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/dma-debug.h>
23 #include <linux/spinlock.h>
24 #include <linux/debugfs.h>
25 #include <linux/device.h>
26 #include <linux/types.h>
27 #include <linux/sched.h>
28 #include <linux/list.h>
29 #include <linux/slab.h>
31 #define HASH_SIZE 1024ULL
32 #define HASH_FN_SHIFT 13
33 #define HASH_FN_MASK (HASH_SIZE - 1)
42 struct dma_debug_entry {
43 struct list_head list;
55 struct list_head list;
57 } ____cacheline_aligned_in_smp;
59 /* Hash list to save the allocated dma addresses */
60 static struct hash_bucket dma_entry_hash[HASH_SIZE];
61 /* List of pre-allocated dma_debug_entry's */
62 static LIST_HEAD(free_entries);
63 /* Lock for the list above */
64 static DEFINE_SPINLOCK(free_entries_lock);
66 /* Global disable flag - will be set in case of an error */
67 static bool global_disable __read_mostly;
69 /* Global error count */
70 static u32 error_count;
72 /* Global error show enable*/
73 static u32 show_all_errors __read_mostly;
74 /* Number of errors to show */
75 static u32 show_num_errors = 1;
77 static u32 num_free_entries;
78 static u32 min_free_entries;
80 /* number of preallocated entries requested by kernel cmdline */
81 static u32 req_entries;
83 /* debugfs dentry's for the stuff above */
84 static struct dentry *dma_debug_dent __read_mostly;
85 static struct dentry *global_disable_dent __read_mostly;
86 static struct dentry *error_count_dent __read_mostly;
87 static struct dentry *show_all_errors_dent __read_mostly;
88 static struct dentry *show_num_errors_dent __read_mostly;
89 static struct dentry *num_free_entries_dent __read_mostly;
90 static struct dentry *min_free_entries_dent __read_mostly;
92 static const char *type2name[4] = { "single", "page",
93 "scather-gather", "coherent" };
95 static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
96 "DMA_FROM_DEVICE", "DMA_NONE" };
99 * The access to some variables in this macro is racy. We can't use atomic_t
100 * here because all these variables are exported to debugfs. Some of them even
101 * writeable. This is also the reason why a lock won't help much. But anyway,
102 * the races are no big deal. Here is why:
104 * error_count: the addition is racy, but the worst thing that can happen is
105 * that we don't count some errors
106 * show_num_errors: the subtraction is racy. Also no big deal because in
107 * worst case this will result in one warning more in the
108 * system log than the user configured. This variable is
109 * writeable via debugfs.
111 #define err_printk(dev, format, arg...) do { \
113 if (show_all_errors || show_num_errors > 0) { \
114 WARN(1, "%s %s: " format, \
115 dev_driver_string(dev), \
116 dev_name(dev) , ## arg); \
118 if (!show_all_errors && show_num_errors > 0) \
119 show_num_errors -= 1; \
123 * Hash related functions
125 * Every DMA-API request is saved into a struct dma_debug_entry. To
126 * have quick access to these structs they are stored into a hash.
128 static int hash_fn(struct dma_debug_entry *entry)
131 * Hash function is based on the dma address.
132 * We use bits 20-27 here as the index into the hash
134 return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
138 * Request exclusive access to a hash bucket for a given dma_debug_entry.
140 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
141 unsigned long *flags)
143 int idx = hash_fn(entry);
144 unsigned long __flags;
146 spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
148 return &dma_entry_hash[idx];
152 * Give up exclusive access to the hash bucket
154 static void put_hash_bucket(struct hash_bucket *bucket,
155 unsigned long *flags)
157 unsigned long __flags = *flags;
159 spin_unlock_irqrestore(&bucket->lock, __flags);
163 * Search a given entry in the hash bucket list
165 static struct dma_debug_entry *hash_bucket_find(struct hash_bucket *bucket,
166 struct dma_debug_entry *ref)
168 struct dma_debug_entry *entry;
170 list_for_each_entry(entry, &bucket->list, list) {
171 if ((entry->dev_addr == ref->dev_addr) &&
172 (entry->dev == ref->dev))
180 * Add an entry to a hash bucket
182 static void hash_bucket_add(struct hash_bucket *bucket,
183 struct dma_debug_entry *entry)
185 list_add_tail(&entry->list, &bucket->list);
189 * Remove entry from a hash bucket list
191 static void hash_bucket_del(struct dma_debug_entry *entry)
193 list_del(&entry->list);
197 * Wrapper function for adding an entry to the hash.
