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 };
  48
  49 enum map_err_types {
  50         MAP_ERR_CHECK_NOT_APPLICABLE,
  51         MAP_ERR_NOT_CHECKED,
  52         MAP_ERR_CHECKED,
  53 };
  54
  55 #define DMA_DEBUG_STACKTRACE_ENTRIES 5
  56
  57 /**
  58  * struct dma_debug_entry - track a dma_map* or dma_alloc_coherent mapping
  59  * @list: node on pre-allocated free_entries list
  60  * @dev: 'dev' argument to dma_map_{page|single|sg} or dma_alloc_coherent
  61  * @type: single, page, sg, coherent
  62  * @pfn: page frame of the start address
  63  * @offset: offset of mapping relative to pfn
  64  * @size: length of the mapping
  65  * @direction: enum dma_data_direction
  66  * @sg_call_ents: 'nents' from dma_map_sg
  67  * @sg_mapped_ents: 'mapped_ents' from dma_map_sg
  68  * @map_err_type: track whether dma_mapping_error() was checked
  69  * @stacktrace: support backtraces when a violation is detected
  70  */
  71 struct dma_debug_entry {
  72         struct list_head list;
  73         struct device    *dev;
  74         int              type;
  75         unsigned long    pfn;
  76         size_t           offset;
  77         u64              dev_addr;
  78         u64              size;
  79         int              direction;
  80         int              sg_call_ents;
  81         int              sg_mapped_ents;
  82         enum map_err_types  map_err_type;
  83 #ifdef CONFIG_STACKTRACE
  84         struct           stack_trace stacktrace;
  85         unsigned long    st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
  86 #endif
  87 };
  88
  89 typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *);
  90
  91 struct hash_bucket {
  92         struct list_head list;
  93         spinlock_t lock;
  94 } ____cacheline_aligned_in_smp;
  95
  96 /* Hash list to save the allocated dma addresses */
  97 static struct hash_bucket dma_entry_hash[HASH_SIZE];
  98 /* List of pre-allocated dma_debug_entry's */
  99 static LIST_HEAD(free_entries);
 100 /* Lock for the list above */
 101 static DEFINE_SPINLOCK(free_entries_lock);
 102
 103 /* Global disable flag - will be set in case of an error */
 104 static bool global_disable __read_mostly;
 105
 106 /* Early initialization disable flag, set at the end of dma_debug_init */
 107 static bool dma_debug_initialized __read_mostly;
 108
 109 static inline bool dma_debug_disabled(void)
 110 {
 111         return global_disable || !dma_debug_initialized;
 112 }
 113
 114 /* Global error count */
 115 static u32 error_count;
 116
 117 /* Global error show enable*/
 118 static u32 show_all_errors __read_mostly;
 119 /* Number of errors to show */
 120 static u32 show_num_errors = 1;
 121
 122 static u32 num_free_entries;
 123 static u32 min_free_entries;
 124 static u32 nr_total_entries;
 125
 126 /* number of preallocated entries requested by kernel cmdline */
 127 static u32 req_entries;
 128
 129 /* debugfs dentry's for the stuff above */
 130 static struct dentry *dma_debug_dent        __read_mostly;
 131 static struct dentry *global_disable_dent   __read_mostly;
 132 static struct dentry *error_count_dent      __read_mostly;
 133 static struct dentry *show_all_errors_dent  __read_mostly;
 134 static struct dentry *show_num_errors_dent  __read_mostly;
 135 static struct dentry *num_free_entries_dent __read_mostly;
 136 static struct dentry *min_free_entries_dent __read_mostly;
 137 static struct dentry *filter_dent           __read_mostly;
 138
 139 /* per-driver filter related state */
 140
 141 #define NAME_MAX_LEN    64
 142
 143 static char                  current_driver_name[NAME_MAX_LEN] __read_mostly;
 144 static struct device_driver *current_driver                    __read_mostly;
 145
 146 static DEFINE_RWLOCK(driver_name_lock);
 147
 148 static const char *const maperr2str[] = {
 149         [MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
 150         [MAP_ERR_NOT_CHECKED] = "dma map error not checked",
 151         [MAP_ERR_CHECKED] = "dma map error checked",
 152 };
 153
 154 static const char *type2name[4] = { "single", "page",
 155                                     "scather-gather", "coherent" };
 156
 157 static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
 158                                    "DMA_FROM_DEVICE", "DMA_NONE" };
 159
 160 /*
 161  * The access to some variables in this macro is racy. We can't use atomic_t
 162  * here because all these variables are exported to debugfs. Some of them even
 163  * writeable. This is also the reason why a lock won't help much. But anyway,
 164  * the races are no big deal. Here is why:
 165  *
 166  *   error_count: the addition is racy, but the worst thing that can happen is
 167  *                that we don't count some errors
 168  *   show_num_errors: the subtraction is racy. Also no big deal because in
 169  *                    worst case this will result in one warning more in the
 170  *                    system log than the user configured. This variable is
 171  *                    writeable via debugfs.
 172  */
 173 static inline void dump_entry_trace(struct dma_debug_entry *entry)
 174 {
 175 #ifdef CONFIG_STACKTRACE
 176         if (entry) {
 177                 pr_warning("Mapped at:\n");
 178                 print_stack_trace(&entry->stacktrace, 0);
 179         }
 180 #endif
 181 }
 182
 183 static bool driver_filter(struct device *dev)
 184 {
 185         struct device_driver *drv;
 186         unsigned long flags;
 187         bool ret;
 188
 189         /* driver filter off */
 190         if (likely(!current_driver_name[0]))
 191                 return true;
 192
 193         /* driver filter on and initialized */
 194         if (current_driver && dev && dev->driver == current_driver)
 195                 return true;
 196
 197         /* driver filter on, but we can't filter on a NULL device... */
 198         if (!dev)
 199                 return false;
 200
 201         if (current_driver || !current_driver_name[0])
 202                 return false;
 203
 204         /* driver filter on but not yet initialized */
 205         drv = dev->driver;
 206         if (!drv)
 207                 return false;
 208
 209         /* lock to protect against change of current_driver_name */
 210         read_lock_irqsave(&driver_name_lock, flags);
 211
 212         ret = false;
 213         if (drv->name &&
 214             strncmp(current_driver_name, drv->name, NAME_MAX_LEN - 1) == 0) {
 215                 current_driver = drv;
 216                 ret = true;
 217         }
 218
 219         read_unlock_irqrestore(&driver_name_lock, flags);
 220
 221         return ret;
 222 }
 223
 224 #define err_printk(dev, entry, format, arg...) do {                     \
 225                 error_count += 1;                                       \
 226                 if (driver_filter(dev) &&                               \
 227                     (show_all_errors || show_num_errors > 0)) {         \
 228                         WARN(1, "%s %s: " format,                       \
 229                              dev ? dev_driver_string(dev) : "NULL",     \
 230                              dev ? dev_name(dev) : "NULL", ## arg);     \
 231                         dump_entry_trace(entry);                        \
 232                 }                                                       \
 233                 if (!show_all_errors && show_num_errors > 0)            \
 234                         show_num_errors -= 1;                           \
 235         } while (0);
 236
 237 /*
 238  * Hash related functions
 239  *
 240  * Every DMA-API request is saved into a struct dma_debug_entry. To
 241  * have quick access to these structs they are stored into a hash.
