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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" |
0decf1f8 MH |
10 | #include "cfi.h" |
11 | #include "arch.h" | |
dcc914f4 | 12 | #include "check.h" |
dcc914f4 | 13 | #include "special.h" |
dcc914f4 | 14 | #include "warn.h" |
0f1441b4 | 15 | #include "arch_elf.h" |
dcc914f4 | 16 | |
ee819aed | 17 | #include <linux/objtool.h> |
dcc914f4 JP |
18 | #include <linux/hashtable.h> |
19 | #include <linux/kernel.h> | |
1e7e4788 | 20 | #include <linux/static_call_types.h> |
dcc914f4 | 21 | |
e6da9567 JP |
22 | #define FAKE_JUMP_OFFSET -1 |
23 | ||
dcc914f4 JP |
24 | struct alternative { |
25 | struct list_head list; | |
26 | struct instruction *insn; | |
764eef4b | 27 | bool skip_orig; |
dcc914f4 JP |
28 | }; |
29 | ||
a3608f59 | 30 | struct cfi_init_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 | ||
87ecb582 | 37 | hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) { |
dcc914f4 JP |
38 | if (insn->sec == sec && insn->offset == offset) |
39 | return insn; | |
87ecb582 | 40 | } |
dcc914f4 JP |
41 | |
42 | return NULL; | |
43 | } | |
44 | ||
45 | static struct instruction *next_insn_same_sec(struct objtool_file *file, | |
46 | struct instruction *insn) | |
47 | { | |
48 | struct instruction *next = list_next_entry(insn, list); | |
49 | ||
baa41469 | 50 | if (!next || &next->list == &file->insn_list || next->sec != insn->sec) |
dcc914f4 JP |
51 | return NULL; |
52 | ||
53 | return next; | |
54 | } | |
55 | ||
13810435 JP |
56 | static struct instruction *next_insn_same_func(struct objtool_file *file, |
57 | struct instruction *insn) | |
58 | { | |
59 | struct instruction *next = list_next_entry(insn, list); | |
60 | struct symbol *func = insn->func; | |
61 | ||
62 | if (!func) | |
63 | return NULL; | |
64 | ||
65 | if (&next->list != &file->insn_list && next->func == func) | |
66 | return next; | |
67 | ||
68 | /* Check if we're already in the subfunction: */ | |
69 | if (func == func->cfunc) | |
70 | return NULL; | |
71 | ||
72 | /* Move to the subfunction: */ | |
73 | return find_insn(file, func->cfunc->sec, func->cfunc->offset); | |
74 | } | |
75 | ||
1119d265 JP |
76 | static struct instruction *prev_insn_same_sym(struct objtool_file *file, |
77 | struct instruction *insn) | |
78 | { | |
79 | struct instruction *prev = list_prev_entry(insn, list); | |
80 | ||
81 | if (&prev->list != &file->insn_list && prev->func == insn->func) | |
82 | return prev; | |
83 | ||
84 | return NULL; | |
85 | } | |
86 | ||
f0f70adb | 87 | #define func_for_each_insn(file, func, insn) \ |
13810435 JP |
88 | for (insn = find_insn(file, func->sec, func->offset); \ |
89 | insn; \ | |
90 | insn = next_insn_same_func(file, insn)) | |
91 | ||
dbf4aeb0 PZ |
92 | #define sym_for_each_insn(file, sym, insn) \ |
93 | for (insn = find_insn(file, sym->sec, sym->offset); \ | |
dcc914f4 | 94 | insn && &insn->list != &file->insn_list && \ |
dbf4aeb0 PZ |
95 | insn->sec == sym->sec && \ |
96 | insn->offset < sym->offset + sym->len; \ | |
dcc914f4 JP |
97 | insn = list_next_entry(insn, list)) |
98 | ||
dbf4aeb0 | 99 | #define sym_for_each_insn_continue_reverse(file, sym, insn) \ |
dcc914f4 JP |
100 | for (insn = list_prev_entry(insn, list); \ |
101 | &insn->list != &file->insn_list && \ | |
dbf4aeb0 | 102 | insn->sec == sym->sec && insn->offset >= sym->offset; \ |
dcc914f4 JP |
103 | insn = list_prev_entry(insn, list)) |
104 | ||
105 | #define sec_for_each_insn_from(file, insn) \ | |
106 | for (; insn; insn = next_insn_same_sec(file, insn)) | |
107 | ||
baa41469 JP |
108 | #define sec_for_each_insn_continue(file, insn) \ |
109 | for (insn = next_insn_same_sec(file, insn); insn; \ | |
110 | insn = next_insn_same_sec(file, insn)) | |
dcc914f4 | 111 | |
0c1ddd33 JP |
112 | static bool is_sibling_call(struct instruction *insn) |
113 | { | |
114 | /* An indirect jump is either a sibling call or a jump to a table. */ | |
115 | if (insn->type == INSN_JUMP_DYNAMIC) | |
116 | return list_empty(&insn->alts); | |
117 | ||
a2296140 | 118 | if (!is_static_jump(insn)) |
0c1ddd33 JP |
119 | return false; |
120 | ||
121 | /* add_jump_destinations() sets insn->call_dest for sibling calls. */ | |
122 | return !!insn->call_dest; | |
123 | } | |
124 | ||
dcc914f4 JP |
125 | /* |
126 | * This checks to see if the given function is a "noreturn" function. | |
127 | * | |
128 | * For global functions which are outside the scope of this object file, we | |
129 | * have to keep a manual list of them. | |
130 | * | |
131 | * For local functions, we have to detect them manually by simply looking for | |
132 | * the lack of a return instruction. | |
dcc914f4 | 133 | */ |
8e25c9f8 JP |
134 | static bool __dead_end_function(struct objtool_file *file, struct symbol *func, |
135 | int recursion) | |
dcc914f4 JP |
136 | { |
137 | int i; | |
138 | struct instruction *insn; | |
139 | bool empty = true; | |
140 | ||
141 | /* | |
142 | * Unfortunately these have to be hard coded because the noreturn | |
143 | * attribute isn't provided in ELF data. | |
144 | */ | |
145 | static const char * const global_noreturns[] = { | |
146 | "__stack_chk_fail", | |
147 | "panic", | |
148 | "do_exit", | |
149 | "do_task_dead", | |
150 | "__module_put_and_exit", | |
151 | "complete_and_exit", | |
dcc914f4 JP |
152 | "__reiserfs_panic", |
153 | "lbug_with_loc", | |
154 | "fortify_panic", | |
b394d468 | 155 | "usercopy_abort", |
684fb246 | 156 | "machine_real_restart", |
4fa5ecda | 157 | "rewind_stack_do_exit", |
33adf80f | 158 | "kunit_try_catch_throw", |
dcc914f4 JP |
159 | }; |
160 | ||
c9bab22b JP |
161 | if (!func) |
162 | return false; | |
163 | ||
dcc914f4 | 164 | if (func->bind == STB_WEAK) |
8e25c9f8 | 165 | return false; |
dcc914f4 JP |
166 | |
167 | if (func->bind == STB_GLOBAL) | |
168 | for (i = 0; i < ARRAY_SIZE(global_noreturns); i++) | |
169 | if (!strcmp(func->name, global_noreturns[i])) | |
8e25c9f8 | 170 | return true; |
dcc914f4 | 171 | |
13810435 | 172 | if (!func->len) |
8e25c9f8 | 173 | return false; |
dcc914f4 | 174 | |
13810435 JP |
175 | insn = find_insn(file, func->sec, func->offset); |
176 | if (!insn->func) | |
8e25c9f8 | 177 | return false; |
13810435 | 178 | |
f0f70adb | 179 | func_for_each_insn(file, func, insn) { |
dcc914f4 JP |
180 | empty = false; |
181 | ||
182 | if (insn->type == INSN_RETURN) | |
8e25c9f8 | 183 | return false; |
dcc914f4 JP |
184 | } |
185 | ||
186 | if (empty) | |
8e25c9f8 | 187 | return false; |
dcc914f4 JP |
188 | |
189 | /* | |
190 | * A function can have a sibling call instead of a return. In that | |
191 | * case, the function's dead-end status depends on whether the target | |
192 | * of the sibling call returns. | |
193 | */ | |
f0f70adb | 194 | func_for_each_insn(file, func, insn) { |
0c1ddd33 | 195 | if (is_sibling_call(insn)) { |
dcc914f4 | 196 | struct instruction *dest = insn->jump_dest; |
dcc914f4 JP |
197 | |
198 | if (!dest) | |
199 | /* sibling call to another file */ | |
8e25c9f8 | 200 | return false; |
dcc914f4 | 201 | |
0c1ddd33 JP |
202 | /* local sibling call */ |
203 | if (recursion == 5) { | |
204 | /* | |
205 | * Infinite recursion: two functions have | |
206 | * sibling calls to each other. This is a very | |
207 | * rare case. It means they aren't dead ends. | |
208 | */ | |
209 | return false; | |
dcc914f4 | 210 | } |
dcc914f4 | 211 | |
0c1ddd33 JP |
212 | return __dead_end_function(file, dest->func, recursion+1); |
213 | } | |
dcc914f4 JP |
214 | } |
215 | ||
8e25c9f8 | 216 | return true; |
dcc914f4 JP |
217 | } |
218 | ||
8e25c9f8 | 219 | static bool dead_end_function(struct objtool_file *file, struct symbol *func) |
dcc914f4 JP |
220 | { |
221 | return __dead_end_function(file, func, 0); | |
222 | } | |
223 | ||
e7c0219b | 224 | static void init_cfi_state(struct cfi_state *cfi) |
baa41469 JP |
225 | { |
226 | int i; | |
227 | ||
dd88a0a0 | 228 | for (i = 0; i < CFI_NUM_REGS; i++) { |
e7c0219b PZ |
229 | cfi->regs[i].base = CFI_UNDEFINED; |
230 | cfi->vals[i].base = CFI_UNDEFINED; | |
dd88a0a0 | 231 | } |
e7c0219b PZ |
232 | cfi->cfa.base = CFI_UNDEFINED; |
233 | cfi->drap_reg = CFI_UNDEFINED; | |
234 | cfi->drap_offset = -1; | |
235 | } | |
236 | ||
932f8e98 | 237 | static void init_insn_state(struct insn_state *state, struct section *sec) |
e7c0219b PZ |
238 | { |
239 | memset(state, 0, sizeof(*state)); | |
240 | init_cfi_state(&state->cfi); | |
932f8e98 PZ |
241 | |
242 | /* | |
243 | * We need the full vmlinux for noinstr validation, otherwise we can | |
244 | * not correctly determine insn->call_dest->sec (external symbols do | |
245 | * not have a section). | |
246 | */ | |
247 | if (vmlinux && sec) | |
248 | state->noinstr = sec->noinstr; | |
baa41469 JP |
249 | } |
250 | ||
dcc914f4 JP |
251 | /* |
252 | * Call the arch-specific instruction decoder for all the instructions and add | |
253 | * them to the global instruction list. | |
254 | */ | |
255 | static int decode_instructions(struct objtool_file *file) | |
256 | { | |
257 | struct section *sec; | |
258 | struct symbol *func; | |
259 | unsigned long offset; | |
260 | struct instruction *insn; | |
1e11f3fd | 261 | unsigned long nr_insns = 0; |
dcc914f4 JP |
262 | int ret; |
263 | ||
baa41469 | 264 | for_each_sec(file, sec) { |
dcc914f4 JP |
265 | |
266 | if (!(sec->sh.sh_flags & SHF_EXECINSTR)) | |
267 | continue; | |
268 | ||
627fce14 JP |
269 | if (strcmp(sec->name, ".altinstr_replacement") && |
270 | strcmp(sec->name, ".altinstr_aux") && | |
271 | strncmp(sec->name, ".discard.", 9)) | |
272 | sec->text = true; | |
273 | ||
0cc9ac8d TG |
274 | if (!strcmp(sec->name, ".noinstr.text") || |
275 | !strcmp(sec->name, ".entry.text")) | |
c4a33939 PZ |
276 | sec->noinstr = true; |
277 | ||
dcc914f4 JP |
278 | for (offset = 0; offset < sec->len; offset += insn->len) { |
279 | insn = malloc(sizeof(*insn)); | |
baa41469 JP |
280 | if (!insn) { |
281 | WARN("malloc failed"); | |
282 | return -1; | |
283 | } | |
dcc914f4 | 284 | memset(insn, 0, sizeof(*insn)); |
dcc914f4 | 285 | INIT_LIST_HEAD(&insn->alts); |
65ea47dc | 286 | INIT_LIST_HEAD(&insn->stack_ops); |
e7c0219b | 287 | init_cfi_state(&insn->cfi); |
baa41469 | 288 | |
dcc914f4 JP |
289 | insn->sec = sec; |
290 | insn->offset = offset; | |
291 | ||
292 | ret = arch_decode_instruction(file->elf, sec, offset, | |
293 | sec->len - offset, | |
294 | &insn->len, &insn->type, | |
baa41469 | 295 | &insn->immediate, |
65ea47dc | 296 | &insn->stack_ops); |
dcc914f4 | 297 | if (ret) |
b7037983 | 298 | goto err; |
dcc914f4 | 299 | |
87ecb582 | 300 | hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset)); |
dcc914f4 | 301 | list_add_tail(&insn->list, &file->insn_list); |
1e11f3fd | 302 | nr_insns++; |
dcc914f4 JP |
303 | } |
304 | ||
305 | list_for_each_entry(func, &sec->symbol_list, list) { | |
e10cd8fe | 306 | if (func->type != STT_FUNC || func->alias != func) |
dcc914f4 JP |
307 | continue; |
308 | ||
309 | if (!find_insn(file, sec, func->offset)) { | |
310 | WARN("%s(): can't find starting instruction", | |
311 | func->name); | |
312 | return -1; | |
313 | } | |
314 | ||
dbf4aeb0 | 315 | sym_for_each_insn(file, func, insn) |
e10cd8fe | 316 | insn->func = func; |
dcc914f4 JP |
317 | } |
318 | } | |
319 | ||
1e11f3fd PZ |
320 | if (stats) |
321 | printf("nr_insns: %lu\n", nr_insns); | |
322 | ||
dcc914f4 | 323 | return 0; |
b7037983 KB |
324 | |
325 | err: | |
326 | free(insn); | |
327 | return ret; | |
dcc914f4 JP |
328 | } |
329 | ||
6b5dd716 ST |
330 | static struct instruction *find_last_insn(struct objtool_file *file, |
331 | struct section *sec) | |
332 | { | |
333 | struct instruction *insn = NULL; | |
334 | unsigned int offset; | |
335 | unsigned int end = (sec->len > 10) ? sec->len - 10 : 0; | |
336 | ||
337 | for (offset = sec->len - 1; offset >= end && !insn; offset--) | |
338 | insn = find_insn(file, sec, offset); | |
339 | ||
340 | return insn; | |
341 | } | |
342 | ||
dcc914f4 | 343 | /* |
649ea4d5 | 344 | * Mark "ud2" instructions and manually annotated dead ends. |
dcc914f4 JP |
345 | */ |
346 | static int add_dead_ends(struct objtool_file *file) | |
347 | { | |
348 | struct section *sec; | |
f1974222 | 349 | struct reloc *reloc; |
dcc914f4 | 350 | struct instruction *insn; |
dcc914f4 | 351 | |
649ea4d5 JP |
352 | /* |
353 | * By default, "ud2" is a dead end unless otherwise annotated, because | |
354 | * GCC 7 inserts it for certain divide-by-zero cases. | |
355 | */ | |
356 | for_each_insn(file, insn) | |
357 | if (insn->type == INSN_BUG) | |
358 | insn->dead_end = true; | |
359 | ||
360 | /* | |
361 | * Check for manually annotated dead ends. | |
362 | */ | |
dcc914f4 JP |
363 | sec = find_section_by_name(file->elf, ".rela.discard.unreachable"); |
364 | if (!sec) | |
649ea4d5 | 365 | goto reachable; |
dcc914f4 | 366 | |
f1974222 MH |
367 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
368 | if (reloc->sym->type != STT_SECTION) { | |
dcc914f4 JP |
369 | WARN("unexpected relocation symbol type in %s", sec->name); |
370 | return -1; | |
371 | } | |
f1974222 | 372 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
