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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 | { | |
ef47cc01 | 436 | struct section *sec; |
1e7e4788 JP |
437 | struct static_call_site *site; |
438 | struct instruction *insn; | |
439 | struct symbol *key_sym; | |
440 | char *key_name, *tmp; | |
441 | int idx; | |
442 | ||
443 | sec = find_section_by_name(file->elf, ".static_call_sites"); | |
444 | if (sec) { | |
445 | INIT_LIST_HEAD(&file->static_call_list); | |
446 | WARN("file already has .static_call_sites section, skipping"); | |
447 | return 0; | |
448 | } | |
449 | ||
450 | if (list_empty(&file->static_call_list)) | |
451 | return 0; | |
452 | ||
453 | idx = 0; | |
454 | list_for_each_entry(insn, &file->static_call_list, static_call_node) | |
455 | idx++; | |
456 | ||
457 | sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE, | |
458 | sizeof(struct static_call_site), idx); | |
459 | if (!sec) | |
460 | return -1; | |
461 | ||
1e7e4788 JP |
462 | idx = 0; |
463 | list_for_each_entry(insn, &file->static_call_list, static_call_node) { | |
464 | ||
465 | site = (struct static_call_site *)sec->data->d_buf + idx; | |
466 | memset(site, 0, sizeof(struct static_call_site)); | |
467 | ||
468 | /* populate reloc for 'addr' */ | |
ef47cc01 PZ |
469 | if (elf_add_reloc_to_insn(file->elf, sec, |
470 | idx * sizeof(struct static_call_site), | |
471 | R_X86_64_PC32, | |
472 | insn->sec, insn->offset)) | |
44f6a7c0 | 473 | return -1; |
1e7e4788 JP |
474 | |
475 | /* find key symbol */ | |
476 | key_name = strdup(insn->call_dest->name); | |
477 | if (!key_name) { | |
478 | perror("strdup"); | |
479 | return -1; | |
480 | } | |
481 | if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR, | |
482 | STATIC_CALL_TRAMP_PREFIX_LEN)) { | |
483 | WARN("static_call: trampoline name malformed: %s", key_name); | |
484 | return -1; | |
485 | } | |
486 | tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN; | |
487 | memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN); | |
488 | ||
489 | key_sym = find_symbol_by_name(file->elf, tmp); | |
490 | if (!key_sym) { | |
73f44fe1 JP |
491 | if (!module) { |
492 | WARN("static_call: can't find static_call_key symbol: %s", tmp); | |
493 | return -1; | |
494 | } | |
495 | ||
496 | /* | |
497 | * For modules(), the key might not be exported, which | |
498 | * means the module can make static calls but isn't | |
499 | * allowed to change them. | |
500 | * | |
501 | * In that case we temporarily set the key to be the | |
502 | * trampoline address. This is fixed up in | |
503 | * static_call_add_module(). | |
504 | */ | |
505 | key_sym = insn->call_dest; | |
1e7e4788 JP |
506 | } |
507 | free(key_name); | |
508 | ||
509 | /* populate reloc for 'key' */ | |
ef47cc01 PZ |
510 | if (elf_add_reloc(file->elf, sec, |
511 | idx * sizeof(struct static_call_site) + 4, | |
512 | R_X86_64_PC32, key_sym, | |
513 | is_sibling_call(insn) * STATIC_CALL_SITE_TAIL)) | |
1e7e4788 | 514 | return -1; |
1e7e4788 JP |
515 | |
516 | idx++; | |
517 | } | |
518 | ||
1e7e4788 JP |
519 | return 0; |
520 | } | |
521 | ||
99d00215 PZ |
522 | static int create_mcount_loc_sections(struct objtool_file *file) |
523 | { | |
ef47cc01 | 524 | struct section *sec; |
99d00215 PZ |
525 | unsigned long *loc; |
526 | struct instruction *insn; | |
527 | int idx; | |
528 | ||
529 | sec = find_section_by_name(file->elf, "__mcount_loc"); | |
530 | if (sec) { | |
531 | INIT_LIST_HEAD(&file->mcount_loc_list); | |
532 | WARN("file already has __mcount_loc section, skipping"); | |
533 | return 0; | |
534 | } | |
535 | ||
536 | if (list_empty(&file->mcount_loc_list)) | |
537 | return 0; | |
538 | ||
539 | idx = 0; | |
540 | list_for_each_entry(insn, &file->mcount_loc_list, mcount_loc_node) | |
541 | idx++; | |
542 | ||
543 | sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx); | |
544 | if (!sec) | |
545 | return -1; | |
546 | ||
99d00215 PZ |
547 | idx = 0; |
548 | list_for_each_entry(insn, &file->mcount_loc_list, mcount_loc_node) { | |
549 | ||
550 | loc = (unsigned long *)sec->data->d_buf + idx; | |
551 | memset(loc, 0, sizeof(unsigned long)); | |
552 | ||
ef47cc01 PZ |
553 | if (elf_add_reloc_to_insn(file->elf, sec, |
554 | idx * sizeof(unsigned long), | |
555 | R_X86_64_64, | |
556 | insn->sec, insn->offset)) | |
99d00215 | 557 | return -1; |
99d00215 PZ |
558 | |
559 | idx++; | |
560 | } | |
561 | ||
99d00215 PZ |
562 | return 0; |
563 | } | |
564 | ||
dcc914f4 JP |
565 | /* |
566 | * Warnings shouldn't be reported for ignored functions. | |
567 | */ | |
568 | static void add_ignores(struct objtool_file *file) | |
569 | { | |
570 | struct instruction *insn; | |
571 | struct section *sec; | |
572 | struct symbol *func; | |
f1974222 | 573 | struct reloc *reloc; |
dcc914f4 | 574 | |
aaf5c623 PZ |
575 | sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard"); |
576 | if (!sec) | |
577 | return; | |
dcc914f4 | 578 | |
f1974222 MH |
579 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
580 | switch (reloc->sym->type) { | |
aaf5c623 | 581 | case STT_FUNC: |
f1974222 | 582 | func = reloc->sym; |
aaf5c623 PZ |
583 | break; |
584 | ||
585 | case STT_SECTION: | |
f1974222 | 586 | func = find_func_by_offset(reloc->sym->sec, reloc->addend); |
7acfe531 | 587 | if (!func) |
dcc914f4 | 588 | continue; |
aaf5c623 | 589 | break; |
dcc914f4 | 590 | |
aaf5c623 | 591 | default: |
f1974222 | 592 | WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type); |
aaf5c623 | 593 | continue; |
dcc914f4 | 594 | } |
aaf5c623 | 595 | |
f0f70adb | 596 | func_for_each_insn(file, func, insn) |
aaf5c623 | 597 | insn->ignore = true; |
dcc914f4 JP |
598 | } |
599 | } | |
600 | ||
ea24213d PZ |
601 | /* |
602 | * This is a whitelist of functions that is allowed to be called with AC set. | |
603 | * The list is meant to be minimal and only contains compiler instrumentation | |
604 | * ABI and a few functions used to implement *_{to,from}_user() functions. | |
605 | * | |
606 | * These functions must not directly change AC, but may PUSHF/POPF. | |
607 | */ | |
608 | static const char *uaccess_safe_builtin[] = { | |
609 | /* KASAN */ | |
610 | "kasan_report", | |
f00748bf | 611 | "kasan_check_range", |
ea24213d PZ |
612 | /* KASAN out-of-line */ |
613 | "__asan_loadN_noabort", | |
614 | "__asan_load1_noabort", | |
615 | "__asan_load2_noabort", | |
616 | "__asan_load4_noabort", | |
617 | "__asan_load8_noabort", | |
618 | "__asan_load16_noabort", | |
619 | "__asan_storeN_noabort", | |
620 | "__asan_store1_noabort", | |
621 | "__asan_store2_noabort", | |
622 | "__asan_store4_noabort", | |
623 | "__asan_store8_noabort", | |
624 | "__asan_store16_noabort", | |
b0b8e56b JH |
625 | "__kasan_check_read", |
626 | "__kasan_check_write", | |
ea24213d PZ |
627 | /* KASAN in-line */ |
628 | "__asan_report_load_n_noabort", | |
629 | "__asan_report_load1_noabort", | |
630 | "__asan_report_load2_noabort", | |
631 | "__asan_report_load4_noabort", | |
632 | "__asan_report_load8_noabort", | |
633 | "__asan_report_load16_noabort", | |
634 | "__asan_report_store_n_noabort", | |
635 | "__asan_report_store1_noabort", | |
636 | "__asan_report_store2_noabort", | |
637 | "__asan_report_store4_noabort", | |
638 | "__asan_report_store8_noabort", | |
639 | "__asan_report_store16_noabort", | |
5f5c9712 | 640 | /* KCSAN */ |
9967683c | 641 | "__kcsan_check_access", |
5f5c9712 ME |
642 | "kcsan_found_watchpoint", |
643 | "kcsan_setup_watchpoint", | |
9967683c | 644 | "kcsan_check_scoped_accesses", |
50a19ad4 ME |
645 | "kcsan_disable_current", |
646 | "kcsan_enable_current_nowarn", | |
5f5c9712 ME |
647 | /* KCSAN/TSAN */ |
648 | "__tsan_func_entry", | |
649 | "__tsan_func_exit", | |
650 | "__tsan_read_range", | |
651 | "__tsan_write_range", | |
652 | "__tsan_read1", | |
653 | "__tsan_read2", | |
654 | "__tsan_read4", | |
655 | "__tsan_read8", | |
656 | "__tsan_read16", | |
657 | "__tsan_write1", | |
658 | "__tsan_write2", | |
659 | "__tsan_write4", | |
660 | "__tsan_write8", | |
661 | "__tsan_write16", | |
a81b3759 ME |
662 | "__tsan_read_write1", |
663 | "__tsan_read_write2", | |
664 | "__tsan_read_write4", | |
665 | "__tsan_read_write8", | |
666 | "__tsan_read_write16", | |
883957b1 ME |
667 | "__tsan_atomic8_load", |
668 | "__tsan_atomic16_load", | |
669 | "__tsan_atomic32_load", | |
670 | "__tsan_atomic64_load", | |
671 | "__tsan_atomic8_store", | |
672 | "__tsan_atomic16_store", | |
673 | "__tsan_atomic32_store", | |
674 | "__tsan_atomic64_store", | |
675 | "__tsan_atomic8_exchange", | |
676 | "__tsan_atomic16_exchange", | |
677 | "__tsan_atomic32_exchange", | |
678 | "__tsan_atomic64_exchange", | |
679 | "__tsan_atomic8_fetch_add", | |
680 | "__tsan_atomic16_fetch_add", | |
681 | "__tsan_atomic32_fetch_add", | |
682 | "__tsan_atomic64_fetch_add", | |
683 | "__tsan_atomic8_fetch_sub", | |
684 | "__tsan_atomic16_fetch_sub", | |
685 | "__tsan_atomic32_fetch_sub", | |
686 | "__tsan_atomic64_fetch_sub", | |
687 | "__tsan_atomic8_fetch_and", | |
688 | "__tsan_atomic16_fetch_and", | |
689 | "__tsan_atomic32_fetch_and", | |
690 | "__tsan_atomic64_fetch_and", | |
691 | "__tsan_atomic8_fetch_or", | |
692 | "__tsan_atomic16_fetch_or", | |
693 | "__tsan_atomic32_fetch_or", | |
694 | "__tsan_atomic64_fetch_or", | |
695 | "__tsan_atomic8_fetch_xor", | |
696 | "__tsan_atomic16_fetch_xor", | |
697 | "__tsan_atomic32_fetch_xor", | |
698 | "__tsan_atomic64_fetch_xor", | |
699 | "__tsan_atomic8_fetch_nand", | |
700 | "__tsan_atomic16_fetch_nand", | |
701 | "__tsan_atomic32_fetch_nand", | |
702 | "__tsan_atomic64_fetch_nand", | |
703 | "__tsan_atomic8_compare_exchange_strong", | |
704 | "__tsan_atomic16_compare_exchange_strong", | |
705 | "__tsan_atomic32_compare_exchange_strong", | |
706 | "__tsan_atomic64_compare_exchange_strong", | |
707 | "__tsan_atomic8_compare_exchange_weak", | |
708 | "__tsan_atomic16_compare_exchange_weak", | |
709 | "__tsan_atomic32_compare_exchange_weak", | |
710 | "__tsan_atomic64_compare_exchange_weak", | |
711 | "__tsan_atomic8_compare_exchange_val", | |
712 | "__tsan_atomic16_compare_exchange_val", | |
713 | "__tsan_atomic32_compare_exchange_val", | |
714 | "__tsan_atomic64_compare_exchange_val", | |
715 | "__tsan_atomic_thread_fence", | |
716 | "__tsan_atomic_signal_fence", | |
ea24213d PZ |
717 | /* KCOV */ |
718 | "write_comp_data", | |
ae033f08 | 719 | "check_kcov_mode", |
ea24213d PZ |
720 | "__sanitizer_cov_trace_pc", |
721 | "__sanitizer_cov_trace_const_cmp1", | |
722 | "__sanitizer_cov_trace_const_cmp2", | |
723 | "__sanitizer_cov_trace_const_cmp4", | |
724 | "__sanitizer_cov_trace_const_cmp8", | |
725 | "__sanitizer_cov_trace_cmp1", | |
726 | "__sanitizer_cov_trace_cmp2", | |
727 | "__sanitizer_cov_trace_cmp4", | |
728 | "__sanitizer_cov_trace_cmp8", | |
36b1c700 | 729 | "__sanitizer_cov_trace_switch", |
ea24213d PZ |
730 | /* UBSAN */ |
731 | "ubsan_type_mismatch_common", | |
732 | "__ubsan_handle_type_mismatch", | |
733 | "__ubsan_handle_type_mismatch_v1", | |
9a50dcaf | 734 | "__ubsan_handle_shift_out_of_bounds", |
ea24213d PZ |
735 | /* misc */ |
736 | "csum_partial_copy_generic", | |
ec6347bb DW |
737 | "copy_mc_fragile", |
738 | "copy_mc_fragile_handle_tail", | |
5da8e4a6 | 739 | "copy_mc_enhanced_fast_string", |
ea24213d PZ |
740 | "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */ |
741 | NULL | |
742 | }; | |
743 | ||
744 | static void add_uaccess_safe(struct objtool_file *file) | |
745 | { | |
746 | struct symbol *func; | |
747 | const char **name; | |
748 | ||
749 | if (!uaccess) | |
750 | return; | |
751 | ||
752 | for (name = uaccess_safe_builtin; *name; name++) { | |
753 | func = find_symbol_by_name(file->elf, *name); | |
754 | if (!func) | |
755 | continue; | |
756 | ||
e10cd8fe | 757 | func->uaccess_safe = true; |
dcc914f4 JP |
758 | } |
759 | } | |
760 | ||
258c7605 JP |
761 | /* |
762 | * FIXME: For now, just ignore any alternatives which add retpolines. This is | |
763 | * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline. | |
