4 * make pr_debug()/dev_dbg() calls runtime configurable based upon their
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.
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>
28 extern struct _ddebug __start___verbose[];
29 extern struct _ddebug __stop___verbose[];
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.
35 long long dynamic_debug_enabled;
36 EXPORT_SYMBOL_GPL(dynamic_debug_enabled);
37 long long dynamic_debug_enabled2;
38 EXPORT_SYMBOL_GPL(dynamic_debug_enabled2);
41 struct list_head link;
43 unsigned int num_ddebugs;
44 unsigned int num_enabled;
45 struct _ddebug *ddebugs;
53 unsigned int first_lineno, last_lineno;
57 struct ddebug_table *table;
61 static DEFINE_MUTEX(ddebug_lock);
62 static LIST_HEAD(ddebug_tables);
63 static int verbose = 0;
65 /* Return the last part of a pathname */
66 static inline const char *basename(const char *path)
68 const char *tail = strrchr(path, '/');
69 return tail ? tail+1 : path;
72 /* format a string into buf[] which describes the _ddebug's flags */
73 static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
79 if (dp->flags & _DPRINTK_FLAGS_PRINT)
89 * must be called with ddebug_lock held
92 static int disabled_hash(char hash, bool first_table)
94 struct ddebug_table *dt;
95 char table_hash_value;
97 list_for_each_entry(dt, &ddebug_tables, link) {
99 table_hash_value = dt->ddebugs->primary_hash;
101 table_hash_value = dt->ddebugs->secondary_hash;
102 if (dt->num_enabled && (hash == table_hash_value))
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
114 static void ddebug_change(const struct ddebug_query *query,
115 unsigned int flags, unsigned int mask)
118 struct ddebug_table *dt;
119 unsigned int newflags;
120 unsigned int nfound = 0;
123 /* search for matching ddebugs */
124 mutex_lock(&ddebug_lock);
125 list_for_each_entry(dt, &ddebug_tables, link) {
127 /* match against the module name */
128 if (query->module != NULL &&
129 strcmp(query->module, dt->mod_name))
132 for (i = 0 ; i < dt->num_ddebugs ; i++) {
133 struct _ddebug *dp = &dt->ddebugs[i];
135 /* match against the source filename */
136 if (query->filename != NULL &&
137 strcmp(query->filename, dp->filename) &&
138 strcmp(query->filename, basename(dp->filename)))
141 /* match against the function */
142 if (query->function != NULL &&
143 strcmp(query->function, dp->function))
146 /* match against the format */
147 if (query->format != NULL &&
148 strstr(dp->format, query->format) == NULL)
151 /* match against the line number range */
152 if (query->first_lineno &&
153 dp->lineno < query->first_lineno)
155 if (query->last_lineno &&
156 dp->lineno > query->last_lineno)
161 newflags = (dp->flags & mask) | flags;
162 if (newflags == dp->flags)
169 dp->flags = newflags;
171 dynamic_debug_enabled |=
172 (1LL << dp->primary_hash);
173 dynamic_debug_enabled2 |=
174 (1LL << dp->secondary_hash);
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);
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,
192 mutex_unlock(&ddebug_lock);
194 if (!nfound && verbose)
195 printk(KERN_INFO "ddebug: no matches for query\n");
199 * Wrapper around strsep() to collapse the multiple empty tokens
200 * that it returns when fed sequences of separator characters.
201 * Now, if we had strtok_r()...
203 static inline char *nearly_strtok_r(char **p, const char *sep)
207 while ((r = strsep(p, sep)) != NULL && *r == '\0')
213 * Split the buffer `buf' into space-separated words.
214 * Return the number of such words or <0 on error.
216 static int ddebug_tokenize(char *buf, char *words[], int maxwords)
220 while (nwords < maxwords &&
221 (words[nwords] = nearly_strtok_r(&buf, " \t\r\n")) != NULL)
224 return -EINVAL; /* ran out of words[] before bytes */
228 printk(KERN_INFO "%s: split into words:", __func__);
229 for (i = 0 ; i < nwords ; i++)
230 printk(" \"%s\"", words[i]);
238 * Parse a single line number. Note that the empty string ""
239 * is treated as a special case and converted to zero, which
240 * is later treated as a "don't care" value.
242 static inline int parse_lineno(const char *str, unsigned int *val)
250 *val = simple_strtoul(str, &end, 10);
251 return end == NULL || end == str || *end != '\0' ? -EINVAL : 0;
255 * Undo octal escaping in a string, inplace. This is useful to
256 * allow the user to express a query which matches a format
257 * containing embedded spaces.
