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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 | ||
7786032e VG |
9 | #include <arch/elf.h> |
10 | #include <objtool/builtin.h> | |
11 | #include <objtool/cfi.h> | |
12 | #include <objtool/arch.h> | |
13 | #include <objtool/check.h> | |
14 | #include <objtool/special.h> | |
15 | #include <objtool/warn.h> | |
16 | #include <objtool/endianness.h> | |
dcc914f4 | 17 | |
ee819aed | 18 | #include <linux/objtool.h> |
dcc914f4 JP |
19 | #include <linux/hashtable.h> |
20 | #include <linux/kernel.h> | |
1e7e4788 | 21 | #include <linux/static_call_types.h> |
dcc914f4 | 22 | |
dcc914f4 JP |
23 | struct alternative { |
24 | struct list_head list; | |
25 | struct instruction *insn; | |
764eef4b | 26 | bool skip_orig; |
dcc914f4 JP |
27 | }; |
28 | ||
a3608f59 | 29 | struct cfi_init_state initial_func_cfi; |
dcc914f4 | 30 | |
627fce14 JP |
31 | struct instruction *find_insn(struct objtool_file *file, |
32 | struct section *sec, unsigned long offset) | |
dcc914f4 JP |
33 | { |
34 | struct instruction *insn; | |
35 | ||
87ecb582 | 36 | hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) { |
dcc914f4 JP |
37 | if (insn->sec == sec && insn->offset == offset) |
38 | return insn; | |
87ecb582 | 39 | } |
dcc914f4 JP |
40 | |
41 | return NULL; | |
42 | } | |
43 | ||
44 | static struct instruction *next_insn_same_sec(struct objtool_file *file, | |
45 | struct instruction *insn) | |
46 | { | |
47 | struct instruction *next = list_next_entry(insn, list); | |
48 | ||
baa41469 | 49 | if (!next || &next->list == &file->insn_list || next->sec != insn->sec) |
dcc914f4 JP |
50 | return NULL; |
51 | ||
52 | return next; | |
53 | } | |
54 | ||
13810435 JP |
55 | static struct instruction *next_insn_same_func(struct objtool_file *file, |
56 | struct instruction *insn) | |
57 | { | |
58 | struct instruction *next = list_next_entry(insn, list); | |
59 | struct symbol *func = insn->func; | |
60 | ||
61 | if (!func) | |
62 | return NULL; | |
63 | ||
64 | if (&next->list != &file->insn_list && next->func == func) | |
65 | return next; | |
66 | ||
67 | /* Check if we're already in the subfunction: */ | |
68 | if (func == func->cfunc) | |
69 | return NULL; | |
70 | ||
71 | /* Move to the subfunction: */ | |
72 | return find_insn(file, func->cfunc->sec, func->cfunc->offset); | |
73 | } | |
74 | ||
1119d265 JP |
75 | static struct instruction *prev_insn_same_sym(struct objtool_file *file, |
76 | struct instruction *insn) | |
77 | { | |
78 | struct instruction *prev = list_prev_entry(insn, list); | |
79 | ||
80 | if (&prev->list != &file->insn_list && prev->func == insn->func) | |
81 | return prev; | |
82 | ||
83 | return NULL; | |
84 | } | |
85 | ||
f0f70adb | 86 | #define func_for_each_insn(file, func, insn) \ |
13810435 JP |
87 | for (insn = find_insn(file, func->sec, func->offset); \ |
88 | insn; \ | |
89 | insn = next_insn_same_func(file, insn)) | |
90 | ||
dbf4aeb0 PZ |
91 | #define sym_for_each_insn(file, sym, insn) \ |
92 | for (insn = find_insn(file, sym->sec, sym->offset); \ | |
dcc914f4 | 93 | insn && &insn->list != &file->insn_list && \ |
dbf4aeb0 PZ |
94 | insn->sec == sym->sec && \ |
95 | insn->offset < sym->offset + sym->len; \ | |
dcc914f4 JP |
96 | insn = list_next_entry(insn, list)) |
97 | ||
dbf4aeb0 | 98 | #define sym_for_each_insn_continue_reverse(file, sym, insn) \ |
dcc914f4 JP |
99 | for (insn = list_prev_entry(insn, list); \ |
100 | &insn->list != &file->insn_list && \ | |
dbf4aeb0 | 101 | insn->sec == sym->sec && insn->offset >= sym->offset; \ |
dcc914f4 JP |
102 | insn = list_prev_entry(insn, list)) |
103 | ||
104 | #define sec_for_each_insn_from(file, insn) \ | |
105 | for (; insn; insn = next_insn_same_sec(file, insn)) | |
106 | ||
baa41469 JP |
107 | #define sec_for_each_insn_continue(file, insn) \ |
108 | for (insn = next_insn_same_sec(file, insn); insn; \ | |
109 | insn = next_insn_same_sec(file, insn)) | |
dcc914f4 | 110 | |
0c1ddd33 JP |
111 | static bool is_sibling_call(struct instruction *insn) |
112 | { | |
ecf11ba4 JP |
113 | /* |
114 | * Assume only ELF functions can make sibling calls. This ensures | |
115 | * sibling call detection consistency between vmlinux.o and individual | |
116 | * objects. | |
117 | */ | |
118 | if (!insn->func) | |
119 | return false; | |
120 | ||
0c1ddd33 JP |
121 | /* An indirect jump is either a sibling call or a jump to a table. */ |
122 | if (insn->type == INSN_JUMP_DYNAMIC) | |
123 | return list_empty(&insn->alts); | |
124 | ||
0c1ddd33 | 125 | /* add_jump_destinations() sets insn->call_dest for sibling calls. */ |
ecf11ba4 | 126 | return (is_static_jump(insn) && insn->call_dest); |
0c1ddd33 JP |
127 | } |
128 | ||
dcc914f4 JP |
129 | /* |
130 | * This checks to see if the given function is a "noreturn" function. | |
131 | * | |
132 | * For global functions which are outside the scope of this object file, we | |
133 | * have to keep a manual list of them. | |
134 | * | |
135 | * For local functions, we have to detect them manually by simply looking for | |
136 | * the lack of a return instruction. | |
dcc914f4 | 137 | */ |
8e25c9f8 JP |
138 | static bool __dead_end_function(struct objtool_file *file, struct symbol *func, |
139 | int recursion) | |
dcc914f4 JP |
140 | { |
141 | int i; | |
142 | struct instruction *insn; | |
143 | bool empty = true; | |
144 | ||
145 | /* | |
146 | * Unfortunately these have to be hard coded because the noreturn | |
147 | * attribute isn't provided in ELF data. | |
148 | */ | |
149 | static const char * const global_noreturns[] = { | |
150 | "__stack_chk_fail", | |
151 | "panic", | |
152 | "do_exit", | |
153 | "do_task_dead", | |
154 | "__module_put_and_exit", | |
155 | "complete_and_exit", | |
dcc914f4 JP |
156 | "__reiserfs_panic", |
157 | "lbug_with_loc", | |
158 | "fortify_panic", | |
b394d468 | 159 | "usercopy_abort", |
684fb246 | 160 | "machine_real_restart", |
4fa5ecda | 161 | "rewind_stack_do_exit", |
33adf80f | 162 | "kunit_try_catch_throw", |
c26acfbb | 163 | "xen_start_kernel", |
dcc914f4 JP |
164 | }; |
165 | ||
c9bab22b JP |
166 | if (!func) |
167 | return false; | |
168 | ||
dcc914f4 | 169 | if (func->bind == STB_WEAK) |
8e25c9f8 | 170 | return false; |
dcc914f4 JP |
171 | |
172 | if (func->bind == STB_GLOBAL) | |
173 | for (i = 0; i < ARRAY_SIZE(global_noreturns); i++) | |
174 | if (!strcmp(func->name, global_noreturns[i])) | |
8e25c9f8 | 175 | return true; |
dcc914f4 | 176 | |
13810435 | 177 | if (!func->len) |
8e25c9f8 | 178 | return false; |
dcc914f4 | 179 | |
13810435 JP |
180 | insn = find_insn(file, func->sec, func->offset); |
181 | if (!insn->func) | |
8e25c9f8 | 182 | return false; |
13810435 | 183 | |
f0f70adb | 184 | func_for_each_insn(file, func, insn) { |
dcc914f4 JP |
185 | empty = false; |
186 | ||
187 | if (insn->type == INSN_RETURN) | |
8e25c9f8 | 188 | return false; |
dcc914f4 JP |
189 | } |
190 | ||
191 | if (empty) | |
8e25c9f8 | 192 | return false; |
dcc914f4 JP |
193 | |
194 | /* | |
195 | * A function can have a sibling call instead of a return. In that | |
196 | * case, the function's dead-end status depends on whether the target | |
197 | * of the sibling call returns. | |
198 | */ | |
f0f70adb | 199 | func_for_each_insn(file, func, insn) { |
0c1ddd33 | 200 | if (is_sibling_call(insn)) { |
dcc914f4 | 201 | struct instruction *dest = insn->jump_dest; |
dcc914f4 JP |
202 | |
203 | if (!dest) | |
204 | /* sibling call to another file */ | |
8e25c9f8 | 205 | return false; |
dcc914f4 | 206 | |
0c1ddd33 JP |
207 | /* local sibling call */ |
208 | if (recursion == 5) { | |
209 | /* | |
210 | * Infinite recursion: two functions have | |
211 | * sibling calls to each other. This is a very | |
212 | * rare case. It means they aren't dead ends. | |
213 | */ | |
214 | return false; | |
dcc914f4 | 215 | } |
dcc914f4 | 216 | |
0c1ddd33 JP |
217 | return __dead_end_function(file, dest->func, recursion+1); |
218 | } | |
dcc914f4 JP |
219 | } |
220 | ||
8e25c9f8 | 221 | return true; |
dcc914f4 JP |
222 | } |
223 | ||
8e25c9f8 | 224 | static bool dead_end_function(struct objtool_file *file, struct symbol *func) |
dcc914f4 JP |
225 | { |
226 | return __dead_end_function(file, func, 0); | |
227 | } | |
228 | ||
e7c0219b | 229 | static void init_cfi_state(struct cfi_state *cfi) |
baa41469 JP |
230 | { |
231 | int i; | |
232 | ||
dd88a0a0 | 233 | for (i = 0; i < CFI_NUM_REGS; i++) { |
e7c0219b PZ |
234 | cfi->regs[i].base = CFI_UNDEFINED; |
235 | cfi->vals[i].base = CFI_UNDEFINED; | |
dd88a0a0 | 236 | } |
e7c0219b PZ |
237 | cfi->cfa.base = CFI_UNDEFINED; |
238 | cfi->drap_reg = CFI_UNDEFINED; | |
239 | cfi->drap_offset = -1; | |
240 | } | |
241 | ||
932f8e98 | 242 | static void init_insn_state(struct insn_state *state, struct section *sec) |
e7c0219b PZ |
243 | { |
244 | memset(state, 0, sizeof(*state)); | |
245 | init_cfi_state(&state->cfi); | |
932f8e98 PZ |
246 | |
247 | /* | |
248 | * We need the full vmlinux for noinstr validation, otherwise we can | |
249 | * not correctly determine insn->call_dest->sec (external symbols do | |
250 | * not have a section). | |
251 | */ | |
41425ebe | 252 | if (vmlinux && noinstr && sec) |
932f8e98 | 253 | state->noinstr = sec->noinstr; |
baa41469 JP |
254 | } |
255 | ||
dcc914f4 JP |
256 | /* |
257 | * Call the arch-specific instruction decoder for all the instructions and add | |
258 | * them to the global instruction list. | |
259 | */ | |
260 | static int decode_instructions(struct objtool_file *file) | |
261 | { | |
262 | struct section *sec; | |
263 | struct symbol *func; | |
264 | unsigned long offset; | |
265 | struct instruction *insn; | |
1e11f3fd | 266 | unsigned long nr_insns = 0; |
dcc914f4 JP |
267 | int ret; |
268 | ||
baa41469 | 269 | for_each_sec(file, sec) { |
dcc914f4 JP |
270 | |
271 | if (!(sec->sh.sh_flags & SHF_EXECINSTR)) | |
272 | continue; | |
273 | ||
627fce14 JP |
274 | if (strcmp(sec->name, ".altinstr_replacement") && |
275 | strcmp(sec->name, ".altinstr_aux") && | |
276 | strncmp(sec->name, ".discard.", 9)) | |
277 | sec->text = true; | |
278 | ||
0cc9ac8d TG |
279 | if (!strcmp(sec->name, ".noinstr.text") || |
280 | !strcmp(sec->name, ".entry.text")) | |
c4a33939 PZ |
281 | sec->noinstr = true; |
282 | ||
dcc914f4 JP |
283 | for (offset = 0; offset < sec->len; offset += insn->len) { |
284 | insn = malloc(sizeof(*insn)); | |
baa41469 JP |
285 | if (!insn) { |
286 | WARN("malloc failed"); | |
287 | return -1; | |
288 | } | |
dcc914f4 | 289 | memset(insn, 0, sizeof(*insn)); |
dcc914f4 | 290 | INIT_LIST_HEAD(&insn->alts); |
65ea47dc | 291 | INIT_LIST_HEAD(&insn->stack_ops); |
e7c0219b | 292 | init_cfi_state(&insn->cfi); |
baa41469 | 293 | |
dcc914f4 JP |
294 | insn->sec = sec; |
295 | insn->offset = offset; | |
296 | ||
297 | ret = arch_decode_instruction(file->elf, sec, offset, | |
298 | sec->len - offset, | |
299 | &insn->len, &insn->type, | |
baa41469 | 300 | &insn->immediate, |
65ea47dc | 301 | &insn->stack_ops); |
dcc914f4 | 302 | if (ret) |
b7037983 | 303 | goto err; |
dcc914f4 | 304 | |
87ecb582 | 305 | hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset)); |
dcc914f4 | 306 | list_add_tail(&insn->list, &file->insn_list); |
1e11f3fd | 307 | nr_insns++; |
dcc914f4 JP |
308 | } |
309 | ||
310 | list_for_each_entry(func, &sec->symbol_list, list) { | |
e10cd8fe | 311 | if (func->type != STT_FUNC || func->alias != func) |
dcc914f4 JP |
312 | continue; |
313 | ||
314 | if (!find_insn(file, sec, func->offset)) { | |
315 | WARN("%s(): can't find starting instruction", | |
316 | func->name); | |
317 | return -1; | |
318 | } | |
319 | ||
dbf4aeb0 | 320 | sym_for_each_insn(file, func, insn) |
e10cd8fe | 321 | insn->func = func; |
dcc914f4 JP |
322 | } |
323 | } | |
324 | ||
1e11f3fd PZ |
325 | if (stats) |
326 | printf("nr_insns: %lu\n", nr_insns); | |
327 | ||
dcc914f4 | 328 | return 0; |
b7037983 KB |
329 | |
330 | err: | |
331 | free(insn); | |
332 | return ret; | |
dcc914f4 JP |
333 | } |
334 | ||
6b5dd716 ST |
335 | static struct instruction *find_last_insn(struct objtool_file *file, |
336 | struct section *sec) | |
337 | { | |
338 | struct instruction *insn = NULL; | |
339 | unsigned int offset; | |
340 | unsigned int end = (sec->len > 10) ? sec->len - 10 : 0; | |
341 | ||
342 | for (offset = sec->len - 1; offset >= end && !insn; offset--) | |
343 | insn = find_insn(file, sec, offset); | |
344 | ||
345 | return insn; | |
346 | } | |
347 | ||
dcc914f4 | 348 | /* |
649ea4d5 | 349 | * Mark "ud2" instructions and manually annotated dead ends. |
dcc914f4 JP |
350 | */ |
351 | static int add_dead_ends(struct objtool_file *file) | |
352 | { | |
353 | struct section *sec; | |
f1974222 | 354 | struct reloc *reloc; |
dcc914f4 | 355 | struct instruction *insn; |
dcc914f4 | 356 | |
649ea4d5 JP |
357 | /* |
358 | * By default, "ud2" is a dead end unless otherwise annotated, because | |
359 | * GCC 7 inserts it for certain divide-by-zero cases. | |
360 | */ | |
361 | for_each_insn(file, insn) | |
362 | if (insn->type == INSN_BUG) | |
363 | insn->dead_end = true; | |
364 | ||
365 | /* | |
366 | * Check for manually annotated dead ends. | |
367 | */ | |
dcc914f4 JP |
368 | sec = find_section_by_name(file->elf, ".rela.discard.unreachable"); |
369 | if (!sec) | |
649ea4d5 | 370 | goto reachable; |
dcc914f4 | 371 | |
f1974222 MH |
372 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
373 | if (reloc->sym->type != STT_SECTION) { | |
dcc914f4 JP |
374 | WARN("unexpected relocation symbol type in %s", sec->name); |
375 | return -1; | |
376 | } | |
f1974222 | 377 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
dcc914f4 JP |
378 | if (insn) |
379 | insn = list_prev_entry(insn, list); | |
f1974222 MH |
380 | else if (reloc->addend == reloc->sym->sec->len) { |
381 | insn = find_last_insn(file, reloc->sym->sec); | |
6b5dd716 | 382 | if (!insn) { |
dcc914f4 | 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 | } else { | |
388 | WARN("can't find unreachable insn at %s+0x%x", | |
f1974222 | 389 | reloc->sym->sec->name, reloc->addend); |
dcc914f4 JP |
390 | return -1; |
391 | } | |