198 * This function takes care of locking itself.
200 static void add_dma_entry(struct dma_debug_entry *entry)
202 struct hash_bucket *bucket;
205 bucket = get_hash_bucket(entry, &flags);
206 hash_bucket_add(bucket, entry);
207 put_hash_bucket(bucket, &flags);
210 /* struct dma_entry allocator
212 * The next two functions implement the allocator for
213 * struct dma_debug_entries.
215 static struct dma_debug_entry *dma_entry_alloc(void)
217 struct dma_debug_entry *entry = NULL;
220 spin_lock_irqsave(&free_entries_lock, flags);
222 if (list_empty(&free_entries)) {
223 printk(KERN_ERR "DMA-API: debugging out of memory "
225 global_disable = true;
229 entry = list_entry(free_entries.next, struct dma_debug_entry, list);
230 list_del(&entry->list);
231 memset(entry, 0, sizeof(*entry));
233 num_free_entries -= 1;
234 if (num_free_entries < min_free_entries)
235 min_free_entries = num_free_entries;
238 spin_unlock_irqrestore(&free_entries_lock, flags);
243 static void dma_entry_free(struct dma_debug_entry *entry)
248 * add to beginning of the list - this way the entries are
249 * more likely cache hot when they are reallocated.
251 spin_lock_irqsave(&free_entries_lock, flags);
252 list_add(&entry->list, &free_entries);
253 num_free_entries += 1;
254 spin_unlock_irqrestore(&free_entries_lock, flags);
258 * DMA-API debugging init code
260 * The init code does two things:
261 * 1. Initialize core data structures
262 * 2. Preallocate a given number of dma_debug_entry structs
265 static int prealloc_memory(u32 num_entries)
267 struct dma_debug_entry *entry, *next_entry;
270 for (i = 0; i < num_entries; ++i) {
271 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
275 list_add_tail(&entry->list, &free_entries);
278 num_free_entries = num_entries;
279 min_free_entries = num_entries;
281 printk(KERN_INFO "DMA-API: preallocated %d debug entries\n",
288 list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
289 list_del(&entry->list);
296 static int dma_debug_fs_init(void)
298 dma_debug_dent = debugfs_create_dir("dma-api", NULL);
299 if (!dma_debug_dent) {
300 printk(KERN_ERR "DMA-API: can not create debugfs directory\n");
304 global_disable_dent = debugfs_create_bool("disabled", 0444,
306 (u32 *)&global_disable);
307 if (!global_disable_dent)
310 error_count_dent = debugfs_create_u32("error_count", 0444,
311 dma_debug_dent, &error_count);
312 if (!error_count_dent)
315 show_all_errors_dent = debugfs_create_u32("all_errors", 0644,
318 if (!show_all_errors_dent)
321 show_num_errors_dent = debugfs_create_u32("num_errors", 0644,
324 if (!show_num_errors_dent)
327 num_free_entries_dent = debugfs_create_u32("num_free_entries", 0444,
330 if (!num_free_entries_dent)
333 min_free_entries_dent = debugfs_create_u32("min_free_entries", 0444,
336 if (!min_free_entries_dent)
342 debugfs_remove_recursive(dma_debug_dent);
349 * Let the architectures decide how many entries should be preallocated.
