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>
23 #include <asm/sections.h>
25 #ifdef CONFIG_KALLSYMS_ALL
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));
36 extern u8 kallsyms_token_table[] __attribute__((weak));
37 extern u16 kallsyms_token_index[] __attribute__((weak));
39 extern unsigned long kallsyms_markers[] __attribute__((weak));
41 static inline int is_kernel_inittext(unsigned long addr)
43 if (addr >= (unsigned long)_sinittext
44 && addr <= (unsigned long)_einittext)
49 static inline int is_kernel_text(unsigned long addr)
51 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext)
53 return in_gate_area_no_task(addr);
56 static inline int is_kernel(unsigned long addr)
58 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
60 return in_gate_area_no_task(addr);
63 /* expand a compressed symbol data into the resulting uncompressed string,
64 given the offset to where the symbol is in the compressed stream */
65 static unsigned int kallsyms_expand_symbol(unsigned int off, char *result)
67 int len, skipped_first = 0;
70 /* get the compressed symbol length from the first symbol byte */
71 data = &kallsyms_names[off];
75 /* update the offset to return the offset for the next symbol on
76 * the compressed stream */
79 /* for every byte on the compressed symbol data, copy the table
80 entry for that byte */
82 tptr = &kallsyms_token_table[ kallsyms_token_index[*data] ];
98 /* return to offset to the next symbol */
102 /* get symbol type information. This is encoded as a single char at the
103 * begining of the symbol name */
104 static char kallsyms_get_symbol_type(unsigned int off)
106 /* get just the first code, look it up in the token table, and return the
107 * first char from this token */
108 return kallsyms_token_table[ kallsyms_token_index[ kallsyms_names[off+1] ] ];
112 /* find the offset on the compressed stream given and index in the
114 static unsigned int get_symbol_offset(unsigned long pos)
119 /* use the closest marker we have. We have markers every 256 positions,
120 * so that should be close enough */
121 name = &kallsyms_names[ kallsyms_markers[pos>>8] ];
123 /* sequentially scan all the symbols up to the point we're searching for.
124 * Every symbol is stored in a [<len>][<len> bytes of data] format, so we
125 * just need to add the len to the current pointer for every symbol we
127 for(i = 0; i < (pos&0xFF); i++)
128 name = name + (*name) + 1;
130 return name - kallsyms_names;
133 /* Lookup the address for this symbol. Returns 0 if not found. */
134 unsigned long kallsyms_lookup_name(const char *name)
136 char namebuf[KSYM_NAME_LEN+1];
140 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
141 off = kallsyms_expand_symbol(off, namebuf);
143 if (strcmp(namebuf, name) == 0)
144 return kallsyms_addresses[i];
146 return module_kallsyms_lookup_name(name);
149 /* Lookup an address. modname is set to NULL if it's in the kernel. */
150 const char *kallsyms_lookup(unsigned long addr,
151 unsigned long *symbolsize,
152 unsigned long *offset,
153 char **modname, char *namebuf)
155 unsigned long i, low, high, mid;
157 /* This kernel should never had been booted. */
158 BUG_ON(!kallsyms_addresses);
160 namebuf[KSYM_NAME_LEN] = 0;
163 if ((all_var && is_kernel(addr)) ||
164 (!all_var && (is_kernel_text(addr) || is_kernel_inittext(addr)))) {
165 unsigned long symbol_end=0;
167 /* do a binary search on the sorted kallsyms_addresses array */
169 high = kallsyms_num_syms;
171 while (high-low > 1) {
172 mid = (low + high) / 2;
173 if (kallsyms_addresses[mid] <= addr) low = mid;
177 /* search for the first aliased symbol. Aliased symbols are
178 symbols with the same address */
179 while (low && kallsyms_addresses[low - 1] == kallsyms_addresses[low])
183 kallsyms_expand_symbol(get_symbol_offset(low), namebuf);
185 /* Search for next non-aliased symbol */
186 for (i = low + 1; i < kallsyms_num_syms; i++) {
187 if (kallsyms_addresses[i] > kallsyms_addresses[low]) {
188 symbol_end = kallsyms_addresses[i];