392 | ||
393 | insn->dead_end = true; | |
394 | } | |
395 | ||
649ea4d5 JP |
396 | reachable: |
397 | /* | |
398 | * These manually annotated reachable checks are needed for GCC 4.4, | |
399 | * where the Linux unreachable() macro isn't supported. In that case | |
400 | * GCC doesn't know the "ud2" is fatal, so it generates code as if it's | |
401 | * not a dead end. | |
402 | */ | |
403 | sec = find_section_by_name(file->elf, ".rela.discard.reachable"); | |
404 | if (!sec) | |
405 | return 0; | |
406 | ||
f1974222 MH |
407 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
408 | if (reloc->sym->type != STT_SECTION) { | |
649ea4d5 JP |
409 | WARN("unexpected relocation symbol type in %s", sec->name); |
410 | return -1; | |
411 | } | |
f1974222 | 412 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
649ea4d5 JP |
413 | if (insn) |
414 | insn = list_prev_entry(insn, list); | |
f1974222 MH |
415 | else if (reloc->addend == reloc->sym->sec->len) { |
416 | insn = find_last_insn(file, reloc->sym->sec); | |
6b5dd716 | 417 | if (!insn) { |
649ea4d5 | 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 | } else { | |
423 | WARN("can't find reachable insn at %s+0x%x", | |
f1974222 | 424 | reloc->sym->sec->name, reloc->addend); |
649ea4d5 JP |
425 | return -1; |
426 | } | |
427 | ||
428 | insn->dead_end = false; | |
429 | } | |
430 | ||
dcc914f4 JP |
431 | return 0; |
432 | } | |
433 | ||
1e7e4788 JP |
434 | static int create_static_call_sections(struct objtool_file *file) |
435 | { | |
436 | struct section *sec, *reloc_sec; | |
437 | struct reloc *reloc; | |
438 | struct static_call_site *site; | |
439 | struct instruction *insn; | |
440 | struct symbol *key_sym; | |
441 | char *key_name, *tmp; | |
442 | int idx; | |
443 | ||
444 | sec = find_section_by_name(file->elf, ".static_call_sites"); | |
445 | if (sec) { | |
446 | INIT_LIST_HEAD(&file->static_call_list); | |
447 | WARN("file already has .static_call_sites section, skipping"); | |
448 | return 0; | |
449 | } | |
450 | ||
451 | if (list_empty(&file->static_call_list)) | |
452 | return 0; | |
453 | ||
454 | idx = 0; | |
455 | list_for_each_entry(insn, &file->static_call_list, static_call_node) | |
456 | idx++; | |
457 | ||
458 | sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE, | |
459 | sizeof(struct static_call_site), idx); | |
460 | if (!sec) | |
461 | return -1; | |
462 | ||
463 | reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA); | |
464 | if (!reloc_sec) | |
465 | return -1; | |
466 | ||
467 | idx = 0; | |
468 | list_for_each_entry(insn, &file->static_call_list, static_call_node) { | |
469 | ||
470 | site = (struct static_call_site *)sec->data->d_buf + idx; | |
471 | memset(site, 0, sizeof(struct static_call_site)); | |
472 | ||
473 | /* populate reloc for 'addr' */ | |
474 | reloc = malloc(sizeof(*reloc)); | |
44f6a7c0 | 475 | |
1e7e4788 JP |
476 | if (!reloc) { |
477 | perror("malloc"); | |
478 | return -1; | |
479 | } | |
480 | memset(reloc, 0, sizeof(*reloc)); | |
44f6a7c0 JP |
481 | |
482 | insn_to_reloc_sym_addend(insn->sec, insn->offset, reloc); | |
483 | if (!reloc->sym) { | |
484 | WARN_FUNC("static call tramp: missing containing symbol", | |
485 | insn->sec, insn->offset); | |
486 | return -1; | |
487 | } | |
488 | ||
1e7e4788 JP |
489 | reloc->type = R_X86_64_PC32; |
490 | reloc->offset = idx * sizeof(struct static_call_site); | |
491 | reloc->sec = reloc_sec; | |
492 | elf_add_reloc(file->elf, reloc); | |
493 | ||
494 | /* find key symbol */ | |
495 | key_name = strdup(insn->call_dest->name); | |
496 | if (!key_name) { | |
497 | perror("strdup"); | |
498 | return -1; | |
499 | } | |
500 | if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR, | |
501 | STATIC_CALL_TRAMP_PREFIX_LEN)) { | |
502 | WARN("static_call: trampoline name malformed: %s", key_name); | |
503 | return -1; | |
504 | } | |
505 | tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN; | |
506 | memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN); | |
507 | ||
508 | key_sym = find_symbol_by_name(file->elf, tmp); | |
509 | if (!key_sym) { | |
73f44fe1 JP |
510 | if (!module) { |
511 | WARN("static_call: can't find static_call_key symbol: %s", tmp); | |
512 | return -1; | |
513 | } | |
514 | ||
515 | /* | |
516 | * For modules(), the key might not be exported, which | |
517 | * means the module can make static calls but isn't | |
518 | * allowed to change them. | |
519 | * | |
520 | * In that case we temporarily set the key to be the | |
521 | * trampoline address. This is fixed up in | |
522 | * static_call_add_module(). | |
523 | */ | |
524 | key_sym = insn->call_dest; | |
1e7e4788 JP |
525 | } |
526 | free(key_name); | |
527 | ||
528 | /* populate reloc for 'key' */ | |
529 | reloc = malloc(sizeof(*reloc)); | |
530 | if (!reloc) { | |
531 | perror("malloc"); | |
532 | return -1; | |
533 | } | |
534 | memset(reloc, 0, sizeof(*reloc)); | |
535 | reloc->sym = key_sym; | |
5b06fd3b | 536 | reloc->addend = is_sibling_call(insn) ? STATIC_CALL_SITE_TAIL : 0; |
1e7e4788 JP |
537 | reloc->type = R_X86_64_PC32; |
538 | reloc->offset = idx * sizeof(struct static_call_site) + 4; | |
539 | reloc->sec = reloc_sec; | |
540 | elf_add_reloc(file->elf, reloc); | |
541 | ||
542 | idx++; | |
543 | } | |
544 | ||
545 | if (elf_rebuild_reloc_section(file->elf, reloc_sec)) | |
546 | return -1; | |
547 | ||
548 | return 0; | |
549 | } | |
550 | ||
99d00215 PZ |
551 | static int create_mcount_loc_sections(struct objtool_file *file) |
552 | { | |
553 | struct section *sec, *reloc_sec; | |
554 | struct reloc *reloc; | |
555 | unsigned long *loc; | |
556 | struct instruction *insn; | |
557 | int idx; | |
558 | ||
559 | sec = find_section_by_name(file->elf, "__mcount_loc"); | |
560 | if (sec) { | |
561 | INIT_LIST_HEAD(&file->mcount_loc_list); | |
562 | WARN("file already has __mcount_loc section, skipping"); | |
563 | return 0; | |
564 | } | |
565 | ||
566 | if (list_empty(&file->mcount_loc_list)) | |
567 | return 0; | |
568 | ||
569 | idx = 0; | |
570 | list_for_each_entry(insn, &file->mcount_loc_list, mcount_loc_node) | |
571 | idx++; | |
572 | ||
573 | sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx); | |
574 | if (!sec) | |
575 | return -1; | |
576 | ||
577 | reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA); | |
578 | if (!reloc_sec) | |
579 | return -1; | |
580 | ||
581 | idx = 0; | |
582 | list_for_each_entry(insn, &file->mcount_loc_list, mcount_loc_node) { | |
583 | ||
584 | loc = (unsigned long *)sec->data->d_buf + idx; | |
585 | memset(loc, 0, sizeof(unsigned long)); | |
586 | ||
587 | reloc = malloc(sizeof(*reloc)); | |
588 | if (!reloc) { | |
589 | perror("malloc"); | |
590 | return -1; | |
591 | } | |
592 | memset(reloc, 0, sizeof(*reloc)); | |
593 | ||
18a14575 ST |
594 | if (insn->sec->sym) { |
595 | reloc->sym = insn->sec->sym; | |
596 | reloc->addend = insn->offset; | |
597 | } else { | |
598 | reloc->sym = find_symbol_containing(insn->sec, insn->offset); | |
599 | ||
600 | if (!reloc->sym) { | |
601 | WARN("missing symbol for insn at offset 0x%lx\n", | |
602 | insn->offset); | |
603 | return -1; | |
604 | } | |
605 | ||
606 | reloc->addend = insn->offset - reloc->sym->offset; | |
607 | } | |
608 | ||
99d00215 PZ |
609 | reloc->type = R_X86_64_64; |
610 | reloc->offset = idx * sizeof(unsigned long); | |
611 | reloc->sec = reloc_sec; | |
612 | elf_add_reloc(file->elf, reloc); | |
613 | ||
614 | idx++; | |
615 | } | |
616 | ||
617 | if (elf_rebuild_reloc_section(file->elf, reloc_sec)) | |
618 | return -1; | |
619 | ||
620 | return 0; | |
621 | } | |
622 | ||
dcc914f4 JP |
623 | /* |
624 | * Warnings shouldn't be reported for ignored functions. | |
625 | */ | |
626 | static void add_ignores(struct objtool_file *file) | |
627 | { | |
628 | struct instruction *insn; | |
629 | struct section *sec; | |
630 | struct symbol *func; | |
f1974222 | 631 | struct reloc *reloc; |
dcc914f4 | 632 | |
aaf5c623 PZ |
633 | sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard"); |
634 | if (!sec) | |
635 | return; | |
dcc914f4 | 636 | |
f1974222 MH |
637 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
638 | switch (reloc->sym->type) { | |
aaf5c623 | 639 | case STT_FUNC: |
f1974222 | 640 | func = reloc->sym; |
aaf5c623 PZ |
641 | break; |
642 | ||
643 | case STT_SECTION: | |
f1974222 | 644 | func = find_func_by_offset(reloc->sym->sec, reloc->addend); |
7acfe531 | 645 | if (!func) |
dcc914f4 | 646 | continue; |
aaf5c623 | 647 | break; |
dcc914f4 | 648 | |
aaf5c623 | 649 | default: |
f1974222 | 650 | WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type); |
aaf5c623 | 651 | continue; |
dcc914f4 | 652 | } |
aaf5c623 | 653 | |
f0f70adb | 654 | func_for_each_insn(file, func, insn) |
aaf5c623 | 655 | insn->ignore = true; |
dcc914f4 JP |
656 | } |
657 | } | |
658 | ||
ea24213d PZ |
659 | /* |
660 | * This is a whitelist of functions that is allowed to be called with AC set. | |
661 | * The list is meant to be minimal and only contains compiler instrumentation | |
662 | * ABI and a few functions used to implement *_{to,from}_user() functions. | |
663 | * | |
664 | * These functions must not directly change AC, but may PUSHF/POPF. | |
665 | */ | |
666 | static const char *uaccess_safe_builtin[] = { | |
667 | /* KASAN */ | |
668 | "kasan_report", | |
f00748bf | 669 | "kasan_check_range", |
ea24213d PZ |
670 | /* KASAN out-of-line */ |
671 | "__asan_loadN_noabort", | |
672 | "__asan_load1_noabort", | |
673 | "__asan_load2_noabort", | |
674 | "__asan_load4_noabort", | |
675 | "__asan_load8_noabort", | |
676 | "__asan_load16_noabort", | |
677 | "__asan_storeN_noabort", | |
678 | "__asan_store1_noabort", | |
679 | "__asan_store2_noabort", | |
680 | "__asan_store4_noabort", | |
681 | "__asan_store8_noabort", | |
682 | "__asan_store16_noabort", | |
b0b8e56b JH |
683 | "__kasan_check_read", |
684 | "__kasan_check_write", | |
ea24213d PZ |
685 | /* KASAN in-line */ |
686 | "__asan_report_load_n_noabort", | |
687 | "__asan_report_load1_noabort", | |
688 | "__asan_report_load2_noabort", | |
689 | "__asan_report_load4_noabort", | |
690 | "__asan_report_load8_noabort", | |
691 | "__asan_report_load16_noabort", | |
692 | "__asan_report_store_n_noabort", | |
693 | "__asan_report_store1_noabort", | |
694 | "__asan_report_store2_noabort", | |
695 | "__asan_report_store4_noabort", | |
696 | "__asan_report_store8_noabort", | |
697 | "__asan_report_store16_noabort", | |
5f5c9712 | 698 | /* KCSAN */ |
9967683c | 699 | "__kcsan_check_access", |
5f5c9712 ME |
700 | "kcsan_found_watchpoint", |
701 | "kcsan_setup_watchpoint", | |
9967683c | 702 | "kcsan_check_scoped_accesses", |
50a19ad4 ME |
703 | "kcsan_disable_current", |
704 | "kcsan_enable_current_nowarn", | |
5f5c9712 ME |
705 | /* KCSAN/TSAN */ |
706 | "__tsan_func_entry", | |
707 | "__tsan_func_exit", | |
708 | "__tsan_read_range", | |
709 | "__tsan_write_range", | |
710 | "__tsan_read1", | |
711 | "__tsan_read2", | |
712 | "__tsan_read4", | |
713 | "__tsan_read8", | |
714 | "__tsan_read16", | |
715 | "__tsan_write1", | |
716 | "__tsan_write2", | |
717 | "__tsan_write4", | |
718 | "__tsan_write8", | |
719 | "__tsan_write16", | |
a81b3759 ME |
720 | "__tsan_read_write1", |
721 | "__tsan_read_write2", | |
722 | "__tsan_read_write4", | |
723 | "__tsan_read_write8", | |
724 | "__tsan_read_write16", | |
883957b1 ME |
725 | "__tsan_atomic8_load", |
726 | "__tsan_atomic16_load", | |
727 | "__tsan_atomic32_load", | |
728 | "__tsan_atomic64_load", | |
729 | "__tsan_atomic8_store", | |
730 | "__tsan_atomic16_store", | |
731 | "__tsan_atomic32_store", | |
732 | "__tsan_atomic64_store", | |
733 | "__tsan_atomic8_exchange", | |
734 | "__tsan_atomic16_exchange", | |
735 | "__tsan_atomic32_exchange", | |
736 | "__tsan_atomic64_exchange", | |
737 | "__tsan_atomic8_fetch_add", | |
738 | "__tsan_atomic16_fetch_add", | |
739 | "__tsan_atomic32_fetch_add", | |
740 | "__tsan_atomic64_fetch_add", | |
741 | "__tsan_atomic8_fetch_sub", | |
742 | "__tsan_atomic16_fetch_sub", | |
743 | "__tsan_atomic32_fetch_sub", | |
744 | "__tsan_atomic64_fetch_sub", | |
745 | "__tsan_atomic8_fetch_and", | |
746 | "__tsan_atomic16_fetch_and", | |
747 | "__tsan_atomic32_fetch_and", | |
748 | "__tsan_atomic64_fetch_and", | |
749 | "__tsan_atomic8_fetch_or", | |
750 | "__tsan_atomic16_fetch_or", | |
751 | "__tsan_atomic32_fetch_or", | |
752 | "__tsan_atomic64_fetch_or", | |
753 | "__tsan_atomic8_fetch_xor", | |
754 | "__tsan_atomic16_fetch_xor", | |
755 | "__tsan_atomic32_fetch_xor", | |
756 | "__tsan_atomic64_fetch_xor", | |
757 | "__tsan_atomic8_fetch_nand", | |
758 | "__tsan_atomic16_fetch_nand", | |
759 | "__tsan_atomic32_fetch_nand", | |
760 | "__tsan_atomic64_fetch_nand", | |
761 | "__tsan_atomic8_compare_exchange_strong", | |
762 | "__tsan_atomic16_compare_exchange_strong", | |
763 | "__tsan_atomic32_compare_exchange_strong", | |
764 | "__tsan_atomic64_compare_exchange_strong", | |
765 | "__tsan_atomic8_compare_exchange_weak", | |
766 | "__tsan_atomic16_compare_exchange_weak", | |
767 | "__tsan_atomic32_compare_exchange_weak", | |
768 | "__tsan_atomic64_compare_exchange_weak", | |
769 | "__tsan_atomic8_compare_exchange_val", | |
770 | "__tsan_atomic16_compare_exchange_val", | |
771 | "__tsan_atomic32_compare_exchange_val", | |
772 | "__tsan_atomic64_compare_exchange_val", | |
773 | "__tsan_atomic_thread_fence", | |
774 | "__tsan_atomic_signal_fence", | |
ea24213d PZ |
775 | /* KCOV */ |
776 | "write_comp_data", | |
ae033f08 | 777 | "check_kcov_mode", |
ea24213d PZ |
778 | "__sanitizer_cov_trace_pc", |
779 | "__sanitizer_cov_trace_const_cmp1", | |
780 | "__sanitizer_cov_trace_const_cmp2", | |
781 | "__sanitizer_cov_trace_const_cmp4", | |
782 | "__sanitizer_cov_trace_const_cmp8", | |
783 | "__sanitizer_cov_trace_cmp1", | |
784 | "__sanitizer_cov_trace_cmp2", | |
785 | "__sanitizer_cov_trace_cmp4", | |
786 | "__sanitizer_cov_trace_cmp8", | |
36b1c700 | 787 | "__sanitizer_cov_trace_switch", |
ea24213d PZ |
788 | /* UBSAN */ |
789 | "ubsan_type_mismatch_common", | |
790 | "__ubsan_handle_type_mismatch", | |
791 | "__ubsan_handle_type_mismatch_v1", | |
