| File: | ddb/db_elf.c |
| Warning: | line 67, column 8 Value stored to 'errstr' during its initialization is never read |
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| 1 | /* $OpenBSD: db_elf.c,v 1.32 2021/03/12 10:22:46 jsg Exp $ */ |
| 2 | /* $NetBSD: db_elf.c,v 1.13 2000/07/07 21:55:18 jhawk Exp $ */ |
| 3 | |
| 4 | /*- |
| 5 | * Copyright (c) 1997 The NetBSD Foundation, Inc. |
| 6 | * All rights reserved. |
| 7 | * |
| 8 | * This code is derived from software contributed to The NetBSD Foundation |
| 9 | * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, |
| 10 | * NASA Ames Research Center. |
| 11 | * |
| 12 | * Redistribution and use in source and binary forms, with or without |
| 13 | * modification, are permitted provided that the following conditions |
| 14 | * are met: |
| 15 | * 1. Redistributions of source code must retain the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer. |
| 17 | * 2. Redistributions in binary form must reproduce the above copyright |
| 18 | * notice, this list of conditions and the following disclaimer in the |
| 19 | * documentation and/or other materials provided with the distribution. |
| 20 | * |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 22 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 23 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 24 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 25 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 26 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 27 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 30 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 31 | * POSSIBILITY OF SUCH DAMAGE. |
| 32 | */ |
| 33 | |
| 34 | #include <sys/param.h> |
| 35 | #include <sys/stdint.h> |
| 36 | #include <sys/systm.h> |
| 37 | #include <sys/exec.h> |
| 38 | |
| 39 | #include <machine/db_machdep.h> |
| 40 | |
| 41 | #include <ddb/db_elf.h> |
| 42 | #include <ddb/db_sym.h> |
| 43 | #include <ddb/db_output.h> |
| 44 | |
| 45 | #include <sys/exec_elf.h> |
| 46 | |
| 47 | db_symtab_t db_symtab; |
| 48 | |
| 49 | Elf_SymElf64_Sym *db_elf_sym_lookup(char *); |
| 50 | |
| 51 | /* |
| 52 | * Find the symbol table and strings; tell ddb about them. |
| 53 | * |
| 54 | * symsize: size of symbol table |
| 55 | * symtab: pointer to start of symbol table |
| 56 | * esymtab: pointer to end of string table, for checking - rounded up to |
| 57 | * integer boundary |
| 58 | */ |
| 59 | int |
| 60 | db_elf_sym_init(int symsize, void *symtab, void *esymtab, const char *name) |
| 61 | { |
| 62 | Elf_EhdrElf64_Ehdr *elf; |
| 63 | Elf_ShdrElf64_Shdr *shp; |
| 64 | Elf_SymElf64_Sym *symp, *symtab_start, *symtab_end; |
| 65 | char *shstrtab, *strtab_start, *strtab_end; |
| 66 | int i; |
| 67 | char *errstr = ""; |
Value stored to 'errstr' during its initialization is never read | |
| 68 | |
| 69 | if (ALIGNED_POINTER(symtab, long)1 == 0) { |
| 70 | db_printf("[ %s symbol table has bad start address %p ]\n", |
| 71 | name, symtab); |
| 72 | return (0); |
| 73 | } |
| 74 | |
| 75 | symtab_start = symtab_end = NULL((void *)0); |
| 76 | strtab_start = strtab_end = NULL((void *)0); |