dcc914f4 JP |
373 | if (insn) |
374 | insn = list_prev_entry(insn, list); | |
f1974222 MH |
375 | else if (reloc->addend == reloc->sym->sec->len) { |
376 | insn = find_last_insn(file, reloc->sym->sec); | |
6b5dd716 | 377 | if (!insn) { |
dcc914f4 | 378 | WARN("can't find unreachable insn at %s+0x%x", |
f1974222 | 379 | reloc->sym->sec->name, reloc->addend); |
dcc914f4 JP |
380 | return -1; |
381 | } | |
382 | } else { | |
383 | WARN("can't find unreachable insn at %s+0x%x", | |
f1974222 | 384 | reloc->sym->sec->name, reloc->addend); |
dcc914f4 JP |
385 | return -1; |
386 | } | |
387 | ||
388 | insn->dead_end = true; | |
389 | } | |
390 | ||
649ea4d5 JP |
391 | reachable: |
392 | /* | |
393 | * These manually annotated reachable checks are needed for GCC 4.4, | |
394 | * where the Linux unreachable() macro isn't supported. In that case | |
395 | * GCC doesn't know the "ud2" is fatal, so it generates code as if it's | |
396 | * not a dead end. | |
397 | */ | |
398 | sec = find_section_by_name(file->elf, ".rela.discard.reachable"); | |
399 | if (!sec) | |
400 | return 0; | |
401 | ||
f1974222 MH |
402 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
403 | if (reloc->sym->type != STT_SECTION) { | |
649ea4d5 JP |
404 | WARN("unexpected relocation symbol type in %s", sec->name); |
405 | return -1; | |
406 | } | |
f1974222 | 407 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
649ea4d5 JP |
408 | if (insn) |
409 | insn = list_prev_entry(insn, list); | |
f1974222 MH |
410 | else if (reloc->addend == reloc->sym->sec->len) { |
411 | insn = find_last_insn(file, reloc->sym->sec); | |
6b5dd716 | 412 | if (!insn) { |
649ea4d5 | 413 | WARN("can't find reachable insn at %s+0x%x", |
f1974222 | 414 | reloc->sym->sec->name, reloc->addend); |
649ea4d5 JP |
415 | return -1; |
416 | } | |
417 | } else { | |
418 | WARN("can't find reachable insn at %s+0x%x", | |
f1974222 | 419 | reloc->sym->sec->name, reloc->addend); |
649ea4d5 JP |
420 | return -1; |
421 | } | |
422 | ||
423 | insn->dead_end = false; | |
424 | } | |
425 | ||
dcc914f4 JP |
426 | return 0; |
427 | } | |
428 | ||
1e7e4788 JP |
429 | static int create_static_call_sections(struct objtool_file *file) |
430 | { | |
431 | struct section *sec, *reloc_sec; | |
432 | struct reloc *reloc; | |
433 | struct static_call_site *site; | |
434 | struct instruction *insn; | |
435 | struct symbol *key_sym; | |
436 | char *key_name, *tmp; | |
437 | int idx; | |
438 | ||
439 | sec = find_section_by_name(file->elf, ".static_call_sites"); | |
440 | if (sec) { | |
441 | INIT_LIST_HEAD(&file->static_call_list); | |
442 | WARN("file already has .static_call_sites section, skipping"); | |
443 | return 0; | |
444 | } | |
445 | ||
446 | if (list_empty(&file->static_call_list)) | |
447 | return 0; | |
448 | ||
449 | idx = 0; | |
450 | list_for_each_entry(insn, &file->static_call_list, static_call_node) | |
451 | idx++; | |
452 | ||
453 | sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE, | |
454 | sizeof(struct static_call_site), idx); | |
455 | if (!sec) | |
456 | return -1; | |
457 | ||
458 | reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA); | |
459 | if (!reloc_sec) | |
460 | return -1; | |
461 | ||
462 | idx = 0; | |
463 | list_for_each_entry(insn, &file->static_call_list, static_call_node) { | |
464 | ||
465 | site = (struct static_call_site *)sec->data->d_buf + idx; | |
466 | memset(site, 0, sizeof(struct static_call_site)); | |
467 | ||
468 | /* populate reloc for 'addr' */ | |
469 | reloc = malloc(sizeof(*reloc)); | |
470 | if (!reloc) { | |
471 | perror("malloc"); | |
472 | return -1; | |
473 | } | |
474 | memset(reloc, 0, sizeof(*reloc)); | |
475 | reloc->sym = insn->sec->sym; | |
476 | reloc->addend = insn->offset; | |
477 | reloc->type = R_X86_64_PC32; | |
478 | reloc->offset = idx * sizeof(struct static_call_site); | |
479 | reloc->sec = reloc_sec; | |
480 | elf_add_reloc(file->elf, reloc); | |
481 | ||
482 | /* find key symbol */ | |
483 | key_name = strdup(insn->call_dest->name); | |
484 | if (!key_name) { | |
485 | perror("strdup"); | |
486 | return -1; | |
487 | } | |
488 | if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR, | |
489 | STATIC_CALL_TRAMP_PREFIX_LEN)) { | |
490 | WARN("static_call: trampoline name malformed: %s", key_name); | |
491 | return -1; | |
492 | } | |
493 | tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN; | |
494 | memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN); | |
495 | ||
496 | key_sym = find_symbol_by_name(file->elf, tmp); | |
497 | if (!key_sym) { | |
498 | WARN("static_call: can't find static_call_key symbol: %s", tmp); | |
499 | return -1; | |
500 | } | |
501 | free(key_name); | |
502 | ||
503 | /* populate reloc for 'key' */ | |
504 | reloc = malloc(sizeof(*reloc)); | |
505 | if (!reloc) { | |
506 | perror("malloc"); | |
507 | return -1; | |
508 | } | |
509 | memset(reloc, 0, sizeof(*reloc)); | |
510 | reloc->sym = key_sym; | |
5b06fd3b | 511 | reloc->addend = is_sibling_call(insn) ? STATIC_CALL_SITE_TAIL : 0; |
1e7e4788 JP |
512 | reloc->type = R_X86_64_PC32; |
513 | reloc->offset = idx * sizeof(struct static_call_site) + 4; | |
514 | reloc->sec = reloc_sec; | |
515 | elf_add_reloc(file->elf, reloc); | |
516 | ||
517 | idx++; | |
518 | } | |
519 | ||
520 | if (elf_rebuild_reloc_section(file->elf, reloc_sec)) | |
521 | return -1; | |
522 | ||
523 | return 0; | |
524 | } | |
525 | ||
dcc914f4 JP |
526 | /* |
527 | * Warnings shouldn't be reported for ignored functions. | |
528 | */ | |
529 | static void add_ignores(struct objtool_file *file) | |
530 | { | |
531 | struct instruction *insn; | |
532 | struct section *sec; | |
533 | struct symbol *func; | |
f1974222 | 534 | struct reloc *reloc; |
dcc914f4 | 535 | |
aaf5c623 PZ |
536 | sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard"); |
537 | if (!sec) | |
538 | return; | |
dcc914f4 | 539 | |
f1974222 MH |
540 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
541 | switch (reloc->sym->type) { | |
aaf5c623 | 542 | case STT_FUNC: |
f1974222 | 543 | func = reloc->sym; |
aaf5c623 PZ |
544 | break; |
545 | ||
546 | case STT_SECTION: | |
f1974222 | 547 | func = find_func_by_offset(reloc->sym->sec, reloc->addend); |
7acfe531 | 548 | if (!func) |
dcc914f4 | 549 | continue; |
aaf5c623 | 550 | break; |
dcc914f4 | 551 | |
aaf5c623 | 552 | default: |
f1974222 | 553 | WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type); |
aaf5c623 | 554 | continue; |
dcc914f4 | 555 | } |
aaf5c623 | 556 | |
f0f70adb | 557 | func_for_each_insn(file, func, insn) |
aaf5c623 | 558 | insn->ignore = true; |
dcc914f4 JP |
559 | } |
560 | } | |
561 | ||
ea24213d PZ |
562 | /* |
563 | * This is a whitelist of functions that is allowed to be called with AC set. | |
564 | * The list is meant to be minimal and only contains compiler instrumentation | |
565 | * ABI and a few functions used to implement *_{to,from}_user() functions. | |
566 | * | |
567 | * These functions must not directly change AC, but may PUSHF/POPF. | |
568 | */ | |
569 | static const char *uaccess_safe_builtin[] = { | |
570 | /* KASAN */ | |
571 | "kasan_report", | |
572 | "check_memory_region", | |
573 | /* KASAN out-of-line */ | |
574 | "__asan_loadN_noabort", | |
575 | "__asan_load1_noabort", | |
576 | "__asan_load2_noabort", | |
577 | "__asan_load4_noabort", | |
578 | "__asan_load8_noabort", | |
579 | "__asan_load16_noabort", | |
580 | "__asan_storeN_noabort", | |
581 | "__asan_store1_noabort", | |
582 | "__asan_store2_noabort", | |
583 | "__asan_store4_noabort", | |
584 | "__asan_store8_noabort", | |
585 | "__asan_store16_noabort", | |
b0b8e56b JH |
586 | "__kasan_check_read", |
587 | "__kasan_check_write", | |
ea24213d PZ |
588 | /* KASAN in-line */ |
589 | "__asan_report_load_n_noabort", | |
590 | "__asan_report_load1_noabort", | |
591 | "__asan_report_load2_noabort", | |
592 | "__asan_report_load4_noabort", | |
593 | "__asan_report_load8_noabort", | |
594 | "__asan_report_load16_noabort", | |
595 | "__asan_report_store_n_noabort", | |
596 | "__asan_report_store1_noabort", | |
597 | "__asan_report_store2_noabort", | |
598 | "__asan_report_store4_noabort", | |
599 | "__asan_report_store8_noabort", | |
600 | "__asan_report_store16_noabort", | |
5f5c9712 | 601 | /* KCSAN */ |
9967683c | 602 | "__kcsan_check_access", |
5f5c9712 ME |
603 | "kcsan_found_watchpoint", |
604 | "kcsan_setup_watchpoint", | |
9967683c | 605 | "kcsan_check_scoped_accesses", |
50a19ad4 ME |
606 | "kcsan_disable_current", |
607 | "kcsan_enable_current_nowarn", | |
5f5c9712 ME |
608 | /* KCSAN/TSAN */ |
609 | "__tsan_func_entry", | |
610 | "__tsan_func_exit", | |
611 | "__tsan_read_range", | |
612 | "__tsan_write_range", | |
613 | "__tsan_read1", | |
614 | "__tsan_read2", | |
615 | "__tsan_read4", | |
616 | "__tsan_read8", | |
617 | "__tsan_read16", | |
618 | "__tsan_write1", | |
619 | "__tsan_write2", | |
620 | "__tsan_write4", | |
621 | "__tsan_write8", | |
622 | "__tsan_write16", | |
a81b3759 ME |
623 | "__tsan_read_write1", |
624 | "__tsan_read_write2", | |
625 | "__tsan_read_write4", | |
626 | "__tsan_read_write8", | |
627 | "__tsan_read_write16", | |
883957b1 ME |
628 | "__tsan_atomic8_load", |
629 | "__tsan_atomic16_load", | |
630 | "__tsan_atomic32_load", | |
631 | "__tsan_atomic64_load", | |
632 | "__tsan_atomic8_store", | |
633 | "__tsan_atomic16_store", | |
634 | "__tsan_atomic32_store", | |
635 | "__tsan_atomic64_store", | |
636 | "__tsan_atomic8_exchange", | |
637 | "__tsan_atomic16_exchange", | |
638 | "__tsan_atomic32_exchange", | |
639 | "__tsan_atomic64_exchange", | |
640 | "__tsan_atomic8_fetch_add", | |
641 | "__tsan_atomic16_fetch_add", | |
642 | "__tsan_atomic32_fetch_add", | |
643 | "__tsan_atomic64_fetch_add", | |
644 | "__tsan_atomic8_fetch_sub", | |
645 | "__tsan_atomic16_fetch_sub", | |
646 | "__tsan_atomic32_fetch_sub", | |
647 | "__tsan_atomic64_fetch_sub", | |
648 | "__tsan_atomic8_fetch_and", | |
649 | "__tsan_atomic16_fetch_and", | |
650 | "__tsan_atomic32_fetch_and", | |
651 | "__tsan_atomic64_fetch_and", | |
652 | "__tsan_atomic8_fetch_or", | |
653 | "__tsan_atomic16_fetch_or", | |
654 | "__tsan_atomic32_fetch_or", | |
655 | "__tsan_atomic64_fetch_or", | |
656 | "__tsan_atomic8_fetch_xor", | |
657 | "__tsan_atomic16_fetch_xor", | |
658 | "__tsan_atomic32_fetch_xor", | |
659 | "__tsan_atomic64_fetch_xor", | |
660 | "__tsan_atomic8_fetch_nand", | |
661 | "__tsan_atomic16_fetch_nand", | |
662 | "__tsan_atomic32_fetch_nand", | |
663 | "__tsan_atomic64_fetch_nand", | |
664 | "__tsan_atomic8_compare_exchange_strong", | |
665 | "__tsan_atomic16_compare_exchange_strong", | |
666 | "__tsan_atomic32_compare_exchange_strong", | |
667 | "__tsan_atomic64_compare_exchange_strong", | |
668 | "__tsan_atomic8_compare_exchange_weak", | |
669 | "__tsan_atomic16_compare_exchange_weak", | |
670 | "__tsan_atomic32_compare_exchange_weak", | |
671 | "__tsan_atomic64_compare_exchange_weak", | |
672 | "__tsan_atomic8_compare_exchange_val", | |
673 | "__tsan_atomic16_compare_exchange_val", | |
674 | "__tsan_atomic32_compare_exchange_val", | |
675 | "__tsan_atomic64_compare_exchange_val", | |
676 | "__tsan_atomic_thread_fence", | |
677 | "__tsan_atomic_signal_fence", | |
ea24213d PZ |
678 | /* KCOV */ |
679 | "write_comp_data", | |
ae033f08 | 680 | "check_kcov_mode", |
ea24213d PZ |
681 | "__sanitizer_cov_trace_pc", |
682 | "__sanitizer_cov_trace_const_cmp1", | |
683 | "__sanitizer_cov_trace_const_cmp2", | |
684 | "__sanitizer_cov_trace_const_cmp4", | |
685 | "__sanitizer_cov_trace_const_cmp8", | |
686 | "__sanitizer_cov_trace_cmp1", | |
687 | "__sanitizer_cov_trace_cmp2", | |
688 | "__sanitizer_cov_trace_cmp4", | |
689 | "__sanitizer_cov_trace_cmp8", | |
36b1c700 | 690 | "__sanitizer_cov_trace_switch", |
ea24213d PZ |
691 | /* UBSAN */ |
692 | "ubsan_type_mismatch_common", | |
693 | "__ubsan_handle_type_mismatch", | |
694 | "__ubsan_handle_type_mismatch_v1", | |
9a50dcaf | 695 | "__ubsan_handle_shift_out_of_bounds", |
ea24213d PZ |
696 | /* misc */ |
697 | "csum_partial_copy_generic", | |
ec6347bb DW |
698 | "copy_mc_fragile", |
699 | "copy_mc_fragile_handle_tail", | |
5da8e4a6 | 700 | "copy_mc_enhanced_fast_string", |
ea24213d PZ |
701 | "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */ |
702 | NULL | |
703 | }; | |
704 | ||
705 | static void add_uaccess_safe(struct objtool_file *file) | |
706 | { | |
707 | struct symbol *func; | |
708 | const char **name; | |
709 | ||
710 | if (!uaccess) | |
711 | return; | |
712 | ||
713 | for (name = uaccess_safe_builtin; *name; name++) { | |
714 | func = find_symbol_by_name(file->elf, *name); | |
715 | if (!func) | |
716 | continue; | |
717 | ||
e10cd8fe | 718 | func->uaccess_safe = true; |
dcc914f4 JP |
719 | } |
720 | } | |
721 | ||
258c7605 JP |
722 | /* |
723 | * FIXME: For now, just ignore any alternatives which add retpolines. This is | |
724 | * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline. | |
725 | * But it at least allows objtool to understand the control flow *around* the | |
726 | * retpoline. | |
727 | */ | |