9a50dcaf | 792 | "__ubsan_handle_shift_out_of_bounds", |
ea24213d PZ |
793 | /* misc */ |
794 | "csum_partial_copy_generic", | |
ec6347bb DW |
795 | "copy_mc_fragile", |
796 | "copy_mc_fragile_handle_tail", | |
5da8e4a6 | 797 | "copy_mc_enhanced_fast_string", |
ea24213d PZ |
798 | "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */ |
799 | NULL | |
800 | }; | |
801 | ||
802 | static void add_uaccess_safe(struct objtool_file *file) | |
803 | { | |
804 | struct symbol *func; | |
805 | const char **name; | |
806 | ||
807 | if (!uaccess) | |
808 | return; | |
809 | ||
810 | for (name = uaccess_safe_builtin; *name; name++) { | |
811 | func = find_symbol_by_name(file->elf, *name); | |
812 | if (!func) | |
813 | continue; | |
814 | ||
e10cd8fe | 815 | func->uaccess_safe = true; |
dcc914f4 JP |
816 | } |
817 | } | |
818 | ||
258c7605 JP |
819 | /* |
820 | * FIXME: For now, just ignore any alternatives which add retpolines. This is | |
821 | * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline. | |
822 | * But it at least allows objtool to understand the control flow *around* the | |
823 | * retpoline. | |
824 | */ | |
ff05ab23 | 825 | static int add_ignore_alternatives(struct objtool_file *file) |
258c7605 JP |
826 | { |
827 | struct section *sec; | |
f1974222 | 828 | struct reloc *reloc; |
258c7605 JP |
829 | struct instruction *insn; |
830 | ||
ff05ab23 | 831 | sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts"); |
258c7605 JP |
832 | if (!sec) |
833 | return 0; | |
834 | ||
f1974222 MH |
835 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
836 | if (reloc->sym->type != STT_SECTION) { | |
258c7605 JP |
837 | WARN("unexpected relocation symbol type in %s", sec->name); |
838 | return -1; | |
839 | } | |
840 | ||
f1974222 | 841 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
258c7605 | 842 | if (!insn) { |
ff05ab23 | 843 | WARN("bad .discard.ignore_alts entry"); |
258c7605 JP |
844 | return -1; |
845 | } | |
846 | ||
847 | insn->ignore_alts = true; | |
848 | } | |
849 | ||
850 | return 0; | |
851 | } | |
852 | ||
dcc914f4 JP |
853 | /* |
854 | * Find the destination instructions for all jumps. | |
855 | */ | |
856 | static int add_jump_destinations(struct objtool_file *file) | |
857 | { | |
858 | struct instruction *insn; | |
f1974222 | 859 | struct reloc *reloc; |
dcc914f4 JP |
860 | struct section *dest_sec; |
861 | unsigned long dest_off; | |
862 | ||
863 | for_each_insn(file, insn) { | |
a2296140 | 864 | if (!is_static_jump(insn)) |
dcc914f4 JP |
865 | continue; |
866 | ||
f1974222 | 867 | reloc = find_reloc_by_dest_range(file->elf, insn->sec, |
ecf11ba4 | 868 | insn->offset, insn->len); |
f1974222 | 869 | if (!reloc) { |
dcc914f4 | 870 | dest_sec = insn->sec; |
bfb08f22 | 871 | dest_off = arch_jump_destination(insn); |
f1974222 MH |
872 | } else if (reloc->sym->type == STT_SECTION) { |
873 | dest_sec = reloc->sym->sec; | |
874 | dest_off = arch_dest_reloc_offset(reloc->addend); | |
1f9a1b74 JP |
875 | } else if (!strncmp(reloc->sym->name, "__x86_indirect_thunk_", 21) || |
876 | !strncmp(reloc->sym->name, "__x86_retpoline_", 16)) { | |
39b73533 JP |
877 | /* |
878 | * Retpoline jumps are really dynamic jumps in | |
879 | * disguise, so convert them accordingly. | |
880 | */ | |
b68b9907 JP |
881 | if (insn->type == INSN_JUMP_UNCONDITIONAL) |
882 | insn->type = INSN_JUMP_DYNAMIC; | |
883 | else | |
884 | insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL; | |
885 | ||
b5bc2231 | 886 | insn->retpoline_safe = true; |
39b73533 | 887 | continue; |
ecf11ba4 JP |
888 | } else if (insn->func) { |
889 | /* internal or external sibling call (with reloc) */ | |
f1974222 | 890 | insn->call_dest = reloc->sym; |
5b06fd3b PZ |
891 | if (insn->call_dest->static_call_tramp) { |
892 | list_add_tail(&insn->static_call_node, | |
893 | &file->static_call_list); | |
894 | } | |
dcc914f4 | 895 | continue; |
ecf11ba4 JP |
896 | } else if (reloc->sym->sec->idx) { |
897 | dest_sec = reloc->sym->sec; | |
898 | dest_off = reloc->sym->sym.st_value + | |
899 | arch_dest_reloc_offset(reloc->addend); | |
900 | } else { | |
901 | /* non-func asm code jumping to another file */ | |
902 | continue; | |
dcc914f4 JP |
903 | } |
904 | ||
905 | insn->jump_dest = find_insn(file, dest_sec, dest_off); | |
906 | if (!insn->jump_dest) { | |
907 | ||
908 | /* | |
909 | * This is a special case where an alt instruction | |
910 | * jumps past the end of the section. These are | |
911 | * handled later in handle_group_alt(). | |
912 | */ | |
913 | if (!strcmp(insn->sec->name, ".altinstr_replacement")) | |
914 | continue; | |
915 | ||
916 | WARN_FUNC("can't find jump dest instruction at %s+0x%lx", | |
917 | insn->sec, insn->offset, dest_sec->name, | |
918 | dest_off); | |
919 | return -1; | |
920 | } | |
cd77849a JP |
921 | |
922 | /* | |
54262aa2 | 923 | * Cross-function jump. |
cd77849a JP |
924 | */ |
925 | if (insn->func && insn->jump_dest->func && | |
54262aa2 PZ |
926 | insn->func != insn->jump_dest->func) { |
927 | ||
928 | /* | |
929 | * For GCC 8+, create parent/child links for any cold | |
930 | * subfunctions. This is _mostly_ redundant with a | |
931 | * similar initialization in read_symbols(). | |
932 | * | |
933 | * If a function has aliases, we want the *first* such | |
934 | * function in the symbol table to be the subfunction's | |
935 | * parent. In that case we overwrite the | |
936 | * initialization done in read_symbols(). | |
937 | * | |
938 | * However this code can't completely replace the | |
939 | * read_symbols() code because this doesn't detect the | |
940 | * case where the parent function's only reference to a | |
e7c2bc37 | 941 | * subfunction is through a jump table. |
54262aa2 | 942 | */ |
34ca59e1 JP |
943 | if (!strstr(insn->func->name, ".cold") && |
944 | strstr(insn->jump_dest->func->name, ".cold")) { | |
54262aa2 PZ |
945 | insn->func->cfunc = insn->jump_dest->func; |
946 | insn->jump_dest->func->pfunc = insn->func; | |
947 | ||
948 | } else if (insn->jump_dest->func->pfunc != insn->func->pfunc && | |
949 | insn->jump_dest->offset == insn->jump_dest->func->offset) { | |
950 | ||
ecf11ba4 | 951 | /* internal sibling call (without reloc) */ |
54262aa2 | 952 | insn->call_dest = insn->jump_dest->func; |
5b06fd3b PZ |
953 | if (insn->call_dest->static_call_tramp) { |
954 | list_add_tail(&insn->static_call_node, | |
955 | &file->static_call_list); | |
956 | } | |
54262aa2 | 957 | } |
cd77849a | 958 | } |
dcc914f4 JP |
959 | } |
960 | ||
961 | return 0; | |
962 | } | |
963 | ||
8aa8eb2a AC |
964 | static void remove_insn_ops(struct instruction *insn) |
965 | { | |
966 | struct stack_op *op, *tmp; | |
967 | ||
968 | list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) { | |
969 | list_del(&op->list); | |
970 | free(op); | |
971 | } | |
972 | } | |
973 | ||
2b232a22 JT |
974 | static struct symbol *find_call_destination(struct section *sec, unsigned long offset) |
975 | { | |
976 | struct symbol *call_dest; | |
977 | ||
978 | call_dest = find_func_by_offset(sec, offset); | |
979 | if (!call_dest) | |
980 | call_dest = find_symbol_by_offset(sec, offset); | |
981 | ||
982 | return call_dest; | |
983 | } | |
984 | ||
dcc914f4 JP |
985 | /* |
986 | * Find the destination instructions for all calls. | |
987 | */ | |
988 | static int add_call_destinations(struct objtool_file *file) | |
989 | { | |
990 | struct instruction *insn; | |
991 | unsigned long dest_off; | |
f1974222 | 992 | struct reloc *reloc; |
dcc914f4 JP |
993 | |
994 | for_each_insn(file, insn) { | |
995 | if (insn->type != INSN_CALL) | |
996 | continue; | |
997 | ||
f1974222 | 998 | reloc = find_reloc_by_dest_range(file->elf, insn->sec, |
8b5fa6bc | 999 | insn->offset, insn->len); |
f1974222 | 1000 | if (!reloc) { |
bfb08f22 | 1001 | dest_off = arch_jump_destination(insn); |
2b232a22 | 1002 | insn->call_dest = find_call_destination(insn->sec, dest_off); |
a845c7cf | 1003 | |
7acfe531 JP |
1004 | if (insn->ignore) |
1005 | continue; | |
1006 | ||
1007 | if (!insn->call_dest) { | |
8aa8eb2a | 1008 | WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset); |
dcc914f4 JP |
1009 | return -1; |
1010 | } | |
a845c7cf | 1011 | |
7acfe531 JP |
1012 | if (insn->func && insn->call_dest->type != STT_FUNC) { |
1013 | WARN_FUNC("unsupported call to non-function", | |
1014 | insn->sec, insn->offset); | |
1015 | return -1; | |
1016 | } | |
1017 | ||
f1974222 MH |
1018 | } else if (reloc->sym->type == STT_SECTION) { |
1019 | dest_off = arch_dest_reloc_offset(reloc->addend); | |
2b232a22 JT |
1020 | insn->call_dest = find_call_destination(reloc->sym->sec, |
1021 | dest_off); | |
7acfe531 | 1022 | if (!insn->call_dest) { |
bfb08f22 | 1023 | WARN_FUNC("can't find call dest symbol at %s+0x%lx", |
dcc914f4 | 1024 | insn->sec, insn->offset, |
f1974222 | 1025 | reloc->sym->sec->name, |
bfb08f22 | 1026 | dest_off); |
dcc914f4 JP |
1027 | return -1; |
1028 | } | |
1029 | } else | |
f1974222 | 1030 | insn->call_dest = reloc->sym; |
8aa8eb2a | 1031 | |
0f1441b4 PZ |
1032 | /* |
1033 | * Many compilers cannot disable KCOV with a function attribute | |
1034 | * so they need a little help, NOP out any KCOV calls from noinstr | |
1035 | * text. | |
1036 | */ | |
1037 | if (insn->sec->noinstr && | |
1038 | !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) { | |
d832c005 PZ |
1039 | if (reloc) { |
1040 | reloc->type = R_NONE; | |
1041 | elf_write_reloc(file->elf, reloc); | |
0f1441b4 PZ |
1042 | } |
1043 | ||
1044 | elf_write_insn(file->elf, insn->sec, | |
1045 | insn->offset, insn->len, | |
1046 | arch_nop_insn(insn->len)); | |
1047 | insn->type = INSN_NOP; | |
1048 | } | |
1049 | ||
99d00215 PZ |
1050 | if (mcount && !strcmp(insn->call_dest->name, "__fentry__")) { |
1051 | if (reloc) { | |
1052 | reloc->type = R_NONE; | |
1053 | elf_write_reloc(file->elf, reloc); | |
1054 | } | |
1055 | ||
1056 | elf_write_insn(file->elf, insn->sec, | |
1057 | insn->offset, insn->len, | |
1058 | arch_nop_insn(insn->len)); | |
1059 | ||
1060 | insn->type = INSN_NOP; | |
1061 | ||
1062 | list_add_tail(&insn->mcount_loc_node, | |
1063 | &file->mcount_loc_list); | |
1064 | } | |
1065 | ||
8aa8eb2a AC |
1066 | /* |
1067 | * Whatever stack impact regular CALLs have, should be undone | |
1068 | * by the RETURN of the called function. | |
1069 | * | |
1070 | * Annotated intra-function calls retain the stack_ops but | |
1071 | * are converted to JUMP, see read_intra_function_calls(). | |
1072 | */ | |
1073 | remove_insn_ops(insn); | |
dcc914f4 JP |
1074 | } |
1075 | ||
1076 | return 0; | |
1077 | } | |
1078 | ||
1079 | /* | |
c9c324dc JP |
1080 | * The .alternatives section requires some extra special care over and above |
1081 | * other special sections because alternatives are patched in place. | |
dcc914f4 JP |
1082 | */ |
1083 | static int handle_group_alt(struct objtool_file *file, | |
1084 | struct special_alt *special_alt, | |
1085 | struct instruction *orig_insn, | |
1086 | struct instruction **new_insn) | |
1087 | { | |
c9c324dc | 1088 | struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL; |
b23cc71c | 1089 | struct alt_group *orig_alt_group, *new_alt_group; |
dcc914f4 JP |
1090 | unsigned long dest_off; |
1091 | ||
b23cc71c JP |
1092 | |
1093 | orig_alt_group = malloc(sizeof(*orig_alt_group)); | |
1094 | if (!orig_alt_group) { | |
1095 | WARN("malloc failed"); | |
1096 | return -1; | |
1097 | } | |
c9c324dc JP |
1098 | orig_alt_group->cfi = calloc(special_alt->orig_len, |
1099 | sizeof(struct cfi_state *)); | |
1100 | if (!orig_alt_group->cfi) { | |
1101 | WARN("calloc failed"); | |
1102 | return -1; | |
1103 | } | |
1104 | ||
dcc914f4 JP |
1105 | last_orig_insn = NULL; |
1106 | insn = orig_insn; | |
1107 | sec_for_each_insn_from(file, insn) { | |
1108 | if (insn->offset >= special_alt->orig_off + special_alt->orig_len) | |
1109 | break; | |
1110 | ||
b23cc71c | 1111 | insn->alt_group = orig_alt_group; |
dcc914f4 JP |
1112 | last_orig_insn = insn; |
1113 | } | |
b23cc71c JP |
1114 | orig_alt_group->orig_group = NULL; |
1115 | orig_alt_group->first_insn = orig_insn; | |
1116 | orig_alt_group->last_insn = last_orig_insn; | |
dcc914f4 | 1117 | |
17bc3391 | 1118 | |
c9c324dc JP |
1119 | new_alt_group = malloc(sizeof(*new_alt_group)); |
1120 | if (!new_alt_group) { | |
1121 | WARN("malloc failed"); | |
1122 | return -1; | |
dcc914f4 | 1123 | } |
dcc914f4 | 1124 | |
c9c324dc JP |
1125 | if (special_alt->new_len < special_alt->orig_len) { |
1126 | /* | |
1127 | * Insert a fake nop at the end to make the replacement | |
1128 | * alt_group the same size as the original. This is needed to | |
1129 | * allow propagate_alt_cfi() to do its magic. When the last | |
1130 | * instruction affects the stack, the instruction after it (the | |
1131 | * nop) will propagate the new state to the shared CFI array. | |
1132 | */ | |
1133 | nop = malloc(sizeof(*nop)); | |
1134 | if (!nop) { | |
1135 | WARN("malloc failed"); | |
17bc3391 JP |
1136 | return -1; |
1137 | } | |
c9c324dc JP |
1138 | memset(nop, 0, sizeof(*nop)); |
1139 | INIT_LIST_HEAD(&nop->alts); | |
1140 | INIT_LIST_HEAD(&nop->stack_ops); | |
1141 | init_cfi_state(&nop->cfi); | |
1142 | ||
1143 | nop->sec = special_alt->new_sec; | |
1144 | nop->offset = special_alt->new_off + special_alt->new_len; | |
1145 | nop->len = special_alt->orig_len - special_alt->new_len; | |
1146 | nop->type = INSN_NOP; | |
1147 | nop->func = orig_insn->func; | |
1148 | nop->alt_group = new_alt_group; | |
1149 | nop->ignore = orig_insn->ignore_alts; | |
dcc914f4 | 1150 | } |
17bc3391 | 1151 | |
c9c324dc JP |
1152 | if (!special_alt->new_len) { |
1153 | *new_insn = nop; | |
1154 | goto end; | |
dcc914f4 JP |
1155 | } |
1156 | ||
dcc914f4 JP |
1157 | insn = *new_insn; |
1158 | sec_for_each_insn_from(file, insn) { | |
45245f51 JT |
1159 | struct reloc *alt_reloc; |
1160 | ||
dcc914f4 JP |
1161 | if (insn->offset >= special_alt->new_off + special_alt->new_len) |
1162 | break; | |
1163 | ||
1164 | last_new_insn = insn; | |
1165 | ||
a845c7cf | 1166 | insn->ignore = orig_insn->ignore_alts; |
