kernel/dma/debug.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2008 Advanced Micro Devices, Inc.
   4  *
   5  * Author: Joerg Roedel <[email protected]>
   6  */
   7
   8 #define pr_fmt(fmt)     "DMA-API: " fmt
   9
  10 #include <linux/sched/task_stack.h>
  11 #include <linux/scatterlist.h>
  12 #include <linux/dma-mapping.h>
  13 #include <linux/sched/task.h>
  14 #include <linux/stacktrace.h>
  15 #include <linux/dma-debug.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/vmalloc.h>
  18 #include <linux/debugfs.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/export.h>
  21 #include <linux/device.h>
  22 #include <linux/types.h>
  23 #include <linux/sched.h>
  24 #include <linux/ctype.h>
  25 #include <linux/list.h>
  26 #include <linux/slab.h>
  27
  28 #include <asm/sections.h>
  29
  30 #define HASH_SIZE       1024ULL
  31 #define HASH_FN_SHIFT   13
  32 #define HASH_FN_MASK    (HASH_SIZE - 1)
  33
  34 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
  35 /* If the pool runs out, add this many new entries at once */
  36 #define DMA_DEBUG_DYNAMIC_ENTRIES (PAGE_SIZE / sizeof(struct dma_debug_entry))
  37
  38 enum {
  39         dma_debug_single,
  40         dma_debug_sg,
  41         dma_debug_coherent,
  42         dma_debug_resource,
  43 };
  44
  45 enum map_err_types {
  46         MAP_ERR_CHECK_NOT_APPLICABLE,
  47         MAP_ERR_NOT_CHECKED,
  48         MAP_ERR_CHECKED,
  49 };
  50
  51 #define DMA_DEBUG_STACKTRACE_ENTRIES 5
  52
  53 /**
  54  * struct dma_debug_entry - track a dma_map* or dma_alloc_coherent mapping
  55  * @list: node on pre-allocated free_entries list
  56  * @dev: 'dev' argument to dma_map_{page|single|sg} or dma_alloc_coherent
  57  * @type: single, page, sg, coherent
  58  * @pfn: page frame of the start address
  59  * @offset: offset of mapping relative to pfn
  60  * @size: length of the mapping
  61  * @direction: enum dma_data_direction
  62  * @sg_call_ents: 'nents' from dma_map_sg
  63  * @sg_mapped_ents: 'mapped_ents' from dma_map_sg
  64  * @map_err_type: track whether dma_mapping_error() was checked
  65  * @stacktrace: support backtraces when a violation is detected
  66  */
  67 struct dma_debug_entry {
  68         struct list_head list;
  69         struct device    *dev;
  70         int              type;
  71         unsigned long    pfn;
  72         size_t           offset;
  73         u64              dev_addr;
  74         u64              size;
  75         int              direction;
  76         int              sg_call_ents;
  77         int              sg_mapped_ents;
  78         enum map_err_types  map_err_type;
  79 #ifdef CONFIG_STACKTRACE
  80         unsigned int    stack_len;
  81         unsigned long   stack_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
  82 #endif
  83 };
  84
  85 typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *);
  86
  87 struct hash_bucket {
  88         struct list_head list;
  89         spinlock_t lock;
  90 } ____cacheline_aligned_in_smp;
  91
  92 /* Hash list to save the allocated dma addresses */
  93 static struct hash_bucket dma_entry_hash[HASH_SIZE];
  94 /* List of pre-allocated dma_debug_entry's */
  95 static LIST_HEAD(free_entries);
  96 /* Lock for the list above */
  97 static DEFINE_SPINLOCK(free_entries_lock);
  98
  99 /* Global disable flag - will be set in case of an error */
 100 static bool global_disable __read_mostly;
 101
 102 /* Early initialization disable flag, set at the end of dma_debug_init */
 103 static bool dma_debug_initialized __read_mostly;
 104
 105 static inline bool dma_debug_disabled(void)
 106 {
 107         return global_disable || !dma_debug_initialized;
 108 }
 109
 110 /* Global error count */
 111 static u32 error_count;
 112
 113 /* Global error show enable*/
 114 static u32 show_all_errors __read_mostly;
 115 /* Number of errors to show */
 116 static u32 show_num_errors = 1;
 117
 118 static u32 num_free_entries;
 119 static u32 min_free_entries;
 120 static u32 nr_total_entries;
 121
 122 /* number of preallocated entries requested by kernel cmdline */
 123 static u32 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
 124
 125 /* per-driver filter related state */
 126
 127 #define NAME_MAX_LEN    64
 128
 129 static char                  current_driver_name[NAME_MAX_LEN] __read_mostly;
 130 static struct device_driver *current_driver                    __read_mostly;
 131
 132 static DEFINE_RWLOCK(driver_name_lock);
 133
 134 static const char *const maperr2str[] = {
 135         [MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
 136         [MAP_ERR_NOT_CHECKED] = "dma map error not checked",
 137         [MAP_ERR_CHECKED] = "dma map error checked",
 138 };
 139
 140 static const char *type2name[5] = { "single", "page",
 141                                     "scather-gather", "coherent",
 142                                     "resource" };
 143
 144 static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
 145                                    "DMA_FROM_DEVICE", "DMA_NONE" };
 146
 147 /*
 148  * The access to some variables in this macro is racy. We can't use atomic_t
 149  * here because all these variables are exported to debugfs. Some of them even
 150  * writeable. This is also the reason why a lock won't help much. But anyway,
 151  * the races are no big deal. Here is why:
 152  *
 153  *   error_count: the addition is racy, but the worst thing that can happen is
 154  *                that we don't count some errors
 155  *   show_num_errors: the subtraction is racy. Also no big deal because in
 156  *                    worst case this will result in one warning more in the
 157  *                    system log than the user configured. This variable is
 158  *                    writeable via debugfs.
 159  */
 160 static inline void dump_entry_trace(struct dma_debug_entry *entry)
 161 {
 162 #ifdef CONFIG_STACKTRACE
 163         if (entry) {
 164                 pr_warning("Mapped at:\n");
 165                 stack_trace_print(entry->stack_entries, entry->stack_len, 0);
 166         }
 167 #endif
 168 }
 169
 170 static bool driver_filter(struct device *dev)
 171 {
 172         struct device_driver *drv;
 173         unsigned long flags;
 174         bool ret;
 175
 176         /* driver filter off */
 177         if (likely(!current_driver_name[0]))
 178                 return true;
 179
 180         /* driver filter on and initialized */
 181         if (current_driver && dev && dev->driver == current_driver)
 182                 return true;
 183
 184         /* driver filter on, but we can't filter on a NULL device... */
 185         if (!dev)
 186                 return false;
 187
 188         if (current_driver || !current_driver_name[0])
 189                 return false;
 190
 191         /* driver filter on but not yet initialized */
 192         drv = dev->driver;
 193         if (!drv)
 194                 return false;
 195
 196         /* lock to protect against change of current_driver_name */
 197         read_lock_irqsave(&driver_name_lock, flags);
 198
 199         ret = false;
 200         if (drv->name &&
 201             strncmp(current_driver_name, drv->name, NAME_MAX_LEN - 1) == 0) {
 202                 current_driver = drv;
 203                 ret = true;
 204         }
 205
 206         read_unlock_irqrestore(&driver_name_lock, flags);
 207
 208         return ret;
 209 }
 210
 211 #define err_printk(dev, entry, format, arg...) do {                     \
 212                 error_count += 1;                                       \
 213                 if (driver_filter(dev) &&                               \
 214                     (show_all_errors || show_num_errors > 0)) {         \
 215                         WARN(1, pr_fmt("%s %s: ") format,               \
 216                              dev ? dev_driver_string(dev) : "NULL",     \
 217                              dev ? dev_name(dev) : "NULL", ## arg);     \
 218                         dump_entry_trace(entry);                        \
 219                 }                                                       \
 220                 if (!show_all_errors && show_num_errors > 0)            \
 221                         show_num_errors -= 1;                           \
 222         } while (0);
 223
 224 /*
 225  * Hash related functions
 226  *
 227  * Every DMA-API request is saved into a struct dma_debug_entry. To
 228  * have quick access to these structs they are stored into a hash.