764 | * But it at least allows objtool to understand the control flow *around* the | |
765 | * retpoline. | |
766 | */ | |
ff05ab23 | 767 | static int add_ignore_alternatives(struct objtool_file *file) |
258c7605 JP |
768 | { |
769 | struct section *sec; | |
f1974222 | 770 | struct reloc *reloc; |
258c7605 JP |
771 | struct instruction *insn; |
772 | ||
ff05ab23 | 773 | sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts"); |
258c7605 JP |
774 | if (!sec) |
775 | return 0; | |
776 | ||
f1974222 MH |
777 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
778 | if (reloc->sym->type != STT_SECTION) { | |
258c7605 JP |
779 | WARN("unexpected relocation symbol type in %s", sec->name); |
780 | return -1; | |
781 | } | |
782 | ||
f1974222 | 783 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
258c7605 | 784 | if (!insn) { |
ff05ab23 | 785 | WARN("bad .discard.ignore_alts entry"); |
258c7605 JP |
786 | return -1; |
787 | } | |
788 | ||
789 | insn->ignore_alts = true; | |
790 | } | |
791 | ||
792 | return 0; | |
793 | } | |
794 | ||
530b4ddd PZ |
795 | __weak bool arch_is_retpoline(struct symbol *sym) |
796 | { | |
797 | return false; | |
798 | } | |
799 | ||
dcc914f4 JP |
800 | /* |
801 | * Find the destination instructions for all jumps. | |
802 | */ | |
803 | static int add_jump_destinations(struct objtool_file *file) | |
804 | { | |
805 | struct instruction *insn; | |
f1974222 | 806 | struct reloc *reloc; |
dcc914f4 JP |
807 | struct section *dest_sec; |
808 | unsigned long dest_off; | |
809 | ||
810 | for_each_insn(file, insn) { | |
a2296140 | 811 | if (!is_static_jump(insn)) |
dcc914f4 JP |
812 | continue; |
813 | ||
f1974222 | 814 | reloc = find_reloc_by_dest_range(file->elf, insn->sec, |
ecf11ba4 | 815 | insn->offset, insn->len); |
f1974222 | 816 | if (!reloc) { |
dcc914f4 | 817 | dest_sec = insn->sec; |
bfb08f22 | 818 | dest_off = arch_jump_destination(insn); |
f1974222 MH |
819 | } else if (reloc->sym->type == STT_SECTION) { |
820 | dest_sec = reloc->sym->sec; | |
821 | dest_off = arch_dest_reloc_offset(reloc->addend); | |
530b4ddd | 822 | } else if (arch_is_retpoline(reloc->sym)) { |
39b73533 JP |
823 | /* |
824 | * Retpoline jumps are really dynamic jumps in | |
825 | * disguise, so convert them accordingly. | |
826 | */ | |
b68b9907 JP |
827 | if (insn->type == INSN_JUMP_UNCONDITIONAL) |
828 | insn->type = INSN_JUMP_DYNAMIC; | |
829 | else | |
830 | insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL; | |
831 | ||
b5bc2231 | 832 | insn->retpoline_safe = true; |
39b73533 | 833 | continue; |
ecf11ba4 JP |
834 | } else if (insn->func) { |
835 | /* internal or external sibling call (with reloc) */ | |
f1974222 | 836 | insn->call_dest = reloc->sym; |
5b06fd3b PZ |
837 | if (insn->call_dest->static_call_tramp) { |
838 | list_add_tail(&insn->static_call_node, | |
839 | &file->static_call_list); | |
840 | } | |
dcc914f4 | 841 | continue; |
ecf11ba4 JP |
842 | } else if (reloc->sym->sec->idx) { |
843 | dest_sec = reloc->sym->sec; | |
844 | dest_off = reloc->sym->sym.st_value + | |
845 | arch_dest_reloc_offset(reloc->addend); | |
846 | } else { | |
847 | /* non-func asm code jumping to another file */ | |
848 | continue; | |
dcc914f4 JP |
849 | } |
850 | ||
851 | insn->jump_dest = find_insn(file, dest_sec, dest_off); | |
852 | if (!insn->jump_dest) { | |
853 | ||
854 | /* | |
855 | * This is a special case where an alt instruction | |
856 | * jumps past the end of the section. These are | |
857 | * handled later in handle_group_alt(). | |
858 | */ | |
859 | if (!strcmp(insn->sec->name, ".altinstr_replacement")) | |
860 | continue; | |
861 | ||
862 | WARN_FUNC("can't find jump dest instruction at %s+0x%lx", | |
863 | insn->sec, insn->offset, dest_sec->name, | |
864 | dest_off); | |
865 | return -1; | |
866 | } | |
cd77849a JP |
867 | |
868 | /* | |
54262aa2 | 869 | * Cross-function jump. |
cd77849a JP |
870 | */ |
871 | if (insn->func && insn->jump_dest->func && | |
54262aa2 PZ |
872 | insn->func != insn->jump_dest->func) { |
873 | ||
874 | /* | |
875 | * For GCC 8+, create parent/child links for any cold | |
876 | * subfunctions. This is _mostly_ redundant with a | |
877 | * similar initialization in read_symbols(). | |
878 | * | |
879 | * If a function has aliases, we want the *first* such | |
880 | * function in the symbol table to be the subfunction's | |
881 | * parent. In that case we overwrite the | |
882 | * initialization done in read_symbols(). | |
883 | * | |
884 | * However this code can't completely replace the | |
885 | * read_symbols() code because this doesn't detect the | |
886 | * case where the parent function's only reference to a | |
e7c2bc37 | 887 | * subfunction is through a jump table. |
54262aa2 | 888 | */ |
34ca59e1 JP |
889 | if (!strstr(insn->func->name, ".cold") && |
890 | strstr(insn->jump_dest->func->name, ".cold")) { | |
54262aa2 PZ |
891 | insn->func->cfunc = insn->jump_dest->func; |
892 | insn->jump_dest->func->pfunc = insn->func; | |
893 | ||
894 | } else if (insn->jump_dest->func->pfunc != insn->func->pfunc && | |
895 | insn->jump_dest->offset == insn->jump_dest->func->offset) { | |
896 | ||
ecf11ba4 | 897 | /* internal sibling call (without reloc) */ |
54262aa2 | 898 | insn->call_dest = insn->jump_dest->func; |
5b06fd3b PZ |
899 | if (insn->call_dest->static_call_tramp) { |
900 | list_add_tail(&insn->static_call_node, | |
901 | &file->static_call_list); | |
902 | } | |
54262aa2 | 903 | } |
cd77849a | 904 | } |
dcc914f4 JP |
905 | } |
906 | ||
907 | return 0; | |
908 | } | |
909 | ||
8aa8eb2a AC |
910 | static void remove_insn_ops(struct instruction *insn) |
911 | { | |
912 | struct stack_op *op, *tmp; | |
913 | ||
914 | list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) { | |
915 | list_del(&op->list); | |
916 | free(op); | |
917 | } | |
918 | } | |
919 | ||
2b232a22 JT |
920 | static struct symbol *find_call_destination(struct section *sec, unsigned long offset) |
921 | { | |
922 | struct symbol *call_dest; | |
923 | ||
924 | call_dest = find_func_by_offset(sec, offset); | |
925 | if (!call_dest) | |
926 | call_dest = find_symbol_by_offset(sec, offset); | |
927 | ||
928 | return call_dest; | |
929 | } | |
930 | ||
dcc914f4 JP |
931 | /* |
932 | * Find the destination instructions for all calls. | |
933 | */ | |
934 | static int add_call_destinations(struct objtool_file *file) | |
935 | { | |
936 | struct instruction *insn; | |
937 | unsigned long dest_off; | |
f1974222 | 938 | struct reloc *reloc; |
dcc914f4 JP |
939 | |
940 | for_each_insn(file, insn) { | |
941 | if (insn->type != INSN_CALL) | |
942 | continue; | |
943 | ||
f1974222 | 944 | reloc = find_reloc_by_dest_range(file->elf, insn->sec, |
8b5fa6bc | 945 | insn->offset, insn->len); |
f1974222 | 946 | if (!reloc) { |
bfb08f22 | 947 | dest_off = arch_jump_destination(insn); |
2b232a22 | 948 | insn->call_dest = find_call_destination(insn->sec, dest_off); |
a845c7cf | 949 | |
7acfe531 JP |
950 | if (insn->ignore) |
951 | continue; | |
952 | ||
953 | if (!insn->call_dest) { | |
8aa8eb2a | 954 | WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset); |
dcc914f4 JP |
955 | return -1; |
956 | } | |
a845c7cf | 957 | |
7acfe531 JP |
958 | if (insn->func && insn->call_dest->type != STT_FUNC) { |
959 | WARN_FUNC("unsupported call to non-function", | |
960 | insn->sec, insn->offset); | |
961 | return -1; | |
962 | } | |
963 | ||
f1974222 MH |
964 | } else if (reloc->sym->type == STT_SECTION) { |
965 | dest_off = arch_dest_reloc_offset(reloc->addend); | |
2b232a22 JT |
966 | insn->call_dest = find_call_destination(reloc->sym->sec, |
967 | dest_off); | |
7acfe531 | 968 | if (!insn->call_dest) { |
bfb08f22 | 969 | WARN_FUNC("can't find call dest symbol at %s+0x%lx", |
dcc914f4 | 970 | insn->sec, insn->offset, |
f1974222 | 971 | reloc->sym->sec->name, |
bfb08f22 | 972 | dest_off); |
dcc914f4 JP |
973 | return -1; |
974 | } | |
bcb1b6ff | 975 | |
530b4ddd | 976 | } else if (arch_is_retpoline(reloc->sym)) { |
bcb1b6ff PZ |
977 | /* |
978 | * Retpoline calls are really dynamic calls in | |
979 | * disguise, so convert them accordingly. | |
980 | */ | |
981 | insn->type = INSN_CALL_DYNAMIC; | |
982 | insn->retpoline_safe = true; | |
983 | ||
984 | remove_insn_ops(insn); | |
985 | continue; | |
986 | ||
dcc914f4 | 987 | } else |
f1974222 | 988 | insn->call_dest = reloc->sym; |
8aa8eb2a | 989 | |
a958c4fe PZ |
990 | if (insn->call_dest && insn->call_dest->static_call_tramp) { |
991 | list_add_tail(&insn->static_call_node, | |
992 | &file->static_call_list); | |
993 | } | |
994 | ||
0f1441b4 PZ |
995 | /* |
996 | * Many compilers cannot disable KCOV with a function attribute | |
997 | * so they need a little help, NOP out any KCOV calls from noinstr | |
998 | * text. | |
999 | */ | |
1000 | if (insn->sec->noinstr && | |
1001 | !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) { | |
d832c005 PZ |
1002 | if (reloc) { |
1003 | reloc->type = R_NONE; | |
1004 | elf_write_reloc(file->elf, reloc); | |
0f1441b4 PZ |
1005 | } |
1006 | ||
1007 | elf_write_insn(file->elf, insn->sec, | |
1008 | insn->offset, insn->len, | |
1009 | arch_nop_insn(insn->len)); | |
1010 | insn->type = INSN_NOP; | |
1011 | } | |
1012 | ||
99d00215 PZ |
1013 | if (mcount && !strcmp(insn->call_dest->name, "__fentry__")) { |
1014 | if (reloc) { | |
1015 | reloc->type = R_NONE; | |
1016 | elf_write_reloc(file->elf, reloc); | |
1017 | } | |
1018 | ||
1019 | elf_write_insn(file->elf, insn->sec, | |
1020 | insn->offset, insn->len, | |
1021 | arch_nop_insn(insn->len)); | |
1022 | ||
1023 | insn->type = INSN_NOP; | |
1024 | ||
1025 | list_add_tail(&insn->mcount_loc_node, | |
1026 | &file->mcount_loc_list); | |
1027 | } | |
1028 | ||
8aa8eb2a AC |
1029 | /* |
1030 | * Whatever stack impact regular CALLs have, should be undone | |
1031 | * by the RETURN of the called function. | |
1032 | * | |
1033 | * Annotated intra-function calls retain the stack_ops but | |
1034 | * are converted to JUMP, see read_intra_function_calls(). | |
1035 | */ | |
1036 | remove_insn_ops(insn); | |
dcc914f4 JP |
1037 | } |
1038 | ||
1039 | return 0; | |
1040 | } | |
1041 | ||
1042 | /* | |
c9c324dc JP |
1043 | * The .alternatives section requires some extra special care over and above |
1044 | * other special sections because alternatives are patched in place. | |
dcc914f4 JP |
1045 | */ |
1046 | static int handle_group_alt(struct objtool_file *file, | |
1047 | struct special_alt *special_alt, | |
1048 | struct instruction *orig_insn, | |
1049 | struct instruction **new_insn) | |
1050 | { | |
c9c324dc | 1051 | struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL; |
b23cc71c | 1052 | struct alt_group *orig_alt_group, *new_alt_group; |
dcc914f4 JP |
1053 | unsigned long dest_off; |
1054 | ||
b23cc71c JP |
1055 | |
1056 | orig_alt_group = malloc(sizeof(*orig_alt_group)); | |
1057 | if (!orig_alt_group) { | |
1058 | WARN("malloc failed"); | |
1059 | return -1; | |
1060 | } | |
c9c324dc JP |
1061 | orig_alt_group->cfi = calloc(special_alt->orig_len, |
1062 | sizeof(struct cfi_state *)); | |
1063 | if (!orig_alt_group->cfi) { | |
1064 | WARN("calloc failed"); | |
1065 | return -1; | |
1066 | } | |
1067 | ||
dcc914f4 JP |
1068 | last_orig_insn = NULL; |
1069 | insn = orig_insn; | |
1070 | sec_for_each_insn_from(file, insn) { | |
1071 | if (insn->offset >= special_alt->orig_off + special_alt->orig_len) | |
1072 | break; | |
1073 | ||
b23cc71c | 1074 | insn->alt_group = orig_alt_group; |
dcc914f4 JP |
1075 | last_orig_insn = insn; |
1076 | } | |
b23cc71c JP |
1077 | orig_alt_group->orig_group = NULL; |
1078 | orig_alt_group->first_insn = orig_insn; | |
1079 | orig_alt_group->last_insn = last_orig_insn; | |
dcc914f4 | 1080 | |
17bc3391 | 1081 | |
c9c324dc JP |
1082 | new_alt_group = malloc(sizeof(*new_alt_group)); |
1083 | if (!new_alt_group) { | |
1084 | WARN("malloc failed"); | |
1085 | return -1; | |
dcc914f4 | 1086 | } |
dcc914f4 | 1087 | |
c9c324dc JP |
1088 | if (special_alt->new_len < special_alt->orig_len) { |
1089 | /* | |
