lib/genalloc.c

   1 /*
   2  * Basic general purpose allocator for managing special purpose
   3  * memory, for example, memory that is not managed by the regular
   4  * kmalloc/kfree interface.  Uses for this includes on-device special
   5  * memory, uncached memory etc.
   6  *
   7  * It is safe to use the allocator in NMI handlers and other special
   8  * unblockable contexts that could otherwise deadlock on locks.  This
   9  * is implemented by using atomic operations and retries on any
  10  * conflicts.  The disadvantage is that there may be livelocks in
  11  * extreme cases.  For better scalability, one allocator can be used
  12  * for each CPU.
  13  *
  14  * The lockless operation only works if there is enough memory
  15  * available.  If new memory is added to the pool a lock has to be
  16  * still taken.  So any user relying on locklessness has to ensure
  17  * that sufficient memory is preallocated.
  18  *
  19  * The basic atomic operation of this allocator is cmpxchg on long.
  20  * On architectures that don't have NMI-safe cmpxchg implementation,
  21  * the allocator can NOT be used in NMI handler.  So code uses the
  22  * allocator in NMI handler should depend on
  23  * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
  24  *
  25  * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
  26  *
  27  * This source code is licensed under the GNU General Public License,
  28  * Version 2.  See the file COPYING for more details.
  29  */
  30
  31 #include <linux/slab.h>
  32 #include <linux/export.h>
  33 #include <linux/bitmap.h>
  34 #include <linux/rculist.h>
  35 #include <linux/interrupt.h>
  36 #include <linux/genalloc.h>
  37 #include <linux/of_device.h>
  38
  39 static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
  40 {
  41         return chunk->end_addr - chunk->start_addr + 1;
  42 }
  43
  44 static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
  45 {
  46         unsigned long val, nval;
  47
  48         nval = *addr;
  49         do {
  50                 val = nval;
  51                 if (val & mask_to_set)
  52                         return -EBUSY;
  53                 cpu_relax();
  54         } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
  55
  56         return 0;
  57 }
  58
  59 static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
  60 {
  61         unsigned long val, nval;
  62
  63         nval = *addr;
  64         do {
  65                 val = nval;
  66                 if ((val & mask_to_clear) != mask_to_clear)
  67                         return -EBUSY;
  68                 cpu_relax();
  69         } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
  70
  71         return 0;
  72 }
  73
  74 /*
  75  * bitmap_set_ll - set the specified number of bits at the specified position
  76  * @map: pointer to a bitmap
  77  * @start: a bit position in @map
  78  * @nr: number of bits to set
  79  *
  80  * Set @nr bits start from @start in @map lock-lessly. Several users
  81  * can set/clear the same bitmap simultaneously without lock. If two
  82  * users set the same bit, one user will return remain bits, otherwise
  83  * return 0.
  84  */
  85 static int bitmap_set_ll(unsigned long *map, int start, int nr)
  86 {
  87         unsigned long *p = map + BIT_WORD(start);
  88         const int size = start + nr;
  89         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
  90         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
  91
  92         while (nr - bits_to_set >= 0) {
  93                 if (set_bits_ll(p, mask_to_set))
  94                         return nr;
  95                 nr -= bits_to_set;
  96                 bits_to_set = BITS_PER_LONG;
  97                 mask_to_set = ~0UL;
  98                 p++;
  99         }
 100         if (nr) {
 101                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
 102                 if (set_bits_ll(p, mask_to_set))
 103                         return nr;
 104         }
 105
 106         return 0;
 107 }
 108
 109 /*
 110  * bitmap_clear_ll - clear the specified number of bits at the specified position
 111  * @map: pointer to a bitmap
 112  * @start: a bit position in @map
 113  * @nr: number of bits to set
 114  *
 115  * Clear @nr bits start from @start in @map lock-lessly. Several users
 116  * can set/clear the same bitmap simultaneously without lock. If two
 117  * users clear the same bit, one user will return remain bits,
 118  * otherwise return 0.
 119  */
 120 static int bitmap_clear_ll(unsigned long *map, int start, int nr)
 121 {
 122         unsigned long *p = map + BIT_WORD(start);
 123         const int size = start + nr;
 124         int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
 125         unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
 126
 127         while (nr - bits_to_clear >= 0) {
 128                 if (clear_bits_ll(p, mask_to_clear))
 129                         return nr;
 130                 nr -= bits_to_clear;
 131                 bits_to_clear = BITS_PER_LONG;
 132                 mask_to_clear = ~0UL;
 133                 p++;
 134         }
 135         if (nr) {
 136                 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
 137                 if (clear_bits_ll(p, mask_to_clear))
 138                         return nr;
 139         }
 140
 141         return 0;
 142 }
 143
 144 /**
 145  * gen_pool_create - create a new special memory pool
 146  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 147  * @nid: node id of the node the pool structure should be allocated on, or -1
 148  *
 149  * Create a new special memory pool that can be used to manage special purpose
 150  * memory not managed by the regular kmalloc/kfree interface.
