1	// SPDX-License-Identifier: GPL-2.0-or-later
2	/*
3	* Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
4	*/
5
6	#include <string.h>
7	#include <stdlib.h>
8	#include <inttypes.h>
9	#include <sys/mman.h>
10
11	#include <objtool/builtin.h>
12	#include <objtool/cfi.h>
13	#include <objtool/arch.h>
14	#include <objtool/check.h>
15	#include <objtool/special.h>
16	#include <objtool/warn.h>
17	#include <objtool/endianness.h>
18
19	#include <linux/objtool_types.h>
20	#include <linux/hashtable.h>
21	#include <linux/kernel.h>
22	#include <linux/static_call_types.h>
23	#include <linux/string.h>
24
25	struct alternative {
26	struct alternative *next;
27	struct instruction *insn;
28	};
29
30	static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
31
32	static struct cfi_init_state initial_func_cfi;
33	static struct cfi_state init_cfi;
34	static struct cfi_state func_cfi;
35	static struct cfi_state force_undefined_cfi;
36
37	struct instruction *find_insn(struct objtool_file *file,
38	struct section *sec, unsigned long offset)
39	{
40	struct instruction *insn;
41
42	hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
43	if (insn->sec == sec && insn->offset == offset)
44	return insn;
45	}
46
47	return NULL;
48	}
49
50	struct instruction *next_insn_same_sec(struct objtool_file *file,
51	struct instruction *insn)
52	{
53	if (insn->idx == INSN_CHUNK_MAX)
54	return find_insn(file, sec: insn->sec, offset: insn->offset + insn->len);
55
56	insn++;
57	if (!insn->len)
58	return NULL;
59
60	return insn;
61	}
62
63	static struct instruction *next_insn_same_func(struct objtool_file *file,
64	struct instruction *insn)
65	{
66	struct instruction *next = next_insn_same_sec(file, insn);
67	struct symbol *func = insn_func(insn);
68
69	if (!func)
70	return NULL;
71
72	if (next && insn_func(next) == func)
73	return next;
74
75	/* Check if we're already in the subfunction: */
76	if (func == func->cfunc)
77	return NULL;
78
79	/* Move to the subfunction: */
80	return find_insn(file, sec: func->cfunc->sec, offset: func->cfunc->offset);
81	}
82
83	static struct instruction *prev_insn_same_sec(struct objtool_file *file,
84	struct instruction *insn)
85	{
86	if (insn->idx == 0) {
87	if (insn->prev_len)
88	return find_insn(file, sec: insn->sec, offset: insn->offset - insn->prev_len);
89	return NULL;
90	}
91
92	return insn - 1;
93	}
94
95	static struct instruction *prev_insn_same_sym(struct objtool_file *file,
96	struct instruction *insn)
97	{
98	struct instruction *prev = prev_insn_same_sec(file, insn);
99
100	if (prev && insn_func(prev) == insn_func(insn))
101	return prev;
102
103	return NULL;
104	}
105
106	#define for_each_insn(file, insn) \
107	for (struct section *__sec, *__fake = (struct section *)1; \
108	__fake; __fake = NULL) \
109	for_each_sec(file, __sec) \
110	sec_for_each_insn(file, __sec, insn)
111
112	#define func_for_each_insn(file, func, insn) \
113	for (insn = find_insn(file, func->sec, func->offset); \
114	insn; \
115	insn = next_insn_same_func(file, insn))
116
117	#define sym_for_each_insn(file, sym, insn) \
118	for (insn = find_insn(file, sym->sec, sym->offset); \
119	insn && insn->offset < sym->offset + sym->len; \
120	insn = next_insn_same_sec(file, insn))
121
122	#define sym_for_each_insn_continue_reverse(file, sym, insn) \
123	for (insn = prev_insn_same_sec(file, insn); \
124	insn && insn->offset >= sym->offset; \
125	insn = prev_insn_same_sec(file, insn))
126
127	#define sec_for_each_insn_from(file, insn) \
128	for (; insn; insn = next_insn_same_sec(file, insn))
129
130	#define sec_for_each_insn_continue(file, insn) \
131	for (insn = next_insn_same_sec(file, insn); insn; \
132	insn = next_insn_same_sec(file, insn))
133
134	static inline struct symbol *insn_call_dest(struct instruction *insn)
135	{
136	if (insn->type == INSN_JUMP_DYNAMIC ||
137	insn->type == INSN_CALL_DYNAMIC)
138	return NULL;
139
140	return insn->_call_dest;
141	}
142
143	static inline struct reloc *insn_jump_table(struct instruction *insn)
144	{
145	if (insn->type == INSN_JUMP_DYNAMIC ||
146	insn->type == INSN_CALL_DYNAMIC)
147	return insn->_jump_table;
148
149	return NULL;
150	}
151
152	static inline unsigned long insn_jump_table_size(struct instruction *insn)
153	{
154	if (insn->type == INSN_JUMP_DYNAMIC ||
155	insn->type == INSN_CALL_DYNAMIC)
156	return insn->_jump_table_size;
157
158	return 0;
159	}
160
161	static bool is_jump_table_jump(struct instruction *insn)
162	{
163	struct alt_group *alt_group = insn->alt_group;
164
165	if (insn_jump_table(insn))
166	return true;
167
168	/* Retpoline alternative for a jump table? */
169	return alt_group && alt_group->orig_group &&
170	insn_jump_table(insn: alt_group->orig_group->first_insn);
171	}
172
173	static bool is_sibling_call(struct instruction *insn)
174	{
175	/*
176	* Assume only STT_FUNC calls have jump-tables.
177	*/
178	if (insn_func(insn)) {
179	/* An indirect jump is either a sibling call or a jump to a table. */
180	if (insn->type == INSN_JUMP_DYNAMIC)
181	return !is_jump_table_jump(insn);
182	}
183
184	/* add_jump_destinations() sets insn_call_dest(insn) for sibling calls. */
185	return (is_static_jump(insn) && insn_call_dest(insn));
186	}
187
188	/*
189	* Checks if a string ends with another.
190	*/
191	static bool str_ends_with(const char *s, const char *sub)
192	{
193	const int slen = strlen(s);
194	const int sublen = strlen(sub);
195
196	if (sublen > slen)
197	return 0;
198
199	return !memcmp(p: s + slen - sublen, q: sub, size: sublen);
200	}
201
202	/*
203	* Checks if a function is a Rust "noreturn" one.
204	*/
205	static bool is_rust_noreturn(const struct symbol *func)
206	{
207	/*
208	* If it does not start with "_R", then it is not a Rust symbol.
209	*/
210	if (strncmp(func->name, "_R", 2))
211	return false;
212
213	/*
214	* These are just heuristics -- we do not control the precise symbol
215	* name, due to the crate disambiguators (which depend on the compiler)
216	* as well as changes to the source code itself between versions (since
217	* these come from the Rust standard library).
218	*/
219	return str_ends_with(s: func->name, sub: "_4core5sliceSp15copy_from_slice17len_mismatch_fail") ||
220	str_ends_with(s: func->name, sub: "_4core6option13unwrap_failed") ||
221	str_ends_with(s: func->name, sub: "_4core6result13unwrap_failed") ||
222	str_ends_with(s: func->name, sub: "_4core9panicking5panic") ||
223	str_ends_with(s: func->name, sub: "_4core9panicking9panic_fmt") ||
224	str_ends_with(s: func->name, sub: "_4core9panicking14panic_explicit") ||
225	str_ends_with(s: func->name, sub: "_4core9panicking14panic_nounwind") ||
226	str_ends_with(s: func->name, sub: "_4core9panicking18panic_bounds_check") ||
227	str_ends_with(s: func->name, sub: "_4core9panicking19assert_failed_inner") ||
228	str_ends_with(s: func->name, sub: "_4core9panicking30panic_null_pointer_dereference") ||
229	str_ends_with(s: func->name, sub: "_4core9panicking36panic_misaligned_pointer_dereference") ||
230	str_ends_with(s: func->name, sub: "_7___rustc17rust_begin_unwind") ||
231	strstr(func->name, "_4core9panicking13assert_failed") ||
232	strstr(func->name, "_4core9panicking11panic_const24panic_const_") ||
233	(strstr(func->name, "_4core5slice5index") &&
234	strstr(func->name, "slice_") &&
235	str_ends_with(s: func->name, sub: "_fail"));
236	}
237
238	/*
239	* This checks to see if the given function is a "noreturn" function.
240	*
241	* For global functions which are outside the scope of this object file, we
242	* have to keep a manual list of them.
243	*
244	* For local functions, we have to detect them manually by simply looking for
245	* the lack of a return instruction.
246	*/
247	static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
248	int recursion)
249	{
250	int i;
251	struct instruction *insn;
252	bool empty = true;
253
254	#define NORETURN(func) __stringify(func),
255	static const char * const global_noreturns[] = {
256	#include "noreturns.h"
257	};
258	#undef NORETURN
259
260	if (!func)
261	return false;
262
263	if (func->bind == STB_GLOBAL || func->bind == STB_WEAK) {
264	if (is_rust_noreturn(func))
265	return true;
266
267	for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
268	if (!strcmp(func->name, global_noreturns[i]))
269	return true;
270	}
271
272	if (func->bind == STB_WEAK)
273	return false;
274
275	if (!func->len)
276	return false;
277
278	insn = find_insn(file, sec: func->sec, offset: func->offset);
279	if (!insn || !insn_func(insn))
280	return false;
281
282	func_for_each_insn(file, func, insn) {
283	empty = false;
284
285	if (insn->type == INSN_RETURN)
286	return false;
287	}
288
289	if (empty)
290	return false;
291
292	/*
293	* A function can have a sibling call instead of a return. In that
294	* case, the function's dead-end status depends on whether the target
295	* of the sibling call returns.
296	*/
297	func_for_each_insn(file, func, insn) {
298	if (is_sibling_call(insn)) {
299	struct instruction *dest = insn->jump_dest;
300
301	if (!dest)
302	/* sibling call to another file */
303	return false;
304
305	/* local sibling call */
306	if (recursion == 5) {
307	/*
308	* Infinite recursion: two functions have
309	* sibling calls to each other. This is a very
310	* rare case. It means they aren't dead ends.
311	*/
312	return false;
313	}
314
315	return __dead_end_function(file, func: insn_func(dest), recursion: recursion+1);
316	}
317	}
318
319	return true;
320	}
321
322	static bool dead_end_function(struct objtool_file *file, struct symbol *func)
323	{
324	return __dead_end_function(file, func, recursion: 0);
325	}
326
327	static void init_cfi_state(struct cfi_state *cfi)
328	{
329	int i;
330
331	for (i = 0; i < CFI_NUM_REGS; i++) {
332	cfi->regs[i].base = CFI_UNDEFINED;
333	cfi->vals[i].base = CFI_UNDEFINED;
334	}
335	cfi->cfa.base = CFI_UNDEFINED;
336	cfi->drap_reg = CFI_UNDEFINED;
337	cfi->drap_offset = -1;
338	}
339
340	static void init_insn_state(struct objtool_file *file, struct insn_state *state,
341	struct section *sec)
342	{
343	memset(state, 0, sizeof(*state));
344	init_cfi_state(cfi: &state->cfi);
345
346	if (opts.noinstr && sec)
347	state->noinstr = sec->noinstr;
348	}
349
350	static struct cfi_state *cfi_alloc(void)
351	{
352	struct cfi_state *cfi = calloc(1, sizeof(struct cfi_state));
353	if (!cfi) {
354	ERROR_GLIBC("calloc");
355	exit(1);
356	}
357	nr_cfi++;
358	return cfi;
359	}
360
361	static int cfi_bits;
362	static struct hlist_head *cfi_hash;
363
364	static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2)
365	{
366	return memcmp((void *)cfi1 + sizeof(cfi1->hash),
367	(void *)cfi2 + sizeof(cfi2->hash),
368	sizeof(struct cfi_state) - sizeof(struct hlist_node));
369	}
370
371	static inline u32 cfi_key(struct cfi_state *cfi)
372	{
373	return jhash((void *)cfi + sizeof(cfi->hash),
374	sizeof(*cfi) - sizeof(cfi->hash), 0);
375	}
376
377	static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi)
378	{
379	struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
380	struct cfi_state *obj;
381
382	hlist_for_each_entry(obj, head, hash) {
383	if (!cficmp(cfi1: cfi, cfi2: obj)) {
384	nr_cfi_cache++;
385	return obj;
386	}
387	}
388
389	obj = cfi_alloc();
390	*obj = *cfi;
391	hlist_add_head(n: &obj->hash, h: head);
392
393	return obj;
394	}
395
396	static void cfi_hash_add(struct cfi_state *cfi)
397	{
398	struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
399
400	hlist_add_head(n: &cfi->hash, h: head);
401	}
402
403	static void *cfi_hash_alloc(unsigned long size)
404	{
405	cfi_bits = max(10, ilog2(size));
406	cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits,
407	PROT_READ|PROT_WRITE,
408	MAP_PRIVATE|MAP_ANON, -1, 0);
409	if (cfi_hash == (void *)-1L) {
410	ERROR_GLIBC("mmap fail cfi_hash");
411	cfi_hash = NULL;
412	} else if (opts.stats) {
413	printf("cfi_bits: %d\n", cfi_bits);
414	}
415
416	return cfi_hash;
417	}
418
419	static unsigned long nr_insns;
420	static unsigned long nr_insns_visited;
421
422	/*
423	* Call the arch-specific instruction decoder for all the instructions and add
424	* them to the global instruction list.
425	*/
426	static int decode_instructions(struct objtool_file *file)
427	{
428	struct section *sec;
429	struct symbol *func;
430	unsigned long offset;
431	struct instruction *insn;
432	int ret;
433
434	for_each_sec(file, sec) {
435	struct instruction *insns = NULL;
436	u8 prev_len = 0;
437	u8 idx = 0;
438
439	if (!(sec->sh.sh_flags & SHF_EXECINSTR))
440	continue;
441
442	if (strcmp(sec->name, ".altinstr_replacement") &&
443	strcmp(sec->name, ".altinstr_aux") &&
444	strncmp(sec->name, ".discard.", 9))
445	sec->text = true;
446
447	if (!strcmp(sec->name, ".noinstr.text") ||
448	!strcmp(sec->name, ".entry.text") ||
449	!strcmp(sec->name, ".cpuidle.text") ||
450	!strncmp(sec->name, ".text..__x86.", 13))
451	sec->noinstr = true;
452
453	/*
454	* .init.text code is ran before userspace and thus doesn't
455	* strictly need retpolines, except for modules which are
456	* loaded late, they very much do need retpoline in their
457	* .init.text
458	*/
459	if (!strcmp(sec->name, ".init.text") && !opts.module)
460	sec->init = true;
461
462	for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
463	if (!insns || idx == INSN_CHUNK_MAX) {
464	insns = calloc(sizeof(*insn), INSN_CHUNK_SIZE);
465	if (!insns) {
466	ERROR_GLIBC("calloc");
467	return -1;
468	}
469	idx = 0;
470	} else {
471	idx++;
472	}
473	insn = &insns[idx];
474	insn->idx = idx;
475
476	INIT_LIST_HEAD(list: &insn->call_node);
477	insn->sec = sec;
478	insn->offset = offset;
479	insn->prev_len = prev_len;
480
481	ret = arch_decode_instruction(file, sec, offset,
482	sec->sh.sh_size - offset,
483	insn);
484	if (ret)
485	return ret;
486
487	prev_len = insn->len;
488
489	/*
490	* By default, "ud2" is a dead end unless otherwise
491	* annotated, because GCC 7 inserts it for certain
492	* divide-by-zero cases.
493	*/
494	if (insn->type == INSN_BUG)
495	insn->dead_end = true;
496
497	hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
498	nr_insns++;
499	}
500
501	sec_for_each_sym(sec, func) {
502	if (func->type != STT_NOTYPE && func->type != STT_FUNC)
503	continue;
504
505	if (func->offset == sec->sh.sh_size) {
506	/* Heuristic: likely an "end" symbol */
507	if (func->type == STT_NOTYPE)
508	continue;
509	ERROR("%s(): STT_FUNC at end of section", func->name);
510	return -1;
511	}
512
513	if (func->embedded_insn || func->alias != func)
514	continue;
515
516	if (!find_insn(file, sec, offset: func->offset)) {
517	ERROR("%s(): can't find starting instruction", func->name);
518	return -1;
519	}
520
521	sym_for_each_insn(file, func, insn) {
522	insn->sym = func;
523	if (func->type == STT_FUNC &&
524	insn->type == INSN_ENDBR &&
525	list_empty(head: &insn->call_node)) {
526	if (insn->offset == func->offset) {
527	list_add_tail(new: &insn->call_node, head: &file->endbr_list);
528	file->nr_endbr++;
529	} else {
530	file->nr_endbr_int++;
531	}
532	}
533	}
534	}
535	}
536
537	if (opts.stats)
538	printf("nr_insns: %lu\n", nr_insns);
539
540	return 0;
541	}
542
543	/*
544	* Read the pv_ops[] .data table to find the static initialized values.
545	*/
546	static int add_pv_ops(struct objtool_file *file, const char *symname)
547	{
548	struct symbol *sym, *func;
549	unsigned long off, end;
550	struct reloc *reloc;
551	int idx;
552
553	sym = find_symbol_by_name(file->elf, symname);
554	if (!sym)
555	return 0;
556
557	off = sym->offset;
558	end = off + sym->len;
559	for (;;) {
560	reloc = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off);
561	if (!reloc)
562	break;
563
564	idx = (reloc_offset(reloc) - sym->offset) / sizeof(unsigned long);
565
566	func = reloc->sym;
567	if (func->type == STT_SECTION)
568	func = find_symbol_by_offset(reloc->sym->sec,
569	reloc_addend(reloc));
570	if (!func) {
571	ERROR_FUNC(reloc->sym->sec, reloc_addend(reloc),
572	"can't find func at %s[%d]", symname, idx);
573	return -1;
574	}
575
576	if (objtool_pv_add(file, idx, func))
577	return -1;
578
579	off = reloc_offset(reloc) + 1;
580	if (off > end)
581	break;
582	}
583
584	return 0;
585	}
586
587	/*
588	* Allocate and initialize file->pv_ops[].