 229  */
 230 static int hash_fn(struct dma_debug_entry *entry)
 231 {
 232         /*
 233          * Hash function is based on the dma address.
 234          * We use bits 20-27 here as the index into the hash
 235          */
 236         return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
 237 }
 238
 239 /*
 240  * Request exclusive access to a hash bucket for a given dma_debug_entry.
 241  */
 242 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
 243                                            unsigned long *flags)
 244         __acquires(&dma_entry_hash[idx].lock)
 245 {
 246         int idx = hash_fn(entry);
 247         unsigned long __flags;
 248
 249         spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
 250         *flags = __flags;
 251         return &dma_entry_hash[idx];
 252 }
 253
 254 /*
 255  * Give up exclusive access to the hash bucket
 256  */
 257 static void put_hash_bucket(struct hash_bucket *bucket,
 258                             unsigned long *flags)
 259         __releases(&bucket->lock)
 260 {
 261         unsigned long __flags = *flags;
 262
 263         spin_unlock_irqrestore(&bucket->lock, __flags);
 264 }
 265
 266 static bool exact_match(struct dma_debug_entry *a, struct dma_debug_entry *b)
 267 {
 268         return ((a->dev_addr == b->dev_addr) &&
 269                 (a->dev == b->dev)) ? true : false;
 270 }
 271
 272 static bool containing_match(struct dma_debug_entry *a,
 273                              struct dma_debug_entry *b)
 274 {
 275         if (a->dev != b->dev)
 276                 return false;
 277
 278         if ((b->dev_addr <= a->dev_addr) &&
 279             ((b->dev_addr + b->size) >= (a->dev_addr + a->size)))
 280                 return true;
 281
 282         return false;
 283 }
 284
 285 /*
 286  * Search a given entry in the hash bucket list
 287  */
 288 static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
 289                                                   struct dma_debug_entry *ref,
 290                                                   match_fn match)
 291 {
 292         struct dma_debug_entry *entry, *ret = NULL;
 293         int matches = 0, match_lvl, last_lvl = -1;
 294
 295         list_for_each_entry(entry, &bucket->list, list) {
 296                 if (!match(ref, entry))
 297                         continue;
 298
 299                 /*
 300                  * Some drivers map the same physical address multiple
 301                  * times. Without a hardware IOMMU this results in the
 302                  * same device addresses being put into the dma-debug
 303                  * hash multiple times too. This can result in false
 304                  * positives being reported. Therefore we implement a
 305                  * best-fit algorithm here which returns the entry from
 306                  * the hash which fits best to the reference value
 307                  * instead of the first-fit.
 308                  */
 309                 matches += 1;
 310                 match_lvl = 0;
 311                 entry->size         == ref->size         ? ++match_lvl : 0;
 312                 entry->type         == ref->type         ? ++match_lvl : 0;
 313                 entry->direction    == ref->direction    ? ++match_lvl : 0;
 314                 entry->sg_call_ents == ref->sg_call_ents ? ++match_lvl : 0;
 315
 316                 if (match_lvl == 4) {
 317                         /* perfect-fit - return the result */
 318                         return entry;
 319                 } else if (match_lvl > last_lvl) {
 320                         /*
 321                          * We found an entry that fits better then the
 322                          * previous one or it is the 1st match.
 323                          */
 324                         last_lvl = match_lvl;
 325                         ret      = entry;
 326                 }
 327         }
 328
 329         /*
 330          * If we have multiple matches but no perfect-fit, just return
 331          * NULL.
 332          */
 333         ret = (matches == 1) ? ret : NULL;
 334
 335         return ret;
 336 }
 337
 338 static struct dma_debug_entry *bucket_find_exact(struct hash_bucket *bucket,
 339                                                  struct dma_debug_entry *ref)
 340 {
 341         return __hash_bucket_find(bucket, ref, exact_match);
 342 }
 343
 344 static struct dma_debug_entry *bucket_find_contain(struct hash_bucket **bucket,
 345                                                    struct dma_debug_entry *ref,
 346                                                    unsigned long *flags)
 347 {
 348
 349         unsigned int max_range = dma_get_max_seg_size(ref->dev);
 350         struct dma_debug_entry *entry, index = *ref;
 351         unsigned int range = 0;
 352
 353         while (range <= max_range) {
 354                 entry = __hash_bucket_find(*bucket, ref, containing_match);
 355
 356                 if (entry)
 357                         return entry;
 358
 359                 /*
 360                  * Nothing found, go back a hash bucket
 361                  */
 362                 put_hash_bucket(*bucket, flags);
 363                 range          += (1 << HASH_FN_SHIFT);
 364                 index.dev_addr -= (1 << HASH_FN_SHIFT);
 365                 *bucket = get_hash_bucket(&index, flags);
 366         }
 367
 368         return NULL;
 369 }
 370
 371 /*
 372  * Add an entry to a hash bucket
 373  */
 374 static void hash_bucket_add(struct hash_bucket *bucket,
 375                             struct dma_debug_entry *entry)
 376 {
 377         list_add_tail(&entry->list, &bucket->list);
 378 }
 379
 380 /*
 381  * Remove entry from a hash bucket list
 382  */
 383 static void hash_bucket_del(struct dma_debug_entry *entry)
 384 {
 385         list_del(&entry->list);
 386 }
 387
 388 static unsigned long long phys_addr(struct dma_debug_entry *entry)
 389 {
 390         if (entry->type == dma_debug_resource)
 391                 return __pfn_to_phys(entry->pfn) + entry->offset;
 392
 393         return page_to_phys(pfn_to_page(entry->pfn)) + entry->offset;
 394 }
 395
 396 /*
 397  * Dump mapping entries for debugging purposes
 398  */
 399 void debug_dma_dump_mappings(struct device *dev)
 400 {
 401         int idx;
 402
 403         for (idx = 0; idx < HASH_SIZE; idx++) {
 404                 struct hash_bucket *bucket = &dma_entry_hash[idx];
 405                 struct dma_debug_entry *entry;
 406                 unsigned long flags;
 407
 408                 spin_lock_irqsave(&bucket->lock, flags);
 409
 410                 list_for_each_entry(entry, &bucket->list, list) {
 411                         if (!dev || dev == entry->dev) {
 412                                 dev_info(entry->dev,
 413                                          "%s idx %d P=%Lx N=%lx D=%Lx L=%Lx %s %s\n",
 414                                          type2name[entry->type], idx,
 415                                          phys_addr(entry), entry->pfn,
 416                                          entry->dev_addr, entry->size,
 417                                          dir2name[entry->direction],
 418                                          maperr2str[entry->map_err_type]);
 419                         }
 420                 }
 421
 422                 spin_unlock_irqrestore(&bucket->lock, flags);
 423         }
 424 }
 425
 426 /*
 427  * For each mapping (initial cacheline in the case of
 428  * dma_alloc_coherent/dma_map_page, initial cacheline in each page of a
 429  * scatterlist, or the cacheline specified in dma_map_single) insert
 430  * into this tree using the cacheline as the key. At
 431  * dma_unmap_{single|sg|page} or dma_free_coherent delete the entry.  If
 432  * the entry already exists at insertion time add a tag as a reference
 433  * count for the overlapping mappings.  For now, the overlap tracking
 434  * just ensures that 'unmaps' balance 'maps' before marking the
 435  * cacheline idle, but we should also be flagging overlaps as an API
 436  * violation.