351 void dma_debug_init(u32 num_entries)
358 for (i = 0; i < HASH_SIZE; ++i) {
359 INIT_LIST_HEAD(&dma_entry_hash[i].list);
360 dma_entry_hash[i].lock = SPIN_LOCK_UNLOCKED;
363 if (dma_debug_fs_init() != 0) {
364 printk(KERN_ERR "DMA-API: error creating debugfs entries "
366 global_disable = true;
372 num_entries = req_entries;
374 if (prealloc_memory(num_entries) != 0) {
375 printk(KERN_ERR "DMA-API: debugging out of memory error "
377 global_disable = true;
382 printk(KERN_INFO "DMA-API: debugging enabled by kernel config\n");
385 static __init int dma_debug_cmdline(char *str)
390 if (strncmp(str, "off", 3) == 0) {
391 printk(KERN_INFO "DMA-API: debugging disabled on kernel "
393 global_disable = true;
399 static __init int dma_debug_entries_cmdline(char *str)
406 res = get_option(&str, &req_entries);
414 __setup("dma_debug=", dma_debug_cmdline);
415 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
417 static void check_unmap(struct dma_debug_entry *ref)
419 struct dma_debug_entry *entry;
420 struct hash_bucket *bucket;
423 if (dma_mapping_error(ref->dev, ref->dev_addr))
426 bucket = get_hash_bucket(ref, &flags);
427 entry = hash_bucket_find(bucket, ref);
430 err_printk(ref->dev, "DMA-API: device driver tries "
431 "to free DMA memory it has not allocated "
432 "[device address=0x%016llx] [size=%llu bytes]\n",
433 ref->dev_addr, ref->size);
437 if (ref->size != entry->size) {
438 err_printk(ref->dev, "DMA-API: device driver frees "
439 "DMA memory with different size "
440 "[device address=0x%016llx] [map size=%llu bytes] "
441 "[unmap size=%llu bytes]\n",
442 ref->dev_addr, entry->size, ref->size);
445 if (ref->type != entry->type) {
446 err_printk(ref->dev, "DMA-API: device driver frees "
447 "DMA memory with wrong function "
448 "[device address=0x%016llx] [size=%llu bytes] "
449 "[mapped as %s] [unmapped as %s]\n",
450 ref->dev_addr, ref->size,
451 type2name[entry->type], type2name[ref->type]);
452 } else if ((entry->type == dma_debug_coherent) &&
453 (ref->paddr != entry->paddr)) {
454 err_printk(ref->dev, "DMA-API: device driver frees "
455 "DMA memory with different CPU address "
456 "[device address=0x%016llx] [size=%llu bytes] "
457 "[cpu alloc address=%p] [cpu free address=%p]",
458 ref->dev_addr, ref->size,
459 (void *)entry->paddr, (void *)ref->paddr);
462 if (ref->sg_call_ents && ref->type == dma_debug_sg &&
463 ref->sg_call_ents != entry->sg_call_ents) {
464 err_printk(ref->dev, "DMA-API: device driver frees "
465 "DMA sg list with different entry count "
466 "[map count=%d] [unmap count=%d]\n",
467 entry->sg_call_ents, ref->sg_call_ents);
471 * This may be no bug in reality - but most implementations of the
472 * DMA API don't handle this properly, so check for it here
474 if (ref->direction != entry->direction) {
475 err_printk(ref->dev, "DMA-API: device driver frees "
476 "DMA memory with different direction "
477 "[device address=0x%016llx] [size=%llu bytes] "
478 "[mapped with %s] [unmapped with %s]\n",
479 ref->dev_addr, ref->size,
480 dir2name[entry->direction],
481 dir2name[ref->direction]);
484 hash_bucket_del(entry);
485 dma_entry_free(entry);
488 put_hash_bucket(bucket, &flags);
491 static void check_for_stack(struct device *dev, void *addr)
493 if (object_is_on_stack(addr))
494 err_printk(dev, "DMA-API: device driver maps memory from stack"
495 " [addr=%p]\n", addr);
498 static void check_sync(struct device *dev, dma_addr_t addr,
499 u64 size, u64 offset, int direction, bool to_cpu)
501 struct dma_debug_entry ref = {
505 .direction = direction,
507 struct dma_debug_entry *entry;
508 struct hash_bucket *bucket;
511 bucket = get_hash_bucket(&ref, &flags);