ff05ab23 | 728 | static int add_ignore_alternatives(struct objtool_file *file) |
258c7605 JP |
729 | { |
730 | struct section *sec; | |
f1974222 | 731 | struct reloc *reloc; |
258c7605 JP |
732 | struct instruction *insn; |
733 | ||
ff05ab23 | 734 | sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts"); |
258c7605 JP |
735 | if (!sec) |
736 | return 0; | |
737 | ||
f1974222 MH |
738 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
739 | if (reloc->sym->type != STT_SECTION) { | |
258c7605 JP |
740 | WARN("unexpected relocation symbol type in %s", sec->name); |
741 | return -1; | |
742 | } | |
743 | ||
f1974222 | 744 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
258c7605 | 745 | if (!insn) { |
ff05ab23 | 746 | WARN("bad .discard.ignore_alts entry"); |
258c7605 JP |
747 | return -1; |
748 | } | |
749 | ||
750 | insn->ignore_alts = true; | |
751 | } | |
752 | ||
753 | return 0; | |
754 | } | |
755 | ||
dcc914f4 JP |
756 | /* |
757 | * Find the destination instructions for all jumps. | |
758 | */ | |
759 | static int add_jump_destinations(struct objtool_file *file) | |
760 | { | |
761 | struct instruction *insn; | |
f1974222 | 762 | struct reloc *reloc; |
dcc914f4 JP |
763 | struct section *dest_sec; |
764 | unsigned long dest_off; | |
765 | ||
766 | for_each_insn(file, insn) { | |
a2296140 | 767 | if (!is_static_jump(insn)) |
dcc914f4 JP |
768 | continue; |
769 | ||
db6c6a0d | 770 | if (insn->offset == FAKE_JUMP_OFFSET) |
dcc914f4 JP |
771 | continue; |
772 | ||
f1974222 | 773 | reloc = find_reloc_by_dest_range(file->elf, insn->sec, |
8b5fa6bc | 774 | insn->offset, insn->len); |
f1974222 | 775 | if (!reloc) { |
dcc914f4 | 776 | dest_sec = insn->sec; |
bfb08f22 | 777 | dest_off = arch_jump_destination(insn); |
f1974222 MH |
778 | } else if (reloc->sym->type == STT_SECTION) { |
779 | dest_sec = reloc->sym->sec; | |
780 | dest_off = arch_dest_reloc_offset(reloc->addend); | |
781 | } else if (reloc->sym->sec->idx) { | |
782 | dest_sec = reloc->sym->sec; | |
783 | dest_off = reloc->sym->sym.st_value + | |
784 | arch_dest_reloc_offset(reloc->addend); | |
785 | } else if (strstr(reloc->sym->name, "_indirect_thunk_")) { | |
39b73533 JP |
786 | /* |
787 | * Retpoline jumps are really dynamic jumps in | |
788 | * disguise, so convert them accordingly. | |
789 | */ | |
b68b9907 JP |
790 | if (insn->type == INSN_JUMP_UNCONDITIONAL) |
791 | insn->type = INSN_JUMP_DYNAMIC; | |
792 | else | |
793 | insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL; | |
794 | ||
b5bc2231 | 795 | insn->retpoline_safe = true; |
39b73533 | 796 | continue; |
dcc914f4 | 797 | } else { |
0c1ddd33 | 798 | /* external sibling call */ |
f1974222 | 799 | insn->call_dest = reloc->sym; |
5b06fd3b PZ |
800 | if (insn->call_dest->static_call_tramp) { |
801 | list_add_tail(&insn->static_call_node, | |
802 | &file->static_call_list); | |
803 | } | |
dcc914f4 JP |
804 | continue; |
805 | } | |
806 | ||
807 | insn->jump_dest = find_insn(file, dest_sec, dest_off); | |
808 | if (!insn->jump_dest) { | |
809 | ||
810 | /* | |
811 | * This is a special case where an alt instruction | |
812 | * jumps past the end of the section. These are | |
813 | * handled later in handle_group_alt(). | |
814 | */ | |
815 | if (!strcmp(insn->sec->name, ".altinstr_replacement")) | |
816 | continue; | |
817 | ||
818 | WARN_FUNC("can't find jump dest instruction at %s+0x%lx", | |
819 | insn->sec, insn->offset, dest_sec->name, | |
820 | dest_off); | |
821 | return -1; | |
822 | } | |
cd77849a JP |
823 | |
824 | /* | |
54262aa2 | 825 | * Cross-function jump. |
cd77849a JP |
826 | */ |
827 | if (insn->func && insn->jump_dest->func && | |
54262aa2 PZ |
828 | insn->func != insn->jump_dest->func) { |
829 | ||
830 | /* | |
831 | * For GCC 8+, create parent/child links for any cold | |
832 | * subfunctions. This is _mostly_ redundant with a | |
833 | * similar initialization in read_symbols(). | |
834 | * | |
835 | * If a function has aliases, we want the *first* such | |
836 | * function in the symbol table to be the subfunction's | |
837 | * parent. In that case we overwrite the | |
838 | * initialization done in read_symbols(). | |
839 | * | |
840 | * However this code can't completely replace the | |
841 | * read_symbols() code because this doesn't detect the | |
842 | * case where the parent function's only reference to a | |
e7c2bc37 | 843 | * subfunction is through a jump table. |
54262aa2 PZ |
844 | */ |
845 | if (!strstr(insn->func->name, ".cold.") && | |
846 | strstr(insn->jump_dest->func->name, ".cold.")) { | |
847 | insn->func->cfunc = insn->jump_dest->func; | |
848 | insn->jump_dest->func->pfunc = insn->func; | |
849 | ||
850 | } else if (insn->jump_dest->func->pfunc != insn->func->pfunc && | |
851 | insn->jump_dest->offset == insn->jump_dest->func->offset) { | |
852 | ||
0c1ddd33 | 853 | /* internal sibling call */ |
54262aa2 | 854 | insn->call_dest = insn->jump_dest->func; |
5b06fd3b PZ |
855 | if (insn->call_dest->static_call_tramp) { |
856 | list_add_tail(&insn->static_call_node, | |
857 | &file->static_call_list); | |
858 | } | |
54262aa2 | 859 | } |
cd77849a | 860 | } |
dcc914f4 JP |
861 | } |
862 | ||
863 | return 0; | |
864 | } | |
865 | ||
8aa8eb2a AC |
866 | static void remove_insn_ops(struct instruction *insn) |
867 | { | |
868 | struct stack_op *op, *tmp; | |
869 | ||
870 | list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) { | |
871 | list_del(&op->list); | |
872 | free(op); | |
873 | } | |
874 | } | |
875 | ||
2b232a22 JT |
876 | static struct symbol *find_call_destination(struct section *sec, unsigned long offset) |
877 | { | |
878 | struct symbol *call_dest; | |
879 | ||
880 | call_dest = find_func_by_offset(sec, offset); | |
881 | if (!call_dest) | |
882 | call_dest = find_symbol_by_offset(sec, offset); | |
883 | ||
884 | return call_dest; | |
885 | } | |
886 | ||
dcc914f4 JP |
887 | /* |
888 | * Find the destination instructions for all calls. | |
889 | */ | |
890 | static int add_call_destinations(struct objtool_file *file) | |
891 | { | |
892 | struct instruction *insn; | |
893 | unsigned long dest_off; | |
f1974222 | 894 | struct reloc *reloc; |
dcc914f4 JP |
895 | |
896 | for_each_insn(file, insn) { | |
897 | if (insn->type != INSN_CALL) | |
898 | continue; | |
899 | ||
f1974222 | 900 | reloc = find_reloc_by_dest_range(file->elf, insn->sec, |
8b5fa6bc | 901 | insn->offset, insn->len); |
f1974222 | 902 | if (!reloc) { |
bfb08f22 | 903 | dest_off = arch_jump_destination(insn); |
2b232a22 | 904 | insn->call_dest = find_call_destination(insn->sec, dest_off); |
a845c7cf | 905 | |
7acfe531 JP |
906 | if (insn->ignore) |
907 | continue; | |
908 | ||
909 | if (!insn->call_dest) { | |
8aa8eb2a | 910 | WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset); |
dcc914f4 JP |
911 | return -1; |
912 | } | |
a845c7cf | 913 | |
7acfe531 JP |
914 | if (insn->func && insn->call_dest->type != STT_FUNC) { |
915 | WARN_FUNC("unsupported call to non-function", | |
916 | insn->sec, insn->offset); | |
917 | return -1; | |
918 | } | |
919 | ||
f1974222 MH |
920 | } else if (reloc->sym->type == STT_SECTION) { |
921 | dest_off = arch_dest_reloc_offset(reloc->addend); | |
2b232a22 JT |
922 | insn->call_dest = find_call_destination(reloc->sym->sec, |
923 | dest_off); | |
7acfe531 | 924 | if (!insn->call_dest) { |
bfb08f22 | 925 | WARN_FUNC("can't find call dest symbol at %s+0x%lx", |
dcc914f4 | 926 | insn->sec, insn->offset, |
f1974222 | 927 | reloc->sym->sec->name, |
bfb08f22 | 928 | dest_off); |
dcc914f4 JP |
929 | return -1; |
930 | } | |
931 | } else | |
f1974222 | 932 | insn->call_dest = reloc->sym; |
8aa8eb2a | 933 | |
0f1441b4 PZ |
934 | /* |
935 | * Many compilers cannot disable KCOV with a function attribute | |
936 | * so they need a little help, NOP out any KCOV calls from noinstr | |
937 | * text. | |
938 | */ | |
939 | if (insn->sec->noinstr && | |
940 | !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) { | |
d832c005 PZ |
941 | if (reloc) { |
942 | reloc->type = R_NONE; | |
943 | elf_write_reloc(file->elf, reloc); | |
0f1441b4 PZ |
944 | } |
945 | ||
946 | elf_write_insn(file->elf, insn->sec, | |
947 | insn->offset, insn->len, | |
948 | arch_nop_insn(insn->len)); | |
949 | insn->type = INSN_NOP; | |
950 | } | |
951 | ||
8aa8eb2a AC |
952 | /* |
953 | * Whatever stack impact regular CALLs have, should be undone | |
954 | * by the RETURN of the called function. | |
955 | * | |
956 | * Annotated intra-function calls retain the stack_ops but | |
957 | * are converted to JUMP, see read_intra_function_calls(). | |
958 | */ | |
959 | remove_insn_ops(insn); | |
dcc914f4 JP |
960 | } |
961 | ||
962 | return 0; | |
963 | } | |
964 | ||
965 | /* | |
966 | * The .alternatives section requires some extra special care, over and above | |
967 | * what other special sections require: | |
968 | * | |
969 | * 1. Because alternatives are patched in-place, we need to insert a fake jump | |
970 | * instruction at the end so that validate_branch() skips all the original | |
971 | * replaced instructions when validating the new instruction path. | |
972 | * | |
973 | * 2. An added wrinkle is that the new instruction length might be zero. In | |
974 | * that case the old instructions are replaced with noops. We simulate that | |
975 | * by creating a fake jump as the only new instruction. | |
976 | * | |
977 | * 3. In some cases, the alternative section includes an instruction which | |
978 | * conditionally jumps to the _end_ of the entry. We have to modify these | |
979 | * jumps' destinations to point back to .text rather than the end of the | |
980 | * entry in .altinstr_replacement. | |
dcc914f4 JP |
981 | */ |
982 | static int handle_group_alt(struct objtool_file *file, | |
983 | struct special_alt *special_alt, | |
984 | struct instruction *orig_insn, | |
985 | struct instruction **new_insn) | |
986 | { | |
13fab06d | 987 | static unsigned int alt_group_next_index = 1; |
17bc3391 | 988 | struct instruction *last_orig_insn, *last_new_insn, *insn, *fake_jump = NULL; |
13fab06d | 989 | unsigned int alt_group = alt_group_next_index++; |
dcc914f4 JP |
990 | unsigned long dest_off; |
991 | ||
992 | last_orig_insn = NULL; | |
993 | insn = orig_insn; | |
994 | sec_for_each_insn_from(file, insn) { | |
995 | if (insn->offset >= special_alt->orig_off + special_alt->orig_len) | |
996 | break; | |
997 | ||
13fab06d | 998 | insn->alt_group = alt_group; |
dcc914f4 JP |
999 | last_orig_insn = insn; |
1000 | } | |
1001 | ||
17bc3391 JP |
1002 | if (next_insn_same_sec(file, last_orig_insn)) { |
1003 | fake_jump = malloc(sizeof(*fake_jump)); | |
1004 | if (!fake_jump) { | |
1005 | WARN("malloc failed"); | |
1006 | return -1; | |
1007 | } | |
1008 | memset(fake_jump, 0, sizeof(*fake_jump)); | |
1009 | INIT_LIST_HEAD(&fake_jump->alts); | |
65ea47dc | 1010 | INIT_LIST_HEAD(&fake_jump->stack_ops); |
e7c0219b | 1011 | init_cfi_state(&fake_jump->cfi); |
17bc3391 JP |
1012 | |
1013 | fake_jump->sec = special_alt->new_sec; | |
e6da9567 | 1014 | fake_jump->offset = FAKE_JUMP_OFFSET; |
17bc3391 JP |
1015 | fake_jump->type = INSN_JUMP_UNCONDITIONAL; |
1016 | fake_jump->jump_dest = list_next_entry(last_orig_insn, list); | |
e6da9567 | 1017 | fake_jump->func = orig_insn->func; |
dcc914f4 | 1018 | } |
dcc914f4 JP |
1019 | |
1020 | if (!special_alt->new_len) { | |
17bc3391 JP |
1021 | if (!fake_jump) { |
1022 | WARN("%s: empty alternative at end of section", | |
1023 | special_alt->orig_sec->name); | |
1024 | return -1; | |
1025 | } | |
1026 | ||
dcc914f4 JP |
1027 | *new_insn = fake_jump; |
1028 | return 0; | |
1029 | } | |
1030 | ||
1031 | last_new_insn = NULL; | |
13fab06d | 1032 | alt_group = alt_group_next_index++; |
dcc914f4 JP |
1033 | insn = *new_insn; |
1034 | sec_for_each_insn_from(file, insn) { | |
45245f51 JT |
1035 | struct reloc *alt_reloc; |
1036 | ||
dcc914f4 JP |
1037 | if (insn->offset >= special_alt->new_off + special_alt->new_len) |
1038 | break; | |
1039 | ||
1040 | last_new_insn = insn; | |
1041 | ||
a845c7cf | 1042 | insn->ignore = orig_insn->ignore_alts; |
a4d09dde | 1043 | insn->func = orig_insn->func; |
13fab06d | 1044 | insn->alt_group = alt_group; |
a845c7cf | 1045 | |
dc419723 JP |
1046 | /* |
1047 | * Since alternative replacement code is copy/pasted by the | |
1048 | * kernel after applying relocations, generally such code can't | |
1049 | * have relative-address relocation references to outside the | |
1050 | * .altinstr_replacement section, unless the arch's | |
1051 | * alternatives code can adjust the relative offsets | |
1052 | * accordingly. | |
dc419723 | 1053 | */ |
45245f51 JT |
1054 | alt_reloc = find_reloc_by_dest_range(file->elf, insn->sec, |
1055 | insn->offset, insn->len); | |
1056 | if (alt_reloc && | |
1057 | !arch_support_alt_relocation(special_alt, insn, alt_reloc)) { | |
dc419723 JP |
1058 | |
1059 | WARN_FUNC("unsupported relocation in alternatives section", | |
1060 | insn->sec, insn->offset); | |
1061 | return -1; | |
1062 | } | |
1063 | ||
a2296140 | 1064 | if (!is_static_jump(insn)) |
dcc914f4 JP |
