Stephane Eranian | 9b07e27 | 2015-11-30 10:02:21 +0100 | [diff] [blame] | 1 | /* |
| 2 | * genelf.c |
| 3 | * Copyright (C) 2014, Google, Inc |
| 4 | * |
| 5 | * Contributed by: |
| 6 | * Stephane Eranian <eranian@gmail.com> |
| 7 | * |
| 8 | * Released under the GPL v2. (and only v2, not any later version) |
| 9 | */ |
| 10 | |
| 11 | #include <sys/types.h> |
| 12 | #include <stdio.h> |
| 13 | #include <getopt.h> |
| 14 | #include <stddef.h> |
| 15 | #include <libelf.h> |
| 16 | #include <string.h> |
| 17 | #include <stdlib.h> |
| 18 | #include <inttypes.h> |
| 19 | #include <limits.h> |
| 20 | #include <fcntl.h> |
| 21 | #include <err.h> |
Maciej Debski | 03f5be2 | 2016-10-13 03:59:36 -0700 | [diff] [blame] | 22 | #ifdef HAVE_DWARF_SUPPORT |
Stephane Eranian | 9b07e27 | 2015-11-30 10:02:21 +0100 | [diff] [blame] | 23 | #include <dwarf.h> |
Maciej Debski | 03f5be2 | 2016-10-13 03:59:36 -0700 | [diff] [blame] | 24 | #endif |
Stephane Eranian | 9b07e27 | 2015-11-30 10:02:21 +0100 | [diff] [blame] | 25 | |
| 26 | #include "perf.h" |
| 27 | #include "genelf.h" |
| 28 | #include "../util/jitdump.h" |
| 29 | |
| 30 | #define JVMTI |
| 31 | |
| 32 | #define BUILD_ID_URANDOM /* different uuid for each run */ |
| 33 | |
| 34 | #ifdef HAVE_LIBCRYPTO |
| 35 | |
| 36 | #define BUILD_ID_MD5 |
| 37 | #undef BUILD_ID_SHA /* does not seem to work well when linked with Java */ |
| 38 | #undef BUILD_ID_URANDOM /* different uuid for each run */ |
| 39 | |
| 40 | #ifdef BUILD_ID_SHA |
| 41 | #include <openssl/sha.h> |
| 42 | #endif |
| 43 | |
| 44 | #ifdef BUILD_ID_MD5 |
| 45 | #include <openssl/md5.h> |
| 46 | #endif |
| 47 | #endif |
| 48 | |
| 49 | |
| 50 | typedef struct { |
| 51 | unsigned int namesz; /* Size of entry's owner string */ |
| 52 | unsigned int descsz; /* Size of the note descriptor */ |
| 53 | unsigned int type; /* Interpretation of the descriptor */ |
| 54 | char name[0]; /* Start of the name+desc data */ |
| 55 | } Elf_Note; |
| 56 | |
| 57 | struct options { |
| 58 | char *output; |
| 59 | int fd; |
| 60 | }; |
| 61 | |
| 62 | static char shd_string_table[] = { |
| 63 | 0, |
| 64 | '.', 't', 'e', 'x', 't', 0, /* 1 */ |
| 65 | '.', 's', 'h', 's', 't', 'r', 't', 'a', 'b', 0, /* 7 */ |
| 66 | '.', 's', 'y', 'm', 't', 'a', 'b', 0, /* 17 */ |
| 67 | '.', 's', 't', 'r', 't', 'a', 'b', 0, /* 25 */ |
| 68 | '.', 'n', 'o', 't', 'e', '.', 'g', 'n', 'u', '.', 'b', 'u', 'i', 'l', 'd', '-', 'i', 'd', 0, /* 33 */ |
| 69 | '.', 'd', 'e', 'b', 'u', 'g', '_', 'l', 'i', 'n', 'e', 0, /* 52 */ |
| 70 | '.', 'd', 'e', 'b', 'u', 'g', '_', 'i', 'n', 'f', 'o', 0, /* 64 */ |
| 71 | '.', 'd', 'e', 'b', 'u', 'g', '_', 'a', 'b', 'b', 'r', 'e', 'v', 0, /* 76 */ |
| 72 | }; |
| 73 | |
| 74 | static struct buildid_note { |
| 75 | Elf_Note desc; /* descsz: size of build-id, must be multiple of 4 */ |
| 76 | char name[4]; /* GNU\0 */ |
