1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * genelf_debug.c 4 * Copyright (C) 2015, Google, Inc 5 * 6 * Contributed by: 7 * Stephane Eranian <eranian@google.com> 8 * 9 * based on GPLv2 source code from Oprofile 10 * @remark Copyright 2007 OProfile authors 11 * @author Philippe Elie 12 */ 13 #include <linux/compiler.h> 14 #include <sys/types.h> 15 #include <stdio.h> 16 #include <getopt.h> 17 #include <stddef.h> 18 #include <libelf.h> 19 #include <string.h> 20 #include <stdlib.h> 21 #include <inttypes.h> 22 #include <limits.h> 23 #include <fcntl.h> 24 #include <err.h> 25 #include <dwarf.h> 26 27 #include "genelf.h" 28 #include "../util/jitdump.h" 29 30 #define BUFFER_EXT_DFL_SIZE (4 * 1024) 31 32 typedef uint32_t uword; 33 typedef uint16_t uhalf; 34 typedef int32_t sword; 35 typedef int16_t shalf; 36 typedef uint8_t ubyte; 37 typedef int8_t sbyte; 38 39 struct buffer_ext { 40 size_t cur_pos; 41 size_t max_sz; 42 void *data; 43 }; 44 45 static void 46 buffer_ext_dump(struct buffer_ext *be, const char *msg) 47 { 48 size_t i; 49 warnx("DUMP for %s", msg); 50 for (i = 0 ; i < be->cur_pos; i++) 51 warnx("%4zu 0x%02x", i, (((char *)be->data)[i]) & 0xff); 52 } 53 54 static inline int 55 buffer_ext_add(struct buffer_ext *be, void *addr, size_t sz) 56 { 57 void *tmp; 58 size_t be_sz = be->max_sz; 59 60 retry: 61 if ((be->cur_pos + sz) < be_sz) { 62 memcpy(be->data + be->cur_pos, addr, sz); 63 be->cur_pos += sz; 64 return 0; 65 } 66 67 if (!be_sz) 68 be_sz = BUFFER_EXT_DFL_SIZE; 69 else 70 be_sz <<= 1; 71 72 tmp = realloc(be->data, be_sz); 73 if (!tmp) 74 return -1; 75 76 be->data = tmp; 77 be->max_sz = be_sz; 78 79 goto retry; 80 } 81 82 static void 83 buffer_ext_init(struct buffer_ext *be) 84 { 85 be->data = NULL; 86 be->cur_pos = 0; 87 be->max_sz = 0; 88 } 89 90 static inline size_t 91 buffer_ext_size(struct buffer_ext *be) 92 { 93 return be->cur_pos; 94 } 95 96 static inline void * 97 buffer_ext_addr(struct buffer_ext *be) 98 { 99 return be->data; 100 } 101 102 struct debug_line_header { 103 // Not counting this field 104 uword total_length; 105 // version number (2 currently) 106 uhalf version; 107 // relative offset from next field to 108 // program statement 109 uword prolog_length; 110 ubyte minimum_instruction_length; 111 ubyte default_is_stmt; 112 // line_base - see DWARF 2 specs 113 sbyte line_base; 114 // line_range - see DWARF 2 specs 115 ubyte line_range; 116 // number of opcode + 1 117 ubyte opcode_base; 118 /* follow the array of opcode args nr: ubytes [nr_opcode_base] */ 119 /* follow the search directories index, zero terminated string 120 * terminated by an empty string. 121 */ 122 /* follow an array of { filename, LEB128, LEB128, LEB128 }, first is 123 * the directory index entry, 0 means current directory, then mtime 124 * and filesize, last entry is followed by en empty string. 125 */ 126 /* follow the first program statement */ 127 } __packed; 128 129 /* DWARF 2 spec talk only about one possible compilation unit header while 130 * binutils can handle two flavours of dwarf 2, 32 and 64 bits, this is not 131 * related to the used arch, an ELF 32 can hold more than 4 Go of debug 132 * information. For now we handle only DWARF 2 32 bits comp unit. It'll only 133 * become a problem if we generate more than 4GB of debug information. 