 242  */
 243 static int hash_fn(struct dma_debug_entry *entry)
 244 {
 245         /*
 246          * Hash function is based on the dma address.
 247          * We use bits 20-27 here as the index into the hash
 248          */
 249         return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
 250 }
 251
 252 /*
 253  * Request exclusive access to a hash bucket for a given dma_debug_entry.
 254  */
 255 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
 256                                            unsigned long *flags)
 257         __acquires(&dma_entry_hash[idx].lock)
 258 {
 259         int idx = hash_fn(entry);
 260         unsigned long __flags;
 261
 262         spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
 263         *flags = __flags;
 264         return &dma_entry_hash[idx];
 265 }
 266
 267 /*
 268  * Give up exclusive access to the hash bucket
 269  */
 270 static void put_hash_bucket(struct hash_bucket *bucket,
 271                             unsigned long *flags)
 272         __releases(&bucket->lock)
 273 {
 274         unsigned long __flags = *flags;
 275
 276         spin_unlock_irqrestore(&bucket->lock, __flags);
 277 }
 278
 279 static bool exact_match(struct dma_debug_entry *a, struct dma_debug_entry *b)
 280 {
 281         return ((a->dev_addr == b->dev_addr) &&
 282                 (a->dev == b->dev)) ? true : false;
 283 }
 284
 285 static bool containing_match(struct dma_debug_entry *a,
 286                              struct dma_debug_entry *b)
 287 {
 288         if (a->dev != b->dev)
 289                 return false;
 290
 291         if ((b->dev_addr <= a->dev_addr) &&
 292             ((b->dev_addr + b->size) >= (a->dev_addr + a->size)))
 293                 return true;
 294
 295         return false;
 296 }
 297
 298 /*
 299  * Search a given entry in the hash bucket list
 300  */
 301 static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
 302                                                   struct dma_debug_entry *ref,
 303                                                   match_fn match)
 304 {
 305         struct dma_debug_entry *entry, *ret = NULL;
 306         int matches = 0, match_lvl, last_lvl = -1;
 307
 308         list_for_each_entry(entry, &bucket->list, list) {
 309                 if (!match(ref, entry))
 310                         continue;
 311
 312                 /*
 313                  * Some drivers map the same physical address multiple
 314                  * times. Without a hardware IOMMU this results in the
 315                  * same device addresses being put into the dma-debug
 316                  * hash multiple times too. This can result in false
 317                  * positives being reported. Therefore we implement a
 318                  * best-fit algorithm here which returns the entry from
 319                  * the hash which fits best to the reference value
 320                  * instead of the first-fit.
 321                  */
 322                 matches += 1;
 323                 match_lvl = 0;
 324                 entry->size         == ref->size         ? ++match_lvl : 0;
 325                 entry->type         == ref->type         ? ++match_lvl : 0;
 326                 entry->direction    == ref->direction    ? ++match_lvl : 0;
 327                 entry->sg_call_ents == ref->sg_call_ents ? ++match_lvl : 0;
 328
 329                 if (match_lvl == 4) {
 330                         /* perfect-fit - return the result */
 331                         return entry;
 332                 } else if (match_lvl > last_lvl) {
 333                         /*
 334                          * We found an entry that fits better then the
 335                          * previous one or it is the 1st match.
 336                          */
 337                         last_lvl = match_lvl;
 338                         ret      = entry;
 339                 }
 340         }
 341
 342         /*
 343          * If we have multiple matches but no perfect-fit, just return
 344          * NULL.
 345          */
 346         ret = (matches == 1) ? ret : NULL;
 347
 348         return ret;
 349 }
 350
 351 static struct dma_debug_entry *bucket_find_exact(struct hash_bucket *bucket,
 352                                                  struct dma_debug_entry *ref)
 353 {
 354         return __hash_bucket_find(bucket, ref, exact_match);
 355 }
 356
 357 static struct dma_debug_entry *bucket_find_contain(struct hash_bucket **bucket,
 358                                                    struct dma_debug_entry *ref,
 359                                                    unsigned long *flags)
 360 {
 361
 362         unsigned int max_range = dma_get_max_seg_size(ref->dev);
 363         struct dma_debug_entry *entry, index = *ref;
 364         unsigned int range = 0;
 365
 366         while (range <= max_range) {
 367                 entry = __hash_bucket_find(*bucket, ref, containing_match);
 368
 369                 if (entry)
 370                         return entry;
 371
 372                 /*
 373                  * Nothing found, go back a hash bucket
 374                  */
 375                 put_hash_bucket(*bucket, flags);
 376                 range          += (1 << HASH_FN_SHIFT);
 377                 index.dev_addr -= (1 << HASH_FN_SHIFT);
 378                 *bucket = get_hash_bucket(&index, flags);
 379         }
 380
 381         return NULL;
 382 }
 383
 384 /*
 385  * Add an entry to a hash bucket
 386  */
 387 static void hash_bucket_add(struct hash_bucket *bucket,
 388                             struct dma_debug_entry *entry)
 389 {
 390         list_add_tail(&entry->list, &bucket->list);
 391 }
 392
 393 /*
 394  * Remove entry from a hash bucket list
 395  */
 396 static void hash_bucket_del(struct dma_debug_entry *entry)
 397 {
 398         list_del(&entry->list);
 399 }
 400
 401 static unsigned long long phys_addr(struct dma_debug_entry *entry)
 402 {
 403         return page_to_phys(pfn_to_page(entry->pfn)) + entry->offset;
 404 }
 405
 406 /*
 407  * Dump mapping entries for debugging purposes
 408  */
 409 void debug_dma_dump_mappings(struct device *dev)
 410 {
 411         int idx;
 412
 413         for (idx = 0; idx < HASH_SIZE; idx++) {
 414                 struct hash_bucket *bucket = &dma_entry_hash[idx];
 415                 struct dma_debug_entry *entry;
 416                 unsigned long flags;
 417
 418                 spin_lock_irqsave(&bucket->lock, flags);
 419
 420                 list_for_each_entry(entry, &bucket->list, list) {
 421                         if (!dev || dev == entry->dev) {
 422                                 dev_info(entry->dev,
 423                                          "%s idx %d P=%Lx N=%lx D=%Lx L=%Lx %s %s\n",
 424                                          type2name[entry->type], idx,
 425                                          phys_addr(entry), entry->pfn,
 426                                          entry->dev_addr, entry->size,
 427                                          dir2name[entry->direction],
 428                                          maperr2str[entry->map_err_type]);
 429                         }
 430                 }
 431
 432                 spin_unlock_irqrestore(&bucket->lock, flags);
 433         }
 434 }
 435 EXPORT_SYMBOL(debug_dma_dump_mappings);
 436
 437 /*
 438  * For each mapping (initial cacheline in the case of
 439  * dma_alloc_coherent/dma_map_page, initial cacheline in each page of a
 440  * scatterlist, or the cacheline specified in dma_map_single) insert
 441  * into this tree using the cacheline as the key. At
 442  * dma_unmap_{single|sg|page} or dma_free_coherent delete the entry.  If
 443  * the entry already exists at insertion time add a tag as a reference
 444  * count for the overlapping mappings.  For now, the overlap tracking
 445  * just ensures that 'unmaps' balance 'maps' before marking the
 446  * cacheline idle, but we should also be flagging overlaps as an API
 447  * violation.
