blob: e22c148e4b7fff7605e605689561df66d018c6fa [file] [log] [blame]
Jason Barone9d376f2009-02-05 11:51:38 -05001/*
2 * lib/dynamic_debug.c
3 *
4 * make pr_debug()/dev_dbg() calls runtime configurable based upon their
5 * source module.
6 *
7 * Copyright (C) 2008 Jason Baron <jbaron@redhat.com>
8 * By Greg Banks <gnb@melbourne.sgi.com>
9 * Copyright (c) 2008 Silicon Graphics Inc. All Rights Reserved.
10 */
11
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/moduleparam.h>
15#include <linux/kallsyms.h>
16#include <linux/version.h>
17#include <linux/types.h>
18#include <linux/mutex.h>
19#include <linux/proc_fs.h>
20#include <linux/seq_file.h>
21#include <linux/list.h>
22#include <linux/sysctl.h>
23#include <linux/ctype.h>
24#include <linux/uaccess.h>
25#include <linux/dynamic_debug.h>
26#include <linux/debugfs.h>
27
28extern struct _ddebug __start___verbose[];
29extern struct _ddebug __stop___verbose[];
30
31/* dynamic_debug_enabled, and dynamic_debug_enabled2 are bitmasks in which
32 * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
33 * use independent hash functions, to reduce the chance of false positives.
34 */
35long long dynamic_debug_enabled;
36EXPORT_SYMBOL_GPL(dynamic_debug_enabled);
37long long dynamic_debug_enabled2;
38EXPORT_SYMBOL_GPL(dynamic_debug_enabled2);
39
40struct ddebug_table {
41 struct list_head link;
42 char *mod_name;
43 unsigned int num_ddebugs;
44 unsigned int num_enabled;
45 struct _ddebug *ddebugs;
46};
47
48struct ddebug_query {
49 const char *filename;
50 const char *module;
51 const char *function;
52 const char *format;
53 unsigned int first_lineno, last_lineno;
54};
55
56struct ddebug_iter {
57 struct ddebug_table *table;
58 unsigned int idx;
59};
60
61static DEFINE_MUTEX(ddebug_lock);
62static LIST_HEAD(ddebug_tables);
63static int verbose = 0;
64
65/* Return the last part of a pathname */
66static inline const char *basename(const char *path)
67{
68 const char *tail = strrchr(path, '/');
69 return tail ? tail+1 : path;
70}
71
72/* format a string into buf[] which describes the _ddebug's flags */
73static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
74 size_t maxlen)
75{
76 char *p = buf;
77
78 BUG_ON(maxlen < 4);
79 if (dp->flags & _DPRINTK_FLAGS_PRINT)
80 *p++ = 'p';
81 if (p == buf)
82 *p++ = '-';
83 *p = '\0';
84
85 return buf;
86}
87
88/*
89 * must be called with ddebug_lock held
90 */
91
92static int disabled_hash(char hash, bool first_table)
93{
94 struct ddebug_table *dt;
95 char table_hash_value;
96
97 list_for_each_entry(dt, &ddebug_tables, link) {
98 if (first_table)
99 table_hash_value = dt->ddebugs->primary_hash;
100 else
101 table_hash_value = dt->ddebugs->secondary_hash;
102 if (dt->num_enabled && (hash == table_hash_value))
103 return 0;
104 }
105 return 1;
106}
107
108/*
109 * Search the tables for _ddebug's which match the given
110 * `query' and apply the `flags' and `mask' to them. Tells
111 * the user which ddebug's were changed, or whether none
112 * were matched.
