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         /*
1159          * Drivers should use dma_mapping_error() to check the returned
1160          * addresses of dma_map_single() and dma_map_page().
1161          * If not, print this warning message. See Documentation/DMA-API.txt.
1162          */
1163         if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1164                 err_printk(ref->dev, entry,
1165                            "DMA-API: device driver failed to check map error"
1166                            "[device address=0x%016llx] [size=%llu bytes] "
1167                            "[mapped as %s]",
1168                            ref->dev_addr, ref->size,
1169                            type2name[entry->type]);
1170         }
1171
1172         hash_bucket_del(entry);
1173         dma_entry_free(entry);
1174
1175         put_hash_bucket(bucket, &flags);
1176 }
1177
1178 static void check_for_stack(struct device *dev,
1179                             struct page *page, size_t offset)
1180 {
1181         void *addr;
1182         struct vm_struct *stack_vm_area = task_stack_vm_area(current);
1183
1184         if (!stack_vm_area) {
1185                 /* Stack is direct-mapped. */
1186                 if (PageHighMem(page))
1187                         return;
1188                 addr = page_address(page) + offset;
1189                 if (object_is_on_stack(addr))
1190                         err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [addr=%p]\n", addr);
1191         } else {
1192                 /* Stack is vmalloced. */
1193                 int i;
1194
1195                 for (i = 0; i < stack_vm_area->nr_pages; i++) {
1196                         if (page != stack_vm_area->pages[i])
1197                                 continue;
1198
1199                         addr = (u8 *)current->stack + i * PAGE_SIZE + offset;
1200                         err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [probable addr=%p]\n", addr);
1201                         break;
1202                 }
1203         }
1204 }
1205
1206 static inline bool overlap(void *addr, unsigned long len, void *start, void *end)
1207 {
1208         unsigned long a1 = (unsigned long)addr;
1209         unsigned long b1 = a1 + len;
1210         unsigned long a2 = (unsigned long)start;
1211         unsigned long b2 = (unsigned long)end;
1212
1213         return !(b1 <= a2 || a1 >= b2);
1214 }
1215
1216 static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
1217 {
1218         if (overlap(addr, len, _stext, _etext) ||
1219             overlap(addr, len, __start_rodata, __end_rodata))
1220                 err_printk(dev, NULL, "DMA-API: device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
1221 }
1222
1223 static void check_sync(struct device *dev,
1224                        struct dma_debug_entry *ref,
1225                        bool to_cpu)
1226 {
1227         struct dma_debug_entry *entry;
1228         struct hash_bucket *bucket;
1229         unsigned long flags;
1230
1231         bucket = get_hash_bucket(ref, &flags);
1232
1233         entry = bucket_find_contain(&bucket, ref, &flags);
1234
1235         if (!entry) {
1236                 err_printk(dev, NULL, "DMA-API: device driver tries "
1237                                 "to sync DMA memory it has not allocated "
1238                                 "[device address=0x%016llx] [size=%llu bytes]\n",
1239                                 (unsigned long long)ref->dev_addr, ref->size);
1240                 goto out;
1241         }
1242
1243         if (ref->size > entry->size) {
1244                 err_printk(dev, entry, "DMA-API: device driver syncs"
1245                                 " DMA memory outside allocated range "
1246                                 "[device address=0x%016llx] "
1247                                 "[allocation size=%llu bytes] "
1248                                 "[sync offset+size=%llu]\n",
1249                                 entry->dev_addr, entry->size,
1250                                 ref->size);
1251         }
1252
1253         if (entry->direction == DMA_BIDIRECTIONAL)
1254                 goto out;
1255
1256         if (ref->direction != entry->direction) {
1257                 err_printk(dev, entry, "DMA-API: device driver syncs "
1258                                 "DMA memory with different direction "
1259                                 "[device address=0x%016llx] [size=%llu bytes] "
1260                                 "[mapped with %s] [synced with %s]\n",