1090 | * Insert a fake nop at the end to make the replacement | |
1091 | * alt_group the same size as the original. This is needed to | |
1092 | * allow propagate_alt_cfi() to do its magic. When the last | |
1093 | * instruction affects the stack, the instruction after it (the | |
1094 | * nop) will propagate the new state to the shared CFI array. | |
1095 | */ | |
1096 | nop = malloc(sizeof(*nop)); | |
1097 | if (!nop) { | |
1098 | WARN("malloc failed"); | |
17bc3391 JP |
1099 | return -1; |
1100 | } | |
c9c324dc JP |
1101 | memset(nop, 0, sizeof(*nop)); |
1102 | INIT_LIST_HEAD(&nop->alts); | |
1103 | INIT_LIST_HEAD(&nop->stack_ops); | |
1104 | init_cfi_state(&nop->cfi); | |
1105 | ||
1106 | nop->sec = special_alt->new_sec; | |
1107 | nop->offset = special_alt->new_off + special_alt->new_len; | |
1108 | nop->len = special_alt->orig_len - special_alt->new_len; | |
1109 | nop->type = INSN_NOP; | |
1110 | nop->func = orig_insn->func; | |
1111 | nop->alt_group = new_alt_group; | |
1112 | nop->ignore = orig_insn->ignore_alts; | |
dcc914f4 | 1113 | } |
17bc3391 | 1114 | |
c9c324dc JP |
1115 | if (!special_alt->new_len) { |
1116 | *new_insn = nop; | |
1117 | goto end; | |
dcc914f4 JP |
1118 | } |
1119 | ||
dcc914f4 JP |
1120 | insn = *new_insn; |
1121 | sec_for_each_insn_from(file, insn) { | |
45245f51 JT |
1122 | struct reloc *alt_reloc; |
1123 | ||
dcc914f4 JP |
1124 | if (insn->offset >= special_alt->new_off + special_alt->new_len) |
1125 | break; | |
1126 | ||
1127 | last_new_insn = insn; | |
1128 | ||
a845c7cf | 1129 | insn->ignore = orig_insn->ignore_alts; |
a4d09dde | 1130 | insn->func = orig_insn->func; |
b23cc71c | 1131 | insn->alt_group = new_alt_group; |
a845c7cf | 1132 | |
dc419723 JP |
1133 | /* |
1134 | * Since alternative replacement code is copy/pasted by the | |
1135 | * kernel after applying relocations, generally such code can't | |
1136 | * have relative-address relocation references to outside the | |
1137 | * .altinstr_replacement section, unless the arch's | |
1138 | * alternatives code can adjust the relative offsets | |
1139 | * accordingly. | |
dc419723 | 1140 | */ |
45245f51 JT |
1141 | alt_reloc = find_reloc_by_dest_range(file->elf, insn->sec, |
1142 | insn->offset, insn->len); | |
1143 | if (alt_reloc && | |
1144 | !arch_support_alt_relocation(special_alt, insn, alt_reloc)) { | |
dc419723 JP |
1145 | |
1146 | WARN_FUNC("unsupported relocation in alternatives section", | |
1147 | insn->sec, insn->offset); | |
1148 | return -1; | |
1149 | } | |
1150 | ||
a2296140 | 1151 | if (!is_static_jump(insn)) |
dcc914f4 JP |
1152 | continue; |
1153 | ||
1154 | if (!insn->immediate) | |
1155 | continue; | |
1156 | ||
bfb08f22 | 1157 | dest_off = arch_jump_destination(insn); |
c9c324dc JP |
1158 | if (dest_off == special_alt->new_off + special_alt->new_len) |
1159 | insn->jump_dest = next_insn_same_sec(file, last_orig_insn); | |
dcc914f4 JP |
1160 | |
1161 | if (!insn->jump_dest) { | |
1162 | WARN_FUNC("can't find alternative jump destination", | |
1163 | insn->sec, insn->offset); | |
1164 | return -1; | |
1165 | } | |
1166 | } | |
1167 | ||
1168 | if (!last_new_insn) { | |
1169 | WARN_FUNC("can't find last new alternative instruction", | |
1170 | special_alt->new_sec, special_alt->new_off); | |
1171 | return -1; | |
1172 | } | |
1173 | ||
c9c324dc JP |
1174 | if (nop) |
1175 | list_add(&nop->list, &last_new_insn->list); | |
1176 | end: | |
b23cc71c JP |
1177 | new_alt_group->orig_group = orig_alt_group; |
1178 | new_alt_group->first_insn = *new_insn; | |
c9c324dc JP |
1179 | new_alt_group->last_insn = nop ? : last_new_insn; |
1180 | new_alt_group->cfi = orig_alt_group->cfi; | |
dcc914f4 JP |
1181 | return 0; |
1182 | } | |
1183 | ||
1184 | /* | |
1185 | * A jump table entry can either convert a nop to a jump or a jump to a nop. | |
1186 | * If the original instruction is a jump, make the alt entry an effective nop | |
1187 | * by just skipping the original instruction. | |
1188 | */ | |
1189 | static int handle_jump_alt(struct objtool_file *file, | |
1190 | struct special_alt *special_alt, | |
1191 | struct instruction *orig_insn, | |
1192 | struct instruction **new_insn) | |
1193 | { | |
1194 | if (orig_insn->type == INSN_NOP) | |
1195 | return 0; | |
1196 | ||
1197 | if (orig_insn->type != INSN_JUMP_UNCONDITIONAL) { | |
1198 | WARN_FUNC("unsupported instruction at jump label", | |
1199 | orig_insn->sec, orig_insn->offset); | |
1200 | return -1; | |
1201 | } | |
1202 | ||
1203 | *new_insn = list_next_entry(orig_insn, list); | |
1204 | return 0; | |
1205 | } | |
1206 | ||
1207 | /* | |
1208 | * Read all the special sections which have alternate instructions which can be | |
1209 | * patched in or redirected to at runtime. Each instruction having alternate | |
1210 | * instruction(s) has them added to its insn->alts list, which will be | |
1211 | * traversed in validate_branch(). | |
1212 | */ | |
1213 | static int add_special_section_alts(struct objtool_file *file) | |
1214 | { | |
1215 | struct list_head special_alts; | |
1216 | struct instruction *orig_insn, *new_insn; | |
1217 | struct special_alt *special_alt, *tmp; | |
1218 | struct alternative *alt; | |
1219 | int ret; | |
1220 | ||
1221 | ret = special_get_alts(file->elf, &special_alts); | |
1222 | if (ret) | |
1223 | return ret; | |
1224 | ||
1225 | list_for_each_entry_safe(special_alt, tmp, &special_alts, list) { | |
dcc914f4 JP |
1226 | |
1227 | orig_insn = find_insn(file, special_alt->orig_sec, | |
1228 | special_alt->orig_off); | |
1229 | if (!orig_insn) { | |
1230 | WARN_FUNC("special: can't find orig instruction", | |
1231 | special_alt->orig_sec, special_alt->orig_off); | |
1232 | ret = -1; | |
1233 | goto out; | |
1234 | } | |
1235 | ||
1236 | new_insn = NULL; | |
1237 | if (!special_alt->group || special_alt->new_len) { | |
1238 | new_insn = find_insn(file, special_alt->new_sec, | |
1239 | special_alt->new_off); | |
1240 | if (!new_insn) { | |
1241 | WARN_FUNC("special: can't find new instruction", | |
1242 | special_alt->new_sec, | |
1243 | special_alt->new_off); | |
1244 | ret = -1; | |
1245 | goto out; | |
1246 | } | |
1247 | } | |
1248 | ||
1249 | if (special_alt->group) { | |
7170cf47 JT |
1250 | if (!special_alt->orig_len) { |
1251 | WARN_FUNC("empty alternative entry", | |
1252 | orig_insn->sec, orig_insn->offset); | |
1253 | continue; | |
1254 | } | |
1255 | ||
dcc914f4 JP |
1256 | ret = handle_group_alt(file, special_alt, orig_insn, |
1257 | &new_insn); | |
1258 | if (ret) | |
1259 | goto out; | |
1260 | } else if (special_alt->jump_or_nop) { | |
1261 | ret = handle_jump_alt(file, special_alt, orig_insn, | |
1262 | &new_insn); | |
1263 | if (ret) | |
1264 | goto out; | |
1265 | } | |
1266 | ||
258c7605 JP |
1267 | alt = malloc(sizeof(*alt)); |
1268 | if (!alt) { | |
1269 | WARN("malloc failed"); | |
1270 | ret = -1; | |
1271 | goto out; | |
1272 | } | |
1273 | ||
dcc914f4 | 1274 | alt->insn = new_insn; |
764eef4b | 1275 | alt->skip_orig = special_alt->skip_orig; |
ea24213d | 1276 | orig_insn->ignore_alts |= special_alt->skip_alt; |
dcc914f4 JP |
1277 | list_add_tail(&alt->list, &orig_insn->alts); |
1278 | ||
1279 | list_del(&special_alt->list); | |
1280 | free(special_alt); | |
1281 | } | |
1282 | ||
1283 | out: | |
1284 | return ret; | |
1285 | } | |
1286 | ||
e7c2bc37 | 1287 | static int add_jump_table(struct objtool_file *file, struct instruction *insn, |
f1974222 | 1288 | struct reloc *table) |
dcc914f4 | 1289 | { |
f1974222 | 1290 | struct reloc *reloc = table; |
e7c2bc37 | 1291 | struct instruction *dest_insn; |
dcc914f4 | 1292 | struct alternative *alt; |
fd35c88b JP |
1293 | struct symbol *pfunc = insn->func->pfunc; |
1294 | unsigned int prev_offset = 0; | |
dcc914f4 | 1295 | |
e7c2bc37 | 1296 | /* |
f1974222 | 1297 | * Each @reloc is a switch table relocation which points to the target |
e7c2bc37 JP |
1298 | * instruction. |
1299 | */ | |
f1974222 | 1300 | list_for_each_entry_from(reloc, &table->sec->reloc_list, list) { |
bd98c813 JH |
1301 | |
1302 | /* Check for the end of the table: */ | |
f1974222 | 1303 | if (reloc != table && reloc->jump_table_start) |
dcc914f4 JP |
1304 | break; |
1305 | ||
e7c2bc37 | 1306 | /* Make sure the table entries are consecutive: */ |
f1974222 | 1307 | if (prev_offset && reloc->offset != prev_offset + 8) |
fd35c88b JP |
1308 | break; |
1309 | ||
1310 | /* Detect function pointers from contiguous objects: */ | |
f1974222 MH |
1311 | if (reloc->sym->sec == pfunc->sec && |
1312 | reloc->addend == pfunc->offset) | |
fd35c88b JP |
1313 | break; |
1314 | ||
f1974222 | 1315 | dest_insn = find_insn(file, reloc->sym->sec, reloc->addend); |
e7c2bc37 | 1316 | if (!dest_insn) |
dcc914f4 JP |
1317 | break; |
1318 | ||
e7c2bc37 | 1319 | /* Make sure the destination is in the same function: */ |
e65050b9 | 1320 | if (!dest_insn->func || dest_insn->func->pfunc != pfunc) |
13810435 | 1321 | break; |
dcc914f4 JP |
1322 | |
1323 | alt = malloc(sizeof(*alt)); | |
1324 | if (!alt) { | |
1325 | WARN("malloc failed"); | |
1326 | return -1; | |
1327 | } | |
1328 | ||
e7c2bc37 | 1329 | alt->insn = dest_insn; |
dcc914f4 | 1330 | list_add_tail(&alt->list, &insn->alts); |
f1974222 | 1331 | prev_offset = reloc->offset; |
fd35c88b JP |
1332 | } |
1333 | ||
1334 | if (!prev_offset) { | |
1335 | WARN_FUNC("can't find switch jump table", | |
1336 | insn->sec, insn->offset); | |
1337 | return -1; | |
dcc914f4 JP |
1338 | } |
1339 | ||
1340 | return 0; | |
1341 | } | |
1342 | ||
1343 | /* | |
d871f7b5 RG |
1344 | * find_jump_table() - Given a dynamic jump, find the switch jump table |
1345 | * associated with it. | |
dcc914f4 | 1346 | */ |
f1974222 | 1347 | static struct reloc *find_jump_table(struct objtool_file *file, |
dcc914f4 JP |
1348 | struct symbol *func, |
1349 | struct instruction *insn) | |
1350 | { | |
d871f7b5 | 1351 | struct reloc *table_reloc; |
113d4bc9 | 1352 | struct instruction *dest_insn, *orig_insn = insn; |
dcc914f4 | 1353 | |
99ce7962 PZ |
1354 | /* |
1355 | * Backward search using the @first_jump_src links, these help avoid | |
1356 | * much of the 'in between' code. Which avoids us getting confused by | |
1357 | * it. | |
1358 | */ | |
7dec80cc | 1359 | for (; |
1119d265 JP |
1360 | insn && insn->func && insn->func->pfunc == func; |
1361 | insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) { | |
99ce7962 | 1362 | |
7dec80cc | 1363 | if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC) |
dcc914f4 JP |
1364 | break; |
1365 | ||
1366 | /* allow small jumps within the range */ | |
1367 | if (insn->type == INSN_JUMP_UNCONDITIONAL && | |
1368 | insn->jump_dest && | |
1369 | (insn->jump_dest->offset <= insn->offset || | |
1370 | insn->jump_dest->offset > orig_insn->offset)) | |
1371 | break; | |
1372 | ||
d871f7b5 | 1373 | table_reloc = arch_find_switch_table(file, insn); |
f1974222 | 1374 | if (!table_reloc) |
e7c2bc37 | 1375 | continue; |
f1974222 | 1376 | dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend); |
113d4bc9 JP |
1377 | if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func) |
1378 | continue; | |
7dec80cc | 1379 | |
f1974222 | 1380 | return table_reloc; |
dcc914f4 JP |
1381 | } |
1382 | ||
1383 | return NULL; | |
1384 | } | |
1385 | ||
bd98c813 JH |
1386 | /* |
1387 | * First pass: Mark the head of each jump table so that in the next pass, | |
1388 | * we know when a given jump table ends and the next one starts. | |
1389 | */ | |
1390 | static void mark_func_jump_tables(struct objtool_file *file, | |
1391 | struct symbol *func) | |
dcc914f4 | 1392 | { |
bd98c813 | 1393 | struct instruction *insn, *last = NULL; |
f1974222 | 1394 | struct reloc *reloc; |
dcc914f4 | 1395 | |
f0f70adb | 1396 | func_for_each_insn(file, func, insn) { |
99ce7962 PZ |
1397 | if (!last) |
1398 | last = insn; | |
1399 | ||
1400 | /* | |
1401 | * Store back-pointers for unconditional forward jumps such | |
e7c2bc37 | 1402 | * that find_jump_table() can back-track using those and |
99ce7962 PZ |
1403 | * avoid some potentially confusing code. |
1404 | */ | |
