lib/dma-debug.c

   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/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>
  35
  36 #include <asm/sections.h>
  37
  38 #define HASH_SIZE       1024ULL
  39 #define HASH_FN_SHIFT   13
  40 #define HASH_FN_MASK    (HASH_SIZE - 1)
  41
  42 enum {
  43         dma_debug_single,
  44         dma_debug_page,
  45         dma_debug_sg,
  46         dma_debug_coherent,
  47         dma_debug_resource,
  48 };
  49
  50 enum map_err_types {
  51         MAP_ERR_CHECK_NOT_APPLICABLE,
  52         MAP_ERR_NOT_CHECKED,
  53         MAP_ERR_CHECKED,
  54 };
  55
  56 #define DMA_DEBUG_STACKTRACE_ENTRIES 5
  57
  58 /**
  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
  71  */
  72 struct dma_debug_entry {
  73         struct list_head list;
  74         struct device    *dev;
  75         int              type;
  76         unsigned long    pfn;
  77         size_t           offset;
  78         u64              dev_addr;
  79         u64              size;
  80         int              direction;
  81         int              sg_call_ents;
  82         int              sg_mapped_ents;
  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];
  87 #endif
  88 };
  89
  90 typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *);
  91
  92 struct hash_bucket {
  93         struct list_head list;
  94         spinlock_t lock;
  95 } ____cacheline_aligned_in_smp;
  96
  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);
 103
 104 /* Global disable flag - will be set in case of an error */
 105 static bool global_disable __read_mostly;
 106
 107 /* Early initialization disable flag, set at the end of dma_debug_init */
 108 static bool dma_debug_initialized __read_mostly;
 109
 110 static inline bool dma_debug_disabled(void)
 111 {
 112         return global_disable || !dma_debug_initialized;
 113 }
 114
 115 /* Global error count */
 116 static u32 error_count;
 117
 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;
 122
 123 static u32 num_free_entries;
 124 static u32 min_free_entries;
 125 static u32 nr_total_entries;
 126
 127 /* number of preallocated entries requested by kernel cmdline */
 128 static u32 req_entries;
 129
 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;
 139
 140 /* per-driver filter related state */
 141
 142 #define NAME_MAX_LEN    64
 143
 144 static char                  current_driver_name[NAME_MAX_LEN] __read_mostly;
 145 static struct device_driver *current_driver                    __read_mostly;
 146
 147 static DEFINE_RWLOCK(driver_name_lock);
 148
 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",
 153 };
 154
 155 static const char *type2name[5] = { "single", "page",
 156                                     "scather-gather", "coherent",
 157                                     "resource" };
 158
 159 static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
 160                                    "DMA_FROM_DEVICE", "DMA_NONE" };
 161
 162 /*
 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:
 167  *
 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.
 174  */
 175 static inline void dump_entry_trace(struct dma_debug_entry *entry)
 176 {
 177 #ifdef CONFIG_STACKTRACE
 178         if (entry) {
 179                 pr_warning("Mapped at:\n");
 180                 print_stack_trace(&entry->stacktrace, 0);
 181         }
 182 #endif
 183 }
 184
 185 static bool driver_filter(struct device *dev)
 186 {
 187         struct device_driver *drv;
 188         unsigned long flags;
 189         bool ret;
 190
 191         /* driver filter off */
 192         if (likely(!current_driver_name[0]))
 193                 return true;
 194
 195         /* driver filter on and initialized */
 196         if (current_driver && dev && dev->driver == current_driver)
 197                 return true;
 198
 199         /* driver filter on, but we can't filter on a NULL device... */
 200         if (!dev)
 201                 return false;
 202
 203         if (current_driver || !current_driver_name[0])
 204                 return false;
 205
 206         /* driver filter on but not yet initialized */
 207         drv = dev->driver;
 208         if (!drv)
 209                 return false;
 210
 211         /* lock to protect against change of current_driver_name */
 212         read_lock_irqsave(&driver_name_lock, flags);
 213
 214         ret = false;
 215         if (drv->name &&
 216             strncmp(current_driver_name, drv->name, NAME_MAX_LEN - 1) == 0) {
 217                 current_driver = drv;
 218                 ret = true;
 219         }
 220
 221         read_unlock_irqrestore(&driver_name_lock, flags);
 222
 223         return ret;
 224 }
 225
 226 #define err_printk(dev, entry, format, arg...) do {                     \
 227                 error_count += 1;                                       \
 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);                        \
 234                 }                                                       \
 235                 if (!show_all_errors && show_num_errors > 0)            \
 236                         show_num_errors -= 1;                           \
 237         } while (0);
 238
 239 /*
 240  * Hash related functions
 241  *
 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.
 244  */
 245 static int hash_fn(struct dma_debug_entry *entry)
 246 {
 247         /*
 248          * Hash function is based on the dma address.
 249          * We use bits 20-27 here as the index into the hash
 250          */
 251         return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
 252 }
 253
 254 /*
 255  * Request exclusive access to a hash bucket for a given dma_debug_entry.
 256  */
 257 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
 258                                            unsigned long *flags)
 259         __acquires(&dma_entry_hash[idx].lock)
 260 {
 261         int idx = hash_fn(entry);
 262         unsigned long __flags;
 263
 264         spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
 265         *flags = __flags;
 266         return &dma_entry_hash[idx];
 267 }
 268
 269 /*
 270  * Give up exclusive access to the hash bucket
 271  */
 272 static void put_hash_bucket(struct hash_bucket *bucket,
 273                             unsigned long *flags)
 274         __releases(&bucket->lock)
 275 {
 276         unsigned long __flags = *flags;
 277
 278         spin_unlock_irqrestore(&bucket->lock, __flags);
 279 }
 280
 281 static bool exact_match(struct dma_debug_entry *a, struct dma_debug_entry *b)
 282 {
 283         return ((a->dev_addr == b->dev_addr) &&
 284                 (a->dev == b->dev)) ? true : false;
 285 }
 286
 287 static bool containing_match(struct dma_debug_entry *a,
 288                              struct dma_debug_entry *b)
 289 {
 290         if (a->dev != b->dev)
 291                 return false;
 292
 293         if ((b->dev_addr <= a->dev_addr) &&
 294             ((b->dev_addr + b->size) >= (a->dev_addr + a->size)))
 295                 return true;
 296
 297         return false;
 298 }
 299
 300 /*
 301  * Search a given entry in the hash bucket list
 302  */
 303 static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
 304                                                   struct dma_debug_entry *ref,
 305                                                   match_fn match)
 306 {
 307         struct dma_debug_entry *entry, *ret = NULL;
 308         int matches = 0, match_lvl, last_lvl = -1;
 309
 310         list_for_each_entry(entry, &bucket->list, list) {
 311                 if (!match(ref, entry))
 312                         continue;
 313
 314                 /*
 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.