 448  *
 449  * Memory usage is mostly constrained by the maximum number of available
 450  * dma-debug entries in that we need a free dma_debug_entry before
 451  * inserting into the tree.  In the case of dma_map_page and
 452  * dma_alloc_coherent there is only one dma_debug_entry and one
 453  * dma_active_cacheline entry to track per event.  dma_map_sg(), on the
 454  * other hand, consumes a single dma_debug_entry, but inserts 'nents'
 455  * entries into the tree.
 456  *
 457  * At any time debug_dma_assert_idle() can be called to trigger a
 458  * warning if any cachelines in the given page are in the active set.
 459  */
 460 static RADIX_TREE(dma_active_cacheline, GFP_NOWAIT);
 461 static DEFINE_SPINLOCK(radix_lock);
 462 #define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1)
 463 #define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT)
 464 #define CACHELINES_PER_PAGE (1 << CACHELINE_PER_PAGE_SHIFT)
 465
 466 static phys_addr_t to_cacheline_number(struct dma_debug_entry *entry)
 467 {
 468         return (entry->pfn << CACHELINE_PER_PAGE_SHIFT) +
 469                 (entry->offset >> L1_CACHE_SHIFT);
 470 }
 471
 472 static int active_cacheline_read_overlap(phys_addr_t cln)
 473 {
 474         int overlap = 0, i;
 475
 476         for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
 477                 if (radix_tree_tag_get(&dma_active_cacheline, cln, i))
 478                         overlap |= 1 << i;
 479         return overlap;
 480 }
 481
 482 static int active_cacheline_set_overlap(phys_addr_t cln, int overlap)
 483 {
 484         int i;
 485
 486         if (overlap > ACTIVE_CACHELINE_MAX_OVERLAP || overlap < 0)
 487                 return overlap;
 488
 489         for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--)
 490                 if (overlap & 1 << i)
 491                         radix_tree_tag_set(&dma_active_cacheline, cln, i);
 492                 else
 493                         radix_tree_tag_clear(&dma_active_cacheline, cln, i);
 494
 495         return overlap;
 496 }
 497
 498 static void active_cacheline_inc_overlap(phys_addr_t cln)
 499 {
 500         int overlap = active_cacheline_read_overlap(cln);
 501
 502         overlap = active_cacheline_set_overlap(cln, ++overlap);
 503
 504         /* If we overflowed the overlap counter then we're potentially
 505          * leaking dma-mappings.  Otherwise, if maps and unmaps are
 506          * balanced then this overflow may cause false negatives in
 507          * debug_dma_assert_idle() as the cacheline may be marked idle
 508          * prematurely.
 509          */
 510         WARN_ONCE(overlap > ACTIVE_CACHELINE_MAX_OVERLAP,
 511                   "DMA-API: exceeded %d overlapping mappings of cacheline %pa\n",
 512                   ACTIVE_CACHELINE_MAX_OVERLAP, &cln);
 513 }
 514
 515 static int active_cacheline_dec_overlap(phys_addr_t cln)
 516 {
 517         int overlap = active_cacheline_read_overlap(cln);
 518
 519         return active_cacheline_set_overlap(cln, --overlap);
 520 }
 521
 522 static int active_cacheline_insert(struct dma_debug_entry *entry)
 523 {
 524         phys_addr_t cln = to_cacheline_number(entry);
 525         unsigned long flags;
 526         int rc;
 527
 528         /* If the device is not writing memory then we don't have any
 529          * concerns about the cpu consuming stale data.  This mitigates
 530          * legitimate usages of overlapping mappings.
 531          */
 532         if (entry->direction == DMA_TO_DEVICE)
 533                 return 0;
 534
 535         spin_lock_irqsave(&radix_lock, flags);
 536         rc = radix_tree_insert(&dma_active_cacheline, cln, entry);
 537         if (rc == -EEXIST)
 538                 active_cacheline_inc_overlap(cln);
 539         spin_unlock_irqrestore(&radix_lock, flags);
 540
 541         return rc;
 542 }
 543
 544 static void active_cacheline_remove(struct dma_debug_entry *entry)
 545 {
 546         phys_addr_t cln = to_cacheline_number(entry);
 547         unsigned long flags;
 548
 549         /* ...mirror the insert case */
 550         if (entry->direction == DMA_TO_DEVICE)
 551                 return;
 552
 553         spin_lock_irqsave(&radix_lock, flags);
 554         /* since we are counting overlaps the final put of the
 555          * cacheline will occur when the overlap count is 0.
 556          * active_cacheline_dec_overlap() returns -1 in that case
 557          */
 558         if (active_cacheline_dec_overlap(cln) < 0)
 559                 radix_tree_delete(&dma_active_cacheline, cln);
 560         spin_unlock_irqrestore(&radix_lock, flags);
 561 }
 562
 563 /**
 564  * debug_dma_assert_idle() - assert that a page is not undergoing dma
 565  * @page: page to lookup in the dma_active_cacheline tree
 566  *
 567  * Place a call to this routine in cases where the cpu touching the page
 568  * before the dma completes (page is dma_unmapped) will lead to data
 569  * corruption.
 570  */
 571 void debug_dma_assert_idle(struct page *page)
 572 {
 573         static struct dma_debug_entry *ents[CACHELINES_PER_PAGE];
 574         struct dma_debug_entry *entry = NULL;
 575         void **results = (void **) &ents;
 576         unsigned int nents, i;
 577         unsigned long flags;
 578         phys_addr_t cln;
 579
 580         if (dma_debug_disabled())
 581                 return;
 582
 583         if (!page)
 584                 return;
 585
 586         cln = (phys_addr_t) page_to_pfn(page) << CACHELINE_PER_PAGE_SHIFT;
 587         spin_lock_irqsave(&radix_lock, flags);
 588         nents = radix_tree_gang_lookup(&dma_active_cacheline, results, cln,
 589                                        CACHELINES_PER_PAGE);
 590         for (i = 0; i < nents; i++) {
 591                 phys_addr_t ent_cln = to_cacheline_number(ents[i]);
 592
 593                 if (ent_cln == cln) {
 594                         entry = ents[i];
 595                         break;
 596                 } else if (ent_cln >= cln + CACHELINES_PER_PAGE)
 597                         break;
 598         }
 599         spin_unlock_irqrestore(&radix_lock, flags);
 600
 601         if (!entry)
 602                 return;
 603
 604         cln = to_cacheline_number(entry);
 605         err_printk(entry->dev, entry,
 606                    "DMA-API: cpu touching an active dma mapped cacheline [cln=%pa]\n",
 607                    &cln);
 608 }
 609
 610 /*
 611  * Wrapper function for adding an entry to the hash.
