]>
Commit | Line | Data |
---|---|---|
442f04c3 JP |
1 | /* |
2 | * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation; either version 2 | |
7 | * of the License, or (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, see <http://www.gnu.org/licenses/>. | |
16 | */ | |
17 | ||
18 | /* | |
19 | * objtool check: | |
20 | * | |
21 | * This command analyzes every .o file and ensures the validity of its stack | |
22 | * trace metadata. It enforces a set of rules on asm code and C inline | |
23 | * assembly code so that stack traces can be reliable. | |
24 | * | |
25 | * For more information, see tools/objtool/Documentation/stack-validation.txt. | |
26 | */ | |
27 | ||
28 | #include <string.h> | |
d0761e37 | 29 | #include <stdlib.h> |
442f04c3 JP |
30 | #include <subcmd/parse-options.h> |
31 | ||
32 | #include "builtin.h" | |
33 | #include "elf.h" | |
34 | #include "special.h" | |
35 | #include "arch.h" | |
36 | #include "warn.h" | |
37 | ||
042ba73f JP |
38 | #include <linux/hashtable.h> |
39 | ||
442f04c3 JP |
40 | #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) |
41 | ||
42 | #define STATE_FP_SAVED 0x1 | |
43 | #define STATE_FP_SETUP 0x2 | |
44 | #define STATE_FENTRY 0x4 | |
45 | ||
46 | struct instruction { | |
47 | struct list_head list; | |
042ba73f | 48 | struct hlist_node hash; |
442f04c3 JP |
49 | struct section *sec; |
50 | unsigned long offset; | |
51 | unsigned int len, state; | |
52 | unsigned char type; | |
53 | unsigned long immediate; | |
d1091c7f | 54 | bool alt_group, visited, dead_end; |
442f04c3 JP |
55 | struct symbol *call_dest; |
56 | struct instruction *jump_dest; | |
57 | struct list_head alts; | |
b1547d31 | 58 | struct symbol *func; |
442f04c3 JP |
59 | }; |
60 | ||
61 | struct alternative { | |
62 | struct list_head list; | |
63 | struct instruction *insn; | |
64 | }; | |
65 | ||
66 | struct objtool_file { | |
67 | struct elf *elf; | |
a196e171 | 68 | struct list_head insn_list; |
042ba73f JP |
69 | DECLARE_HASHTABLE(insn_hash, 16); |
70 | struct section *rodata, *whitelist; | |
b1547d31 | 71 | bool ignore_unreachables, c_file; |
442f04c3 JP |
72 | }; |
73 | ||
74 | const char *objname; | |
75 | static bool nofp; | |
76 | ||
74aec058 JP |
77 | static struct instruction *find_insn(struct objtool_file *file, |
78 | struct section *sec, unsigned long offset) | |
442f04c3 JP |
79 | { |
80 | struct instruction *insn; | |
81 | ||
042ba73f | 82 | hash_for_each_possible(file->insn_hash, insn, hash, offset) |
442f04c3 JP |
83 | if (insn->sec == sec && insn->offset == offset) |
84 | return insn; | |
85 | ||
86 | return NULL; | |
87 | } | |
88 | ||
74aec058 JP |
89 | static struct instruction *next_insn_same_sec(struct objtool_file *file, |
90 | struct instruction *insn) | |
91 | { | |
92 | struct instruction *next = list_next_entry(insn, list); | |
93 | ||
a196e171 | 94 | if (&next->list == &file->insn_list || next->sec != insn->sec) |
74aec058 JP |
95 | return NULL; |
96 | ||
97 | return next; | |
98 | } | |
99 | ||
9cfffb11 JP |
100 | static bool gcov_enabled(struct objtool_file *file) |
101 | { | |
102 | struct section *sec; | |
103 | struct symbol *sym; | |
104 | ||
105 | list_for_each_entry(sec, &file->elf->sections, list) | |
106 | list_for_each_entry(sym, &sec->symbol_list, list) | |
107 | if (!strncmp(sym->name, "__gcov_.", 8)) | |
108 | return true; | |
109 | ||
110 | return false; | |
111 | } | |
112 | ||
74aec058 | 113 | #define for_each_insn(file, insn) \ |
a196e171 | 114 | list_for_each_entry(insn, &file->insn_list, list) |
74aec058 JP |
115 | |
116 | #define func_for_each_insn(file, func, insn) \ | |
117 | for (insn = find_insn(file, func->sec, func->offset); \ | |
a196e171 | 118 | insn && &insn->list != &file->insn_list && \ |
74aec058 JP |
119 | insn->sec == func->sec && \ |
120 | insn->offset < func->offset + func->len; \ | |
121 | insn = list_next_entry(insn, list)) | |
122 | ||
6d01f28b JP |
123 | #define func_for_each_insn_continue_reverse(file, func, insn) \ |
124 | for (insn = list_prev_entry(insn, list); \ | |
125 | &insn->list != &file->insn_list && \ | |
126 | insn->sec == func->sec && insn->offset >= func->offset; \ | |
127 | insn = list_prev_entry(insn, list)) | |
128 | ||
74aec058 JP |
129 | #define sec_for_each_insn_from(file, insn) \ |
130 | for (; insn; insn = next_insn_same_sec(file, insn)) | |
131 | ||
132 | ||
442f04c3 JP |
133 | /* |
134 | * Check if the function has been manually whitelisted with the | |
135 | * STACK_FRAME_NON_STANDARD macro, or if it should be automatically whitelisted | |
136 | * due to its use of a context switching instruction. | |
137 | */ | |
138 | static bool ignore_func(struct objtool_file *file, struct symbol *func) | |
139 | { | |
442f04c3 JP |
140 | struct rela *rela; |
141 | struct instruction *insn; | |
142 | ||
143 | /* check for STACK_FRAME_NON_STANDARD */ | |
042ba73f | 144 | if (file->whitelist && file->whitelist->rela) |
0ea5ad86 JP |
145 | list_for_each_entry(rela, &file->whitelist->rela->rela_list, list) { |
146 | if (rela->sym->type == STT_SECTION && | |
147 | rela->sym->sec == func->sec && | |
442f04c3 JP |
148 | rela->addend == func->offset) |
149 | return true; | |
0ea5ad86 JP |
150 | if (rela->sym->type == STT_FUNC && rela->sym == func) |
151 | return true; | |
152 | } | |
442f04c3 JP |
153 | |
154 | /* check if it has a context switching instruction */ | |
74aec058 | 155 | func_for_each_insn(file, func, insn) |
442f04c3 JP |
156 | if (insn->type == INSN_CONTEXT_SWITCH) |
157 | return true; | |
442f04c3 JP |
158 | |
159 | return false; | |
160 | } | |
