Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
4 : *
5 : * Rewritten and vastly simplified by Rusty Russell for in-kernel
6 : * module loader:
7 : * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
8 : *
9 : * ChangeLog:
10 : *
11 : * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
12 : * Changed the compression method from stem compression to "table lookup"
13 : * compression (see scripts/kallsyms.c for a more complete description)
14 : */
15 : #include <linux/kallsyms.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/ctype.h>
24 : #include <linux/slab.h>
25 : #include <linux/filter.h>
26 : #include <linux/ftrace.h>
27 : #include <linux/kprobes.h>
28 : #include <linux/build_bug.h>
29 : #include <linux/compiler.h>
30 : #include <linux/module.h>
31 : #include <linux/kernel.h>
32 : #include <linux/bsearch.h>
33 : #include <linux/btf_ids.h>
34 :
35 : #include "kallsyms_internal.h"
36 :
37 : /*
38 : * Expand a compressed symbol data into the resulting uncompressed string,
39 : * if uncompressed string is too long (>= maxlen), it will be truncated,
40 : * given the offset to where the symbol is in the compressed stream.
41 : */
42 56 : static unsigned int kallsyms_expand_symbol(unsigned int off,
43 : char *result, size_t maxlen)
44 : {
45 56 : int len, skipped_first = 0;
46 : const char *tptr;
47 : const u8 *data;
48 :
49 : /* Get the compressed symbol length from the first symbol byte. */
50 56 : data = &kallsyms_names[off];
51 56 : len = *data;
52 56 : data++;
53 56 : off++;
54 :
55 : /* If MSB is 1, it is a "big" symbol, so needs an additional byte. */
56 56 : if ((len & 0x80) != 0) {
57 0 : len = (len & 0x7F) | (*data << 7);
58 0 : data++;
59 0 : off++;
60 : }
61 :
62 : /*
63 : * Update the offset to return the offset for the next symbol on
64 : * the compressed stream.
65 : */
66 56 : off += len;
67 :
68 : /*
69 : * For every byte on the compressed symbol data, copy the table
70 : * entry for that byte.
71 : */
72 576 : while (len) {
73 464 : tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
74 464 : data++;
75 464 : len--;
76 :
77 1738 : while (*tptr) {
78 810 : if (skipped_first) {
79 754 : if (maxlen <= 1)
80 : goto tail;
81 754 : *result = *tptr;
82 754 : result++;
83 754 : maxlen--;
84 : } else
85 : skipped_first = 1;
86 810 : tptr++;
87 : }
88 : }
89 :
90 : tail:
91 56 : if (maxlen)
92 56 : *result = '\0';
93 :
94 : /* Return to offset to the next symbol. */
95 56 : return off;
96 : }
97 :
98 : /*
99 : * Get symbol type information. This is encoded as a single char at the
100 : * beginning of the symbol name.
101 : */
102 : static char kallsyms_get_symbol_type(unsigned int off)
103 : {
104 : /*
105 : * Get just the first code, look it up in the token table,
106 : * and return the first char from this token.
107 : */
108 0 : return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
109 : }
110 :
111 :
112 : /*
113 : * Find the offset on the compressed stream given and index in the
114 : * kallsyms array.
115 : */
116 : static unsigned int get_symbol_offset(unsigned long pos)
117 : {
118 : const u8 *name;
119 : int i, len;
120 :
121 : /*
122 : * Use the closest marker we have. We have markers every 256 positions,
123 : * so that should be close enough.
124 : */
125 56 : name = &kallsyms_names[kallsyms_markers[pos >> 8]];
126 :
127 : /*
128 : * Sequentially scan all the symbols up to the point we're searching
129 : * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
130 : * so we just need to add the len to the current pointer for every
131 : * symbol we wish to skip.
132 : */
133 6104 : for (i = 0; i < (pos & 0xFF); i++) {
134 6048 : len = *name;
135 :
136 : /*
137 : * If MSB is 1, it is a "big" symbol, so we need to look into
138 : * the next byte (and skip it, too).