1405 | if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest && | |
1406 | insn->offset > last->offset && | |
1407 | insn->jump_dest->offset > insn->offset && | |
1408 | !insn->jump_dest->first_jump_src) { | |
1409 | ||
1410 | insn->jump_dest->first_jump_src = insn; | |
1411 | last = insn->jump_dest; | |
1412 | } | |
1413 | ||
dcc914f4 JP |
1414 | if (insn->type != INSN_JUMP_DYNAMIC) |
1415 | continue; | |
1416 | ||
f1974222 MH |
1417 | reloc = find_jump_table(file, func, insn); |
1418 | if (reloc) { | |
1419 | reloc->jump_table_start = true; | |
1420 | insn->jump_table = reloc; | |
dcc914f4 | 1421 | } |
dcc914f4 | 1422 | } |
bd98c813 JH |
1423 | } |
1424 | ||
1425 | static int add_func_jump_tables(struct objtool_file *file, | |
1426 | struct symbol *func) | |
1427 | { | |
1428 | struct instruction *insn; | |
1429 | int ret; | |
1430 | ||
f0f70adb | 1431 | func_for_each_insn(file, func, insn) { |
bd98c813 JH |
1432 | if (!insn->jump_table) |
1433 | continue; | |
dcc914f4 | 1434 | |
bd98c813 | 1435 | ret = add_jump_table(file, insn, insn->jump_table); |
dcc914f4 JP |
1436 | if (ret) |
1437 | return ret; | |
1438 | } | |
1439 | ||
1440 | return 0; | |
1441 | } | |
1442 | ||
1443 | /* | |
1444 | * For some switch statements, gcc generates a jump table in the .rodata | |
1445 | * section which contains a list of addresses within the function to jump to. | |
1446 | * This finds these jump tables and adds them to the insn->alts lists. | |
1447 | */ | |
e7c2bc37 | 1448 | static int add_jump_table_alts(struct objtool_file *file) |
dcc914f4 JP |
1449 | { |
1450 | struct section *sec; | |
1451 | struct symbol *func; | |
1452 | int ret; | |
1453 | ||
4a60aa05 | 1454 | if (!file->rodata) |
dcc914f4 JP |
1455 | return 0; |
1456 | ||
baa41469 | 1457 | for_each_sec(file, sec) { |
dcc914f4 JP |
1458 | list_for_each_entry(func, &sec->symbol_list, list) { |
1459 | if (func->type != STT_FUNC) | |
1460 | continue; | |
1461 | ||
bd98c813 | 1462 | mark_func_jump_tables(file, func); |
e7c2bc37 | 1463 | ret = add_func_jump_tables(file, func); |
dcc914f4 JP |
1464 | if (ret) |
1465 | return ret; | |
1466 | } | |
1467 | } | |
1468 | ||
1469 | return 0; | |
1470 | } | |
1471 | ||
b735bd3e JP |
1472 | static void set_func_state(struct cfi_state *state) |
1473 | { | |
1474 | state->cfa = initial_func_cfi.cfa; | |
1475 | memcpy(&state->regs, &initial_func_cfi.regs, | |
1476 | CFI_NUM_REGS * sizeof(struct cfi_reg)); | |
1477 | state->stack_size = initial_func_cfi.cfa.offset; | |
1478 | } | |
1479 | ||
39358a03 JP |
1480 | static int read_unwind_hints(struct objtool_file *file) |
1481 | { | |
f1974222 MH |
1482 | struct section *sec, *relocsec; |
1483 | struct reloc *reloc; | |
39358a03 JP |
1484 | struct unwind_hint *hint; |
1485 | struct instruction *insn; | |
39358a03 JP |
1486 | int i; |
1487 | ||
1488 | sec = find_section_by_name(file->elf, ".discard.unwind_hints"); | |
1489 | if (!sec) | |
1490 | return 0; | |
1491 | ||
f1974222 MH |
1492 | relocsec = sec->reloc; |
1493 | if (!relocsec) { | |
39358a03 JP |
1494 | WARN("missing .rela.discard.unwind_hints section"); |
1495 | return -1; | |
1496 | } | |
1497 | ||
1498 | if (sec->len % sizeof(struct unwind_hint)) { | |
1499 | WARN("struct unwind_hint size mismatch"); | |
1500 | return -1; | |
1501 | } | |
1502 | ||
1503 | file->hints = true; | |
1504 | ||
1505 | for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) { | |
1506 | hint = (struct unwind_hint *)sec->data->d_buf + i; | |
1507 | ||
f1974222 MH |
1508 | reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint)); |
1509 | if (!reloc) { | |
1510 | WARN("can't find reloc for unwind_hints[%d]", i); | |
39358a03 JP |
1511 | return -1; |
1512 | } | |
1513 | ||
f1974222 | 1514 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
39358a03 JP |
1515 | if (!insn) { |
1516 | WARN("can't find insn for unwind_hints[%d]", i); | |
1517 | return -1; | |
1518 | } | |
1519 | ||
b735bd3e | 1520 | insn->hint = true; |
39358a03 | 1521 | |
b735bd3e JP |
1522 | if (hint->type == UNWIND_HINT_TYPE_FUNC) { |
1523 | set_func_state(&insn->cfi); | |
39358a03 JP |
1524 | continue; |
1525 | } | |
1526 | ||
edea9e6b | 1527 | if (arch_decode_hint_reg(insn, hint->sp_reg)) { |
39358a03 JP |
1528 | WARN_FUNC("unsupported unwind_hint sp base reg %d", |
1529 | insn->sec, insn->offset, hint->sp_reg); | |
1530 | return -1; | |
1531 | } | |
1532 | ||
b735bd3e | 1533 | insn->cfi.cfa.offset = bswap_if_needed(hint->sp_offset); |
e7c0219b PZ |
1534 | insn->cfi.type = hint->type; |
1535 | insn->cfi.end = hint->end; | |
39358a03 JP |
1536 | } |
1537 | ||
1538 | return 0; | |
1539 | } | |
1540 | ||
b5bc2231 PZ |
1541 | static int read_retpoline_hints(struct objtool_file *file) |
1542 | { | |
63474dc4 | 1543 | struct section *sec; |
b5bc2231 | 1544 | struct instruction *insn; |
f1974222 | 1545 | struct reloc *reloc; |
b5bc2231 | 1546 | |
63474dc4 | 1547 | sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe"); |
b5bc2231 PZ |
1548 | if (!sec) |
1549 | return 0; | |
1550 | ||
f1974222 MH |
1551 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
1552 | if (reloc->sym->type != STT_SECTION) { | |
63474dc4 | 1553 | WARN("unexpected relocation symbol type in %s", sec->name); |
b5bc2231 PZ |
1554 | return -1; |
1555 | } | |
1556 | ||
f1974222 | 1557 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
b5bc2231 | 1558 | if (!insn) { |
63474dc4 | 1559 | WARN("bad .discard.retpoline_safe entry"); |
b5bc2231 PZ |
1560 | return -1; |
1561 | } | |
1562 | ||
1563 | if (insn->type != INSN_JUMP_DYNAMIC && | |
1564 | insn->type != INSN_CALL_DYNAMIC) { | |
63474dc4 | 1565 | WARN_FUNC("retpoline_safe hint not an indirect jump/call", |
b5bc2231 PZ |
1566 | insn->sec, insn->offset); |
1567 | return -1; | |
1568 | } | |
1569 | ||
1570 | insn->retpoline_safe = true; | |
1571 | } | |
1572 | ||
1573 | return 0; | |
1574 | } | |
1575 | ||
c4a33939 PZ |
1576 | static int read_instr_hints(struct objtool_file *file) |
1577 | { | |
1578 | struct section *sec; | |
1579 | struct instruction *insn; | |
f1974222 | 1580 | struct reloc *reloc; |
c4a33939 PZ |
1581 | |
1582 | sec = find_section_by_name(file->elf, ".rela.discard.instr_end"); | |
1583 | if (!sec) | |
1584 | return 0; | |
1585 | ||
f1974222 MH |
1586 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
1587 | if (reloc->sym->type != STT_SECTION) { | |
c4a33939 PZ |
1588 | WARN("unexpected relocation symbol type in %s", sec->name); |
1589 | return -1; | |
1590 | } | |
1591 | ||
f1974222 | 1592 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
c4a33939 PZ |
1593 | if (!insn) { |
1594 | WARN("bad .discard.instr_end entry"); | |
1595 | return -1; | |
1596 | } | |
1597 | ||
1598 | insn->instr--; | |
1599 | } | |
1600 | ||
1601 | sec = find_section_by_name(file->elf, ".rela.discard.instr_begin"); | |
1602 | if (!sec) | |
1603 | return 0; | |
1604 | ||
f1974222 MH |
1605 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
1606 | if (reloc->sym->type != STT_SECTION) { | |
c4a33939 PZ |
1607 | WARN("unexpected relocation symbol type in %s", sec->name); |
1608 | return -1; | |
1609 | } | |
1610 | ||
f1974222 | 1611 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
c4a33939 PZ |
1612 | if (!insn) { |
1613 | WARN("bad .discard.instr_begin entry"); | |
1614 | return -1; | |
1615 | } | |
1616 | ||
1617 | insn->instr++; | |
1618 | } | |
1619 | ||
1620 | return 0; | |
1621 | } | |
1622 | ||
8aa8eb2a AC |
1623 | static int read_intra_function_calls(struct objtool_file *file) |
1624 | { | |
1625 | struct instruction *insn; | |
1626 | struct section *sec; | |
f1974222 | 1627 | struct reloc *reloc; |
8aa8eb2a AC |
1628 | |
1629 | sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls"); | |
1630 | if (!sec) | |
1631 | return 0; | |
1632 | ||
f1974222 | 1633 | list_for_each_entry(reloc, &sec->reloc_list, list) { |
8aa8eb2a AC |
1634 | unsigned long dest_off; |
1635 | ||
f1974222 | 1636 | if (reloc->sym->type != STT_SECTION) { |
8aa8eb2a AC |
1637 | WARN("unexpected relocation symbol type in %s", |
1638 | sec->name); | |
1639 | return -1; | |
1640 | } | |
1641 | ||
f1974222 | 1642 | insn = find_insn(file, reloc->sym->sec, reloc->addend); |
8aa8eb2a AC |
1643 | if (!insn) { |
1644 | WARN("bad .discard.intra_function_call entry"); | |
1645 | return -1; | |
1646 | } | |
1647 | ||
1648 | if (insn->type != INSN_CALL) { | |
1649 | WARN_FUNC("intra_function_call not a direct call", | |
1650 | insn->sec, insn->offset); | |
1651 | return -1; | |
1652 | } | |
1653 | ||
1654 | /* | |
1655 | * Treat intra-function CALLs as JMPs, but with a stack_op. | |
1656 | * See add_call_destinations(), which strips stack_ops from | |
1657 | * normal CALLs. | |
1658 | */ | |
1659 | insn->type = INSN_JUMP_UNCONDITIONAL; | |
1660 | ||
1661 | dest_off = insn->offset + insn->len + insn->immediate; | |
1662 | insn->jump_dest = find_insn(file, insn->sec, dest_off); | |
1663 | if (!insn->jump_dest) { | |
1664 | WARN_FUNC("can't find call dest at %s+0x%lx", | |
1665 | insn->sec, insn->offset, | |
1666 | insn->sec->name, dest_off); | |
1667 | return -1; | |
1668 | } | |
1669 | } | |
1670 | ||
1671 | return 0; | |
1672 | } | |
1673 | ||
1e7e4788 JP |
1674 | static int read_static_call_tramps(struct objtool_file *file) |
1675 | { | |
1676 | struct section *sec; | |
1677 | struct symbol *func; | |
1678 | ||
1679 | for_each_sec(file, sec) { | |
1680 | list_for_each_entry(func, &sec->symbol_list, list) { | |
1681 | if (func->bind == STB_GLOBAL && | |
1682 | !strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR, | |
1683 | strlen(STATIC_CALL_TRAMP_PREFIX_STR))) | |
1684 | func->static_call_tramp = true; | |
1685 | } | |
1686 | } | |
1687 | ||
1688 | return 0; | |
1689 | } | |
1690 | ||
4a60aa05 AX |
1691 | static void mark_rodata(struct objtool_file *file) |
1692 | { | |
1693 | struct section *sec; | |
1694 | bool found = false; | |
1695 | ||
1696 | /* | |
87b512de JP |
1697 | * Search for the following rodata sections, each of which can |
1698 | * potentially contain jump tables: | |
1699 | * | |
1700 | * - .rodata: can contain GCC switch tables | |
1701 | * - .rodata.<func>: same, if -fdata-sections is being used | |
1702 | * - .rodata..c_jump_table: contains C annotated jump tables | |
1703 | * | |
1704 | * .rodata.str1.* sections are ignored; they don't contain jump tables. | |
4a60aa05 AX |
1705 | */ |
1706 | for_each_sec(file, sec) { | |
1ee44470 MS |
1707 | if (!strncmp(sec->name, ".rodata", 7) && |
1708 | !strstr(sec->name, ".str1.")) { | |
4a60aa05 AX |
1709 | sec->rodata = true; |
1710 | found = true; | |
1711 | } | |
1712 | } | |
1713 | ||
1714 | file->rodata = found; | |
1715 | } | |
1716 | ||
dcc914f4 JP |
1717 | static int decode_sections(struct objtool_file *file) |
1718 | { | |
1719 | int ret; | |
1720 | ||
4a60aa05 AX |
1721 | mark_rodata(file); |
1722 | ||
dcc914f4 JP |
1723 | ret = decode_instructions(file); |
1724 | if (ret) | |
1725 | return ret; | |
1726 | ||
1727 | ret = add_dead_ends(file); | |
1728 | if (ret) | |
1729 | return ret; | |
1730 | ||
1731 | add_ignores(file); | |
ea24213d | 1732 | add_uaccess_safe(file); |
dcc914f4 | 1733 | |
ff05ab23 | 1734 | ret = add_ignore_alternatives(file); |
258c7605 JP |
1735 | if (ret) |
1736 | return ret; | |
1737 | ||
a958c4fe PZ |
1738 | /* |
1739 | * Must be before add_{jump_call}_destination. | |
1740 | */ | |
5b06fd3b PZ |
1741 | ret = read_static_call_tramps(file); |
1742 | if (ret) | |
1743 | return ret; | |
1744 | ||
dcc914f4 JP |
1745 | ret = add_jump_destinations(file); |
1746 | if (ret) | |
1747 | return ret; | |
1748 | ||
a845c7cf | 1749 | ret = add_special_section_alts(file); |
dcc914f4 JP |
1750 | if (ret) |
1751 | return ret; | |
1752 | ||
a958c4fe PZ |
1753 | /* |
1754 | * Must be before add_call_destination(); it changes INSN_CALL to | |
1755 | * INSN_JUMP. | |
1756 | */ | |
8aa8eb2a AC |
1757 | ret = read_intra_function_calls(file); |
1758 | if (ret) | |
1759 | return ret; | |
1760 | ||
a845c7cf | 1761 | ret = add_call_destinations(file); |
dcc914f4 JP |
