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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 | ||
87b512de JP |
21 | #define C_JUMP_TABLE_SECTION ".rodata..c_jump_table" |
22 | ||
dcc914f4 JP |
23 | struct alternative { |
24 | struct list_head list; | |
25 | struct instruction *insn; | |
764eef4b | 26 | bool skip_orig; |
dcc914f4 JP |
27 | }; |
28 | ||
29 | const char *objname; | |
baa41469 | 30 | struct cfi_state initial_func_cfi; |
dcc914f4 | 31 | |
627fce14 JP |
32 | struct instruction *find_insn(struct objtool_file *file, |
33 | struct section *sec, unsigned long offset) | |
dcc914f4 JP |
34 | { |
35 | struct instruction *insn; | |
36 | ||
37 | hash_for_each_possible(file->insn_hash, insn, hash, offset) | |
38 | if (insn->sec == sec && insn->offset == offset) | |
39 | return insn; | |
40 | ||
41 | return NULL; | |
42 | } | |
43 | ||
44 | static struct instruction *next_insn_same_sec(struct objtool_file *file, | |
45 | struct instruction *insn) | |
46 | { | |
47 | struct instruction *next = list_next_entry(insn, list); | |
48 | ||
baa41469 | 49 | if (!next || &next->list == &file->insn_list || next->sec != insn->sec) |
dcc914f4 JP |
50 | return NULL; |
51 | ||
52 | return next; | |
53 | } | |
54 | ||
13810435 JP |
55 | static struct instruction *next_insn_same_func(struct objtool_file *file, |
56 | struct instruction *insn) | |
57 | { | |
58 | struct instruction *next = list_next_entry(insn, list); | |
59 | struct symbol *func = insn->func; | |
60 | ||
61 | if (!func) | |
62 | return NULL; | |
63 | ||
64 | if (&next->list != &file->insn_list && next->func == func) | |
65 | return next; | |
66 | ||
67 | /* Check if we're already in the subfunction: */ | |
68 | if (func == func->cfunc) | |
69 | return NULL; | |
70 | ||
71 | /* Move to the subfunction: */ | |
72 | return find_insn(file, func->cfunc->sec, func->cfunc->offset); | |
73 | } | |
74 | ||
75 | #define func_for_each_insn_all(file, func, insn) \ | |
76 | for (insn = find_insn(file, func->sec, func->offset); \ | |
77 | insn; \ | |
78 | insn = next_insn_same_func(file, insn)) | |
79 | ||
dcc914f4 JP |
80 | #define func_for_each_insn(file, func, insn) \ |
81 | for (insn = find_insn(file, func->sec, func->offset); \ | |
82 | insn && &insn->list != &file->insn_list && \ | |
83 | insn->sec == func->sec && \ | |
84 | insn->offset < func->offset + func->len; \ | |
85 | insn = list_next_entry(insn, list)) | |
86 | ||
87 | #define func_for_each_insn_continue_reverse(file, func, insn) \ | |
88 | for (insn = list_prev_entry(insn, list); \ | |
89 | &insn->list != &file->insn_list && \ | |
90 | insn->sec == func->sec && insn->offset >= func->offset; \ | |
91 | insn = list_prev_entry(insn, list)) | |
92 | ||
93 | #define sec_for_each_insn_from(file, insn) \ | |
94 | for (; insn; insn = next_insn_same_sec(file, insn)) | |
95 | ||
baa41469 JP |
96 | #define sec_for_each_insn_continue(file, insn) \ |
97 | for (insn = next_insn_same_sec(file, insn); insn; \ | |
98 | insn = next_insn_same_sec(file, insn)) | |
dcc914f4 | 99 | |
dcc914f4 JP |
100 | /* |
101 | * This checks to see if the given function is a "noreturn" function. | |
102 | * | |
103 | * For global functions which are outside the scope of this object file, we | |
104 | * have to keep a manual list of them. | |
105 | * | |
106 | * For local functions, we have to detect them manually by simply looking for | |
107 | * the lack of a return instruction. | |
108 | * | |
109 | * Returns: | |
110 | * -1: error | |
111 | * 0: no dead end | |
112 | * 1: dead end | |
113 | */ | |
114 | static int __dead_end_function(struct objtool_file *file, struct symbol *func, | |
115 | int recursion) | |
116 | { | |
117 | int i; | |
118 | struct instruction *insn; | |
119 | bool empty = true; | |
120 | ||
121 | /* | |
122 | * Unfortunately these have to be hard coded because the noreturn | |
123 | * attribute isn't provided in ELF data. | |
124 | */ | |
125 | static const char * const global_noreturns[] = { | |
126 | "__stack_chk_fail", | |
127 | "panic", | |
128 | "do_exit", | |
129 | "do_task_dead", | |
130 | "__module_put_and_exit", | |
131 | "complete_and_exit", | |
132 | "kvm_spurious_fault", | |
133 | "__reiserfs_panic", | |
134 | "lbug_with_loc", | |
135 | "fortify_panic", | |
b394d468 | 136 | "usercopy_abort", |
684fb246 | 137 | "machine_real_restart", |
4fa5ecda | 138 | "rewind_stack_do_exit", |
dcc914f4 JP |
139 | }; |
140 | ||
141 | if (func->bind == STB_WEAK) | |
142 | return 0; | |
143 | ||
144 | if (func->bind == STB_GLOBAL) | |
145 | for (i = 0; i < ARRAY_SIZE(global_noreturns); i++) | |
146 | if (!strcmp(func->name, global_noreturns[i])) | |
147 | return 1; | |
148 | ||
13810435 | 149 | if (!func->len) |
dcc914f4 JP |
150 | return 0; |
151 | ||
13810435 JP |
152 | insn = find_insn(file, func->sec, func->offset); |
153 | if (!insn->func) | |
154 | return 0; | |
155 | ||
156 | func_for_each_insn_all(file, func, insn) { | |
dcc914f4 JP |
157 | empty = false; |
158 | ||
159 | if (insn->type == INSN_RETURN) | |
160 | return 0; | |
161 | } | |
162 | ||
163 | if (empty) | |
164 | return 0; | |
165 | ||
166 | /* | |
167 | * A function can have a sibling call instead of a return. In that | |
168 | * case, the function's dead-end status depends on whether the target | |
169 | * of the sibling call returns. | |
170 | */ | |
13810435 | 171 | func_for_each_insn_all(file, func, insn) { |
dcc914f4 JP |
172 | if (insn->type == INSN_JUMP_UNCONDITIONAL) { |
173 | struct instruction *dest = insn->jump_dest; | |
dcc914f4 JP |
174 | |
175 | if (!dest) | |
176 | /* sibling call to another file */ | |
177 | return 0; | |
178 | ||
13810435 | 179 | if (dest->func && dest->func->pfunc != insn->func->pfunc) { |
dcc914f4 | 180 | |
13810435 | 181 | /* local sibling call */ |
dcc914f4 | 182 | if (recursion == 5) { |
0afd0d9e JP |
183 | /* |
184 | * Infinite recursion: two functions | |
185 | * have sibling calls to each other. | |
186 | * This is a very rare case. It means | |
187 | * they aren't dead ends. | |
188 | */ | |
189 | return 0; | |
dcc914f4 JP |
190 | } |
191 | ||
13810435 | 192 | return __dead_end_function(file, dest->func, |
dcc914f4 JP |
193 | recursion + 1); |
194 | } | |
195 | } | |
196 | ||
197 | if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts)) | |
198 | /* sibling call */ | |
199 | return 0; | |
200 | } | |
201 | ||
202 | return 1; | |
203 | } | |
204 | ||
205 | static int dead_end_function(struct objtool_file *file, struct symbol *func) | |
206 | { | |
207 | return __dead_end_function(file, func, 0); | |
208 | } | |
209 | ||
baa41469 JP |
210 | static void clear_insn_state(struct insn_state *state) |
211 | { | |
212 | int i; | |
213 | ||
214 | memset(state, 0, sizeof(*state)); | |
215 | state->cfa.base = CFI_UNDEFINED; | |
dd88a0a0 | 216 | for (i = 0; i < CFI_NUM_REGS; i++) { |
baa41469 | 217 | state->regs[i].base = CFI_UNDEFINED; |
dd88a0a0 JP |
218 | state->vals[i].base = CFI_UNDEFINED; |
219 | } | |
baa41469 | 220 | state->drap_reg = CFI_UNDEFINED; |
bf4d1a83 | 221 | state->drap_offset = -1; |
baa41469 JP |
222 | } |
223 | ||
dcc914f4 JP |
224 | /* |
225 | * Call the arch-specific instruction decoder for all the instructions and add | |
226 | * them to the global instruction list. | |
227 | */ | |
228 | static int decode_instructions(struct objtool_file *file) | |
229 | { | |
230 | struct section *sec; | |
231 | struct symbol *func; | |
232 | unsigned long offset; | |
233 | struct instruction *insn; | |
234 | int ret; | |
235 | ||
baa41469 | 236 | for_each_sec(file, sec) { |
dcc914f4 JP |
237 | |
238 | if (!(sec->sh.sh_flags & SHF_EXECINSTR)) | |
239 | continue; | |
240 | ||
627fce14 JP |
241 | if (strcmp(sec->name, ".altinstr_replacement") && |
242 | strcmp(sec->name, ".altinstr_aux") && | |
243 | strncmp(sec->name, ".discard.", 9)) | |
244 | sec->text = true; | |
245 | ||
dcc914f4 JP |
246 | for (offset = 0; offset < sec->len; offset += insn->len) { |
247 | insn = malloc(sizeof(*insn)); | |
baa41469 JP |
248 | if (!insn) { |
249 | WARN("malloc failed"); | |
250 | return -1; | |
251 | } | |
dcc914f4 | 252 | memset(insn, 0, sizeof(*insn)); |
dcc914f4 | 253 | INIT_LIST_HEAD(&insn->alts); |
baa41469 JP |
254 | clear_insn_state(&insn->state); |
255 | ||
dcc914f4 JP |
256 | insn->sec = sec; |
257 | insn->offset = offset; | |
258 | ||
259 | ret = arch_decode_instruction(file->elf, sec, offset, | |
260 | sec->len - offset, | |
261 | &insn->len, &insn->type, | |
baa41469 JP |
262 | &insn->immediate, |
263 | &insn->stack_op); | |
dcc914f4 | 264 | if (ret) |
b7037983 | 265 | goto err; |
dcc914f4 JP |
266 | |
267 | if (!insn->type || insn->type > INSN_LAST) { | |
268 | WARN_FUNC("invalid instruction type %d", | |
269 | insn->sec, insn->offset, insn->type); | |
b7037983 KB |
270 | ret = -1; |
271 | goto err; | |
dcc914f4 JP |
272 | } |
273 | ||
274 | hash_add(file->insn_hash, &insn->hash, insn->offset); | |
275 | list_add_tail(&insn->list, &file->insn_list); | |
276 | } | |
277 | ||
278 | list_for_each_entry(func, &sec->symbol_list, list) { | |
279 | if (func->type != STT_FUNC) | |
280 | continue; | |
281 | ||
282 | if (!find_insn(file, sec, func->offset)) { | |
283 | WARN("%s(): can't find starting instruction", | |
284 | func->name); | |
285 | return -1; | |
286 | } | |
287 | ||
288 | func_for_each_insn(file, func, insn) | |
289 | if (!insn->func) | |
290 | insn->func = func; | |
291 | } | |
292 | } | |
293 | ||
294 | return 0; | |
b7037983 KB |
295 | |
296 | err: | |
297 | free(insn); | |
298 | return ret; | |
dcc914f4 JP |
299 | } |
300 | ||
301 | /* | |
649ea4d5 | 302 | * Mark "ud2" instructions and manually annotated dead ends. |
dcc914f4 JP |
303 | */ |
304 | static int add_dead_ends(struct objtool_file *file) | |
305 | { | |
306 | struct section *sec; | |
307 | struct rela *rela; | |
308 | struct instruction *insn; | |
309 | bool found; | |
310 | ||
649ea4d5 JP |
311 | /* |
312 | * By default, "ud2" is a dead end unless otherwise annotated, because | |
313 | * GCC 7 inserts it for certain divide-by-zero cases. | |
314 | */ | |
315 | for_each_insn(file, insn) | |
316 | if (insn->type == INSN_BUG) | |
317 | insn->dead_end = true; | |
318 | ||
319 | /* | |
320 | * Check for manually annotated dead ends. | |
321 | */ | |
dcc914f4 JP |
322 | sec = find_section_by_name(file->elf, ".rela.discard.unreachable"); |
323 | if (!sec) | |
649ea4d5 | 324 | goto reachable; |
dcc914f4 JP |
325 | |
326 | list_for_each_entry(rela, &sec->rela_list, list) { | |
327 | if (rela->sym->type != STT_SECTION) { | |
328 | WARN("unexpected relocation symbol type in %s", sec->name); | |
