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