1261                                 (unsigned long long)ref->dev_addr, entry->size,
1262                                 dir2name[entry->direction],
1263                                 dir2name[ref->direction]);
1264         }
1265
1266         if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
1267                       !(ref->direction == DMA_TO_DEVICE))
1268                 err_printk(dev, entry, "DMA-API: device driver syncs "
1269                                 "device read-only DMA memory for cpu "
1270                                 "[device address=0x%016llx] [size=%llu bytes] "
1271                                 "[mapped with %s] [synced with %s]\n",
1272                                 (unsigned long long)ref->dev_addr, entry->size,
1273                                 dir2name[entry->direction],
1274                                 dir2name[ref->direction]);
1275
1276         if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
1277                        !(ref->direction == DMA_FROM_DEVICE))
1278                 err_printk(dev, entry, "DMA-API: device driver syncs "
1279                                 "device write-only DMA memory to device "
1280                                 "[device address=0x%016llx] [size=%llu bytes] "
1281                                 "[mapped with %s] [synced with %s]\n",
1282                                 (unsigned long long)ref->dev_addr, entry->size,
1283                                 dir2name[entry->direction],
1284                                 dir2name[ref->direction]);
1285
1286         if (ref->sg_call_ents && ref->type == dma_debug_sg &&
1287             ref->sg_call_ents != entry->sg_call_ents) {
1288                 err_printk(ref->dev, entry, "DMA-API: device driver syncs "
1289                            "DMA sg list with different entry count "
1290                            "[map count=%d] [sync count=%d]\n",
1291                            entry->sg_call_ents, ref->sg_call_ents);
1292         }
1293
1294 out:
1295         put_hash_bucket(bucket, &flags);
1296 }
1297
1298 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
1299                         size_t size, int direction, dma_addr_t dma_addr,
1300                         bool map_single)
1301 {
1302         struct dma_debug_entry *entry;
1303
1304         if (unlikely(dma_debug_disabled()))
1305                 return;
1306
1307         if (dma_mapping_error(dev, dma_addr))
1308                 return;
1309
1310         entry = dma_entry_alloc();
1311         if (!entry)
1312                 return;
1313
1314         entry->dev       = dev;
1315         entry->type      = dma_debug_page;
1316         entry->pfn       = page_to_pfn(page);
1317         entry->offset    = offset,
1318         entry->dev_addr  = dma_addr;
1319         entry->size      = size;
1320         entry->direction = direction;
1321         entry->map_err_type = MAP_ERR_NOT_CHECKED;
1322
1323         if (map_single)
1324                 entry->type = dma_debug_single;
1325
1326         check_for_stack(dev, page, offset);
1327
1328         if (!PageHighMem(page)) {
1329                 void *addr = page_address(page) + offset;
1330
1331                 check_for_illegal_area(dev, addr, size);
1332         }
1333
1334         add_dma_entry(entry);
1335 }
1336 EXPORT_SYMBOL(debug_dma_map_page);
1337
1338 void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
1339 {
1340         struct dma_debug_entry ref;
1341         struct dma_debug_entry *entry;
1342         struct hash_bucket *bucket;
1343         unsigned long flags;
1344
1345         if (unlikely(dma_debug_disabled()))
1346                 return;
1347
1348         ref.dev = dev;
1349         ref.dev_addr = dma_addr;
1350         bucket = get_hash_bucket(&ref, &flags);
1351
1352         list_for_each_entry(entry, &bucket->list, list) {
1353                 if (!exact_match(&ref, entry))
1354                         continue;
1355
1356                 /*
1357                  * The same physical address can be mapped multiple
1358                  * times. Without a hardware IOMMU this results in the
1359                  * same device addresses being put into the dma-debug
1360                  * hash multiple times too. This can result in false
1361                  * positives being reported. Therefore we implement a
1362                  * best-fit algorithm here which updates the first entry
1363                  * from the hash which fits the reference value and is
1364                  * not currently listed as being checked.