a4d09dde | 1167 | insn->func = orig_insn->func; |
b23cc71c | 1168 | insn->alt_group = new_alt_group; |
a845c7cf | 1169 | |
dc419723 JP |
1170 | /* |
1171 | * Since alternative replacement code is copy/pasted by the | |
1172 | * kernel after applying relocations, generally such code can't | |
1173 | * have relative-address relocation references to outside the | |
1174 | * .altinstr_replacement section, unless the arch's | |
1175 | * alternatives code can adjust the relative offsets | |
1176 | * accordingly. | |
dc419723 | 1177 | */ |
45245f51 JT |
1178 | alt_reloc = find_reloc_by_dest_range(file->elf, insn->sec, |
1179 | insn->offset, insn->len); | |
1180 | if (alt_reloc && | |
1181 | !arch_support_alt_relocation(special_alt, insn, alt_reloc)) { | |
dc419723 JP |
1182 | |
1183 | WARN_FUNC("unsupported relocation in alternatives section", | |
1184 | insn->sec, insn->offset); | |
1185 | return -1; | |
1186 | } | |
1187 | ||
a2296140 | 1188 | if (!is_static_jump(insn)) |
dcc914f4 JP |
1189 | continue; |
1190 | ||
1191 | if (!insn->immediate) | |
1192 | continue; | |
1193 | ||
bfb08f22 | 1194 | dest_off = arch_jump_destination(insn); |
c9c324dc JP |
1195 | if (dest_off == special_alt->new_off + special_alt->new_len) |
1196 | insn->jump_dest = next_insn_same_sec(file, last_orig_insn); | |
dcc914f4 JP |
1197 | |
1198 | if (!insn->jump_dest) { | |
1199 | WARN_FUNC("can't find alternative jump destination", | |
1200 | insn->sec, insn->offset); | |
1201 | return -1; | |
1202 | } | |
1203 | } | |
1204 | ||
1205 | if (!last_new_insn) { | |
1206 | WARN_FUNC("can't find last new alternative instruction", | |
1207 | special_alt->new_sec, special_alt->new_off); | |
1208 | return -1; | |
1209 | } | |
1210 | ||
c9c324dc JP |
1211 | if (nop) |
1212 | list_add(&nop->list, &last_new_insn->list); | |
1213 | end: | |
b23cc71c JP |
1214 | new_alt_group->orig_group = orig_alt_group; |
1215 | new_alt_group->first_insn = *new_insn; | |
c9c324dc JP |
1216 | new_alt_group->last_insn = nop ? : last_new_insn; |
1217 | new_alt_group->cfi = orig_alt_group->cfi; | |
dcc914f4 JP |
1218 | return 0; |
1219 | } | |
1220 | ||
1221 | /* | |
1222 | * A jump table entry can either convert a nop to a jump or a jump to a nop. | |
1223 | * If the original instruction is a jump, make the alt entry an effective nop | |
1224 | * by just skipping the original instruction. | |
1225 | */ | |
1226 | static int handle_jump_alt(struct objtool_file *file, | |
1227 | struct special_alt *special_alt, | |
1228 | struct instruction *orig_insn, | |
1229 | struct instruction **new_insn) | |
1230 | { | |
1231 | if (orig_insn->type == INSN_NOP) | |
1232 | return 0; | |
1233 | ||
1234 | if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) { | |
1235 | WARN_FUNC("unsupported instruction at jump label", | |
1236 | orig_insn->sec, orig_insn->offset); | |
1237 | return -1; | |
1238 | } | |
1239 | ||
1240 | *new_insn = list_next_entry(orig_insn, list); | |
1241 | return 0; | |
1242 | } | |
1243 | ||
1244 | /* | |
1245 | * Read all the special sections which have alternate instructions which can be | |
1246 | * patched in or redirected to at runtime. Each instruction having alternate | |
1247 | * instruction(s) has them added to its insn->alts list, which will be | |
1248 | * traversed in validate_branch(). | |
1249 | */ | |
1250 | static int add_special_section_alts(struct objtool_file *file) | |
1251 | { | |
1252 | struct list_head special_alts; | |
1253 | struct instruction *orig_insn, *new_insn; | |
1254 | struct special_alt *special_alt, *tmp; | |
1255 | struct alternative *alt; | |
1256 | int ret; | |
1257 | ||
1258 | ret = special_get_alts(file->elf, &special_alts); | |
1259 | if (ret) | |
1260 | return ret; | |
1261 | ||
1262 | list_for_each_entry_safe(special_alt, tmp, &special_alts, list) { | |
dcc914f4 JP |
1263 | |
1264 | orig_insn = find_insn(file, special_alt->orig_sec, | |
1265 | special_alt->orig_off); | |
1266 | if (!orig_insn) { | |
1267 | WARN_FUNC("special: can't find orig instruction", | |
1268 | special_alt->orig_sec, special_alt->orig_off); | |
1269 | ret = -1; | |
1270 | goto out; | |
1271 | } | |
1272 | ||
1273 | new_insn = NULL; | |
1274 | if (!special_alt->group || special_alt->new_len) { | |
1275 | new_insn = find_insn(file, special_alt->new_sec, | |
1276 | special_alt->new_off); | |
1277 | if (!new_insn) { | |
1278 | WARN_FUNC("special: can't find new instruction", | |
1279 | special_alt->new_sec, | |
1280 | special_alt->new_off); | |
1281 | ret = -1; | |
1282 | goto out; | |
1283 | } | |
1284 | } | |
1285 | ||
1286 | if (special_alt->group) { | |
7170cf47 JT |
1287 | if (!special_alt->orig_len) { |
1288 | WARN_FUNC("empty alternative entry", | |
1289 | orig_insn->sec, orig_insn->offset); | |
1290 | continue; | |
1291 | } | |
1292 | ||
dcc914f4 JP |
1293 | ret = handle_group_alt(file, special_alt, orig_insn, |
1294 | &new_insn); | |
1295 | if (ret) | |
1296 | goto out; | |
1297 | } else if (special_alt->jump_or_nop) { | |
1298 | ret = handle_jump_alt(file, special_alt, orig_insn, | |
1299 | &new_insn); | |
1300 | if (ret) | |
1301 | goto out; | |
1302 | } | |
1303 | ||
258c7605 JP |
1304 | alt = malloc(sizeof(*alt)); |
1305 | if (!alt) { | |
1306 | WARN("malloc failed"); | |
1307 | ret = -1; | |
1308 | goto out; | |
1309 | } | |
1310 | ||
dcc914f4 | 1311 | alt->insn = new_insn; |
764eef4b | 1312 | alt->skip_orig = special_alt->skip_orig; |
ea24213d | 1313 | orig_insn->ignore_alts |= special_alt->skip_alt; |
dcc914f4 JP |
1314 | list_add_tail(&alt->list, &orig_insn->alts); |
1315 | ||
1316 | list_del(&special_alt->list); | |
1317 | free(special_alt); | |
1318 | } | |
1319 | ||
1320 | out: | |
1321 | return ret; | |
1322 | } | |
1323 | ||
e7c2bc37 | 1324 | static int add_jump_table(struct objtool_file *file, struct instruction *insn, |
f1974222 | 1325 | struct reloc *table) |
dcc914f4 | 1326 | { |
f1974222 | 1327 | struct reloc *reloc = table; |
e7c2bc37 | 1328 | struct instruction *dest_insn; |
dcc914f4 | 1329 | struct alternative *alt; |
fd35c88b JP |
1330 | struct symbol *pfunc = insn->func->pfunc; |
1331 | unsigned int prev_offset = 0; | |
dcc914f4 | 1332 | |
e7c2bc37 | 1333 | /* |
f1974222 | 1334 | * Each @reloc is a switch table relocation which points to the target |
e7c2bc37 JP |
1335 | * instruction. |
1336 | */ | |
f1974222 | 1337 | list_for_each_entry_from(reloc, &table->sec->reloc_list, list) { |
bd98c813 JH |
1338 | |
1339 | /* Check for the end of the table: */ | |
f1974222 | 1340 | if (reloc != table && reloc->jump_table_start) |
dcc914f4 JP |
1341 | break; |
1342 | ||
e7c2bc37 | 1343 | /* Make sure the table entries are consecutive: */ |
f1974222 | 1344 | if (prev_offset && reloc->offset != prev_offset + 8) |
fd35c88b JP |
1345 | break; |
1346 | ||
1347 | /* Detect function pointers from contiguous objects: */ | |
f1974222 MH |
1348 | if (reloc->sym->sec == pfunc->sec && |
1349 | reloc->addend == pfunc->offset) | |
fd35c88b JP |
1350 | break; |
1351 | ||
f1974222 | 1352 | dest_insn = find_insn(file, reloc->sym->sec, reloc->addend); |
e7c2bc37 | 1353 | if (!dest_insn) |
dcc914f4 JP |
1354 | break; |
1355 | ||
e7c2bc37 | 1356 | /* Make sure the destination is in the same function: */ |
e65050b9 | 1357 | if (!dest_insn->func || dest_insn->func->pfunc != pfunc) |
13810435 | 1358 | break; |
dcc914f4 JP |
1359 | |
1360 | alt = malloc(sizeof(*alt)); | |
1361 | if (!alt) { | |
1362 | WARN("malloc failed"); | |
1363 | return -1; | |
1364 | } | |
1365 | ||
e7c2bc37 | 1366 | alt->insn = dest_insn; |
dcc914f4 | 1367 | list_add_tail(&alt->list, &insn->alts); |
f1974222 | 1368 | prev_offset = reloc->offset; |
fd35c88b JP |
1369 | } |
1370 | ||
1371 | if (!prev_offset) { | |
1372 | WARN_FUNC("can't find switch jump table", | |
1373 | insn->sec, insn->offset); | |
1374 | return -1; | |
dcc914f4 JP |
1375 | } |
1376 | ||
1377 | return 0; | |
1378 | } | |
1379 | ||
1380 | /* | |
d871f7b5 RG |
1381 | * find_jump_table() - Given a dynamic jump, find the switch jump table |
1382 | * associated with it. | |
dcc914f4 | 1383 | */ |
f1974222 | 1384 | static struct reloc *find_jump_table(struct objtool_file *file, |
dcc914f4 JP |
1385 | struct symbol *func, |
1386 | struct instruction *insn) | |
1387 | { | |
d871f7b5 | 1388 | struct reloc *table_reloc; |
113d4bc9 | 1389 | struct instruction *dest_insn, *orig_insn = insn; |
dcc914f4 | 1390 | |
99ce7962 PZ |
1391 | /* |
1392 | * Backward search using the @first_jump_src links, these help avoid | |
1393 | * much of the 'in between' code. Which avoids us getting confused by | |
1394 | * it. | |
1395 | */ | |
7dec80cc | 1396 | for (; |
1119d265 JP |
1397 | insn && insn->func && insn->func->pfunc == func; |
1398 | insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) { | |
99ce7962 | 1399 | |
7dec80cc | 1400 | if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC) |
dcc914f4 JP |
1401 | break; |
1402 | ||
1403 | /* allow small jumps within the range */ | |
1404 | if (insn->type == INSN_JUMP_UNCONDITIONAL && | |
1405 | insn->jump_dest && | |
1406 | (insn->jump_dest->offset <= insn->offset || | |
1407 | insn->jump_dest->offset > orig_insn->offset)) | |
1408 | break; | |
1409 | ||
d871f7b5 | 1410 | table_reloc = arch_find_switch_table(file, insn); |
f1974222 | 1411 | if (!table_reloc) |
e7c2bc37 | 1412 | continue; |
f1974222 | 1413 | dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend); |
113d4bc9 JP |
1414 | if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func) |
1415 | continue; | |
7dec80cc | 1416 | |
f1974222 | 1417 | return table_reloc; |
dcc914f4 JP |
1418 | } |
1419 | ||
1420 | return NULL; | |
1421 | } | |
1422 | ||
bd98c813 JH |
1423 | /* |
1424 | * First pass: Mark the head of each jump table so that in the next pass, | |
1425 | * we know when a given jump table ends and the next one starts. | |
1426 | */ | |
1427 | static void mark_func_jump_tables(struct objtool_file *file, | |
1428 | struct symbol *func) | |
dcc914f4 | 1429 | { |
bd98c813 | 1430 | struct instruction *insn, *last = NULL; |
f1974222 | 1431 | struct reloc *reloc; |
dcc914f4 | 1432 | |
f0f70adb | 1433 | func_for_each_insn(file, func, insn) { |
99ce7962 PZ |
1434 | if (!last) |
1435 | last = insn; | |
1436 | ||
1437 | /* | |
1438 | * Store back-pointers for unconditional forward jumps such | |
e7c2bc37 | 1439 | * that find_jump_table() can back-track using those and |
99ce7962 PZ |
1440 | * avoid some potentially confusing code. |
1441 | */ | |
1442 | if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest && | |
1443 | insn->offset > last->offset && | |
1444 | insn->jump_dest->offset > insn->offset && | |
1445 | !insn->jump_dest->first_jump_src) { | |
1446 | ||
1447 | insn->jump_dest->first_jump_src = insn; | |
1448 | last = insn->jump_dest; | |
1449 | } | |
1450 | ||
dcc914f4 JP |
1451 | if (insn->type != INSN_JUMP_DYNAMIC) |
1452 | continue; | |
1453 | ||
f1974222 MH |
1454 | reloc = find_jump_table(file, func, insn); |
1455 | if (reloc) { | |
1456 | reloc->jump_table_start = true; | |
1457 | insn->jump_table = reloc; | |
dcc914f4 | 1458 | } |
dcc914f4 | 1459 | } |
bd98c813 JH |
1460 | } |
1461 | ||
1462 | static int add_func_jump_tables(struct objtool_file *file, | |
1463 | struct symbol *func) | |
1464 | { | |
1465 | struct instruction *insn; | |
1466 | int ret; | |
1467 | ||
f0f70adb | 1468 | func_for_each_insn(file, func, insn) { |
bd98c813 JH |
1469 | if (!insn->jump_table) |
1470 | continue; | |
dcc914f4 | 1471 | |
bd98c813 | 1472 | ret = add_jump_table(file, insn, insn->jump_table); |
dcc914f4 JP |
1473 | if (ret) |
1474 | return ret; | |
1475 | } | |
1476 | ||
1477 | return 0; | |
1478 | } | |
1479 | ||
1480 | /* | |
1481 | * For some switch statements, gcc generates a jump table in the .rodata | |
1482 | * section which contains a list of addresses within the function to jump to. | |
1483 | * This finds these jump tables and adds them to the insn->alts lists. | |
1484 | */ | |
e7c2bc37 | 1485 | static int add_jump_table_alts(struct objtool_file *file) |
dcc914f4 JP |
1486 | { |
1487 | struct section *sec; | |
1488 | struct symbol *func; | |
1489 | int ret; | |
1490 | ||
4a60aa05 | 1491 | if (!file->rodata) |
dcc914f4 JP |
1492 | return 0; |
1493 | ||
baa41469 | 1494 | for_each_sec(file, sec) { |
dcc914f4 JP |
1495 | list_for_each_entry(func, &sec->symbol_list, list) { |
1496 | if (func->type != STT_FUNC) | |
1497 | continue; | |
1498 | ||
bd98c813 | 1499 | mark_func_jump_tables(file, func); |
e7c2bc37 | 1500 | ret = add_func_jump_tables(file, func); |
dcc914f4 JP |
1501 | if (ret) |
1502 | return ret; | |
1503 | } | |
1504 | } | |
1505 | ||
1506 | return 0; | |
1507 | } | |
1508 | ||
b735bd3e JP |
1509 | static void set_func_state(struct cfi_state *state) |
1510 | { | |
1511 | state->cfa = initial_func_cfi.cfa; | |
1512 | memcpy(&state->regs, &initial_func_cfi.regs, | |
1513 | CFI_NUM_REGS * sizeof(struct cfi_reg)); | |
1514 | state->stack_size = initial_func_cfi.cfa.offset; | |
1515 | } | |
1516 | ||
39358a03 JP |
1517 | static int read_unwind_hints(struct objtool_file *file) |
1518 | { | |
f1974222 MH |
1519 | struct section *sec, *relocsec; |
1520 | struct reloc *reloc; | |
39358a03 JP |
1521 | struct unwind_hint *hint; |
1522 | struct instruction *insn; | |
39358a03 JP |
1523 | int i; |
1524 | ||
1525 | sec = find_section_by_name(file->elf, ".discard.unwind_hints"); | |
1526 | if (!sec) | |
1527 | return 0; | |
1528 | ||
f1974222 MH |
1529 | relocsec = sec->reloc; |
1530 | if (!relocsec) { | |
39358a03 JP |
1531 | WARN("missing .rela.discard.unwind_hints section"); |
1532 | return -1; | |
1533 | } | |
1534 | ||
1535 | if (sec->len % sizeof(struct unwind_hint)) { | |
1536 | WARN("struct unwind_hint size mismatch"); | |
1537 | return -1; | |
1538 | } | |
1539 | ||
1540 | file->hints = true; | |
1541 | ||
1542 | for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) { | |
1543 | hint = (struct unwind_hint *)sec->data->d_buf + i; | |
1544 | ||
f1974222 MH |
1545 | reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint)); |
1546 | if (!reloc) { | |
1547 | WARN("can't find reloc for unwind_hints[%d]", i); | |