 323                  */
 324                 matches += 1;
 325                 match_lvl = 0;
 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;
 330
 331                 if (match_lvl == 4) {
 332                         /* perfect-fit - return the result */
 333                         return entry;
 334                 } else if (match_lvl > last_lvl) {
 335                         /*
 336                          * We found an entry that fits better then the
 337                          * previous one or it is the 1st match.
 338                          */
 339                         last_lvl = match_lvl;
 340                         ret      = entry;
 341                 }
 342         }
 343
 344         /*
 345          * If we have multiple matches but no perfect-fit, just return
 346          * NULL.
 347          */
 348         ret = (matches == 1) ? ret : NULL;
 349
 350         return ret;
 351 }
 352
 353 static struct dma_debug_entry *bucket_find_exact(struct hash_bucket *bucket,
 354                                                  struct dma_debug_entry *ref)
 355 {
 356         return __hash_bucket_find(bucket, ref, exact_match);
 357 }
 358
 359 static struct dma_debug_entry *bucket_find_contain(struct hash_bucket **bucket,
 360                                                    struct dma_debug_entry *ref,
 361                                                    unsigned long *flags)
 362 {
 363
 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;
 367
 368         while (range <= max_range) {
 369                 entry = __hash_bucket_find(*bucket, ref, containing_match);
 370
 371                 if (entry)
 372                         return entry;
 373
 374                 /*
 375                  * Nothing found, go back a hash bucket
 376                  */
 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);
 381         }
 382
 383         return NULL;
 384 }
 385
 386 /*
 387  * Add an entry to a hash bucket
 388  */
 389 static void hash_bucket_add(struct hash_bucket *bucket,
 390                             struct dma_debug_entry *entry)
 391 {
 392         list_add_tail(&entry->list, &bucket->list);
 393 }
 394
 395 /*
 396  * Remove entry from a hash bucket list
 397  */
 398 static void hash_bucket_del(struct dma_debug_entry *entry)
 399 {
 400         list_del(&entry->list);
 401 }
 402
 403 static unsigned long long phys_addr(struct dma_debug_entry *entry)
 404 {
 405         if (entry->type == dma_debug_resource)
 406                 return __pfn_to_phys(entry->pfn) + entry->offset;
 407
 408         return page_to_phys(pfn_to_page(entry->pfn)) + entry->offset;
 409 }
 410
 411 /*
 412  * Dump mapping entries for debugging purposes
 413  */
 414 void debug_dma_dump_mappings(struct device *dev)
 415 {
 416         int idx;
 417
 418         for (idx = 0; idx < HASH_SIZE; idx++) {
 419                 struct hash_bucket *bucket = &dma_entry_hash[idx];
 420                 struct dma_debug_entry *entry;
 421                 unsigned long flags;
 422
 423                 spin_lock_irqsave(&bucket->lock, flags);
 424
 425                 list_for_each_entry(entry, &bucket->list, list) {
 426                         if (!dev || dev == entry->dev) {
 427                                 dev_info(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]);
 434                         }
 435                 }
 436
 437                 spin_unlock_irqrestore(&bucket->lock, flags);
 438         }
 439 }
 440 EXPORT_SYMBOL(debug_dma_dump_mappings);
 441
 442 /*
 443  * For each mapping (initial cacheline in the case of
 444  * dma_alloc_coherent/dma_map_page, initial cacheline in each page of a
 445  * scatterlist, or the cacheline specified in dma_map_single) insert
 446  * into this tree using the cacheline as the key. At
 447  * dma_unmap_{single|sg|page} or dma_free_coherent delete the entry.  If
 448  * the entry already exists at insertion time add a tag as a reference
 449  * count for the overlapping mappings.  For now, the overlap tracking
 450  * just ensures that 'unmaps' balance 'maps' before marking the
 451  * cacheline idle, but we should also be flagging overlaps as an API
 452  * violation.
 453  *
 454  * Memory usage is mostly constrained by the maximum number of available
 455  * dma-debug entries in that we need a free dma_debug_entry before
 456  * inserting into the tree.  In the case of dma_map_page and
 457  * dma_alloc_coherent there is only one dma_debug_entry and one
 458  * dma_active_cacheline entry to track per event.  dma_map_sg(), on the
 459  * other hand, consumes a single dma_debug_entry, but inserts 'nents'
 460  * entries into the tree.
 461  *
 462  * At any time debug_dma_assert_idle() can be called to trigger a
 463  * warning if any cachelines in the given page are in the active set.
 464  */
 465 static RADIX_TREE(dma_active_cacheline, GFP_NOWAIT);
 466 static DEFINE_SPINLOCK(radix_lock);
 467 #define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1)
 468 #define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT)
 469 #define CACHELINES_PER_PAGE (1 << CACHELINE_PER_PAGE_SHIFT)
 470
 471 static phys_addr_t to_cacheline_number(struct dma_debug_entry *entry)
 472 {
 473         return (entry->pfn << CACHELINE_PER_PAGE_SHIFT) +
 474                 (entry->offset >> L1_CACHE_SHIFT);
 475 }
 476
 477 static int active_cacheline_read_overlap(phys_addr_t cln)
 478 {
 479         int overlap = 0, i;
 480
 481         for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
 482                 if (radix_tree_tag_get(&dma_active_cacheline, cln, i))
 483                         overlap |= 1 << i;
 484         return overlap;
 485 }
 486
 487 static int active_cacheline_set_overlap(phys_addr_t cln, int overlap)
 488 {
 489         int i;
 490
 491         if (overlap > ACTIVE_CACHELINE_MAX_OVERLAP || overlap < 0)
 492                 return overlap;
 493
 494         for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
 495                 if (overlap & 1 << i)
 496                         radix_tree_tag_set(&dma_active_cacheline, cln, i);
 497                 else
 498                         radix_tree_tag_clear(&dma_active_cacheline, cln, i);
 499
 500         return overlap;
 501 }
 502
 503 static void active_cacheline_inc_overlap(phys_addr_t cln)
 504 {
 505         int overlap = active_cacheline_read_overlap(cln);
 506
 507         overlap = active_cacheline_set_overlap(cln, ++overlap);
 508
 509         /* If we overflowed the overlap counter then we're potentially
 510          * leaking dma-mappings.  Otherwise, if maps and unmaps are
 511          * balanced then this overflow may cause false negatives in
 512          * debug_dma_assert_idle() as the cacheline may be marked idle
 513          * prematurely.
