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/err.h>
20 #include <linux/proc_fs.h>
21 #include <linux/sched.h> /* for cond_resched */
23 #include <linux/ctype.h>
25 #include <asm/sections.h>
27 #ifdef CONFIG_KALLSYMS_ALL
33 /* These will be re-linked against their real values during the second link stage */
34 extern const unsigned long kallsyms_addresses[] __attribute__((weak));
35 extern const u8 kallsyms_names[] __attribute__((weak));
37 /* tell the compiler that the count isn't in the small data section if the arch
40 extern const unsigned long kallsyms_num_syms
41 __attribute__((weak, section(".rodata")));
43 extern const u8 kallsyms_token_table[] __attribute__((weak));
44 extern const u16 kallsyms_token_index[] __attribute__((weak));
46 extern const unsigned long kallsyms_markers[] __attribute__((weak));
48 static inline int is_kernel_inittext(unsigned long addr)
50 if (addr >= (unsigned long)_sinittext
51 && addr <= (unsigned long)_einittext)
56 static inline int is_kernel_text(unsigned long addr)
58 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext)
60 return in_gate_area_no_task(addr);
63 static inline int is_kernel(unsigned long addr)
65 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
67 return in_gate_area_no_task(addr);
70 static int is_ksym_addr(unsigned long addr)
73 return is_kernel(addr);
75 return is_kernel_text(addr) || is_kernel_inittext(addr);
78 /* expand a compressed symbol data into the resulting uncompressed string,
79 given the offset to where the symbol is in the compressed stream */
80 static unsigned int kallsyms_expand_symbol(unsigned int off, char *result)
82 int len, skipped_first = 0;
83 const u8 *tptr, *data;
85 /* get the compressed symbol length from the first symbol byte */
86 data = &kallsyms_names[off];
90 /* update the offset to return the offset for the next symbol on
91 * the compressed stream */
94 /* for every byte on the compressed symbol data, copy the table
95 entry for that byte */
97 tptr = &kallsyms_token_table[ kallsyms_token_index[*data] ];
113 /* return to offset to the next symbol */
117 /* get symbol type information. This is encoded as a single char at the
118 * begining of the symbol name */
119 static char kallsyms_get_symbol_type(unsigned int off)
121 /* get just the first code, look it up in the token table, and return the
122 * first char from this token */
123 return kallsyms_token_table[ kallsyms_token_index[ kallsyms_names[off+1] ] ];
127 /* find the offset on the compressed stream given and index in the
129 static unsigned int get_symbol_offset(unsigned long pos)
134 /* use the closest marker we have. We have markers every 256 positions,
135 * so that should be close enough */
136 name = &kallsyms_names[ kallsyms_markers[pos>>8] ];
138 /* sequentially scan all the symbols up to the point we're searching for.
139 * Every symbol is stored in a [<len>][<len> bytes of data] format, so we
140 * just need to add the len to the current pointer for every symbol we
142 for(i = 0; i < (pos&0xFF); i++)
143 name = name + (*name) + 1;
145 return name - kallsyms_names;
148 /* Lookup the address for this symbol. Returns 0 if not found. */
149 unsigned long kallsyms_lookup_name(const char *name)
151 char namebuf[KSYM_NAME_LEN];
155 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
156 off = kallsyms_expand_symbol(off, namebuf);
158 if (strcmp(namebuf, name) == 0)
159 return kallsyms_addresses[i];
161 return module_kallsyms_lookup_name(name);
164 static unsigned long get_symbol_pos(unsigned long addr,
165 unsigned long *symbolsize,
166 unsigned long *offset)
168 unsigned long symbol_start = 0, symbol_end = 0;
169 unsigned long i, low, high, mid;
171 /* This kernel should never had been booted. */
172 BUG_ON(!kallsyms_addresses);
174 /* do a binary search on the sorted kallsyms_addresses array */
176 high = kallsyms_num_syms;
178 while (high - low > 1) {
179 mid = low + (high - low) / 2;
180 if (kallsyms_addresses[mid] <= addr)
187 * search for the first aliased symbol. Aliased
188 * symbols are symbols with the same address
190 while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low])
193 symbol_start = kallsyms_addresses[low];
195 /* Search for next non-aliased symbol */
196 for (i = low + 1; i < kallsyms_num_syms; i++) {
197 if (kallsyms_addresses[i] > symbol_start) {
198 symbol_end = kallsyms_addresses[i];
203 /* if we found no next symbol, we use the end of the section */
205 if (is_kernel_inittext(addr))
206 symbol_end = (unsigned long)_einittext;
208 symbol_end = (unsigned long)_end;
210 symbol_end = (unsigned long)_etext;
214 *symbolsize = symbol_end - symbol_start;
216 *offset = addr - symbol_start;
222 * Lookup an address but don't bother to find any names.