 437  *
 438  * Memory usage is mostly constrained by the maximum number of available
 439  * dma-debug entries in that we need a free dma_debug_entry before
 440  * inserting into the tree.  In the case of dma_map_page and
 441  * dma_alloc_coherent there is only one dma_debug_entry and one
 442  * dma_active_cacheline entry to track per event.  dma_map_sg(), on the
 443  * other hand, consumes a single dma_debug_entry, but inserts 'nents'
 444  * entries into the tree.
 445  *
 446  * At any time debug_dma_assert_idle() can be called to trigger a
 447  * warning if any cachelines in the given page are in the active set.
 448  */
 449 static RADIX_TREE(dma_active_cacheline, GFP_NOWAIT);
 450 static DEFINE_SPINLOCK(radix_lock);
 451 #define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1)
 452 #define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT)
 453 #define CACHELINES_PER_PAGE (1 << CACHELINE_PER_PAGE_SHIFT)
 454
 455 static phys_addr_t to_cacheline_number(struct dma_debug_entry *entry)
 456 {
 457         return (entry->pfn << CACHELINE_PER_PAGE_SHIFT) +
 458                 (entry->offset >> L1_CACHE_SHIFT);
 459 }
 460
 461 static int active_cacheline_read_overlap(phys_addr_t cln)
 462 {
 463         int overlap = 0, i;
 464
 465         for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
 466                 if (radix_tree_tag_get(&dma_active_cacheline, cln, i))
 467                         overlap |= 1 << i;
 468         return overlap;
 469 }
 470
 471 static int active_cacheline_set_overlap(phys_addr_t cln, int overlap)
 472 {
 473         int i;
 474
 475         if (overlap > ACTIVE_CACHELINE_MAX_OVERLAP || overlap < 0)
 476                 return overlap;
 477
 478         for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
 479                 if (overlap & 1 << i)
 480                         radix_tree_tag_set(&dma_active_cacheline, cln, i);
 481                 else
 482                         radix_tree_tag_clear(&dma_active_cacheline, cln, i);
 483
 484         return overlap;
 485 }
 486
 487 static void active_cacheline_inc_overlap(phys_addr_t cln)
 488 {
 489         int overlap = active_cacheline_read_overlap(cln);
 490
 491         overlap = active_cacheline_set_overlap(cln, ++overlap);
 492
 493         /* If we overflowed the overlap counter then we're potentially
 494          * leaking dma-mappings.  Otherwise, if maps and unmaps are
 495          * balanced then this overflow may cause false negatives in
 496          * debug_dma_assert_idle() as the cacheline may be marked idle
 497          * prematurely.
 498          */
 499         WARN_ONCE(overlap > ACTIVE_CACHELINE_MAX_OVERLAP,
 500                   pr_fmt("exceeded %d overlapping mappings of cacheline %pa\n"),
 501                   ACTIVE_CACHELINE_MAX_OVERLAP, &cln);
 502 }
 503
 504 static int active_cacheline_dec_overlap(phys_addr_t cln)
 505 {
 506         int overlap = active_cacheline_read_overlap(cln);
 507
 508         return active_cacheline_set_overlap(cln, --overlap);
 509 }
 510
 511 static int active_cacheline_insert(struct dma_debug_entry *entry)
 512 {
 513         phys_addr_t cln = to_cacheline_number(entry);
 514         unsigned long flags;
 515         int rc;
 516
 517         /* If the device is not writing memory then we don't have any
 518          * concerns about the cpu consuming stale data.  This mitigates
 519          * legitimate usages of overlapping mappings.
 520          */
 521         if (entry->direction == DMA_TO_DEVICE)
 522                 return 0;
 523
 524         spin_lock_irqsave(&radix_lock, flags);
 525         rc = radix_tree_insert(&dma_active_cacheline, cln, entry);
 526         if (rc == -EEXIST)
 527                 active_cacheline_inc_overlap(cln);
 528         spin_unlock_irqrestore(&radix_lock, flags);
 529
 530         return rc;
 531 }
 532
 533 static void active_cacheline_remove(struct dma_debug_entry *entry)
 534 {
 535         phys_addr_t cln = to_cacheline_number(entry);
 536         unsigned long flags;
 537
 538         /* ...mirror the insert case */
 539         if (entry->direction == DMA_TO_DEVICE)
 540                 return;
 541
 542         spin_lock_irqsave(&radix_lock, flags);
 543         /* since we are counting overlaps the final put of the
 544          * cacheline will occur when the overlap count is 0.
 545          * active_cacheline_dec_overlap() returns -1 in that case
 546          */
 547         if (active_cacheline_dec_overlap(cln) < 0)
 548                 radix_tree_delete(&dma_active_cacheline, cln);
 549         spin_unlock_irqrestore(&radix_lock, flags);
 550 }
 551
 552 /**
 553  * debug_dma_assert_idle() - assert that a page is not undergoing dma
 554  * @page: page to lookup in the dma_active_cacheline tree
 555  *
 556  * Place a call to this routine in cases where the cpu touching the page
 557  * before the dma completes (page is dma_unmapped) will lead to data
 558  * corruption.
 559  */
 560 void debug_dma_assert_idle(struct page *page)
 561 {
 562         static struct dma_debug_entry *ents[CACHELINES_PER_PAGE];
 563         struct dma_debug_entry *entry = NULL;
 564         void **results = (void **) &ents;
 565         unsigned int nents, i;
 566         unsigned long flags;
 567         phys_addr_t cln;
 568
 569         if (dma_debug_disabled())
 570                 return;
 571
 572         if (!page)
 573                 return;
 574
 575         cln = (phys_addr_t) page_to_pfn(page) << CACHELINE_PER_PAGE_SHIFT;
 576         spin_lock_irqsave(&radix_lock, flags);
 577         nents = radix_tree_gang_lookup(&dma_active_cacheline, results, cln,
 578                                        CACHELINES_PER_PAGE);
 579         for (i = 0; i < nents; i++) {
 580                 phys_addr_t ent_cln = to_cacheline_number(ents[i]);
 581
 582                 if (ent_cln == cln) {
 583                         entry = ents[i];
 584                         break;
 585                 } else if (ent_cln >= cln + CACHELINES_PER_PAGE)
 586                         break;
 587         }
 588         spin_unlock_irqrestore(&radix_lock, flags);
 589
 590         if (!entry)
 591                 return;
 592
 593         cln = to_cacheline_number(entry);
 594         err_printk(entry->dev, entry,
 595                    "cpu touching an active dma mapped cacheline [cln=%pa]\n",
 596                    &cln);
 597 }
 598
 599 /*
 600  * Wrapper function for adding an entry to the hash.
 601  * This function takes care of locking itself.