 151  */
 152 struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
 153 {
 154         struct gen_pool *pool;
 155
 156         pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
 157         if (pool != NULL) {
 158                 spin_lock_init(&pool->lock);
 159                 INIT_LIST_HEAD(&pool->chunks);
 160                 pool->min_alloc_order = min_alloc_order;
 161                 pool->algo = gen_pool_first_fit;
 162                 pool->data = NULL;
 163         }
 164         return pool;
 165 }
 166 EXPORT_SYMBOL(gen_pool_create);
 167
 168 /**
 169  * gen_pool_add_virt - add a new chunk of special memory to the pool
 170  * @pool: pool to add new memory chunk to
 171  * @virt: virtual starting address of memory chunk to add to pool
 172  * @phys: physical starting address of memory chunk to add to pool
 173  * @size: size in bytes of the memory chunk to add to pool
 174  * @nid: node id of the node the chunk structure and bitmap should be
 175  *       allocated on, or -1
 176  *
 177  * Add a new chunk of special memory to the specified pool.
 178  *
 179  * Returns 0 on success or a -ve errno on failure.
 180  */
 181 int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
 182                  size_t size, int nid)
 183 {
 184         struct gen_pool_chunk *chunk;
 185         int nbits = size >> pool->min_alloc_order;
 186         int nbytes = sizeof(struct gen_pool_chunk) +
 187                                 BITS_TO_LONGS(nbits) * sizeof(long);
 188
 189         chunk = kzalloc_node(nbytes, GFP_KERNEL, nid);
 190         if (unlikely(chunk == NULL))
 191                 return -ENOMEM;
 192
 193         chunk->phys_addr = phys;
 194         chunk->start_addr = virt;
 195         chunk->end_addr = virt + size - 1;
 196         atomic_set(&chunk->avail, size);
 197
 198         spin_lock(&pool->lock);
 199         list_add_rcu(&chunk->next_chunk, &pool->chunks);
 200         spin_unlock(&pool->lock);
 201
 202         return 0;
 203 }
 204 EXPORT_SYMBOL(gen_pool_add_virt);
 205
 206 /**
 207  * gen_pool_virt_to_phys - return the physical address of memory
 208  * @pool: pool to allocate from
 209  * @addr: starting address of memory
 210  *
 211  * Returns the physical address on success, or -1 on error.
 212  */
 213 phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
 214 {
 215         struct gen_pool_chunk *chunk;
 216         phys_addr_t paddr = -1;
 217
 218         rcu_read_lock();
 219         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 220                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 221                         paddr = chunk->phys_addr + (addr - chunk->start_addr);
 222                         break;
 223                 }
 224         }
 225         rcu_read_unlock();
 226
 227         return paddr;
 228 }
 229 EXPORT_SYMBOL(gen_pool_virt_to_phys);
 230
 231 /**
 232  * gen_pool_destroy - destroy a special memory pool
 233  * @pool: pool to destroy
 234  *
 235  * Destroy the specified special memory pool. Verifies that there are no
 236  * outstanding allocations.
 237  */
 238 void gen_pool_destroy(struct gen_pool *pool)
 239 {
 240         struct list_head *_chunk, *_next_chunk;
 241         struct gen_pool_chunk *chunk;
 242         int order = pool->min_alloc_order;
 243         int bit, end_bit;
 244
 245         list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
 246                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 247                 list_del(&chunk->next_chunk);
 248
 249                 end_bit = chunk_size(chunk) >> order;
 250                 bit = find_next_bit(chunk->bits, end_bit, 0);
 251                 BUG_ON(bit < end_bit);
 252
 253                 kfree(chunk);
 254         }
 255         kfree(pool);
 256         return;
 257 }
 258 EXPORT_SYMBOL(gen_pool_destroy);
 259
 260 /**
 261  * gen_pool_alloc - allocate special memory from the pool
 262  * @pool: pool to allocate from
 263  * @size: number of bytes to allocate from the pool
 264  *
 265  * Allocate the requested number of bytes from the specified pool.
 266  * Uses the pool allocation function (with first-fit algorithm by default).
 267  * Can not be used in NMI handler on architectures without
 268  * NMI-safe cmpxchg implementation.
