make the alt entry an effective nop
1706 * by just skipping the original instruction.
1708 static int handle_jump_alt(struct objtool_file *file,
1709 struct special_alt *special_alt,
1710 struct instruction *orig_insn,
1711 struct instruction **new_insn)
1713 if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
1714 orig_insn->type != INSN_NOP) {
1716 WARN_FUNC("unsupported instruction at jump label",
1717 orig_insn->sec, orig_insn->offset);
1721 if (opts.hack_jump_label && special_alt->key_addend & 2) {
1722 struct reloc *reloc = insn_reloc(file, orig_insn);
1725 reloc->type = R_NONE;
1726 elf_write_reloc(file->elf, reloc);
1728 elf_write_insn(file->elf, orig_insn->sec,
1729 orig_insn->offset, orig_insn->len,
1730 arch_nop_insn(orig_insn->len));
1731 orig_insn->type = INSN_NOP;
1734 if (orig_insn->type == INSN_NOP) {
1735 if (orig_insn->len == 2)
1736 file->jl_nop_short++;
1738 file->jl_nop_long++;
1743 if (orig_insn->len == 2)
1748 *new_insn = list_next_entry(orig_insn, list);
1753 * Read all the special sections which have alternate instructions which can be
1754 * patched in or redirected to at runtime. Each instruction having alternate
1755 * instruction(s) has them added to its insn->alts list, which will be
1756 * traversed in validate_branch().
1758 static int add_special_section_alts(struct objtool_file *file)
1760 struct list_head special_alts;
1761 struct instruction *orig_insn, *new_insn;
1762 struct special_alt *special_alt, *tmp;
1763 struct alternative *alt;
1766 ret = special_get_alts(file->elf, &special_alts);
1770 list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
1772 orig_insn = find_insn(file, special_alt->orig_sec,
1773 special_alt->orig_off);
1775 WARN_FUNC("special: can't find orig instruction",
1776 special_alt->orig_sec, special_alt->orig_off);
1782 if (!special_alt->group || special_alt->new_len) {
1783 new_insn = find_insn(file, special_alt->new_sec,
1784 special_alt->new_off);
1786 WARN_FUNC("special: can't find new instruction",
1787 special_alt->new_sec,
1788 special_alt->new_off);
1794 if (special_alt->group) {
1795 if (!special_alt->orig_len) {
1796 WARN_FUNC("empty alternative entry",
1797 orig_insn->sec, orig_insn->offset);
1801 ret = handle_group_alt(file, special_alt, orig_insn,
1805 } else if (special_alt->jump_or_nop) {
1806 ret = handle_jump_alt(file, special_alt, orig_insn,
1812 alt = malloc(sizeof(*alt));
1814 WARN("malloc failed");
1819 alt->insn = new_insn;
1820 alt->skip_orig = special_alt->skip_orig;
1821 orig_insn->ignore_alts |= special_alt->skip_alt;
1822 list_add_tail(&alt->list, &orig_insn->alts);
1824 list_del(&special_alt->list);
1829 printf("jl\\\tNOP\tJMP\n");
1830 printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
1831 printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
1838 static int add_jump_table(struct objtool_file *file, struct instruction *insn,
1839 struct reloc *table)
1841 struct reloc *reloc = table;
1842 struct instruction *dest_insn;
1843 struct alternative *alt;
1844 struct symbol *pfunc = insn->func->pfunc;
1845 unsigned int prev_offset = 0;
1848 * Each @reloc is a switch table relocation which points to the target
1851 list_for_each_entry_from(reloc, &table->sec->reloc_list, list) {
1853 /* Check for the end of the table: */
1854 if (reloc != table && reloc->jump_table_start)
1857 /* Make sure the table entries are consecutive: */
1858 if (prev_offset && reloc->offset != prev_offset + 8)
1861 /* Detect function pointers from contiguous objects: */
1862 if (reloc->sym->sec == pfunc->sec &&
1863 reloc->addend == pfunc->offset)
1866 dest_insn = find_insn(file, reloc->sym->sec, reloc->addend);
1870 /* Make sure the destination is in the same function: */
1871 if (!dest_insn->func || dest_insn->func->pfunc != pfunc)
1874 alt = malloc(sizeof(*alt));
1876 WARN("malloc failed");
1880 alt->insn = dest_insn;
1881 list_add_tail(&alt->list, &insn->alts);
1882 prev_offset = reloc->offset;
1886 WARN_FUNC("can't find switch jump table",
1887 insn->sec, insn->offset);
1895 * find_jump_table() - Given a dynamic jump, find the switch jump table
1896 * associated with it.
1898 static struct reloc *find_jump_table(struct objtool_file *file,
1899 struct symbol *func,
1900 struct instruction *insn)
1902 struct reloc *table_reloc;
1903 struct instruction *dest_insn, *orig_insn = insn;
1906 * Backward search using the @first_jump_src links, these help avoid
1907 * much of the 'in between' code. Which avoids us getting confused by
1911 insn && insn->func && insn->func->pfunc == func;
1912 insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
1914 if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
1917 /* allow small jumps within the range */
1918 if (insn->type == INSN_JUMP_UNCONDITIONAL &&
1920 (insn->jump_dest->offset <= insn->offset ||
1921 insn->jump_dest->offset > orig_insn->offset))
1924 table_reloc = arch_find_switch_table(file, insn);
1927 dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
1928 if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
1938 * First pass: Mark the head of each jump table so that in the next pass,
1939 * we know when a given jump table ends and the next one starts.
1941 static void mark_func_jump_tables(struct objtool_file *file,
1942 struct symbol *func)
1944 struct instruction *insn, *last = NULL;
1945 struct reloc *reloc;
1947 func_for_each_insn(file, func, insn) {
1952 * Store back-pointers for unconditional forward jumps such
1953 * that find_jump_table() can back-track using those and
1954 * avoid some potentially confusing code.
1956 if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
1957 insn->offset > last->offset &&
1958 insn->jump_dest->offset > insn->offset &&
1959 !insn->jump_dest->first_jump_src) {
1961 insn->jump_dest->first_jump_src = insn;
1962 last = insn->jump_dest;
1965 if (insn->type != INSN_JUMP_DYNAMIC)
1968 reloc = find_jump_table(file, func, insn);
1970 reloc->jump_table_start = true;
1971 insn->jump_table = reloc;
1976 static int add_func_jump_tables(struct objtool_file *file,
1977 struct symbol *func)
1979 struct instruction *insn;
1982 func_for_each_insn(file, func, insn) {
1983 if (!insn->jump_table)
1986 ret = add_jump_table(file, insn, insn->jump_table);
1995 * For some switch statements, gcc generates a jump table in the .rodata
1996 * section which contains a list of addresses within the function to jump to.
1997 * This finds these jump tables and adds them to the insn->alts lists.
