2 * Copyright (C) 2008 Advanced Micro Devices, Inc.
4 * Author: Joerg Roedel <joerg.roedel@amd.com>
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.
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.
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
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/vmalloc.h>
26 #include <linux/debugfs.h>
27 #include <linux/uaccess.h>
28 #include <linux/export.h>
29 #include <linux/device.h>
30 #include <linux/types.h>
31 #include <linux/sched.h>
32 #include <linux/ctype.h>
33 #include <linux/list.h>
34 #include <linux/slab.h>
36 #include <asm/sections.h>
38 #define HASH_SIZE 1024ULL
39 #define HASH_FN_SHIFT 13
40 #define HASH_FN_MASK (HASH_SIZE - 1)
51 MAP_ERR_CHECK_NOT_APPLICABLE,
56 #define DMA_DEBUG_STACKTRACE_ENTRIES 5
59 * struct dma_debug_entry - track a dma_map* or dma_alloc_coherent mapping
60 * @list: node on pre-allocated free_entries list
61 * @dev: 'dev' argument to dma_map_{page|single|sg} or dma_alloc_coherent
62 * @type: single, page, sg, coherent
63 * @pfn: page frame of the start address
64 * @offset: offset of mapping relative to pfn
65 * @size: length of the mapping
66 * @direction: enum dma_data_direction
67 * @sg_call_ents: 'nents' from dma_map_sg
68 * @sg_mapped_ents: 'mapped_ents' from dma_map_sg
69 * @map_err_type: track whether dma_mapping_error() was checked
70 * @stacktrace: support backtraces when a violation is detected
72 struct dma_debug_entry {
73 struct list_head list;
83 enum map_err_types map_err_type;
84 #ifdef CONFIG_STACKTRACE
85 struct stack_trace stacktrace;
86 unsigned long st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
90 typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *);
93 struct list_head list;
95 } ____cacheline_aligned_in_smp;
97 /* Hash list to save the allocated dma addresses */
98 static struct hash_bucket dma_entry_hash[HASH_SIZE];
99 /* List of pre-allocated dma_debug_entry's */
100 static LIST_HEAD(free_entries);
101 /* Lock for the list above */
102 static DEFINE_SPINLOCK(free_entries_lock);
104 /* Global disable flag - will be set in case of an error */
105 static bool global_disable __read_mostly;
107 /* Early initialization disable flag, set at the end of dma_debug_init */
108 static bool dma_debug_initialized __read_mostly;
110 static inline bool dma_debug_disabled(void)
112 return global_disable || !dma_debug_initialized;
115 /* Global error count */
116 static u32 error_count;
118 /* Global error show enable*/
119 static u32 show_all_errors __read_mostly;
120 /* Number of errors to show */
121 static u32 show_num_errors = 1;
123 static u32 num_free_entries;
124 static u32 min_free_entries;
125 static u32 nr_total_entries;
127 /* number of preallocated entries requested by kernel cmdline */
128 static u32 req_entries;
130 /* debugfs dentry's for the stuff above */
131 static struct dentry *dma_debug_dent __read_mostly;
132 static struct dentry *global_disable_dent __read_mostly;
133 static struct dentry *error_count_dent __read_mostly;
134 static struct dentry *show_all_errors_dent __read_mostly;
135 static struct dentry *show_num_errors_dent __read_mostly;
136 static struct dentry *num_free_entries_dent __read_mostly;
137 static struct dentry *min_free_entries_dent __read_mostly;
138 static struct dentry *filter_dent __read_mostly;
140 /* per-driver filter related state */
142 #define NAME_MAX_LEN 64
144 static char current_driver_name[NAME_MAX_LEN] __read_mostly;
145 static struct device_driver *current_driver __read_mostly;
147 static DEFINE_RWLOCK(driver_name_lock);
149 static const char *const maperr2str[] = {
150 [MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
151 [MAP_ERR_NOT_CHECKED] = "dma map error not checked",
152 [MAP_ERR_CHECKED] = "dma map error checked",
155 static const char *type2name[5] = { "single", "page",
156 "scather-gather", "coherent",
159 static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
160 "DMA_FROM_DEVICE", "DMA_NONE" };
163 * The access to some variables in this macro is racy. We can't use atomic_t
164 * here because all these variables are exported to debugfs. Some of them even
165 * writeable. This is also the reason why a lock won't help much. But anyway,
166 * the races are no big deal. Here is why:
168 * error_count: the addition is racy, but the worst thing that can happen is
169 * that we don't count some errors
170 * show_num_errors: the subtraction is racy. Also no big deal because in
171 * worst case this will result in one warning more in the
172 * system log than the user configured. This variable is
173 * writeable via debugfs.
175 static inline void dump_entry_trace(struct dma_debug_entry *entry)
177 #ifdef CONFIG_STACKTRACE
179 pr_warning("Mapped at:\n");
180 print_stack_trace(&entry->stacktrace, 0);
185 static bool driver_filter(struct device *dev)
187 struct device_driver *drv;
191 /* driver filter off */
192 if (likely(!current_driver_name[0]))
195 /* driver filter on and initialized */
196 if (current_driver && dev && dev->driver == current_driver)
199 /* driver filter on, but we can't filter on a NULL device... */
203 if (current_driver || !current_driver_name[0])
206 /* driver filter on but not yet initialized */
211 /* lock to protect against change of current_driver_name */
212 read_lock_irqsave(&driver_name_lock, flags);
216 strncmp(current_driver_name, drv->name, NAME_MAX_LEN - 1) == 0) {
217 current_driver = drv;
221 read_unlock_irqrestore(&driver_name_lock, flags);
226 #define err_printk(dev, entry, format, arg...) do { \
228 if (driver_filter(dev) && \
229 (show_all_errors || show_num_errors > 0)) { \
230 WARN(1, "%s %s: " format, \
231 dev ? dev_driver_string(dev) : "NULL", \
232 dev ? dev_name(dev) : "NULL", ## arg); \
233 dump_entry_trace(entry); \
235 if (!show_all_errors && show_num_errors > 0) \
236 show_num_errors -= 1; \
240 * Hash related functions
242 * Every DMA-API request is saved into a struct dma_debug_entry. To
243 * have quick access to these structs they are stored into a hash.