 602  */
 603 static void add_dma_entry(struct dma_debug_entry *entry)
 604 {
 605         struct hash_bucket *bucket;
 606         unsigned long flags;
 607         int rc;
 608
 609         bucket = get_hash_bucket(entry, &flags);
 610         hash_bucket_add(bucket, entry);
 611         put_hash_bucket(bucket, &flags);
 612
 613         rc = active_cacheline_insert(entry);
 614         if (rc == -ENOMEM) {
 615                 pr_err("cacheline tracking ENOMEM, dma-debug disabled\n");
 616                 global_disable = true;
 617         }
 618
 619         /* TODO: report -EEXIST errors here as overlapping mappings are
 620          * not supported by the DMA API
 621          */
 622 }
 623
 624 static int dma_debug_create_entries(gfp_t gfp)
 625 {
 626         struct dma_debug_entry *entry;
 627         int i;
 628
 629         entry = (void *)get_zeroed_page(gfp);
 630         if (!entry)
 631                 return -ENOMEM;
 632
 633         for (i = 0; i < DMA_DEBUG_DYNAMIC_ENTRIES; i++)
 634                 list_add_tail(&entry[i].list, &free_entries);
 635
 636         num_free_entries += DMA_DEBUG_DYNAMIC_ENTRIES;
 637         nr_total_entries += DMA_DEBUG_DYNAMIC_ENTRIES;
 638
 639         return 0;
 640 }
 641
 642 static struct dma_debug_entry *__dma_entry_alloc(void)
 643 {
 644         struct dma_debug_entry *entry;
 645
 646         entry = list_entry(free_entries.next, struct dma_debug_entry, list);
 647         list_del(&entry->list);
 648         memset(entry, 0, sizeof(*entry));
 649
 650         num_free_entries -= 1;
 651         if (num_free_entries < min_free_entries)
 652                 min_free_entries = num_free_entries;
 653
 654         return entry;
 655 }
 656
 657 void __dma_entry_alloc_check_leak(void)
 658 {
 659         u32 tmp = nr_total_entries % nr_prealloc_entries;
 660
 661         /* Shout each time we tick over some multiple of the initial pool */
 662         if (tmp < DMA_DEBUG_DYNAMIC_ENTRIES) {
 663                 pr_info("dma_debug_entry pool grown to %u (%u00%%)\n",
 664                         nr_total_entries,
 665                         (nr_total_entries / nr_prealloc_entries));
 666         }
 667 }
 668
 669 /* struct dma_entry allocator
 670  *
 671  * The next two functions implement the allocator for
 672  * struct dma_debug_entries.
 673  */
 674 static struct dma_debug_entry *dma_entry_alloc(void)
 675 {
 676         struct dma_debug_entry *entry;
 677         unsigned long flags;
 678
 679         spin_lock_irqsave(&free_entries_lock, flags);
 680         if (num_free_entries == 0) {
 681                 if (dma_debug_create_entries(GFP_ATOMIC)) {
 682                         global_disable = true;
 683                         spin_unlock_irqrestore(&free_entries_lock, flags);
 684                         pr_err("debugging out of memory - disabling\n");
 685                         return NULL;
 686                 }
 687                 __dma_entry_alloc_check_leak();
 688         }
 689
 690         entry = __dma_entry_alloc();
 691
 692         spin_unlock_irqrestore(&free_entries_lock, flags);
 693
 694 #ifdef CONFIG_STACKTRACE
 695         entry->stack_len = stack_trace_save(entry->stack_entries,
 696                                             ARRAY_SIZE(entry->stack_entries),
 697                                             1);
 698 #endif
 699         return entry;
 700 }
 701
 702 static void dma_entry_free(struct dma_debug_entry *entry)
 703 {
 704         unsigned long flags;
 705
 706         active_cacheline_remove(entry);
 707
 708         /*
 709          * add to beginning of the list - this way the entries are
 710          * more likely cache hot when they are reallocated.
 711          */
 712         spin_lock_irqsave(&free_entries_lock, flags);
 713         list_add(&entry->list, &free_entries);
 714         num_free_entries += 1;
 715         spin_unlock_irqrestore(&free_entries_lock, flags);
 716 }
 717
 718 /*
 719  * DMA-API debugging init code
 720  *
 721  * The init code does two things:
 722  *   1. Initialize core data structures
 723  *   2. Preallocate a given number of dma_debug_entry structs
 724  */
 725
 726 static ssize_t filter_read(struct file *file, char __user *user_buf,
 727                            size_t count, loff_t *ppos)
 728 {
 729         char buf[NAME_MAX_LEN + 1];
 730         unsigned long flags;
 731         int len;
 732
 733         if (!current_driver_name[0])
 734                 return 0;
 735
 736         /*
 737          * We can't copy to userspace directly because current_driver_name can
 738          * only be read under the driver_name_lock with irqs disabled. So
 739          * create a temporary copy first.
 740          */
 741         read_lock_irqsave(&driver_name_lock, flags);
 742         len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
 743         read_unlock_irqrestore(&driver_name_lock, flags);
 744
 745         return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 746 }
 747
 748 static ssize_t filter_write(struct file *file, const char __user *userbuf,
 749                             size_t count, loff_t *ppos)
 750 {
 751         char buf[NAME_MAX_LEN];
 752         unsigned long flags;
 753         size_t len;
 754         int i;
 755
 756         /*
 757          * We can't copy from userspace directly. Access to
 758          * current_driver_name is protected with a write_lock with irqs
 759          * disabled. Since copy_from_user can fault and may sleep we
 760          * need to copy to temporary buffer first
 761          */
 762         len = min(count, (size_t)(NAME_MAX_LEN - 1));
 763         if (copy_from_user(buf, userbuf, len))
 764                 return -EFAULT;
 765
 766         buf[len] = 0;
 767
 768         write_lock_irqsave(&driver_name_lock, flags);
 769
 770         /*
 771          * Now handle the string we got from userspace very carefully.
 772          * The rules are:
 773          *         - only use the first token we got
 774          *         - token delimiter is everything looking like a space
 775          *           character (' ', '\n', '\t' ...)
 776          *
 777          */
 778         if (!isalnum(buf[0])) {
 779                 /*
 780                  * If the first character userspace gave us is not
 781                  * alphanumerical then assume the filter should be
 782                  * switched off.
 783                  */
 784                 if (current_driver_name[0])
 785                         pr_info("switching off dma-debug driver filter\n");
 786                 current_driver_name[0] = 0;
 787                 current_driver = NULL;
 788                 goto out_unlock;
 789         }
 790
 791         /*
 792          * Now parse out the first token and use it as the name for the
 793          * driver to filter for.