589	*/
590	static int init_pv_ops(struct objtool_file *file)
591	{
592	static const char *pv_ops_tables[] = {
593	"pv_ops",
594	"xen_cpu_ops",
595	"xen_irq_ops",
596	"xen_mmu_ops",
597	NULL,
598	};
599	const char *pv_ops;
600	struct symbol *sym;
601	int idx, nr, ret;
602
603	if (!opts.noinstr)
604	return 0;
605
606	file->pv_ops = NULL;
607
608	sym = find_symbol_by_name(file->elf, "pv_ops");
609	if (!sym)
610	return 0;
611
612	nr = sym->len / sizeof(unsigned long);
613	file->pv_ops = calloc(sizeof(struct pv_state), nr);
614	if (!file->pv_ops) {
615	ERROR_GLIBC("calloc");
616	return -1;
617	}
618
619	for (idx = 0; idx < nr; idx++)
620	INIT_LIST_HEAD(list: &file->pv_ops[idx].targets);
621
622	for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++) {
623	ret = add_pv_ops(file, symname: pv_ops);
624	if (ret)
625	return ret;
626	}
627
628	return 0;
629	}
630
631	static int create_static_call_sections(struct objtool_file *file)
632	{
633	struct static_call_site *site;
634	struct section *sec;
635	struct instruction *insn;
636	struct symbol *key_sym;
637	char *key_name, *tmp;
638	int idx;
639
640	sec = find_section_by_name(file->elf, ".static_call_sites");
641	if (sec) {
642	INIT_LIST_HEAD(list: &file->static_call_list);
643	WARN("file already has .static_call_sites section, skipping");
644	return 0;
645	}
646
647	if (list_empty(head: &file->static_call_list))
648	return 0;
649
650	idx = 0;
651	list_for_each_entry(insn, &file->static_call_list, call_node)
652	idx++;
653
654	sec = elf_create_section_pair(file->elf, ".static_call_sites",
655	sizeof(*site), idx, idx * 2);
656	if (!sec)
657	return -1;
658
659	/* Allow modules to modify the low bits of static_call_site::key */
660	sec->sh.sh_flags |= SHF_WRITE;
661
662	idx = 0;
663	list_for_each_entry(insn, &file->static_call_list, call_node) {
664
665	/* populate reloc for 'addr' */
666	if (!elf_init_reloc_text_sym(file->elf, sec,
667	idx * sizeof(*site), idx * 2,
668	insn->sec, insn->offset))
669	return -1;
670
671	/* find key symbol */
672	key_name = strdup(insn_call_dest(insn)->name);
673	if (!key_name) {
674	ERROR_GLIBC("strdup");
675	return -1;
676	}
677	if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
678	STATIC_CALL_TRAMP_PREFIX_LEN)) {
679	ERROR("static_call: trampoline name malformed: %s", key_name);
680	return -1;
681	}
682	tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
683	memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
684
685	key_sym = find_symbol_by_name(file->elf, tmp);
686	if (!key_sym) {
687	if (!opts.module) {
688	ERROR("static_call: can't find static_call_key symbol: %s", tmp);
689	return -1;
690	}
691
692	/*
693	* For modules(), the key might not be exported, which
694	* means the module can make static calls but isn't
695	* allowed to change them.
696	*
697	* In that case we temporarily set the key to be the
698	* trampoline address. This is fixed up in
699	* static_call_add_module().
700	*/
701	key_sym = insn_call_dest(insn);
702	}
703
704	/* populate reloc for 'key' */
705	if (!elf_init_reloc_data_sym(file->elf, sec,
706	idx * sizeof(*site) + 4,
707	(idx * 2) + 1, key_sym,
708	is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
709	return -1;
710
711	idx++;
712	}
713
714	return 0;
715	}
716
717	static int create_retpoline_sites_sections(struct objtool_file *file)
718	{
719	struct instruction *insn;
720	struct section *sec;
721	int idx;
722
723	sec = find_section_by_name(file->elf, ".retpoline_sites");
724	if (sec) {
725	WARN("file already has .retpoline_sites, skipping");
726	return 0;
727	}
728
729	idx = 0;
730	list_for_each_entry(insn, &file->retpoline_call_list, call_node)
731	idx++;
732
733	if (!idx)
734	return 0;
735
736	sec = elf_create_section_pair(file->elf, ".retpoline_sites",
737	sizeof(int), idx, idx);
738	if (!sec)
739	return -1;
740
741	idx = 0;
742	list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
743
744	if (!elf_init_reloc_text_sym(file->elf, sec,
745	idx * sizeof(int), idx,
746	insn->sec, insn->offset))
747	return -1;
748
749	idx++;
750	}
751
752	return 0;
753	}
754
755	static int create_return_sites_sections(struct objtool_file *file)
756	{
757	struct instruction *insn;
758	struct section *sec;
759	int idx;
760
761	sec = find_section_by_name(file->elf, ".return_sites");
762	if (sec) {
763	WARN("file already has .return_sites, skipping");
764	return 0;
765	}
766
767	idx = 0;
768	list_for_each_entry(insn, &file->return_thunk_list, call_node)
769	idx++;
770
771	if (!idx)
772	return 0;
773
774	sec = elf_create_section_pair(file->elf, ".return_sites",
775	sizeof(int), idx, idx);
776	if (!sec)
777	return -1;
778
779	idx = 0;
780	list_for_each_entry(insn, &file->return_thunk_list, call_node) {
781
782	if (!elf_init_reloc_text_sym(file->elf, sec,
783	idx * sizeof(int), idx,
784	insn->sec, insn->offset))
785	return -1;
786
787	idx++;
788	}
789
790	return 0;
791	}
792
793	static int create_ibt_endbr_seal_sections(struct objtool_file *file)
794	{
795	struct instruction *insn;
796	struct section *sec;
797	int idx;
798
799	sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
800	if (sec) {
801	WARN("file already has .ibt_endbr_seal, skipping");
802	return 0;
803	}
804
805	idx = 0;
806	list_for_each_entry(insn, &file->endbr_list, call_node)
807	idx++;
808
809	if (opts.stats) {
810	printf("ibt: ENDBR at function start: %d\n", file->nr_endbr);
811	printf("ibt: ENDBR inside functions: %d\n", file->nr_endbr_int);
812	printf("ibt: superfluous ENDBR: %d\n", idx);
813	}
814
815	if (!idx)
816	return 0;
817
818	sec = elf_create_section_pair(file->elf, ".ibt_endbr_seal",
819	sizeof(int), idx, idx);
820	if (!sec)
821	return -1;
822
823	idx = 0;
824	list_for_each_entry(insn, &file->endbr_list, call_node) {
825
826	int *site = (int *)sec->data->d_buf + idx;
827	struct symbol *sym = insn->sym;
828	*site = 0;
829
830	if (opts.module && sym && sym->type == STT_FUNC &&
831	insn->offset == sym->offset &&
832	(!strcmp(sym->name, "init_module") ||
833	!strcmp(sym->name, "cleanup_module"))) {
834	ERROR("%s(): Magic init_module() function name is deprecated, use module_init(fn) instead",
835	sym->name);
836	return -1;
837	}
838
839	if (!elf_init_reloc_text_sym(file->elf, sec,
840	idx * sizeof(int), idx,
841	insn->sec, insn->offset))
842	return -1;
843
844	idx++;
845	}
846
847	return 0;
848	}
849
850	static int create_cfi_sections(struct objtool_file *file)
851	{
852	struct section *sec;
853	struct symbol *sym;
854	int idx;
855
856	sec = find_section_by_name(file->elf, ".cfi_sites");
857	if (sec) {
858	INIT_LIST_HEAD(list: &file->call_list);
859	WARN("file already has .cfi_sites section, skipping");
860	return 0;
861	}
862
863	idx = 0;
864	for_each_sym(file, sym) {
865	if (sym->type != STT_FUNC)
866	continue;
867
868	if (strncmp(sym->name, "__cfi_", 6))
869	continue;
870
871	idx++;
872	}
873
874	sec = elf_create_section_pair(file->elf, ".cfi_sites",
875	sizeof(unsigned int), idx, idx);
876	if (!sec)
877	return -1;
878
879	idx = 0;
880	for_each_sym(file, sym) {
881	if (sym->type != STT_FUNC)
882	continue;
883
884	if (strncmp(sym->name, "__cfi_", 6))
885	continue;
886
887	if (!elf_init_reloc_text_sym(file->elf, sec,
888	idx * sizeof(unsigned int), idx,
889	sym->sec, sym->offset))
890	return -1;
891
892	idx++;
893	}
894
895	return 0;
896	}
897
898	static int create_mcount_loc_sections(struct objtool_file *file)
899	{
900	size_t addr_size = elf_addr_size(file->elf);
901	struct instruction *insn;
902	struct section *sec;
903	int idx;
904
905	sec = find_section_by_name(file->elf, "__mcount_loc");
906	if (sec) {
907	INIT_LIST_HEAD(list: &file->mcount_loc_list);
908	WARN("file already has __mcount_loc section, skipping");
909	return 0;
910	}
911
912	if (list_empty(head: &file->mcount_loc_list))
913	return 0;
914
915	idx = 0;
916	list_for_each_entry(insn, &file->mcount_loc_list, call_node)
917	idx++;
918
919	sec = elf_create_section_pair(file->elf, "__mcount_loc", addr_size,
920	idx, idx);
921	if (!sec)
922	return -1;
923
924	sec->sh.sh_addralign = addr_size;
925
926	idx = 0;
927	list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
928
929	struct reloc *reloc;
930
931	reloc = elf_init_reloc_text_sym(file->elf, sec, idx * addr_size, idx,
932	insn->sec, insn->offset);
933	if (!reloc)
934	return -1;
935
936	set_reloc_type(file->elf, reloc, addr_size == 8 ? R_ABS64 : R_ABS32);
937
938	idx++;
939	}
940
941	return 0;
942	}
943
944	static int create_direct_call_sections(struct objtool_file *file)
945	{
946	struct instruction *insn;
947	struct section *sec;
948	int idx;
949
950	sec = find_section_by_name(file->elf, ".call_sites");
951	if (sec) {
952	INIT_LIST_HEAD(list: &file->call_list);
953	WARN("file already has .call_sites section, skipping");
954	return 0;
955	}
956
957	if (list_empty(head: &file->call_list))
958	return 0;
959
960	idx = 0;
961	list_for_each_entry(insn, &file->call_list, call_node)
962	idx++;
963
964	sec = elf_create_section_pair(file->elf, ".call_sites",
965	sizeof(unsigned int), idx, idx);
966	if (!sec)
967	return -1;
968
969	idx = 0;
970	list_for_each_entry(insn, &file->call_list, call_node) {
971
972	if (!elf_init_reloc_text_sym(file->elf, sec,
973	idx * sizeof(unsigned int), idx,
974	insn->sec, insn->offset))
975	return -1;
976
977	idx++;
978	}
979
980	return 0;
981	}
982
983	/*
984	* Warnings shouldn't be reported for ignored functions.
985	*/
986	static int add_ignores(struct objtool_file *file)
987	{
988	struct section *rsec;
989	struct symbol *func;
990	struct reloc *reloc;
991
992	rsec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
993	if (!rsec)
994	return 0;
995
996	for_each_reloc(rsec, reloc) {
997	switch (reloc->sym->type) {
998	case STT_FUNC:
999	func = reloc->sym;
1000	break;
1001
1002	case STT_SECTION:
1003	func = find_func_by_offset(reloc->sym->sec, reloc_addend(reloc));
1004	if (!func)
1005	continue;
1006	break;
1007
1008	default:
1009	ERROR("unexpected relocation symbol type in %s: %d",
1010	rsec->name, reloc->sym->type);
1011	return -1;
1012	}
1013
1014	func->ignore = true;
1015	if (func->cfunc)
1016	func->cfunc->ignore = true;
1017	}
1018
1019	return 0;
1020	}
1021
1022	/*
1023	* This is a whitelist of functions that is allowed to be called with AC set.
1024	* The list is meant to be minimal and only contains compiler instrumentation
1025	* ABI and a few functions used to implement *_{to,from}_user() functions.
1026	*
1027	* These functions must not directly change AC, but may PUSHF/POPF.
1028	*/
1029	static const char *uaccess_safe_builtin[] = {
1030	/* KASAN */
1031	"kasan_report",
1032	"kasan_check_range",
1033	/* KASAN out-of-line */
1034	"__asan_loadN_noabort",
1035	"__asan_load1_noabort",
1036	"__asan_load2_noabort",
1037	"__asan_load4_noabort",
1038	"__asan_load8_noabort",
1039	"__asan_load16_noabort",
1040	"__asan_storeN_noabort",
1041	"__asan_store1_noabort",
1042	"__asan_store2_noabort",
1043	"__asan_store4_noabort",
1044	"__asan_store8_noabort",
1045	"__asan_store16_noabort",
1046	"__kasan_check_read",
1047	"__kasan_check_write",
1048	/* KASAN in-line */
1049	"__asan_report_load_n_noabort",
1050	"__asan_report_load1_noabort",
1051	"__asan_report_load2_noabort",
1052	"__asan_report_load4_noabort",
1053	"__asan_report_load8_noabort",
1054	"__asan_report_load16_noabort",
1055	"__asan_report_store_n_noabort",
1056	"__asan_report_store1_noabort",
1057	"__asan_report_store2_noabort",
1058	"__asan_report_store4_noabort",
1059	"__asan_report_store8_noabort",
1060	"__asan_report_store16_noabort",
1061	/* KCSAN */
1062	"__kcsan_check_access",
1063	"__kcsan_mb",
1064	"__kcsan_wmb",
1065	"__kcsan_rmb",
1066	"__kcsan_release",
1067	"kcsan_found_watchpoint",
1068	"kcsan_setup_watchpoint",
1069	"kcsan_check_scoped_accesses",
1070	"kcsan_disable_current",
1071	"kcsan_enable_current_nowarn",
1072	/* KCSAN/TSAN */
1073	"__tsan_func_entry",
1074	"__tsan_func_exit",
1075	"__tsan_read_range",
1076	"__tsan_write_range",
1077	"__tsan_read1",
1078	"__tsan_read2",
1079	"__tsan_read4",
1080	"__tsan_read8",
1081	"__tsan_read16",
1082	"__tsan_write1",
1083	"__tsan_write2",
1084	"__tsan_write4",
1085	"__tsan_write8",
1086	"__tsan_write16",
1087	"__tsan_read_write1",
1088	"__tsan_read_write2",
1089	"__tsan_read_write4",
1090	"__tsan_read_write8",
1091	"__tsan_read_write16",
1092	"__tsan_volatile_read1",
1093	"__tsan_volatile_read2",
1094	"__tsan_volatile_read4",
1095	"__tsan_volatile_read8",
1096	"__tsan_volatile_read16",
1097	"__tsan_volatile_write1",
1098	"__tsan_volatile_write2",
1099	"__tsan_volatile_write4",
1100	"__tsan_volatile_write8",
1101	"__tsan_volatile_write16",
1102	"__tsan_atomic8_load",
1103	"__tsan_atomic16_load",
1104	"__tsan_atomic32_load",
1105	"__tsan_atomic64_load",
1106	"__tsan_atomic8_store",
1107	"__tsan_atomic16_store",
1108	"__tsan_atomic32_store",
1109	"__tsan_atomic64_store",
1110	"__tsan_atomic8_exchange",
1111	"__tsan_atomic16_exchange",
1112	"__tsan_atomic32_exchange",
1113	"__tsan_atomic64_exchange",
1114	"__tsan_atomic8_fetch_add",
1115	"__tsan_atomic16_fetch_add",
1116	"__tsan_atomic32_fetch_add",
1117	"__tsan_atomic64_fetch_add",
1118	"__tsan_atomic8_fetch_sub",
1119	"__tsan_atomic16_fetch_sub",
1120	"__tsan_atomic32_fetch_sub",
1121	"__tsan_atomic64_fetch_sub",
1122	"__tsan_atomic8_fetch_and",
1123	"__tsan_atomic16_fetch_and",
1124	"__tsan_atomic32_fetch_and",
1125	"__tsan_atomic64_fetch_and",
1126	"__tsan_atomic8_fetch_or",
1127	"__tsan_atomic16_fetch_or",
1128	"__tsan_atomic32_fetch_or",
1129	"__tsan_atomic64_fetch_or",
1130	"__tsan_atomic8_fetch_xor",
1131	"__tsan_atomic16_fetch_xor",
1132	"__tsan_atomic32_fetch_xor",
1133	"__tsan_atomic64_fetch_xor",
1134	"__tsan_atomic8_fetch_nand",
1135	"__tsan_atomic16_fetch_nand",
1136	"__tsan_atomic32_fetch_nand",
1137	"__tsan_atomic64_fetch_nand",
1138	"__tsan_atomic8_compare_exchange_strong",
1139	"__tsan_atomic16_compare_exchange_strong",
1140	"__tsan_atomic32_compare_exchange_strong",
1141	"__tsan_atomic64_compare_exchange_strong",
1142	"__tsan_atomic8_compare_exchange_weak",
1143	"__tsan_atomic16_compare_exchange_weak",
1144	"__tsan_atomic32_compare_exchange_weak",
1145	"__tsan_atomic64_compare_exchange_weak",
1146	"__tsan_atomic8_compare_exchange_val",
1147	"__tsan_atomic16_compare_exchange_val",
1148	"__tsan_atomic32_compare_exchange_val",
1149	"__tsan_atomic64_compare_exchange_val",
1150	"__tsan_atomic_thread_fence",
1151	"__tsan_atomic_signal_fence",
1152	"__tsan_unaligned_read16",
1153	"__tsan_unaligned_write16",
1154	/* KCOV */
1155	"write_comp_data",
1156	"check_kcov_mode",
1157	"__sanitizer_cov_trace_pc",
1158	"__sanitizer_cov_trace_const_cmp1",
1159	"__sanitizer_cov_trace_const_cmp2",
1160	"__sanitizer_cov_trace_const_cmp4",
1161	"__sanitizer_cov_trace_const_cmp8",
1162	"__sanitizer_cov_trace_cmp1",
1163	"__sanitizer_cov_trace_cmp2",
1164	"__sanitizer_cov_trace_cmp4",
1165	"__sanitizer_cov_trace_cmp8",
1166	"__sanitizer_cov_trace_switch",
1167	/* KMSAN */
1168	"kmsan_copy_to_user",
1169	"kmsan_disable_current",
1170	"kmsan_enable_current",
1171	"kmsan_report",
1172	"kmsan_unpoison_entry_regs",
1173	"kmsan_unpoison_memory",
1174	"__msan_chain_origin",
1175	"__msan_get_context_state",
1176	"__msan_instrument_asm_store",
1177	"__msan_metadata_ptr_for_load_1",
1178	"__msan_metadata_ptr_for_load_2",
1179	"__msan_metadata_ptr_for_load_4",
1180	"__msan_metadata_ptr_for_load_8",
1181	"__msan_metadata_ptr_for_load_n",
1182	"__msan_metadata_ptr_for_store_1",
1183	"__msan_metadata_ptr_for_store_2",
1184	"__msan_metadata_ptr_for_store_4",
1185	"__msan_metadata_ptr_for_store_8",
1186	"__msan_metadata_ptr_for_store_n",
1187	"__msan_poison_alloca",
1188	"__msan_warning",
1189	/* UBSAN */
1190	"ubsan_type_mismatch_common",
1191	"__ubsan_handle_type_mismatch",
1192	"__ubsan_handle_type_mismatch_v1",
1193	"__ubsan_handle_shift_out_of_bounds",
1194	"__ubsan_handle_load_invalid_value",
1195	/* STACKLEAK */
1196	"stackleak_track_stack",
1197	/* TRACE_BRANCH_PROFILING */
1198	"ftrace_likely_update",
1199	/* STACKPROTECTOR */
1200	"__stack_chk_fail",
1201	/* misc */
1202	"csum_partial_copy_generic",
1203	"copy_mc_fragile",
1204	"copy_mc_fragile_handle_tail",
1205	"copy_mc_enhanced_fast_string",
1206	"rep_stos_alternative",
1207	"rep_movs_alternative",
1208	"__copy_user_nocache",
1209	NULL
1210	};
1211
1212	static void add_uaccess_safe(struct objtool_file *file)
1213	{
1214	struct symbol *func;
1215	const char **name;
1216
1217	if (!opts.uaccess)
1218	return;
1219
1220	for (name = uaccess_safe_builtin; *name; name++) {
1221	func = find_symbol_by_name(file->elf, *name);
1222	if (!func)
1223	continue;
1224
1225	func->uaccess_safe = true;
1226	}
1227	}
1228
1229	/*
1230	* Symbols that replace INSN_CALL_DYNAMIC, every (tail) call to such a symbol
1231	* will be added to the .retpoline_sites section.