245 static int hash_fn(struct dma_debug_entry *entry)
248 * Hash function is based on the dma address.
249 * We use bits 20-27 here as the index into the hash
251 return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
255 * Request exclusive access to a hash bucket for a given dma_debug_entry.
257 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
258 unsigned long *flags)
259 __acquires(&dma_entry_hash[idx].lock)
261 int idx = hash_fn(entry);
262 unsigned long __flags;
264 spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
266 return &dma_entry_hash[idx];
270 * Give up exclusive access to the hash bucket
272 static void put_hash_bucket(struct hash_bucket *bucket,
273 unsigned long *flags)
274 __releases(&bucket->lock)
276 unsigned long __flags = *flags;
278 spin_unlock_irqrestore(&bucket->lock, __flags);
281 static bool exact_match(struct dma_debug_entry *a, struct dma_debug_entry *b)
283 return ((a->dev_addr == b->dev_addr) &&
284 (a->dev == b->dev)) ? true : false;
287 static bool containing_match(struct dma_debug_entry *a,
288 struct dma_debug_entry *b)
290 if (a->dev != b->dev)
293 if ((b->dev_addr <= a->dev_addr) &&
294 ((b->dev_addr + b->size) >= (a->dev_addr + a->size)))
301 * Search a given entry in the hash bucket list
303 static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
304 struct dma_debug_entry *ref,
307 struct dma_debug_entry *entry, *ret = NULL;
308 int matches = 0, match_lvl, last_lvl = -1;
310 list_for_each_entry(entry, &bucket->list, list) {
311 if (!match(ref, entry))
315 * Some drivers map the same physical address multiple
316 * times. Without a hardware IOMMU this results in the
317 * same device addresses being put into the dma-debug
318 * hash multiple times too. This can result in false
319 * positives being reported. Therefore we implement a
320 * best-fit algorithm here which returns the entry from
321 * the hash which fits best to the reference value
322 * instead of the first-fit.
326 entry->size == ref->size ? ++match_lvl : 0;
327 entry->type == ref->type ? ++match_lvl : 0;
328 entry->direction == ref->direction ? ++match_lvl : 0;
329 entry->sg_call_ents == ref->sg_call_ents ? ++match_lvl : 0;
331 if (match_lvl == 4) {
332 /* perfect-fit - return the result */
334 } else if (match_lvl > last_lvl) {
336 * We found an entry that fits better then the
337 * previous one or it is the 1st match.
339 last_lvl = match_lvl;
345 * If we have multiple matches but no perfect-fit, just return
348 ret = (matches == 1) ? ret : NULL;
353 static struct dma_debug_entry *bucket_find_exact(struct hash_bucket *bucket,
354 struct dma_debug_entry *ref)
356 return __hash_bucket_find(bucket, ref, exact_match);
359 static struct dma_debug_entry *bucket_find_contain(struct hash_bucket **bucket,
360 struct dma_debug_entry *ref,
361 unsigned long *flags)
364 unsigned int max_range = dma_get_max_seg_size(ref->dev);
365 struct dma_debug_entry *entry, index = *ref;
366 unsigned int range = 0;
368 while (range <= max_range) {
369 entry = __hash_bucket_find(*bucket, ref, containing_match);
375 * Nothing found, go back a hash bucket
377 put_hash_bucket(*bucket, flags);
378 range += (1 << HASH_FN_SHIFT);
379 index.dev_addr -= (1 << HASH_FN_SHIFT);
380 *bucket = get_hash_bucket(&index, flags);
387 * Add an entry to a hash bucket
389 static void hash_bucket_add(struct hash_bucket *bucket,
390 struct dma_debug_entry *entry)
392 list_add_tail(&entry->list, &bucket->list);
396 * Remove entry from a hash bucket list
398 static void hash_bucket_del(struct dma_debug_entry *entry)
400 list_del(&entry->list);
403 static unsigned long long phys_addr(struct dma_debug_entry *entry)
405 if (entry->type == dma_debug_resource)
406 return __pfn_to_phys(entry->pfn) + entry->offset;
408 return page_to_phys(pfn_to_page(entry->pfn)) + entry->offset;
412 * Dump mapping entries for debugging purposes
414 void debug_dma_dump_mappings(struct device *dev)
418 for (idx = 0; idx < HASH_SIZE; idx++) {
419 struct hash_bucket *bucket = &dma_entry_hash[idx];
420 struct dma_debug_entry *entry;
423 spin_lock_irqsave(&bucket->lock, flags);
425 list_for_each_entry(entry, &bucket->list, list) {
426 if (!dev || dev == entry->dev) {
428 "%s idx %d P=%Lx N=%lx D=%Lx L=%Lx %s %s\n",
429 type2name[entry->type], idx,
430 phys_addr(entry), entry->pfn,
431 entry->dev_addr, entry->size,
432 dir2name[entry->direction],
433 maperr2str[entry->map_err_type]);
437 spin_unlock_irqrestore(&bucket->lock, flags);
441 EXPORT_SYMBOL(debug_dma_dump_mappings);
444 * For each mapping (initial cacheline in the case of
445 * dma_alloc_coherent/dma_map_page, initial cacheline in each page of a
446 * scatterlist, or the cacheline specified in dma_map_single) insert
447 * into this tree using the cacheline as the key. At
448 * dma_unmap_{single|sg|page} or dma_free_coherent delete the entry. If
449 * the entry already exists at insertion time add a tag as a reference
450 * count for the overlapping mappings. For now, the overlap tracking
451 * just ensures that 'unmaps' balance 'maps' before marking the
452 * cacheline idle, but we should also be flagging overlaps as an API
455 * Memory usage is mostly constrained by the maximum number of available
456 * dma-debug entries in that we need a free dma_debug_entry before
457 * inserting into the tree. In the case of dma_map_page and
458 * dma_alloc_coherent there is only one dma_debug_entry and one
459 * dma_active_cacheline entry to track per event. dma_map_sg(), on the
460 * other hand, consumes a single dma_debug_entry, but inserts 'nents'
461 * entries into the tree.
