1 /* 2 * kallsyms.c: in-kernel printing of symbolic oopses and stack traces. 3 * 4 * Rewritten and vastly simplified by Rusty Russell for in-kernel 5 * module loader: 6 * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation 7 * 8 * ChangeLog: 9 * 10 * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com> 11 * Changed the compression method from stem compression to "table lookup" 12 * compression (see scripts/kallsyms.c for a more complete description) 13 */ 14 #include <linux/kallsyms.h> 15 #include <linux/module.h> 16 #include <linux/init.h> 17 #include <linux/seq_file.h> 18 #include <linux/fs.h> 19 #include <linux/err.h> 20 #include <linux/proc_fs.h> 21 #include <linux/sched.h> /* for cond_resched */ 22 #include <linux/mm.h> 23 #include <linux/ctype.h> 24 25 #include <asm/sections.h> 26 27 #ifdef CONFIG_KALLSYMS_ALL 28 #define all_var 1 29 #else 30 #define all_var 0 31 #endif 32 33 /* These will be re-linked against their real values during the second link stage */ 34 extern unsigned long kallsyms_addresses[] __attribute__((weak)); 35 extern unsigned long kallsyms_num_syms __attribute__((weak,section("data"))); 36 extern u8 kallsyms_names[] __attribute__((weak)); 37 38 extern u8 kallsyms_token_table[] __attribute__((weak)); 39 extern u16 kallsyms_token_index[] __attribute__((weak)); 40 41 extern unsigned long kallsyms_markers[] __attribute__((weak)); 42 43 static inline int is_kernel_inittext(unsigned long addr) 44 { 45 if (addr >= (unsigned long)_sinittext 46 && addr <= (unsigned long)_einittext) 47 return 1; 48 return 0; 49 } 50 51 static inline int is_kernel_extratext(unsigned long addr) 52 { 53 if (addr >= (unsigned long)_sextratext 54 && addr <= (unsigned long)_eextratext) 55 return 1; 56 return 0; 57 } 58 59 static inline int is_kernel_text(unsigned long addr) 60 { 61 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) 62 return 1; 63 return in_gate_area_no_task(addr); 64 } 65 66 static inline int is_kernel(unsigned long addr) 67 { 68 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) 69 return 1; 70 return in_gate_area_no_task(addr); 71 } 72 73 static int is_ksym_addr(unsigned long addr) 74 { 75 if (all_var) 76 return is_kernel(addr); 77 78 return is_kernel_text(addr) || is_kernel_inittext(addr) || 79 is_kernel_extratext(addr); 80 } 81 82 /* expand a compressed symbol data into the resulting uncompressed string, 83 given the offset to where the symbol is in the compressed stream */ 84 static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) 85 { 86 int len, skipped_first = 0; 87 u8 *tptr, *data; 88 89 /* get the compressed symbol length from the first symbol byte */ 90 data = &kallsyms_names[off]; 91 len = *data; 92 data++; 93 94 /* update the offset to return the offset for the next symbol on 95 * the compressed stream */ 96 off += len + 1; 97 98 /* for every byte on the compressed symbol data, copy the table 99 entry for that byte */ 100 while(len) { 101 tptr = &kallsyms_token_table[ kallsyms_token_index[*data] ]; 102 data++; 103 len--; 104 105 while (*tptr) { 106 if(skipped_first) { 107 *result = *tptr; 108 result++; 109 } else 110 skipped_first = 1; 111 tptr++; 112 } 113 } 114 115 *result = '\0'; 116 117 /* return to offset to the next symbol */ 118 return off; 119 } 120 121 /* get symbol type information. This is encoded as a single char at the 122 * begining of the symbol name */ 123 static char kallsyms_get_symbol_type(unsigned int off) 124 { 125 /* get just the first code, look it up in the token table, and return the 126 * first char from this token */ 127 return kallsyms_token_table[ kallsyms_token_index[ kallsyms_names[off+1] ] ]; 128 } 129 130 131 /* find the offset on the compressed stream given and index in the 132 * kallsyms array */ 133 static unsigned int get_symbol_offset(unsigned long pos) 134 { 135 u8 *name; 136 int i; 137 138 /* use the closest marker we have. We have markers every 256 positions, 139 * so that should be close enough */ 140 name = &kallsyms_names[ kallsyms_markers[pos>>8] ]; 141 142 /* sequentially scan all the symbols up to the point we're searching for. 143 * Every