 612  * This function takes care of locking itself.
 613  */
 614 static void add_dma_entry(struct dma_debug_entry *entry)
 615 {
 616         struct hash_bucket *bucket;
 617         unsigned long flags;
 618         int rc;
 619
 620         bucket = get_hash_bucket(entry, &flags);
 621         hash_bucket_add(bucket, entry);
 622         put_hash_bucket(bucket, &flags);
 623
 624         rc = active_cacheline_insert(entry);
 625         if (rc == -ENOMEM) {
 626                 pr_err("DMA-API: cacheline tracking ENOMEM, dma-debug disabled\n");
 627                 global_disable = true;
 628         }
 629
 630         /* TODO: report -EEXIST errors here as overlapping mappings are
 631          * not supported by the DMA API
 632          */
 633 }
 634
 635 static struct dma_debug_entry *__dma_entry_alloc(void)
 636 {
 637         struct dma_debug_entry *entry;
 638
 639         entry = list_entry(free_entries.next, struct dma_debug_entry, list);
 640         list_del(&entry->list);
 641         memset(entry, 0, sizeof(*entry));
 642
 643         num_free_entries -= 1;
 644         if (num_free_entries < min_free_entries)
 645                 min_free_entries = num_free_entries;
 646
 647         return entry;
 648 }
 649
 650 /* struct dma_entry allocator
 651  *
 652  * The next two functions implement the allocator for
 653  * struct dma_debug_entries.
 654  */
 655 static struct dma_debug_entry *dma_entry_alloc(void)
 656 {
 657         struct dma_debug_entry *entry;
 658         unsigned long flags;
 659
 660         spin_lock_irqsave(&free_entries_lock, flags);
 661
 662         if (list_empty(&free_entries)) {
 663                 global_disable = true;
 664                 spin_unlock_irqrestore(&free_entries_lock, flags);
 665                 pr_err("DMA-API: debugging out of memory - disabling\n");
 666                 return NULL;
 667         }
 668
 669         entry = __dma_entry_alloc();
 670
 671         spin_unlock_irqrestore(&free_entries_lock, flags);
 672
 673 #ifdef CONFIG_STACKTRACE
 674         entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES;
 675         entry->stacktrace.entries = entry->st_entries;
 676         entry->stacktrace.skip = 2;
 677         save_stack_trace(&entry->stacktrace);
 678 #endif
 679
 680         return entry;
 681 }
 682
 683 static void dma_entry_free(struct dma_debug_entry *entry)
 684 {
 685         unsigned long flags;
 686
 687         active_cacheline_remove(entry);
 688
 689         /*
 690          * add to beginning of the list - this way the entries are
 691          * more likely cache hot when they are reallocated.
 692          */
 693         spin_lock_irqsave(&free_entries_lock, flags);
 694         list_add(&entry->list, &free_entries);
 695         num_free_entries += 1;
 696         spin_unlock_irqrestore(&free_entries_lock, flags);
 697 }
 698
 699 int dma_debug_resize_entries(u32 num_entries)
 700 {
 701         int i, delta, ret = 0;
 702         unsigned long flags;
 703         struct dma_debug_entry *entry;
 704         LIST_HEAD(tmp);
 705
 706         spin_lock_irqsave(&free_entries_lock, flags);
 707
 708         if (nr_total_entries < num_entries) {
 709                 delta = num_entries - nr_total_entries;
 710
 711                 spin_unlock_irqrestore(&free_entries_lock, flags);
 712
 713                 for (i = 0; i < delta; i++) {
 714                         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 715                         if (!entry)
 716                                 break;
 717
 718                         list_add_tail(&entry->list, &tmp);
 719                 }
 720
 721                 spin_lock_irqsave(&free_entries_lock, flags);
 722
 723                 list_splice(&tmp, &free_entries);
 724                 nr_total_entries += i;
 725                 num_free_entries += i;
 726         } else {
 727                 delta = nr_total_entries - num_entries;
 728
 729                 for (i = 0; i < delta && !list_empty(&free_entries); i++) {
 730                         entry = __dma_entry_alloc();
 731                         kfree(entry);
 732                 }
 733
 734                 nr_total_entries -= i;
 735         }
 736
 737         if (nr_total_entries != num_entries)
 738                 ret = 1;
 739
 740         spin_unlock_irqrestore(&free_entries_lock, flags);
 741
 742         return ret;
 743 }
 744 EXPORT_SYMBOL(dma_debug_resize_entries);
 745
 746 /*
 747  * DMA-API debugging init code
 748  *
 749  * The init code does two things:
 750  *   1. Initialize core data structures
 751  *   2. Preallocate a given number of dma_debug_entry structs
 752  */
 753
 754 static int prealloc_memory(u32 num_entries)
 755 {
 756         struct dma_debug_entry *entry, *next_entry;
 757         int i;
 758
 759         for (i = 0; i < num_entries; ++i) {
 760                 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 761                 if (!entry)
 762                         goto out_err;
 763
 764                 list_add_tail(&entry->list, &free_entries);
 765         }
 766
 767         num_free_entries = num_entries;
 768         min_free_entries = num_entries;
 769
 770         pr_info("DMA-API: preallocated %d debug entries\n", num_entries);
 771
 772         return 0;
 773
 774 out_err:
 775
 776         list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
 777                 list_del(&entry->list);
 778                 kfree(entry);
 779         }
 780
 781         return -ENOMEM;
 782 }
 783
 784 static ssize_t filter_read(struct file *file, char __user *user_buf,
 785                            size_t count, loff_t *ppos)
 786 {
 787         char buf[NAME_MAX_LEN + 1];
 788         unsigned long flags;
 789         int len;
 790
 791         if (!current_driver_name[0])
 792                 return 0;
 793
 794         /*
 795          * We can't copy to userspace directly because current_driver_name can
 796          * only be read under the driver_name_lock with irqs disabled. So
 797          * create a temporary copy first.
 798          */
 799         read_lock_irqsave(&driver_name_lock, flags);
 800         len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
 801         read_unlock_irqrestore(&driver_name_lock, flags);
 802
 803         return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 804 }
 805
 806 static ssize_t filter_write(struct file *file, const char __user *userbuf,
 807                             size_t count, loff_t *ppos)
 808 {
 809         char buf[NAME_MAX_LEN];
 810         unsigned long flags;
 811         size_t len;
 812         int i;
 813
 814         /*
 815          * We can't copy from userspace directly. Access to
 816          * current_driver_name is protected with a write_lock with irqs
 817          * disabled. Since copy_from_user can fault and may sleep we
 818          * need to copy to temporary buffer first
 819          */
 820         len = min(count, (size_t)(NAME_MAX_LEN - 1));
 821         if (copy_from_user(buf, userbuf, len))
 822                 return -EFAULT;
 823
 824         buf[len] = 0;
 825
 826         write_lock_irqsave(&driver_name_lock, flags);
 827
 828         /*
 829          * Now handle the string we got from userspace very carefully.
 830          * The rules are:
 831          *         - only use the first token we got
 832          *         - token delimiter is everything looking like a space
 833          *           character (' ', '\n', '\t' ...)