161 | ||
162 | /* | |
163 | * This checks to see if the given function is a "noreturn" function. | |
164 | * | |
165 | * For global functions which are outside the scope of this object file, we | |
166 | * have to keep a manual list of them. | |
167 | * | |
168 | * For local functions, we have to detect them manually by simply looking for | |
169 | * the lack of a return instruction. | |
b1e03249 JP |
170 | * |
171 | * Returns: | |
172 | * -1: error | |
173 | * 0: no dead end | |
174 | * 1: dead end | |
442f04c3 | 175 | */ |
b1e03249 JP |
176 | static int __dead_end_function(struct objtool_file *file, struct symbol *func, |
177 | int recursion) | |
442f04c3 JP |
178 | { |
179 | int i; | |
74aec058 | 180 | struct instruction *insn; |
442f04c3 JP |
181 | bool empty = true; |
182 | ||
183 | /* | |
184 | * Unfortunately these have to be hard coded because the noreturn | |
185 | * attribute isn't provided in ELF data. | |
186 | */ | |
187 | static const char * const global_noreturns[] = { | |
188 | "__stack_chk_fail", | |
189 | "panic", | |
190 | "do_exit", | |
c1fad9ef | 191 | "do_task_dead", |
442f04c3 JP |
192 | "__module_put_and_exit", |
193 | "complete_and_exit", | |
194 | "kvm_spurious_fault", | |
195 | "__reiserfs_panic", | |
196 | "lbug_with_loc" | |
197 | }; | |
198 | ||
199 | if (func->bind == STB_WEAK) | |
b1e03249 | 200 | return 0; |
442f04c3 JP |
201 | |
202 | if (func->bind == STB_GLOBAL) | |
203 | for (i = 0; i < ARRAY_SIZE(global_noreturns); i++) | |
204 | if (!strcmp(func->name, global_noreturns[i])) | |
b1e03249 | 205 | return 1; |
442f04c3 JP |
206 | |
207 | if (!func->sec) | |
b1e03249 | 208 | return 0; |
442f04c3 | 209 | |
74aec058 | 210 | func_for_each_insn(file, func, insn) { |
442f04c3 JP |
211 | empty = false; |
212 | ||
213 | if (insn->type == INSN_RETURN) | |
b1e03249 | 214 | return 0; |
81bfafca JP |
215 | } |
216 | ||
217 | if (empty) | |
b1e03249 | 218 | return 0; |
81bfafca JP |
219 | |
220 | /* | |
221 | * A function can have a sibling call instead of a return. In that | |
222 | * case, the function's dead-end status depends on whether the target | |
223 | * of the sibling call returns. | |
224 | */ | |
74aec058 | 225 | func_for_each_insn(file, func, insn) { |
81bfafca JP |
226 | if (insn->sec != func->sec || |
227 | insn->offset >= func->offset + func->len) | |
228 | break; | |
442f04c3 JP |
229 | |
230 | if (insn->type == INSN_JUMP_UNCONDITIONAL) { | |
231 | struct instruction *dest = insn->jump_dest; | |
232 | struct symbol *dest_func; | |
233 | ||
234 | if (!dest) | |
235 | /* sibling call to another file */ | |
b1e03249 | 236 | return 0; |
442f04c3 JP |
237 | |
238 | if (dest->sec != func->sec || | |
239 | dest->offset < func->offset || | |
240 | dest->offset >= func->offset + func->len) { | |
241 | /* local sibling call */ | |
242 | dest_func = find_symbol_by_offset(dest->sec, | |
243 | dest->offset); | |
244 | if (!dest_func) | |
245 | continue; | |
246 | ||
b1e03249 JP |
247 | if (recursion == 5) { |
248 | WARN_FUNC("infinite recursion (objtool bug!)", | |
249 | dest->sec, dest->offset); | |
250 | return -1; | |
251 | } | |
252 | ||
253 | return __dead_end_function(file, dest_func, | |
254 | recursion + 1); | |
442f04c3 JP |
255 | } |
256 | } | |
257 | ||
b1547d31 | 258 | if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts)) |
442f04c3 | 259 | /* sibling call */ |
b1e03249 | 260 | return 0; |
442f04c3 JP |
261 | } |
262 | ||
b1e03249 JP |
263 | return 1; |
264 | } | |
265 | ||
266 | static int dead_end_function(struct objtool_file *file, struct symbol *func) | |
267 | { | |
268 | return __dead_end_function(file, func, 0); | |
442f04c3 JP |
269 | } |
270 | ||
271 | /* | |
272 | * Call the arch-specific instruction decoder for all the instructions and add | |
a196e171 | 273 | * them to the global instruction list. |
442f04c3 JP |
274 | */ |
275 | static int decode_instructions(struct objtool_file *file) | |
276 | { | |
277 | struct section *sec; | |
b1547d31 | 278 | struct symbol *func; |
442f04c3 JP |
279 | unsigned long offset; |
280 | struct instruction *insn; | |
281 | int ret; | |
282 | ||
442f04c3 JP |
283 | list_for_each_entry(sec, &file->elf->sections, list) { |
284 | ||
285 | if (!(sec->sh.sh_flags & SHF_EXECINSTR)) | |
286 | continue; | |
287 | ||
288 | for (offset = 0; offset < sec->len; offset += insn->len) { | |
289 | insn = malloc(sizeof(*insn)); | |
290 | memset(insn, 0, sizeof(*insn)); | |
291 | ||
292 | INIT_LIST_HEAD(&insn->alts); | |
293 | insn->sec = sec; | |
294 | insn->offset = offset; | |
295 | ||
296 | ret = arch_decode_instruction(file->elf, sec, offset, | |
297 | sec->len - offset, | |
298 | &insn->len, &insn->type, | |
299 | &insn->immediate); | |
300 | if (ret) | |
301 | return ret; | |
302 | ||
303 | if (!insn->type || insn->type > INSN_LAST) { | |
304 | WARN_FUNC("invalid instruction type %d", | |
305 | insn->sec, insn->offset, insn->type); | |
306 | return -1; | |
307 | } | |
308 | ||
042ba73f | 309 | hash_add(file->insn_hash, &insn->hash, insn->offset); |
a196e171 | 310 | list_add_tail(&insn->list, &file->insn_list); |
442f04c3 | 311 | } |
b1547d31 JP |
312 | |
313 | list_for_each_entry(func, &sec->symbol_list, list) { | |
314 | if (func->type != STT_FUNC) | |
315 | continue; | |
316 | ||
317 | if (!find_insn(file, sec, func->offset)) { | |
318 | WARN("%s(): can't find starting instruction", | |
319 | func->name); | |
320 | return -1; | |
321 | } | |
322 | ||
323 | func_for_each_insn(file, func, insn) | |
324 | if (!insn->func) | |
325 | insn->func = func; | |
326 | } | |
442f04c3 JP |
327 | } |