| 77 | char build_id[20]; |
| 78 | } bnote; |
| 79 | |
| 80 | static Elf_Sym symtab[]={ |
| 81 | /* symbol 0 MUST be the undefined symbol */ |
| 82 | { .st_name = 0, /* index in sym_string table */ |
| 83 | .st_info = ELF_ST_TYPE(STT_NOTYPE), |
| 84 | .st_shndx = 0, /* for now */ |
| 85 | .st_value = 0x0, |
| 86 | .st_other = ELF_ST_VIS(STV_DEFAULT), |
| 87 | .st_size = 0, |
| 88 | }, |
| 89 | { .st_name = 1, /* index in sym_string table */ |
| 90 | .st_info = ELF_ST_BIND(STB_LOCAL) | ELF_ST_TYPE(STT_FUNC), |
| 91 | .st_shndx = 1, |
| 92 | .st_value = 0, /* for now */ |
| 93 | .st_other = ELF_ST_VIS(STV_DEFAULT), |
| 94 | .st_size = 0, /* for now */ |
| 95 | } |
| 96 | }; |
| 97 | |
| 98 | #ifdef BUILD_ID_URANDOM |
| 99 | static void |
| 100 | gen_build_id(struct buildid_note *note, |
| 101 | unsigned long load_addr __maybe_unused, |
| 102 | const void *code __maybe_unused, |
| 103 | size_t csize __maybe_unused) |
| 104 | { |
| 105 | int fd; |
| 106 | size_t sz = sizeof(note->build_id); |
| 107 | ssize_t sret; |
| 108 | |
| 109 | fd = open("/dev/urandom", O_RDONLY); |
| 110 | if (fd == -1) |
| 111 | err(1, "cannot access /dev/urandom for builid"); |
| 112 | |
| 113 | sret = read(fd, note->build_id, sz); |
| 114 | |
| 115 | close(fd); |
| 116 | |
| 117 | if (sret != (ssize_t)sz) |
| 118 | memset(note->build_id, 0, sz); |
| 119 | } |
| 120 | #endif |
| 121 | |
| 122 | #ifdef BUILD_ID_SHA |
| 123 | static void |
| 124 | gen_build_id(struct buildid_note *note, |
| 125 | unsigned long load_addr __maybe_unused, |
| 126 | const void *code, |
| 127 | size_t csize) |
| 128 | { |
| 129 | if (sizeof(note->build_id) < SHA_DIGEST_LENGTH) |
| 130 | errx(1, "build_id too small for SHA1"); |
| 131 | |
| 132 | SHA1(code, csize, (unsigned char *)note->build_id); |
| 133 | } |
| 134 | #endif |
| 135 | |
| 136 | #ifdef BUILD_ID_MD5 |
| 137 | static void |
| 138 | gen_build_id(struct buildid_note *note, unsigned long load_addr, const void *code, size_t csize) |
| 139 | { |
| 140 | MD5_CTX context; |
| 141 | |
| 142 | if (sizeof(note->build_id) < 16) |
| 143 | errx(1, "build_id too small for MD5"); |
| 144 | |
| 145 | MD5_Init(&context); |
| 146 | MD5_Update(&context, &load_addr, sizeof(load_addr)); |
| 147 | MD5_Update(&context, code, csize); |
| 148 | MD5_Final((unsigned char *)note->build_id, &context); |
| 149 | } |
| 150 | #endif |
| 151 | |
| 152 | /* |
| 153 | * fd: file descriptor open for writing for the output file |
| 154 | * load_addr: code load address (could be zero, just used for buildid) |
| 155 | * sym: function name (for native code - used as the symbol) |
| 156 | * code: the native code |
| 157 | * csize: the code size in bytes |
| 158 | */ |
| 159 | int |
| 160 | jit_write_elf(int fd, uint64_t load_addr, const char *sym, |
Stephane Eranian | 598b7c6 | 2015-11-30 10:02:23 +0100 | [diff] [blame] | 161 | const void *code, int csize, |