1232	*/
1233	__weak bool arch_is_retpoline(struct symbol *sym)
1234	{
1235	return false;
1236	}
1237
1238	/*
1239	* Symbols that replace INSN_RETURN, every (tail) call to such a symbol
1240	* will be added to the .return_sites section.
1241	*/
1242	__weak bool arch_is_rethunk(struct symbol *sym)
1243	{
1244	return false;
1245	}
1246
1247	/*
1248	* Symbols that are embedded inside other instructions, because sometimes crazy
1249	* code exists. These are mostly ignored for validation purposes.
1250	*/
1251	__weak bool arch_is_embedded_insn(struct symbol *sym)
1252	{
1253	return false;
1254	}
1255
1256	static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
1257	{
1258	struct reloc *reloc;
1259
1260	if (insn->no_reloc)
1261	return NULL;
1262
1263	if (!file)
1264	return NULL;
1265
1266	reloc = find_reloc_by_dest_range(file->elf, insn->sec,
1267	insn->offset, insn->len);
1268	if (!reloc) {
1269	insn->no_reloc = 1;
1270	return NULL;
1271	}
1272
1273	return reloc;
1274	}
1275
1276	static void remove_insn_ops(struct instruction *insn)
1277	{
1278	struct stack_op *op, *next;
1279
1280	for (op = insn->stack_ops; op; op = next) {
1281	next = op->next;
1282	free(op);
1283	}
1284	insn->stack_ops = NULL;
1285	}
1286
1287	static int annotate_call_site(struct objtool_file *file,
1288	struct instruction *insn, bool sibling)
1289	{
1290	struct reloc *reloc = insn_reloc(file, insn);
1291	struct symbol *sym = insn_call_dest(insn);
1292
1293	if (!sym)
1294	sym = reloc->sym;
1295
1296	if (sym->static_call_tramp) {
1297	list_add_tail(new: &insn->call_node, head: &file->static_call_list);
1298	return 0;
1299	}
1300
1301	if (sym->retpoline_thunk) {
1302	list_add_tail(new: &insn->call_node, head: &file->retpoline_call_list);
1303	return 0;
1304	}
1305
1306	/*
1307	* Many compilers cannot disable KCOV or sanitizer calls with a function
1308	* attribute so they need a little help, NOP out any such calls from
1309	* noinstr text.
1310	*/
1311	if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
1312	if (reloc)
1313	set_reloc_type(file->elf, reloc, R_NONE);
1314
1315	if (elf_write_insn(file->elf, insn->sec,
1316	insn->offset, insn->len,
1317	sibling ? arch_ret_insn(insn->len)
1318	: arch_nop_insn(insn->len))) {
1319	return -1;
1320	}
1321
1322	insn->type = sibling ? INSN_RETURN : INSN_NOP;
1323
1324	if (sibling) {
1325	/*
1326	* We've replaced the tail-call JMP insn by two new
1327	* insn: RET; INT3, except we only have a single struct
1328	* insn here. Mark it retpoline_safe to avoid the SLS
1329	* warning, instead of adding another insn.
1330	*/
1331	insn->retpoline_safe = true;
1332	}
1333
1334	return 0;
1335	}
1336
1337	if (opts.mcount && sym->fentry) {
1338	if (sibling)
1339	WARN_INSN(insn, "tail call to __fentry__ !?!?");
1340	if (opts.mnop) {
1341	if (reloc)
1342	set_reloc_type(file->elf, reloc, R_NONE);
1343
1344	if (elf_write_insn(file->elf, insn->sec,
1345	insn->offset, insn->len,
1346	arch_nop_insn(insn->len))) {
1347	return -1;
1348	}
1349
1350	insn->type = INSN_NOP;
1351	}
1352
1353	list_add_tail(new: &insn->call_node, head: &file->mcount_loc_list);
1354	return 0;
1355	}
1356
1357	if (insn->type == INSN_CALL && !insn->sec->init &&
1358	!insn->_call_dest->embedded_insn)
1359	list_add_tail(new: &insn->call_node, head: &file->call_list);
1360
1361	if (!sibling && dead_end_function(file, func: sym))
1362	insn->dead_end = true;
1363
1364	return 0;
1365	}
1366
1367	static int add_call_dest(struct objtool_file *file, struct instruction *insn,
1368	struct symbol *dest, bool sibling)
1369	{
1370	insn->_call_dest = dest;
1371	if (!dest)
1372	return 0;
1373
1374	/*
1375	* Whatever stack impact regular CALLs have, should be undone
1376	* by the RETURN of the called function.
1377	*
1378	* Annotated intra-function calls retain the stack_ops but
1379	* are converted to JUMP, see read_intra_function_calls().
1380	*/
1381	remove_insn_ops(insn);
1382
1383	return annotate_call_site(file, insn, sibling);
1384	}
1385
1386	static int add_retpoline_call(struct objtool_file *file, struct instruction *insn)
1387	{
1388	/*
1389	* Retpoline calls/jumps are really dynamic calls/jumps in disguise,
1390	* so convert them accordingly.
1391	*/
1392	switch (insn->type) {
1393	case INSN_CALL:
1394	insn->type = INSN_CALL_DYNAMIC;
1395	break;
1396	case INSN_JUMP_UNCONDITIONAL:
1397	insn->type = INSN_JUMP_DYNAMIC;
1398	break;
1399	case INSN_JUMP_CONDITIONAL:
1400	insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
1401	break;
1402	default:
1403	return 0;
1404	}
1405
1406	insn->retpoline_safe = true;
1407
1408	/*
1409	* Whatever stack impact regular CALLs have, should be undone
1410	* by the RETURN of the called function.
1411	*
1412	* Annotated intra-function calls retain the stack_ops but
1413	* are converted to JUMP, see read_intra_function_calls().
1414	*/
1415	remove_insn_ops(insn);
1416
1417	return annotate_call_site(file, insn, sibling: false);
1418	}
1419
1420	static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
1421	{
1422	/*
1423	* Return thunk tail calls are really just returns in disguise,
1424	* so convert them accordingly.
1425	*/
1426	insn->type = INSN_RETURN;
1427	insn->retpoline_safe = true;
1428
1429	if (add)
1430	list_add_tail(new: &insn->call_node, head: &file->return_thunk_list);
1431	}
1432
1433	static bool is_first_func_insn(struct objtool_file *file,
1434	struct instruction *insn, struct symbol *sym)
1435	{
1436	if (insn->offset == sym->offset)
1437	return true;
1438
1439	/* Allow direct CALL/JMP past ENDBR */
1440	if (opts.ibt) {
1441	struct instruction *prev = prev_insn_same_sym(file, insn);
1442
1443	if (prev && prev->type == INSN_ENDBR &&
1444	insn->offset == sym->offset + prev->len)
1445	return true;
1446	}
1447
1448	return false;
1449	}
1450
1451	/*
1452	* A sibling call is a tail-call to another symbol -- to differentiate from a
1453	* recursive tail-call which is to the same symbol.
1454	*/
1455	static bool jump_is_sibling_call(struct objtool_file *file,
1456	struct instruction *from, struct instruction *to)
1457	{
1458	struct symbol *fs = from->sym;
1459	struct symbol *ts = to->sym;
1460
1461	/* Not a sibling call if from/to a symbol hole */
1462	if (!fs || !ts)
1463	return false;
1464
1465	/* Not a sibling call if not targeting the start of a symbol. */
1466	if (!is_first_func_insn(file, insn: to, sym: ts))
1467	return false;
1468
1469	/* Disallow sibling calls into STT_NOTYPE */
1470	if (ts->type == STT_NOTYPE)
1471	return false;
1472
1473	/* Must not be self to be a sibling */
1474	return fs->pfunc != ts->pfunc;
1475	}
1476
1477	/*
1478	* Find the destination instructions for all jumps.
1479	*/
1480	static int add_jump_destinations(struct objtool_file *file)
1481	{
1482	struct instruction *insn, *jump_dest;
1483	struct reloc *reloc;
1484	struct section *dest_sec;
1485	unsigned long dest_off;
1486	int ret;
1487
1488	for_each_insn(file, insn) {
1489	struct symbol *func = insn_func(insn);
1490
1491	if (insn->jump_dest) {
1492	/*
1493	* handle_group_alt() may have previously set
1494	* 'jump_dest' for some alternatives.
1495	*/
1496	continue;
1497	}
1498	if (!is_static_jump(insn))
1499	continue;
1500
1501	reloc = insn_reloc(file, insn);
1502	if (!reloc) {
1503	dest_sec = insn->sec;
1504	dest_off = arch_jump_destination(insn);
1505	} else if (reloc->sym->type == STT_SECTION) {
1506	dest_sec = reloc->sym->sec;
1507	dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
1508	} else if (reloc->sym->retpoline_thunk) {
1509	ret = add_retpoline_call(file, insn);
1510	if (ret)
1511	return ret;
1512	continue;
1513	} else if (reloc->sym->return_thunk) {
1514	add_return_call(file, insn, true);
1515	continue;
1516	} else if (func) {
1517	/*
1518	* External sibling call or internal sibling call with
1519	* STT_FUNC reloc.
1520	*/
1521	ret = add_call_dest(file, insn, reloc->sym, true);
1522	if (ret)
1523	return ret;
1524	continue;
1525	} else if (reloc->sym->sec->idx) {
1526	dest_sec = reloc->sym->sec;
1527	dest_off = reloc->sym->sym.st_value +
1528	arch_dest_reloc_offset(reloc_addend(reloc));
1529	} else {
1530	/* non-func asm code jumping to another file */
1531	continue;
1532	}
1533
1534	jump_dest = find_insn(file, dest_sec, dest_off);
1535	if (!jump_dest) {
1536	struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
1537
1538	/*
1539	* This is a special case for retbleed_untrain_ret().
1540	* It jumps to __x86_return_thunk(), but objtool
1541	* can't find the thunk's starting RET
1542	* instruction, because the RET is also in the
1543	* middle of another instruction. Objtool only
1544	* knows about the outer instruction.
1545	*/
1546	if (sym && sym->embedded_insn) {
1547	add_return_call(file, insn, false);
1548	continue;
1549	}
1550
1551	/*
1552	* GCOV/KCOV dead code can jump to the end of the
1553	* function/section.
1554	*/
1555	if (file->ignore_unreachables && func &&
1556	dest_sec == insn->sec &&
1557	dest_off == func->offset + func->len)
1558	continue;
1559
1560	ERROR_INSN(insn, "can't find jump dest instruction at %s+0x%lx",
1561	dest_sec->name, dest_off);
1562	return -1;
1563	}
1564
1565	/*
1566	* An intra-TU jump in retpoline.o might not have a relocation
1567	* for its jump dest, in which case the above
1568	* add_{retpoline,return}_call() didn't happen.
1569	*/
1570	if (jump_dest->sym && jump_dest->offset == jump_dest->sym->offset) {
1571	if (jump_dest->sym->retpoline_thunk) {
1572	ret = add_retpoline_call(file, insn);
1573	if (ret)
1574	return ret;
1575	continue;
1576	}
1577	if (jump_dest->sym->return_thunk) {
1578	add_return_call(file, insn, true);
1579	continue;
1580	}
1581	}
1582
1583	/*
1584	* Cross-function jump.
1585	*/
1586	if (func && insn_func(jump_dest) && func != insn_func(jump_dest)) {
1587
1588	/*
1589	* For GCC 8+, create parent/child links for any cold
1590	* subfunctions. This is _mostly_ redundant with a
1591	* similar initialization in read_symbols().
1592	*
1593	* If a function has aliases, we want the *first* such
1594	* function in the symbol table to be the subfunction's
1595	* parent. In that case we overwrite the
1596	* initialization done in read_symbols().
1597	*
1598	* However this code can't completely replace the
1599	* read_symbols() code because this doesn't detect the
1600	* case where the parent function's only reference to a
1601	* subfunction is through a jump table.
1602	*/
1603	if (!strstr(func->name, ".cold") &&
1604	strstr(insn_func(jump_dest)->name, ".cold")) {
1605	func->cfunc = insn_func(jump_dest);
1606	insn_func(jump_dest)->pfunc = func;
1607	}
1608	}
1609
1610	if (jump_is_sibling_call(file, insn, jump_dest)) {
1611	/*
1612	* Internal sibling call without reloc or with
1613	* STT_SECTION reloc.
1614	*/
1615	ret = add_call_dest(file, insn, insn_func(jump_dest), true);
1616	if (ret)
1617	return ret;
1618	continue;
1619	}
1620
1621	insn->jump_dest = jump_dest;
1622	}
1623
1624	return 0;
1625	}
1626
1627	static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
1628	{
1629	struct symbol *call_dest;
1630
1631	call_dest = find_func_by_offset(sec, offset);
1632	if (!call_dest)
1633	call_dest = find_symbol_by_offset(sec, offset);
1634
1635	return call_dest;
1636	}
1637
1638	/*
1639	* Find the destination instructions for all calls.
1640	*/
1641	static int add_call_destinations(struct objtool_file *file)
1642	{
1643	struct instruction *insn;
1644	unsigned long dest_off;
1645	struct symbol *dest;
1646	struct reloc *reloc;
1647	int ret;
1648
1649	for_each_insn(file, insn) {
1650	struct symbol *func = insn_func(insn);
1651	if (insn->type != INSN_CALL)
1652	continue;
1653
1654	reloc = insn_reloc(file, insn);
1655	if (!reloc) {
1656	dest_off = arch_jump_destination(insn);
1657	dest = find_call_destination(insn->sec, dest_off);
1658
1659	ret = add_call_dest(file, insn, dest, false);
1660	if (ret)
1661	return ret;
1662
1663	if (func && func->ignore)
1664	continue;
1665
1666	if (!insn_call_dest(insn)) {
1667	ERROR_INSN(insn, "unannotated intra-function call");
1668	return -1;
1669	}
1670
1671	if (func && insn_call_dest(insn)->type != STT_FUNC) {
1672	ERROR_INSN(insn, "unsupported call to non-function");
1673	return -1;
1674	}
1675
1676	} else if (reloc->sym->type == STT_SECTION) {
1677	dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
1678	dest = find_call_destination(reloc->sym->sec, dest_off);
1679	if (!dest) {
1680	ERROR_INSN(insn, "can't find call dest symbol at %s+0x%lx",
1681	reloc->sym->sec->name, dest_off);
1682	return -1;
1683	}
1684
1685	ret = add_call_dest(file, insn, dest, false);
1686	if (ret)
1687	return ret;
1688
1689	} else if (reloc->sym->retpoline_thunk) {
1690	ret = add_retpoline_call(file, insn);
1691	if (ret)
1692	return ret;
1693
1694	} else {
1695	ret = add_call_dest(file, insn, reloc->sym, false);
1696	if (ret)
1697	return ret;
1698	}
1699	}
1700
1701	return 0;
1702	}
1703
1704	/*
1705	* The .alternatives section requires some extra special care over and above
1706	* other special sections because alternatives are patched in place.
1707	*/
1708	static int handle_group_alt(struct objtool_file *file,
1709	struct special_alt *special_alt,
1710	struct instruction *orig_insn,
1711	struct instruction **new_insn)
1712	{
1713	struct instruction *last_new_insn = NULL, *insn, *nop = NULL;
1714	struct alt_group *orig_alt_group, *new_alt_group;
1715	unsigned long dest_off;
1716
1717	orig_alt_group = orig_insn->alt_group;
1718	if (!orig_alt_group) {
1719	struct instruction *last_orig_insn = NULL;
1720
1721	orig_alt_group = calloc(1, sizeof(*orig_alt_group));
1722	if (!orig_alt_group) {
1723	ERROR_GLIBC("calloc");
1724	return -1;
1725	}
1726	orig_alt_group->cfi = calloc(special_alt->orig_len,
1727	sizeof(struct cfi_state *));
1728	if (!orig_alt_group->cfi) {
1729	ERROR_GLIBC("calloc");
1730	return -1;
1731	}
1732
1733	insn = orig_insn;
1734	sec_for_each_insn_from(file, insn) {
1735	if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
1736	break;
1737
1738	insn->alt_group = orig_alt_group;
1739	last_orig_insn = insn;
1740	}
1741	orig_alt_group->orig_group = NULL;
1742	orig_alt_group->first_insn = orig_insn;
1743	orig_alt_group->last_insn = last_orig_insn;
1744	orig_alt_group->nop = NULL;
1745	orig_alt_group->ignore = orig_insn->ignore_alts;
1746	} else {
1747	if (orig_alt_group->last_insn->offset + orig_alt_group->last_insn->len -
1748	orig_alt_group->first_insn->offset != special_alt->orig_len) {
1749	ERROR_INSN(orig_insn, "weirdly overlapping alternative! %ld != %d",
1750	orig_alt_group->last_insn->offset +
1751	orig_alt_group->last_insn->len -
1752	orig_alt_group->first_insn->offset,
1753	special_alt->orig_len);
1754	return -1;
1755	}
1756	}
1757
1758	new_alt_group = calloc(1, sizeof(*new_alt_group));
1759	if (!new_alt_group) {
1760	ERROR_GLIBC("calloc");
1761	return -1;
1762	}
1763
1764	if (special_alt->new_len < special_alt->orig_len) {
1765	/*
1766	* Insert a fake nop at the end to make the replacement
1767	* alt_group the same size as the original. This is needed to
1768	* allow propagate_alt_cfi() to do its magic. When the last
1769	* instruction affects the stack, the instruction after it (the
1770	* nop) will propagate the new state to the shared CFI array.
