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1ccea77e | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
dcc914f4 JP |
2 | /* |
3 | * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com> | |
dcc914f4 JP |
4 | */ |
5 | ||
6 | #include <string.h> | |
7 | #include <stdlib.h> | |
8 | ||
43a4525f | 9 | #include "builtin.h" |
dcc914f4 JP |
10 | #include "check.h" |
11 | #include "elf.h" | |
12 | #include "special.h" | |
13 | #include "arch.h" | |
14 | #include "warn.h" | |
15 | ||
16 | #include <linux/hashtable.h> | |
17 | #include <linux/kernel.h> | |
18 | ||
e6da9567 JP |
19 | #define FAKE_JUMP_OFFSET -1 |
20 | ||
dcc914f4 JP |
21 | struct alternative { |
22 | struct list_head list; | |
23 | struct instruction *insn; | |
764eef4b | 24 | bool skip_orig; |
dcc914f4 JP |
25 | }; |
26 | ||
27 | const char *objname; | |
baa41469 | 28 | struct cfi_state initial_func_cfi; |
dcc914f4 | 29 | |
627fce14 JP |
30 | struct instruction *find_insn(struct objtool_file *file, |
31 | struct section *sec, unsigned long offset) | |
dcc914f4 JP |
32 | { |
33 | struct instruction *insn; | |
34 | ||
35 | hash_for_each_possible(file->insn_hash, insn, hash, offset) | |
36 | if (insn->sec == sec && insn->offset == offset) | |
37 | return insn; | |
38 | ||
39 | return NULL; | |
40 | } | |
41 | ||
42 | static struct instruction *next_insn_same_sec(struct objtool_file *file, | |
43 | struct instruction *insn) | |
44 | { | |
45 | struct instruction *next = list_next_entry(insn, list); | |
46 | ||
baa41469 | 47 | if (!next || &next->list == &file->insn_list || next->sec != insn->sec) |
dcc914f4 JP |
48 | return NULL; |
49 | ||
50 | return next; | |
51 | } | |
52 | ||
13810435 JP |
53 | static struct instruction *next_insn_same_func(struct objtool_file *file, |
54 | struct instruction *insn) | |
55 | { | |
56 | struct instruction *next = list_next_entry(insn, list); | |
57 | struct symbol *func = insn->func; | |
58 | ||
59 | if (!func) | |
60 | return NULL; | |
61 | ||
62 | if (&next->list != &file->insn_list && next->func == func) | |
63 | return next; | |
64 | ||
65 | /* Check if we're already in the subfunction: */ | |
66 | if (func == func->cfunc) | |
67 | return NULL; | |
68 | ||
69 | /* Move to the subfunction: */ | |
70 | return find_insn(file, func->cfunc->sec, func->cfunc->offset); | |
71 | } | |
72 | ||
73 | #define func_for_each_insn_all(file, func, insn) \ | |
74 | for (insn = find_insn(file, func->sec, func->offset); \ | |
75 | insn; \ | |
76 | insn = next_insn_same_func(file, insn)) | |
77 | ||
dcc914f4 JP |
78 | #define func_for_each_insn(file, func, insn) \ |
79 | for (insn = find_insn(file, func->sec, func->offset); \ | |
80 | insn && &insn->list != &file->insn_list && \ | |
81 | insn->sec == func->sec && \ | |
82 | insn->offset < func->offset + func->len; \ | |
83 | insn = list_next_entry(insn, list)) | |
84 | ||
85 | #define func_for_each_insn_continue_reverse(file, func, insn) \ | |
86 | for (insn = list_prev_entry(insn, list); \ | |
87 | &insn->list != &file->insn_list && \ | |
88 | insn->sec == func->sec && insn->offset >= func->offset; \ | |
89 | insn = list_prev_entry(insn, list)) | |
90 | ||
91 | #define sec_for_each_insn_from(file, insn) \ | |
92 | for (; insn; insn = next_insn_same_sec(file, insn)) | |
93 | ||
baa41469 JP |
94 | #define sec_for_each_insn_continue(file, insn) \ |
95 | for (insn = next_insn_same_sec(file, insn); insn; \ | |
96 | insn = next_insn_same_sec(file, insn)) | |
dcc914f4 | 97 | |
dcc914f4 JP |
98 | /* |
99 | * This checks to see if the given function is a "noreturn" function. | |
100 | * | |
101 | * For global functions which are outside the scope of this object file, we | |
102 | * have to keep a manual list of them. | |
103 | * | |
104 | * For local functions, we have to detect them manually by simply looking for | |
105 | * the lack of a return instruction. | |
106 | * | |
107 | * Returns: | |
108 | * -1: error | |
109 | * 0: no dead end | |
110 | * 1: dead end | |
111 | */ | |
112 | static int __dead_end_function(struct objtool_file *file, struct symbol *func, | |
113 | int recursion) | |
114 | { | |
115 | int i; | |
116 | struct instruction *insn; | |
117 | bool empty = true; | |
118 | ||
119 | /* | |
120 | * Unfortunately these have to be hard coded because the noreturn | |
121 | * attribute isn't provided in ELF data. | |
122 | */ | |
123 | static const char * const global_noreturns[] = { | |
124 | "__stack_chk_fail", | |
125 | "panic", | |
126 | "do_exit", | |
127 | "do_task_dead", | |
128 | "__module_put_and_exit", | |
129 | "complete_and_exit", | |
130 | "kvm_spurious_fault", | |
131 | "__reiserfs_panic", | |
132 | "lbug_with_loc", | |
133 | "fortify_panic", | |
b394d468 | 134 | "usercopy_abort", |
684fb246 | 135 | "machine_real_restart", |
4fa5ecda | 136 | "rewind_stack_do_exit", |
dcc914f4 JP |
137 | }; |
138 | ||
139 | if (func->bind == STB_WEAK) | |
140 | return 0; | |
141 | ||
142 | if (func->bind == STB_GLOBAL) | |
143 | for (i = 0; i < ARRAY_SIZE(global_noreturns); i++) | |
144 | if (!strcmp(func->name, global_noreturns[i])) | |
145 | return 1; | |
146 | ||
13810435 | 147 | if (!func->len) |
dcc914f4 JP |
148 | return 0; |
149 | ||
13810435 JP |
150 | insn = find_insn(file, func->sec, func->offset); |
151 | if (!insn->func) | |
152 | return 0; | |
153 | ||
154 | func_for_each_insn_all(file, func, insn) { | |
dcc914f4 JP |
155 | empty = false; |
156 | ||
157 | if (insn->type == INSN_RETURN) | |
158 | return 0; | |
159 | } | |
160 | ||
161 | if (empty) | |
162 | return 0; | |
163 | ||
164 | /* | |
165 | * A function can have a sibling call instead of a return. In that | |
166 | * case, the function's dead-end status depends on whether the target | |
167 | * of the sibling call returns. | |
168 | */ | |
13810435 | 169 | func_for_each_insn_all(file, func, insn) { |
dcc914f4 JP |
170 | if (insn->type == INSN_JUMP_UNCONDITIONAL) { |
171 | struct instruction *dest = insn->jump_dest; | |
dcc914f4 JP |
172 | |
173 | if (!dest) | |
174 | /* sibling call to another file */ | |
175 | return 0; | |
176 | ||
13810435 | 177 | if (dest->func && dest->func->pfunc != insn->func->pfunc) { |
dcc914f4 | 178 | |
13810435 | 179 | /* local sibling call */ |
dcc914f4 | 180 | if (recursion == 5) { |
0afd0d9e JP |
181 | /* |
182 | * Infinite recursion: two functions | |
183 | * have sibling calls to each other. | |
184 | * This is a very rare case. It means | |
185 | * they aren't dead ends. | |
186 | */ | |
187 | return 0; | |
dcc914f4 JP |
188 | } |
189 | ||
13810435 | 190 | return __dead_end_function(file, dest->func, |
dcc914f4 JP |
191 | recursion + 1); |
192 | } | |
193 | } | |
194 | ||
195 | if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts)) | |
196 | /* sibling call */ | |
197 | return 0; | |
198 | } | |
199 | ||
200 | return 1; | |
201 | } | |
202 | ||
203 | static int dead_end_function(struct objtool_file *file, struct symbol *func) | |
204 | { | |
205 | return __dead_end_function(file, func, 0); | |
206 | } | |
207 | ||
baa41469 JP |
208 | static void clear_insn_state(struct insn_state *state) |
209 | { | |
210 | int i; | |
211 | ||
212 | memset(state, 0, sizeof(*state)); | |
213 | state->cfa.base = CFI_UNDEFINED; | |
dd88a0a0 | 214 | for (i = 0; i < CFI_NUM_REGS; i++) { |
baa41469 | 215 | state->regs[i].base = CFI_UNDEFINED; |
dd88a0a0 JP |
216 | state->vals[i].base = CFI_UNDEFINED; |
217 | } | |
baa41469 | 218 | state->drap_reg = CFI_UNDEFINED; |
bf4d1a83 | 219 | state->drap_offset = -1; |
baa41469 JP |
220 | } |
221 | ||
dcc914f4 JP |
222 | /* |
223 | * Call the arch-specific instruction decoder for all the instructions and add | |
224 | * them to the global instruction list. | |
225 | */ | |
226 | static int decode_instructions(struct objtool_file *file) | |
227 | { | |
228 | struct section *sec; | |
229 | struct symbol *func; | |
230 | unsigned long offset; | |
231 | struct instruction *insn; | |
232 | int ret; | |
233 | ||
baa41469 | 234 | for_each_sec(file, sec) { |
dcc914f4 JP |
235 | |
236 | if (!(sec->sh.sh_flags & SHF_EXECINSTR)) | |
237 | continue; | |
238 | ||
627fce14 JP |
239 | if (strcmp(sec->name, ".altinstr_replacement") && |
240 | strcmp(sec->name, ".altinstr_aux") && | |
241 | strncmp(sec->name, ".discard.", 9)) | |
242 | sec->text = true; | |
243 | ||
dcc914f4 JP |
244 | for (offset = 0; offset < sec->len; offset += insn->len) { |
245 | insn = malloc(sizeof(*insn)); | |
baa41469 JP |
246 | if (!insn) { |
247 | WARN("malloc failed"); | |
248 | return -1; | |
249 | } | |
dcc914f4 | 250 | memset(insn, 0, sizeof(*insn)); |
dcc914f4 | 251 | INIT_LIST_HEAD(&insn->alts); |
baa41469 JP |
252 | clear_insn_state(&insn->state); |
253 | ||
dcc914f4 JP |
254 | insn->sec = sec; |
255 | insn->offset = offset; | |
256 | ||
257 | ret = arch_decode_instruction(file->elf, sec, offset, | |
258 | sec->len - offset, | |
259 | &insn->len, &insn->type, | |
baa41469 JP |
260 | &insn->immediate, |
261 | &insn->stack_op); | |
dcc914f4 | 262 | if (ret) |
b7037983 | 263 | goto err; |
dcc914f4 JP |
264 | |
265 | if (!insn->type || insn->type > INSN_LAST) { | |
266 | WARN_FUNC("invalid instruction type %d", | |
267 | insn->sec, insn->offset, insn->type); | |
b7037983 KB |
268 | ret = -1; |
269 | goto err; | |
dcc914f4 JP |
270 | } |
271 | ||
272 | hash_add(file->insn_hash, &insn->hash, insn->offset); | |
273 | list_add_tail(&insn->list, &file->insn_list); | |
274 | } | |
275 | ||
276 | list_for_each_entry(func, &sec->symbol_list, list) { | |
277 | if (func->type != STT_FUNC) | |
278 | continue; | |
279 | ||
280 | if (!find_insn(file, sec, func->offset)) { | |
281 | WARN("%s(): can't find starting instruction", | |
282 | func->name); | |
283 | return -1; | |
284 | } | |
285 | ||
286 | func_for_each_insn(file, func, insn) | |
287 | if (!insn->func) | |
288 | insn->func = func; | |
289 | } | |
290 | } | |
291 | ||
292 | return 0; | |
b7037983 KB |
293 | |
294 | err: | |
295 | free(insn); | |
296 | return ret; | |
dcc914f4 JP |
297 | } |
298 | ||
299 | /* | |
649ea4d5 | 300 | * Mark "ud2" instructions and manually annotated dead ends. |
dcc914f4 JP |
301 | */ |
302 | static int add_dead_ends(struct objtool_file *file) | |
303 | { | |
304 | struct section *sec; | |
305 | struct rela *rela; | |
306 | struct instruction *insn; | |
307 | bool found; | |
308 | ||
649ea4d5 JP |
309 | /* |
310 | * By default, "ud2" is a dead end unless otherwise annotated, because | |
311 | * GCC 7 inserts it for certain divide-by-zero cases. | |
312 | */ | |
313 | for_each_insn(file, insn) | |