329 | return -1; | |
330 | } | |
331 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
332 | if (insn) | |
333 | insn = list_prev_entry(insn, list); | |
334 | else if (rela->addend == rela->sym->sec->len) { | |
335 | found = false; | |
336 | list_for_each_entry_reverse(insn, &file->insn_list, list) { | |
337 | if (insn->sec == rela->sym->sec) { | |
338 | found = true; | |
339 | break; | |
340 | } | |
341 | } | |
342 | ||
343 | if (!found) { | |
344 | WARN("can't find unreachable insn at %s+0x%x", | |
345 | rela->sym->sec->name, rela->addend); | |
346 | return -1; | |
347 | } | |
348 | } else { | |
349 | WARN("can't find unreachable insn at %s+0x%x", | |
350 | rela->sym->sec->name, rela->addend); | |
351 | return -1; | |
352 | } | |
353 | ||
354 | insn->dead_end = true; | |
355 | } | |
356 | ||
649ea4d5 JP |
357 | reachable: |
358 | /* | |
359 | * These manually annotated reachable checks are needed for GCC 4.4, | |
360 | * where the Linux unreachable() macro isn't supported. In that case | |
361 | * GCC doesn't know the "ud2" is fatal, so it generates code as if it's | |
362 | * not a dead end. | |
363 | */ | |
364 | sec = find_section_by_name(file->elf, ".rela.discard.reachable"); | |
365 | if (!sec) | |
366 | return 0; | |
367 | ||
368 | list_for_each_entry(rela, &sec->rela_list, list) { | |
369 | if (rela->sym->type != STT_SECTION) { | |
370 | WARN("unexpected relocation symbol type in %s", sec->name); | |
371 | return -1; | |
372 | } | |
373 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
374 | if (insn) | |
375 | insn = list_prev_entry(insn, list); | |
376 | else if (rela->addend == rela->sym->sec->len) { | |
377 | found = false; | |
378 | list_for_each_entry_reverse(insn, &file->insn_list, list) { | |
379 | if (insn->sec == rela->sym->sec) { | |
380 | found = true; | |
381 | break; | |
382 | } | |
383 | } | |
384 | ||
385 | if (!found) { | |
386 | WARN("can't find reachable insn at %s+0x%x", | |
387 | rela->sym->sec->name, rela->addend); | |
388 | return -1; | |
389 | } | |
390 | } else { | |
391 | WARN("can't find reachable insn at %s+0x%x", | |
392 | rela->sym->sec->name, rela->addend); | |
393 | return -1; | |
394 | } | |
395 | ||
396 | insn->dead_end = false; | |
397 | } | |
398 | ||
dcc914f4 JP |
399 | return 0; |
400 | } | |
401 | ||
402 | /* | |
403 | * Warnings shouldn't be reported for ignored functions. | |
404 | */ | |
405 | static void add_ignores(struct objtool_file *file) | |
406 | { | |
407 | struct instruction *insn; | |
408 | struct section *sec; | |
409 | struct symbol *func; | |
aaf5c623 | 410 | struct rela *rela; |
dcc914f4 | 411 | |
aaf5c623 PZ |
412 | sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard"); |
413 | if (!sec) | |
414 | return; | |
dcc914f4 | 415 | |
aaf5c623 PZ |
416 | list_for_each_entry(rela, &sec->rela_list, list) { |
417 | switch (rela->sym->type) { | |
418 | case STT_FUNC: | |
419 | func = rela->sym; | |
420 | break; | |
421 | ||
422 | case STT_SECTION: | |
423 | func = find_symbol_by_offset(rela->sym->sec, rela->addend); | |
424 | if (!func || func->type != STT_FUNC) | |
dcc914f4 | 425 | continue; |
aaf5c623 | 426 | break; |
dcc914f4 | 427 | |
aaf5c623 PZ |
428 | default: |
429 | WARN("unexpected relocation symbol type in %s: %d", sec->name, rela->sym->type); | |
430 | continue; | |
dcc914f4 | 431 | } |
aaf5c623 PZ |
432 | |
433 | func_for_each_insn_all(file, func, insn) | |
434 | insn->ignore = true; | |
dcc914f4 JP |
435 | } |
436 | } | |
437 | ||
ea24213d PZ |
438 | /* |
439 | * This is a whitelist of functions that is allowed to be called with AC set. | |
440 | * The list is meant to be minimal and only contains compiler instrumentation | |
441 | * ABI and a few functions used to implement *_{to,from}_user() functions. | |
442 | * | |
443 | * These functions must not directly change AC, but may PUSHF/POPF. | |
444 | */ | |
445 | static const char *uaccess_safe_builtin[] = { | |
446 | /* KASAN */ | |
447 | "kasan_report", | |
448 | "check_memory_region", | |
449 | /* KASAN out-of-line */ | |
450 | "__asan_loadN_noabort", | |
451 | "__asan_load1_noabort", | |
452 | "__asan_load2_noabort", | |
453 | "__asan_load4_noabort", | |
454 | "__asan_load8_noabort", | |
455 | "__asan_load16_noabort", | |
456 | "__asan_storeN_noabort", | |
457 | "__asan_store1_noabort", | |
458 | "__asan_store2_noabort", | |
459 | "__asan_store4_noabort", | |
460 | "__asan_store8_noabort", | |
461 | "__asan_store16_noabort", | |
462 | /* KASAN in-line */ | |
463 | "__asan_report_load_n_noabort", | |
464 | "__asan_report_load1_noabort", | |
465 | "__asan_report_load2_noabort", | |
466 | "__asan_report_load4_noabort", | |
467 | "__asan_report_load8_noabort", | |
468 | "__asan_report_load16_noabort", | |
469 | "__asan_report_store_n_noabort", | |
470 | "__asan_report_store1_noabort", | |
471 | "__asan_report_store2_noabort", | |
472 | "__asan_report_store4_noabort", | |
473 | "__asan_report_store8_noabort", | |
474 | "__asan_report_store16_noabort", | |
475 | /* KCOV */ | |
476 | "write_comp_data", | |
477 | "__sanitizer_cov_trace_pc", | |
478 | "__sanitizer_cov_trace_const_cmp1", | |
479 | "__sanitizer_cov_trace_const_cmp2", | |
480 | "__sanitizer_cov_trace_const_cmp4", | |
481 | "__sanitizer_cov_trace_const_cmp8", | |
482 | "__sanitizer_cov_trace_cmp1", | |
483 | "__sanitizer_cov_trace_cmp2", | |
484 | "__sanitizer_cov_trace_cmp4", | |
485 | "__sanitizer_cov_trace_cmp8", | |
486 | /* UBSAN */ | |
487 | "ubsan_type_mismatch_common", | |
488 | "__ubsan_handle_type_mismatch", | |
489 | "__ubsan_handle_type_mismatch_v1", | |
490 | /* misc */ | |
491 | "csum_partial_copy_generic", | |
492 | "__memcpy_mcsafe", | |
a7e47f26 | 493 | "mcsafe_handle_tail", |
ea24213d PZ |
494 | "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */ |
495 | NULL | |
496 | }; | |
497 | ||
498 | static void add_uaccess_safe(struct objtool_file *file) | |
499 | { | |
500 | struct symbol *func; | |
501 | const char **name; | |
502 | ||
503 | if (!uaccess) | |
504 | return; | |
505 | ||
506 | for (name = uaccess_safe_builtin; *name; name++) { | |
507 | func = find_symbol_by_name(file->elf, *name); | |
508 | if (!func) | |
509 | continue; | |
510 | ||
511 | func->alias->uaccess_safe = true; | |
dcc914f4 JP |
512 | } |
513 | } | |
514 | ||
258c7605 JP |
515 | /* |
516 | * FIXME: For now, just ignore any alternatives which add retpolines. This is | |
517 | * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline. | |
518 | * But it at least allows objtool to understand the control flow *around* the | |
519 | * retpoline. | |
520 | */ | |
ff05ab23 | 521 | static int add_ignore_alternatives(struct objtool_file *file) |
258c7605 JP |
522 | { |
523 | struct section *sec; | |
524 | struct rela *rela; | |
525 | struct instruction *insn; | |
526 | ||
ff05ab23 | 527 | sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts"); |
258c7605 JP |
528 | if (!sec) |
529 | return 0; | |
530 | ||
531 | list_for_each_entry(rela, &sec->rela_list, list) { | |
532 | if (rela->sym->type != STT_SECTION) { | |
533 | WARN("unexpected relocation symbol type in %s", sec->name); | |
534 | return -1; | |
535 | } | |
536 | ||
537 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
538 | if (!insn) { | |
ff05ab23 | 539 | WARN("bad .discard.ignore_alts entry"); |
258c7605 JP |
540 | return -1; |
541 | } | |
542 | ||
543 | insn->ignore_alts = true; | |
544 | } | |
545 | ||
546 | return 0; | |
547 | } | |
548 | ||
dcc914f4 JP |
549 | /* |
550 | * Find the destination instructions for all jumps. | |
551 | */ | |
552 | static int add_jump_destinations(struct objtool_file *file) | |
553 | { | |
554 | struct instruction *insn; | |
555 | struct rela *rela; | |
556 | struct section *dest_sec; | |
557 | unsigned long dest_off; | |
558 | ||
559 | for_each_insn(file, insn) { | |
560 | if (insn->type != INSN_JUMP_CONDITIONAL && | |
561 | insn->type != INSN_JUMP_UNCONDITIONAL) | |
562 | continue; | |
563 | ||
e6da9567 | 564 | if (insn->ignore || insn->offset == FAKE_JUMP_OFFSET) |
dcc914f4 JP |
565 | continue; |
566 | ||
567 | rela = find_rela_by_dest_range(insn->sec, insn->offset, | |
568 | insn->len); | |
569 | if (!rela) { | |
570 | dest_sec = insn->sec; | |
571 | dest_off = insn->offset + insn->len + insn->immediate; | |
572 | } else if (rela->sym->type == STT_SECTION) { | |
573 | dest_sec = rela->sym->sec; | |
574 | dest_off = rela->addend + 4; | |
575 | } else if (rela->sym->sec->idx) { | |
576 | dest_sec = rela->sym->sec; | |
577 | dest_off = rela->sym->sym.st_value + rela->addend + 4; | |
39b73533 JP |
578 | } else if (strstr(rela->sym->name, "_indirect_thunk_")) { |
579 | /* | |
580 | * Retpoline jumps are really dynamic jumps in | |
581 | * disguise, so convert them accordingly. | |
582 | */ | |
583 | insn->type = INSN_JUMP_DYNAMIC; | |
b5bc2231 | 584 | insn->retpoline_safe = true; |
39b73533 | 585 | continue; |
dcc914f4 JP |
586 | } else { |
587 | /* sibling call */ | |
54262aa2 PZ |
588 | insn->call_dest = rela->sym; |
589 | insn->jump_dest = NULL; | |
dcc914f4 JP |
590 | continue; |
591 | } | |
592 | ||
593 | insn->jump_dest = find_insn(file, dest_sec, dest_off); | |
594 | if (!insn->jump_dest) { | |
595 | ||
596 | /* | |
597 | * This is a special case where an alt instruction | |
598 | * jumps past the end of the section. These are | |
599 | * handled later in handle_group_alt(). | |
600 | */ | |
601 | if (!strcmp(insn->sec->name, ".altinstr_replacement")) | |
602 | continue; | |
603 | ||
604 | WARN_FUNC("can't find jump dest instruction at %s+0x%lx", | |
605 | insn->sec, insn->offset, dest_sec->name, | |
606 | dest_off); | |
607 | return -1; | |
608 | } | |
cd77849a JP |
609 | |
610 | /* | |
54262aa2 | 611 | * Cross-function jump. |
cd77849a JP |
612 | */ |
613 | if (insn->func && insn->jump_dest->func && | |
54262aa2 PZ |
614 | insn->func != insn->jump_dest->func) { |
615 | ||
616 | /* | |
617 | * For GCC 8+, create parent/child links for any cold | |
618 | * subfunctions. This is _mostly_ redundant with a | |
619 | * similar initialization in read_symbols(). | |
620 | * | |
621 | * If a function has aliases, we want the *first* such | |
622 | * function in the symbol table to be the subfunction's | |
623 | * parent. In that case we overwrite the | |
624 | * initialization done in read_symbols(). | |
625 | * | |
626 | * However this code can't completely replace the | |
627 | * read_symbols() code because this doesn't detect the | |
628 | * case where the parent function's only reference to a | |
