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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/kdb.h>
20#include <linux/err.h>
21#include <linux/proc_fs.h>
22#include <linux/sched.h> /* for cond_resched */
23#include <linux/mm.h>
24#include <linux/ctype.h>
25#include <linux/slab.h>
26#include <linux/compiler.h>
27
28#include <asm/sections.h>
29
30#ifdef CONFIG_KALLSYMS_ALL
31#define all_var 1
32#else
33#define all_var 0
34#endif
35
36/*
37 * These will be re-linked against their real values
38 * during the second link stage.
39 */
40extern const unsigned long kallsyms_addresses[] __weak;
41extern const int kallsyms_offsets[] __weak;
42extern const u8 kallsyms_names[] __weak;
43
44/*
45 * Tell the compiler that the count isn't in the small data section if the arch
46 * has one (eg: FRV).
47 */
48extern const unsigned long kallsyms_num_syms
49__attribute__((weak, section(".rodata")));
50
51extern const unsigned long kallsyms_relative_base
52__attribute__((weak, section(".rodata")));
53
54extern const u8 kallsyms_token_table[] __weak;
55extern const u16 kallsyms_token_index[] __weak;
56
57extern const unsigned long kallsyms_markers[] __weak;
58
59static inline int is_kernel_inittext(unsigned long addr)
60{
61 if (addr >= (unsigned long)_sinittext
62 && addr <= (unsigned long)_einittext)
63 return 1;
64 return 0;
65}
66
67static inline int is_kernel_text(unsigned long addr)
68{
69 if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) ||
70 arch_is_kernel_text(addr))
71 return 1;
72 return in_gate_area_no_mm(addr);
73}
74
75static inline int is_kernel(unsigned long addr)
76{
77 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
78 return 1;
79 return in_gate_area_no_mm(addr);
80}
81
82static int is_ksym_addr(unsigned long addr)
83{
84 if (all_var)
85 return is_kernel(addr);
86
87 return is_kernel_text(addr) || is_kernel_inittext(addr);
88}
89
90/*
91 * Expand a compressed symbol data into the resulting uncompressed string,
92 * if uncompressed string is too long (>= maxlen), it will be truncated,
93 * given the offset to where the symbol is in the compressed stream.
94 */
95static unsigned int kallsyms_expand_symbol(unsigned int off,
96 char *result, size_t maxlen)
97{
98 int len, skipped_first = 0;
99 const u8 *tptr, *data;
100
101 /* Get the compressed symbol length from the first symbol byte. */
102 data = &kallsyms_names[off];
103 len = *data;
104 data++;
105
106 /*
107 * Update the offset to return the offset for the next symbol on
108 * the compressed stream.
109 */
110 off += len + 1;
111
112 /*
113 * For every byte on the compressed symbol data, copy the table
114 * entry for that byte.
115 */
116 while (len) {
117 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
118 data++;
119 len--;
120
121 while (*tptr) {
122 if (skipped_first) {
123 if (maxlen <= 1)
124 goto tail;
125 *result = *tptr;
126 result++;
127 maxlen--;
128 } else
129 skipped_first = 1;
130 tptr++;
131 }
132 }
133
134tail:
135 if (maxlen)
136 *result = '\0';
137
138 /* Return to offset to the next symbol. */
139 return off;
140}
141
142/*
143 * Get symbol type information. This is encoded as a single char at the
144 * beginning of the symbol name.
145 */
146static char kallsyms_get_symbol_type(unsigned int off)
147{
148 /*
149 * Get just the first code, look it up in the token table,
150 * and return the first char from this token.
151 */
152 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
153}
154
155
156/*
157 * Find the offset on the compressed stream given and index in the
158 * kallsyms array.
159 */
160static unsigned int get_symbol_offset(unsigned long pos)
161{
162 const u8 *name;
163 int i;
164
165 /*
166 * Use the closest marker we have. We have markers every 256 positions,
167 * so that should be close enough.
168 */
169 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
170
171 /*
172 * Sequentially scan all the symbols up to the point we're searching
173 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
174 * so we just need to add the len to the current pointer for every
175 * symbol we wish to skip.
