1 /* $NetBSD: db_elf.c,v 1.20 2002/02/15 07:33:50 simonb 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/cdefs.h> 41 __KERNEL_RCSID(0, "$NetBSD: db_elf.c,v 1.20 2002/02/15 07:33:50 simonb Exp $"); 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/proc.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(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 static boolean_t db_elf_sym_init(int, void *, void *, const char *); 71 static db_sym_t db_elf_lookup(db_symtab_t *, char *); 72 static db_sym_t db_elf_search_symbol(db_symtab_t *, db_addr_t, db_strategy_t, 73 db_expr_t *); 74 static void db_elf_symbol_values(db_symtab_t *, db_sym_t, char **, 75 db_expr_t *); 76 static boolean_t db_elf_line_at_pc(db_symtab_t *, db_sym_t, char **, int *, 77 db_expr_t); 78 static boolean_t db_elf_sym_numargs(db_symtab_t *, db_sym_t, int *, char **); 79 static void db_elf_forall(db_symtab_t *, db_forall_func_t db_forall_func, 80 void *); 81 82 const db_symformat_t db_symformat_elf = { 83 "ELF", 84 db_elf_sym_init, 85 db_elf_lookup, 86 db_elf_search_symbol, 87 db_elf_symbol_values, 88 db_elf_line_at_pc, 89 db_elf_sym_numargs, 90 db_elf_forall 91 }; 92 93 /* 94 * Find the symbol table and strings; tell ddb about them. 95 */ 96 static boolean_t 97 db_elf_sym_init( 98 int symsize, /* size of symbol table */ 99 void *symtab, /* pointer to start of symbol table */ 100 void *esymtab, /* pointer to end of string table, 101 for checking - rounded up to integer 102 boundary */ 103 const char *name 104 ) 105 { 106 Elf_Ehdr *elf; 107 Elf_Shdr *shp; 108 Elf_Sym *symp, *symtab_start, *symtab_end; 109 char *strtab_start, *strtab_end; 110 int i, j; 111 112 if (ALIGNED_POINTER(symtab, long) == 0) { 113 printf("[ %s symbol table has bad start address %p ]\n", 114 name, symtab); 115 return (FALSE); 116 } 117 118 symtab_start = symtab_end = NULL; 119 strtab_start = strtab_end = NULL; 120 121 /* 122 * The format of the symbols loaded by the boot program is: 123 * 124 * Elf exec header 125 * first section header 126 * . . . 127 * . . . 128 * last section header 129 * first symbol or string table section 130 * . . . 131 * . . . 132 * last symbol or string table section 133 */ 134 135 /* 136 * Validate the Elf header. 137 */ 138 elf = (Elf_Ehdr *)symtab; 139 if (memcmp(elf->e_ident, ELFMAG, SELFMAG) != 0 || 140 elf->e_ident[EI_CLASS] != ELFCLASS) 141 goto badheader; 142 143 switch (elf->e_machine) { 144 145 ELFDEFNNAME(MACHDEP_ID_CASES) 146 147 default: 148 goto badheader; 149 } 150 151 /* 152 * Find the first (and, we hope, only) SHT_SYMTAB section in 153 * the file, and the SHT_STRTAB section that goes with it. 154 */ 155 if (elf->e_shoff == 0) 156 goto badheader; 157 shp = (Elf_Shdr *)((char *)symtab + elf->e_shoff); 158 for (i = 0; i < elf->e_shnum; i++) { 159 if (shp[i].sh_type == SHT_SYMTAB) { 160 if (shp[i].sh_offset == 0) 161 continue; 162 /* Got the symbol table. */ 163 symtab_start = (Elf_Sym *)((char *)symtab + 164 shp[i].sh_offset); 165 symtab_end = (Elf_Sym *)((char *)symtab + 166 shp[i].sh_offset + shp[i].sh_size); 167 /* Find the string table to go with it. */ 168 j = shp[i].sh_link; 169 if (shp[j].sh_offset == 0) 170 continue; 171 strtab_start = (char *)symtab + shp[j].sh_offset; 172 strtab_end = (char *)symtab + shp[j].sh_offset + 173 shp[j].sh_size; 174 /* There should only be one symbol table. */ 175 break; 176 } 177 } 178 179 /* 180 * Now, sanity check the symbols against the string table. 