139 : */
140 6048 : if ((len & 0x80) != 0)
141 0 : len = ((len & 0x7F) | (name[1] << 7)) + 1;
142 :
143 6048 : name = name + len + 1;
144 : }
145 :
146 56 : return name - kallsyms_names;
147 : }
148 :
149 0 : unsigned long kallsyms_sym_address(int idx)
150 : {
151 : if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
152 : return kallsyms_addresses[idx];
153 :
154 : /* values are unsigned offsets if --absolute-percpu is not in effect */
155 : if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
156 1002 : return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
157 :
158 : /* ...otherwise, positive offsets are absolute values */
159 : if (kallsyms_offsets[idx] >= 0)
160 : return kallsyms_offsets[idx];
161 :
162 : /* ...and negative offsets are relative to kallsyms_relative_base - 1 */
163 : return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
164 : }
165 :
166 : static bool cleanup_symbol_name(char *s)
167 : {
168 : char *res;
169 :
170 : if (!IS_ENABLED(CONFIG_LTO_CLANG))
171 : return false;
172 :
173 : /*
174 : * LLVM appends various suffixes for local functions and variables that
175 : * must be promoted to global scope as part of LTO. This can break
176 : * hooking of static functions with kprobes. '.' is not a valid
177 : * character in an identifier in C. Suffixes only in LLVM LTO observed:
178 : * - foo.llvm.[0-9a-f]+
179 : */
180 : res = strstr(s, ".llvm.");
181 : if (res) {
182 : *res = '\0';
183 : return true;
184 : }
185 :
186 : return false;
187 : }
188 :
189 : static int compare_symbol_name(const char *name, char *namebuf)
190 : {
191 : int ret;
192 :
193 0 : ret = strcmp(name, namebuf);
194 : if (!ret)
195 : return ret;
196 :
197 : if (cleanup_symbol_name(namebuf) && !strcmp(name, namebuf))
198 : return 0;
199 :
200 : return ret;
201 : }
202 :
203 : static unsigned int get_symbol_seq(int index)
204 : {
205 0 : unsigned int i, seq = 0;
206 :
207 0 : for (i = 0; i < 3; i++)
208 0 : seq = (seq << 8) | kallsyms_seqs_of_names[3 * index + i];
209 :
210 : return seq;
211 : }
212 :
213 0 : static int kallsyms_lookup_names(const char *name,
214 : unsigned int *start,
215 : unsigned int *end)
216 : {
217 : int ret;
218 : int low, mid, high;
219 : unsigned int seq, off;
220 : char namebuf[KSYM_NAME_LEN];
221 :
222 0 : low = 0;
223 0 : high = kallsyms_num_syms - 1;
224 :
225 0 : while (low <= high) {
226 0 : mid = low + (high - low) / 2;
227 0 : seq = get_symbol_seq(mid);
228 0 : off = get_symbol_offset(seq);
229 0 : kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
230 0 : ret = compare_symbol_name(name, namebuf);
231 0 : if (ret > 0)
232 0 : low = mid + 1;
233 0 : else if (ret < 0)
234 0 : high = mid - 1;
235 : else
236 : break;
237 : }
238 :
239 0 : if (low > high)
240 : return -ESRCH;
241 :
242 : low = mid;
243 0 : while (low) {
244 0 : seq = get_symbol_seq(low - 1);
245 0 : off = get_symbol_offset(seq);
246 0 : kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
247 0 : if (compare_symbol_name(name, namebuf))
248 : break;
249 : low--;
250 : }
251 0 : *start = low;
252 :
253 0 : if (end) {
254 : high = mid;
255 0 : while (high < kallsyms_num_syms - 1) {
256 0 : seq = get_symbol_seq(high + 1);
257 0 : off = get_symbol_offset(seq);
258 0 : kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
259 0 : if (compare_symbol_name(name, namebuf))
260 : break;
261 : high++;
262 : }
263 0 : *end = high;
264 : }
265 :
266 : return 0;
267 : }
268 :
269 : /* Lookup the address for this symbol. Returns 0 if not found. */
270 0 : unsigned long kallsyms_lookup_name(const char *name)
271 : {
272 : int ret;
273 : unsigned int i;
274 :
275 : /* Skip the search for empty string. */
276 0 : if (!*name)
277 : return 0;
278 :
279 0 : ret = kallsyms_lookup_names(name, &i, NULL);
280 0 : if (!ret)
281 0 : return kallsyms_sym_address(get_symbol_seq(i));
282 :
283 : return module_kallsyms_lookup_name(name);
284 : }
285 :
286 : /*
287 : * Iterate over all symbols in vmlinux. For symbols from modules use
288 : * module_kallsyms_on_each_symbol instead.
