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TOMOYO Linux Cross Reference
Linux/lib/dma-debug.c

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  1 /*
  2  * Copyright (C) 2008 Advanced Micro Devices, Inc.
  3  *
  4  * Author: Joerg Roedel <joerg.roedel@amd.com>
  5  *
  6  * This program is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 as published
  8  * by the Free Software Foundation.
  9  *
 10  * This program is distributed in the hope that it will be useful,
 11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13  * GNU General Public License for more details.
 14  *
 15  * You should have received a copy of the GNU General Public License
 16  * along with this program; if not, write to the Free Software
 17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 18  */
 19 
 20 #include <linux/scatterlist.h>
 21 #include <linux/dma-mapping.h>
 22 #include <linux/stacktrace.h>
 23 #include <linux/dma-debug.h>
 24 #include <linux/spinlock.h>
 25 #include <linux/debugfs.h>
 26 #include <linux/uaccess.h>
 27 #include <linux/device.h>
 28 #include <linux/types.h>
 29 #include <linux/sched.h>
 30 #include <linux/ctype.h>
 31 #include <linux/list.h>
 32 #include <linux/slab.h>
 33 
 34 #include <asm/sections.h>
 35 
 36 #define HASH_SIZE       1024ULL
 37 #define HASH_FN_SHIFT   13
 38 #define HASH_FN_MASK    (HASH_SIZE - 1)
 39 
 40 enum {
 41         dma_debug_single,
 42         dma_debug_page,
 43         dma_debug_sg,
 44         dma_debug_coherent,
 45 };
 46 
 47 #define DMA_DEBUG_STACKTRACE_ENTRIES 5
 48 
 49 struct dma_debug_entry {
 50         struct list_head list;
 51         struct device    *dev;
 52         int              type;
 53         phys_addr_t      paddr;
 54         u64              dev_addr;
 55         u64              size;
 56         int              direction;
 57         int              sg_call_ents;
 58         int              sg_mapped_ents;
 59 #ifdef CONFIG_STACKTRACE
 60         struct           stack_trace stacktrace;
 61         unsigned long    st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
 62 #endif
 63 };
 64 
 65 struct hash_bucket {
 66         struct list_head list;
 67         spinlock_t lock;
 68 } ____cacheline_aligned_in_smp;
 69 
 70 /* Hash list to save the allocated dma addresses */
 71 static struct hash_bucket dma_entry_hash[HASH_SIZE];
 72 /* List of pre-allocated dma_debug_entry's */
 73 static LIST_HEAD(free_entries);
 74 /* Lock for the list above */
 75 static DEFINE_SPINLOCK(free_entries_lock);
 76 
 77 /* Global disable flag - will be set in case of an error */
 78 static bool global_disable __read_mostly;
 79 
 80 /* Global error count */
 81 static u32 error_count;
 82 
 83 /* Global error show enable*/
 84 static u32 show_all_errors __read_mostly;
 85 /* Number of errors to show */
 86 static u32 show_num_errors = 1;
 87 
 88 static u32 num_free_entries;
 89 static u32 min_free_entries;
 90 static u32 nr_total_entries;
 91 
 92 /* number of preallocated entries requested by kernel cmdline */
 93 static u32 req_entries;
 94 
 95 /* debugfs dentry's for the stuff above */
 96 static struct dentry *dma_debug_dent        __read_mostly;
 97 static struct dentry *global_disable_dent   __read_mostly;
 98 static struct dentry *error_count_dent      __read_mostly;
 99 static struct dentry *show_all_errors_dent  __read_mostly;
100 static struct dentry *show_num_errors_dent  __read_mostly;
101 static struct dentry *num_free_entries_dent __read_mostly;
102 static struct dentry *min_free_entries_dent __read_mostly;
103 static struct dentry *filter_dent           __read_mostly;
104 
105 /* per-driver filter related state */
106 
107 #define NAME_MAX_LEN    64
108 
109 static char                  current_driver_name[NAME_MAX_LEN] __read_mostly;
110 static struct device_driver *current_driver                    __read_mostly;
111 
112 static DEFINE_RWLOCK(driver_name_lock);
113 
114 static const char *type2name[4] = { "single", "page",
115                                     "scather-gather", "coherent" };
116 
117 static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
118                                    "DMA_FROM_DEVICE", "DMA_NONE" };
119 
120 /* little merge helper - remove it after the merge window */
121 #ifndef BUS_NOTIFY_UNBOUND_DRIVER
122 #define BUS_NOTIFY_UNBOUND_DRIVER 0x0005
123 #endif
124 
125 /*
126  * The access to some variables in this macro is racy. We can't use atomic_t
127  * here because all these variables are exported to debugfs. Some of them even
128  * writeable. This is also the reason why a lock won't help much. But anyway,
129  * the races are no big deal. Here is why:
130  *
131  *   error_count: the addition is racy, but the worst thing that can happen is
132  *                that we don't count some errors
133  *   show_num_errors: the subtraction is racy. Also no big deal because in
134  *                    worst case this will result in one warning more in the
135  *                    system log than the user configured. This variable is
136  *                    writeable via debugfs.