176 */
177 for (i = 0; i < (pos & 0xFF); i++)
178 name = name + (*name) + 1;
179
180 return name - kallsyms_names;
181}
182
183static unsigned long kallsyms_sym_address(int idx)
184{
185 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
186 return kallsyms_addresses[idx];
187
188 /* values are unsigned offsets if --absolute-percpu is not in effect */
189 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
190 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
191
192 /* ...otherwise, positive offsets are absolute values */
193 if (kallsyms_offsets[idx] >= 0)
194 return kallsyms_offsets[idx];
195
196 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
197 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
198}
199
200/* Lookup the address for this symbol. Returns 0 if not found. */
201unsigned long kallsyms_lookup_name(const char *name)
202{
203 char namebuf[KSYM_NAME_LEN];
204 unsigned long i;
205 unsigned int off;
206
207 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
208 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
209
210 if (strcmp(namebuf, name) == 0)
211 return kallsyms_sym_address(i);
212 }
213 return module_kallsyms_lookup_name(name);
214}
215EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
216
217int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
218 unsigned long),
219 void *data)
220{
221 char namebuf[KSYM_NAME_LEN];
222 unsigned long i;
223 unsigned int off;
224 int ret;
225
226 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
227 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
228 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
229 if (ret != 0)
230 return ret;
231 }
232 return module_kallsyms_on_each_symbol(fn, data);
233}
234EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
235
236static unsigned long get_symbol_pos(unsigned long addr,
237 unsigned long *symbolsize,
238 unsigned long *offset)
239{
240 unsigned long symbol_start = 0, symbol_end = 0;
241 unsigned long i, low, high, mid;
242
243 /* This kernel should never had been booted. */
244 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
245 BUG_ON(!kallsyms_addresses);
246 else
247 BUG_ON(!kallsyms_offsets);
248
249 /* Do a binary search on the sorted kallsyms_addresses array. */
250 low = 0;
251 high = kallsyms_num_syms;
252
253 while (high - low > 1) {
254 mid = low + (high - low) / 2;
255 if (kallsyms_sym_address(mid) <= addr)
256 low = mid;
257 else
258 high = mid;
259 }
260
261 /*
262 * Search for the first aliased symbol. Aliased
263 * symbols are symbols with the same address.
264 */
265 while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
266 --low;
267
268 symbol_start = kallsyms_sym_address(low);
269
270 /* Search for next non-aliased symbol. */
271 for (i = low + 1; i < kallsyms_num_syms; i++) {
272 if (kallsyms_sym_address(i) > symbol_start) {
273 symbol_end = kallsyms_sym_address(i);
274 break;
275 }
276 }
277
278 /* If we found no next symbol, we use the end of the section. */
279 if (!symbol_end) {
280 if (is_kernel_inittext(addr))
281 symbol_end = (unsigned long)_einittext;
282 else if (all_var)
283 symbol_end = (unsigned long)_end;
284 else
285 symbol_end = (unsigned long)_etext;
286 }
287
288 if (symbolsize)
289 *symbolsize = symbol_end - symbol_start;
290 if (offset)
291 *offset = addr - symbol_start;
292
293 return low;
294}
295
296/*
297 * Lookup an address but don't bother to find any names.
298 */
299int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
300 unsigned long *offset)
301{
302 char namebuf[KSYM_NAME_LEN];
303 if (is_ksym_addr(addr))
304 return !!get_symbol_pos(addr, symbolsize, offset);
305
306 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
307}
308
309/*
310 * Lookup an address
311 * - modname is set to NULL if it's in the kernel.
312 * - We guarantee that the returned name is valid until we reschedule even if.
313 * It resides in a module.
314 * - We also guarantee that modname will be valid until rescheduled.