289 : */
290 0 : int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long),
291 : void *data)
292 : {
293 : char namebuf[KSYM_NAME_LEN];
294 : unsigned long i;
295 : unsigned int off;
296 : int ret;
297 :
298 0 : for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
299 0 : off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
300 0 : ret = fn(data, namebuf, kallsyms_sym_address(i));
301 0 : if (ret != 0)
302 : return ret;
303 0 : cond_resched();
304 : }
305 : return 0;
306 : }
307 :
308 0 : int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long),
309 : const char *name, void *data)
310 : {
311 : int ret;
312 : unsigned int i, start, end;
313 :
314 0 : ret = kallsyms_lookup_names(name, &start, &end);
315 0 : if (ret)
316 : return 0;
317 :
318 0 : for (i = start; !ret && i <= end; i++) {
319 0 : ret = fn(data, kallsyms_sym_address(get_symbol_seq(i)));
320 0 : cond_resched();
321 : }
322 :
323 : return ret;
324 : }
325 :
326 56 : static unsigned long get_symbol_pos(unsigned long addr,
327 : unsigned long *symbolsize,
328 : unsigned long *offset)
329 : {
330 56 : unsigned long symbol_start = 0, symbol_end = 0;
331 : unsigned long i, low, high, mid;
332 :
333 : /* This kernel should never had been booted. */
334 : if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
335 : BUG_ON(!kallsyms_addresses);
336 : else
337 56 : BUG_ON(!kallsyms_offsets);
338 :
339 : /* Do a binary search on the sorted kallsyms_addresses array. */
340 56 : low = 0;
341 56 : high = kallsyms_num_syms;
342 :
343 890 : while (high - low > 1) {
344 778 : mid = low + (high - low) / 2;
345 1556 : if (kallsyms_sym_address(mid) <= addr)
346 : low = mid;
347 : else
348 : high = mid;
349 : }
350 :
351 : /*
352 : * Search for the first aliased symbol. Aliased
353 : * symbols are symbols with the same address.
354 : */
355 168 : while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
356 0 : --low;
357 :
358 112 : symbol_start = kallsyms_sym_address(low);
359 :
360 : /* Search for next non-aliased symbol. */
361 56 : for (i = low + 1; i < kallsyms_num_syms; i++) {
362 112 : if (kallsyms_sym_address(i) > symbol_start) {
363 : symbol_end = kallsyms_sym_address(i);
364 : break;
365 : }
366 : }
367 :
368 : /* If we found no next symbol, we use the end of the section. */
369 56 : if (!symbol_end) {
370 0 : if (is_kernel_inittext(addr))
371 0 : symbol_end = (unsigned long)_einittext;
372 : else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
373 : symbol_end = (unsigned long)_end;
374 : else
375 0 : symbol_end = (unsigned long)_etext;
376 : }
377 :
378 56 : if (symbolsize)
379 56 : *symbolsize = symbol_end - symbol_start;
380 56 : if (offset)
381 56 : *offset = addr - symbol_start;
382 :
383 56 : return low;
384 : }
385 :
386 : /*
387 : * Lookup an address but don't bother to find any names.