39358a03 JP |
1548 | return -1; |
1549 | } | |
1550 | ||
f1974222 | 1551 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
39358a03 JP |
1552 | if (!insn) { |
1553 | WARN("can't find insn for unwind_hints[%d]", i); | |
1554 | return -1; | |
1555 | } | |
1556 | ||
b735bd3e | 1557 | insn->hint = true; |
39358a03 | 1558 | |
b735bd3e JP |
1559 | if (hint->type == UNWIND_HINT_TYPE_FUNC) { |
1560 | set_func_state(&insn->cfi); | |
39358a03 JP |
1561 | continue; |
1562 | } | |
1563 | ||
edea9e6b | 1564 | if (arch_decode_hint_reg(insn, hint->sp_reg)) { |
39358a03 JP |
1565 | WARN_FUNC("unsupported unwind_hint sp base reg %d", |
1566 | insn->sec, insn->offset, hint->sp_reg); | |
1567 | return -1; | |
1568 | } | |
1569 | ||
b735bd3e | 1570 | insn->cfi.cfa.offset = bswap_if_needed(hint->sp_offset); |
e7c0219b PZ |
1571 | insn->cfi.type = hint->type; |
1572 | insn->cfi.end = hint->end; | |
39358a03 JP |
1573 | } |
1574 | ||
1575 | return 0; | |
1576 | } | |
1577 | ||
b5bc2231 PZ |
1578 | static int read_retpoline_hints(struct objtool_file *file) |
1579 | { | |
63474dc4 | 1580 | struct section *sec; |
b5bc2231 | 1581 | struct instruction *insn; |
f1974222 | 1582 | struct reloc *reloc; |
b5bc2231 | 1583 | |
63474dc4 | 1584 | sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe"); |
b5bc2231 PZ |
1585 | if (!sec) |
1586 | return 0; | |
1587 | ||
f1974222 MH |
1588 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
1589 | if (reloc->sym->type != STT_SECTION) { | |
63474dc4 | 1590 | WARN("unexpected relocation symbol type in %s", sec->name); |
b5bc2231 PZ |
1591 | return -1; |
1592 | } | |
1593 | ||
f1974222 | 1594 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
b5bc2231 | 1595 | if (!insn) { |
63474dc4 | 1596 | WARN("bad .discard.retpoline_safe entry"); |
b5bc2231 PZ |
1597 | return -1; |
1598 | } | |
1599 | ||
1600 | if (insn->type != INSN_JUMP_DYNAMIC && | |
1601 | insn->type != INSN_CALL_DYNAMIC) { | |
63474dc4 | 1602 | WARN_FUNC("retpoline_safe hint not an indirect jump/call", |
b5bc2231 PZ |
1603 | insn->sec, insn->offset); |
1604 | return -1; | |
1605 | } | |
1606 | ||
1607 | insn->retpoline_safe = true; | |
1608 | } | |
1609 | ||
1610 | return 0; | |
1611 | } | |
1612 | ||
c4a33939 PZ |
1613 | static int read_instr_hints(struct objtool_file *file) |
1614 | { | |
1615 | struct section *sec; | |
1616 | struct instruction *insn; | |
f1974222 | 1617 | struct reloc *reloc; |
c4a33939 PZ |
1618 | |
1619 | sec = find_section_by_name(file->elf, ".rela.discard.instr_end"); | |
1620 | if (!sec) | |
1621 | return 0; | |
1622 | ||
f1974222 MH |
1623 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
1624 | if (reloc->sym->type != STT_SECTION) { | |
c4a33939 PZ |
1625 | WARN("unexpected relocation symbol type in %s", sec->name); |
1626 | return -1; | |
1627 | } | |
1628 | ||
f1974222 | 1629 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
c4a33939 PZ |
1630 | if (!insn) { |
1631 | WARN("bad .discard.instr_end entry"); | |
1632 | return -1; | |
1633 | } | |
1634 | ||
1635 | insn->instr--; | |
1636 | } | |
1637 | ||
1638 | sec = find_section_by_name(file->elf, ".rela.discard.instr_begin"); | |
1639 | if (!sec) | |
1640 | return 0; | |
1641 | ||
f1974222 MH |
1642 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
1643 | if (reloc->sym->type != STT_SECTION) { | |
c4a33939 PZ |
1644 | WARN("unexpected relocation symbol type in %s", sec->name); |
1645 | return -1; | |
1646 | } | |
1647 | ||
f1974222 | 1648 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
c4a33939 PZ |
1649 | if (!insn) { |
1650 | WARN("bad .discard.instr_begin entry"); | |
1651 | return -1; | |
1652 | } | |
1653 | ||
1654 | insn->instr++; | |
1655 | } | |
1656 | ||
1657 | return 0; | |
1658 | } | |
1659 | ||
8aa8eb2a AC |
1660 | static int read_intra_function_calls(struct objtool_file *file) |
1661 | { | |
1662 | struct instruction *insn; | |
1663 | struct section *sec; | |
f1974222 | 1664 | struct reloc *reloc; |
8aa8eb2a AC |
1665 | |
1666 | sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls"); | |
1667 | if (!sec) | |
1668 | return 0; | |
1669 | ||
f1974222 | 1670 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
8aa8eb2a AC |
1671 | unsigned long dest_off; |
1672 | ||
f1974222 | 1673 | if (reloc->sym->type != STT_SECTION) { |
8aa8eb2a AC |
1674 | WARN("unexpected relocation symbol type in %s", |
1675 | sec->name); | |
1676 | return -1; | |
1677 | } | |
1678 | ||
f1974222 | 1679 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
8aa8eb2a AC |
1680 | if (!insn) { |
1681 | WARN("bad .discard.intra_function_call entry"); | |
1682 | return -1; | |
1683 | } | |
1684 | ||
1685 | if (insn->type != INSN_CALL) { | |
1686 | WARN_FUNC("intra_function_call not a direct call", | |
1687 | insn->sec, insn->offset); | |
1688 | return -1; | |
1689 | } | |
1690 | ||
1691 | /* | |
1692 | * Treat intra-function CALLs as JMPs, but with a stack_op. | |
1693 | * See add_call_destinations(), which strips stack_ops from | |
1694 | * normal CALLs. | |
1695 | */ | |
1696 | insn->type = INSN_JUMP_UNCONDITIONAL; | |
1697 | ||
1698 | dest_off = insn->offset + insn->len + insn->immediate; | |
1699 | insn->jump_dest = find_insn(file, insn->sec, dest_off); | |
1700 | if (!insn->jump_dest) { | |
1701 | WARN_FUNC("can't find call dest at %s+0x%lx", | |
1702 | insn->sec, insn->offset, | |
1703 | insn->sec->name, dest_off); | |
1704 | return -1; | |
1705 | } | |
1706 | } | |
1707 | ||
1708 | return 0; | |
1709 | } | |
1710 | ||
1e7e4788 JP |
1711 | static int read_static_call_tramps(struct objtool_file *file) |
1712 | { | |
1713 | struct section *sec; | |
1714 | struct symbol *func; | |
1715 | ||
1716 | for_each_sec(file, sec) { | |
1717 | list_for_each_entry(func, &sec->symbol_list, list) { | |
1718 | if (func->bind == STB_GLOBAL && | |
1719 | !strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR, | |
1720 | strlen(STATIC_CALL_TRAMP_PREFIX_STR))) | |
1721 | func->static_call_tramp = true; | |
1722 | } | |
1723 | } | |
1724 | ||
1725 | return 0; | |
1726 | } | |
1727 | ||
4a60aa05 AX |
1728 | static void mark_rodata(struct objtool_file *file) |
1729 | { | |
1730 | struct section *sec; | |
1731 | bool found = false; | |
1732 | ||
1733 | /* | |
87b512de JP |
1734 | * Search for the following rodata sections, each of which can |
1735 | * potentially contain jump tables: | |
1736 | * | |
1737 | * - .rodata: can contain GCC switch tables | |
1738 | * - .rodata.<func>: same, if -fdata-sections is being used | |
1739 | * - .rodata..c_jump_table: contains C annotated jump tables | |
1740 | * | |
1741 | * .rodata.str1.* sections are ignored; they don't contain jump tables. | |
4a60aa05 AX |
1742 | */ |
1743 | for_each_sec(file, sec) { | |
1ee44470 MS |
1744 | if (!strncmp(sec->name, ".rodata", 7) && |
1745 | !strstr(sec->name, ".str1.")) { | |
4a60aa05 AX |
1746 | sec->rodata = true; |
1747 | found = true; | |
1748 | } | |
1749 | } | |
1750 | ||
1751 | file->rodata = found; | |
1752 | } | |
1753 | ||
dcc914f4 JP |
1754 | static int decode_sections(struct objtool_file *file) |
1755 | { | |
1756 | int ret; | |
1757 | ||
4a60aa05 AX |
1758 | mark_rodata(file); |
1759 | ||
dcc914f4 JP |
1760 | ret = decode_instructions(file); |
1761 | if (ret) | |
1762 | return ret; | |
1763 | ||
1764 | ret = add_dead_ends(file); | |
1765 | if (ret) | |
1766 | return ret; | |
1767 | ||
1768 | add_ignores(file); | |
ea24213d | 1769 | add_uaccess_safe(file); |
dcc914f4 | 1770 | |
ff05ab23 | 1771 | ret = add_ignore_alternatives(file); |
258c7605 JP |
1772 | if (ret) |
1773 | return ret; | |
1774 | ||
5b06fd3b PZ |
1775 | ret = read_static_call_tramps(file); |
1776 | if (ret) | |
1777 | return ret; | |
1778 | ||
dcc914f4 JP |
1779 | ret = add_jump_destinations(file); |
1780 | if (ret) | |
1781 | return ret; | |
1782 | ||
a845c7cf | 1783 | ret = add_special_section_alts(file); |
dcc914f4 JP |
1784 | if (ret) |
1785 | return ret; | |
1786 | ||
8aa8eb2a AC |
1787 | ret = read_intra_function_calls(file); |
1788 | if (ret) | |
1789 | return ret; | |
1790 | ||
a845c7cf | 1791 | ret = add_call_destinations(file); |
dcc914f4 JP |
1792 | if (ret) |
1793 | return ret; | |
1794 | ||
e7c2bc37 | 1795 | ret = add_jump_table_alts(file); |
dcc914f4 JP |
1796 | if (ret) |
1797 | return ret; | |
1798 | ||
39358a03 JP |
1799 | ret = read_unwind_hints(file); |
1800 | if (ret) | |
1801 | return ret; | |
1802 | ||
b5bc2231 PZ |
1803 | ret = read_retpoline_hints(file); |
1804 | if (ret) | |
1805 | return ret; | |
1806 | ||
c4a33939 PZ |
1807 | ret = read_instr_hints(file); |
1808 | if (ret) | |
1809 | return ret; | |
1810 | ||
dcc914f4 JP |
1811 | return 0; |
1812 | } | |
1813 | ||
1814 | static bool is_fentry_call(struct instruction *insn) | |
1815 | { | |
87cf61fe | 1816 | if (insn->type == INSN_CALL && insn->call_dest && |
dcc914f4 JP |
1817 | insn->call_dest->type == STT_NOTYPE && |
1818 | !strcmp(insn->call_dest->name, "__fentry__")) | |
1819 | return true; | |
1820 | ||
1821 | return false; | |
1822 | } | |
1823 | ||
e25eea89 | 1824 | static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state) |
dcc914f4 | 1825 | { |
e7c0219b | 1826 | struct cfi_state *cfi = &state->cfi; |
baa41469 JP |
1827 | int i; |
1828 | ||
e7c0219b | 1829 | if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap) |
e25eea89 PZ |
1830 | return true; |
1831 | ||
b735bd3e | 1832 | if (cfi->cfa.offset != initial_func_cfi.cfa.offset) |
baa41469 JP |
1833 | return true; |
1834 | ||
b735bd3e | 1835 | if (cfi->stack_size != initial_func_cfi.cfa.offset) |
e25eea89 PZ |
1836 | return true; |
1837 | ||
1838 | for (i = 0; i < CFI_NUM_REGS; i++) { | |
e7c0219b PZ |
1839 | if (cfi->regs[i].base != initial_func_cfi.regs[i].base || |
1840 | cfi->regs[i].offset != initial_func_cfi.regs[i].offset) | |
baa41469 | 1841 | return true; |
e25eea89 | 1842 | } |
baa41469 JP |
1843 | |
1844 | return false; | |
1845 | } | |
1846 | ||
fb084fde JT |
1847 | static bool check_reg_frame_pos(const struct cfi_reg *reg, |
1848 | int expected_offset) | |
1849 | { | |
1850 | return reg->base == CFI_CFA && | |
1851 | reg->offset == expected_offset; | |
1852 | } | |
1853 | ||
baa41469 JP |
1854 | static bool has_valid_stack_frame(struct insn_state *state) |
1855 | { | |
e7c0219b PZ |
1856 | struct cfi_state *cfi = &state->cfi; |
1857 | ||
fb084fde JT |
1858 | if (cfi->cfa.base == CFI_BP && |
1859 | check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) && | |
1860 | check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8)) | |
baa41469 JP |
1861 | return true; |
1862 | ||
e7c0219b | 1863 | if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP) |
baa41469 JP |
1864 | return true; |
1865 | ||
1866 | return false; | |
dcc914f4 JP |
1867 | } |
1868 | ||
e7c0219b PZ |
1869 | static int update_cfi_state_regs(struct instruction *insn, |
1870 | struct cfi_state *cfi, | |
65ea47dc | 1871 | struct stack_op *op) |
627fce14 | 1872 | { |
e7c0219b | 1873 | struct cfi_reg *cfa = &cfi->cfa; |
627fce14 | 1874 | |
d8dd25a4 | 1875 | if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT) |
627fce14 JP |
1876 | return 0; |
1877 | ||
1878 | /* push */ | |
ea24213d | 1879 | if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF) |
627fce14 JP |
1880 | cfa->offset += 8; |
1881 | ||
1882 | /* pop */ | |
ea24213d | 1883 | if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF) |
627fce14 JP |
1884 | cfa->offset -= 8; |
1885 | ||
1886 | /* add immediate to sp */ | |
1887 | if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD && | |
1888 | op->dest.reg == CFI_SP && op->src.reg == CFI_SP) | |
1889 | cfa->offset -= op->src.offset; | |
1890 | ||
1891 | return 0; | |
1892 | } | |
1893 | ||
e7c0219b | 1894 | static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset) |
dcc914f4 | 1895 | { |
bf4d1a83 | 1896 | if (arch_callee_saved_reg(reg) && |
e7c0219b PZ |
1897 | cfi->regs[reg].base == CFI_UNDEFINED) { |
1898 | cfi->regs[reg].base = base; | |
1899 | cfi->regs[reg].offset = offset; | |
baa41469 | 1900 | } |
dcc914f4 JP |
1901 | } |
1902 | ||
e7c0219b | 1903 | static void restore_reg(struct cfi_state *cfi, unsigned char reg) |
dcc914f4 | 1904 | { |
e7c0219b PZ |
1905 | cfi->regs[reg].base = initial_func_cfi.regs[reg].base; |
1906 | cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset; | |
baa41469 JP |
1907 | } |
1908 | ||
1909 | /* | |
1910 | * A note about DRAP stack alignment: | |
1911 | * | |
1912 | * GCC has the concept of a DRAP register, which is used to help keep track of | |
1913 | * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP | |
1914 | * register. The typical DRAP pattern is: | |
1915 | * | |
1916 | * 4c 8d 54 24 08 lea 0x8(%rsp),%r10 | |
1917 | * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp | |
1918 | * 41 ff 72 f8 pushq -0x8(%r10) | |
1919 | * 55 push %rbp | |
1920 | * 48 89 e5 mov %rsp,%rbp | |
1921 | * (more pushes) | |
1922 | * 41 52 push %r10 | |
1923 | * ... | |
1924 | * 41 5a pop %r10 | |
1925 | * (more pops) | |
1926 | * 5d pop %rbp | |
1927 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1928 | * c3 retq | |
1929 | * | |
1930 | * There are some variations in the epilogues, like: | |
1931 | * | |
1932 | * 5b pop %rbx | |
1933 | * 41 5a pop %r10 | |
1934 | * 41 5c pop %r12 | |
1935 | * 41 5d pop %r13 | |
1936 | * 41 5e pop %r14 | |
1937 | * c9 leaveq | |
1938 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1939 | * c3 retq | |
1940 | * | |
1941 | * and: | |
1942 | * | |
1943 | * 4c 8b 55 e8 mov -0x18(%rbp),%r10 | |
1944 | * 48 8b 5d e0 mov -0x20(%rbp),%rbx | |
1945 | * 4c 8b 65 f0 mov -0x10(%rbp),%r12 | |
1946 | * 4c 8b 6d f8 mov -0x8(%rbp),%r13 | |
1947 | * c9 leaveq | |
1948 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1949 | * c3 retq | |
1950 | * | |
1951 | * Sometimes r13 is used as the DRAP register, in which case it's saved and | |
1952 | * restored beforehand: | |
1953 | * | |
1954 | * 41 55 push %r13 | |
1955 | * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13 | |
1956 | * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp | |
1957 | * ... | |