113 */
114static void ddebug_change(const struct ddebug_query *query,
115 unsigned int flags, unsigned int mask)
116{
117 int i;
118 struct ddebug_table *dt;
119 unsigned int newflags;
120 unsigned int nfound = 0;
121 char flagbuf[8];
122
123 /* search for matching ddebugs */
124 mutex_lock(&ddebug_lock);
125 list_for_each_entry(dt, &ddebug_tables, link) {
126
127 /* match against the module name */
128 if (query->module != NULL &&
129 strcmp(query->module, dt->mod_name))
130 continue;
131
132 for (i = 0 ; i < dt->num_ddebugs ; i++) {
133 struct _ddebug *dp = &dt->ddebugs[i];
134
135 /* match against the source filename */
136 if (query->filename != NULL &&
137 strcmp(query->filename, dp->filename) &&
138 strcmp(query->filename, basename(dp->filename)))
139 continue;
140
141 /* match against the function */
142 if (query->function != NULL &&
143 strcmp(query->function, dp->function))
144 continue;
145
146 /* match against the format */
147 if (query->format != NULL &&
148 strstr(dp->format, query->format) == NULL)
149 continue;
150
151 /* match against the line number range */
152 if (query->first_lineno &&
153 dp->lineno < query->first_lineno)
154 continue;
155 if (query->last_lineno &&
156 dp->lineno > query->last_lineno)
157 continue;
158
159 nfound++;
160
161 newflags = (dp->flags & mask) | flags;
162 if (newflags == dp->flags)
163 continue;
164
165 if (!newflags)
166 dt->num_enabled--;
Roel Kluin4df7b3e2009-07-15 20:29:07 +0200167 else if (!dp->flags)
Jason Barone9d376f2009-02-05 11:51:38 -0500168 dt->num_enabled++;
169 dp->flags = newflags;
170 if (newflags) {
171 dynamic_debug_enabled |=
172 (1LL << dp->primary_hash);
173 dynamic_debug_enabled2 |=
174 (1LL << dp->secondary_hash);
175 } else {
176 if (disabled_hash(dp->primary_hash, true))
177 dynamic_debug_enabled &=
178 ~(1LL << dp->primary_hash);
179 if (disabled_hash(dp->secondary_hash, false))
180 dynamic_debug_enabled2 &=
181 ~(1LL << dp->secondary_hash);
182 }
183 if (verbose)
184 printk(KERN_INFO
185 "ddebug: changed %s:%d [%s]%s %s\n",
186 dp->filename, dp->lineno,
187 dt->mod_name, dp->function,
188 ddebug_describe_flags(dp, flagbuf,
189 sizeof(flagbuf)));
190 }
191 }
192 mutex_unlock(&ddebug_lock);
193
194 if (!nfound && verbose)
195 printk(KERN_INFO "ddebug: no matches for query\n");
196}
197
198/*
Jason Barone9d376f2009-02-05 11:51:38 -0500199 * Split the buffer `buf' into space-separated words.
Greg Banks9898abb2009-02-06 12:54:26 +1100200 * Handles simple " and ' quoting, i.e. without nested,
201 * embedded or escaped \". Return the number of words
202 * or <0 on error.
Jason Barone9d376f2009-02-05 11:51:38 -0500203 */
204static int ddebug_tokenize(char *buf, char *words[], int maxwords)
205{
206 int nwords = 0;
207
Greg Banks9898abb2009-02-06 12:54:26 +1100208 while (*buf) {
209 char *end;
210
211 /* Skip leading whitespace */
212 while (*buf && isspace(*buf))
213 buf++;
214 if (!*buf)
215 break; /* oh, it was trailing whitespace */
216
217 /* Run `end' over a word, either whitespace separated or quoted */
218 if (*buf == '"' || *buf == '\'') {
219 int quote = *buf++;
220 for (end = buf ; *end && *end != quote ; end++)
221 ;
222 if (!*end)
223 return -EINVAL; /* unclosed quote */
224 } else {
225 for (end = buf ; *end && !isspace(*end) ; end++)
226 ;
227 BUG_ON(end == buf);
228 }
229 /* Here `buf' is the start of the word, `end' is one past the end */
230
231 if (nwords == maxwords)
232 return -EINVAL; /* ran out of words[] before bytes */
233 if (*end)
234 *end++ = '\0'; /* terminate the word */
235 words[nwords++] = buf;
236 buf = end;
237 }
Jason Barone9d376f2009-02-05 11:51:38 -0500238
239 if (verbose) {
240 int i;
241 printk(KERN_INFO "%s: split into words:", __func__);
242 for (i = 0 ; i < nwords ; i++)
243 printk(" \"%s\"", words[i]);
244 printk("\n");
245 }
246
247 return nwords;
248}
249
250/*
251 * Parse a single line number. Note that the empty string ""
252 * is treated as a special case and converted to zero, which
253 * is later treated as a "don't care" value.