328 | ||
329 | return 0; | |
330 | } | |
331 | ||
d1091c7f JP |
332 | /* |
333 | * Find all uses of the unreachable() macro, which are code path dead ends. | |
334 | */ | |
335 | static int add_dead_ends(struct objtool_file *file) | |
336 | { | |
337 | struct section *sec; | |
338 | struct rela *rela; | |
339 | struct instruction *insn; | |
340 | bool found; | |
341 | ||
e390f9a9 | 342 | sec = find_section_by_name(file->elf, ".rela.discard.unreachable"); |
d1091c7f JP |
343 | if (!sec) |
344 | return 0; | |
345 | ||
346 | list_for_each_entry(rela, &sec->rela_list, list) { | |
347 | if (rela->sym->type != STT_SECTION) { | |
e390f9a9 | 348 | WARN("unexpected relocation symbol type in %s", sec->name); |
d1091c7f JP |
349 | return -1; |
350 | } | |
351 | insn = find_insn(file, rela->sym->sec, rela->addend); | |
352 | if (insn) | |
353 | insn = list_prev_entry(insn, list); | |
354 | else if (rela->addend == rela->sym->sec->len) { | |
355 | found = false; | |
356 | list_for_each_entry_reverse(insn, &file->insn_list, list) { | |
357 | if (insn->sec == rela->sym->sec) { | |
358 | found = true; | |
359 | break; | |
360 | } | |
361 | } | |
362 | ||
363 | if (!found) { | |
364 | WARN("can't find unreachable insn at %s+0x%x", | |
365 | rela->sym->sec->name, rela->addend); | |
366 | return -1; | |
367 | } | |
368 | } else { | |
369 | WARN("can't find unreachable insn at %s+0x%x", | |
370 | rela->sym->sec->name, rela->addend); | |
371 | return -1; | |
372 | } | |
373 | ||
374 | insn->dead_end = true; | |
375 | } | |
376 | ||
377 | return 0; | |
378 | } | |
379 | ||
442f04c3 JP |
380 | /* |
381 | * Warnings shouldn't be reported for ignored functions. | |
382 | */ | |
a196e171 | 383 | static void add_ignores(struct objtool_file *file) |
442f04c3 JP |
384 | { |
385 | struct instruction *insn; | |
386 | struct section *sec; | |
387 | struct symbol *func; | |
388 | ||
389 | list_for_each_entry(sec, &file->elf->sections, list) { | |
a196e171 | 390 | list_for_each_entry(func, &sec->symbol_list, list) { |
442f04c3 JP |
391 | if (func->type != STT_FUNC) |
392 | continue; | |
393 | ||
394 | if (!ignore_func(file, func)) | |
395 | continue; | |
396 | ||
74aec058 | 397 | func_for_each_insn(file, func, insn) |
442f04c3 | 398 | insn->visited = true; |
442f04c3 JP |
399 | } |
400 | } | |
401 | } | |
402 | ||
403 | /* | |
404 | * Find the destination instructions for all jumps. | |
405 | */ | |
a196e171 | 406 | static int add_jump_destinations(struct objtool_file *file) |
442f04c3 JP |
407 | { |
408 | struct instruction *insn; | |
409 | struct rela *rela; | |
410 | struct section *dest_sec; | |
411 | unsigned long dest_off; | |
412 | ||
74aec058 | 413 | for_each_insn(file, insn) { |
442f04c3 JP |
414 | if (insn->type != INSN_JUMP_CONDITIONAL && |
415 | insn->type != INSN_JUMP_UNCONDITIONAL) | |
416 | continue; | |
417 | ||
418 | /* skip ignores */ | |
419 | if (insn->visited) | |
420 | continue; | |
421 | ||
422 | rela = find_rela_by_dest_range(insn->sec, insn->offset, | |
423 | insn->len); | |
424 | if (!rela) { | |
425 | dest_sec = insn->sec; | |
426 | dest_off = insn->offset + insn->len + insn->immediate; | |
427 | } else if (rela->sym->type == STT_SECTION) { | |
428 | dest_sec = rela->sym->sec; | |
429 | dest_off = rela->addend + 4; | |
430 | } else if (rela->sym->sec->idx) { | |
431 | dest_sec = rela->sym->sec; | |
432 | dest_off = rela->sym->sym.st_value + rela->addend + 4; | |
433 | } else { | |
434 | /* sibling call */ | |
435 | insn->jump_dest = 0; | |
436 | continue; | |
437 | } | |
438 | ||
74aec058 | 439 | insn->jump_dest = find_insn(file, dest_sec, dest_off); |
442f04c3 JP |
440 | if (!insn->jump_dest) { |
441 | ||
442 | /* | |
443 | * This is a special case where an alt instruction | |
444 | * jumps past the end of the section. These are | |
445 | * handled later in handle_group_alt(). | |
446 | */ | |
447 | if (!strcmp(insn->sec->name, ".altinstr_replacement")) | |
448 | continue; | |
449 | ||
450 | WARN_FUNC("can't find jump dest instruction at %s+0x%lx", | |
451 | insn->sec, insn->offset, dest_sec->name, | |
452 | dest_off); | |
453 | return -1; | |
454 | } | |
455 | } | |
456 | ||
457 | return 0; | |
458 | } | |
459 | ||
460 | /* | |
461 | * Find the destination instructions for all calls. | |
462 | */ | |
a196e171 | 463 | static int add_call_destinations(struct objtool_file *file) |
442f04c3 JP |
464 | { |
465 | struct instruction *insn; | |
466 | unsigned long dest_off; | |
467 | struct rela *rela; | |
468 | ||
74aec058 | 469 | for_each_insn(file, insn) { |
442f04c3 JP |
470 | if (insn->type != INSN_CALL) |
471 | continue; | |
472 | ||
473 | rela = find_rela_by_dest_range(insn->sec, insn->offset, | |
474 | insn->len); | |
475 | if (!rela) { | |
476 | dest_off = insn->offset + insn->len + insn->immediate; | |
477 | insn->call_dest = find_symbol_by_offset(insn->sec, | |
478 | dest_off); | |
479 | if (!insn->call_dest) { | |
480 | WARN_FUNC("can't find call dest symbol at offset 0x%lx", | |
481 | insn->sec, insn->offset, dest_off); | |
482 | return -1; | |
483 | } | |
484 | } else if (rela->sym->type == STT_SECTION) { | |
485 | insn->call_dest = find_symbol_by_offset(rela->sym->sec, | |
486 | rela->addend+4); | |
487 | if (!insn->call_dest || | |
488 | insn->call_dest->type != STT_FUNC) { | |
489 | WARN_FUNC("can't find call dest symbol at %s+0x%x", | |
490 | insn->sec, insn->offset, | |
491 | rela->sym->sec->name, | |
492 | rela->addend + 4); | |
493 | return -1; | |
494 | } | |
495 | } else | |
496 | insn->call_dest = rela->sym; | |
497 | } | |
498 | ||
499 | return 0; | |