137  */
138 static inline void dump_entry_trace(struct dma_debug_entry *entry)
139 {
140 #ifdef CONFIG_STACKTRACE
141         if (entry) {
142                 pr_warning("Mapped at:\n");
143                 print_stack_trace(&entry->stacktrace, 0);
144         }
145 #endif
146 }
147 
148 static bool driver_filter(struct device *dev)
149 {
150         struct device_driver *drv;
151         unsigned long flags;
152         bool ret;
153 
154         /* driver filter off */
155         if (likely(!current_driver_name[0]))
156                 return true;
157 
158         /* driver filter on and initialized */
159         if (current_driver && dev && dev->driver == current_driver)
160                 return true;
161 
162         /* driver filter on, but we can't filter on a NULL device... */
163         if (!dev)
164                 return false;
165 
166         if (current_driver || !current_driver_name[0])
167                 return false;
168 
169         /* driver filter on but not yet initialized */
170         drv = get_driver(dev->driver);
171         if (!drv)
172                 return false;
173 
174         /* lock to protect against change of current_driver_name */
175         read_lock_irqsave(&driver_name_lock, flags);
176 
177         ret = false;
178         if (drv->name &&
179             strncmp(current_driver_name, drv->name, NAME_MAX_LEN - 1) == 0) {
180                 current_driver = drv;
181                 ret = true;
182         }
183 
184         read_unlock_irqrestore(&driver_name_lock, flags);
185         put_driver(drv);
186 
187         return ret;
188 }
189 
190 #define err_printk(dev, entry, format, arg...) do {                     \
191                 error_count += 1;                                       \
192                 if (driver_filter(dev) &&                               \
193                     (show_all_errors || show_num_errors > 0)) {         \
194                         WARN(1, "%s %s: " format,                       \
195                              dev ? dev_driver_string(dev) : "NULL",     \
196                              dev ? dev_name(dev) : "NULL", ## arg);     \
197                         dump_entry_trace(entry);                        \
198                 }                                                       \
199                 if (!show_all_errors && show_num_errors > 0)            \
200                         show_num_errors -= 1;                           \
201         } while (0);
202 
203 /*
204  * Hash related functions
205  *
206  * Every DMA-API request is saved into a struct dma_debug_entry. To
207  * have quick access to these structs they are stored into a hash.
208  */
209 static int hash_fn(struct dma_debug_entry *entry)
210 {
211         /*
212          * Hash function is based on the dma address.
213          * We use bits 20-27 here as the index into the hash
214          */
215         return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
216 }
217 
218 /*
219  * Request exclusive access to a hash bucket for a given dma_debug_entry.
220  */
221 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
222                                            unsigned long *flags)
223 {
224         int idx = hash_fn(entry);
225         unsigned long __flags;
226 
227         spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
228         *flags = __flags;
229         return &dma_entry_hash[idx];
230 }
231 
232 /*
233  * Give up exclusive access to the hash bucket
234  */
235 static void put_hash_bucket(struct hash_bucket *bucket,
236                             unsigned long *flags)
237 {
238         unsigned long __flags = *flags;
239 
240         spin_unlock_irqrestore(&bucket->lock, __flags);
241 }
242 
243 /*
244  * Search a given entry in the hash bucket list
245  */
246 static struct dma_debug_entry *hash_bucket_find(struct hash_bucket *bucket,
247                                                 struct dma_debug_entry *ref)
248 {
249         struct dma_debug_entry *entry, *ret = NULL;
250         int matches = 0, match_lvl, last_lvl = 0;
251 
252         list_for_each_entry(entry, &bucket->list, list) {
253                 if ((entry->dev_addr != ref->dev_addr) ||
254                     (entry->dev != ref->dev))
255                         continue;
256 
257                 /*
258                  * Some drivers map the same physical address multiple
259                  * times. Without a hardware IOMMU this results in the
260                  * same device addresses being put into the dma-debug
261                  * hash multiple times too. This can result in false
262                  * positives being reported. Therefore we implement a
263                  * best-fit algorithm here which returns the entry from
264                  * the hash which fits best to the reference value
265                  * instead of the first-fit.
266                  */
267                 matches += 1;
268                 match_lvl = 0;
269                 entry->size         == ref->size         ? ++match_lvl : 0;
270                 entry->type         == ref->type         ? ++match_lvl : 0;
271                 entry->direction    == ref->direction    ? ++match_lvl : 0;
272                 entry->sg_call_ents == ref->sg_call_ents ? ++match_lvl : 0;
273 
274                 if (match_lvl == 4) {
275                         /* perfect-fit - return the result */
276                         return entry;
277                 } else if (match_lvl > last_lvl) {
278                         /*
279                          * We found an entry that fits better then the
280                          * previous one
281                          */
282                         last_lvl = match_lvl;
283                         ret      = entry;
284                 }
285         }
286 
287         /*
288          * If we have multiple matches but no perfect-fit, just return
289          * NULL.