1999 static int add_jump_table_alts(struct objtool_file *file)
2001 struct section *sec;
2002 struct symbol *func;
2008 for_each_sec(file, sec) {
2009 list_for_each_entry(func, &sec->symbol_list, list) {
2010 if (func->type != STT_FUNC)
2013 mark_func_jump_tables(file, func);
2014 ret = add_func_jump_tables(file, func);
2023 static void set_func_state(struct cfi_state *state)
2025 state->cfa = initial_func_cfi.cfa;
2026 memcpy(&state->regs, &initial_func_cfi.regs,
2027 CFI_NUM_REGS * sizeof(struct cfi_reg));
2028 state->stack_size = initial_func_cfi.cfa.offset;
2031 static int read_unwind_hints(struct objtool_file *file)
2033 struct cfi_state cfi = init_cfi;
2034 struct section *sec, *relocsec;
2035 struct unwind_hint *hint;
2036 struct instruction *insn;
2037 struct reloc *reloc;
2040 sec = find_section_by_name(file->elf, ".discard.unwind_hints");
2044 relocsec = sec->reloc;
2046 WARN("missing .rela.discard.unwind_hints section");
2050 if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
2051 WARN("struct unwind_hint size mismatch");
2057 for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
2058 hint = (struct unwind_hint *)sec->data->d_buf + i;
2060 reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
2062 WARN("can't find reloc for unwind_hints[%d]", i);
2066 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2068 WARN("can't find insn for unwind_hints[%d]", i);
2074 if (hint->type == UNWIND_HINT_TYPE_SAVE) {
2080 if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
2081 insn->restore = true;
2085 if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
2086 struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
2088 if (sym && sym->bind == STB_GLOBAL) {
2089 if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
2090 WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR",
2091 insn->sec, insn->offset);
2098 if (hint->type == UNWIND_HINT_TYPE_ENTRY) {
2099 hint->type = UNWIND_HINT_TYPE_CALL;
2103 if (hint->type == UNWIND_HINT_TYPE_FUNC) {
2104 insn->cfi = &func_cfi;
2111 if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
2112 WARN_FUNC("unsupported unwind_hint sp base reg %d",
2113 insn->sec, insn->offset, hint->sp_reg);
2117 cfi.cfa.offset = bswap_if_needed(hint->sp_offset);
2118 cfi.type = hint->type;
2119 cfi.end = hint->end;
2121 insn->cfi = cfi_hash_find_or_add(&cfi);
2127 static int read_noendbr_hints(struct objtool_file *file)
2129 struct section *sec;
2130 struct instruction *insn;
2131 struct reloc *reloc;
2133 sec = find_section_by_name(file->elf, ".rela.discard.noendbr");
2137 list_for_each_entry(reloc, &sec->reloc_list, list) {
2138 insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend);
2140 WARN("bad .discard.noendbr entry");
2150 static int read_retpoline_hints(struct objtool_file *file)
2152 struct section *sec;
2153 struct instruction *insn;
2154 struct reloc *reloc;
2156 sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
2160 list_for_each_entry(reloc, &sec->reloc_list, list) {
2161 if (reloc->sym->type != STT_SECTION) {
2162 WARN("unexpected relocation symbol type in %s", sec->name);
2166 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2168 WARN("bad .discard.retpoline_safe entry");
2172 if (insn->type != INSN_JUMP_DYNAMIC &&
2173 insn->type != INSN_CALL_DYNAMIC &&
2174 insn->type != INSN_RETURN &&
2175 insn->type != INSN_NOP) {
2176 WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret/nop",
2177 insn->sec, insn->offset);
2181 insn->retpoline_safe = true;
2187 static int read_instr_hints(struct objtool_file *file)
2189 struct section *sec;
2190 struct instruction *insn;
2191 struct reloc *reloc;
2193 sec = find_section_by_name(file->elf, ".rela.discard.instr_end");
2197 list_for_each_entry(reloc, &sec->reloc_list, list) {
2198 if (reloc->sym->type != STT_SECTION) {
2199 WARN("unexpected relocation symbol type in %s", sec->name);
2203 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2205 WARN("bad .discard.instr_end entry");
2212 sec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
2216 list_for_each_entry(reloc, &sec->reloc_list, list) {
2217 if (reloc->sym->type != STT_SECTION) {
2218 WARN("unexpected relocation symbol type in %s", sec->name);
2222 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2224 WARN("bad .discard.instr_begin entry");
2234 static int read_intra_function_calls(struct objtool_file *file)
2236 struct instruction *insn;
2237 struct section *sec;
2238 struct reloc *reloc;
2240 sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
2244 list_for_each_entry(reloc, &sec->reloc_list, list) {
2245 unsigned long dest_off;
2247 if (reloc->sym->type != STT_SECTION) {
2248 WARN("unexpected relocation symbol type in %s",
2253 insn = find_insn(file, reloc->sym->sec, reloc->addend);
2255 WARN("bad .discard.intra_function_call entry");
2259 if (insn->type != INSN_CALL) {
2260 WARN_FUNC("intra_function_call not a direct call",
2261 insn->sec, insn->offset);
2266 * Treat intra-function CALLs as JMPs, but with a stack_op.
2267 * See add_call_destinations(), which strips stack_ops from
2270 insn->type = INSN_JUMP_UNCONDITIONAL;
2272 dest_off = arch_jump_destination(insn);
2273 insn->jump_dest = find_insn(file, insn->sec, dest_off);
2274 if (!insn->jump_dest) {
2275 WARN_FUNC("can't find call dest at %s+0x%lx",
2276 insn->sec, insn->offset,
2277 insn->sec->name, dest_off);
2286 * Return true if name matches an instrumentation function, where calls to that
2287 * function from noinstr code can safely be removed, but compilers won't do so.
2289 static bool is_profiling_func(const char *name)
2292 * Many compilers cannot disable KCOV with a function attribute.
2294 if (!strncmp(name, "__sanitizer_cov_", 16))
2298 * Some compilers currently do not remove __tsan_func_entry/exit nor
2299 * __tsan_atomic_signal_fence (used for barrier instrumentation) with
2300 * the __no_sanitize_thread attribute, remove them. Once the kernel's
2301 * minimum Clang version is 14.0, this can be removed.
2303 if (!strncmp(name, "__tsan_func_", 12) ||
2304 !strcmp(name, "__tsan_atomic_signal_fence"))
2310 static int classify_symbols(struct objtool_file *file)
2312 struct section *sec;
2313 struct symbol *func;
2315 for_each_sec(file, sec) {
2316 list_for_each_entry(func, &sec->symbol_list, list) {
2317 if (func->bind != STB_GLOBAL)
2320 if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
2321 strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
2322 func->static_call_tramp = true;
2324 if (arch_is_retpoline(func))
2325 func->retpoline_thunk = true;
2327 if (arch_is_rethunk(func))
2328 func->return_thunk = true;
2330 if (!strcmp(func->name, "__fentry__"))
2331 func->fentry = true;
2333 if (is_profiling_func(func->name))
2334 func->profiling_func = true;
2341 static void mark_rodata(struct objtool_file *file)
2343 struct section *sec;
2347 * Search for the following rodata sections, each of which can
2348 * potentially contain jump tables:
2350 * - .rodata: can contain GCC switch tables
2351 * - .rodata.<func>: same, if -fdata-sections is being used
2352 * - .rodata..c_jump_table: contains C annotated jump tables
2354 * .rodata.str1.* sections are ignored; they don't contain jump tables.