 794          */
 795         for (i = 0; i < NAME_MAX_LEN - 1; ++i) {
 796                 current_driver_name[i] = buf[i];
 797                 if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
 798                         break;
 799         }
 800         current_driver_name[i] = 0;
 801         current_driver = NULL;
 802
 803         pr_info("enable driver filter for driver [%s]\n",
 804                 current_driver_name);
 805
 806 out_unlock:
 807         write_unlock_irqrestore(&driver_name_lock, flags);
 808
 809         return count;
 810 }
 811
 812 static const struct file_operations filter_fops = {
 813         .read  = filter_read,
 814         .write = filter_write,
 815         .llseek = default_llseek,
 816 };
 817
 818 static int dump_show(struct seq_file *seq, void *v)
 819 {
 820         int idx;
 821
 822         for (idx = 0; idx < HASH_SIZE; idx++) {
 823                 struct hash_bucket *bucket = &dma_entry_hash[idx];
 824                 struct dma_debug_entry *entry;
 825                 unsigned long flags;
 826
 827                 spin_lock_irqsave(&bucket->lock, flags);
 828                 list_for_each_entry(entry, &bucket->list, list) {
 829                         seq_printf(seq,
 830                                    "%s %s %s idx %d P=%llx N=%lx D=%llx L=%llx %s %s\n",
 831                                    dev_name(entry->dev),
 832                                    dev_driver_string(entry->dev),
 833                                    type2name[entry->type], idx,
 834                                    phys_addr(entry), entry->pfn,
 835                                    entry->dev_addr, entry->size,
 836                                    dir2name[entry->direction],
 837                                    maperr2str[entry->map_err_type]);
 838                 }
 839                 spin_unlock_irqrestore(&bucket->lock, flags);
 840         }
 841         return 0;
 842 }
 843 DEFINE_SHOW_ATTRIBUTE(dump);
 844
 845 static void dma_debug_fs_init(void)
 846 {
 847         struct dentry *dentry = debugfs_create_dir("dma-api", NULL);
 848
 849         debugfs_create_bool("disabled", 0444, dentry, &global_disable);
 850         debugfs_create_u32("error_count", 0444, dentry, &error_count);
 851         debugfs_create_u32("all_errors", 0644, dentry, &show_all_errors);
 852         debugfs_create_u32("num_errors", 0644, dentry, &show_num_errors);
 853         debugfs_create_u32("num_free_entries", 0444, dentry, &num_free_entries);
 854         debugfs_create_u32("min_free_entries", 0444, dentry, &min_free_entries);
 855         debugfs_create_u32("nr_total_entries", 0444, dentry, &nr_total_entries);
 856         debugfs_create_file("driver_filter", 0644, dentry, NULL, &filter_fops);
 857         debugfs_create_file("dump", 0444, dentry, NULL, &dump_fops);
 858 }
 859
 860 static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry)
 861 {
 862         struct dma_debug_entry *entry;
 863         unsigned long flags;
 864         int count = 0, i;
 865
 866         for (i = 0; i < HASH_SIZE; ++i) {
 867                 spin_lock_irqsave(&dma_entry_hash[i].lock, flags);
 868                 list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
 869                         if (entry->dev == dev) {
 870                                 count += 1;
 871                                 *out_entry = entry;
 872                         }
 873                 }
 874                 spin_unlock_irqrestore(&dma_entry_hash[i].lock, flags);
 875         }
 876
 877         return count;
 878 }
 879
 880 static int dma_debug_device_change(struct notifier_block *nb, unsigned long action, void *data)
 881 {
 882         struct device *dev = data;
 883         struct dma_debug_entry *uninitialized_var(entry);
 884         int count;
 885
 886         if (dma_debug_disabled())
 887                 return 0;
 888
 889         switch (action) {
 890         case BUS_NOTIFY_UNBOUND_DRIVER:
 891                 count = device_dma_allocations(dev, &entry);
 892                 if (count == 0)
 893                         break;
 894                 err_printk(dev, entry, "device driver has pending "
 895                                 "DMA allocations while released from device "
 896                                 "[count=%d]\n"
 897                                 "One of leaked entries details: "
 898                                 "[device address=0x%016llx] [size=%llu bytes] "
 899                                 "[mapped with %s] [mapped as %s]\n",
 900                         count, entry->dev_addr, entry->size,
 901                         dir2name[entry->direction], type2name[entry->type]);
 902                 break;
 903         default:
 904                 break;
 905         }
 906
 907         return 0;
 908 }
 909
 910 void dma_debug_add_bus(struct bus_type *bus)
 911 {
 912         struct notifier_block *nb;
 913
 914         if (dma_debug_disabled())
 915                 return;
 916
 917         nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
 918         if (nb == NULL) {
 919                 pr_err("dma_debug_add_bus: out of memory\n");
 920                 return;
 921         }
 922
 923         nb->notifier_call = dma_debug_device_change;
 924
 925         bus_register_notifier(bus, nb);
 926 }
 927
 928 static int dma_debug_init(void)
 929 {
 930         int i, nr_pages;
 931
 932         /* Do not use dma_debug_initialized here, since we really want to be
 933          * called to set dma_debug_initialized
 934          */
 935         if (global_disable)
 936                 return 0;
 937
 938         for (i = 0; i < HASH_SIZE; ++i) {
 939                 INIT_LIST_HEAD(&dma_entry_hash[i].list);
 940                 spin_lock_init(&dma_entry_hash[i].lock);
 941         }
 942
 943         dma_debug_fs_init();
 944
 945         nr_pages = DIV_ROUND_UP(nr_prealloc_entries, DMA_DEBUG_DYNAMIC_ENTRIES);
 946         for (i = 0; i < nr_pages; ++i)
 947                 dma_debug_create_entries(GFP_KERNEL);
 948         if (num_free_entries >= nr_prealloc_entries) {
 949                 pr_info("preallocated %d debug entries\n", nr_total_entries);
 950         } else if (num_free_entries > 0) {
 951                 pr_warn("%d debug entries requested but only %d allocated\n",
 952                         nr_prealloc_entries, nr_total_entries);
 953         } else {
 954                 pr_err("debugging out of memory error - disabled\n");
 955                 global_disable = true;
 956
 957                 return 0;
 958         }
 959         min_free_entries = num_free_entries;
 960
 961         dma_debug_initialized = true;
 962
 963         pr_info("debugging enabled by kernel config\n");
 964         return 0;
 965 }
 966 core_initcall(dma_debug_init);
 967
 968 static __init int dma_debug_cmdline(char *str)
 969 {
 970         if (!str)
 971                 return -EINVAL;
 972
 973         if (strncmp(str, "off", 3) == 0) {
 974                 pr_info("debugging disabled on kernel command line\n");
 975                 global_disable = true;
 976         }
 977
 978         return 0;
 979 }
 980
 981 static __init int dma_debug_entries_cmdline(char *str)
 982 {
 983         if (!str)
 984                 return -EINVAL;
 985         if (!get_option(&str, &nr_prealloc_entries))
 986                 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
 987         return 0;
 988 }
 989
 990 __setup("dma_debug=", dma_debug_cmdline);
 991 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
 992
 993 static void check_unmap(struct dma_debug_entry *ref)
 994 {
 995         struct dma_debug_entry *entry;
 996         struct hash_bucket *bucket;
 997         unsigned long flags;
 998
 999         bucket = get_hash_bucket(ref, &flags);
1000         entry = bucket_find_exact(bucket, ref);
1001
1002         if (!entry) {
1003                 /* must drop lock before calling dma_mapping_error */
1004                 put_hash_bucket(bucket, &flags);
1005
1006                 if (dma_mapping_error(ref->dev, ref->dev_addr)) {
1007                         err_printk(ref->dev, NULL,
1008                                    "device driver tries to free an "
1009                                    "invalid DMA memory address\n");
1010                 } else {
1011                         err_printk(ref->dev, NULL,
1012                                    "device driver tries to free DMA "
1013                                    "memory it has not allocated [device "
1014                                    "address=0x%016llx] [size=%llu bytes]\n",
1015                                    ref->dev_addr, ref->size);
1016                 }
1017                 return;
1018         }
1019
1020         if (ref->size != entry->size) {
1021                 err_printk(ref->dev, entry, "device driver frees "
1022                            "DMA memory with different size "
1023                            "[device address=0x%016llx] [map size=%llu bytes] "
1024                            "[unmap size=%llu bytes]\n",
1025                            ref->dev_addr, entry->size, ref->size);
1026         }
1027
1028         if (ref->type != entry->type) {
1029                 err_printk(ref->dev, entry, "device driver frees "
1030                            "DMA memory with wrong function "
1031                            "[device address=0x%016llx] [size=%llu bytes] "
1032                            "[mapped as %s] [unmapped as %s]\n",
1033                            ref->dev_addr, ref->size,
1034                            type2name[entry->type], type2name[ref->type]);
1035         } else if ((entry->type == dma_debug_coherent) &&
1036                    (phys_addr(ref) != phys_addr(entry))) {
1037                 err_printk(ref->dev, entry, "device driver frees "
1038                            "DMA memory with different CPU address "
1039                            "[device address=0x%016llx] [size=%llu bytes] "
1040                            "[cpu alloc address=0x%016llx] "
1041                            "[cpu free address=0x%016llx]",
1042                            ref->dev_addr, ref->size,
1043                            phys_addr(entry),
1044                            phys_addr(ref));
1045         }
1046
1047         if (ref->sg_call_ents && ref->type == dma_debug_sg &&
1048             ref->sg_call_ents != entry->sg_call_ents) {
1049                 err_printk(ref->dev, entry, "device driver frees "
1050                            "DMA sg list with different entry count "
1051                            "[map count=%d] [unmap count=%d]\n",
1052                            entry->sg_call_ents, ref->sg_call_ents);
1053         }
1054
1055         /*
1056          * This may be no bug in reality - but most implementations of the
1057          * DMA API don't handle this properly, so check for it here
1058          */
1059         if (ref->direction != entry->direction) {
1060                 err_printk(ref->dev, entry, "device driver frees "
1061                            "DMA memory with different direction "
1062                            "[device address=0x%016llx] [size=%llu bytes] "
1063                            "[mapped with %s] [unmapped with %s]\n",
1064                            ref->dev_addr, ref->size,
1065                            dir2name[entry->direction],
1066                            dir2name[ref->direction]);
1067         }
1068
1069         /*
1070          * Drivers should use dma_mapping_error() to check the returned
1071          * addresses of dma_map_single() and dma_map_page().
