linux/mm/dmapool.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * DMA Pool allocator
   4 *
   5 * Copyright 2001 David Brownell
   6 * Copyright 2007 Intel Corporation
   7 *   Author: Matthew Wilcox <willy@linux.intel.com>
   8 *
   9 * This allocator returns small blocks of a given size which are DMA-able by
  10 * the given device.  It uses the dma_alloc_coherent page allocator to get
  11 * new pages, then splits them up into blocks of the required size.
  12 * Many older drivers still have their own code to do this.
  13 *
  14 * The current design of this allocator is fairly simple.  The pool is
  15 * represented by the 'struct dma_pool' which keeps a doubly-linked list of
  16 * allocated pages.  Each page in the page_list is split into blocks of at
  17 * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
  18 * list of free blocks within the page.  Used blocks aren't tracked, but we
  19 * keep a count of how many are currently allocated from each page.
  20 */
  21
  22#include <linux/device.h>
  23#include <linux/dma-mapping.h>
  24#include <linux/dmapool.h>
  25#include <linux/kernel.h>
  26#include <linux/list.h>
  27#include <linux/export.h>
  28#include <linux/mutex.h>
  29#include <linux/poison.h>
  30#include <linux/sched.h>
  31#include <linux/sched/mm.h>
  32#include <linux/slab.h>
  33#include <linux/stat.h>
  34#include <linux/spinlock.h>
  35#include <linux/string.h>
  36#include <linux/types.h>
  37#include <linux/wait.h>
  38
  39#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
  40#define DMAPOOL_DEBUG 1
  41#endif
  42
  43struct dma_pool {               /* the pool */
  44        struct list_head page_list;
  45        spinlock_t lock;
  46        size_t size;
  47        struct device *dev;
  48        size_t allocation;
  49        size_t boundary;
  50        char name[32];
  51        struct list_head pools;
  52};
  53
  54struct dma_page {               /* cacheable header for 'allocation' bytes */
  55        struct list_head page_list;
  56        void *vaddr;
  57        dma_addr_t dma;
  58        unsigned int in_use;
  59        unsigned int offset;
  60};
  61
  62static DEFINE_MUTEX(pools_lock);
  63static DEFINE_MUTEX(pools_reg_lock);
  64
  65static ssize_t pools_show(struct device *dev, struct device_attribute *attr, char *buf)
  66{
  67        unsigned temp;
  68        unsigned size;
  69        char *next;
  70        struct dma_page *page;
  71        struct dma_pool *pool;
  72
  73        next = buf;
  74        size = PAGE_SIZE;
  75
  76        temp = scnprintf(next, size, "poolinfo - 0.1\n");
  77        size -= temp;
  78        next += temp;
  79
  80        mutex_lock(&pools_lock);
  81        list_for_each_entry(pool, &dev->dma_pools, pools) {
  82                unsigned pages = 0;
  83                unsigned blocks = 0;
  84
  85                spin_lock_irq(&pool->lock);
  86                list_for_each_entry(page, &pool->page_list, page_list) {
  87                        pages++;
  88                        blocks += page->in_use;
  89                }
  90                spin_unlock_irq(&pool->lock);
  91
  92                /* per-pool info, no real statistics yet */
  93                temp = scnprintf(next, size, "%-16s %4u %4zu %4zu %2u\n",
  94                                 pool->name, blocks,
  95                                 pages * (pool->allocation / pool->size),
  96                                 pool->size, pages);
  97                size -= temp;
  98                next += temp;
  99        }
 100        mutex_unlock(&pools_lock);
 101
 102        return PAGE_SIZE - size;
 103}
 104
 105static DEVICE_ATTR_RO(pools);
 106
 107/**
 108 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
 109 * @name: name of pool, for diagnostics
 110 * @dev: device that will be doing the DMA
 111 * @size: size of the blocks in this pool.
 112 * @align: alignment requirement for blocks; must be a power of two
 113 * @boundary: returned blocks won't cross this power of two boundary
 114 * Context: not in_interrupt()
 115 *
 116 * Given one of these pools, dma_pool_alloc()
 117 * may be used to allocate memory.  Such memory will all have "consistent"
 118 * DMA mappings, accessible by the device and its driver without using
 119 * cache flushing primitives.  The actual size of blocks allocated may be
 120 * larger than requested because of alignment.
 121 *
 122 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
 123 * cross that size boundary.  This is useful for devices which have
 124 * addressing restrictions on individual DMA transfers, such as not crossing
 125 * boundaries of 4KBytes.