388 : */
389 0 : int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
390 : unsigned long *offset)
391 : {
392 : char namebuf[KSYM_NAME_LEN];
393 :
394 0 : if (is_ksym_addr(addr)) {
395 0 : get_symbol_pos(addr, symbolsize, offset);
396 0 : return 1;
397 : }
398 : return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) ||
399 : !!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
400 : }
401 :
402 56 : static const char *kallsyms_lookup_buildid(unsigned long addr,
403 : unsigned long *symbolsize,
404 : unsigned long *offset, char **modname,
405 : const unsigned char **modbuildid, char *namebuf)
406 : {
407 : const char *ret;
408 :
409 56 : namebuf[KSYM_NAME_LEN - 1] = 0;
410 56 : namebuf[0] = 0;
411 :
412 56 : if (is_ksym_addr(addr)) {
413 : unsigned long pos;
414 :
415 56 : pos = get_symbol_pos(addr, symbolsize, offset);
416 : /* Grab name */
417 56 : kallsyms_expand_symbol(get_symbol_offset(pos),
418 : namebuf, KSYM_NAME_LEN);
419 56 : if (modname)
420 56 : *modname = NULL;
421 56 : if (modbuildid)
422 56 : *modbuildid = NULL;
423 :
424 : ret = namebuf;
425 : goto found;
426 : }
427 :
428 : /* See if it's in a module or a BPF JITed image. */
429 : ret = module_address_lookup(addr, symbolsize, offset,
430 : modname, modbuildid, namebuf);
431 : if (!ret)
432 : ret = bpf_address_lookup(addr, symbolsize,
433 : offset, modname, namebuf);
434 :
435 : if (!ret)
436 : ret = ftrace_mod_address_lookup(addr, symbolsize,
437 : offset, modname, namebuf);
438 :
439 : found:
440 56 : cleanup_symbol_name(namebuf);
441 56 : return ret;
442 : }
443 :
444 : /*
445 : * Lookup an address
446 : * - modname is set to NULL if it's in the kernel.
447 : * - We guarantee that the returned name is valid until we reschedule even if.
448 : * It resides in a module.
449 : * - We also guarantee that modname will be valid until rescheduled.
450 : */
451 0 : const char *kallsyms_lookup(unsigned long addr,
452 : unsigned long *symbolsize,
453 : unsigned long *offset,
454 : char **modname, char *namebuf)
455 : {
456 0 : return kallsyms_lookup_buildid(addr, symbolsize, offset, modname,
457 : NULL, namebuf);
458 : }
459 :
460 0 : int lookup_symbol_name(unsigned long addr, char *symname)
461 : {
462 : int res;
463 :
464 0 : symname[0] = '\0';
465 0 : symname[KSYM_NAME_LEN - 1] = '\0';
466 :
467 0 : if (is_ksym_addr(addr)) {
468 : unsigned long pos;
469 :
470 0 : pos = get_symbol_pos(addr, NULL, NULL);
471 : /* Grab name */
472 0 : kallsyms_expand_symbol(get_symbol_offset(pos),
473 : symname, KSYM_NAME_LEN);
474 : goto found;
475 : }
476 : /* See if it's in a module. */
477 : res = lookup_module_symbol_name(addr, symname);
478 : if (res)
479 : return res;
480 :
481 : found:
482 0 : cleanup_symbol_name(symname);
483 0 : return 0;
484 : }
485 :
486 : /* Look up a kernel symbol and return it in a text buffer. */
487 56 : static int __sprint_symbol(char *buffer, unsigned long address,
488 : int symbol_offset, int add_offset, int add_buildid)
489 : {
490 : char *modname;
491 : const unsigned char *buildid;
492 : const char *name;
493 : unsigned long offset, size;
494 : int len;
495 :
496 56 : address += symbol_offset;
497 56 : name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid,
498 : buffer);
499 56 : if (!name)
500 0 : return sprintf(buffer, "0x%lx", address - symbol_offset);
501 :
502 56 : if (name != buffer)
503 : strcpy(buffer, name);
504 56 : len = strlen(buffer);
505 56 : offset -= symbol_offset;
506 :
507 56 : if (add_offset)
508 56 : len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
509 :
510 56 : if (modname) {
511 0 : len += sprintf(buffer + len, " [%s", modname);
512 : #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
513 : if (add_buildid && buildid) {
514 : /* build ID should match length of sprintf */
515 : #if IS_ENABLED(CONFIG_MODULES)
516 : static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
517 : #endif
518 : len += sprintf(buffer + len, " %20phN", buildid);
519 : }
520 : #endif
521 0 : len += sprintf(buffer + len, "]");
522 : }
523 :
524 : return len;
525 : }
526 :
527 : /**
528 : * sprint_symbol - Look up a kernel symbol and return it in a text buffer
529 : * @buffer: buffer to be stored
530 : * @address: address to lookup
531 : *
532 : * This function looks up a kernel symbol with @address and stores its name,
533 : * offset, size and module name to @buffer if possible. If no symbol was found,
534 : * just saves its @address as is.