1958 | * 49 8d 65 f0 lea -0x10(%r13),%rsp | |
1959 | * 41 5d pop %r13 | |
1960 | * c3 retq | |
1961 | */ | |
e7c0219b | 1962 | static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi, |
65ea47dc | 1963 | struct stack_op *op) |
baa41469 | 1964 | { |
e7c0219b PZ |
1965 | struct cfi_reg *cfa = &cfi->cfa; |
1966 | struct cfi_reg *regs = cfi->regs; | |
baa41469 JP |
1967 | |
1968 | /* stack operations don't make sense with an undefined CFA */ | |
1969 | if (cfa->base == CFI_UNDEFINED) { | |
1970 | if (insn->func) { | |
1971 | WARN_FUNC("undefined stack state", insn->sec, insn->offset); | |
1972 | return -1; | |
1973 | } | |
1974 | return 0; | |
1975 | } | |
1976 | ||
ee819aed JT |
1977 | if (cfi->type == UNWIND_HINT_TYPE_REGS || |
1978 | cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL) | |
e7c0219b | 1979 | return update_cfi_state_regs(insn, cfi, op); |
627fce14 | 1980 | |
baa41469 JP |
1981 | switch (op->dest.type) { |
1982 | ||
1983 | case OP_DEST_REG: | |
1984 | switch (op->src.type) { | |
1985 | ||
1986 | case OP_SRC_REG: | |
0d0970ee JP |
1987 | if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP && |
1988 | cfa->base == CFI_SP && | |
fb084fde | 1989 | check_reg_frame_pos(®s[CFI_BP], -cfa->offset)) { |
0d0970ee JP |
1990 | |
1991 | /* mov %rsp, %rbp */ | |
1992 | cfa->base = op->dest.reg; | |
e7c0219b | 1993 | cfi->bp_scratch = false; |
0d0970ee | 1994 | } |
dd88a0a0 | 1995 | |
0d0970ee | 1996 | else if (op->src.reg == CFI_SP && |
e7c0219b | 1997 | op->dest.reg == CFI_BP && cfi->drap) { |
dd88a0a0 | 1998 | |
0d0970ee JP |
1999 | /* drap: mov %rsp, %rbp */ |
2000 | regs[CFI_BP].base = CFI_BP; | |
e7c0219b PZ |
2001 | regs[CFI_BP].offset = -cfi->stack_size; |
2002 | cfi->bp_scratch = false; | |
0d0970ee | 2003 | } |
dd88a0a0 | 2004 | |
0d0970ee JP |
2005 | else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
2006 | ||
2007 | /* | |
2008 | * mov %rsp, %reg | |
2009 | * | |
2010 | * This is needed for the rare case where GCC | |
2011 | * does: | |
2012 | * | |
2013 | * mov %rsp, %rax | |
2014 | * ... | |
2015 | * mov %rax, %rsp | |
2016 | */ | |
e7c0219b PZ |
2017 | cfi->vals[op->dest.reg].base = CFI_CFA; |
2018 | cfi->vals[op->dest.reg].offset = -cfi->stack_size; | |
dd88a0a0 JP |
2019 | } |
2020 | ||
3c1f0583 JP |
2021 | else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP && |
2022 | cfa->base == CFI_BP) { | |
2023 | ||
2024 | /* | |
2025 | * mov %rbp, %rsp | |
2026 | * | |
2027 | * Restore the original stack pointer (Clang). | |
2028 | */ | |
e7c0219b | 2029 | cfi->stack_size = -cfi->regs[CFI_BP].offset; |
3c1f0583 JP |
2030 | } |
2031 | ||
dd88a0a0 JP |
2032 | else if (op->dest.reg == cfa->base) { |
2033 | ||
2034 | /* mov %reg, %rsp */ | |
2035 | if (cfa->base == CFI_SP && | |
e7c0219b | 2036 | cfi->vals[op->src.reg].base == CFI_CFA) { |
dd88a0a0 JP |
2037 | |
2038 | /* | |
2039 | * This is needed for the rare case | |
2040 | * where GCC does something dumb like: | |
2041 | * | |
2042 | * lea 0x8(%rsp), %rcx | |
2043 | * ... | |
2044 | * mov %rcx, %rsp | |
2045 | */ | |
e7c0219b PZ |
2046 | cfa->offset = -cfi->vals[op->src.reg].offset; |
2047 | cfi->stack_size = cfa->offset; | |
dd88a0a0 | 2048 | |
aafeb14e PZ |
2049 | } else if (cfa->base == CFI_SP && |
2050 | cfi->vals[op->src.reg].base == CFI_SP_INDIRECT && | |
2051 | cfi->vals[op->src.reg].offset == cfa->offset) { | |
2052 | ||
2053 | /* | |
2054 | * Stack swizzle: | |
2055 | * | |
2056 | * 1: mov %rsp, (%[tos]) | |
2057 | * 2: mov %[tos], %rsp | |
2058 | * ... | |
2059 | * 3: pop %rsp | |
2060 | * | |
2061 | * Where: | |
2062 | * | |
2063 | * 1 - places a pointer to the previous | |
2064 | * stack at the Top-of-Stack of the | |
2065 | * new stack. | |
2066 | * | |
2067 | * 2 - switches to the new stack. | |
2068 | * | |
2069 | * 3 - pops the Top-of-Stack to restore | |
2070 | * the original stack. | |
2071 | * | |
2072 | * Note: we set base to SP_INDIRECT | |
2073 | * here and preserve offset. Therefore | |
2074 | * when the unwinder reaches ToS it | |
2075 | * will dereference SP and then add the | |
2076 | * offset to find the next frame, IOW: | |
2077 | * (%rsp) + offset. | |
2078 | */ | |
2079 | cfa->base = CFI_SP_INDIRECT; | |
2080 | ||
dd88a0a0 JP |
2081 | } else { |
2082 | cfa->base = CFI_UNDEFINED; | |
2083 | cfa->offset = 0; | |
2084 | } | |
baa41469 JP |
2085 | } |
2086 | ||
724c8a23 PZ |
2087 | else if (op->dest.reg == CFI_SP && |
2088 | cfi->vals[op->src.reg].base == CFI_SP_INDIRECT && | |
2089 | cfi->vals[op->src.reg].offset == cfa->offset) { | |
2090 | ||
2091 | /* | |
2092 | * The same stack swizzle case 2) as above. But | |
2093 | * because we can't change cfa->base, case 3) | |
2094 | * will become a regular POP. Pretend we're a | |
2095 | * PUSH so things don't go unbalanced. | |
2096 | */ | |
2097 | cfi->stack_size += 8; | |
2098 | } | |
2099 | ||
2100 | ||
baa41469 JP |
2101 | break; |
2102 | ||
2103 | case OP_SRC_ADD: | |
2104 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) { | |
2105 | ||
2106 | /* add imm, %rsp */ | |
e7c0219b | 2107 | cfi->stack_size -= op->src.offset; |
baa41469 JP |
2108 | if (cfa->base == CFI_SP) |
2109 | cfa->offset -= op->src.offset; | |
2110 | break; | |
2111 | } | |
2112 | ||
2113 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) { | |
2114 | ||
2115 | /* lea disp(%rbp), %rsp */ | |
e7c0219b | 2116 | cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset); |
baa41469 JP |
2117 | break; |
2118 | } | |
2119 | ||
468af56a JT |
2120 | if (!cfi->drap && op->src.reg == CFI_SP && |
2121 | op->dest.reg == CFI_BP && cfa->base == CFI_SP && | |
2122 | check_reg_frame_pos(®s[CFI_BP], -cfa->offset + op->src.offset)) { | |
2123 | ||
2124 | /* lea disp(%rsp), %rbp */ | |
2125 | cfa->base = CFI_BP; | |
2126 | cfa->offset -= op->src.offset; | |
2127 | cfi->bp_scratch = false; | |
2128 | break; | |
2129 | } | |
2130 | ||
dd88a0a0 | 2131 | if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
baa41469 JP |
2132 | |
2133 | /* drap: lea disp(%rsp), %drap */ | |
e7c0219b | 2134 | cfi->drap_reg = op->dest.reg; |
dd88a0a0 JP |
2135 | |
2136 | /* | |
2137 | * lea disp(%rsp), %reg | |
2138 | * | |
2139 | * This is needed for the rare case where GCC | |
2140 | * does something dumb like: | |
2141 | * | |
2142 | * lea 0x8(%rsp), %rcx | |
2143 | * ... | |
2144 | * mov %rcx, %rsp | |
2145 | */ | |
e7c0219b PZ |
2146 | cfi->vals[op->dest.reg].base = CFI_CFA; |
2147 | cfi->vals[op->dest.reg].offset = \ | |
2148 | -cfi->stack_size + op->src.offset; | |
dd88a0a0 | 2149 | |
baa41469 JP |
2150 | break; |
2151 | } | |
2152 | ||
e7c0219b PZ |
2153 | if (cfi->drap && op->dest.reg == CFI_SP && |
2154 | op->src.reg == cfi->drap_reg) { | |
baa41469 JP |
2155 | |
2156 | /* drap: lea disp(%drap), %rsp */ | |
2157 | cfa->base = CFI_SP; | |
e7c0219b PZ |
2158 | cfa->offset = cfi->stack_size = -op->src.offset; |
2159 | cfi->drap_reg = CFI_UNDEFINED; | |
2160 | cfi->drap = false; | |
baa41469 JP |
2161 | break; |
2162 | } | |
2163 | ||
e7c0219b | 2164 | if (op->dest.reg == cfi->cfa.base) { |
baa41469 JP |
2165 | WARN_FUNC("unsupported stack register modification", |
2166 | insn->sec, insn->offset); | |
2167 | return -1; | |
2168 | } | |
2169 | ||
2170 | break; | |
2171 | ||
2172 | case OP_SRC_AND: | |
2173 | if (op->dest.reg != CFI_SP || | |
e7c0219b PZ |
2174 | (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) || |
2175 | (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) { | |
baa41469 JP |
2176 | WARN_FUNC("unsupported stack pointer realignment", |
2177 | insn->sec, insn->offset); | |
2178 | return -1; | |
2179 | } | |
2180 | ||
e7c0219b | 2181 | if (cfi->drap_reg != CFI_UNDEFINED) { |
baa41469 | 2182 | /* drap: and imm, %rsp */ |
e7c0219b PZ |
2183 | cfa->base = cfi->drap_reg; |
2184 | cfa->offset = cfi->stack_size = 0; | |
2185 | cfi->drap = true; | |
baa41469 JP |
2186 | } |
2187 | ||
2188 | /* | |
2189 | * Older versions of GCC (4.8ish) realign the stack | |
2190 | * without DRAP, with a frame pointer. | |
2191 | */ | |
2192 | ||
2193 | break; | |
2194 | ||
2195 | case OP_SRC_POP: | |
ea24213d | 2196 | case OP_SRC_POPF: |
aafeb14e PZ |
2197 | if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) { |
2198 | ||
2199 | /* pop %rsp; # restore from a stack swizzle */ | |
2200 | cfa->base = CFI_SP; | |
2201 | break; | |
2202 | } | |
2203 | ||
e7c0219b | 2204 | if (!cfi->drap && op->dest.reg == cfa->base) { |
baa41469 JP |
2205 | |
2206 | /* pop %rbp */ | |
2207 | cfa->base = CFI_SP; | |
2208 | } | |
2209 | ||
e7c0219b PZ |
2210 | if (cfi->drap && cfa->base == CFI_BP_INDIRECT && |
2211 | op->dest.reg == cfi->drap_reg && | |
2212 | cfi->drap_offset == -cfi->stack_size) { | |
baa41469 | 2213 | |
bf4d1a83 | 2214 | /* drap: pop %drap */ |
e7c0219b | 2215 | cfa->base = cfi->drap_reg; |
bf4d1a83 | 2216 | cfa->offset = 0; |
e7c0219b | 2217 | cfi->drap_offset = -1; |
baa41469 | 2218 | |
e7c0219b | 2219 | } else if (regs[op->dest.reg].offset == -cfi->stack_size) { |
baa41469 | 2220 | |
bf4d1a83 | 2221 | /* pop %reg */ |
e7c0219b | 2222 | restore_reg(cfi, op->dest.reg); |
baa41469 JP |
2223 | } |
2224 | ||
e7c0219b | 2225 | cfi->stack_size -= 8; |
baa41469 JP |
2226 | if (cfa->base == CFI_SP) |
2227 | cfa->offset -= 8; | |
2228 | ||
2229 | break; | |
2230 | ||
2231 | case OP_SRC_REG_INDIRECT: | |
201ef5a9 JT |
2232 | if (!cfi->drap && op->dest.reg == cfa->base && |
2233 | op->dest.reg == CFI_BP) { | |
2234 | ||
2235 | /* mov disp(%rsp), %rbp */ | |
2236 | cfa->base = CFI_SP; | |
2237 | cfa->offset = cfi->stack_size; | |
2238 | } | |
2239 | ||
e7c0219b PZ |
2240 | if (cfi->drap && op->src.reg == CFI_BP && |
2241 | op->src.offset == cfi->drap_offset) { | |
bf4d1a83 JP |
2242 | |
2243 | /* drap: mov disp(%rbp), %drap */ | |
e7c0219b | 2244 | cfa->base = cfi->drap_reg; |
bf4d1a83 | 2245 | cfa->offset = 0; |
e7c0219b | 2246 | cfi->drap_offset = -1; |
bf4d1a83 JP |
2247 | } |
2248 | ||
e7c0219b | 2249 | if (cfi->drap && op->src.reg == CFI_BP && |
baa41469 JP |
2250 | op->src.offset == regs[op->dest.reg].offset) { |
2251 | ||
2252 | /* drap: mov disp(%rbp), %reg */ | |
e7c0219b | 2253 | restore_reg(cfi, op->dest.reg); |
baa41469 JP |
2254 | |
2255 | } else if (op->src.reg == cfa->base && | |
2256 | op->src.offset == regs[op->dest.reg].offset + cfa->offset) { | |
2257 | ||
2258 | /* mov disp(%rbp), %reg */ | |
2259 | /* mov disp(%rsp), %reg */ | |
e7c0219b | 2260 | restore_reg(cfi, op->dest.reg); |
201ef5a9 JT |
2261 | |
2262 | } else if (op->src.reg == CFI_SP && | |
2263 | op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) { | |
2264 | ||
2265 | /* mov disp(%rsp), %reg */ | |
2266 | restore_reg(cfi, op->dest.reg); | |
baa41469 JP |
2267 | } |
2268 | ||
2269 | break; | |
2270 | ||
2271 | default: | |
2272 | WARN_FUNC("unknown stack-related instruction", | |
2273 | insn->sec, insn->offset); | |
2274 | return -1; | |
2275 | } | |
2276 | ||
2277 | break; | |
2278 | ||
2279 | case OP_DEST_PUSH: | |
ea24213d | 2280 | case OP_DEST_PUSHF: |
e7c0219b | 2281 | cfi->stack_size += 8; |
baa41469 JP |
2282 | if (cfa->base == CFI_SP) |
2283 | cfa->offset += 8; | |
2284 | ||
2285 | if (op->src.type != OP_SRC_REG) | |
2286 | break; | |
2287 | ||
e7c0219b PZ |
2288 | if (cfi->drap) { |
2289 | if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) { | |
baa41469 JP |
2290 | |
2291 | /* drap: push %drap */ | |
2292 | cfa->base = CFI_BP_INDIRECT; | |
e7c0219b | 2293 | cfa->offset = -cfi->stack_size; |
baa41469 | 2294 | |
bf4d1a83 | 2295 | /* save drap so we know when to restore it */ |
e7c0219b | 2296 | cfi->drap_offset = -cfi->stack_size; |
baa41469 | 2297 | |
e7c0219b | 2298 | } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) { |
baa41469 JP |
2299 | |
2300 | /* drap: push %rbp */ | |
e7c0219b | 2301 | cfi->stack_size = 0; |
baa41469 | 2302 | |
f4f80398 | 2303 | } else { |
baa41469 JP |
2304 | |
2305 | /* drap: push %reg */ | |
e7c0219b | 2306 | save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size); |
baa41469 JP |
2307 | } |
2308 | ||
2309 | } else { | |
2310 | ||
2311 | /* push %reg */ | |
e7c0219b | 2312 | save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size); |
baa41469 JP |
2313 | } |
2314 | ||
2315 | /* detect when asm code uses rbp as a scratch register */ | |
867ac9d7 | 2316 | if (!no_fp && insn->func && op->src.reg == CFI_BP && |
baa41469 | 2317 | cfa->base != CFI_BP) |
e7c0219b | 2318 | cfi->bp_scratch = true; |
baa41469 JP |
2319 | break; |
2320 | ||
2321 | case OP_DEST_REG_INDIRECT: | |
2322 | ||
e7c0219b PZ |
2323 | if (cfi->drap) { |
2324 | if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) { | |
baa41469 JP |
2325 | |
2326 | /* drap: mov %drap, disp(%rbp) */ | |
2327 | cfa->base = CFI_BP_INDIRECT; | |
2328 | cfa->offset = op->dest.offset; | |
2329 | ||
bf4d1a83 | 2330 | /* save drap offset so we know when to restore it */ |
e7c0219b | 2331 | cfi->drap_offset = op->dest.offset; |
f4f80398 | 2332 | } else { |
baa41469 JP |
2333 | |
2334 | /* drap: mov reg, disp(%rbp) */ | |
e7c0219b | 2335 | save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset); |
baa41469 JP |
2336 | } |
2337 | ||
2338 | } else if (op->dest.reg == cfa->base) { | |
2339 | ||
2340 | /* mov reg, disp(%rbp) */ | |
2341 | /* mov reg, disp(%rsp) */ | |
e7c0219b PZ |
2342 | save_reg(cfi, op->src.reg, CFI_CFA, |
2343 | op->dest.offset - cfi->cfa.offset); | |
201ef5a9 JT |
2344 | |
2345 | } else if (op->dest.reg == CFI_SP) { | |
2346 | ||
2347 | /* mov reg, disp(%rsp) */ | |
2348 | save_reg(cfi, op->src.reg, CFI_CFA, | |
2349 | op->dest.offset - cfi->stack_size); | |
aafeb14e PZ |
2350 | |
2351 | } else if (op->src.reg == CFI_SP && op->dest.offset == 0) { | |
2352 | ||
2353 | /* mov %rsp, (%reg); # setup a stack swizzle. */ | |
2354 | cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT; | |
2355 | cfi->vals[op->dest.reg].offset = cfa->offset; | |
baa41469 JP |
2356 | } |
2357 | ||
2358 | break; | |
2359 | ||
2360 | case OP_DEST_LEAVE: | |
e7c0219b PZ |
2361 | if ((!cfi->drap && cfa->base != CFI_BP) || |
2362 | (cfi->drap && cfa->base != cfi->drap_reg)) { | |
baa41469 JP |