Maciej Debski | 03f5be2 | 2016-10-13 03:59:36 -0700 | [diff] [blame] | 162 | void *debug __maybe_unused, int nr_debug_entries __maybe_unused) |
Stephane Eranian | 9b07e27 | 2015-11-30 10:02:21 +0100 | [diff] [blame] | 163 | { |
| 164 | Elf *e; |
| 165 | Elf_Data *d; |
| 166 | Elf_Scn *scn; |
| 167 | Elf_Ehdr *ehdr; |
| 168 | Elf_Shdr *shdr; |
| 169 | char *strsym = NULL; |
| 170 | int symlen; |
| 171 | int retval = -1; |
| 172 | |
| 173 | if (elf_version(EV_CURRENT) == EV_NONE) { |
| 174 | warnx("ELF initialization failed"); |
| 175 | return -1; |
| 176 | } |
| 177 | |
| 178 | e = elf_begin(fd, ELF_C_WRITE, NULL); |
| 179 | if (!e) { |
| 180 | warnx("elf_begin failed"); |
| 181 | goto error; |
| 182 | } |
| 183 | |
| 184 | /* |
| 185 | * setup ELF header |
| 186 | */ |
| 187 | ehdr = elf_newehdr(e); |
| 188 | if (!ehdr) { |
| 189 | warnx("cannot get ehdr"); |
| 190 | goto error; |
| 191 | } |
| 192 | |
| 193 | ehdr->e_ident[EI_DATA] = GEN_ELF_ENDIAN; |
| 194 | ehdr->e_ident[EI_CLASS] = GEN_ELF_CLASS; |
| 195 | ehdr->e_machine = GEN_ELF_ARCH; |
| 196 | ehdr->e_type = ET_DYN; |
| 197 | ehdr->e_entry = GEN_ELF_TEXT_OFFSET; |
| 198 | ehdr->e_version = EV_CURRENT; |
| 199 | ehdr->e_shstrndx= 2; /* shdr index for section name */ |
| 200 | |
| 201 | /* |
| 202 | * setup text section |
| 203 | */ |
| 204 | scn = elf_newscn(e); |
| 205 | if (!scn) { |
| 206 | warnx("cannot create section"); |
| 207 | goto error; |
| 208 | } |
| 209 | |
| 210 | d = elf_newdata(scn); |
| 211 | if (!d) { |
| 212 | warnx("cannot get new data"); |
| 213 | goto error; |
| 214 | } |
| 215 | |
| 216 | d->d_align = 16; |
| 217 | d->d_off = 0LL; |
| 218 | d->d_buf = (void *)code; |
| 219 | d->d_type = ELF_T_BYTE; |
| 220 | d->d_size = csize; |
| 221 | d->d_version = EV_CURRENT; |
| 222 | |
| 223 | shdr = elf_getshdr(scn); |
| 224 | if (!shdr) { |
| 225 | warnx("cannot get section header"); |
| 226 | goto error; |
| 227 | } |
| 228 | |
| 229 | shdr->sh_name = 1; |
| 230 | shdr->sh_type = SHT_PROGBITS; |
| 231 | shdr->sh_addr = GEN_ELF_TEXT_OFFSET; |
| 232 | shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC; |
| 233 | shdr->sh_entsize = 0; |
| 234 | |
| 235 | /* |
| 236 | * setup section headers string table |
| 237 | */ |
| 238 | scn = elf_newscn(e); |
| 239 | if (!scn) { |
| 240 | warnx("cannot create section"); |
| 241 | goto error; |
| 242 | } |
| 243 | |
| 244 | d = elf_newdata(scn); |
| 245 | if (!d) { |
| 246 | warnx("cannot get new data"); |
| 247 | goto error; |
| 248 | } |
| 249 | |
| 250 | d->d_align = 1; |
| 251 | d->d_off = 0LL; |
| 252 | d->d_buf = shd_string_table; |
| 253 | d->d_type = ELF_T_BYTE; |
| 254 | d->d_size = sizeof(shd_string_table); |
| 255 | d->d_version = EV_CURRENT; |
| 256 | |
| 257 | shdr = elf_getshdr(scn); |
| 258 | if (!shdr) { |
| 259 | warnx("cannot get section header"); |
| 260 | goto error; |