314 | if (insn->type == INSN_BUG) | |
315 | insn->dead_end = true; | |
316 | ||
317 | /* | |
318 | * Check for manually annotated dead ends. | |
319 | */ | |
dcc914f4 JP |
320 | sec = find_section_by_name(file->elf, ".rela.discard.unreachable"); |
321 | if (!sec) | |
649ea4d5 | 322 | goto reachable; |
dcc914f4 JP |
323 | |
324 | list_for_each_entry(rela, &sec->rela_list, list) { | |
325 | if (rela->sym->type != STT_SECTION) { | |
326 | WARN("unexpected relocation symbol type in %s", sec->name); | |
327 | return -1; | |
328 | } | |
329 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
330 | if (insn) | |
331 | insn = list_prev_entry(insn, list); | |
332 | else if (rela->addend == rela->sym->sec->len) { | |
333 | found = false; | |
334 | list_for_each_entry_reverse(insn, &file->insn_list, list) { | |
335 | if (insn->sec == rela->sym->sec) { | |
336 | found = true; | |
337 | break; | |
338 | } | |
339 | } | |
340 | ||
341 | if (!found) { | |
342 | WARN("can't find unreachable insn at %s+0x%x", | |
343 | rela->sym->sec->name, rela->addend); | |
344 | return -1; | |
345 | } | |
346 | } else { | |
347 | WARN("can't find unreachable insn at %s+0x%x", | |
348 | rela->sym->sec->name, rela->addend); | |
349 | return -1; | |
350 | } | |
351 | ||
352 | insn->dead_end = true; | |
353 | } | |
354 | ||
649ea4d5 JP |
355 | reachable: |
356 | /* | |
357 | * These manually annotated reachable checks are needed for GCC 4.4, | |
358 | * where the Linux unreachable() macro isn't supported. In that case | |
359 | * GCC doesn't know the "ud2" is fatal, so it generates code as if it's | |
360 | * not a dead end. | |
361 | */ | |
362 | sec = find_section_by_name(file->elf, ".rela.discard.reachable"); | |
363 | if (!sec) | |
364 | return 0; | |
365 | ||
366 | list_for_each_entry(rela, &sec->rela_list, list) { | |
367 | if (rela->sym->type != STT_SECTION) { | |
368 | WARN("unexpected relocation symbol type in %s", sec->name); | |
369 | return -1; | |
370 | } | |
371 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
372 | if (insn) | |
373 | insn = list_prev_entry(insn, list); | |
374 | else if (rela->addend == rela->sym->sec->len) { | |
375 | found = false; | |
376 | list_for_each_entry_reverse(insn, &file->insn_list, list) { | |
377 | if (insn->sec == rela->sym->sec) { | |
378 | found = true; | |
379 | break; | |
380 | } | |
381 | } | |
382 | ||
383 | if (!found) { | |
384 | WARN("can't find reachable insn at %s+0x%x", | |
385 | rela->sym->sec->name, rela->addend); | |
386 | return -1; | |
387 | } | |
388 | } else { | |
389 | WARN("can't find reachable insn at %s+0x%x", | |
390 | rela->sym->sec->name, rela->addend); | |
391 | return -1; | |
392 | } | |
393 | ||
394 | insn->dead_end = false; | |
395 | } | |
396 | ||
dcc914f4 JP |
397 | return 0; |
398 | } | |
399 | ||
400 | /* | |
401 | * Warnings shouldn't be reported for ignored functions. | |
402 | */ | |
403 | static void add_ignores(struct objtool_file *file) | |
404 | { | |
405 | struct instruction *insn; | |
406 | struct section *sec; | |
407 | struct symbol *func; | |
aaf5c623 | 408 | struct rela *rela; |
dcc914f4 | 409 | |
aaf5c623 PZ |
410 | sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard"); |
411 | if (!sec) | |
412 | return; | |
dcc914f4 | 413 | |
aaf5c623 PZ |
414 | list_for_each_entry(rela, &sec->rela_list, list) { |
415 | switch (rela->sym->type) { | |
416 | case STT_FUNC: | |
417 | func = rela->sym; | |
418 | break; | |
419 | ||
420 | case STT_SECTION: | |
421 | func = find_symbol_by_offset(rela->sym->sec, rela->addend); | |
422 | if (!func || func->type != STT_FUNC) | |
dcc914f4 | 423 | continue; |
aaf5c623 | 424 | break; |
dcc914f4 | 425 | |
aaf5c623 PZ |
426 | default: |
427 | WARN("unexpected relocation symbol type in %s: %d", sec->name, rela->sym->type); | |
428 | continue; | |
dcc914f4 | 429 | } |
aaf5c623 PZ |
430 | |
431 | func_for_each_insn_all(file, func, insn) | |
432 | insn->ignore = true; | |
dcc914f4 JP |
433 | } |
434 | } | |
435 | ||
ea24213d PZ |
436 | /* |
437 | * This is a whitelist of functions that is allowed to be called with AC set. | |
438 | * The list is meant to be minimal and only contains compiler instrumentation | |
439 | * ABI and a few functions used to implement *_{to,from}_user() functions. | |
440 | * | |
441 | * These functions must not directly change AC, but may PUSHF/POPF. | |
442 | */ | |
443 | static const char *uaccess_safe_builtin[] = { | |
444 | /* KASAN */ | |
445 | "kasan_report", | |
446 | "check_memory_region", | |
447 | /* KASAN out-of-line */ | |
448 | "__asan_loadN_noabort", | |
449 | "__asan_load1_noabort", | |
450 | "__asan_load2_noabort", | |
451 | "__asan_load4_noabort", | |
452 | "__asan_load8_noabort", | |
453 | "__asan_load16_noabort", | |
454 | "__asan_storeN_noabort", | |
455 | "__asan_store1_noabort", | |
456 | "__asan_store2_noabort", | |
457 | "__asan_store4_noabort", | |
458 | "__asan_store8_noabort", | |
459 | "__asan_store16_noabort", | |
460 | /* KASAN in-line */ | |
461 | "__asan_report_load_n_noabort", | |
462 | "__asan_report_load1_noabort", | |
463 | "__asan_report_load2_noabort", | |
464 | "__asan_report_load4_noabort", | |
465 | "__asan_report_load8_noabort", | |
466 | "__asan_report_load16_noabort", | |
467 | "__asan_report_store_n_noabort", | |
468 | "__asan_report_store1_noabort", | |
469 | "__asan_report_store2_noabort", | |
470 | "__asan_report_store4_noabort", | |
471 | "__asan_report_store8_noabort", | |
472 | "__asan_report_store16_noabort", | |
473 | /* KCOV */ | |
474 | "write_comp_data", | |
475 | "__sanitizer_cov_trace_pc", | |
476 | "__sanitizer_cov_trace_const_cmp1", | |
477 | "__sanitizer_cov_trace_const_cmp2", | |
478 | "__sanitizer_cov_trace_const_cmp4", | |
479 | "__sanitizer_cov_trace_const_cmp8", | |
480 | "__sanitizer_cov_trace_cmp1", | |
481 | "__sanitizer_cov_trace_cmp2", | |
482 | "__sanitizer_cov_trace_cmp4", | |
483 | "__sanitizer_cov_trace_cmp8", | |
484 | /* UBSAN */ | |
485 | "ubsan_type_mismatch_common", | |
486 | "__ubsan_handle_type_mismatch", | |
487 | "__ubsan_handle_type_mismatch_v1", | |
488 | /* misc */ | |
489 | "csum_partial_copy_generic", | |
490 | "__memcpy_mcsafe", | |
491 | "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */ | |
492 | NULL | |
493 | }; | |
494 | ||
495 | static void add_uaccess_safe(struct objtool_file *file) | |
496 | { | |
497 | struct symbol *func; | |
498 | const char **name; | |
499 | ||
500 | if (!uaccess) | |
501 | return; | |
502 | ||
503 | for (name = uaccess_safe_builtin; *name; name++) { | |
504 | func = find_symbol_by_name(file->elf, *name); | |
505 | if (!func) | |
506 | continue; | |
507 | ||
508 | func->alias->uaccess_safe = true; | |
dcc914f4 JP |
509 | } |
510 | } | |
511 | ||
258c7605 JP |
512 | /* |
513 | * FIXME: For now, just ignore any alternatives which add retpolines. This is | |
514 | * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline. | |
515 | * But it at least allows objtool to understand the control flow *around* the | |
516 | * retpoline. | |
517 | */ | |
ff05ab23 | 518 | static int add_ignore_alternatives(struct objtool_file *file) |
258c7605 JP |
519 | { |
520 | struct section *sec; | |
521 | struct rela *rela; | |
522 | struct instruction *insn; | |
523 | ||
ff05ab23 | 524 | sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts"); |
258c7605 JP |
525 | if (!sec) |
526 | return 0; | |
527 | ||
528 | list_for_each_entry(rela, &sec->rela_list, list) { | |
529 | if (rela->sym->type != STT_SECTION) { | |
530 | WARN("unexpected relocation symbol type in %s", sec->name); | |
531 | return -1; | |
532 | } | |
533 | ||
534 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
535 | if (!insn) { | |
ff05ab23 | 536 | WARN("bad .discard.ignore_alts entry"); |
258c7605 JP |
537 | return -1; |
538 | } | |
539 | ||
540 | insn->ignore_alts = true; | |
541 | } | |
542 | ||
543 | return 0; | |
544 | } | |
545 | ||
dcc914f4 JP |
546 | /* |
547 | * Find the destination instructions for all jumps. | |
548 | */ | |
549 | static int add_jump_destinations(struct objtool_file *file) | |
550 | { | |
551 | struct instruction *insn; | |
552 | struct rela *rela; | |
553 | struct section *dest_sec; | |
554 | unsigned long dest_off; | |
555 | ||
556 | for_each_insn(file, insn) { | |
557 | if (insn->type != INSN_JUMP_CONDITIONAL && | |
558 | insn->type != INSN_JUMP_UNCONDITIONAL) | |
559 | continue; | |
560 | ||
e6da9567 | 561 | if (insn->ignore || insn->offset == FAKE_JUMP_OFFSET) |
dcc914f4 JP |
562 | continue; |
563 | ||
564 | rela = find_rela_by_dest_range(insn->sec, insn->offset, | |
565 | insn->len); | |
566 | if (!rela) { | |
567 | dest_sec = insn->sec; | |
568 | dest_off = insn->offset + insn->len + insn->immediate; | |
569 | } else if (rela->sym->type == STT_SECTION) { | |
570 | dest_sec = rela->sym->sec; | |
571 | dest_off = rela->addend + 4; | |
572 | } else if (rela->sym->sec->idx) { | |
573 | dest_sec = rela->sym->sec; | |
574 | dest_off = rela->sym->sym.st_value + rela->addend + 4; | |
39b73533 JP |
575 | } else if (strstr(rela->sym->name, "_indirect_thunk_")) { |
576 | /* | |
577 | * Retpoline jumps are really dynamic jumps in | |
578 | * disguise, so convert them accordingly. | |
579 | */ | |
580 | insn->type = INSN_JUMP_DYNAMIC; | |
b5bc2231 | 581 | insn->retpoline_safe = true; |
39b73533 | 582 | continue; |
dcc914f4 JP |
583 | } else { |
584 | /* sibling call */ | |
54262aa2 PZ |
585 | insn->call_dest = rela->sym; |
586 | insn->jump_dest = NULL; | |
dcc914f4 JP |
587 | continue; |
588 | } | |
589 | ||
590 | insn->jump_dest = find_insn(file, dest_sec, dest_off); | |
591 | if (!insn->jump_dest) { | |
592 | ||
593 | /* | |
594 | * This is a special case where an alt instruction | |
595 | * jumps past the end of the section. These are | |
596 | * handled later in handle_group_alt(). | |
597 | */ | |
598 | if (!strcmp(insn->sec->name, ".altinstr_replacement")) | |
599 | continue; | |
600 | ||
601 | WARN_FUNC("can't find jump dest instruction at %s+0x%lx", | |
602 | insn->sec, insn->offset, dest_sec->name, | |
603 | dest_off); | |
604 | return -1; | |
605 | } | |
cd77849a JP |
606 | |
607 | /* | |
54262aa2 | 608 | * Cross-function jump. |
cd77849a JP |
609 | */ |
610 | if (insn->func && insn->jump_dest->func && | |
54262aa2 PZ |
611 | insn->func != insn->jump_dest->func) { |
612 | ||
613 | /* | |
614 | * For GCC 8+, create parent/child links for any cold | |
615 | * subfunctions. This is _mostly_ redundant with a | |
616 | * similar initialization in read_symbols(). | |
617 | * | |