290          */
291         ret = (matches == 1) ? ret : NULL;
292 
293         return ret;
294 }
295 
296 /*
297  * Add an entry to a hash bucket
298  */
299 static void hash_bucket_add(struct hash_bucket *bucket,
300                             struct dma_debug_entry *entry)
301 {
302         list_add_tail(&entry->list, &bucket->list);
303 }
304 
305 /*
306  * Remove entry from a hash bucket list
307  */
308 static void hash_bucket_del(struct dma_debug_entry *entry)
309 {
310         list_del(&entry->list);
311 }
312 
313 /*
314  * Dump mapping entries for debugging purposes
315  */
316 void debug_dma_dump_mappings(struct device *dev)
317 {
318         int idx;
319 
320         for (idx = 0; idx < HASH_SIZE; idx++) {
321                 struct hash_bucket *bucket = &dma_entry_hash[idx];
322                 struct dma_debug_entry *entry;
323                 unsigned long flags;
324 
325                 spin_lock_irqsave(&bucket->lock, flags);
326 
327                 list_for_each_entry(entry, &bucket->list, list) {
328                         if (!dev || dev == entry->dev) {
329                                 dev_info(entry->dev,
330                                          "%s idx %d P=%Lx D=%Lx L=%Lx %s\n",
331                                          type2name[entry->type], idx,
332                                          (unsigned long long)entry->paddr,
333                                          entry->dev_addr, entry->size,
334                                          dir2name[entry->direction]);
335                         }
336                 }
337 
338                 spin_unlock_irqrestore(&bucket->lock, flags);
339         }
340 }
341 EXPORT_SYMBOL(debug_dma_dump_mappings);
342 
343 /*
344  * Wrapper function for adding an entry to the hash.
345  * This function takes care of locking itself.
346  */
347 static void add_dma_entry(struct dma_debug_entry *entry)
348 {
349         struct hash_bucket *bucket;
350         unsigned long flags;
351 
352         bucket = get_hash_bucket(entry, &flags);
353         hash_bucket_add(bucket, entry);
354         put_hash_bucket(bucket, &flags);
355 }
356 
357 static struct dma_debug_entry *__dma_entry_alloc(void)
358 {
359         struct dma_debug_entry *entry;
360 
361         entry = list_entry(free_entries.next, struct dma_debug_entry, list);
362         list_del(&entry->list);
363         memset(entry, 0, sizeof(*entry));
364 
365         num_free_entries -= 1;
366         if (num_free_entries < min_free_entries)
367                 min_free_entries = num_free_entries;
368 
369         return entry;
370 }
371 
372 /* struct dma_entry allocator
373  *
374  * The next two functions implement the allocator for
375  * struct dma_debug_entries.
376  */
377 static struct dma_debug_entry *dma_entry_alloc(void)
378 {
379         struct dma_debug_entry *entry = NULL;
380         unsigned long flags;
381 
382         spin_lock_irqsave(&free_entries_lock, flags);
383 
384         if (list_empty(&free_entries)) {
385                 pr_err("DMA-API: debugging out of memory - disabling\n");
386                 global_disable = true;
387                 goto out;
388         }
389 
390         entry = __dma_entry_alloc();
391 
392 #ifdef CONFIG_STACKTRACE
393         entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES;
394         entry->stacktrace.entries = entry->st_entries;
395         entry->stacktrace.skip = 2;
396         save_stack_trace(&entry->stacktrace);
397 #endif
398 
399 out:
400         spin_unlock_irqrestore(&free_entries_lock, flags);
401 
402         return entry;
403 }
404 
405 static void dma_entry_free(struct dma_debug_entry *entry)
406 {
407         unsigned long flags;
408 
409         /*
410          * add to beginning of the list - this way the entries are
411          * more likely cache hot when they are reallocated.
412          */
413         spin_lock_irqsave(&free_entries_lock, flags);
414         list_add(&entry->list, &free_entries);
415         num_free_entries += 1;
416         spin_unlock_irqrestore(&free_entries_lock, flags);
417 }
418 
419 int dma_debug_resize_entries(u32 num_entries)
420 {
421         int i, delta, ret = 0;
422         unsigned long flags;
423         struct dma_debug_entry *entry;
424         LIST_HEAD(tmp);
425 
426         spin_lock_irqsave(&free_entries_lock, flags);
427 
428         if (nr_total_entries < num_entries) {
429                 delta = num_entries - nr_total_entries;
430 
431                 spin_unlock_irqrestore(&free_entries_lock, flags);
432 
433                 for (i = 0; i < delta; i++) {
434                         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
435                         if (!entry)
436                                 break;
437 
438                         list_add_tail(&entry->list, &tmp);
439                 }
440 
441                 spin_lock_irqsave(&free_entries_lock, flags);
442 
443                 list_splice(&tmp, &free_entries);
444                 nr_total_entries += i;
445                 num_free_entries += i;
446         } else {
447                 delta = nr_total_entries - num_entries;
448 
449                 for (i = 0; i < delta && !list_empty(&free_entries); i++) {
450                         entry = __dma_entry_alloc();
451                         kfree(entry);
452                 }
453 
454                 nr_total_entries -= i;
455         }
456 
457         if (nr_total_entries != num_entries)
458                 ret = 1;
459 
460         spin_unlock_irqrestore(&free_entries_lock, flags);
461 
462         return ret;
463 }
464 EXPORT_SYMBOL(dma_debug_resize_entries);
465 
466 /*
467  * DMA-API debugging init code
468  *
469  * The init code does two things:
470  *   1. Initialize core data structures
471  *   2. Preallocate a given number of dma_debug_entry structs
472  */
473 
474 static int prealloc_memory(u32 num_entries)
475 {
476         struct dma_debug_entry *entry, *next_entry;
477         int i;
478 
479         for (i = 0; i < num_entries; ++i) {
480                 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
481                 if (!entry)
482                         goto out_err;
483 
484                 list_add_tail(&entry->list, &free_entries);
485         }
486 
487         num_free_entries = num_entries;
488         min_free_entries = num_entries;
489 
490         pr_info("DMA-API: preallocated %d debug entries\n", num_entries);
491 
492         return 0;
493 
494 out_err:
495 
496         list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
497                 list_del(&entry->list);
498                 kfree(entry);
499         }
500 
501         return -ENOMEM;
502 }
503 
504 static ssize_t filter_read(struct file *file, char __user *user_buf,
505                            size_t count, loff_t *ppos)
506 {
507         char buf[NAME_MAX_LEN + 1];
508         unsigned long flags;
509         int len;
510 
511         if (!current_driver_name[0])
512                 return 0;
513 
514         /*
515          * We can't copy to userspace directly because current_driver_name can
516          * only be read under the driver_name_lock with irqs disabled. So
517          * create a temporary copy first.