513 entry = hash_bucket_find(bucket, &ref);
516 err_printk(dev, "DMA-API: device driver tries "
517 "to sync DMA memory it has not allocated "
518 "[device address=0x%016llx] [size=%llu bytes]\n",
523 if ((offset + size) > entry->size) {
524 err_printk(dev, "DMA-API: device driver syncs"
525 " DMA memory outside allocated range "
526 "[device address=0x%016llx] "
527 "[allocation size=%llu bytes] [sync offset=%llu] "
528 "[sync size=%llu]\n", entry->dev_addr, entry->size,
532 if (direction != entry->direction) {
533 err_printk(dev, "DMA-API: device driver syncs "
534 "DMA memory with different direction "
535 "[device address=0x%016llx] [size=%llu bytes] "
536 "[mapped with %s] [synced with %s]\n",
538 dir2name[entry->direction],
539 dir2name[direction]);
542 if (entry->direction == DMA_BIDIRECTIONAL)
545 if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
546 !(direction == DMA_TO_DEVICE))
547 err_printk(dev, "DMA-API: device driver syncs "
548 "device read-only DMA memory for cpu "
549 "[device address=0x%016llx] [size=%llu bytes] "
550 "[mapped with %s] [synced with %s]\n",
552 dir2name[entry->direction],
553 dir2name[direction]);
555 if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
556 !(direction == DMA_FROM_DEVICE))
557 err_printk(dev, "DMA-API: device driver syncs "
558 "device write-only DMA memory to device "
559 "[device address=0x%016llx] [size=%llu bytes] "
560 "[mapped with %s] [synced with %s]\n",
562 dir2name[entry->direction],
563 dir2name[direction]);
566 put_hash_bucket(bucket, &flags);
570 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
571 size_t size, int direction, dma_addr_t dma_addr,
574 struct dma_debug_entry *entry;
576 if (unlikely(global_disable))
579 if (unlikely(dma_mapping_error(dev, dma_addr)))
582 entry = dma_entry_alloc();
587 entry->type = dma_debug_page;
588 entry->paddr = page_to_phys(page) + offset;
589 entry->dev_addr = dma_addr;
591 entry->direction = direction;
594 entry->type = dma_debug_single;
595 check_for_stack(dev, page_address(page) + offset);
598 add_dma_entry(entry);
600 EXPORT_SYMBOL(debug_dma_map_page);
602 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
603 size_t size, int direction, bool map_single)
605 struct dma_debug_entry ref = {
606 .type = dma_debug_page,
610 .direction = direction,
613 if (unlikely(global_disable))
617 ref.type = dma_debug_single;
621 EXPORT_SYMBOL(debug_dma_unmap_page);
623 void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
624 int nents, int mapped_ents, int direction)
626 struct dma_debug_entry *entry;
627 struct scatterlist *s;
630 if (unlikely(global_disable))
633 for_each_sg(sg, s, mapped_ents, i) {
634 entry = dma_entry_alloc();
638 entry->type = dma_debug_sg;
640 entry->paddr = sg_phys(s);
641 entry->size = s->length;
642 entry->dev_addr = s->dma_address;
643 entry->direction = direction;
644 entry->sg_call_ents = nents;
645 entry->sg_mapped_ents = mapped_ents;
647 check_for_stack(dev, sg_virt(s));
649 add_dma_entry(entry);
652 EXPORT_SYMBOL(debug_dma_map_sg);
654 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
657 struct dma_debug_entry *entry;
658 struct scatterlist *s;
659 int mapped_ents = 0, i;
662 if (unlikely(global_disable))
665 for_each_sg(sglist, s, nelems, i) {
667 struct dma_debug_entry ref = {
668 .type = dma_debug_sg,
671 .dev_addr = s->dma_address,
677 if (mapped_ents && i >= mapped_ents)
680 if (mapped_ents == 0) {
681 struct hash_bucket *bucket;
682 ref.sg_call_ents = nelems;
683 bucket = get_hash_bucket(&ref, &flags);
684 entry = hash_bucket_find(bucket, &ref);
686 mapped_ents = entry->sg_mapped_ents;
687 put_hash_bucket(bucket, &flags);
693 EXPORT_SYMBOL(debug_dma_unmap_sg);