315 */
316const char *kallsyms_lookup(unsigned long addr,
317 unsigned long *symbolsize,
318 unsigned long *offset,
319 char **modname, char *namebuf)
320{
321 namebuf[KSYM_NAME_LEN - 1] = 0;
322 namebuf[0] = 0;
323
324 if (is_ksym_addr(addr)) {
325 unsigned long pos;
326
327 pos = get_symbol_pos(addr, symbolsize, offset);
328 /* Grab name */
329 kallsyms_expand_symbol(get_symbol_offset(pos),
330 namebuf, KSYM_NAME_LEN);
331 if (modname)
332 *modname = NULL;
333 return namebuf;
334 }
335
336 /* See if it's in a module. */
337 return module_address_lookup(addr, symbolsize, offset, modname,
338 namebuf);
339}
340
341int lookup_symbol_name(unsigned long addr, char *symname)
342{
343 symname[0] = '\0';
344 symname[KSYM_NAME_LEN - 1] = '\0';
345
346 if (is_ksym_addr(addr)) {
347 unsigned long pos;
348
349 pos = get_symbol_pos(addr, NULL, NULL);
350 /* Grab name */
351 kallsyms_expand_symbol(get_symbol_offset(pos),
352 symname, KSYM_NAME_LEN);
353 return 0;
354 }
355 /* See if it's in a module. */
356 return lookup_module_symbol_name(addr, symname);
357}
358
359int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
360 unsigned long *offset, char *modname, char *name)
361{
362 name[0] = '\0';
363 name[KSYM_NAME_LEN - 1] = '\0';
364
365 if (is_ksym_addr(addr)) {
366 unsigned long pos;
367
368 pos = get_symbol_pos(addr, size, offset);
369 /* Grab name */
370 kallsyms_expand_symbol(get_symbol_offset(pos),
371 name, KSYM_NAME_LEN);
372 modname[0] = '\0';
373 return 0;
374 }
375 /* See if it's in a module. */
376 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
377}
378
379/* Look up a kernel symbol and return it in a text buffer. */
380static int __sprint_symbol(char *buffer, unsigned long address,
381 int symbol_offset, int add_offset)
382{
383 char *modname;
384 const char *name;
385 unsigned long offset, size;
386 int len;
387
388 address += symbol_offset;
389 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
390 if (!name)
391 return sprintf(buffer, "0x%lx", address - symbol_offset);
392
393 if (name != buffer)
394 strcpy(buffer, name);
395 len = strlen(buffer);
396 offset -= symbol_offset;
397
398 if (add_offset)
399 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
400
401 if (modname)
402 len += sprintf(buffer + len, " [%s]", modname);
403
404 return len;
405}
406
407/**
408 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
409 * @buffer: buffer to be stored
410 * @address: address to lookup
411 *
412 * This function looks up a kernel symbol with @address and stores its name,
413 * offset, size and module name to @buffer if possible. If no symbol was found,
414 * just saves its @address as is.
415 *
416 * This function returns the number of bytes stored in @buffer.
417 */
418int sprint_symbol(char *buffer, unsigned long address)
419{
420 return __sprint_symbol(buffer, address, 0, 1);
421}
422EXPORT_SYMBOL_GPL(sprint_symbol);
423
424/**
425 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
426 * @buffer: buffer to be stored
427 * @address: address to lookup
428 *
429 * This function looks up a kernel symbol with @address and stores its name
430 * and module name to @buffer if possible. If no symbol was found, just saves
431 * its @address as is.
432 *
433 * This function returns the number of bytes stored in @buffer.
434 */
435int sprint_symbol_no_offset(char *buffer, unsigned long address)
436{
437 return __sprint_symbol(buffer, address, 0, 0);
438}
439EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
440
441/**
442 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
443 * @buffer: buffer to be stored
444 * @address: address to lookup
445 *
446 * This function is for stack backtrace and does the same thing as
447 * sprint_symbol() but with modified/decreased @address. If there is a
448 * tail-call to the function marked "noreturn", gcc optimized out code after
449 * the call so that the stack-saved return address could point outside of the
450 * caller. This function ensures that kallsyms will find the original caller
451 * by decreasing @address.
452 *
453 * This function returns the number of bytes stored in @buffer.
454 */
455int sprint_backtrace(char *buffer, unsigned long address)
456{
457 return __sprint_symbol(buffer, address, -1, 1);
458}
459
460/* Look up a kernel symbol and print it to the kernel messages. */
461void __print_symbol(const char *fmt, unsigned long address)
462{
463 char buffer[KSYM_SYMBOL_LEN];
464
465 sprint_symbol(buffer, address);
466
467 printk(fmt, buffer);
468}
469EXPORT_SYMBOL(__print_symbol);
470
471/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
472struct kallsym_iter {
473 loff_t pos;
474 unsigned long value;