618 | * If a function has aliases, we want the *first* such | |
619 | * function in the symbol table to be the subfunction's | |
620 | * parent. In that case we overwrite the | |
621 | * initialization done in read_symbols(). | |
622 | * | |
623 | * However this code can't completely replace the | |
624 | * read_symbols() code because this doesn't detect the | |
625 | * case where the parent function's only reference to a | |
626 | * subfunction is through a switch table. | |
627 | */ | |
628 | if (!strstr(insn->func->name, ".cold.") && | |
629 | strstr(insn->jump_dest->func->name, ".cold.")) { | |
630 | insn->func->cfunc = insn->jump_dest->func; | |
631 | insn->jump_dest->func->pfunc = insn->func; | |
632 | ||
633 | } else if (insn->jump_dest->func->pfunc != insn->func->pfunc && | |
634 | insn->jump_dest->offset == insn->jump_dest->func->offset) { | |
635 | ||
636 | /* sibling class */ | |
637 | insn->call_dest = insn->jump_dest->func; | |
638 | insn->jump_dest = NULL; | |
639 | } | |
cd77849a | 640 | } |
dcc914f4 JP |
641 | } |
642 | ||
643 | return 0; | |
644 | } | |
645 | ||
646 | /* | |
647 | * Find the destination instructions for all calls. | |
648 | */ | |
649 | static int add_call_destinations(struct objtool_file *file) | |
650 | { | |
651 | struct instruction *insn; | |
652 | unsigned long dest_off; | |
653 | struct rela *rela; | |
654 | ||
655 | for_each_insn(file, insn) { | |
656 | if (insn->type != INSN_CALL) | |
657 | continue; | |
658 | ||
659 | rela = find_rela_by_dest_range(insn->sec, insn->offset, | |
660 | insn->len); | |
661 | if (!rela) { | |
662 | dest_off = insn->offset + insn->len + insn->immediate; | |
663 | insn->call_dest = find_symbol_by_offset(insn->sec, | |
664 | dest_off); | |
a845c7cf JP |
665 | |
666 | if (!insn->call_dest && !insn->ignore) { | |
667 | WARN_FUNC("unsupported intra-function call", | |
668 | insn->sec, insn->offset); | |
b5bc2231 PZ |
669 | if (retpoline) |
670 | WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE."); | |
dcc914f4 JP |
671 | return -1; |
672 | } | |
a845c7cf | 673 | |
dcc914f4 JP |
674 | } else if (rela->sym->type == STT_SECTION) { |
675 | insn->call_dest = find_symbol_by_offset(rela->sym->sec, | |
676 | rela->addend+4); | |
677 | if (!insn->call_dest || | |
678 | insn->call_dest->type != STT_FUNC) { | |
679 | WARN_FUNC("can't find call dest symbol at %s+0x%x", | |
680 | insn->sec, insn->offset, | |
681 | rela->sym->sec->name, | |
682 | rela->addend + 4); | |
683 | return -1; | |
684 | } | |
685 | } else | |
686 | insn->call_dest = rela->sym; | |
687 | } | |
688 | ||
689 | return 0; | |
690 | } | |
691 | ||
692 | /* | |
693 | * The .alternatives section requires some extra special care, over and above | |
694 | * what other special sections require: | |
695 | * | |
696 | * 1. Because alternatives are patched in-place, we need to insert a fake jump | |
697 | * instruction at the end so that validate_branch() skips all the original | |
698 | * replaced instructions when validating the new instruction path. | |
699 | * | |
700 | * 2. An added wrinkle is that the new instruction length might be zero. In | |
701 | * that case the old instructions are replaced with noops. We simulate that | |
702 | * by creating a fake jump as the only new instruction. | |
703 | * | |
704 | * 3. In some cases, the alternative section includes an instruction which | |
705 | * conditionally jumps to the _end_ of the entry. We have to modify these | |
706 | * jumps' destinations to point back to .text rather than the end of the | |
707 | * entry in .altinstr_replacement. | |
dcc914f4 JP |
708 | */ |
709 | static int handle_group_alt(struct objtool_file *file, | |
710 | struct special_alt *special_alt, | |
711 | struct instruction *orig_insn, | |
712 | struct instruction **new_insn) | |
713 | { | |
17bc3391 | 714 | struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL; |
dcc914f4 JP |
715 | unsigned long dest_off; |
716 | ||
717 | last_orig_insn = NULL; | |
718 | insn = orig_insn; | |
719 | sec_for_each_insn_from(file, insn) { | |
720 | if (insn->offset >= special_alt->orig_off + special_alt->orig_len) | |
721 | break; | |
722 | ||
dcc914f4 JP |
723 | insn->alt_group = true; |
724 | last_orig_insn = insn; | |
725 | } | |
726 | ||
17bc3391 JP |
727 | if (next_insn_same_sec(file, last_orig_insn)) { |
728 | fake_jump = malloc(sizeof(*fake_jump)); | |
729 | if (!fake_jump) { | |
730 | WARN("malloc failed"); | |
731 | return -1; | |
732 | } | |
733 | memset(fake_jump, 0, sizeof(*fake_jump)); | |
734 | INIT_LIST_HEAD(&fake_jump->alts); | |
735 | clear_insn_state(&fake_jump->state); | |
736 | ||
737 | fake_jump->sec = special_alt->new_sec; | |
e6da9567 | 738 | fake_jump->offset = FAKE_JUMP_OFFSET; |
17bc3391 JP |
739 | fake_jump->type = INSN_JUMP_UNCONDITIONAL; |
740 | fake_jump->jump_dest = list_next_entry(last_orig_insn, list); | |
e6da9567 | 741 | fake_jump->func = orig_insn->func; |
dcc914f4 | 742 | } |
dcc914f4 JP |
743 | |
744 | if (!special_alt->new_len) { | |
17bc3391 JP |
745 | if (!fake_jump) { |
746 | WARN("%s: empty alternative at end of section", | |
747 | special_alt->orig_sec->name); | |
748 | return -1; | |
749 | } | |
750 | ||
dcc914f4 JP |
751 | *new_insn = fake_jump; |
752 | return 0; | |
753 | } | |
754 | ||
755 | last_new_insn = NULL; | |
756 | insn = *new_insn; | |
757 | sec_for_each_insn_from(file, insn) { | |
758 | if (insn->offset >= special_alt->new_off + special_alt->new_len) | |
759 | break; | |
760 | ||
761 | last_new_insn = insn; | |
762 | ||
a845c7cf | 763 | insn->ignore = orig_insn->ignore_alts; |
a4d09dde | 764 | insn->func = orig_insn->func; |
a845c7cf | 765 | |
dcc914f4 JP |
766 | if (insn->type != INSN_JUMP_CONDITIONAL && |
767 | insn->type != INSN_JUMP_UNCONDITIONAL) | |
768 | continue; | |
769 | ||
770 | if (!insn->immediate) | |
771 | continue; | |
772 | ||
773 | dest_off = insn->offset + insn->len + insn->immediate; | |
17bc3391 JP |
774 | if (dest_off == special_alt->new_off + special_alt->new_len) { |
775 | if (!fake_jump) { | |
776 | WARN("%s: alternative jump to end of section", | |
777 | special_alt->orig_sec->name); | |
778 | return -1; | |
779 | } | |
dcc914f4 | 780 | insn->jump_dest = fake_jump; |
17bc3391 | 781 | } |
dcc914f4 JP |
782 | |
783 | if (!insn->jump_dest) { | |
784 | WARN_FUNC("can't find alternative jump destination", | |
785 | insn->sec, insn->offset); | |
786 | return -1; | |
787 | } | |
788 | } | |
789 | ||
790 | if (!last_new_insn) { | |
791 | WARN_FUNC("can't find last new alternative instruction", | |
792 | special_alt->new_sec, special_alt->new_off); | |
793 | return -1; | |
794 | } | |
795 | ||
17bc3391 JP |
796 | if (fake_jump) |
797 | list_add(&fake_jump->list, &last_new_insn->list); | |
dcc914f4 JP |
798 | |
799 | return 0; | |
800 | } | |
801 | ||
802 | /* | |
803 | * A jump table entry can either convert a nop to a jump or a jump to a nop. | |
804 | * If the original instruction is a jump, make the alt entry an effective nop | |
805 | * by just skipping the original instruction. | |
806 | */ | |
807 | static int handle_jump_alt(struct objtool_file *file, | |
808 | struct special_alt *special_alt, | |
809 | struct instruction *orig_insn, | |
810 | struct instruction **new_insn) | |
811 | { | |
812 | if (orig_insn->type == INSN_NOP) | |
813 | return 0; | |
814 | ||
815 | if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) { | |
816 | WARN_FUNC("unsupported instruction at jump label", | |
817 | orig_insn->sec, orig_insn->offset); | |
818 | return -1; | |
819 | } | |
820 | ||
821 | *new_insn = list_next_entry(orig_insn, list); | |
822 | return 0; | |
823 | } | |
824 | ||
825 | /* | |
826 | * Read all the special sections which have alternate instructions which can be | |
827 | * patched in or redirected to at runtime. Each instruction having alternate | |
828 | * instruction(s) has them added to its insn->alts list, which will be | |
829 | * traversed in validate_branch(). | |
830 | */ | |
831 | static int add_special_section_alts(struct objtool_file *file) | |
832 | { | |
833 | struct list_head special_alts; | |
834 | struct instruction *orig_insn, *new_insn; | |
835 | struct special_alt *special_alt, *tmp; | |
836 | struct alternative *alt; | |
837 | int ret; | |
838 | ||
839 | ret = special_get_alts(file->elf, &special_alts); | |
840 | if (ret) | |
841 | return ret; | |
842 | ||
843 | list_for_each_entry_safe(special_alt, tmp, &special_alts, list) { | |
dcc914f4 JP |
844 | |
845 | orig_insn = find_insn(file, special_alt->orig_sec, | |
846 | special_alt->orig_off); | |
847 | if (!orig_insn) { | |
848 | WARN_FUNC("special: can't find orig instruction", | |
849 | special_alt->orig_sec, special_alt->orig_off); | |
850 | ret = -1; | |
851 | goto out; | |
852 | } | |
853 | ||
854 | new_insn = NULL; | |
855 | if (!special_alt->group || special_alt->new_len) { | |
856 | new_insn = find_insn(file, special_alt->new_sec, | |
857 | special_alt->new_off); | |
858 | if (!new_insn) { | |
859 | WARN_FUNC("special: can't find new instruction", | |
860 | special_alt->new_sec, | |
861 | special_alt->new_off); | |
862 | ret = -1; | |
863 | goto out; | |
864 | } | |
865 | } | |
866 | ||
867 | if (special_alt->group) { | |
868 | ret = handle_group_alt(file, special_alt, orig_insn, | |
869 | &new_insn); | |
870 | if (ret) | |
871 | goto out; | |
872 | } else if (special_alt->jump_or_nop) { | |
873 | ret = handle_jump_alt(file, special_alt, orig_insn, | |
874 | &new_insn); | |
875 | if (ret) | |
876 | goto out; | |
877 | } | |
878 | ||
258c7605 JP |
879 | alt = malloc(sizeof(*alt)); |
880 | if (!alt) { | |
881 | WARN("malloc failed"); | |
882 | ret = -1; | |
883 | goto out; | |
884 | } | |
885 | ||
dcc914f4 | 886 | alt->insn = new_insn; |
764eef4b | 887 | alt->skip_orig = special_alt->skip_orig; |
ea24213d | 888 | orig_insn->ignore_alts |= special_alt->skip_alt; |
dcc914f4 JP |
889 | list_add_tail(&alt->list, &orig_insn->alts); |
890 | ||
891 | list_del(&special_alt->list); | |
892 | free(special_alt); | |
893 | } | |
894 | ||
895 | out: | |
896 | return ret; | |
897 | } | |
898 | ||
13810435 JP |
899 | static int add_switch_table(struct objtool_file *file, struct instruction *insn, |
900 | struct rela *table, struct rela *next_table) | |
dcc914f4 JP |
901 | { |
902 | struct rela *rela = table; | |
903 | struct instruction *alt_insn; | |
904 | struct alternative *alt; | |
fd35c88b JP |
905 | struct symbol *pfunc = insn->func->pfunc; |
906 | unsigned int prev_offset = 0; | |
dcc914f4 | 907 | |