 514          */
 515         WARN_ONCE(overlap > ACTIVE_CACHELINE_MAX_OVERLAP,
 516                   "DMA-API: exceeded %d overlapping mappings of cacheline %pa\n",
 517                   ACTIVE_CACHELINE_MAX_OVERLAP, &cln);
 518 }
 519
 520 static int active_cacheline_dec_overlap(phys_addr_t cln)
 521 {
 522         int overlap = active_cacheline_read_overlap(cln);
 523
 524         return active_cacheline_set_overlap(cln, --overlap);
 525 }
 526
 527 static int active_cacheline_insert(struct dma_debug_entry *entry)
 528 {
 529         phys_addr_t cln = to_cacheline_number(entry);
 530         unsigned long flags;
 531         int rc;
 532
 533         /* If the device is not writing memory then we don't have any
 534          * concerns about the cpu consuming stale data.  This mitigates
 535          * legitimate usages of overlapping mappings.
 536          */
 537         if (entry->direction == DMA_TO_DEVICE)
 538                 return 0;
 539
 540         spin_lock_irqsave(&radix_lock, flags);
 541         rc = radix_tree_insert(&dma_active_cacheline, cln, entry);
 542         if (rc == -EEXIST)
 543                 active_cacheline_inc_overlap(cln);
 544         spin_unlock_irqrestore(&radix_lock, flags);
 545
 546         return rc;
 547 }
 548
 549 static void active_cacheline_remove(struct dma_debug_entry *entry)
 550 {
 551         phys_addr_t cln = to_cacheline_number(entry);
 552         unsigned long flags;
 553
 554         /* ...mirror the insert case */
 555         if (entry->direction == DMA_TO_DEVICE)
 556                 return;
 557
 558         spin_lock_irqsave(&radix_lock, flags);
 559         /* since we are counting overlaps the final put of the
 560          * cacheline will occur when the overlap count is 0.
 561          * active_cacheline_dec_overlap() returns -1 in that case
 562          */
 563         if (active_cacheline_dec_overlap(cln) < 0)
 564                 radix_tree_delete(&dma_active_cacheline, cln);
 565         spin_unlock_irqrestore(&radix_lock, flags);
 566 }
 567
 568 /**
 569  * debug_dma_assert_idle() - assert that a page is not undergoing dma
 570  * @page: page to lookup in the dma_active_cacheline tree
 571  *
 572  * Place a call to this routine in cases where the cpu touching the page
 573  * before the dma completes (page is dma_unmapped) will lead to data
 574  * corruption.
 575  */
 576 void debug_dma_assert_idle(struct page *page)
 577 {
 578         static struct dma_debug_entry *ents[CACHELINES_PER_PAGE];
 579         struct dma_debug_entry *entry = NULL;
 580         void **results = (void **) &ents;
 581         unsigned int nents, i;
 582         unsigned long flags;
 583         phys_addr_t cln;
 584
 585         if (dma_debug_disabled())
 586                 return;
 587
 588         if (!page)
 589                 return;
 590
 591         cln = (phys_addr_t) page_to_pfn(page) << CACHELINE_PER_PAGE_SHIFT;
 592         spin_lock_irqsave(&radix_lock, flags);
 593         nents = radix_tree_gang_lookup(&dma_active_cacheline, results, cln,
 594                                        CACHELINES_PER_PAGE);
 595         for (i = 0; i < nents; i++) {
 596                 phys_addr_t ent_cln = to_cacheline_number(ents[i]);
 597
 598                 if (ent_cln == cln) {
 599                         entry = ents[i];
 600                         break;
 601                 } else if (ent_cln >= cln + CACHELINES_PER_PAGE)
 602                         break;
 603         }
 604         spin_unlock_irqrestore(&radix_lock, flags);
 605
 606         if (!entry)
 607                 return;
 608
 609         cln = to_cacheline_number(entry);
 610         err_printk(entry->dev, entry,
 611                    "DMA-API: cpu touching an active dma mapped cacheline [cln=%pa]\n",
 612                    &cln);
 613 }
 614
 615 /*
 616  * Wrapper function for adding an entry to the hash.
 617  * This function takes care of locking itself.
 618  */
 619 static void add_dma_entry(struct dma_debug_entry *entry)
 620 {
 621         struct hash_bucket *bucket;
 622         unsigned long flags;
 623         int rc;
 624
 625         bucket = get_hash_bucket(entry, &flags);
 626         hash_bucket_add(bucket, entry);
 627         put_hash_bucket(bucket, &flags);
 628
 629         rc = active_cacheline_insert(entry);
 630         if (rc == -ENOMEM) {
 631                 pr_err("DMA-API: cacheline tracking ENOMEM, dma-debug disabled\n");
 632                 global_disable = true;
 633         }
 634
 635         /* TODO: report -EEXIST errors here as overlapping mappings are
 636          * not supported by the DMA API
 637          */
 638 }
 639
 640 static struct dma_debug_entry *__dma_entry_alloc(void)
 641 {
 642         struct dma_debug_entry *entry;
 643
 644         entry = list_entry(free_entries.next, struct dma_debug_entry, list);
 645         list_del(&entry->list);
 646         memset(entry, 0, sizeof(*entry));
 647
 648         num_free_entries -= 1;
 649         if (num_free_entries < min_free_entries)
 650                 min_free_entries = num_free_entries;
 651
 652         return entry;
 653 }
 654
 655 /* struct dma_entry allocator
 656  *
 657  * The next two functions implement the allocator for
 658  * struct dma_debug_entries.
 659  */
 660 static struct dma_debug_entry *dma_entry_alloc(void)
 661 {
 662         struct dma_debug_entry *entry;
 663         unsigned long flags;
 664
 665         spin_lock_irqsave(&free_entries_lock, flags);
 666
 667         if (list_empty(&free_entries)) {
 668                 global_disable = true;
 669                 spin_unlock_irqrestore(&free_entries_lock, flags);
 670                 pr_err("DMA-API: debugging out of memory - disabling\n");
 671                 return NULL;
 672         }
 673
 674         entry = __dma_entry_alloc();
 675
 676         spin_unlock_irqrestore(&free_entries_lock, flags);
 677
 678 #ifdef CONFIG_STACKTRACE
 679         entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES;
 680         entry->stacktrace.entries = entry->st_entries;
 681         entry->stacktrace.skip = 2;
 682         save_stack_trace(&entry->stacktrace);
 683 #endif
 684
 685         return entry;
 686 }
 687
 688 static void dma_entry_free(struct dma_debug_entry *entry)
 689 {
 690         unsigned long flags;
 691
 692         active_cacheline_remove(entry);
 693
 694         /*
 695          * add to beginning of the list - this way the entries are
 696          * more likely cache hot when they are reallocated.