629 | * subfunction is through a switch table. | |
630 | */ | |
631 | if (!strstr(insn->func->name, ".cold.") && | |
632 | strstr(insn->jump_dest->func->name, ".cold.")) { | |
633 | insn->func->cfunc = insn->jump_dest->func; | |
634 | insn->jump_dest->func->pfunc = insn->func; | |
635 | ||
636 | } else if (insn->jump_dest->func->pfunc != insn->func->pfunc && | |
637 | insn->jump_dest->offset == insn->jump_dest->func->offset) { | |
638 | ||
639 | /* sibling class */ | |
640 | insn->call_dest = insn->jump_dest->func; | |
641 | insn->jump_dest = NULL; | |
642 | } | |
cd77849a | 643 | } |
dcc914f4 JP |
644 | } |
645 | ||
646 | return 0; | |
647 | } | |
648 | ||
649 | /* | |
650 | * Find the destination instructions for all calls. | |
651 | */ | |
652 | static int add_call_destinations(struct objtool_file *file) | |
653 | { | |
654 | struct instruction *insn; | |
655 | unsigned long dest_off; | |
656 | struct rela *rela; | |
657 | ||
658 | for_each_insn(file, insn) { | |
659 | if (insn->type != INSN_CALL) | |
660 | continue; | |
661 | ||
662 | rela = find_rela_by_dest_range(insn->sec, insn->offset, | |
663 | insn->len); | |
664 | if (!rela) { | |
665 | dest_off = insn->offset + insn->len + insn->immediate; | |
666 | insn->call_dest = find_symbol_by_offset(insn->sec, | |
667 | dest_off); | |
a845c7cf JP |
668 | |
669 | if (!insn->call_dest && !insn->ignore) { | |
670 | WARN_FUNC("unsupported intra-function call", | |
671 | insn->sec, insn->offset); | |
b5bc2231 PZ |
672 | if (retpoline) |
673 | WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE."); | |
dcc914f4 JP |
674 | return -1; |
675 | } | |
a845c7cf | 676 | |
dcc914f4 JP |
677 | } else if (rela->sym->type == STT_SECTION) { |
678 | insn->call_dest = find_symbol_by_offset(rela->sym->sec, | |
679 | rela->addend+4); | |
680 | if (!insn->call_dest || | |
681 | insn->call_dest->type != STT_FUNC) { | |
682 | WARN_FUNC("can't find call dest symbol at %s+0x%x", | |
683 | insn->sec, insn->offset, | |
684 | rela->sym->sec->name, | |
685 | rela->addend + 4); | |
686 | return -1; | |
687 | } | |
688 | } else | |
689 | insn->call_dest = rela->sym; | |
690 | } | |
691 | ||
692 | return 0; | |
693 | } | |
694 | ||
695 | /* | |
696 | * The .alternatives section requires some extra special care, over and above | |
697 | * what other special sections require: | |
698 | * | |
699 | * 1. Because alternatives are patched in-place, we need to insert a fake jump | |
700 | * instruction at the end so that validate_branch() skips all the original | |
701 | * replaced instructions when validating the new instruction path. | |
702 | * | |
703 | * 2. An added wrinkle is that the new instruction length might be zero. In | |
704 | * that case the old instructions are replaced with noops. We simulate that | |
705 | * by creating a fake jump as the only new instruction. | |
706 | * | |
707 | * 3. In some cases, the alternative section includes an instruction which | |
708 | * conditionally jumps to the _end_ of the entry. We have to modify these | |
709 | * jumps' destinations to point back to .text rather than the end of the | |
710 | * entry in .altinstr_replacement. | |
dcc914f4 JP |
711 | */ |
712 | static int handle_group_alt(struct objtool_file *file, | |
713 | struct special_alt *special_alt, | |
714 | struct instruction *orig_insn, | |
715 | struct instruction **new_insn) | |
716 | { | |
17bc3391 | 717 | struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL; |
dcc914f4 JP |
718 | unsigned long dest_off; |
719 | ||
720 | last_orig_insn = NULL; | |
721 | insn = orig_insn; | |
722 | sec_for_each_insn_from(file, insn) { | |
723 | if (insn->offset >= special_alt->orig_off + special_alt->orig_len) | |
724 | break; | |
725 | ||
dcc914f4 JP |
726 | insn->alt_group = true; |
727 | last_orig_insn = insn; | |
728 | } | |
729 | ||
17bc3391 JP |
730 | if (next_insn_same_sec(file, last_orig_insn)) { |
731 | fake_jump = malloc(sizeof(*fake_jump)); | |
732 | if (!fake_jump) { | |
733 | WARN("malloc failed"); | |
734 | return -1; | |
735 | } | |
736 | memset(fake_jump, 0, sizeof(*fake_jump)); | |
737 | INIT_LIST_HEAD(&fake_jump->alts); | |
738 | clear_insn_state(&fake_jump->state); | |
739 | ||
740 | fake_jump->sec = special_alt->new_sec; | |
e6da9567 | 741 | fake_jump->offset = FAKE_JUMP_OFFSET; |
17bc3391 JP |
742 | fake_jump->type = INSN_JUMP_UNCONDITIONAL; |
743 | fake_jump->jump_dest = list_next_entry(last_orig_insn, list); | |
e6da9567 | 744 | fake_jump->func = orig_insn->func; |
dcc914f4 | 745 | } |
dcc914f4 JP |
746 | |
747 | if (!special_alt->new_len) { | |
17bc3391 JP |
748 | if (!fake_jump) { |
749 | WARN("%s: empty alternative at end of section", | |
750 | special_alt->orig_sec->name); | |
751 | return -1; | |
752 | } | |
753 | ||
dcc914f4 JP |
754 | *new_insn = fake_jump; |
755 | return 0; | |
756 | } | |
757 | ||
758 | last_new_insn = NULL; | |
759 | insn = *new_insn; | |
760 | sec_for_each_insn_from(file, insn) { | |
761 | if (insn->offset >= special_alt->new_off + special_alt->new_len) | |
762 | break; | |
763 | ||
764 | last_new_insn = insn; | |
765 | ||
a845c7cf | 766 | insn->ignore = orig_insn->ignore_alts; |
a4d09dde | 767 | insn->func = orig_insn->func; |
a845c7cf | 768 | |
dcc914f4 JP |
769 | if (insn->type != INSN_JUMP_CONDITIONAL && |
770 | insn->type != INSN_JUMP_UNCONDITIONAL) | |
771 | continue; | |
772 | ||
773 | if (!insn->immediate) | |
774 | continue; | |
775 | ||
776 | dest_off = insn->offset + insn->len + insn->immediate; | |
17bc3391 JP |
777 | if (dest_off == special_alt->new_off + special_alt->new_len) { |
778 | if (!fake_jump) { | |
779 | WARN("%s: alternative jump to end of section", | |
780 | special_alt->orig_sec->name); | |
781 | return -1; | |
782 | } | |
dcc914f4 | 783 | insn->jump_dest = fake_jump; |
17bc3391 | 784 | } |
dcc914f4 JP |
785 | |
786 | if (!insn->jump_dest) { | |
787 | WARN_FUNC("can't find alternative jump destination", | |
788 | insn->sec, insn->offset); | |
789 | return -1; | |
790 | } | |
791 | } | |
792 | ||
793 | if (!last_new_insn) { | |
794 | WARN_FUNC("can't find last new alternative instruction", | |
795 | special_alt->new_sec, special_alt->new_off); | |
796 | return -1; | |
797 | } | |
798 | ||
17bc3391 JP |
799 | if (fake_jump) |
800 | list_add(&fake_jump->list, &last_new_insn->list); | |
dcc914f4 JP |
801 | |
802 | return 0; | |
803 | } | |
804 | ||
805 | /* | |
806 | * A jump table entry can either convert a nop to a jump or a jump to a nop. | |
807 | * If the original instruction is a jump, make the alt entry an effective nop | |
808 | * by just skipping the original instruction. | |
809 | */ | |
810 | static int handle_jump_alt(struct objtool_file *file, | |
811 | struct special_alt *special_alt, | |
812 | struct instruction *orig_insn, | |
813 | struct instruction **new_insn) | |
814 | { | |
815 | if (orig_insn->type == INSN_NOP) | |
816 | return 0; | |
817 | ||
818 | if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) { | |
819 | WARN_FUNC("unsupported instruction at jump label", | |
820 | orig_insn->sec, orig_insn->offset); | |
821 | return -1; | |
822 | } | |
823 | ||
824 | *new_insn = list_next_entry(orig_insn, list); | |
825 | return 0; | |
826 | } | |
827 | ||
828 | /* | |
829 | * Read all the special sections which have alternate instructions which can be | |
830 | * patched in or redirected to at runtime. Each instruction having alternate | |
831 | * instruction(s) has them added to its insn->alts list, which will be | |
832 | * traversed in validate_branch(). | |
833 | */ | |
834 | static int add_special_section_alts(struct objtool_file *file) | |
835 | { | |
836 | struct list_head special_alts; | |
837 | struct instruction *orig_insn, *new_insn; | |
838 | struct special_alt *special_alt, *tmp; | |
839 | struct alternative *alt; | |
840 | int ret; | |
841 | ||
842 | ret = special_get_alts(file->elf, &special_alts); | |
843 | if (ret) | |
844 | return ret; | |
845 | ||
846 | list_for_each_entry_safe(special_alt, tmp, &special_alts, list) { | |
dcc914f4 JP |
847 | |
848 | orig_insn = find_insn(file, special_alt->orig_sec, | |
849 | special_alt->orig_off); | |
850 | if (!orig_insn) { | |
851 | WARN_FUNC("special: can't find orig instruction", | |
852 | special_alt->orig_sec, special_alt->orig_off); | |
853 | ret = -1; | |
854 | goto out; | |
855 | } | |
856 | ||
857 | new_insn = NULL; | |
858 | if (!special_alt->group || special_alt->new_len) { | |
859 | new_insn = find_insn(file, special_alt->new_sec, | |
860 | special_alt->new_off); | |
861 | if (!new_insn) { | |
862 | WARN_FUNC("special: can't find new instruction", | |
863 | special_alt->new_sec, | |
864 | special_alt->new_off); | |
865 | ret = -1; | |
866 | goto out; | |
867 | } | |
868 | } | |
869 | ||
870 | if (special_alt->group) { | |
871 | ret = handle_group_alt(file, special_alt, orig_insn, | |
872 | &new_insn); | |
873 | if (ret) | |
874 | goto out; | |
875 | } else if (special_alt->jump_or_nop) { | |
876 | ret = handle_jump_alt(file, special_alt, orig_insn, | |
877 | &new_insn); | |
878 | if (ret) | |
879 | goto out; | |
880 | } | |
881 | ||
258c7605 JP |
882 | alt = malloc(sizeof(*alt)); |
883 | if (!alt) { | |
884 | WARN("malloc failed"); | |
885 | ret = -1; | |
886 | goto out; | |
887 | } | |
888 | ||
dcc914f4 | 889 | alt->insn = new_insn; |
764eef4b | 890 | alt->skip_orig = special_alt->skip_orig; |
ea24213d | 891 | orig_insn->ignore_alts |= special_alt->skip_alt; |
dcc914f4 JP |
892 | list_add_tail(&alt->list, &orig_insn->alts); |
893 | ||
894 | list_del(&special_alt->list); | |
895 | free(special_alt); | |
896 | } | |
897 | ||
898 | out: | |
899 | return ret; | |
900 | } | |
901 | ||
13810435 JP |
902 | static int add_switch_table(struct objtool_file *file, struct instruction *insn, |
903 | struct rela *table, struct rela *next_table) | |
dcc914f4 JP |
904 | { |
905 | struct rela *rela = table; | |
906 | struct instruction *alt_insn; | |
907 | struct alternative *alt; | |
fd35c88b JP |
908 | struct symbol *pfunc = insn->func->pfunc; |
909 | unsigned int prev_offset = 0; | |
dcc914f4 | 910 | |
4a60aa05 | 911 | list_for_each_entry_from(rela, &table->rela_sec->rela_list, list) { |
dcc914f4 JP |
912 | if (rela == next_table) |
913 | break; | |
914 | ||
fd35c88b JP |
915 | /* Make sure the switch table entries are consecutive: */ |
916 | if (prev_offset && rela->offset != prev_offset + 8) | |
917 | break; | |
918 | ||
919 | /* Detect function pointers from contiguous objects: */ | |
920 | if (rela->sym->sec == pfunc->sec && | |
921 | rela->addend == pfunc->offset) | |
922 | break; | |