1065 | continue; |
1066 | ||
1067 | if (!insn->immediate) | |
1068 | continue; | |
1069 | ||
bfb08f22 | 1070 | dest_off = arch_jump_destination(insn); |
17bc3391 JP |
1071 | if (dest_off == special_alt->new_off + special_alt->new_len) { |
1072 | if (!fake_jump) { | |
1073 | WARN("%s: alternative jump to end of section", | |
1074 | special_alt->orig_sec->name); | |
1075 | return -1; | |
1076 | } | |
dcc914f4 | 1077 | insn->jump_dest = fake_jump; |
17bc3391 | 1078 | } |
dcc914f4 JP |
1079 | |
1080 | if (!insn->jump_dest) { | |
1081 | WARN_FUNC("can't find alternative jump destination", | |
1082 | insn->sec, insn->offset); | |
1083 | return -1; | |
1084 | } | |
1085 | } | |
1086 | ||
1087 | if (!last_new_insn) { | |
1088 | WARN_FUNC("can't find last new alternative instruction", | |
1089 | special_alt->new_sec, special_alt->new_off); | |
1090 | return -1; | |
1091 | } | |
1092 | ||
17bc3391 JP |
1093 | if (fake_jump) |
1094 | list_add(&fake_jump->list, &last_new_insn->list); | |
dcc914f4 JP |
1095 | |
1096 | return 0; | |
1097 | } | |
1098 | ||
1099 | /* | |
1100 | * A jump table entry can either convert a nop to a jump or a jump to a nop. | |
1101 | * If the original instruction is a jump, make the alt entry an effective nop | |
1102 | * by just skipping the original instruction. | |
1103 | */ | |
1104 | static int handle_jump_alt(struct objtool_file *file, | |
1105 | struct special_alt *special_alt, | |
1106 | struct instruction *orig_insn, | |
1107 | struct instruction **new_insn) | |
1108 | { | |
1109 | if (orig_insn->type == INSN_NOP) | |
1110 | return 0; | |
1111 | ||
1112 | if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) { | |
1113 | WARN_FUNC("unsupported instruction at jump label", | |
1114 | orig_insn->sec, orig_insn->offset); | |
1115 | return -1; | |
1116 | } | |
1117 | ||
1118 | *new_insn = list_next_entry(orig_insn, list); | |
1119 | return 0; | |
1120 | } | |
1121 | ||
1122 | /* | |
1123 | * Read all the special sections which have alternate instructions which can be | |
1124 | * patched in or redirected to at runtime. Each instruction having alternate | |
1125 | * instruction(s) has them added to its insn->alts list, which will be | |
1126 | * traversed in validate_branch(). | |
1127 | */ | |
1128 | static int add_special_section_alts(struct objtool_file *file) | |
1129 | { | |
1130 | struct list_head special_alts; | |
1131 | struct instruction *orig_insn, *new_insn; | |
1132 | struct special_alt *special_alt, *tmp; | |
1133 | struct alternative *alt; | |
1134 | int ret; | |
1135 | ||
1136 | ret = special_get_alts(file->elf, &special_alts); | |
1137 | if (ret) | |
1138 | return ret; | |
1139 | ||
1140 | list_for_each_entry_safe(special_alt, tmp, &special_alts, list) { | |
dcc914f4 JP |
1141 | |
1142 | orig_insn = find_insn(file, special_alt->orig_sec, | |
1143 | special_alt->orig_off); | |
1144 | if (!orig_insn) { | |
1145 | WARN_FUNC("special: can't find orig instruction", | |
1146 | special_alt->orig_sec, special_alt->orig_off); | |
1147 | ret = -1; | |
1148 | goto out; | |
1149 | } | |
1150 | ||
1151 | new_insn = NULL; | |
1152 | if (!special_alt->group || special_alt->new_len) { | |
1153 | new_insn = find_insn(file, special_alt->new_sec, | |
1154 | special_alt->new_off); | |
1155 | if (!new_insn) { | |
1156 | WARN_FUNC("special: can't find new instruction", | |
1157 | special_alt->new_sec, | |
1158 | special_alt->new_off); | |
1159 | ret = -1; | |
1160 | goto out; | |
1161 | } | |
1162 | } | |
1163 | ||
1164 | if (special_alt->group) { | |
7170cf47 JT |
1165 | if (!special_alt->orig_len) { |
1166 | WARN_FUNC("empty alternative entry", | |
1167 | orig_insn->sec, orig_insn->offset); | |
1168 | continue; | |
1169 | } | |
1170 | ||
dcc914f4 JP |
1171 | ret = handle_group_alt(file, special_alt, orig_insn, |
1172 | &new_insn); | |
1173 | if (ret) | |
1174 | goto out; | |
1175 | } else if (special_alt->jump_or_nop) { | |
1176 | ret = handle_jump_alt(file, special_alt, orig_insn, | |
1177 | &new_insn); | |
1178 | if (ret) | |
1179 | goto out; | |
1180 | } | |
1181 | ||
258c7605 JP |
1182 | alt = malloc(sizeof(*alt)); |
1183 | if (!alt) { | |
1184 | WARN("malloc failed"); | |
1185 | ret = -1; | |
1186 | goto out; | |
1187 | } | |
1188 | ||
dcc914f4 | 1189 | alt->insn = new_insn; |
764eef4b | 1190 | alt->skip_orig = special_alt->skip_orig; |
ea24213d | 1191 | orig_insn->ignore_alts |= special_alt->skip_alt; |
dcc914f4 JP |
1192 | list_add_tail(&alt->list, &orig_insn->alts); |
1193 | ||
1194 | list_del(&special_alt->list); | |
1195 | free(special_alt); | |
1196 | } | |
1197 | ||
1198 | out: | |
1199 | return ret; | |
1200 | } | |
1201 | ||
e7c2bc37 | 1202 | static int add_jump_table(struct objtool_file *file, struct instruction *insn, |
f1974222 | 1203 | struct reloc *table) |
dcc914f4 | 1204 | { |
f1974222 | 1205 | struct reloc *reloc = table; |
e7c2bc37 | 1206 | struct instruction *dest_insn; |
dcc914f4 | 1207 | struct alternative *alt; |
fd35c88b JP |
1208 | struct symbol *pfunc = insn->func->pfunc; |
1209 | unsigned int prev_offset = 0; | |
dcc914f4 | 1210 | |
e7c2bc37 | 1211 | /* |
f1974222 | 1212 | * Each @reloc is a switch table relocation which points to the target |
e7c2bc37 JP |
1213 | * instruction. |
1214 | */ | |
f1974222 | 1215 | list_for_each_entry_from(reloc, &table->sec->reloc_list, list) { |
bd98c813 JH |
1216 | |
1217 | /* Check for the end of the table: */ | |
f1974222 | 1218 | if (reloc != table && reloc->jump_table_start) |
dcc914f4 JP |
1219 | break; |
1220 | ||
e7c2bc37 | 1221 | /* Make sure the table entries are consecutive: */ |
f1974222 | 1222 | if (prev_offset && reloc->offset != prev_offset + 8) |
fd35c88b JP |
1223 | break; |
1224 | ||
1225 | /* Detect function pointers from contiguous objects: */ | |
f1974222 MH |
1226 | if (reloc->sym->sec == pfunc->sec && |
1227 | reloc->addend == pfunc->offset) | |
fd35c88b JP |
1228 | break; |
1229 | ||
f1974222 | 1230 | dest_insn = find_insn(file, reloc->sym->sec, reloc->addend); |
e7c2bc37 | 1231 | if (!dest_insn) |
dcc914f4 JP |
1232 | break; |
1233 | ||
e7c2bc37 | 1234 | /* Make sure the destination is in the same function: */ |
e65050b9 | 1235 | if (!dest_insn->func || dest_insn->func->pfunc != pfunc) |
13810435 | 1236 | break; |
dcc914f4 JP |
1237 | |
1238 | alt = malloc(sizeof(*alt)); | |
1239 | if (!alt) { | |
1240 | WARN("malloc failed"); | |
1241 | return -1; | |
1242 | } | |
1243 | ||
e7c2bc37 | 1244 | alt->insn = dest_insn; |
dcc914f4 | 1245 | list_add_tail(&alt->list, &insn->alts); |
f1974222 | 1246 | prev_offset = reloc->offset; |
fd35c88b JP |
1247 | } |
1248 | ||
1249 | if (!prev_offset) { | |
1250 | WARN_FUNC("can't find switch jump table", | |
1251 | insn->sec, insn->offset); | |
1252 | return -1; | |
dcc914f4 JP |
1253 | } |
1254 | ||
1255 | return 0; | |
1256 | } | |
1257 | ||
1258 | /* | |
d871f7b5 RG |
1259 | * find_jump_table() - Given a dynamic jump, find the switch jump table |
1260 | * associated with it. | |
dcc914f4 | 1261 | */ |
f1974222 | 1262 | static struct reloc *find_jump_table(struct objtool_file *file, |
dcc914f4 JP |
1263 | struct symbol *func, |
1264 | struct instruction *insn) | |
1265 | { | |
d871f7b5 | 1266 | struct reloc *table_reloc; |
113d4bc9 | 1267 | struct instruction *dest_insn, *orig_insn = insn; |
dcc914f4 | 1268 | |
99ce7962 PZ |
1269 | /* |
1270 | * Backward search using the @first_jump_src links, these help avoid | |
1271 | * much of the 'in between' code. Which avoids us getting confused by | |
1272 | * it. | |
1273 | */ | |
7dec80cc | 1274 | for (; |
1119d265 JP |
1275 | insn && insn->func && insn->func->pfunc == func; |
1276 | insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) { | |
99ce7962 | 1277 | |
7dec80cc | 1278 | if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC) |
dcc914f4 JP |
1279 | break; |
1280 | ||
1281 | /* allow small jumps within the range */ | |
1282 | if (insn->type == INSN_JUMP_UNCONDITIONAL && | |
1283 | insn->jump_dest && | |
1284 | (insn->jump_dest->offset <= insn->offset || | |
1285 | insn->jump_dest->offset > orig_insn->offset)) | |
1286 | break; | |
1287 | ||
d871f7b5 | 1288 | table_reloc = arch_find_switch_table(file, insn); |
f1974222 | 1289 | if (!table_reloc) |
e7c2bc37 | 1290 | continue; |
f1974222 | 1291 | dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend); |
113d4bc9 JP |
1292 | if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func) |
1293 | continue; | |
7dec80cc | 1294 | |
f1974222 | 1295 | return table_reloc; |
dcc914f4 JP |
1296 | } |
1297 | ||
1298 | return NULL; | |
1299 | } | |
1300 | ||
bd98c813 JH |
1301 | /* |
1302 | * First pass: Mark the head of each jump table so that in the next pass, | |
1303 | * we know when a given jump table ends and the next one starts. | |
1304 | */ | |
1305 | static void mark_func_jump_tables(struct objtool_file *file, | |
1306 | struct symbol *func) | |
dcc914f4 | 1307 | { |
bd98c813 | 1308 | struct instruction *insn, *last = NULL; |
f1974222 | 1309 | struct reloc *reloc; |
dcc914f4 | 1310 | |
f0f70adb | 1311 | func_for_each_insn(file, func, insn) { |
99ce7962 PZ |
1312 | if (!last) |
1313 | last = insn; | |
1314 | ||
1315 | /* | |
1316 | * Store back-pointers for unconditional forward jumps such | |
e7c2bc37 | 1317 | * that find_jump_table() can back-track using those and |
99ce7962 PZ |
1318 | * avoid some potentially confusing code. |
1319 | */ | |
1320 | if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest && | |
1321 | insn->offset > last->offset && | |
1322 | insn->jump_dest->offset > insn->offset && | |
1323 | !insn->jump_dest->first_jump_src) { | |
1324 | ||
1325 | insn->jump_dest->first_jump_src = insn; | |
1326 | last = insn->jump_dest; | |
1327 | } | |
1328 | ||
dcc914f4 JP |
1329 | if (insn->type != INSN_JUMP_DYNAMIC) |
1330 | continue; | |
1331 | ||
f1974222 MH |
1332 | reloc = find_jump_table(file, func, insn); |
1333 | if (reloc) { | |
1334 | reloc->jump_table_start = true; | |
1335 | insn->jump_table = reloc; | |
dcc914f4 | 1336 | } |
dcc914f4 | 1337 | } |
bd98c813 JH |
1338 | } |
1339 | ||
1340 | static int add_func_jump_tables(struct objtool_file *file, | |
1341 | struct symbol *func) | |
1342 | { | |
1343 | struct instruction *insn; | |
1344 | int ret; | |
1345 | ||
f0f70adb | 1346 | func_for_each_insn(file, func, insn) { |
bd98c813 JH |
1347 | if (!insn->jump_table) |
1348 | continue; | |
dcc914f4 | 1349 | |
bd98c813 | 1350 | ret = add_jump_table(file, insn, insn->jump_table); |
dcc914f4 JP |
1351 | if (ret) |
1352 | return ret; | |
1353 | } | |
1354 | ||
1355 | return 0; | |
1356 | } | |
1357 | ||
1358 | /* | |
1359 | * For some switch statements, gcc generates a jump table in the .rodata | |
1360 | * section which contains a list of addresses within the function to jump to. | |
1361 | * This finds these jump tables and adds them to the insn->alts lists. | |
1362 | */ | |
e7c2bc37 | 1363 | static int add_jump_table_alts(struct objtool_file *file) |
dcc914f4 JP |
1364 | { |
1365 | struct section *sec; | |
1366 | struct symbol *func; | |
1367 | int ret; | |
1368 | ||
4a60aa05 | 1369 | if (!file->rodata) |
dcc914f4 JP |
1370 | return 0; |
1371 | ||
baa41469 | 1372 | for_each_sec(file, sec) { |
dcc914f4 JP |
1373 | list_for_each_entry(func, &sec->symbol_list, list) { |
1374 | if (func->type != STT_FUNC) | |
1375 | continue; | |
1376 | ||
bd98c813 | 1377 | mark_func_jump_tables(file, func); |
e7c2bc37 | 1378 | ret = add_func_jump_tables(file, func); |
dcc914f4 JP |
1379 | if (ret) |
1380 | return ret; | |
1381 | } | |
1382 | } | |
1383 | ||
1384 | return 0; | |
1385 | } | |
1386 | ||
39358a03 JP |
1387 | static int read_unwind_hints(struct objtool_file *file) |
1388 | { | |
f1974222 MH |
1389 | struct section *sec, *relocsec; |
1390 | struct reloc *reloc; | |
39358a03 JP |
1391 | struct unwind_hint *hint; |
1392 | struct instruction *insn; | |
1393 | struct cfi_reg *cfa; | |
1394 | int i; | |
1395 | ||
1396 | sec = find_section_by_name(file->elf, ".discard.unwind_hints"); | |
1397 | if (!sec) | |
1398 | return 0; | |
1399 | ||
f1974222 MH |
1400 | relocsec = sec->reloc; |
1401 | if (!relocsec) { | |
39358a03 JP |
1402 | WARN("missing .rela.discard.unwind_hints section"); |
1403 | return -1; | |
1404 | } | |
1405 | ||
1406 | if (sec->len % sizeof(struct unwind_hint)) { | |
1407 | WARN("struct unwind_hint size mismatch"); | |
1408 | return -1; | |
1409 | } | |
1410 | ||
1411 | file->hints = true; | |
1412 | ||
1413 | for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) { | |
1414 | hint = (struct unwind_hint *)sec->data->d_buf + i; | |
1415 | ||
f1974222 MH |
1416 | reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint)); |
1417 | if (!reloc) { | |
1418 | WARN("can't find reloc for unwind_hints[%d]", i); | |
39358a03 JP |
1419 | return -1; |
1420 | } | |
1421 | ||
f1974222 | 1422 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
39358a03 JP |
1423 | if (!insn) { |
1424 | WARN("can't find insn for unwind_hints[%d]", i); | |
1425 | return -1; | |
1426 | } | |
1427 | ||
e7c0219b | 1428 | cfa = &insn->cfi.cfa; |
