1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Post mortem Dwarf CFI based unwinding on top of regs and stack dumps. 4 * 5 * Lots of this code have been borrowed or heavily inspired from parts of 6 * the libunwind 0.99 code which are (amongst other contributors I may have 7 * forgotten): 8 * 9 * Copyright (C) 2002-2007 Hewlett-Packard Co 10 * Contributed by David Mosberger-Tang <davidm@hpl.hp.com> 11 * 12 * And the bugs have been added by: 13 * 14 * Copyright (C) 2010, Frederic Weisbecker <fweisbec@gmail.com> 15 * Copyright (C) 2012, Jiri Olsa <jolsa@redhat.com> 16 * 17 */ 18 19 #include <elf.h> 20 #include <errno.h> 21 #include <gelf.h> 22 #include <fcntl.h> 23 #include <inttypes.h> 24 #include <string.h> 25 #include <unistd.h> 26 #include <sys/mman.h> 27 #include <linux/list.h> 28 #include <linux/zalloc.h> 29 #ifndef REMOTE_UNWIND_LIBUNWIND 30 #include <libunwind.h> 31 #include <libunwind-ptrace.h> 32 #endif 33 #include "callchain.h" 34 #include "thread.h" 35 #include "session.h" 36 #include "perf_regs.h" 37 #include "unwind.h" 38 #include "map.h" 39 #include "symbol.h" 40 #include "debug.h" 41 #include "asm/bug.h" 42 #include "dso.h" 43 44 extern int 45 UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as, 46 unw_word_t ip, 47 unw_dyn_info_t *di, 48 unw_proc_info_t *pi, 49 int need_unwind_info, void *arg); 50 51 #define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table) 52 53 extern int 54 UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug, 55 unw_word_t ip, 56 unw_word_t segbase, 57 const char *obj_name, unw_word_t start, 58 unw_word_t end); 59 60 #define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame) 61 62 #define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */ 63 #define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */ 64 65 /* Pointer-encoding formats: */ 66 #define DW_EH_PE_omit 0xff 67 #define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */ 68 #define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */ 69 #define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */ 70 #define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */ 71 #define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */ 72 73 /* Pointer-encoding application: */ 74 #define DW_EH_PE_absptr 0x00 /* absolute value */ 75 #define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */ 76 77 /* 78 * The following are not documented by LSB v1.3, yet they are used by 79 * GCC, presumably they aren't documented by LSB since they aren't 80 * used on Linux: 81 */ 82 #define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */ 83 #define DW_EH_PE_aligned 0x50 /* aligned pointer */ 84 85 /* Flags intentionally not handled, since they're not needed: 86 * #define DW_EH_PE_indirect 0x80 87 * #define DW_EH_PE_uleb128 0x01 88 * #define DW_EH_PE_udata2 0x02 89 * #define DW_EH_PE_sleb128 0x09 90 * #define DW_EH_PE_sdata2 0x0a 91 * #define DW_EH_PE_textrel 0x20 92 * #define DW_EH_PE_datarel 0x30 93 */ 94 95 struct unwind_info { 96 struct perf_sample *sample; 97 struct machine *machine; 98 struct thread *thread; 99 bool best_effort; 100 }; 101 102 #define dw_read(ptr, type, end) ({ \ 103 type *__p = (type *) ptr; \ 104 type __v; \ 105 if ((__p + 1) > (type *) end) \ 106 return -EINVAL; \ 107 __v = *__p++; \ 108 ptr = (typeof(ptr)) __p; \ 109 __v; \ 110 }) 111 112 static int __dw_read_encoded_value(u8 **p, u8 *end, u64 *val, 113 u8 encoding) 114 { 115 u8 *cur = *p; 116 *val = 0; 117 118 switch (encoding) { 119 case DW_EH_PE_omit: 120 *val = 0; 121 goto out; 122 case DW_EH_PE_ptr: 123 *val = dw_read(cur, unsigned long, end); 124 goto out; 125 default: 126 break; 127 } 128 129 switch (encoding & DW_EH_PE_APPL_MASK) { 130 case DW_EH_PE_absptr: 131 break; 132 case DW_EH_PE_pcrel: 133 *val = (unsigned long) cur; 134 break; 135 default: 136 return -EINVAL; 137 } 138 139 if ((encoding & 0x07) == 0x00) 140 encoding |= DW_EH_PE_udata4; 141 142 switch (encoding & DW_EH_PE_FORMAT_MASK) { 143 case DW_EH_PE_sdata4: 144 *val += dw_read(cur, s32, end); 145 break; 146 case DW_EH_PE_udata4: 147 *val += dw_read(cur, u32, end); 148 break; 149 case DW_EH_PE_sdata8: 150 *val += dw_read(cur, s64, end); 151 break; 152 case DW_EH_PE_udata8: 153 *val += dw_read(cur, u64, end); 154 break; 155 default: 156 return -EINVAL; 157 } 158 159 out: 160 *p = cur; 161 return 0; 162 } 163 164 #define dw_read_encoded_value(ptr, end, enc) ({ \ 165 u64 __v; \ 166 if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \ 167 return -EINVAL; \ 168 } \ 169 __v; \ 170 }) 171 172 static int elf_section_address_and_offset(int fd, const char *name, u64 *address, u64 *offset) 173 { 174 Elf *elf; 175 GElf_Ehdr ehdr; 176 GElf_Shdr shdr; 177 int ret = -1; 178 179 elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); 180 if (elf == NULL) 181 return -1; 182 183 if (gelf_getehdr(elf, &ehdr) == NULL) 184 goto out_err; 185 186 if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL)) 187 goto out_err; 188 189 *address = shdr.sh_addr; 190 *offset = shdr.sh_offset; 191 ret = 0; 192 out_err: 193 elf_end(elf); 194 return ret; 195 } 196 197 #ifndef NO_LIBUNWIND_DEBUG_FRAME 198 static u64 elf_section_offset(int fd, const char *name) 199 { 200 u64 address, offset = 0; 201 202 if (elf_section_address_and_offset(fd, name, &address, &offset)) 203 return 0; 204 205 return offset; 206 } 207 #endif 208 209 static u64 elf_base_address(int fd) 210 { 211 Elf *elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); 212 GElf_Phdr phdr; 213 u64 retval = 0; 214 size_t i, phdrnum = 0; 215 216 if (elf == NULL) 217 return 0; 218 (void)elf_getphdrnum(elf, &phdrnum); 219 /* PT_LOAD segments are sorted by p_vaddr, so the first has the minimum p_vaddr. */ 220 for (i = 0; i < phdrnum; i++) { 221 if (gelf_getphdr(elf, i, &phdr) && phdr.p_type == PT_LOAD) { 222 retval = phdr.p_vaddr & -getpagesize(); 223 break; 224 } 225 } 226 227 elf_end(elf); 228 return retval; 229 } 230 231 #ifndef NO_LIBUNWIND_DEBUG_FRAME 232 static int elf_is_exec(int fd, const char *name) 233 { 234 Elf *elf; 235 GElf_Ehdr ehdr; 236 int retval = 0; 237 238 elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); 239 if (elf == NULL) 240 return 0; 241 if (gelf_getehdr(elf, &ehdr) == NULL) 242 goto out; 243 244 retval = (ehdr.e_type == ET_EXEC); 245 246 out: 247 elf_end(elf); 248 pr_debug("unwind: elf_is_exec(%s): %d\n", name, retval); 249 return retval; 250 } 251 #endif 252 253 struct table_entry { 254 u32 start_ip_offset; 255 u32 fde_offset; 256 }; 257 258 struct eh_frame_hdr { 259 unsigned char version; 260 unsigned char eh_frame_ptr_enc; 261 unsigned char fde_count_enc; 262 unsigned char table_enc; 263 264 /* 265 * The rest of the header is variable-length and consists of the 266 * following members: 267 * 268 * encoded_t