535 : *
536 : * This function returns the number of bytes stored in @buffer.
537 : */
538 56 : int sprint_symbol(char *buffer, unsigned long address)
539 : {
540 56 : return __sprint_symbol(buffer, address, 0, 1, 0);
541 : }
542 : EXPORT_SYMBOL_GPL(sprint_symbol);
543 :
544 : /**
545 : * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
546 : * @buffer: buffer to be stored
547 : * @address: address to lookup
548 : *
549 : * This function looks up a kernel symbol with @address and stores its name,
550 : * offset, size, module name and module build ID to @buffer if possible. If no
551 : * symbol was found, just saves its @address as is.
552 : *
553 : * This function returns the number of bytes stored in @buffer.
554 : */
555 0 : int sprint_symbol_build_id(char *buffer, unsigned long address)
556 : {
557 0 : return __sprint_symbol(buffer, address, 0, 1, 1);
558 : }
559 : EXPORT_SYMBOL_GPL(sprint_symbol_build_id);
560 :
561 : /**
562 : * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
563 : * @buffer: buffer to be stored
564 : * @address: address to lookup
565 : *
566 : * This function looks up a kernel symbol with @address and stores its name
567 : * and module name to @buffer if possible. If no symbol was found, just saves
568 : * its @address as is.
569 : *
570 : * This function returns the number of bytes stored in @buffer.
571 : */
572 0 : int sprint_symbol_no_offset(char *buffer, unsigned long address)
573 : {
574 0 : return __sprint_symbol(buffer, address, 0, 0, 0);
575 : }
576 : EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
577 :
578 : /**
579 : * sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
580 : * @buffer: buffer to be stored
581 : * @address: address to lookup
582 : *
583 : * This function is for stack backtrace and does the same thing as
584 : * sprint_symbol() but with modified/decreased @address. If there is a
585 : * tail-call to the function marked "noreturn", gcc optimized out code after
586 : * the call so that the stack-saved return address could point outside of the
587 : * caller. This function ensures that kallsyms will find the original caller
588 : * by decreasing @address.
589 : *
590 : * This function returns the number of bytes stored in @buffer.
591 : */
592 0 : int sprint_backtrace(char *buffer, unsigned long address)
593 : {
594 0 : return __sprint_symbol(buffer, address, -1, 1, 0);
595 : }
596 :
597 : /**
598 : * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
599 : * @buffer: buffer to be stored
600 : * @address: address to lookup
601 : *
602 : * This function is for stack backtrace and does the same thing as
603 : * sprint_symbol() but with modified/decreased @address. If there is a
604 : * tail-call to the function marked "noreturn", gcc optimized out code after
605 : * the call so that the stack-saved return address could point outside of the
606 : * caller. This function ensures that kallsyms will find the original caller
607 : * by decreasing @address. This function also appends the module build ID to
608 : * the @buffer if @address is within a kernel module.