500 | } | |
501 | ||
502 | /* | |
503 | * The .alternatives section requires some extra special care, over and above | |
504 | * what other special sections require: | |
505 | * | |
506 | * 1. Because alternatives are patched in-place, we need to insert a fake jump | |
507 | * instruction at the end so that validate_branch() skips all the original | |
508 | * replaced instructions when validating the new instruction path. | |
509 | * | |
510 | * 2. An added wrinkle is that the new instruction length might be zero. In | |
511 | * that case the old instructions are replaced with noops. We simulate that | |
512 | * by creating a fake jump as the only new instruction. | |
513 | * | |
514 | * 3. In some cases, the alternative section includes an instruction which | |
515 | * conditionally jumps to the _end_ of the entry. We have to modify these | |
516 | * jumps' destinations to point back to .text rather than the end of the | |
517 | * entry in .altinstr_replacement. | |
518 | * | |
519 | * 4. It has been requested that we don't validate the !POPCNT feature path | |
520 | * which is a "very very small percentage of machines". | |
521 | */ | |
522 | static int handle_group_alt(struct objtool_file *file, | |
523 | struct special_alt *special_alt, | |
524 | struct instruction *orig_insn, | |
525 | struct instruction **new_insn) | |
526 | { | |
527 | struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump; | |
528 | unsigned long dest_off; | |
529 | ||
530 | last_orig_insn = NULL; | |
531 | insn = orig_insn; | |
74aec058 JP |
532 | sec_for_each_insn_from(file, insn) { |
533 | if (insn->offset >= special_alt->orig_off + special_alt->orig_len) | |
442f04c3 JP |
534 | break; |
535 | ||
536 | if (special_alt->skip_orig) | |
537 | insn->type = INSN_NOP; | |
538 | ||
539 | insn->alt_group = true; | |
540 | last_orig_insn = insn; | |
541 | } | |
542 | ||
74aec058 | 543 | if (!next_insn_same_sec(file, last_orig_insn)) { |
442f04c3 JP |
544 | WARN("%s: don't know how to handle alternatives at end of section", |
545 | special_alt->orig_sec->name); | |
546 | return -1; | |
547 | } | |
548 | ||
549 | fake_jump = malloc(sizeof(*fake_jump)); | |
550 | if (!fake_jump) { | |
551 | WARN("malloc failed"); | |
552 | return -1; | |
553 | } | |
554 | memset(fake_jump, 0, sizeof(*fake_jump)); | |
555 | INIT_LIST_HEAD(&fake_jump->alts); | |
556 | fake_jump->sec = special_alt->new_sec; | |
557 | fake_jump->offset = -1; | |
558 | fake_jump->type = INSN_JUMP_UNCONDITIONAL; | |
559 | fake_jump->jump_dest = list_next_entry(last_orig_insn, list); | |
560 | ||
561 | if (!special_alt->new_len) { | |
562 | *new_insn = fake_jump; | |
563 | return 0; | |
564 | } | |
565 | ||
566 | last_new_insn = NULL; | |
567 | insn = *new_insn; | |
74aec058 JP |
568 | sec_for_each_insn_from(file, insn) { |
569 | if (insn->offset >= special_alt->new_off + special_alt->new_len) | |
442f04c3 JP |
570 | break; |
571 | ||
572 | last_new_insn = insn; | |
573 | ||
574 | if (insn->type != INSN_JUMP_CONDITIONAL && | |
575 | insn->type != INSN_JUMP_UNCONDITIONAL) | |
576 | continue; | |
577 | ||
578 | if (!insn->immediate) | |
579 | continue; | |
580 | ||
581 | dest_off = insn->offset + insn->len + insn->immediate; | |
582 | if (dest_off == special_alt->new_off + special_alt->new_len) | |
583 | insn->jump_dest = fake_jump; | |
584 | ||
585 | if (!insn->jump_dest) { | |
586 | WARN_FUNC("can't find alternative jump destination", | |
587 | insn->sec, insn->offset); | |
588 | return -1; | |
589 | } | |
590 | } | |
591 | ||
592 | if (!last_new_insn) { | |
593 | WARN_FUNC("can't find last new alternative instruction", | |
594 | special_alt->new_sec, special_alt->new_off); | |
595 | return -1; | |
596 | } | |
597 | ||
598 | list_add(&fake_jump->list, &last_new_insn->list); | |
599 | ||
600 | return 0; | |
601 | } | |
602 | ||
603 | /* | |
604 | * A jump table entry can either convert a nop to a jump or a jump to a nop. | |
605 | * If the original instruction is a jump, make the alt entry an effective nop | |
606 | * by just skipping the original instruction. | |
607 | */ | |
608 | static int handle_jump_alt(struct objtool_file *file, | |
609 | struct special_alt *special_alt, | |
610 | struct instruction *orig_insn, | |
611 | struct instruction **new_insn) | |
612 | { | |
613 | if (orig_insn->type == INSN_NOP) | |
614 | return 0; | |
615 | ||
616 | if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) { | |
617 | WARN_FUNC("unsupported instruction at jump label", | |
618 | orig_insn->sec, orig_insn->offset); | |
619 | return -1; | |
620 | } | |
621 | ||
622 | *new_insn = list_next_entry(orig_insn, list); | |
623 | return 0; | |
624 | } | |
625 | ||
626 | /* | |
627 | * Read all the special sections which have alternate instructions which can be | |
628 | * patched in or redirected to at runtime. Each instruction having alternate | |
629 | * instruction(s) has them added to its insn->alts list, which will be | |
630 | * traversed in validate_branch(). | |
631 | */ | |
a196e171 | 632 | static int add_special_section_alts(struct objtool_file *file) |
442f04c3 JP |
633 | { |
634 | struct list_head special_alts; | |
635 | struct instruction *orig_insn, *new_insn; | |
636 | struct special_alt *special_alt, *tmp; | |
637 | struct alternative *alt; | |
638 | int ret; | |
639 | ||
640 | ret = special_get_alts(file->elf, &special_alts); | |
641 | if (ret) | |
642 | return ret; | |
643 | ||
644 | list_for_each_entry_safe(special_alt, tmp, &special_alts, list) { | |
645 | alt = malloc(sizeof(*alt)); | |
646 | if (!alt) { | |