 126 *
 127 * Return: a dma allocation pool with the requested characteristics, or
 128 * %NULL if one can't be created.
 129 */
 130struct dma_pool *dma_pool_create(const char *name, struct device *dev,
 131                                 size_t size, size_t align, size_t boundary)
 132{
 133        struct dma_pool *retval;
 134        size_t allocation;
 135        bool empty = false;
 136
 137        if (align == 0)
 138                align = 1;
 139        else if (align & (align - 1))
 140                return NULL;
 141
 142        if (size == 0)
 143                return NULL;
 144        else if (size < 4)
 145                size = 4;
 146
 147        size = ALIGN(size, align);
 148        allocation = max_t(size_t, size, PAGE_SIZE);
 149
 150        if (!boundary)
 151                boundary = allocation;
 152        else if ((boundary < size) || (boundary & (boundary - 1)))
 153                return NULL;
 154
 155        retval = kmalloc(sizeof(*retval), GFP_KERNEL);
 156        if (!retval)
 157                return retval;
 158
 159        strscpy(retval->name, name, sizeof(retval->name));
 160
 161        retval->dev = dev;
 162
 163        INIT_LIST_HEAD(&retval->page_list);
 164        spin_lock_init(&retval->lock);
 165        retval->size = size;
 166        retval->boundary = boundary;
 167        retval->allocation = allocation;
 168
 169        INIT_LIST_HEAD(&retval->pools);
 170
 171        /*
 172         * pools_lock ensures that the ->dma_pools list does not get corrupted.
 173         * pools_reg_lock ensures that there is not a race between
 174         * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
 175         * when the first invocation of dma_pool_create() failed on
 176         * device_create_file() and the second assumes that it has been done (I
 177         * know it is a short window).
 178         */
 179        mutex_lock(&pools_reg_lock);
 180        mutex_lock(&pools_lock);
 181        if (list_empty(&dev->dma_pools))
 182                empty = true;
 183        list_add(&retval->pools, &dev->dma_pools);
 184        mutex_unlock(&pools_lock);
 185        if (empty) {
 186                int err;
 187
 188                err = device_create_file(dev, &dev_attr_pools);
 189                if (err) {
 190                        mutex_lock(&pools_lock);
 191                        list_del(&retval->pools);
 192                        mutex_unlock(&pools_lock);
 193                        mutex_unlock(&pools_reg_lock);
 194                        kfree(retval);
 195                        return NULL;
 196                }
 197        }
 198        mutex_unlock(&pools_reg_lock);
 199        return retval;
 200}
 201EXPORT_SYMBOL(dma_pool_create);
 202
 203static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 204{
 205        unsigned int offset = 0;
 206        unsigned int next_boundary = pool->boundary;
 207
 208        do {
 209                unsigned int next = offset + pool->size;
 210                if (unlikely((next + pool->size) >= next_boundary)) {
 211                        next = next_boundary;
 212                        next_boundary += pool->boundary;
 213                }
 214                *(int *)(page->vaddr + offset) = next;
 215                offset = next;
 216        } while (offset < pool->allocation);
 217}
 218
 219static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 220{
 221        struct dma_page *page;
 222
 223        page = kmalloc(sizeof(*page), mem_flags);
 224        if (!page)
 225                return NULL;
 226        page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 227                                         &page->dma, mem_flags);
 228        if (page->vaddr) {
 229#ifdef  DMAPOOL_DEBUG
 230                memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 231#endif
 232                pool_initialise_page(pool, page);
 233                page->in_use = 0;
 234                page->offset = 0;
 235        } else {
 236                kfree(page);
 237                page = NULL;
 238        }
 239        return page;
 240}
 241
 242static inline bool is_page_busy(struct dma_page *page)
 243{
 244        return page->in_use != 0;
 245}
 246
 247static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
 248{
 249        dma_addr_t dma = page->dma;
 250
 251#ifdef  DMAPOOL_DEBUG
 252        memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 253#endif
 254        dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
 255        list_del(&page->page_list);
 256        kfree(page);
 257}
 258
 259/**
 260 * dma_pool_destroy - destroys a pool of dma memory blocks.
 261 * @pool: dma pool that will be destroyed
 262 * Context: !in_interrupt()
 263 *
 264 * Caller guarantees that no more memory from the pool is in use,
 265 * and that nothing will try to use the pool after this call.