224 int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
225 unsigned long *offset)
227 char namebuf[KSYM_NAME_LEN];
228 if (is_ksym_addr(addr))
229 return !!get_symbol_pos(addr, symbolsize, offset);
231 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
236 * - modname is set to NULL if it's in the kernel
237 * - we guarantee that the returned name is valid until we reschedule even if
238 * it resides in a module
239 * - we also guarantee that modname will be valid until rescheduled
241 const char *kallsyms_lookup(unsigned long addr,
242 unsigned long *symbolsize,
243 unsigned long *offset,
244 char **modname, char *namebuf)
246 namebuf[KSYM_NAME_LEN - 1] = 0;
249 if (is_ksym_addr(addr)) {
252 pos = get_symbol_pos(addr, symbolsize, offset);
254 kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);
260 /* see if it's in a module */
261 return module_address_lookup(addr, symbolsize, offset, modname,
265 int lookup_symbol_name(unsigned long addr, char *symname)
268 symname[KSYM_NAME_LEN - 1] = '\0';
270 if (is_ksym_addr(addr)) {
273 pos = get_symbol_pos(addr, NULL, NULL);
275 kallsyms_expand_symbol(get_symbol_offset(pos), symname);
278 /* see if it's in a module */
279 return lookup_module_symbol_name(addr, symname);
282 int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
283 unsigned long *offset, char *modname, char *name)
286 name[KSYM_NAME_LEN - 1] = '\0';
288 if (is_ksym_addr(addr)) {
291 pos = get_symbol_pos(addr, size, offset);
293 kallsyms_expand_symbol(get_symbol_offset(pos), name);
297 /* see if it's in a module */
298 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
301 /* Look up a kernel symbol and return it in a text buffer. */
302 int sprint_symbol(char *buffer, unsigned long address)
306 unsigned long offset, size;
309 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
311 return sprintf(buffer, "0x%lx", address);
314 strcpy(buffer, name);
315 len = strlen(buffer);
319 len += sprintf(buffer, "+%#lx/%#lx [%s]",
320 offset, size, modname);
322 len += sprintf(buffer, "+%#lx/%#lx", offset, size);
327 /* Look up a kernel symbol and print it to the kernel messages. */
328 void __print_symbol(const char *fmt, unsigned long address)
330 char buffer[KSYM_SYMBOL_LEN];
332 sprint_symbol(buffer, address);
337 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
342 unsigned int nameoff; /* If iterating in core kernel symbols */
344 char name[KSYM_NAME_LEN];
345 char module_name[MODULE_NAME_LEN];
349 static int get_ksymbol_mod(struct kallsym_iter *iter)
351 if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
352 &iter->type, iter->name, iter->module_name,
353 &iter->exported) < 0)
358 /* Returns space to next name. */
359 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
361 unsigned off = iter->nameoff;
363 iter->module_name[0] = '\0';
364 iter->value = kallsyms_addresses[iter->pos];
366 iter->type = kallsyms_get_symbol_type(off);
368 off = kallsyms_expand_symbol(off, iter->name);
370 return off - iter->nameoff;
373 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
375 iter->name[0] = '\0';
376 iter->nameoff = get_symbol_offset(new_pos);
380 /* Returns false if pos at or past end of file. */
381 static int update_iter(struct kallsym_iter *iter, loff_t pos)
383 /* Module symbols can be accessed randomly. */
384 if (pos >= kallsyms_num_syms) {
386 return get_ksymbol_mod(iter);
389 /* If we're not on the desired position, reset to new position. */
390 if (pos != iter->pos)
391 reset_iter(iter, pos);
393 iter->nameoff += get_ksymbol_core(iter);
399 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
403 if (!update_iter(m->private, *pos))
408 static void *s_start(struct seq_file *m, loff_t *pos)
410 if (!update_iter(m->private, *pos))
415 static void s_stop(struct seq_file *m, void *p)
419 static int s_show(struct seq_file *m, void *p)
421 struct kallsym_iter *iter = m->private;
423 /* Some debugging symbols have no name. Ignore them. */
427 if (iter->module_name[0]) {
430 /* Label it "global" if it is exported,
431 * "local" if not exported. */
432 type = iter->exported ? toupper(iter->type) :
434 seq_printf(m, "%0*lx %c %s\t[%s]\n",
435 (int)(2*sizeof(void*)),
436 iter->value, type, iter->name, iter->module_name);
438 seq_printf(m, "%0*lx %c %s\n",
439 (int)(2*sizeof(void*)),
440 iter->value, iter->type, iter->name);
444 static const struct seq_operations kallsyms_op = {
451 static int kallsyms_open(struct inode *inode, struct file *file)
453 /* We keep iterator in m->private, since normal case is to
454 * s_start from where we left off, so we avoid doing
455 * using get_symbol_offset for every symbol */
456 struct kallsym_iter *iter;
459 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
464 ret = seq_open(file, &kallsyms_op);
466 ((struct seq_file *)file->private_data)->private = iter;
472 static const struct file_operations kallsyms_operations = {
473 .open = kallsyms_open,
476 .release = seq_release_private,
479 static int __init kallsyms_init(void)
481 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
484 __initcall(kallsyms_init);
486 EXPORT_SYMBOL(__print_symbol);
487 EXPORT_SYMBOL_GPL(sprint_symbol);