1771	*/
1772	nop = calloc(1, sizeof(*nop));
1773	if (!nop) {
1774	ERROR_GLIBC("calloc");
1775	return -1;
1776	}
1777	memset(nop, 0, sizeof(*nop));
1778
1779	nop->sec = special_alt->new_sec;
1780	nop->offset = special_alt->new_off + special_alt->new_len;
1781	nop->len = special_alt->orig_len - special_alt->new_len;
1782	nop->type = INSN_NOP;
1783	nop->sym = orig_insn->sym;
1784	nop->alt_group = new_alt_group;
1785	}
1786
1787	if (!special_alt->new_len) {
1788	*new_insn = nop;
1789	goto end;
1790	}
1791
1792	insn = *new_insn;
1793	sec_for_each_insn_from(file, insn) {
1794	struct reloc *alt_reloc;
1795
1796	if (insn->offset >= special_alt->new_off + special_alt->new_len)
1797	break;
1798
1799	last_new_insn = insn;
1800
1801	insn->sym = orig_insn->sym;
1802	insn->alt_group = new_alt_group;
1803
1804	/*
1805	* Since alternative replacement code is copy/pasted by the
1806	* kernel after applying relocations, generally such code can't
1807	* have relative-address relocation references to outside the
1808	* .altinstr_replacement section, unless the arch's
1809	* alternatives code can adjust the relative offsets
1810	* accordingly.
1811	*/
1812	alt_reloc = insn_reloc(file, insn);
1813	if (alt_reloc && arch_pc_relative_reloc(alt_reloc) &&
1814	!arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
1815
1816	ERROR_INSN(insn, "unsupported relocation in alternatives section");
1817	return -1;
1818	}
1819
1820	if (!is_static_jump(insn))
1821	continue;
1822
1823	if (!insn->immediate)
1824	continue;
1825
1826	dest_off = arch_jump_destination(insn);
1827	if (dest_off == special_alt->new_off + special_alt->new_len) {
1828	insn->jump_dest = next_insn_same_sec(file, insn: orig_alt_group->last_insn);
1829	if (!insn->jump_dest) {
1830	ERROR_INSN(insn, "can't find alternative jump destination");
1831	return -1;
1832	}
1833	}
1834	}
1835
1836	if (!last_new_insn) {
1837	ERROR_FUNC(special_alt->new_sec, special_alt->new_off,
1838	"can't find last new alternative instruction");
1839	return -1;
1840	}
1841
1842	end:
1843	new_alt_group->orig_group = orig_alt_group;
1844	new_alt_group->first_insn = *new_insn;
1845	new_alt_group->last_insn = last_new_insn;
1846	new_alt_group->nop = nop;
1847	new_alt_group->ignore = (*new_insn)->ignore_alts;
1848	new_alt_group->cfi = orig_alt_group->cfi;
1849	return 0;
1850	}
1851
1852	/*
1853	* A jump table entry can either convert a nop to a jump or a jump to a nop.
1854	* If the original instruction is a jump, make the alt entry an effective nop
1855	* by just skipping the original instruction.
1856	*/
1857	static int handle_jump_alt(struct objtool_file *file,
1858	struct special_alt *special_alt,
1859	struct instruction *orig_insn,
1860	struct instruction **new_insn)
1861	{
1862	if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
1863	orig_insn->type != INSN_NOP) {
1864
1865	ERROR_INSN(orig_insn, "unsupported instruction at jump label");
1866	return -1;
1867	}
1868
1869	if (opts.hack_jump_label && special_alt->key_addend & 2) {
1870	struct reloc *reloc = insn_reloc(file, insn: orig_insn);
1871
1872	if (reloc)
1873	set_reloc_type(file->elf, reloc, R_NONE);
1874
1875	if (elf_write_insn(file->elf, orig_insn->sec,
1876	orig_insn->offset, orig_insn->len,
1877	arch_nop_insn(orig_insn->len))) {
1878	return -1;
1879	}
1880
1881	orig_insn->type = INSN_NOP;
1882	}
1883
1884	if (orig_insn->type == INSN_NOP) {
1885	if (orig_insn->len == 2)
1886	file->jl_nop_short++;
1887	else
1888	file->jl_nop_long++;
1889
1890	return 0;
1891	}
1892
1893	if (orig_insn->len == 2)
1894	file->jl_short++;
1895	else
1896	file->jl_long++;
1897
1898	*new_insn = next_insn_same_sec(file, insn: orig_insn);
1899	return 0;
1900	}
1901
1902	/*
1903	* Read all the special sections which have alternate instructions which can be
1904	* patched in or redirected to at runtime. Each instruction having alternate
1905	* instruction(s) has them added to its insn->alts list, which will be
1906	* traversed in validate_branch().
1907	*/
1908	static int add_special_section_alts(struct objtool_file *file)
1909	{
1910	struct list_head special_alts;
1911	struct instruction *orig_insn, *new_insn;
1912	struct special_alt *special_alt, *tmp;
1913	struct alternative *alt;
1914	int ret;
1915
1916	if (special_get_alts(file->elf, &special_alts))
1917	return -1;
1918
1919	list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
1920
1921	orig_insn = find_insn(file, sec: special_alt->orig_sec,
1922	offset: special_alt->orig_off);
1923	if (!orig_insn) {
1924	ERROR_FUNC(special_alt->orig_sec, special_alt->orig_off,
1925	"special: can't find orig instruction");
1926	return -1;
1927	}
1928
1929	new_insn = NULL;
1930	if (!special_alt->group || special_alt->new_len) {
1931	new_insn = find_insn(file, sec: special_alt->new_sec,
1932	offset: special_alt->new_off);
1933	if (!new_insn) {
1934	ERROR_FUNC(special_alt->new_sec, special_alt->new_off,
1935	"special: can't find new instruction");
1936	return -1;
1937	}
1938	}
1939
1940	if (special_alt->group) {
1941	if (!special_alt->orig_len) {
1942	ERROR_INSN(orig_insn, "empty alternative entry");
1943	continue;
1944	}
1945
1946	ret = handle_group_alt(file, special_alt, orig_insn,
1947	new_insn: &new_insn);
1948	if (ret)
1949	return ret;
1950
1951	} else if (special_alt->jump_or_nop) {
1952	ret = handle_jump_alt(file, special_alt, orig_insn,
1953	new_insn: &new_insn);
1954	if (ret)
1955	return ret;
1956	}
1957
1958	alt = calloc(1, sizeof(*alt));
1959	if (!alt) {
1960	ERROR_GLIBC("calloc");
1961	return -1;
1962	}
1963
1964	alt->insn = new_insn;
1965	alt->next = orig_insn->alts;
1966	orig_insn->alts = alt;
1967
1968	list_del(entry: &special_alt->list);
1969	free(special_alt);
1970	}
1971
1972	if (opts.stats) {
1973	printf("jl\\\tNOP\tJMP\n");
1974	printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
1975	printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
1976	}
1977
1978	return 0;
1979	}
1980
1981	__weak unsigned long arch_jump_table_sym_offset(struct reloc *reloc, struct reloc *table)
1982	{
1983	return reloc->sym->offset + reloc_addend(reloc);
1984	}
1985
1986	static int add_jump_table(struct objtool_file *file, struct instruction *insn)
1987	{
1988	unsigned long table_size = insn_jump_table_size(insn);
1989	struct symbol *pfunc = insn_func(insn)->pfunc;
1990	struct reloc *table = insn_jump_table(insn);
1991	struct instruction *dest_insn;
1992	unsigned int prev_offset = 0;
1993	struct reloc *reloc = table;
1994	struct alternative *alt;
1995	unsigned long sym_offset;
1996
1997	/*
1998	* Each @reloc is a switch table relocation which points to the target
1999	* instruction.
2000	*/
2001	for_each_reloc_from(table->sec, reloc) {
2002
2003	/* Check for the end of the table: */
2004	if (table_size && reloc_offset(reloc) - reloc_offset(table) >= table_size)
2005	break;
2006	if (reloc != table && is_jump_table(reloc))
2007	break;
2008
2009	/* Make sure the table entries are consecutive: */
2010	if (prev_offset && reloc_offset(reloc) != prev_offset + arch_reloc_size(reloc))
2011	break;
2012
2013	sym_offset = arch_jump_table_sym_offset(reloc, table);
2014
2015	/* Detect function pointers from contiguous objects: */
2016	if (reloc->sym->sec == pfunc->sec && sym_offset == pfunc->offset)
2017	break;
2018
2019	/*
2020	* Clang sometimes leaves dangling unused jump table entries
2021	* which point to the end of the function. Ignore them.
2022	*/
2023	if (reloc->sym->sec == pfunc->sec &&
2024	sym_offset == pfunc->offset + pfunc->len)
2025	goto next;
2026
2027	dest_insn = find_insn(file, sec: reloc->sym->sec, offset: sym_offset);
2028	if (!dest_insn)
2029	break;
2030
2031	/* Make sure the destination is in the same function: */
2032	if (!insn_func(dest_insn) || insn_func(dest_insn)->pfunc != pfunc)
2033	break;
2034
2035	alt = calloc(1, sizeof(*alt));
2036	if (!alt) {
2037	ERROR_GLIBC("calloc");
2038	return -1;
2039	}
2040
2041	alt->insn = dest_insn;
2042	alt->next = insn->alts;
2043	insn->alts = alt;
2044	next:
2045	prev_offset = reloc_offset(reloc);
2046	}
2047
2048	if (!prev_offset) {
2049	ERROR_INSN(insn, "can't find switch jump table");
2050	return -1;
2051	}
2052
2053	return 0;
2054	}
2055
2056	/*
2057	* find_jump_table() - Given a dynamic jump, find the switch jump table
2058	* associated with it.
2059	*/
2060	static void find_jump_table(struct objtool_file *file, struct symbol *func,
2061	struct instruction *insn)
2062	{
2063	struct reloc *table_reloc;
2064	struct instruction *dest_insn, *orig_insn = insn;
2065	unsigned long table_size;
2066	unsigned long sym_offset;
2067
2068	/*
2069	* Backward search using the @first_jump_src links, these help avoid
2070	* much of the 'in between' code. Which avoids us getting confused by
2071	* it.
2072	*/
2073	for (;
2074	insn && insn_func(insn) && insn_func(insn)->pfunc == func;
2075	insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
2076
2077	if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
2078	break;
2079
2080	/* allow small jumps within the range */
2081	if (insn->type == INSN_JUMP_UNCONDITIONAL &&
2082	insn->jump_dest &&
2083	(insn->jump_dest->offset <= insn->offset ||
2084	insn->jump_dest->offset > orig_insn->offset))
2085	break;
2086
2087	table_reloc = arch_find_switch_table(file, insn, &table_size);
2088	if (!table_reloc)
2089	continue;
2090
2091	sym_offset = table_reloc->sym->offset + reloc_addend(table_reloc);
2092
2093	dest_insn = find_insn(file, sec: table_reloc->sym->sec, offset: sym_offset);
2094	if (!dest_insn || !insn_func(dest_insn) || insn_func(dest_insn)->pfunc != func)
2095	continue;
2096
2097	set_jump_table(table_reloc);
2098	orig_insn->_jump_table = table_reloc;
2099	orig_insn->_jump_table_size = table_size;
2100
2101	break;
2102	}
2103	}
2104
2105	/*
2106	* First pass: Mark the head of each jump table so that in the next pass,
2107	* we know when a given jump table ends and the next one starts.
2108	*/
2109	static void mark_func_jump_tables(struct objtool_file *file,
2110	struct symbol *func)
2111	{
2112	struct instruction *insn, *last = NULL;
2113
2114	func_for_each_insn(file, func, insn) {
2115	if (!last)
2116	last = insn;
2117
2118	/*
2119	* Store back-pointers for unconditional forward jumps such
2120	* that find_jump_table() can back-track using those and
2121	* avoid some potentially confusing code.
2122	*/
2123	if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
2124	insn->offset > last->offset &&
2125	insn->jump_dest->offset > insn->offset &&
2126	!insn->jump_dest->first_jump_src) {
2127
2128	insn->jump_dest->first_jump_src = insn;
2129	last = insn->jump_dest;
2130	}
2131
2132	if (insn->type != INSN_JUMP_DYNAMIC)
2133	continue;
2134
2135	find_jump_table(file, func, insn);
2136	}
2137	}
2138
2139	static int add_func_jump_tables(struct objtool_file *file,
2140	struct symbol *func)
2141	{
2142	struct instruction *insn;
2143	int ret;
2144
2145	func_for_each_insn(file, func, insn) {
2146	if (!insn_jump_table(insn))
2147	continue;
2148
2149	ret = add_jump_table(file, insn);
2150	if (ret)
2151	return ret;
2152	}
2153
2154	return 0;
2155	}
2156
2157	/*
2158	* For some switch statements, gcc generates a jump table in the .rodata
2159	* section which contains a list of addresses within the function to jump to.
2160	* This finds these jump tables and adds them to the insn->alts lists.
2161	*/
2162	static int add_jump_table_alts(struct objtool_file *file)
2163	{
2164	struct symbol *func;
2165	int ret;
2166
2167	if (!file->rodata)
2168	return 0;
2169
2170	for_each_sym(file, func) {
2171	if (func->type != STT_FUNC)
2172	continue;
2173
2174	mark_func_jump_tables(file, func);
2175	ret = add_func_jump_tables(file, func);
2176	if (ret)
2177	return ret;
2178	}
2179
2180	return 0;
2181	}
2182
2183	static void set_func_state(struct cfi_state *state)
2184	{
2185	state->cfa = initial_func_cfi.cfa;
2186	memcpy(&state->regs, &initial_func_cfi.regs,
2187	CFI_NUM_REGS * sizeof(struct cfi_reg));
2188	state->stack_size = initial_func_cfi.cfa.offset;
2189	state->type = UNWIND_HINT_TYPE_CALL;
2190	}
2191
2192	static int read_unwind_hints(struct objtool_file *file)
2193	{
2194	struct cfi_state cfi = init_cfi;
2195	struct section *sec;
2196	struct unwind_hint *hint;
2197	struct instruction *insn;
2198	struct reloc *reloc;
2199	unsigned long offset;
2200	int i;
2201
2202	sec = find_section_by_name(file->elf, ".discard.unwind_hints");
2203	if (!sec)
2204	return 0;
2205
2206	if (!sec->rsec) {
2207	ERROR("missing .rela.discard.unwind_hints section");
2208	return -1;
2209	}
2210
2211	if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
2212	ERROR("struct unwind_hint size mismatch");
2213	return -1;
2214	}
2215
2216	file->hints = true;
2217
2218	for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
2219	hint = (struct unwind_hint *)sec->data->d_buf + i;
2220
2221	reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
2222	if (!reloc) {
2223	ERROR("can't find reloc for unwind_hints[%d]", i);
2224	return -1;
2225	}
2226
2227	if (reloc->sym->type == STT_SECTION) {
2228	offset = reloc_addend(reloc);
2229	} else if (reloc->sym->local_label) {
2230	offset = reloc->sym->offset;
2231	} else {
2232	ERROR("unexpected relocation symbol type in %s", sec->rsec->name);
2233	return -1;
2234	}
2235
2236	insn = find_insn(file, sec: reloc->sym->sec, offset);
2237	if (!insn) {
2238	ERROR("can't find insn for unwind_hints[%d]", i);
2239	return -1;
2240	}
2241
2242	insn->hint = true;
2243
2244	if (hint->type == UNWIND_HINT_TYPE_UNDEFINED) {
2245	insn->cfi = &force_undefined_cfi;
2246	continue;
2247	}
2248
2249	if (hint->type == UNWIND_HINT_TYPE_SAVE) {
2250	insn->hint = false;
2251	insn->save = true;
2252	continue;
2253	}
2254
2255	if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
2256	insn->restore = true;
2257	continue;
2258	}
2259
2260	if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
2261	struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
2262
2263	if (sym && sym->bind == STB_GLOBAL) {
2264	if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
2265	ERROR_INSN(insn, "UNWIND_HINT_IRET_REGS without ENDBR");
2266	return -1;
2267	}
2268	}
2269	}
2270
2271	if (hint->type == UNWIND_HINT_TYPE_FUNC) {
2272	insn->cfi = &func_cfi;
2273	continue;
2274	}
2275
2276	if (insn->cfi)
2277	cfi = *(insn->cfi);
2278
2279	if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
2280	ERROR_INSN(insn, "unsupported unwind_hint sp base reg %d", hint->sp_reg);
2281	return -1;
2282	}
2283
2284	cfi.cfa.offset = bswap_if_needed(file->elf, hint->sp_offset);
2285	cfi.type = hint->type;
2286	cfi.signal = hint->signal;
2287
2288	insn->cfi = cfi_hash_find_or_add(cfi: &cfi);
2289	}
2290
2291	return 0;
2292	}
2293
2294	static int read_annotate(struct objtool_file *file,
2295	int (*func)(struct objtool_file *file, int type, struct instruction *insn))
2296	{
2297	struct section *sec;
2298	struct instruction *insn;
2299	struct reloc *reloc;
2300	uint64_t offset;
2301	int type, ret;
2302
2303	sec = find_section_by_name(file->elf, ".discard.annotate_insn");
2304	if (!sec)
2305	return 0;
2306
2307	if (!sec->rsec)
2308	return 0;
2309
2310	if (sec->sh.sh_entsize != 8) {
2311	static bool warned = false;
2312	if (!warned && opts.verbose) {
2313	WARN("%s: dodgy linker, sh_entsize != 8", sec->name);
2314	warned = true;
2315	}
2316	sec->sh.sh_entsize = 8;
2317	}
2318
2319	for_each_reloc(sec->rsec, reloc) {
2320	type = *(u32 *)(sec->data->d_buf + (reloc_idx(reloc) * sec->sh.sh_entsize) + 4);
2321
2322	offset = reloc->sym->offset + reloc_addend(reloc);
2323	insn = find_insn(file, sec: reloc->sym->sec, offset);
2324
2325	if (!insn) {
2326	ERROR("bad .discard.annotate_insn entry: %d of type %d", reloc_idx(reloc), type);
2327	return -1;
2328	}
2329
2330	ret = func(file, type, insn);
2331	if (ret < 0)
2332	return ret;
2333	}
2334
2335	return 0;
2336	}
2337
2338	static int __annotate_early(struct objtool_file *file, int type, struct instruction *insn)
2339	{
2340	switch (type) {
2341
2342	/* Must be before add_special_section_alts() */
2343	case ANNOTYPE_IGNORE_ALTS:
2344	insn->ignore_alts = true;
2345	break;
2346
2347	/*
2348	* Must be before read_unwind_hints() since that needs insn->noendbr.