4a60aa05 | 908 | list_for_each_entry_from(rela, &table->rela_sec->rela_list, list) { |
dcc914f4 JP |
909 | if (rela == next_table) |
910 | break; | |
911 | ||
fd35c88b JP |
912 | /* Make sure the switch table entries are consecutive: */ |
913 | if (prev_offset && rela->offset != prev_offset + 8) | |
914 | break; | |
915 | ||
916 | /* Detect function pointers from contiguous objects: */ | |
917 | if (rela->sym->sec == pfunc->sec && | |
918 | rela->addend == pfunc->offset) | |
919 | break; | |
920 | ||
13810435 JP |
921 | alt_insn = find_insn(file, rela->sym->sec, rela->addend); |
922 | if (!alt_insn) | |
dcc914f4 JP |
923 | break; |
924 | ||
13810435 | 925 | /* Make sure the jmp dest is in the function or subfunction: */ |
fd35c88b | 926 | if (alt_insn->func->pfunc != pfunc) |
13810435 | 927 | break; |
dcc914f4 JP |
928 | |
929 | alt = malloc(sizeof(*alt)); | |
930 | if (!alt) { | |
931 | WARN("malloc failed"); | |
932 | return -1; | |
933 | } | |
934 | ||
935 | alt->insn = alt_insn; | |
936 | list_add_tail(&alt->list, &insn->alts); | |
fd35c88b JP |
937 | prev_offset = rela->offset; |
938 | } | |
939 | ||
940 | if (!prev_offset) { | |
941 | WARN_FUNC("can't find switch jump table", | |
942 | insn->sec, insn->offset); | |
943 | return -1; | |
dcc914f4 JP |
944 | } |
945 | ||
946 | return 0; | |
947 | } | |
948 | ||
949 | /* | |
950 | * find_switch_table() - Given a dynamic jump, find the switch jump table in | |
951 | * .rodata associated with it. | |
952 | * | |
953 | * There are 3 basic patterns: | |
954 | * | |
955 | * 1. jmpq *[rodata addr](,%reg,8) | |
956 | * | |
957 | * This is the most common case by far. It jumps to an address in a simple | |
958 | * jump table which is stored in .rodata. | |
959 | * | |
960 | * 2. jmpq *[rodata addr](%rip) | |
961 | * | |
962 | * This is caused by a rare GCC quirk, currently only seen in three driver | |
963 | * functions in the kernel, only with certain obscure non-distro configs. | |
964 | * | |
965 | * As part of an optimization, GCC makes a copy of an existing switch jump | |
966 | * table, modifies it, and then hard-codes the jump (albeit with an indirect | |
967 | * jump) to use a single entry in the table. The rest of the jump table and | |
968 | * some of its jump targets remain as dead code. | |
969 | * | |
970 | * In such a case we can just crudely ignore all unreachable instruction | |
971 | * warnings for the entire object file. Ideally we would just ignore them | |
972 | * for the function, but that would require redesigning the code quite a | |
973 | * bit. And honestly that's just not worth doing: unreachable instruction | |
974 | * warnings are of questionable value anyway, and this is such a rare issue. | |
975 | * | |
976 | * 3. mov [rodata addr],%reg1 | |
977 | * ... some instructions ... | |
978 | * jmpq *(%reg1,%reg2,8) | |
979 | * | |
980 | * This is a fairly uncommon pattern which is new for GCC 6. As of this | |
981 | * writing, there are 11 occurrences of it in the allmodconfig kernel. | |
982 | * | |
99ce7962 PZ |
983 | * As of GCC 7 there are quite a few more of these and the 'in between' code |
984 | * is significant. Esp. with KASAN enabled some of the code between the mov | |
985 | * and jmpq uses .rodata itself, which can confuse things. | |
986 | * | |
dcc914f4 JP |
987 | * TODO: Once we have DWARF CFI and smarter instruction decoding logic, |
988 | * ensure the same register is used in the mov and jump instructions. | |
99ce7962 PZ |
989 | * |
990 | * NOTE: RETPOLINE made it harder still to decode dynamic jumps. | |
dcc914f4 JP |
991 | */ |
992 | static struct rela *find_switch_table(struct objtool_file *file, | |
993 | struct symbol *func, | |
994 | struct instruction *insn) | |
995 | { | |
996 | struct rela *text_rela, *rodata_rela; | |
997 | struct instruction *orig_insn = insn; | |
4a60aa05 | 998 | struct section *rodata_sec; |
6f5ec299 | 999 | unsigned long table_offset; |
dcc914f4 | 1000 | |
99ce7962 PZ |
1001 | /* |
1002 | * Backward search using the @first_jump_src links, these help avoid | |
1003 | * much of the 'in between' code. Which avoids us getting confused by | |
1004 | * it. | |
1005 | */ | |
7dec80cc | 1006 | for (; |
99ce7962 PZ |
1007 | &insn->list != &file->insn_list && |
1008 | insn->sec == func->sec && | |
1009 | insn->offset >= func->offset; | |
1010 | ||
1011 | insn = insn->first_jump_src ?: list_prev_entry(insn, list)) { | |
1012 | ||
7dec80cc | 1013 | if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC) |
dcc914f4 JP |
1014 | break; |
1015 | ||
1016 | /* allow small jumps within the range */ | |
1017 | if (insn->type == INSN_JUMP_UNCONDITIONAL && | |
1018 | insn->jump_dest && | |
1019 | (insn->jump_dest->offset <= insn->offset || | |
1020 | insn->jump_dest->offset > orig_insn->offset)) | |
1021 | break; | |
1022 | ||
1023 | /* look for a relocation which references .rodata */ | |
1024 | text_rela = find_rela_by_dest_range(insn->sec, insn->offset, | |
1025 | insn->len); | |
4a60aa05 AX |
1026 | if (!text_rela || text_rela->sym->type != STT_SECTION || |
1027 | !text_rela->sym->sec->rodata) | |
dcc914f4 JP |
1028 | continue; |
1029 | ||
6f5ec299 | 1030 | table_offset = text_rela->addend; |
4a60aa05 AX |
1031 | rodata_sec = text_rela->sym->sec; |
1032 | ||
6f5ec299 JP |
1033 | if (text_rela->type == R_X86_64_PC32) |
1034 | table_offset += 4; | |
1035 | ||
dcc914f4 JP |
1036 | /* |
1037 | * Make sure the .rodata address isn't associated with a | |
1038 | * symbol. gcc jump tables are anonymous data. | |
1039 | */ | |
4a60aa05 | 1040 | if (find_symbol_containing(rodata_sec, table_offset)) |
1402fd8e JP |
1041 | continue; |
1042 | ||
4a60aa05 | 1043 | rodata_rela = find_rela_by_dest(rodata_sec, table_offset); |
7dec80cc JP |
1044 | if (rodata_rela) { |
1045 | /* | |
1046 | * Use of RIP-relative switch jumps is quite rare, and | |
1047 | * indicates a rare GCC quirk/bug which can leave dead | |
1048 | * code behind. | |
1049 | */ | |
1050 | if (text_rela->type == R_X86_64_PC32) | |
1051 | file->ignore_unreachables = true; | |
1052 | ||
6f5ec299 | 1053 | return rodata_rela; |
7dec80cc | 1054 | } |
dcc914f4 JP |
1055 | } |
1056 | ||
1057 | return NULL; | |
1058 | } | |
1059 | ||
99ce7962 | 1060 | |
dcc914f4 JP |
1061 | static int add_func_switch_tables(struct objtool_file *file, |
1062 | struct symbol *func) | |
1063 | { | |
99ce7962 | 1064 | struct instruction *insn, *last = NULL, *prev_jump = NULL; |
dcc914f4 JP |
1065 | struct rela *rela, *prev_rela = NULL; |
1066 | int ret; | |
1067 | ||
13810435 | 1068 | func_for_each_insn_all(file, func, insn) { |
99ce7962 PZ |
1069 | if (!last) |
1070 | last = insn; | |
1071 | ||
1072 | /* | |
1073 | * Store back-pointers for unconditional forward jumps such | |
1074 | * that find_switch_table() can back-track using those and | |
1075 | * avoid some potentially confusing code. | |
1076 | */ | |
1077 | if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest && | |
1078 | insn->offset > last->offset && | |
1079 | insn->jump_dest->offset > insn->offset && | |
1080 | !insn->jump_dest->first_jump_src) { | |
1081 | ||
1082 | insn->jump_dest->first_jump_src = insn; | |
1083 | last = insn->jump_dest; | |
1084 | } | |
1085 | ||
dcc914f4 JP |
1086 | if (insn->type != INSN_JUMP_DYNAMIC) |
1087 | continue; | |
1088 | ||
1089 | rela = find_switch_table(file, func, insn); | |
1090 | if (!rela) | |
1091 | continue; | |
1092 | ||
1093 | /* | |
1094 | * We found a switch table, but we don't know yet how big it | |
1095 | * is. Don't add it until we reach the end of the function or | |
1096 | * the beginning of another switch table in the same function. | |
1097 | */ | |
1098 | if (prev_jump) { | |
13810435 | 1099 | ret = add_switch_table(file, prev_jump, prev_rela, rela); |
dcc914f4 JP |
1100 | if (ret) |
1101 | return ret; | |
1102 | } | |
1103 | ||
1104 | prev_jump = insn; | |
1105 | prev_rela = rela; | |
1106 | } | |
1107 | ||
1108 | if (prev_jump) { | |
13810435 | 1109 | ret = add_switch_table(file, prev_jump, prev_rela, NULL); |
dcc914f4 JP |
1110 | if (ret) |
1111 | return ret; | |
1112 | } | |
1113 | ||
1114 | return 0; | |
1115 | } | |
1116 | ||
1117 | /* | |
1118 | * For some switch statements, gcc generates a jump table in the .rodata | |
1119 | * section which contains a list of addresses within the function to jump to. | |
1120 | * This finds these jump tables and adds them to the insn->alts lists. | |
1121 | */ | |
1122 | static int add_switch_table_alts(struct objtool_file *file) | |
1123 | { | |
1124 | struct section *sec; | |
1125 | struct symbol *func; | |
1126 | int ret; | |
1127 | ||
4a60aa05 | 1128 | if (!file->rodata) |
dcc914f4 JP |
1129 | return 0; |
1130 | ||
baa41469 | 1131 | for_each_sec(file, sec) { |
dcc914f4 JP |
1132 | list_for_each_entry(func, &sec->symbol_list, list) { |
1133 | if (func->type != STT_FUNC) | |
1134 | continue; | |
1135 | ||
1136 | ret = add_func_switch_tables(file, func); | |
1137 | if (ret) | |
1138 | return ret; | |
1139 | } | |
1140 | } | |
1141 | ||
1142 | return 0; | |
1143 | } | |
1144 | ||
39358a03 JP |
1145 | static int read_unwind_hints(struct objtool_file *file) |
1146 | { | |
1147 | struct section *sec, *relasec; | |
1148 | struct rela *rela; | |
1149 | struct unwind_hint *hint; | |
1150 | struct instruction *insn; | |
1151 | struct cfi_reg *cfa; | |
1152 | int i; | |
1153 | ||
1154 | sec = find_section_by_name(file->elf, ".discard.unwind_hints"); | |
1155 | if (!sec) | |
1156 | return 0; | |
1157 | ||
1158 | relasec = sec->rela; | |
1159 | if (!relasec) { | |
1160 | WARN("missing .rela.discard.unwind_hints section"); | |
1161 | return -1; | |
1162 | } | |
1163 | ||
1164 | if (sec->len % sizeof(struct unwind_hint)) { | |
1165 | WARN("struct unwind_hint size mismatch"); | |
1166 | return -1; | |
1167 | } | |
1168 | ||
1169 | file->hints = true; | |
1170 | ||
1171 | for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) { | |
1172 | hint = (struct unwind_hint *)sec->data->d_buf + i; | |
1173 | ||
1174 | rela = find_rela_by_dest(sec, i * sizeof(*hint)); | |
1175 | if (!rela) { | |
1176 | WARN("can't find rela for unwind_hints[%d]", i); | |
1177 | return -1; | |
1178 | } | |
1179 | ||
1180 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
1181 | if (!insn) { | |
1182 | WARN("can't find insn for unwind_hints[%d]", i); | |
1183 | return -1; | |
1184 | } | |
1185 | ||
1186 | cfa = &insn->state.cfa; | |
1187 | ||
1188 | if (hint->type == UNWIND_HINT_TYPE_SAVE) { | |
1189 | insn->save = true; | |
1190 | continue; | |
1191 | ||