 269  */
 270 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
 271 {
 272         struct gen_pool_chunk *chunk;
 273         unsigned long addr = 0;
 274         int order = pool->min_alloc_order;
 275         int nbits, start_bit = 0, end_bit, remain;
 276
 277 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 278         BUG_ON(in_nmi());
 279 #endif
 280
 281         if (size == 0)
 282                 return 0;
 283
 284         nbits = (size + (1UL << order) - 1) >> order;
 285         rcu_read_lock();
 286         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 287                 if (size > atomic_read(&chunk->avail))
 288                         continue;
 289
 290                 end_bit = chunk_size(chunk) >> order;
 291 retry:
 292                 start_bit = pool->algo(chunk->bits, end_bit, start_bit, nbits,
 293                                 pool->data);
 294                 if (start_bit >= end_bit)
 295                         continue;
 296                 remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
 297                 if (remain) {
 298                         remain = bitmap_clear_ll(chunk->bits, start_bit,
 299                                                  nbits - remain);
 300                         BUG_ON(remain);
 301                         goto retry;
 302                 }
 303
 304                 addr = chunk->start_addr + ((unsigned long)start_bit << order);
 305                 size = nbits << order;
 306                 atomic_sub(size, &chunk->avail);
 307                 break;
 308         }
 309         rcu_read_unlock();
 310         return addr;
 311 }
 312 EXPORT_SYMBOL(gen_pool_alloc);
 313
 314 /**
 315  * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
 316  * @pool: pool to allocate from
 317  * @size: number of bytes to allocate from the pool
 318  * @dma: dma-view physical address return value.  Use NULL if unneeded.
 319  *
 320  * Allocate the requested number of bytes from the specified pool.
 321  * Uses the pool allocation function (with first-fit algorithm by default).
 322  * Can not be used in NMI handler on architectures without
 323  * NMI-safe cmpxchg implementation.
 324  */
 325 void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
 326 {
 327         unsigned long vaddr;
 328
 329         if (!pool)
 330                 return NULL;
 331
 332         vaddr = gen_pool_alloc(pool, size);
 333         if (!vaddr)
 334                 return NULL;
 335
 336         if (dma)
 337                 *dma = gen_pool_virt_to_phys(pool, vaddr);
 338
 339         return (void *)vaddr;
 340 }
 341 EXPORT_SYMBOL(gen_pool_dma_alloc);
 342
 343 /**
 344  * gen_pool_free - free allocated special memory back to the pool
 345  * @pool: pool to free to
 346  * @addr: starting address of memory to free back to pool
 347  * @size: size in bytes of memory to free
 348  *
 349  * Free previously allocated special memory back to the specified
 350  * pool.  Can not be used in NMI handler on architectures without
 351  * NMI-safe cmpxchg implementation.
 352  */
 353 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 354 {
 355         struct gen_pool_chunk *chunk;
 356         int order = pool->min_alloc_order;
 357         int start_bit, nbits, remain;
 358
 359 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 360         BUG_ON(in_nmi());
 361 #endif
 362
 363         nbits = (size + (1UL << order) - 1) >> order;
 364         rcu_read_lock();
 365         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 366                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 367                         BUG_ON(addr + size - 1 > chunk->end_addr);
 368                         start_bit = (addr - chunk->start_addr) >> order;
 369                         remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
 370                         BUG_ON(remain);
 371                         size = nbits << order;
 372                         atomic_add(size, &chunk->avail);
 373                         rcu_read_unlock();
 374                         return;
 375                 }
 376         }
 377         rcu_read_unlock();
 378         BUG();
 379 }
 380 EXPORT_SYMBOL(gen_pool_free);
 381
 382 /**
 383  * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
 384  * @pool:       the generic memory pool
 385  * @func:       func to call
 386  * @data:       additional data used by @func
 387  *
 388  * Call @func for every chunk of generic memory pool.  The @func is
 389  * called with rcu_read_lock held.
 390  */
 391 void gen_pool_for_each_chunk(struct gen_pool *pool,
 392         void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
 393         void *data)
 394 {
 395         struct gen_pool_chunk *chunk;
 396
 397         rcu_read_lock();
 398         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
 399                 func(pool, chunk, data);
 400         rcu_read_unlock();
 401 }
 402 EXPORT_SYMBOL(gen_pool_for_each_chunk);
 403
 404 /**
 405  * addr_in_gen_pool - checks if an address falls within the range of a pool
 406  * @pool:       the generic memory pool
 407  * @start:      start address
 408  * @size:       size of the region
 409  *
 410  * