2 * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
4 * Rewritten and vastly simplified by Rusty Russell for in-kernel
6 * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
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)
14 #include <linux/kallsyms.h>
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/seq_file.h>
19 #include <linux/kdb.h>
20 #include <linux/err.h>
21 #include <linux/proc_fs.h>
22 #include <linux/sched.h> /* for cond_resched */
24 #include <linux/ctype.h>
25 #include <linux/slab.h>
27 #include <asm/sections.h>
29 #ifdef CONFIG_KALLSYMS_ALL
36 * These will be re-linked against their real values
37 * during the second link stage.
39 extern const unsigned long kallsyms_addresses[] __attribute__((weak));
40 extern const u8 kallsyms_names[] __attribute__((weak));
43 * Tell the compiler that the count isn't in the small data section if the arch
46 extern const unsigned long kallsyms_num_syms
47 __attribute__((weak, section(".rodata")));
49 extern const u8 kallsyms_token_table[] __attribute__((weak));
50 extern const u16 kallsyms_token_index[] __attribute__((weak));
52 extern const unsigned long kallsyms_markers[] __attribute__((weak));
54 static inline int is_kernel_inittext(unsigned long addr)
56 if (addr >= (unsigned long)_sinittext
57 && addr <= (unsigned long)_einittext)
62 static inline int is_kernel_text(unsigned long addr)
64 if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) ||
65 arch_is_kernel_text(addr))
67 return in_gate_area_no_mm(addr);
70 static inline int is_kernel(unsigned long addr)
72 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
74 return in_gate_area_no_mm(addr);
77 static int is_ksym_addr(unsigned long addr)
80 return is_kernel(addr);
82 return is_kernel_text(addr) || is_kernel_inittext(addr);
86 * Expand a compressed symbol data into the resulting uncompressed string,
87 * if uncompressed string is too long (>= maxlen), it will be truncated,
88 * given the offset to where the symbol is in the compressed stream.
90 static unsigned int kallsyms_expand_symbol(unsigned int off,
91 char *result, size_t maxlen)
93 int len, skipped_first = 0;
94 const u8 *tptr, *data;
96 /* Get the compressed symbol length from the first symbol byte. */
97 data = &kallsyms_names[off];
102 * Update the offset to return the offset for the next symbol on
103 * the compressed stream.
108 * For every byte on the compressed symbol data, copy the table
109 * entry for that byte.
112 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
133 /* Return to offset to the next symbol. */
138 * Get symbol type information. This is encoded as a single char at the
139 * beginning of the symbol name.
141 static char kallsyms_get_symbol_type(unsigned int off)
144 * Get just the first code, look it up in the token table,
145 * and return the first char from this token.
147 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
152 * Find the offset on the compressed stream given and index in the
155 static unsigned int get_symbol_offset(unsigned long pos)
161 * Use the closest marker we have. We have markers every 256 positions,
162 * so that should be close enough.
164 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
167 * Sequentially scan all the symbols up to the point we're searching
168 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
169 * so we just need to add the len to the current pointer for every
170 * symbol we wish to skip.
172 for (i = 0; i < (pos & 0xFF); i++)
173 name = name + (*name) + 1;
175 return name - kallsyms_names;
178 /* Lookup the address for this symbol. Returns 0 if not found. */
179 unsigned long kallsyms_lookup_name(const char *name)
181 char namebuf[KSYM_NAME_LEN];
185 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
186 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
188 if (strcmp(namebuf, name) == 0)
189 return kallsyms_addresses[i];
191 return module_kallsyms_lookup_name(name);
193 EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
195 int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
199 char namebuf[KSYM_NAME_LEN];
204 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
205 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
206 ret = fn(data, namebuf, NULL, kallsyms_addresses[i]);
210 return module_kallsyms_on_each_symbol(fn, data);
212 EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
214 static unsigned long get_symbol_pos(unsigned long addr,
215 unsigned long *symbolsize,
216 unsigned long *offset)
218 unsigned long symbol_start = 0, symbol_end = 0;
219 unsigned long i, low, high, mid;
221 /* This kernel should never had been booted. */
222 BUG_ON(!kallsyms_addresses);
224 /* Do a binary search on the sorted kallsyms_addresses array. */
226 high = kallsyms_num_syms;
228 while (high - low > 1) {
229 mid = low + (high - low) / 2;
230 if (kallsyms_addresses[mid] <= addr)
237 * Search for the first aliased symbol. Aliased
238 * symbols are symbols with the same address.