 266 */
 267void dma_pool_destroy(struct dma_pool *pool)
 268{
 269        struct dma_page *page, *tmp;
 270        bool empty = false;
 271
 272        if (unlikely(!pool))
 273                return;
 274
 275        mutex_lock(&pools_reg_lock);
 276        mutex_lock(&pools_lock);
 277        list_del(&pool->pools);
 278        if (pool->dev && list_empty(&pool->dev->dma_pools))
 279                empty = true;
 280        mutex_unlock(&pools_lock);
 281        if (empty)
 282                device_remove_file(pool->dev, &dev_attr_pools);
 283        mutex_unlock(&pools_reg_lock);
 284
 285        list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) {
 286                if (is_page_busy(page)) {
 287                        if (pool->dev)
 288                                dev_err(pool->dev, "%s %s, %p busy\n", __func__,
 289                                        pool->name, page->vaddr);
 290                        else
 291                                pr_err("%s %s, %p busy\n", __func__,
 292                                       pool->name, page->vaddr);
 293                        /* leak the still-in-use consistent memory */
 294                        list_del(&page->page_list);
 295                        kfree(page);
 296                } else
 297                        pool_free_page(pool, page);
 298        }
 299
 300        kfree(pool);
 301}
 302EXPORT_SYMBOL(dma_pool_destroy);
 303
 304/**
 305 * dma_pool_alloc - get a block of consistent memory
 306 * @pool: dma pool that will produce the block
 307 * @mem_flags: GFP_* bitmask
 308 * @handle: pointer to dma address of block
 309 *
 310 * Return: the kernel virtual address of a currently unused block,
 311 * and reports its dma address through the handle.
 312 * If such a memory block can't be allocated, %NULL is returned.
 313 */
 314void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 315                     dma_addr_t *handle)
 316{
 317        unsigned long flags;
 318        struct dma_page *page;
 319        size_t offset;
 320        void *retval;
 321
 322        might_alloc(mem_flags);
 323
 324        spin_lock_irqsave(&pool->lock, flags);
 325        list_for_each_entry(page, &pool->page_list, page_list) {
 326                if (page->offset < pool->allocation)
 327                        goto ready;
 328        }
 329
 330        /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
 331        spin_unlock_irqrestore(&pool->lock, flags);
 332
 333        page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
 334        if (!page)
 335                return NULL;
 336
 337        spin_lock_irqsave(&pool->lock, flags);
 338
 339        list_add(&page->page_list, &pool->page_list);
 340 ready:
 341        page->in_use++;
 342        offset = page->offset;
 343        page->offset = *(int *)(page->vaddr + offset);
 344        retval = offset + page->vaddr;
 345        *handle = offset + page->dma;
 346#ifdef  DMAPOOL_DEBUG
 347        {
 348                int i;
 349                u8 *data = retval;
 350                /* page->offset is stored in first 4 bytes */
 351                for (i = sizeof(page->offset); i < pool->size; i++) {
 352                        if (data[i] == POOL_POISON_FREED)
 353                                continue;
 354                        if (pool->dev)
 355                                dev_err(pool->dev, "%s %s, %p (corrupted)\n",
 356                                        __func__, pool->name, retval);
 357                        else
 358                                pr_err("%s %s, %p (corrupted)\n",
 359                                        __func__, pool->name, retval);
 360
 361                        /*
 362                         * Dump the first 4 bytes even if they are not
 363                         * POOL_POISON_FREED
 364                         */
 365                        print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
 366                                        data, pool->size, 1);
 367                        break;
 368                }
 369        }
 370        if (!(mem_flags & __GFP_ZERO))
 371                memset(retval, POOL_POISON_ALLOCATED, pool->size);
 372#endif
 373        spin_unlock_irqrestore(&pool->lock, flags);
 374
 375        if (want_init_on_alloc(mem_flags))
 376                memset(retval, 0, pool->size);
 377
 378        return retval;
 379}
 380EXPORT_SYMBOL(dma_pool_alloc);
 381
 382static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 383{
 384        struct dma_page *page;
 385
 386        list_for_each_entry(page, &pool->page_list, page_list) {
 387                if (dma < page->dma)
 388                        continue;
 389                if ((dma - page->dma) < pool->allocation)
 390                        return page;
 391        }
 392        return NULL;
 393}
 394
 395/**
 396 * dma_pool_free - put block back into dma pool
 397 * @pool: the dma pool holding the block
 398 * @vaddr: virtual address of block
 399 * @dma: dma address of block
 400 *
 401 * Caller promises neither device nor driver will again touch this block
 402 * unless it is first re-allocated.