2349	*/
2350	case ANNOTYPE_NOENDBR:
2351	insn->noendbr = 1;
2352	break;
2353
2354	default:
2355	break;
2356	}
2357
2358	return 0;
2359	}
2360
2361	static int __annotate_ifc(struct objtool_file *file, int type, struct instruction *insn)
2362	{
2363	unsigned long dest_off;
2364
2365	if (type != ANNOTYPE_INTRA_FUNCTION_CALL)
2366	return 0;
2367
2368	if (insn->type != INSN_CALL) {
2369	ERROR_INSN(insn, "intra_function_call not a direct call");
2370	return -1;
2371	}
2372
2373	/*
2374	* Treat intra-function CALLs as JMPs, but with a stack_op.
2375	* See add_call_destinations(), which strips stack_ops from
2376	* normal CALLs.
2377	*/
2378	insn->type = INSN_JUMP_UNCONDITIONAL;
2379
2380	dest_off = arch_jump_destination(insn);
2381	insn->jump_dest = find_insn(file, sec: insn->sec, offset: dest_off);
2382	if (!insn->jump_dest) {
2383	ERROR_INSN(insn, "can't find call dest at %s+0x%lx",
2384	insn->sec->name, dest_off);
2385	return -1;
2386	}
2387
2388	return 0;
2389	}
2390
2391	static int __annotate_late(struct objtool_file *file, int type, struct instruction *insn)
2392	{
2393	switch (type) {
2394	case ANNOTYPE_NOENDBR:
2395	/* early */
2396	break;
2397
2398	case ANNOTYPE_RETPOLINE_SAFE:
2399	if (insn->type != INSN_JUMP_DYNAMIC &&
2400	insn->type != INSN_CALL_DYNAMIC &&
2401	insn->type != INSN_RETURN &&
2402	insn->type != INSN_NOP) {
2403	ERROR_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
2404	return -1;
2405	}
2406
2407	insn->retpoline_safe = true;
2408	break;
2409
2410	case ANNOTYPE_INSTR_BEGIN:
2411	insn->instr++;
2412	break;
2413
2414	case ANNOTYPE_INSTR_END:
2415	insn->instr--;
2416	break;
2417
2418	case ANNOTYPE_UNRET_BEGIN:
2419	insn->unret = 1;
2420	break;
2421
2422	case ANNOTYPE_IGNORE_ALTS:
2423	/* early */
2424	break;
2425
2426	case ANNOTYPE_INTRA_FUNCTION_CALL:
2427	/* ifc */
2428	break;
2429
2430	case ANNOTYPE_REACHABLE:
2431	insn->dead_end = false;
2432	break;
2433
2434	default:
2435	ERROR_INSN(insn, "Unknown annotation type: %d", type);
2436	return -1;
2437	}
2438
2439	return 0;
2440	}
2441
2442	/*
2443	* Return true if name matches an instrumentation function, where calls to that
2444	* function from noinstr code can safely be removed, but compilers won't do so.
2445	*/
2446	static bool is_profiling_func(const char *name)
2447	{
2448	/*
2449	* Many compilers cannot disable KCOV with a function attribute.
2450	*/
2451	if (!strncmp(name, "__sanitizer_cov_", 16))
2452	return true;
2453
2454	/*
2455	* Some compilers currently do not remove __tsan_func_entry/exit nor
2456	* __tsan_atomic_signal_fence (used for barrier instrumentation) with
2457	* the __no_sanitize_thread attribute, remove them. Once the kernel's
2458	* minimum Clang version is 14.0, this can be removed.
2459	*/
2460	if (!strncmp(name, "__tsan_func_", 12) ||
2461	!strcmp(name, "__tsan_atomic_signal_fence"))
2462	return true;
2463
2464	return false;
2465	}
2466
2467	static int classify_symbols(struct objtool_file *file)
2468	{
2469	struct symbol *func;
2470
2471	for_each_sym(file, func) {
2472	if (func->type == STT_NOTYPE && strstarts(func->name, ".L"))
2473	func->local_label = true;
2474
2475	if (func->bind != STB_GLOBAL)
2476	continue;
2477
2478	if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
2479	strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
2480	func->static_call_tramp = true;
2481
2482	if (arch_is_retpoline(sym: func))
2483	func->retpoline_thunk = true;
2484
2485	if (arch_is_rethunk(sym: func))
2486	func->return_thunk = true;
2487
2488	if (arch_is_embedded_insn(sym: func))
2489	func->embedded_insn = true;
2490
2491	if (arch_ftrace_match(func->name))
2492	func->fentry = true;
2493
2494	if (is_profiling_func(name: func->name))
2495	func->profiling_func = true;
2496	}
2497
2498	return 0;
2499	}
2500
2501	static void mark_rodata(struct objtool_file *file)
2502	{
2503	struct section *sec;
2504	bool found = false;
2505
2506	/*
2507	* Search for the following rodata sections, each of which can
2508	* potentially contain jump tables:
2509	*
2510	* - .rodata: can contain GCC switch tables
2511	* - .rodata.<func>: same, if -fdata-sections is being used
2512	* - .data.rel.ro.c_jump_table: contains C annotated jump tables
2513	*
2514	* .rodata.str1.* sections are ignored; they don't contain jump tables.
2515	*/
2516	for_each_sec(file, sec) {
2517	if ((!strncmp(sec->name, ".rodata", 7) &&
2518	!strstr(sec->name, ".str1.")) ||
2519	!strncmp(sec->name, ".data.rel.ro", 12)) {
2520	sec->rodata = true;
2521	found = true;
2522	}
2523	}
2524
2525	file->rodata = found;
2526	}
2527
2528	static int decode_sections(struct objtool_file *file)
2529	{
2530	int ret;
2531
2532	mark_rodata(file);
2533
2534	ret = init_pv_ops(file);
2535	if (ret)
2536	return ret;
2537
2538	/*
2539	* Must be before add_{jump_call}_destination.
2540	*/
2541	ret = classify_symbols(file);
2542	if (ret)
2543	return ret;
2544
2545	ret = decode_instructions(file);
2546	if (ret)
2547	return ret;
2548
2549	ret = add_ignores(file);
2550	if (ret)
2551	return ret;
2552
2553	add_uaccess_safe(file);
2554
2555	ret = read_annotate(file, func: __annotate_early);
2556	if (ret)
2557	return ret;
2558
2559	/*
2560	* Must be before add_jump_destinations(), which depends on 'func'
2561	* being set for alternatives, to enable proper sibling call detection.
2562	*/
2563	if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr) {
2564	ret = add_special_section_alts(file);
2565	if (ret)
2566	return ret;
2567	}
2568
2569	ret = add_jump_destinations(file);
2570	if (ret)
2571	return ret;
2572
2573	/*
2574	* Must be before add_call_destination(); it changes INSN_CALL to
2575	* INSN_JUMP.
2576	*/
2577	ret = read_annotate(file, func: __annotate_ifc);
2578	if (ret)
2579	return ret;
2580
2581	ret = add_call_destinations(file);
2582	if (ret)
2583	return ret;
2584
2585	ret = add_jump_table_alts(file);
2586	if (ret)
2587	return ret;
2588
2589	ret = read_unwind_hints(file);
2590	if (ret)
2591	return ret;
2592
2593	/*
2594	* Must be after add_call_destinations() such that it can override
2595	* dead_end_function() marks.
2596	*/
2597	ret = read_annotate(file, func: __annotate_late);
2598	if (ret)
2599	return ret;
2600
2601	return 0;
2602	}
2603
2604	static bool is_special_call(struct instruction *insn)
2605	{
2606	if (insn->type == INSN_CALL) {
2607	struct symbol *dest = insn_call_dest(insn);
2608
2609	if (!dest)
2610	return false;
2611
2612	if (dest->fentry || dest->embedded_insn)
2613	return true;
2614	}
2615
2616	return false;
2617	}
2618
2619	static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
2620	{
2621	struct cfi_state *cfi = &state->cfi;
2622	int i;
2623
2624	if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
2625	return true;
2626
2627	if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
2628	return true;
2629
2630	if (cfi->stack_size != initial_func_cfi.cfa.offset)
2631	return true;
2632
2633	for (i = 0; i < CFI_NUM_REGS; i++) {
2634	if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
2635	cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
2636	return true;
2637	}
2638
2639	return false;
2640	}
2641
2642	static bool check_reg_frame_pos(const struct cfi_reg *reg,
2643	int expected_offset)
2644	{
2645	return reg->base == CFI_CFA &&
2646	reg->offset == expected_offset;
2647	}
2648
2649	static bool has_valid_stack_frame(struct insn_state *state)
2650	{
2651	struct cfi_state *cfi = &state->cfi;
2652
2653	if (cfi->cfa.base == CFI_BP &&
2654	check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
2655	check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
2656	return true;
2657
2658	if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
2659	return true;
2660
2661	return false;
2662	}
2663
2664	static int update_cfi_state_regs(struct instruction *insn,
2665	struct cfi_state *cfi,
2666	struct stack_op *op)
2667	{
2668	struct cfi_reg *cfa = &cfi->cfa;
2669
2670	if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
2671	return 0;
2672
2673	/* push */
2674	if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
2675	cfa->offset += 8;
2676
2677	/* pop */
2678	if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
2679	cfa->offset -= 8;
2680
2681	/* add immediate to sp */
2682	if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
2683	op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
2684	cfa->offset -= op->src.offset;
2685
2686	return 0;
2687	}
2688
2689	static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
2690	{
2691	if (arch_callee_saved_reg(reg) &&
2692	cfi->regs[reg].base == CFI_UNDEFINED) {
2693	cfi->regs[reg].base = base;
2694	cfi->regs[reg].offset = offset;
2695	}
2696	}
2697
2698	static void restore_reg(struct cfi_state *cfi, unsigned char reg)
2699	{
2700	cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
2701	cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
2702	}
2703
2704	/*
2705	* A note about DRAP stack alignment:
2706	*
2707	* GCC has the concept of a DRAP register, which is used to help keep track of
2708	* the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
2709	* register. The typical DRAP pattern is:
2710	*
2711	* 4c 8d 54 24 08 lea 0x8(%rsp),%r10
2712	* 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
2713	* 41 ff 72 f8 pushq -0x8(%r10)
2714	* 55 push %rbp
2715	* 48 89 e5 mov %rsp,%rbp
2716	* (more pushes)
2717	* 41 52 push %r10
2718	* ...
2719	* 41 5a pop %r10
2720	* (more pops)
2721	* 5d pop %rbp
2722	* 49 8d 62 f8 lea -0x8(%r10),%rsp
2723	* c3 retq
2724	*
2725	* There are some variations in the epilogues, like:
2726	*
2727	* 5b pop %rbx
2728	* 41 5a pop %r10
2729	* 41 5c pop %r12
2730	* 41 5d pop %r13
2731	* 41 5e pop %r14
2732	* c9 leaveq
2733	* 49 8d 62 f8 lea -0x8(%r10),%rsp
2734	* c3 retq
2735	*
2736	* and:
2737	*
2738	* 4c 8b 55 e8 mov -0x18(%rbp),%r10
2739	* 48 8b 5d e0 mov -0x20(%rbp),%rbx
2740	* 4c 8b 65 f0 mov -0x10(%rbp),%r12
2741	* 4c 8b 6d f8 mov -0x8(%rbp),%r13
2742	* c9 leaveq
2743	* 49 8d 62 f8 lea -0x8(%r10),%rsp
2744	* c3 retq
2745	*
2746	* Sometimes r13 is used as the DRAP register, in which case it's saved and
2747	* restored beforehand:
2748	*
2749	* 41 55 push %r13
2750	* 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
2751	* 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
2752	* ...
2753	* 49 8d 65 f0 lea -0x10(%r13),%rsp
2754	* 41 5d pop %r13
2755	* c3 retq
2756	*/
2757	static int update_cfi_state(struct instruction *insn,
2758	struct instruction *next_insn,
2759	struct cfi_state *cfi, struct stack_op *op)
2760	{
2761	struct cfi_reg *cfa = &cfi->cfa;
2762	struct cfi_reg *regs = cfi->regs;
2763
2764	/* ignore UNWIND_HINT_UNDEFINED regions */
2765	if (cfi->force_undefined)
2766	return 0;
2767
2768	/* stack operations don't make sense with an undefined CFA */
2769	if (cfa->base == CFI_UNDEFINED) {
2770	if (insn_func(insn)) {
2771	WARN_INSN(insn, "undefined stack state");
2772	return 1;
2773	}
2774	return 0;
2775	}
2776
2777	if (cfi->type == UNWIND_HINT_TYPE_REGS ||
2778	cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
2779	return update_cfi_state_regs(insn, cfi, op);
2780
2781	switch (op->dest.type) {
2782
2783	case OP_DEST_REG:
2784	switch (op->src.type) {
2785
2786	case OP_SRC_REG:
2787	if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
2788	cfa->base == CFI_SP &&
2789	check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {
2790
2791	/* mov %rsp, %rbp */
2792	cfa->base = op->dest.reg;
2793	cfi->bp_scratch = false;
2794	}
2795
2796	else if (op->src.reg == CFI_SP &&
2797	op->dest.reg == CFI_BP && cfi->drap) {
2798
2799	/* drap: mov %rsp, %rbp */
2800	regs[CFI_BP].base = CFI_BP;
2801	regs[CFI_BP].offset = -cfi->stack_size;
2802	cfi->bp_scratch = false;
2803	}
2804
2805	else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2806
2807	/*
2808	* mov %rsp, %reg
2809	*
2810	* This is needed for the rare case where GCC
2811	* does:
2812	*
2813	* mov %rsp, %rax
2814	* ...
2815	* mov %rax, %rsp
2816	*/
2817	cfi->vals[op->dest.reg].base = CFI_CFA;
2818	cfi->vals[op->dest.reg].offset = -cfi->stack_size;
2819	}
2820
2821	else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
2822	(cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {
2823
2824	/*
2825	* mov %rbp, %rsp
2826	*
2827	* Restore the original stack pointer (Clang).
2828	*/
2829	cfi->stack_size = -cfi->regs[CFI_BP].offset;
2830	}
2831
2832	else if (op->dest.reg == cfa->base) {
2833
2834	/* mov %reg, %rsp */
2835	if (cfa->base == CFI_SP &&
2836	cfi->vals[op->src.reg].base == CFI_CFA) {
2837
2838	/*
2839	* This is needed for the rare case
2840	* where GCC does something dumb like:
2841	*
2842	* lea 0x8(%rsp), %rcx
2843	* ...
2844	* mov %rcx, %rsp
2845	*/
2846	cfa->offset = -cfi->vals[op->src.reg].offset;
2847	cfi->stack_size = cfa->offset;
2848
2849	} else if (cfa->base == CFI_SP &&
2850	cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2851	cfi->vals[op->src.reg].offset == cfa->offset) {
2852
2853	/*
2854	* Stack swizzle:
2855	*
2856	* 1: mov %rsp, (%[tos])
2857	* 2: mov %[tos], %rsp
2858	* ...
2859	* 3: pop %rsp
2860	*
2861	* Where:
2862	*
2863	* 1 - places a pointer to the previous
2864	* stack at the Top-of-Stack of the
2865	* new stack.
2866	*
2867	* 2 - switches to the new stack.
2868	*
2869	* 3 - pops the Top-of-Stack to restore
2870	* the original stack.
2871	*
2872	* Note: we set base to SP_INDIRECT
2873	* here and preserve offset. Therefore
2874	* when the unwinder reaches ToS it
2875	* will dereference SP and then add the
2876	* offset to find the next frame, IOW:
2877	* (%rsp) + offset.
2878	*/
2879	cfa->base = CFI_SP_INDIRECT;
2880
2881	} else {
2882	cfa->base = CFI_UNDEFINED;
2883	cfa->offset = 0;
2884	}
2885	}
2886
2887	else if (op->dest.reg == CFI_SP &&
2888	cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
2889	cfi->vals[op->src.reg].offset == cfa->offset) {
2890
2891	/*
2892	* The same stack swizzle case 2) as above. But
2893	* because we can't change cfa->base, case 3)
2894	* will become a regular POP. Pretend we're a
2895	* PUSH so things don't go unbalanced.
2896	*/
2897	cfi->stack_size += 8;
2898	}
2899
2900
2901	break;
2902
2903	case OP_SRC_ADD:
2904	if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
2905
2906	/* add imm, %rsp */
2907	cfi->stack_size -= op->src.offset;
2908	if (cfa->base == CFI_SP)
2909	cfa->offset -= op->src.offset;
2910	break;
2911	}
2912
2913	if (op->dest.reg == CFI_BP && op->src.reg == CFI_SP &&
2914	insn->sym->frame_pointer) {
2915	/* addi.d fp,sp,imm on LoongArch */
2916	if (cfa->base == CFI_SP && cfa->offset == op->src.offset) {
2917	cfa->base = CFI_BP;
2918	cfa->offset = 0;
2919	}
2920	break;
2921	}
2922
2923	if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
2924	/* addi.d sp,fp,imm on LoongArch */
2925	if (cfa->base == CFI_BP && cfa->offset == 0) {
2926	if (insn->sym->frame_pointer) {
2927	cfa->base = CFI_SP;
2928	cfa->offset = -op->src.offset;
2929	}
2930	} else {
2931	/* lea disp(%rbp), %rsp */
2932	cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
2933	}
2934	break;
2935	}
2936
2937	if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
2938
2939	/* drap: lea disp(%rsp), %drap */
2940	cfi->drap_reg = op->dest.reg;
2941
2942	/*
2943	* lea disp(%rsp), %reg
2944	*
2945	* This is needed for the rare case where GCC
2946	* does something dumb like:
2947	*
2948	* lea 0x8(%rsp), %rcx
2949	* ...
2950	* mov %rcx, %rsp
2951	*/
2952	cfi->vals[op->dest.reg].base = CFI_CFA;
2953	cfi->vals[op->dest.reg].offset = \
2954	-cfi->stack_size + op->src.offset;
2955
2956	break;
2957	}
2958
2959	if (cfi->drap && op->dest.reg == CFI_SP &&
2960	op->src.reg == cfi->drap_reg) {
2961
2962	/* drap: lea disp(%drap), %rsp */
2963	cfa->base = CFI_SP;
2964	cfa->offset = cfi->stack_size = -op->src.offset;
2965	cfi->drap_reg = CFI_UNDEFINED;
2966	cfi->drap = false;
2967	break;
2968	}
2969
2970	if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
2971	WARN_INSN(insn, "unsupported stack register modification");
2972	return -1;
2973	}
2974
2975	break;
2976
2977	case OP_SRC_AND:
2978	if (op->dest.reg != CFI_SP ||
2979	(cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
2980	(cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
2981	WARN_INSN(insn, "unsupported stack pointer realignment");
2982	return -1;
2983	}
2984
2985	if (cfi->drap_reg != CFI_UNDEFINED) {
2986	/* drap: and imm, %rsp */
2987	cfa->base = cfi->drap_reg;
2988	cfa->offset = cfi->stack_size = 0;
2989	cfi->drap = true;
2990	}
2991
2992	/*
2993	* Older versions of GCC (4.8ish) realign the stack
2994	* without DRAP, with a frame pointer.