1762 | if (ret) |
1763 | return ret; | |
1764 | ||
e7c2bc37 | 1765 | ret = add_jump_table_alts(file); |
dcc914f4 JP |
1766 | if (ret) |
1767 | return ret; | |
1768 | ||
39358a03 JP |
1769 | ret = read_unwind_hints(file); |
1770 | if (ret) | |
1771 | return ret; | |
1772 | ||
b5bc2231 PZ |
1773 | ret = read_retpoline_hints(file); |
1774 | if (ret) | |
1775 | return ret; | |
1776 | ||
c4a33939 PZ |
1777 | ret = read_instr_hints(file); |
1778 | if (ret) | |
1779 | return ret; | |
1780 | ||
dcc914f4 JP |
1781 | return 0; |
1782 | } | |
1783 | ||
1784 | static bool is_fentry_call(struct instruction *insn) | |
1785 | { | |
87cf61fe | 1786 | if (insn->type == INSN_CALL && insn->call_dest && |
dcc914f4 JP |
1787 | insn->call_dest->type == STT_NOTYPE && |
1788 | !strcmp(insn->call_dest->name, "__fentry__")) | |
1789 | return true; | |
1790 | ||
1791 | return false; | |
1792 | } | |
1793 | ||
e25eea89 | 1794 | static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state) |
dcc914f4 | 1795 | { |
e7c0219b | 1796 | struct cfi_state *cfi = &state->cfi; |
baa41469 JP |
1797 | int i; |
1798 | ||
e7c0219b | 1799 | if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap) |
e25eea89 PZ |
1800 | return true; |
1801 | ||
b735bd3e | 1802 | if (cfi->cfa.offset != initial_func_cfi.cfa.offset) |
baa41469 JP |
1803 | return true; |
1804 | ||
b735bd3e | 1805 | if (cfi->stack_size != initial_func_cfi.cfa.offset) |
e25eea89 PZ |
1806 | return true; |
1807 | ||
1808 | for (i = 0; i < CFI_NUM_REGS; i++) { | |
e7c0219b PZ |
1809 | if (cfi->regs[i].base != initial_func_cfi.regs[i].base || |
1810 | cfi->regs[i].offset != initial_func_cfi.regs[i].offset) | |
baa41469 | 1811 | return true; |
e25eea89 | 1812 | } |
baa41469 JP |
1813 | |
1814 | return false; | |
1815 | } | |
1816 | ||
fb084fde JT |
1817 | static bool check_reg_frame_pos(const struct cfi_reg *reg, |
1818 | int expected_offset) | |
1819 | { | |
1820 | return reg->base == CFI_CFA && | |
1821 | reg->offset == expected_offset; | |
1822 | } | |
1823 | ||
baa41469 JP |
1824 | static bool has_valid_stack_frame(struct insn_state *state) |
1825 | { | |
e7c0219b PZ |
1826 | struct cfi_state *cfi = &state->cfi; |
1827 | ||
fb084fde JT |
1828 | if (cfi->cfa.base == CFI_BP && |
1829 | check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) && | |
1830 | check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8)) | |
baa41469 JP |
1831 | return true; |
1832 | ||
e7c0219b | 1833 | if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP) |
baa41469 JP |
1834 | return true; |
1835 | ||
1836 | return false; | |
dcc914f4 JP |
1837 | } |
1838 | ||
e7c0219b PZ |
1839 | static int update_cfi_state_regs(struct instruction *insn, |
1840 | struct cfi_state *cfi, | |
65ea47dc | 1841 | struct stack_op *op) |
627fce14 | 1842 | { |
e7c0219b | 1843 | struct cfi_reg *cfa = &cfi->cfa; |
627fce14 | 1844 | |
d8dd25a4 | 1845 | if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT) |
627fce14 JP |
1846 | return 0; |
1847 | ||
1848 | /* push */ | |
ea24213d | 1849 | if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF) |
627fce14 JP |
1850 | cfa->offset += 8; |
1851 | ||
1852 | /* pop */ | |
ea24213d | 1853 | if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF) |
627fce14 JP |
1854 | cfa->offset -= 8; |
1855 | ||
1856 | /* add immediate to sp */ | |
1857 | if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD && | |
1858 | op->dest.reg == CFI_SP && op->src.reg == CFI_SP) | |
1859 | cfa->offset -= op->src.offset; | |
1860 | ||
1861 | return 0; | |
1862 | } | |
1863 | ||
e7c0219b | 1864 | static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset) |
dcc914f4 | 1865 | { |
bf4d1a83 | 1866 | if (arch_callee_saved_reg(reg) && |
e7c0219b PZ |
1867 | cfi->regs[reg].base == CFI_UNDEFINED) { |
1868 | cfi->regs[reg].base = base; | |
1869 | cfi->regs[reg].offset = offset; | |
baa41469 | 1870 | } |
dcc914f4 JP |
1871 | } |
1872 | ||
e7c0219b | 1873 | static void restore_reg(struct cfi_state *cfi, unsigned char reg) |
dcc914f4 | 1874 | { |
e7c0219b PZ |
1875 | cfi->regs[reg].base = initial_func_cfi.regs[reg].base; |
1876 | cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset; | |
baa41469 JP |
1877 | } |
1878 | ||
1879 | /* | |
1880 | * A note about DRAP stack alignment: | |
1881 | * | |
1882 | * GCC has the concept of a DRAP register, which is used to help keep track of | |
1883 | * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP | |
1884 | * register. The typical DRAP pattern is: | |
1885 | * | |
1886 | * 4c 8d 54 24 08 lea 0x8(%rsp),%r10 | |
1887 | * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp | |
1888 | * 41 ff 72 f8 pushq -0x8(%r10) | |
1889 | * 55 push %rbp | |
1890 | * 48 89 e5 mov %rsp,%rbp | |
1891 | * (more pushes) | |
1892 | * 41 52 push %r10 | |
1893 | * ... | |
1894 | * 41 5a pop %r10 | |
1895 | * (more pops) | |
1896 | * 5d pop %rbp | |
1897 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1898 | * c3 retq | |
1899 | * | |
1900 | * There are some variations in the epilogues, like: | |
1901 | * | |
1902 | * 5b pop %rbx | |
1903 | * 41 5a pop %r10 | |
1904 | * 41 5c pop %r12 | |
1905 | * 41 5d pop %r13 | |
1906 | * 41 5e pop %r14 | |
1907 | * c9 leaveq | |
1908 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1909 | * c3 retq | |
1910 | * | |
1911 | * and: | |
1912 | * | |
1913 | * 4c 8b 55 e8 mov -0x18(%rbp),%r10 | |
1914 | * 48 8b 5d e0 mov -0x20(%rbp),%rbx | |
1915 | * 4c 8b 65 f0 mov -0x10(%rbp),%r12 | |
1916 | * 4c 8b 6d f8 mov -0x8(%rbp),%r13 | |
1917 | * c9 leaveq | |
1918 | * 49 8d 62 f8 lea -0x8(%r10),%rsp | |
1919 | * c3 retq | |
1920 | * | |
1921 | * Sometimes r13 is used as the DRAP register, in which case it's saved and | |
1922 | * restored beforehand: | |
1923 | * | |
1924 | * 41 55 push %r13 | |
1925 | * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13 | |
1926 | * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp | |
1927 | * ... | |
1928 | * 49 8d 65 f0 lea -0x10(%r13),%rsp | |
1929 | * 41 5d pop %r13 | |
1930 | * c3 retq | |
1931 | */ | |
e7c0219b | 1932 | static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi, |
65ea47dc | 1933 | struct stack_op *op) |
baa41469 | 1934 | { |
e7c0219b PZ |
1935 | struct cfi_reg *cfa = &cfi->cfa; |
1936 | struct cfi_reg *regs = cfi->regs; | |
baa41469 JP |
1937 | |
1938 | /* stack operations don't make sense with an undefined CFA */ | |
1939 | if (cfa->base == CFI_UNDEFINED) { | |
1940 | if (insn->func) { | |
1941 | WARN_FUNC("undefined stack state", insn->sec, insn->offset); | |
1942 | return -1; | |
1943 | } | |
1944 | return 0; | |
1945 | } | |
1946 | ||
ee819aed JT |
1947 | if (cfi->type == UNWIND_HINT_TYPE_REGS || |
1948 | cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL) | |
e7c0219b | 1949 | return update_cfi_state_regs(insn, cfi, op); |
627fce14 | 1950 | |
baa41469 JP |
1951 | switch (op->dest.type) { |
1952 | ||
1953 | case OP_DEST_REG: | |
1954 | switch (op->src.type) { | |
1955 | ||
1956 | case OP_SRC_REG: | |
0d0970ee JP |
1957 | if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP && |
1958 | cfa->base == CFI_SP && | |
fb084fde | 1959 | check_reg_frame_pos(®s[CFI_BP], -cfa->offset)) { |
0d0970ee JP |
1960 | |
1961 | /* mov %rsp, %rbp */ | |
1962 | cfa->base = op->dest.reg; | |
e7c0219b | 1963 | cfi->bp_scratch = false; |
0d0970ee | 1964 | } |
dd88a0a0 | 1965 | |
0d0970ee | 1966 | else if (op->src.reg == CFI_SP && |
e7c0219b | 1967 | op->dest.reg == CFI_BP && cfi->drap) { |
dd88a0a0 | 1968 | |
0d0970ee JP |
1969 | /* drap: mov %rsp, %rbp */ |
1970 | regs[CFI_BP].base = CFI_BP; | |
e7c0219b PZ |
1971 | regs[CFI_BP].offset = -cfi->stack_size; |
1972 | cfi->bp_scratch = false; | |
0d0970ee | 1973 | } |
dd88a0a0 | 1974 | |
0d0970ee JP |
1975 | else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
1976 | ||
1977 | /* | |
1978 | * mov %rsp, %reg | |
1979 | * | |
1980 | * This is needed for the rare case where GCC | |
1981 | * does: | |
1982 | * | |
1983 | * mov %rsp, %rax | |
1984 | * ... | |
1985 | * mov %rax, %rsp | |
1986 | */ | |
e7c0219b PZ |
1987 | cfi->vals[op->dest.reg].base = CFI_CFA; |
1988 | cfi->vals[op->dest.reg].offset = -cfi->stack_size; | |
dd88a0a0 JP |
1989 | } |
1990 | ||
3c1f0583 JP |
1991 | else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP && |
1992 | cfa->base == CFI_BP) { | |
1993 | ||
1994 | /* | |
1995 | * mov %rbp, %rsp | |
1996 | * | |
1997 | * Restore the original stack pointer (Clang). | |
1998 | */ | |
e7c0219b | 1999 | cfi->stack_size = -cfi->regs[CFI_BP].offset; |
3c1f0583 JP |
2000 | } |
2001 | ||
dd88a0a0 JP |
2002 | else if (op->dest.reg == cfa->base) { |
2003 | ||
2004 | /* mov %reg, %rsp */ | |
2005 | if (cfa->base == CFI_SP && | |
e7c0219b | 2006 | cfi->vals[op->src.reg].base == CFI_CFA) { |
dd88a0a0 JP |
2007 | |
2008 | /* | |
2009 | * This is needed for the rare case | |
2010 | * where GCC does something dumb like: | |
2011 | * | |
2012 | * lea 0x8(%rsp), %rcx | |
2013 | * ... | |
2014 | * mov %rcx, %rsp | |
2015 | */ | |
e7c0219b PZ |
2016 | cfa->offset = -cfi->vals[op->src.reg].offset; |
2017 | cfi->stack_size = cfa->offset; | |
dd88a0a0 | 2018 | |
aafeb14e PZ |
2019 | } else if (cfa->base == CFI_SP && |
2020 | cfi->vals[op->src.reg].base == CFI_SP_INDIRECT && | |
2021 | cfi->vals[op->src.reg].offset == cfa->offset) { | |
2022 | ||
2023 | /* | |
2024 | * Stack swizzle: | |
2025 | * | |
2026 | * 1: mov %rsp, (%[tos]) | |
2027 | * 2: mov %[tos], %rsp | |
2028 | * ... | |
2029 | * 3: pop %rsp | |
2030 | * | |
2031 | * Where: | |
2032 | * | |
2033 | * 1 - places a pointer to the previous | |
2034 | * stack at the Top-of-Stack of the | |
2035 | * new stack. | |
2036 | * | |
2037 | * 2 - switches to the new stack. | |
2038 | * | |
2039 | * 3 - pops the Top-of-Stack to restore | |
2040 | * the original stack. | |
2041 | * | |
2042 | * Note: we set base to SP_INDIRECT | |
2043 | * here and preserve offset. Therefore | |
2044 | * when the unwinder reaches ToS it | |
2045 | * will dereference SP and then add the | |
2046 | * offset to find the next frame, IOW: | |
2047 | * (%rsp) + offset. | |
2048 | */ | |
2049 | cfa->base = CFI_SP_INDIRECT; | |
2050 | ||
dd88a0a0 JP |
2051 | } else { |
2052 | cfa->base = CFI_UNDEFINED; | |
2053 | cfa->offset = 0; | |
2054 | } | |
baa41469 JP |
2055 | } |
2056 | ||
724c8a23 PZ |
2057 | else if (op->dest.reg == CFI_SP && |
2058 | cfi->vals[op->src.reg].base == CFI_SP_INDIRECT && | |
2059 | cfi->vals[op->src.reg].offset == cfa->offset) { | |
2060 | ||
2061 | /* | |
2062 | * The same stack swizzle case 2) as above. But | |
2063 | * because we can't change cfa->base, case 3) | |
2064 | * will become a regular POP. Pretend we're a | |
2065 | * PUSH so things don't go unbalanced. | |
2066 | */ | |
2067 | cfi->stack_size += 8; | |
2068 | } | |
2069 | ||
2070 | ||
baa41469 JP |
2071 | break; |
2072 | ||
2073 | case OP_SRC_ADD: | |
2074 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) { | |
2075 | ||
2076 | /* add imm, %rsp */ | |
e7c0219b | 2077 | cfi->stack_size -= op->src.offset; |
baa41469 JP |
2078 | if (cfa->base == CFI_SP) |
2079 | cfa->offset -= op->src.offset; | |
2080 | break; | |
2081 | } | |
2082 | ||
2083 | if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) { | |
2084 | ||
2085 | /* lea disp(%rbp), %rsp */ | |
e7c0219b | 2086 | cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset); |
baa41469 JP |
2087 | break; |
2088 | } | |
2089 | ||
468af56a JT |
2090 | if (!cfi->drap && op->src.reg == CFI_SP && |
2091 | op->dest.reg == CFI_BP && cfa->base == CFI_SP && | |
2092 | check_reg_frame_pos(®s[CFI_BP], -cfa->offset + op->src.offset)) { | |
2093 | ||
2094 | /* lea disp(%rsp), %rbp */ | |
2095 | cfa->base = CFI_BP; | |
2096 | cfa->offset -= op->src.offset; | |
2097 | cfi->bp_scratch = false; | |
2098 | break; | |
2099 | } | |
2100 | ||
dd88a0a0 | 2101 | if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { |
baa41469 JP |
2102 | |
2103 | /* drap: lea disp(%rsp), %drap */ | |
e7c0219b | 2104 | cfi->drap_reg = op->dest.reg; |
dd88a0a0 JP |