463 * At any time debug_dma_assert_idle() can be called to trigger a
464 * warning if any cachelines in the given page are in the active set.
466 static RADIX_TREE(dma_active_cacheline, GFP_ATOMIC);
467 static DEFINE_SPINLOCK(radix_lock);
468 #define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1)
469 #define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT)
470 #define CACHELINES_PER_PAGE (1 << CACHELINE_PER_PAGE_SHIFT)
472 static phys_addr_t to_cacheline_number(struct dma_debug_entry *entry)
474 return (entry->pfn << CACHELINE_PER_PAGE_SHIFT) +
475 (entry->offset >> L1_CACHE_SHIFT);
478 static int active_cacheline_read_overlap(phys_addr_t cln)
482 for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
483 if (radix_tree_tag_get(&dma_active_cacheline, cln, i))
488 static int active_cacheline_set_overlap(phys_addr_t cln, int overlap)
492 if (overlap > ACTIVE_CACHELINE_MAX_OVERLAP || overlap < 0)
495 for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
496 if (overlap & 1 << i)
497 radix_tree_tag_set(&dma_active_cacheline, cln, i);
499 radix_tree_tag_clear(&dma_active_cacheline, cln, i);
504 static void active_cacheline_inc_overlap(phys_addr_t cln)
506 int overlap = active_cacheline_read_overlap(cln);
508 overlap = active_cacheline_set_overlap(cln, ++overlap);
510 /* If we overflowed the overlap counter then we're potentially
511 * leaking dma-mappings. Otherwise, if maps and unmaps are
512 * balanced then this overflow may cause false negatives in
513 * debug_dma_assert_idle() as the cacheline may be marked idle
516 WARN_ONCE(overlap > ACTIVE_CACHELINE_MAX_OVERLAP,
517 "DMA-API: exceeded %d overlapping mappings of cacheline %pa\n",
518 ACTIVE_CACHELINE_MAX_OVERLAP, &cln);
521 static int active_cacheline_dec_overlap(phys_addr_t cln)
523 int overlap = active_cacheline_read_overlap(cln);
525 return active_cacheline_set_overlap(cln, --overlap);
528 static int active_cacheline_insert(struct dma_debug_entry *entry)
530 phys_addr_t cln = to_cacheline_number(entry);
534 /* If the device is not writing memory then we don't have any
535 * concerns about the cpu consuming stale data. This mitigates
536 * legitimate usages of overlapping mappings.
538 if (entry->direction == DMA_TO_DEVICE)
541 spin_lock_irqsave(&radix_lock, flags);
542 rc = radix_tree_insert(&dma_active_cacheline, cln, entry);
544 active_cacheline_inc_overlap(cln);
545 spin_unlock_irqrestore(&radix_lock, flags);
550 static void active_cacheline_remove(struct dma_debug_entry *entry)
552 phys_addr_t cln = to_cacheline_number(entry);
555 /* ...mirror the insert case */
556 if (entry->direction == DMA_TO_DEVICE)
559 spin_lock_irqsave(&radix_lock, flags);
560 /* since we are counting overlaps the final put of the
561 * cacheline will occur when the overlap count is 0.
562 * active_cacheline_dec_overlap() returns -1 in that case
564 if (active_cacheline_dec_overlap(cln) < 0)
565 radix_tree_delete(&dma_active_cacheline, cln);
566 spin_unlock_irqrestore(&radix_lock, flags);
570 * debug_dma_assert_idle() - assert that a page is not undergoing dma
571 * @page: page to lookup in the dma_active_cacheline tree
573 * Place a call to this routine in cases where the cpu touching the page
574 * before the dma completes (page is dma_unmapped) will lead to data
577 void debug_dma_assert_idle(struct page *page)
579 static struct dma_debug_entry *ents[CACHELINES_PER_PAGE];
580 struct dma_debug_entry *entry = NULL;
581 void **results = (void **) &ents;
582 unsigned int nents, i;
586 if (dma_debug_disabled())
592 cln = (phys_addr_t) page_to_pfn(page) << CACHELINE_PER_PAGE_SHIFT;
593 spin_lock_irqsave(&radix_lock, flags);
594 nents = radix_tree_gang_lookup(&dma_active_cacheline, results, cln,
595 CACHELINES_PER_PAGE);
596 for (i = 0; i < nents; i++) {
597 phys_addr_t ent_cln = to_cacheline_number(ents[i]);
599 if (ent_cln == cln) {
602 } else if (ent_cln >= cln + CACHELINES_PER_PAGE)
605 spin_unlock_irqrestore(&radix_lock, flags);
610 cln = to_cacheline_number(entry);
611 err_printk(entry->dev, entry,
612 "DMA-API: cpu touching an active dma mapped cacheline [cln=%pa]\n",
617 * Wrapper function for adding an entry to the hash.