2363 | WARN_FUNC("leave instruction with modified stack frame", |
2364 | insn->sec, insn->offset); | |
2365 | return -1; | |
2366 | } | |
2367 | ||
2368 | /* leave (mov %rbp, %rsp; pop %rbp) */ | |
2369 | ||
e7c0219b PZ |
2370 | cfi->stack_size = -cfi->regs[CFI_BP].offset - 8; |
2371 | restore_reg(cfi, CFI_BP); | |
baa41469 | 2372 | |
e7c0219b | 2373 | if (!cfi->drap) { |
baa41469 JP |
2374 | cfa->base = CFI_SP; |
2375 | cfa->offset -= 8; | |
2376 | } | |
2377 | ||
2378 | break; | |
2379 | ||
2380 | case OP_DEST_MEM: | |
ea24213d | 2381 | if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) { |
baa41469 JP |
2382 | WARN_FUNC("unknown stack-related memory operation", |
2383 | insn->sec, insn->offset); | |
2384 | return -1; | |
2385 | } | |
2386 | ||
2387 | /* pop mem */ | |
e7c0219b | 2388 | cfi->stack_size -= 8; |
baa41469 JP |
2389 | if (cfa->base == CFI_SP) |
2390 | cfa->offset -= 8; | |
2391 | ||
2392 | break; | |
2393 | ||
2394 | default: | |
2395 | WARN_FUNC("unknown stack-related instruction", | |
2396 | insn->sec, insn->offset); | |
2397 | return -1; | |
2398 | } | |
2399 | ||
2400 | return 0; | |
2401 | } | |
2402 | ||
c9c324dc JP |
2403 | /* |
2404 | * The stack layouts of alternatives instructions can sometimes diverge when | |
2405 | * they have stack modifications. That's fine as long as the potential stack | |
2406 | * layouts don't conflict at any given potential instruction boundary. | |
2407 | * | |
2408 | * Flatten the CFIs of the different alternative code streams (both original | |
2409 | * and replacement) into a single shared CFI array which can be used to detect | |
2410 | * conflicts and nicely feed a linear array of ORC entries to the unwinder. | |
2411 | */ | |
2412 | static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn) | |
65ea47dc | 2413 | { |
c9c324dc JP |
2414 | struct cfi_state **alt_cfi; |
2415 | int group_off; | |
65ea47dc | 2416 | |
c9c324dc JP |
2417 | if (!insn->alt_group) |
2418 | return 0; | |
65ea47dc | 2419 | |
c9c324dc JP |
2420 | alt_cfi = insn->alt_group->cfi; |
2421 | group_off = insn->offset - insn->alt_group->first_insn->offset; | |
65ea47dc | 2422 | |
c9c324dc JP |
2423 | if (!alt_cfi[group_off]) { |
2424 | alt_cfi[group_off] = &insn->cfi; | |
2425 | } else { | |
2426 | if (memcmp(alt_cfi[group_off], &insn->cfi, sizeof(struct cfi_state))) { | |
2427 | WARN_FUNC("stack layout conflict in alternatives", | |
2428 | insn->sec, insn->offset); | |
ab3852ab PZ |
2429 | return -1; |
2430 | } | |
c9c324dc JP |
2431 | } |
2432 | ||
2433 | return 0; | |
2434 | } | |
2435 | ||
2436 | static int handle_insn_ops(struct instruction *insn, struct insn_state *state) | |
2437 | { | |
2438 | struct stack_op *op; | |
2439 | ||
2440 | list_for_each_entry(op, &insn->stack_ops, list) { | |
2441 | ||
2442 | if (update_cfi_state(insn, &state->cfi, op)) | |
2443 | return 1; | |
ab3852ab | 2444 | |
65ea47dc JT |
2445 | if (op->dest.type == OP_DEST_PUSHF) { |
2446 | if (!state->uaccess_stack) { | |
2447 | state->uaccess_stack = 1; | |
2448 | } else if (state->uaccess_stack >> 31) { | |
2449 | WARN_FUNC("PUSHF stack exhausted", | |
2450 | insn->sec, insn->offset); | |
2451 | return 1; | |
2452 | } | |
2453 | state->uaccess_stack <<= 1; | |
2454 | state->uaccess_stack |= state->uaccess; | |
2455 | } | |
2456 | ||
2457 | if (op->src.type == OP_SRC_POPF) { | |
2458 | if (state->uaccess_stack) { | |
2459 | state->uaccess = state->uaccess_stack & 1; | |
2460 | state->uaccess_stack >>= 1; | |
2461 | if (state->uaccess_stack == 1) | |
2462 | state->uaccess_stack = 0; | |
2463 | } | |
2464 | } | |
2465 | } | |
2466 | ||
2467 | return 0; | |
2468 | } | |
2469 | ||
e7c0219b | 2470 | static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2) |
baa41469 | 2471 | { |
e7c0219b | 2472 | struct cfi_state *cfi1 = &insn->cfi; |
baa41469 JP |
2473 | int i; |
2474 | ||
e7c0219b PZ |
2475 | if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) { |
2476 | ||
baa41469 JP |
2477 | WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d", |
2478 | insn->sec, insn->offset, | |
e7c0219b PZ |
2479 | cfi1->cfa.base, cfi1->cfa.offset, |
2480 | cfi2->cfa.base, cfi2->cfa.offset); | |
baa41469 | 2481 | |
e7c0219b | 2482 | } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) { |
baa41469 | 2483 | for (i = 0; i < CFI_NUM_REGS; i++) { |
e7c0219b | 2484 | if (!memcmp(&cfi1->regs[i], &cfi2->regs[i], |
baa41469 JP |
2485 | sizeof(struct cfi_reg))) |
2486 | continue; | |
2487 | ||
2488 | WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d", | |
2489 | insn->sec, insn->offset, | |
e7c0219b PZ |
2490 | i, cfi1->regs[i].base, cfi1->regs[i].offset, |
2491 | i, cfi2->regs[i].base, cfi2->regs[i].offset); | |
baa41469 JP |
2492 | break; |
2493 | } | |
2494 | ||
e7c0219b PZ |
2495 | } else if (cfi1->type != cfi2->type) { |
2496 | ||
627fce14 | 2497 | WARN_FUNC("stack state mismatch: type1=%d type2=%d", |
e7c0219b PZ |
2498 | insn->sec, insn->offset, cfi1->type, cfi2->type); |
2499 | ||
2500 | } else if (cfi1->drap != cfi2->drap || | |
2501 | (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) || | |
2502 | (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) { | |
627fce14 | 2503 | |
bf4d1a83 | 2504 | WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)", |
baa41469 | 2505 | insn->sec, insn->offset, |
e7c0219b PZ |
2506 | cfi1->drap, cfi1->drap_reg, cfi1->drap_offset, |
2507 | cfi2->drap, cfi2->drap_reg, cfi2->drap_offset); | |
baa41469 JP |
2508 | |
2509 | } else | |
2510 | return true; | |
2511 | ||
2512 | return false; | |
dcc914f4 JP |
2513 | } |
2514 | ||
ea24213d PZ |
2515 | static inline bool func_uaccess_safe(struct symbol *func) |
2516 | { | |
2517 | if (func) | |
e10cd8fe | 2518 | return func->uaccess_safe; |
ea24213d PZ |
2519 | |
2520 | return false; | |
2521 | } | |
2522 | ||
0c1ddd33 | 2523 | static inline const char *call_dest_name(struct instruction *insn) |
ea24213d PZ |
2524 | { |
2525 | if (insn->call_dest) | |
2526 | return insn->call_dest->name; | |
2527 | ||
2528 | return "{dynamic}"; | |
2529 | } | |
2530 | ||
6b643a07 PZ |
2531 | static inline bool noinstr_call_dest(struct symbol *func) |
2532 | { | |
2533 | /* | |
2534 | * We can't deal with indirect function calls at present; | |
2535 | * assume they're instrumented. | |
2536 | */ | |
2537 | if (!func) | |
2538 | return false; | |
2539 | ||
2540 | /* | |
2541 | * If the symbol is from a noinstr section; we good. | |
2542 | */ | |
2543 | if (func->sec->noinstr) | |
2544 | return true; | |
2545 | ||
2546 | /* | |
2547 | * The __ubsan_handle_*() calls are like WARN(), they only happen when | |
2548 | * something 'BAD' happened. At the risk of taking the machine down, | |
2549 | * let them proceed to get the message out. | |
2550 | */ | |
2551 | if (!strncmp(func->name, "__ubsan_handle_", 15)) | |
2552 | return true; | |
2553 | ||
2554 | return false; | |
2555 | } | |
2556 | ||
ea24213d PZ |
2557 | static int validate_call(struct instruction *insn, struct insn_state *state) |
2558 | { | |
c4a33939 | 2559 | if (state->noinstr && state->instr <= 0 && |
6b643a07 | 2560 | !noinstr_call_dest(insn->call_dest)) { |
c4a33939 PZ |
2561 | WARN_FUNC("call to %s() leaves .noinstr.text section", |
2562 | insn->sec, insn->offset, call_dest_name(insn)); | |
2563 | return 1; | |
2564 | } | |
2565 | ||
ea24213d PZ |
2566 | if (state->uaccess && !func_uaccess_safe(insn->call_dest)) { |
2567 | WARN_FUNC("call to %s() with UACCESS enabled", | |
0c1ddd33 | 2568 | insn->sec, insn->offset, call_dest_name(insn)); |
ea24213d PZ |
2569 | return 1; |
2570 | } | |
2571 | ||
2f0f9e9a PZ |
2572 | if (state->df) { |
2573 | WARN_FUNC("call to %s() with DF set", | |
0c1ddd33 | 2574 | insn->sec, insn->offset, call_dest_name(insn)); |
2f0f9e9a PZ |
2575 | return 1; |
2576 | } | |
2577 | ||
ea24213d PZ |
2578 | return 0; |
2579 | } | |
2580 | ||
54262aa2 PZ |
2581 | static int validate_sibling_call(struct instruction *insn, struct insn_state *state) |
2582 | { | |
e25eea89 | 2583 | if (has_modified_stack_frame(insn, state)) { |
54262aa2 PZ |
2584 | WARN_FUNC("sibling call from callable instruction with modified stack frame", |
2585 | insn->sec, insn->offset); | |
2586 | return 1; | |
2587 | } | |
2588 | ||
ea24213d | 2589 | return validate_call(insn, state); |
54262aa2 PZ |
2590 | } |
2591 | ||
a92e92d1 PZ |
2592 | static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state) |
2593 | { | |
c4a33939 PZ |
2594 | if (state->noinstr && state->instr > 0) { |
2595 | WARN_FUNC("return with instrumentation enabled", | |
2596 | insn->sec, insn->offset); | |
2597 | return 1; | |
2598 | } | |
2599 | ||
a92e92d1 PZ |
2600 | if (state->uaccess && !func_uaccess_safe(func)) { |
2601 | WARN_FUNC("return with UACCESS enabled", | |
2602 | insn->sec, insn->offset); | |
2603 | return 1; | |
2604 | } | |
2605 | ||
2606 | if (!state->uaccess && func_uaccess_safe(func)) { | |
2607 | WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function", | |
2608 | insn->sec, insn->offset); | |
2609 | return 1; | |
2610 | } | |
2611 | ||
2612 | if (state->df) { | |
2613 | WARN_FUNC("return with DF set", | |
2614 | insn->sec, insn->offset); | |
2615 | return 1; | |
2616 | } | |
2617 | ||
e25eea89 | 2618 | if (func && has_modified_stack_frame(insn, state)) { |
a92e92d1 PZ |
2619 | WARN_FUNC("return with modified stack frame", |
2620 | insn->sec, insn->offset); | |
2621 | return 1; | |
2622 | } | |
2623 | ||
e7c0219b | 2624 | if (state->cfi.bp_scratch) { |
b2966952 JP |
2625 | WARN_FUNC("BP used as a scratch register", |
2626 | insn->sec, insn->offset); | |
a92e92d1 PZ |
2627 | return 1; |
2628 | } | |
2629 | ||
2630 | return 0; | |
2631 | } | |
2632 | ||
c9c324dc JP |
2633 | static struct instruction *next_insn_to_validate(struct objtool_file *file, |
2634 | struct instruction *insn) | |
7117f16b | 2635 | { |
b23cc71c | 2636 | struct alt_group *alt_group = insn->alt_group; |
7117f16b | 2637 | |
c9c324dc JP |
2638 | /* |
2639 | * Simulate the fact that alternatives are patched in-place. When the | |
2640 | * end of a replacement alt_group is reached, redirect objtool flow to | |
2641 | * the end of the original alt_group. | |
2642 | */ | |
2643 | if (alt_group && insn == alt_group->last_insn && alt_group->orig_group) | |
2644 | return next_insn_same_sec(file, alt_group->orig_group->last_insn); | |
2645 | ||
2646 | return next_insn_same_sec(file, insn); | |
7117f16b PZ |
2647 | } |
2648 | ||
dcc914f4 JP |
2649 | /* |
2650 | * Follow the branch starting at the given instruction, and recursively follow | |
2651 | * any other branches (jumps). Meanwhile, track the frame pointer state at | |
2652 | * each instruction and validate all the rules described in | |
2653 | * tools/objtool/Documentation/stack-validation.txt. | |
2654 | */ | |
c705cecc | 2655 | static int validate_branch(struct objtool_file *file, struct symbol *func, |
b7460462 | 2656 | struct instruction *insn, struct insn_state state) |
dcc914f4 JP |
2657 | { |
2658 | struct alternative *alt; | |
b7460462 | 2659 | struct instruction *next_insn; |
dcc914f4 | 2660 | struct section *sec; |
882a0db9 | 2661 | u8 visited; |
dcc914f4 JP |
2662 | int ret; |
2663 | ||
dcc914f4 | 2664 | sec = insn->sec; |
dcc914f4 | 2665 | |
dcc914f4 | 2666 | while (1) { |
c9c324dc | 2667 | next_insn = next_insn_to_validate(file, insn); |
39358a03 | 2668 | |
13810435 | 2669 | if (file->c_file && func && insn->func && func != insn->func->pfunc) { |
ee97638b JP |
2670 | WARN("%s() falls through to next function %s()", |
2671 | func->name, insn->func->name); | |
2672 | return 1; | |
dcc914f4 JP |
2673 | } |
2674 | ||
4855022a JP |
2675 | if (func && insn->ignore) { |
2676 | WARN_FUNC("BUG: why am I validating an ignored function?", | |
2677 | sec, insn->offset); | |
12b25729 | 2678 | return 1; |
4855022a JP |
2679 | } |
2680 | ||
882a0db9 | 2681 | visited = 1 << state.uaccess; |
dcc914f4 | 2682 | if (insn->visited) { |
e7c0219b | 2683 | if (!insn->hint && !insn_cfi_match(insn, &state.cfi)) |
dcc914f4 | 2684 | return 1; |
dcc914f4 | 2685 | |
882a0db9 | 2686 | if (insn->visited & visited) |
ea24213d | 2687 | return 0; |
dcc914f4 JP |
2688 | } |
2689 | ||
c4a33939 PZ |
2690 | if (state.noinstr) |
2691 | state.instr += insn->instr; | |
2692 | ||
c536ed2f | 2693 | if (insn->hint) |
e7c0219b | 2694 | state.cfi = insn->cfi; |
c536ed2f | 2695 | else |
e7c0219b | 2696 | insn->cfi = state.cfi; |
dcc914f4 | 2697 | |
882a0db9 | 2698 | insn->visited |= visited; |
baa41469 | 2699 | |
c9c324dc JP |
2700 | if (propagate_alt_cfi(file, insn)) |
2701 | return 1; | |
2702 | ||
7117f16b | 2703 | if (!insn->ignore_alts && !list_empty(&insn->alts)) { |
764eef4b PZ |
2704 | bool skip_orig = false; |
2705 | ||
a845c7cf | 2706 | list_for_each_entry(alt, &insn->alts, list) { |
764eef4b PZ |
2707 | if (alt->skip_orig) |
2708 | skip_orig = true; | |
2709 | ||
c705cecc | 2710 | ret = validate_branch(file, func, alt->insn, state); |
7697eee3 PZ |
2711 | if (ret) { |
2712 | if (backtrace) | |
2713 | BT_FUNC("(alt)", insn); | |
2714 | return ret; | |
2715 | } | |
a845c7cf | 2716 | } |
764eef4b PZ |
2717 | |
2718 | if (skip_orig) | |
2719 | return 0; | |
dcc914f4 JP |
2720 | } |
2721 | ||
60041bcd PZ |
2722 | if (handle_insn_ops(insn, &state)) |
2723 | return 1; | |
2724 | ||
dcc914f4 JP |
2725 | switch (insn->type) { |
2726 | ||
dcc914f4 | 2727 | case INSN_RETURN: |
a92e92d1 | 2728 | return validate_return(func, insn, &state); |
dcc914f4 JP |
2729 | |
2730 | case INSN_CALL: | |
ea24213d PZ |
2731 | case INSN_CALL_DYNAMIC: |
2732 | ret = validate_call(insn, &state); | |
2733 | if (ret) | |
2734 | return ret; | |
dcc914f4 | 2735 | |
c9bab22b JP |
2736 | if (!no_fp && func && !is_fentry_call(insn) && |
2737 | !has_valid_stack_frame(&state)) { | |
dcc914f4 JP |
2738 | WARN_FUNC("call without frame pointer save/setup", |
2739 | sec, insn->offset); | |
2740 | return 1; | |
2741 | } | |
c9bab22b JP |
2742 | |
2743 | if (dead_end_function(file, insn->call_dest)) | |
2744 | return 0; | |
2745 | ||
1e7e4788 JP |
2746 | if (insn->type == INSN_CALL && insn->call_dest->static_call_tramp) { |