181 */ 182 if (symtab_start == NULL || strtab_start == NULL || 183 ALIGNED_POINTER(symtab_start, long) == 0 || 184 ALIGNED_POINTER(strtab_start, long) == 0) 185 goto badheader; 186 for (symp = symtab_start; symp < symtab_end; symp++) 187 if (symp->st_name + strtab_start > strtab_end) 188 goto badheader; 189 190 /* 191 * Link the symbol table into the debugger. 192 */ 193 if (db_add_symbol_table((char *)symtab_start, 194 (char *)symtab_end, name, (char *)symtab) != -1) { 195 printf("[ using %lu bytes of %s ELF symbol table ]\n", 196 (u_long)roundup(((char *)esymtab - (char *)symtab), 197 sizeof(u_long)), name); 198 return (TRUE); 199 } 200 201 return (FALSE); 202 203 badheader: 204 printf("[ %s ELF symbol table not valid ]\n", name); 205 return (FALSE); 206 } 207 208 /* 209 * Internal helper function - return a pointer to the string table 210 * for the current symbol table. 211 */ 212 static char * 213 db_elf_find_strtab(db_symtab_t *stab) 214 { 215 Elf_Ehdr *elf = STAB_TO_EHDR(stab); 216 Elf_Shdr *shp = STAB_TO_SHDR(stab, elf); 217 int i; 218 219 /* 220 * We don't load ELF header for ELF modules. 221 * Find out if this is a loadable module. If so, 222 * string table comes right after symbol table. 223 */ 224 if ((Elf_Sym *)elf == STAB_TO_SYMSTART(stab)) { 225 return ((char *)STAB_TO_SYMEND(stab)); 226 } 227 for (i = 0; i < elf->e_shnum; i++) { 228 if (shp[i].sh_type == SHT_SYMTAB) 229 return ((char*)elf + shp[shp[i].sh_link].sh_offset); 230 } 231 232 return (NULL); 233 } 234 235 /* 236 * Lookup the symbol with the given name. 237 */ 238 static db_sym_t 239 db_elf_lookup(db_symtab_t *stab, char *symstr) 240 { 241 Elf_Sym *symp, *symtab_start, *symtab_end; 242 char *strtab; 243 244 symtab_start = STAB_TO_SYMSTART(stab); 245 symtab_end = STAB_TO_SYMEND(stab); 246 247 strtab = db_elf_find_strtab(stab); 248 if (strtab == NULL) 249 return ((db_sym_t)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 ((db_sym_t)symp); 255 } 256 257 return ((db_sym_t)0); 258 } 259 260 /* 261 * Search for the symbol with the given address (matching within the 262 * provided threshold). 263 */ 264 static db_sym_t 265 db_elf_search_symbol(db_symtab_t *symtab, db_addr_t off, db_strategy_t strategy, 266 db_expr_t *diffp) 267 { 268 Elf_Sym *rsymp, *symp, *symtab_start, *symtab_end; 269 db_expr_t diff = *diffp; 270 271 symtab_start = STAB_TO_SYMSTART(symtab); 272 symtab_end = STAB_TO_SYMEND(symtab); 273 274 rsymp = NULL; 275 276 for (symp = symtab_start; symp < symtab_end; symp++) { 277 if (symp->st_name == 0) 278 continue; 279 #if 0 280 /* This prevents me from seeing anythin in locore.s -- eeh */ 281 if (ELF_SYM_TYPE(symp->st_info) != Elf_estt_object && 282 ELF_SYM_TYPE(symp->st_info) != Elf_estt_func) 283 continue; 284 #endif 285 286 if (off >= symp->st_value) { 287 if ((off - symp->st_value) < diff) { 288 diff = off - symp->st_value; 289 rsymp = symp; 290 if (diff == 0) { 291 if (strategy == DB_STGY_PROC && 292 ELFDEFNNAME(ST_TYPE)(symp->st_info) 293 == STT_FUNC && 294 ELFDEFNNAME(ST_BIND)(symp->st_info) 295 != STB_LOCAL) 296 break; 297 if (strategy == DB_STGY_ANY && 298 ELFDEFNNAME(ST_BIND)(symp->st_info) 299 != STB_LOCAL) 300 break; 301 } 302 } else if ((off - symp->st_value) == diff) { 303 if (rsymp == NULL) 304 rsymp = symp; 305 else if (ELFDEFNNAME(ST_BIND)(rsymp->st_info) 306 == STB_LOCAL && 307 ELFDEFNNAME(ST_BIND)(symp->st_info) 308 != STB_LOCAL) { 309 /* pick the external symbol */ 310 rsymp = symp; 311 } 312 } 313 } 314 } 315 316 if (rsymp == NULL) 317 *diffp = off; 318 else 319 *diffp = diff; 320 321 return ((db_sym_t)rsymp); 322 } 323 324 /* 325 * Return the name and value for a symbol. 326 */ 327 static void 328 db_elf_symbol_values(db_symtab_t *symtab, db_sym_t sym, char **namep, 329 db_expr_t *valuep) 330 { 331 Elf_Sym *symp = (Elf_Sym *)sym; 332 char *strtab; 333 334 if (namep) { 335 strtab = db_elf_find_strtab(symtab); 336 if (strtab == NULL) 337 *namep = NULL; 338 else 339 *namep = strtab + symp->st_name; 340 } 341 342 if (valuep) 343 *valuep = symp->st_value; 344 } 345 346 /* 347 * Return the file and line number of the current program counter 348 * if we can find the appropriate debugging symbol. 349 */ 350 static boolean_t 351 db_elf_line_at_pc(symtab, cursym, filename, linenum, off) 352 db_symtab_t *symtab; 353 db_sym_t cursym; 354 char **filename; 355 int *linenum; 356 db_expr_t off; 357 { 358 359 /* 360 * XXX We don't support this (yet). 361 */ 362 return (FALSE); 363 } 364 365 /* 366 * Returns the number of arguments to a function and their 367 * names if we can find the appropriate debugging symbol. 368 */ 369 static boolean_t 370 db_elf_sym_numargs(db_symtab_t *symtab, db_sym_t cursym, int *nargp, 371 char **argnamep) 372 { 373 374 /* 375 * XXX We don't support this (yet). 376 */ 377 return (FALSE); 378 } 379 380 static void 381 db_elf_forall(db_symtab_t *stab, db_forall_func_t db_forall_func, void *arg) 382 { 383 char *strtab; 384 static char suffix[2]; 385 Elf_Sym *symp, *symtab_start, *symtab_end; 386 387 symtab_start = STAB_TO_SYMSTART(stab); 388 symtab_end = STAB_TO_SYMEND(stab); 389 390 strtab = db_elf_find_strtab(stab); 391 if (strtab == NULL) 392 return; 393 394 for (symp = symtab_start; symp < symtab_end; symp++) 395 if (symp->st_name != 0) { 396 suffix[1] = '\0'; 397 switch (ELFDEFNNAME(ST_TYPE)(symp->st_info)) { 398 case STT_OBJECT: 399 suffix[0] = '+'; 400 break; 401 case STT_FUNC: 402 suffix[0] = '*'; 403 break; 404 case STT_SECTION: 405 suffix[0] = '&'; 406 break; 407 case STT_FILE: 408 suffix[0] = '/'; 409 break; 410 default: 411 suffix[0] = '\0'; 412 } 413 (*db_forall_func)(stab, (db_sym_t)symp, 414 strtab + symp->st_name, suffix, 0, arg); 415 } 416 return; 417 } 418 #endif /* DB_ELF_SYMBOLS */ 419