647 | WARN("malloc failed"); | |
648 | ret = -1; | |
649 | goto out; | |
650 | } | |
651 | ||
74aec058 JP |
652 | orig_insn = find_insn(file, special_alt->orig_sec, |
653 | special_alt->orig_off); | |
442f04c3 JP |
654 | if (!orig_insn) { |
655 | WARN_FUNC("special: can't find orig instruction", | |
656 | special_alt->orig_sec, special_alt->orig_off); | |
657 | ret = -1; | |
658 | goto out; | |
659 | } | |
660 | ||
661 | new_insn = NULL; | |
662 | if (!special_alt->group || special_alt->new_len) { | |
74aec058 JP |
663 | new_insn = find_insn(file, special_alt->new_sec, |
664 | special_alt->new_off); | |
442f04c3 JP |
665 | if (!new_insn) { |
666 | WARN_FUNC("special: can't find new instruction", | |
667 | special_alt->new_sec, | |
668 | special_alt->new_off); | |
669 | ret = -1; | |
670 | goto out; | |
671 | } | |
672 | } | |
673 | ||
674 | if (special_alt->group) { | |
675 | ret = handle_group_alt(file, special_alt, orig_insn, | |
676 | &new_insn); | |
677 | if (ret) | |
678 | goto out; | |
679 | } else if (special_alt->jump_or_nop) { | |
680 | ret = handle_jump_alt(file, special_alt, orig_insn, | |
681 | &new_insn); | |
682 | if (ret) | |
683 | goto out; | |
684 | } | |
685 | ||
686 | alt->insn = new_insn; | |
687 | list_add_tail(&alt->list, &orig_insn->alts); | |
688 | ||
689 | list_del(&special_alt->list); | |
690 | free(special_alt); | |
691 | } | |
692 | ||
693 | out: | |
694 | return ret; | |
695 | } | |
696 | ||
8133fbb4 JP |
697 | static int add_switch_table(struct objtool_file *file, struct symbol *func, |
698 | struct instruction *insn, struct rela *table, | |
699 | struct rela *next_table) | |
442f04c3 | 700 | { |
8133fbb4 JP |
701 | struct rela *rela = table; |
702 | struct instruction *alt_insn; | |
442f04c3 JP |
703 | struct alternative *alt; |
704 | ||
8133fbb4 JP |
705 | list_for_each_entry_from(rela, &file->rodata->rela->rela_list, list) { |
706 | if (rela == next_table) | |
707 | break; | |
708 | ||
709 | if (rela->sym->sec != insn->sec || | |
710 | rela->addend <= func->offset || | |
711 | rela->addend >= func->offset + func->len) | |
712 | break; | |
713 | ||
714 | alt_insn = find_insn(file, insn->sec, rela->addend); | |
715 | if (!alt_insn) { | |
716 | WARN("%s: can't find instruction at %s+0x%x", | |
717 | file->rodata->rela->name, insn->sec->name, | |
718 | rela->addend); | |
719 | return -1; | |
720 | } | |
721 | ||
722 | alt = malloc(sizeof(*alt)); | |
723 | if (!alt) { | |
724 | WARN("malloc failed"); | |
725 | return -1; | |
726 | } | |
727 | ||
728 | alt->insn = alt_insn; | |
729 | list_add_tail(&alt->list, &insn->alts); | |
730 | } | |
731 | ||
732 | return 0; | |
733 | } | |
734 | ||
6d01f28b JP |
735 | /* |
736 | * find_switch_table() - Given a dynamic jump, find the switch jump table in | |
737 | * .rodata associated with it. | |
738 | * | |
739 | * There are 3 basic patterns: | |
740 | * | |
741 | * 1. jmpq *[rodata addr](,%reg,8) | |
742 | * | |
743 | * This is the most common case by far. It jumps to an address in a simple | |
744 | * jump table which is stored in .rodata. | |
745 | * | |
746 | * 2. jmpq *[rodata addr](%rip) | |
747 | * | |
748 | * This is caused by a rare GCC quirk, currently only seen in three driver | |
749 | * functions in the kernel, only with certain obscure non-distro configs. | |
750 | * | |
751 | * As part of an optimization, GCC makes a copy of an existing switch jump | |
752 | * table, modifies it, and then hard-codes the jump (albeit with an indirect | |
753 | * jump) to use a single entry in the table. The rest of the jump table and | |
754 | * some of its jump targets remain as dead code. | |
755 | * | |
756 | * In such a case we can just crudely ignore all unreachable instruction | |
757 | * warnings for the entire object file. Ideally we would just ignore them | |
758 | * for the function, but that would require redesigning the code quite a | |
759 | * bit. And honestly that's just not worth doing: unreachable instruction | |
760 | * warnings are of questionable value anyway, and this is such a rare issue. | |
761 | * | |
762 | * 3. mov [rodata addr],%reg1 | |
763 | * ... some instructions ... | |
764 | * jmpq *(%reg1,%reg2,8) | |
765 | * | |
766 | * This is a fairly uncommon pattern which is new for GCC 6. As of this | |
767 | * writing, there are 11 occurrences of it in the allmodconfig kernel. | |
768 | * | |
769 | * TODO: Once we have DWARF CFI and smarter instruction decoding logic, | |
770 | * ensure the same register is used in the mov and jump instructions. | |
771 | */ | |
772 | static struct rela *find_switch_table(struct objtool_file *file, | |
773 | struct symbol *func, | |
774 | struct instruction *insn) | |
8133fbb4 | 775 | { |
6d01f28b | 776 | struct rela *text_rela, *rodata_rela; |
3732710f | 777 | struct instruction *orig_insn = insn; |
8133fbb4 | 778 | |
6d01f28b JP |
779 | text_rela = find_rela_by_dest_range(insn->sec, insn->offset, insn->len); |
780 | if (text_rela && text_rela->sym == file->rodata->sym) { | |
781 | /* case 1 */ | |
782 | rodata_rela = find_rela_by_dest(file->rodata, | |
783 | text_rela->addend); | |
784 | if (rodata_rela) | |
785 | return rodata_rela; | |
8133fbb4 | 786 | |
6d01f28b JP |
787 | /* case 2 */ |
788 | rodata_rela = find_rela_by_dest(file->rodata, | |
789 | text_rela->addend + 4); | |
790 | if (!rodata_rela) | |
791 | return NULL; | |
792 | file->ignore_unreachables = true; | |
793 | return rodata_rela; | |
794 | } | |
795 | ||
796 | /* case 3 */ | |
797 | func_for_each_insn_continue_reverse(file, func, insn) { | |
3732710f | 798 | if (insn->type == INSN_JUMP_DYNAMIC) |