1192 | } else if (hint->type == UNWIND_HINT_TYPE_RESTORE) { | |
1193 | insn->restore = true; | |
1194 | insn->hint = true; | |
1195 | continue; | |
1196 | } | |
1197 | ||
1198 | insn->hint = true; | |
1199 | ||
1200 | switch (hint->sp_reg) { | |
1201 | case ORC_REG_UNDEFINED: | |
1202 | cfa->base = CFI_UNDEFINED; | |
1203 | break; | |
1204 | case ORC_REG_SP: | |
1205 | cfa->base = CFI_SP; | |
1206 | break; | |
1207 | case ORC_REG_BP: | |
1208 | cfa->base = CFI_BP; | |
1209 | break; | |
1210 | case ORC_REG_SP_INDIRECT: | |
1211 | cfa->base = CFI_SP_INDIRECT; | |
1212 | break; | |
1213 | case ORC_REG_R10: | |
1214 | cfa->base = CFI_R10; | |
1215 | break; | |
1216 | case ORC_REG_R13: | |
1217 | cfa->base = CFI_R13; | |
1218 | break; | |
1219 | case ORC_REG_DI: | |
1220 | cfa->base = CFI_DI; | |
1221 | break; | |
1222 | case ORC_REG_DX: | |
1223 | cfa->base = CFI_DX; | |
1224 | break; | |
1225 | default: | |
1226 | WARN_FUNC("unsupported unwind_hint sp base reg %d", | |
1227 | insn->sec, insn->offset, hint->sp_reg); | |
1228 | return -1; | |
1229 | } | |
1230 | ||
1231 | cfa->offset = hint->sp_offset; | |
1232 | insn->state.type = hint->type; | |
d31a5802 | 1233 | insn->state.end = hint->end; |
39358a03 JP |
1234 | } |
1235 | ||
1236 | return 0; | |
1237 | } | |
1238 | ||
b5bc2231 PZ |
1239 | static int read_retpoline_hints(struct objtool_file *file) |
1240 | { | |
63474dc4 | 1241 | struct section *sec; |
b5bc2231 PZ |
1242 | struct instruction *insn; |
1243 | struct rela *rela; | |
b5bc2231 | 1244 | |
63474dc4 | 1245 | sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe"); |
b5bc2231 PZ |
1246 | if (!sec) |
1247 | return 0; | |
1248 | ||
63474dc4 JP |
1249 | list_for_each_entry(rela, &sec->rela_list, list) { |
1250 | if (rela->sym->type != STT_SECTION) { | |
1251 | WARN("unexpected relocation symbol type in %s", sec->name); | |
b5bc2231 PZ |
1252 | return -1; |
1253 | } | |
1254 | ||
1255 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
1256 | if (!insn) { | |
63474dc4 | 1257 | WARN("bad .discard.retpoline_safe entry"); |
b5bc2231 PZ |
1258 | return -1; |
1259 | } | |
1260 | ||
1261 | if (insn->type != INSN_JUMP_DYNAMIC && | |
1262 | insn->type != INSN_CALL_DYNAMIC) { | |
63474dc4 | 1263 | WARN_FUNC("retpoline_safe hint not an indirect jump/call", |
b5bc2231 PZ |
1264 | insn->sec, insn->offset); |
1265 | return -1; | |
1266 | } | |
1267 | ||
1268 | insn->retpoline_safe = true; | |
1269 | } | |
1270 | ||
1271 | return 0; | |
1272 | } | |
1273 | ||
4a60aa05 AX |
1274 | static void mark_rodata(struct objtool_file *file) |
1275 | { | |
1276 | struct section *sec; | |
1277 | bool found = false; | |
1278 | ||
1279 | /* | |
1280 | * This searches for the .rodata section or multiple .rodata.func_name | |
1281 | * sections if -fdata-sections is being used. The .str.1.1 and .str.1.8 | |
1282 | * rodata sections are ignored as they don't contain jump tables. | |
1283 | */ | |
1284 | for_each_sec(file, sec) { | |
1285 | if (!strncmp(sec->name, ".rodata", 7) && | |
1286 | !strstr(sec->name, ".str1.")) { | |
1287 | sec->rodata = true; | |
1288 | found = true; | |
1289 | } | |
1290 | } | |
1291 | ||
1292 | file->rodata = found; | |
1293 | } | |
1294 | ||
dcc914f4 JP |
1295 | static int decode_sections(struct objtool_file *file) |
1296 | { | |
1297 | int ret; | |
1298 | ||
4a60aa05 AX |
1299 | mark_rodata(file); |
1300 | ||
dcc914f4 JP |
1301 | ret = decode_instructions(file); |
1302 | if (ret) | |
1303 | return ret; | |
1304 | ||
1305 | ret = add_dead_ends(file); | |
1306 | if (ret) | |
1307 | return ret; | |
1308 | ||
1309 | add_ignores(file); | |
ea24213d | 1310 | add_uaccess_safe(file); |
dcc914f4 | 1311 | |
ff05ab23 | 1312 | ret = add_ignore_alternatives(file); |
258c7605 JP |
1313 | if (ret) |
1314 | return ret; | |
1315 | ||
dcc914f4 JP |
1316 | ret = add_jump_destinations(file); |
1317 | if (ret) | |
1318 | return ret; | |
1319 | ||
a845c7cf | 1320 | ret = add_special_section_alts(file); |
dcc914f4 JP |
1321 | if (ret) |
1322 | return ret; | |
1323 | ||
a845c7cf | 1324 | ret = add_call_destinations(file); |
dcc914f4 JP |
1325 | if (ret) |
1326 | return ret; | |
1327 | ||
1328 | ret = add_switch_table_alts(file); | |
1329 | if (ret) | |
1330 | return ret; | |
1331 | ||
39358a03 JP |
1332 | ret = read_unwind_hints(file); |
1333 | if (ret) | |
1334 | return ret; | |
1335 | ||
b5bc2231 PZ |
1336 | ret = read_retpoline_hints(file); |
1337 | if (ret) | |
1338 | return ret; | |
1339 | ||
dcc914f4 JP |
1340 | return 0; |
1341 | } | |
1342 | ||
1343 | static bool is_fentry_call(struct instruction *insn) | |
1344 | { | |
1345 | if (insn->type == INSN_CALL && | |
1346 | insn->call_dest->type == STT_NOTYPE && | |
1347 | !strcmp(insn->call_dest->name, "__fentry__")) | |
1348 | return true; | |
1349 | ||
1350 | return false; | |
1351 | } | |
1352 | ||
baa41469 | 1353 | static bool has_modified_stack_frame(struct insn_state *state) |
dcc914f4 | 1354 | { |
baa41469 JP |
1355 | int i; |
1356 | ||
1357 | if (state->cfa.base != initial_func_cfi.cfa.base || | |
1358 | state->cfa.offset != initial_func_cfi.cfa.offset || | |
1359 | state->stack_size != initial_func_cfi.cfa.offset || | |
1360 | state->drap) | |
1361 | return true; | |
1362 | ||
1363 | for (i = 0; i < CFI_NUM_REGS; i++) | |
1364 | if (state->regs[i].base != initial_func_cfi.regs[i].base || | |
1365 | state->regs[i].offset != initial_func_cfi.regs[i].offset) | |
1366 | return true; | |
1367 | ||
1368 | return false; | |
1369 | } | |
1370 | ||
1371 | static bool has_valid_stack_frame(struct insn_state *state) | |
1372 | { | |
1373 | if (state->cfa.base == CFI_BP && state->regs[CFI_BP].base == CFI_CFA && | |
1374 | state->regs[CFI_BP].offset == -16) | |
1375 | return true; | |
1376 | ||
1377 | if (state->drap && state->regs[CFI_BP].base == CFI_BP) | |
1378 | return true; | |
1379 | ||
1380 | return false; | |
dcc914f4 JP |
1381 | } |
1382 | ||
627fce14 JP |
1383 | static int update_insn_state_regs(struct instruction *insn, struct insn_state *state) |
1384 | { | |
1385 | struct cfi_reg *cfa = &state->cfa; | |
1386 | struct stack_op *op = &insn->stack_op; | |
1387 | ||
1388 | if (cfa->base != CFI_SP) | |
1389 | return 0; | |
1390 | ||
1391 | /* push */ | |
ea24213d | 1392 | if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF) |
627fce14 JP |
1393 | cfa->offset += 8; |
1394 | ||
1395 | /* pop */ | |
ea24213d | 1396 | if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF) |
627fce14 JP |
1397 | cfa->offset -= 8; |
1398 | ||
1399 | /* add immediate to sp */ | |
1400 | if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD && | |
1401 | op->dest.reg == CFI_SP && op->src.reg == CFI_SP) | |
1402 | cfa->offset -= op->src.offset; | |
1403 | ||
1404 | return 0; | |
1405 | } | |
1406 | ||
baa41469 JP |
1407 | static void save_reg(struct insn_state *state, unsigned char reg, int base, |
1408 | int offset) | |
dcc914f4 | 1409 | { |
bf4d1a83 | 1410 | if (arch_callee_saved_reg(reg) && |
baa41469 JP |
1411 | state->regs[reg].base == CFI_UNDEFINED) { |
1412 | state->regs[reg].base = base; | |
1413 | state->regs[reg].offset = offset; | |
1414 | } | |
dcc914f4 JP |
1415 | } |
1416 | ||
baa41469 | 1417 | static void restore_reg(struct insn_state *state, unsigned char reg) |
dcc914f4 | 1418 | { |
baa41469 JP |
1419 | state->regs[reg].base = CFI_UNDEFINED; |
1420 | state->regs[reg].offset = 0; | |
1421 | } | |
1422 | ||
1423 | /* | |
1424 | * A note about DRAP stack alignment: | |
1425 | * | |
1426 | * GCC has the concept of a DRAP register, which is used to help keep track of | |
1427 | * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP | |
1428 | * register. The typical DRAP pattern is: | |
1429 | * | |
1430 | * 4c 8d 54 24 08 lea 0x8(%rsp),%r10 | |
1431 | * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp | |
1432 | * 41 ff 72 f8 pushq -0x8(%r10) | |
1433 | * 55 push %rbp | |
1434 | * 48 89 e5 mov %rsp,%rbp | |
1435 | * (more pushes) | |
1436 | * 41 52 push %r10 | |
1437 | * ... | |
1438 | * 41 5a pop %r10 | |
1439 | * (more pops) | |
1440 | * 5d pop %rbp | |
1441 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1442 | * c3 retq | |
1443 | * | |
1444 | * There are some variations in the epilogues, like: | |
1445 | * | |
1446 | * 5b pop %rbx | |
1447 | * 41 5a pop %r10 | |
1448 | * 41 5c pop %r12 | |
1449 | * 41 5d pop %r13 | |
1450 | * 41 5e pop %r14 | |
1451 | * c9 leaveq | |
1452 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1453 | * c3 retq | |
1454 | * | |
1455 | * and: | |
1456 | * | |
1457 | * 4c 8b 55 e8 mov -0x18(%rbp),%r10 | |
1458 | * 48 8b 5d e0 mov -0x20(%rbp),%rbx | |
1459 | * 4c 8b 65 f0 mov -0x10(%rbp),%r12 | |
1460 | * 4c 8b 6d f8 mov -0x8(%rbp),%r13 | |
1461 | * c9 leaveq | |
1462 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1463 | * c3 retq | |
1464 | * | |
1465 | * Sometimes r13 is used as the DRAP register, in which case it's saved and | |
1466 | * restored beforehand: | |
1467 | * | |
1468 | * 41 55 push %r13 | |
1469 | * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13 | |
1470 | * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp | |
1471 | * ... | |
1472 | * 49 8d 65 f0 lea -0x10(%r13),%rsp | |
1473 | * 41 5d pop %r13 | |
1474 | * c3 retq | |
1475 | */ | |
1476 | static int update_insn_state(struct instruction *insn, struct insn_state *state) | |
1477 | { | |
1478 | struct stack_op *op = &insn->stack_op; | |
1479 | struct cfi_reg *cfa = &state->cfa; | |
1480 | struct cfi_reg *regs = state->regs; | |
1481 | ||
1482 | /* stack operations don't make sense with an undefined CFA */ | |
1483 | if (cfa->base == CFI_UNDEFINED) { | |
1484 | if (insn->func) { | |
1485 | WARN_FUNC("undefined stack state", insn->sec, insn->offset); | |
1486 | return -1; | |
1487 | } | |
1488 | return 0; | |
1489 | } | |
1490 | ||
627fce14 JP |
1491 | if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET) |
1492 | return update_insn_state_regs(insn, state); | |
1493 | ||
baa41469 JP |
1494 | switch (op->dest.type) { |
1495 | ||
1496 | case OP_DEST_REG: | |
1497 | switch (op->src.type) { | |
1498 | ||
1499 | case OP_SRC_REG: | |
0d0970ee JP |
1500 | if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP && |
1501 | cfa->base == CFI_SP && | |
1502 | regs[CFI_BP].base == CFI_CFA && | |
1503 | regs[CFI_BP].offset == -cfa->offset) { | |
1504 | ||
1505 | /* mov %rsp, %rbp */ | |
1506 | cfa->base = op->dest.reg; | |
1507 | state->bp_scratch = false; | |
1508 | } | |
dd88a0a0 | 1509 | |
0d0970ee JP |
1510 | else if (op->src.reg == CFI_SP && |