518          */
519         read_lock_irqsave(&driver_name_lock, flags);
520         len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
521         read_unlock_irqrestore(&driver_name_lock, flags);
522 
523         return simple_read_from_buffer(user_buf, count, ppos, buf, len);
524 }
525 
526 static ssize_t filter_write(struct file *file, const char __user *userbuf,
527                             size_t count, loff_t *ppos)
528 {
529         char buf[NAME_MAX_LEN];
530         unsigned long flags;
531         size_t len;
532         int i;
533 
534         /*
535          * We can't copy from userspace directly. Access to
536          * current_driver_name is protected with a write_lock with irqs
537          * disabled. Since copy_from_user can fault and may sleep we
538          * need to copy to temporary buffer first
539          */
540         len = min(count, (size_t)(NAME_MAX_LEN - 1));
541         if (copy_from_user(buf, userbuf, len))
542                 return -EFAULT;
543 
544         buf[len] = 0;
545 
546         write_lock_irqsave(&driver_name_lock, flags);
547 
548         /*
549          * Now handle the string we got from userspace very carefully.
550          * The rules are:
551          *         - only use the first token we got
552          *         - token delimiter is everything looking like a space
553          *           character (' ', '\n', '\t' ...)
554          *
555          */
556         if (!isalnum(buf[0])) {
557                 /*
558                  * If the first character userspace gave us is not
559                  * alphanumerical then assume the filter should be
560                  * switched off.
561                  */
562                 if (current_driver_name[0])
563                         pr_info("DMA-API: switching off dma-debug driver filter\n");
564                 current_driver_name[0] = 0;
565                 current_driver = NULL;
566                 goto out_unlock;
567         }
568 
569         /*
570          * Now parse out the first token and use it as the name for the
571          * driver to filter for.
572          */
573         for (i = 0; i < NAME_MAX_LEN - 1; ++i) {
574                 current_driver_name[i] = buf[i];
575                 if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
576                         break;
577         }
578         current_driver_name[i] = 0;
579         current_driver = NULL;
580 
581         pr_info("DMA-API: enable driver filter for driver [%s]\n",
582                 current_driver_name);
583 
584 out_unlock:
585         write_unlock_irqrestore(&driver_name_lock, flags);
586 
587         return count;
588 }
589 
590 static const struct file_operations filter_fops = {
591         .read  = filter_read,
592         .write = filter_write,
593         .llseek = default_llseek,
594 };
595 
596 static int dma_debug_fs_init(void)
597 {
598         dma_debug_dent = debugfs_create_dir("dma-api", NULL);
599         if (!dma_debug_dent) {
600                 pr_err("DMA-API: can not create debugfs directory\n");
601                 return -ENOMEM;
602         }
603 
604         global_disable_dent = debugfs_create_bool("disabled", 0444,
605                         dma_debug_dent,
606                         (u32 *)&global_disable);
607         if (!global_disable_dent)
608                 goto out_err;
609 
610         error_count_dent = debugfs_create_u32("error_count", 0444,
611                         dma_debug_dent, &error_count);
612         if (!error_count_dent)
613                 goto out_err;
614 
615         show_all_errors_dent = debugfs_create_u32("all_errors", 0644,
616                         dma_debug_dent,
617                         &show_all_errors);
618         if (!show_all_errors_dent)
619                 goto out_err;
620 
621         show_num_errors_dent = debugfs_create_u32("num_errors", 0644,
622                         dma_debug_dent,
623                         &show_num_errors);
624         if (!show_num_errors_dent)
625                 goto out_err;
626 
627         num_free_entries_dent = debugfs_create_u32("num_free_entries", 0444,
628                         dma_debug_dent,
629                         &num_free_entries);
630         if (!num_free_entries_dent)
631                 goto out_err;
632 
633         min_free_entries_dent = debugfs_create_u32("min_free_entries", 0444,
634                         dma_debug_dent,
635                         &min_free_entries);
636         if (!min_free_entries_dent)
637                 goto out_err;
638 
639         filter_dent = debugfs_create_file("driver_filter", 0644,
640                                           dma_debug_dent, NULL, &filter_fops);
641         if (!filter_dent)
642                 goto out_err;
643 
644         return 0;
645 
646 out_err:
647         debugfs_remove_recursive(dma_debug_dent);
648 
649         return -ENOMEM;
650 }
651 
652 static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry)
653 {
654         struct dma_debug_entry *entry;
655         unsigned long flags;
656         int count = 0, i;
657 
658         local_irq_save(flags);
659 
660         for (i = 0; i < HASH_SIZE; ++i) {
661                 spin_lock(&dma_entry_hash[i].lock);
662                 list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
663                         if (entry->dev == dev) {
664                                 count += 1;
665                                 *out_entry = entry;
666                         }
667                 }
668                 spin_unlock(&dma_entry_hash[i].lock);
669         }
670 
671         local_irq_restore(flags);
672 
673         return count;
674 }
675 
676 static int dma_debug_device_change(struct notifier_block *nb, unsigned long action, void *data)
677 {
678         struct device *dev = data;
679         struct dma_debug_entry *uninitialized_var(entry);
680         int count;