| 261 | } |
| 262 | |
| 263 | shdr->sh_name = 7; /* offset of '.shstrtab' in shd_string_table */ |
| 264 | shdr->sh_type = SHT_STRTAB; |
| 265 | shdr->sh_flags = 0; |
| 266 | shdr->sh_entsize = 0; |
| 267 | |
| 268 | /* |
| 269 | * setup symtab section |
| 270 | */ |
| 271 | symtab[1].st_size = csize; |
| 272 | symtab[1].st_value = GEN_ELF_TEXT_OFFSET; |
| 273 | |
| 274 | scn = elf_newscn(e); |
| 275 | if (!scn) { |
| 276 | warnx("cannot create section"); |
| 277 | goto error; |
| 278 | } |
| 279 | |
| 280 | d = elf_newdata(scn); |
| 281 | if (!d) { |
| 282 | warnx("cannot get new data"); |
| 283 | goto error; |
| 284 | } |
| 285 | |
| 286 | d->d_align = 8; |
| 287 | d->d_off = 0LL; |
| 288 | d->d_buf = symtab; |
| 289 | d->d_type = ELF_T_SYM; |
| 290 | d->d_size = sizeof(symtab); |
| 291 | d->d_version = EV_CURRENT; |
| 292 | |
| 293 | shdr = elf_getshdr(scn); |
| 294 | if (!shdr) { |
| 295 | warnx("cannot get section header"); |
| 296 | goto error; |
| 297 | } |
| 298 | |
| 299 | shdr->sh_name = 17; /* offset of '.symtab' in shd_string_table */ |
| 300 | shdr->sh_type = SHT_SYMTAB; |
| 301 | shdr->sh_flags = 0; |
| 302 | shdr->sh_entsize = sizeof(Elf_Sym); |
| 303 | shdr->sh_link = 4; /* index of .strtab section */ |
| 304 | |
| 305 | /* |
| 306 | * setup symbols string table |
| 307 | * 2 = 1 for 0 in 1st entry, 1 for the 0 at end of symbol for 2nd entry |
| 308 | */ |
| 309 | symlen = 2 + strlen(sym); |
| 310 | strsym = calloc(1, symlen); |
| 311 | if (!strsym) { |
| 312 | warnx("cannot allocate strsym"); |
| 313 | goto error; |
| 314 | } |
| 315 | strcpy(strsym + 1, sym); |
| 316 | |
| 317 | scn = elf_newscn(e); |
| 318 | if (!scn) { |
| 319 | warnx("cannot create section"); |
| 320 | goto error; |
| 321 | } |
| 322 | |
| 323 | d = elf_newdata(scn); |
| 324 | if (!d) { |
| 325 | warnx("cannot get new data"); |
| 326 | goto error; |
| 327 | } |
| 328 | |
| 329 | d->d_align = 1; |
| 330 | d->d_off = 0LL; |
| 331 | d->d_buf = strsym; |
| 332 | d->d_type = ELF_T_BYTE; |
| 333 | d->d_size = symlen; |
| 334 | d->d_version = EV_CURRENT; |
| 335 | |
| 336 | shdr = elf_getshdr(scn); |
| 337 | if (!shdr) { |
| 338 | warnx("cannot get section header"); |
| 339 | goto error; |
| 340 | } |
| 341 | |
| 342 | shdr->sh_name = 25; /* offset in shd_string_table */ |
| 343 | shdr->sh_type = SHT_STRTAB; |
| 344 | shdr->sh_flags = 0; |
| 345 | shdr->sh_entsize = 0; |
| 346 | |
| 347 | /* |
| 348 | * setup build-id section |
| 349 | */ |
| 350 | scn = elf_newscn(e); |
| 351 | if (!scn) { |
| 352 | warnx("cannot create section"); |
| 353 | goto error; |
| 354 | } |
| 355 | |
| 356 | d = elf_newdata(scn); |
| 357 | if (!d) { |
| 358 | warnx("cannot get new data"); |
| 359 | goto error; |
| 360 | } |
| 361 | |
| 362 | /* |
| 363 | * build-id generation |
| 364 | */ |
| 365 | gen_build_id(&bnote, load_addr, code, csize); |