1511 | op->dest.reg == CFI_BP && state->drap) { | |
dd88a0a0 | 1512 | |
0d0970ee JP |
1513 | /* drap: mov %rsp, %rbp */ |
1514 | regs[CFI_BP].base = CFI_BP; | |
1515 | regs[CFI_BP].offset = -state->stack_size; | |
1516 | state->bp_scratch = false; | |
1517 | } | |
dd88a0a0 | 1518 | |
0d0970ee JP |
1519 | else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
1520 | ||
1521 | /* | |
1522 | * mov %rsp, %reg | |
1523 | * | |
1524 | * This is needed for the rare case where GCC | |
1525 | * does: | |
1526 | * | |
1527 | * mov %rsp, %rax | |
1528 | * ... | |
1529 | * mov %rax, %rsp | |
1530 | */ | |
1531 | state->vals[op->dest.reg].base = CFI_CFA; | |
1532 | state->vals[op->dest.reg].offset = -state->stack_size; | |
dd88a0a0 JP |
1533 | } |
1534 | ||
3c1f0583 JP |
1535 | else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP && |
1536 | cfa->base == CFI_BP) { | |
1537 | ||
1538 | /* | |
1539 | * mov %rbp, %rsp | |
1540 | * | |
1541 | * Restore the original stack pointer (Clang). | |
1542 | */ | |
1543 | state->stack_size = -state->regs[CFI_BP].offset; | |
1544 | } | |
1545 | ||
dd88a0a0 JP |
1546 | else if (op->dest.reg == cfa->base) { |
1547 | ||
1548 | /* mov %reg, %rsp */ | |
1549 | if (cfa->base == CFI_SP && | |
1550 | state->vals[op->src.reg].base == CFI_CFA) { | |
1551 | ||
1552 | /* | |
1553 | * This is needed for the rare case | |
1554 | * where GCC does something dumb like: | |
1555 | * | |
1556 | * lea 0x8(%rsp), %rcx | |
1557 | * ... | |
1558 | * mov %rcx, %rsp | |
1559 | */ | |
1560 | cfa->offset = -state->vals[op->src.reg].offset; | |
1561 | state->stack_size = cfa->offset; | |
1562 | ||
1563 | } else { | |
1564 | cfa->base = CFI_UNDEFINED; | |
1565 | cfa->offset = 0; | |
1566 | } | |
baa41469 JP |
1567 | } |
1568 | ||
1569 | break; | |
1570 | ||
1571 | case OP_SRC_ADD: | |
1572 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) { | |
1573 | ||
1574 | /* add imm, %rsp */ | |
1575 | state->stack_size -= op->src.offset; | |
1576 | if (cfa->base == CFI_SP) | |
1577 | cfa->offset -= op->src.offset; | |
1578 | break; | |
1579 | } | |
1580 | ||
1581 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) { | |
1582 | ||
1583 | /* lea disp(%rbp), %rsp */ | |
1584 | state->stack_size = -(op->src.offset + regs[CFI_BP].offset); | |
1585 | break; | |
1586 | } | |
1587 | ||
dd88a0a0 | 1588 | if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
baa41469 JP |
1589 | |
1590 | /* drap: lea disp(%rsp), %drap */ | |
1591 | state->drap_reg = op->dest.reg; | |
dd88a0a0 JP |
1592 | |
1593 | /* | |
1594 | * lea disp(%rsp), %reg | |
1595 | * | |
1596 | * This is needed for the rare case where GCC | |
1597 | * does something dumb like: | |
1598 | * | |
1599 | * lea 0x8(%rsp), %rcx | |
1600 | * ... | |
1601 | * mov %rcx, %rsp | |
1602 | */ | |
1603 | state->vals[op->dest.reg].base = CFI_CFA; | |
1604 | state->vals[op->dest.reg].offset = \ | |
1605 | -state->stack_size + op->src.offset; | |
1606 | ||
baa41469 JP |
1607 | break; |
1608 | } | |
1609 | ||
1610 | if (state->drap && op->dest.reg == CFI_SP && | |
1611 | op->src.reg == state->drap_reg) { | |
1612 | ||
1613 | /* drap: lea disp(%drap), %rsp */ | |
1614 | cfa->base = CFI_SP; | |
1615 | cfa->offset = state->stack_size = -op->src.offset; | |
1616 | state->drap_reg = CFI_UNDEFINED; | |
1617 | state->drap = false; | |
1618 | break; | |
1619 | } | |
1620 | ||
1621 | if (op->dest.reg == state->cfa.base) { | |
1622 | WARN_FUNC("unsupported stack register modification", | |
1623 | insn->sec, insn->offset); | |
1624 | return -1; | |
1625 | } | |
1626 | ||
1627 | break; | |
1628 | ||
1629 | case OP_SRC_AND: | |
1630 | if (op->dest.reg != CFI_SP || | |
1631 | (state->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) || | |
1632 | (state->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) { | |
1633 | WARN_FUNC("unsupported stack pointer realignment", | |
1634 | insn->sec, insn->offset); | |
1635 | return -1; | |
1636 | } | |
1637 | ||
1638 | if (state->drap_reg != CFI_UNDEFINED) { | |
1639 | /* drap: and imm, %rsp */ | |
1640 | cfa->base = state->drap_reg; | |
1641 | cfa->offset = state->stack_size = 0; | |
1642 | state->drap = true; | |
baa41469 JP |
1643 | } |
1644 | ||
1645 | /* | |
1646 | * Older versions of GCC (4.8ish) realign the stack | |
1647 | * without DRAP, with a frame pointer. | |
1648 | */ | |
1649 | ||
1650 | break; | |
1651 | ||
1652 | case OP_SRC_POP: | |
ea24213d | 1653 | case OP_SRC_POPF: |
baa41469 JP |
1654 | if (!state->drap && op->dest.type == OP_DEST_REG && |
1655 | op->dest.reg == cfa->base) { | |
1656 | ||
1657 | /* pop %rbp */ | |
1658 | cfa->base = CFI_SP; | |
1659 | } | |
1660 | ||
bf4d1a83 JP |
1661 | if (state->drap && cfa->base == CFI_BP_INDIRECT && |
1662 | op->dest.type == OP_DEST_REG && | |
1663 | op->dest.reg == state->drap_reg && | |
1664 | state->drap_offset == -state->stack_size) { | |
baa41469 | 1665 | |
bf4d1a83 JP |
1666 | /* drap: pop %drap */ |
1667 | cfa->base = state->drap_reg; | |
1668 | cfa->offset = 0; | |
1669 | state->drap_offset = -1; | |
baa41469 | 1670 | |
bf4d1a83 | 1671 | } else if (regs[op->dest.reg].offset == -state->stack_size) { |
baa41469 | 1672 | |
bf4d1a83 | 1673 | /* pop %reg */ |
baa41469 JP |
1674 | restore_reg(state, op->dest.reg); |
1675 | } | |
1676 | ||
1677 | state->stack_size -= 8; | |
1678 | if (cfa->base == CFI_SP) | |
1679 | cfa->offset -= 8; | |
1680 | ||
1681 | break; | |
1682 | ||
1683 | case OP_SRC_REG_INDIRECT: | |
bf4d1a83 JP |
1684 | if (state->drap && op->src.reg == CFI_BP && |
1685 | op->src.offset == state->drap_offset) { | |
1686 | ||
1687 | /* drap: mov disp(%rbp), %drap */ | |
1688 | cfa->base = state->drap_reg; | |
1689 | cfa->offset = 0; | |
1690 | state->drap_offset = -1; | |
1691 | } | |
1692 | ||
baa41469 JP |
1693 | if (state->drap && op->src.reg == CFI_BP && |
1694 | op->src.offset == regs[op->dest.reg].offset) { | |
1695 | ||
1696 | /* drap: mov disp(%rbp), %reg */ | |
baa41469 JP |
1697 | restore_reg(state, op->dest.reg); |
1698 | ||
1699 | } else if (op->src.reg == cfa->base && | |
1700 | op->src.offset == regs[op->dest.reg].offset + cfa->offset) { | |
1701 | ||
1702 | /* mov disp(%rbp), %reg */ | |
1703 | /* mov disp(%rsp), %reg */ | |
1704 | restore_reg(state, op->dest.reg); | |
1705 | } | |
1706 | ||
1707 | break; | |
1708 | ||
1709 | default: | |
1710 | WARN_FUNC("unknown stack-related instruction", | |
1711 | insn->sec, insn->offset); | |
1712 | return -1; | |
1713 | } | |
1714 | ||
1715 | break; | |
1716 | ||
1717 | case OP_DEST_PUSH: | |
ea24213d | 1718 | case OP_DEST_PUSHF: |
baa41469 JP |
1719 | state->stack_size += 8; |
1720 | if (cfa->base == CFI_SP) | |
1721 | cfa->offset += 8; | |
1722 | ||
1723 | if (op->src.type != OP_SRC_REG) | |
1724 | break; | |
1725 | ||
1726 | if (state->drap) { | |
1727 | if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) { | |
1728 | ||
1729 | /* drap: push %drap */ | |
1730 | cfa->base = CFI_BP_INDIRECT; | |
1731 | cfa->offset = -state->stack_size; | |
1732 | ||
bf4d1a83 JP |
1733 | /* save drap so we know when to restore it */ |
1734 | state->drap_offset = -state->stack_size; | |
baa41469 JP |
1735 | |
1736 | } else if (op->src.reg == CFI_BP && cfa->base == state->drap_reg) { | |
1737 | ||
1738 | /* drap: push %rbp */ | |
1739 | state->stack_size = 0; | |
1740 | ||
1741 | } else if (regs[op->src.reg].base == CFI_UNDEFINED) { | |
1742 | ||
1743 | /* drap: push %reg */ | |
1744 | save_reg(state, op->src.reg, CFI_BP, -state->stack_size); | |
1745 | } | |
1746 | ||
1747 | } else { | |
1748 | ||
1749 | /* push %reg */ | |
1750 | save_reg(state, op->src.reg, CFI_CFA, -state->stack_size); | |
1751 | } | |
1752 | ||
1753 | /* detect when asm code uses rbp as a scratch register */ | |
867ac9d7 | 1754 | if (!no_fp && insn->func && op->src.reg == CFI_BP && |
baa41469 JP |
1755 | cfa->base != CFI_BP) |
1756 | state->bp_scratch = true; | |
1757 | break; | |
1758 | ||
1759 | case OP_DEST_REG_INDIRECT: | |
1760 | ||
1761 | if (state->drap) { | |
1762 | if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) { | |
1763 | ||
1764 | /* drap: mov %drap, disp(%rbp) */ | |
1765 | cfa->base = CFI_BP_INDIRECT; | |
1766 | cfa->offset = op->dest.offset; | |
1767 | ||
bf4d1a83 JP |
1768 | /* save drap offset so we know when to restore it */ |
1769 | state->drap_offset = op->dest.offset; | |
baa41469 JP |
1770 | } |
1771 | ||
1772 | else if (regs[op->src.reg].base == CFI_UNDEFINED) { | |
1773 | ||
1774 | /* drap: mov reg, disp(%rbp) */ | |
1775 | save_reg(state, op->src.reg, CFI_BP, op->dest.offset); | |
1776 | } | |
1777 | ||
1778 | } else if (op->dest.reg == cfa->base) { | |
1779 | ||
1780 | /* mov reg, disp(%rbp) */ | |
1781 | /* mov reg, disp(%rsp) */ | |
1782 | save_reg(state, op->src.reg, CFI_CFA, | |
1783 | op->dest.offset - state->cfa.offset); | |
1784 | } | |
1785 | ||
1786 | break; | |
1787 | ||
1788 | case OP_DEST_LEAVE: | |
1789 | if ((!state->drap && cfa->base != CFI_BP) || | |
1790 | (state->drap && cfa->base != state->drap_reg)) { | |
1791 | WARN_FUNC("leave instruction with modified stack frame", | |
1792 | insn->sec, insn->offset); | |
1793 | return -1; | |
1794 | } | |
1795 | ||
1796 | /* leave (mov %rbp, %rsp; pop %rbp) */ | |
1797 | ||
1798 | state->stack_size = -state->regs[CFI_BP].offset - 8; | |
1799 | restore_reg(state, CFI_BP); | |
1800 | ||
1801 | if (!state->drap) { | |
1802 | cfa->base = CFI_SP; | |
1803 | cfa->offset -= 8; | |
1804 | } | |
1805 | ||
1806 | break; | |
1807 | ||
1808 | case OP_DEST_MEM: | |
ea24213d | 1809 | if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) { |
baa41469 JP |
1810 | WARN_FUNC("unknown stack-related memory operation", |
1811 | insn->sec, insn->offset); | |
1812 | return -1; | |
1813 | } | |
1814 | ||
1815 | /* pop mem */ | |
1816 | state->stack_size -= 8; | |
1817 | if (cfa->base == CFI_SP) | |
1818 | cfa->offset -= 8; | |
1819 | ||
1820 | break; | |
1821 | ||
1822 | default: | |
1823 | WARN_FUNC("unknown stack-related instruction", | |
1824 | insn->sec, insn->offset); | |
1825 | return -1; | |
1826 | } | |
1827 | ||
1828 | return 0; | |
1829 | } | |
1830 | ||
1831 | static bool insn_state_match(struct instruction *insn, struct insn_state *state) | |
1832 | { | |
1833 | struct insn_state *state1 = &insn->state, *state2 = state; | |
1834 | int i; | |
1835 | ||
1836 | if (memcmp(&state1->cfa, &state2->cfa, sizeof(state1->cfa))) { | |
1837 | WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d", | |
1838 | insn->sec, insn->offset, | |
1839 | state1->cfa.base, state1->cfa.offset, | |