681 
682         if (global_disable)
683                 return 0;
684 
685         switch (action) {
686         case BUS_NOTIFY_UNBOUND_DRIVER:
687                 count = device_dma_allocations(dev, &entry);
688                 if (count == 0)
689                         break;
690                 err_printk(dev, entry, "DMA-API: device driver has pending "
691                                 "DMA allocations while released from device "
692                                 "[count=%d]\n"
693                                 "One of leaked entries details: "
694                                 "[device address=0x%016llx] [size=%llu bytes] "
695                                 "[mapped with %s] [mapped as %s]\n",
696                         count, entry->dev_addr, entry->size,
697                         dir2name[entry->direction], type2name[entry->type]);
698                 break;
699         default:
700                 break;
701         }
702 
703         return 0;
704 }
705 
706 void dma_debug_add_bus(struct bus_type *bus)
707 {
708         struct notifier_block *nb;
709 
710         if (global_disable)
711                 return;
712 
713         nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
714         if (nb == NULL) {
715                 pr_err("dma_debug_add_bus: out of memory\n");
716                 return;
717         }
718 
719         nb->notifier_call = dma_debug_device_change;
720 
721         bus_register_notifier(bus, nb);
722 }
723 
724 /*
725  * Let the architectures decide how many entries should be preallocated.
726  */
727 void dma_debug_init(u32 num_entries)
728 {
729         int i;
730 
731         if (global_disable)
732                 return;
733 
734         for (i = 0; i < HASH_SIZE; ++i) {
735                 INIT_LIST_HEAD(&dma_entry_hash[i].list);
736                 spin_lock_init(&dma_entry_hash[i].lock);
737         }
738 
739         if (dma_debug_fs_init() != 0) {
740                 pr_err("DMA-API: error creating debugfs entries - disabling\n");
741                 global_disable = true;
742 
743                 return;
744         }
745 
746         if (req_entries)
747                 num_entries = req_entries;
748 
749         if (prealloc_memory(num_entries) != 0) {
750                 pr_err("DMA-API: debugging out of memory error - disabled\n");
751                 global_disable = true;
752 
753                 return;
754         }
755 
756         nr_total_entries = num_free_entries;
757 
758         pr_info("DMA-API: debugging enabled by kernel config\n");
759 }
760 
761 static __init int dma_debug_cmdline(char *str)
762 {
763         if (!str)
764                 return -EINVAL;
765 
766         if (strncmp(str, "off", 3) == 0) {
767                 pr_info("DMA-API: debugging disabled on kernel command line\n");
768                 global_disable = true;
769         }
770 
771         return 0;
772 }
773 
774 static __init int dma_debug_entries_cmdline(char *str)
775 {
776         int res;
777 
778         if (!str)
779                 return -EINVAL;
780 
781         res = get_option(&str, &req_entries);
782 
783         if (!res)
784                 req_entries = 0;
785 
786         return 0;
787 }
788 
789 __setup("dma_debug=", dma_debug_cmdline);
790 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
791 
792 static void check_unmap(struct dma_debug_entry *ref)
793 {
794         struct dma_debug_entry *entry;
795         struct hash_bucket *bucket;
796         unsigned long flags;
797 
798         if (dma_mapping_error(ref->dev, ref->dev_addr)) {
799                 err_printk(ref->dev, NULL, "DMA-API: device driver tries "
800                            "to free an invalid DMA memory address\n");
801                 return;
802         }
803 
804         bucket = get_hash_bucket(ref, &flags);
805         entry = hash_bucket_find(bucket, ref);
806 
807         if (!entry) {
808                 err_printk(ref->dev, NULL, "DMA-API: device driver tries "
809                            "to free DMA memory it has not allocated "
810                            "[device address=0x%016llx] [size=%llu bytes]\n",
811                            ref->dev_addr, ref->size);
812                 goto out;
813         }
814 
815         if (ref->size != entry->size) {
816                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
817                            "DMA memory with different size "
818                            "[device address=0x%016llx] [map size=%llu bytes] "
819                            "[unmap size=%llu bytes]\n",
820                            ref->dev_addr, entry->size, ref->size);
821         }
822 
823         if (ref->type != entry->type) {
824                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
825                            "DMA memory with wrong function "
826                            "[device address=0x%016llx] [size=%llu bytes] "
827                            "[mapped as %s] [unmapped as %s]\n",
828                            ref->dev_addr, ref->size,
829                            type2name[entry->type], type2name[ref->type]);
830         } else if ((entry->type == dma_debug_coherent) &&
831                    (ref->paddr != entry->paddr)) {
832                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
833                            "DMA memory with different CPU address "
834                            "[device address=0x%016llx] [size=%llu bytes] "
835                            "[cpu alloc address=0x%016llx] "
836                            "[cpu free address=0x%016llx]",
837                            ref->dev_addr, ref->size,
838                            (unsigned long long)entry->paddr,
839                            (unsigned long long)ref->paddr);
840         }
841 
842         if (ref->sg_call_ents && ref->type == dma_debug_sg &&
843             ref->sg_call_ents != entry->sg_call_ents) {