2356 for_each_sec(file, sec) {
2357 if (!strncmp(sec->name, ".rodata", 7) &&
2358 !strstr(sec->name, ".str1.")) {
2364 file->rodata = found;
2367 static int decode_sections(struct objtool_file *file)
2373 ret = init_pv_ops(file);
2377 ret = decode_instructions(file);
2382 add_uaccess_safe(file);
2384 ret = add_ignore_alternatives(file);
2389 * Must be before read_unwind_hints() since that needs insn->noendbr.
2391 ret = read_noendbr_hints(file);
2396 * Must be before add_{jump_call}_destination.
2398 ret = classify_symbols(file);
2403 * Must be before add_jump_destinations(), which depends on 'func'
2404 * being set for alternatives, to enable proper sibling call detection.
2406 ret = add_special_section_alts(file);
2410 ret = add_jump_destinations(file);
2415 * Must be before add_call_destination(); it changes INSN_CALL to
2418 ret = read_intra_function_calls(file);
2422 ret = add_call_destinations(file);
2427 * Must be after add_call_destinations() such that it can override
2428 * dead_end_function() marks.
2430 ret = add_dead_ends(file);
2434 ret = add_jump_table_alts(file);
2438 ret = read_unwind_hints(file);
2442 ret = read_retpoline_hints(file);
2446 ret = read_instr_hints(file);
2453 static bool is_fentry_call(struct instruction *insn)
2455 if (insn->type == INSN_CALL &&
2457 insn->call_dest->fentry)
2463 static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
2465 struct cfi_state *cfi = &state->cfi;
2468 if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
2471 if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
2474 if (cfi->stack_size != initial_func_cfi.cfa.offset)
2477 for (i = 0; i < CFI_NUM_REGS; i++) {
2478 if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
2479 cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
2486 static bool check_reg_frame_pos(const struct cfi_reg *reg,
2487 int expected_offset)
2489 return reg->base == CFI_CFA &&
2490 reg->offset == expected_offset;
2493 static bool has_valid_stack_frame(struct insn_state *state)
2495 struct cfi_state *cfi = &state->cfi;
2497 if (cfi->cfa.base == CFI_BP &&
2498 check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
2499 check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
2502 if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
2508 static int update_cfi_state_regs(struct instruction *insn,
2509 struct cfi_state *cfi,
2510 struct stack_op *op)
2512 struct cfi_reg *cfa = &cfi->cfa;
2514 if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
2518 if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
2522 if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
2525 /* add immediate to sp */
2526 if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
2527 op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
2528 cfa->offset -= op->src.offset;
2533 static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
2535 if (arch_callee_saved_reg(reg) &&
2536 cfi->regs[reg].base == CFI_UNDEFINED) {
2537 cfi->regs[reg].base = base;
2538 cfi->regs[reg].offset = offset;
2542 static void restore_reg(struct cfi_state *cfi, unsigned char reg)
2544 cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
2545 cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
2549 * A note about DRAP stack alignment:
2551 * GCC has the concept of a DRAP register, which is used to help keep track of
2552 * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
2553 * register. The typical DRAP pattern is:
2555 * 4c 8d 54 24 08 lea 0x8(%rsp),%r10
2556 * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
2557 * 41 ff 72 f8 pushq -0x8(%r10)
2559 * 48 89 e5 mov %rsp,%rbp
2566 * 49 8d 62 f8 lea -0x8(%r10),%rsp
2569 * There are some variations in the epilogues, like:
2577 * 49 8d 62 f8 lea -0x8(%r10),%rsp
2582 * 4c 8b 55 e8 mov -0x18(%rbp),%r10
2583 * 48 8b 5d e0 mov -0x20(%rbp),%rbx
2584 * 4c 8b 65 f0 mov -0x10(%rbp),%r12
2585 * 4c 8b 6d f8 mov -0x8(%rbp),%r13
2587 * 49 8d 62 f8 lea -0x8(%r10),%rsp
2590 * Sometimes r13 is used as the DRAP register, in which case it's saved and
2591 * restored beforehand:
2594 * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
2595 * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
2597 * 49 8d 65 f0 lea -0x10(%r13),%rsp
2601 static int update_cfi_state(struct instruction *insn,
2602 struct instruction *next_insn,
2603 struct cfi_state *cfi, struct stack_op *op)
2605 struct cfi_reg *cfa = &cfi->cfa;
2606 struct cfi_reg *regs = cfi->regs;
2608 /* stack operations don't make sense with an undefined CFA */
2609 if (cfa->base == CFI_UNDEFINED) {
2611 WARN_FUNC("undefined stack state", insn->sec, insn->offset);
2617 if (cfi->type == UNWIND_HINT_TYPE_REGS ||
2618 cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
2619 return update_cfi_state_regs(insn, cfi, op);
2621 switch (op->dest.type) {
2624 switch (op->src.type) {
2627 if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
2628 cfa->base == CFI_SP &&
2629 check_reg_frame_pos(®s[CFI_BP], -cfa->offset)) {
2631 /* mov %rsp, %rbp */
2632 cfa->base = op->dest.reg;
2633 cfi->bp_scratch = false;
2636 else if (op->src.reg == CFI_SP &&
2637 op->dest.reg == CFI_BP && cfi->drap) {
2639 /* drap: mov %rsp, %rbp */
2640 regs[CFI_BP].base = CFI_BP;
2641 regs[CFI_BP].offset = -cfi->stack_size;
2642 cfi->bp_scratch = false;
2645 else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2650 * This is needed for the rare case where GCC
2657 cfi->vals[op->dest.reg].base = CFI_CFA;
2658 cfi->vals[op->dest.reg].offset = -cfi->stack_size;
2661 else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
2662 (cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {
2667 * Restore the original stack pointer (Clang).
2669 cfi->stack_size = -cfi->regs[CFI_BP].offset;
2672 else if (op->dest.reg == cfa->base) {
2674 /* mov %reg, %rsp */
2675 if (cfa->base == CFI_SP &&
2676 cfi->vals[op->src.reg].base == CFI_CFA) {
2679 * This is needed for the rare case
2680 * where GCC does something dumb like:
2682 * lea 0x8(%rsp), %rcx
2686 cfa->offset = -cfi->vals[op->src.reg].offset;
2687 cfi->stack_size = cfa->offset;
2689 } else if (cfa->base == CFI_SP &&
2690 cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2691 cfi->vals[op->src.reg].offset == cfa->offset) {
2696 * 1: mov %rsp, (%[tos])
2697 * 2: mov %[tos], %rsp
2703 * 1 - places a pointer to the previous
2704 * stack at the Top-of-Stack of the
2707 * 2 - switches to the new stack.
