1 /* $NetBSD: db_elf.c,v 1.11 2000/05/22 14:49:10 jhawk Exp $ */ 2 3 /*- 4 * Copyright (c) 1997 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the NetBSD 22 * Foundation, Inc. and its contributors. 23 * 4. Neither the name of The NetBSD Foundation nor the names of its 24 * contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 37 * POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 #include <sys/types.h> 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/proc.h> 44 45 #include <machine/db_machdep.h> 46 47 #include <ddb/db_sym.h> 48 #include <ddb/db_output.h> 49 #include <ddb/db_extern.h> 50 51 #ifdef DB_ELF_SYMBOLS 52 53 #ifndef DB_ELFSIZE 54 #error Must define DB_ELFSIZE! 55 #endif 56 57 #define ELFSIZE DB_ELFSIZE 58 59 #include <sys/exec_elf.h> 60 61 static char *db_elf_find_strtab __P((db_symtab_t *)); 62 63 #define STAB_TO_SYMSTART(stab) ((Elf_Sym *)((stab)->start)) 64 #define STAB_TO_SYMEND(stab) ((Elf_Sym *)((stab)->end)) 65 #define STAB_TO_EHDR(stab) ((Elf_Ehdr *)((stab)->private)) 66 #define STAB_TO_SHDR(stab, e) ((Elf_Shdr *)((stab)->private + (e)->e_shoff)) 67 68 boolean_t db_elf_sym_init __P((int, void *, void *, const char *)); 69 db_sym_t db_elf_lookup __P((db_symtab_t *, char *)); 70 db_sym_t db_elf_search_symbol __P((db_symtab_t *, db_addr_t, 71 db_strategy_t, db_expr_t *)); 72 void db_elf_symbol_values __P((db_symtab_t *, db_sym_t, 73 char **, db_expr_t *)); 74 boolean_t db_elf_line_at_pc __P((db_symtab_t *, db_sym_t, 75 char **, int *, db_expr_t)); 76 boolean_t db_elf_sym_numargs __P((db_symtab_t *, db_sym_t, int *, 77 char **)); 78 void db_elf_forall __P((db_symtab_t *, 79 db_forall_func_t db_forall_func, void *)); 80 81 db_symformat_t db_symformat_elf = { 82 "ELF", 83 db_elf_sym_init, 84 db_elf_lookup, 85 db_elf_search_symbol, 86 db_elf_symbol_values, 87 db_elf_line_at_pc, 88 db_elf_sym_numargs, 89 db_elf_forall 90 }; 91 92 /* 93 * Find the symbol table and strings; tell ddb about them. 94 */ 95 boolean_t 96 db_elf_sym_init(symsize, symtab, esymtab, name) 97 int symsize; /* size of symbol table */ 98 void *symtab; /* pointer to start of symbol table */ 99 void *esymtab; /* pointer to end of string table, 100 for checking - rounded up to integer 101 boundary */ 102 const char *name; 103 { 104 Elf_Ehdr *elf; 105 Elf_Shdr *shp; 106 Elf_Sym *symp, *symtab_start, *symtab_end; 107 char *strtab_start, *strtab_end; 108 int i; 109 110 if (ALIGNED_POINTER(symtab, long) == 0) { 111 printf("[ %s symbol table has bad start address %p ]\n", 112 name, symtab); 113 return (FALSE); 114 } 115 116 symtab_start = symtab_end = NULL; 117 strtab_start = strtab_end = NULL; 118 119 /* 120 * The format of the symbols loaded by the boot program is: 121 * 122 * Elf exec header 123 * first section header 124 * . . . 125 * . . . 126 * last section header 127 * first symbol or string table section 128 * . . . 129 * . . . 130 * last symbol or string table section 131 */ 132 133 /* 134 * Validate the Elf header. 135 */ 136 elf = (Elf_Ehdr *)symtab; 137 if (memcmp(elf->e_ident, ELFMAG, SELFMAG) != 0 || 138 elf->e_ident[EI_CLASS] != ELFCLASS) 139 goto badheader; 140 141 switch (elf->e_machine) { 142 143 ELFDEFNNAME(MACHDEP_ID_CASES) 144 145 default: 146 goto badheader; 147 } 148 149 /* 150 * We need to avoid the section header string table (small string 151 * table which names the sections). We do this by assuming that 152 * the following two conditions will be true: 153 * 154 * (1) .shstrtab will be smaller than one page. 155 * (2) .strtab will be larger than one page. 156 * 157 * When we encounter what we think is the .shstrtab, we change 158 * its section type Elf_sht_null so that it will be ignored 159 * later. 