923 | ||
13810435 JP |
924 | alt_insn = find_insn(file, rela->sym->sec, rela->addend); |
925 | if (!alt_insn) | |
dcc914f4 JP |
926 | break; |
927 | ||
13810435 | 928 | /* Make sure the jmp dest is in the function or subfunction: */ |
fd35c88b | 929 | if (alt_insn->func->pfunc != pfunc) |
13810435 | 930 | break; |
dcc914f4 JP |
931 | |
932 | alt = malloc(sizeof(*alt)); | |
933 | if (!alt) { | |
934 | WARN("malloc failed"); | |
935 | return -1; | |
936 | } | |
937 | ||
938 | alt->insn = alt_insn; | |
939 | list_add_tail(&alt->list, &insn->alts); | |
fd35c88b JP |
940 | prev_offset = rela->offset; |
941 | } | |
942 | ||
943 | if (!prev_offset) { | |
944 | WARN_FUNC("can't find switch jump table", | |
945 | insn->sec, insn->offset); | |
946 | return -1; | |
dcc914f4 JP |
947 | } |
948 | ||
949 | return 0; | |
950 | } | |
951 | ||
952 | /* | |
953 | * find_switch_table() - Given a dynamic jump, find the switch jump table in | |
954 | * .rodata associated with it. | |
955 | * | |
956 | * There are 3 basic patterns: | |
957 | * | |
958 | * 1. jmpq *[rodata addr](,%reg,8) | |
959 | * | |
960 | * This is the most common case by far. It jumps to an address in a simple | |
961 | * jump table which is stored in .rodata. | |
962 | * | |
963 | * 2. jmpq *[rodata addr](%rip) | |
964 | * | |
965 | * This is caused by a rare GCC quirk, currently only seen in three driver | |
966 | * functions in the kernel, only with certain obscure non-distro configs. | |
967 | * | |
968 | * As part of an optimization, GCC makes a copy of an existing switch jump | |
969 | * table, modifies it, and then hard-codes the jump (albeit with an indirect | |
970 | * jump) to use a single entry in the table. The rest of the jump table and | |
971 | * some of its jump targets remain as dead code. | |
972 | * | |
973 | * In such a case we can just crudely ignore all unreachable instruction | |
974 | * warnings for the entire object file. Ideally we would just ignore them | |
975 | * for the function, but that would require redesigning the code quite a | |
976 | * bit. And honestly that's just not worth doing: unreachable instruction | |
977 | * warnings are of questionable value anyway, and this is such a rare issue. | |
978 | * | |
979 | * 3. mov [rodata addr],%reg1 | |
980 | * ... some instructions ... | |
981 | * jmpq *(%reg1,%reg2,8) | |
982 | * | |
983 | * This is a fairly uncommon pattern which is new for GCC 6. As of this | |
984 | * writing, there are 11 occurrences of it in the allmodconfig kernel. | |
985 | * | |
99ce7962 PZ |
986 | * As of GCC 7 there are quite a few more of these and the 'in between' code |
987 | * is significant. Esp. with KASAN enabled some of the code between the mov | |
988 | * and jmpq uses .rodata itself, which can confuse things. | |
989 | * | |
dcc914f4 JP |
990 | * TODO: Once we have DWARF CFI and smarter instruction decoding logic, |
991 | * ensure the same register is used in the mov and jump instructions. | |
99ce7962 PZ |
992 | * |
993 | * NOTE: RETPOLINE made it harder still to decode dynamic jumps. | |
dcc914f4 JP |
994 | */ |
995 | static struct rela *find_switch_table(struct objtool_file *file, | |
996 | struct symbol *func, | |
997 | struct instruction *insn) | |
998 | { | |
999 | struct rela *text_rela, *rodata_rela; | |
1000 | struct instruction *orig_insn = insn; | |
4a60aa05 | 1001 | struct section *rodata_sec; |
6f5ec299 | 1002 | unsigned long table_offset; |
dcc914f4 | 1003 | |
99ce7962 PZ |
1004 | /* |
1005 | * Backward search using the @first_jump_src links, these help avoid | |
1006 | * much of the 'in between' code. Which avoids us getting confused by | |
1007 | * it. | |
1008 | */ | |
7dec80cc | 1009 | for (; |
99ce7962 PZ |
1010 | &insn->list != &file->insn_list && |
1011 | insn->sec == func->sec && | |
1012 | insn->offset >= func->offset; | |
1013 | ||
1014 | insn = insn->first_jump_src ?: list_prev_entry(insn, list)) { | |
1015 | ||
7dec80cc | 1016 | if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC) |
dcc914f4 JP |
1017 | break; |
1018 | ||
1019 | /* allow small jumps within the range */ | |
1020 | if (insn->type == INSN_JUMP_UNCONDITIONAL && | |
1021 | insn->jump_dest && | |
1022 | (insn->jump_dest->offset <= insn->offset || | |
1023 | insn->jump_dest->offset > orig_insn->offset)) | |
1024 | break; | |
1025 | ||
1026 | /* look for a relocation which references .rodata */ | |
1027 | text_rela = find_rela_by_dest_range(insn->sec, insn->offset, | |
1028 | insn->len); | |
4a60aa05 AX |
1029 | if (!text_rela || text_rela->sym->type != STT_SECTION || |
1030 | !text_rela->sym->sec->rodata) | |
dcc914f4 JP |
1031 | continue; |
1032 | ||
6f5ec299 | 1033 | table_offset = text_rela->addend; |
4a60aa05 AX |
1034 | rodata_sec = text_rela->sym->sec; |
1035 | ||
6f5ec299 JP |
1036 | if (text_rela->type == R_X86_64_PC32) |
1037 | table_offset += 4; | |
1038 | ||
dcc914f4 JP |
1039 | /* |
1040 | * Make sure the .rodata address isn't associated with a | |
87b512de JP |
1041 | * symbol. GCC jump tables are anonymous data. |
1042 | * | |
1043 | * Also support C jump tables which are in the same format as | |
1044 | * switch jump tables. For objtool to recognize them, they | |
1045 | * need to be placed in the C_JUMP_TABLE_SECTION section. They | |
1046 | * have symbols associated with them. | |
dcc914f4 | 1047 | */ |
87b512de JP |
1048 | if (find_symbol_containing(rodata_sec, table_offset) && |
1049 | strcmp(rodata_sec->name, C_JUMP_TABLE_SECTION)) | |
1402fd8e JP |
1050 | continue; |
1051 | ||
4a60aa05 | 1052 | rodata_rela = find_rela_by_dest(rodata_sec, table_offset); |
7dec80cc JP |
1053 | if (rodata_rela) { |
1054 | /* | |
1055 | * Use of RIP-relative switch jumps is quite rare, and | |
1056 | * indicates a rare GCC quirk/bug which can leave dead | |
1057 | * code behind. | |
1058 | */ | |
1059 | if (text_rela->type == R_X86_64_PC32) | |
1060 | file->ignore_unreachables = true; | |
1061 | ||
6f5ec299 | 1062 | return rodata_rela; |
7dec80cc | 1063 | } |
dcc914f4 JP |
1064 | } |
1065 | ||
1066 | return NULL; | |
1067 | } | |
1068 | ||
99ce7962 | 1069 | |
dcc914f4 JP |
1070 | static int add_func_switch_tables(struct objtool_file *file, |
1071 | struct symbol *func) | |
1072 | { | |
99ce7962 | 1073 | struct instruction *insn, *last = NULL, *prev_jump = NULL; |
dcc914f4 JP |
1074 | struct rela *rela, *prev_rela = NULL; |
1075 | int ret; | |
1076 | ||
13810435 | 1077 | func_for_each_insn_all(file, func, insn) { |
99ce7962 PZ |
1078 | if (!last) |
1079 | last = insn; | |
1080 | ||
1081 | /* | |
1082 | * Store back-pointers for unconditional forward jumps such | |
1083 | * that find_switch_table() can back-track using those and | |
1084 | * avoid some potentially confusing code. | |
1085 | */ | |
1086 | if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest && | |
1087 | insn->offset > last->offset && | |
1088 | insn->jump_dest->offset > insn->offset && | |
1089 | !insn->jump_dest->first_jump_src) { | |
1090 | ||
1091 | insn->jump_dest->first_jump_src = insn; | |
1092 | last = insn->jump_dest; | |
1093 | } | |
1094 | ||
dcc914f4 JP |
1095 | if (insn->type != INSN_JUMP_DYNAMIC) |
1096 | continue; | |
1097 | ||
1098 | rela = find_switch_table(file, func, insn); | |
1099 | if (!rela) | |
1100 | continue; | |
1101 | ||
1102 | /* | |
1103 | * We found a switch table, but we don't know yet how big it | |
1104 | * is. Don't add it until we reach the end of the function or | |
1105 | * the beginning of another switch table in the same function. | |
1106 | */ | |
1107 | if (prev_jump) { | |
13810435 | 1108 | ret = add_switch_table(file, prev_jump, prev_rela, rela); |
dcc914f4 JP |
1109 | if (ret) |
1110 | return ret; | |
1111 | } | |
1112 | ||
1113 | prev_jump = insn; | |
1114 | prev_rela = rela; | |
1115 | } | |
1116 | ||
1117 | if (prev_jump) { | |
13810435 | 1118 | ret = add_switch_table(file, prev_jump, prev_rela, NULL); |
dcc914f4 JP |
1119 | if (ret) |
1120 | return ret; | |
1121 | } | |
1122 | ||
1123 | return 0; | |
1124 | } | |
1125 | ||
1126 | /* | |
1127 | * For some switch statements, gcc generates a jump table in the .rodata | |
1128 | * section which contains a list of addresses within the function to jump to. | |
1129 | * This finds these jump tables and adds them to the insn->alts lists. | |
1130 | */ | |
1131 | static int add_switch_table_alts(struct objtool_file *file) | |
1132 | { | |
1133 | struct section *sec; | |
1134 | struct symbol *func; | |
1135 | int ret; | |
1136 | ||
4a60aa05 | 1137 | if (!file->rodata) |
dcc914f4 JP |
1138 | return 0; |
1139 | ||
baa41469 | 1140 | for_each_sec(file, sec) { |
dcc914f4 JP |
1141 | list_for_each_entry(func, &sec->symbol_list, list) { |
1142 | if (func->type != STT_FUNC) | |
1143 | continue; | |
1144 | ||
1145 | ret = add_func_switch_tables(file, func); | |
1146 | if (ret) | |
1147 | return ret; | |
1148 | } | |
1149 | } | |
1150 | ||
1151 | return 0; | |
1152 | } | |
1153 | ||
39358a03 JP |
1154 | static int read_unwind_hints(struct objtool_file *file) |
1155 | { | |
1156 | struct section *sec, *relasec; | |
1157 | struct rela *rela; | |
1158 | struct unwind_hint *hint; | |
1159 | struct instruction *insn; | |
1160 | struct cfi_reg *cfa; | |
1161 | int i; | |
1162 | ||
1163 | sec = find_section_by_name(file->elf, ".discard.unwind_hints"); | |
1164 | if (!sec) | |
1165 | return 0; | |
1166 | ||
1167 | relasec = sec->rela; | |
1168 | if (!relasec) { | |
1169 | WARN("missing .rela.discard.unwind_hints section"); | |
1170 | return -1; | |
1171 | } | |
1172 | ||
1173 | if (sec->len % sizeof(struct unwind_hint)) { | |
1174 | WARN("struct unwind_hint size mismatch"); | |
1175 | return -1; | |
1176 | } | |
1177 | ||
1178 | file->hints = true; | |
1179 | ||
1180 | for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) { | |
1181 | hint = (struct unwind_hint *)sec->data->d_buf + i; | |
1182 | ||
1183 | rela = find_rela_by_dest(sec, i * sizeof(*hint)); | |
1184 | if (!rela) { | |
1185 | WARN("can't find rela for unwind_hints[%d]", i); | |
1186 | return -1; | |
1187 | } | |
1188 | ||
1189 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
1190 | if (!insn) { | |
1191 | WARN("can't find insn for unwind_hints[%d]", i); | |
1192 | return -1; | |
1193 | } | |
1194 | ||
1195 | cfa = &insn->state.cfa; | |
1196 | ||
1197 | if (hint->type == UNWIND_HINT_TYPE_SAVE) { | |
1198 | insn->save = true; | |
1199 | continue; | |
1200 | ||
1201 | } else if (hint->type == UNWIND_HINT_TYPE_RESTORE) { | |
1202 | insn->restore = true; | |
1203 | insn->hint = true; | |
1204 | continue; | |
1205 | } | |