2747 | list_add_tail(&insn->static_call_node, | |
2748 | &file->static_call_list); | |
2749 | } | |
2750 | ||
dcc914f4 JP |
2751 | break; |
2752 | ||
2753 | case INSN_JUMP_CONDITIONAL: | |
2754 | case INSN_JUMP_UNCONDITIONAL: | |
ecf11ba4 | 2755 | if (is_sibling_call(insn)) { |
54262aa2 | 2756 | ret = validate_sibling_call(insn, &state); |
dcc914f4 | 2757 | if (ret) |
54262aa2 | 2758 | return ret; |
4855022a | 2759 | |
0c1ddd33 | 2760 | } else if (insn->jump_dest) { |
c705cecc JP |
2761 | ret = validate_branch(file, func, |
2762 | insn->jump_dest, state); | |
7697eee3 PZ |
2763 | if (ret) { |
2764 | if (backtrace) | |
2765 | BT_FUNC("(branch)", insn); | |
2766 | return ret; | |
2767 | } | |
4855022a | 2768 | } |
dcc914f4 JP |
2769 | |
2770 | if (insn->type == INSN_JUMP_UNCONDITIONAL) | |
2771 | return 0; | |
2772 | ||
2773 | break; | |
2774 | ||
2775 | case INSN_JUMP_DYNAMIC: | |
b68b9907 | 2776 | case INSN_JUMP_DYNAMIC_CONDITIONAL: |
ecf11ba4 | 2777 | if (is_sibling_call(insn)) { |
54262aa2 PZ |
2778 | ret = validate_sibling_call(insn, &state); |
2779 | if (ret) | |
2780 | return ret; | |
dcc914f4 JP |
2781 | } |
2782 | ||
b68b9907 JP |
2783 | if (insn->type == INSN_JUMP_DYNAMIC) |
2784 | return 0; | |
2785 | ||
2786 | break; | |
dcc914f4 | 2787 | |
39358a03 JP |
2788 | case INSN_CONTEXT_SWITCH: |
2789 | if (func && (!next_insn || !next_insn->hint)) { | |
2790 | WARN_FUNC("unsupported instruction in callable function", | |
2791 | sec, insn->offset); | |
2792 | return 1; | |
2793 | } | |
2794 | return 0; | |
2795 | ||
ea24213d PZ |
2796 | case INSN_STAC: |
2797 | if (state.uaccess) { | |
2798 | WARN_FUNC("recursive UACCESS enable", sec, insn->offset); | |
2799 | return 1; | |
2800 | } | |
2801 | ||
2802 | state.uaccess = true; | |
2803 | break; | |
2804 | ||
2805 | case INSN_CLAC: | |
c705cecc | 2806 | if (!state.uaccess && func) { |
ea24213d PZ |
2807 | WARN_FUNC("redundant UACCESS disable", sec, insn->offset); |
2808 | return 1; | |
2809 | } | |
2810 | ||
2811 | if (func_uaccess_safe(func) && !state.uaccess_stack) { | |
2812 | WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset); | |
2813 | return 1; | |
2814 | } | |
2815 | ||
2816 | state.uaccess = false; | |
baa41469 JP |
2817 | break; |
2818 | ||
2f0f9e9a | 2819 | case INSN_STD: |
6f567c93 | 2820 | if (state.df) { |
2f0f9e9a | 2821 | WARN_FUNC("recursive STD", sec, insn->offset); |
6f567c93 JP |
2822 | return 1; |
2823 | } | |
2f0f9e9a PZ |
2824 | |
2825 | state.df = true; | |
2826 | break; | |
2827 | ||
2828 | case INSN_CLD: | |
6f567c93 | 2829 | if (!state.df && func) { |
2f0f9e9a | 2830 | WARN_FUNC("redundant CLD", sec, insn->offset); |
6f567c93 JP |
2831 | return 1; |
2832 | } | |
2f0f9e9a PZ |
2833 | |
2834 | state.df = false; | |
baa41469 JP |
2835 | break; |
2836 | ||
dcc914f4 JP |
2837 | default: |
2838 | break; | |
2839 | } | |
2840 | ||
2841 | if (insn->dead_end) | |
2842 | return 0; | |
2843 | ||
00d96180 | 2844 | if (!next_insn) { |
e7c0219b | 2845 | if (state.cfi.cfa.base == CFI_UNDEFINED) |
00d96180 | 2846 | return 0; |
dcc914f4 JP |
2847 | WARN("%s: unexpected end of section", sec->name); |
2848 | return 1; | |
2849 | } | |
00d96180 JP |
2850 | |
2851 | insn = next_insn; | |
dcc914f4 JP |
2852 | } |
2853 | ||
2854 | return 0; | |
2855 | } | |
2856 | ||
932f8e98 | 2857 | static int validate_unwind_hints(struct objtool_file *file, struct section *sec) |
39358a03 JP |
2858 | { |
2859 | struct instruction *insn; | |
39358a03 | 2860 | struct insn_state state; |
932f8e98 | 2861 | int ret, warnings = 0; |
39358a03 JP |
2862 | |
2863 | if (!file->hints) | |
2864 | return 0; | |
2865 | ||
932f8e98 | 2866 | init_insn_state(&state, sec); |
39358a03 | 2867 | |
932f8e98 PZ |
2868 | if (sec) { |
2869 | insn = find_insn(file, sec, 0); | |
2870 | if (!insn) | |
2871 | return 0; | |
2872 | } else { | |
2873 | insn = list_first_entry(&file->insn_list, typeof(*insn), list); | |
2874 | } | |
2875 | ||
2876 | while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) { | |
39358a03 | 2877 | if (insn->hint && !insn->visited) { |
c705cecc | 2878 | ret = validate_branch(file, insn->func, insn, state); |
7697eee3 PZ |
2879 | if (ret && backtrace) |
2880 | BT_FUNC("<=== (hint)", insn); | |
39358a03 JP |
2881 | warnings += ret; |
2882 | } | |
932f8e98 PZ |
2883 | |
2884 | insn = list_next_entry(insn, list); | |
39358a03 JP |
2885 | } |
2886 | ||
2887 | return warnings; | |
2888 | } | |
2889 | ||
b5bc2231 PZ |
2890 | static int validate_retpoline(struct objtool_file *file) |
2891 | { | |
2892 | struct instruction *insn; | |
2893 | int warnings = 0; | |
2894 | ||
2895 | for_each_insn(file, insn) { | |
2896 | if (insn->type != INSN_JUMP_DYNAMIC && | |
2897 | insn->type != INSN_CALL_DYNAMIC) | |
2898 | continue; | |
2899 | ||
2900 | if (insn->retpoline_safe) | |
2901 | continue; | |
2902 | ||
ca41b97e PZ |
2903 | /* |
2904 | * .init.text code is ran before userspace and thus doesn't | |
2905 | * strictly need retpolines, except for modules which are | |
2906 | * loaded late, they very much do need retpoline in their | |
2907 | * .init.text | |
2908 | */ | |
2909 | if (!strcmp(insn->sec->name, ".init.text") && !module) | |
2910 | continue; | |
2911 | ||
b5bc2231 PZ |
2912 | WARN_FUNC("indirect %s found in RETPOLINE build", |
2913 | insn->sec, insn->offset, | |
2914 | insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); | |
2915 | ||
2916 | warnings++; | |
2917 | } | |
2918 | ||
2919 | return warnings; | |
2920 | } | |
2921 | ||
dcc914f4 JP |
2922 | static bool is_kasan_insn(struct instruction *insn) |
2923 | { | |
2924 | return (insn->type == INSN_CALL && | |
2925 | !strcmp(insn->call_dest->name, "__asan_handle_no_return")); | |
2926 | } | |
2927 | ||
2928 | static bool is_ubsan_insn(struct instruction *insn) | |
2929 | { | |
2930 | return (insn->type == INSN_CALL && | |
2931 | !strcmp(insn->call_dest->name, | |
2932 | "__ubsan_handle_builtin_unreachable")); | |
2933 | } | |
2934 | ||
14db1f0a | 2935 | static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn) |
dcc914f4 JP |
2936 | { |
2937 | int i; | |
14db1f0a | 2938 | struct instruction *prev_insn; |
dcc914f4 | 2939 | |
baa41469 JP |
2940 | if (insn->ignore || insn->type == INSN_NOP) |
2941 | return true; | |
2942 | ||
2943 | /* | |
2944 | * Ignore any unused exceptions. This can happen when a whitelisted | |
2945 | * function has an exception table entry. | |
0e2bb2bc JP |
2946 | * |
2947 | * Also ignore alternative replacement instructions. This can happen | |
2948 | * when a whitelisted function uses one of the ALTERNATIVE macros. | |
baa41469 | 2949 | */ |
0e2bb2bc JP |
2950 | if (!strcmp(insn->sec->name, ".fixup") || |
2951 | !strcmp(insn->sec->name, ".altinstr_replacement") || | |
2952 | !strcmp(insn->sec->name, ".altinstr_aux")) | |
dcc914f4 JP |
2953 | return true; |
2954 | ||
bd841d61 JP |
2955 | if (!insn->func) |
2956 | return false; | |
2957 | ||
2958 | /* | |
2959 | * CONFIG_UBSAN_TRAP inserts a UD2 when it sees | |
2960 | * __builtin_unreachable(). The BUG() macro has an unreachable() after | |
2961 | * the UD2, which causes GCC's undefined trap logic to emit another UD2 | |
2962 | * (or occasionally a JMP to UD2). | |
14db1f0a IH |
2963 | * |
2964 | * It may also insert a UD2 after calling a __noreturn function. | |
bd841d61 | 2965 | */ |
14db1f0a IH |
2966 | prev_insn = list_prev_entry(insn, list); |
2967 | if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) && | |
bd841d61 JP |
2968 | (insn->type == INSN_BUG || |
2969 | (insn->type == INSN_JUMP_UNCONDITIONAL && | |
2970 | insn->jump_dest && insn->jump_dest->type == INSN_BUG))) | |
2971 | return true; | |
2972 | ||
dcc914f4 JP |
2973 | /* |
2974 | * Check if this (or a subsequent) instruction is related to | |
2975 | * CONFIG_UBSAN or CONFIG_KASAN. | |
2976 | * | |
2977 | * End the search at 5 instructions to avoid going into the weeds. | |
2978 | */ | |
2979 | for (i = 0; i < 5; i++) { | |
2980 | ||
2981 | if (is_kasan_insn(insn) || is_ubsan_insn(insn)) | |
2982 | return true; | |
2983 | ||
fe24e271 JP |
2984 | if (insn->type == INSN_JUMP_UNCONDITIONAL) { |
2985 | if (insn->jump_dest && | |
2986 | insn->jump_dest->func == insn->func) { | |
2987 | insn = insn->jump_dest; | |
2988 | continue; | |
2989 | } | |
2990 | ||
2991 | break; | |
dcc914f4 JP |
2992 | } |
2993 | ||
baa41469 | 2994 | if (insn->offset + insn->len >= insn->func->offset + insn->func->len) |
dcc914f4 | 2995 | break; |
fe24e271 | 2996 | |
dcc914f4 JP |
2997 | insn = list_next_entry(insn, list); |
2998 | } | |
2999 | ||
3000 | return false; | |
3001 | } | |
3002 | ||
4b5e2e7f PZ |
3003 | static int validate_symbol(struct objtool_file *file, struct section *sec, |
3004 | struct symbol *sym, struct insn_state *state) | |
dcc914f4 | 3005 | { |
dcc914f4 | 3006 | struct instruction *insn; |
4b5e2e7f PZ |
3007 | int ret; |
3008 | ||
3009 | if (!sym->len) { | |
3010 | WARN("%s() is missing an ELF size annotation", sym->name); | |
3011 | return 1; | |
3012 | } | |
3013 | ||
3014 | if (sym->pfunc != sym || sym->alias != sym) | |
3015 | return 0; | |
3016 | ||
3017 | insn = find_insn(file, sec, sym->offset); | |
3018 | if (!insn || insn->ignore || insn->visited) | |
3019 | return 0; | |
3020 | ||
3021 | state->uaccess = sym->uaccess_safe; | |
3022 | ||
3023 | ret = validate_branch(file, insn->func, insn, *state); | |
3024 | if (ret && backtrace) | |
3025 | BT_FUNC("<=== (sym)", insn); | |
3026 | return ret; | |
3027 | } | |
3028 | ||
3029 | static int validate_section(struct objtool_file *file, struct section *sec) | |
3030 | { | |
baa41469 | 3031 | struct insn_state state; |
4b5e2e7f PZ |
3032 | struct symbol *func; |
3033 | int warnings = 0; | |
dcc914f4 | 3034 | |
350994bf PZ |
3035 | list_for_each_entry(func, &sec->symbol_list, list) { |
3036 | if (func->type != STT_FUNC) | |
3037 | continue; | |
e10cd8fe | 3038 | |
932f8e98 | 3039 | init_insn_state(&state, sec); |
b735bd3e | 3040 | set_func_state(&state.cfi); |
0699e551 | 3041 | |
4b5e2e7f | 3042 | warnings += validate_symbol(file, sec, func, &state); |
dcc914f4 JP |
3043 | } |
3044 | ||
dcc914f4 JP |
3045 | return warnings; |
3046 | } | |
3047 | ||
c4a33939 PZ |
3048 | static int validate_vmlinux_functions(struct objtool_file *file) |
3049 | { | |
3050 | struct section *sec; | |
932f8e98 | 3051 | int warnings = 0; |
c4a33939 PZ |
3052 | |
3053 | sec = find_section_by_name(file->elf, ".noinstr.text"); | |
0cc9ac8d TG |
3054 | if (sec) { |
3055 | warnings += validate_section(file, sec); | |
3056 | warnings += validate_unwind_hints(file, sec); | |
3057 | } | |
c4a33939 | 3058 | |
0cc9ac8d TG |
3059 | sec = find_section_by_name(file->elf, ".entry.text"); |
3060 | if (sec) { | |
3061 | warnings += validate_section(file, sec); | |
3062 | warnings += validate_unwind_hints(file, sec); | |
3063 | } | |
932f8e98 PZ |
3064 | |
3065 | return warnings; | |
c4a33939 PZ |
3066 | } |
3067 | ||
350994bf PZ |
3068 | static int validate_functions(struct objtool_file *file) |
3069 | { | |
3070 | struct section *sec; | |
3071 | int warnings = 0; | |
3072 | ||
da837bd6 PZ |
3073 | for_each_sec(file, sec) { |
3074 | if (!(sec->sh.sh_flags & SHF_EXECINSTR)) | |
3075 | continue; | |
3076 | ||
350994bf | 3077 | warnings += validate_section(file, sec); |
da837bd6 | 3078 | } |
350994bf PZ |
3079 | |
3080 | return warnings; | |
3081 | } | |
3082 | ||
baa41469 | 3083 | static int validate_reachable_instructions(struct objtool_file *file) |
dcc914f4 JP |
3084 | { |
3085 | struct instruction *insn; | |
baa41469 JP |
3086 | |
3087 | if (file->ignore_unreachables) | |
3088 | return 0; | |
dcc914f4 JP |
3089 | |
3090 | for_each_insn(file, insn) { | |
14db1f0a | 3091 | if (insn->visited || ignore_unreachable_insn(file, insn)) |
baa41469 JP |
3092 | continue; |
3093 | ||
baa41469 JP |
3094 | WARN_FUNC("unreachable instruction", insn->sec, insn->offset); |
3095 | return 1; | |
dcc914f4 JP |
3096 | } |
3097 | ||
baa41469 | 3098 | return 0; |
dcc914f4 JP |
3099 | } |
3100 | ||
d44becb9 | 3101 | int check(struct objtool_file *file) |
dcc914f4 | 3102 | { |
dcc914f4 JP |
3103 | int ret, warnings = 0; |
3104 | ||
baa41469 JP |
3105 | arch_initial_func_cfi_state(&initial_func_cfi); |
3106 | ||
6545eb03 | 3107 | ret = decode_sections(file); |
dcc914f4 JP |
3108 | if (ret < 0) |
3109 | goto out; | |
3110 | warnings += ret; | |
3111 | ||
6545eb03 | 3112 | if (list_empty(&file->insn_list)) |
dcc914f4 | 3113 | goto out; |
dcc914f4 | 3114 | |
c4a33939 | 3115 | if (vmlinux && !validate_dup) { |
6545eb03 | 3116 | ret = validate_vmlinux_functions(file); |
c4a33939 PZ |
3117 | if (ret < 0) |
3118 | goto out; | |
3119 | ||
3120 | warnings += ret; | |
3121 | goto out; | |
3122 | } | |
3123 | ||
b5bc2231 | 3124 | if (retpoline) { |
6545eb03 | 3125 | ret = validate_retpoline(file); |
b5bc2231 PZ |
3126 | if (ret < 0) |
3127 | return ret; | |
3128 | warnings += ret; | |
3129 | } | |
3130 | ||
6545eb03 | 3131 | ret = validate_functions(file); |
dcc914f4 JP |
3132 | if (ret < 0) |
3133 | goto out; | |
3134 | warnings += ret; | |
3135 | ||
6545eb03 | 3136 | ret = validate_unwind_hints(file, NULL); |
39358a03 JP |
3137 | if (ret < 0) |
3138 | goto out; | |
3139 | warnings += ret; | |
3140 | ||
baa41469 | 3141 | if (!warnings) { |
6545eb03 | 3142 | ret = validate_reachable_instructions(file); |
baa41469 JP |
3143 | if (ret < 0) |
3144 | goto out; | |
3145 | warnings += ret; | |
3146 | } | |
3147 | ||
6545eb03 | 3148 | ret = create_static_call_sections(file); |
1e7e4788 JP |
3149 | if (ret < 0) |
3150 | goto out; | |
3151 | warnings += ret; | |
3152 | ||
99d00215 PZ |
3153 | if (mcount) { |
3154 | ret = create_mcount_loc_sections(file); | |
3155 | if (ret < 0) | |
3156 | goto out; | |
3157 | warnings += ret; | |
3158 | } | |
3159 | ||
dcc914f4 | 3160 | out: |
655cf865 JP |
3161 | /* |
3162 | * For now, don't fail the kernel build on fatal warnings. These | |
3163 | * errors are still fairly common due to the growing matrix of | |
3164 | * supported toolchains and their recent pace of change. | |
3165 | */ | |
dcc914f4 JP |
3166 | return 0; |
3167 | } |