| 366 | bnote.desc.namesz = sizeof(bnote.name); /* must include 0 termination */ |
| 367 | bnote.desc.descsz = sizeof(bnote.build_id); |
| 368 | bnote.desc.type = NT_GNU_BUILD_ID; |
| 369 | strcpy(bnote.name, "GNU"); |
| 370 | |
| 371 | d->d_align = 4; |
| 372 | d->d_off = 0LL; |
| 373 | d->d_buf = &bnote; |
| 374 | d->d_type = ELF_T_BYTE; |
| 375 | d->d_size = sizeof(bnote); |
| 376 | d->d_version = EV_CURRENT; |
| 377 | |
| 378 | shdr = elf_getshdr(scn); |
| 379 | if (!shdr) { |
| 380 | warnx("cannot get section header"); |
| 381 | goto error; |
| 382 | } |
| 383 | |
| 384 | shdr->sh_name = 33; /* offset in shd_string_table */ |
| 385 | shdr->sh_type = SHT_NOTE; |
| 386 | shdr->sh_addr = 0x0; |
| 387 | shdr->sh_flags = SHF_ALLOC; |
| 388 | shdr->sh_size = sizeof(bnote); |
| 389 | shdr->sh_entsize = 0; |
| 390 | |
Maciej Debski | 03f5be2 | 2016-10-13 03:59:36 -0700 | [diff] [blame] | 391 | #ifdef HAVE_DWARF_SUPPORT |
Stephane Eranian | 598b7c6 | 2015-11-30 10:02:23 +0100 | [diff] [blame] | 392 | if (debug && nr_debug_entries) { |
| 393 | retval = jit_add_debug_info(e, load_addr, debug, nr_debug_entries); |
| 394 | if (retval) |
| 395 | goto error; |
Maciej Debski | 03f5be2 | 2016-10-13 03:59:36 -0700 | [diff] [blame] | 396 | } else |
| 397 | #endif |
| 398 | { |
Stephane Eranian | 598b7c6 | 2015-11-30 10:02:23 +0100 | [diff] [blame] | 399 | if (elf_update(e, ELF_C_WRITE) < 0) { |
| 400 | warnx("elf_update 4 failed"); |
| 401 | goto error; |
| 402 | } |
Stephane Eranian | 9b07e27 | 2015-11-30 10:02:21 +0100 | [diff] [blame] | 403 | } |
| 404 | |
| 405 | retval = 0; |
| 406 | error: |
| 407 | (void)elf_end(e); |
| 408 | |
| 409 | free(strsym); |
| 410 | |
| 411 | |
| 412 | return retval; |
| 413 | } |
| 414 | |
| 415 | #ifndef JVMTI |
| 416 | |
| 417 | static unsigned char x86_code[] = { |
| 418 | 0xBB, 0x2A, 0x00, 0x00, 0x00, /* movl $42, %ebx */ |
| 419 | 0xB8, 0x01, 0x00, 0x00, 0x00, /* movl $1, %eax */ |
| 420 | 0xCD, 0x80 /* int $0x80 */ |
| 421 | }; |
| 422 | |
| 423 | static struct options options; |
| 424 | |
| 425 | int main(int argc, char **argv) |
| 426 | { |
| 427 | int c, fd, ret; |
| 428 | |
| 429 | while ((c = getopt(argc, argv, "o:h")) != -1) { |
| 430 | switch (c) { |
| 431 | case 'o': |
| 432 | options.output = optarg; |
| 433 | break; |
| 434 | case 'h': |
| 435 | printf("Usage: genelf -o output_file [-h]\n"); |
| 436 | return 0; |
| 437 | default: |
| 438 | errx(1, "unknown option"); |
| 439 | } |
| 440 | } |
| 441 | |
| 442 | fd = open(options.output, O_CREAT|O_TRUNC|O_RDWR, 0666); |
| 443 | if (fd == -1) |
| 444 | err(1, "cannot create file %s", options.output); |
| 445 | |
| 446 | ret = jit_write_elf(fd, "main", x86_code, sizeof(x86_code)); |
| 447 | close(fd); |
| 448 | |
| 449 | if (ret != 0) |
| 450 | unlink(options.output); |
| 451 | |
| 452 | return ret; |
| 453 | } |
| 454 | #endif |