 834          *
 835          */
 836         if (!isalnum(buf[0])) {
 837                 /*
 838                  * If the first character userspace gave us is not
 839                  * alphanumerical then assume the filter should be
 840                  * switched off.
 841                  */
 842                 if (current_driver_name[0])
 843                         pr_info("DMA-API: switching off dma-debug driver filter\n");
 844                 current_driver_name[0] = 0;
 845                 current_driver = NULL;
 846                 goto out_unlock;
 847         }
 848
 849         /*
 850          * Now parse out the first token and use it as the name for the
 851          * driver to filter for.
 852          */
 853         for (i = 0; i < NAME_MAX_LEN - 1; ++i) {
 854                 current_driver_name[i] = buf[i];
 855                 if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
 856                         break;
 857         }
 858         current_driver_name[i] = 0;
 859         current_driver = NULL;
 860
 861         pr_info("DMA-API: enable driver filter for driver [%s]\n",
 862                 current_driver_name);
 863
 864 out_unlock:
 865         write_unlock_irqrestore(&driver_name_lock, flags);
 866
 867         return count;
 868 }
 869
 870 static const struct file_operations filter_fops = {
 871         .read  = filter_read,
 872         .write = filter_write,
 873         .llseek = default_llseek,
 874 };
 875
 876 static int dma_debug_fs_init(void)
 877 {
 878         dma_debug_dent = debugfs_create_dir("dma-api", NULL);
 879         if (!dma_debug_dent) {
 880                 pr_err("DMA-API: can not create debugfs directory\n");
 881                 return -ENOMEM;
 882         }
 883
 884         global_disable_dent = debugfs_create_bool("disabled", 0444,
 885                         dma_debug_dent,
 886                         &global_disable);
 887         if (!global_disable_dent)
 888                 goto out_err;
 889
 890         error_count_dent = debugfs_create_u32("error_count", 0444,
 891                         dma_debug_dent, &error_count);
 892         if (!error_count_dent)
 893                 goto out_err;
 894
 895         show_all_errors_dent = debugfs_create_u32("all_errors", 0644,
 896                         dma_debug_dent,
 897                         &show_all_errors);
 898         if (!show_all_errors_dent)
 899                 goto out_err;
 900
 901         show_num_errors_dent = debugfs_create_u32("num_errors", 0644,
 902                         dma_debug_dent,
 903                         &show_num_errors);
 904         if (!show_num_errors_dent)
 905                 goto out_err;
 906
 907         num_free_entries_dent = debugfs_create_u32("num_free_entries", 0444,
 908                         dma_debug_dent,
 909                         &num_free_entries);
 910         if (!num_free_entries_dent)
 911                 goto out_err;
 912
 913         min_free_entries_dent = debugfs_create_u32("min_free_entries", 0444,
 914                         dma_debug_dent,
 915                         &min_free_entries);
 916         if (!min_free_entries_dent)
 917                 goto out_err;
 918
 919         filter_dent = debugfs_create_file("driver_filter", 0644,
 920                                           dma_debug_dent, NULL, &filter_fops);
 921         if (!filter_dent)
 922                 goto out_err;
 923
 924         return 0;
 925
 926 out_err:
 927         debugfs_remove_recursive(dma_debug_dent);
 928
 929         return -ENOMEM;
 930 }
 931
 932 static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry)
 933 {
 934         struct dma_debug_entry *entry;
 935         unsigned long flags;
 936         int count = 0, i;
 937
 938         local_irq_save(flags);
 939
 940         for (i = 0; i < HASH_SIZE; ++i) {
 941                 spin_lock(&dma_entry_hash[i].lock);
 942                 list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
 943                         if (entry->dev == dev) {
 944                                 count += 1;
 945                                 *out_entry = entry;
 946                         }
 947                 }
 948                 spin_unlock(&dma_entry_hash[i].lock);
 949         }
 950
 951         local_irq_restore(flags);
 952
 953         return count;
 954 }
 955
 956 static int dma_debug_device_change(struct notifier_block *nb, unsigned long action, void *data)
 957 {
 958         struct device *dev = data;
 959         struct dma_debug_entry *uninitialized_var(entry);
 960         int count;
 961
 962         if (dma_debug_disabled())
 963                 return 0;
 964
 965         switch (action) {
 966         case BUS_NOTIFY_UNBOUND_DRIVER:
 967                 count = device_dma_allocations(dev, &entry);
 968                 if (count == 0)
 969                         break;
 970                 err_printk(dev, entry, "DMA-API: device driver has pending "
 971                                 "DMA allocations while released from device "
 972                                 "[count=%d]\n"
 973                                 "One of leaked entries details: "
 974                                 "[device address=0x%016llx] [size=%llu bytes] "
 975                                 "[mapped with %s] [mapped as %s]\n",
 976                         count, entry->dev_addr, entry->size,
 977                         dir2name[entry->direction], type2name[entry->type]);
 978                 break;
 979         default:
 980                 break;
 981         }
 982
 983         return 0;
 984 }
 985
 986 void dma_debug_add_bus(struct bus_type *bus)
 987 {
 988         struct notifier_block *nb;
 989
 990         if (dma_debug_disabled())
 991                 return;
 992
 993         nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
 994         if (nb == NULL) {
 995                 pr_err("dma_debug_add_bus: out of memory\n");
 996                 return;
 997         }
 998
 999         nb->notifier_call = dma_debug_device_change;
1000
1001         bus_register_notifier(bus, nb);
1002 }
1003
1004 /*
1005  * Let the architectures decide how many entries should be preallocated.