618 * This function takes care of locking itself.
620 static void add_dma_entry(struct dma_debug_entry *entry)
622 struct hash_bucket *bucket;
626 bucket = get_hash_bucket(entry, &flags);
627 hash_bucket_add(bucket, entry);
628 put_hash_bucket(bucket, &flags);
630 rc = active_cacheline_insert(entry);
632 pr_err("DMA-API: cacheline tracking ENOMEM, dma-debug disabled\n");
633 global_disable = true;
636 /* TODO: report -EEXIST errors here as overlapping mappings are
637 * not supported by the DMA API
641 static struct dma_debug_entry *__dma_entry_alloc(void)
643 struct dma_debug_entry *entry;
645 entry = list_entry(free_entries.next, struct dma_debug_entry, list);
646 list_del(&entry->list);
647 memset(entry, 0, sizeof(*entry));
649 num_free_entries -= 1;
650 if (num_free_entries < min_free_entries)
651 min_free_entries = num_free_entries;
656 /* struct dma_entry allocator
658 * The next two functions implement the allocator for
659 * struct dma_debug_entries.
661 static struct dma_debug_entry *dma_entry_alloc(void)
663 struct dma_debug_entry *entry;
666 spin_lock_irqsave(&free_entries_lock, flags);
668 if (list_empty(&free_entries)) {
669 global_disable = true;
670 spin_unlock_irqrestore(&free_entries_lock, flags);
671 pr_err("DMA-API: debugging out of memory - disabling\n");
675 entry = __dma_entry_alloc();
677 spin_unlock_irqrestore(&free_entries_lock, flags);
679 #ifdef CONFIG_STACKTRACE
680 entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES;
681 entry->stacktrace.entries = entry->st_entries;
682 entry->stacktrace.skip = 2;
683 save_stack_trace(&entry->stacktrace);
689 static void dma_entry_free(struct dma_debug_entry *entry)
693 active_cacheline_remove(entry);
696 * add to beginning of the list - this way the entries are
697 * more likely cache hot when they are reallocated.
699 spin_lock_irqsave(&free_entries_lock, flags);
700 list_add(&entry->list, &free_entries);
701 num_free_entries += 1;
702 spin_unlock_irqrestore(&free_entries_lock, flags);
705 int dma_debug_resize_entries(u32 num_entries)
707 int i, delta, ret = 0;
709 struct dma_debug_entry *entry;
712 spin_lock_irqsave(&free_entries_lock, flags);
714 if (nr_total_entries < num_entries) {
715 delta = num_entries - nr_total_entries;
717 spin_unlock_irqrestore(&free_entries_lock, flags);
719 for (i = 0; i < delta; i++) {
720 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
724 list_add_tail(&entry->list, &tmp);
727 spin_lock_irqsave(&free_entries_lock, flags);
729 list_splice(&tmp, &free_entries);
730 nr_total_entries += i;
731 num_free_entries += i;
733 delta = nr_total_entries - num_entries;
735 for (i = 0; i < delta && !list_empty(&free_entries); i++) {
736 entry = __dma_entry_alloc();
740 nr_total_entries -= i;
743 if (nr_total_entries != num_entries)
746 spin_unlock_irqrestore(&free_entries_lock, flags);
750 EXPORT_SYMBOL(dma_debug_resize_entries);
753 * DMA-API debugging init code
755 * The init code does two things:
756 * 1. Initialize core data structures
757 * 2. Preallocate a given number of dma_debug_entry structs
760 static int prealloc_memory(u32 num_entries)
762 struct dma_debug_entry *entry, *next_entry;
765 for (i = 0; i < num_entries; ++i) {
766 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
770 list_add_tail(&entry->list, &free_entries);
773 num_free_entries = num_entries;
774 min_free_entries = num_entries;
776 pr_info("DMA-API: preallocated %d debug entries\n", num_entries);
782 list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
783 list_del(&entry->list);
790 static ssize_t filter_read(struct file *file, char __user *user_buf,
791 size_t count, loff_t *ppos)
793 char buf[NAME_MAX_LEN + 1];
797 if (!current_driver_name[0])
801 * We can't copy to userspace directly because current_driver_name can
802 * only be read under the driver_name_lock with irqs disabled. So
803 * create a temporary copy first.
805 read_lock_irqsave(&driver_name_lock, flags);
806 len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
807 read_unlock_irqrestore(&driver_name_lock, flags);
809 return simple_read_from_buffer(user_buf, count, ppos, buf, len);
812 static ssize_t filter_write(struct file *file, const char __user *userbuf,
813 size_t count, loff_t *ppos)
815 char buf[NAME_MAX_LEN];
821 * We can't copy from userspace directly. Access to
822 * current_driver_name is protected with a write_lock with irqs
823 * disabled. Since copy_from_user can fault and may sleep we
824 * need to copy to temporary buffer first
826 len = min(count, (size_t)(NAME_MAX_LEN - 1));
827 if (copy_from_user(buf, userbuf, len))
832 write_lock_irqsave(&driver_name_lock, flags);
835 * Now handle the string we got from userspace very carefully.
837 * - only use the first token we got
838 * - token delimiter is everything looking like a space
839 * character (' ', '\n', '\t' ...)
842 if (!isalnum(buf[0])) {
844 * If the first character userspace gave us is not
845 * alphanumerical then assume the filter should be
848 if (current_driver_name[0])
849 pr_info("DMA-API: switching off dma-debug driver filter\n");
850 current_driver_name[0] = 0;
851 current_driver = NULL;
856 * Now parse out the first token and use it as the name for the
857 * driver to filter for.
