1 /* $OpenBSD: db_elf.c,v 1.3 2001/08/19 16:25:00 art 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 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the NetBSD 23 * Foundation, Inc. and its contributors. 24 * 4. Neither the name of The NetBSD Foundation nor the names of its 25 * contributors may be used to endorse or promote products derived 26 * from this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 29 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 30 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 31 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 32 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 33 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 34 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 35 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 36 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 37 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 38 * POSSIBILITY OF SUCH DAMAGE. 39 */ 40 41 #include <sys/types.h> 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/proc.h> 45 #include <sys/exec.h> 46 47 #include <machine/db_machdep.h> 48 49 #include <ddb/db_sym.h> 50 #include <ddb/db_output.h> 51 #include <ddb/db_extern.h> 52 53 #ifdef DB_ELF_SYMBOLS 54 55 #ifndef DB_ELFSIZE 56 #error Must define DB_ELFSIZE! 57 #endif 58 59 #define ELFSIZE DB_ELFSIZE 60 61 #include <sys/exec_elf.h> 62 63 static char *db_elf_find_strtab __P((db_symtab_t *)); 64 65 #define STAB_TO_SYMSTART(stab) ((Elf_Sym *)((stab)->start)) 66 #define STAB_TO_SYMEND(stab) ((Elf_Sym *)((stab)->end)) 67 #define STAB_TO_EHDR(stab) ((Elf_Ehdr *)((stab)->private)) 68 #define STAB_TO_SHDR(stab, e) ((Elf_Shdr *)((stab)->private + (e)->e_shoff)) 69 70 boolean_t db_elf_sym_init __P((int, void *, void *, const char *)); 71 db_sym_t db_elf_lookup __P((db_symtab_t *, char *)); 72 db_sym_t db_elf_search_symbol __P((db_symtab_t *, db_addr_t, 73 db_strategy_t, db_expr_t *)); 74 void db_elf_symbol_values __P((db_symtab_t *, db_sym_t, 75 char **, db_expr_t *)); 76 boolean_t db_elf_line_at_pc __P((db_symtab_t *, db_sym_t, 77 char **, int *, db_expr_t)); 78 boolean_t db_elf_sym_numargs __P((db_symtab_t *, db_sym_t, int *, 79 char **)); 80 void db_elf_forall __P((db_symtab_t *, 81 db_forall_func_t db_forall_func, void *)); 82 83 db_symformat_t db_symformat_elf = { 84 "ELF", 85 db_elf_sym_init, 86 db_elf_lookup, 87 db_elf_search_symbol, 88 db_elf_symbol_values, 89 db_elf_line_at_pc, 90 db_elf_sym_numargs, 91 db_elf_forall 92 }; 93 94 /* 95 * Find the symbol table and strings; tell ddb about them. 96 */ 97 boolean_t 98 db_elf_sym_init(symsize, symtab, esymtab, name) 99 int symsize; /* size of symbol table */ 100 void *symtab; /* pointer to start of symbol table */ 101 void *esymtab; /* pointer to end of string table, 102 for checking - rounded up to integer 103 boundary */ 104 const char *name; 105 { 106 Elf_Ehdr *elf; 107 Elf_Shdr *shp; 108 Elf_Sym *symp, *symtab_start, *symtab_end; 109 char *shstrtab, *strtab_start, *strtab_end; 110 int i; 111 char *errstr = ""; 112 113 if (ALIGNED_POINTER(symtab, long) == 0) { 114 printf("[ %s symbol table has bad start address %p ]\n", 115 name, symtab); 116 return (FALSE); 117 } 118 119 symtab_start = symtab_end = NULL; 120 strtab_start = strtab_end = NULL; 121 122 /* 123 * The format of the symbols loaded by the boot program is: 124 * 125 * Elf exec header 126 * first section header 127 * . . . 128 * . . . 129 * last section header 130 * first symbol or string table section 131 * . . . 132 * . . . 133 * last symbol or string table section 134 */ 135 136 /* 137 * Validate the Elf header. 