193 /* if we found no next symbol, we use the end of the section */
195 if (is_kernel_inittext(addr))
196 symbol_end = (unsigned long)_einittext;
198 symbol_end = all_var ? (unsigned long)_end : (unsigned long)_etext;
201 *symbolsize = symbol_end - kallsyms_addresses[low];
203 *offset = addr - kallsyms_addresses[low];
207 return module_address_lookup(addr, symbolsize, offset, modname);
210 /* Replace "%s" in format with address, or returns -errno. */
211 void __print_symbol(const char *fmt, unsigned long address)
215 unsigned long offset, size;
216 char namebuf[KSYM_NAME_LEN+1];
217 char buffer[sizeof("%s+%#lx/%#lx [%s]") + KSYM_NAME_LEN +
218 2*(BITS_PER_LONG*3/10) + MODULE_NAME_LEN + 1];
220 name = kallsyms_lookup(address, &size, &offset, &modname, namebuf);
223 sprintf(buffer, "0x%lx", address);
226 sprintf(buffer, "%s+%#lx/%#lx [%s]", name, offset,
229 sprintf(buffer, "%s+%#lx/%#lx", name, offset, size);
234 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
238 struct module *owner;
240 unsigned int nameoff; /* If iterating in core kernel symbols */
242 char name[KSYM_NAME_LEN+1];
245 /* Only label it "global" if it is exported. */
246 static void upcase_if_global(struct kallsym_iter *iter)
248 if (is_exported(iter->name, iter->owner))
249 iter->type += 'A' - 'a';
252 static int get_ksymbol_mod(struct kallsym_iter *iter)
254 iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms,
256 &iter->type, iter->name);
257 if (iter->owner == NULL)
260 upcase_if_global(iter);
264 /* Returns space to next name. */
265 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
267 unsigned off = iter->nameoff;
270 iter->value = kallsyms_addresses[iter->pos];
272 iter->type = kallsyms_get_symbol_type(off);
274 off = kallsyms_expand_symbol(off, iter->name);
276 return off - iter->nameoff;
279 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
281 iter->name[0] = '\0';
282 iter->nameoff = get_symbol_offset(new_pos);
286 /* Returns false if pos at or past end of file. */
287 static int update_iter(struct kallsym_iter *iter, loff_t pos)
289 /* Module symbols can be accessed randomly. */
290 if (pos >= kallsyms_num_syms) {
292 return get_ksymbol_mod(iter);
295 /* If we're not on the desired position, reset to new position. */
296 if (pos != iter->pos)
297 reset_iter(iter, pos);
299 iter->nameoff += get_ksymbol_core(iter);
305 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
309 if (!update_iter(m->private, *pos))
314 static void *s_start(struct seq_file *m, loff_t *pos)
316 if (!update_iter(m->private, *pos))
321 static void s_stop(struct seq_file *m, void *p)
325 static int s_show(struct seq_file *m, void *p)
327 struct kallsym_iter *iter = m->private;
329 /* Some debugging symbols have no name. Ignore them. */
334 seq_printf(m, "%0*lx %c %s\t[%s]\n",
335 (int)(2*sizeof(void*)),
336 iter->value, iter->type, iter->name,
337 module_name(iter->owner));
339 seq_printf(m, "%0*lx %c %s\n",
340 (int)(2*sizeof(void*)),
341 iter->value, iter->type, iter->name);
345 struct seq_operations kallsyms_op = {
352 static int kallsyms_open(struct inode *inode, struct file *file)
354 /* We keep iterator in m->private, since normal case is to
355 * s_start from where we left off, so we avoid doing
356 * using get_symbol_offset for every symbol */
357 struct kallsym_iter *iter;
360 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
365 ret = seq_open(file, &kallsyms_op);
367 ((struct seq_file *)file->private_data)->private = iter;
373 static int kallsyms_release(struct inode *inode, struct file *file)
375 struct seq_file *m = (struct seq_file *)file->private_data;
377 return seq_release(inode, file);
380 static struct file_operations kallsyms_operations = {
381 .open = kallsyms_open,
384 .release = kallsyms_release,
387 int __init kallsyms_init(void)
389 struct proc_dir_entry *entry;
391 entry = create_proc_entry("kallsyms", 0444, NULL);
393 entry->proc_fops = &kallsyms_operations;
396 __initcall(kallsyms_init);
398 EXPORT_SYMBOL(__print_symbol);