859 for (i = 0; i < NAME_MAX_LEN - 1; ++i) {
860 current_driver_name[i] = buf[i];
861 if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
864 current_driver_name[i] = 0;
865 current_driver = NULL;
867 pr_info("DMA-API: enable driver filter for driver [%s]\n",
868 current_driver_name);
871 write_unlock_irqrestore(&driver_name_lock, flags);
876 static const struct file_operations filter_fops = {
878 .write = filter_write,
879 .llseek = default_llseek,
882 static int dma_debug_fs_init(void)
884 dma_debug_dent = debugfs_create_dir("dma-api", NULL);
885 if (!dma_debug_dent) {
886 pr_err("DMA-API: can not create debugfs directory\n");
890 global_disable_dent = debugfs_create_bool("disabled", 0444,
893 if (!global_disable_dent)
896 error_count_dent = debugfs_create_u32("error_count", 0444,
897 dma_debug_dent, &error_count);
898 if (!error_count_dent)
901 show_all_errors_dent = debugfs_create_u32("all_errors", 0644,
904 if (!show_all_errors_dent)
907 show_num_errors_dent = debugfs_create_u32("num_errors", 0644,
910 if (!show_num_errors_dent)
913 num_free_entries_dent = debugfs_create_u32("num_free_entries", 0444,
916 if (!num_free_entries_dent)
919 min_free_entries_dent = debugfs_create_u32("min_free_entries", 0444,
922 if (!min_free_entries_dent)
925 filter_dent = debugfs_create_file("driver_filter", 0644,
926 dma_debug_dent, NULL, &filter_fops);
933 debugfs_remove_recursive(dma_debug_dent);
938 static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry)
940 struct dma_debug_entry *entry;
944 local_irq_save(flags);
946 for (i = 0; i < HASH_SIZE; ++i) {
947 spin_lock(&dma_entry_hash[i].lock);
948 list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
949 if (entry->dev == dev) {
954 spin_unlock(&dma_entry_hash[i].lock);
957 local_irq_restore(flags);
962 static int dma_debug_device_change(struct notifier_block *nb, unsigned long action, void *data)
964 struct device *dev = data;
965 struct dma_debug_entry *uninitialized_var(entry);
968 if (dma_debug_disabled())
972 case BUS_NOTIFY_UNBOUND_DRIVER:
973 count = device_dma_allocations(dev, &entry);
976 err_printk(dev, entry, "DMA-API: device driver has pending "
977 "DMA allocations while released from device "
979 "One of leaked entries details: "
980 "[device address=0x%016llx] [size=%llu bytes] "
981 "[mapped with %s] [mapped as %s]\n",
982 count, entry->dev_addr, entry->size,
983 dir2name[entry->direction], type2name[entry->type]);
992 void dma_debug_add_bus(struct bus_type *bus)
994 struct notifier_block *nb;
996 if (dma_debug_disabled())
999 nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
1001 pr_err("dma_debug_add_bus: out of memory\n");
1005 nb->notifier_call = dma_debug_device_change;
1007 bus_register_notifier(bus, nb);
1011 * Let the architectures decide how many entries should be preallocated.
1013 void dma_debug_init(u32 num_entries)
1017 /* Do not use dma_debug_initialized here, since we really want to be
1018 * called to set dma_debug_initialized
1023 for (i = 0; i < HASH_SIZE; ++i) {
1024 INIT_LIST_HEAD(&dma_entry_hash[i].list);
1025 spin_lock_init(&dma_entry_hash[i].lock);
1028 if (dma_debug_fs_init() != 0) {
1029 pr_err("DMA-API: error creating debugfs entries - disabling\n");
1030 global_disable = true;
1036 num_entries = req_entries;
1038 if (prealloc_memory(num_entries) != 0) {
1039 pr_err("DMA-API: debugging out of memory error - disabled\n");
1040 global_disable = true;
1045 nr_total_entries = num_free_entries;
1047 dma_debug_initialized = true;
1049 pr_info("DMA-API: debugging enabled by kernel config\n");
1052 static __init int dma_debug_cmdline(char *str)
1057 if (strncmp(str, "off", 3) == 0) {
1058 pr_info("DMA-API: debugging disabled on kernel command line\n");
1059 global_disable = true;
1065 static __init int dma_debug_entries_cmdline(char *str)
1072 res = get_option(&str, &req_entries);
1080 __setup("dma_debug=", dma_debug_cmdline);
1081 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
1083 static void check_unmap(struct dma_debug_entry *ref)
1085 struct dma_debug_entry *entry;
1086 struct hash_bucket *bucket;
1087 unsigned long flags;
1089 bucket = get_hash_bucket(ref, &flags);
1090 entry = bucket_find_exact(bucket, ref);
1093 /* must drop lock before calling dma_mapping_error */
1094 put_hash_bucket(bucket, &flags);
1096 if (dma_mapping_error(ref->dev, ref->dev_addr)) {
1097 err_printk(ref->dev, NULL,
1098 "DMA-API: device driver tries to free an "
1099 "invalid DMA memory address\n");
1101 err_printk(ref->dev, NULL,
1102 "DMA-API: device driver tries to free DMA "
1103 "memory it has not allocated [device "
1104 "address=0x%016llx] [size=%llu bytes]\n",
1105 ref->dev_addr, ref->size);
1110 if (ref->size != entry->size) {
1111 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1112 "DMA memory with different size "
1113 "[device address=0x%016llx] [map size=%llu bytes] "