2105 | |
2106 | /* | |
2107 | * lea disp(%rsp), %reg | |
2108 | * | |
2109 | * This is needed for the rare case where GCC | |
2110 | * does something dumb like: | |
2111 | * | |
2112 | * lea 0x8(%rsp), %rcx | |
2113 | * ... | |
2114 | * mov %rcx, %rsp | |
2115 | */ | |
e7c0219b PZ |
2116 | cfi->vals[op->dest.reg].base = CFI_CFA; |
2117 | cfi->vals[op->dest.reg].offset = \ | |
2118 | -cfi->stack_size + op->src.offset; | |
dd88a0a0 | 2119 | |
baa41469 JP |
2120 | break; |
2121 | } | |
2122 | ||
e7c0219b PZ |
2123 | if (cfi->drap && op->dest.reg == CFI_SP && |
2124 | op->src.reg == cfi->drap_reg) { | |
baa41469 JP |
2125 | |
2126 | /* drap: lea disp(%drap), %rsp */ | |
2127 | cfa->base = CFI_SP; | |
e7c0219b PZ |
2128 | cfa->offset = cfi->stack_size = -op->src.offset; |
2129 | cfi->drap_reg = CFI_UNDEFINED; | |
2130 | cfi->drap = false; | |
baa41469 JP |
2131 | break; |
2132 | } | |
2133 | ||
e7c0219b | 2134 | if (op->dest.reg == cfi->cfa.base) { |
baa41469 JP |
2135 | WARN_FUNC("unsupported stack register modification", |
2136 | insn->sec, insn->offset); | |
2137 | return -1; | |
2138 | } | |
2139 | ||
2140 | break; | |
2141 | ||
2142 | case OP_SRC_AND: | |
2143 | if (op->dest.reg != CFI_SP || | |
e7c0219b PZ |
2144 | (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) || |
2145 | (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) { | |
baa41469 JP |
2146 | WARN_FUNC("unsupported stack pointer realignment", |
2147 | insn->sec, insn->offset); | |
2148 | return -1; | |
2149 | } | |
2150 | ||
e7c0219b | 2151 | if (cfi->drap_reg != CFI_UNDEFINED) { |
baa41469 | 2152 | /* drap: and imm, %rsp */ |
e7c0219b PZ |
2153 | cfa->base = cfi->drap_reg; |
2154 | cfa->offset = cfi->stack_size = 0; | |
2155 | cfi->drap = true; | |
baa41469 JP |
2156 | } |
2157 | ||
2158 | /* | |
2159 | * Older versions of GCC (4.8ish) realign the stack | |
2160 | * without DRAP, with a frame pointer. | |
2161 | */ | |
2162 | ||
2163 | break; | |
2164 | ||
2165 | case OP_SRC_POP: | |
ea24213d | 2166 | case OP_SRC_POPF: |
aafeb14e PZ |
2167 | if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) { |
2168 | ||
2169 | /* pop %rsp; # restore from a stack swizzle */ | |
2170 | cfa->base = CFI_SP; | |
2171 | break; | |
2172 | } | |
2173 | ||
e7c0219b | 2174 | if (!cfi->drap && op->dest.reg == cfa->base) { |
baa41469 JP |
2175 | |
2176 | /* pop %rbp */ | |
2177 | cfa->base = CFI_SP; | |
2178 | } | |
2179 | ||
e7c0219b PZ |
2180 | if (cfi->drap && cfa->base == CFI_BP_INDIRECT && |
2181 | op->dest.reg == cfi->drap_reg && | |
2182 | cfi->drap_offset == -cfi->stack_size) { | |
baa41469 | 2183 | |
bf4d1a83 | 2184 | /* drap: pop %drap */ |
e7c0219b | 2185 | cfa->base = cfi->drap_reg; |
bf4d1a83 | 2186 | cfa->offset = 0; |
e7c0219b | 2187 | cfi->drap_offset = -1; |
baa41469 | 2188 | |
e7c0219b | 2189 | } else if (regs[op->dest.reg].offset == -cfi->stack_size) { |
baa41469 | 2190 | |
bf4d1a83 | 2191 | /* pop %reg */ |
e7c0219b | 2192 | restore_reg(cfi, op->dest.reg); |
baa41469 JP |
2193 | } |
2194 | ||
e7c0219b | 2195 | cfi->stack_size -= 8; |
baa41469 JP |
2196 | if (cfa->base == CFI_SP) |
2197 | cfa->offset -= 8; | |
2198 | ||
2199 | break; | |
2200 | ||
2201 | case OP_SRC_REG_INDIRECT: | |
201ef5a9 JT |
2202 | if (!cfi->drap && op->dest.reg == cfa->base && |
2203 | op->dest.reg == CFI_BP) { | |
2204 | ||
2205 | /* mov disp(%rsp), %rbp */ | |
2206 | cfa->base = CFI_SP; | |
2207 | cfa->offset = cfi->stack_size; | |
2208 | } | |
2209 | ||
e7c0219b PZ |
2210 | if (cfi->drap && op->src.reg == CFI_BP && |
2211 | op->src.offset == cfi->drap_offset) { | |
bf4d1a83 JP |
2212 | |
2213 | /* drap: mov disp(%rbp), %drap */ | |
e7c0219b | 2214 | cfa->base = cfi->drap_reg; |
bf4d1a83 | 2215 | cfa->offset = 0; |
e7c0219b | 2216 | cfi->drap_offset = -1; |
bf4d1a83 JP |
2217 | } |
2218 | ||
e7c0219b | 2219 | if (cfi->drap && op->src.reg == CFI_BP && |
baa41469 JP |
2220 | op->src.offset == regs[op->dest.reg].offset) { |
2221 | ||
2222 | /* drap: mov disp(%rbp), %reg */ | |
e7c0219b | 2223 | restore_reg(cfi, op->dest.reg); |
baa41469 JP |
2224 | |
2225 | } else if (op->src.reg == cfa->base && | |
2226 | op->src.offset == regs[op->dest.reg].offset + cfa->offset) { | |
2227 | ||
2228 | /* mov disp(%rbp), %reg */ | |
2229 | /* mov disp(%rsp), %reg */ | |
e7c0219b | 2230 | restore_reg(cfi, op->dest.reg); |
201ef5a9 JT |
2231 | |
2232 | } else if (op->src.reg == CFI_SP && | |
2233 | op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) { | |
2234 | ||
2235 | /* mov disp(%rsp), %reg */ | |
2236 | restore_reg(cfi, op->dest.reg); | |
baa41469 JP |
2237 | } |
2238 | ||
2239 | break; | |
2240 | ||
2241 | default: | |
2242 | WARN_FUNC("unknown stack-related instruction", | |
2243 | insn->sec, insn->offset); | |
2244 | return -1; | |
2245 | } | |
2246 | ||
2247 | break; | |
2248 | ||
2249 | case OP_DEST_PUSH: | |
ea24213d | 2250 | case OP_DEST_PUSHF: |
e7c0219b | 2251 | cfi->stack_size += 8; |
baa41469 JP |
2252 | if (cfa->base == CFI_SP) |
2253 | cfa->offset += 8; | |
2254 | ||
2255 | if (op->src.type != OP_SRC_REG) | |
2256 | break; | |
2257 | ||
e7c0219b PZ |
2258 | if (cfi->drap) { |
2259 | if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) { | |
baa41469 JP |
2260 | |
2261 | /* drap: push %drap */ | |
2262 | cfa->base = CFI_BP_INDIRECT; | |
e7c0219b | 2263 | cfa->offset = -cfi->stack_size; |
baa41469 | 2264 | |
bf4d1a83 | 2265 | /* save drap so we know when to restore it */ |
e7c0219b | 2266 | cfi->drap_offset = -cfi->stack_size; |
baa41469 | 2267 | |
e7c0219b | 2268 | } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) { |
baa41469 JP |
2269 | |
2270 | /* drap: push %rbp */ | |
e7c0219b | 2271 | cfi->stack_size = 0; |
baa41469 | 2272 | |
f4f80398 | 2273 | } else { |
baa41469 JP |
2274 | |
2275 | /* drap: push %reg */ | |
e7c0219b | 2276 | save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size); |
baa41469 JP |
2277 | } |
2278 | ||
2279 | } else { | |
2280 | ||
2281 | /* push %reg */ | |
e7c0219b | 2282 | save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size); |
baa41469 JP |
2283 | } |
2284 | ||
2285 | /* detect when asm code uses rbp as a scratch register */ | |
867ac9d7 | 2286 | if (!no_fp && insn->func && op->src.reg == CFI_BP && |
baa41469 | 2287 | cfa->base != CFI_BP) |
e7c0219b | 2288 | cfi->bp_scratch = true; |
baa41469 JP |
2289 | break; |
2290 | ||
2291 | case OP_DEST_REG_INDIRECT: | |
2292 | ||
e7c0219b PZ |
2293 | if (cfi->drap) { |
2294 | if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) { | |
baa41469 JP |
2295 | |
2296 | /* drap: mov %drap, disp(%rbp) */ | |
2297 | cfa->base = CFI_BP_INDIRECT; | |
2298 | cfa->offset = op->dest.offset; | |
2299 | ||
bf4d1a83 | 2300 | /* save drap offset so we know when to restore it */ |
e7c0219b | 2301 | cfi->drap_offset = op->dest.offset; |
f4f80398 | 2302 | } else { |
baa41469 JP |
2303 | |
2304 | /* drap: mov reg, disp(%rbp) */ | |
e7c0219b | 2305 | save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset); |
baa41469 JP |
2306 | } |
2307 | ||
2308 | } else if (op->dest.reg == cfa->base) { | |
2309 | ||
2310 | /* mov reg, disp(%rbp) */ | |
2311 | /* mov reg, disp(%rsp) */ | |
e7c0219b PZ |
2312 | save_reg(cfi, op->src.reg, CFI_CFA, |
2313 | op->dest.offset - cfi->cfa.offset); | |
201ef5a9 JT |
2314 | |
2315 | } else if (op->dest.reg == CFI_SP) { | |
2316 | ||
2317 | /* mov reg, disp(%rsp) */ | |
2318 | save_reg(cfi, op->src.reg, CFI_CFA, | |
2319 | op->dest.offset - cfi->stack_size); | |
aafeb14e PZ |
2320 | |
2321 | } else if (op->src.reg == CFI_SP && op->dest.offset == 0) { | |
2322 | ||
2323 | /* mov %rsp, (%reg); # setup a stack swizzle. */ | |
2324 | cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT; | |
2325 | cfi->vals[op->dest.reg].offset = cfa->offset; | |
baa41469 JP |
2326 | } |
2327 | ||
2328 | break; | |
2329 | ||
2330 | case OP_DEST_LEAVE: | |
e7c0219b PZ |
2331 | if ((!cfi->drap && cfa->base != CFI_BP) || |
2332 | (cfi->drap && cfa->base != cfi->drap_reg)) { | |
baa41469 JP |
2333 | WARN_FUNC("leave instruction with modified stack frame", |
2334 | insn->sec, insn->offset); | |
2335 | return -1; | |
2336 | } | |
2337 | ||
2338 | /* leave (mov %rbp, %rsp; pop %rbp) */ | |
2339 | ||
e7c0219b PZ |
2340 | cfi->stack_size = -cfi->regs[CFI_BP].offset - 8; |
2341 | restore_reg(cfi, CFI_BP); | |
baa41469 | 2342 | |
e7c0219b | 2343 | if (!cfi->drap) { |
baa41469 JP |
2344 | cfa->base = CFI_SP; |
2345 | cfa->offset -= 8; | |
2346 | } | |
2347 | ||
2348 | break; | |
2349 | ||
2350 | case OP_DEST_MEM: | |
ea24213d | 2351 | if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) { |
baa41469 JP |
2352 | WARN_FUNC("unknown stack-related memory operation", |
2353 | insn->sec, insn->offset); | |
2354 | return -1; | |
2355 | } | |
2356 | ||
2357 | /* pop mem */ | |
e7c0219b | 2358 | cfi->stack_size -= 8; |
baa41469 JP |
2359 | if (cfa->base == CFI_SP) |
2360 | cfa->offset -= 8; | |
2361 | ||
2362 | break; | |
2363 | ||
2364 | default: | |
2365 | WARN_FUNC("unknown stack-related instruction", | |
2366 | insn->sec, insn->offset); | |
2367 | return -1; | |
2368 | } | |
2369 | ||
2370 | return 0; | |
2371 | } | |
2372 | ||
c9c324dc JP |
2373 | /* |
2374 | * The stack layouts of alternatives instructions can sometimes diverge when | |
2375 | * they have stack modifications. That's fine as long as the potential stack | |
2376 | * layouts don't conflict at any given potential instruction boundary. | |
2377 | * | |
2378 | * Flatten the CFIs of the different alternative code streams (both original | |
2379 | * and replacement) into a single shared CFI array which can be used to detect | |
2380 | * conflicts and nicely feed a linear array of ORC entries to the unwinder. | |
2381 | */ | |
2382 | static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn) | |
65ea47dc | 2383 | { |
c9c324dc JP |
2384 | struct cfi_state **alt_cfi; |
2385 | int group_off; | |
65ea47dc | 2386 | |
c9c324dc JP |
2387 | if (!insn->alt_group) |
2388 | return 0; | |
65ea47dc | 2389 | |
c9c324dc JP |
2390 | alt_cfi = insn->alt_group->cfi; |
2391 | group_off = insn->offset - insn->alt_group->first_insn->offset; | |
65ea47dc | 2392 | |
c9c324dc JP |
2393 | if (!alt_cfi[group_off]) { |
2394 | alt_cfi[group_off] = &insn->cfi; | |
2395 | } else { | |
2396 | if (memcmp(alt_cfi[group_off], &insn->cfi, sizeof(struct cfi_state))) { | |
2397 | WARN_FUNC("stack layout conflict in alternatives", | |
2398 | insn->sec, insn->offset); | |
ab3852ab PZ |
2399 | return -1; |
2400 | } | |
c9c324dc JP |
2401 | } |
2402 | ||
2403 | return 0; | |
2404 | } | |
2405 | ||
2406 | static int handle_insn_ops(struct instruction *insn, struct insn_state *state) | |
2407 | { | |
2408 | struct stack_op *op; | |
2409 | ||
2410 | list_for_each_entry(op, &insn->stack_ops, list) { | |
2411 | ||
2412 | if (update_cfi_state(insn, &state->cfi, op)) | |
2413 | return 1; | |
ab3852ab | 2414 | |
ba08abca PZ |
2415 | if (!insn->alt_group) |
2416 | continue; | |
2417 | ||
65ea47dc JT |
2418 | if (op->dest.type == OP_DEST_PUSHF) { |
2419 | if (!state->uaccess_stack) { | |
2420 | state->uaccess_stack = 1; | |
2421 | } else if (state->uaccess_stack >> 31) { | |
2422 | WARN_FUNC("PUSHF stack exhausted", | |
2423 | insn->sec, insn->offset); | |
2424 | return 1; | |
2425 | } | |
2426 | state->uaccess_stack <<= 1; | |
2427 | state->uaccess_stack |= state->uaccess; | |
2428 | } | |
2429 | ||
2430 | if (op->src.type == OP_SRC_POPF) { | |
2431 | if (state->uaccess_stack) { | |
2432 | state->uaccess = state->uaccess_stack & 1; | |
2433 | state->uaccess_stack >>= 1; | |
2434 | if (state->uaccess_stack == 1) | |
2435 | state->uaccess_stack = 0; | |
2436 | } | |
2437 | } | |
2438 | } | |
2439 | ||
2440 | return 0; | |
2441 | } | |
2442 | ||
e7c0219b | 2443 | static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2) |
baa41469 | 2444 | { |
e7c0219b | 2445 | struct cfi_state *cfi1 = &insn->cfi; |
baa41469 JP |
2446 | int i; |
2447 | ||
e7c0219b PZ |
2448 | if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) { |