6d01f28b | 799 | break; |
442f04c3 | 800 | |
3732710f JP |
801 | /* allow small jumps within the range */ |
802 | if (insn->type == INSN_JUMP_UNCONDITIONAL && | |
803 | insn->jump_dest && | |
804 | (insn->jump_dest->offset <= insn->offset || | |
56fb2d6e | 805 | insn->jump_dest->offset > orig_insn->offset)) |
3732710f JP |
806 | break; |
807 | ||
5c51f4ae | 808 | /* look for a relocation which references .rodata */ |
a196e171 JP |
809 | text_rela = find_rela_by_dest_range(insn->sec, insn->offset, |
810 | insn->len); | |
5c51f4ae JP |
811 | if (!text_rela || text_rela->sym != file->rodata->sym) |
812 | continue; | |
813 | ||
814 | /* | |
815 | * Make sure the .rodata address isn't associated with a | |
816 | * symbol. gcc jump tables are anonymous data. | |
817 | */ | |
818 | if (find_symbol_containing(file->rodata, text_rela->addend)) | |
819 | continue; | |
820 | ||
821 | return find_rela_by_dest(file->rodata, text_rela->addend); | |
6d01f28b | 822 | } |
442f04c3 | 823 | |
6d01f28b JP |
824 | return NULL; |
825 | } | |
8133fbb4 | 826 | |
6d01f28b JP |
827 | static int add_func_switch_tables(struct objtool_file *file, |
828 | struct symbol *func) | |
829 | { | |
830 | struct instruction *insn, *prev_jump = NULL; | |
831 | struct rela *rela, *prev_rela = NULL; | |
832 | int ret; | |
8133fbb4 | 833 | |
6d01f28b JP |
834 | func_for_each_insn(file, func, insn) { |
835 | if (insn->type != INSN_JUMP_DYNAMIC) | |
836 | continue; | |
837 | ||
838 | rela = find_switch_table(file, func, insn); | |
839 | if (!rela) | |
442f04c3 JP |
840 | continue; |
841 | ||
8133fbb4 JP |
842 | /* |
843 | * We found a switch table, but we don't know yet how big it | |
844 | * is. Don't add it until we reach the end of the function or | |
845 | * the beginning of another switch table in the same function. | |
846 | */ | |
847 | if (prev_jump) { | |
848 | ret = add_switch_table(file, func, prev_jump, prev_rela, | |
6d01f28b | 849 | rela); |
8133fbb4 JP |
850 | if (ret) |
851 | return ret; | |
442f04c3 JP |
852 | } |
853 | ||
8133fbb4 | 854 | prev_jump = insn; |
6d01f28b | 855 | prev_rela = rela; |
8133fbb4 | 856 | } |
442f04c3 | 857 | |
8133fbb4 JP |
858 | if (prev_jump) { |
859 | ret = add_switch_table(file, func, prev_jump, prev_rela, NULL); | |
860 | if (ret) | |
861 | return ret; | |
862 | } | |
863 | ||
864 | return 0; | |
865 | } | |
442f04c3 | 866 | |
8133fbb4 JP |
867 | /* |
868 | * For some switch statements, gcc generates a jump table in the .rodata | |
869 | * section which contains a list of addresses within the function to jump to. | |
870 | * This finds these jump tables and adds them to the insn->alts lists. | |
871 | */ | |
872 | static int add_switch_table_alts(struct objtool_file *file) | |
873 | { | |
874 | struct section *sec; | |
875 | struct symbol *func; | |
876 | int ret; | |
877 | ||
878 | if (!file->rodata || !file->rodata->rela) | |
879 | return 0; | |
880 | ||
881 | list_for_each_entry(sec, &file->elf->sections, list) { | |
882 | list_for_each_entry(func, &sec->symbol_list, list) { | |
883 | if (func->type != STT_FUNC) | |
884 | continue; | |
885 | ||
886 | ret = add_func_switch_tables(file, func); | |
887 | if (ret) | |
888 | return ret; | |
442f04c3 JP |
889 | } |
890 | } | |
891 | ||
892 | return 0; | |
893 | } | |
894 | ||
895 | static int decode_sections(struct objtool_file *file) | |
896 | { | |
897 | int ret; | |
898 | ||
899 | ret = decode_instructions(file); | |
900 | if (ret) | |
901 | return ret; | |
902 | ||
d1091c7f JP |
903 | ret = add_dead_ends(file); |
904 | if (ret) | |
905 | return ret; | |
906 | ||
a196e171 | 907 | add_ignores(file); |
442f04c3 | 908 | |
a196e171 | 909 | ret = add_jump_destinations(file); |
442f04c3 JP |
910 | if (ret) |
911 | return ret; | |
912 | ||
a196e171 | 913 | ret = add_call_destinations(file); |
442f04c3 JP |
914 | if (ret) |
915 | return ret; | |
916 | ||
a196e171 | 917 | ret = add_special_section_alts(file); |
442f04c3 JP |
918 | if (ret) |
919 | return ret; | |
920 | ||
a196e171 | 921 | ret = add_switch_table_alts(file); |
442f04c3 JP |
922 | if (ret) |
923 | return ret; | |
924 | ||
925 | return 0; | |
926 | } | |
927 | ||
928 | static bool is_fentry_call(struct instruction *insn) | |
929 | { | |
930 | if (insn->type == INSN_CALL && | |
931 | insn->call_dest->type == STT_NOTYPE && | |
932 | !strcmp(insn->call_dest->name, "__fentry__")) | |
933 | return true; | |
934 | ||
935 | return false; | |
936 | } | |
937 | ||
938 | static bool has_modified_stack_frame(struct instruction *insn) | |
939 | { | |
940 | return (insn->state & STATE_FP_SAVED) || | |
941 | (insn->state & STATE_FP_SETUP); | |
942 | } | |
943 | ||
944 | static bool has_valid_stack_frame(struct instruction *insn) | |
945 | { | |
946 | return (insn->state & STATE_FP_SAVED) && | |
947 | (insn->state & STATE_FP_SETUP); | |
948 | } | |
949 | ||
d8d1b2cb JP |
950 | static unsigned int frame_state(unsigned long state) |
951 | { | |
952 | return (state & (STATE_FP_SAVED | STATE_FP_SETUP)); | |
953 | } | |
954 | ||
442f04c3 JP |
955 | /* |
956 | * Follow the branch starting at the given instruction, and recursively follow | |
957 | * any other branches (jumps). Meanwhile, track the frame pointer state at | |
958 | * each instruction and validate all the rules described in | |
959 | * tools/objtool/Documentation/stack-validation.txt. | |
960 | */ | |
961 | static int validate_branch(struct objtool_file *file, | |
962 | struct instruction *first, unsigned char first_state) | |
963 | { | |
964 | struct alternative *alt; | |
965 | struct instruction *insn; | |