2995	*/
2996
2997	break;
2998
2999	case OP_SRC_POP:
3000	case OP_SRC_POPF:
3001	if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
3002
3003	/* pop %rsp; # restore from a stack swizzle */
3004	cfa->base = CFI_SP;
3005	break;
3006	}
3007
3008	if (!cfi->drap && op->dest.reg == cfa->base) {
3009
3010	/* pop %rbp */
3011	cfa->base = CFI_SP;
3012	}
3013
3014	if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
3015	op->dest.reg == cfi->drap_reg &&
3016	cfi->drap_offset == -cfi->stack_size) {
3017
3018	/* drap: pop %drap */
3019	cfa->base = cfi->drap_reg;
3020	cfa->offset = 0;
3021	cfi->drap_offset = -1;
3022
3023	} else if (cfi->stack_size == -regs[op->dest.reg].offset) {
3024
3025	/* pop %reg */
3026	restore_reg(cfi, reg: op->dest.reg);
3027	}
3028
3029	cfi->stack_size -= 8;
3030	if (cfa->base == CFI_SP)
3031	cfa->offset -= 8;
3032
3033	break;
3034
3035	case OP_SRC_REG_INDIRECT:
3036	if (!cfi->drap && op->dest.reg == cfa->base &&
3037	op->dest.reg == CFI_BP) {
3038
3039	/* mov disp(%rsp), %rbp */
3040	cfa->base = CFI_SP;
3041	cfa->offset = cfi->stack_size;
3042	}
3043
3044	if (cfi->drap && op->src.reg == CFI_BP &&
3045	op->src.offset == cfi->drap_offset) {
3046
3047	/* drap: mov disp(%rbp), %drap */
3048	cfa->base = cfi->drap_reg;
3049	cfa->offset = 0;
3050	cfi->drap_offset = -1;
3051	}
3052
3053	if (cfi->drap && op->src.reg == CFI_BP &&
3054	op->src.offset == regs[op->dest.reg].offset) {
3055
3056	/* drap: mov disp(%rbp), %reg */
3057	restore_reg(cfi, reg: op->dest.reg);
3058
3059	} else if (op->src.reg == cfa->base &&
3060	op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
3061
3062	/* mov disp(%rbp), %reg */
3063	/* mov disp(%rsp), %reg */
3064	restore_reg(cfi, reg: op->dest.reg);
3065
3066	} else if (op->src.reg == CFI_SP &&
3067	op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
3068
3069	/* mov disp(%rsp), %reg */
3070	restore_reg(cfi, reg: op->dest.reg);
3071	}
3072
3073	break;
3074
3075	default:
3076	WARN_INSN(insn, "unknown stack-related instruction");
3077	return -1;
3078	}
3079
3080	break;
3081
3082	case OP_DEST_PUSH:
3083	case OP_DEST_PUSHF:
3084	cfi->stack_size += 8;
3085	if (cfa->base == CFI_SP)
3086	cfa->offset += 8;
3087
3088	if (op->src.type != OP_SRC_REG)
3089	break;
3090
3091	if (cfi->drap) {
3092	if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
3093
3094	/* drap: push %drap */
3095	cfa->base = CFI_BP_INDIRECT;
3096	cfa->offset = -cfi->stack_size;
3097
3098	/* save drap so we know when to restore it */
3099	cfi->drap_offset = -cfi->stack_size;
3100
3101	} else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
3102
3103	/* drap: push %rbp */
3104	cfi->stack_size = 0;
3105
3106	} else {
3107
3108	/* drap: push %reg */
3109	save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
3110	}
3111
3112	} else {
3113
3114	/* push %reg */
3115	save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
3116	}
3117
3118	/* detect when asm code uses rbp as a scratch register */
3119	if (opts.stackval && insn_func(insn) && op->src.reg == CFI_BP &&
3120	cfa->base != CFI_BP)
3121	cfi->bp_scratch = true;
3122	break;
3123
3124	case OP_DEST_REG_INDIRECT:
3125
3126	if (cfi->drap) {
3127	if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
3128
3129	/* drap: mov %drap, disp(%rbp) */
3130	cfa->base = CFI_BP_INDIRECT;
3131	cfa->offset = op->dest.offset;
3132
3133	/* save drap offset so we know when to restore it */
3134	cfi->drap_offset = op->dest.offset;
3135	} else {
3136
3137	/* drap: mov reg, disp(%rbp) */
3138	save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
3139	}
3140
3141	} else if (op->dest.reg == cfa->base) {
3142
3143	/* mov reg, disp(%rbp) */
3144	/* mov reg, disp(%rsp) */
3145	save_reg(cfi, op->src.reg, CFI_CFA,
3146	op->dest.offset - cfi->cfa.offset);
3147
3148	} else if (op->dest.reg == CFI_SP) {
3149
3150	/* mov reg, disp(%rsp) */
3151	save_reg(cfi, op->src.reg, CFI_CFA,
3152	op->dest.offset - cfi->stack_size);
3153
3154	} else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
3155
3156	/* mov %rsp, (%reg); # setup a stack swizzle. */
3157	cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
3158	cfi->vals[op->dest.reg].offset = cfa->offset;
3159	}
3160
3161	break;
3162
3163	case OP_DEST_MEM:
3164	if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
3165	WARN_INSN(insn, "unknown stack-related memory operation");
3166	return -1;
3167	}
3168
3169	/* pop mem */
3170	cfi->stack_size -= 8;
3171	if (cfa->base == CFI_SP)
3172	cfa->offset -= 8;
3173
3174	break;
3175
3176	default:
3177	WARN_INSN(insn, "unknown stack-related instruction");
3178	return -1;
3179	}
3180
3181	return 0;
3182	}
3183
3184	/*
3185	* The stack layouts of alternatives instructions can sometimes diverge when
3186	* they have stack modifications. That's fine as long as the potential stack
3187	* layouts don't conflict at any given potential instruction boundary.
3188	*
3189	* Flatten the CFIs of the different alternative code streams (both original
3190	* and replacement) into a single shared CFI array which can be used to detect
3191	* conflicts and nicely feed a linear array of ORC entries to the unwinder.
3192	*/
3193	static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
3194	{
3195	struct cfi_state **alt_cfi;
3196	int group_off;
3197
3198	if (!insn->alt_group)
3199	return 0;
3200
3201	if (!insn->cfi) {
3202	WARN("CFI missing");
3203	return -1;
3204	}
3205
3206	alt_cfi = insn->alt_group->cfi;
3207	group_off = insn->offset - insn->alt_group->first_insn->offset;
3208
3209	if (!alt_cfi[group_off]) {
3210	alt_cfi[group_off] = insn->cfi;
3211	} else {
3212	if (cficmp(cfi1: alt_cfi[group_off], cfi2: insn->cfi)) {
3213	struct alt_group *orig_group = insn->alt_group->orig_group ?: insn->alt_group;
3214	struct instruction *orig = orig_group->first_insn;
3215	WARN_INSN(orig, "stack layout conflict in alternatives: %s",
3216	offstr(insn->sec, insn->offset));
3217	return -1;
3218	}
3219	}
3220
3221	return 0;
3222	}
3223
3224	static int handle_insn_ops(struct instruction *insn,
3225	struct instruction *next_insn,
3226	struct insn_state *state)
3227	{
3228	struct stack_op *op;
3229	int ret;
3230
3231	for (op = insn->stack_ops; op; op = op->next) {
3232
3233	ret = update_cfi_state(insn, next_insn, cfi: &state->cfi, op);
3234	if (ret)
3235	return ret;
3236
3237	if (!opts.uaccess || !insn->alt_group)
3238	continue;
3239
3240	if (op->dest.type == OP_DEST_PUSHF) {
3241	if (!state->uaccess_stack) {
3242	state->uaccess_stack = 1;
3243	} else if (state->uaccess_stack >> 31) {
3244	WARN_INSN(insn, "PUSHF stack exhausted");
3245	return 1;
3246	}
3247	state->uaccess_stack <<= 1;
3248	state->uaccess_stack |= state->uaccess;
3249	}
3250
3251	if (op->src.type == OP_SRC_POPF) {
3252	if (state->uaccess_stack) {
3253	state->uaccess = state->uaccess_stack & 1;
3254	state->uaccess_stack >>= 1;
3255	if (state->uaccess_stack == 1)
3256	state->uaccess_stack = 0;
3257	}
3258	}
3259	}
3260
3261	return 0;
3262	}
3263
3264	static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
3265	{
3266	struct cfi_state *cfi1 = insn->cfi;
3267	int i;
3268
3269	if (!cfi1) {
3270	WARN("CFI missing");
3271	return false;
3272	}
3273
3274	if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
3275
3276	WARN_INSN(insn, "stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
3277	cfi1->cfa.base, cfi1->cfa.offset,
3278	cfi2->cfa.base, cfi2->cfa.offset);
3279	return false;
3280
3281	}
3282
3283	if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
3284	for (i = 0; i < CFI_NUM_REGS; i++) {
3285
3286	if (!memcmp(&cfi1->regs[i], &cfi2->regs[i], sizeof(struct cfi_reg)))
3287	continue;
3288
3289	WARN_INSN(insn, "stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
3290	i, cfi1->regs[i].base, cfi1->regs[i].offset,
3291	i, cfi2->regs[i].base, cfi2->regs[i].offset);
3292	}
3293	return false;
3294	}
3295
3296	if (cfi1->type != cfi2->type) {
3297
3298	WARN_INSN(insn, "stack state mismatch: type1=%d type2=%d",
3299	cfi1->type, cfi2->type);
3300	return false;
3301	}
3302
3303	if (cfi1->drap != cfi2->drap ||
3304	(cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
3305	(cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
3306
3307	WARN_INSN(insn, "stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
3308	cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
3309	cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
3310	return false;
3311	}
3312
3313	return true;
3314	}
3315
3316	static inline bool func_uaccess_safe(struct symbol *func)
3317	{
3318	if (func)
3319	return func->uaccess_safe;
3320
3321	return false;
3322	}
3323
3324	static inline const char *call_dest_name(struct instruction *insn)
3325	{
3326	static char pvname[19];
3327	struct reloc *reloc;
3328	int idx;
3329
3330	if (insn_call_dest(insn))
3331	return insn_call_dest(insn)->name;
3332
3333	reloc = insn_reloc(NULL, insn);
3334	if (reloc && !strcmp(reloc->sym->name, "pv_ops")) {
3335	idx = (reloc_addend(reloc) / sizeof(void *));
3336	snprintf(buf: pvname, size: sizeof(pvname), fmt: "pv_ops[%d]", idx);
3337	return pvname;
3338	}
3339
3340	return "{dynamic}";
3341	}
3342
3343	static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
3344	{
3345	struct symbol *target;
3346	struct reloc *reloc;
3347	int idx;
3348
3349	reloc = insn_reloc(file, insn);
3350	if (!reloc || strcmp(reloc->sym->name, "pv_ops"))
3351	return false;
3352
3353	idx = (arch_dest_reloc_offset(reloc_addend(reloc)) / sizeof(void *));
3354
3355	if (file->pv_ops[idx].clean)
3356	return true;
3357
3358	file->pv_ops[idx].clean = true;
3359
3360	list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
3361	if (!target->sec->noinstr) {
3362	WARN("pv_ops[%d]: %s", idx, target->name);
3363	file->pv_ops[idx].clean = false;
3364	}
3365	}
3366
3367	return file->pv_ops[idx].clean;
3368	}
3369
3370	static inline bool noinstr_call_dest(struct objtool_file *file,
3371	struct instruction *insn,
3372	struct symbol *func)
3373	{
3374	/*
3375	* We can't deal with indirect function calls at present;
3376	* assume they're instrumented.
3377	*/
3378	if (!func) {
3379	if (file->pv_ops)
3380	return pv_call_dest(file, insn);
3381
3382	return false;
3383	}
3384
3385	/*
3386	* If the symbol is from a noinstr section; we good.
3387	*/
3388	if (func->sec->noinstr)
3389	return true;
3390
3391	/*
3392	* If the symbol is a static_call trampoline, we can't tell.
3393	*/
3394	if (func->static_call_tramp)
3395	return true;
3396
3397	/*
3398	* The __ubsan_handle_*() calls are like WARN(), they only happen when
3399	* something 'BAD' happened. At the risk of taking the machine down,
3400	* let them proceed to get the message out.
3401	*/
3402	if (!strncmp(func->name, "__ubsan_handle_", 15))
3403	return true;
3404
3405	return false;
3406	}
3407
3408	static int validate_call(struct objtool_file *file,
3409	struct instruction *insn,
3410	struct insn_state *state)
3411	{
3412	if (state->noinstr && state->instr <= 0 &&
3413	!noinstr_call_dest(file, insn, insn_call_dest(insn))) {
3414	WARN_INSN(insn, "call to %s() leaves .noinstr.text section", call_dest_name(insn));
3415	return 1;
3416	}
3417
3418	if (state->uaccess && !func_uaccess_safe(func: insn_call_dest(insn))) {
3419	WARN_INSN(insn, "call to %s() with UACCESS enabled", call_dest_name(insn));
3420	return 1;
3421	}
3422
3423	if (state->df) {
3424	WARN_INSN(insn, "call to %s() with DF set", call_dest_name(insn));
3425	return 1;
3426	}
3427
3428	return 0;
3429	}
3430
3431	static int validate_sibling_call(struct objtool_file *file,
3432	struct instruction *insn,
3433	struct insn_state *state)
3434	{
3435	if (insn_func(insn) && has_modified_stack_frame(insn, state)) {
3436	WARN_INSN(insn, "sibling call from callable instruction with modified stack frame");
3437	return 1;
3438	}
3439
3440	return validate_call(file, insn, state);
3441	}
3442
3443	static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
3444	{
3445	if (state->noinstr && state->instr > 0) {
3446	WARN_INSN(insn, "return with instrumentation enabled");
3447	return 1;
3448	}
3449
3450	if (state->uaccess && !func_uaccess_safe(func)) {
3451	WARN_INSN(insn, "return with UACCESS enabled");
3452	return 1;
3453	}
3454
3455	if (!state->uaccess && func_uaccess_safe(func)) {
3456	WARN_INSN(insn, "return with UACCESS disabled from a UACCESS-safe function");
3457	return 1;
3458	}
3459
3460	if (state->df) {
3461	WARN_INSN(insn, "return with DF set");
3462	return 1;
3463	}
3464
3465	if (func && has_modified_stack_frame(insn, state)) {
3466	WARN_INSN(insn, "return with modified stack frame");
3467	return 1;
3468	}
3469
3470	if (state->cfi.bp_scratch) {
3471	WARN_INSN(insn, "BP used as a scratch register");
3472	return 1;
3473	}
3474
3475	return 0;
3476	}
3477
3478	static struct instruction *next_insn_to_validate(struct objtool_file *file,
3479	struct instruction *insn)
3480	{
3481	struct alt_group *alt_group = insn->alt_group;
3482
3483	/*
3484	* Simulate the fact that alternatives are patched in-place. When the
3485	* end of a replacement alt_group is reached, redirect objtool flow to
3486	* the end of the original alt_group.
3487	*
3488	* insn->alts->insn -> alt_group->first_insn
3489	* ...
3490	* alt_group->last_insn
3491	* [alt_group->nop] -> next(orig_group->last_insn)
3492	*/
3493	if (alt_group) {
3494	if (alt_group->nop) {
3495	/* ->nop implies ->orig_group */
3496	if (insn == alt_group->last_insn)
3497	return alt_group->nop;
3498	if (insn == alt_group->nop)
3499	goto next_orig;
3500	}
3501	if (insn == alt_group->last_insn && alt_group->orig_group)
3502	goto next_orig;
3503	}
3504
3505	return next_insn_same_sec(file, insn);
3506
3507	next_orig:
3508	return next_insn_same_sec(file, insn: alt_group->orig_group->last_insn);
3509	}
3510
3511	static bool skip_alt_group(struct instruction *insn)
3512	{
3513	struct instruction *alt_insn = insn->alts ? insn->alts->insn : NULL;
3514
3515	/* ANNOTATE_IGNORE_ALTERNATIVE */
3516	if (insn->alt_group && insn->alt_group->ignore)
3517	return true;
3518
3519	/*
3520	* For NOP patched with CLAC/STAC, only follow the latter to avoid
3521	* impossible code paths combining patched CLAC with unpatched STAC
3522	* or vice versa.
3523	*
3524	* ANNOTATE_IGNORE_ALTERNATIVE could have been used here, but Linus
3525	* requested not to do that to avoid hurting .s file readability
3526	* around CLAC/STAC alternative sites.
3527	*/
3528
3529	if (!alt_insn)
3530	return false;
3531
3532	/* Don't override ASM_{CLAC,STAC}_UNSAFE */
3533	if (alt_insn->alt_group && alt_insn->alt_group->ignore)
3534	return false;
3535
3536	return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
3537	}
3538
3539	/*
3540	* Follow the branch starting at the given instruction, and recursively follow
3541	* any other branches (jumps). Meanwhile, track the frame pointer state at
3542	* each instruction and validate all the rules described in
3543	* tools/objtool/Documentation/objtool.txt.