160 */ 161 shp = (Elf_Shdr *)((char *)symtab + elf->e_shoff); 162 for (i = 0; i < elf->e_shnum; i++) { 163 switch (shp[i].sh_type) { 164 case SHT_STRTAB: 165 if (shp[i].sh_size < NBPG) { 166 shp[i].sh_type = SHT_NULL; 167 continue; 168 } 169 if (strtab_start != NULL) 170 goto multiple_strtab; 171 strtab_start = (char *)symtab + shp[i].sh_offset; 172 strtab_end = (char *)symtab + shp[i].sh_offset + 173 shp[i].sh_size; 174 break; 175 176 case SHT_SYMTAB: 177 if (symtab_start != NULL) 178 goto multiple_symtab; 179 symtab_start = (Elf_Sym *)((char *)symtab + 180 shp[i].sh_offset); 181 symtab_end = (Elf_Sym *)((char *)symtab + 182 shp[i].sh_offset + shp[i].sh_size); 183 break; 184 185 default: 186 /* Ignore all other sections. */ 187 break; 188 } 189 } 190 191 /* 192 * Now, sanity check the symbols against the string table. 193 */ 194 if (symtab_start == NULL || strtab_start == NULL || 195 ALIGNED_POINTER(symtab_start, long) == 0 || 196 ALIGNED_POINTER(strtab_start, long) == 0) 197 goto badheader; 198 for (symp = symtab_start; symp < symtab_end; symp++) 199 if (symp->st_name + strtab_start > strtab_end) 200 goto badheader; 201 202 /* 203 * Link the symbol table into the debugger. 204 */ 205 if (db_add_symbol_table((char *)symtab_start, 206 (char *)symtab_end, name, (char *)symtab) != -1) { 207 printf("[ preserving %lu bytes of %s ELF symbol table ]\n", 208 (u_long)roundup(((char *)esymtab - (char *)symtab), 209 sizeof(u_long)), name); 210 return (TRUE); 211 } 212 213 return (FALSE); 214 215 badheader: 216 printf("[ %s ELF symbol table not valid ]\n", name); 217 return (FALSE); 218 219 multiple_strtab: 220 printf("[ %s has multiple ELF string tables ]\n", name); 221 return (FALSE); 222 223 multiple_symtab: 224 printf("[ %s has multiple ELF symbol tables ]\n", name); 225 return (FALSE); 226 } 227 228 /* 229 * Internal helper function - return a pointer to the string table 230 * for the current symbol table. 231 */ 232 static char * 233 db_elf_find_strtab(stab) 234 db_symtab_t *stab; 235 { 236 Elf_Ehdr *elf = STAB_TO_EHDR(stab); 237 Elf_Shdr *shp = STAB_TO_SHDR(stab, elf); 238 int i; 239 240 for (i = 0; i < elf->e_shnum; i++) { 241 if (shp[i].sh_type == SHT_STRTAB) 242 return (stab->private + shp[i].sh_offset); 243 } 244 245 return (NULL); 246 } 247 248 /* 249 * Lookup the symbol with the given name. 250 */ 251 db_sym_t 252 db_elf_lookup(stab, symstr) 253 db_symtab_t *stab; 254 char *symstr; 255 { 256 Elf_Sym *symp, *symtab_start, *symtab_end; 257 char *strtab; 258 259 symtab_start = STAB_TO_SYMSTART(stab); 260 symtab_end = STAB_TO_SYMEND(stab); 261 262 strtab = db_elf_find_strtab(stab); 263 if (strtab == NULL) 264 return ((db_sym_t)0); 265 266 for (symp = symtab_start; symp < symtab_end; symp++) { 267 if (symp->st_name != 0 && 268 db_eqname(strtab + symp->st_name, symstr, 0)) 269 return ((db_sym_t)symp); 270 } 271 272 return ((db_sym_t)0); 273 } 274 275 /* 276 * Search for the symbol with the given address (matching within the 277 * provided threshold). 