eh_frame_ptr; 269 * encoded_t fde_count; 270 */ 271 272 /* A single encoded pointer should not be more than 8 bytes. */ 273 u64 enc[2]; 274 275 /* 276 * struct { 277 * encoded_t start_ip; 278 * encoded_t fde_addr; 279 * } binary_search_table[fde_count]; 280 */ 281 char data[]; 282 } __packed; 283 284 static int unwind_spec_ehframe(struct dso *dso, struct machine *machine, 285 u64 offset, u64 *table_data_offset, u64 *fde_count) 286 { 287 struct eh_frame_hdr hdr; 288 u8 *enc = (u8 *) &hdr.enc; 289 u8 *end = (u8 *) &hdr.data; 290 ssize_t r; 291 292 r = dso__data_read_offset(dso, machine, offset, 293 (u8 *) &hdr, sizeof(hdr)); 294 if (r != sizeof(hdr)) 295 return -EINVAL; 296 297 /* We dont need eh_frame_ptr, just skip it. */ 298 dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc); 299 300 *fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc); 301 *table_data_offset = enc - (u8 *) &hdr; 302 return 0; 303 } 304 305 static int read_unwind_spec_eh_frame(struct dso *dso, struct unwind_info *ui, 306 u64 *table_data, u64 *segbase, 307 u64 *fde_count) 308 { 309 struct map_rb_node *map_node; 310 u64 base_addr = UINT64_MAX; 311 int ret, fd; 312 313 if (dso->data.eh_frame_hdr_offset == 0) { 314 fd = dso__data_get_fd(dso, ui->machine); 315 if (fd < 0) 316 return -EINVAL; 317 318 /* Check the .eh_frame section for unwinding info */ 319 ret = elf_section_address_and_offset(fd, ".eh_frame_hdr", 320 &dso->data.eh_frame_hdr_addr, 321 &dso->data.eh_frame_hdr_offset); 322 dso->data.elf_base_addr = elf_base_address(fd); 323 dso__data_put_fd(dso); 324 if (ret || dso->data.eh_frame_hdr_offset == 0) 325 return -EINVAL; 326 } 327 328 maps__for_each_entry(ui->thread->maps, map_node) { 329 struct map *map = map_node->map; 330 331 if (map__dso(map) == dso && map->start < base_addr) 332 base_addr = map->start; 333 } 334 base_addr -= dso->data.elf_base_addr; 335 /* Address of .eh_frame_hdr */ 336 *segbase = base_addr + dso->data.eh_frame_hdr_addr; 337 ret = unwind_spec_ehframe(dso, ui->machine, dso->data.eh_frame_hdr_offset, 338 table_data, fde_count); 339 if (ret) 340 return ret; 341 /* binary_search_table offset plus .eh_frame_hdr address */ 342 *table_data += *segbase; 343 return 0; 344 } 345 346 #ifndef NO_LIBUNWIND_DEBUG_FRAME 347 static int read_unwind_spec_debug_frame(struct dso *dso, 348 struct machine *machine, u64 *offset) 349 { 350 int fd; 351 u64 ofs = dso->data.debug_frame_offset; 352 353 /* debug_frame can reside in: 354 * - dso 355 * - debug pointed by symsrc_filename 356 * - gnu_debuglink, which doesn't necessary 357 * has to be pointed by symsrc_filename 358 */ 359 if (ofs == 0) { 360 fd = dso__data_get_fd(dso, machine); 361 if (fd >= 0) { 362 ofs = elf_section_offset(fd, ".debug_frame"); 363 dso__data_put_fd(dso); 364 } 365 366 if (ofs <= 0) { 367 fd = open(dso->symsrc_filename, O_RDONLY); 368 if (fd >= 0) { 369 ofs = elf_section_offset(fd, ".debug_frame"); 370 close(fd); 371 } 372 } 373 374 if (ofs <= 0) { 375 char *debuglink = malloc(PATH_MAX); 376 int ret = 0; 377 378 ret = dso__read_binary_type_filename( 379 dso, DSO_BINARY_TYPE__DEBUGLINK, 380 machine->root_dir, debuglink, PATH_MAX); 381 if (!ret) { 382 fd = open(debuglink, O_RDONLY); 383 if (fd >= 0) { 384 ofs = elf_section_offset(fd, 385 ".debug_frame"); 386 close(fd); 387 } 388 } 389 if (ofs > 0) { 390 if (dso->symsrc_filename != NULL) { 391 pr_warning( 392 "%s: overwrite