| 77 | |
| 78 | /* |
| 79 | * The format of the symbols loaded by the boot program is: |
| 80 | * |
| 81 | * Elf exec header |
| 82 | * first section header |
| 83 | * . . . |
| 84 | * . . . |
| 85 | * last section header |
| 86 | * first symbol, string, or line table section |
| 87 | * . . . |
| 88 | * . . . |
| 89 | * last symbol, string, or line table section |
| 90 | */ |
| 91 | |
| 92 | /* |
| 93 | * Validate the Elf header. |
| 94 | */ |
| 95 | elf = (Elf_EhdrElf64_Ehdr *)symtab; |
| 96 | if (memcmp(elf->e_ident, ELFMAG, SELFMAG)__builtin_memcmp((elf->e_ident), ("\177ELF"), (4)) != 0 || |
| 97 | elf->e_ident[EI_CLASS4] != ELFCLASS2) { |
| 98 | errstr = "bad magic"; |
| 99 | goto badheader; |
| 100 | } |
| 101 | |
| 102 | if (elf->e_machine != ELF_TARG_MACH62) { |
| 103 | errstr = "bad e_machine"; |
| 104 | goto badheader; |
| 105 | } |
| 106 | |
| 107 | /* |
| 108 | * Find the section header string table (.shstrtab), and look up |
| 109 | * the symbol table (.symtab) and string table (.strtab) via their |
| 110 | * names in shstrtab, rather than by table type. |
| 111 | * This works in the presence of multiple string tables, such as |
| 112 | * stabs data found when booting bsd.gdb. |
| 113 | */ |
| 114 | shp = (Elf_ShdrElf64_Shdr *)((char *)symtab + elf->e_shoff); |
| 115 | shstrtab = (char *)symtab + shp[elf->e_shstrndx].sh_offset; |
| 116 | for (i = 0; i < elf->e_shnum; i++) { |
| 117 | if (shp[i].sh_type == SHT_SYMTAB2) { |
| 118 | int j; |
| 119 | |
| 120 | if (shp[i].sh_offset == 0) |
| 121 | continue; |
| 122 | symtab_start = (Elf_SymElf64_Sym *)((char *)symtab + |
| 123 | shp[i].sh_offset); |
| 124 | symtab_end = (Elf_SymElf64_Sym *)((char *)symtab + |
| 125 | shp[i].sh_offset + shp[i].sh_size); |
| 126 | j = shp[i].sh_link; |
| 127 | if (shp[j].sh_offset == 0) |
| 128 | continue; |
| 129 | strtab_start = (char *)symtab + shp[j].sh_offset; |
| 130 | strtab_end = (char *)symtab + shp[j].sh_offset + |
| 131 | shp[j].sh_size; |
| 132 | break; |
| 133 | } |
| 134 | |
| 135 | /* |
| 136 | * This is the old way of doing things. |
| 137 | * XXX - verify that it's not needed. |
| 138 | */ |
| 139 | if (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0) { |
| 140 | strtab_start = (char *)symtab + shp[i].sh_offset; |
| 141 | strtab_end = (char *)symtab + shp[i].sh_offset + |
| 142 | shp[i].sh_size; |
| 143 | } else if (strcmp(".symtab", shstrtab+shp[i].sh_name) == 0) { |
| 144 | symtab_start = (Elf_SymElf64_Sym *)((char *)symtab + |
| 145 | shp[i].sh_offset); |
| 146 | symtab_end = (Elf_SymElf64_Sym *)((char *)symtab + |
| 147 | shp[i].sh_offset + shp[i].sh_size); |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | /* |
| 152 | * Now, sanity check the symbols against the string table. |
| 153 | */ |
| 154 | if (symtab_start == NULL((void *)0) || strtab_start == NULL((void *)0) || |
| 155 | ALIGNED_POINTER(symtab_start, long)1 == 0) { |
| 156 | errstr = "symtab unaligned"; |
| 157 | goto badheader; |
| 158 | } |
| 159 | for (symp = symtab_start; symp < symtab_end; symp++) |
| 160 | if (symp->st_name + strtab_start > strtab_end) { |