844                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
845                            "DMA sg list with different entry count "
846                            "[map count=%d] [unmap count=%d]\n",
847                            entry->sg_call_ents, ref->sg_call_ents);
848         }
849 
850         /*
851          * This may be no bug in reality - but most implementations of the
852          * DMA API don't handle this properly, so check for it here
853          */
854         if (ref->direction != entry->direction) {
855                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
856                            "DMA memory with different direction "
857                            "[device address=0x%016llx] [size=%llu bytes] "
858                            "[mapped with %s] [unmapped with %s]\n",
859                            ref->dev_addr, ref->size,
860                            dir2name[entry->direction],
861                            dir2name[ref->direction]);
862         }
863 
864         hash_bucket_del(entry);
865         dma_entry_free(entry);
866 
867 out:
868         put_hash_bucket(bucket, &flags);
869 }
870 
871 static void check_for_stack(struct device *dev, void *addr)
872 {
873         if (object_is_on_stack(addr))
874                 err_printk(dev, NULL, "DMA-API: device driver maps memory from"
875                                 "stack [addr=%p]\n", addr);
876 }
877 
878 static inline bool overlap(void *addr, unsigned long len, void *start, void *end)
879 {
880         unsigned long a1 = (unsigned long)addr;
881         unsigned long b1 = a1 + len;
882         unsigned long a2 = (unsigned long)start;
883         unsigned long b2 = (unsigned long)end;
884 
885         return !(b1 <= a2 || a1 >= b2);
886 }
887 
888 static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
889 {
890         if (overlap(addr, len, _text, _etext) ||
891             overlap(addr, len, __start_rodata, __end_rodata))
892                 err_printk(dev, NULL, "DMA-API: device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
893 }
894 
895 static void check_sync(struct device *dev,
896                        struct dma_debug_entry *ref,
897                        bool to_cpu)
898 {
899         struct dma_debug_entry *entry;
900         struct hash_bucket *bucket;
901         unsigned long flags;
902 
903         bucket = get_hash_bucket(ref, &flags);
904 
905         entry = hash_bucket_find(bucket, ref);
906 
907         if (!entry) {
908                 err_printk(dev, NULL, "DMA-API: device driver tries "
909                                 "to sync DMA memory it has not allocated "
910                                 "[device address=0x%016llx] [size=%llu bytes]\n",
911                                 (unsigned long long)ref->dev_addr, ref->size);
912                 goto out;
913         }
914 
915         if (ref->size > entry->size) {
916                 err_printk(dev, entry, "DMA-API: device driver syncs"
917                                 " DMA memory outside allocated range "
918                                 "[device address=0x%016llx] "
919                                 "[allocation size=%llu bytes] "
920                                 "[sync offset+size=%llu]\n",
921                                 entry->dev_addr, entry->size,
922                                 ref->size);
923         }
924 
925         if (entry->direction == DMA_BIDIRECTIONAL)
926                 goto out;
927 
928         if (ref->direction != entry->direction) {
929                 err_printk(dev, entry, "DMA-API: device driver syncs "
930                                 "DMA memory with different direction "
931                                 "[device address=0x%016llx] [size=%llu bytes] "
932                                 "[mapped with %s] [synced with %s]\n",
933                                 (unsigned long long)ref->dev_addr, entry->size,
934                                 dir2name[entry->direction],
935                                 dir2name[ref->direction]);
936         }
937 
938         if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
939                       !(ref->direction == DMA_TO_DEVICE))
940                 err_printk(dev, entry, "DMA-API: device driver syncs "
941                                 "device read-only DMA memory for cpu "
942                                 "[device address=0x%016llx] [size=%llu bytes] "
943                                 "[mapped with %s] [synced with %s]\n",
944                                 (unsigned long long)ref->dev_addr, entry->size,
945                                 dir2name[entry->direction],
946                                 dir2name[ref->direction]);
947 
948         if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
949                        !(ref->direction == DMA_FROM_DEVICE))
950                 err_printk(dev, entry, "DMA-API: device driver syncs "
951                                 "device write-only DMA memory to device "
952                                 "[device address=0x%016llx] [size=%llu bytes] "
953                                 "[mapped with %s] [synced with %s]\n",
954                                 (unsigned long long)ref->dev_addr, entry->size,
955                                 dir2name[entry->direction],
956                                 dir2name[ref->direction]);
957 
958 out:
959         put_hash_bucket(bucket, &flags);
960 }
961 
962 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
963                         size_t size, int direction, dma_addr_t dma_addr,
964                         bool map_single)
965 {
966         struct dma_debug_entry *entry;
967 
968         if (unlikely(global_disable))
969                 return;
970 
971         if (unlikely(dma_mapping_error(dev, dma_addr)))
972                 return;
973 
974         entry = dma_entry_alloc();