39358a03 | 1429 | |
c536ed2f | 1430 | if (hint->type == UNWIND_HINT_TYPE_RET_OFFSET) { |
e25eea89 | 1431 | insn->ret_offset = hint->sp_offset; |
39358a03 JP |
1432 | continue; |
1433 | } | |
1434 | ||
1435 | insn->hint = true; | |
1436 | ||
edea9e6b | 1437 | if (arch_decode_hint_reg(insn, hint->sp_reg)) { |
39358a03 JP |
1438 | WARN_FUNC("unsupported unwind_hint sp base reg %d", |
1439 | insn->sec, insn->offset, hint->sp_reg); | |
1440 | return -1; | |
1441 | } | |
1442 | ||
1443 | cfa->offset = hint->sp_offset; | |
e7c0219b PZ |
1444 | insn->cfi.type = hint->type; |
1445 | insn->cfi.end = hint->end; | |
39358a03 JP |
1446 | } |
1447 | ||
1448 | return 0; | |
1449 | } | |
1450 | ||
b5bc2231 PZ |
1451 | static int read_retpoline_hints(struct objtool_file *file) |
1452 | { | |
63474dc4 | 1453 | struct section *sec; |
b5bc2231 | 1454 | struct instruction *insn; |
f1974222 | 1455 | struct reloc *reloc; |
b5bc2231 | 1456 | |
63474dc4 | 1457 | sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe"); |
b5bc2231 PZ |
1458 | if (!sec) |
1459 | return 0; | |
1460 | ||
f1974222 MH |
1461 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
1462 | if (reloc->sym->type != STT_SECTION) { | |
63474dc4 | 1463 | WARN("unexpected relocation symbol type in %s", sec->name); |
b5bc2231 PZ |
1464 | return -1; |
1465 | } | |
1466 | ||
f1974222 | 1467 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
b5bc2231 | 1468 | if (!insn) { |
63474dc4 | 1469 | WARN("bad .discard.retpoline_safe entry"); |
b5bc2231 PZ |
1470 | return -1; |
1471 | } | |
1472 | ||
1473 | if (insn->type != INSN_JUMP_DYNAMIC && | |
1474 | insn->type != INSN_CALL_DYNAMIC) { | |
63474dc4 | 1475 | WARN_FUNC("retpoline_safe hint not an indirect jump/call", |
b5bc2231 PZ |
1476 | insn->sec, insn->offset); |
1477 | return -1; | |
1478 | } | |
1479 | ||
1480 | insn->retpoline_safe = true; | |
1481 | } | |
1482 | ||
1483 | return 0; | |
1484 | } | |
1485 | ||
c4a33939 PZ |
1486 | static int read_instr_hints(struct objtool_file *file) |
1487 | { | |
1488 | struct section *sec; | |
1489 | struct instruction *insn; | |
f1974222 | 1490 | struct reloc *reloc; |
c4a33939 PZ |
1491 | |
1492 | sec = find_section_by_name(file->elf, ".rela.discard.instr_end"); | |
1493 | if (!sec) | |
1494 | return 0; | |
1495 | ||
f1974222 MH |
1496 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
1497 | if (reloc->sym->type != STT_SECTION) { | |
c4a33939 PZ |
1498 | WARN("unexpected relocation symbol type in %s", sec->name); |
1499 | return -1; | |
1500 | } | |
1501 | ||
f1974222 | 1502 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
c4a33939 PZ |
1503 | if (!insn) { |
1504 | WARN("bad .discard.instr_end entry"); | |
1505 | return -1; | |
1506 | } | |
1507 | ||
1508 | insn->instr--; | |
1509 | } | |
1510 | ||
1511 | sec = find_section_by_name(file->elf, ".rela.discard.instr_begin"); | |
1512 | if (!sec) | |
1513 | return 0; | |
1514 | ||
f1974222 MH |
1515 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
1516 | if (reloc->sym->type != STT_SECTION) { | |
c4a33939 PZ |
1517 | WARN("unexpected relocation symbol type in %s", sec->name); |
1518 | return -1; | |
1519 | } | |
1520 | ||
f1974222 | 1521 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
c4a33939 PZ |
1522 | if (!insn) { |
1523 | WARN("bad .discard.instr_begin entry"); | |
1524 | return -1; | |
1525 | } | |
1526 | ||
1527 | insn->instr++; | |
1528 | } | |
1529 | ||
1530 | return 0; | |
1531 | } | |
1532 | ||
8aa8eb2a AC |
1533 | static int read_intra_function_calls(struct objtool_file *file) |
1534 | { | |
1535 | struct instruction *insn; | |
1536 | struct section *sec; | |
f1974222 | 1537 | struct reloc *reloc; |
8aa8eb2a AC |
1538 | |
1539 | sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls"); | |
1540 | if (!sec) | |
1541 | return 0; | |
1542 | ||
f1974222 | 1543 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
8aa8eb2a AC |
1544 | unsigned long dest_off; |
1545 | ||
f1974222 | 1546 | if (reloc->sym->type != STT_SECTION) { |
8aa8eb2a AC |
1547 | WARN("unexpected relocation symbol type in %s", |
1548 | sec->name); | |
1549 | return -1; | |
1550 | } | |
1551 | ||
f1974222 | 1552 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
8aa8eb2a AC |
1553 | if (!insn) { |
1554 | WARN("bad .discard.intra_function_call entry"); | |
1555 | return -1; | |
1556 | } | |
1557 | ||
1558 | if (insn->type != INSN_CALL) { | |
1559 | WARN_FUNC("intra_function_call not a direct call", | |
1560 | insn->sec, insn->offset); | |
1561 | return -1; | |
1562 | } | |
1563 | ||
1564 | /* | |
1565 | * Treat intra-function CALLs as JMPs, but with a stack_op. | |
1566 | * See add_call_destinations(), which strips stack_ops from | |
1567 | * normal CALLs. | |
1568 | */ | |
1569 | insn->type = INSN_JUMP_UNCONDITIONAL; | |
1570 | ||
1571 | dest_off = insn->offset + insn->len + insn->immediate; | |
1572 | insn->jump_dest = find_insn(file, insn->sec, dest_off); | |
1573 | if (!insn->jump_dest) { | |
1574 | WARN_FUNC("can't find call dest at %s+0x%lx", | |
1575 | insn->sec, insn->offset, | |
1576 | insn->sec->name, dest_off); | |
1577 | return -1; | |
1578 | } | |
1579 | } | |
1580 | ||
1581 | return 0; | |
1582 | } | |
1583 | ||
1e7e4788 JP |
1584 | static int read_static_call_tramps(struct objtool_file *file) |
1585 | { | |
1586 | struct section *sec; | |
1587 | struct symbol *func; | |
1588 | ||
1589 | for_each_sec(file, sec) { | |
1590 | list_for_each_entry(func, &sec->symbol_list, list) { | |
1591 | if (func->bind == STB_GLOBAL && | |
1592 | !strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR, | |
1593 | strlen(STATIC_CALL_TRAMP_PREFIX_STR))) | |
1594 | func->static_call_tramp = true; | |
1595 | } | |
1596 | } | |
1597 | ||
1598 | return 0; | |
1599 | } | |
1600 | ||
4a60aa05 AX |
1601 | static void mark_rodata(struct objtool_file *file) |
1602 | { | |
1603 | struct section *sec; | |
1604 | bool found = false; | |
1605 | ||
1606 | /* | |
87b512de JP |
1607 | * Search for the following rodata sections, each of which can |
1608 | * potentially contain jump tables: | |
1609 | * | |
1610 | * - .rodata: can contain GCC switch tables | |
1611 | * - .rodata.<func>: same, if -fdata-sections is being used | |
1612 | * - .rodata..c_jump_table: contains C annotated jump tables | |
1613 | * | |
1614 | * .rodata.str1.* sections are ignored; they don't contain jump tables. | |
4a60aa05 AX |
1615 | */ |
1616 | for_each_sec(file, sec) { | |
1ee44470 MS |
1617 | if (!strncmp(sec->name, ".rodata", 7) && |
1618 | !strstr(sec->name, ".str1.")) { | |
4a60aa05 AX |
1619 | sec->rodata = true; |
1620 | found = true; | |
1621 | } | |
1622 | } | |
1623 | ||
1624 | file->rodata = found; | |
1625 | } | |
1626 | ||
dcc914f4 JP |
1627 | static int decode_sections(struct objtool_file *file) |
1628 | { | |
1629 | int ret; | |
1630 | ||
4a60aa05 AX |
1631 | mark_rodata(file); |
1632 | ||
dcc914f4 JP |
1633 | ret = decode_instructions(file); |
1634 | if (ret) | |
1635 | return ret; | |
1636 | ||
1637 | ret = add_dead_ends(file); | |
1638 | if (ret) | |
1639 | return ret; | |
1640 | ||
1641 | add_ignores(file); | |
ea24213d | 1642 | add_uaccess_safe(file); |
dcc914f4 | 1643 | |
ff05ab23 | 1644 | ret = add_ignore_alternatives(file); |
258c7605 JP |
1645 | if (ret) |
1646 | return ret; | |
1647 | ||
5b06fd3b PZ |
1648 | ret = read_static_call_tramps(file); |
1649 | if (ret) | |
1650 | return ret; | |
1651 | ||
dcc914f4 JP |
1652 | ret = add_jump_destinations(file); |
1653 | if (ret) | |
1654 | return ret; | |
1655 | ||
a845c7cf | 1656 | ret = add_special_section_alts(file); |
dcc914f4 JP |
1657 | if (ret) |
1658 | return ret; | |
1659 | ||
8aa8eb2a AC |
1660 | ret = read_intra_function_calls(file); |
1661 | if (ret) | |
1662 | return ret; | |
1663 | ||
a845c7cf | 1664 | ret = add_call_destinations(file); |
dcc914f4 JP |
1665 | if (ret) |
1666 | return ret; | |
1667 | ||
e7c2bc37 | 1668 | ret = add_jump_table_alts(file); |
dcc914f4 JP |
1669 | if (ret) |
1670 | return ret; | |
1671 | ||
39358a03 JP |
1672 | ret = read_unwind_hints(file); |
1673 | if (ret) | |
1674 | return ret; | |
1675 | ||
b5bc2231 PZ |
1676 | ret = read_retpoline_hints(file); |
1677 | if (ret) | |
1678 | return ret; | |
1679 | ||
c4a33939 PZ |
1680 | ret = read_instr_hints(file); |
1681 | if (ret) | |
1682 | return ret; | |
1683 | ||
dcc914f4 JP |
1684 | return 0; |
1685 | } | |
1686 | ||
1687 | static bool is_fentry_call(struct instruction *insn) | |
1688 | { | |
87cf61fe | 1689 | if (insn->type == INSN_CALL && insn->call_dest && |
dcc914f4 JP |
1690 | insn->call_dest->type == STT_NOTYPE && |
1691 | !strcmp(insn->call_dest->name, "__fentry__")) | |
1692 | return true; | |
1693 | ||
1694 | return false; | |
1695 | } | |
1696 | ||
e25eea89 | 1697 | static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state) |
dcc914f4 | 1698 | { |
e25eea89 | 1699 | u8 ret_offset = insn->ret_offset; |
e7c0219b | 1700 | struct cfi_state *cfi = &state->cfi; |
baa41469 JP |
1701 | int i; |
1702 | ||
e7c0219b | 1703 | if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap) |
e25eea89 PZ |
1704 | return true; |
1705 | ||
e7c0219b | 1706 | if (cfi->cfa.offset != initial_func_cfi.cfa.offset + ret_offset) |
baa41469 JP |
1707 | return true; |
1708 | ||
e7c0219b | 1709 | if (cfi->stack_size != initial_func_cfi.cfa.offset + ret_offset) |
e25eea89 PZ |
1710 | return true; |
1711 | ||
c721b3f8 AC |
1712 | /* |
1713 | * If there is a ret offset hint then don't check registers | |
1714 | * because a callee-saved register might have been pushed on | |
1715 | * the stack. | |
1716 | */ | |
1717 | if (ret_offset) | |
1718 | return false; | |
1719 | ||
e25eea89 | 1720 | for (i = 0; i < CFI_NUM_REGS; i++) { |
e7c0219b PZ |
1721 | if (cfi->regs[i].base != initial_func_cfi.regs[i].base || |
1722 | cfi->regs[i].offset != initial_func_cfi.regs[i].offset) | |
baa41469 | 1723 | return true; |
e25eea89 | 1724 | } |
baa41469 JP |
1725 | |
1726 | return false; | |
1727 | } | |
1728 | ||
1729 | static bool has_valid_stack_frame(struct insn_state *state) | |
1730 | { | |
e7c0219b PZ |
1731 | struct cfi_state *cfi = &state->cfi; |
1732 | ||
1733 | if (cfi->cfa.base == CFI_BP && cfi->regs[CFI_BP].base == CFI_CFA && | |
1734 | cfi->regs[CFI_BP].offset == -16) | |
baa41469 JP |
1735 | return true; |
1736 | ||
e7c0219b | 1737 | if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP) |
baa41469 JP |
1738 | return true; |
1739 | ||
1740 | return false; | |
dcc914f4 JP |
1741 | } |
1742 | ||
e7c0219b PZ |
1743 | static int update_cfi_state_regs(struct instruction *insn, |
1744 | struct cfi_state *cfi, | |
65ea47dc | 1745 | struct stack_op *op) |
627fce14 | 1746 | { |
e7c0219b | 1747 | struct cfi_reg *cfa = &cfi->cfa; |
627fce14 | 1748 | |
d8dd25a4 | 1749 | if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT) |
627fce14 JP |
1750 | return 0; |
1751 | ||
1752 | /* push */ | |
ea24213d | 1753 | if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF) |
627fce14 JP |
1754 | cfa->offset += 8; |
1755 | ||
1756 | /* pop */ | |
ea24213d | 1757 | if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF) |
627fce14 JP |
1758 | cfa->offset -= 8; |
1759 | ||
1760 | /* add immediate to sp */ | |
1761 | if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD && | |
1762 | op->dest.reg == CFI_SP && op->src.reg == CFI_SP) | |
1763 | cfa->offset -= op->src.offset; | |
1764 | ||
1765 | return 0; | |
1766 | } | |
1767 | ||
e7c0219b | 1768 | static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset) |
dcc914f4 | 1769 | { |
bf4d1a83 | 1770 | if (arch_callee_saved_reg(reg) && |
e7c0219b PZ |
1771 | cfi->regs[reg].base == CFI_UNDEFINED) { |
1772 | cfi->regs[reg].base = base; | |
1773 | cfi->regs[reg].offset = offset; | |
baa41469 | 1774 | } |
dcc914f4 JP |
1775 | } |
1776 | ||
e7c0219b | 1777 | static void restore_reg(struct cfi_state *cfi, unsigned char reg) |
dcc914f4 | 1778 | { |
e7c0219b PZ |
1779 | cfi->regs[reg].base = initial_func_cfi.regs[reg].base; |
1780 | cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset; | |
baa41469 JP |
1781 | } |
1782 | ||
1783 | /* | |
1784 | * A note about DRAP stack alignment: | |
1785 | * | |
1786 | * GCC has the concept of a DRAP register, which is used to help keep track of | |
1787 | * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP | |
1788 | * register. The typical DRAP pattern is: | |
1789 | * | |
1790 | * 4c 8d 54 24 08 lea 0x8(%rsp),%r10 | |
1791 | * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp | |
1792 | * 41 ff 72 f8 pushq -0x8(%r10) | |
1793 | * 55 push %rbp | |
1794 | * 48 89 e5 mov %rsp,%rbp | |
1795 | * (more pushes) | |
1796 | * 41 52 push %r10 | |
1797 | * ... | |
1798 | * 41 5a pop %r10 | |
1799 | * (more pops) | |
1800 | * 5d pop %rbp | |
1801 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1802 | * c3 retq | |
1803 | * | |
1804 | * There are some variations in the epilogues, like: | |
1805 | * | |
1806 | * 5b pop %rbx | |
1807 | * 41 5a pop %r10 | |
1808 | * 41 5c pop %r12 | |
1809 | * 41 5d pop %r13 | |
1810 | * 41 5e pop %r14 | |