2709 * 3 - pops the Top-of-Stack to restore
2710 * the original stack.
2712 * Note: we set base to SP_INDIRECT
2713 * here and preserve offset. Therefore
2714 * when the unwinder reaches ToS it
2715 * will dereference SP and then add the
2716 * offset to find the next frame, IOW:
2719 cfa->base = CFI_SP_INDIRECT;
2722 cfa->base = CFI_UNDEFINED;
2727 else if (op->dest.reg == CFI_SP &&
2728 cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2729 cfi->vals[op->src.reg].offset == cfa->offset) {
2732 * The same stack swizzle case 2) as above. But
2733 * because we can't change cfa->base, case 3)
2734 * will become a regular POP. Pretend we're a
2735 * PUSH so things don't go unbalanced.
2737 cfi->stack_size += 8;
2744 if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
2747 cfi->stack_size -= op->src.offset;
2748 if (cfa->base == CFI_SP)
2749 cfa->offset -= op->src.offset;
2753 if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
2755 /* lea disp(%rbp), %rsp */
2756 cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
2760 if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2762 /* drap: lea disp(%rsp), %drap */
2763 cfi->drap_reg = op->dest.reg;
2766 * lea disp(%rsp), %reg
2768 * This is needed for the rare case where GCC
2769 * does something dumb like:
2771 * lea 0x8(%rsp), %rcx
2775 cfi->vals[op->dest.reg].base = CFI_CFA;
2776 cfi->vals[op->dest.reg].offset = \
2777 -cfi->stack_size + op->src.offset;
2782 if (cfi->drap && op->dest.reg == CFI_SP &&
2783 op->src.reg == cfi->drap_reg) {
2785 /* drap: lea disp(%drap), %rsp */
2787 cfa->offset = cfi->stack_size = -op->src.offset;
2788 cfi->drap_reg = CFI_UNDEFINED;
2793 if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
2794 WARN_FUNC("unsupported stack register modification",
2795 insn->sec, insn->offset);
2802 if (op->dest.reg != CFI_SP ||
2803 (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
2804 (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
2805 WARN_FUNC("unsupported stack pointer realignment",
2806 insn->sec, insn->offset);
2810 if (cfi->drap_reg != CFI_UNDEFINED) {
2811 /* drap: and imm, %rsp */
2812 cfa->base = cfi->drap_reg;
2813 cfa->offset = cfi->stack_size = 0;
2818 * Older versions of GCC (4.8ish) realign the stack
2819 * without DRAP, with a frame pointer.
2826 if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
2828 /* pop %rsp; # restore from a stack swizzle */
2833 if (!cfi->drap && op->dest.reg == cfa->base) {
2839 if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
2840 op->dest.reg == cfi->drap_reg &&
2841 cfi->drap_offset == -cfi->stack_size) {
2843 /* drap: pop %drap */
2844 cfa->base = cfi->drap_reg;
2846 cfi->drap_offset = -1;
2848 } else if (cfi->stack_size == -regs[op->dest.reg].offset) {
2851 restore_reg(cfi, op->dest.reg);
2854 cfi->stack_size -= 8;
2855 if (cfa->base == CFI_SP)
2860 case OP_SRC_REG_INDIRECT:
2861 if (!cfi->drap && op->dest.reg == cfa->base &&
2862 op->dest.reg == CFI_BP) {
2864 /* mov disp(%rsp), %rbp */
2866 cfa->offset = cfi->stack_size;
2869 if (cfi->drap && op->src.reg == CFI_BP &&
2870 op->src.offset == cfi->drap_offset) {
2872 /* drap: mov disp(%rbp), %drap */
2873 cfa->base = cfi->drap_reg;
2875 cfi->drap_offset = -1;
2878 if (cfi->drap && op->src.reg == CFI_BP &&
2879 op->src.offset == regs[op->dest.reg].offset) {
2881 /* drap: mov disp(%rbp), %reg */
2882 restore_reg(cfi, op->dest.reg);
2884 } else if (op->src.reg == cfa->base &&
2885 op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
2887 /* mov disp(%rbp), %reg */
2888 /* mov disp(%rsp), %reg */
2889 restore_reg(cfi, op->dest.reg);
2891 } else if (op->src.reg == CFI_SP &&
2892 op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
2894 /* mov disp(%rsp), %reg */
2895 restore_reg(cfi, op->dest.reg);
2901 WARN_FUNC("unknown stack-related instruction",
2902 insn->sec, insn->offset);
2910 cfi->stack_size += 8;
2911 if (cfa->base == CFI_SP)
2914 if (op->src.type != OP_SRC_REG)
2918 if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
2920 /* drap: push %drap */
2921 cfa->base = CFI_BP_INDIRECT;
2922 cfa->offset = -cfi->stack_size;
2924 /* save drap so we know when to restore it */
2925 cfi->drap_offset = -cfi->stack_size;
2927 } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
2929 /* drap: push %rbp */
2930 cfi->stack_size = 0;
2934 /* drap: push %reg */
2935 save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
2941 save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
2944 /* detect when asm code uses rbp as a scratch register */
2945 if (opts.stackval && insn->func && op->src.reg == CFI_BP &&
2946 cfa->base != CFI_BP)
2947 cfi->bp_scratch = true;
2950 case OP_DEST_REG_INDIRECT:
2953 if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
2955 /* drap: mov %drap, disp(%rbp) */
2956 cfa->base = CFI_BP_INDIRECT;
2957 cfa->offset = op->dest.offset;
2959 /* save drap offset so we know when to restore it */
2960 cfi->drap_offset = op->dest.offset;
2963 /* drap: mov reg, disp(%rbp) */
2964 save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
2967 } else if (op->dest.reg == cfa->base) {
2969 /* mov reg, disp(%rbp) */
2970 /* mov reg, disp(%rsp) */
2971 save_reg(cfi, op->src.reg, CFI_CFA,
2972 op->dest.offset - cfi->cfa.offset);
2974 } else if (op->dest.reg == CFI_SP) {
2976 /* mov reg, disp(%rsp) */
2977 save_reg(cfi, op->src.reg, CFI_CFA,
2978 op->dest.offset - cfi->stack_size);
2980 } else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
2982 /* mov %rsp, (%reg); # setup a stack swizzle. */
2983 cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
2984 cfi->vals[op->dest.reg].offset = cfa->offset;
2990 if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
2991 WARN_FUNC("unknown stack-related memory operation",
2992 insn->sec, insn->offset);
2997 cfi->stack_size -= 8;
2998 if (cfa->base == CFI_SP)
3004 WARN_FUNC("unknown stack-related instruction",
3005 insn->sec, insn->offset);
3013 * The stack layouts of alternatives instructions can sometimes diverge when
3014 * they have stack modifications. That's fine as long as the potential stack
3015 * layouts don't conflict at any given potential instruction boundary.