symsrc(%s,%s)\n", 393 __func__, 394 dso->symsrc_filename, 395 debuglink); 396 zfree(&dso->symsrc_filename); 397 } 398 dso->symsrc_filename = debuglink; 399 } else { 400 free(debuglink); 401 } 402 } 403 404 dso->data.debug_frame_offset = ofs; 405 } 406 407 *offset = ofs; 408 if (*offset) 409 return 0; 410 411 return -EINVAL; 412 } 413 #endif 414 415 static struct map *find_map(unw_word_t ip, struct unwind_info *ui) 416 { 417 struct addr_location al; 418 return thread__find_map(ui->thread, PERF_RECORD_MISC_USER, ip, &al); 419 } 420 421 static int 422 find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi, 423 int need_unwind_info, void *arg) 424 { 425 struct unwind_info *ui = arg; 426 struct map *map; 427 struct dso *dso; 428 unw_dyn_info_t di; 429 u64 table_data, segbase, fde_count; 430 int ret = -EINVAL; 431 432 map = find_map(ip, ui); 433 if (!map) 434 return -EINVAL; 435 436 dso = map__dso(map); 437 if (!dso) 438 return -EINVAL; 439 440 pr_debug("unwind: find_proc_info dso %s\n", dso->name); 441 442 /* Check the .eh_frame section for unwinding info */ 443 if (!read_unwind_spec_eh_frame(dso, ui, &table_data, &segbase, &fde_count)) { 444 memset(&di, 0, sizeof(di)); 445 di.format = UNW_INFO_FORMAT_REMOTE_TABLE; 446 di.start_ip = map->start; 447 di.end_ip = map->end; 448 di.u.rti.segbase = segbase; 449 di.u.rti.table_data = table_data; 450 di.u.rti.table_len = fde_count * sizeof(struct table_entry) 451 / sizeof(unw_word_t); 452 ret = dwarf_search_unwind_table(as, ip, &di, pi, 453 need_unwind_info, arg); 454 } 455 456 #ifndef NO_LIBUNWIND_DEBUG_FRAME 457 /* Check the .debug_frame section for unwinding info */ 458 if (ret < 0 && 459 !read_unwind_spec_debug_frame(dso, ui->machine, &segbase)) { 460 int fd = dso__data_get_fd(dso, ui->machine); 461 int is_exec = elf_is_exec(fd, dso->name); 462 unw_word_t base = is_exec ? 0 : map->start; 463 const char *symfile; 464 465 if (fd >= 0) 466 dso__data_put_fd(dso); 467 468 symfile = dso->symsrc_filename ?: dso->name; 469 470 memset(&di, 0, sizeof(di)); 471 if (dwarf_find_debug_frame(0, &di, ip, base, symfile, 472 map->start, map->end)) 473 return dwarf_search_unwind_table(as, ip, &di, pi, 474 need_unwind_info, arg); 475 } 476 #endif 477 478 return ret; 479 } 480 481 static int access_fpreg(unw_addr_space_t __maybe_unused as, 482 unw_regnum_t __maybe_unused num, 483 unw_fpreg_t __maybe_unused *val, 484 int __maybe_unused __write, 485 void __maybe_unused *arg) 486 { 487 pr_err("unwind: access_fpreg unsupported\n"); 488 return -UNW_EINVAL; 489 } 490 491 static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as, 492 unw_word_t __maybe_unused *dil_addr, 493 void __maybe_unused *arg) 494 { 495 return -UNW_ENOINFO; 496 } 497 498 static int resume(unw_addr_space_t __maybe_unused as, 499 unw_cursor_t __maybe_unused *cu, 500 void __maybe_unused *arg) 501 { 502 pr_err("unwind: resume unsupported\n"); 503 return -UNW_EINVAL; 504 } 505 506 static int 507 get_proc_name(unw_addr_space_t __maybe_unused as, 508 unw_word_t __maybe_unused addr, 509 char __maybe_unused *bufp, size_t __maybe_unused buf_len, 510 unw_word_t __maybe_unused *offp, void __maybe_unused *arg) 511 { 512 pr_err("unwind: get_proc_name unsupported\n"); 513 return -UNW_EINVAL; 514 } 515 516 static int access_dso_mem(struct unwind_info *ui, unw_word_t addr, 517 unw_word_t *data) 518 { 519 struct map *map; 520 struct dso *dso; 521 ssize_t size; 522 523 map = find_map(addr, ui); 524 if (!map) { 525 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 526 return -1; 527 } 528 529 dso = map__dso(map); 530 531 if (!dso) 532 return -1; 533 534 size = dso__data_read_addr(dso, map, ui->machine, 535 addr, (u8 *) data, sizeof(*data)); 536 537 return !