254 */
255static inline int parse_lineno(const char *str, unsigned int *val)
256{
257 char *end = NULL;
258 BUG_ON(str == NULL);
259 if (*str == '\0') {
260 *val = 0;
261 return 0;
262 }
263 *val = simple_strtoul(str, &end, 10);
264 return end == NULL || end == str || *end != '\0' ? -EINVAL : 0;
265}
266
267/*
268 * Undo octal escaping in a string, inplace. This is useful to
269 * allow the user to express a query which matches a format
270 * containing embedded spaces.
271 */
272#define isodigit(c) ((c) >= '0' && (c) <= '7')
273static char *unescape(char *str)
274{
275 char *in = str;
276 char *out = str;
277
278 while (*in) {
279 if (*in == '\\') {
280 if (in[1] == '\\') {
281 *out++ = '\\';
282 in += 2;
283 continue;
284 } else if (in[1] == 't') {
285 *out++ = '\t';
286 in += 2;
287 continue;
288 } else if (in[1] == 'n') {
289 *out++ = '\n';
290 in += 2;
291 continue;
292 } else if (isodigit(in[1]) &&
293 isodigit(in[2]) &&
294 isodigit(in[3])) {
295 *out++ = ((in[1] - '0')<<6) |
296 ((in[2] - '0')<<3) |
297 (in[3] - '0');
298 in += 4;
299 continue;
300 }
301 }
302 *out++ = *in++;
303 }
304 *out = '\0';
305
306 return str;
307}
308
309/*
310 * Parse words[] as a ddebug query specification, which is a series
311 * of (keyword, value) pairs chosen from these possibilities:
312 *
313 * func <function-name>
314 * file <full-pathname>
315 * file <base-filename>
316 * module <module-name>
317 * format <escaped-string-to-find-in-format>
318 * line <lineno>
319 * line <first-lineno>-<last-lineno> // where either may be empty
320 */
321static int ddebug_parse_query(char *words[], int nwords,
322 struct ddebug_query *query)
323{
324 unsigned int i;
325
326 /* check we have an even number of words */
327 if (nwords % 2 != 0)
328 return -EINVAL;
329 memset(query, 0, sizeof(*query));
330
331 for (i = 0 ; i < nwords ; i += 2) {
332 if (!strcmp(words[i], "func"))
333 query->function = words[i+1];
334 else if (!strcmp(words[i], "file"))
335 query->filename = words[i+1];
336 else if (!strcmp(words[i], "module"))
337 query->module = words[i+1];
338 else if (!strcmp(words[i], "format"))
339 query->format = unescape(words[i+1]);
340 else if (!strcmp(words[i], "line")) {
341 char *first = words[i+1];
342 char *last = strchr(first, '-');
343 if (last)
344 *last++ = '\0';
345 if (parse_lineno(first, &query->first_lineno) < 0)
346 return -EINVAL;
347 if (last != NULL) {
348 /* range <first>-<last> */
349 if (parse_lineno(last, &query->last_lineno) < 0)
350 return -EINVAL;
351 } else {
352 query->last_lineno = query->first_lineno;
353 }
354 } else {
355 if (verbose)
356 printk(KERN_ERR "%s: unknown keyword \"%s\"\n",
357 __func__, words[i]);
358 return -EINVAL;
359 }
360 }
361
362 if (verbose)
363 printk(KERN_INFO "%s: q->function=\"%s\" q->filename=\"%s\" "
364 "q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u\n",
365 __func__, query->function, query->filename,
366 query->module, query->format, query->first_lineno,
367 query->last_lineno);
368
369 return 0;
370}
371
372/*
373 * Parse `str' as a flags specification, format [-+=][p]+.