1006  */
1007 void dma_debug_init(u32 num_entries)
1008 {
1009         int i;
1010
1011         /* Do not use dma_debug_initialized here, since we really want to be
1012          * called to set dma_debug_initialized
1013          */
1014         if (global_disable)
1015                 return;
1016
1017         for (i = 0; i < HASH_SIZE; ++i) {
1018                 INIT_LIST_HEAD(&dma_entry_hash[i].list);
1019                 spin_lock_init(&dma_entry_hash[i].lock);
1020         }
1021
1022         if (dma_debug_fs_init() != 0) {
1023                 pr_err("DMA-API: error creating debugfs entries - disabling\n");
1024                 global_disable = true;
1025
1026                 return;
1027         }
1028
1029         if (req_entries)
1030                 num_entries = req_entries;
1031
1032         if (prealloc_memory(num_entries) != 0) {
1033                 pr_err("DMA-API: debugging out of memory error - disabled\n");
1034                 global_disable = true;
1035
1036                 return;
1037         }
1038
1039         nr_total_entries = num_free_entries;
1040
1041         dma_debug_initialized = true;
1042
1043         pr_info("DMA-API: debugging enabled by kernel config\n");
1044 }
1045
1046 static __init int dma_debug_cmdline(char *str)
1047 {
1048         if (!str)
1049                 return -EINVAL;
1050
1051         if (strncmp(str, "off", 3) == 0) {
1052                 pr_info("DMA-API: debugging disabled on kernel command line\n");
1053                 global_disable = true;
1054         }
1055
1056         return 0;
1057 }
1058
1059 static __init int dma_debug_entries_cmdline(char *str)
1060 {
1061         int res;
1062
1063         if (!str)
1064                 return -EINVAL;
1065
1066         res = get_option(&str, &req_entries);
1067
1068         if (!res)
1069                 req_entries = 0;
1070
1071         return 0;
1072 }
1073
1074 __setup("dma_debug=", dma_debug_cmdline);
1075 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
1076
1077 static void check_unmap(struct dma_debug_entry *ref)
1078 {
1079         struct dma_debug_entry *entry;
1080         struct hash_bucket *bucket;
1081         unsigned long flags;
1082
1083         bucket = get_hash_bucket(ref, &flags);
1084         entry = bucket_find_exact(bucket, ref);
1085
1086         if (!entry) {
1087                 /* must drop lock before calling dma_mapping_error */
1088                 put_hash_bucket(bucket, &flags);
1089
1090                 if (dma_mapping_error(ref->dev, ref->dev_addr)) {
1091                         err_printk(ref->dev, NULL,
1092                                    "DMA-API: device driver tries to free an "
1093                                    "invalid DMA memory address\n");
1094                 } else {
1095                         err_printk(ref->dev, NULL,
1096                                    "DMA-API: device driver tries to free DMA "
1097                                    "memory it has not allocated [device "
1098                                    "address=0x%016llx] [size=%llu bytes]\n",
1099                                    ref->dev_addr, ref->size);
1100                 }
1101                 return;
1102         }
1103
1104         if (ref->size != entry->size) {
1105                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1106                            "DMA memory with different size "
1107                            "[device address=0x%016llx] [map size=%llu bytes] "
1108                            "[unmap size=%llu bytes]\n",
1109                            ref->dev_addr, entry->size, ref->size);
1110         }
1111
1112         if (ref->type != entry->type) {
1113                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1114                            "DMA memory with wrong function "
1115                            "[device address=0x%016llx] [size=%llu bytes] "
1116                            "[mapped as %s] [unmapped as %s]\n",
1117                            ref->dev_addr, ref->size,
1118                            type2name[entry->type], type2name[ref->type]);
1119         } else if ((entry->type == dma_debug_coherent) &&
1120                    (phys_addr(ref) != phys_addr(entry))) {
1121                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1122                            "DMA memory with different CPU address "
1123                            "[device address=0x%016llx] [size=%llu bytes] "
1124                            "[cpu alloc address=0x%016llx] "
1125                            "[cpu free address=0x%016llx]",
1126                            ref->dev_addr, ref->size,
1127                            phys_addr(entry),
1128                            phys_addr(ref));
1129         }
1130
1131         if (ref->sg_call_ents && ref->type == dma_debug_sg &&
1132             ref->sg_call_ents != entry->sg_call_ents) {
1133                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1134                            "DMA sg list with different entry count "
1135                            "[map count=%d] [unmap count=%d]\n",
1136                            entry->sg_call_ents, ref->sg_call_ents);
1137         }
1138
1139         /*
1140          * This may be no bug in reality - but most implementations of the
1141          * DMA API don't handle this properly, so check for it here
1142          */
1143         if (ref->direction != entry->direction) {
1144                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
1145                            "DMA memory with different direction "
1146                            "[device address=0x%016llx] [size=%llu bytes] "
1147                            "[mapped with %s] [unmapped with %s]\n",
1148                            ref->dev_addr, ref->size,
1149                            dir2name[entry->direction],
1150                            dir2name[ref->direction]);
1151         }
1152
1153         if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1154                 err_printk(ref->dev, entry,
1155                            "DMA-API: device driver failed to check map error"
1156                            "[device address=0x%016llx] [size=%llu bytes] "
1157                            "[mapped as %s]",
1158                            ref->dev_addr, ref->size,
1159                            type2name[entry->type]);
1160         }
1161
1162         hash_bucket_del(entry);
1163         dma_entry_free(entry);
1164
1165         put_hash_bucket(bucket, &flags);
1166 }
1167
1168 static void check_for_stack(struct device *dev,
1169                             struct page *page, size_t offset)
1170 {
1171         void *addr;
1172         struct vm_struct *stack_vm_area = task_stack_vm_area(current);
1173
1174         if (!stack_vm_area) {
1175                 /* Stack is direct-mapped. */
1176                 if (PageHighMem(page))
1177                         return;
1178                 addr = page_address(page) + offset;
1179                 if (object_is_on_stack(addr))
1180                         err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [addr=%p]\n", addr);
1181         } else {
1182                 /* Stack is vmalloced. */
1183                 int i;
1184
1185                 for (i = 0; i < stack_vm_area->nr_pages; i++) {
1186                         if (page != stack_vm_area->pages[i])
1187                                 continue;
1188
1189                         addr = (u8 *)current->stack + i * PAGE_SIZE + offset;
1190                         err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [probable addr=%p]\n", addr);
1191                         break;
1192                 }
1193         }
1194 }
1195
1196 static inline bool overlap(void *addr, unsigned long len, void *start, void *end)
1197 {
1198         unsigned long a1 = (unsigned long)addr;
1199         unsigned long b1 = a1 + len;
1200         unsigned long a2 = (unsigned long)start;
1201         unsigned long b2 = (unsigned long)end;
1202
1203         return !(b1 <= a2 || a1 >= b2);
1204 }
1205
1206 static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
1207 {
1208         if (overlap(addr, len, _stext, _etext) ||
1209             overlap(addr, len, __start_rodata, __end_rodata))
1210                 err_printk(dev, NULL, "DMA-API: device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
1211 }
1212
1213 static void check_sync(struct device *dev,
1214                        struct dma_debug_entry *ref,
1215                        bool to_cpu)
1216 {
1217         struct dma_debug_entry *entry;
1218         struct hash_bucket *bucket;
1219         unsigned long flags;
1220
1221         bucket = get_hash_bucket(ref, &flags);
1222
1223         entry = bucket_find_contain(&bucket, ref, &flags);
1224
1225         if (!entry) {
1226                 err_printk(dev, NULL, "DMA-API: device driver tries "
1227                                 "to sync DMA memory it has not allocated "
1228                                 "[device address=0x%016llx] [size=%llu bytes]\n",
1229                                 (unsigned long long)ref->dev_addr, ref->size);
1230                 goto out;
1231         }
1232
1233         if (ref->size > entry->size) {
1234                 err_printk(dev, entry, "DMA-API: device driver syncs"
1235                                 " DMA memory outside allocated range "
1236                                 "[device address=0x%016llx] "
1237                                 "[allocation size=%llu bytes] "
1238                                 "[sync offset+size=%llu]\n",
1239                                 entry->dev_addr, entry->size,
1240                                 ref->size);
1241         }
1242
1243         if (entry->direction == DMA_BIDIRECTIONAL)
1244                 goto out;
1245
1246         if (ref->direction != entry->direction) {
1247                 err_printk(dev, entry, "DMA-API: device driver syncs "
1248                                 "DMA memory with different direction "
1249                                 "[device address=0x%016llx] [size=%llu bytes] "
1250                                 "[mapped with %s] [synced with %s]\n",
1251                                 (unsigned long long)ref->dev_addr, entry->size,
1252                                 dir2name[entry->direction],
1253                                 dir2name[ref->direction]);
1254         }
1255
1256         if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
1257                       !(ref->direction == DMA_TO_DEVICE))
1258                 err_printk(dev, entry, "DMA-API: device driver syncs "
1259                                 "device read-only DMA memory for cpu "
1260                                 "[device address=0x%016llx] [size=%llu bytes] "
1261                                 "[mapped with %s] [synced with %s]\n",
1262                                 (unsigned long long)ref->dev_addr, entry->size,
1263                                 dir2name[entry->direction],
1264                                 dir2name[ref->direction]);
1265
1266         if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
1267                        !(ref->direction == DMA_FROM_DEVICE))
1268                 err_printk(dev, entry, "DMA-API: device driver syncs "
1269                                 "device write-only DMA memory to device "
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 (ref->sg_call_ents && ref->type == dma_debug_sg &&
1277             ref->sg_call_ents != entry->sg_call_ents) {
1278                 err_printk(ref->dev, entry, "DMA-API: device driver syncs "
1279                            "DMA sg list with different entry count "
1280                            "[map count=%d] [sync count=%d]\n",
1281                            entry->sg_call_ents, ref->sg_call_ents);
1282         }
1283
1284 out:
1285         put_hash_bucket(bucket, &flags);
1286 }
1287
1288 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
1289                         size_t size, int direction, dma_addr_t dma_addr,
1290                         bool map_single)
1291 {
1292         struct dma_debug_entry *entry;
1293
1294         if (unlikely(dma_debug_disabled()))
1295                 return;
1296
1297         if (dma_mapping_error(dev, dma_addr))
1298                 return;
1299
1300         entry = dma_entry_alloc();
1301         if (!entry)
1302                 return;
1303
1304         entry->dev       = dev;
1305         entry->type      = dma_debug_page;
1306         entry->pfn       = page_to_pfn(page);
1307         entry->offset    = offset,
1308         entry->dev_addr  = dma_addr;
1309         entry->size      = size;
1310         entry->direction = direction;
1311         entry->map_err_type = MAP_ERR_NOT_CHECKED;
1312
1313         if (map_single)
1314                 entry->type = dma_debug_single;
1315
1316         check_for_stack(dev, page, offset);
1317
1318         if (!PageHighMem(page)) {
1319                 void *addr = page_address(page) + offset;
1320
1321                 check_for_illegal_area(dev, addr, size);
1322         }
1323
1324         add_dma_entry(entry);
1325 }
1326 EXPORT_SYMBOL(debug_dma_map_page);
1327
1328 void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
1329 {
1330         struct dma_debug_entry ref;
1331         struct dma_debug_entry *entry;
1332         struct hash_bucket *bucket;
1333         unsigned long flags;
1334
1335         if (unlikely(dma_debug_disabled()))
1336                 return;
1337
1338         ref.dev = dev;
1339         ref.dev_addr = dma_addr;
1340         bucket = get_hash_bucket(&ref, &flags);
1341
1342         list_for_each_entry(entry, &bucket->list, list) {
1343                 if (!exact_match(&ref, entry))
1344                         continue;
1345
1346                 /*
1347                  * The same physical address can be mapped multiple
1348                  * times. Without a hardware IOMMU this results in the
1349                  * same device addresses being put into the dma-debug
1350                  * hash multiple times too. This can result in false
1351                  * positives being reported. Therefore we implement a
1352                  * best-fit algorithm here which updates the first entry
1353                  * from the hash which fits the reference value and is
1354                  * not currently listed as being checked.
1355                  */
1356                 if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1357                         entry->map_err_type = MAP_ERR_CHECKED;
1358                         break;
1359                 }
1360         }
1361
1362         put_hash_bucket(bucket, &flags);
1363 }
1364 EXPORT_SYMBOL(debug_dma_mapping_error);
1365
1366 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
1367                           size_t size, int direction, bool map_single)
1368 {
1369         struct dma_debug_entry ref = {
1370                 .type           = dma_debug_page,
1371                 .dev            = dev,
1372                 .dev_addr       = addr,
1373                 .size           = size,
1374                 .direction      = direction,
1375         };
1376
1377         if (unlikely(dma_debug_disabled()))
1378                 return;
1379
1380         if (map_single)
1381                 ref.type = dma_debug_single;
1382
1383         check_unmap(&ref);
1384 }
1385 EXPORT_SYMBOL(debug_dma_unmap_page);
1386
1387 void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
1388                       int nents, int mapped_ents, int direction)
1389 {
1390         struct dma_debug_entry *entry;
1391         struct scatterlist *s;
1392         int i;
1393
1394         if (unlikely(dma_debug_disabled()))
1395                 return;
1396
1397         for_each_sg(sg, s, mapped_ents, i) {
1398                 entry = dma_entry_alloc();
1399                 if (!entry)
1400                         return;
1401
1402                 entry->type           = dma_debug_sg;
1403                 entry->dev            = dev;
1404                 entry->pfn            = page_to_pfn(sg_page(s));
1405                 entry->offset         = s->offset,
1406                 entry->size           = sg_dma_len(s);
1407                 entry->dev_addr       = sg_dma_address(s);
1408                 entry->direction      = direction;
1409                 entry->sg_call_ents   = nents;
1410                 entry->sg_mapped_ents = mapped_ents;
1411
1412                 check_for_stack(dev, sg_page(s), s->offset);
1413
1414                 if (!PageHighMem(sg_page(s))) {
1415                         check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
1416                 }
1417
1418                 add_dma_entry(entry);
1419         }
1420 }
1421 EXPORT_SYMBOL(debug_dma_map_sg);
1422
1423 static int get_nr_mapped_entries(struct device *dev,
1424                                  struct dma_debug_entry *ref)
1425 {
1426         struct dma_debug_entry *entry;
1427         struct hash_bucket *bucket;
1428         unsigned long flags;
1429         int mapped_ents;
1430
1431         bucket       = get_hash_bucket(ref, &flags);
1432         entry        = bucket_find_exact(bucket, ref);
1433         mapped_ents  = 0;
1434
1435         if (entry)
1436                 mapped_ents = entry->sg_mapped_ents;
1437         put_hash_bucket(bucket, &flags);
1438
1439         return mapped_ents;
1440 }
1441
1442 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