3017 * Flatten the CFIs of the different alternative code streams (both original
3018 * and replacement) into a single shared CFI array which can be used to detect
3019 * conflicts and nicely feed a linear array of ORC entries to the unwinder.
3021 static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
3023 struct cfi_state **alt_cfi;
3026 if (!insn->alt_group)
3030 WARN("CFI missing");
3034 alt_cfi = insn->alt_group->cfi;
3035 group_off = insn->offset - insn->alt_group->first_insn->offset;
3037 if (!alt_cfi[group_off]) {
3038 alt_cfi[group_off] = insn->cfi;
3040 if (cficmp(alt_cfi[group_off], insn->cfi)) {
3041 WARN_FUNC("stack layout conflict in alternatives",
3042 insn->sec, insn->offset);
3050 static int handle_insn_ops(struct instruction *insn,
3051 struct instruction *next_insn,
3052 struct insn_state *state)
3054 struct stack_op *op;
3056 list_for_each_entry(op, &insn->stack_ops, list) {
3058 if (update_cfi_state(insn, next_insn, &state->cfi, op))
3061 if (!insn->alt_group)
3064 if (op->dest.type == OP_DEST_PUSHF) {
3065 if (!state->uaccess_stack) {
3066 state->uaccess_stack = 1;
3067 } else if (state->uaccess_stack >> 31) {
3068 WARN_FUNC("PUSHF stack exhausted",
3069 insn->sec, insn->offset);
3072 state->uaccess_stack <<= 1;
3073 state->uaccess_stack |= state->uaccess;
3076 if (op->src.type == OP_SRC_POPF) {
3077 if (state->uaccess_stack) {
3078 state->uaccess = state->uaccess_stack & 1;
3079 state->uaccess_stack >>= 1;
3080 if (state->uaccess_stack == 1)
3081 state->uaccess_stack = 0;
3089 static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
3091 struct cfi_state *cfi1 = insn->cfi;
3095 WARN("CFI missing");
3099 if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
3101 WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
3102 insn->sec, insn->offset,
3103 cfi1->cfa.base, cfi1->cfa.offset,
3104 cfi2->cfa.base, cfi2->cfa.offset);
3106 } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
3107 for (i = 0; i < CFI_NUM_REGS; i++) {
3108 if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
3109 sizeof(struct cfi_reg)))
3112 WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
3113 insn->sec, insn->offset,
3114 i, cfi1->regs[i].base, cfi1->regs[i].offset,
3115 i, cfi2->regs[i].base, cfi2->regs[i].offset);
3119 } else if (cfi1->type != cfi2->type) {
3121 WARN_FUNC("stack state mismatch: type1=%d type2=%d",
3122 insn->sec, insn->offset, cfi1->type, cfi2->type);
3124 } else if (cfi1->drap != cfi2->drap ||
3125 (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
3126 (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
3128 WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
3129 insn->sec, insn->offset,
3130 cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
3131 cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
3139 static inline bool func_uaccess_safe(struct symbol *func)
3142 return func->uaccess_safe;
3147 static inline const char *call_dest_name(struct instruction *insn)
3149 static char pvname[19];
3153 if (insn->call_dest)
3154 return insn->call_dest->name;
3156 rel = insn_reloc(NULL, insn);
3157 if (rel && !strcmp(rel->sym->name, "pv_ops")) {
3158 idx = (rel->addend / sizeof(void *));
3159 snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
3166 static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
3168 struct symbol *target;
3172 rel = insn_reloc(file, insn);
3173 if (!rel || strcmp(rel->sym->name, "pv_ops"))
3176 idx = (arch_dest_reloc_offset(rel->addend) / sizeof(void *));
3178 if (file->pv_ops[idx].clean)
3181 file->pv_ops[idx].clean = true;
3183 list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
3184 if (!target->sec->noinstr) {
3185 WARN("pv_ops[%d]: %s", idx, target->name);
3186 file->pv_ops[idx].clean = false;
3190 return file->pv_ops[idx].clean;
3193 static inline bool noinstr_call_dest(struct objtool_file *file,
3194 struct instruction *insn,
3195 struct symbol *func)
3198 * We can't deal with indirect function calls at present;
3199 * assume they're instrumented.
3203 return pv_call_dest(file, insn);
3209 * If the symbol is from a noinstr section; we good.
3211 if (func->sec->noinstr)
3215 * The __ubsan_handle_*() calls are like WARN(), they only happen when
3216 * something 'BAD' happened. At the risk of taking the machine down,
3217 * let them proceed to get the message out.
3219 if (!strncmp(func->name, "__ubsan_handle_", 15))
3225 static int validate_call(struct objtool_file *file,
3226 struct instruction *insn,
3227 struct insn_state *state)
3229 if (state->noinstr && state->instr <= 0 &&
3230 !noinstr_call_dest(file, insn, insn->call_dest)) {
3231 WARN_FUNC("call to %s() leaves .noinstr.text section",
3232 insn->sec, insn->offset, call_dest_name(insn));
3236 if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
3237 WARN_FUNC("call to %s() with UACCESS enabled",
3238 insn->sec, insn->offset, call_dest_name(insn));
3243 WARN_FUNC("call to %s() with DF set",
3244 insn->sec, insn->offset, call_dest_name(insn));
3251 static int validate_sibling_call(struct objtool_file *file,
3252 struct instruction *insn,
3253 struct insn_state *state)
3255 if (has_modified_stack_frame(insn, state)) {
3256 WARN_FUNC("sibling call from callable instruction with modified stack frame",
3257 insn->sec, insn->offset);
3261 return validate_call(file, insn, state);
3264 static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
3266 if (state->noinstr && state->instr > 0) {
3267 WARN_FUNC("return with instrumentation enabled",
3268 insn->sec, insn->offset);
3272 if (state->uaccess && !func_uaccess_safe(func)) {
3273 WARN_FUNC("return with UACCESS enabled",
3274 insn->sec, insn->offset);
3278 if (!state->uaccess && func_uaccess_safe(func)) {
3279 WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function",
3280 insn->sec, insn->offset);
3285 WARN_FUNC("return with DF set",
3286 insn->sec, insn->offset);
3290 if (func && has_modified_stack_frame(insn, state)) {
3291 WARN_FUNC("return with modified stack frame",
3292 insn->sec, insn->offset);
3296 if (state->cfi.bp_scratch) {
3297 WARN_FUNC("BP used as a scratch register",
3298 insn->sec, insn->offset);
3305 static struct instruction *next_insn_to_validate(struct objtool_file *file,
3306 struct instruction *insn)
3308 struct alt_group *alt_group = insn->alt_group;
3311 * Simulate the fact that alternatives are patched in-place. When the
3312 * end of a replacement alt_group is reached, redirect objtool flow to
3313 * the end of the original alt_group.