374 * Sets up *maskp and *flagsp to be used when changing the
375 * flags fields of matched _ddebug's. Returns 0 on success
376 * or <0 on error.
377 */
378static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
379 unsigned int *maskp)
380{
381 unsigned flags = 0;
382 int op = '=';
383
384 switch (*str) {
385 case '+':
386 case '-':
387 case '=':
388 op = *str++;
389 break;
390 default:
391 return -EINVAL;
392 }
393 if (verbose)
394 printk(KERN_INFO "%s: op='%c'\n", __func__, op);
395
396 for ( ; *str ; ++str) {
397 switch (*str) {
398 case 'p':
399 flags |= _DPRINTK_FLAGS_PRINT;
400 break;
401 default:
402 return -EINVAL;
403 }
404 }
405 if (flags == 0)
406 return -EINVAL;
407 if (verbose)
408 printk(KERN_INFO "%s: flags=0x%x\n", __func__, flags);
409
410 /* calculate final *flagsp, *maskp according to mask and op */
411 switch (op) {
412 case '=':
413 *maskp = 0;
414 *flagsp = flags;
415 break;
416 case '+':
417 *maskp = ~0U;
418 *flagsp = flags;
419 break;
420 case '-':
421 *maskp = ~flags;
422 *flagsp = 0;
423 break;
424 }
425 if (verbose)
426 printk(KERN_INFO "%s: *flagsp=0x%x *maskp=0x%x\n",
427 __func__, *flagsp, *maskp);
428 return 0;
429}
430
431/*
432 * File_ops->write method for <debugfs>/dynamic_debug/conrol. Gathers the
433 * command text from userspace, parses and executes it.
434 */
435static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
436 size_t len, loff_t *offp)
437{
438 unsigned int flags = 0, mask = 0;
439 struct ddebug_query query;
440#define MAXWORDS 9
441 int nwords;
442 char *words[MAXWORDS];
443 char tmpbuf[256];
444
445 if (len == 0)
446 return 0;
447 /* we don't check *offp -- multiple writes() are allowed */
448 if (len > sizeof(tmpbuf)-1)
449 return -E2BIG;
450 if (copy_from_user(tmpbuf, ubuf, len))
451 return -EFAULT;
452 tmpbuf[len] = '\0';
453 if (verbose)
454 printk(KERN_INFO "%s: read %d bytes from userspace\n",
455 __func__, (int)len);
456
457 nwords = ddebug_tokenize(tmpbuf, words, MAXWORDS);
458 if (nwords < 0)
459 return -EINVAL;
460 if (ddebug_parse_query(words, nwords-1, &query))
461 return -EINVAL;
462 if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
463 return -EINVAL;
464
465 /* actually go and implement the change */
466 ddebug_change(&query, flags, mask);
467
468 *offp += len;
469 return len;
470}
471
472/*
473 * Set the iterator to point to the first _ddebug object
474 * and return a pointer to that first object. Returns
475 * NULL if there are no _ddebugs at all.
476 */
477static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
478{
479 if (list_empty(&ddebug_tables)) {
480 iter->table = NULL;
481 iter->idx = 0;
482 return NULL;
483 }
484 iter->table = list_entry(ddebug_tables.next,
485 struct ddebug_table, link);
486 iter->idx = 0;
487 return &iter->table->ddebugs[iter->idx];
488}
489
490/*
491 * Advance the iterator to point to the next _ddebug
492 * object from the one the iterator currently points at,
493 * and returns a pointer to the new _ddebug. Returns
494 * NULL if the iterator has seen all the _ddebugs.
495 */
496static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
497{
498 if (iter->table == NULL)
499 return NULL;
500 if (++iter->idx == iter->table->num_ddebugs) {
501 /* iterate to next table */
502 iter->idx = 0;
503 if (list_is_last(&iter->table->link, &ddebug_tables)) {
504 iter->table = NULL;
505 return NULL;
506 }
507 iter->table = list_entry(iter->table->link.next,
508 struct ddebug_table, link);
509 }
510 return &iter->table->ddebugs[iter->idx];
511}
512
513/*
514 * Seq_ops start method. Called at the start of every
515 * read() call from userspace. Takes the ddebug_lock and
516 * seeks the seq_file's iterator to the given position.