975         if (!entry)
976                 return;
977 
978         entry->dev       = dev;
979         entry->type      = dma_debug_page;
980         entry->paddr     = page_to_phys(page) + offset;
981         entry->dev_addr  = dma_addr;
982         entry->size      = size;
983         entry->direction = direction;
984 
985         if (map_single)
986                 entry->type = dma_debug_single;
987 
988         if (!PageHighMem(page)) {
989                 void *addr = page_address(page) + offset;
990 
991                 check_for_stack(dev, addr);
992                 check_for_illegal_area(dev, addr, size);
993         }
994 
995         add_dma_entry(entry);
996 }
997 EXPORT_SYMBOL(debug_dma_map_page);
998 
999 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
1000                           size_t size, int direction, bool map_single)
1001 {
1002         struct dma_debug_entry ref = {
1003                 .type           = dma_debug_page,
1004                 .dev            = dev,
1005                 .dev_addr       = addr,
1006                 .size           = size,
1007                 .direction      = direction,
1008         };
1009 
1010         if (unlikely(global_disable))
1011                 return;
1012 
1013         if (map_single)
1014                 ref.type = dma_debug_single;
1015 
1016         check_unmap(&ref);
1017 }
1018 EXPORT_SYMBOL(debug_dma_unmap_page);
1019 
1020 void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
1021                       int nents, int mapped_ents, int direction)
1022 {
1023         struct dma_debug_entry *entry;
1024         struct scatterlist *s;
1025         int i;
1026 
1027         if (unlikely(global_disable))
1028                 return;
1029 
1030         for_each_sg(sg, s, mapped_ents, i) {
1031                 entry = dma_entry_alloc();
1032                 if (!entry)
1033                         return;
1034 
1035                 entry->type           = dma_debug_sg;
1036                 entry->dev            = dev;
1037                 entry->paddr          = sg_phys(s);
1038                 entry->size           = sg_dma_len(s);
1039                 entry->dev_addr       = sg_dma_address(s);
1040                 entry->direction      = direction;
1041                 entry->sg_call_ents   = nents;
1042                 entry->sg_mapped_ents = mapped_ents;
1043 
1044                 if (!PageHighMem(sg_page(s))) {
1045                         check_for_stack(dev, sg_virt(s));
1046                         check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
1047                 }
1048 
1049                 add_dma_entry(entry);
1050         }
1051 }
1052 EXPORT_SYMBOL(debug_dma_map_sg);
1053 
1054 static int get_nr_mapped_entries(struct device *dev,
1055                                  struct dma_debug_entry *ref)
1056 {
1057         struct dma_debug_entry *entry;
1058         struct hash_bucket *bucket;
1059         unsigned long flags;
1060         int mapped_ents;
1061 
1062         bucket       = get_hash_bucket(ref, &flags);
1063         entry        = hash_bucket_find(bucket, ref);
1064         mapped_ents  = 0;
1065 
1066         if (entry)
1067                 mapped_ents = entry->sg_mapped_ents;
1068         put_hash_bucket(bucket, &flags);
1069 
1070         return mapped_ents;
1071 }
1072 
1073 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
1074                         int nelems, int dir)
1075 {
1076         struct scatterlist *s;
1077         int mapped_ents = 0, i;
1078 
1079         if (unlikely(global_disable))
1080                 return;
1081 
1082         for_each_sg(sglist, s, nelems, i) {
1083 
1084                 struct dma_debug_entry ref = {
1085                         .type           = dma_debug_sg,
1086                         .dev            = dev,
1087                         .paddr          = sg_phys(s),
1088                         .dev_addr       = sg_dma_address(s),
1089                         .size           = sg_dma_len(s),
1090                         .direction      = dir,
1091                         .sg_call_ents   = nelems,
1092                 };
1093 
1094                 if (mapped_ents && i >= mapped_ents)
1095                         break;
1096 
1097                 if (!i)
1098                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1099 
1100                 check_unmap(&ref);
1101         }
1102 }
1103 EXPORT_SYMBOL(debug_dma_unmap_sg);
1104 
1105 void debug_dma_alloc_coherent(struct device *dev, size_t size,
1106                               dma_addr_t dma_addr, void *virt)
1107 {
1108         struct dma_debug_entry *entry;
1109 
1110         if (unlikely(global_disable))
1111                 return;
1112 
1113         if (unlikely(virt == NULL))
1114                 return;
1115 
1116         entry = dma_entry_alloc();
1117         if (!entry)
1118                 return;
1119 
1120         entry->type      = dma_debug_coherent;
1121         entry->dev       = dev;
1122         entry->paddr     = virt_to_phys(virt);
1123         entry->size      = size;
1124         entry->dev_addr  = dma_addr;
1125         entry->direction = DMA_BIDIRECTIONAL;
1126 
1127         add_dma_entry(entry);
1128 }
1129 EXPORT_SYMBOL(debug_dma_alloc_coherent);
1130 
1131 void debug_dma_free_coherent(struct device *dev, size_t size,
1132                          void *virt, dma_addr_t addr)
1133 {
1134         struct dma_debug_entry ref = {
1135                 .type           = dma_debug_coherent,
1136                 .dev            = dev,
1137                 .paddr          = virt_to_phys(virt),
1138                 .dev_addr       = addr,
1139                 .size           = size,
1140                 .direction      = DMA_BIDIRECTIONAL,
1141         };
1142 
1143         if (unlikely(global_disable))
1144                 return;
1145 
1146         check_unmap(&ref);