475 unsigned int nameoff; /* If iterating in core kernel symbols. */
476 char type;
477 char name[KSYM_NAME_LEN];
478 char module_name[MODULE_NAME_LEN];
479 int exported;
480};
481
482static int get_ksymbol_mod(struct kallsym_iter *iter)
483{
484 if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
485 &iter->type, iter->name, iter->module_name,
486 &iter->exported) < 0)
487 return 0;
488 return 1;
489}
490
491/* Returns space to next name. */
492static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
493{
494 unsigned off = iter->nameoff;
495
496 iter->module_name[0] = '\0';
497 iter->value = kallsyms_sym_address(iter->pos);
498
499 iter->type = kallsyms_get_symbol_type(off);
500
501 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
502
503 return off - iter->nameoff;
504}
505
506static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
507{
508 iter->name[0] = '\0';
509 iter->nameoff = get_symbol_offset(new_pos);
510 iter->pos = new_pos;
511}
512
513/* Returns false if pos at or past end of file. */
514static int update_iter(struct kallsym_iter *iter, loff_t pos)
515{
516 /* Module symbols can be accessed randomly. */
517 if (pos >= kallsyms_num_syms) {
518 iter->pos = pos;
519 return get_ksymbol_mod(iter);
520 }
521
522 /* If we're not on the desired position, reset to new position. */
523 if (pos != iter->pos)
524 reset_iter(iter, pos);
525
526 iter->nameoff += get_ksymbol_core(iter);
527 iter->pos++;
528
529 return 1;
530}
531
532static void *s_next(struct seq_file *m, void *p, loff_t *pos)
533{
534 (*pos)++;
535
536 if (!update_iter(m->private, *pos))
537 return NULL;
538 return p;
539}
540
541static void *s_start(struct seq_file *m, loff_t *pos)
542{
543 if (!update_iter(m->private, *pos))
544 return NULL;
545 return m->private;
546}
547
548static void s_stop(struct seq_file *m, void *p)
549{
550}
551
552static int s_show(struct seq_file *m, void *p)
553{
554 struct kallsym_iter *iter = m->private;
555
556 /* Some debugging symbols have no name. Ignore them. */
557 if (!iter->name[0])
558 return 0;
559
560 if (iter->module_name[0]) {
561 char type;
562
563 /*
564 * Label it "global" if it is exported,
565 * "local" if not exported.
566 */
567 type = iter->exported ? toupper(iter->type) :
568 tolower(iter->type);
569 seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
570 type, iter->name, iter->module_name);
571 } else
572 seq_printf(m, "%pK %c %s\n", (void *)iter->value,
573 iter->type, iter->name);
574 return 0;
575}
576
577static const struct seq_operations kallsyms_op = {
578 .start = s_start,
579 .next = s_next,
580 .stop = s_stop,
581 .show = s_show
582};
583
584static int kallsyms_open(struct inode *inode, struct file *file)
585{
586 /*
587 * We keep iterator in m->private, since normal case is to
588 * s_start from where we left off, so we avoid doing
589 * using get_symbol_offset for every symbol.
590 */
591 struct kallsym_iter *iter;
592 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
593 if (!iter)
594 return -ENOMEM;
595 reset_iter(iter, 0);
596
597 return 0;
598}
599
600#ifdef CONFIG_KGDB_KDB
601const char *kdb_walk_kallsyms(loff_t *pos)
602{
603 static struct kallsym_iter kdb_walk_kallsyms_iter;
604 if (*pos == 0) {
605 memset(&kdb_walk_kallsyms_iter, 0,
606 sizeof(kdb_walk_kallsyms_iter));
607 reset_iter(&kdb_walk_kallsyms_iter, 0);
608 }
609 while (1) {
610 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
611 return NULL;
612 ++*pos;
613 /* Some debugging symbols have no name. Ignore them. */
614 if (kdb_walk_kallsyms_iter.name[0])
615 return kdb_walk_kallsyms_iter.name;
616 }
617}
618#endif /* CONFIG_KGDB_KDB */
619
620static const struct file_operations kallsyms_operations = {
621 .open = kallsyms_open,
622 .read = seq_read,
623 .llseek = seq_lseek,
624 .release = seq_release_private,
625};
626
627static int __init kallsyms_init(void)
628{
629 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
630 return 0;
631}
632device_initcall(kallsyms_init);
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/init.h>
16#include <linux/seq_file.h>
17#include <linux/fs.h>
18#include <linux/kdb.h>
19#include <linux/err.h>
20#include <linux/proc_fs.h>
21#include <linux/sched.h> /* for cond_resched */
22#include <linux/ctype.h>
23#include <linux/slab.h>
24#include <linux/filter.h>
25#include <linux/ftrace.h>
26#include <linux/compiler.h>
27
28/*
29 * These will be re-linked against their real values
30 * during the second link stage.
31 */
32extern const unsigned long kallsyms_addresses[] __weak;
33extern const int kallsyms_offsets[] __weak;
34extern const u8 kallsyms_names[] __weak;
35
36/*
37 * Tell the compiler that the count isn't in the small data section if the arch
38 * has one (eg: FRV).