 697          */
 698         spin_lock_irqsave(&free_entries_lock, flags);
 699         list_add(&entry->list, &free_entries);
 700         num_free_entries += 1;
 701         spin_unlock_irqrestore(&free_entries_lock, flags);
 702 }
 703
 704 int dma_debug_resize_entries(u32 num_entries)
 705 {
 706         int i, delta, ret = 0;
 707         unsigned long flags;
 708         struct dma_debug_entry *entry;
 709         LIST_HEAD(tmp);
 710
 711         spin_lock_irqsave(&free_entries_lock, flags);
 712
 713         if (nr_total_entries < num_entries) {
 714                 delta = num_entries - nr_total_entries;
 715
 716                 spin_unlock_irqrestore(&free_entries_lock, flags);
 717
 718                 for (i = 0; i < delta; i++) {
 719                         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 720                         if (!entry)
 721                                 break;
 722
 723                         list_add_tail(&entry->list, &tmp);
 724                 }
 725
 726                 spin_lock_irqsave(&free_entries_lock, flags);
 727
 728                 list_splice(&tmp, &free_entries);
 729                 nr_total_entries += i;
 730                 num_free_entries += i;
 731         } else {
 732                 delta = nr_total_entries - num_entries;
 733
 734                 for (i = 0; i < delta && !list_empty(&free_entries); i++) {
 735                         entry = __dma_entry_alloc();
 736                         kfree(entry);
 737                 }
 738
 739                 nr_total_entries -= i;
 740         }
 741
 742         if (nr_total_entries != num_entries)
 743                 ret = 1;
 744
 745         spin_unlock_irqrestore(&free_entries_lock, flags);
 746
 747         return ret;
 748 }
 749 EXPORT_SYMBOL(dma_debug_resize_entries);
 750
 751 /*
 752  * DMA-API debugging init code
 753  *
 754  * The init code does two things:
 755  *   1. Initialize core data structures
 756  *   2. Preallocate a given number of dma_debug_entry structs
 757  */
 758
 759 static int prealloc_memory(u32 num_entries)
 760 {
 761         struct dma_debug_entry *entry, *next_entry;
 762         int i;
 763
 764         for (i = 0; i < num_entries; ++i) {
 765                 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 766                 if (!entry)
 767                         goto out_err;
 768
 769                 list_add_tail(&entry->list, &free_entries);
 770         }
 771
 772         num_free_entries = num_entries;
 773         min_free_entries = num_entries;
 774
 775         pr_info("DMA-API: preallocated %d debug entries\n", num_entries);
 776
 777         return 0;
 778
 779 out_err:
 780
 781         list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
 782                 list_del(&entry->list);
 783                 kfree(entry);
 784         }
 785
 786         return -ENOMEM;
 787 }
 788
 789 static ssize_t filter_read(struct file *file, char __user *user_buf,
 790                            size_t count, loff_t *ppos)
 791 {
 792         char buf[NAME_MAX_LEN + 1];
 793         unsigned long flags;
 794         int len;
 795
 796         if (!current_driver_name[0])
 797                 return 0;
 798
 799         /*
 800          * We can't copy to userspace directly because current_driver_name can
 801          * only be read under the driver_name_lock with irqs disabled. So
 802          * create a temporary copy first.
 803          */
 804         read_lock_irqsave(&driver_name_lock, flags);
 805         len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
 806         read_unlock_irqrestore(&driver_name_lock, flags);
 807
 808         return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 809 }
 810
 811 static ssize_t filter_write(struct file *file, const char __user *userbuf,
 812                             size_t count, loff_t *ppos)
 813 {
 814         char buf[NAME_MAX_LEN];
 815         unsigned long flags;
 816         size_t len;
 817         int i;
 818
 819         /*
 820          * We can't copy from userspace directly. Access to
 821          * current_driver_name is protected with a write_lock with irqs
 822          * disabled. Since copy_from_user can fault and may sleep we
 823          * need to copy to temporary buffer first
 824          */
 825         len = min(count, (size_t)(NAME_MAX_LEN - 1));
 826         if (copy_from_user(buf, userbuf, len))
 827                 return -EFAULT;
 828
 829         buf[len] = 0;
 830
 831         write_lock_irqsave(&driver_name_lock, flags);
 832
 833         /*
 834          * Now handle the string we got from userspace very carefully.
 835          * The rules are:
 836          *         - only use the first token we got
 837          *         - token delimiter is everything looking like a space
 838          *           character (' ', '\n', '\t' ...)
 839          *
 840          */
 841         if (!isalnum(buf[0])) {
 842                 /*
 843                  * If the first character userspace gave us is not
 844                  * alphanumerical then assume the filter should be
 845                  * switched off.
 846                  */
 847                 if (current_driver_name[0])
 848                         pr_info("DMA-API: switching off dma-debug driver filter\n");
 849                 current_driver_name[0] = 0;
 850                 current_driver = NULL;
 851                 goto out_unlock;
 852         }
 853
 854         /*
 855          * Now parse out the first token and use it as the name for the
 856          * driver to filter for.
 857          */
 858         for (i = 0; i < NAME_MAX_LEN - 1; ++i) {
 859                 current_driver_name[i] = buf[i];
 860                 if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
 861                         break;
 862         }
 863         current_driver_name[i] = 0;
 864         current_driver = NULL;
 865
 866         pr_info("DMA-API: enable driver filter for driver [%s]\n",
 867                 current_driver_name);
 868
 869 out_unlock:
 870         write_unlock_irqrestore(&driver_name_lock, flags);
 871
 872         return count;
 873 }
 874
 875 static const struct file_operations filter_fops = {
 876         .read  = filter_read,
 877         .write = filter_write,
 878         .llseek = default_llseek,
 879 };
 880
 881 static int dma_debug_fs_init(void)
 882 {
 883         dma_debug_dent = debugfs_create_dir("dma-api", NULL);
 884         if (!dma_debug_dent) {
 885                 pr_err("DMA-API: can not create debugfs directory\n");
 886                 return -ENOMEM;
 887         }
 888
 889         global_disable_dent = debugfs_create_bool("disabled", 0444,
 890                         dma_debug_dent,
 891                         &global_disable);
 892         if (!global_disable_dent)
 893                 goto out_err;
 894
 895         error_count_dent = debugfs_create_u32("error_count", 0444,
 896                         dma_debug_dent, &error_count);
 897         if (!error_count_dent)
 898                 goto out_err;
 899
 900         show_all_errors_dent = debugfs_create_u32("all_errors", 0644,
 901                         dma_debug_dent,
 902                         &show_all_errors);
 903         if (!show_all_errors_dent)
 904                 goto out_err;
 905
 906         show_num_errors_dent = debugfs_create_u32("num_errors", 0644,
 907                         dma_debug_dent,
 908                         &show_num_errors);
 909         if (!show_num_errors_dent)
 910                 goto out_err;
 911
 912         num_free_entries_dent = debugfs_create_u32("num_free_entries", 0444,
 913                         dma_debug_dent,
 914                         &num_free_entries);
 915         if (!num_free_entries_dent)
 916                 goto out_err;
 917
 918         min_free_entries_dent = debugfs_create_u32("min_free_entries", 0444,
 919                         dma_debug_dent,
 920                         &min_free_entries);
 921         if (!min_free_entries_dent)
 922                 goto out_err;
 923
 924         filter_dent = debugfs_create_file("driver_filter", 0644,
 925                                           dma_debug_dent, NULL, &filter_fops);
 926         if (!filter_dent)
 927                 goto out_err;
 928
 929         return 0;
 930
 931 out_err:
 932         debugfs_remove_recursive(dma_debug_dent);
 933
 934         return -ENOMEM;
 935 }
 936
 937 static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry)
 938 {
 939         struct dma_debug_entry *entry;
 940         unsigned long flags;