1072          * If not, print this warning message. See Documentation/DMA-API.txt.
1073          */
1074         if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1075                 err_printk(ref->dev, entry,
1076                            "device driver failed to check map error"
1077                            "[device address=0x%016llx] [size=%llu bytes] "
1078                            "[mapped as %s]",
1079                            ref->dev_addr, ref->size,
1080                            type2name[entry->type]);
1081         }
1082
1083         hash_bucket_del(entry);
1084         dma_entry_free(entry);
1085
1086         put_hash_bucket(bucket, &flags);
1087 }
1088
1089 static void check_for_stack(struct device *dev,
1090                             struct page *page, size_t offset)
1091 {
1092         void *addr;
1093         struct vm_struct *stack_vm_area = task_stack_vm_area(current);
1094
1095         if (!stack_vm_area) {
1096                 /* Stack is direct-mapped. */
1097                 if (PageHighMem(page))
1098                         return;
1099                 addr = page_address(page) + offset;
1100                 if (object_is_on_stack(addr))
1101                         err_printk(dev, NULL, "device driver maps memory from stack [addr=%p]\n", addr);
1102         } else {
1103                 /* Stack is vmalloced. */
1104                 int i;
1105
1106                 for (i = 0; i < stack_vm_area->nr_pages; i++) {
1107                         if (page != stack_vm_area->pages[i])
1108                                 continue;
1109
1110                         addr = (u8 *)current->stack + i * PAGE_SIZE + offset;
1111                         err_printk(dev, NULL, "device driver maps memory from stack [probable addr=%p]\n", addr);
1112                         break;
1113                 }
1114         }
1115 }
1116
1117 static inline bool overlap(void *addr, unsigned long len, void *start, void *end)
1118 {
1119         unsigned long a1 = (unsigned long)addr;
1120         unsigned long b1 = a1 + len;
1121         unsigned long a2 = (unsigned long)start;
1122         unsigned long b2 = (unsigned long)end;
1123
1124         return !(b1 <= a2 || a1 >= b2);
1125 }
1126
1127 static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
1128 {
1129         if (overlap(addr, len, _stext, _etext) ||
1130             overlap(addr, len, __start_rodata, __end_rodata))
1131                 err_printk(dev, NULL, "device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
1132 }
1133
1134 static void check_sync(struct device *dev,
1135                        struct dma_debug_entry *ref,
1136                        bool to_cpu)
1137 {
1138         struct dma_debug_entry *entry;
1139         struct hash_bucket *bucket;
1140         unsigned long flags;
1141
1142         bucket = get_hash_bucket(ref, &flags);
1143
1144         entry = bucket_find_contain(&bucket, ref, &flags);
1145
1146         if (!entry) {
1147                 err_printk(dev, NULL, "device driver tries "
1148                                 "to sync DMA memory it has not allocated "
1149                                 "[device address=0x%016llx] [size=%llu bytes]\n",
1150                                 (unsigned long long)ref->dev_addr, ref->size);
1151                 goto out;
1152         }
1153
1154         if (ref->size > entry->size) {
1155                 err_printk(dev, entry, "device driver syncs"
1156                                 " DMA memory outside allocated range "
1157                                 "[device address=0x%016llx] "
1158                                 "[allocation size=%llu bytes] "
1159                                 "[sync offset+size=%llu]\n",
1160                                 entry->dev_addr, entry->size,
1161                                 ref->size);
1162         }
1163
1164         if (entry->direction == DMA_BIDIRECTIONAL)
1165                 goto out;
1166
1167         if (ref->direction != entry->direction) {
1168                 err_printk(dev, entry, "device driver syncs "
1169                                 "DMA memory with different direction "
1170                                 "[device address=0x%016llx] [size=%llu bytes] "
1171                                 "[mapped with %s] [synced with %s]\n",
1172                                 (unsigned long long)ref->dev_addr, entry->size,
1173                                 dir2name[entry->direction],
1174                                 dir2name[ref->direction]);
1175         }
1176
1177         if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
1178                       !(ref->direction == DMA_TO_DEVICE))
1179                 err_printk(dev, entry, "device driver syncs "
1180                                 "device read-only DMA memory for cpu "
1181                                 "[device address=0x%016llx] [size=%llu bytes] "
1182                                 "[mapped with %s] [synced with %s]\n",
1183                                 (unsigned long long)ref->dev_addr, entry->size,
1184                                 dir2name[entry->direction],
1185                                 dir2name[ref->direction]);
1186
1187         if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
1188                        !(ref->direction == DMA_FROM_DEVICE))
1189                 err_printk(dev, entry, "device driver syncs "
1190                                 "device write-only DMA memory to device "
1191                                 "[device address=0x%016llx] [size=%llu bytes] "
1192                                 "[mapped with %s] [synced with %s]\n",
1193                                 (unsigned long long)ref->dev_addr, entry->size,
1194                                 dir2name[entry->direction],
1195                                 dir2name[ref->direction]);
1196
1197         if (ref->sg_call_ents && ref->type == dma_debug_sg &&
1198             ref->sg_call_ents != entry->sg_call_ents) {
1199                 err_printk(ref->dev, entry, "device driver syncs "
1200                            "DMA sg list with different entry count "
1201                            "[map count=%d] [sync count=%d]\n",
1202                            entry->sg_call_ents, ref->sg_call_ents);
1203         }
1204
1205 out:
1206         put_hash_bucket(bucket, &flags);
1207 }
1208
1209 static void check_sg_segment(struct device *dev, struct scatterlist *sg)
1210 {
1211 #ifdef CONFIG_DMA_API_DEBUG_SG
1212         unsigned int max_seg = dma_get_max_seg_size(dev);
1213         u64 start, end, boundary = dma_get_seg_boundary(dev);
1214
1215         /*
1216          * Either the driver forgot to set dma_parms appropriately, or
1217          * whoever generated the list forgot to check them.