39 */
40extern const unsigned long kallsyms_num_syms
41__attribute__((weak, section(".rodata")));
42
43extern const unsigned long kallsyms_relative_base
44__attribute__((weak, section(".rodata")));
45
46extern const u8 kallsyms_token_table[] __weak;
47extern const u16 kallsyms_token_index[] __weak;
48
49extern const unsigned long kallsyms_markers[] __weak;
50
51/*
52 * Expand a compressed symbol data into the resulting uncompressed string,
53 * if uncompressed string is too long (>= maxlen), it will be truncated,
54 * given the offset to where the symbol is in the compressed stream.
55 */
56static unsigned int kallsyms_expand_symbol(unsigned int off,
57 char *result, size_t maxlen)
58{
59 int len, skipped_first = 0;
60 const u8 *tptr, *data;
61
62 /* Get the compressed symbol length from the first symbol byte. */
63 data = &kallsyms_names[off];
64 len = *data;
65 data++;
66
67 /*
68 * Update the offset to return the offset for the next symbol on
69 * the compressed stream.
70 */
71 off += len + 1;
72
73 /*
74 * For every byte on the compressed symbol data, copy the table
75 * entry for that byte.
76 */
77 while (len) {
78 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
79 data++;
80 len--;
81
82 while (*tptr) {
83 if (skipped_first) {
84 if (maxlen <= 1)
85 goto tail;
86 *result = *tptr;
87 result++;
88 maxlen--;
89 } else
90 skipped_first = 1;
91 tptr++;
92 }
93 }
94
95tail:
96 if (maxlen)
97 *result = '\0';
98
99 /* Return to offset to the next symbol. */
100 return off;
101}
102
103/*
104 * Get symbol type information. This is encoded as a single char at the
105 * beginning of the symbol name.
106 */
107static char kallsyms_get_symbol_type(unsigned int off)
108{
109 /*
110 * Get just the first code, look it up in the token table,
111 * and return the first char from this token.
112 */
113 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
114}
115
116
117/*
118 * Find the offset on the compressed stream given and index in the
119 * kallsyms array.
120 */
121static unsigned int get_symbol_offset(unsigned long pos)
122{
123 const u8 *name;
124 int i;
125
126 /*
127 * Use the closest marker we have. We have markers every 256 positions,
128 * so that should be close enough.
129 */
130 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
131
132 /*
133 * Sequentially scan all the symbols up to the point we're searching
134 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
135 * so we just need to add the len to the current pointer for every
136 * symbol we wish to skip.
137 */
138 for (i = 0; i < (pos & 0xFF); i++)
139 name = name + (*name) + 1;
140
141 return name - kallsyms_names;
142}
143
144static unsigned long kallsyms_sym_address(int idx)
145{
146 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
147 return kallsyms_addresses[idx];
148
149 /* values are unsigned offsets if --absolute-percpu is not in effect */
150 if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
151 return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
152
153 /* ...otherwise, positive offsets are absolute values */
154 if (kallsyms_offsets[idx] >= 0)
155 return kallsyms_offsets[idx];
156
157 /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
158 return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
159}
160
161/* Lookup the address for this symbol. Returns 0 if not found. */
162unsigned long kallsyms_lookup_name(const char *name)
163{
164 char namebuf[KSYM_NAME_LEN];
165 unsigned long i;
166 unsigned int off;
167
168 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
169 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
170
171 if (strcmp(namebuf, name) == 0)
172 return kallsyms_sym_address(i);
173 }
174 return module_kallsyms_lookup_name(name);
175}
176EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
177
178int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
179 unsigned long),
180 void *data)
181{
182 char namebuf[KSYM_NAME_LEN];
183 unsigned long i;
184 unsigned int off;
185 int ret;
186
187 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
188 off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
189 ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
190 if (ret != 0)
191 return ret;
192 }
193 return module_kallsyms_on_each_symbol(fn, data);
194}
195EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
196
197static unsigned long get_symbol_pos(unsigned long addr,
198 unsigned long *symbolsize,
199 unsigned long *offset)
200{
201 unsigned long symbol_start = 0, symbol_end = 0;
202 unsigned long i, low, high, mid;
203
204 /* This kernel should never had been booted. */
205 if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
206 BUG_ON(!kallsyms_addresses);
207 else
208 BUG_ON(!kallsyms_offsets);
209
210 /* Do a binary search on the sorted kallsyms_addresses array. */
211 low = 0;
212 high = kallsyms_num_syms;
213
214 while (high - low > 1) {
215 mid = low + (high - low) / 2;
216 if (kallsyms_sym_address(mid) <= addr)
217 low = mid;
218 else
219 high = mid;
220 }
221
222 /*
223 * Search for the first aliased symbol. Aliased
224 * symbols are symbols with the same address.