609 : *
610 : * This function returns the number of bytes stored in @buffer.
611 : */
612 0 : int sprint_backtrace_build_id(char *buffer, unsigned long address)
613 : {
614 0 : return __sprint_symbol(buffer, address, -1, 1, 1);
615 : }
616 :
617 : /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
618 : struct kallsym_iter {
619 : loff_t pos;
620 : loff_t pos_mod_end;
621 : loff_t pos_ftrace_mod_end;
622 : loff_t pos_bpf_end;
623 : unsigned long value;
624 : unsigned int nameoff; /* If iterating in core kernel symbols. */
625 : char type;
626 : char name[KSYM_NAME_LEN];
627 : char module_name[MODULE_NAME_LEN];
628 : int exported;
629 : int show_value;
630 : };
631 :
632 : static int get_ksymbol_mod(struct kallsym_iter *iter)
633 : {
634 0 : int ret = module_get_kallsym(iter->pos - kallsyms_num_syms,
635 : &iter->value, &iter->type,
636 0 : iter->name, iter->module_name,
637 : &iter->exported);
638 : if (ret < 0) {
639 0 : iter->pos_mod_end = iter->pos;
640 : return 0;
641 : }
642 :
643 : return 1;
644 : }
645 :
646 : /*
647 : * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
648 : * purposes. In that case "__builtin__ftrace" is used as a module name, even
649 : * though "__builtin__ftrace" is not a module.
650 : */
651 : static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
652 : {
653 0 : int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
654 : &iter->value, &iter->type,
655 0 : iter->name, iter->module_name,
656 : &iter->exported);
657 : if (ret < 0) {
658 0 : iter->pos_ftrace_mod_end = iter->pos;
659 : return 0;
660 : }
661 :
662 : return 1;
663 : }
664 :
665 0 : static int get_ksymbol_bpf(struct kallsym_iter *iter)
666 : {
667 : int ret;
668 :
669 0 : strscpy(iter->module_name, "bpf", MODULE_NAME_LEN);
670 0 : iter->exported = 0;
671 0 : ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
672 : &iter->value, &iter->type,
673 0 : iter->name);
674 : if (ret < 0) {
675 0 : iter->pos_bpf_end = iter->pos;
676 : return 0;
677 : }
678 :
679 : return 1;
680 : }
681 :
682 : /*
683 : * This uses "__builtin__kprobes" as a module name for symbols for pages
684 : * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
685 : * module.
686 : */
687 0 : static int get_ksymbol_kprobe(struct kallsym_iter *iter)
688 : {
689 0 : strscpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
690 0 : iter->exported = 0;
691 0 : return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
692 : &iter->value, &iter->type,
693 0 : iter->name) < 0 ? 0 : 1;
694 : }
695 :
696 : /* Returns space to next name. */
697 0 : static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
698 : {
699 0 : unsigned off = iter->nameoff;
700 :
701 0 : iter->module_name[0] = '\0';
702 0 : iter->value = kallsyms_sym_address(iter->pos);
703 :
704 0 : iter->type = kallsyms_get_symbol_type(off);
705 :
706 0 : off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
707 :
708 0 : return off - iter->nameoff;
709 : }
710 :
711 0 : static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
712 : {
713 0 : iter->name[0] = '\0';
714 0 : iter->nameoff = get_symbol_offset(new_pos);
715 0 : iter->pos = new_pos;
716 0 : if (new_pos == 0) {
717 0 : iter->pos_mod_end = 0;
718 0 : iter->pos_ftrace_mod_end = 0;
719 0 : iter->pos_bpf_end = 0;
720 : }
721 0 : }
722 :
723 : /*
724 : * The end position (last + 1) of each additional kallsyms section is recorded
725 : * in iter->pos_..._end as each section is added, and so can be used to
726 : * determine which get_ksymbol_...() function to call next.