966 | struct section *sec; | |
b1547d31 | 967 | struct symbol *func = NULL; |
442f04c3 | 968 | unsigned char state; |
1bcb58a0 | 969 | int ret; |
442f04c3 JP |
970 | |
971 | insn = first; | |
972 | sec = insn->sec; | |
973 | state = first_state; | |
974 | ||
975 | if (insn->alt_group && list_empty(&insn->alts)) { | |
976 | WARN_FUNC("don't know how to handle branch to middle of alternative instruction group", | |
977 | sec, insn->offset); | |
1bcb58a0 | 978 | return 1; |
442f04c3 JP |
979 | } |
980 | ||
981 | while (1) { | |
b1547d31 JP |
982 | if (file->c_file && insn->func) { |
983 | if (func && func != insn->func) { | |
984 | WARN("%s() falls through to next function %s()", | |
985 | func->name, insn->func->name); | |
986 | return 1; | |
987 | } | |
988 | ||
989 | func = insn->func; | |
990 | } | |
991 | ||
442f04c3 | 992 | if (insn->visited) { |
d8d1b2cb | 993 | if (frame_state(insn->state) != frame_state(state)) { |
442f04c3 JP |
994 | WARN_FUNC("frame pointer state mismatch", |
995 | sec, insn->offset); | |
1bcb58a0 | 996 | return 1; |
442f04c3 JP |
997 | } |
998 | ||
1bcb58a0 | 999 | return 0; |
442f04c3 JP |
1000 | } |
1001 | ||
442f04c3 JP |
1002 | insn->visited = true; |
1003 | insn->state = state; | |
1004 | ||
1005 | list_for_each_entry(alt, &insn->alts, list) { | |
1006 | ret = validate_branch(file, alt->insn, state); | |
1bcb58a0 JP |
1007 | if (ret) |
1008 | return 1; | |
442f04c3 JP |
1009 | } |
1010 | ||
1011 | switch (insn->type) { | |
1012 | ||
1013 | case INSN_FP_SAVE: | |
1014 | if (!nofp) { | |
1015 | if (state & STATE_FP_SAVED) { | |
1016 | WARN_FUNC("duplicate frame pointer save", | |
1017 | sec, insn->offset); | |
1bcb58a0 | 1018 | return 1; |
442f04c3 JP |
1019 | } |
1020 | state |= STATE_FP_SAVED; | |
1021 | } | |
1022 | break; | |
1023 | ||
1024 | case INSN_FP_SETUP: | |
1025 | if (!nofp) { | |
1026 | if (state & STATE_FP_SETUP) { | |
1027 | WARN_FUNC("duplicate frame pointer setup", | |
1028 | sec, insn->offset); | |
1bcb58a0 | 1029 | return 1; |
442f04c3 JP |
1030 | } |
1031 | state |= STATE_FP_SETUP; | |
1032 | } | |
1033 | break; | |
1034 | ||
1035 | case INSN_FP_RESTORE: | |
1036 | if (!nofp) { | |
1037 | if (has_valid_stack_frame(insn)) | |
1038 | state &= ~STATE_FP_SETUP; | |
1039 | ||
1040 | state &= ~STATE_FP_SAVED; | |
1041 | } | |
1042 | break; | |
1043 | ||
1044 | case INSN_RETURN: | |
1045 | if (!nofp && has_modified_stack_frame(insn)) { | |
1046 | WARN_FUNC("return without frame pointer restore", | |
1047 | sec, insn->offset); | |
1bcb58a0 | 1048 | return 1; |
442f04c3 | 1049 | } |
1bcb58a0 | 1050 | return 0; |
442f04c3 JP |
1051 | |
1052 | case INSN_CALL: | |
1053 | if (is_fentry_call(insn)) { | |
1054 | state |= STATE_FENTRY; | |
1055 | break; | |
1056 | } | |
1057 | ||
b1e03249 JP |
1058 | ret = dead_end_function(file, insn->call_dest); |
1059 | if (ret == 1) | |
1bcb58a0 | 1060 | return 0; |
b1e03249 | 1061 | if (ret == -1) |
1bcb58a0 | 1062 | return 1; |
442f04c3 JP |
1063 | |
1064 | /* fallthrough */ | |
1065 | case INSN_CALL_DYNAMIC: | |
1066 | if (!nofp && !has_valid_stack_frame(insn)) { | |
1067 | WARN_FUNC("call without frame pointer save/setup", | |
1068 | sec, insn->offset); | |
1bcb58a0 | 1069 | return 1; |
442f04c3 JP |
1070 | } |
1071 | break; | |
1072 | ||
1073 | case INSN_JUMP_CONDITIONAL: | |
1074 | case INSN_JUMP_UNCONDITIONAL: | |
1075 | if (insn->jump_dest) { | |
1076 | ret = validate_branch(file, insn->jump_dest, | |
1077 | state); | |
1bcb58a0 JP |
1078 | if (ret) |
1079 | return 1; | |
442f04c3 JP |
1080 | } else if (has_modified_stack_frame(insn)) { |
1081 | WARN_FUNC("sibling call from callable instruction with changed frame pointer", | |
1082 | sec, insn->offset); | |
1bcb58a0 | 1083 | return 1; |
442f04c3 JP |
1084 | } /* else it's a sibling call */ |
1085 | ||
1086 | if (insn->type == INSN_JUMP_UNCONDITIONAL) | |
1bcb58a0 | 1087 | return 0; |
442f04c3 JP |
1088 | |
1089 | break; | |
1090 | ||
1091 | case INSN_JUMP_DYNAMIC: | |
1092 | if (list_empty(&insn->alts) && | |
1093 | has_modified_stack_frame(insn)) { | |
1094 | WARN_FUNC("sibling call from callable instruction with changed frame pointer", | |
1095 | sec, insn->offset); | |
1bcb58a0 | 1096 | return 1; |
442f04c3 JP |
1097 | } |
1098 | ||
1bcb58a0 | 1099 | return 0; |
442f04c3 | 1100 | |
442f04c3 JP |
1101 | default: |
1102 | break; | |
1103 | } | |
1104 | ||
d1091c7f JP |
1105 | if (insn->dead_end) |
1106 | return 0; | |
1107 | ||
74aec058 JP |
1108 | insn = next_insn_same_sec(file, insn); |
1109 | if (!insn) { | |
442f04c3 | 1110 | WARN("%s: unexpected end of section", sec->name); |
1bcb58a0 | 1111 | return 1; |
442f04c3 JP |
1112 | } |
1113 | } | |
1114 | ||
1bcb58a0 | 1115 | return 0; |
442f04c3 JP |
1116 | } |
1117 | ||
442f04c3 JP |
1118 | static bool is_kasan_insn(struct instruction *insn) |
1119 | { | |
1120 | return (insn->type == INSN_CALL && | |
1121 | !strcmp(insn->call_dest->name, "__asan_handle_no_return")); | |
1122 | } | |
1123 | ||
1124 | static bool is_ubsan_insn(struct instruction *insn) | |
1125 | { | |
1126 | return (insn->type == INSN_CALL && | |
1127 | !strcmp(insn->call_dest->name, | |
1128 | "__ubsan_handle_builtin_unreachable")); | |
1129 | } | |
1130 | ||
74aec058 JP |
1131 | static bool ignore_unreachable_insn(struct symbol *func, |
1132 | struct instruction *insn) | |
442f04c3 JP |
1133 | { |
1134 | int i; | |
1135 | ||
1136 | if (insn->type == INSN_NOP) | |
1137 | return true; | |
1138 | ||
442f04c3 JP |
1139 | /* |
1140 | * Check if this (or a subsequent) instruction is related to | |