138 */ 139 elf = (Elf_Ehdr *)symtab; 140 if (memcmp(elf->e_ident, ELFMAG, SELFMAG) != 0 || 141 elf->e_ident[EI_CLASS] != ELFCLASS) { 142 errstr = "bad magic"; 143 goto badheader; 144 } 145 146 if (elf->e_machine != ELF_TARG_MACH) { 147 errstr = "bad e_machine"; 148 goto badheader; 149 } 150 151 /* 152 * Find the section header string table (.shstrtab), and look up 153 * the symbol table (.symtab) and string table (.strtab) via their 154 * names in shstrtab, rather than by table type. 155 * This works in the presence of multiple string tables, such as 156 * stabs data found when booting bsd.gdb. 157 */ 158 shp = (Elf_Shdr *)((char *)symtab + elf->e_shoff); 159 shstrtab = (char*)symtab + shp[elf->e_shstrndx].sh_offset; 160 for (i = 0; i < elf->e_shnum; i++) { 161 if (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0) { 162 strtab_start = (char *)symtab + shp[i].sh_offset; 163 strtab_end = (char *)symtab + shp[i].sh_offset + 164 shp[i].sh_size; 165 } else if (strcmp(".symtab", shstrtab+shp[i].sh_name) == 0) { 166 symtab_start = (Elf_Sym *)((char *)symtab + 167 shp[i].sh_offset); 168 symtab_end = (Elf_Sym *)((char *)symtab + 169 shp[i].sh_offset + shp[i].sh_size); 170 } 171 } 172 173 /* 174 * Now, sanity check the symbols against the string table. 175 */ 176 if (symtab_start == NULL || strtab_start == NULL || 177 ALIGNED_POINTER(symtab_start, long) == 0 || 178 ALIGNED_POINTER(strtab_start, long) == 0) { 179 errstr = "symtab unaligned"; 180 goto badheader; 181 } 182 for (symp = symtab_start; symp < symtab_end; symp++) 183 if (symp->st_name + strtab_start > strtab_end) { 184 errstr = "symtab corrupted"; 185 goto badheader; 186 } 187 188 /* 189 * Link the symbol table into the debugger. 190 */ 191 if (db_add_symbol_table((char *)symtab_start, 192 (char *)symtab_end, name, (char *)symtab) != -1) { 193 printf("[ using %lu bytes of %s ELF symbol table ]\n", 194 (u_long)roundup(((char *)esymtab - (char *)symtab), 195 sizeof(u_long)), name); 196 return (TRUE); 197 } 198 199 return (FALSE); 200 201 badheader: 202 printf("[ %s ELF symbol table not valid: %s ]\n", name, errstr); 203 return (FALSE); 204 } 205 206 /* 207 * Internal helper function - return a pointer to the string table 208 * for the current symbol table. 209 */ 210 static char * 211 db_elf_find_strtab(stab) 212 db_symtab_t *stab; 213 { 214 Elf_Ehdr *elf = STAB_TO_EHDR(stab); 215 Elf_Shdr *shp = STAB_TO_SHDR(stab, elf); 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 (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0) 222 return ((char*)elf + shp[i].sh_offset); 223 } 224 225 return (NULL); 226 } 227 228 /* 229 * Lookup the symbol with the given name. 230 */ 231 db_sym_t 232 db_elf_lookup(stab, symstr) 233 db_symtab_t *stab; 234 char *symstr; 235 { 236 Elf_Sym *symp, *symtab_start, *symtab_end; 237 char *strtab; 238 239 symtab_start = STAB_TO_SYMSTART(stab); 240 symtab_end = STAB_TO_SYMEND(stab); 241 242 strtab = db_elf_find_strtab(stab); 243 if (strtab == NULL) 244 return ((db_sym_t)0); 245 246 for (symp = symtab_start; symp < symtab_end; symp++) { 247 if (symp->st_name != 0 && 248 db_eqname(strtab + symp->st_name, symstr, 0)) 249 return ((db_sym_t)symp); 250 } 251 252 return ((db_sym_t)0); 253 } 254 255 /* 256 * Search for the symbol with the given address (matching within the 257 * provided threshold). 258 */ 259 db_sym_t 260 db_elf_search_symbol(symtab, off, strategy, diffp) 261 db_symtab_t *symtab; 262 db_addr_t off; 263 db_strategy_t strategy; 264 db_expr_t *diffp; /* in/out */ 265 { 266 Elf_Sym *rsymp, *symp, *symtab_start, *symtab_end; 267 db_expr_t diff = *diffp; 268 269 symtab_start = STAB_TO_SYMSTART(symtab); 270 symtab_end = STAB_TO_SYMEND(symtab); 271 272 rsymp = NULL; 273 274 for (symp = symtab_start; symp < symtab_end; symp++) { 275 if (symp->st_name == 0) 276 continue; 277 #if 0 278 /* This prevents me from seeing anythin in locore.s -- eeh */ 279 if (ELF_SYM_TYPE(symp->st_info) != Elf_estt_object && 280 ELF_SYM_TYPE(symp->st_info) != Elf_estt_func) 281 continue; 282 #endif 283 284 if (off >= symp->st_value) { 285 if ((off - symp->st_value) < diff) { 286 diff = off - symp->st_value; 287 rsymp = symp; 288 if (diff == 0) { 289 if (strategy == DB_STGY_PROC && 290 ELFDEFNNAME(ST_TYPE)(symp->st_info) 291 == STT_FUNC && 292 ELFDEFNNAME(ST_BIND)(symp->st_info) 293 != STB_LOCAL) 294 break; 295 if (strategy == DB_STGY_ANY && 296 ELFDEFNNAME(ST_BIND)(symp->st_info) 297 != STB_LOCAL) 298 break; 299 } 300 } else if ((off - symp->st_value) == diff) { 301 if (rsymp == NULL) 302 rsymp = symp; 303 else if (ELFDEFNNAME(ST_BIND)(rsymp->st_info) 304 == STB_LOCAL && 305 ELFDEFNNAME(ST_BIND)(symp->st_info) 306 != STB_LOCAL) { 307 /* pick the external symbol */ 308 rsymp = symp; 309 } 310 } 311 } 312 } 313 314 if (rsymp == NULL) 315 *diffp = off; 316 else 317 *diffp = diff; 318 319 return ((db_sym_t)rsymp); 320 } 321 322 /* 323 * Return the name and value for a symbol. 324 */ 325 void 326 db_elf_symbol_values(symtab, sym, namep, valuep) 327 db_symtab_t *symtab; 328 db_sym_t sym; 329 char **namep; 330 db_expr_t *valuep; 331 { 332 Elf_Sym *symp = (Elf_Sym *)sym; 333 char *strtab; 334 335 if (namep) { 336 strtab = db_elf_find_strtab(symtab); 337 if (strtab == NULL) 338 *namep = NULL; 339 else 340 *namep = strtab + symp->st_name; 341 } 342 343 if (valuep) 344 *valuep = symp->st_value; 345 } 346 347 /* 348 * Return the file and line number of the current program counter 349 * if we can find the appropriate debugging symbol. 350 */ 351 boolean_t 352 db_elf_line_at_pc(symtab, cursym, filename, linenum, off) 353 db_symtab_t *symtab; 354 db_sym_t cursym; 355 char **filename; 356 int *linenum; 357 db_expr_t off; 358 { 359 360 /* 361 * XXX We don't support this (yet). 362 */ 363 return (FALSE); 364 } 365 366 /* 367 * Returns the number of arguments to a function and their 368 * names if we can find the appropriate debugging symbol. 369 */ 370 boolean_t 371 db_elf_sym_numargs(symtab, cursym, nargp, argnamep) 372 db_symtab_t *symtab; 373 db_sym_t cursym; 374 int *nargp; 375 char **argnamep; 376 { 377 378 /* 379 * XXX We don't support this (yet). 380 */ 381 return (FALSE); 382 } 383 384 void 385 db_elf_forall(stab, db_forall_func, arg) 386 db_symtab_t *stab; 387 db_forall_func_t db_forall_func; 388 void *arg; 389 { 390 char *strtab; 391 static char suffix[2]; 392 Elf_Sym *symp, *symtab_start, *symtab_end; 393 394 symtab_start = STAB_TO_SYMSTART(stab); 395 symtab_end = STAB_TO_SYMEND(stab); 396 397 strtab = db_elf_find_strtab(stab); 398 if (strtab == NULL) 399 return; 400 401 for (symp = symtab_start; symp < symtab_end; symp++) 402 if (symp->st_name != 0) { 403 suffix[1] = '\0'; 404 switch (ELFDEFNNAME(ST_TYPE)(symp->st_info)) { 405 case STT_OBJECT: 406 suffix[0] = '+'; 407 break; 408 case STT_FUNC: 409 suffix[0] = '*'; 410 break; 411 case STT_SECTION: 412 suffix[0] = '&'; 413 break; 414 case STT_FILE: 415 suffix[0] = '/'; 416 break; 417 default: 418 suffix[0] = '\0'; 419 } 420 (*db_forall_func)(stab, (db_sym_t)symp, 421 strtab + symp->st_name, suffix, 0, arg); 422 } 423 return; 424 } 425 #endif /* DB_ELF_SYMBOLS */ 426