1365                  */
1366                 if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1367                         entry->map_err_type = MAP_ERR_CHECKED;
1368                         break;
1369                 }
1370         }
1371
1372         put_hash_bucket(bucket, &flags);
1373 }
1374 EXPORT_SYMBOL(debug_dma_mapping_error);
1375
1376 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
1377                           size_t size, int direction, bool map_single)
1378 {
1379         struct dma_debug_entry ref = {
1380                 .type           = dma_debug_page,
1381                 .dev            = dev,
1382                 .dev_addr       = addr,
1383                 .size           = size,
1384                 .direction      = direction,
1385         };
1386
1387         if (unlikely(dma_debug_disabled()))
1388                 return;
1389
1390         if (map_single)
1391                 ref.type = dma_debug_single;
1392
1393         check_unmap(&ref);
1394 }
1395 EXPORT_SYMBOL(debug_dma_unmap_page);
1396
1397 void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
1398                       int nents, int mapped_ents, int direction)
1399 {
1400         struct dma_debug_entry *entry;
1401         struct scatterlist *s;
1402         int i;
1403
1404         if (unlikely(dma_debug_disabled()))
1405                 return;
1406
1407         for_each_sg(sg, s, mapped_ents, i) {
1408                 entry = dma_entry_alloc();
1409                 if (!entry)
1410                         return;
1411
1412                 entry->type           = dma_debug_sg;
1413                 entry->dev            = dev;
1414                 entry->pfn            = page_to_pfn(sg_page(s));
1415                 entry->offset         = s->offset,
1416                 entry->size           = sg_dma_len(s);
1417                 entry->dev_addr       = sg_dma_address(s);
1418                 entry->direction      = direction;
1419                 entry->sg_call_ents   = nents;
1420                 entry->sg_mapped_ents = mapped_ents;
1421
1422                 check_for_stack(dev, sg_page(s), s->offset);
1423
1424                 if (!PageHighMem(sg_page(s))) {
1425                         check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
1426                 }
1427
1428                 add_dma_entry(entry);
1429         }
1430 }
1431 EXPORT_SYMBOL(debug_dma_map_sg);
1432
1433 static int get_nr_mapped_entries(struct device *dev,
1434                                  struct dma_debug_entry *ref)
1435 {
1436         struct dma_debug_entry *entry;
1437         struct hash_bucket *bucket;
1438         unsigned long flags;
1439         int mapped_ents;
1440
1441         bucket       = get_hash_bucket(ref, &flags);
1442         entry        = bucket_find_exact(bucket, ref);
1443         mapped_ents  = 0;
1444
1445         if (entry)
1446                 mapped_ents = entry->sg_mapped_ents;
1447         put_hash_bucket(bucket, &flags);
1448
1449         return mapped_ents;
1450 }
1451
1452 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
1453                         int nelems, int dir)
1454 {
1455         struct scatterlist *s;
1456         int mapped_ents = 0, i;
1457
1458         if (unlikely(dma_debug_disabled()))
1459                 return;
1460
1461         for_each_sg(sglist, s, nelems, i) {
1462
1463                 struct dma_debug_entry ref = {
1464                         .type           = dma_debug_sg,
1465                         .dev            = dev,
1466                         .pfn            = page_to_pfn(sg_page(s)),
1467                         .offset         = s->offset,
1468                         .dev_addr       = sg_dma_address(s),
1469                         .size           = sg_dma_len(s),
1470                         .direction      = dir,
1471                         .sg_call_ents   = nelems,
1472                 };
1473
1474                 if (mapped_ents && i >= mapped_ents)
1475                         break;
1476
1477                 if (!i)
1478                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1479
1480                 check_unmap(&ref);
1481         }
1482 }
1483 EXPORT_SYMBOL(debug_dma_unmap_sg);
1484
1485 void debug_dma_alloc_coherent(struct device *dev, size_t size,
1486                               dma_addr_t dma_addr, void *virt)
1487 {
1488         struct dma_debug_entry *entry;
1489