| 161 | errstr = "symtab corrupted"; |
| 162 | goto badheader; |
| 163 | } |
| 164 | |
| 165 | /* |
| 166 | * Link the symbol table into the debugger. |
| 167 | */ |
| 168 | db_symtab.start = (char *)symtab_start; |
| 169 | db_symtab.end = (char *)symtab_end; |
| 170 | db_symtab.name = name; |
| 171 | db_symtab.private = (char *)symtab; |
| 172 | |
| 173 | db_printf("[ using %lu bytes of %s ELF symbol table ]\n", |
| 174 | (u_long)roundup(((char *)esymtab - (char *)symtab), sizeof(u_long))((((((char *)esymtab - (char *)symtab))+((sizeof(u_long))-1)) /(sizeof(u_long)))*(sizeof(u_long))), |
| 175 | name); |
| 176 | |
| 177 | return (1); |
| 178 | |
| 179 | badheader: |
| 180 | db_printf("[ %s ELF symbol table not valid: %s ]\n", name, errstr); |
| 181 | return (0); |
| 182 | } |
| 183 | |
| 184 | /* |
| 185 | * Internal helper function - return a pointer to the string table |
| 186 | * for the current symbol table. |
| 187 | */ |
| 188 | char * |
| 189 | db_elf_find_strtab(db_symtab_t *stab) |
| 190 | { |
| 191 | Elf_EhdrElf64_Ehdr *elf = STAB_TO_EHDR(stab)((Elf64_Ehdr *)((stab)->private)); |
| 192 | Elf_ShdrElf64_Shdr *shp = STAB_TO_SHDR(stab, elf)((Elf64_Shdr *)((stab)->private + (elf)->e_shoff)); |
| 193 | char *shstrtab; |
| 194 | int i; |
| 195 | |
| 196 | shstrtab = (char *)elf + shp[elf->e_shstrndx].sh_offset; |
| 197 | for (i = 0; i < elf->e_shnum; i++) { |
| 198 | if (shp[i].sh_type == SHT_SYMTAB2) |
| 199 | return ((char *)elf + shp[shp[i].sh_link].sh_offset); |
| 200 | if (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0) |
| 201 | return ((char *)elf + shp[i].sh_offset); |
| 202 | } |
| 203 | |
| 204 | return (NULL((void *)0)); |
| 205 | } |
| 206 | |
| 207 | /* |
| 208 | * Internal helper function - return a pointer to the section |
| 209 | * named ``sname''. |
| 210 | */ |
| 211 | const char * |
| 212 | db_elf_find_section(db_symtab_t *stab, size_t *size, const char *sname) |
| 213 | { |
| 214 | Elf_EhdrElf64_Ehdr *elf = STAB_TO_EHDR(stab)((Elf64_Ehdr *)((stab)->private)); |
| 215 | Elf_ShdrElf64_Shdr *shp = STAB_TO_SHDR(stab, elf)((Elf64_Shdr *)((stab)->private + (elf)->e_shoff)); |
| 216 | char *shstrtab; |
| 217 | int i; |
| 218 | |
| 219 | shstrtab = (char *)elf + shp[elf->e_shstrndx].sh_offset; |
| 220 | for (i = 0; i < elf->e_shnum; i++) { |
| 221 | if ((shp[i].sh_flags & SHF_ALLOC0x2) != 0 && |
| 222 | strcmp(sname, shstrtab+shp[i].sh_name) == 0) { |
| 223 | *size = shp[i].sh_size; |
| 224 | return ((char *)elf + shp[i].sh_offset); |
| 225 | } |
| 226 | } |
| 227 | |
| 228 | return (NULL((void *)0)); |
| 229 | } |
| 230 | |
| 231 | /* |
| 232 | * Lookup the symbol with the given name. |
| 233 | */ |
| 234 | Elf_SymElf64_Sym * |
| 235 | db_elf_sym_lookup(char *symstr) |
| 236 | { |
| 237 | db_symtab_t *stab = &db_symtab; |
| 238 | Elf_SymElf64_Sym *symp, *symtab_start, *symtab_end; |
| 239 | char *strtab; |
| 240 | |
| 241 | if (stab->private == NULL((void *)0)) |
| 242 | return (NULL((void *)0)); |
| 243 | |
| 244 | symtab_start = STAB_TO_SYMSTART(stab)((Elf64_Sym *)((stab)->start)); |
| 245 | symtab_end = STAB_TO_SYMEND(stab)((Elf64_Sym *)((stab)->end)); |