259 #define isodigit(c) ((c) >= '0' && (c) <= '7')
260 static char *unescape(char *str)
271 } else if (in[1] == 't') {
275 } else if (in[1] == 'n') {
279 } else if (isodigit(in[1]) &&
282 *out++ = ((in[1] - '0')<<6) |
297 * Parse words[] as a ddebug query specification, which is a series
298 * of (keyword, value) pairs chosen from these possibilities:
300 * func <function-name>
301 * file <full-pathname>
302 * file <base-filename>
303 * module <module-name>
304 * format <escaped-string-to-find-in-format>
306 * line <first-lineno>-<last-lineno> // where either may be empty
308 static int ddebug_parse_query(char *words[], int nwords,
309 struct ddebug_query *query)
313 /* check we have an even number of words */
316 memset(query, 0, sizeof(*query));
318 for (i = 0 ; i < nwords ; i += 2) {
319 if (!strcmp(words[i], "func"))
320 query->function = words[i+1];
321 else if (!strcmp(words[i], "file"))
322 query->filename = words[i+1];
323 else if (!strcmp(words[i], "module"))
324 query->module = words[i+1];
325 else if (!strcmp(words[i], "format"))
326 query->format = unescape(words[i+1]);
327 else if (!strcmp(words[i], "line")) {
328 char *first = words[i+1];
329 char *last = strchr(first, '-');
332 if (parse_lineno(first, &query->first_lineno) < 0)
335 /* range <first>-<last> */
336 if (parse_lineno(last, &query->last_lineno) < 0)
339 query->last_lineno = query->first_lineno;
343 printk(KERN_ERR "%s: unknown keyword \"%s\"\n",
350 printk(KERN_INFO "%s: q->function=\"%s\" q->filename=\"%s\" "
351 "q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u\n",
352 __func__, query->function, query->filename,
353 query->module, query->format, query->first_lineno,
360 * Parse `str' as a flags specification, format [-+=][p]+.
361 * Sets up *maskp and *flagsp to be used when changing the
362 * flags fields of matched _ddebug's. Returns 0 on success
365 static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
381 printk(KERN_INFO "%s: op='%c'\n", __func__, op);
383 for ( ; *str ; ++str) {
386 flags |= _DPRINTK_FLAGS_PRINT;
395 printk(KERN_INFO "%s: flags=0x%x\n", __func__, flags);
397 /* calculate final *flagsp, *maskp according to mask and op */
413 printk(KERN_INFO "%s: *flagsp=0x%x *maskp=0x%x\n",
414 __func__, *flagsp, *maskp);
419 * File_ops->write method for <debugfs>/dynamic_debug/conrol. Gathers the
420 * command text from userspace, parses and executes it.
422 static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
423 size_t len, loff_t *offp)
425 unsigned int flags = 0, mask = 0;
426 struct ddebug_query query;
429 char *words[MAXWORDS];
434 /* we don't check *offp -- multiple writes() are allowed */
435 if (len > sizeof(tmpbuf)-1)
437 if (copy_from_user(tmpbuf, ubuf, len))
441 printk(KERN_INFO "%s: read %d bytes from userspace\n",
444 nwords = ddebug_tokenize(tmpbuf, words, MAXWORDS);
447 if (ddebug_parse_query(words, nwords-1, &query))
449 if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
452 /* actually go and implement the change */
453 ddebug_change(&query, flags, mask);
460 * Set the iterator to point to the first _ddebug object
461 * and return a pointer to that first object. Returns
462 * NULL if there are no _ddebugs at all.
464 static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
466 if (list_empty(&ddebug_tables)) {
471 iter->table = list_entry(ddebug_tables.next,
472 struct ddebug_table, link);
474 return &iter->table->ddebugs[iter->idx];
478 * Advance the iterator to point to the next _ddebug
479 * object from the one the iterator currently points at,
480 * and returns a pointer to the new _ddebug. Returns
481 * NULL if the iterator has seen all the _ddebugs.
483 static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
485 if (iter->table == NULL)
487 if (++iter->idx == iter->table->num_ddebugs) {
488 /* iterate to next table */
490 if (list_is_last(&iter->table->link, &ddebug_tables)) {
494 iter->table = list_entry(iter->table->link.next,
495 struct ddebug_table, link);
497 return &iter->table->ddebugs[iter->idx];
501 * Seq_ops start method. Called at the start of every
502 * read() call from userspace. Takes the ddebug_lock and
503 * seeks the seq_file's iterator to the given position.
505 static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
507 struct ddebug_iter *iter = m->private;
512 printk(KERN_INFO "%s: called m=%p *pos=%lld\n",
513 __func__, m, (unsigned long long)*pos);
515 mutex_lock(&ddebug_lock);
518 return SEQ_START_TOKEN;
521 dp = ddebug_iter_first(iter);
522 while (dp != NULL && --n > 0)
523 dp = ddebug_iter_next(iter);
528 * Seq_ops next method. Called several times within a read()
529 * call from userspace, with ddebug_lock held. Walks to the
530 * next _ddebug object with a special case for the header line.