727 : */
728 0 : static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
729 : {
730 0 : iter->pos = pos;
731 :
732 0 : if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
733 0 : get_ksymbol_mod(iter))
734 : return 1;
735 :
736 0 : if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
737 0 : get_ksymbol_ftrace_mod(iter))
738 : return 1;
739 :
740 0 : if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
741 0 : get_ksymbol_bpf(iter))
742 : return 1;
743 :
744 0 : return get_ksymbol_kprobe(iter);
745 : }
746 :
747 : /* Returns false if pos at or past end of file. */
748 0 : static int update_iter(struct kallsym_iter *iter, loff_t pos)
749 : {
750 : /* Module symbols can be accessed randomly. */
751 0 : if (pos >= kallsyms_num_syms)
752 0 : return update_iter_mod(iter, pos);
753 :
754 : /* If we're not on the desired position, reset to new position. */
755 0 : if (pos != iter->pos)
756 0 : reset_iter(iter, pos);
757 :
758 0 : iter->nameoff += get_ksymbol_core(iter);
759 0 : iter->pos++;
760 :
761 0 : return 1;
762 : }
763 :
764 0 : static void *s_next(struct seq_file *m, void *p, loff_t *pos)
765 : {
766 0 : (*pos)++;
767 :
768 0 : if (!update_iter(m->private, *pos))
769 : return NULL;
770 0 : return p;
771 : }
772 :
773 0 : static void *s_start(struct seq_file *m, loff_t *pos)
774 : {
775 0 : if (!update_iter(m->private, *pos))
776 : return NULL;
777 0 : return m->private;
778 : }
779 :
780 0 : static void s_stop(struct seq_file *m, void *p)
781 : {
782 0 : }
783 :
784 0 : static int s_show(struct seq_file *m, void *p)
785 : {
786 : void *value;
787 0 : struct kallsym_iter *iter = m->private;
788 :
789 : /* Some debugging symbols have no name. Ignore them. */
790 0 : if (!iter->name[0])
791 : return 0;
792 :
793 0 : value = iter->show_value ? (void *)iter->value : NULL;
794 :
795 0 : if (iter->module_name[0]) {
796 : char type;
797 :
798 : /*
799 : * Label it "global" if it is exported,
800 : * "local" if not exported.
801 : */
802 0 : type = iter->exported ? toupper(iter->type) :
803 0 : tolower(iter->type);
804 0 : seq_printf(m, "%px %c %s\t[%s]\n", value,
805 0 : type, iter->name, iter->module_name);
806 : } else
807 0 : seq_printf(m, "%px %c %s\n", value,
808 0 : iter->type, iter->name);
809 : return 0;
810 : }
811 :
812 : static const struct seq_operations kallsyms_op = {
813 : .start = s_start,
814 : .next = s_next,
815 : .stop = s_stop,
816 : .show = s_show
817 : };
818 :
819 : #ifdef CONFIG_BPF_SYSCALL
820 :
821 : struct bpf_iter__ksym {
822 : __bpf_md_ptr(struct bpf_iter_meta *, meta);
823 : __bpf_md_ptr(struct kallsym_iter *, ksym);
824 : };
825 :
826 : static int ksym_prog_seq_show(struct seq_file *m, bool in_stop)
827 : {
828 : struct bpf_iter__ksym ctx;
829 : struct bpf_iter_meta meta;
830 : struct bpf_prog *prog;
831 :
832 : meta.seq = m;
833 : prog = bpf_iter_get_info(&meta, in_stop);
834 : if (!prog)
835 : return 0;
836 :
837 : ctx.meta = &meta;
838 : ctx.ksym = m ? m->private : NULL;
839 : return bpf_iter_run_prog(prog, &ctx);
840 : }
841 :
842 : static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p)
843 : {
844 : return ksym_prog_seq_show(m, false);
845 : }
846 :
847 : static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p)
848 : {
849 : if (!p)
850 : (void) ksym_prog_seq_show(m, true);
851 : else
852 : s_stop(m, p);
853 : }
854 :
855 : static const struct seq_operations bpf_iter_ksym_ops = {
856 : .start = s_start,
857 : .next = s_next,
858 : .stop = bpf_iter_ksym_seq_stop,
859 : .show = bpf_iter_ksym_seq_show,
860 : };
861 :
862 : static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux)
863 : {
864 : struct kallsym_iter *iter = priv_data;
865 :
866 : reset_iter(iter, 0);
867 :
868 : /* cache here as in kallsyms_open() case; use current process
869 : * credentials to tell BPF iterators if values should be shown.