1141 | * CONFIG_UBSAN or CONFIG_KASAN. | |
1142 | * | |
1143 | * End the search at 5 instructions to avoid going into the weeds. | |
1144 | */ | |
1145 | for (i = 0; i < 5; i++) { | |
1146 | ||
1147 | if (is_kasan_insn(insn) || is_ubsan_insn(insn)) | |
1148 | return true; | |
1149 | ||
1150 | if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest) { | |
1151 | insn = insn->jump_dest; | |
1152 | continue; | |
1153 | } | |
1154 | ||
74aec058 | 1155 | if (insn->offset + insn->len >= func->offset + func->len) |
442f04c3 JP |
1156 | break; |
1157 | insn = list_next_entry(insn, list); | |
1158 | } | |
1159 | ||
1160 | return false; | |
1161 | } | |
1162 | ||
1163 | static int validate_functions(struct objtool_file *file) | |
1164 | { | |
1165 | struct section *sec; | |
1166 | struct symbol *func; | |
1167 | struct instruction *insn; | |
442f04c3 JP |
1168 | int ret, warnings = 0; |
1169 | ||
1170 | list_for_each_entry(sec, &file->elf->sections, list) { | |
a196e171 | 1171 | list_for_each_entry(func, &sec->symbol_list, list) { |
442f04c3 JP |
1172 | if (func->type != STT_FUNC) |
1173 | continue; | |
1174 | ||
74aec058 | 1175 | insn = find_insn(file, sec, func->offset); |
b1547d31 | 1176 | if (!insn) |
442f04c3 | 1177 | continue; |
442f04c3 JP |
1178 | |
1179 | ret = validate_branch(file, insn, 0); | |
1180 | warnings += ret; | |
1181 | } | |
1182 | } | |
1183 | ||
1184 | list_for_each_entry(sec, &file->elf->sections, list) { | |
a196e171 | 1185 | list_for_each_entry(func, &sec->symbol_list, list) { |
442f04c3 JP |
1186 | if (func->type != STT_FUNC) |
1187 | continue; | |
1188 | ||
74aec058 | 1189 | func_for_each_insn(file, func, insn) { |
442f04c3 JP |
1190 | if (insn->visited) |
1191 | continue; | |
1192 | ||
442f04c3 | 1193 | insn->visited = true; |
7e578441 JP |
1194 | |
1195 | if (file->ignore_unreachables || warnings || | |
1196 | ignore_unreachable_insn(func, insn)) | |
1197 | continue; | |
1198 | ||
9cfffb11 JP |
1199 | /* |
1200 | * gcov produces a lot of unreachable | |
1201 | * instructions. If we get an unreachable | |
1202 | * warning and the file has gcov enabled, just | |
1203 | * ignore it, and all other such warnings for | |
1204 | * the file. | |
1205 | */ | |
1206 | if (!file->ignore_unreachables && | |
1207 | gcov_enabled(file)) { | |
1208 | file->ignore_unreachables = true; | |
1209 | continue; | |
1210 | } | |
1211 | ||
7e578441 JP |
1212 | WARN_FUNC("function has unreachable instruction", insn->sec, insn->offset); |
1213 | warnings++; | |
442f04c3 JP |
1214 | } |
1215 | } | |
1216 | } | |
1217 | ||
1218 | return warnings; | |
1219 | } | |
1220 | ||
1221 | static int validate_uncallable_instructions(struct objtool_file *file) | |
1222 | { | |
1223 | struct instruction *insn; | |
1224 | int warnings = 0; | |
1225 | ||
74aec058 | 1226 | for_each_insn(file, insn) { |
442f04c3 JP |
1227 | if (!insn->visited && insn->type == INSN_RETURN) { |
1228 | WARN_FUNC("return instruction outside of a callable function", | |
1229 | insn->sec, insn->offset); | |
1230 | warnings++; | |
1231 | } | |
1232 | } | |
1233 | ||
1234 | return warnings; | |
1235 | } | |
1236 | ||
1237 | static void cleanup(struct objtool_file *file) | |
1238 | { | |
1239 | struct instruction *insn, *tmpinsn; | |
1240 | struct alternative *alt, *tmpalt; | |
1241 | ||
a196e171 | 1242 | list_for_each_entry_safe(insn, tmpinsn, &file->insn_list, list) { |
442f04c3 JP |
1243 | list_for_each_entry_safe(alt, tmpalt, &insn->alts, list) { |
1244 | list_del(&alt->list); | |
1245 | free(alt); | |
1246 | } | |
1247 | list_del(&insn->list); | |
042ba73f | 1248 | hash_del(&insn->hash); |
442f04c3 JP |
1249 | free(insn); |
1250 | } | |
1251 | elf_close(file->elf); | |
1252 | } | |
1253 | ||
1254 | const char * const check_usage[] = { | |
1255 | "objtool check [<options>] file.o", | |
1256 | NULL, | |
1257 | }; | |
1258 | ||
1259 | int cmd_check(int argc, const char **argv) | |
1260 | { | |
1261 | struct objtool_file file; | |
1262 | int ret, warnings = 0; | |
1263 | ||
1264 | const struct option options[] = { | |
1265 | OPT_BOOLEAN('f', "no-fp", &nofp, "Skip frame pointer validation"), | |
1266 | OPT_END(), | |
1267 | }; | |
1268 | ||
1269 | argc = parse_options(argc, argv, options, check_usage, 0); | |
1270 | ||
1271 | if (argc != 1) | |
1272 | usage_with_options(check_usage, options); | |
1273 | ||
1274 | objname = argv[0]; | |
1275 | ||
1276 | file.elf = elf_open(objname); | |
1277 | if (!file.elf) { | |
1278 | fprintf(stderr, "error reading elf file %s\n", objname); | |
1279 | return 1; | |
1280 | } | |
1281 | ||
a196e171 | 1282 | INIT_LIST_HEAD(&file.insn_list); |
042ba73f | 1283 | hash_init(file.insn_hash); |
e390f9a9 | 1284 | file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard"); |
7e578441 JP |
1285 | file.rodata = find_section_by_name(file.elf, ".rodata"); |
1286 | file.ignore_unreachables = false; | |
b1547d31 | 1287 | file.c_file = find_section_by_name(file.elf, ".comment"); |
442f04c3 JP |
1288 | |
1289 | ret = decode_sections(&file); | |
1290 | if (ret < 0) | |
1291 | goto out; | |
1292 | warnings += ret; | |
1293 | ||
1294 | ret = validate_functions(&file); | |
1295 | if (ret < 0) | |
1296 | goto out; | |
1297 | warnings += ret; | |
1298 | ||
1299 | ret = validate_uncallable_instructions(&file); | |
1300 | if (ret < 0) | |
1301 | goto out; | |
1302 | warnings += ret; | |
1303 | ||
1304 | out: | |
1305 | cleanup(&file); | |
1306 | ||
1307 | /* ignore warnings for now until we get all the code cleaned up */ | |
1308 | if (ret || warnings) | |
1309 | return 0; | |
1310 | return 0; | |
1311 | } |