1218          */
1219         if (sg->length > max_seg)
1220                 err_printk(dev, NULL, "mapping sg segment longer than device claims to support [len=%u] [max=%u]\n",
1221                            sg->length, max_seg);
1222         /*
1223          * In some cases this could potentially be the DMA API
1224          * implementation's fault, but it would usually imply that
1225          * the scatterlist was built inappropriately to begin with.
1226          */
1227         start = sg_dma_address(sg);
1228         end = start + sg_dma_len(sg) - 1;
1229         if ((start ^ end) & ~boundary)
1230                 err_printk(dev, NULL, "mapping sg segment across boundary [start=0x%016llx] [end=0x%016llx] [boundary=0x%016llx]\n",
1231                            start, end, boundary);
1232 #endif
1233 }
1234
1235 void debug_dma_map_single(struct device *dev, const void *addr,
1236                             unsigned long len)
1237 {
1238         if (unlikely(dma_debug_disabled()))
1239                 return;
1240
1241         if (!virt_addr_valid(addr))
1242                 err_printk(dev, NULL, "device driver maps memory from invalid area [addr=%p] [len=%lu]\n",
1243                            addr, len);
1244
1245         if (is_vmalloc_addr(addr))
1246                 err_printk(dev, NULL, "device driver maps memory from vmalloc area [addr=%p] [len=%lu]\n",
1247                            addr, len);
1248 }
1249 EXPORT_SYMBOL(debug_dma_map_single);
1250
1251 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
1252                         size_t size, int direction, dma_addr_t dma_addr)
1253 {
1254         struct dma_debug_entry *entry;
1255
1256         if (unlikely(dma_debug_disabled()))
1257                 return;
1258
1259         if (dma_mapping_error(dev, dma_addr))
1260                 return;
1261
1262         entry = dma_entry_alloc();
1263         if (!entry)
1264                 return;
1265
1266         entry->dev       = dev;
1267         entry->type      = dma_debug_single;
1268         entry->pfn       = page_to_pfn(page);
1269         entry->offset    = offset,
1270         entry->dev_addr  = dma_addr;
1271         entry->size      = size;
1272         entry->direction = direction;
1273         entry->map_err_type = MAP_ERR_NOT_CHECKED;
1274
1275         check_for_stack(dev, page, offset);
1276
1277         if (!PageHighMem(page)) {
1278                 void *addr = page_address(page) + offset;
1279
1280                 check_for_illegal_area(dev, addr, size);
1281         }
1282
1283         add_dma_entry(entry);
1284 }
1285 EXPORT_SYMBOL(debug_dma_map_page);
1286
1287 void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
1288 {
1289         struct dma_debug_entry ref;
1290         struct dma_debug_entry *entry;
1291         struct hash_bucket *bucket;
1292         unsigned long flags;
1293
1294         if (unlikely(dma_debug_disabled()))
1295                 return;
1296
1297         ref.dev = dev;
1298         ref.dev_addr = dma_addr;
1299         bucket = get_hash_bucket(&ref, &flags);
1300
1301         list_for_each_entry(entry, &bucket->list, list) {
1302                 if (!exact_match(&ref, entry))
1303                         continue;
1304
1305                 /*
1306                  * The same physical address can be mapped multiple
1307                  * times. Without a hardware IOMMU this results in the
1308                  * same device addresses being put into the dma-debug
1309                  * hash multiple times too. This can result in false
1310                  * positives being reported. Therefore we implement a
1311                  * best-fit algorithm here which updates the first entry
1312                  * from the hash which fits the reference value and is
1313                  * not currently listed as being checked.
1314                  */
1315                 if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1316                         entry->map_err_type = MAP_ERR_CHECKED;
1317                         break;
1318                 }
1319         }
1320
1321         put_hash_bucket(bucket, &flags);
1322 }
1323 EXPORT_SYMBOL(debug_dma_mapping_error);
1324
1325 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
1326                           size_t size, int direction)
1327 {
1328         struct dma_debug_entry ref = {
1329                 .type           = dma_debug_single,
1330                 .dev            = dev,
1331                 .dev_addr       = addr,
1332                 .size           = size,
1333                 .direction      = direction,
1334         };
1335
1336         if (unlikely(dma_debug_disabled()))
1337                 return;
1338         check_unmap(&ref);
1339 }
1340 EXPORT_SYMBOL(debug_dma_unmap_page);
1341
1342 void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
1343                       int nents, int mapped_ents, int direction)
1344 {
1345         struct dma_debug_entry *entry;
1346         struct scatterlist *s;
1347         int i;
1348
1349         if (unlikely(dma_debug_disabled()))
1350                 return;
1351
1352         for_each_sg(sg, s, mapped_ents, i) {
1353                 entry = dma_entry_alloc();
1354                 if (!entry)
1355                         return;
1356
1357                 entry->type           = dma_debug_sg;
1358                 entry->dev            = dev;
1359                 entry->pfn            = page_to_pfn(sg_page(s));
1360                 entry->offset         = s->offset,
1361                 entry->size           = sg_dma_len(s);
1362                 entry->dev_addr       = sg_dma_address(s);
1363                 entry->direction      = direction;
1364                 entry->sg_call_ents   = nents;
1365                 entry->sg_mapped_ents = mapped_ents;
1366
1367                 check_for_stack(dev, sg_page(s), s->offset);
1368
1369                 if (!PageHighMem(sg_page(s))) {
1370                         check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
1371                 }
1372
1373                 check_sg_segment(dev, s);
1374
1375                 add_dma_entry(entry);
1376         }
1377 }
1378 EXPORT_SYMBOL(debug_dma_map_sg);
1379
1380 static int get_nr_mapped_entries(struct device *dev,
1381                                  struct dma_debug_entry *ref)
1382 {
1383         struct dma_debug_entry *entry;
1384         struct hash_bucket *bucket;
1385         unsigned long flags;
1386         int mapped_ents;
1387
1388         bucket       = get_hash_bucket(ref, &flags);
1389         entry        = bucket_find_exact(bucket, ref);
1390         mapped_ents  = 0;
1391
1392         if (entry)
1393                 mapped_ents = entry->sg_mapped_ents;
1394         put_hash_bucket(bucket, &flags);
1395
1396         return mapped_ents;
1397 }
1398
1399 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
1400                         int nelems, int dir)
1401 {
1402         struct scatterlist *s;
1403         int mapped_ents = 0, i;
1404
1405         if (unlikely(dma_debug_disabled()))
1406                 return;
1407
1408         for_each_sg(sglist, s, nelems, i) {
1409
1410                 struct dma_debug_entry ref = {
1411                         .type           = dma_debug_sg,
1412                         .dev            = dev,
1413                         .pfn            = page_to_pfn(sg_page(s)),
1414                         .offset         = s->offset,
1415                         .dev_addr       = sg_dma_address(s),
1416                         .size           = sg_dma_len(s),
1417                         .direction      = dir,
1418                         .sg_call_ents   = nelems,
1419                 };
1420
1421                 if (mapped_ents && i >= mapped_ents)
1422                         break;
1423
1424                 if (!i)
1425                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1426
1427                 check_unmap(&ref);
1428         }
1429 }