278 */ 279 db_sym_t 280 db_elf_search_symbol(symtab, off, strategy, diffp) 281 db_symtab_t *symtab; 282 db_addr_t off; 283 db_strategy_t strategy; 284 db_expr_t *diffp; /* in/out */ 285 { 286 Elf_Sym *rsymp, *symp, *symtab_start, *symtab_end; 287 db_expr_t diff = *diffp; 288 289 symtab_start = STAB_TO_SYMSTART(symtab); 290 symtab_end = STAB_TO_SYMEND(symtab); 291 292 rsymp = NULL; 293 294 for (symp = symtab_start; symp < symtab_end; symp++) { 295 if (symp->st_name == 0) 296 continue; 297 #if 0 298 /* This prevents me from seeing anythin in locore.s -- eeh */ 299 if (ELF_SYM_TYPE(symp->st_info) != Elf_estt_object && 300 ELF_SYM_TYPE(symp->st_info) != Elf_estt_func) 301 continue; 302 #endif 303 304 if (off >= symp->st_value) { 305 if ((off - symp->st_value) < diff) { 306 diff = off - symp->st_value; 307 rsymp = symp; 308 if (diff == 0) { 309 if (strategy == DB_STGY_PROC && 310 ELFDEFNNAME(ST_TYPE)(symp->st_info) 311 == STT_FUNC && 312 ELFDEFNNAME(ST_BIND)(symp->st_info) 313 != STB_LOCAL) 314 break; 315 if (strategy == DB_STGY_ANY && 316 ELFDEFNNAME(ST_BIND)(symp->st_info) 317 != STB_LOCAL) 318 break; 319 } 320 } else if ((off - symp->st_value) == diff) { 321 if (rsymp == NULL) 322 rsymp = symp; 323 else if (ELFDEFNNAME(ST_BIND)(rsymp->st_info) 324 == STB_LOCAL && 325 ELFDEFNNAME(ST_BIND)(symp->st_info) 326 != STB_LOCAL) { 327 /* pick the external symbol */ 328 rsymp = symp; 329 } 330 } 331 } 332 } 333 334 if (rsymp == NULL) 335 *diffp = off; 336 else 337 *diffp = diff; 338 339 return ((db_sym_t)rsymp); 340 } 341 342 /* 343 * Return the name and value for a symbol. 344 */ 345 void 346 db_elf_symbol_values(symtab, sym, namep, valuep) 347 db_symtab_t *symtab; 348 db_sym_t sym; 349 char **namep; 350 db_expr_t *valuep; 351 { 352 Elf_Sym *symp = (Elf_Sym *)sym; 353 char *strtab; 354 355 if (namep) { 356 strtab = db_elf_find_strtab(symtab); 357 if (strtab == NULL) 358 *namep = NULL; 359 else 360 *namep = strtab + symp->st_name; 361 } 362 363 if (valuep) 364 *valuep = symp->st_value; 365 } 366 367 /* 368 * Return the file and line number of the current program counter 369 * if we can find the appropriate debugging symbol. 370 */ 371 boolean_t 372 db_elf_line_at_pc(symtab, cursym, filename, linenum, off) 373 db_symtab_t *symtab; 374 db_sym_t cursym; 375 char **filename; 376 int *linenum; 377 db_expr_t off; 378 { 379 380 /* 381 * XXX We don't support this (yet). 382 */ 383 return (FALSE); 384 } 385 386 /* 387 * Returns the number of arguments to a function and their 388 * names if we can find the appropriate debugging symbol. 389 */ 390 boolean_t 391 db_elf_sym_numargs(symtab, cursym, nargp, argnamep) 392 db_symtab_t *symtab; 393 db_sym_t cursym; 394 int *nargp; 395 char **argnamep; 396 { 397 398 /* 399 * XXX We don't support this (yet). 400 */ 401 return (FALSE); 402 } 403 404 void 405 db_elf_forall(stab, db_forall_func, arg) 406 db_symtab_t *stab; 407 db_forall_func_t db_forall_func; 408 void *arg; 409 { 410 char *strtab; 411 static char suffix[2]; 412 Elf_Sym *symp, *symtab_start, *symtab_end; 413 414 symtab_start = STAB_TO_SYMSTART(stab); 415 symtab_end = STAB_TO_SYMEND(stab); 416 417 strtab = db_elf_find_strtab(stab); 418 if (strtab == NULL) 419 return; 420 421 for (symp = symtab_start; symp < symtab_end; symp++) 422 if (symp->st_name != 0) { 423 suffix[1] = '\0'; 424 switch (ELFDEFNNAME(ST_TYPE)(symp->st_info)) { 425 case STT_OBJECT: 426 suffix[0] = '+'; 427 break; 428 case STT_FUNC: 429 suffix[0] = '*'; 430 break; 431 case STT_SECTION: 432 suffix[0] = '&'; 433 break; 434 case STT_FILE: 435 suffix[0] = '/'; 436 break; 437 default: 438 suffix[0] = '\0'; 439 } 440 (*db_forall_func)(stab, (db_sym_t)symp, 441 strtab + symp->st_name, suffix, 0, arg); 442 } 443 return; 444 } 445 #endif /* DB_ELF_SYMBOLS */ 446