134 */ 135 struct compilation_unit_header { 136 uword total_length; 137 uhalf version; 138 uword debug_abbrev_offset; 139 ubyte pointer_size; 140 } __packed; 141 142 #define DW_LNS_num_opcode (DW_LNS_set_isa + 1) 143 144 /* field filled at run time are marked with -1 */ 145 static struct debug_line_header const default_debug_line_header = { 146 .total_length = -1, 147 .version = 2, 148 .prolog_length = -1, 149 .minimum_instruction_length = 1, /* could be better when min instruction size != 1 */ 150 .default_is_stmt = 1, /* we don't take care about basic block */ 151 .line_base = -5, /* sensible value for line base ... */ 152 .line_range = -14, /* ... and line range are guessed statically */ 153 .opcode_base = DW_LNS_num_opcode 154 }; 155 156 static ubyte standard_opcode_length[] = 157 { 158 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1 159 }; 160 #if 0 161 { 162 [DW_LNS_advance_pc] = 1, 163 [DW_LNS_advance_line] = 1, 164 [DW_LNS_set_file] = 1, 165 [DW_LNS_set_column] = 1, 166 [DW_LNS_fixed_advance_pc] = 1, 167 [DW_LNS_set_isa] = 1, 168 }; 169 #endif 170 171 /* field filled at run time are marked with -1 */ 172 static struct compilation_unit_header default_comp_unit_header = { 173 .total_length = -1, 174 .version = 2, 175 .debug_abbrev_offset = 0, /* we reuse the same abbrev entries for all comp unit */ 176 .pointer_size = sizeof(void *) 177 }; 178 179 static void emit_uword(struct buffer_ext *be, uword data) 180 { 181 buffer_ext_add(be, &data, sizeof(uword)); 182 } 183 184 static void emit_string(struct buffer_ext *be, const char *s) 185 { 186 buffer_ext_add(be, (void *)s, strlen(s) + 1); 187 } 188 189 static void emit_unsigned_LEB128(struct buffer_ext *be, 190 unsigned long data) 191 { 192 do { 193 ubyte cur = data & 0x7F; 194 data >>= 7; 195 if (data) 196 cur |= 0x80; 197 buffer_ext_add(be, &cur, 1); 198 } while (data); 199 } 200 201 static void emit_signed_LEB128(struct buffer_ext *be, long data) 202 { 203 int more = 1; 204 int negative = data < 0; 205 int size = sizeof(long) * CHAR_BIT; 206 while (more) { 207 ubyte cur = data & 0x7F; 208 data >>= 7; 209 if (negative) 210 data |= - (1 << (size - 7)); 211 if ((data == 0 && !(cur & 0x40)) || 212 (data == -1l && (cur & 0x40))) 213 more = 0; 214 else 215 cur |= 0x80; 216 buffer_ext_add(be, &cur, 1); 217 } 218 } 219 220 static void emit_extended_opcode(struct buffer_ext *be, ubyte opcode, 221 void *data, size_t data_len) 222 { 223 buffer_ext_add(be, (char *)"", 1); 224 225 emit_unsigned_LEB128(be, data_len + 1); 226 227 buffer_ext_add(be, &opcode, 1); 228 buffer_ext_add(be, data, data_len); 229 } 230 231 static void emit_opcode(struct buffer_ext *be, ubyte opcode) 232 { 233 buffer_ext_add(be, &opcode, 1); 234 } 235 236 static void emit_opcode_signed(struct buffer_ext *be, 237 ubyte opcode, long data) 238 { 239 buffer_ext_add(be, &opcode, 1); 240 emit_signed_LEB128(be, data); 241 } 242 243 static void emit_opcode_unsigned(struct buffer_ext *be, ubyte opcode, 244 unsigned long data) 245 { 246 buffer_ext_add(be, &opcode, 