1811 | * c9 leaveq | |
1812 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1813 | * c3 retq | |
1814 | * | |
1815 | * and: | |
1816 | * | |
1817 | * 4c 8b 55 e8 mov -0x18(%rbp),%r10 | |
1818 | * 48 8b 5d e0 mov -0x20(%rbp),%rbx | |
1819 | * 4c 8b 65 f0 mov -0x10(%rbp),%r12 | |
1820 | * 4c 8b 6d f8 mov -0x8(%rbp),%r13 | |
1821 | * c9 leaveq | |
1822 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1823 | * c3 retq | |
1824 | * | |
1825 | * Sometimes r13 is used as the DRAP register, in which case it's saved and | |
1826 | * restored beforehand: | |
1827 | * | |
1828 | * 41 55 push %r13 | |
1829 | * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13 | |
1830 | * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp | |
1831 | * ... | |
1832 | * 49 8d 65 f0 lea -0x10(%r13),%rsp | |
1833 | * 41 5d pop %r13 | |
1834 | * c3 retq | |
1835 | */ | |
e7c0219b | 1836 | static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi, |
65ea47dc | 1837 | struct stack_op *op) |
baa41469 | 1838 | { |
e7c0219b PZ |
1839 | struct cfi_reg *cfa = &cfi->cfa; |
1840 | struct cfi_reg *regs = cfi->regs; | |
baa41469 JP |
1841 | |
1842 | /* stack operations don't make sense with an undefined CFA */ | |
1843 | if (cfa->base == CFI_UNDEFINED) { | |
1844 | if (insn->func) { | |
1845 | WARN_FUNC("undefined stack state", insn->sec, insn->offset); | |
1846 | return -1; | |
1847 | } | |
1848 | return 0; | |
1849 | } | |
1850 | ||
ee819aed JT |
1851 | if (cfi->type == UNWIND_HINT_TYPE_REGS || |
1852 | cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL) | |
e7c0219b | 1853 | return update_cfi_state_regs(insn, cfi, op); |
627fce14 | 1854 | |
baa41469 JP |
1855 | switch (op->dest.type) { |
1856 | ||
1857 | case OP_DEST_REG: | |
1858 | switch (op->src.type) { | |
1859 | ||
1860 | case OP_SRC_REG: | |
0d0970ee JP |
1861 | if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP && |
1862 | cfa->base == CFI_SP && | |
1863 | regs[CFI_BP].base == CFI_CFA && | |
1864 | regs[CFI_BP].offset == -cfa->offset) { | |
1865 | ||
1866 | /* mov %rsp, %rbp */ | |
1867 | cfa->base = op->dest.reg; | |
e7c0219b | 1868 | cfi->bp_scratch = false; |
0d0970ee | 1869 | } |
dd88a0a0 | 1870 | |
0d0970ee | 1871 | else if (op->src.reg == CFI_SP && |
e7c0219b | 1872 | op->dest.reg == CFI_BP && cfi->drap) { |
dd88a0a0 | 1873 | |
0d0970ee JP |
1874 | /* drap: mov %rsp, %rbp */ |
1875 | regs[CFI_BP].base = CFI_BP; | |
e7c0219b PZ |
1876 | regs[CFI_BP].offset = -cfi->stack_size; |
1877 | cfi->bp_scratch = false; | |
0d0970ee | 1878 | } |
dd88a0a0 | 1879 | |
0d0970ee JP |
1880 | else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
1881 | ||
1882 | /* | |
1883 | * mov %rsp, %reg | |
1884 | * | |
1885 | * This is needed for the rare case where GCC | |
1886 | * does: | |
1887 | * | |
1888 | * mov %rsp, %rax | |
1889 | * ... | |
1890 | * mov %rax, %rsp | |
1891 | */ | |
e7c0219b PZ |
1892 | cfi->vals[op->dest.reg].base = CFI_CFA; |
1893 | cfi->vals[op->dest.reg].offset = -cfi->stack_size; | |
dd88a0a0 JP |
1894 | } |
1895 | ||
3c1f0583 JP |
1896 | else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP && |
1897 | cfa->base == CFI_BP) { | |
1898 | ||
1899 | /* | |
1900 | * mov %rbp, %rsp | |
1901 | * | |
1902 | * Restore the original stack pointer (Clang). | |
1903 | */ | |
e7c0219b | 1904 | cfi->stack_size = -cfi->regs[CFI_BP].offset; |
3c1f0583 JP |
1905 | } |
1906 | ||
dd88a0a0 JP |
1907 | else if (op->dest.reg == cfa->base) { |
1908 | ||
1909 | /* mov %reg, %rsp */ | |
1910 | if (cfa->base == CFI_SP && | |
e7c0219b | 1911 | cfi->vals[op->src.reg].base == CFI_CFA) { |
dd88a0a0 JP |
1912 | |
1913 | /* | |
1914 | * This is needed for the rare case | |
1915 | * where GCC does something dumb like: | |
1916 | * | |
1917 | * lea 0x8(%rsp), %rcx | |
1918 | * ... | |
1919 | * mov %rcx, %rsp | |
1920 | */ | |
e7c0219b PZ |
1921 | cfa->offset = -cfi->vals[op->src.reg].offset; |
1922 | cfi->stack_size = cfa->offset; | |
dd88a0a0 JP |
1923 | |
1924 | } else { | |
1925 | cfa->base = CFI_UNDEFINED; | |
1926 | cfa->offset = 0; | |
1927 | } | |
baa41469 JP |
1928 | } |
1929 | ||
1930 | break; | |
1931 | ||
1932 | case OP_SRC_ADD: | |
1933 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) { | |
1934 | ||
1935 | /* add imm, %rsp */ | |
e7c0219b | 1936 | cfi->stack_size -= op->src.offset; |
baa41469 JP |
1937 | if (cfa->base == CFI_SP) |
1938 | cfa->offset -= op->src.offset; | |
1939 | break; | |
1940 | } | |
1941 | ||
1942 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) { | |
1943 | ||
1944 | /* lea disp(%rbp), %rsp */ | |
e7c0219b | 1945 | cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset); |
baa41469 JP |
1946 | break; |
1947 | } | |
1948 | ||
dd88a0a0 | 1949 | if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
baa41469 JP |
1950 | |
1951 | /* drap: lea disp(%rsp), %drap */ | |
e7c0219b | 1952 | cfi->drap_reg = op->dest.reg; |
dd88a0a0 JP |
1953 | |
1954 | /* | |
1955 | * lea disp(%rsp), %reg | |
1956 | * | |
1957 | * This is needed for the rare case where GCC | |
1958 | * does something dumb like: | |
1959 | * | |
1960 | * lea 0x8(%rsp), %rcx | |
1961 | * ... | |
1962 | * mov %rcx, %rsp | |
1963 | */ | |
e7c0219b PZ |
1964 | cfi->vals[op->dest.reg].base = CFI_CFA; |
1965 | cfi->vals[op->dest.reg].offset = \ | |
1966 | -cfi->stack_size + op->src.offset; | |
dd88a0a0 | 1967 | |
baa41469 JP |
1968 | break; |
1969 | } | |
1970 | ||
e7c0219b PZ |
1971 | if (cfi->drap && op->dest.reg == CFI_SP && |
1972 | op->src.reg == cfi->drap_reg) { | |
baa41469 JP |
1973 | |
1974 | /* drap: lea disp(%drap), %rsp */ | |
1975 | cfa->base = CFI_SP; | |
e7c0219b PZ |
1976 | cfa->offset = cfi->stack_size = -op->src.offset; |
1977 | cfi->drap_reg = CFI_UNDEFINED; | |
1978 | cfi->drap = false; | |
baa41469 JP |
1979 | break; |
1980 | } | |
1981 | ||
e7c0219b | 1982 | if (op->dest.reg == cfi->cfa.base) { |
baa41469 JP |
1983 | WARN_FUNC("unsupported stack register modification", |
1984 | insn->sec, insn->offset); | |
1985 | return -1; | |
1986 | } | |
1987 | ||
1988 | break; | |
1989 | ||
1990 | case OP_SRC_AND: | |
1991 | if (op->dest.reg != CFI_SP || | |
e7c0219b PZ |
1992 | (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) || |
1993 | (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) { | |
baa41469 JP |
1994 | WARN_FUNC("unsupported stack pointer realignment", |
1995 | insn->sec, insn->offset); | |
1996 | return -1; | |
1997 | } | |
1998 | ||
e7c0219b | 1999 | if (cfi->drap_reg != CFI_UNDEFINED) { |
baa41469 | 2000 | /* drap: and imm, %rsp */ |
e7c0219b PZ |
2001 | cfa->base = cfi->drap_reg; |
2002 | cfa->offset = cfi->stack_size = 0; | |
2003 | cfi->drap = true; | |
baa41469 JP |
2004 | } |
2005 | ||
2006 | /* | |
2007 | * Older versions of GCC (4.8ish) realign the stack | |
2008 | * without DRAP, with a frame pointer. | |
2009 | */ | |
2010 | ||
2011 | break; | |
2012 | ||
2013 | case OP_SRC_POP: | |
ea24213d | 2014 | case OP_SRC_POPF: |
e7c0219b | 2015 | if (!cfi->drap && op->dest.reg == cfa->base) { |
baa41469 JP |
2016 | |
2017 | /* pop %rbp */ | |
2018 | cfa->base = CFI_SP; | |
2019 | } | |
2020 | ||
e7c0219b PZ |
2021 | if (cfi->drap && cfa->base == CFI_BP_INDIRECT && |
2022 | op->dest.reg == cfi->drap_reg && | |
2023 | cfi->drap_offset == -cfi->stack_size) { | |
baa41469 | 2024 | |
bf4d1a83 | 2025 | /* drap: pop %drap */ |
e7c0219b | 2026 | cfa->base = cfi->drap_reg; |
bf4d1a83 | 2027 | cfa->offset = 0; |
e7c0219b | 2028 | cfi->drap_offset = -1; |
baa41469 | 2029 | |
e7c0219b | 2030 | } else if (regs[op->dest.reg].offset == -cfi->stack_size) { |
baa41469 | 2031 | |
bf4d1a83 | 2032 | /* pop %reg */ |
e7c0219b | 2033 | restore_reg(cfi, op->dest.reg); |
baa41469 JP |
2034 | } |
2035 | ||
e7c0219b | 2036 | cfi->stack_size -= 8; |
baa41469 JP |
2037 | if (cfa->base == CFI_SP) |
2038 | cfa->offset -= 8; | |
2039 | ||
2040 | break; | |
2041 | ||
2042 | case OP_SRC_REG_INDIRECT: | |
e7c0219b PZ |
2043 | if (cfi->drap && op->src.reg == CFI_BP && |
2044 | op->src.offset == cfi->drap_offset) { | |
bf4d1a83 JP |
2045 | |
2046 | /* drap: mov disp(%rbp), %drap */ | |
e7c0219b | 2047 | cfa->base = cfi->drap_reg; |
bf4d1a83 | 2048 | cfa->offset = 0; |
e7c0219b | 2049 | cfi->drap_offset = -1; |
bf4d1a83 JP |
2050 | } |
2051 | ||
e7c0219b | 2052 | if (cfi->drap && op->src.reg == CFI_BP && |
baa41469 JP |
2053 | op->src.offset == regs[op->dest.reg].offset) { |
2054 | ||
2055 | /* drap: mov disp(%rbp), %reg */ | |
e7c0219b | 2056 | restore_reg(cfi, op->dest.reg); |
baa41469 JP |
2057 | |
2058 | } else if (op->src.reg == cfa->base && | |
2059 | op->src.offset == regs[op->dest.reg].offset + cfa->offset) { | |
2060 | ||
2061 | /* mov disp(%rbp), %reg */ | |
2062 | /* mov disp(%rsp), %reg */ | |
e7c0219b | 2063 | restore_reg(cfi, op->dest.reg); |
baa41469 JP |
2064 | } |
2065 | ||
2066 | break; | |
2067 | ||
2068 | default: | |
2069 | WARN_FUNC("unknown stack-related instruction", | |
2070 | insn->sec, insn->offset); | |
2071 | return -1; | |
2072 | } | |
2073 | ||
2074 | break; | |
2075 | ||
2076 | case OP_DEST_PUSH: | |
ea24213d | 2077 | case OP_DEST_PUSHF: |
e7c0219b | 2078 | cfi->stack_size += 8; |
baa41469 JP |
2079 | if (cfa->base == CFI_SP) |
2080 | cfa->offset += 8; | |
2081 | ||
2082 | if (op->src.type != OP_SRC_REG) | |
2083 | break; | |
2084 | ||
e7c0219b PZ |
2085 | if (cfi->drap) { |
2086 | if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) { | |
baa41469 JP |
2087 | |
2088 | /* drap: push %drap */ | |
2089 | cfa->base = CFI_BP_INDIRECT; | |
e7c0219b | 2090 | cfa->offset = -cfi->stack_size; |
baa41469 | 2091 | |
bf4d1a83 | 2092 | /* save drap so we know when to restore it */ |
e7c0219b | 2093 | cfi->drap_offset = -cfi->stack_size; |
baa41469 | 2094 | |
e7c0219b | 2095 | } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) { |
baa41469 JP |
2096 | |
2097 | /* drap: push %rbp */ | |
e7c0219b | 2098 | cfi->stack_size = 0; |
baa41469 | 2099 | |
f4f80398 | 2100 | } else { |
baa41469 JP |
2101 | |
2102 | /* drap: push %reg */ | |
e7c0219b | 2103 | save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size); |
baa41469 JP |
2104 | } |
2105 | ||
2106 | } else { | |
2107 | ||
2108 | /* push %reg */ | |
e7c0219b | 2109 | save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size); |
baa41469 JP |
2110 | } |
2111 | ||
2112 | /* detect when asm code uses rbp as a scratch register */ | |
867ac9d7 | 2113 | if (!no_fp && insn->func && op->src.reg == CFI_BP && |
baa41469 | 2114 | cfa->base != CFI_BP) |
e7c0219b | 2115 | cfi->bp_scratch = true; |
baa41469 JP |
2116 | break; |
2117 | ||
2118 | case OP_DEST_REG_INDIRECT: | |
2119 | ||
e7c0219b PZ |
2120 | if (cfi->drap) { |
2121 | if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) { | |
baa41469 JP |
2122 | |
2123 | /* drap: mov %drap, disp(%rbp) */ | |
2124 | cfa->base = CFI_BP_INDIRECT; | |
2125 | cfa->offset = op->dest.offset; | |
2126 | ||
bf4d1a83 | 2127 | /* save drap offset so we know when to restore it */ |
e7c0219b | 2128 | cfi->drap_offset = op->dest.offset; |
f4f80398 | 2129 | } else { |
baa41469 JP |
2130 | |
2131 | /* drap: mov reg, disp(%rbp) */ | |
e7c0219b | 2132 | save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset); |
baa41469 JP |
2133 | } |
2134 | ||
2135 | } else if (op->dest.reg == cfa->base) { | |
2136 | ||
2137 | /* mov reg, disp(%rbp) */ | |
2138 | /* mov reg, disp(%rsp) */ | |
e7c0219b PZ |
2139 | save_reg(cfi, op->src.reg, CFI_CFA, |
2140 | op->dest.offset - cfi->cfa.offset); | |
baa41469 JP |
2141 | } |
2142 | ||
2143 | break; | |
2144 | ||
2145 | case OP_DEST_LEAVE: | |
e7c0219b PZ |
2146 | if ((!cfi->drap && cfa->base != CFI_BP) || |
2147 | (cfi->drap && cfa->base != cfi->drap_reg)) { | |
baa41469 JP |
2148 | WARN_FUNC("leave instruction with modified stack frame", |
2149 | insn->sec, insn->offset); | |
2150 | return -1; | |
2151 | } | |
2152 | ||
2153 | /* leave (mov %rbp, %rsp; pop %rbp) */ | |
2154 | ||
e7c0219b PZ |
2155 | cfi->stack_size = -cfi->regs[CFI_BP].offset - 8; |
2156 | restore_reg(cfi, CFI_BP); | |
baa41469 | 2157 | |
e7c0219b | 2158 | if (!cfi->drap) { |
baa41469 JP |
2159 | cfa->base = CFI_SP; |
2160 | cfa->offset -= 8; | |
2161 | } | |
2162 | ||
2163 | break; | |
2164 | ||
2165 | case OP_DEST_MEM: | |
ea24213d | 2166 | if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) { |
baa41469 JP |
2167 | WARN_FUNC("unknown stack-related memory operation", |
2168 | insn->sec, insn->offset); | |
2169 | return -1; | |
2170 | } | |
2171 | ||
2172 | /* pop mem */ | |
e7c0219b | 2173 | cfi->stack_size -= 8; |
baa41469 JP |
2174 | if (cfa->base == CFI_SP) |
2175 | cfa->offset -= 8; | |
2176 | ||
2177 | break; | |
2178 | ||
2179 | default: | |
2180 | WARN_FUNC("unknown stack-related instruction", | |
2181 | insn->sec, insn->offset); | |
2182 | return -1; | |
2183 | } | |
2184 | ||
2185 | return 0; | |
2186 | } | |
2187 | ||
65ea47dc JT |
2188 | static int handle_insn_ops(struct instruction *insn, struct insn_state *state) |
2189 | { | |
2190 | struct stack_op *op; | |
2191 | ||
2192 | list_for_each_entry(op, &insn->stack_ops, list) { | |