870 : */
871 : iter->show_value = kallsyms_show_value(current_cred());
872 :
873 : return 0;
874 : }
875 :
876 : DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym)
877 :
878 : static const struct bpf_iter_seq_info ksym_iter_seq_info = {
879 : .seq_ops = &bpf_iter_ksym_ops,
880 : .init_seq_private = bpf_iter_ksym_init,
881 : .fini_seq_private = NULL,
882 : .seq_priv_size = sizeof(struct kallsym_iter),
883 : };
884 :
885 : static struct bpf_iter_reg ksym_iter_reg_info = {
886 : .target = "ksym",
887 : .feature = BPF_ITER_RESCHED,
888 : .ctx_arg_info_size = 1,
889 : .ctx_arg_info = {
890 : { offsetof(struct bpf_iter__ksym, ksym),
891 : PTR_TO_BTF_ID_OR_NULL },
892 : },
893 : .seq_info = &ksym_iter_seq_info,
894 : };
895 :
896 : BTF_ID_LIST(btf_ksym_iter_id)
897 : BTF_ID(struct, kallsym_iter)
898 :
899 : static int __init bpf_ksym_iter_register(void)
900 : {
901 : ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id;
902 : return bpf_iter_reg_target(&ksym_iter_reg_info);
903 : }
904 :
905 : late_initcall(bpf_ksym_iter_register);
906 :
907 : #endif /* CONFIG_BPF_SYSCALL */
908 :
909 0 : static int kallsyms_open(struct inode *inode, struct file *file)
910 : {
911 : /*
912 : * We keep iterator in m->private, since normal case is to
913 : * s_start from where we left off, so we avoid doing
914 : * using get_symbol_offset for every symbol.
915 : */
916 : struct kallsym_iter *iter;
917 0 : iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
918 0 : if (!iter)
919 : return -ENOMEM;
920 0 : reset_iter(iter, 0);
921 :
922 : /*
923 : * Instead of checking this on every s_show() call, cache
924 : * the result here at open time.
925 : */
926 0 : iter->show_value = kallsyms_show_value(file->f_cred);
927 0 : return 0;
928 : }
929 :
930 : #ifdef CONFIG_KGDB_KDB
931 : const char *kdb_walk_kallsyms(loff_t *pos)
932 : {
933 : static struct kallsym_iter kdb_walk_kallsyms_iter;
934 : if (*pos == 0) {
935 : memset(&kdb_walk_kallsyms_iter, 0,
936 : sizeof(kdb_walk_kallsyms_iter));
937 : reset_iter(&kdb_walk_kallsyms_iter, 0);
938 : }
939 : while (1) {
940 : if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
941 : return NULL;
942 : ++*pos;
943 : /* Some debugging symbols have no name. Ignore them. */
944 : if (kdb_walk_kallsyms_iter.name[0])
945 : return kdb_walk_kallsyms_iter.name;
946 : }
947 : }
948 : #endif /* CONFIG_KGDB_KDB */
949 :
950 : static const struct proc_ops kallsyms_proc_ops = {
951 : .proc_open = kallsyms_open,
952 : .proc_read = seq_read,
953 : .proc_lseek = seq_lseek,
954 : .proc_release = seq_release_private,
955 : };
956 :
957 1 : static int __init kallsyms_init(void)
958 : {
959 1 : proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
960 1 : return 0;
961 : }
962 : device_initcall(kallsyms_init);
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