225 */
226 while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
227 --low;
228
229 symbol_start = kallsyms_sym_address(low);
230
231 /* Search for next non-aliased symbol. */
232 for (i = low + 1; i < kallsyms_num_syms; i++) {
233 if (kallsyms_sym_address(i) > symbol_start) {
234 symbol_end = kallsyms_sym_address(i);
235 break;
236 }
237 }
238
239 /* If we found no next symbol, we use the end of the section. */
240 if (!symbol_end) {
241 if (is_kernel_inittext(addr))
242 symbol_end = (unsigned long)_einittext;
243 else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
244 symbol_end = (unsigned long)_end;
245 else
246 symbol_end = (unsigned long)_etext;
247 }
248
249 if (symbolsize)
250 *symbolsize = symbol_end - symbol_start;
251 if (offset)
252 *offset = addr - symbol_start;
253
254 return low;
255}
256
257/*
258 * Lookup an address but don't bother to find any names.
259 */
260int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
261 unsigned long *offset)
262{
263 char namebuf[KSYM_NAME_LEN];
264
265 if (is_ksym_addr(addr))
266 return !!get_symbol_pos(addr, symbolsize, offset);
267 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) ||
268 !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
269}
270
271/*
272 * Lookup an address
273 * - modname is set to NULL if it's in the kernel.
274 * - We guarantee that the returned name is valid until we reschedule even if.
275 * It resides in a module.
276 * - We also guarantee that modname will be valid until rescheduled.
277 */
278const char *kallsyms_lookup(unsigned long addr,
279 unsigned long *symbolsize,
280 unsigned long *offset,
281 char **modname, char *namebuf)
282{
283 const char *ret;
284
285 namebuf[KSYM_NAME_LEN - 1] = 0;
286 namebuf[0] = 0;
287
288 if (is_ksym_addr(addr)) {
289 unsigned long pos;
290
291 pos = get_symbol_pos(addr, symbolsize, offset);
292 /* Grab name */
293 kallsyms_expand_symbol(get_symbol_offset(pos),
294 namebuf, KSYM_NAME_LEN);
295 if (modname)
296 *modname = NULL;
297 return namebuf;
298 }
299
300 /* See if it's in a module or a BPF JITed image. */
301 ret = module_address_lookup(addr, symbolsize, offset,
302 modname, namebuf);
303 if (!ret)
304 ret = bpf_address_lookup(addr, symbolsize,
305 offset, modname, namebuf);
306
307 if (!ret)
308 ret = ftrace_mod_address_lookup(addr, symbolsize,
309 offset, modname, namebuf);
310 return ret;
311}
312
313int lookup_symbol_name(unsigned long addr, char *symname)
314{
315 symname[0] = '\0';
316 symname[KSYM_NAME_LEN - 1] = '\0';
317
318 if (is_ksym_addr(addr)) {
319 unsigned long pos;
320
321 pos = get_symbol_pos(addr, NULL, NULL);
322 /* Grab name */
323 kallsyms_expand_symbol(get_symbol_offset(pos),
324 symname, KSYM_NAME_LEN);
325 return 0;
326 }
327 /* See if it's in a module. */
328 return lookup_module_symbol_name(addr, symname);
329}
330
331int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
332 unsigned long *offset, char *modname, char *name)
333{
334 name[0] = '\0';
335 name[KSYM_NAME_LEN - 1] = '\0';
336
337 if (is_ksym_addr(addr)) {
338 unsigned long pos;
339
340 pos = get_symbol_pos(addr, size, offset);
341 /* Grab name */
342 kallsyms_expand_symbol(get_symbol_offset(pos),
343 name, KSYM_NAME_LEN);
344 modname[0] = '\0';
345 return 0;
346 }
347 /* See if it's in a module. */
348 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
349}
350
351/* Look up a kernel symbol and return it in a text buffer. */
352static int __sprint_symbol(char *buffer, unsigned long address,
353 int symbol_offset, int add_offset)
354{
355 char *modname;
356 const char *name;
357 unsigned long offset, size;
358 int len;
359
360 address += symbol_offset;
361 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
362 if (!name)
363 return sprintf(buffer, "0x%lx", address - symbol_offset);
364
365 if (name != buffer)
366 strcpy(buffer, name);
367 len = strlen(buffer);
368 offset -= symbol_offset;
369
370 if (add_offset)
371 len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
372
373 if (modname)
374 len += sprintf(buffer + len, " [%s]", modname);
375
376 return len;
377}
378
379/**
380 * sprint_symbol - Look up a kernel symbol and return it in a text buffer
381 * @buffer: buffer to be stored
382 * @address: address to lookup
383 *
384 * This function looks up a kernel symbol with @address and stores its name,
385 * offset, size and module name to @buffer if possible. If no symbol was found,
386 * just saves its @address as is.