 941         int count = 0, i;
 942
 943         local_irq_save(flags);
 944
 945         for (i = 0; i < HASH_SIZE; ++i) {
 946                 spin_lock(&dma_entry_hash[i].lock);
 947                 list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
 948                         if (entry->dev == dev) {
 949                                 count += 1;
 950                                 *out_entry = entry;
 951                         }
 952                 }
 953                 spin_unlock(&dma_entry_hash[i].lock);
 954         }
 955
 956         local_irq_restore(flags);
 957
 958         return count;
 959 }
 960
 961 static int dma_debug_device_change(struct notifier_block *nb, unsigned long action, void *data)
 962 {
 963         struct device *dev = data;
 964         struct dma_debug_entry *uninitialized_var(entry);
 965         int count;
 966
 967         if (dma_debug_disabled())
 968                 return 0;
 969
 970         switch (action) {
 971         case BUS_NOTIFY_UNBOUND_DRIVER:
 972                 count = device_dma_allocations(dev, &entry);
 973                 if (count == 0)
 974                         break;
 975                 err_printk(dev, entry, "DMA-API: device driver has pending "
 976                                 "DMA allocations while released from device "
 977                                 "[count=%d]\n"
 978                                 "One of leaked entries details: "
 979                                 "[device address=0x%016llx] [size=%llu bytes] "
 980                                 "[mapped with %s] [mapped as %s]\n",
 981                         count, entry->dev_addr, entry->size,
 982                         dir2name[entry->direction], type2name[entry->type]);
 983                 break;
 984         default:
 985                 break;
 986         }
 987
 988         return 0;
 989 }
 990
 991 void dma_debug_add_bus(struct bus_type *bus)
 992 {
 993         struct notifier_block *nb;
 994
 995         if (dma_debug_disabled())
 996                 return;
 997
 998         nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
 999         if (nb == NULL) {
1000                 pr_err("dma_debug_add_bus: out of memory\n");
1001                 return;
1002         }
1003
1004         nb->notifier_call = dma_debug_device_change;
1005
1006         bus_register_notifier(bus, nb);
1007 }
1008
1009 /*
1010  * Let the architectures decide how many entries should be preallocated.
1011  */
1012 void dma_debug_init(u32 num_entries)
1013 {
1014         int i;
1015
1016         /* Do not use dma_debug_initialized here, since we really want to be
1017          * called to set dma_debug_initialized
1018          */
1019         if (global_disable)
1020                 return;
1021
1022         for (i = 0; i < HASH_SIZE; ++i) {
1023                 INIT_LIST_HEAD(&dma_entry_hash[i].list);
1024                 spin_lock_init(&dma_entry_hash[i].lock);
1025         }
1026
1027         if (dma_debug_fs_init() != 0) {
1028                 pr_err("DMA-API: error creating debugfs entries - disabling\n");
1029                 global_disable = true;
1030
1031                 return;
1032         }
1033
1034         if (req_entries)
1035                 num_entries = req_entries;
1036
1037         if (prealloc_memory(num_entries) != 0) {
1038                 pr_err("DMA-API: debugging out of memory error - disabled\n");
1039                 global_disable = true;
1040
1041                 return;
1042         }
1043
1044         nr_total_entries = num_free_entries;
1045
1046         dma_debug_initialized = true;
1047
1048         pr_info("DMA-API: debugging enabled by kernel config\n");
1049 }
1050
1051 static __init int dma_debug_cmdline(char *str)
1052 {
1053         if (!str)
1054                 return -EINVAL;
1055
1056         if (strncmp(str, "off", 3) == 0) {
1057                 pr_info("DMA-API: debugging disabled on kernel command line\n");
1058                 global_disable = true;
1059         }
1060
1061         return 0;
1062 }
1063
1064 static __init int dma_debug_entries_cmdline(char *str)
1065 {
1066         int res;
1067
1068         if (!str)
1069                 return -EINVAL;
1070
1071         res = get_option(&str, &req_entries);
1072
1073         if (!res)
1074                 req_entries = 0;
1075
1076         return 0;
1077 }
1078
1079 __setup("dma_debug=", dma_debug_cmdline);
1080 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
1081
1082 static void check_unmap(struct dma_debug_entry *ref)
1083 {
1084         struct dma_debug_entry *entry;
1085         struct hash_bucket *bucket;
1086         unsigned long flags;
1087
1088         bucket = get_hash_bucket(ref, &flags);
1089         entry = bucket_find_exact(bucket, ref);
1090
1091         if (!entry) {
1092                 /* must drop lock before calling dma_mapping_error */
1093                 put_hash_bucket(bucket, &flags);
1094
1095                 if (dma_mapping_error(ref->dev, ref->dev_addr)) {
1096                         err_printk(ref->dev, NULL,
1097                                    "DMA-API: device driver tries to free an "
1098                                    "invalid DMA memory address\n");
1099                 } else {
1100                         err_printk(ref->dev, NULL,
1101                                    "DMA-API: device driver tries to free DMA "
1102                                    "memory it has not allocated [device "
1103                                    "address=0x%016llx] [size=%llu bytes]\n",
1104                                    ref->dev_addr, ref->size);
1105                 }
1106                 return;
1107         }
1108
1109         if (ref->size != entry->size) {
1110                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1111                            "DMA memory with different size "
1112                            "[device address=0x%016llx] [map size=%llu bytes] "
1113                            "[unmap size=%llu bytes]\n",
1114                            ref->dev_addr, entry->size, ref->size);
1115         }
1116
1117         if (ref->type != entry->type) {
1118                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1119                            "DMA memory with wrong function "
1120                            "[device address=0x%016llx] [size=%llu bytes] "
1121                            "[mapped as %s] [unmapped as %s]\n",
1122                            ref->dev_addr, ref->size,
1123                            type2name[entry->type], type2name[ref->type]);
1124         } else if ((entry->type == dma_debug_coherent) &&
1125                    (phys_addr(ref) != phys_addr(entry))) {
1126                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1127                            "DMA memory with different CPU address "
1128                            "[device address=0x%016llx] [size=%llu bytes] "
1129                            "[cpu alloc address=0x%016llx] "
1130                            "[cpu free address=0x%016llx]",
1131                            ref->dev_addr, ref->size,
1132                            phys_addr(entry),
1133                            phys_addr(ref));
1134         }
1135
1136         if (ref->sg_call_ents && ref->type == dma_debug_sg &&
1137             ref->sg_call_ents != entry->sg_call_ents) {
1138                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1139                            "DMA sg list with different entry count "
1140                            "[map count=%d] [unmap count=%d]\n",
1141                            entry->sg_call_ents, ref->sg_call_ents);
1142         }
1143
1144         /*
1145          * This may be no bug in reality - but most implementations of the
1146          * DMA API don't handle this properly, so check for it here
1147          */
1148         if (ref->direction != entry->direction) {
1149                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1150                            "DMA memory with different direction "
1151                            "[device address=0x%016llx] [size=%llu bytes] "
1152                            "[mapped with %s] [unmapped with %s]\n",
1153                            ref->dev_addr, ref->size,
1154                            dir2name[entry->direction],
1155                            dir2name[ref->direction]);
1156         }
1157
1158         if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1159                 err_printk(ref->dev, entry,
1160                            "DMA-API: device driver failed to check map error"
