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