 403 */
 404void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 405{
 406        struct dma_page *page;
 407        unsigned long flags;
 408        unsigned int offset;
 409
 410        spin_lock_irqsave(&pool->lock, flags);
 411        page = pool_find_page(pool, dma);
 412        if (!page) {
 413                spin_unlock_irqrestore(&pool->lock, flags);
 414                if (pool->dev)
 415                        dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n",
 416                                __func__, pool->name, vaddr, &dma);
 417                else
 418                        pr_err("%s %s, %p/%pad (bad dma)\n",
 419                               __func__, pool->name, vaddr, &dma);
 420                return;
 421        }
 422
 423        offset = vaddr - page->vaddr;
 424        if (want_init_on_free())
 425                memset(vaddr, 0, pool->size);
 426#ifdef  DMAPOOL_DEBUG
 427        if ((dma - page->dma) != offset) {
 428                spin_unlock_irqrestore(&pool->lock, flags);
 429                if (pool->dev)
 430                        dev_err(pool->dev, "%s %s, %p (bad vaddr)/%pad\n",
 431                                __func__, pool->name, vaddr, &dma);
 432                else
 433                        pr_err("%s %s, %p (bad vaddr)/%pad\n",
 434                               __func__, pool->name, vaddr, &dma);
 435                return;
 436        }
 437        {
 438                unsigned int chain = page->offset;
 439                while (chain < pool->allocation) {
 440                        if (chain != offset) {
 441                                chain = *(int *)(page->vaddr + chain);
 442                                continue;
 443                        }
 444                        spin_unlock_irqrestore(&pool->lock, flags);
 445                        if (pool->dev)
 446                                dev_err(pool->dev, "%s %s, dma %pad already free\n",
 447                                        __func__, pool->name, &dma);
 448                        else
 449                                pr_err("%s %s, dma %pad already free\n",
 450                                       __func__, pool->name, &dma);
 451                        return;
 452                }
 453        }
 454        memset(vaddr, POOL_POISON_FREED, pool->size);
 455#endif
 456
 457        page->in_use--;
 458        *(int *)vaddr = page->offset;
 459        page->offset = offset;
 460        /*
 461         * Resist a temptation to do
 462         *    if (!is_page_busy(page)) pool_free_page(pool, page);
 463         * Better have a few empty pages hang around.
 464         */
 465        spin_unlock_irqrestore(&pool->lock, flags);
 466}
 467EXPORT_SYMBOL(dma_pool_free);
 468
 469/*
 470 * Managed DMA pool
 471 */
 472static void dmam_pool_release(struct device *dev, void *res)
 473{
 474        struct dma_pool *pool = *(struct dma_pool **)res;
 475
 476        dma_pool_destroy(pool);
 477}
 478
 479static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 480{
 481        return *(struct dma_pool **)res == match_data;
 482}
 483
 484/**
 485 * dmam_pool_create - Managed dma_pool_create()
 486 * @name: name of pool, for diagnostics
 487 * @dev: device that will be doing the DMA
 488 * @size: size of the blocks in this pool.
 489 * @align: alignment requirement for blocks; must be a power of two
 490 * @allocation: returned blocks won't cross this boundary (or zero)
 491 *
 492 * Managed dma_pool_create().  DMA pool created with this function is
 493 * automatically destroyed on driver detach.
 494 *
 495 * Return: a managed dma allocation pool with the requested
 496 * characteristics, or %NULL if one can't be created.
 497 */
 498struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 499                                  size_t size, size_t align, size_t allocation)
 500{
 501        struct dma_pool **ptr, *pool;
 502
 503        ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 504        if (!ptr)
 505                return NULL;
 506
 507        pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 508        if (pool)
 509                devres_add(dev, ptr);
 510        else
 511                devres_free(ptr);
 512
 513        return pool;
 514}
 515EXPORT_SYMBOL(dmam_pool_create);
 516
 517/**
 518 * dmam_pool_destroy - Managed dma_pool_destroy()
 519 * @pool: dma pool that will be destroyed
 520 *
 521 * Managed dma_pool_destroy().
 522 */
 523void dmam_pool_destroy(struct dma_pool *pool)
 524{
 525        struct device *dev = pool->dev;
 526
 527        WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
 528}
 529EXPORT_SYMBOL(dmam_pool_destroy);
 530