1430 EXPORT_SYMBOL(debug_dma_unmap_sg);
1431
1432 void debug_dma_alloc_coherent(struct device *dev, size_t size,
1433                               dma_addr_t dma_addr, void *virt)
1434 {
1435         struct dma_debug_entry *entry;
1436
1437         if (unlikely(dma_debug_disabled()))
1438                 return;
1439
1440         if (unlikely(virt == NULL))
1441                 return;
1442
1443         /* handle vmalloc and linear addresses */
1444         if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
1445                 return;
1446
1447         entry = dma_entry_alloc();
1448         if (!entry)
1449                 return;
1450
1451         entry->type      = dma_debug_coherent;
1452         entry->dev       = dev;
1453         entry->offset    = offset_in_page(virt);
1454         entry->size      = size;
1455         entry->dev_addr  = dma_addr;
1456         entry->direction = DMA_BIDIRECTIONAL;
1457
1458         if (is_vmalloc_addr(virt))
1459                 entry->pfn = vmalloc_to_pfn(virt);
1460         else
1461                 entry->pfn = page_to_pfn(virt_to_page(virt));
1462
1463         add_dma_entry(entry);
1464 }
1465
1466 void debug_dma_free_coherent(struct device *dev, size_t size,
1467                          void *virt, dma_addr_t addr)
1468 {
1469         struct dma_debug_entry ref = {
1470                 .type           = dma_debug_coherent,
1471                 .dev            = dev,
1472                 .offset         = offset_in_page(virt),
1473                 .dev_addr       = addr,
1474                 .size           = size,
1475                 .direction      = DMA_BIDIRECTIONAL,
1476         };
1477
1478         /* handle vmalloc and linear addresses */
1479         if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt))
1480                 return;
1481
1482         if (is_vmalloc_addr(virt))
1483                 ref.pfn = vmalloc_to_pfn(virt);
1484         else
1485                 ref.pfn = page_to_pfn(virt_to_page(virt));
1486
1487         if (unlikely(dma_debug_disabled()))
1488                 return;
1489
1490         check_unmap(&ref);
1491 }
1492
1493 void debug_dma_map_resource(struct device *dev, phys_addr_t addr, size_t size,
1494                             int direction, dma_addr_t dma_addr)
1495 {
1496         struct dma_debug_entry *entry;
1497
1498         if (unlikely(dma_debug_disabled()))
1499                 return;
1500
1501         entry = dma_entry_alloc();
1502         if (!entry)
1503                 return;
1504
1505         entry->type             = dma_debug_resource;
1506         entry->dev              = dev;
1507         entry->pfn              = PHYS_PFN(addr);
1508         entry->offset           = offset_in_page(addr);
1509         entry->size             = size;
1510         entry->dev_addr         = dma_addr;
1511         entry->direction        = direction;
1512         entry->map_err_type     = MAP_ERR_NOT_CHECKED;
1513
1514         add_dma_entry(entry);
1515 }
1516 EXPORT_SYMBOL(debug_dma_map_resource);
1517
1518 void debug_dma_unmap_resource(struct device *dev, dma_addr_t dma_addr,
1519                               size_t size, int direction)
1520 {
1521         struct dma_debug_entry ref = {
1522                 .type           = dma_debug_resource,
1523                 .dev            = dev,
1524                 .dev_addr       = dma_addr,
1525                 .size           = size,
1526                 .direction      = direction,
1527         };
1528
1529         if (unlikely(dma_debug_disabled()))
1530                 return;
1531
1532         check_unmap(&ref);
1533 }
1534 EXPORT_SYMBOL(debug_dma_unmap_resource);
1535
1536 void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
1537                                    size_t size, int direction)
1538 {
1539         struct dma_debug_entry ref;
1540
1541         if (unlikely(dma_debug_disabled()))
1542                 return;
1543
1544         ref.type         = dma_debug_single;
1545         ref.dev          = dev;
1546         ref.dev_addr     = dma_handle;
1547         ref.size         = size;
1548         ref.direction    = direction;
1549         ref.sg_call_ents = 0;
1550
1551         check_sync(dev, &ref, true);
1552 }
1553 EXPORT_SYMBOL(debug_dma_sync_single_for_cpu);
1554
1555 void debug_dma_sync_single_for_device(struct device *dev,
1556                                       dma_addr_t dma_handle, size_t size,
1557                                       int direction)
1558 {
1559         struct dma_debug_entry ref;
1560
1561         if (unlikely(dma_debug_disabled()))
1562                 return;
1563
1564         ref.type         = dma_debug_single;
1565         ref.dev          = dev;
1566         ref.dev_addr     = dma_handle;
1567         ref.size         = size;
1568         ref.direction    = direction;
1569         ref.sg_call_ents = 0;
1570
1571         check_sync(dev, &ref, false);
1572 }
1573 EXPORT_SYMBOL(debug_dma_sync_single_for_device);
1574
1575 void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
1576                                int nelems, int direction)
1577 {
1578         struct scatterlist *s;
1579         int mapped_ents = 0, i;
1580
1581         if (unlikely(dma_debug_disabled()))
1582                 return;
1583
1584         for_each_sg(sg, s, nelems, i) {
1585
1586                 struct dma_debug_entry ref = {
1587                         .type           = dma_debug_sg,
1588                         .dev            = dev,
1589                         .pfn            = page_to_pfn(sg_page(s)),
1590                         .offset         = s->offset,
1591                         .dev_addr       = sg_dma_address(s),
1592                         .size           = sg_dma_len(s),
1593                         .direction      = direction,
1594                         .sg_call_ents   = nelems,
1595                 };
1596
1597                 if (!i)
1598                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1599
1600                 if (i >= mapped_ents)
1601                         break;
1602
1603                 check_sync(dev, &ref, true);
1604         }
1605 }
1606 EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
1607
1608 void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
1609                                   int nelems, int direction)
1610 {
1611         struct scatterlist *s;
1612         int mapped_ents = 0, i;
1613
1614         if (unlikely(dma_debug_disabled()))
1615                 return;
1616
1617         for_each_sg(sg, s, nelems, i) {
1618
1619                 struct dma_debug_entry ref = {
1620                         .type           = dma_debug_sg,
1621                         .dev            = dev,
1622                         .pfn            = page_to_pfn(sg_page(s)),
1623                         .offset         = s->offset,
1624                         .dev_addr       = sg_dma_address(s),
1625                         .size           = sg_dma_len(s),
1626                         .direction      = direction,
1627                         .sg_call_ents   = nelems,
1628                 };
1629                 if (!i)
1630                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1631
1632                 if (i >= mapped_ents)
1633                         break;
1634
1635                 check_sync(dev, &ref, false);
1636         }
1637 }
1638 EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
1639
1640 static int __init dma_debug_driver_setup(char *str)
1641 {
1642         int i;
1643
1644         for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
1645                 current_driver_name[i] = *str;
1646                 if (*str == 0)
1647                         break;
1648         }
1649
1650         if (current_driver_name[0])
1651                 pr_info("enable driver filter for driver [%s]\n",
1652                         current_driver_name);
1653
1654
1655         return 1;
1656 }
1657 __setup("dma_debug_driver=", dma_debug_driver_setup);