1490         if (unlikely(dma_debug_disabled()))
1491                 return;
1492
1493         if (unlikely(virt == NULL))
1494                 return;
1495
1496         entry = dma_entry_alloc();
1497         if (!entry)
1498                 return;
1499
1500         entry->type      = dma_debug_coherent;
1501         entry->dev       = dev;
1502         entry->pfn       = page_to_pfn(virt_to_page(virt));
1503         entry->offset    = (size_t) virt & ~PAGE_MASK;
1504         entry->size      = size;
1505         entry->dev_addr  = dma_addr;
1506         entry->direction = DMA_BIDIRECTIONAL;
1507
1508         add_dma_entry(entry);
1509 }
1510 EXPORT_SYMBOL(debug_dma_alloc_coherent);
1511
1512 void debug_dma_free_coherent(struct device *dev, size_t size,
1513                          void *virt, dma_addr_t addr)
1514 {
1515         struct dma_debug_entry ref = {
1516                 .type           = dma_debug_coherent,
1517                 .dev            = dev,
1518                 .pfn            = page_to_pfn(virt_to_page(virt)),
1519                 .offset         = (size_t) virt & ~PAGE_MASK,
1520                 .dev_addr       = addr,
1521                 .size           = size,
1522                 .direction      = DMA_BIDIRECTIONAL,
1523         };
1524
1525         if (unlikely(dma_debug_disabled()))
1526                 return;
1527
1528         check_unmap(&ref);
1529 }
1530 EXPORT_SYMBOL(debug_dma_free_coherent);
1531
1532 void debug_dma_map_resource(struct device *dev, phys_addr_t addr, size_t size,
1533                             int direction, dma_addr_t dma_addr)
1534 {
1535         struct dma_debug_entry *entry;
1536
1537         if (unlikely(dma_debug_disabled()))
1538                 return;
1539
1540         entry = dma_entry_alloc();
1541         if (!entry)
1542                 return;
1543
1544         entry->type             = dma_debug_resource;
1545         entry->dev              = dev;
1546         entry->pfn              = PHYS_PFN(addr);
1547         entry->offset           = offset_in_page(addr);
1548         entry->size             = size;
1549         entry->dev_addr         = dma_addr;
1550         entry->direction        = direction;
1551         entry->map_err_type     = MAP_ERR_NOT_CHECKED;
1552
1553         add_dma_entry(entry);
1554 }
1555 EXPORT_SYMBOL(debug_dma_map_resource);
1556
1557 void debug_dma_unmap_resource(struct device *dev, dma_addr_t dma_addr,
1558                               size_t size, int direction)
1559 {
1560         struct dma_debug_entry ref = {
1561                 .type           = dma_debug_resource,
1562                 .dev            = dev,
1563                 .dev_addr       = dma_addr,
1564                 .size           = size,
1565                 .direction      = direction,
1566         };
1567
1568         if (unlikely(dma_debug_disabled()))
1569                 return;
1570
1571         check_unmap(&ref);
1572 }
1573 EXPORT_SYMBOL(debug_dma_unmap_resource);
1574
1575 void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
1576                                    size_t size, int direction)
1577 {
1578         struct dma_debug_entry ref;
1579
1580         if (unlikely(dma_debug_disabled()))
1581                 return;
1582
1583         ref.type         = dma_debug_single;
1584         ref.dev          = dev;
1585         ref.dev_addr     = dma_handle;
1586         ref.size         = size;
1587         ref.direction    = direction;
1588         ref.sg_call_ents = 0;
1589
1590         check_sync(dev, &ref, true);
1591 }
1592 EXPORT_SYMBOL(debug_dma_sync_single_for_cpu);
1593
1594 void debug_dma_sync_single_for_device(struct device *dev,
1595                                       dma_addr_t dma_handle, size_t size,
1596                                       int direction)
1597 {
1598         struct dma_debug_entry ref;
1599
1600         if (unlikely(dma_debug_disabled()))
1601                 return;
1602
1603         ref.type         = dma_debug_single;
1604         ref.dev          = dev;
1605         ref.dev_addr     = dma_handle;
1606         ref.size         = size;
1607         ref.direction    = direction;
1608         ref.sg_call_ents = 0;
1609
1610         check_sync(dev, &ref, false);
1611 }
1612 EXPORT_SYMBOL(debug_dma_sync_single_for_device);
1613
1614 void debug_dma_sync_single_range_for_cpu(struct device *dev,
1615                                          dma_addr_t dma_handle,