3544	*/
3545	static int validate_branch(struct objtool_file *file, struct symbol *func,
3546	struct instruction *insn, struct insn_state state)
3547	{
3548	struct alternative *alt;
3549	struct instruction *next_insn, *prev_insn = NULL;
3550	struct section *sec;
3551	u8 visited;
3552	int ret;
3553
3554	if (func && func->ignore)
3555	return 0;
3556
3557	sec = insn->sec;
3558
3559	while (1) {
3560	next_insn = next_insn_to_validate(file, insn);
3561
3562	if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
3563	/* Ignore KCFI type preambles, which always fall through */
3564	if (!strncmp(func->name, "__cfi_", 6) ||
3565	!strncmp(func->name, "__pfx_", 6))
3566	return 0;
3567
3568	if (file->ignore_unreachables)
3569	return 0;
3570
3571	WARN("%s() falls through to next function %s()",
3572	func->name, insn_func(insn)->name);
3573	func->warned = 1;
3574
3575	return 1;
3576	}
3577
3578	visited = VISITED_BRANCH << state.uaccess;
3579	if (insn->visited & VISITED_BRANCH_MASK) {
3580	if (!insn->hint && !insn_cfi_match(insn, cfi2: &state.cfi))
3581	return 1;
3582
3583	if (insn->visited & visited)
3584	return 0;
3585	} else {
3586	nr_insns_visited++;
3587	}
3588
3589	if (state.noinstr)
3590	state.instr += insn->instr;
3591
3592	if (insn->hint) {
3593	if (insn->restore) {
3594	struct instruction *save_insn, *i;
3595
3596	i = insn;
3597	save_insn = NULL;
3598
3599	sym_for_each_insn_continue_reverse(file, func, i) {
3600	if (i->save) {
3601	save_insn = i;
3602	break;
3603	}
3604	}
3605
3606	if (!save_insn) {
3607	WARN_INSN(insn, "no corresponding CFI save for CFI restore");
3608	return 1;
3609	}
3610
3611	if (!save_insn->visited) {
3612	/*
3613	* If the restore hint insn is at the
3614	* beginning of a basic block and was
3615	* branched to from elsewhere, and the
3616	* save insn hasn't been visited yet,
3617	* defer following this branch for now.
3618	* It will be seen later via the
3619	* straight-line path.
3620	*/
3621	if (!prev_insn)
3622	return 0;
3623
3624	WARN_INSN(insn, "objtool isn't smart enough to handle this CFI save/restore combo");
3625	return 1;
3626	}
3627
3628	insn->cfi = save_insn->cfi;
3629	nr_cfi_reused++;
3630	}
3631
3632	state.cfi = *insn->cfi;
3633	} else {
3634	/* XXX track if we actually changed state.cfi */
3635
3636	if (prev_insn && !cficmp(cfi1: prev_insn->cfi, cfi2: &state.cfi)) {
3637	insn->cfi = prev_insn->cfi;
3638	nr_cfi_reused++;
3639	} else {
3640	insn->cfi = cfi_hash_find_or_add(cfi: &state.cfi);
3641	}
3642	}
3643
3644	insn->visited |= visited;
3645
3646	if (propagate_alt_cfi(file, insn))
3647	return 1;
3648
3649	if (insn->alts) {
3650	for (alt = insn->alts; alt; alt = alt->next) {
3651	ret = validate_branch(file, func, insn: alt->insn, state: state);
3652	if (ret) {
3653	BT_INSN(insn, "(alt)");
3654	return ret;
3655	}
3656	}
3657	}
3658
3659	if (skip_alt_group(insn))
3660	return 0;
3661
3662	if (handle_insn_ops(insn, next_insn, state: &state))
3663	return 1;
3664
3665	switch (insn->type) {
3666
3667	case INSN_RETURN:
3668	return validate_return(func, insn, state: &state);
3669
3670	case INSN_CALL:
3671	case INSN_CALL_DYNAMIC:
3672	ret = validate_call(file, insn, state: &state);
3673	if (ret)
3674	return ret;
3675
3676	if (opts.stackval && func && !is_special_call(insn) &&
3677	!has_valid_stack_frame(&state)) {
3678	WARN_INSN(insn, "call without frame pointer save/setup");
3679	return 1;
3680	}
3681
3682	break;
3683
3684	case INSN_JUMP_CONDITIONAL:
3685	case INSN_JUMP_UNCONDITIONAL:
3686	if (is_sibling_call(insn)) {
3687	ret = validate_sibling_call(file, insn, state: &state);
3688	if (ret)
3689	return ret;
3690
3691	} else if (insn->jump_dest) {
3692	ret = validate_branch(file, func,
3693	insn: insn->jump_dest, state: state);
3694	if (ret) {
3695	BT_INSN(insn, "(branch)");
3696	return ret;
3697	}
3698	}
3699
3700	if (insn->type == INSN_JUMP_UNCONDITIONAL)
3701	return 0;
3702
3703	break;
3704
3705	case INSN_JUMP_DYNAMIC:
3706	case INSN_JUMP_DYNAMIC_CONDITIONAL:
3707	if (is_sibling_call(insn)) {
3708	ret = validate_sibling_call(file, insn, state: &state);
3709	if (ret)
3710	return ret;
3711	}
3712
3713	if (insn->type == INSN_JUMP_DYNAMIC)
3714	return 0;
3715
3716	break;
3717
3718	case INSN_SYSCALL:
3719	if (func && (!next_insn || !next_insn->hint)) {
3720	WARN_INSN(insn, "unsupported instruction in callable function");
3721	return 1;
3722	}
3723
3724	break;
3725
3726	case INSN_SYSRET:
3727	if (func && (!next_insn || !next_insn->hint)) {
3728	WARN_INSN(insn, "unsupported instruction in callable function");
3729	return 1;
3730	}
3731
3732	return 0;
3733
3734	case INSN_STAC:
3735	if (!opts.uaccess)
3736	break;
3737
3738	if (state.uaccess) {
3739	WARN_INSN(insn, "recursive UACCESS enable");
3740	return 1;
3741	}
3742
3743	state.uaccess = true;
3744	break;
3745
3746	case INSN_CLAC:
3747	if (!opts.uaccess)
3748	break;
3749
3750	if (!state.uaccess && func) {
3751	WARN_INSN(insn, "redundant UACCESS disable");
3752	return 1;
3753	}
3754
3755	if (func_uaccess_safe(func) && !state.uaccess_stack) {
3756	WARN_INSN(insn, "UACCESS-safe disables UACCESS");
3757	return 1;
3758	}
3759
3760	state.uaccess = false;
3761	break;
3762
3763	case INSN_STD:
3764	if (state.df) {
3765	WARN_INSN(insn, "recursive STD");
3766	return 1;
3767	}
3768
3769	state.df = true;
3770	break;
3771
3772	case INSN_CLD:
3773	if (!state.df && func) {
3774	WARN_INSN(insn, "redundant CLD");
3775	return 1;
3776	}
3777
3778	state.df = false;
3779	break;
3780
3781	default:
3782	break;
3783	}
3784
3785	if (insn->dead_end)
3786	return 0;
3787
3788	if (!next_insn) {
3789	if (state.cfi.cfa.base == CFI_UNDEFINED)
3790	return 0;
3791	if (file->ignore_unreachables)
3792	return 0;
3793
3794	WARN("%s%sunexpected end of section %s",
3795	func ? func->name : "", func ? "(): " : "",
3796	sec->name);
3797	return 1;
3798	}
3799
3800	prev_insn = insn;
3801	insn = next_insn;
3802	}
3803
3804	return 0;
3805	}
3806
3807	static int validate_unwind_hint(struct objtool_file *file,
3808	struct instruction *insn,
3809	struct insn_state *state)
3810	{
3811	if (insn->hint && !insn->visited) {
3812	int ret = validate_branch(file, insn_func(insn), insn, *state);
3813	if (ret)
3814	BT_INSN(insn, "<=== (hint)");
3815	return ret;
3816	}
3817
3818	return 0;
3819	}
3820
3821	static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
3822	{
3823	struct instruction *insn;
3824	struct insn_state state;
3825	int warnings = 0;
3826
3827	if (!file->hints)
3828	return 0;
3829
3830	init_insn_state(file, state: &state, sec);
3831
3832	if (sec) {
3833	sec_for_each_insn(file, sec, insn)
3834	warnings += validate_unwind_hint(file, insn, state: &state);
3835	} else {
3836	for_each_insn(file, insn)
3837	warnings += validate_unwind_hint(file, insn, &state);
3838	}
3839
3840	return warnings;
3841	}
3842
3843	/*
3844	* Validate rethunk entry constraint: must untrain RET before the first RET.
3845	*
3846	* Follow every branch (intra-function) and ensure VALIDATE_UNRET_END comes
3847	* before an actual RET instruction.
3848	*/
3849	static int validate_unret(struct objtool_file *file, struct instruction *insn)
3850	{
3851	struct instruction *next, *dest;
3852	int ret;
3853
3854	for (;;) {
3855	next = next_insn_to_validate(file, insn);
3856
3857	if (insn->visited & VISITED_UNRET)
3858	return 0;
3859
3860	insn->visited |= VISITED_UNRET;
3861
3862	if (insn->alts) {
3863	struct alternative *alt;
3864	for (alt = insn->alts; alt; alt = alt->next) {
3865	ret = validate_unret(file, insn: alt->insn);
3866	if (ret) {
3867	BT_INSN(insn, "(alt)");
3868	return ret;
3869	}
3870	}
3871	}
3872
3873	switch (insn->type) {
3874
3875	case INSN_CALL_DYNAMIC:
3876	case INSN_JUMP_DYNAMIC:
3877	case INSN_JUMP_DYNAMIC_CONDITIONAL:
3878	WARN_INSN(insn, "early indirect call");
3879	return 1;
3880
3881	case INSN_JUMP_UNCONDITIONAL:
3882	case INSN_JUMP_CONDITIONAL:
3883	if (!is_sibling_call(insn)) {
3884	if (!insn->jump_dest) {
3885	WARN_INSN(insn, "unresolved jump target after linking?!?");
3886	return 1;
3887	}
3888	ret = validate_unret(file, insn: insn->jump_dest);
3889	if (ret) {
3890	BT_INSN(insn, "(branch%s)",
3891	insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
3892	return ret;
3893	}
3894
3895	if (insn->type == INSN_JUMP_UNCONDITIONAL)
3896	return 0;
3897
3898	break;
3899	}
3900
3901	/* fallthrough */
3902	case INSN_CALL:
3903	dest = find_insn(file, sec: insn_call_dest(insn)->sec,
3904	offset: insn_call_dest(insn)->offset);
3905	if (!dest) {
3906	WARN("Unresolved function after linking!?: %s",
3907	insn_call_dest(insn)->name);
3908	return 1;
3909	}
3910
3911	ret = validate_unret(file, insn: dest);
3912	if (ret) {
3913	BT_INSN(insn, "(call)");
3914	return ret;
3915	}
3916	/*
3917	* If a call returns without error, it must have seen UNTRAIN_RET.
3918	* Therefore any non-error return is a success.
3919	*/
3920	return 0;
3921
3922	case INSN_RETURN:
3923	WARN_INSN(insn, "RET before UNTRAIN");
3924	return 1;
3925
3926	case INSN_SYSCALL:
3927	break;
3928
3929	case INSN_SYSRET:
3930	return 0;
3931
3932	case INSN_NOP:
3933	if (insn->retpoline_safe)
3934	return 0;
3935	break;
3936
3937	default:
3938	break;
3939	}
3940
3941	if (insn->dead_end)
3942	return 0;
3943
3944	if (!next) {
3945	WARN_INSN(insn, "teh end!");
3946	return 1;
3947	}
3948	insn = next;
3949	}
3950
3951	return 0;
3952	}
3953
3954	/*
3955	* Validate that all branches starting at VALIDATE_UNRET_BEGIN encounter
3956	* VALIDATE_UNRET_END before RET.
3957	*/
3958	static int validate_unrets(struct objtool_file *file)
3959	{
3960	struct instruction *insn;
3961	int warnings = 0;
3962
3963	for_each_insn(file, insn) {
3964	if (!insn->unret)
3965	continue;
3966
3967	warnings += validate_unret(file, insn);
3968	}
3969
3970	return warnings;
3971	}
3972
3973	static int validate_retpoline(struct objtool_file *file)
3974	{
3975	struct instruction *insn;
3976	int warnings = 0;
3977
3978	for_each_insn(file, insn) {
3979	if (insn->type != INSN_JUMP_DYNAMIC &&
3980	insn->type != INSN_CALL_DYNAMIC &&
3981	insn->type != INSN_RETURN)
3982	continue;
3983
3984	if (insn->retpoline_safe)
3985	continue;
3986
3987	if (insn->sec->init)
3988	continue;
3989
3990	if (insn->type == INSN_RETURN) {
3991	if (opts.rethunk) {
3992	WARN_INSN(insn, "'naked' return found in MITIGATION_RETHUNK build");
3993	warnings++;
3994	}
3995	continue;
3996	}
3997
3998	WARN_INSN(insn, "indirect %s found in MITIGATION_RETPOLINE build",
3999	insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
4000	warnings++;
4001	}
4002
4003	return warnings;
4004	}
4005
4006	static bool is_kasan_insn(struct instruction *insn)
4007	{
4008	return (insn->type == INSN_CALL &&
4009	!strcmp(insn_call_dest(insn)->name, "__asan_handle_no_return"));
4010	}
4011
4012	static bool is_ubsan_insn(struct instruction *insn)
4013	{
4014	return (insn->type == INSN_CALL &&
4015	!strcmp(insn_call_dest(insn)->name,
4016	"__ubsan_handle_builtin_unreachable"));
4017	}
4018
4019	static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
4020	{
4021	struct symbol *func = insn_func(insn);
4022	struct instruction *prev_insn;
4023	int i;
4024
4025	if (insn->type == INSN_NOP || insn->type == INSN_TRAP || (func && func->ignore))
4026	return true;
4027
4028	/*
4029	* Ignore alternative replacement instructions. This can happen
4030	* when a whitelisted function uses one of the ALTERNATIVE macros.
4031	*/
4032	if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
4033	!strcmp(insn->sec->name, ".altinstr_aux"))
4034	return true;
4035
4036	/*
4037	* Whole archive runs might encounter dead code from weak symbols.
4038	* This is where the linker will have dropped the weak symbol in
4039	* favour of a regular symbol, but leaves the code in place.
4040	*
4041	* In this case we'll find a piece of code (whole function) that is not
4042	* covered by a !section symbol. Ignore them.
4043	*/
4044	if (opts.link && !func) {
4045	int size = find_symbol_hole_containing(insn->sec, insn->offset);
4046	unsigned long end = insn->offset + size;
4047
4048	if (!size) /* not a hole */
4049	return false;
4050
4051	if (size < 0) /* hole until the end */
4052	return true;
4053
4054	sec_for_each_insn_continue(file, insn) {
4055	/*
4056	* If we reach a visited instruction at or before the
4057	* end of the hole, ignore the unreachable.
4058	*/
4059	if (insn->visited)
4060	return true;
4061
4062	if (insn->offset >= end)
4063	break;
4064
4065	/*
4066	* If this hole jumps to a .cold function, mark it ignore too.
4067	*/
4068	if (insn->jump_dest && insn_func(insn->jump_dest) &&
4069	strstr(insn_func(insn->jump_dest)->name, ".cold")) {
4070	insn_func(insn->jump_dest)->ignore = true;
4071	}
4072	}
4073
4074	return false;
4075	}
4076
4077	if (!func)
4078	return false;
4079
4080	if (func->static_call_tramp)
4081	return true;
4082
4083	/*
4084	* CONFIG_UBSAN_TRAP inserts a UD2 when it sees
4085	* __builtin_unreachable(). The BUG() macro has an unreachable() after
4086	* the UD2, which causes GCC's undefined trap logic to emit another UD2
4087	* (or occasionally a JMP to UD2).
4088	*
4089	* It may also insert a UD2 after calling a __noreturn function.
4090	*/
4091	prev_insn = prev_insn_same_sec(file, insn);
4092	if (prev_insn && prev_insn->dead_end &&
4093	(insn->type == INSN_BUG ||
4094	(insn->type == INSN_JUMP_UNCONDITIONAL &&
4095	insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
4096	return true;
4097
4098	/*
4099	* Check if this (or a subsequent) instruction is related to
4100	* CONFIG_UBSAN or CONFIG_KASAN.
4101	*
4102	* End the search at 5 instructions to avoid going into the weeds.
4103	*/
4104	for (i = 0; i < 5; i++) {
4105
4106	if (is_kasan_insn(insn) || is_ubsan_insn(insn))
4107	return true;
4108
4109	if (insn->type == INSN_JUMP_UNCONDITIONAL) {
4110	if (insn->jump_dest &&
4111	insn_func(insn->jump_dest) == func) {
4112	insn = insn->jump_dest;
4113	continue;
4114	}
4115
4116	break;
4117	}
4118
4119	if (insn->offset + insn->len >= func->offset + func->len)
4120	break;
4121
4122	insn = next_insn_same_sec(file, insn);
4123	}
4124
4125	return false;
4126	}
4127
4128	static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
4129	{
4130	struct instruction *insn, *prev;
4131	struct cfi_state *cfi;
4132
4133	insn = find_insn(file, sec: func->sec, offset: func->offset);
4134	if (!insn)
4135	return -1;
4136
4137	for (prev = prev_insn_same_sec(file, insn);
4138	prev;
4139	prev = prev_insn_same_sec(file, insn: prev)) {
4140	u64 offset;
4141
4142	if (prev->type != INSN_NOP)
4143	return -1;
4144
4145	offset = func->offset - prev->offset;
4146
4147	if (offset > opts.prefix)
4148	return -1;
4149
4150	if (offset < opts.prefix)
4151	continue;
4152
4153	elf_create_prefix_symbol(file->elf, func, opts.prefix);
4154	break;
4155	}
4156
4157	if (!prev)
4158	return -1;
4159
4160	if (!insn->cfi) {
4161	/*
4162	* This can happen if stack validation isn't enabled or the
4163	* function is annotated with STACK_FRAME_NON_STANDARD.