240 while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low])
243 symbol_start = kallsyms_addresses[low];
245 /* Search for next non-aliased symbol. */
246 for (i = low + 1; i < kallsyms_num_syms; i++) {
247 if (kallsyms_addresses[i] > symbol_start) {
248 symbol_end = kallsyms_addresses[i];
253 /* If we found no next symbol, we use the end of the section. */
255 if (is_kernel_inittext(addr))
256 symbol_end = (unsigned long)_einittext;
258 symbol_end = (unsigned long)_end;
260 symbol_end = (unsigned long)_etext;
264 *symbolsize = symbol_end - symbol_start;
266 *offset = addr - symbol_start;
272 * Lookup an address but don't bother to find any names.
274 int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
275 unsigned long *offset)
277 char namebuf[KSYM_NAME_LEN];
278 if (is_ksym_addr(addr))
279 return !!get_symbol_pos(addr, symbolsize, offset);
281 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
286 * - modname is set to NULL if it's in the kernel.
287 * - We guarantee that the returned name is valid until we reschedule even if.
288 * It resides in a module.
289 * - We also guarantee that modname will be valid until rescheduled.
291 const char *kallsyms_lookup(unsigned long addr,
292 unsigned long *symbolsize,
293 unsigned long *offset,
294 char **modname, char *namebuf)
296 namebuf[KSYM_NAME_LEN - 1] = 0;
299 if (is_ksym_addr(addr)) {
302 pos = get_symbol_pos(addr, symbolsize, offset);
304 kallsyms_expand_symbol(get_symbol_offset(pos),
305 namebuf, KSYM_NAME_LEN);
311 /* See if it's in a module. */
312 return module_address_lookup(addr, symbolsize, offset, modname,
316 int lookup_symbol_name(unsigned long addr, char *symname)
319 symname[KSYM_NAME_LEN - 1] = '\0';
321 if (is_ksym_addr(addr)) {
324 pos = get_symbol_pos(addr, NULL, NULL);
326 kallsyms_expand_symbol(get_symbol_offset(pos),
327 symname, KSYM_NAME_LEN);
330 /* See if it's in a module. */
331 return lookup_module_symbol_name(addr, symname);
334 int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
335 unsigned long *offset, char *modname, char *name)
338 name[KSYM_NAME_LEN - 1] = '\0';
340 if (is_ksym_addr(addr)) {
343 pos = get_symbol_pos(addr, size, offset);
345 kallsyms_expand_symbol(get_symbol_offset(pos),
346 name, KSYM_NAME_LEN);
350 /* See if it's in a module. */
351 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
354 /* Look up a kernel symbol and return it in a text buffer. */
355 static int __sprint_symbol(char *buffer, unsigned long address,
356 int symbol_offset, int add_offset)
360 unsigned long offset, size;
363 address += symbol_offset;
364 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
366 return sprintf(buffer, "0x%lx", address);
369 strcpy(buffer, name);
370 len = strlen(buffer);
371 offset -= symbol_offset;
374 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
377 len += sprintf(buffer + len, " [%s]", modname);
383 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
384 * @buffer: buffer to be stored
385 * @address: address to lookup
387 * This function looks up a kernel symbol with @address and stores its name,
388 * offset, size and module name to @buffer if possible. If no symbol was found,
389 * just saves its @address as is.
391 * This function returns the number of bytes stored in @buffer.
393 int sprint_symbol(char *buffer, unsigned long address)
395 return __sprint_symbol(buffer, address, 0, 1);
397 EXPORT_SYMBOL_GPL(sprint_symbol);
400 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
401 * @buffer: buffer to be stored
402 * @address: address to lookup
404 * This function looks up a kernel symbol with @address and stores its name
405 * and module name to @buffer if possible. If no symbol was found, just saves
406 * its @address as is.
408 * This function returns the number of bytes stored in @buffer.