1114 "[unmap size=%llu bytes]\n",
1115 ref->dev_addr, entry->size, ref->size);
1118 if (ref->type != entry->type) {
1119 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1120 "DMA memory with wrong function "
1121 "[device address=0x%016llx] [size=%llu bytes] "
1122 "[mapped as %s] [unmapped as %s]\n",
1123 ref->dev_addr, ref->size,
1124 type2name[entry->type], type2name[ref->type]);
1125 } else if ((entry->type == dma_debug_coherent) &&
1126 (phys_addr(ref) != phys_addr(entry))) {
1127 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1128 "DMA memory with different CPU address "
1129 "[device address=0x%016llx] [size=%llu bytes] "
1130 "[cpu alloc address=0x%016llx] "
1131 "[cpu free address=0x%016llx]",
1132 ref->dev_addr, ref->size,
1137 if (ref->sg_call_ents && ref->type == dma_debug_sg &&
1138 ref->sg_call_ents != entry->sg_call_ents) {
1139 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1140 "DMA sg list with different entry count "
1141 "[map count=%d] [unmap count=%d]\n",
1142 entry->sg_call_ents, ref->sg_call_ents);
1146 * This may be no bug in reality - but most implementations of the
1147 * DMA API don't handle this properly, so check for it here
1149 if (ref->direction != entry->direction) {
1150 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1151 "DMA memory with different direction "
1152 "[device address=0x%016llx] [size=%llu bytes] "
1153 "[mapped with %s] [unmapped with %s]\n",
1154 ref->dev_addr, ref->size,
1155 dir2name[entry->direction],
1156 dir2name[ref->direction]);
1159 if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1160 err_printk(ref->dev, entry,
1161 "DMA-API: device driver failed to check map error"
1162 "[device address=0x%016llx] [size=%llu bytes] "
1164 ref->dev_addr, ref->size,
1165 type2name[entry->type]);
1168 hash_bucket_del(entry);
1169 dma_entry_free(entry);
1171 put_hash_bucket(bucket, &flags);
1174 static void check_for_stack(struct device *dev,
1175 struct page *page, size_t offset)
1178 struct vm_struct *stack_vm_area = task_stack_vm_area(current);
1180 if (!stack_vm_area) {
1181 /* Stack is direct-mapped. */
1182 if (PageHighMem(page))
1184 addr = page_address(page) + offset;
1185 if (object_is_on_stack(addr))
1186 err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [addr=%p]\n", addr);
1188 /* Stack is vmalloced. */
1191 for (i = 0; i < stack_vm_area->nr_pages; i++) {
1192 if (page != stack_vm_area->pages[i])
1195 addr = (u8 *)current->stack + i * PAGE_SIZE + offset;
1196 err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [probable addr=%p]\n", addr);
1202 static inline bool overlap(void *addr, unsigned long len, void *start, void *end)
1204 unsigned long a1 = (unsigned long)addr;
1205 unsigned long b1 = a1 + len;
1206 unsigned long a2 = (unsigned long)start;
1207 unsigned long b2 = (unsigned long)end;
1209 return !(b1 <= a2 || a1 >= b2);
1212 static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
1214 if (overlap(addr, len, _stext, _etext) ||
1215 overlap(addr, len, __start_rodata, __end_rodata))
1216 err_printk(dev, NULL, "DMA-API: device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
1219 static void check_sync(struct device *dev,
1220 struct dma_debug_entry *ref,
1223 struct dma_debug_entry *entry;
1224 struct hash_bucket *bucket;
1225 unsigned long flags;
1227 bucket = get_hash_bucket(ref, &flags);
1229 entry = bucket_find_contain(&bucket, ref, &flags);
1232 err_printk(dev, NULL, "DMA-API: device driver tries "
1233 "to sync DMA memory it has not allocated "
1234 "[device address=0x%016llx] [size=%llu bytes]\n",
1235 (unsigned long long)ref->dev_addr, ref->size);
1239 if (ref->size > entry->size) {
1240 err_printk(dev, entry, "DMA-API: device driver syncs"
1241 " DMA memory outside allocated range "
1242 "[device address=0x%016llx] "
1243 "[allocation size=%llu bytes] "
1244 "[sync offset+size=%llu]\n",
1245 entry->dev_addr, entry->size,
1249 if (entry->direction == DMA_BIDIRECTIONAL)
1252 if (ref->direction != entry->direction) {
1253 err_printk(dev, entry, "DMA-API: device driver syncs "
1254 "DMA memory with different direction "
1255 "[device address=0x%016llx] [size=%llu bytes] "
1256 "[mapped with %s] [synced with %s]\n",
1257 (unsigned long long)ref->dev_addr, entry->size,
1258 dir2name[entry->direction],
1259 dir2name[ref->direction]);
1262 if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
1263 !(ref->direction == DMA_TO_DEVICE))
1264 err_printk(dev, entry, "DMA-API: device driver syncs "
1265 "device read-only DMA memory for cpu "
1266 "[device address=0x%016llx] [size=%llu bytes] "
1267 "[mapped with %s] [synced with %s]\n",
1268 (unsigned long long)ref->dev_addr, entry->size,
1269 dir2name[entry->direction],
1270 dir2name[ref->direction]);
1272 if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