(size == sizeof(*data)); 538 } 539 540 static int access_mem(unw_addr_space_t __maybe_unused as, 541 unw_word_t addr, unw_word_t *valp, 542 int __write, void *arg) 543 { 544 struct unwind_info *ui = arg; 545 struct stack_dump *stack = &ui->sample->user_stack; 546 u64 start, end; 547 int offset; 548 int ret; 549 550 /* Don't support write, probably not needed. */ 551 if (__write || !stack || !ui->sample->user_regs.regs) { 552 *valp = 0; 553 return 0; 554 } 555 556 ret = perf_reg_value(&start, &ui->sample->user_regs, 557 LIBUNWIND__ARCH_REG_SP); 558 if (ret) 559 return ret; 560 561 end = start + stack->size; 562 563 /* Check overflow. */ 564 if (addr + sizeof(unw_word_t) < addr) 565 return -EINVAL; 566 567 if (addr < start || addr + sizeof(unw_word_t) >= end) { 568 ret = access_dso_mem(ui, addr, valp); 569 if (ret) { 570 pr_debug("unwind: access_mem %p not inside range" 571 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 572 (void *) (uintptr_t) addr, start, end); 573 *valp = 0; 574 return ret; 575 } 576 return 0; 577 } 578 579 offset = addr - start; 580 *valp = *(unw_word_t *)&stack->data[offset]; 581 pr_debug("unwind: access_mem addr %p val %lx, offset %d\n", 582 (void *) (uintptr_t) addr, (unsigned long)*valp, offset); 583 return 0; 584 } 585 586 static int access_reg(unw_addr_space_t __maybe_unused as, 587 unw_regnum_t regnum, unw_word_t *valp, 588 int __write, void *arg) 589 { 590 struct unwind_info *ui = arg; 591 int id, ret; 592 u64 val; 593 594 /* Don't support write, I suspect we don't need it. */ 595 if (__write) { 596 pr_err("unwind: access_reg w %d\n", regnum); 597 return 0; 598 } 599 600 if (!ui->sample->user_regs.regs) { 601 *valp = 0; 602 return 0; 603 } 604 605 id = LIBUNWIND__ARCH_REG_ID(regnum); 606 if (id < 0) 607 return -EINVAL; 608 609 ret = perf_reg_value(&val, &ui->sample->user_regs, id); 610 if (ret) { 611 if (!ui->best_effort) 612 pr_err("unwind: can't read reg %d\n", regnum); 613 return ret; 614 } 615 616 *valp = (unw_word_t) val; 617 pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp); 618 return 0; 619 } 620 621 static void put_unwind_info(unw_addr_space_t __maybe_unused as, 622 unw_proc_info_t *pi __maybe_unused, 623 void *arg __maybe_unused) 624 { 625 pr_debug("unwind: put_unwind_info called\n"); 626 } 627 628 static int entry(u64 ip, struct thread *thread, 629 unwind_entry_cb_t cb, void *arg) 630 { 631 struct unwind_entry e; 632 struct addr_location al; 633 634 e.ms.sym = thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al); 635 e.ip = ip; 636 e.ms.map = al.map; 637 e.ms.maps = al.maps; 638 639 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 640 al.sym ? al.sym->name : "''", 641 ip, 642 al.map ? al.map->map_ip(al.map, ip) : (u64) 0); 643 644 return cb(&e, arg); 645 } 646 647 static void display_error(int err) 648 { 649 switch (err) { 650 case UNW_EINVAL: 651 pr_err("unwind: Only supports local.\n"); 652 break; 653 case UNW_EUNSPEC: 654 pr_err("unwind: Unspecified error.\n"); 655 break; 656 case UNW_EBADREG: 657 pr_err("unwind: Register unavailable.