ab3852ab | 2193 | struct cfi_state old_cfi = state->cfi; |
65ea47dc JT |
2194 | int res; |
2195 | ||
e7c0219b | 2196 | res = update_cfi_state(insn, &state->cfi, op); |
65ea47dc JT |
2197 | if (res) |
2198 | return res; | |
2199 | ||
ab3852ab PZ |
2200 | if (insn->alt_group && memcmp(&state->cfi, &old_cfi, sizeof(struct cfi_state))) { |
2201 | WARN_FUNC("alternative modifies stack", insn->sec, insn->offset); | |
2202 | return -1; | |
2203 | } | |
2204 | ||
65ea47dc JT |
2205 | if (op->dest.type == OP_DEST_PUSHF) { |
2206 | if (!state->uaccess_stack) { | |
2207 | state->uaccess_stack = 1; | |
2208 | } else if (state->uaccess_stack >> 31) { | |
2209 | WARN_FUNC("PUSHF stack exhausted", | |
2210 | insn->sec, insn->offset); | |
2211 | return 1; | |
2212 | } | |
2213 | state->uaccess_stack <<= 1; | |
2214 | state->uaccess_stack |= state->uaccess; | |
2215 | } | |
2216 | ||
2217 | if (op->src.type == OP_SRC_POPF) { | |
2218 | if (state->uaccess_stack) { | |
2219 | state->uaccess = state->uaccess_stack & 1; | |
2220 | state->uaccess_stack >>= 1; | |
2221 | if (state->uaccess_stack == 1) | |
2222 | state->uaccess_stack = 0; | |
2223 | } | |
2224 | } | |
2225 | } | |
2226 | ||
2227 | return 0; | |
2228 | } | |
2229 | ||
e7c0219b | 2230 | static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2) |
baa41469 | 2231 | { |
e7c0219b | 2232 | struct cfi_state *cfi1 = &insn->cfi; |
baa41469 JP |
2233 | int i; |
2234 | ||
e7c0219b PZ |
2235 | if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) { |
2236 | ||
baa41469 JP |
2237 | WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d", |
2238 | insn->sec, insn->offset, | |
e7c0219b PZ |
2239 | cfi1->cfa.base, cfi1->cfa.offset, |
2240 | cfi2->cfa.base, cfi2->cfa.offset); | |
baa41469 | 2241 | |
e7c0219b | 2242 | } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) { |
baa41469 | 2243 | for (i = 0; i < CFI_NUM_REGS; i++) { |
e7c0219b | 2244 | if (!memcmp(&cfi1->regs[i], &cfi2->regs[i], |
baa41469 JP |
2245 | sizeof(struct cfi_reg))) |
2246 | continue; | |
2247 | ||
2248 | WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d", | |
2249 | insn->sec, insn->offset, | |
e7c0219b PZ |
2250 | i, cfi1->regs[i].base, cfi1->regs[i].offset, |
2251 | i, cfi2->regs[i].base, cfi2->regs[i].offset); | |
baa41469 JP |
2252 | break; |
2253 | } | |
2254 | ||
e7c0219b PZ |
2255 | } else if (cfi1->type != cfi2->type) { |
2256 | ||
627fce14 | 2257 | WARN_FUNC("stack state mismatch: type1=%d type2=%d", |
e7c0219b PZ |
2258 | insn->sec, insn->offset, cfi1->type, cfi2->type); |
2259 | ||
2260 | } else if (cfi1->drap != cfi2->drap || | |
2261 | (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) || | |
2262 | (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) { | |
627fce14 | 2263 | |
bf4d1a83 | 2264 | WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)", |
baa41469 | 2265 | insn->sec, insn->offset, |
e7c0219b PZ |
2266 | cfi1->drap, cfi1->drap_reg, cfi1->drap_offset, |
2267 | cfi2->drap, cfi2->drap_reg, cfi2->drap_offset); | |
baa41469 JP |
2268 | |
2269 | } else | |
2270 | return true; | |
2271 | ||
2272 | return false; | |
dcc914f4 JP |
2273 | } |
2274 | ||
ea24213d PZ |
2275 | static inline bool func_uaccess_safe(struct symbol *func) |
2276 | { | |
2277 | if (func) | |
e10cd8fe | 2278 | return func->uaccess_safe; |
ea24213d PZ |
2279 | |
2280 | return false; | |
2281 | } | |
2282 | ||
0c1ddd33 | 2283 | static inline const char *call_dest_name(struct instruction *insn) |
ea24213d PZ |
2284 | { |
2285 | if (insn->call_dest) | |
2286 | return insn->call_dest->name; | |
2287 | ||
2288 | return "{dynamic}"; | |
2289 | } | |
2290 | ||
6b643a07 PZ |
2291 | static inline bool noinstr_call_dest(struct symbol *func) |
2292 | { | |
2293 | /* | |
2294 | * We can't deal with indirect function calls at present; | |
2295 | * assume they're instrumented. | |
2296 | */ | |
2297 | if (!func) | |
2298 | return false; | |
2299 | ||
2300 | /* | |
2301 | * If the symbol is from a noinstr section; we good. | |
2302 | */ | |
2303 | if (func->sec->noinstr) | |
2304 | return true; | |
2305 | ||
2306 | /* | |
2307 | * The __ubsan_handle_*() calls are like WARN(), they only happen when | |
2308 | * something 'BAD' happened. At the risk of taking the machine down, | |
2309 | * let them proceed to get the message out. | |
2310 | */ | |
2311 | if (!strncmp(func->name, "__ubsan_handle_", 15)) | |
2312 | return true; | |
2313 | ||
2314 | return false; | |
2315 | } | |
2316 | ||
ea24213d PZ |
2317 | static int validate_call(struct instruction *insn, struct insn_state *state) |
2318 | { | |
c4a33939 | 2319 | if (state->noinstr && state->instr <= 0 && |
6b643a07 | 2320 | !noinstr_call_dest(insn->call_dest)) { |
c4a33939 PZ |
2321 | WARN_FUNC("call to %s() leaves .noinstr.text section", |
2322 | insn->sec, insn->offset, call_dest_name(insn)); | |
2323 | return 1; | |
2324 | } | |
2325 | ||
ea24213d PZ |
2326 | if (state->uaccess && !func_uaccess_safe(insn->call_dest)) { |
2327 | WARN_FUNC("call to %s() with UACCESS enabled", | |
0c1ddd33 | 2328 | insn->sec, insn->offset, call_dest_name(insn)); |
ea24213d PZ |
2329 | return 1; |
2330 | } | |
2331 | ||
2f0f9e9a PZ |
2332 | if (state->df) { |
2333 | WARN_FUNC("call to %s() with DF set", | |
0c1ddd33 | 2334 | insn->sec, insn->offset, call_dest_name(insn)); |
2f0f9e9a PZ |
2335 | return 1; |
2336 | } | |
2337 | ||
ea24213d PZ |
2338 | return 0; |
2339 | } | |
2340 | ||
54262aa2 PZ |
2341 | static int validate_sibling_call(struct instruction *insn, struct insn_state *state) |
2342 | { | |
e25eea89 | 2343 | if (has_modified_stack_frame(insn, state)) { |
54262aa2 PZ |
2344 | WARN_FUNC("sibling call from callable instruction with modified stack frame", |
2345 | insn->sec, insn->offset); | |
2346 | return 1; | |
2347 | } | |
2348 | ||
ea24213d | 2349 | return validate_call(insn, state); |
54262aa2 PZ |
2350 | } |
2351 | ||
a92e92d1 PZ |
2352 | static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state) |
2353 | { | |
c4a33939 PZ |
2354 | if (state->noinstr && state->instr > 0) { |
2355 | WARN_FUNC("return with instrumentation enabled", | |
2356 | insn->sec, insn->offset); | |
2357 | return 1; | |
2358 | } | |
2359 | ||
a92e92d1 PZ |
2360 | if (state->uaccess && !func_uaccess_safe(func)) { |
2361 | WARN_FUNC("return with UACCESS enabled", | |
2362 | insn->sec, insn->offset); | |
2363 | return 1; | |
2364 | } | |
2365 | ||
2366 | if (!state->uaccess && func_uaccess_safe(func)) { | |
2367 | WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function", | |
2368 | insn->sec, insn->offset); | |
2369 | return 1; | |
2370 | } | |
2371 | ||
2372 | if (state->df) { | |
2373 | WARN_FUNC("return with DF set", | |
2374 | insn->sec, insn->offset); | |
2375 | return 1; | |
2376 | } | |
2377 | ||
e25eea89 | 2378 | if (func && has_modified_stack_frame(insn, state)) { |
a92e92d1 PZ |
2379 | WARN_FUNC("return with modified stack frame", |
2380 | insn->sec, insn->offset); | |
2381 | return 1; | |
2382 | } | |
2383 | ||
e7c0219b | 2384 | if (state->cfi.bp_scratch) { |
b2966952 JP |
2385 | WARN_FUNC("BP used as a scratch register", |
2386 | insn->sec, insn->offset); | |
a92e92d1 PZ |
2387 | return 1; |
2388 | } | |
2389 | ||
2390 | return 0; | |
2391 | } | |
2392 | ||
7117f16b PZ |
2393 | /* |
2394 | * Alternatives should not contain any ORC entries, this in turn means they | |
2395 | * should not contain any CFI ops, which implies all instructions should have | |
2396 | * the same same CFI state. | |
2397 | * | |
2398 | * It is possible to constuct alternatives that have unreachable holes that go | |
2399 | * unreported (because they're NOPs), such holes would result in CFI_UNDEFINED | |
2400 | * states which then results in ORC entries, which we just said we didn't want. | |
2401 | * | |
2402 | * Avoid them by copying the CFI entry of the first instruction into the whole | |
2403 | * alternative. | |
2404 | */ | |
2405 | static void fill_alternative_cfi(struct objtool_file *file, struct instruction *insn) | |
2406 | { | |
2407 | struct instruction *first_insn = insn; | |
2408 | int alt_group = insn->alt_group; | |
2409 | ||
2410 | sec_for_each_insn_continue(file, insn) { | |
2411 | if (insn->alt_group != alt_group) | |
2412 | break; | |
2413 | insn->cfi = first_insn->cfi; | |
2414 | } | |
2415 | } | |
2416 | ||
dcc914f4 JP |
2417 | /* |
2418 | * Follow the branch starting at the given instruction, and recursively follow | |
2419 | * any other branches (jumps). Meanwhile, track the frame pointer state at | |
2420 | * each instruction and validate all the rules described in | |
2421 | * tools/objtool/Documentation/stack-validation.txt. | |
2422 | */ | |
c705cecc | 2423 | static int validate_branch(struct objtool_file *file, struct symbol *func, |
b7460462 | 2424 | struct instruction *insn, struct insn_state state) |
dcc914f4 JP |
2425 | { |
2426 | struct alternative *alt; | |
b7460462 | 2427 | struct instruction *next_insn; |
dcc914f4 | 2428 | struct section *sec; |
882a0db9 | 2429 | u8 visited; |
dcc914f4 JP |
2430 | int ret; |
2431 | ||
dcc914f4 | 2432 | sec = insn->sec; |
dcc914f4 | 2433 | |
dcc914f4 | 2434 | while (1) { |
39358a03 JP |
2435 | next_insn = next_insn_same_sec(file, insn); |
2436 | ||
13810435 | 2437 | if (file->c_file && func && insn->func && func != insn->func->pfunc) { |
ee97638b JP |
2438 | WARN("%s() falls through to next function %s()", |
2439 | func->name, insn->func->name); | |
2440 | return 1; | |
dcc914f4 JP |
2441 | } |
2442 | ||
4855022a JP |
2443 | if (func && insn->ignore) { |
2444 | WARN_FUNC("BUG: why am I validating an ignored function?", | |
2445 | sec, insn->offset); | |
12b25729 | 2446 | return 1; |
4855022a JP |
2447 | } |
2448 | ||
882a0db9 | 2449 | visited = 1 << state.uaccess; |
dcc914f4 | 2450 | if (insn->visited) { |
e7c0219b | 2451 | if (!insn->hint && !insn_cfi_match(insn, &state.cfi)) |
dcc914f4 | 2452 | return 1; |
dcc914f4 | 2453 | |
882a0db9 | 2454 | if (insn->visited & visited) |
ea24213d | 2455 | return 0; |
dcc914f4 JP |
2456 | } |
2457 | ||
c4a33939 PZ |
2458 | if (state.noinstr) |
2459 | state.instr += insn->instr; | |
2460 | ||
c536ed2f | 2461 | if (insn->hint) |
e7c0219b | 2462 | state.cfi = insn->cfi; |
c536ed2f | 2463 | else |
e7c0219b | 2464 | insn->cfi = state.cfi; |
dcc914f4 | 2465 | |
882a0db9 | 2466 | insn->visited |= visited; |
baa41469 | 2467 | |
7117f16b | 2468 | if (!insn->ignore_alts && !list_empty(&insn->alts)) { |
764eef4b PZ |
2469 | bool skip_orig = false; |
2470 | ||
a845c7cf | 2471 | list_for_each_entry(alt, &insn->alts, list) { |
764eef4b PZ |
2472 | if (alt->skip_orig) |
2473 | skip_orig = true; | |
2474 | ||
c705cecc | 2475 | ret = validate_branch(file, func, alt->insn, state); |
7697eee3 PZ |
2476 | if (ret) { |
2477 | if (backtrace) | |
2478 | BT_FUNC("(alt)", insn); | |
2479 | return ret; | |
2480 | } | |
a845c7cf | 2481 | } |
764eef4b | 2482 | |
7117f16b PZ |
2483 | if (insn->alt_group) |
2484 | fill_alternative_cfi(file, insn); | |
2485 | ||
764eef4b PZ |
2486 | if (skip_orig) |
2487 | return 0; | |
dcc914f4 JP |
2488 | } |
2489 | ||
60041bcd PZ |
2490 | if (handle_insn_ops(insn, &state)) |
2491 | return 1; | |
2492 | ||
dcc914f4 JP |
2493 | switch (insn->type) { |
2494 | ||
dcc914f4 | 2495 | case INSN_RETURN: |
a92e92d1 | 2496 | return validate_return(func, insn, &state); |
dcc914f4 JP |
2497 | |
2498 | case INSN_CALL: | |
ea24213d PZ |
2499 | case INSN_CALL_DYNAMIC: |
2500 | ret = validate_call(insn, &state); | |
2501 | if (ret) | |
2502 | return ret; | |
dcc914f4 | 2503 | |
c9bab22b JP |
2504 | if (!no_fp && func && !is_fentry_call(insn) && |
2505 | !has_valid_stack_frame(&state)) { | |
dcc914f4 JP |
2506 | WARN_FUNC("call without frame pointer save/setup", |
2507 | sec, insn->offset); | |
2508 | return 1; | |
2509 | } | |
c9bab22b JP |
2510 | |
2511 | if (dead_end_function(file, insn->call_dest)) | |
2512 | return 0; | |
2513 | ||
1e7e4788 JP |
2514 | if (insn->type == INSN_CALL && insn->call_dest->static_call_tramp) { |
2515 | list_add_tail(&insn->static_call_node, | |
2516 | &file->static_call_list); | |
2517 | } | |
2518 | ||
dcc914f4 JP |
2519 | break; |
2520 | ||
2521 | case INSN_JUMP_CONDITIONAL: | |
2522 | case INSN_JUMP_UNCONDITIONAL: | |
0c1ddd33 | 2523 | if (func && is_sibling_call(insn)) { |
54262aa2 | 2524 | ret = validate_sibling_call(insn, &state); |
dcc914f4 | 2525 | if (ret) |
54262aa2 | 2526 | return ret; |
4855022a | 2527 | |
0c1ddd33 | 2528 | } else if (insn->jump_dest) { |
c705cecc JP |
2529 | ret = validate_branch(file, func, |
2530 | insn->jump_dest, state); | |
7697eee3 PZ |
2531 | if (ret) { |
2532 | if (backtrace) | |
2533 | BT_FUNC("(branch)", insn); | |
2534 | return ret; | |
2535 | } | |
4855022a | 2536 | } |
dcc914f4 JP |
2537 | |
2538 | if (insn->type == INSN_JUMP_UNCONDITIONAL) | |
2539 | return 0; | |
2540 | ||
2541 | break; | |
2542 | ||
2543 | case INSN_JUMP_DYNAMIC: | |
b68b9907 | 2544 | case INSN_JUMP_DYNAMIC_CONDITIONAL: |
0c1ddd33 | 2545 | if (func && is_sibling_call(insn)) { |
54262aa2 PZ |
2546 | ret = validate_sibling_call(insn, &state); |