517 */
518static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
519{
520 struct ddebug_iter *iter = m->private;
521 struct _ddebug *dp;
522 int n = *pos;
523
524 if (verbose)
525 printk(KERN_INFO "%s: called m=%p *pos=%lld\n",
526 __func__, m, (unsigned long long)*pos);
527
528 mutex_lock(&ddebug_lock);
529
530 if (!n)
531 return SEQ_START_TOKEN;
532 if (n < 0)
533 return NULL;
534 dp = ddebug_iter_first(iter);
535 while (dp != NULL && --n > 0)
536 dp = ddebug_iter_next(iter);
537 return dp;
538}
539
540/*
541 * Seq_ops next method. Called several times within a read()
542 * call from userspace, with ddebug_lock held. Walks to the
543 * next _ddebug object with a special case for the header line.
544 */
545static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
546{
547 struct ddebug_iter *iter = m->private;
548 struct _ddebug *dp;
549
550 if (verbose)
551 printk(KERN_INFO "%s: called m=%p p=%p *pos=%lld\n",
552 __func__, m, p, (unsigned long long)*pos);
553
554 if (p == SEQ_START_TOKEN)
555 dp = ddebug_iter_first(iter);
556 else
557 dp = ddebug_iter_next(iter);
558 ++*pos;
559 return dp;
560}
561
562/*
563 * Seq_ops show method. Called several times within a read()
564 * call from userspace, with ddebug_lock held. Formats the
565 * current _ddebug as a single human-readable line, with a
566 * special case for the header line.
567 */
568static int ddebug_proc_show(struct seq_file *m, void *p)
569{
570 struct ddebug_iter *iter = m->private;
571 struct _ddebug *dp = p;
572 char flagsbuf[8];
573
574 if (verbose)
575 printk(KERN_INFO "%s: called m=%p p=%p\n",
576 __func__, m, p);
577
578 if (p == SEQ_START_TOKEN) {
579 seq_puts(m,
580 "# filename:lineno [module]function flags format\n");
581 return 0;
582 }
583
584 seq_printf(m, "%s:%u [%s]%s %s \"",
585 dp->filename, dp->lineno,
586 iter->table->mod_name, dp->function,
587 ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
588 seq_escape(m, dp->format, "\t\r\n\"");
589 seq_puts(m, "\"\n");
590
591 return 0;
592}
593
594/*
595 * Seq_ops stop method. Called at the end of each read()
596 * call from userspace. Drops ddebug_lock.
597 */
598static void ddebug_proc_stop(struct seq_file *m, void *p)
599{
600 if (verbose)
601 printk(KERN_INFO "%s: called m=%p p=%p\n",
602 __func__, m, p);
603 mutex_unlock(&ddebug_lock);
604}
605
606static const struct seq_operations ddebug_proc_seqops = {
607 .start = ddebug_proc_start,
608 .next = ddebug_proc_next,
609 .show = ddebug_proc_show,
610 .stop = ddebug_proc_stop
611};
612
613/*
614 * File_ops->open method for <debugfs>/dynamic_debug/control. Does the seq_file
615 * setup dance, and also creates an iterator to walk the _ddebugs.
616 * Note that we create a seq_file always, even for O_WRONLY files
617 * where it's not needed, as doing so simplifies the ->release method.
618 */
619static int ddebug_proc_open(struct inode *inode, struct file *file)
620{
621 struct ddebug_iter *iter;
622 int err;
623
624 if (verbose)
625 printk(KERN_INFO "%s: called\n", __func__);
626
627 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
628 if (iter == NULL)
629 return -ENOMEM;
630
631 err = seq_open(file, &ddebug_proc_seqops);
632 if (err) {
633 kfree(iter);
634 return err;
635 }
636 ((struct seq_file *) file->private_data)->private = iter;
637 return 0;
638}
639
640static const struct file_operations ddebug_proc_fops = {
641 .owner = THIS_MODULE,
642 .open = ddebug_proc_open,
643 .read = seq_read,
644 .llseek = seq_lseek,
645 .release = seq_release_private,
646 .write = ddebug_proc_write
647};
648
649/*
650 * Allocate a new ddebug_table for the given module
651 * and add it to the global list.