1616                                          unsigned long offset, size_t size,
1617                                          int direction)
1618 {
1619         struct dma_debug_entry ref;
1620
1621         if (unlikely(dma_debug_disabled()))
1622                 return;
1623
1624         ref.type         = dma_debug_single;
1625         ref.dev          = dev;
1626         ref.dev_addr     = dma_handle;
1627         ref.size         = offset + size;
1628         ref.direction    = direction;
1629         ref.sg_call_ents = 0;
1630
1631         check_sync(dev, &ref, true);
1632 }
1633 EXPORT_SYMBOL(debug_dma_sync_single_range_for_cpu);
1634
1635 void debug_dma_sync_single_range_for_device(struct device *dev,
1636                                             dma_addr_t dma_handle,
1637                                             unsigned long offset,
1638                                             size_t size, int direction)
1639 {
1640         struct dma_debug_entry ref;
1641
1642         if (unlikely(dma_debug_disabled()))
1643                 return;
1644
1645         ref.type         = dma_debug_single;
1646         ref.dev          = dev;
1647         ref.dev_addr     = dma_handle;
1648         ref.size         = offset + size;
1649         ref.direction    = direction;
1650         ref.sg_call_ents = 0;
1651
1652         check_sync(dev, &ref, false);
1653 }
1654 EXPORT_SYMBOL(debug_dma_sync_single_range_for_device);
1655
1656 void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
1657                                int nelems, int direction)
1658 {
1659         struct scatterlist *s;
1660         int mapped_ents = 0, i;
1661
1662         if (unlikely(dma_debug_disabled()))
1663                 return;
1664
1665         for_each_sg(sg, s, nelems, i) {
1666
1667                 struct dma_debug_entry ref = {
1668                         .type           = dma_debug_sg,
1669                         .dev            = dev,
1670                         .pfn            = page_to_pfn(sg_page(s)),
1671                         .offset         = s->offset,
1672                         .dev_addr       = sg_dma_address(s),
1673                         .size           = sg_dma_len(s),
1674                         .direction      = direction,
1675                         .sg_call_ents   = nelems,
1676                 };
1677
1678                 if (!i)
1679                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1680
1681                 if (i >= mapped_ents)
1682                         break;
1683
1684                 check_sync(dev, &ref, true);
1685         }
1686 }
1687 EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
1688
1689 void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
1690                                   int nelems, int direction)
1691 {
1692         struct scatterlist *s;
1693         int mapped_ents = 0, i;
1694
1695         if (unlikely(dma_debug_disabled()))
1696                 return;
1697
1698         for_each_sg(sg, s, nelems, i) {
1699
1700                 struct dma_debug_entry ref = {
1701                         .type           = dma_debug_sg,
1702                         .dev            = dev,
1703                         .pfn            = page_to_pfn(sg_page(s)),
1704                         .offset         = s->offset,
1705                         .dev_addr       = sg_dma_address(s),
1706                         .size           = sg_dma_len(s),
1707                         .direction      = direction,
1708                         .sg_call_ents   = nelems,
1709                 };
1710                 if (!i)
1711                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1712
1713                 if (i >= mapped_ents)
1714                         break;
1715
1716                 check_sync(dev, &ref, false);
1717         }
1718 }
1719 EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
1720
1721 static int __init dma_debug_driver_setup(char *str)
1722 {
1723         int i;
1724
1725         for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
1726                 current_driver_name[i] = *str;
1727                 if (*str == 0)
1728                         break;
1729         }
1730
1731         if (current_driver_name[0])
1732                 pr_info("DMA-API: enable driver filter for driver [%s]\n",
1733                         current_driver_name);
1734
1735
1736         return 1;
1737 }
1738 __setup("dma_debug_driver=", dma_debug_driver_setup);