2449 | ||
baa41469 JP |
2450 | WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d", |
2451 | insn->sec, insn->offset, | |
e7c0219b PZ |
2452 | cfi1->cfa.base, cfi1->cfa.offset, |
2453 | cfi2->cfa.base, cfi2->cfa.offset); | |
baa41469 | 2454 | |
e7c0219b | 2455 | } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) { |
baa41469 | 2456 | for (i = 0; i < CFI_NUM_REGS; i++) { |
e7c0219b | 2457 | if (!memcmp(&cfi1->regs[i], &cfi2->regs[i], |
baa41469 JP |
2458 | sizeof(struct cfi_reg))) |
2459 | continue; | |
2460 | ||
2461 | WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d", | |
2462 | insn->sec, insn->offset, | |
e7c0219b PZ |
2463 | i, cfi1->regs[i].base, cfi1->regs[i].offset, |
2464 | i, cfi2->regs[i].base, cfi2->regs[i].offset); | |
baa41469 JP |
2465 | break; |
2466 | } | |
2467 | ||
e7c0219b PZ |
2468 | } else if (cfi1->type != cfi2->type) { |
2469 | ||
627fce14 | 2470 | WARN_FUNC("stack state mismatch: type1=%d type2=%d", |
e7c0219b PZ |
2471 | insn->sec, insn->offset, cfi1->type, cfi2->type); |
2472 | ||
2473 | } else if (cfi1->drap != cfi2->drap || | |
2474 | (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) || | |
2475 | (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) { | |
627fce14 | 2476 | |
bf4d1a83 | 2477 | WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)", |
baa41469 | 2478 | insn->sec, insn->offset, |
e7c0219b PZ |
2479 | cfi1->drap, cfi1->drap_reg, cfi1->drap_offset, |
2480 | cfi2->drap, cfi2->drap_reg, cfi2->drap_offset); | |
baa41469 JP |
2481 | |
2482 | } else | |
2483 | return true; | |
2484 | ||
2485 | return false; | |
dcc914f4 JP |
2486 | } |
2487 | ||
ea24213d PZ |
2488 | static inline bool func_uaccess_safe(struct symbol *func) |
2489 | { | |
2490 | if (func) | |
e10cd8fe | 2491 | return func->uaccess_safe; |
ea24213d PZ |
2492 | |
2493 | return false; | |
2494 | } | |
2495 | ||
0c1ddd33 | 2496 | static inline const char *call_dest_name(struct instruction *insn) |
ea24213d PZ |
2497 | { |
2498 | if (insn->call_dest) | |
2499 | return insn->call_dest->name; | |
2500 | ||
2501 | return "{dynamic}"; | |
2502 | } | |
2503 | ||
6b643a07 PZ |
2504 | static inline bool noinstr_call_dest(struct symbol *func) |
2505 | { | |
2506 | /* | |
2507 | * We can't deal with indirect function calls at present; | |
2508 | * assume they're instrumented. | |
2509 | */ | |
2510 | if (!func) | |
2511 | return false; | |
2512 | ||
2513 | /* | |
2514 | * If the symbol is from a noinstr section; we good. | |
2515 | */ | |
2516 | if (func->sec->noinstr) | |
2517 | return true; | |
2518 | ||
2519 | /* | |
2520 | * The __ubsan_handle_*() calls are like WARN(), they only happen when | |
2521 | * something 'BAD' happened. At the risk of taking the machine down, | |
2522 | * let them proceed to get the message out. | |
2523 | */ | |
2524 | if (!strncmp(func->name, "__ubsan_handle_", 15)) | |
2525 | return true; | |
2526 | ||
2527 | return false; | |
2528 | } | |
2529 | ||
ea24213d PZ |
2530 | static int validate_call(struct instruction *insn, struct insn_state *state) |
2531 | { | |
c4a33939 | 2532 | if (state->noinstr && state->instr <= 0 && |
6b643a07 | 2533 | !noinstr_call_dest(insn->call_dest)) { |
c4a33939 PZ |
2534 | WARN_FUNC("call to %s() leaves .noinstr.text section", |
2535 | insn->sec, insn->offset, call_dest_name(insn)); | |
2536 | return 1; | |
2537 | } | |
2538 | ||
ea24213d PZ |
2539 | if (state->uaccess && !func_uaccess_safe(insn->call_dest)) { |
2540 | WARN_FUNC("call to %s() with UACCESS enabled", | |
0c1ddd33 | 2541 | insn->sec, insn->offset, call_dest_name(insn)); |
ea24213d PZ |
2542 | return 1; |
2543 | } | |
2544 | ||
2f0f9e9a PZ |
2545 | if (state->df) { |
2546 | WARN_FUNC("call to %s() with DF set", | |
0c1ddd33 | 2547 | insn->sec, insn->offset, call_dest_name(insn)); |
2f0f9e9a PZ |
2548 | return 1; |
2549 | } | |
2550 | ||
ea24213d PZ |
2551 | return 0; |
2552 | } | |
2553 | ||
54262aa2 PZ |
2554 | static int validate_sibling_call(struct instruction *insn, struct insn_state *state) |
2555 | { | |
e25eea89 | 2556 | if (has_modified_stack_frame(insn, state)) { |
54262aa2 PZ |
2557 | WARN_FUNC("sibling call from callable instruction with modified stack frame", |
2558 | insn->sec, insn->offset); | |
2559 | return 1; | |
2560 | } | |
2561 | ||
ea24213d | 2562 | return validate_call(insn, state); |
54262aa2 PZ |
2563 | } |
2564 | ||
a92e92d1 PZ |
2565 | static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state) |
2566 | { | |
c4a33939 PZ |
2567 | if (state->noinstr && state->instr > 0) { |
2568 | WARN_FUNC("return with instrumentation enabled", | |
2569 | insn->sec, insn->offset); | |
2570 | return 1; | |
2571 | } | |
2572 | ||
a92e92d1 PZ |
2573 | if (state->uaccess && !func_uaccess_safe(func)) { |
2574 | WARN_FUNC("return with UACCESS enabled", | |
2575 | insn->sec, insn->offset); | |
2576 | return 1; | |
2577 | } | |
2578 | ||
2579 | if (!state->uaccess && func_uaccess_safe(func)) { | |
2580 | WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function", | |
2581 | insn->sec, insn->offset); | |
2582 | return 1; | |
2583 | } | |
2584 | ||
2585 | if (state->df) { | |
2586 | WARN_FUNC("return with DF set", | |
2587 | insn->sec, insn->offset); | |
2588 | return 1; | |
2589 | } | |
2590 | ||
e25eea89 | 2591 | if (func && has_modified_stack_frame(insn, state)) { |
a92e92d1 PZ |
2592 | WARN_FUNC("return with modified stack frame", |
2593 | insn->sec, insn->offset); | |
2594 | return 1; | |
2595 | } | |
2596 | ||
e7c0219b | 2597 | if (state->cfi.bp_scratch) { |
b2966952 JP |
2598 | WARN_FUNC("BP used as a scratch register", |
2599 | insn->sec, insn->offset); | |
a92e92d1 PZ |
2600 | return 1; |
2601 | } | |
2602 | ||
2603 | return 0; | |
2604 | } | |
2605 | ||
c9c324dc JP |
2606 | static struct instruction *next_insn_to_validate(struct objtool_file *file, |
2607 | struct instruction *insn) | |
7117f16b | 2608 | { |
b23cc71c | 2609 | struct alt_group *alt_group = insn->alt_group; |
7117f16b | 2610 | |
c9c324dc JP |
2611 | /* |
2612 | * Simulate the fact that alternatives are patched in-place. When the | |
2613 | * end of a replacement alt_group is reached, redirect objtool flow to | |
2614 | * the end of the original alt_group. | |
2615 | */ | |
2616 | if (alt_group && insn == alt_group->last_insn && alt_group->orig_group) | |
2617 | return next_insn_same_sec(file, alt_group->orig_group->last_insn); | |
2618 | ||
2619 | return next_insn_same_sec(file, insn); | |
7117f16b PZ |
2620 | } |
2621 | ||
dcc914f4 JP |
2622 | /* |
2623 | * Follow the branch starting at the given instruction, and recursively follow | |
2624 | * any other branches (jumps). Meanwhile, track the frame pointer state at | |
2625 | * each instruction and validate all the rules described in | |
2626 | * tools/objtool/Documentation/stack-validation.txt. | |
2627 | */ | |
c705cecc | 2628 | static int validate_branch(struct objtool_file *file, struct symbol *func, |
b7460462 | 2629 | struct instruction *insn, struct insn_state state) |
dcc914f4 JP |
2630 | { |
2631 | struct alternative *alt; | |
b7460462 | 2632 | struct instruction *next_insn; |
dcc914f4 | 2633 | struct section *sec; |
882a0db9 | 2634 | u8 visited; |
dcc914f4 JP |
2635 | int ret; |
2636 | ||
dcc914f4 | 2637 | sec = insn->sec; |
dcc914f4 | 2638 | |
dcc914f4 | 2639 | while (1) { |
c9c324dc | 2640 | next_insn = next_insn_to_validate(file, insn); |
39358a03 | 2641 | |
13810435 | 2642 | if (file->c_file && func && insn->func && func != insn->func->pfunc) { |
ee97638b JP |
2643 | WARN("%s() falls through to next function %s()", |
2644 | func->name, insn->func->name); | |
2645 | return 1; | |
dcc914f4 JP |
2646 | } |
2647 | ||
4855022a JP |
2648 | if (func && insn->ignore) { |
2649 | WARN_FUNC("BUG: why am I validating an ignored function?", | |
2650 | sec, insn->offset); | |
12b25729 | 2651 | return 1; |
4855022a JP |
2652 | } |
2653 | ||
882a0db9 | 2654 | visited = 1 << state.uaccess; |
dcc914f4 | 2655 | if (insn->visited) { |
e7c0219b | 2656 | if (!insn->hint && !insn_cfi_match(insn, &state.cfi)) |
dcc914f4 | 2657 | return 1; |
dcc914f4 | 2658 | |
882a0db9 | 2659 | if (insn->visited & visited) |
ea24213d | 2660 | return 0; |
dcc914f4 JP |
2661 | } |
2662 | ||
c4a33939 PZ |
2663 | if (state.noinstr) |
2664 | state.instr += insn->instr; | |
2665 | ||
c536ed2f | 2666 | if (insn->hint) |
e7c0219b | 2667 | state.cfi = insn->cfi; |
c536ed2f | 2668 | else |
e7c0219b | 2669 | insn->cfi = state.cfi; |
dcc914f4 | 2670 | |
882a0db9 | 2671 | insn->visited |= visited; |
baa41469 | 2672 | |
c9c324dc JP |
2673 | if (propagate_alt_cfi(file, insn)) |
2674 | return 1; | |
2675 | ||
7117f16b | 2676 | if (!insn->ignore_alts && !list_empty(&insn->alts)) { |
764eef4b PZ |
2677 | bool skip_orig = false; |
2678 | ||
a845c7cf | 2679 | list_for_each_entry(alt, &insn->alts, list) { |
764eef4b PZ |
2680 | if (alt->skip_orig) |
2681 | skip_orig = true; | |
2682 | ||
c705cecc | 2683 | ret = validate_branch(file, func, alt->insn, state); |
7697eee3 PZ |
2684 | if (ret) { |
2685 | if (backtrace) | |
2686 | BT_FUNC("(alt)", insn); | |
2687 | return ret; | |
2688 | } | |
a845c7cf | 2689 | } |
764eef4b PZ |
2690 | |
2691 | if (skip_orig) | |
2692 | return 0; | |
dcc914f4 JP |
2693 | } |
2694 | ||
60041bcd PZ |
2695 | if (handle_insn_ops(insn, &state)) |
2696 | return 1; | |
2697 | ||
dcc914f4 JP |
2698 | switch (insn->type) { |
2699 | ||
dcc914f4 | 2700 | case INSN_RETURN: |
a92e92d1 | 2701 | return validate_return(func, insn, &state); |
dcc914f4 JP |
2702 | |
2703 | case INSN_CALL: | |
ea24213d PZ |
2704 | case INSN_CALL_DYNAMIC: |
2705 | ret = validate_call(insn, &state); | |
2706 | if (ret) | |
2707 | return ret; | |
dcc914f4 | 2708 | |
c9bab22b JP |
2709 | if (!no_fp && func && !is_fentry_call(insn) && |
2710 | !has_valid_stack_frame(&state)) { | |
dcc914f4 JP |
2711 | WARN_FUNC("call without frame pointer save/setup", |
2712 | sec, insn->offset); | |
2713 | return 1; | |
2714 | } | |
c9bab22b JP |
2715 | |
2716 | if (dead_end_function(file, insn->call_dest)) | |
2717 | return 0; | |
2718 | ||
dcc914f4 JP |
2719 | break; |
2720 | ||
2721 | case INSN_JUMP_CONDITIONAL: | |
2722 | case INSN_JUMP_UNCONDITIONAL: | |
ecf11ba4 | 2723 | if (is_sibling_call(insn)) { |
54262aa2 | 2724 | ret = validate_sibling_call(insn, &state); |
dcc914f4 | 2725 | if (ret) |
54262aa2 | 2726 | return ret; |
4855022a | 2727 | |
0c1ddd33 | 2728 | } else if (insn->jump_dest) { |
c705cecc JP |
2729 | ret = validate_branch(file, func, |
2730 | insn->jump_dest, state); | |
7697eee3 PZ |
2731 | if (ret) { |
2732 | if (backtrace) | |
2733 | BT_FUNC("(branch)", insn); | |
2734 | return ret; | |
2735 | } | |
4855022a | 2736 | } |
dcc914f4 JP |
2737 | |
2738 | if (insn->type == INSN_JUMP_UNCONDITIONAL) | |
2739 | return 0; | |
2740 | ||
2741 | break; | |
2742 | ||
2743 | case INSN_JUMP_DYNAMIC: | |
b68b9907 | 2744 | case INSN_JUMP_DYNAMIC_CONDITIONAL: |
ecf11ba4 | 2745 | if (is_sibling_call(insn)) { |
54262aa2 PZ |
2746 | ret = validate_sibling_call(insn, &state); |
2747 | if (ret) | |
2748 | return ret; | |
dcc914f4 JP |
2749 | } |
2750 | ||
b68b9907 JP |
2751 | if (insn->type == INSN_JUMP_DYNAMIC) |
2752 | return 0; | |
2753 | ||
2754 | break; | |
dcc914f4 | 2755 | |
39358a03 JP |
2756 | case INSN_CONTEXT_SWITCH: |
2757 | if (func && (!next_insn || !next_insn->hint)) { | |
2758 | WARN_FUNC("unsupported instruction in callable function", | |
2759 | sec, insn->offset); | |
2760 | return 1; | |
2761 | } | |
2762 | return 0; | |
2763 | ||
ea24213d PZ |
2764 | case INSN_STAC: |
2765 | if (state.uaccess) { | |
2766 | WARN_FUNC("recursive UACCESS enable", sec, insn->offset); | |
2767 | return 1; | |
2768 | } | |
2769 | ||
2770 | state.uaccess = true; | |
2771 | break; | |
2772 | ||
2773 | case INSN_CLAC: | |
c705cecc | 2774 | if (!state.uaccess && func) { |
ea24213d PZ |
2775 | WARN_FUNC("redundant UACCESS disable", sec, insn->offset); |
2776 | return 1; | |
2777 | } | |
2778 | ||
2779 | if (func_uaccess_safe(func) && !state.uaccess_stack) { | |