symbol is stored in a [<len>][<len> bytes of data] format, so we 144 * just need to add the len to the current pointer for every symbol we 145 * wish to skip */ 146 for(i = 0; i < (pos&0xFF); i++) 147 name = name + (*name) + 1; 148 149 return name - kallsyms_names; 150 } 151 152 /* Lookup the address for this symbol. Returns 0 if not found. */ 153 unsigned long kallsyms_lookup_name(const char *name) 154 { 155 char namebuf[KSYM_NAME_LEN+1]; 156 unsigned long i; 157 unsigned int off; 158 159 for (i = 0, off = 0; i < kallsyms_num_syms; i++) { 160 off = kallsyms_expand_symbol(off, namebuf); 161 162 if (strcmp(namebuf, name) == 0) 163 return kallsyms_addresses[i]; 164 } 165 return module_kallsyms_lookup_name(name); 166 } 167 168 static unsigned long get_symbol_pos(unsigned long addr, 169 unsigned long *symbolsize, 170 unsigned long *offset) 171 { 172 unsigned long symbol_start = 0, symbol_end = 0; 173 unsigned long i, low, high, mid; 174 175 /* This kernel should never had been booted. */ 176 BUG_ON(!kallsyms_addresses); 177 178 /* do a binary search on the sorted kallsyms_addresses array */ 179 low = 0; 180 high = kallsyms_num_syms; 181 182 while (high - low > 1) { 183 mid = (low + high) / 2; 184 if (kallsyms_addresses[mid] <= addr) 185 low = mid; 186 else 187 high = mid; 188 } 189 190 /* 191 * search for the first aliased symbol. Aliased 192 * symbols are symbols with the same address 193 */ 194 while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low]) 195 --low; 196 197 symbol_start = kallsyms_addresses[low]; 198 199 /* Search for next non-aliased symbol */ 200 for (i = low + 1; i < kallsyms_num_syms; i++) { 201 if (kallsyms_addresses[i] > symbol_start) { 202 symbol_end = kallsyms_addresses[i]; 203 break; 204 } 205 } 206 207 /* if we found no next symbol, we use the end of the section */ 208 if (!symbol_end) { 209 if (is_kernel_inittext(addr)) 210 symbol_end = (unsigned long)_einittext; 211 else if (all_var) 212 symbol_end = (unsigned long)_end; 213 else 214 symbol_end = (unsigned long)_etext; 215 } 216 217 *symbolsize = symbol_end - symbol_start; 218 *offset = addr - symbol_start; 219 220 return low; 221 } 222 223 /* 224 * Lookup an address but don't bother to find any names. 225 */ 226 int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, 227 unsigned long *offset) 228 { 229 if (is_ksym_addr(addr)) 230 return !!get_symbol_pos(addr, symbolsize, offset); 231 232 return !!module_address_lookup(addr, symbolsize, offset, NULL); 233 } 234 235 /* 236 * Lookup an address 237 * - modname is set to NULL if it's in the kernel 238 * - we guarantee that the returned name is valid until we reschedule even if 239 * it resides in a module 240 * - we also guarantee that modname will be valid until rescheduled 241 */ 242 const char *kallsyms_lookup(unsigned long addr, 243 unsigned long *symbolsize, 244 unsigned long *offset, 245 char **modname, char *namebuf) 246 { 247 const char *msym; 248 249 namebuf[KSYM_NAME_LEN] = 0; 250 namebuf[0] = 0; 251 252 if (is_ksym_addr(addr)) { 253 unsigned long pos; 254 255 pos = get_symbol_pos(addr, symbolsize, offset); 256 /* Grab name */ 257 kallsyms_expand_symbol(get_symbol_offset(pos), namebuf); 258 *modname = NULL; 259 return namebuf; 260 } 261 262 /* see if it's in a module */ 263 msym = module_address_lookup(addr, symbolsize, offset, modname); 264 if (msym) 265 return strncpy(namebuf, msym, KSYM_NAME_LEN); 266 267 return NULL; 268 } 269 270 /* Replace "%s" in format with address, or returns -errno. */ 271 void __print_symbol(const char *fmt, unsigned long address) 272 { 273 char *modname; 274 const char *name; 275 unsigned long offset, size; 276 char namebuf[KSYM_NAME_LEN+1]; 277 char buffer[sizeof("%s+%#lx/%#lx [%s]") + KSYM_NAME_LEN + 278 2*(BITS_PER_LONG*3/10) + MODULE_NAME_LEN + 1]; 279 280 name = kallsyms_lookup(address, &size, &offset, &modname, namebuf); 281 282 if (!name) 283 sprintf(buffer, "0x%lx", address); 284 else { 285 if (modname) 286 sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset, 287 size, modname); 288 else 289 sprintf(buffer, "%s+%#lx/%#lx", name, offset, size); 290 } 291 