1147 }
1148 EXPORT_SYMBOL(debug_dma_free_coherent);
1149 
1150 void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
1151                                    size_t size, int direction)
1152 {
1153         struct dma_debug_entry ref;
1154 
1155         if (unlikely(global_disable))
1156                 return;
1157 
1158         ref.type         = dma_debug_single;
1159         ref.dev          = dev;
1160         ref.dev_addr     = dma_handle;
1161         ref.size         = size;
1162         ref.direction    = direction;
1163         ref.sg_call_ents = 0;
1164 
1165         check_sync(dev, &ref, true);
1166 }
1167 EXPORT_SYMBOL(debug_dma_sync_single_for_cpu);
1168 
1169 void debug_dma_sync_single_for_device(struct device *dev,
1170                                       dma_addr_t dma_handle, size_t size,
1171                                       int direction)
1172 {
1173         struct dma_debug_entry ref;
1174 
1175         if (unlikely(global_disable))
1176                 return;
1177 
1178         ref.type         = dma_debug_single;
1179         ref.dev          = dev;
1180         ref.dev_addr     = dma_handle;
1181         ref.size         = size;
1182         ref.direction    = direction;
1183         ref.sg_call_ents = 0;
1184 
1185         check_sync(dev, &ref, false);
1186 }
1187 EXPORT_SYMBOL(debug_dma_sync_single_for_device);
1188 
1189 void debug_dma_sync_single_range_for_cpu(struct device *dev,
1190                                          dma_addr_t dma_handle,
1191                                          unsigned long offset, size_t size,
1192                                          int direction)
1193 {
1194         struct dma_debug_entry ref;
1195 
1196         if (unlikely(global_disable))
1197                 return;
1198 
1199         ref.type         = dma_debug_single;
1200         ref.dev          = dev;
1201         ref.dev_addr     = dma_handle;
1202         ref.size         = offset + size;
1203         ref.direction    = direction;
1204         ref.sg_call_ents = 0;
1205 
1206         check_sync(dev, &ref, true);
1207 }
1208 EXPORT_SYMBOL(debug_dma_sync_single_range_for_cpu);
1209 
1210 void debug_dma_sync_single_range_for_device(struct device *dev,
1211                                             dma_addr_t dma_handle,
1212                                             unsigned long offset,
1213                                             size_t size, int direction)
1214 {
1215         struct dma_debug_entry ref;
1216 
1217         if (unlikely(global_disable))
1218                 return;
1219 
1220         ref.type         = dma_debug_single;
1221         ref.dev          = dev;
1222         ref.dev_addr     = dma_handle;
1223         ref.size         = offset + size;
1224         ref.direction    = direction;
1225         ref.sg_call_ents = 0;
1226 
1227         check_sync(dev, &ref, false);
1228 }
1229 EXPORT_SYMBOL(debug_dma_sync_single_range_for_device);
1230 
1231 void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
1232                                int nelems, int direction)
1233 {
1234         struct scatterlist *s;
1235         int mapped_ents = 0, i;
1236 
1237         if (unlikely(global_disable))
1238                 return;
1239 
1240         for_each_sg(sg, s, nelems, i) {
1241 
1242                 struct dma_debug_entry ref = {
1243                         .type           = dma_debug_sg,
1244                         .dev            = dev,
1245                         .paddr          = sg_phys(s),
1246                         .dev_addr       = sg_dma_address(s),
1247                         .size           = sg_dma_len(s),
1248                         .direction      = direction,
1249                         .sg_call_ents   = nelems,
1250                 };
1251 
1252                 if (!i)
1253                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1254 
1255                 if (i >= mapped_ents)
1256                         break;
1257 
1258                 check_sync(dev, &ref, true);
1259         }
1260 }
1261 EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
1262 
1263 void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
1264                                   int nelems, int direction)
1265 {
1266         struct scatterlist *s;
1267         int mapped_ents = 0, i;
1268 
1269         if (unlikely(global_disable))
1270                 return;
1271 
1272         for_each_sg(sg, s, nelems, i) {
1273 
1274                 struct dma_debug_entry ref = {
1275                         .type           = dma_debug_sg,
1276                         .dev            = dev,
1277                         .paddr          = sg_phys(s),
1278                         .dev_addr       = sg_dma_address(s),
1279                         .size           = sg_dma_len(s),
1280                         .direction      = direction,
1281                         .sg_call_ents   = nelems,
1282                 };
1283                 if (!i)
1284                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1285 
1286                 if (i >= mapped_ents)
1287                         break;
1288 
1289                 check_sync(dev, &ref, false);
1290         }
1291 }
1292 EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
1293 
1294 static int __init dma_debug_driver_setup(char *str)
1295 {
1296         int i;
1297 
1298         for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
1299                 current_driver_name[i] = *str;
1300                 if (*str == 0)
1301                         break;
1302         }
1303 
1304         if (current_driver_name[0])
1305                 pr_info("DMA-API: enable driver filter for driver [%s]\n",
1306                         current_driver_name);
1307 
1308 
1309         return 1;
1310 }
1311 __setup("dma_debug_driver=", dma_debug_driver_setup);
1312 

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