1206 | ||
1207 | insn->hint = true; | |
1208 | ||
1209 | switch (hint->sp_reg) { | |
1210 | case ORC_REG_UNDEFINED: | |
1211 | cfa->base = CFI_UNDEFINED; | |
1212 | break; | |
1213 | case ORC_REG_SP: | |
1214 | cfa->base = CFI_SP; | |
1215 | break; | |
1216 | case ORC_REG_BP: | |
1217 | cfa->base = CFI_BP; | |
1218 | break; | |
1219 | case ORC_REG_SP_INDIRECT: | |
1220 | cfa->base = CFI_SP_INDIRECT; | |
1221 | break; | |
1222 | case ORC_REG_R10: | |
1223 | cfa->base = CFI_R10; | |
1224 | break; | |
1225 | case ORC_REG_R13: | |
1226 | cfa->base = CFI_R13; | |
1227 | break; | |
1228 | case ORC_REG_DI: | |
1229 | cfa->base = CFI_DI; | |
1230 | break; | |
1231 | case ORC_REG_DX: | |
1232 | cfa->base = CFI_DX; | |
1233 | break; | |
1234 | default: | |
1235 | WARN_FUNC("unsupported unwind_hint sp base reg %d", | |
1236 | insn->sec, insn->offset, hint->sp_reg); | |
1237 | return -1; | |
1238 | } | |
1239 | ||
1240 | cfa->offset = hint->sp_offset; | |
1241 | insn->state.type = hint->type; | |
d31a5802 | 1242 | insn->state.end = hint->end; |
39358a03 JP |
1243 | } |
1244 | ||
1245 | return 0; | |
1246 | } | |
1247 | ||
b5bc2231 PZ |
1248 | static int read_retpoline_hints(struct objtool_file *file) |
1249 | { | |
63474dc4 | 1250 | struct section *sec; |
b5bc2231 PZ |
1251 | struct instruction *insn; |
1252 | struct rela *rela; | |
b5bc2231 | 1253 | |
63474dc4 | 1254 | sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe"); |
b5bc2231 PZ |
1255 | if (!sec) |
1256 | return 0; | |
1257 | ||
63474dc4 JP |
1258 | list_for_each_entry(rela, &sec->rela_list, list) { |
1259 | if (rela->sym->type != STT_SECTION) { | |
1260 | WARN("unexpected relocation symbol type in %s", sec->name); | |
b5bc2231 PZ |
1261 | return -1; |
1262 | } | |
1263 | ||
1264 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
1265 | if (!insn) { | |
63474dc4 | 1266 | WARN("bad .discard.retpoline_safe entry"); |
b5bc2231 PZ |
1267 | return -1; |
1268 | } | |
1269 | ||
1270 | if (insn->type != INSN_JUMP_DYNAMIC && | |
1271 | insn->type != INSN_CALL_DYNAMIC) { | |
63474dc4 | 1272 | WARN_FUNC("retpoline_safe hint not an indirect jump/call", |
b5bc2231 PZ |
1273 | insn->sec, insn->offset); |
1274 | return -1; | |
1275 | } | |
1276 | ||
1277 | insn->retpoline_safe = true; | |
1278 | } | |
1279 | ||
1280 | return 0; | |
1281 | } | |
1282 | ||
4a60aa05 AX |
1283 | static void mark_rodata(struct objtool_file *file) |
1284 | { | |
1285 | struct section *sec; | |
1286 | bool found = false; | |
1287 | ||
1288 | /* | |
87b512de JP |
1289 | * Search for the following rodata sections, each of which can |
1290 | * potentially contain jump tables: | |
1291 | * | |
1292 | * - .rodata: can contain GCC switch tables | |
1293 | * - .rodata.<func>: same, if -fdata-sections is being used | |
1294 | * - .rodata..c_jump_table: contains C annotated jump tables | |
1295 | * | |
1296 | * .rodata.str1.* sections are ignored; they don't contain jump tables. | |
4a60aa05 AX |
1297 | */ |
1298 | for_each_sec(file, sec) { | |
87b512de JP |
1299 | if ((!strncmp(sec->name, ".rodata", 7) && !strstr(sec->name, ".str1.")) || |
1300 | !strcmp(sec->name, C_JUMP_TABLE_SECTION)) { | |
4a60aa05 AX |
1301 | sec->rodata = true; |
1302 | found = true; | |
1303 | } | |
1304 | } | |
1305 | ||
1306 | file->rodata = found; | |
1307 | } | |
1308 | ||
dcc914f4 JP |
1309 | static int decode_sections(struct objtool_file *file) |
1310 | { | |
1311 | int ret; | |
1312 | ||
4a60aa05 AX |
1313 | mark_rodata(file); |
1314 | ||
dcc914f4 JP |
1315 | ret = decode_instructions(file); |
1316 | if (ret) | |
1317 | return ret; | |
1318 | ||
1319 | ret = add_dead_ends(file); | |
1320 | if (ret) | |
1321 | return ret; | |
1322 | ||
1323 | add_ignores(file); | |
ea24213d | 1324 | add_uaccess_safe(file); |
dcc914f4 | 1325 | |
ff05ab23 | 1326 | ret = add_ignore_alternatives(file); |
258c7605 JP |
1327 | if (ret) |
1328 | return ret; | |
1329 | ||
dcc914f4 JP |
1330 | ret = add_jump_destinations(file); |
1331 | if (ret) | |
1332 | return ret; | |
1333 | ||
a845c7cf | 1334 | ret = add_special_section_alts(file); |
dcc914f4 JP |
1335 | if (ret) |
1336 | return ret; | |
1337 | ||
a845c7cf | 1338 | ret = add_call_destinations(file); |
dcc914f4 JP |
1339 | if (ret) |
1340 | return ret; | |
1341 | ||
1342 | ret = add_switch_table_alts(file); | |
1343 | if (ret) | |
1344 | return ret; | |
1345 | ||
39358a03 JP |
1346 | ret = read_unwind_hints(file); |
1347 | if (ret) | |
1348 | return ret; | |
1349 | ||
b5bc2231 PZ |
1350 | ret = read_retpoline_hints(file); |
1351 | if (ret) | |
1352 | return ret; | |
1353 | ||
dcc914f4 JP |
1354 | return 0; |
1355 | } | |
1356 | ||
1357 | static bool is_fentry_call(struct instruction *insn) | |
1358 | { | |
1359 | if (insn->type == INSN_CALL && | |
1360 | insn->call_dest->type == STT_NOTYPE && | |
1361 | !strcmp(insn->call_dest->name, "__fentry__")) | |
1362 | return true; | |
1363 | ||
1364 | return false; | |
1365 | } | |
1366 | ||
baa41469 | 1367 | static bool has_modified_stack_frame(struct insn_state *state) |
dcc914f4 | 1368 | { |
baa41469 JP |
1369 | int i; |
1370 | ||
1371 | if (state->cfa.base != initial_func_cfi.cfa.base || | |
1372 | state->cfa.offset != initial_func_cfi.cfa.offset || | |
1373 | state->stack_size != initial_func_cfi.cfa.offset || | |
1374 | state->drap) | |
1375 | return true; | |
1376 | ||
1377 | for (i = 0; i < CFI_NUM_REGS; i++) | |
1378 | if (state->regs[i].base != initial_func_cfi.regs[i].base || | |
1379 | state->regs[i].offset != initial_func_cfi.regs[i].offset) | |
1380 | return true; | |
1381 | ||
1382 | return false; | |
1383 | } | |
1384 | ||
1385 | static bool has_valid_stack_frame(struct insn_state *state) | |
1386 | { | |
1387 | if (state->cfa.base == CFI_BP && state->regs[CFI_BP].base == CFI_CFA && | |
1388 | state->regs[CFI_BP].offset == -16) | |
1389 | return true; | |
1390 | ||
1391 | if (state->drap && state->regs[CFI_BP].base == CFI_BP) | |
1392 | return true; | |
1393 | ||
1394 | return false; | |
dcc914f4 JP |
1395 | } |
1396 | ||
627fce14 JP |
1397 | static int update_insn_state_regs(struct instruction *insn, struct insn_state *state) |
1398 | { | |
1399 | struct cfi_reg *cfa = &state->cfa; | |
1400 | struct stack_op *op = &insn->stack_op; | |
1401 | ||
1402 | if (cfa->base != CFI_SP) | |
1403 | return 0; | |
1404 | ||
1405 | /* push */ | |
ea24213d | 1406 | if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF) |
627fce14 JP |
1407 | cfa->offset += 8; |
1408 | ||
1409 | /* pop */ | |
ea24213d | 1410 | if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF) |
627fce14 JP |
1411 | cfa->offset -= 8; |
1412 | ||
1413 | /* add immediate to sp */ | |
1414 | if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD && | |
1415 | op->dest.reg == CFI_SP && op->src.reg == CFI_SP) | |
1416 | cfa->offset -= op->src.offset; | |
1417 | ||
1418 | return 0; | |
1419 | } | |
1420 | ||
baa41469 JP |
1421 | static void save_reg(struct insn_state *state, unsigned char reg, int base, |
1422 | int offset) | |
dcc914f4 | 1423 | { |
bf4d1a83 | 1424 | if (arch_callee_saved_reg(reg) && |
baa41469 JP |
1425 | state->regs[reg].base == CFI_UNDEFINED) { |
1426 | state->regs[reg].base = base; | |
1427 | state->regs[reg].offset = offset; | |
1428 | } | |
dcc914f4 JP |
1429 | } |
1430 | ||
baa41469 | 1431 | static void restore_reg(struct insn_state *state, unsigned char reg) |
dcc914f4 | 1432 | { |
baa41469 JP |
1433 | state->regs[reg].base = CFI_UNDEFINED; |
1434 | state->regs[reg].offset = 0; | |
1435 | } | |
1436 | ||
1437 | /* | |
1438 | * A note about DRAP stack alignment: | |
1439 | * | |
1440 | * GCC has the concept of a DRAP register, which is used to help keep track of | |
1441 | * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP | |
1442 | * register. The typical DRAP pattern is: | |
1443 | * | |
1444 | * 4c 8d 54 24 08 lea 0x8(%rsp),%r10 | |
1445 | * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp | |
1446 | * 41 ff 72 f8 pushq -0x8(%r10) | |
1447 | * 55 push %rbp | |
1448 | * 48 89 e5 mov %rsp,%rbp | |
1449 | * (more pushes) | |
1450 | * 41 52 push %r10 | |
1451 | * ... | |
1452 | * 41 5a pop %r10 | |
1453 | * (more pops) | |
1454 | * 5d pop %rbp | |
1455 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1456 | * c3 retq | |
1457 | * | |
1458 | * There are some variations in the epilogues, like: | |
1459 | * | |
1460 | * 5b pop %rbx | |
1461 | * 41 5a pop %r10 | |
1462 | * 41 5c pop %r12 | |
1463 | * 41 5d pop %r13 | |
1464 | * 41 5e pop %r14 | |
1465 | * c9 leaveq | |
1466 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1467 | * c3 retq | |
1468 | * | |
1469 | * and: | |
1470 | * | |
1471 | * 4c 8b 55 e8 mov -0x18(%rbp),%r10 | |
1472 | * 48 8b 5d e0 mov -0x20(%rbp),%rbx | |
1473 | * 4c 8b 65 f0 mov -0x10(%rbp),%r12 | |
1474 | * 4c 8b 6d f8 mov -0x8(%rbp),%r13 | |
1475 | * c9 leaveq | |
1476 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1477 | * c3 retq | |
1478 | * | |
1479 | * Sometimes r13 is used as the DRAP register, in which case it's saved and | |
1480 | * restored beforehand: | |
1481 | * | |
1482 | * 41 55 push %r13 | |
1483 | * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13 | |
1484 | * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp | |
1485 | * ... | |
1486 | * 49 8d 65 f0 lea -0x10(%r13),%rsp | |
1487 | * 41 5d pop %r13 | |
1488 | * c3 retq | |
1489 | */ | |
1490 | static int update_insn_state(struct instruction *insn, struct insn_state *state) | |
1491 | { | |
1492 | struct stack_op *op = &insn->stack_op; | |
1493 | struct cfi_reg *cfa = &state->cfa; | |
1494 | struct cfi_reg *regs = state->regs; | |
1495 | ||
1496 | /* stack operations don't make sense with an undefined CFA */ | |
1497 | if (cfa->base == CFI_UNDEFINED) { | |
1498 | if (insn->func) { | |
1499 | WARN_FUNC("undefined stack state", insn->sec, insn->offset); | |
1500 | return -1; | |
1501 | } | |
1502 | return 0; | |
1503 | } | |
1504 | ||
627fce14 JP |
1505 | if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET) |
1506 | return update_insn_state_regs(insn, state); | |
1507 | ||
baa41469 JP |
1508 | switch (op->dest.type) { |
1509 | ||
1510 | case OP_DEST_REG: | |
1511 | switch (op->src.type) { | |
1512 | ||
1513 | case OP_SRC_REG: | |
0d0970ee JP |
1514 | if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP && |
1515 | cfa->base == CFI_SP && | |
1516 | regs[CFI_BP].base == CFI_CFA && | |
1517 | regs[CFI_BP].offset == -cfa->offset) { | |
1518 | ||
1519 | /* mov %rsp, %rbp */ | |
1520 | cfa->base = op->dest.reg; | |
1521 | state->bp_scratch = false; | |