532 static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
534 struct ddebug_iter *iter = m->private;
538 printk(KERN_INFO "%s: called m=%p p=%p *pos=%lld\n",
539 __func__, m, p, (unsigned long long)*pos);
541 if (p == SEQ_START_TOKEN)
542 dp = ddebug_iter_first(iter);
544 dp = ddebug_iter_next(iter);
550 * Seq_ops show method. Called several times within a read()
551 * call from userspace, with ddebug_lock held. Formats the
552 * current _ddebug as a single human-readable line, with a
553 * special case for the header line.
555 static int ddebug_proc_show(struct seq_file *m, void *p)
557 struct ddebug_iter *iter = m->private;
558 struct _ddebug *dp = p;
562 printk(KERN_INFO "%s: called m=%p p=%p\n",
565 if (p == SEQ_START_TOKEN) {
567 "# filename:lineno [module]function flags format\n");
571 seq_printf(m, "%s:%u [%s]%s %s \"",
572 dp->filename, dp->lineno,
573 iter->table->mod_name, dp->function,
574 ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
575 seq_escape(m, dp->format, "\t\r\n\"");
582 * Seq_ops stop method. Called at the end of each read()
583 * call from userspace. Drops ddebug_lock.
585 static void ddebug_proc_stop(struct seq_file *m, void *p)
588 printk(KERN_INFO "%s: called m=%p p=%p\n",
590 mutex_unlock(&ddebug_lock);
593 static const struct seq_operations ddebug_proc_seqops = {
594 .start = ddebug_proc_start,
595 .next = ddebug_proc_next,
596 .show = ddebug_proc_show,
597 .stop = ddebug_proc_stop
601 * File_ops->open method for <debugfs>/dynamic_debug/control. Does the seq_file
602 * setup dance, and also creates an iterator to walk the _ddebugs.
603 * Note that we create a seq_file always, even for O_WRONLY files
604 * where it's not needed, as doing so simplifies the ->release method.
606 static int ddebug_proc_open(struct inode *inode, struct file *file)
608 struct ddebug_iter *iter;
612 printk(KERN_INFO "%s: called\n", __func__);
614 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
618 err = seq_open(file, &ddebug_proc_seqops);
623 ((struct seq_file *) file->private_data)->private = iter;
627 static const struct file_operations ddebug_proc_fops = {
628 .owner = THIS_MODULE,
629 .open = ddebug_proc_open,
632 .release = seq_release_private,
633 .write = ddebug_proc_write
637 * Allocate a new ddebug_table for the given module
638 * and add it to the global list.
640 int ddebug_add_module(struct _ddebug *tab, unsigned int n,
643 struct ddebug_table *dt;
646 dt = kzalloc(sizeof(*dt), GFP_KERNEL);
649 new_name = kstrdup(name, GFP_KERNEL);
650 if (new_name == NULL) {
654 dt->mod_name = new_name;
659 mutex_lock(&ddebug_lock);
660 list_add_tail(&dt->link, &ddebug_tables);
661 mutex_unlock(&ddebug_lock);
664 printk(KERN_INFO "%u debug prints in module %s\n",
668 EXPORT_SYMBOL_GPL(ddebug_add_module);
670 static void ddebug_table_free(struct ddebug_table *dt)
672 list_del_init(&dt->link);
678 * Called in response to a module being unloaded. Removes
679 * any ddebug_table's which point at the module.
681 int ddebug_remove_module(char *mod_name)
683 struct ddebug_table *dt, *nextdt;
687 printk(KERN_INFO "%s: removing module \"%s\"\n",
690 mutex_lock(&ddebug_lock);
691 list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
692 if (!strcmp(dt->mod_name, mod_name)) {
693 ddebug_table_free(dt);
697 mutex_unlock(&ddebug_lock);
700 EXPORT_SYMBOL_GPL(ddebug_remove_module);
702 static void ddebug_remove_all_tables(void)
704 mutex_lock(&ddebug_lock);
705 while (!list_empty(&ddebug_tables)) {
706 struct ddebug_table *dt = list_entry(ddebug_tables.next,
709 ddebug_table_free(dt);
711 mutex_unlock(&ddebug_lock);
714 static int __init dynamic_debug_init(void)
716 struct dentry *dir, *file;
717 struct _ddebug *iter, *iter_start;
718 const char *modname = NULL;
722 dir = debugfs_create_dir("dynamic_debug", NULL);
725 file = debugfs_create_file("control", 0644, dir, NULL,
731 if (__start___verbose != __stop___verbose) {
732 iter = __start___verbose;
733 modname = iter->modname;
735 for (; iter < __stop___verbose; iter++) {
736 if (strcmp(modname, iter->modname)) {
737 ret = ddebug_add_module(iter_start, n, modname);
741 modname = iter->modname;
746 ret = ddebug_add_module(iter_start, n, modname);
750 ddebug_remove_all_tables();
752 debugfs_remove(file);
756 module_init(dynamic_debug_init);