2547 | if (ret) | |
2548 | return ret; | |
dcc914f4 JP |
2549 | } |
2550 | ||
b68b9907 JP |
2551 | if (insn->type == INSN_JUMP_DYNAMIC) |
2552 | return 0; | |
2553 | ||
2554 | break; | |
dcc914f4 | 2555 | |
39358a03 JP |
2556 | case INSN_CONTEXT_SWITCH: |
2557 | if (func && (!next_insn || !next_insn->hint)) { | |
2558 | WARN_FUNC("unsupported instruction in callable function", | |
2559 | sec, insn->offset); | |
2560 | return 1; | |
2561 | } | |
2562 | return 0; | |
2563 | ||
ea24213d PZ |
2564 | case INSN_STAC: |
2565 | if (state.uaccess) { | |
2566 | WARN_FUNC("recursive UACCESS enable", sec, insn->offset); | |
2567 | return 1; | |
2568 | } | |
2569 | ||
2570 | state.uaccess = true; | |
2571 | break; | |
2572 | ||
2573 | case INSN_CLAC: | |
c705cecc | 2574 | if (!state.uaccess && func) { |
ea24213d PZ |
2575 | WARN_FUNC("redundant UACCESS disable", sec, insn->offset); |
2576 | return 1; | |
2577 | } | |
2578 | ||
2579 | if (func_uaccess_safe(func) && !state.uaccess_stack) { | |
2580 | WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset); | |
2581 | return 1; | |
2582 | } | |
2583 | ||
2584 | state.uaccess = false; | |
baa41469 JP |
2585 | break; |
2586 | ||
2f0f9e9a PZ |
2587 | case INSN_STD: |
2588 | if (state.df) | |
2589 | WARN_FUNC("recursive STD", sec, insn->offset); | |
2590 | ||
2591 | state.df = true; | |
2592 | break; | |
2593 | ||
2594 | case INSN_CLD: | |
c705cecc | 2595 | if (!state.df && func) |
2f0f9e9a PZ |
2596 | WARN_FUNC("redundant CLD", sec, insn->offset); |
2597 | ||
2598 | state.df = false; | |
baa41469 JP |
2599 | break; |
2600 | ||
dcc914f4 JP |
2601 | default: |
2602 | break; | |
2603 | } | |
2604 | ||
2605 | if (insn->dead_end) | |
2606 | return 0; | |
2607 | ||
00d96180 | 2608 | if (!next_insn) { |
e7c0219b | 2609 | if (state.cfi.cfa.base == CFI_UNDEFINED) |
00d96180 | 2610 | return 0; |
dcc914f4 JP |
2611 | WARN("%s: unexpected end of section", sec->name); |
2612 | return 1; | |
2613 | } | |
00d96180 JP |
2614 | |
2615 | insn = next_insn; | |
dcc914f4 JP |
2616 | } |
2617 | ||
2618 | return 0; | |
2619 | } | |
2620 | ||
932f8e98 | 2621 | static int validate_unwind_hints(struct objtool_file *file, struct section *sec) |
39358a03 JP |
2622 | { |
2623 | struct instruction *insn; | |
39358a03 | 2624 | struct insn_state state; |
932f8e98 | 2625 | int ret, warnings = 0; |
39358a03 JP |
2626 | |
2627 | if (!file->hints) | |
2628 | return 0; | |
2629 | ||
932f8e98 | 2630 | init_insn_state(&state, sec); |
39358a03 | 2631 | |
932f8e98 PZ |
2632 | if (sec) { |
2633 | insn = find_insn(file, sec, 0); | |
2634 | if (!insn) | |
2635 | return 0; | |
2636 | } else { | |
2637 | insn = list_first_entry(&file->insn_list, typeof(*insn), list); | |
2638 | } | |
2639 | ||
2640 | while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) { | |
39358a03 | 2641 | if (insn->hint && !insn->visited) { |
c705cecc | 2642 | ret = validate_branch(file, insn->func, insn, state); |
7697eee3 PZ |
2643 | if (ret && backtrace) |
2644 | BT_FUNC("<=== (hint)", insn); | |
39358a03 JP |
2645 | warnings += ret; |
2646 | } | |
932f8e98 PZ |
2647 | |
2648 | insn = list_next_entry(insn, list); | |
39358a03 JP |
2649 | } |
2650 | ||
2651 | return warnings; | |
2652 | } | |
2653 | ||
b5bc2231 PZ |
2654 | static int validate_retpoline(struct objtool_file *file) |
2655 | { | |
2656 | struct instruction *insn; | |
2657 | int warnings = 0; | |
2658 | ||
2659 | for_each_insn(file, insn) { | |
2660 | if (insn->type != INSN_JUMP_DYNAMIC && | |
2661 | insn->type != INSN_CALL_DYNAMIC) | |
2662 | continue; | |
2663 | ||
2664 | if (insn->retpoline_safe) | |
2665 | continue; | |
2666 | ||
ca41b97e PZ |
2667 | /* |
2668 | * .init.text code is ran before userspace and thus doesn't | |
2669 | * strictly need retpolines, except for modules which are | |
2670 | * loaded late, they very much do need retpoline in their | |
2671 | * .init.text | |
2672 | */ | |
2673 | if (!strcmp(insn->sec->name, ".init.text") && !module) | |
2674 | continue; | |
2675 | ||
b5bc2231 PZ |
2676 | WARN_FUNC("indirect %s found in RETPOLINE build", |
2677 | insn->sec, insn->offset, | |
2678 | insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); | |
2679 | ||
2680 | warnings++; | |
2681 | } | |
2682 | ||
2683 | return warnings; | |
2684 | } | |
2685 | ||
dcc914f4 JP |
2686 | static bool is_kasan_insn(struct instruction *insn) |
2687 | { | |
2688 | return (insn->type == INSN_CALL && | |
2689 | !strcmp(insn->call_dest->name, "__asan_handle_no_return")); | |
2690 | } | |
2691 | ||
2692 | static bool is_ubsan_insn(struct instruction *insn) | |
2693 | { | |
2694 | return (insn->type == INSN_CALL && | |
2695 | !strcmp(insn->call_dest->name, | |
2696 | "__ubsan_handle_builtin_unreachable")); | |
2697 | } | |
2698 | ||
14db1f0a | 2699 | static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn) |
dcc914f4 JP |
2700 | { |
2701 | int i; | |
14db1f0a | 2702 | struct instruction *prev_insn; |
dcc914f4 | 2703 | |
baa41469 JP |
2704 | if (insn->ignore || insn->type == INSN_NOP) |
2705 | return true; | |
2706 | ||
2707 | /* | |
2708 | * Ignore any unused exceptions. This can happen when a whitelisted | |
2709 | * function has an exception table entry. | |
0e2bb2bc JP |
2710 | * |
2711 | * Also ignore alternative replacement instructions. This can happen | |
2712 | * when a whitelisted function uses one of the ALTERNATIVE macros. | |
baa41469 | 2713 | */ |
0e2bb2bc JP |
2714 | if (!strcmp(insn->sec->name, ".fixup") || |
2715 | !strcmp(insn->sec->name, ".altinstr_replacement") || | |
2716 | !strcmp(insn->sec->name, ".altinstr_aux")) | |
dcc914f4 JP |
2717 | return true; |
2718 | ||
fb136219 JT |
2719 | if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->offset == FAKE_JUMP_OFFSET) |
2720 | return true; | |
2721 | ||
bd841d61 JP |
2722 | if (!insn->func) |
2723 | return false; | |
2724 | ||
2725 | /* | |
2726 | * CONFIG_UBSAN_TRAP inserts a UD2 when it sees | |
2727 | * __builtin_unreachable(). The BUG() macro has an unreachable() after | |
2728 | * the UD2, which causes GCC's undefined trap logic to emit another UD2 | |
2729 | * (or occasionally a JMP to UD2). | |
14db1f0a IH |
2730 | * |
2731 | * It may also insert a UD2 after calling a __noreturn function. | |
bd841d61 | 2732 | */ |
14db1f0a IH |
2733 | prev_insn = list_prev_entry(insn, list); |
2734 | if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) && | |
bd841d61 JP |
2735 | (insn->type == INSN_BUG || |
2736 | (insn->type == INSN_JUMP_UNCONDITIONAL && | |
2737 | insn->jump_dest && insn->jump_dest->type == INSN_BUG))) | |
2738 | return true; | |
2739 | ||
dcc914f4 JP |
2740 | /* |
2741 | * Check if this (or a subsequent) instruction is related to | |
2742 | * CONFIG_UBSAN or CONFIG_KASAN. | |
2743 | * | |
2744 | * End the search at 5 instructions to avoid going into the weeds. | |
2745 | */ | |
2746 | for (i = 0; i < 5; i++) { | |
2747 | ||
2748 | if (is_kasan_insn(insn) || is_ubsan_insn(insn)) | |
2749 | return true; | |
2750 | ||
fe24e271 JP |
2751 | if (insn->type == INSN_JUMP_UNCONDITIONAL) { |
2752 | if (insn->jump_dest && | |
2753 | insn->jump_dest->func == insn->func) { | |
2754 | insn = insn->jump_dest; | |
2755 | continue; | |
2756 | } | |
2757 | ||
2758 | break; | |
dcc914f4 JP |
2759 | } |
2760 | ||
baa41469 | 2761 | if (insn->offset + insn->len >= insn->func->offset + insn->func->len) |
dcc914f4 | 2762 | break; |
fe24e271 | 2763 | |
dcc914f4 JP |
2764 | insn = list_next_entry(insn, list); |
2765 | } | |
2766 | ||
2767 | return false; | |
2768 | } | |
2769 | ||
4b5e2e7f PZ |
2770 | static int validate_symbol(struct objtool_file *file, struct section *sec, |
2771 | struct symbol *sym, struct insn_state *state) | |
dcc914f4 | 2772 | { |
dcc914f4 | 2773 | struct instruction *insn; |
4b5e2e7f PZ |
2774 | int ret; |
2775 | ||
2776 | if (!sym->len) { | |
2777 | WARN("%s() is missing an ELF size annotation", sym->name); | |
2778 | return 1; | |
2779 | } | |
2780 | ||
2781 | if (sym->pfunc != sym || sym->alias != sym) | |
2782 | return 0; | |
2783 | ||
2784 | insn = find_insn(file, sec, sym->offset); | |
2785 | if (!insn || insn->ignore || insn->visited) | |
2786 | return 0; | |
2787 | ||
2788 | state->uaccess = sym->uaccess_safe; | |
2789 | ||
2790 | ret = validate_branch(file, insn->func, insn, *state); | |
2791 | if (ret && backtrace) | |
2792 | BT_FUNC("<=== (sym)", insn); | |
2793 | return ret; | |
2794 | } | |
2795 | ||
2796 | static int validate_section(struct objtool_file *file, struct section *sec) | |
2797 | { | |
baa41469 | 2798 | struct insn_state state; |
4b5e2e7f PZ |
2799 | struct symbol *func; |
2800 | int warnings = 0; | |
dcc914f4 | 2801 | |
350994bf PZ |
2802 | list_for_each_entry(func, &sec->symbol_list, list) { |
2803 | if (func->type != STT_FUNC) | |
2804 | continue; | |
e10cd8fe | 2805 | |
932f8e98 | 2806 | init_insn_state(&state, sec); |
e7c0219b PZ |
2807 | state.cfi.cfa = initial_func_cfi.cfa; |
2808 | memcpy(&state.cfi.regs, &initial_func_cfi.regs, | |
0699e551 | 2809 | CFI_NUM_REGS * sizeof(struct cfi_reg)); |
e7c0219b | 2810 | state.cfi.stack_size = initial_func_cfi.cfa.offset; |
0699e551 | 2811 | |
4b5e2e7f | 2812 | warnings += validate_symbol(file, sec, func, &state); |
dcc914f4 JP |
2813 | } |
2814 | ||
dcc914f4 JP |
2815 | return warnings; |
2816 | } | |
2817 | ||
c4a33939 PZ |
2818 | static int validate_vmlinux_functions(struct objtool_file *file) |
2819 | { | |
2820 | struct section *sec; | |
932f8e98 | 2821 | int warnings = 0; |
c4a33939 PZ |
2822 | |
2823 | sec = find_section_by_name(file->elf, ".noinstr.text"); | |
0cc9ac8d TG |
2824 | if (sec) { |
2825 | warnings += validate_section(file, sec); | |
2826 | warnings += validate_unwind_hints(file, sec); | |
2827 | } | |
c4a33939 | 2828 | |
0cc9ac8d TG |
2829 | sec = find_section_by_name(file->elf, ".entry.text"); |
2830 | if (sec) { | |
2831 | warnings += validate_section(file, sec); | |
2832 | warnings += validate_unwind_hints(file, sec); | |
2833 | } | |
932f8e98 PZ |
2834 | |
2835 | return warnings; | |
c4a33939 PZ |
2836 | } |
2837 | ||
350994bf PZ |
2838 | static int validate_functions(struct objtool_file *file) |
2839 | { | |
2840 | struct section *sec; | |
2841 | int warnings = 0; | |
2842 | ||
da837bd6 PZ |
2843 | for_each_sec(file, sec) { |
2844 | if (!(sec->sh.sh_flags & SHF_EXECINSTR)) | |
2845 | continue; | |
2846 | ||
350994bf | 2847 | warnings += validate_section(file, sec); |
da837bd6 | 2848 | } |
350994bf PZ |
2849 | |
2850 | return warnings; | |
2851 | } | |
2852 | ||
baa41469 | 2853 | static int validate_reachable_instructions(struct objtool_file *file) |
dcc914f4 JP |
2854 | { |
2855 | struct instruction *insn; | |
baa41469 JP |
2856 | |
2857 | if (file->ignore_unreachables) | |
2858 | return 0; | |
dcc914f4 JP |
2859 | |
2860 | for_each_insn(file, insn) { | |
14db1f0a | 2861 | if (insn->visited || ignore_unreachable_insn(file, insn)) |
baa41469 JP |
2862 | continue; |
2863 | ||
baa41469 JP |
2864 | WARN_FUNC("unreachable instruction", insn->sec, insn->offset); |
2865 | return 1; | |
dcc914f4 JP |
2866 | } |
2867 | ||
baa41469 | 2868 | return 0; |
dcc914f4 JP |
2869 | } |
2870 | ||
d44becb9 | 2871 | int check(struct objtool_file *file) |
dcc914f4 | 2872 | { |
dcc914f4 JP |
2873 | int ret, warnings = 0; |
2874 | ||
baa41469 JP |
2875 | arch_initial_func_cfi_state(&initial_func_cfi); |
2876 | ||
6545eb03 | 2877 | ret = decode_sections(file); |
dcc914f4 JP |
2878 | if (ret < 0) |
2879 | goto out; | |
2880 | warnings += ret; | |
2881 | ||
6545eb03 | 2882 | if (list_empty(&file->insn_list)) |
dcc914f4 | 2883 | goto out; |
dcc914f4 | 2884 | |
c4a33939 | 2885 | if (vmlinux && !validate_dup) { |
6545eb03 | 2886 | ret = validate_vmlinux_functions(file); |
c4a33939 PZ |
2887 | if (ret < 0) |
2888 | goto out; | |
2889 | ||
2890 | warnings += ret; | |
2891 | goto out; | |
2892 | } | |
2893 | ||
b5bc2231 | 2894 | if (retpoline) { |
6545eb03 | 2895 | ret = validate_retpoline(file); |
b5bc2231 PZ |
2896 | if (ret < 0) |
2897 | return ret; | |
2898 | warnings += ret; | |
2899 | } | |
2900 | ||
6545eb03 | 2901 | ret = validate_functions(file); |
dcc914f4 JP |
2902 | if (ret < 0) |
2903 | goto out; | |
2904 | warnings += ret; | |
2905 | ||
6545eb03 | 2906 | ret = validate_unwind_hints(file, NULL); |
39358a03 JP |
2907 | if (ret < 0) |
2908 | goto out; | |
2909 | warnings += ret; | |
2910 | ||
baa41469 | 2911 | if (!warnings) { |
6545eb03 | 2912 | ret = validate_reachable_instructions(file); |
baa41469 JP |
2913 | if (ret < 0) |
2914 | goto out; | |
2915 | warnings += ret; | |
2916 | } | |
2917 | ||
6545eb03 | 2918 | ret = create_static_call_sections(file); |
1e7e4788 JP |
2919 | if (ret < 0) |
2920 | goto out; | |
2921 | warnings += ret; | |
2922 | ||
dcc914f4 | 2923 | out: |
644592d3 JP |
2924 | if (ret < 0) { |
2925 | /* | |
2926 | * Fatal error. The binary is corrupt or otherwise broken in | |
2927 | * some way, or objtool itself is broken. Fail the kernel | |
2928 | * build. | |
2929 | */ | |
2930 | return ret; | |
2931 | } | |
2932 | ||
dcc914f4 JP |
2933 | return 0; |
2934 | } |