410 int sprint_symbol_no_offset(char *buffer, unsigned long address)
412 return __sprint_symbol(buffer, address, 0, 0);
414 EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
417 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
418 * @buffer: buffer to be stored
419 * @address: address to lookup
421 * This function is for stack backtrace and does the same thing as
422 * sprint_symbol() but with modified/decreased @address. If there is a
423 * tail-call to the function marked "noreturn", gcc optimized out code after
424 * the call so that the stack-saved return address could point outside of the
425 * caller. This function ensures that kallsyms will find the original caller
426 * by decreasing @address.
428 * This function returns the number of bytes stored in @buffer.
430 int sprint_backtrace(char *buffer, unsigned long address)
432 return __sprint_symbol(buffer, address, -1, 1);
435 /* Look up a kernel symbol and print it to the kernel messages. */
436 void __print_symbol(const char *fmt, unsigned long address)
438 char buffer[KSYM_SYMBOL_LEN];
440 sprint_symbol(buffer, address);
444 EXPORT_SYMBOL(__print_symbol);
446 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
447 struct kallsym_iter {
450 unsigned int nameoff; /* If iterating in core kernel symbols. */
452 char name[KSYM_NAME_LEN];
453 char module_name[MODULE_NAME_LEN];
457 static int get_ksymbol_mod(struct kallsym_iter *iter)
459 if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
460 &iter->type, iter->name, iter->module_name,
461 &iter->exported) < 0)
466 /* Returns space to next name. */
467 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
469 unsigned off = iter->nameoff;
471 iter->module_name[0] = '\0';
472 iter->value = kallsyms_addresses[iter->pos];
474 iter->type = kallsyms_get_symbol_type(off);
476 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
478 return off - iter->nameoff;
481 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
483 iter->name[0] = '\0';
484 iter->nameoff = get_symbol_offset(new_pos);
488 /* Returns false if pos at or past end of file. */
489 static int update_iter(struct kallsym_iter *iter, loff_t pos)
491 /* Module symbols can be accessed randomly. */
492 if (pos >= kallsyms_num_syms) {
494 return get_ksymbol_mod(iter);
497 /* If we're not on the desired position, reset to new position. */
498 if (pos != iter->pos)
499 reset_iter(iter, pos);
501 iter->nameoff += get_ksymbol_core(iter);
507 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
511 if (!update_iter(m->private, *pos))
516 static void *s_start(struct seq_file *m, loff_t *pos)
518 if (!update_iter(m->private, *pos))
523 static void s_stop(struct seq_file *m, void *p)
527 static int s_show(struct seq_file *m, void *p)
529 struct kallsym_iter *iter = m->private;
531 /* Some debugging symbols have no name. Ignore them. */
535 if (iter->module_name[0]) {
539 * Label it "global" if it is exported,
540 * "local" if not exported.
542 type = iter->exported ? toupper(iter->type) :
544 seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
545 type, iter->name, iter->module_name);
547 seq_printf(m, "%pK %c %s\n", (void *)iter->value,
548 iter->type, iter->name);
552 static const struct seq_operations kallsyms_op = {
559 static int kallsyms_open(struct inode *inode, struct file *file)
562 * We keep iterator in m->private, since normal case is to
563 * s_start from where we left off, so we avoid doing
564 * using get_symbol_offset for every symbol.
566 struct kallsym_iter *iter;
569 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
574 ret = seq_open(file, &kallsyms_op);
576 ((struct seq_file *)file->private_data)->private = iter;
582 #ifdef CONFIG_KGDB_KDB
583 const char *kdb_walk_kallsyms(loff_t *pos)
585 static struct kallsym_iter kdb_walk_kallsyms_iter;
587 memset(&kdb_walk_kallsyms_iter, 0,
588 sizeof(kdb_walk_kallsyms_iter));
589 reset_iter(&kdb_walk_kallsyms_iter, 0);
592 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
595 /* Some debugging symbols have no name. Ignore them. */
596 if (kdb_walk_kallsyms_iter.name[0])
597 return kdb_walk_kallsyms_iter.name;
600 #endif /* CONFIG_KGDB_KDB */
602 static const struct file_operations kallsyms_operations = {
603 .open = kallsyms_open,
606 .release = seq_release_private,
609 static int __init kallsyms_init(void)
611 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
614 device_initcall(kallsyms_init);