1273 !(ref->direction == DMA_FROM_DEVICE))
1274 err_printk(dev, entry, "DMA-API: device driver syncs "
1275 "device write-only DMA memory to device "
1276 "[device address=0x%016llx] [size=%llu bytes] "
1277 "[mapped with %s] [synced with %s]\n",
1278 (unsigned long long)ref->dev_addr, entry->size,
1279 dir2name[entry->direction],
1280 dir2name[ref->direction]);
1282 if (ref->sg_call_ents && ref->type == dma_debug_sg &&
1283 ref->sg_call_ents != entry->sg_call_ents) {
1284 err_printk(ref->dev, entry, "DMA-API: device driver syncs "
1285 "DMA sg list with different entry count "
1286 "[map count=%d] [sync count=%d]\n",
1287 entry->sg_call_ents, ref->sg_call_ents);
1291 put_hash_bucket(bucket, &flags);
1294 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
1295 size_t size, int direction, dma_addr_t dma_addr,
1298 struct dma_debug_entry *entry;
1300 if (unlikely(dma_debug_disabled()))
1303 if (dma_mapping_error(dev, dma_addr))
1306 entry = dma_entry_alloc();
1311 entry->type = dma_debug_page;
1312 entry->pfn = page_to_pfn(page);
1313 entry->offset = offset,
1314 entry->dev_addr = dma_addr;
1316 entry->direction = direction;
1317 entry->map_err_type = MAP_ERR_NOT_CHECKED;
1320 entry->type = dma_debug_single;
1322 check_for_stack(dev, page, offset);
1324 if (!PageHighMem(page)) {
1325 void *addr = page_address(page) + offset;
1327 check_for_illegal_area(dev, addr, size);
1330 add_dma_entry(entry);
1332 EXPORT_SYMBOL(debug_dma_map_page);
1334 void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
1336 struct dma_debug_entry ref;
1337 struct dma_debug_entry *entry;
1338 struct hash_bucket *bucket;
1339 unsigned long flags;
1341 if (unlikely(dma_debug_disabled()))
1345 ref.dev_addr = dma_addr;
1346 bucket = get_hash_bucket(&ref, &flags);
1348 list_for_each_entry(entry, &bucket->list, list) {
1349 if (!exact_match(&ref, entry))
1353 * The same physical address can be mapped multiple
1354 * times. Without a hardware IOMMU this results in the
1355 * same device addresses being put into the dma-debug
1356 * hash multiple times too. This can result in false
1357 * positives being reported. Therefore we implement a
1358 * best-fit algorithm here which updates the first entry
1359 * from the hash which fits the reference value and is
1360 * not currently listed as being checked.
1362 if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1363 entry->map_err_type = MAP_ERR_CHECKED;
1368 put_hash_bucket(bucket, &flags);
1370 EXPORT_SYMBOL(debug_dma_mapping_error);
1372 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
1373 size_t size, int direction, bool map_single)
1375 struct dma_debug_entry ref = {
1376 .type = dma_debug_page,
1380 .direction = direction,
1383 if (unlikely(dma_debug_disabled()))
1387 ref.type = dma_debug_single;
1391 EXPORT_SYMBOL(debug_dma_unmap_page);
1393 void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
1394 int nents, int mapped_ents, int direction)
1396 struct dma_debug_entry *entry;
1397 struct scatterlist *s;
1400 if (unlikely(dma_debug_disabled()))
1403 for_each_sg(sg, s, mapped_ents, i) {
1404 entry = dma_entry_alloc();
1408 entry->type = dma_debug_sg;
1410 entry->pfn = page_to_pfn(sg_page(s));
1411 entry->offset = s->offset,
1412 entry->size = sg_dma_len(s);
1413 entry->dev_addr = sg_dma_address(s);
1414 entry->direction = direction;
1415 entry->sg_call_ents = nents;
1416 entry->sg_mapped_ents = mapped_ents;
1418 check_for_stack(dev, sg_page(s), s->offset);
1420 if (!PageHighMem(sg_page(s))) {
1421 check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
1424 add_dma_entry(entry);
1427 EXPORT_SYMBOL(debug_dma_map_sg);
1429 static int get_nr_mapped_entries(struct device *dev,
1430 struct dma_debug_entry *ref)
1432 struct dma_debug_entry *entry;
1433 struct hash_bucket *bucket;
1434 unsigned long flags;
1437 bucket = get_hash_bucket(ref, &flags);
1438 entry = bucket_find_exact(bucket, ref);
1442 mapped_ents = entry->sg_mapped_ents;
1443 put_hash_bucket(bucket, &flags);
1448 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
1449 int nelems, int dir)
1451 struct scatterlist *s;
1452 int mapped_ents = 0, i;
1454 if (unlikely(dma_debug_disabled()))
1457 for_each_sg(sglist, s, nelems, i) {
1459 struct dma_debug_entry ref = {
1460 .type = dma_debug_sg,
1462 .pfn = page_to_pfn(sg_page(s)),
1463 .offset = s->offset,
1464 .dev_addr = sg_dma_address(s),
1465 .size = sg_dma_len(s),
1467 .sg_call_ents = nelems,
1470 if (mapped_ents && i >= mapped_ents)
1474 mapped_ents = get_nr_mapped_entries(dev, &ref);
1479 EXPORT_SYMBOL(debug_dma_unmap_sg);
1481 void debug_dma_alloc_coherent(struct device *dev, size_t size,
1482 dma_addr_t dma_addr, void *virt)
1484 struct dma_debug_entry *entry;
1486 if (unlikely(dma_debug_disabled()))
1489 if (unlikely(virt == NULL))
1492 entry = dma_entry_alloc();
1496 entry->type = dma_debug_coherent;