1); 247 emit_unsigned_LEB128(be, data); 248 } 249 250 static void emit_advance_pc(struct buffer_ext *be, unsigned long delta_pc) 251 { 252 emit_opcode_unsigned(be, DW_LNS_advance_pc, delta_pc); 253 } 254 255 static void emit_advance_lineno(struct buffer_ext *be, long delta_lineno) 256 { 257 emit_opcode_signed(be, DW_LNS_advance_line, delta_lineno); 258 } 259 260 static void emit_lne_end_of_sequence(struct buffer_ext *be) 261 { 262 emit_extended_opcode(be, DW_LNE_end_sequence, NULL, 0); 263 } 264 265 static void emit_set_file(struct buffer_ext *be, unsigned long idx) 266 { 267 emit_opcode_unsigned(be, DW_LNS_set_file, idx); 268 } 269 270 static void emit_lne_define_filename(struct buffer_ext *be, 271 const char *filename) 272 { 273 buffer_ext_add(be, (void *)"", 1); 274 275 /* LNE field, strlen(filename) + zero termination, 3 bytes for: the dir entry, timestamp, filesize */ 276 emit_unsigned_LEB128(be, strlen(filename) + 5); 277 emit_opcode(be, DW_LNE_define_file); 278 emit_string(be, filename); 279 /* directory index 0=do not know */ 280 emit_unsigned_LEB128(be, 0); 281 /* last modification date on file 0=do not know */ 282 emit_unsigned_LEB128(be, 0); 283 /* filesize 0=do not know */ 284 emit_unsigned_LEB128(be, 0); 285 } 286 287 static void emit_lne_set_address(struct buffer_ext *be, 288 void *address) 289 { 290 emit_extended_opcode(be, DW_LNE_set_address, &address, sizeof(unsigned long)); 291 } 292 293 static ubyte get_special_opcode(struct debug_entry *ent, 294 unsigned int last_line, 295 unsigned long last_vma) 296 { 297 unsigned int temp; 298 unsigned long delta_addr; 299 300 /* 301 * delta from line_base 302 */ 303 temp = (ent->lineno - last_line) - default_debug_line_header.line_base; 304 305 if (temp >= default_debug_line_header.line_range) 306 return 0; 307 308 /* 309 * delta of addresses 310 */ 311 delta_addr = (ent->addr - last_vma) / default_debug_line_header.minimum_instruction_length; 312 313 /* This is not sufficient to ensure opcode will be in [0-256] but 314 * sufficient to ensure when summing with the delta lineno we will 315 * not overflow the unsigned long opcode */ 316 317 if (delta_addr <= 256 / default_debug_line_header.line_range) { 318 unsigned long opcode = temp + 319 (delta_addr * default_debug_line_header.line_range) + 320 default_debug_line_header.opcode_base; 321 322 return opcode <= 255 ? opcode : 0; 323 } 324 return 0; 325 } 326 327 static void emit_lineno_info(struct buffer_ext *be, 328 struct debug_entry *ent, size_t nr_entry, 329 unsigned long code_addr) 330 { 331 size_t i; 332 333 /* 334 * Machine state at start of a statement program 335 * address = 0 336 * file = 1 337 * line = 1 338 * column = 0 339 * is_stmt = default_is_stmt as given in the debug_line_header 340 * basic block = 0 341 * end sequence = 0 342 */ 343 344 /* start state of the state machine we take care of */ 345 unsigned long last_vma = code_addr; 346 char const *cur_filename = NULL; 347 unsigned long cur_file_idx = 0; 348 int last_line = 1; 349 350 emit_lne_set_address(be, (void *)code_addr); 351 352 for (i = 0; i < nr_entry; i++, ent = debug_entry_next(ent)) { 353 int need_copy = 0; 354 ubyte