1161                            "[device address=0x%016llx] [size=%llu bytes] "
1162                            "[mapped as %s]",
1163                            ref->dev_addr, ref->size,
1164                            type2name[entry->type]);
1165         }
1166
1167         hash_bucket_del(entry);
1168         dma_entry_free(entry);
1169
1170         put_hash_bucket(bucket, &flags);
1171 }
1172
1173 static void check_for_stack(struct device *dev,
1174                             struct page *page, size_t offset)
1175 {
1176         void *addr;
1177         struct vm_struct *stack_vm_area = task_stack_vm_area(current);
1178
1179         if (!stack_vm_area) {
1180                 /* Stack is direct-mapped. */
1181                 if (PageHighMem(page))
1182                         return;
1183                 addr = page_address(page) + offset;
1184                 if (object_is_on_stack(addr))
1185                         err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [addr=%p]\n", addr);
1186         } else {
1187                 /* Stack is vmalloced. */
1188                 int i;
1189
1190                 for (i = 0; i < stack_vm_area->nr_pages; i++) {
1191                         if (page != stack_vm_area->pages[i])
1192                                 continue;
1193
1194                         addr = (u8 *)current->stack + i * PAGE_SIZE + offset;
1195                         err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [probable addr=%p]\n", addr);
1196                         break;
1197                 }
1198         }
1199 }
1200
1201 static inline bool overlap(void *addr, unsigned long len, void *start, void *end)
1202 {
1203         unsigned long a1 = (unsigned long)addr;
1204         unsigned long b1 = a1 + len;
1205         unsigned long a2 = (unsigned long)start;
1206         unsigned long b2 = (unsigned long)end;
1207
1208         return !(b1 <= a2 || a1 >= b2);
1209 }
1210
1211 static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
1212 {
1213         if (overlap(addr, len, _stext, _etext) ||
1214             overlap(addr, len, __start_rodata, __end_rodata))
1215                 err_printk(dev, NULL, "DMA-API: device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
1216 }
1217
1218 static void check_sync(struct device *dev,
1219                        struct dma_debug_entry *ref,
1220                        bool to_cpu)
1221 {
1222         struct dma_debug_entry *entry;
1223         struct hash_bucket *bucket;
1224         unsigned long flags;
1225
1226         bucket = get_hash_bucket(ref, &flags);
1227
1228         entry = bucket_find_contain(&bucket, ref, &flags);
1229
1230         if (!entry) {
1231                 err_printk(dev, NULL, "DMA-API: device driver tries "
1232                                 "to sync DMA memory it has not allocated "
1233                                 "[device address=0x%016llx] [size=%llu bytes]\n",
1234                                 (unsigned long long)ref->dev_addr, ref->size);
1235                 goto out;
1236         }
1237
1238         if (ref->size > entry->size) {
1239                 err_printk(dev, entry, "DMA-API: device driver syncs"
1240                                 " DMA memory outside allocated range "
1241                                 "[device address=0x%016llx] "
1242                                 "[allocation size=%llu bytes] "
1243                                 "[sync offset+size=%llu]\n",
1244                                 entry->dev_addr, entry->size,
1245                                 ref->size);
1246         }
1247
1248         if (entry->direction == DMA_BIDIRECTIONAL)
1249                 goto out;
1250
1251         if (ref->direction != entry->direction) {
1252                 err_printk(dev, entry, "DMA-API: device driver syncs "
1253                                 "DMA memory with different direction "
1254                                 "[device address=0x%016llx] [size=%llu bytes] "
1255                                 "[mapped with %s] [synced with %s]\n",
1256                                 (unsigned long long)ref->dev_addr, entry->size,
1257                                 dir2name[entry->direction],
1258                                 dir2name[ref->direction]);
1259         }
1260
1261         if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
1262                       !(ref->direction == DMA_TO_DEVICE))
1263                 err_printk(dev, entry, "DMA-API: device driver syncs "
1264                                 "device read-only DMA memory for cpu "
1265                                 "[device address=0x%016llx] [size=%llu bytes] "
1266                                 "[mapped with %s] [synced with %s]\n",
1267                                 (unsigned long long)ref->dev_addr, entry->size,
1268                                 dir2name[entry->direction],
1269                                 dir2name[ref->direction]);
1270
1271         if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
1272                        !(ref->direction == DMA_FROM_DEVICE))
1273                 err_printk(dev, entry, "DMA-API: device driver syncs "
1274                                 "device write-only DMA memory to device "
1275                                 "[device address=0x%016llx] [size=%llu bytes] "
1276                                 "[mapped with %s] [synced with %s]\n",
1277                                 (unsigned long long)ref->dev_addr, entry->size,
1278                                 dir2name[entry->direction],
1279                                 dir2name[ref->direction]);
1280
1281         if (ref->sg_call_ents && ref->type == dma_debug_sg &&
1282             ref->sg_call_ents != entry->sg_call_ents) {
1283                 err_printk(ref->dev, entry, "DMA-API: device driver syncs "
1284                            "DMA sg list with different entry count "
1285                            "[map count=%d] [sync count=%d]\n",
1286                            entry->sg_call_ents, ref->sg_call_ents);
1287         }
1288
1289 out:
1290         put_hash_bucket(bucket, &flags);
1291 }
1292
1293 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
1294                         size_t size, int direction, dma_addr_t dma_addr,
1295                         bool map_single)
1296 {
1297         struct dma_debug_entry *entry;
1298
1299         if (unlikely(dma_debug_disabled()))
1300                 return;
1301
1302         if (dma_mapping_error(dev, dma_addr))
1303                 return;
1304
1305         entry = dma_entry_alloc();
1306         if (!entry)
1307                 return;
1308
1309         entry->dev       = dev;
1310         entry->type      = dma_debug_page;
1311         entry->pfn       = page_to_pfn(page);
1312         entry->offset    = offset,
1313         entry->dev_addr  = dma_addr;
1314         entry->size      = size;
1315         entry->direction = direction;
1316         entry->map_err_type = MAP_ERR_NOT_CHECKED;
1317
1318         if (map_single)
1319                 entry->type = dma_debug_single;
1320
1321         check_for_stack(dev, page, offset);
1322
1323         if (!PageHighMem(page)) {
1324                 void *addr = page_address(page) + offset;
1325
1326                 check_for_illegal_area(dev, addr, size);
1327         }
1328
1329         add_dma_entry(entry);
1330 }
1331 EXPORT_SYMBOL(debug_dma_map_page);
1332
1333 void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
1334 {
1335         struct dma_debug_entry ref;
1336         struct dma_debug_entry *entry;
1337         struct hash_bucket *bucket;
1338         unsigned long flags;
1339
1340         if (unlikely(dma_debug_disabled()))
1341                 return;
1342
1343         ref.dev = dev;
1344         ref.dev_addr = dma_addr;
1345         bucket = get_hash_bucket(&ref, &flags);
1346
1347         list_for_each_entry(entry, &bucket->list, list) {
1348                 if (!exact_match(&ref, entry))
1349                         continue;
1350
1351                 /*
1352                  * The same physical address can be mapped multiple
1353                  * times. Without a hardware IOMMU this results in the
1354                  * same device addresses being put into the dma-debug
1355                  * hash multiple times too. This can result in false
1356                  * positives being reported. Therefore we implement a
1357                  * best-fit algorithm here which updates the first entry
1358                  * from the hash which fits the reference value and is
1359                  * not currently listed as being checked.