4164	*/
4165	return 0;
4166	}
4167
4168	/* Propagate insn->cfi to the prefix code */
4169	cfi = cfi_hash_find_or_add(cfi: insn->cfi);
4170	for (; prev != insn; prev = next_insn_same_sec(file, insn: prev))
4171	prev->cfi = cfi;
4172
4173	return 0;
4174	}
4175
4176	static int add_prefix_symbols(struct objtool_file *file)
4177	{
4178	struct section *sec;
4179	struct symbol *func;
4180
4181	for_each_sec(file, sec) {
4182	if (!(sec->sh.sh_flags & SHF_EXECINSTR))
4183	continue;
4184
4185	sec_for_each_sym(sec, func) {
4186	if (func->type != STT_FUNC)
4187	continue;
4188
4189	add_prefix_symbol(file, func);
4190	}
4191	}
4192
4193	return 0;
4194	}
4195
4196	static int validate_symbol(struct objtool_file *file, struct section *sec,
4197	struct symbol *sym, struct insn_state *state)
4198	{
4199	struct instruction *insn;
4200	int ret;
4201
4202	if (!sym->len) {
4203	WARN("%s() is missing an ELF size annotation", sym->name);
4204	return 1;
4205	}
4206
4207	if (sym->pfunc != sym || sym->alias != sym)
4208	return 0;
4209
4210	insn = find_insn(file, sec, offset: sym->offset);
4211	if (!insn || insn->visited)
4212	return 0;
4213
4214	if (opts.uaccess)
4215	state->uaccess = sym->uaccess_safe;
4216
4217	ret = validate_branch(file, insn_func(insn), insn, *state);
4218	if (ret)
4219	BT_INSN(insn, "<=== (sym)");
4220	return ret;
4221	}
4222
4223	static int validate_section(struct objtool_file *file, struct section *sec)
4224	{
4225	struct insn_state state;
4226	struct symbol *func;
4227	int warnings = 0;
4228
4229	sec_for_each_sym(sec, func) {
4230	if (func->type != STT_FUNC)
4231	continue;
4232
4233	init_insn_state(file, state: &state, sec);
4234	set_func_state(&state.cfi);
4235
4236	warnings += validate_symbol(file, sec, sym: func, state: &state);
4237	}
4238
4239	return warnings;
4240	}
4241
4242	static int validate_noinstr_sections(struct objtool_file *file)
4243	{
4244	struct section *sec;
4245	int warnings = 0;
4246
4247	sec = find_section_by_name(file->elf, ".noinstr.text");
4248	if (sec) {
4249	warnings += validate_section(file, sec);
4250	warnings += validate_unwind_hints(file, sec);
4251	}
4252
4253	sec = find_section_by_name(file->elf, ".entry.text");
4254	if (sec) {
4255	warnings += validate_section(file, sec);
4256	warnings += validate_unwind_hints(file, sec);
4257	}
4258
4259	sec = find_section_by_name(file->elf, ".cpuidle.text");
4260	if (sec) {
4261	warnings += validate_section(file, sec);
4262	warnings += validate_unwind_hints(file, sec);
4263	}
4264
4265	return warnings;
4266	}
4267
4268	static int validate_functions(struct objtool_file *file)
4269	{
4270	struct section *sec;
4271	int warnings = 0;
4272
4273	for_each_sec(file, sec) {
4274	if (!(sec->sh.sh_flags & SHF_EXECINSTR))
4275	continue;
4276
4277	warnings += validate_section(file, sec);
4278	}
4279
4280	return warnings;
4281	}
4282
4283	static void mark_endbr_used(struct instruction *insn)
4284	{
4285	if (!list_empty(head: &insn->call_node))
4286	list_del_init(entry: &insn->call_node);
4287	}
4288
4289	static bool noendbr_range(struct objtool_file *file, struct instruction *insn)
4290	{
4291	struct symbol *sym = find_symbol_containing(insn->sec, insn->offset-1);
4292	struct instruction *first;
4293
4294	if (!sym)
4295	return false;
4296
4297	first = find_insn(file, sec: sym->sec, offset: sym->offset);
4298	if (!first)
4299	return false;
4300
4301	if (first->type != INSN_ENDBR && !first->noendbr)
4302	return false;
4303
4304	return insn->offset == sym->offset + sym->len;
4305	}
4306
4307	static int __validate_ibt_insn(struct objtool_file *file, struct instruction *insn,
4308	struct instruction *dest)
4309	{
4310	if (dest->type == INSN_ENDBR) {
4311	mark_endbr_used(insn: dest);
4312	return 0;
4313	}
4314
4315	if (insn_func(dest) && insn_func(insn) &&
4316	insn_func(dest)->pfunc == insn_func(insn)->pfunc) {
4317	/*
4318	* Anything from->to self is either _THIS_IP_ or
4319	* IRET-to-self.
4320	*
4321	* There is no sane way to annotate _THIS_IP_ since the
4322	* compiler treats the relocation as a constant and is
4323	* happy to fold in offsets, skewing any annotation we
4324	* do, leading to vast amounts of false-positives.
4325	*
4326	* There's also compiler generated _THIS_IP_ through
4327	* KCOV and such which we have no hope of annotating.
4328	*
4329	* As such, blanket accept self-references without
4330	* issue.
4331	*/
4332	return 0;
4333	}
4334
4335	/*
4336	* Accept anything ANNOTATE_NOENDBR.
4337	*/
4338	if (dest->noendbr)
4339	return 0;
4340
4341	/*
4342	* Accept if this is the instruction after a symbol
4343	* that is (no)endbr -- typical code-range usage.
4344	*/
4345	if (noendbr_range(file, insn: dest))
4346	return 0;
4347
4348	WARN_INSN(insn, "relocation to !ENDBR: %s", offstr(dest->sec, dest->offset));
4349	return 1;
4350	}
4351
4352	static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
4353	{
4354	struct instruction *dest;
4355	struct reloc *reloc;
4356	unsigned long off;
4357	int warnings = 0;
4358
4359	/*
4360	* Looking for function pointer load relocations. Ignore
4361	* direct/indirect branches:
4362	*/
4363	switch (insn->type) {
4364
4365	case INSN_CALL:
4366	case INSN_CALL_DYNAMIC:
4367	case INSN_JUMP_CONDITIONAL:
4368	case INSN_JUMP_UNCONDITIONAL:
4369	case INSN_JUMP_DYNAMIC:
4370	case INSN_JUMP_DYNAMIC_CONDITIONAL:
4371	case INSN_RETURN:
4372	case INSN_NOP:
4373	return 0;
4374
4375	case INSN_LEA_RIP:
4376	if (!insn_reloc(file, insn)) {
4377	/* local function pointer reference without reloc */
4378
4379	off = arch_jump_destination(insn);
4380
4381	dest = find_insn(file, sec: insn->sec, offset: off);
4382	if (!dest) {
4383	WARN_INSN(insn, "corrupt function pointer reference");
4384	return 1;
4385	}
4386
4387	return __validate_ibt_insn(file, insn, dest);
4388	}
4389	break;
4390
4391	default:
4392	break;
4393	}
4394
4395	for (reloc = insn_reloc(file, insn);
4396	reloc;
4397	reloc = find_reloc_by_dest_range(file->elf, insn->sec,
4398	reloc_offset(reloc) + 1,
4399	(insn->offset + insn->len) - (reloc_offset(reloc) + 1))) {
4400
4401	off = reloc->sym->offset;
4402	if (reloc_type(reloc) == R_X86_64_PC32 ||
4403	reloc_type(reloc) == R_X86_64_PLT32)
4404	off += arch_dest_reloc_offset(reloc_addend(reloc));
4405	else
4406	off += reloc_addend(reloc);
4407
4408	dest = find_insn(file, sec: reloc->sym->sec, offset: off);
4409	if (!dest)
4410	continue;
4411
4412	warnings += __validate_ibt_insn(file, insn, dest);
4413	}
4414
4415	return warnings;
4416	}
4417
4418	static int validate_ibt_data_reloc(struct objtool_file *file,
4419	struct reloc *reloc)
4420	{
4421	struct instruction *dest;
4422
4423	dest = find_insn(file, sec: reloc->sym->sec,
4424	offset: reloc->sym->offset + reloc_addend(reloc));
4425	if (!dest)
4426	return 0;
4427
4428	if (dest->type == INSN_ENDBR) {
4429	mark_endbr_used(insn: dest);
4430	return 0;
4431	}
4432
4433	if (dest->noendbr)
4434	return 0;
4435
4436	WARN_FUNC(reloc->sec->base, reloc_offset(reloc),
4437	"data relocation to !ENDBR: %s", offstr(dest->sec, dest->offset));
4438
4439	return 1;
4440	}
4441
4442	/*
4443	* Validate IBT rules and remove used ENDBR instructions from the seal list.
4444	* Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
4445	* NOPs) later, in create_ibt_endbr_seal_sections().
4446	*/
4447	static int validate_ibt(struct objtool_file *file)
4448	{
4449	struct section *sec;
4450	struct reloc *reloc;
4451	struct instruction *insn;
4452	int warnings = 0;
4453
4454	for_each_insn(file, insn)
4455	warnings += validate_ibt_insn(file, insn);
4456
4457	for_each_sec(file, sec) {
4458
4459	/* Already done by validate_ibt_insn() */
4460	if (sec->sh.sh_flags & SHF_EXECINSTR)
4461	continue;
4462
4463	if (!sec->rsec)
4464	continue;
4465
4466	/*
4467	* These sections can reference text addresses, but not with
4468	* the intent to indirect branch to them.
4469	*/
4470	if ((!strncmp(sec->name, ".discard", 8) &&
4471	strcmp(sec->name, ".discard.ibt_endbr_noseal")) ||
4472	!strncmp(sec->name, ".debug", 6) ||
4473	!strcmp(sec->name, ".altinstructions") ||
4474	!strcmp(sec->name, ".ibt_endbr_seal") ||
4475	!strcmp(sec->name, ".orc_unwind_ip") ||
4476	!strcmp(sec->name, ".parainstructions") ||
4477	!strcmp(sec->name, ".retpoline_sites") ||
4478	!strcmp(sec->name, ".smp_locks") ||
4479	!strcmp(sec->name, ".static_call_sites") ||
4480	!strcmp(sec->name, "_error_injection_whitelist") ||
4481	!strcmp(sec->name, "_kprobe_blacklist") ||
4482	!strcmp(sec->name, "__bug_table") ||
4483	!strcmp(sec->name, "__ex_table") ||
4484	!strcmp(sec->name, "__jump_table") ||
4485	!strcmp(sec->name, "__mcount_loc") ||
4486	!strcmp(sec->name, ".kcfi_traps") ||
4487	!strcmp(sec->name, ".llvm.call-graph-profile") ||
4488	!strcmp(sec->name, ".llvm_bb_addr_map") ||
4489	!strcmp(sec->name, "__tracepoints") ||
4490	strstr(sec->name, "__patchable_function_entries"))
4491	continue;
4492
4493	for_each_reloc(sec->rsec, reloc)
4494	warnings += validate_ibt_data_reloc(file, reloc);
4495	}
4496
4497	return warnings;
4498	}
4499
4500	static int validate_sls(struct objtool_file *file)
4501	{
4502	struct instruction *insn, *next_insn;
4503	int warnings = 0;
4504
4505	for_each_insn(file, insn) {
4506	next_insn = next_insn_same_sec(file, insn);
4507
4508	if (insn->retpoline_safe)
4509	continue;
4510
4511	switch (insn->type) {
4512	case INSN_RETURN:
4513	if (!next_insn || next_insn->type != INSN_TRAP) {
4514	WARN_INSN(insn, "missing int3 after ret");
4515	warnings++;
4516	}
4517
4518	break;
4519	case INSN_JUMP_DYNAMIC:
4520	if (!next_insn || next_insn->type != INSN_TRAP) {
4521	WARN_INSN(insn, "missing int3 after indirect jump");
4522	warnings++;
4523	}
4524	break;
4525	default:
4526	break;
4527	}
4528	}
4529
4530	return warnings;
4531	}
4532
4533	static int validate_reachable_instructions(struct objtool_file *file)
4534	{
4535	struct instruction *insn, *prev_insn;
4536	struct symbol *call_dest;
4537	int warnings = 0;
4538
4539	if (file->ignore_unreachables)
4540	return 0;
4541
4542	for_each_insn(file, insn) {
4543	if (insn->visited || ignore_unreachable_insn(file, insn))
4544	continue;
4545
4546	prev_insn = prev_insn_same_sec(file, insn);
4547	if (prev_insn && prev_insn->dead_end) {
4548	call_dest = insn_call_dest(prev_insn);
4549	if (call_dest) {
4550	WARN_INSN(insn, "%s() missing __noreturn in .c/.h or NORETURN() in noreturns.h",
4551	call_dest->name);
4552	warnings++;
4553	continue;
4554	}
4555	}
4556
4557	WARN_INSN(insn, "unreachable instruction");
4558	warnings++;
4559	}
4560
4561	return warnings;
4562	}
4563
4564	/* 'funcs' is a space-separated list of function names */
4565	static void disas_funcs(const char *funcs)
4566	{
4567	const char *objdump_str, *cross_compile;
4568	int size, ret;
4569	char *cmd;
4570
4571	cross_compile = getenv("CROSS_COMPILE");
4572	if (!cross_compile)
4573	cross_compile = "";
4574
4575	objdump_str = "%sobjdump -wdr %s | gawk -M -v _funcs='%s' '"
4576	"BEGIN { split(_funcs, funcs); }"
4577	"/^$/ { func_match = 0; }"
4578	"/<.*>:/ { "
4579	"f = gensub(/.*<(.*)>:/, \"\\\\1\", 1);"
4580	"for (i in funcs) {"
4581	"if (funcs[i] == f) {"
4582	"func_match = 1;"
4583	"base = strtonum(\"0x\" $1);"
4584	"break;"
4585	"}"
4586	"}"
4587	"}"
4588	"{"
4589	"if (func_match) {"
4590	"addr = strtonum(\"0x\" $1);"
4591	"printf(\"%%04x \", addr - base);"
4592	"print;"
4593	"}"
4594	"}' 1>&2";
4595
4596	/* fake snprintf() to calculate the size */
4597	size = snprintf(NULL, 0, objdump_str, cross_compile, objname, funcs) + 1;
4598	if (size <= 0) {
4599	WARN("objdump string size calculation failed");
4600	return;
4601	}
4602
4603	cmd = malloc(size);
4604
4605	/* real snprintf() */
4606	snprintf(cmd, size, objdump_str, cross_compile, objname, funcs);
4607	ret = system(cmd);
4608	if (ret) {
4609	WARN("disassembly failed: %d", ret);
4610	return;
4611	}
4612	}
4613
4614	static void disas_warned_funcs(struct objtool_file *file)
4615	{
4616	struct symbol *sym;
4617	char *funcs = NULL, *tmp;
4618
4619	for_each_sym(file, sym) {
4620	if (sym->warned) {
4621	if (!funcs) {
4622	funcs = malloc(strlen(sym->name) + 1);
4623	if (!funcs) {
4624	ERROR_GLIBC("malloc");
4625	return;
4626	}
4627	strcpy(funcs, sym->name);
4628	} else {
4629	tmp = malloc(strlen(funcs) + strlen(sym->name) + 2);
4630	if (!tmp) {
4631	ERROR_GLIBC("malloc");
4632	return;
4633	}
4634	sprintf(buf: tmp, fmt: "%s %s", funcs, sym->name);
4635	free(funcs);
4636	funcs = tmp;
4637	}
4638	}
4639	}
4640
4641	if (funcs)
4642	disas_funcs(funcs);
4643	}
4644
4645	struct insn_chunk {
4646	void *addr;
4647	struct insn_chunk *next;
4648	};
4649
4650	/*
4651	* Reduce peak RSS usage by freeing insns memory before writing the ELF file,
4652	* which can trigger more allocations for .debug_* sections whose data hasn't
4653	* been read yet.
4654	*/
4655	static void free_insns(struct objtool_file *file)
4656	{
4657	struct instruction *insn;
4658	struct insn_chunk *chunks = NULL, *chunk;
4659
4660	for_each_insn(file, insn) {
4661	if (!insn->idx) {
4662	chunk = malloc(sizeof(*chunk));
4663	chunk->addr = insn;
4664	chunk->next = chunks;
4665	chunks = chunk;
4666	}
4667	}
4668
4669	for (chunk = chunks; chunk; chunk = chunk->next)
4670	free(chunk->addr);
4671	}
4672
4673	int check(struct objtool_file *file)
4674	{
4675	int ret = 0, warnings = 0;
4676
4677	arch_initial_func_cfi_state(&initial_func_cfi);
4678	init_cfi_state(cfi: &init_cfi);
4679	init_cfi_state(cfi: &func_cfi);
4680	set_func_state(&func_cfi);
4681	init_cfi_state(cfi: &force_undefined_cfi);
4682	force_undefined_cfi.force_undefined = true;
4683
4684	if (!cfi_hash_alloc(size: 1UL << (file->elf->symbol_bits - 3))) {
4685	ret = -1;
4686	goto out;
4687	}
4688
4689	cfi_hash_add(cfi: &init_cfi);
4690	cfi_hash_add(cfi: &func_cfi);
4691
4692	ret = decode_sections(file);
4693	if (ret)
4694	goto out;
4695
4696	if (!nr_insns)
4697	goto out;
4698
4699	if (opts.retpoline)
4700	warnings += validate_retpoline(file);
4701
4702	if (opts.stackval || opts.orc || opts.uaccess) {
4703	int w = 0;
4704
4705	w += validate_functions(file);
4706	w += validate_unwind_hints(file, NULL);
4707	if (!w)
4708	w += validate_reachable_instructions(file);
4709
4710	warnings += w;
4711
4712	} else if (opts.noinstr) {
4713	warnings += validate_noinstr_sections(file);
4714	}
4715
4716	if (opts.unret) {
4717	/*
4718	* Must be after validate_branch() and friends, it plays
4719	* further games with insn->visited.
4720	*/
4721	warnings += validate_unrets(file);
4722	}
4723
4724	if (opts.ibt)
4725	warnings += validate_ibt(file);
4726
4727	if (opts.sls)
4728	warnings += validate_sls(file);
4729
4730	if (opts.static_call) {
4731	ret = create_static_call_sections(file);
4732	if (ret)
4733	goto out;
4734	}
4735
4736	if (opts.retpoline) {
4737	ret = create_retpoline_sites_sections(file);
4738	if (ret)
4739	goto out;
4740	}
4741
4742	if (opts.cfi) {
4743	ret = create_cfi_sections(file);
4744	if (ret)
4745	goto out;
4746	}
4747
4748	if (opts.rethunk) {
4749	ret = create_return_sites_sections(file);
4750	if (ret)
4751	goto out;
4752
4753	if (opts.hack_skylake) {
4754	ret = create_direct_call_sections(file);
4755	if (ret)
4756	goto out;
4757	}
4758	}
4759
4760	if (opts.mcount) {
4761	ret = create_mcount_loc_sections(file);
4762	if (ret)
4763	goto out;
4764	}
4765
4766	if (opts.prefix) {
4767	ret = add_prefix_symbols(file);
4768	if (ret)
4769	goto out;
4770	}
4771
4772	if (opts.ibt) {
4773	ret = create_ibt_endbr_seal_sections(file);
4774	if (ret)
4775	goto out;
4776	}
4777
4778	if (opts.orc && nr_insns) {
4779	ret = orc_create(file);
4780	if (ret)
4781	goto out;
4782	}
4783
4784	free_insns(file);
4785
4786	if (opts.stats) {
4787	printf("nr_insns_visited: %ld\n", nr_insns_visited);
4788	printf("nr_cfi: %ld\n", nr_cfi);
4789	printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
4790	printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
4791	}
4792
4793	out:
4794	if (!ret && !warnings)
4795	return 0;
4796
4797	if (opts.werror && warnings)
4798	ret = 1;
4799
4800	if (opts.verbose) {
4801	if (opts.werror && warnings)
4802	WARN("%d warning(s) upgraded to errors", warnings);
4803	print_args();
4804	disas_warned_funcs(file);
4805	}
4806
4807	return ret;
4808	}
4809