1443                         int nelems, int dir)
1444 {
1445         struct scatterlist *s;
1446         int mapped_ents = 0, i;
1447
1448         if (unlikely(dma_debug_disabled()))
1449                 return;
1450
1451         for_each_sg(sglist, s, nelems, i) {
1452
1453                 struct dma_debug_entry ref = {
1454                         .type           = dma_debug_sg,
1455                         .dev            = dev,
1456                         .pfn            = page_to_pfn(sg_page(s)),
1457                         .offset         = s->offset,
1458                         .dev_addr       = sg_dma_address(s),
1459                         .size           = sg_dma_len(s),
1460                         .direction      = dir,
1461                         .sg_call_ents   = nelems,
1462                 };
1463
1464                 if (mapped_ents && i >= mapped_ents)
1465                         break;
1466
1467                 if (!i)
1468                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1469
1470                 check_unmap(&ref);
1471         }
1472 }
1473 EXPORT_SYMBOL(debug_dma_unmap_sg);
1474
1475 void debug_dma_alloc_coherent(struct device *dev, size_t size,
1476                               dma_addr_t dma_addr, void *virt)
1477 {
1478         struct dma_debug_entry *entry;
1479
1480         if (unlikely(dma_debug_disabled()))
1481                 return;
1482
1483         if (unlikely(virt == NULL))
1484                 return;
1485
1486         entry = dma_entry_alloc();
1487         if (!entry)
1488                 return;
1489
1490         entry->type      = dma_debug_coherent;
1491         entry->dev       = dev;
1492         entry->pfn       = page_to_pfn(virt_to_page(virt));
1493         entry->offset    = (size_t) virt & ~PAGE_MASK;
1494         entry->size      = size;
1495         entry->dev_addr  = dma_addr;
1496         entry->direction = DMA_BIDIRECTIONAL;
1497
1498         add_dma_entry(entry);
1499 }
1500 EXPORT_SYMBOL(debug_dma_alloc_coherent);
1501
1502 void debug_dma_free_coherent(struct device *dev, size_t size,
1503                          void *virt, dma_addr_t addr)
1504 {
1505         struct dma_debug_entry ref = {
1506                 .type           = dma_debug_coherent,
1507                 .dev            = dev,
1508                 .pfn            = page_to_pfn(virt_to_page(virt)),
1509                 .offset         = (size_t) virt & ~PAGE_MASK,
1510                 .dev_addr       = addr,
1511                 .size           = size,
1512                 .direction      = DMA_BIDIRECTIONAL,
1513         };
1514
1515         if (unlikely(dma_debug_disabled()))
1516                 return;
1517
1518         check_unmap(&ref);
1519 }
1520 EXPORT_SYMBOL(debug_dma_free_coherent);
1521
1522 void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
1523                                    size_t size, int direction)
1524 {
1525         struct dma_debug_entry ref;
1526
1527         if (unlikely(dma_debug_disabled()))
1528                 return;
1529
1530         ref.type         = dma_debug_single;
1531         ref.dev          = dev;
1532         ref.dev_addr     = dma_handle;
1533         ref.size         = size;
1534         ref.direction    = direction;
1535         ref.sg_call_ents = 0;
1536
1537         check_sync(dev, &ref, true);
1538 }
1539 EXPORT_SYMBOL(debug_dma_sync_single_for_cpu);
1540
1541 void debug_dma_sync_single_for_device(struct device *dev,
1542                                       dma_addr_t dma_handle, size_t size,
1543                                       int direction)
1544 {
1545         struct dma_debug_entry ref;
1546
1547         if (unlikely(dma_debug_disabled()))
1548                 return;
1549
1550         ref.type         = dma_debug_single;
1551         ref.dev          = dev;
1552         ref.dev_addr     = dma_handle;
1553         ref.size         = size;
1554         ref.direction    = direction;
1555         ref.sg_call_ents = 0;
1556
1557         check_sync(dev, &ref, false);
1558 }
1559 EXPORT_SYMBOL(debug_dma_sync_single_for_device);
1560
1561 void debug_dma_sync_single_range_for_cpu(struct device *dev,
1562                                          dma_addr_t dma_handle,
1563                                          unsigned long offset, size_t size,
1564                                          int direction)
1565 {
1566         struct dma_debug_entry ref;
1567
1568         if (unlikely(dma_debug_disabled()))
1569                 return;
1570
1571         ref.type         = dma_debug_single;
1572         ref.dev          = dev;
1573         ref.dev_addr     = dma_handle;
1574         ref.size         = offset + size;
1575         ref.direction    = direction;
1576         ref.sg_call_ents = 0;
1577
1578         check_sync(dev, &ref, true);
1579 }
1580 EXPORT_SYMBOL(debug_dma_sync_single_range_for_cpu);
1581
1582 void debug_dma_sync_single_range_for_device(struct device *dev,
1583                                             dma_addr_t dma_handle,
1584                                             unsigned long offset,
1585                                             size_t size, int direction)
1586 {
1587         struct dma_debug_entry ref;
1588
1589         if (unlikely(dma_debug_disabled()))
1590                 return;
1591
1592         ref.type         = dma_debug_single;
1593         ref.dev          = dev;
1594         ref.dev_addr     = dma_handle;
1595         ref.size         = offset + size;
1596         ref.direction    = direction;
1597         ref.sg_call_ents = 0;
1598
1599         check_sync(dev, &ref, false);
1600 }
1601 EXPORT_SYMBOL(debug_dma_sync_single_range_for_device);
1602
1603 void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
1604                                int nelems, int direction)
1605 {
1606         struct scatterlist *s;
1607         int mapped_ents = 0, i;
1608
1609         if (unlikely(dma_debug_disabled()))
1610                 return;
1611
1612         for_each_sg(sg, s, nelems, i) {
1613
1614                 struct dma_debug_entry ref = {
1615                         .type           = dma_debug_sg,
1616                         .dev            = dev,
1617                         .pfn            = page_to_pfn(sg_page(s)),
1618                         .offset         = s->offset,
1619                         .dev_addr       = sg_dma_address(s),
1620                         .size           = sg_dma_len(s),
1621                         .direction      = direction,
1622                         .sg_call_ents   = nelems,
1623                 };
1624
1625                 if (!i)
1626                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1627
1628                 if (i >= mapped_ents)
1629                         break;
1630
1631                 check_sync(dev, &ref, true);
1632         }
1633 }
1634 EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
1635
1636 void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
1637                                   int nelems, int direction)
1638 {
1639         struct scatterlist *s;
1640         int mapped_ents = 0, i;
1641
1642         if (unlikely(dma_debug_disabled()))
1643                 return;
1644
1645         for_each_sg(sg, s, nelems, i) {
1646
1647                 struct dma_debug_entry ref = {
1648                         .type           = dma_debug_sg,
1649                         .dev            = dev,
1650                         .pfn            = page_to_pfn(sg_page(s)),
1651                         .offset         = s->offset,
1652                         .dev_addr       = sg_dma_address(s),
1653                         .size           = sg_dma_len(s),
1654                         .direction      = direction,
1655                         .sg_call_ents   = nelems,
1656                 };
1657                 if (!i)
1658                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1659
1660                 if (i >= mapped_ents)
1661                         break;
1662
1663                 check_sync(dev, &ref, false);
1664         }
1665 }
1666 EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
1667
1668 static int __init dma_debug_driver_setup(char *str)
1669 {
1670         int i;
1671
1672         for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
1673                 current_driver_name[i] = *str;
1674                 if (*str == 0)
1675                         break;
1676         }
1677
1678         if (current_driver_name[0])
1679                 pr_info("DMA-API: enable driver filter for driver [%s]\n",
1680                         current_driver_name);
1681
1682
1683         return 1;
1684 }
1685 __setup("dma_debug_driver=", dma_debug_driver_setup);