3315 if (alt_group && insn == alt_group->last_insn && alt_group->orig_group)
3316 return next_insn_same_sec(file, alt_group->orig_group->last_insn);
3318 return next_insn_same_sec(file, insn);
3322 * Follow the branch starting at the given instruction, and recursively follow
3323 * any other branches (jumps). Meanwhile, track the frame pointer state at
3324 * each instruction and validate all the rules described in
3325 * tools/objtool/Documentation/objtool.txt.
3327 static int validate_branch(struct objtool_file *file, struct symbol *func,
3328 struct instruction *insn, struct insn_state state)
3330 struct alternative *alt;
3331 struct instruction *next_insn, *prev_insn = NULL;
3332 struct section *sec;
3339 next_insn = next_insn_to_validate(file, insn);
3341 if (func && insn->func && func != insn->func->pfunc) {
3342 /* Ignore KCFI type preambles, which always fall through */
3343 if (!strncmp(func->name, "__cfi_", 6))
3346 WARN("%s() falls through to next function %s()",
3347 func->name, insn->func->name);
3351 if (func && insn->ignore) {
3352 WARN_FUNC("BUG: why am I validating an ignored function?",
3357 visited = VISITED_BRANCH << state.uaccess;
3358 if (insn->visited & VISITED_BRANCH_MASK) {
3359 if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
3362 if (insn->visited & visited)
3369 state.instr += insn->instr;
3372 if (insn->restore) {
3373 struct instruction *save_insn, *i;
3378 sym_for_each_insn_continue_reverse(file, func, i) {
3386 WARN_FUNC("no corresponding CFI save for CFI restore",
3391 if (!save_insn->visited) {
3392 WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
3397 insn->cfi = save_insn->cfi;
3401 state.cfi = *insn->cfi;
3403 /* XXX track if we actually changed state.cfi */
3405 if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {
3406 insn->cfi = prev_insn->cfi;
3409 insn->cfi = cfi_hash_find_or_add(&state.cfi);
3413 insn->visited |= visited;
3415 if (propagate_alt_cfi(file, insn))
3418 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
3419 bool skip_orig = false;
3421 list_for_each_entry(alt, &insn->alts, list) {
3425 ret = validate_branch(file, func, alt->insn, state);
3428 BT_FUNC("(alt)", insn);
3437 if (handle_insn_ops(insn, next_insn, &state))
3440 switch (insn->type) {
3443 return validate_return(func, insn, &state);
3446 case INSN_CALL_DYNAMIC:
3447 ret = validate_call(file, insn, &state);
3451 if (opts.stackval && func && !is_fentry_call(insn) &&
3452 !has_valid_stack_frame(&state)) {
3453 WARN_FUNC("call without frame pointer save/setup",
3463 case INSN_JUMP_CONDITIONAL:
3464 case INSN_JUMP_UNCONDITIONAL:
3465 if (is_sibling_call(insn)) {
3466 ret = validate_sibling_call(file, insn, &state);
3470 } else if (insn->jump_dest) {
3471 ret = validate_branch(file, func,
3472 insn->jump_dest, state);
3475 BT_FUNC("(branch)", insn);
3480 if (insn->type == INSN_JUMP_UNCONDITIONAL)
3485 case INSN_JUMP_DYNAMIC:
3486 case INSN_JUMP_DYNAMIC_CONDITIONAL:
3487 if (is_sibling_call(insn)) {
3488 ret = validate_sibling_call(file, insn, &state);
3493 if (insn->type == INSN_JUMP_DYNAMIC)
3498 case INSN_CONTEXT_SWITCH:
3499 if (func && (!next_insn || !next_insn->hint)) {
3500 WARN_FUNC("unsupported instruction in callable function",
3507 if (state.uaccess) {
3508 WARN_FUNC("recursive UACCESS enable", sec, insn->offset);
3512 state.uaccess = true;
3516 if (!state.uaccess && func) {
3517 WARN_FUNC("redundant UACCESS disable", sec, insn->offset);
3521 if (func_uaccess_safe(func) && !state.uaccess_stack) {
3522 WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset);
3526 state.uaccess = false;
3531 WARN_FUNC("recursive STD", sec, insn->offset);
3539 if (!state.df && func) {
3540 WARN_FUNC("redundant CLD", sec, insn->offset);
3555 if (state.cfi.cfa.base == CFI_UNDEFINED)
3557 WARN("%s: unexpected end of section", sec->name);
3568 static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
3570 struct instruction *insn;
3571 struct insn_state state;
3572 int ret, warnings = 0;
3577 init_insn_state(file, &state, sec);
3580 insn = find_insn(file, sec, 0);
3584 insn = list_first_entry(&file->insn_list, typeof(*insn), list);
3587 while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
3588 if (insn->hint && !insn->visited && !insn->ignore) {
3589 ret = validate_branch(file, insn->func, insn, state);
3590 if (ret && opts.backtrace)
3591 BT_FUNC("<=== (hint)", insn);
3595 insn = list_next_entry(insn, list);
3602 * Validate rethunk entry constraint: must untrain RET before the first RET.
3604 * Follow every branch (intra-function) and ensure ANNOTATE_UNRET_END comes
3605 * before an actual RET instruction.
3607 static int validate_entry(struct objtool_file *file, struct instruction *insn)
3609 struct instruction *next, *dest;
3610 int ret, warnings = 0;
3613 next = next_insn_to_validate(file, insn);
3615 if (insn->visited & VISITED_ENTRY)
3618 insn->visited |= VISITED_ENTRY;
3620 if (!insn->ignore_alts && !list_empty(&insn->alts)) {
3621 struct alternative *alt;
3622 bool skip_orig = false;
3624 list_for_each_entry(alt, &insn->alts, list) {
3628 ret = validate_entry(file, alt->insn);
3631 BT_FUNC("(alt)", insn);
3640 switch (insn->type) {
3642 case INSN_CALL_DYNAMIC:
3643 case INSN_JUMP_DYNAMIC:
3644 case INSN_JUMP_DYNAMIC_CONDITIONAL:
3645 WARN_FUNC("early indirect call", insn->sec, insn->offset);
3648 case INSN_JUMP_UNCONDITIONAL:
3649 case INSN_JUMP_CONDITIONAL:
3650 if (!is_sibling_call(insn)) {
3651 if (!insn->jump_dest) {
3652 WARN_FUNC("unresolved jump target after linking?!?",
3653 insn->sec, insn->offset);
3656 ret = validate_entry(file, insn->jump_dest);
3658 if (opts.backtrace) {
3659 BT_FUNC("(branch%s)", insn,
3660 insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
3665 if (insn->type == INSN_JUMP_UNCONDITIONAL)
3673 dest = find_insn(file, insn->call_dest->sec,
3674 insn->call_dest->offset);
3676 WARN("Unresolved function after linking!?: %s",
3677 insn->call_dest->name);
3681 ret = validate_entry(file, dest);
3684 BT_FUNC("(call)", insn);
3688 * If a call returns without error, it must have seen UNTRAIN_RET.