1840 | state2->cfa.base, state2->cfa.offset); | |
1841 | ||
1842 | } else if (memcmp(&state1->regs, &state2->regs, sizeof(state1->regs))) { | |
1843 | for (i = 0; i < CFI_NUM_REGS; i++) { | |
1844 | if (!memcmp(&state1->regs[i], &state2->regs[i], | |
1845 | sizeof(struct cfi_reg))) | |
1846 | continue; | |
1847 | ||
1848 | WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d", | |
1849 | insn->sec, insn->offset, | |
1850 | i, state1->regs[i].base, state1->regs[i].offset, | |
1851 | i, state2->regs[i].base, state2->regs[i].offset); | |
1852 | break; | |
1853 | } | |
1854 | ||
627fce14 JP |
1855 | } else if (state1->type != state2->type) { |
1856 | WARN_FUNC("stack state mismatch: type1=%d type2=%d", | |
1857 | insn->sec, insn->offset, state1->type, state2->type); | |
1858 | ||
baa41469 | 1859 | } else if (state1->drap != state2->drap || |
bf4d1a83 JP |
1860 | (state1->drap && state1->drap_reg != state2->drap_reg) || |
1861 | (state1->drap && state1->drap_offset != state2->drap_offset)) { | |
1862 | WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)", | |
baa41469 | 1863 | insn->sec, insn->offset, |
bf4d1a83 JP |
1864 | state1->drap, state1->drap_reg, state1->drap_offset, |
1865 | state2->drap, state2->drap_reg, state2->drap_offset); | |
baa41469 JP |
1866 | |
1867 | } else | |
1868 | return true; | |
1869 | ||
1870 | return false; | |
dcc914f4 JP |
1871 | } |
1872 | ||
ea24213d PZ |
1873 | static inline bool func_uaccess_safe(struct symbol *func) |
1874 | { | |
1875 | if (func) | |
1876 | return func->alias->uaccess_safe; | |
1877 | ||
1878 | return false; | |
1879 | } | |
1880 | ||
1881 | static inline const char *insn_dest_name(struct instruction *insn) | |
1882 | { | |
1883 | if (insn->call_dest) | |
1884 | return insn->call_dest->name; | |
1885 | ||
1886 | return "{dynamic}"; | |
1887 | } | |
1888 | ||
1889 | static int validate_call(struct instruction *insn, struct insn_state *state) | |
1890 | { | |
1891 | if (state->uaccess && !func_uaccess_safe(insn->call_dest)) { | |
1892 | WARN_FUNC("call to %s() with UACCESS enabled", | |
1893 | insn->sec, insn->offset, insn_dest_name(insn)); | |
1894 | return 1; | |
1895 | } | |
1896 | ||
2f0f9e9a PZ |
1897 | if (state->df) { |
1898 | WARN_FUNC("call to %s() with DF set", | |
1899 | insn->sec, insn->offset, insn_dest_name(insn)); | |
1900 | return 1; | |
1901 | } | |
1902 | ||
ea24213d PZ |
1903 | return 0; |
1904 | } | |
1905 | ||
54262aa2 PZ |
1906 | static int validate_sibling_call(struct instruction *insn, struct insn_state *state) |
1907 | { | |
1908 | if (has_modified_stack_frame(state)) { | |
1909 | WARN_FUNC("sibling call from callable instruction with modified stack frame", | |
1910 | insn->sec, insn->offset); | |
1911 | return 1; | |
1912 | } | |
1913 | ||
ea24213d | 1914 | return validate_call(insn, state); |
54262aa2 PZ |
1915 | } |
1916 | ||
dcc914f4 JP |
1917 | /* |
1918 | * Follow the branch starting at the given instruction, and recursively follow | |
1919 | * any other branches (jumps). Meanwhile, track the frame pointer state at | |
1920 | * each instruction and validate all the rules described in | |
1921 | * tools/objtool/Documentation/stack-validation.txt. | |
1922 | */ | |
baa41469 JP |
1923 | static int validate_branch(struct objtool_file *file, struct instruction *first, |
1924 | struct insn_state state) | |
dcc914f4 JP |
1925 | { |
1926 | struct alternative *alt; | |
39358a03 | 1927 | struct instruction *insn, *next_insn; |
dcc914f4 JP |
1928 | struct section *sec; |
1929 | struct symbol *func = NULL; | |
dcc914f4 JP |
1930 | int ret; |
1931 | ||
1932 | insn = first; | |
1933 | sec = insn->sec; | |
dcc914f4 JP |
1934 | |
1935 | if (insn->alt_group && list_empty(&insn->alts)) { | |
1936 | WARN_FUNC("don't know how to handle branch to middle of alternative instruction group", | |
1937 | sec, insn->offset); | |
12b25729 | 1938 | return 1; |
dcc914f4 JP |
1939 | } |
1940 | ||
1941 | while (1) { | |
39358a03 JP |
1942 | next_insn = next_insn_same_sec(file, insn); |
1943 | ||
13810435 | 1944 | if (file->c_file && func && insn->func && func != insn->func->pfunc) { |
ee97638b JP |
1945 | WARN("%s() falls through to next function %s()", |
1946 | func->name, insn->func->name); | |
1947 | return 1; | |
dcc914f4 JP |
1948 | } |
1949 | ||
e6f393bc JP |
1950 | if (insn->func) |
1951 | func = insn->func->pfunc; | |
baa41469 | 1952 | |
4855022a JP |
1953 | if (func && insn->ignore) { |
1954 | WARN_FUNC("BUG: why am I validating an ignored function?", | |
1955 | sec, insn->offset); | |
12b25729 | 1956 | return 1; |
4855022a JP |
1957 | } |
1958 | ||
dcc914f4 | 1959 | if (insn->visited) { |
39358a03 | 1960 | if (!insn->hint && !insn_state_match(insn, &state)) |
dcc914f4 | 1961 | return 1; |
dcc914f4 | 1962 | |
ea24213d PZ |
1963 | /* If we were here with AC=0, but now have AC=1, go again */ |
1964 | if (insn->state.uaccess || !state.uaccess) | |
1965 | return 0; | |
dcc914f4 JP |
1966 | } |
1967 | ||
39358a03 JP |
1968 | if (insn->hint) { |
1969 | if (insn->restore) { | |
1970 | struct instruction *save_insn, *i; | |
1971 | ||
1972 | i = insn; | |
1973 | save_insn = NULL; | |
13810435 | 1974 | func_for_each_insn_continue_reverse(file, insn->func, i) { |
39358a03 JP |
1975 | if (i->save) { |
1976 | save_insn = i; | |
1977 | break; | |
1978 | } | |
1979 | } | |
1980 | ||
1981 | if (!save_insn) { | |
1982 | WARN_FUNC("no corresponding CFI save for CFI restore", | |
1983 | sec, insn->offset); | |
1984 | return 1; | |
1985 | } | |
1986 | ||
1987 | if (!save_insn->visited) { | |
1988 | /* | |
1989 | * Oops, no state to copy yet. | |
1990 | * Hopefully we can reach this | |
1991 | * instruction from another branch | |
1992 | * after the save insn has been | |
1993 | * visited. | |
1994 | */ | |
1995 | if (insn == first) | |
1996 | return 0; | |
1997 | ||
1998 | WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo", | |
1999 | sec, insn->offset); | |
2000 | return 1; | |
2001 | } | |
2002 | ||
2003 | insn->state = save_insn->state; | |
2004 | } | |
2005 | ||
2006 | state = insn->state; | |
2007 | ||
2008 | } else | |
2009 | insn->state = state; | |
dcc914f4 | 2010 | |
baa41469 JP |
2011 | insn->visited = true; |
2012 | ||
a845c7cf | 2013 | if (!insn->ignore_alts) { |
764eef4b PZ |
2014 | bool skip_orig = false; |
2015 | ||
a845c7cf | 2016 | list_for_each_entry(alt, &insn->alts, list) { |
764eef4b PZ |
2017 | if (alt->skip_orig) |
2018 | skip_orig = true; | |
2019 | ||
a845c7cf | 2020 | ret = validate_branch(file, alt->insn, state); |
7697eee3 PZ |
2021 | if (ret) { |
2022 | if (backtrace) | |
2023 | BT_FUNC("(alt)", insn); | |
2024 | return ret; | |
2025 | } | |
a845c7cf | 2026 | } |
764eef4b PZ |
2027 | |
2028 | if (skip_orig) | |
2029 | return 0; | |
dcc914f4 JP |
2030 | } |
2031 | ||
2032 | switch (insn->type) { | |
2033 | ||
dcc914f4 | 2034 | case INSN_RETURN: |
ea24213d PZ |
2035 | if (state.uaccess && !func_uaccess_safe(func)) { |
2036 | WARN_FUNC("return with UACCESS enabled", sec, insn->offset); | |
2037 | return 1; | |
2038 | } | |
2039 | ||
2040 | if (!state.uaccess && func_uaccess_safe(func)) { | |
2041 | WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function", sec, insn->offset); | |
2042 | return 1; | |
2043 | } | |
2044 | ||
2f0f9e9a PZ |
2045 | if (state.df) { |
2046 | WARN_FUNC("return with DF set", sec, insn->offset); | |
2047 | return 1; | |
2048 | } | |
2049 | ||
baa41469 JP |
2050 | if (func && has_modified_stack_frame(&state)) { |
2051 | WARN_FUNC("return with modified stack frame", | |
dcc914f4 JP |
2052 | sec, insn->offset); |
2053 | return 1; | |
2054 | } | |
baa41469 JP |
2055 | |
2056 | if (state.bp_scratch) { | |
2057 | WARN("%s uses BP as a scratch register", | |
2058 | insn->func->name); | |
2059 | return 1; | |
2060 | } | |
2061 | ||
dcc914f4 JP |
2062 | return 0; |
2063 | ||
2064 | case INSN_CALL: | |
ea24213d PZ |
2065 | case INSN_CALL_DYNAMIC: |
2066 | ret = validate_call(insn, &state); | |
2067 | if (ret) | |
2068 | return ret; | |
dcc914f4 | 2069 | |
ea24213d PZ |
2070 | if (insn->type == INSN_CALL) { |
2071 | if (is_fentry_call(insn)) | |
2072 | break; | |
2073 | ||
2074 | ret = dead_end_function(file, insn->call_dest); | |
2075 | if (ret == 1) | |
2076 | return 0; | |
2077 | if (ret == -1) | |
2078 | return 1; | |
2079 | } | |
dcc914f4 | 2080 | |
867ac9d7 | 2081 | if (!no_fp && func && !has_valid_stack_frame(&state)) { |
dcc914f4 JP |
2082 | WARN_FUNC("call without frame pointer save/setup", |
2083 | sec, insn->offset); | |
2084 | return 1; | |
2085 | } | |
2086 | break; | |
2087 | ||
2088 | case INSN_JUMP_CONDITIONAL: | |
2089 | case INSN_JUMP_UNCONDITIONAL: | |
54262aa2 PZ |
2090 | if (func && !insn->jump_dest) { |
2091 | ret = validate_sibling_call(insn, &state); | |
dcc914f4 | 2092 | if (ret) |
54262aa2 | 2093 | return ret; |
4855022a | 2094 | |
54262aa2 PZ |
2095 | } else if (insn->jump_dest && |
2096 | (!func || !insn->jump_dest->func || | |
2097 | insn->jump_dest->func->pfunc == func)) { | |
dcc914f4 JP |
2098 | ret = validate_branch(file, insn->jump_dest, |
2099 | state); | |
7697eee3 PZ |
2100 | if (ret) { |
2101 | if (backtrace) | |
2102 | BT_FUNC("(branch)", insn); | |
2103 | return ret; | |
2104 | } | |
4855022a | 2105 | } |
dcc914f4 JP |
2106 | |
2107 | if (insn->type == INSN_JUMP_UNCONDITIONAL) | |
2108 | return 0; | |
2109 | ||
2110 | break; | |
2111 | ||
2112 | case INSN_JUMP_DYNAMIC: | |
54262aa2 PZ |
2113 | if (func && list_empty(&insn->alts)) { |
2114 | ret = validate_sibling_call(insn, &state); | |
2115 | if (ret) | |
2116 | return ret; | |
dcc914f4 JP |
2117 | } |
2118 | ||
2119 | return 0; | |
2120 | ||
39358a03 JP |
2121 | case INSN_CONTEXT_SWITCH: |
2122 | if (func && (!next_insn || !next_insn->hint)) { | |
2123 | WARN_FUNC("unsupported instruction in callable function", | |
2124 | sec, insn->offset); | |
2125 | return 1; | |
2126 | } | |
2127 | return 0; | |
2128 | ||
baa41469 JP |
2129 | case INSN_STACK: |
2130 | if (update_insn_state(insn, &state)) | |
12b25729 | 2131 | return 1; |
baa41469 | 2132 | |
ea24213d PZ |
2133 | if (insn->stack_op.dest.type == OP_DEST_PUSHF) { |
2134 | if (!state.uaccess_stack) { | |
2135 | state.uaccess_stack = 1; | |
2136 | } else if (state.uaccess_stack >> 31) { | |
2137 | WARN_FUNC("PUSHF stack exhausted", sec, insn->offset); | |
2138 | return 1; | |
2139 | } | |
2140 | state.uaccess_stack <<= 1; | |
2141 | state.uaccess_stack |= state.uaccess; | |
2142 | } | |
2143 | ||
2144 | if (insn->stack_op.src.type == OP_SRC_POPF) { | |
2145 | if (state.uaccess_stack) { | |