| 246 | |
| 247 | strtab = db_elf_find_strtab(stab); |
| 248 | if (strtab == NULL((void *)0)) |
| 249 | return (NULL((void *)0)); |
| 250 | |
| 251 | for (symp = symtab_start; symp < symtab_end; symp++) { |
| 252 | if (symp->st_name != 0 && |
| 253 | db_eqname(strtab + symp->st_name, symstr, 0)) |
| 254 | return (symp); |
| 255 | } |
| 256 | |
| 257 | return (NULL((void *)0)); |
| 258 | } |
| 259 | |
| 260 | /* |
| 261 | * Search for the symbol with the given address (matching within the |
| 262 | * provided threshold). |
| 263 | */ |
| 264 | Elf_SymElf64_Sym * |
| 265 | db_elf_sym_search(vaddr_t off, db_strategy_t strategy, db_expr_t *diffp) |
| 266 | { |
| 267 | db_symtab_t *stab = &db_symtab; |
| 268 | Elf_SymElf64_Sym *rsymp, *symp, *symtab_start, *symtab_end; |
| 269 | db_expr_t diff = *diffp; |
| 270 | |
| 271 | if (stab->private == NULL((void *)0)) |
| 272 | return (NULL((void *)0)); |
| 273 | |
| 274 | symtab_start = STAB_TO_SYMSTART(stab)((Elf64_Sym *)((stab)->start)); |
| 275 | symtab_end = STAB_TO_SYMEND(stab)((Elf64_Sym *)((stab)->end)); |
| 276 | |
| 277 | rsymp = NULL((void *)0); |
| 278 | |
| 279 | for (symp = symtab_start; symp < symtab_end; symp++) { |
| 280 | if (symp->st_name == 0) |
| 281 | continue; |
| 282 | #if 0 |
| 283 | /* This prevents me from seeing anythin in locore.s -- eeh */ |
| 284 | if (ELF_SYM_TYPE(symp->st_info) != Elf_estt_object && |
| 285 | ELF_SYM_TYPE(symp->st_info) != Elf_estt_func) |
| 286 | continue; |
| 287 | #endif |
| 288 | |
| 289 | if (off >= symp->st_value) { |
| 290 | if ((off - symp->st_value) < diff) { |
| 291 | diff = off - symp->st_value; |
| 292 | rsymp = symp; |
| 293 | if (diff == 0) { |
| 294 | if (strategy == DB_STGY_PROC2 && |
| 295 | ELF_ST_TYPE(symp->st_info)(((unsigned int) symp->st_info) & 0xf) |
| 296 | == STT_FUNC2 && |
| 297 | ELF_ST_BIND(symp->st_info)((symp->st_info) >> 4) |
| 298 | != STB_LOCAL0) |
| 299 | break; |
| 300 | if (strategy == DB_STGY_ANY0 && |
| 301 | ELF_ST_BIND(symp->st_info)((symp->st_info) >> 4) |
| 302 | != STB_LOCAL0) |
| 303 | break; |
| 304 | } |
| 305 | } else if ((off - symp->st_value) == diff) { |
| 306 | if (rsymp == NULL((void *)0)) |
| 307 | rsymp = symp; |
| 308 | else if (ELF_ST_BIND(rsymp->st_info)((rsymp->st_info) >> 4) |
| 309 | == STB_LOCAL0 && |
| 310 | ELF_ST_BIND(symp->st_info)((symp->st_info) >> 4) |
| 311 | != STB_LOCAL0) { |
| 312 | /* pick the external symbol */ |
| 313 | rsymp = symp; |
| 314 | } |
| 315 | } |
| 316 | } |
| 317 | } |
| 318 | |
| 319 | if (rsymp == NULL((void *)0)) |
| 320 | *diffp = off; |
| 321 | else |
| 322 | *diffp = diff; |
| 323 | |
| 324 | return (rsymp); |
| 325 | } |
| 326 | |
| 327 | /* |
| 328 | * Return the name and value for a symbol. |
| 329 | */ |
| 330 | void |
| 331 | db_symbol_values(Elf_SymElf64_Sym *sym, char **namep, db_expr_t *valuep) |
| 332 | { |
| 333 | db_symtab_t *stab = &db_symtab; |
| 334 | Elf_SymElf64_Sym *symp = (Elf_SymElf64_Sym *)sym; |
| 335 | char *strtab; |
| 336 | |
| 337 | if (sym == NULL((void *)0)) { |
| 338 | *namep = NULL((void *)0); |
| 339 | return; |
| 340 | } |