2780 | WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset); | |
2781 | return 1; | |
2782 | } | |
2783 | ||
2784 | state.uaccess = false; | |
baa41469 JP |
2785 | break; |
2786 | ||
2f0f9e9a | 2787 | case INSN_STD: |
6f567c93 | 2788 | if (state.df) { |
2f0f9e9a | 2789 | WARN_FUNC("recursive STD", sec, insn->offset); |
6f567c93 JP |
2790 | return 1; |
2791 | } | |
2f0f9e9a PZ |
2792 | |
2793 | state.df = true; | |
2794 | break; | |
2795 | ||
2796 | case INSN_CLD: | |
6f567c93 | 2797 | if (!state.df && func) { |
2f0f9e9a | 2798 | WARN_FUNC("redundant CLD", sec, insn->offset); |
6f567c93 JP |
2799 | return 1; |
2800 | } | |
2f0f9e9a PZ |
2801 | |
2802 | state.df = false; | |
baa41469 JP |
2803 | break; |
2804 | ||
dcc914f4 JP |
2805 | default: |
2806 | break; | |
2807 | } | |
2808 | ||
2809 | if (insn->dead_end) | |
2810 | return 0; | |
2811 | ||
00d96180 | 2812 | if (!next_insn) { |
e7c0219b | 2813 | if (state.cfi.cfa.base == CFI_UNDEFINED) |
00d96180 | 2814 | return 0; |
dcc914f4 JP |
2815 | WARN("%s: unexpected end of section", sec->name); |
2816 | return 1; | |
2817 | } | |
00d96180 JP |
2818 | |
2819 | insn = next_insn; | |
dcc914f4 JP |
2820 | } |
2821 | ||
2822 | return 0; | |
2823 | } | |
2824 | ||
932f8e98 | 2825 | static int validate_unwind_hints(struct objtool_file *file, struct section *sec) |
39358a03 JP |
2826 | { |
2827 | struct instruction *insn; | |
39358a03 | 2828 | struct insn_state state; |
932f8e98 | 2829 | int ret, warnings = 0; |
39358a03 JP |
2830 | |
2831 | if (!file->hints) | |
2832 | return 0; | |
2833 | ||
932f8e98 | 2834 | init_insn_state(&state, sec); |
39358a03 | 2835 | |
932f8e98 PZ |
2836 | if (sec) { |
2837 | insn = find_insn(file, sec, 0); | |
2838 | if (!insn) | |
2839 | return 0; | |
2840 | } else { | |
2841 | insn = list_first_entry(&file->insn_list, typeof(*insn), list); | |
2842 | } | |
2843 | ||
2844 | while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) { | |
39358a03 | 2845 | if (insn->hint && !insn->visited) { |
c705cecc | 2846 | ret = validate_branch(file, insn->func, insn, state); |
7697eee3 PZ |
2847 | if (ret && backtrace) |
2848 | BT_FUNC("<=== (hint)", insn); | |
39358a03 JP |
2849 | warnings += ret; |
2850 | } | |
932f8e98 PZ |
2851 | |
2852 | insn = list_next_entry(insn, list); | |
39358a03 JP |
2853 | } |
2854 | ||
2855 | return warnings; | |
2856 | } | |
2857 | ||
b5bc2231 PZ |
2858 | static int validate_retpoline(struct objtool_file *file) |
2859 | { | |
2860 | struct instruction *insn; | |
2861 | int warnings = 0; | |
2862 | ||
2863 | for_each_insn(file, insn) { | |
2864 | if (insn->type != INSN_JUMP_DYNAMIC && | |
2865 | insn->type != INSN_CALL_DYNAMIC) | |
2866 | continue; | |
2867 | ||
2868 | if (insn->retpoline_safe) | |
2869 | continue; | |
2870 | ||
ca41b97e PZ |
2871 | /* |
2872 | * .init.text code is ran before userspace and thus doesn't | |
2873 | * strictly need retpolines, except for modules which are | |
2874 | * loaded late, they very much do need retpoline in their | |
2875 | * .init.text | |
2876 | */ | |
2877 | if (!strcmp(insn->sec->name, ".init.text") && !module) | |
2878 | continue; | |
2879 | ||
b5bc2231 PZ |
2880 | WARN_FUNC("indirect %s found in RETPOLINE build", |
2881 | insn->sec, insn->offset, | |
2882 | insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call"); | |
2883 | ||
2884 | warnings++; | |
2885 | } | |
2886 | ||
2887 | return warnings; | |
2888 | } | |
2889 | ||
dcc914f4 JP |
2890 | static bool is_kasan_insn(struct instruction *insn) |
2891 | { | |
2892 | return (insn->type == INSN_CALL && | |
2893 | !strcmp(insn->call_dest->name, "__asan_handle_no_return")); | |
2894 | } | |
2895 | ||
2896 | static bool is_ubsan_insn(struct instruction *insn) | |
2897 | { | |
2898 | return (insn->type == INSN_CALL && | |
2899 | !strcmp(insn->call_dest->name, | |
2900 | "__ubsan_handle_builtin_unreachable")); | |
2901 | } | |
2902 | ||
14db1f0a | 2903 | static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn) |
dcc914f4 JP |
2904 | { |
2905 | int i; | |
14db1f0a | 2906 | struct instruction *prev_insn; |
dcc914f4 | 2907 | |
baa41469 JP |
2908 | if (insn->ignore || insn->type == INSN_NOP) |
2909 | return true; | |
2910 | ||
2911 | /* | |
2912 | * Ignore any unused exceptions. This can happen when a whitelisted | |
2913 | * function has an exception table entry. | |
0e2bb2bc JP |
2914 | * |
2915 | * Also ignore alternative replacement instructions. This can happen | |
2916 | * when a whitelisted function uses one of the ALTERNATIVE macros. | |
baa41469 | 2917 | */ |
0e2bb2bc JP |
2918 | if (!strcmp(insn->sec->name, ".fixup") || |
2919 | !strcmp(insn->sec->name, ".altinstr_replacement") || | |
2920 | !strcmp(insn->sec->name, ".altinstr_aux")) | |
dcc914f4 JP |
2921 | return true; |
2922 | ||
bd841d61 JP |
2923 | if (!insn->func) |
2924 | return false; | |
2925 | ||
2926 | /* | |
2927 | * CONFIG_UBSAN_TRAP inserts a UD2 when it sees | |
2928 | * __builtin_unreachable(). The BUG() macro has an unreachable() after | |
2929 | * the UD2, which causes GCC's undefined trap logic to emit another UD2 | |
2930 | * (or occasionally a JMP to UD2). | |
14db1f0a IH |
2931 | * |
2932 | * It may also insert a UD2 after calling a __noreturn function. | |
bd841d61 | 2933 | */ |
14db1f0a IH |
2934 | prev_insn = list_prev_entry(insn, list); |
2935 | if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) && | |
bd841d61 JP |
2936 | (insn->type == INSN_BUG || |
2937 | (insn->type == INSN_JUMP_UNCONDITIONAL && | |
2938 | insn->jump_dest && insn->jump_dest->type == INSN_BUG))) | |
2939 | return true; | |
2940 | ||
dcc914f4 JP |
2941 | /* |
2942 | * Check if this (or a subsequent) instruction is related to | |
2943 | * CONFIG_UBSAN or CONFIG_KASAN. | |
2944 | * | |
2945 | * End the search at 5 instructions to avoid going into the weeds. | |
2946 | */ | |
2947 | for (i = 0; i < 5; i++) { | |
2948 | ||
2949 | if (is_kasan_insn(insn) || is_ubsan_insn(insn)) | |
2950 | return true; | |
2951 | ||
fe24e271 JP |
2952 | if (insn->type == INSN_JUMP_UNCONDITIONAL) { |
2953 | if (insn->jump_dest && | |
2954 | insn->jump_dest->func == insn->func) { | |
2955 | insn = insn->jump_dest; | |
2956 | continue; | |
2957 | } | |
2958 | ||
2959 | break; | |
dcc914f4 JP |
2960 | } |
2961 | ||
baa41469 | 2962 | if (insn->offset + insn->len >= insn->func->offset + insn->func->len) |
dcc914f4 | 2963 | break; |
fe24e271 | 2964 | |
dcc914f4 JP |
2965 | insn = list_next_entry(insn, list); |
2966 | } | |
2967 | ||
2968 | return false; | |
2969 | } | |
2970 | ||
4b5e2e7f PZ |
2971 | static int validate_symbol(struct objtool_file *file, struct section *sec, |
2972 | struct symbol *sym, struct insn_state *state) | |
dcc914f4 | 2973 | { |
dcc914f4 | 2974 | struct instruction *insn; |
4b5e2e7f PZ |
2975 | int ret; |
2976 | ||
2977 | if (!sym->len) { | |
2978 | WARN("%s() is missing an ELF size annotation", sym->name); | |
2979 | return 1; | |
2980 | } | |
2981 | ||
2982 | if (sym->pfunc != sym || sym->alias != sym) | |
2983 | return 0; | |
2984 | ||
2985 | insn = find_insn(file, sec, sym->offset); | |
2986 | if (!insn || insn->ignore || insn->visited) | |
2987 | return 0; | |
2988 | ||
2989 | state->uaccess = sym->uaccess_safe; | |
2990 | ||
2991 | ret = validate_branch(file, insn->func, insn, *state); | |
2992 | if (ret && backtrace) | |
2993 | BT_FUNC("<=== (sym)", insn); | |
2994 | return ret; | |
2995 | } | |
2996 | ||
2997 | static int validate_section(struct objtool_file *file, struct section *sec) | |
2998 | { | |
baa41469 | 2999 | struct insn_state state; |
4b5e2e7f PZ |
3000 | struct symbol *func; |
3001 | int warnings = 0; | |
dcc914f4 | 3002 | |
350994bf PZ |
3003 | list_for_each_entry(func, &sec->symbol_list, list) { |
3004 | if (func->type != STT_FUNC) | |
3005 | continue; | |
e10cd8fe | 3006 | |
932f8e98 | 3007 | init_insn_state(&state, sec); |
b735bd3e | 3008 | set_func_state(&state.cfi); |
0699e551 | 3009 | |
4b5e2e7f | 3010 | warnings += validate_symbol(file, sec, func, &state); |
dcc914f4 JP |
3011 | } |
3012 | ||
dcc914f4 JP |
3013 | return warnings; |
3014 | } | |
3015 | ||
c4a33939 PZ |
3016 | static int validate_vmlinux_functions(struct objtool_file *file) |
3017 | { | |
3018 | struct section *sec; | |
932f8e98 | 3019 | int warnings = 0; |
c4a33939 PZ |
3020 | |
3021 | sec = find_section_by_name(file->elf, ".noinstr.text"); | |
0cc9ac8d TG |
3022 | if (sec) { |
3023 | warnings += validate_section(file, sec); | |
3024 | warnings += validate_unwind_hints(file, sec); | |
3025 | } | |
c4a33939 | 3026 | |
0cc9ac8d TG |
3027 | sec = find_section_by_name(file->elf, ".entry.text"); |
3028 | if (sec) { | |
3029 | warnings += validate_section(file, sec); | |
3030 | warnings += validate_unwind_hints(file, sec); | |
3031 | } | |
932f8e98 PZ |
3032 | |
3033 | return warnings; | |
c4a33939 PZ |
3034 | } |
3035 | ||
350994bf PZ |
3036 | static int validate_functions(struct objtool_file *file) |
3037 | { | |
3038 | struct section *sec; | |
3039 | int warnings = 0; | |
3040 | ||
da837bd6 PZ |
3041 | for_each_sec(file, sec) { |
3042 | if (!(sec->sh.sh_flags & SHF_EXECINSTR)) | |
3043 | continue; | |
3044 | ||
350994bf | 3045 | warnings += validate_section(file, sec); |
da837bd6 | 3046 | } |
350994bf PZ |
3047 | |
3048 | return warnings; | |
3049 | } | |
3050 | ||
baa41469 | 3051 | static int validate_reachable_instructions(struct objtool_file *file) |
dcc914f4 JP |
3052 | { |
3053 | struct instruction *insn; | |
baa41469 JP |
3054 | |
3055 | if (file->ignore_unreachables) | |
3056 | return 0; | |
dcc914f4 JP |
3057 | |
3058 | for_each_insn(file, insn) { | |
14db1f0a | 3059 | if (insn->visited || ignore_unreachable_insn(file, insn)) |
baa41469 JP |
3060 | continue; |
3061 | ||
baa41469 JP |
3062 | WARN_FUNC("unreachable instruction", insn->sec, insn->offset); |
3063 | return 1; | |
dcc914f4 JP |
3064 | } |
3065 | ||
baa41469 | 3066 | return 0; |
dcc914f4 JP |
3067 | } |
3068 | ||
d44becb9 | 3069 | int check(struct objtool_file *file) |
dcc914f4 | 3070 | { |
dcc914f4 JP |
3071 | int ret, warnings = 0; |
3072 | ||
baa41469 JP |
3073 | arch_initial_func_cfi_state(&initial_func_cfi); |
3074 | ||
6545eb03 | 3075 | ret = decode_sections(file); |
dcc914f4 JP |
3076 | if (ret < 0) |
3077 | goto out; | |
3078 | warnings += ret; | |
3079 | ||
6545eb03 | 3080 | if (list_empty(&file->insn_list)) |
dcc914f4 | 3081 | goto out; |
dcc914f4 | 3082 | |
c4a33939 | 3083 | if (vmlinux && !validate_dup) { |
6545eb03 | 3084 | ret = validate_vmlinux_functions(file); |
c4a33939 PZ |
3085 | if (ret < 0) |
3086 | goto out; | |
3087 | ||
3088 | warnings += ret; | |
3089 | goto out; | |
3090 | } | |
3091 | ||
b5bc2231 | 3092 | if (retpoline) { |
6545eb03 | 3093 | ret = validate_retpoline(file); |
b5bc2231 PZ |
3094 | if (ret < 0) |
3095 | return ret; | |
3096 | warnings += ret; | |
3097 | } | |
3098 | ||
6545eb03 | 3099 | ret = validate_functions(file); |
dcc914f4 JP |
3100 | if (ret < 0) |
3101 | goto out; | |
3102 | warnings += ret; | |
3103 | ||
6545eb03 | 3104 | ret = validate_unwind_hints(file, NULL); |
39358a03 JP |
3105 | if (ret < 0) |
3106 | goto out; | |
3107 | warnings += ret; | |
3108 | ||
baa41469 | 3109 | if (!warnings) { |
6545eb03 | 3110 | ret = validate_reachable_instructions(file); |
baa41469 JP |
3111 | if (ret < 0) |
3112 | goto out; | |
3113 | warnings += ret; | |
3114 | } | |
3115 | ||
6545eb03 | 3116 | ret = create_static_call_sections(file); |
1e7e4788 JP |
3117 | if (ret < 0) |
3118 | goto out; | |
3119 | warnings += ret; | |
3120 | ||
99d00215 PZ |
3121 | if (mcount) { |
3122 | ret = create_mcount_loc_sections(file); | |
3123 | if (ret < 0) | |
3124 | goto out; | |
3125 | warnings += ret; | |
3126 | } | |
3127 | ||
dcc914f4 | 3128 | out: |
655cf865 JP |
3129 | /* |
3130 | * For now, don't fail the kernel build on fatal warnings. These | |
3131 | * errors are still fairly common due to the growing matrix of | |
3132 | * supported toolchains and their recent pace of change. | |
3133 | */ | |
dcc914f4 JP |
3134 | return 0; |
3135 | } |