1522 | } | |
dd88a0a0 | 1523 | |
0d0970ee JP |
1524 | else if (op->src.reg == CFI_SP && |
1525 | op->dest.reg == CFI_BP && state->drap) { | |
dd88a0a0 | 1526 | |
0d0970ee JP |
1527 | /* drap: mov %rsp, %rbp */ |
1528 | regs[CFI_BP].base = CFI_BP; | |
1529 | regs[CFI_BP].offset = -state->stack_size; | |
1530 | state->bp_scratch = false; | |
1531 | } | |
dd88a0a0 | 1532 | |
0d0970ee JP |
1533 | else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
1534 | ||
1535 | /* | |
1536 | * mov %rsp, %reg | |
1537 | * | |
1538 | * This is needed for the rare case where GCC | |
1539 | * does: | |
1540 | * | |
1541 | * mov %rsp, %rax | |
1542 | * ... | |
1543 | * mov %rax, %rsp | |
1544 | */ | |
1545 | state->vals[op->dest.reg].base = CFI_CFA; | |
1546 | state->vals[op->dest.reg].offset = -state->stack_size; | |
dd88a0a0 JP |
1547 | } |
1548 | ||
3c1f0583 JP |
1549 | else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP && |
1550 | cfa->base == CFI_BP) { | |
1551 | ||
1552 | /* | |
1553 | * mov %rbp, %rsp | |
1554 | * | |
1555 | * Restore the original stack pointer (Clang). | |
1556 | */ | |
1557 | state->stack_size = -state->regs[CFI_BP].offset; | |
1558 | } | |
1559 | ||
dd88a0a0 JP |
1560 | else if (op->dest.reg == cfa->base) { |
1561 | ||
1562 | /* mov %reg, %rsp */ | |
1563 | if (cfa->base == CFI_SP && | |
1564 | state->vals[op->src.reg].base == CFI_CFA) { | |
1565 | ||
1566 | /* | |
1567 | * This is needed for the rare case | |
1568 | * where GCC does something dumb like: | |
1569 | * | |
1570 | * lea 0x8(%rsp), %rcx | |
1571 | * ... | |
1572 | * mov %rcx, %rsp | |
1573 | */ | |
1574 | cfa->offset = -state->vals[op->src.reg].offset; | |
1575 | state->stack_size = cfa->offset; | |
1576 | ||
1577 | } else { | |
1578 | cfa->base = CFI_UNDEFINED; | |
1579 | cfa->offset = 0; | |
1580 | } | |
baa41469 JP |
1581 | } |
1582 | ||
1583 | break; | |
1584 | ||
1585 | case OP_SRC_ADD: | |
1586 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) { | |
1587 | ||
1588 | /* add imm, %rsp */ | |
1589 | state->stack_size -= op->src.offset; | |
1590 | if (cfa->base == CFI_SP) | |
1591 | cfa->offset -= op->src.offset; | |
1592 | break; | |
1593 | } | |
1594 | ||
1595 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) { | |
1596 | ||
1597 | /* lea disp(%rbp), %rsp */ | |
1598 | state->stack_size = -(op->src.offset + regs[CFI_BP].offset); | |
1599 | break; | |
1600 | } | |
1601 | ||
dd88a0a0 | 1602 | if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
baa41469 JP |
1603 | |
1604 | /* drap: lea disp(%rsp), %drap */ | |
1605 | state->drap_reg = op->dest.reg; | |
dd88a0a0 JP |
1606 | |
1607 | /* | |
1608 | * lea disp(%rsp), %reg | |
1609 | * | |
1610 | * This is needed for the rare case where GCC | |
1611 | * does something dumb like: | |
1612 | * | |
1613 | * lea 0x8(%rsp), %rcx | |
1614 | * ... | |
1615 | * mov %rcx, %rsp | |
1616 | */ | |
1617 | state->vals[op->dest.reg].base = CFI_CFA; | |
1618 | state->vals[op->dest.reg].offset = \ | |
1619 | -state->stack_size + op->src.offset; | |
1620 | ||
baa41469 JP |
1621 | break; |
1622 | } | |
1623 | ||
1624 | if (state->drap && op->dest.reg == CFI_SP && | |
1625 | op->src.reg == state->drap_reg) { | |
1626 | ||
1627 | /* drap: lea disp(%drap), %rsp */ | |
1628 | cfa->base = CFI_SP; | |
1629 | cfa->offset = state->stack_size = -op->src.offset; | |
1630 | state->drap_reg = CFI_UNDEFINED; | |
1631 | state->drap = false; | |
1632 | break; | |
1633 | } | |
1634 | ||
1635 | if (op->dest.reg == state->cfa.base) { | |
1636 | WARN_FUNC("unsupported stack register modification", | |
1637 | insn->sec, insn->offset); | |
1638 | return -1; | |
1639 | } | |
1640 | ||
1641 | break; | |
1642 | ||
1643 | case OP_SRC_AND: | |
1644 | if (op->dest.reg != CFI_SP || | |
1645 | (state->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) || | |
1646 | (state->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) { | |
1647 | WARN_FUNC("unsupported stack pointer realignment", | |
1648 | insn->sec, insn->offset); | |
1649 | return -1; | |
1650 | } | |
1651 | ||
1652 | if (state->drap_reg != CFI_UNDEFINED) { | |
1653 | /* drap: and imm, %rsp */ | |
1654 | cfa->base = state->drap_reg; | |
1655 | cfa->offset = state->stack_size = 0; | |
1656 | state->drap = true; | |
baa41469 JP |
1657 | } |
1658 | ||
1659 | /* | |
1660 | * Older versions of GCC (4.8ish) realign the stack | |
1661 | * without DRAP, with a frame pointer. | |
1662 | */ | |
1663 | ||
1664 | break; | |
1665 | ||
1666 | case OP_SRC_POP: | |
ea24213d | 1667 | case OP_SRC_POPF: |
baa41469 JP |
1668 | if (!state->drap && op->dest.type == OP_DEST_REG && |
1669 | op->dest.reg == cfa->base) { | |
1670 | ||
1671 | /* pop %rbp */ | |
1672 | cfa->base = CFI_SP; | |
1673 | } | |
1674 | ||
bf4d1a83 JP |
1675 | if (state->drap && cfa->base == CFI_BP_INDIRECT && |
1676 | op->dest.type == OP_DEST_REG && | |
1677 | op->dest.reg == state->drap_reg && | |
1678 | state->drap_offset == -state->stack_size) { | |
baa41469 | 1679 | |
bf4d1a83 JP |
1680 | /* drap: pop %drap */ |
1681 | cfa->base = state->drap_reg; | |
1682 | cfa->offset = 0; | |
1683 | state->drap_offset = -1; | |
baa41469 | 1684 | |
bf4d1a83 | 1685 | } else if (regs[op->dest.reg].offset == -state->stack_size) { |
baa41469 | 1686 | |
bf4d1a83 | 1687 | /* pop %reg */ |
baa41469 JP |
1688 | restore_reg(state, op->dest.reg); |
1689 | } | |
1690 | ||
1691 | state->stack_size -= 8; | |
1692 | if (cfa->base == CFI_SP) | |
1693 | cfa->offset -= 8; | |
1694 | ||
1695 | break; | |
1696 | ||
1697 | case OP_SRC_REG_INDIRECT: | |
bf4d1a83 JP |
1698 | if (state->drap && op->src.reg == CFI_BP && |
1699 | op->src.offset == state->drap_offset) { | |
1700 | ||
1701 | /* drap: mov disp(%rbp), %drap */ | |
1702 | cfa->base = state->drap_reg; | |
1703 | cfa->offset = 0; | |
1704 | state->drap_offset = -1; | |
1705 | } | |
1706 | ||
baa41469 JP |
1707 | if (state->drap && op->src.reg == CFI_BP && |
1708 | op->src.offset == regs[op->dest.reg].offset) { | |
1709 | ||
1710 | /* drap: mov disp(%rbp), %reg */ | |
baa41469 JP |
1711 | restore_reg(state, op->dest.reg); |
1712 | ||
1713 | } else if (op->src.reg == cfa->base && | |
1714 | op->src.offset == regs[op->dest.reg].offset + cfa->offset) { | |
1715 | ||
1716 | /* mov disp(%rbp), %reg */ | |
1717 | /* mov disp(%rsp), %reg */ | |
1718 | restore_reg(state, op->dest.reg); | |
1719 | } | |
1720 | ||
1721 | break; | |
1722 | ||
1723 | default: | |
1724 | WARN_FUNC("unknown stack-related instruction", | |
1725 | insn->sec, insn->offset); | |
1726 | return -1; | |
1727 | } | |
1728 | ||
1729 | break; | |
1730 | ||
1731 | case OP_DEST_PUSH: | |
ea24213d | 1732 | case OP_DEST_PUSHF: |
baa41469 JP |
1733 | state->stack_size += 8; |
1734 | if (cfa->base == CFI_SP) | |
1735 | cfa->offset += 8; | |
1736 | ||
1737 | if (op->src.type != OP_SRC_REG) | |
1738 | break; | |
1739 | ||
1740 | if (state->drap) { | |
1741 | if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) { | |
1742 | ||
1743 | /* drap: push %drap */ | |
1744 | cfa->base = CFI_BP_INDIRECT; | |
1745 | cfa->offset = -state->stack_size; | |
1746 | ||
bf4d1a83 JP |
1747 | /* save drap so we know when to restore it */ |
1748 | state->drap_offset = -state->stack_size; | |
baa41469 JP |
1749 | |
1750 | } else if (op->src.reg == CFI_BP && cfa->base == state->drap_reg) { | |
1751 | ||
1752 | /* drap: push %rbp */ | |
1753 | state->stack_size = 0; | |
1754 | ||
1755 | } else if (regs[op->src.reg].base == CFI_UNDEFINED) { | |
1756 | ||
1757 | /* drap: push %reg */ | |
1758 | save_reg(state, op->src.reg, CFI_BP, -state->stack_size); | |
1759 | } | |
1760 | ||
1761 | } else { | |
1762 | ||
1763 | /* push %reg */ | |
1764 | save_reg(state, op->src.reg, CFI_CFA, -state->stack_size); | |
1765 | } | |
1766 | ||
1767 | /* detect when asm code uses rbp as a scratch register */ | |
867ac9d7 | 1768 | if (!no_fp && insn->func && op->src.reg == CFI_BP && |
baa41469 JP |
1769 | cfa->base != CFI_BP) |
1770 | state->bp_scratch = true; | |
1771 | break; | |
1772 | ||
1773 | case OP_DEST_REG_INDIRECT: | |
1774 | ||
1775 | if (state->drap) { | |
1776 | if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) { | |
1777 | ||
1778 | /* drap: mov %drap, disp(%rbp) */ | |
1779 | cfa->base = CFI_BP_INDIRECT; | |
1780 | cfa->offset = op->dest.offset; | |
1781 | ||
bf4d1a83 JP |
1782 | /* save drap offset so we know when to restore it */ |
1783 | state->drap_offset = op->dest.offset; | |
baa41469 JP |
1784 | } |
1785 | ||
1786 | else if (regs[op->src.reg].base == CFI_UNDEFINED) { | |
1787 | ||
1788 | /* drap: mov reg, disp(%rbp) */ | |
1789 | save_reg(state, op->src.reg, CFI_BP, op->dest.offset); | |
1790 | } | |
1791 | ||
1792 | } else if (op->dest.reg == cfa->base) { | |
1793 | ||
1794 | /* mov reg, disp(%rbp) */ | |
1795 | /* mov reg, disp(%rsp) */ | |
1796 | save_reg(state, op->src.reg, CFI_CFA, | |
1797 | op->dest.offset - state->cfa.offset); | |
1798 | } | |
1799 | ||
1800 | break; | |
1801 | ||
1802 | case OP_DEST_LEAVE: | |
1803 | if ((!state->drap && cfa->base != CFI_BP) || | |
1804 | (state->drap && cfa->base != state->drap_reg)) { | |
1805 | WARN_FUNC("leave instruction with modified stack frame", | |
1806 | insn->sec, insn->offset); | |
1807 | return -1; | |
1808 | } | |
1809 | ||
1810 | /* leave (mov %rbp, %rsp; pop %rbp) */ | |
1811 | ||
1812 | state->stack_size = -state->regs[CFI_BP].offset - 8; | |
1813 | restore_reg(state, CFI_BP); | |
1814 | ||
1815 | if (!state->drap) { | |
1816 | cfa->base = CFI_SP; | |
1817 | cfa->offset -= 8; | |
1818 | } | |
1819 | ||
1820 | break; | |
1821 | ||
1822 | case OP_DEST_MEM: | |
ea24213d | 1823 | if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) { |
baa41469 JP |
1824 | WARN_FUNC("unknown stack-related memory operation", |
1825 | insn->sec, insn->offset); | |
1826 | return -1; | |
1827 | } | |
1828 | ||
1829 | /* pop mem */ | |
1830 | state->stack_size -= 8; | |
1831 | if (cfa->base == CFI_SP) | |
1832 | cfa->offset -= 8; | |
1833 | ||
1834 | break; | |
1835 | ||
1836 | default: | |
1837 | WARN_FUNC("unknown stack-related instruction", | |
1838 | insn->sec, insn->offset); | |
1839 | return -1; | |
1840 | } | |
1841 | ||
1842 | return 0; | |
1843 | } | |
1844 | ||
1845 | static bool insn_state_match(struct instruction *insn, struct insn_state *state) | |
1846 | { | |
1847 | struct insn_state *state1 = &insn->state, *state2 = state; | |
1848 | int i; | |
1849 | ||
1850 | if (memcmp(&state1->cfa, &state2->cfa, sizeof(state1->cfa))) { | |
1851 | WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d", | |