special_opcode; 355 356 /* 357 * check if filename changed, if so add it 358 */ 359 if (!cur_filename || strcmp(cur_filename, ent->name)) { 360 emit_lne_define_filename(be, ent->name); 361 cur_filename = ent->name; 362 emit_set_file(be, ++cur_file_idx); 363 need_copy = 1; 364 } 365 366 special_opcode = get_special_opcode(ent, last_line, last_vma); 367 if (special_opcode != 0) { 368 last_line = ent->lineno; 369 last_vma = ent->addr; 370 emit_opcode(be, special_opcode); 371 } else { 372 /* 373 * lines differ, emit line delta 374 */ 375 if (last_line != ent->lineno) { 376 emit_advance_lineno(be, ent->lineno - last_line); 377 last_line = ent->lineno; 378 need_copy = 1; 379 } 380 /* 381 * addresses differ, emit address delta 382 */ 383 if (last_vma != ent->addr) { 384 emit_advance_pc(be, ent->addr - last_vma); 385 last_vma = ent->addr; 386 need_copy = 1; 387 } 388 /* 389 * add new row to matrix 390 */ 391 if (need_copy) 392 emit_opcode(be, DW_LNS_copy); 393 } 394 } 395 } 396 397 static void add_debug_line(struct buffer_ext *be, 398 struct debug_entry *ent, size_t nr_entry, 399 unsigned long code_addr) 400 { 401 struct debug_line_header * dbg_header; 402 size_t old_size; 403 404 old_size = buffer_ext_size(be); 405 406 buffer_ext_add(be, (void *)&default_debug_line_header, 407 sizeof(default_debug_line_header)); 408 409 buffer_ext_add(be, &standard_opcode_length, sizeof(standard_opcode_length)); 410 411 // empty directory entry 412 buffer_ext_add(be, (void *)"", 1); 413 414 // empty filename directory 415 buffer_ext_add(be, (void *)"", 1); 416 417 dbg_header = buffer_ext_addr(be) + old_size; 418 dbg_header->prolog_length = (buffer_ext_size(be) - old_size) - 419 offsetof(struct debug_line_header, minimum_instruction_length); 420 421 emit_lineno_info(be, ent, nr_entry, code_addr); 422 423 emit_lne_end_of_sequence(be); 424 425 dbg_header = buffer_ext_addr(be) + old_size; 426 dbg_header->total_length = (buffer_ext_size(be) - old_size) - 427 offsetof(struct debug_line_header, version); 428 } 429 430 static void 431 add_debug_abbrev(struct buffer_ext *be) 432 { 433 emit_unsigned_LEB128(be, 1); 434 emit_unsigned_LEB128(be, DW_TAG_compile_unit); 435 emit_unsigned_LEB128(be, DW_CHILDREN_yes); 436 emit_unsigned_LEB128(be, DW_AT_stmt_list); 437 emit_unsigned_LEB128(be, DW_FORM_data4); 438 emit_unsigned_LEB128(be, 0); 439 emit_unsigned_LEB128(be, 0); 440 emit_unsigned_LEB128(be, 0); 441 } 442 443 static void 444 add_compilation_unit(struct buffer_ext *be, 445 size_t offset_debug_line) 446 { 447 struct compilation_unit_header *comp_unit_header; 448 size_t old_size = buffer_ext_size(be); 449 450 buffer_ext_add(be, &default_comp_unit_header, 451 sizeof(default_comp_unit_header)); 452 453 emit_unsigned_LEB128(be, 1); 454 emit_uword(be, offset_debug_line); 455 456 comp_unit_header = buffer_ext_addr(be) + old_size; 457 comp_unit_header->total_length = (buffer_ext_size(be) - old_size) - 458 offsetof(struct compilation_unit_header, version); 459 } 460 461 static int 462 jit_process_debug_info(uint64_t code_addr, 463 void *debug, int nr_debug_entries, 464 struct buffer_ext *dl, 465 struct buffer_ext *da, 466 struct buffer_ext *di) 467 { 