3689 * Therefore any non-error return is a success.
3694 WARN_FUNC("RET before UNTRAIN", insn->sec, insn->offset);
3698 if (insn->retpoline_safe)
3707 WARN_FUNC("teh end!", insn->sec, insn->offset);
3717 * Validate that all branches starting at 'insn->entry' encounter UNRET_END
3720 static int validate_unret(struct objtool_file *file)
3722 struct instruction *insn;
3723 int ret, warnings = 0;
3725 for_each_insn(file, insn) {
3729 ret = validate_entry(file, insn);
3731 WARN_FUNC("Failed UNRET validation", insn->sec, insn->offset);
3740 static int validate_retpoline(struct objtool_file *file)
3742 struct instruction *insn;
3745 for_each_insn(file, insn) {
3746 if (insn->type != INSN_JUMP_DYNAMIC &&
3747 insn->type != INSN_CALL_DYNAMIC &&
3748 insn->type != INSN_RETURN)
3751 if (insn->retpoline_safe)
3755 * .init.text code is ran before userspace and thus doesn't
3756 * strictly need retpolines, except for modules which are
3757 * loaded late, they very much do need retpoline in their
3760 if (!strcmp(insn->sec->name, ".init.text") && !opts.module)
3763 if (insn->type == INSN_RETURN) {
3765 WARN_FUNC("'naked' return found in RETHUNK build",
3766 insn->sec, insn->offset);
3770 WARN_FUNC("indirect %s found in RETPOLINE build",
3771 insn->sec, insn->offset,
3772 insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
3781 static bool is_kasan_insn(struct instruction *insn)
3783 return (insn->type == INSN_CALL &&
3784 !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
3787 static bool is_ubsan_insn(struct instruction *insn)
3789 return (insn->type == INSN_CALL &&
3790 !strcmp(insn->call_dest->name,
3791 "__ubsan_handle_builtin_unreachable"));
3794 static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
3797 struct instruction *prev_insn;
3799 if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
3803 * Ignore alternative replacement instructions. This can happen
3804 * when a whitelisted function uses one of the ALTERNATIVE macros.
3806 if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
3807 !strcmp(insn->sec->name, ".altinstr_aux"))
3811 * Whole archive runs might encounter dead code from weak symbols.
3812 * This is where the linker will have dropped the weak symbol in
3813 * favour of a regular symbol, but leaves the code in place.
3815 * In this case we'll find a piece of code (whole function) that is not
3816 * covered by a !section symbol. Ignore them.
3818 if (opts.link && !insn->func) {
3819 int size = find_symbol_hole_containing(insn->sec, insn->offset);
3820 unsigned long end = insn->offset + size;
3822 if (!size) /* not a hole */
3825 if (size < 0) /* hole until the end */
3828 sec_for_each_insn_continue(file, insn) {
3830 * If we reach a visited instruction at or before the
3831 * end of the hole, ignore the unreachable.
3836 if (insn->offset >= end)
3840 * If this hole jumps to a .cold function, mark it ignore too.
3842 if (insn->jump_dest && insn->jump_dest->func &&
3843 strstr(insn->jump_dest->func->name, ".cold")) {
3844 struct instruction *dest = insn->jump_dest;
3845 func_for_each_insn(file, dest->func, dest)
3846 dest->ignore = true;
3856 if (insn->func->static_call_tramp)
3860 * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
3861 * __builtin_unreachable(). The BUG() macro has an unreachable() after
3862 * the UD2, which causes GCC's undefined trap logic to emit another UD2
3863 * (or occasionally a JMP to UD2).
3865 * It may also insert a UD2 after calling a __noreturn function.
3867 prev_insn = list_prev_entry(insn, list);
3868 if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&
3869 (insn->type == INSN_BUG ||
3870 (insn->type == INSN_JUMP_UNCONDITIONAL &&
3871 insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
3875 * Check if this (or a subsequent) instruction is related to
3876 * CONFIG_UBSAN or CONFIG_KASAN.
3878 * End the search at 5 instructions to avoid going into the weeds.
3880 for (i = 0; i < 5; i++) {
3882 if (is_kasan_insn(insn) || is_ubsan_insn(insn))
3885 if (insn->type == INSN_JUMP_UNCONDITIONAL) {
3886 if (insn->jump_dest &&
3887 insn->jump_dest->func == insn->func) {
3888 insn = insn->jump_dest;
3895 if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
3898 insn = list_next_entry(insn, list);
3904 static int validate_symbol(struct objtool_file *file, struct section *sec,
3905 struct symbol *sym, struct insn_state *state)
3907 struct instruction *insn;
3911 WARN("%s() is missing an ELF size annotation", sym->name);
3915 if (sym->pfunc != sym || sym->alias != sym)
3918 insn = find_insn(file, sec, sym->offset);
3919 if (!insn || insn->ignore || insn->visited)
3922 state->uaccess = sym->uaccess_safe;
3924 ret = validate_branch(file, insn->func, insn, *state);
3925 if (ret && opts.backtrace)
3926 BT_FUNC("<=== (sym)", insn);
3930 static int validate_section(struct objtool_file *file, struct section *sec)
3932 struct insn_state state;
3933 struct symbol *func;
3936 list_for_each_entry(func, &sec->symbol_list, list) {
3937 if (func->type != STT_FUNC)
3940 init_insn_state(file, &state, sec);
3941 set_func_state(&state.cfi);
3943 warnings += validate_symbol(file, sec, func, &state);
3949 static int validate_noinstr_sections(struct objtool_file *file)
3951 struct section *sec;
3954 sec = find_section_by_name(file->elf, ".noinstr.text");
3956 warnings += validate_section(file, sec);
3957 warnings += validate_unwind_hints(file, sec);
3960 sec = find_section_by_name(file->elf, ".entry.text");
3962 warnings += validate_section(file, sec);
3963 warnings += validate_unwind_hints(file, sec);
3969 static int validate_functions(struct objtool_file *file)
3971 struct section *sec;
3974 for_each_sec(file, sec) {
3975 if (!(sec->sh.sh_flags & SHF_EXECINSTR))
3978 warnings += validate_section(file, sec);
3984 static void mark_endbr_used(struct instruction *insn)
3986 if (!list_empty(&insn->call_node))
3987 list_del_init(&insn->call_node);
3990 static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
3992 struct instruction *dest;
3993 struct reloc *reloc;
3998 * Looking for function pointer load relocations. Ignore
3999 * direct/indirect branches:
4001 switch (insn->type) {
4003 case INSN_CALL_DYNAMIC:
4004 case INSN_JUMP_CONDITIONAL:
4005 case INSN_JUMP_UNCONDITIONAL:
4006 case INSN_JUMP_DYNAMIC:
4007 case INSN_JUMP_DYNAMIC_CONDITIONAL:
4015 for (reloc = insn_reloc(file, insn);
4017 reloc = find_reloc_by_dest_range(file->elf, insn->sec,
4019 (insn->offset + insn->len) - (reloc->offset + 1))) {
4022 * static_call_update() references the trampoline, which
4023 * doesn't have (or need) ENDBR. Skip warning in that case.