387 *
388 * This function returns the number of bytes stored in @buffer.
389 */
390int sprint_symbol(char *buffer, unsigned long address)
391{
392 return __sprint_symbol(buffer, address, 0, 1);
393}
394EXPORT_SYMBOL_GPL(sprint_symbol);
395
396/**
397 * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
398 * @buffer: buffer to be stored
399 * @address: address to lookup
400 *
401 * This function looks up a kernel symbol with @address and stores its name
402 * and module name to @buffer if possible. If no symbol was found, just saves
403 * its @address as is.
404 *
405 * This function returns the number of bytes stored in @buffer.
406 */
407int sprint_symbol_no_offset(char *buffer, unsigned long address)
408{
409 return __sprint_symbol(buffer, address, 0, 0);
410}
411EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
412
413/**
414 * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
415 * @buffer: buffer to be stored
416 * @address: address to lookup
417 *
418 * This function is for stack backtrace and does the same thing as
419 * sprint_symbol() but with modified/decreased @address. If there is a
420 * tail-call to the function marked "noreturn", gcc optimized out code after
421 * the call so that the stack-saved return address could point outside of the
422 * caller. This function ensures that kallsyms will find the original caller
423 * by decreasing @address.
424 *
425 * This function returns the number of bytes stored in @buffer.
426 */
427int sprint_backtrace(char *buffer, unsigned long address)
428{
429 return __sprint_symbol(buffer, address, -1, 1);
430}
431
432/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
433struct kallsym_iter {
434 loff_t pos;
435 loff_t pos_mod_end;
436 loff_t pos_ftrace_mod_end;
437 unsigned long value;
438 unsigned int nameoff; /* If iterating in core kernel symbols. */
439 char type;
440 char name[KSYM_NAME_LEN];
441 char module_name[MODULE_NAME_LEN];
442 int exported;
443 int show_value;
444};
445
446static int get_ksymbol_mod(struct kallsym_iter *iter)
447{
448 int ret = module_get_kallsym(iter->pos - kallsyms_num_syms,
449 &iter->value, &iter->type,
450 iter->name, iter->module_name,
451 &iter->exported);
452 if (ret < 0) {
453 iter->pos_mod_end = iter->pos;
454 return 0;
455 }
456
457 return 1;
458}
459
460static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
461{
462 int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
463 &iter->value, &iter->type,
464 iter->name, iter->module_name,
465 &iter->exported);
466 if (ret < 0) {
467 iter->pos_ftrace_mod_end = iter->pos;
468 return 0;
469 }
470
471 return 1;
472}
473
474static int get_ksymbol_bpf(struct kallsym_iter *iter)
475{
476 iter->module_name[0] = '\0';
477 iter->exported = 0;
478 return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
479 &iter->value, &iter->type,
480 iter->name) < 0 ? 0 : 1;
481}
482
483/* Returns space to next name. */
484static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
485{
486 unsigned off = iter->nameoff;
487
488 iter->module_name[0] = '\0';
489 iter->value = kallsyms_sym_address(iter->pos);
490
491 iter->type = kallsyms_get_symbol_type(off);
492
493 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
494
495 return off - iter->nameoff;
496}
497
498static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
499{
500 iter->name[0] = '\0';
501 iter->nameoff = get_symbol_offset(new_pos);
502 iter->pos = new_pos;
503 if (new_pos == 0) {
504 iter->pos_mod_end = 0;
505 iter->pos_ftrace_mod_end = 0;
506 }
507}
508
509static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
510{
511 iter->pos = pos;
512
513 if (iter->pos_ftrace_mod_end > 0 &&
514 iter->pos_ftrace_mod_end < iter->pos)
515 return get_ksymbol_bpf(iter);
516
517 if (iter->pos_mod_end > 0 &&
518 iter->pos_mod_end < iter->pos) {
519 if (!get_ksymbol_ftrace_mod(iter))
520 return get_ksymbol_bpf(iter);
521 return 1;
522 }
523
524 if (!get_ksymbol_mod(iter)) {
525 if (!get_ksymbol_ftrace_mod(iter))