| 341 | |
| 342 | if (stab->private == NULL((void *)0)) |
| 343 | return; |
| 344 | |
| 345 | if (namep) { |
| 346 | strtab = db_elf_find_strtab(stab); |
| 347 | if (strtab == NULL((void *)0)) |
| 348 | *namep = NULL((void *)0); |
| 349 | else |
| 350 | *namep = strtab + symp->st_name; |
| 351 | } |
| 352 | |
| 353 | if (valuep) |
| 354 | *valuep = symp->st_value; |
| 355 | } |
| 356 | |
| 357 | /* |
| 358 | * Return the file and line number of the current program counter |
| 359 | * if we can find the appropriate debugging symbol. |
| 360 | */ |
| 361 | int |
| 362 | db_elf_line_at_pc(Elf_SymElf64_Sym *cursym, char **filename, |
| 363 | int *linenum, db_expr_t off) |
| 364 | { |
| 365 | db_symtab_t *stab = &db_symtab; |
| 366 | static char path[PATH_MAX1024]; |
| 367 | const char *linetab, *dirname, *basename; |
| 368 | size_t linetab_size; |
| 369 | |
| 370 | if (stab->private == NULL((void *)0)) |
| 371 | return (0); |
| 372 | |
| 373 | linetab = db_elf_find_section(stab, &linetab_size, ".debug_line"); |
| 374 | if (linetab == NULL((void *)0)) |
| 375 | return (0); |
| 376 | |
| 377 | if (!db_dwarf_line_at_pc(linetab, linetab_size, off, |
| 378 | &dirname, &basename, linenum)) |
| 379 | return (0); |
| 380 | |
| 381 | if (dirname == NULL((void *)0)) |
| 382 | strlcpy(path, basename, sizeof(path)); |
| 383 | else |
| 384 | snprintf(path, sizeof(path), "%s/%s", dirname, basename); |
| 385 | *filename = path; |
| 386 | return (1); |
| 387 | } |
| 388 | |
| 389 | void |
| 390 | db_elf_sym_forall(db_forall_func_t db_forall_func, void *arg) |
| 391 | { |
| 392 | db_symtab_t *stab = &db_symtab; |
| 393 | char *strtab; |
| 394 | static char suffix[2]; |
| 395 | Elf_SymElf64_Sym *symp, *symtab_start, *symtab_end; |
| 396 | |
| 397 | if (stab->private == NULL((void *)0)) |
| 398 | return; |
| 399 | |
| 400 | symtab_start = STAB_TO_SYMSTART(stab)((Elf64_Sym *)((stab)->start)); |
| 401 | symtab_end = STAB_TO_SYMEND(stab)((Elf64_Sym *)((stab)->end)); |
| 402 | |
| 403 | strtab = db_elf_find_strtab(stab); |
| 404 | if (strtab == NULL((void *)0)) |
| 405 | return; |
| 406 | |
| 407 | for (symp = symtab_start; symp < symtab_end; symp++) |
| 408 | if (symp->st_name != 0) { |
| 409 | suffix[1] = '\0'; |
| 410 | switch (ELF_ST_TYPE(symp->st_info)(((unsigned int) symp->st_info) & 0xf)) { |
| 411 | case STT_OBJECT1: |
| 412 | suffix[0] = '+'; |
| 413 | break; |
| 414 | case STT_FUNC2: |
| 415 | suffix[0] = '*'; |
| 416 | break; |
| 417 | case STT_SECTION3: |
| 418 | suffix[0] = '&'; |
| 419 | break; |
| 420 | case STT_FILE4: |
| 421 | suffix[0] = '/'; |
| 422 | break; |
| 423 | default: |
| 424 | suffix[0] = '\0'; |
| 425 | } |
| 426 | (*db_forall_func)(symp, |
| 427 | strtab + symp->st_name, suffix, 0, arg); |
| 428 | } |
| 429 | } |
| 430 | |
| 431 | Elf_SymElf64_Sym * |
| 432 | db_symbol_by_name(char *name, db_expr_t *valuep) |
| 433 | { |
| 434 | Elf_SymElf64_Sym *sym; |
| 435 | |
| 436 | sym = db_elf_sym_lookup(name); |
| 437 | if (sym == NULL((void *)0)) |
| 438 | return (NULL((void *)0)); |
| 439 | db_symbol_values(sym, &name, valuep); |
| 440 | return (sym); |
| 441 | } |