1498 entry->pfn = page_to_pfn(virt_to_page(virt));
1499 entry->offset = (size_t) virt & ~PAGE_MASK;
1501 entry->dev_addr = dma_addr;
1502 entry->direction = DMA_BIDIRECTIONAL;
1504 add_dma_entry(entry);
1506 EXPORT_SYMBOL(debug_dma_alloc_coherent);
1508 void debug_dma_free_coherent(struct device *dev, size_t size,
1509 void *virt, dma_addr_t addr)
1511 struct dma_debug_entry ref = {
1512 .type = dma_debug_coherent,
1514 .pfn = page_to_pfn(virt_to_page(virt)),
1515 .offset = (size_t) virt & ~PAGE_MASK,
1518 .direction = DMA_BIDIRECTIONAL,
1521 if (unlikely(dma_debug_disabled()))
1526 EXPORT_SYMBOL(debug_dma_free_coherent);
1528 void debug_dma_map_resource(struct device *dev, phys_addr_t addr, size_t size,
1529 int direction, dma_addr_t dma_addr)
1531 struct dma_debug_entry *entry;
1533 if (unlikely(dma_debug_disabled()))
1536 entry = dma_entry_alloc();
1540 entry->type = dma_debug_resource;
1542 entry->pfn = PHYS_PFN(addr);
1543 entry->offset = offset_in_page(addr);
1545 entry->dev_addr = dma_addr;
1546 entry->direction = direction;
1547 entry->map_err_type = MAP_ERR_NOT_CHECKED;
1549 add_dma_entry(entry);
1551 EXPORT_SYMBOL(debug_dma_map_resource);
1553 void debug_dma_unmap_resource(struct device *dev, dma_addr_t dma_addr,
1554 size_t size, int direction)
1556 struct dma_debug_entry ref = {
1557 .type = dma_debug_resource,
1559 .dev_addr = dma_addr,
1561 .direction = direction,
1564 if (unlikely(dma_debug_disabled()))
1569 EXPORT_SYMBOL(debug_dma_unmap_resource);
1571 void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
1572 size_t size, int direction)
1574 struct dma_debug_entry ref;
1576 if (unlikely(dma_debug_disabled()))
1579 ref.type = dma_debug_single;
1581 ref.dev_addr = dma_handle;
1583 ref.direction = direction;
1584 ref.sg_call_ents = 0;
1586 check_sync(dev, &ref, true);
1588 EXPORT_SYMBOL(debug_dma_sync_single_for_cpu);
1590 void debug_dma_sync_single_for_device(struct device *dev,
1591 dma_addr_t dma_handle, size_t size,
1594 struct dma_debug_entry ref;
1596 if (unlikely(dma_debug_disabled()))
1599 ref.type = dma_debug_single;
1601 ref.dev_addr = dma_handle;
1603 ref.direction = direction;
1604 ref.sg_call_ents = 0;
1606 check_sync(dev, &ref, false);
1608 EXPORT_SYMBOL(debug_dma_sync_single_for_device);
1610 void debug_dma_sync_single_range_for_cpu(struct device *dev,
1611 dma_addr_t dma_handle,
1612 unsigned long offset, size_t size,
1615 struct dma_debug_entry ref;
1617 if (unlikely(dma_debug_disabled()))
1620 ref.type = dma_debug_single;
1622 ref.dev_addr = dma_handle;
1623 ref.size = offset + size;
1624 ref.direction = direction;
1625 ref.sg_call_ents = 0;
1627 check_sync(dev, &ref, true);
1629 EXPORT_SYMBOL(debug_dma_sync_single_range_for_cpu);
1631 void debug_dma_sync_single_range_for_device(struct device *dev,
1632 dma_addr_t dma_handle,
1633 unsigned long offset,
1634 size_t size, int direction)
1636 struct dma_debug_entry ref;
1638 if (unlikely(dma_debug_disabled()))
1641 ref.type = dma_debug_single;
1643 ref.dev_addr = dma_handle;
1644 ref.size = offset + size;
1645 ref.direction = direction;
1646 ref.sg_call_ents = 0;
1648 check_sync(dev, &ref, false);
1650 EXPORT_SYMBOL(debug_dma_sync_single_range_for_device);
1652 void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
1653 int nelems, int direction)
1655 struct scatterlist *s;
1656 int mapped_ents = 0, i;
1658 if (unlikely(dma_debug_disabled()))
1661 for_each_sg(sg, s, nelems, i) {
1663 struct dma_debug_entry ref = {
1664 .type = dma_debug_sg,
1666 .pfn = page_to_pfn(sg_page(s)),
1667 .offset = s->offset,
1668 .dev_addr = sg_dma_address(s),
1669 .size = sg_dma_len(s),
1670 .direction = direction,
1671 .sg_call_ents = nelems,
1675 mapped_ents = get_nr_mapped_entries(dev, &ref);
1677 if (i >= mapped_ents)
1680 check_sync(dev, &ref, true);
1683 EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
1685 void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
1686 int nelems, int direction)
1688 struct scatterlist *s;
1689 int mapped_ents = 0, i;
1691 if (unlikely(dma_debug_disabled()))
1694 for_each_sg(sg, s, nelems, i) {
1696 struct dma_debug_entry ref = {
1697 .type = dma_debug_sg,
1699 .pfn = page_to_pfn(sg_page(s)),
1700 .offset = s->offset,
1701 .dev_addr = sg_dma_address(s),
1702 .size = sg_dma_len(s),
1703 .direction = direction,
1704 .sg_call_ents = nelems,
1707 mapped_ents = get_nr_mapped_entries(dev, &ref);
1709 if (i >= mapped_ents)
1712 check_sync(dev, &ref, false);
1715 EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
1717 static int __init dma_debug_driver_setup(char *str)
1721 for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
1722 current_driver_name[i] = *str;
1727 if (current_driver_name[0])
1728 pr_info("DMA-API: enable driver filter for driver [%s]\n",
1729 current_driver_name);
1734 __setup("dma_debug_driver=", dma_debug_driver_setup);