4025 if (reloc->sym->static_call_tramp)
4028 off = reloc->sym->offset;
4029 if (reloc->type == R_X86_64_PC32 || reloc->type == R_X86_64_PLT32)
4030 off += arch_dest_reloc_offset(reloc->addend);
4032 off += reloc->addend;
4034 dest = find_insn(file, reloc->sym->sec, off);
4038 if (dest->type == INSN_ENDBR) {
4039 mark_endbr_used(dest);
4043 if (dest->func && dest->func == insn->func) {
4045 * Anything from->to self is either _THIS_IP_ or
4048 * There is no sane way to annotate _THIS_IP_ since the
4049 * compiler treats the relocation as a constant and is
4050 * happy to fold in offsets, skewing any annotation we
4051 * do, leading to vast amounts of false-positives.
4053 * There's also compiler generated _THIS_IP_ through
4054 * KCOV and such which we have no hope of annotating.
4056 * As such, blanket accept self-references without
4065 WARN_FUNC("relocation to !ENDBR: %s",
4066 insn->sec, insn->offset,
4067 offstr(dest->sec, dest->offset));
4075 static int validate_ibt_data_reloc(struct objtool_file *file,
4076 struct reloc *reloc)
4078 struct instruction *dest;
4080 dest = find_insn(file, reloc->sym->sec,
4081 reloc->sym->offset + reloc->addend);
4085 if (dest->type == INSN_ENDBR) {
4086 mark_endbr_used(dest);
4093 WARN_FUNC("data relocation to !ENDBR: %s",
4094 reloc->sec->base, reloc->offset,
4095 offstr(dest->sec, dest->offset));
4101 * Validate IBT rules and remove used ENDBR instructions from the seal list.
4102 * Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
4103 * NOPs) later, in create_ibt_endbr_seal_sections().
4105 static int validate_ibt(struct objtool_file *file)
4107 struct section *sec;
4108 struct reloc *reloc;
4109 struct instruction *insn;
4112 for_each_insn(file, insn)
4113 warnings += validate_ibt_insn(file, insn);
4115 for_each_sec(file, sec) {
4117 /* Already done by validate_ibt_insn() */
4118 if (sec->sh.sh_flags & SHF_EXECINSTR)
4125 * These sections can reference text addresses, but not with
4126 * the intent to indirect branch to them.
4128 if ((!strncmp(sec->name, ".discard", 8) &&
4129 strcmp(sec->name, ".discard.ibt_endbr_noseal")) ||
4130 !strncmp(sec->name, ".debug", 6) ||
4131 !strcmp(sec->name, ".altinstructions") ||
4132 !strcmp(sec->name, ".ibt_endbr_seal") ||
4133 !strcmp(sec->name, ".orc_unwind_ip") ||
4134 !strcmp(sec->name, ".parainstructions") ||
4135 !strcmp(sec->name, ".retpoline_sites") ||
4136 !strcmp(sec->name, ".smp_locks") ||
4137 !strcmp(sec->name, ".static_call_sites") ||
4138 !strcmp(sec->name, "_error_injection_whitelist") ||
4139 !strcmp(sec->name, "_kprobe_blacklist") ||
4140 !strcmp(sec->name, "__bug_table") ||
4141 !strcmp(sec->name, "__ex_table") ||
4142 !strcmp(sec->name, "__jump_table") ||
4143 !strcmp(sec->name, "__mcount_loc") ||
4144 !strcmp(sec->name, ".kcfi_traps") ||
4145 strstr(sec->name, "__patchable_function_entries"))
4148 list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
4149 warnings += validate_ibt_data_reloc(file, reloc);
4155 static int validate_sls(struct objtool_file *file)
4157 struct instruction *insn, *next_insn;
4160 for_each_insn(file, insn) {
4161 next_insn = next_insn_same_sec(file, insn);
4163 if (insn->retpoline_safe)
4166 switch (insn->type) {
4168 if (!next_insn || next_insn->type != INSN_TRAP) {
4169 WARN_FUNC("missing int3 after ret",
4170 insn->sec, insn->offset);
4175 case INSN_JUMP_DYNAMIC:
4176 if (!next_insn || next_insn->type != INSN_TRAP) {
4177 WARN_FUNC("missing int3 after indirect jump",
4178 insn->sec, insn->offset);
4190 static int validate_reachable_instructions(struct objtool_file *file)
4192 struct instruction *insn;
4194 if (file->ignore_unreachables)
4197 for_each_insn(file, insn) {
4198 if (insn->visited || ignore_unreachable_insn(file, insn))
4201 WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
4208 int check(struct objtool_file *file)
4210 int ret, warnings = 0;
4212 arch_initial_func_cfi_state(&initial_func_cfi);
4213 init_cfi_state(&init_cfi);
4214 init_cfi_state(&func_cfi);
4215 set_func_state(&func_cfi);
4217 if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
4220 cfi_hash_add(&init_cfi);
4221 cfi_hash_add(&func_cfi);
4223 ret = decode_sections(file);
4229 if (list_empty(&file->insn_list))
4232 if (opts.retpoline) {
4233 ret = validate_retpoline(file);
4239 if (opts.stackval || opts.orc || opts.uaccess) {
4240 ret = validate_functions(file);
4245 ret = validate_unwind_hints(file, NULL);
4251 ret = validate_reachable_instructions(file);
4257 } else if (opts.noinstr) {
4258 ret = validate_noinstr_sections(file);
4266 * Must be after validate_branch() and friends, it plays
4267 * further games with insn->visited.
4269 ret = validate_unret(file);
4276 ret = validate_ibt(file);
4283 ret = validate_sls(file);
4289 if (opts.static_call) {
4290 ret = create_static_call_sections(file);
4296 if (opts.retpoline) {
4297 ret = create_retpoline_sites_sections(file);
4304 ret = create_return_sites_sections(file);
4311 ret = create_mcount_loc_sections(file);
4318 ret = create_ibt_endbr_seal_sections(file);
4324 if (opts.orc && !list_empty(&file->insn_list)) {
4325 ret = orc_create(file);
4333 printf("nr_insns_visited: %ld\n", nr_insns_visited);
4334 printf("nr_cfi: %ld\n", nr_cfi);
4335 printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
4336 printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
4341 * For now, don't fail the kernel build on fatal warnings. These
4342 * errors are still fairly common due to the growing matrix of
4343 * supported toolchains and their recent pace of change.