1360                  */
1361                 if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1362                         entry->map_err_type = MAP_ERR_CHECKED;
1363                         break;
1364                 }
1365         }
1366
1367         put_hash_bucket(bucket, &flags);
1368 }
1369 EXPORT_SYMBOL(debug_dma_mapping_error);
1370
1371 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
1372                           size_t size, int direction, bool map_single)
1373 {
1374         struct dma_debug_entry ref = {
1375                 .type           = dma_debug_page,
1376                 .dev            = dev,
1377                 .dev_addr       = addr,
1378                 .size           = size,
1379                 .direction      = direction,
1380         };
1381
1382         if (unlikely(dma_debug_disabled()))
1383                 return;
1384
1385         if (map_single)
1386                 ref.type = dma_debug_single;
1387
1388         check_unmap(&ref);
1389 }
1390 EXPORT_SYMBOL(debug_dma_unmap_page);
1391
1392 void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
1393                       int nents, int mapped_ents, int direction)
1394 {
1395         struct dma_debug_entry *entry;
1396         struct scatterlist *s;
1397         int i;
1398
1399         if (unlikely(dma_debug_disabled()))
1400                 return;
1401
1402         for_each_sg(sg, s, mapped_ents, i) {
1403                 entry = dma_entry_alloc();
1404                 if (!entry)
1405                         return;
1406
1407                 entry->type           = dma_debug_sg;
1408                 entry->dev            = dev;
1409                 entry->pfn            = page_to_pfn(sg_page(s));
1410                 entry->offset         = s->offset,
1411                 entry->size           = sg_dma_len(s);
1412                 entry->dev_addr       = sg_dma_address(s);
1413                 entry->direction      = direction;
1414                 entry->sg_call_ents   = nents;
1415                 entry->sg_mapped_ents = mapped_ents;
1416
1417                 check_for_stack(dev, sg_page(s), s->offset);
1418
1419                 if (!PageHighMem(sg_page(s))) {
1420                         check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
1421                 }
1422
1423                 add_dma_entry(entry);
1424         }
1425 }
1426 EXPORT_SYMBOL(debug_dma_map_sg);
1427
1428 static int get_nr_mapped_entries(struct device *dev,
1429                                  struct dma_debug_entry *ref)
1430 {
1431         struct dma_debug_entry *entry;
1432         struct hash_bucket *bucket;
1433         unsigned long flags;
1434         int mapped_ents;
1435
1436         bucket       = get_hash_bucket(ref, &flags);
1437         entry        = bucket_find_exact(bucket, ref);
1438         mapped_ents  = 0;
1439
1440         if (entry)
1441                 mapped_ents = entry->sg_mapped_ents;
1442         put_hash_bucket(bucket, &flags);
1443
1444         return mapped_ents;
1445 }
1446
1447 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
1448                         int nelems, int dir)
1449 {
1450         struct scatterlist *s;
1451         int mapped_ents = 0, i;
1452
1453         if (unlikely(dma_debug_disabled()))
1454                 return;
1455
1456         for_each_sg(sglist, s, nelems, i) {
1457
1458                 struct dma_debug_entry ref = {
1459                         .type           = dma_debug_sg,
1460                         .dev            = dev,
1461                         .pfn            = page_to_pfn(sg_page(s)),
1462                         .offset         = s->offset,
1463                         .dev_addr       = sg_dma_address(s),
1464                         .size           = sg_dma_len(s),
1465                         .direction      = dir,
1466                         .sg_call_ents   = nelems,
1467                 };
1468
1469                 if (mapped_ents && i >= mapped_ents)
1470                         break;
1471
1472                 if (!i)
1473                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1474
1475                 check_unmap(&ref);
1476         }
1477 }
1478 EXPORT_SYMBOL(debug_dma_unmap_sg);
1479
1480 void debug_dma_alloc_coherent(struct device *dev, size_t size,
1481                               dma_addr_t dma_addr, void *virt)
1482 {
1483         struct dma_debug_entry *entry;
1484
1485         if (unlikely(dma_debug_disabled()))
1486                 return;
1487
1488         if (unlikely(virt == NULL))
1489                 return;
1490
1491         entry = dma_entry_alloc();
1492         if (!entry)
1493                 return;
1494
1495         entry->type      = dma_debug_coherent;
1496         entry->dev       = dev;
1497         entry->pfn       = page_to_pfn(virt_to_page(virt));
1498         entry->offset    = (size_t) virt & ~PAGE_MASK;
1499         entry->size      = size;
1500         entry->dev_addr  = dma_addr;
1501         entry->direction = DMA_BIDIRECTIONAL;
1502
1503         add_dma_entry(entry);
1504 }
1505 EXPORT_SYMBOL(debug_dma_alloc_coherent);
1506
1507 void debug_dma_free_coherent(struct device *dev, size_t size,
1508                          void *virt, dma_addr_t addr)
1509 {
1510         struct dma_debug_entry ref = {
1511                 .type           = dma_debug_coherent,
1512                 .dev            = dev,
1513                 .pfn            = page_to_pfn(virt_to_page(virt)),
1514                 .offset         = (size_t) virt & ~PAGE_MASK,
1515                 .dev_addr       = addr,
1516                 .size           = size,
1517                 .direction      = DMA_BIDIRECTIONAL,
1518         };
1519
1520         if (unlikely(dma_debug_disabled()))
1521                 return;
1522
1523         check_unmap(&ref);
1524 }
1525 EXPORT_SYMBOL(debug_dma_free_coherent);
1526
1527 void debug_dma_map_resource(struct device *dev, phys_addr_t addr, size_t size,
1528                             int direction, dma_addr_t dma_addr)
1529 {
1530         struct dma_debug_entry *entry;
1531
1532         if (unlikely(dma_debug_disabled()))
1533                 return;
1534
1535         entry = dma_entry_alloc();
1536         if (!entry)
1537                 return;
1538
1539         entry->type             = dma_debug_resource;
1540         entry->dev              = dev;
1541         entry->pfn              = PHYS_PFN(addr);
1542         entry->offset           = offset_in_page(addr);
1543         entry->size             = size;
1544         entry->dev_addr         = dma_addr;
1545         entry->direction        = direction;
1546         entry->map_err_type     = MAP_ERR_NOT_CHECKED;