468 struct debug_entry *ent = debug; 469 int i; 470 471 for (i = 0; i < nr_debug_entries; i++) { 472 ent->addr = ent->addr - code_addr; 473 ent = debug_entry_next(ent); 474 } 475 add_compilation_unit(di, buffer_ext_size(dl)); 476 add_debug_line(dl, debug, nr_debug_entries, 0); 477 add_debug_abbrev(da); 478 if (0) buffer_ext_dump(da, "abbrev"); 479 480 return 0; 481 } 482 483 int 484 jit_add_debug_info(Elf *e, uint64_t code_addr, void *debug, int nr_debug_entries) 485 { 486 Elf_Data *d; 487 Elf_Scn *scn; 488 Elf_Shdr *shdr; 489 struct buffer_ext dl, di, da; 490 int ret; 491 492 buffer_ext_init(&dl); 493 buffer_ext_init(&di); 494 buffer_ext_init(&da); 495 496 ret = jit_process_debug_info(code_addr, debug, nr_debug_entries, &dl, &da, &di); 497 if (ret) 498 return -1; 499 /* 500 * setup .debug_line section 501 */ 502 scn = elf_newscn(e); 503 if (!scn) { 504 warnx("cannot create section"); 505 return -1; 506 } 507 508 d = elf_newdata(scn); 509 if (!d) { 510 warnx("cannot get new data"); 511 return -1; 512 } 513 514 d->d_align = 1; 515 d->d_off = 0LL; 516 d->d_buf = buffer_ext_addr(&dl); 517 d->d_type = ELF_T_BYTE; 518 d->d_size = buffer_ext_size(&dl); 519 d->d_version = EV_CURRENT; 520 521 shdr = elf_getshdr(scn); 522 if (!shdr) { 523 warnx("cannot get section header"); 524 return -1; 525 } 526 527 shdr->sh_name = 52; /* .debug_line */ 528 shdr->sh_type = SHT_PROGBITS; 529 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */ 530 shdr->sh_flags = 0; 531 shdr->sh_entsize = 0; 532 533 /* 534 * setup .debug_info section 535 */ 536 scn = elf_newscn(e); 537 if (!scn) { 538 warnx("cannot create section"); 539 return -1; 540 } 541 542 d = elf_newdata(scn); 543 if (!d) { 544 warnx("cannot get new data"); 545 return -1; 546 } 547 548 d->d_align = 1; 549 d->d_off = 0LL; 550 d->d_buf = buffer_ext_addr(&di); 551 d->d_type = ELF_T_BYTE; 552 d->d_size = buffer_ext_size(&di); 553 d->d_version = EV_CURRENT; 554 555 shdr = elf_getshdr(scn); 556 if (!shdr) { 557 warnx("cannot get section header"); 558 return -1; 559 } 560 561 shdr->sh_name = 64; /* .debug_info */ 562 shdr->sh_type = SHT_PROGBITS; 563 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */ 564 shdr->sh_flags = 0; 565 shdr->sh_entsize = 0; 566 567 /* 568 * setup .debug_abbrev section 569 */ 570 scn = elf_newscn(e); 571 if (!scn) { 572 warnx("cannot create section"); 573 return -1; 574 } 575 576 d = elf_newdata(scn); 577 if (!d) { 578 warnx("cannot get new data"); 579 return -1; 580 } 581 582 d->d_align = 1; 583 d->d_off = 0LL; 584 d->d_buf = buffer_ext_addr(&da); 585 d->d_type = ELF_T_BYTE; 586 d->d_size = buffer_ext_size(&da); 587 d->d_version = EV_CURRENT; 588 589 shdr = elf_getshdr(scn); 590 if (!shdr) { 591 warnx("cannot get section header"); 592 return -1; 593 } 594 595 shdr->sh_name = 76; /* .debug_info */ 596 shdr->sh_type = SHT_PROGBITS; 597 shdr->sh_addr = 0; /* must be zero or == sh_offset -> dynamic object */ 598 shdr->sh_flags = 0; 599 shdr->sh_entsize = 0; 600 601 /* 602 * now we update the ELF image with all the sections 603 */ 604 if (elf_update(e, ELF_C_WRITE) < 0) { 605 warnx("elf_update debug failed"); 606 return -1; 607 } 608 return 0; 609 } 610