1852 | insn->sec, insn->offset, | |
1853 | state1->cfa.base, state1->cfa.offset, | |
1854 | state2->cfa.base, state2->cfa.offset); | |
1855 | ||
1856 | } else if (memcmp(&state1->regs, &state2->regs, sizeof(state1->regs))) { | |
1857 | for (i = 0; i < CFI_NUM_REGS; i++) { | |
1858 | if (!memcmp(&state1->regs[i], &state2->regs[i], | |
1859 | sizeof(struct cfi_reg))) | |
1860 | continue; | |
1861 | ||
1862 | WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d", | |
1863 | insn->sec, insn->offset, | |
1864 | i, state1->regs[i].base, state1->regs[i].offset, | |
1865 | i, state2->regs[i].base, state2->regs[i].offset); | |
1866 | break; | |
1867 | } | |
1868 | ||
627fce14 JP |
1869 | } else if (state1->type != state2->type) { |
1870 | WARN_FUNC("stack state mismatch: type1=%d type2=%d", | |
1871 | insn->sec, insn->offset, state1->type, state2->type); | |
1872 | ||
baa41469 | 1873 | } else if (state1->drap != state2->drap || |
bf4d1a83 JP |
1874 | (state1->drap && state1->drap_reg != state2->drap_reg) || |
1875 | (state1->drap && state1->drap_offset != state2->drap_offset)) { | |
1876 | WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)", | |
baa41469 | 1877 | insn->sec, insn->offset, |
bf4d1a83 JP |
1878 | state1->drap, state1->drap_reg, state1->drap_offset, |
1879 | state2->drap, state2->drap_reg, state2->drap_offset); | |
baa41469 JP |
1880 | |
1881 | } else | |
1882 | return true; | |
1883 | ||
1884 | return false; | |
dcc914f4 JP |
1885 | } |
1886 | ||
ea24213d PZ |
1887 | static inline bool func_uaccess_safe(struct symbol *func) |
1888 | { | |
1889 | if (func) | |
1890 | return func->alias->uaccess_safe; | |
1891 | ||
1892 | return false; | |
1893 | } | |
1894 | ||
1895 | static inline const char *insn_dest_name(struct instruction *insn) | |
1896 | { | |
1897 | if (insn->call_dest) | |
1898 | return insn->call_dest->name; | |
1899 | ||
1900 | return "{dynamic}"; | |
1901 | } | |
1902 | ||
1903 | static int validate_call(struct instruction *insn, struct insn_state *state) | |
1904 | { | |
1905 | if (state->uaccess && !func_uaccess_safe(insn->call_dest)) { | |
1906 | WARN_FUNC("call to %s() with UACCESS enabled", | |
1907 | insn->sec, insn->offset, insn_dest_name(insn)); | |
1908 | return 1; | |
1909 | } | |
1910 | ||
2f0f9e9a PZ |
1911 | if (state->df) { |
1912 | WARN_FUNC("call to %s() with DF set", | |
1913 | insn->sec, insn->offset, insn_dest_name(insn)); | |
1914 | return 1; | |
1915 | } | |
1916 | ||
ea24213d PZ |
1917 | return 0; |
1918 | } | |
1919 | ||
54262aa2 PZ |
1920 | static int validate_sibling_call(struct instruction *insn, struct insn_state *state) |
1921 | { | |
1922 | if (has_modified_stack_frame(state)) { | |
1923 | WARN_FUNC("sibling call from callable instruction with modified stack frame", | |
1924 | insn->sec, insn->offset); | |
1925 | return 1; | |
1926 | } | |
1927 | ||
ea24213d | 1928 | return validate_call(insn, state); |
54262aa2 PZ |
1929 | } |
1930 | ||
dcc914f4 JP |
1931 | /* |
1932 | * Follow the branch starting at the given instruction, and recursively follow | |
1933 | * any other branches (jumps). Meanwhile, track the frame pointer state at | |
1934 | * each instruction and validate all the rules described in | |
1935 | * tools/objtool/Documentation/stack-validation.txt. | |
1936 | */ | |
c705cecc JP |
1937 | static int validate_branch(struct objtool_file *file, struct symbol *func, |
1938 | struct instruction *first, struct insn_state state) | |
dcc914f4 JP |
1939 | { |
1940 | struct alternative *alt; | |
39358a03 | 1941 | struct instruction *insn, *next_insn; |
dcc914f4 | 1942 | struct section *sec; |
dcc914f4 JP |
1943 | int ret; |
1944 | ||
1945 | insn = first; | |
1946 | sec = insn->sec; | |
dcc914f4 JP |
1947 | |
1948 | if (insn->alt_group && list_empty(&insn->alts)) { | |
1949 | WARN_FUNC("don't know how to handle branch to middle of alternative instruction group", | |
1950 | sec, insn->offset); | |
12b25729 | 1951 | return 1; |
dcc914f4 JP |
1952 | } |
1953 | ||
1954 | while (1) { | |
39358a03 JP |
1955 | next_insn = next_insn_same_sec(file, insn); |
1956 | ||
13810435 | 1957 | if (file->c_file && func && insn->func && func != insn->func->pfunc) { |
ee97638b JP |
1958 | WARN("%s() falls through to next function %s()", |
1959 | func->name, insn->func->name); | |
1960 | return 1; | |
dcc914f4 JP |
1961 | } |
1962 | ||
4855022a JP |
1963 | if (func && insn->ignore) { |
1964 | WARN_FUNC("BUG: why am I validating an ignored function?", | |
1965 | sec, insn->offset); | |
12b25729 | 1966 | return 1; |
4855022a JP |
1967 | } |
1968 | ||
dcc914f4 | 1969 | if (insn->visited) { |
39358a03 | 1970 | if (!insn->hint && !insn_state_match(insn, &state)) |
dcc914f4 | 1971 | return 1; |
dcc914f4 | 1972 | |
ea24213d PZ |
1973 | /* If we were here with AC=0, but now have AC=1, go again */ |
1974 | if (insn->state.uaccess || !state.uaccess) | |
1975 | return 0; | |
dcc914f4 JP |
1976 | } |
1977 | ||
39358a03 JP |
1978 | if (insn->hint) { |
1979 | if (insn->restore) { | |
1980 | struct instruction *save_insn, *i; | |
1981 | ||
1982 | i = insn; | |
1983 | save_insn = NULL; | |
c705cecc | 1984 | func_for_each_insn_continue_reverse(file, func, i) { |
39358a03 JP |
1985 | if (i->save) { |
1986 | save_insn = i; | |
1987 | break; | |
1988 | } | |
1989 | } | |
1990 | ||
1991 | if (!save_insn) { | |
1992 | WARN_FUNC("no corresponding CFI save for CFI restore", | |
1993 | sec, insn->offset); | |
1994 | return 1; | |
1995 | } | |
1996 | ||
1997 | if (!save_insn->visited) { | |
1998 | /* | |
1999 | * Oops, no state to copy yet. | |
2000 | * Hopefully we can reach this | |
2001 | * instruction from another branch | |
2002 | * after the save insn has been | |
2003 | * visited. | |
2004 | */ | |
2005 | if (insn == first) | |
2006 | return 0; | |
2007 | ||
2008 | WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo", | |
2009 | sec, insn->offset); | |
2010 | return 1; | |
2011 | } | |
2012 | ||
2013 | insn->state = save_insn->state; | |
2014 | } | |
2015 | ||
2016 | state = insn->state; | |
2017 | ||
2018 | } else | |
2019 | insn->state = state; | |
dcc914f4 | 2020 | |
baa41469 JP |
2021 | insn->visited = true; |
2022 | ||
a845c7cf | 2023 | if (!insn->ignore_alts) { |
764eef4b PZ |
2024 | bool skip_orig = false; |
2025 | ||
a845c7cf | 2026 | list_for_each_entry(alt, &insn->alts, list) { |
764eef4b PZ |
2027 | if (alt->skip_orig) |
2028 | skip_orig = true; | |
2029 | ||
c705cecc | 2030 | ret = validate_branch(file, func, alt->insn, state); |
7697eee3 PZ |
2031 | if (ret) { |
2032 | if (backtrace) | |
2033 | BT_FUNC("(alt)", insn); | |
2034 | return ret; | |
2035 | } | |
a845c7cf | 2036 | } |
764eef4b PZ |
2037 | |
2038 | if (skip_orig) | |
2039 | return 0; | |
dcc914f4 JP |
2040 | } |
2041 | ||
2042 | switch (insn->type) { | |
2043 | ||
dcc914f4 | 2044 | case INSN_RETURN: |
ea24213d PZ |
2045 | if (state.uaccess && !func_uaccess_safe(func)) { |
2046 | WARN_FUNC("return with UACCESS enabled", sec, insn->offset); | |
2047 | return 1; | |
2048 | } | |
2049 | ||
2050 | if (!state.uaccess && func_uaccess_safe(func)) { | |
2051 | WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function", sec, insn->offset); | |
2052 | return 1; | |
2053 | } | |
2054 | ||
2f0f9e9a PZ |
2055 | if (state.df) { |
2056 | WARN_FUNC("return with DF set", sec, insn->offset); | |
2057 | return 1; | |
2058 | } | |
2059 | ||
baa41469 JP |
2060 | if (func && has_modified_stack_frame(&state)) { |
2061 | WARN_FUNC("return with modified stack frame", | |
dcc914f4 JP |
2062 | sec, insn->offset); |
2063 | return 1; | |
2064 | } | |
baa41469 JP |
2065 | |
2066 | if (state.bp_scratch) { | |
2067 | WARN("%s uses BP as a scratch register", | |
c705cecc | 2068 | func->name); |
baa41469 JP |
2069 | return 1; |
2070 | } | |
2071 | ||
dcc914f4 JP |
2072 | return 0; |
2073 | ||
2074 | case INSN_CALL: | |
ea24213d PZ |
2075 | case INSN_CALL_DYNAMIC: |
2076 | ret = validate_call(insn, &state); | |
2077 | if (ret) | |
2078 | return ret; | |
dcc914f4 | 2079 | |
ea24213d PZ |
2080 | if (insn->type == INSN_CALL) { |
2081 | if (is_fentry_call(insn)) | |
2082 | break; | |
2083 | ||
2084 | ret = dead_end_function(file, insn->call_dest); | |
2085 | if (ret == 1) | |
2086 | return 0; | |
2087 | if (ret == -1) | |
2088 | return 1; | |
2089 | } | |
dcc914f4 | 2090 | |
867ac9d7 | 2091 | if (!no_fp && func && !has_valid_stack_frame(&state)) { |
dcc914f4 JP |
2092 | WARN_FUNC("call without frame pointer save/setup", |
2093 | sec, insn->offset); | |
2094 | return 1; | |
2095 | } | |
2096 | break; | |
2097 | ||
2098 | case INSN_JUMP_CONDITIONAL: | |
2099 | case INSN_JUMP_UNCONDITIONAL: | |
54262aa2 PZ |
2100 | if (func && !insn->jump_dest) { |
2101 | ret = validate_sibling_call(insn, &state); | |
dcc914f4 | 2102 | if (ret) |
54262aa2 | 2103 | return ret; |
4855022a | 2104 | |
54262aa2 PZ |
2105 | } else if (insn->jump_dest && |
2106 | (!func || !insn->jump_dest->func || | |
2107 | insn->jump_dest->func->pfunc == func)) { | |
c705cecc JP |
2108 | ret = validate_branch(file, func, |
2109 | insn->jump_dest, state); | |
7697eee3 PZ |
2110 | if (ret) { |
2111 | if (backtrace) | |
2112 | BT_FUNC("(branch)", insn); | |
2113 | return ret; | |
2114 | } | |
4855022a | 2115 | } |
dcc914f4 JP |
2116 | |
2117 | if (insn->type == INSN_JUMP_UNCONDITIONAL) | |
2118 | return 0; | |
2119 | ||
2120 | break; | |
2121 | ||
2122 | case INSN_JUMP_DYNAMIC: | |
54262aa2 PZ |
2123 | if (func && list_empty(&insn->alts)) { |
2124 | ret = validate_sibling_call(insn, &state); | |
2125 | if (ret) | |
2126 | return ret; | |
dcc914f4 JP |
2127 | } |
2128 | ||
2129 | return 0; | |
2130 | ||
39358a03 JP |
2131 | case INSN_CONTEXT_SWITCH: |
2132 | if (func && (!next_insn || !next_insn->hint)) { | |
2133 | WARN_FUNC("unsupported instruction in callable function", | |
2134 | sec, insn->offset); | |
2135 | return 1; | |
2136 | } | |
2137 | return 0; | |
2138 | ||
baa41469 JP |
2139 | case INSN_STACK: |
2140 | if (update_insn_state(insn, &state)) | |
12b25729 | 2141 | return 1; |
baa41469 | 2142 | |
ea24213d PZ |
2143 | if (insn->stack_op.dest.type == OP_DEST_PUSHF) { |
2144 | if (!state.uaccess_stack) { | |
2145 | state.uaccess_stack = 1; | |
2146 | } else if (state.uaccess_stack >> 31) { | |
2147 | WARN_FUNC("PUSHF stack exhausted", sec, insn->offset); | |
2148 | return 1; | |
2149 | } | |
2150 | state.uaccess_stack <<= 1; | |
2151 | state.uaccess_stack |= state.uaccess; | |
2152 | } | |
2153 | ||
2154 | if (insn->stack_op.src.type == OP_SRC_POPF) { | |
2155 | if (state.uaccess_stack) { | |
2156 | state.uaccess = state.uaccess_stack & 1; | |