2146 | state.uaccess = state.uaccess_stack & 1; | |
2147 | state.uaccess_stack >>= 1; | |
2148 | if (state.uaccess_stack == 1) | |
2149 | state.uaccess_stack = 0; | |
2150 | } | |
2151 | } | |
2152 | ||
2153 | break; | |
2154 | ||
2155 | case INSN_STAC: | |
2156 | if (state.uaccess) { | |
2157 | WARN_FUNC("recursive UACCESS enable", sec, insn->offset); | |
2158 | return 1; | |
2159 | } | |
2160 | ||
2161 | state.uaccess = true; | |
2162 | break; | |
2163 | ||
2164 | case INSN_CLAC: | |
2165 | if (!state.uaccess && insn->func) { | |
2166 | WARN_FUNC("redundant UACCESS disable", sec, insn->offset); | |
2167 | return 1; | |
2168 | } | |
2169 | ||
2170 | if (func_uaccess_safe(func) && !state.uaccess_stack) { | |
2171 | WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset); | |
2172 | return 1; | |
2173 | } | |
2174 | ||
2175 | state.uaccess = false; | |
baa41469 JP |
2176 | break; |
2177 | ||
2f0f9e9a PZ |
2178 | case INSN_STD: |
2179 | if (state.df) | |
2180 | WARN_FUNC("recursive STD", sec, insn->offset); | |
2181 | ||
2182 | state.df = true; | |
2183 | break; | |
2184 | ||
2185 | case INSN_CLD: | |
2186 | if (!state.df && insn->func) | |
2187 | WARN_FUNC("redundant CLD", sec, insn->offset); | |
2188 | ||
2189 | state.df = false; | |
baa41469 JP |
2190 | break; |
2191 | ||
dcc914f4 JP |
2192 | default: |
2193 | break; | |
2194 | } | |
2195 | ||
2196 | if (insn->dead_end) | |
2197 | return 0; | |
2198 | ||
00d96180 JP |
2199 | if (!next_insn) { |
2200 | if (state.cfa.base == CFI_UNDEFINED) | |
2201 | return 0; | |
dcc914f4 JP |
2202 | WARN("%s: unexpected end of section", sec->name); |
2203 | return 1; | |
2204 | } | |
00d96180 JP |
2205 | |
2206 | insn = next_insn; | |
dcc914f4 JP |
2207 | } |
2208 | ||
2209 | return 0; | |
2210 | } | |
2211 | ||
39358a03 JP |
2212 | static int validate_unwind_hints(struct objtool_file *file) |
2213 | { | |
2214 | struct instruction *insn; | |
2215 | int ret, warnings = 0; | |
2216 | struct insn_state state; | |
2217 | ||
2218 | if (!file->hints) | |
2219 | return 0; | |
2220 | ||
2221 | clear_insn_state(&state); | |
2222 | ||
2223 | for_each_insn(file, insn) { | |
2224 | if (insn->hint && !insn->visited) { | |
2225 | ret = validate_branch(file, insn, state); | |
7697eee3 PZ |
2226 | if (ret && backtrace) |
2227 | BT_FUNC("<=== (hint)", insn); | |
39358a03 JP |
2228 | warnings += ret; |
2229 | } | |
2230 | } | |
2231 | ||
2232 | return warnings; | |
2233 | } | |
2234 | ||
b5bc2231 PZ |
2235 | static int validate_retpoline(struct objtool_file *file) |
2236 | { | |
2237 | struct instruction *insn; | |
2238 | int warnings = 0; | |
2239 | ||
2240 | for_each_insn(file, insn) { | |
2241 | if (insn->type != INSN_JUMP_DYNAMIC && | |
2242 | insn->type != INSN_CALL_DYNAMIC) | |
2243 | continue; | |
2244 | ||
2245 | if (insn->retpoline_safe) | |
2246 | continue; | |
2247 | ||
ca41b97e PZ |
2248 | /* |
2249 | * .init.text code is ran before userspace and thus doesn't | |
2250 | * strictly need retpolines, except for modules which are | |
2251 | * loaded late, they very much do need retpoline in their | |
2252 | * .init.text | |
2253 | */ | |
2254 | if (!strcmp(insn->sec->name, ".init.text") && !module) | |
2255 | continue; | |
2256 | ||
b5bc2231 PZ |
2257 | WARN_FUNC("indirect %s found in RETPOLINE build", |
2258 | insn->sec, insn->offset, | |
2259 | insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); | |
2260 | ||
2261 | warnings++; | |
2262 | } | |
2263 | ||
2264 | return warnings; | |
2265 | } | |
2266 | ||
dcc914f4 JP |
2267 | static bool is_kasan_insn(struct instruction *insn) |
2268 | { | |
2269 | return (insn->type == INSN_CALL && | |
2270 | !strcmp(insn->call_dest->name, "__asan_handle_no_return")); | |
2271 | } | |
2272 | ||
2273 | static bool is_ubsan_insn(struct instruction *insn) | |
2274 | { | |
2275 | return (insn->type == INSN_CALL && | |
2276 | !strcmp(insn->call_dest->name, | |
2277 | "__ubsan_handle_builtin_unreachable")); | |
2278 | } | |
2279 | ||
baa41469 | 2280 | static bool ignore_unreachable_insn(struct instruction *insn) |
dcc914f4 JP |
2281 | { |
2282 | int i; | |
2283 | ||
baa41469 JP |
2284 | if (insn->ignore || insn->type == INSN_NOP) |
2285 | return true; | |
2286 | ||
2287 | /* | |
2288 | * Ignore any unused exceptions. This can happen when a whitelisted | |
2289 | * function has an exception table entry. | |
0e2bb2bc JP |
2290 | * |
2291 | * Also ignore alternative replacement instructions. This can happen | |
2292 | * when a whitelisted function uses one of the ALTERNATIVE macros. | |
baa41469 | 2293 | */ |
0e2bb2bc JP |
2294 | if (!strcmp(insn->sec->name, ".fixup") || |
2295 | !strcmp(insn->sec->name, ".altinstr_replacement") || | |
2296 | !strcmp(insn->sec->name, ".altinstr_aux")) | |
dcc914f4 JP |
2297 | return true; |
2298 | ||
2299 | /* | |
2300 | * Check if this (or a subsequent) instruction is related to | |
2301 | * CONFIG_UBSAN or CONFIG_KASAN. | |
2302 | * | |
2303 | * End the search at 5 instructions to avoid going into the weeds. | |
2304 | */ | |
baa41469 JP |
2305 | if (!insn->func) |
2306 | return false; | |
dcc914f4 JP |
2307 | for (i = 0; i < 5; i++) { |
2308 | ||
2309 | if (is_kasan_insn(insn) || is_ubsan_insn(insn)) | |
2310 | return true; | |
2311 | ||
fe24e271 JP |
2312 | if (insn->type == INSN_JUMP_UNCONDITIONAL) { |
2313 | if (insn->jump_dest && | |
2314 | insn->jump_dest->func == insn->func) { | |
2315 | insn = insn->jump_dest; | |
2316 | continue; | |
2317 | } | |
2318 | ||
2319 | break; | |
dcc914f4 JP |
2320 | } |
2321 | ||
baa41469 | 2322 | if (insn->offset + insn->len >= insn->func->offset + insn->func->len) |
dcc914f4 | 2323 | break; |
fe24e271 | 2324 | |
dcc914f4 JP |
2325 | insn = list_next_entry(insn, list); |
2326 | } | |
2327 | ||
2328 | return false; | |
2329 | } | |
2330 | ||
2331 | static int validate_functions(struct objtool_file *file) | |
2332 | { | |
2333 | struct section *sec; | |
2334 | struct symbol *func; | |
2335 | struct instruction *insn; | |
baa41469 | 2336 | struct insn_state state; |
dcc914f4 JP |
2337 | int ret, warnings = 0; |
2338 | ||
baa41469 JP |
2339 | clear_insn_state(&state); |
2340 | ||
2341 | state.cfa = initial_func_cfi.cfa; | |
2342 | memcpy(&state.regs, &initial_func_cfi.regs, | |
2343 | CFI_NUM_REGS * sizeof(struct cfi_reg)); | |
2344 | state.stack_size = initial_func_cfi.cfa.offset; | |
2345 | ||
2346 | for_each_sec(file, sec) { | |
dcc914f4 | 2347 | list_for_each_entry(func, &sec->symbol_list, list) { |
13810435 | 2348 | if (func->type != STT_FUNC || func->pfunc != func) |
dcc914f4 JP |
2349 | continue; |
2350 | ||
2351 | insn = find_insn(file, sec, func->offset); | |
baa41469 | 2352 | if (!insn || insn->ignore) |
dcc914f4 JP |
2353 | continue; |
2354 | ||
ea24213d PZ |
2355 | state.uaccess = func->alias->uaccess_safe; |
2356 | ||
baa41469 | 2357 | ret = validate_branch(file, insn, state); |
7697eee3 PZ |
2358 | if (ret && backtrace) |
2359 | BT_FUNC("<=== (func)", insn); | |
dcc914f4 JP |
2360 | warnings += ret; |
2361 | } | |
2362 | } | |
2363 | ||
dcc914f4 JP |
2364 | return warnings; |
2365 | } | |
2366 | ||
baa41469 | 2367 | static int validate_reachable_instructions(struct objtool_file *file) |
dcc914f4 JP |
2368 | { |
2369 | struct instruction *insn; | |
baa41469 JP |
2370 | |
2371 | if (file->ignore_unreachables) | |
2372 | return 0; | |
dcc914f4 JP |
2373 | |
2374 | for_each_insn(file, insn) { | |
baa41469 JP |
2375 | if (insn->visited || ignore_unreachable_insn(insn)) |
2376 | continue; | |
2377 | ||
baa41469 JP |
2378 | WARN_FUNC("unreachable instruction", insn->sec, insn->offset); |
2379 | return 1; | |
dcc914f4 JP |
2380 | } |
2381 | ||
baa41469 | 2382 | return 0; |
dcc914f4 JP |
2383 | } |
2384 | ||
2385 | static void cleanup(struct objtool_file *file) | |
2386 | { | |
2387 | struct instruction *insn, *tmpinsn; | |
2388 | struct alternative *alt, *tmpalt; | |
2389 | ||
2390 | list_for_each_entry_safe(insn, tmpinsn, &file->insn_list, list) { | |
2391 | list_for_each_entry_safe(alt, tmpalt, &insn->alts, list) { | |
2392 | list_del(&alt->list); | |
2393 | free(alt); | |
2394 | } | |
2395 | list_del(&insn->list); | |
2396 | hash_del(&insn->hash); | |
2397 | free(insn); | |
2398 | } | |
2399 | elf_close(file->elf); | |
2400 | } | |
2401 | ||
0c671812 JP |
2402 | static struct objtool_file file; |
2403 | ||
43a4525f | 2404 | int check(const char *_objname, bool orc) |
dcc914f4 | 2405 | { |
dcc914f4 JP |
2406 | int ret, warnings = 0; |
2407 | ||
2408 | objname = _objname; | |
dcc914f4 | 2409 | |
627fce14 | 2410 | file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY); |
baa41469 | 2411 | if (!file.elf) |
dcc914f4 | 2412 | return 1; |
dcc914f4 JP |
2413 | |
2414 | INIT_LIST_HEAD(&file.insn_list); | |
2415 | hash_init(file.insn_hash); | |
dcc914f4 | 2416 | file.c_file = find_section_by_name(file.elf, ".comment"); |
867ac9d7 | 2417 | file.ignore_unreachables = no_unreachable; |
39358a03 | 2418 | file.hints = false; |
dcc914f4 | 2419 | |
baa41469 JP |
2420 | arch_initial_func_cfi_state(&initial_func_cfi); |
2421 | ||
dcc914f4 JP |
2422 | ret = decode_sections(&file); |
2423 | if (ret < 0) | |
2424 | goto out; | |
2425 | warnings += ret; | |
2426 | ||
baa41469 | 2427 | if (list_empty(&file.insn_list)) |
dcc914f4 | 2428 | goto out; |
dcc914f4 | 2429 | |
b5bc2231 PZ |
2430 | if (retpoline) { |
2431 | ret = validate_retpoline(&file); | |
2432 | if (ret < 0) | |
2433 | return ret; | |
2434 | warnings += ret; | |
2435 | } | |
2436 | ||
baa41469 | 2437 | ret = validate_functions(&file); |
dcc914f4 JP |
2438 | if (ret < 0) |
2439 | goto out; | |
2440 | warnings += ret; | |
2441 | ||
39358a03 JP |
2442 | ret = validate_unwind_hints(&file); |
2443 | if (ret < 0) | |
2444 | goto out; | |
2445 | warnings += ret; | |
2446 | ||
baa41469 JP |
2447 | if (!warnings) { |
2448 | ret = validate_reachable_instructions(&file); | |
2449 | if (ret < 0) | |
2450 | goto out; | |
2451 | warnings += ret; | |
2452 | } | |
2453 | ||
627fce14 JP |
2454 | if (orc) { |
2455 | ret = create_orc(&file); | |
2456 | if (ret < 0) | |
2457 | goto out; | |
2458 | ||
2459 | ret = create_orc_sections(&file); | |
2460 | if (ret < 0) | |
2461 | goto out; | |
2462 | ||
2463 | ret = elf_write(file.elf); | |
2464 | if (ret < 0) | |
2465 | goto out; | |
2466 | } | |
2467 | ||
dcc914f4 JP |
2468 | out: |
2469 | cleanup(&file); | |
2470 | ||
2471 | /* ignore warnings for now until we get all the code cleaned up */ | |
2472 | if (ret || warnings) | |
2473 | return 0; | |
2474 | return 0; | |
2475 | } |