printk(fmt, buffer); 292 } 293 294 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ 295 struct kallsym_iter 296 { 297 loff_t pos; 298 struct module *owner; 299 unsigned long value; 300 unsigned int nameoff; /* If iterating in core kernel symbols */ 301 char type; 302 char name[KSYM_NAME_LEN+1]; 303 }; 304 305 static int get_ksymbol_mod(struct kallsym_iter *iter) 306 { 307 iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms, 308 &iter->value, &iter->type, 309 iter->name, sizeof(iter->name)); 310 if (iter->owner == NULL) 311 return 0; 312 313 /* Label it "global" if it is exported, "local" if not exported. */ 314 iter->type = is_exported(iter->name, iter->owner) 315 ? toupper(iter->type) : tolower(iter->type); 316 317 return 1; 318 } 319 320 /* Returns space to next name. */ 321 static unsigned long get_ksymbol_core(struct kallsym_iter *iter) 322 { 323 unsigned off = iter->nameoff; 324 325 iter->owner = NULL; 326 iter->value = kallsyms_addresses[iter->pos]; 327 328 iter->type = kallsyms_get_symbol_type(off); 329 330 off = kallsyms_expand_symbol(off, iter->name); 331 332 return off - iter->nameoff; 333 } 334 335 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) 336 { 337 iter->name[0] = '\0'; 338 iter->nameoff = get_symbol_offset(new_pos); 339 iter->pos = new_pos; 340 } 341 342 /* Returns false if pos at or past end of file. */ 343 static int update_iter(struct kallsym_iter *iter, loff_t pos) 344 { 345 /* Module symbols can be accessed randomly. */ 346 if (pos >= kallsyms_num_syms) { 347 iter->pos = pos; 348 return get_ksymbol_mod(iter); 349 } 350 351 /* If we're not on the desired position, reset to new position. */ 352 if (pos != iter->pos) 353 reset_iter(iter, pos); 354 355 iter->nameoff += get_ksymbol_core(iter); 356 iter->pos++; 357 358 return 1; 359 } 360 361 static void *s_next(struct seq_file *m, void *p, loff_t *pos) 362 { 363 (*pos)++; 364 365 if (!update_iter(m->private, *pos)) 366 return NULL; 367 return p; 368 } 369 370 static void *s_start(struct seq_file *m, loff_t *pos) 371 { 372 if (!update_iter(m->private, *pos)) 373 return NULL; 374 return m->private; 375 } 376 377 static void s_stop(struct seq_file *m, void *p) 378 { 379 } 380 381 static int s_show(struct seq_file *m, void *p) 382 { 383 struct kallsym_iter *iter = m->private; 384 385 /* Some debugging symbols have no name. Ignore them. */ 386 if (!iter->name[0]) 387 return 0; 388 389 if (iter->owner) 390 seq_printf(m, "%0*lx %c %s\t[%s]\n", 391 (int)(2*sizeof(void*)), 392 iter->value, iter->type, iter->name, 393 module_name(iter->owner)); 394 else 395 seq_printf(m, "%0*lx %c %s\n", 396 (int)(2*sizeof(void*)), 397 iter->value, iter->type, iter->name); 398 return 0; 399 } 400 401 static const struct seq_operations kallsyms_op = { 402 .start = s_start, 403 .next = s_next, 404 .stop = s_stop, 405 .show = s_show 406 }; 407 408 static int kallsyms_open(struct inode *inode, struct file *file) 409 { 410 /* We keep iterator in m->private, since normal case is to 411 * s_start from where we left off, so we avoid doing 412 * using get_symbol_offset for every symbol */ 413 struct kallsym_iter *iter; 414 int ret; 415 416 iter = kmalloc(sizeof(*iter), GFP_KERNEL); 417 if (!iter) 418 return -ENOMEM; 419 reset_iter(iter, 0); 420 421 ret = seq_open(file, &kallsyms_op); 422 if (ret == 0) 423 ((struct seq_file *)file->private_data)->private = iter; 424 else 425 kfree(iter); 426 return ret; 427 } 428 429 static int kallsyms_release(struct inode *inode, struct file *file) 430 { 431 struct seq_file *m = (struct seq_file *)file->private_data; 432 kfree(m->private); 433 return seq_release(inode, file); 434 } 435 436 static const struct file_operations kallsyms_operations = { 437 .open = kallsyms_open, 438 .read = seq_read, 439 .llseek = seq_lseek, 440 .release = kallsyms_release, 441 }; 442 443 static int __init kallsyms_init(void) 444 { 445 struct proc_dir_entry *entry; 446 447 entry = create_proc_entry("kallsyms", 0444, NULL); 448 if (entry) 449 entry->proc_fops = &kallsyms_operations; 450 return 0; 451 } 452 __initcall(kallsyms_init); 453 454 EXPORT_SYMBOL(__print_symbol); 455