2157 | state.uaccess_stack >>= 1; | |
2158 | if (state.uaccess_stack == 1) | |
2159 | state.uaccess_stack = 0; | |
2160 | } | |
2161 | } | |
2162 | ||
2163 | break; | |
2164 | ||
2165 | case INSN_STAC: | |
2166 | if (state.uaccess) { | |
2167 | WARN_FUNC("recursive UACCESS enable", sec, insn->offset); | |
2168 | return 1; | |
2169 | } | |
2170 | ||
2171 | state.uaccess = true; | |
2172 | break; | |
2173 | ||
2174 | case INSN_CLAC: | |
c705cecc | 2175 | if (!state.uaccess && func) { |
ea24213d PZ |
2176 | WARN_FUNC("redundant UACCESS disable", sec, insn->offset); |
2177 | return 1; | |
2178 | } | |
2179 | ||
2180 | if (func_uaccess_safe(func) && !state.uaccess_stack) { | |
2181 | WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset); | |
2182 | return 1; | |
2183 | } | |
2184 | ||
2185 | state.uaccess = false; | |
baa41469 JP |
2186 | break; |
2187 | ||
2f0f9e9a PZ |
2188 | case INSN_STD: |
2189 | if (state.df) | |
2190 | WARN_FUNC("recursive STD", sec, insn->offset); | |
2191 | ||
2192 | state.df = true; | |
2193 | break; | |
2194 | ||
2195 | case INSN_CLD: | |
c705cecc | 2196 | if (!state.df && func) |
2f0f9e9a PZ |
2197 | WARN_FUNC("redundant CLD", sec, insn->offset); |
2198 | ||
2199 | state.df = false; | |
baa41469 JP |
2200 | break; |
2201 | ||
dcc914f4 JP |
2202 | default: |
2203 | break; | |
2204 | } | |
2205 | ||
2206 | if (insn->dead_end) | |
2207 | return 0; | |
2208 | ||
00d96180 JP |
2209 | if (!next_insn) { |
2210 | if (state.cfa.base == CFI_UNDEFINED) | |
2211 | return 0; | |
dcc914f4 JP |
2212 | WARN("%s: unexpected end of section", sec->name); |
2213 | return 1; | |
2214 | } | |
00d96180 JP |
2215 | |
2216 | insn = next_insn; | |
dcc914f4 JP |
2217 | } |
2218 | ||
2219 | return 0; | |
2220 | } | |
2221 | ||
39358a03 JP |
2222 | static int validate_unwind_hints(struct objtool_file *file) |
2223 | { | |
2224 | struct instruction *insn; | |
2225 | int ret, warnings = 0; | |
2226 | struct insn_state state; | |
2227 | ||
2228 | if (!file->hints) | |
2229 | return 0; | |
2230 | ||
2231 | clear_insn_state(&state); | |
2232 | ||
2233 | for_each_insn(file, insn) { | |
2234 | if (insn->hint && !insn->visited) { | |
c705cecc | 2235 | ret = validate_branch(file, insn->func, insn, state); |
7697eee3 PZ |
2236 | if (ret && backtrace) |
2237 | BT_FUNC("<=== (hint)", insn); | |
39358a03 JP |
2238 | warnings += ret; |
2239 | } | |
2240 | } | |
2241 | ||
2242 | return warnings; | |
2243 | } | |
2244 | ||
b5bc2231 PZ |
2245 | static int validate_retpoline(struct objtool_file *file) |
2246 | { | |
2247 | struct instruction *insn; | |
2248 | int warnings = 0; | |
2249 | ||
2250 | for_each_insn(file, insn) { | |
2251 | if (insn->type != INSN_JUMP_DYNAMIC && | |
2252 | insn->type != INSN_CALL_DYNAMIC) | |
2253 | continue; | |
2254 | ||
2255 | if (insn->retpoline_safe) | |
2256 | continue; | |
2257 | ||
ca41b97e PZ |
2258 | /* |
2259 | * .init.text code is ran before userspace and thus doesn't | |
2260 | * strictly need retpolines, except for modules which are | |
2261 | * loaded late, they very much do need retpoline in their | |
2262 | * .init.text | |
2263 | */ | |
2264 | if (!strcmp(insn->sec->name, ".init.text") && !module) | |
2265 | continue; | |
2266 | ||
b5bc2231 PZ |
2267 | WARN_FUNC("indirect %s found in RETPOLINE build", |
2268 | insn->sec, insn->offset, | |
2269 | insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); | |
2270 | ||
2271 | warnings++; | |
2272 | } | |
2273 | ||
2274 | return warnings; | |
2275 | } | |
2276 | ||
dcc914f4 JP |
2277 | static bool is_kasan_insn(struct instruction *insn) |
2278 | { | |
2279 | return (insn->type == INSN_CALL && | |
2280 | !strcmp(insn->call_dest->name, "__asan_handle_no_return")); | |
2281 | } | |
2282 | ||
2283 | static bool is_ubsan_insn(struct instruction *insn) | |
2284 | { | |
2285 | return (insn->type == INSN_CALL && | |
2286 | !strcmp(insn->call_dest->name, | |
2287 | "__ubsan_handle_builtin_unreachable")); | |
2288 | } | |
2289 | ||
baa41469 | 2290 | static bool ignore_unreachable_insn(struct instruction *insn) |
dcc914f4 JP |
2291 | { |
2292 | int i; | |
2293 | ||
baa41469 JP |
2294 | if (insn->ignore || insn->type == INSN_NOP) |
2295 | return true; | |
2296 | ||
2297 | /* | |
2298 | * Ignore any unused exceptions. This can happen when a whitelisted | |
2299 | * function has an exception table entry. | |
0e2bb2bc JP |
2300 | * |
2301 | * Also ignore alternative replacement instructions. This can happen | |
2302 | * when a whitelisted function uses one of the ALTERNATIVE macros. | |
baa41469 | 2303 | */ |
0e2bb2bc JP |
2304 | if (!strcmp(insn->sec->name, ".fixup") || |
2305 | !strcmp(insn->sec->name, ".altinstr_replacement") || | |
2306 | !strcmp(insn->sec->name, ".altinstr_aux")) | |
dcc914f4 JP |
2307 | return true; |
2308 | ||
2309 | /* | |
2310 | * Check if this (or a subsequent) instruction is related to | |
2311 | * CONFIG_UBSAN or CONFIG_KASAN. | |
2312 | * | |
2313 | * End the search at 5 instructions to avoid going into the weeds. | |
2314 | */ | |
baa41469 JP |
2315 | if (!insn->func) |
2316 | return false; | |
dcc914f4 JP |
2317 | for (i = 0; i < 5; i++) { |
2318 | ||
2319 | if (is_kasan_insn(insn) || is_ubsan_insn(insn)) | |
2320 | return true; | |
2321 | ||
fe24e271 JP |
2322 | if (insn->type == INSN_JUMP_UNCONDITIONAL) { |
2323 | if (insn->jump_dest && | |
2324 | insn->jump_dest->func == insn->func) { | |
2325 | insn = insn->jump_dest; | |
2326 | continue; | |
2327 | } | |
2328 | ||
2329 | break; | |
dcc914f4 JP |
2330 | } |
2331 | ||
baa41469 | 2332 | if (insn->offset + insn->len >= insn->func->offset + insn->func->len) |
dcc914f4 | 2333 | break; |
fe24e271 | 2334 | |
dcc914f4 JP |
2335 | insn = list_next_entry(insn, list); |
2336 | } | |
2337 | ||
2338 | return false; | |
2339 | } | |
2340 | ||
2341 | static int validate_functions(struct objtool_file *file) | |
2342 | { | |
2343 | struct section *sec; | |
2344 | struct symbol *func; | |
2345 | struct instruction *insn; | |
baa41469 | 2346 | struct insn_state state; |
dcc914f4 JP |
2347 | int ret, warnings = 0; |
2348 | ||
baa41469 JP |
2349 | clear_insn_state(&state); |
2350 | ||
2351 | state.cfa = initial_func_cfi.cfa; | |
2352 | memcpy(&state.regs, &initial_func_cfi.regs, | |
2353 | CFI_NUM_REGS * sizeof(struct cfi_reg)); | |
2354 | state.stack_size = initial_func_cfi.cfa.offset; | |
2355 | ||
2356 | for_each_sec(file, sec) { | |
dcc914f4 | 2357 | list_for_each_entry(func, &sec->symbol_list, list) { |
13810435 | 2358 | if (func->type != STT_FUNC || func->pfunc != func) |
dcc914f4 JP |
2359 | continue; |
2360 | ||
2361 | insn = find_insn(file, sec, func->offset); | |
c705cecc | 2362 | if (!insn || insn->ignore || insn->visited) |
dcc914f4 JP |
2363 | continue; |
2364 | ||
ea24213d PZ |
2365 | state.uaccess = func->alias->uaccess_safe; |
2366 | ||
c705cecc | 2367 | ret = validate_branch(file, func, insn, state); |
7697eee3 PZ |
2368 | if (ret && backtrace) |
2369 | BT_FUNC("<=== (func)", insn); | |
dcc914f4 JP |
2370 | warnings += ret; |
2371 | } | |
2372 | } | |
2373 | ||
dcc914f4 JP |
2374 | return warnings; |
2375 | } | |
2376 | ||
baa41469 | 2377 | static int validate_reachable_instructions(struct objtool_file *file) |
dcc914f4 JP |
2378 | { |
2379 | struct instruction *insn; | |
baa41469 JP |
2380 | |
2381 | if (file->ignore_unreachables) | |
2382 | return 0; | |
dcc914f4 JP |
2383 | |
2384 | for_each_insn(file, insn) { | |
baa41469 JP |
2385 | if (insn->visited || ignore_unreachable_insn(insn)) |
2386 | continue; | |
2387 | ||
baa41469 JP |
2388 | WARN_FUNC("unreachable instruction", insn->sec, insn->offset); |
2389 | return 1; | |
dcc914f4 JP |
2390 | } |
2391 | ||
baa41469 | 2392 | return 0; |
dcc914f4 JP |
2393 | } |
2394 | ||
2395 | static void cleanup(struct objtool_file *file) | |
2396 | { | |
2397 | struct instruction *insn, *tmpinsn; | |
2398 | struct alternative *alt, *tmpalt; | |
2399 | ||
2400 | list_for_each_entry_safe(insn, tmpinsn, &file->insn_list, list) { | |
2401 | list_for_each_entry_safe(alt, tmpalt, &insn->alts, list) { | |
2402 | list_del(&alt->list); | |
2403 | free(alt); | |
2404 | } | |
2405 | list_del(&insn->list); | |
2406 | hash_del(&insn->hash); | |
2407 | free(insn); | |
2408 | } | |
2409 | elf_close(file->elf); | |
2410 | } | |
2411 | ||
0c671812 JP |
2412 | static struct objtool_file file; |
2413 | ||
43a4525f | 2414 | int check(const char *_objname, bool orc) |
dcc914f4 | 2415 | { |
dcc914f4 JP |
2416 | int ret, warnings = 0; |
2417 | ||
2418 | objname = _objname; | |
dcc914f4 | 2419 | |
8e144797 | 2420 | file.elf = elf_read(objname, orc ? O_RDWR : O_RDONLY); |
baa41469 | 2421 | if (!file.elf) |
dcc914f4 | 2422 | return 1; |
dcc914f4 JP |
2423 | |
2424 | INIT_LIST_HEAD(&file.insn_list); | |
2425 | hash_init(file.insn_hash); | |
dcc914f4 | 2426 | file.c_file = find_section_by_name(file.elf, ".comment"); |
867ac9d7 | 2427 | file.ignore_unreachables = no_unreachable; |
39358a03 | 2428 | file.hints = false; |
dcc914f4 | 2429 | |
baa41469 JP |
2430 | arch_initial_func_cfi_state(&initial_func_cfi); |
2431 | ||
dcc914f4 JP |
2432 | ret = decode_sections(&file); |
2433 | if (ret < 0) | |
2434 | goto out; | |
2435 | warnings += ret; | |
2436 | ||
baa41469 | 2437 | if (list_empty(&file.insn_list)) |
dcc914f4 | 2438 | goto out; |
dcc914f4 | 2439 | |
b5bc2231 PZ |
2440 | if (retpoline) { |
2441 | ret = validate_retpoline(&file); | |
2442 | if (ret < 0) | |
2443 | return ret; | |
2444 | warnings += ret; | |
2445 | } | |
2446 | ||
baa41469 | 2447 | ret = validate_functions(&file); |
dcc914f4 JP |
2448 | if (ret < 0) |
2449 | goto out; | |
2450 | warnings += ret; | |
2451 | ||
39358a03 JP |
2452 | ret = validate_unwind_hints(&file); |
2453 | if (ret < 0) | |
2454 | goto out; | |
2455 | warnings += ret; | |
2456 | ||
baa41469 JP |
2457 | if (!warnings) { |
2458 | ret = validate_reachable_instructions(&file); | |
2459 | if (ret < 0) | |
2460 | goto out; | |
2461 | warnings += ret; | |
2462 | } | |
2463 | ||
627fce14 JP |
2464 | if (orc) { |
2465 | ret = create_orc(&file); | |
2466 | if (ret < 0) | |
2467 | goto out; | |
2468 | ||
2469 | ret = create_orc_sections(&file); | |
2470 | if (ret < 0) | |
2471 | goto out; | |
2472 | ||
2473 | ret = elf_write(file.elf); | |
2474 | if (ret < 0) | |
2475 | goto out; | |
2476 | } | |
2477 | ||
dcc914f4 JP |
2478 | out: |
2479 | cleanup(&file); | |
2480 | ||
2481 | /* ignore warnings for now until we get all the code cleaned up */ | |
2482 | if (ret || warnings) | |
2483 | return 0; | |
2484 | return 0; | |
2485 | } |