1547
1548         add_dma_entry(entry);
1549 }
1550 EXPORT_SYMBOL(debug_dma_map_resource);
1551
1552 void debug_dma_unmap_resource(struct device *dev, dma_addr_t dma_addr,
1553                               size_t size, int direction)
1554 {
1555         struct dma_debug_entry ref = {
1556                 .type           = dma_debug_resource,
1557                 .dev            = dev,
1558                 .dev_addr       = dma_addr,
1559                 .size           = size,
1560                 .direction      = direction,
1561         };
1562
1563         if (unlikely(dma_debug_disabled()))
1564                 return;
1565
1566         check_unmap(&ref);
1567 }
1568 EXPORT_SYMBOL(debug_dma_unmap_resource);
1569
1570 void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
1571                                    size_t size, int direction)
1572 {
1573         struct dma_debug_entry ref;
1574
1575         if (unlikely(dma_debug_disabled()))
1576                 return;
1577
1578         ref.type         = dma_debug_single;
1579         ref.dev          = dev;
1580         ref.dev_addr     = dma_handle;
1581         ref.size         = size;
1582         ref.direction    = direction;
1583         ref.sg_call_ents = 0;
1584
1585         check_sync(dev, &ref, true);
1586 }
1587 EXPORT_SYMBOL(debug_dma_sync_single_for_cpu);
1588
1589 void debug_dma_sync_single_for_device(struct device *dev,
1590                                       dma_addr_t dma_handle, size_t size,
1591                                       int direction)
1592 {
1593         struct dma_debug_entry ref;
1594
1595         if (unlikely(dma_debug_disabled()))
1596                 return;
1597
1598         ref.type         = dma_debug_single;
1599         ref.dev          = dev;
1600         ref.dev_addr     = dma_handle;
1601         ref.size         = size;
1602         ref.direction    = direction;
1603         ref.sg_call_ents = 0;
1604
1605         check_sync(dev, &ref, false);
1606 }
1607 EXPORT_SYMBOL(debug_dma_sync_single_for_device);
1608
1609 void debug_dma_sync_single_range_for_cpu(struct device *dev,
1610                                          dma_addr_t dma_handle,
1611                                          unsigned long offset, size_t size,
1612                                          int direction)
1613 {
1614         struct dma_debug_entry ref;
1615
1616         if (unlikely(dma_debug_disabled()))
1617                 return;
1618
1619         ref.type         = dma_debug_single;
1620         ref.dev          = dev;
1621         ref.dev_addr     = dma_handle;
1622         ref.size         = offset + size;
1623         ref.direction    = direction;
1624         ref.sg_call_ents = 0;
1625
1626         check_sync(dev, &ref, true);
1627 }
1628 EXPORT_SYMBOL(debug_dma_sync_single_range_for_cpu);
1629
1630 void debug_dma_sync_single_range_for_device(struct device *dev,
1631                                             dma_addr_t dma_handle,
1632                                             unsigned long offset,
1633                                             size_t size, int direction)
1634 {
1635         struct dma_debug_entry ref;
1636
1637         if (unlikely(dma_debug_disabled()))
1638                 return;
1639
1640         ref.type         = dma_debug_single;
1641         ref.dev          = dev;
1642         ref.dev_addr     = dma_handle;
1643         ref.size         = offset + size;
1644         ref.direction    = direction;
1645         ref.sg_call_ents = 0;
1646
1647         check_sync(dev, &ref, false);
1648 }
1649 EXPORT_SYMBOL(debug_dma_sync_single_range_for_device);
1650
1651 void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
1652                                int nelems, int direction)
1653 {
1654         struct scatterlist *s;
1655         int mapped_ents = 0, i;
1656
1657         if (unlikely(dma_debug_disabled()))
1658                 return;
1659
1660         for_each_sg(sg, s, nelems, i) {
1661
1662                 struct dma_debug_entry ref = {
1663                         .type           = dma_debug_sg,
1664                         .dev            = dev,
1665                         .pfn            = page_to_pfn(sg_page(s)),
1666                         .offset         = s->offset,
1667                         .dev_addr       = sg_dma_address(s),
1668                         .size           = sg_dma_len(s),
1669                         .direction      = direction,
1670                         .sg_call_ents   = nelems,
1671                 };
1672
1673                 if (!i)
1674                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1675
1676                 if (i >= mapped_ents)
1677                         break;
1678
1679                 check_sync(dev, &ref, true);
1680         }
1681 }
1682 EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
1683
1684 void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
1685                                   int nelems, int direction)
1686 {
1687         struct scatterlist *s;
1688         int mapped_ents = 0, i;
1689
1690         if (unlikely(dma_debug_disabled()))
1691                 return;
1692
1693         for_each_sg(sg, s, nelems, i) {
1694
1695                 struct dma_debug_entry ref = {
1696                         .type           = dma_debug_sg,
1697                         .dev            = dev,
1698                         .pfn            = page_to_pfn(sg_page(s)),
1699                         .offset         = s->offset,
1700                         .dev_addr       = sg_dma_address(s),
1701                         .size           = sg_dma_len(s),
1702                         .direction      = direction,
1703                         .sg_call_ents   = nelems,
1704                 };
1705                 if (!i)
1706                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1707
1708                 if (i >= mapped_ents)
1709                         break;
1710
1711                 check_sync(dev, &ref, false);
1712         }
1713 }
1714 EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
1715
1716 static int __init dma_debug_driver_setup(char *str)
1717 {
1718         int i;
1719
1720         for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
1721                 current_driver_name[i] = *str;
1722                 if (*str == 0)
1723                         break;
1724         }
1725
1726         if (current_driver_name[0])
1727                 pr_info("DMA-API: enable driver filter for driver [%s]\n",
1728                         current_driver_name);
1729
1730
1731         return 1;
1732 }
1733 __setup("dma_debug_driver=", dma_debug_driver_setup);