526 return get_ksymbol_bpf(iter);
527 }
528
529 return 1;
530}
531
532/* Returns false if pos at or past end of file. */
533static int update_iter(struct kallsym_iter *iter, loff_t pos)
534{
535 /* Module symbols can be accessed randomly. */
536 if (pos >= kallsyms_num_syms)
537 return update_iter_mod(iter, pos);
538
539 /* If we're not on the desired position, reset to new position. */
540 if (pos != iter->pos)
541 reset_iter(iter, pos);
542
543 iter->nameoff += get_ksymbol_core(iter);
544 iter->pos++;
545
546 return 1;
547}
548
549static void *s_next(struct seq_file *m, void *p, loff_t *pos)
550{
551 (*pos)++;
552
553 if (!update_iter(m->private, *pos))
554 return NULL;
555 return p;
556}
557
558static void *s_start(struct seq_file *m, loff_t *pos)
559{
560 if (!update_iter(m->private, *pos))
561 return NULL;
562 return m->private;
563}
564
565static void s_stop(struct seq_file *m, void *p)
566{
567}
568
569static int s_show(struct seq_file *m, void *p)
570{
571 void *value;
572 struct kallsym_iter *iter = m->private;
573
574 /* Some debugging symbols have no name. Ignore them. */
575 if (!iter->name[0])
576 return 0;
577
578 value = iter->show_value ? (void *)iter->value : NULL;
579
580 if (iter->module_name[0]) {
581 char type;
582
583 /*
584 * Label it "global" if it is exported,
585 * "local" if not exported.
586 */
587 type = iter->exported ? toupper(iter->type) :
588 tolower(iter->type);
589 seq_printf(m, "%px %c %s\t[%s]\n", value,
590 type, iter->name, iter->module_name);
591 } else
592 seq_printf(m, "%px %c %s\n", value,
593 iter->type, iter->name);
594 return 0;
595}
596
597static const struct seq_operations kallsyms_op = {
598 .start = s_start,
599 .next = s_next,
600 .stop = s_stop,
601 .show = s_show
602};
603
604static inline int kallsyms_for_perf(void)
605{
606#ifdef CONFIG_PERF_EVENTS
607 extern int sysctl_perf_event_paranoid;
608 if (sysctl_perf_event_paranoid <= 1)
609 return 1;
610#endif
611 return 0;
612}
613
614/*
615 * We show kallsyms information even to normal users if we've enabled
616 * kernel profiling and are explicitly not paranoid (so kptr_restrict
617 * is clear, and sysctl_perf_event_paranoid isn't set).
618 *
619 * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
620 * block even that).
621 */
622int kallsyms_show_value(void)
623{
624 switch (kptr_restrict) {
625 case 0:
626 if (kallsyms_for_perf())
627 return 1;
628 /* fallthrough */
629 case 1:
630 if (has_capability_noaudit(current, CAP_SYSLOG))
631 return 1;
632 /* fallthrough */
633 default:
634 return 0;
635 }
636}
637
638static int kallsyms_open(struct inode *inode, struct file *file)
639{
640 /*
641 * We keep iterator in m->private, since normal case is to
642 * s_start from where we left off, so we avoid doing
643 * using get_symbol_offset for every symbol.
644 */
645 struct kallsym_iter *iter;
646 iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
647 if (!iter)
648 return -ENOMEM;
649 reset_iter(iter, 0);
650
651 iter->show_value = kallsyms_show_value();
652 return 0;
653}
654
655#ifdef CONFIG_KGDB_KDB
656const char *kdb_walk_kallsyms(loff_t *pos)
657{
658 static struct kallsym_iter kdb_walk_kallsyms_iter;
659 if (*pos == 0) {
660 memset(&kdb_walk_kallsyms_iter, 0,
661 sizeof(kdb_walk_kallsyms_iter));
662 reset_iter(&kdb_walk_kallsyms_iter, 0);
663 }
664 while (1) {
665 if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
666 return NULL;
667 ++*pos;
668 /* Some debugging symbols have no name. Ignore them. */
669 if (kdb_walk_kallsyms_iter.name[0])
670 return kdb_walk_kallsyms_iter.name;
671 }
672}
673#endif /* CONFIG_KGDB_KDB */
674
675static const struct file_operations kallsyms_operations = {
676 .open = kallsyms_open,
677 .read = seq_read,
678 .llseek = seq_lseek,
679 .release = seq_release_private,
680};
681
682static int __init kallsyms_init(void)
683{
684 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
685 return 0;
686}
687device_initcall(kallsyms_init);