652 */
653int ddebug_add_module(struct _ddebug *tab, unsigned int n,
654 const char *name)
655{
656 struct ddebug_table *dt;
657 char *new_name;
658
659 dt = kzalloc(sizeof(*dt), GFP_KERNEL);
660 if (dt == NULL)
661 return -ENOMEM;
662 new_name = kstrdup(name, GFP_KERNEL);
663 if (new_name == NULL) {
664 kfree(dt);
665 return -ENOMEM;
666 }
667 dt->mod_name = new_name;
668 dt->num_ddebugs = n;
669 dt->num_enabled = 0;
670 dt->ddebugs = tab;
671
672 mutex_lock(&ddebug_lock);
673 list_add_tail(&dt->link, &ddebug_tables);
674 mutex_unlock(&ddebug_lock);
675
676 if (verbose)
677 printk(KERN_INFO "%u debug prints in module %s\n",
678 n, dt->mod_name);
679 return 0;
680}
681EXPORT_SYMBOL_GPL(ddebug_add_module);
682
683static void ddebug_table_free(struct ddebug_table *dt)
684{
685 list_del_init(&dt->link);
686 kfree(dt->mod_name);
687 kfree(dt);
688}
689
690/*
691 * Called in response to a module being unloaded. Removes
692 * any ddebug_table's which point at the module.
693 */
694int ddebug_remove_module(char *mod_name)
695{
696 struct ddebug_table *dt, *nextdt;
697 int ret = -ENOENT;
698
699 if (verbose)
700 printk(KERN_INFO "%s: removing module \"%s\"\n",
701 __func__, mod_name);
702
703 mutex_lock(&ddebug_lock);
704 list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
705 if (!strcmp(dt->mod_name, mod_name)) {
706 ddebug_table_free(dt);
707 ret = 0;
708 }
709 }
710 mutex_unlock(&ddebug_lock);
711 return ret;
712}
713EXPORT_SYMBOL_GPL(ddebug_remove_module);
714
715static void ddebug_remove_all_tables(void)
716{
717 mutex_lock(&ddebug_lock);
718 while (!list_empty(&ddebug_tables)) {
719 struct ddebug_table *dt = list_entry(ddebug_tables.next,
720 struct ddebug_table,
721 link);
722 ddebug_table_free(dt);
723 }
724 mutex_unlock(&ddebug_lock);
725}
726
727static int __init dynamic_debug_init(void)
728{
729 struct dentry *dir, *file;
730 struct _ddebug *iter, *iter_start;
731 const char *modname = NULL;
732 int ret = 0;
733 int n = 0;
734
735 dir = debugfs_create_dir("dynamic_debug", NULL);
736 if (!dir)
737 return -ENOMEM;
738 file = debugfs_create_file("control", 0644, dir, NULL,
739 &ddebug_proc_fops);
740 if (!file) {
741 debugfs_remove(dir);
742 return -ENOMEM;
743 }
744 if (__start___verbose != __stop___verbose) {
745 iter = __start___verbose;
746 modname = iter->modname;
747 iter_start = iter;
748 for (; iter < __stop___verbose; iter++) {
749 if (strcmp(modname, iter->modname)) {
750 ret = ddebug_add_module(iter_start, n, modname);
751 if (ret)
752 goto out_free;
753 n = 0;
754 modname = iter->modname;
755 iter_start = iter;
756 }
757 n++;
758 }
759 ret = ddebug_add_module(iter_start, n, modname);
760 }
761out_free:
762 if (ret) {
763 ddebug_remove_all_tables();
764 debugfs_remove(dir);
765 debugfs_remove(file);
766 }
767 return 0;
768}
769module_init(dynamic_debug_init);