\n"); 658 break; 659 default: 660 break; 661 } 662 } 663 664 static unw_accessors_t accessors = { 665 .find_proc_info = find_proc_info, 666 .put_unwind_info = put_unwind_info, 667 .get_dyn_info_list_addr = get_dyn_info_list_addr, 668 .access_mem = access_mem, 669 .access_reg = access_reg, 670 .access_fpreg = access_fpreg, 671 .resume = resume, 672 .get_proc_name = get_proc_name, 673 }; 674 675 static int _unwind__prepare_access(struct maps *maps) 676 { 677 void *addr_space = unw_create_addr_space(&accessors, 0); 678 679 maps->addr_space = addr_space; 680 if (!addr_space) { 681 pr_err("unwind: Can't create unwind address space.\n"); 682 return -ENOMEM; 683 } 684 685 unw_set_caching_policy(addr_space, UNW_CACHE_GLOBAL); 686 return 0; 687 } 688 689 static void _unwind__flush_access(struct maps *maps) 690 { 691 unw_flush_cache(maps__addr_space(maps), 0, 0); 692 } 693 694 static void _unwind__finish_access(struct maps *maps) 695 { 696 unw_destroy_addr_space(maps__addr_space(maps)); 697 } 698 699 static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb, 700 void *arg, int max_stack) 701 { 702 u64 val; 703 unw_word_t ips[max_stack]; 704 unw_addr_space_t addr_space; 705 unw_cursor_t c; 706 int ret, i = 0; 707 708 ret = perf_reg_value(&val, &ui->sample->user_regs, 709 LIBUNWIND__ARCH_REG_IP); 710 if (ret) 711 return ret; 712 713 ips[i++] = (unw_word_t) val; 714 715 /* 716 * If we need more than one entry, do the DWARF 717 * unwind itself. 718 */ 719 if (max_stack - 1 > 0) { 720 WARN_ONCE(!ui->thread, "WARNING: ui->thread is NULL"); 721 addr_space = maps__addr_space(ui->thread->maps); 722 723 if (addr_space == NULL) 724 return -1; 725 726 ret = unw_init_remote(&c, addr_space, ui); 727 if (ret && !ui->best_effort) 728 display_error(ret); 729 730 while (!ret && (unw_step(&c) > 0) && i < max_stack) { 731 unw_get_reg(&c, UNW_REG_IP, &ips[i]); 732 733 /* 734 * Decrement the IP for any non-activation frames. 735 * this is required to properly find the srcline 736 * for caller frames. 737 * See also the documentation for dwfl_frame_pc(), 738 * which this code tries to replicate. 739 */ 740 if (unw_is_signal_frame(&c) <= 0) 741 --ips[i]; 742 743 ++i; 744 } 745 746 max_stack = i; 747 } 748 749 /* 750 * Display what we got based on the order setup. 751 */ 752 for (i = 0; i < max_stack && !ret; i++) { 753 int j = i; 754 755 if (callchain_param.order == ORDER_CALLER) 756 j = max_stack - i - 1; 757 ret = ips[j] ? entry(ips[j], ui->thread, cb, arg) : 0; 758 } 759 760 return ret; 761 } 762 763 static int _unwind__get_entries(unwind_entry_cb_t cb, void *arg, 764 struct thread *thread, 765 struct perf_sample *data, int max_stack, 766 bool best_effort) 767 { 768 struct unwind_info ui = { 769 .sample = data, 770 .thread = thread, 771 .machine = maps__machine(thread->maps), 772 .best_effort = best_effort 773 }; 774 775 if (!data->user_regs.regs) 776 return -EINVAL; 777 778 if (max_stack <= 0) 779 return -EINVAL; 780 781 return get_entries(&ui, cb, arg, max_stack); 782 } 783 784 static struct unwind_libunwind_ops 785 _unwind_libunwind_ops = { 786 .prepare_access = _unwind__prepare_access, 787 .flush_access = _unwind__flush_access, 788 .finish_access = _unwind__finish_access, 789 .get_entries = _unwind__get_entries, 790 }; 791 792 #ifndef REMOTE_UNWIND_LIBUNWIND 793 struct unwind_libunwind_ops * 794 local_unwind_libunwind_ops = &_unwind_libunwind_ops; 795 #endif 796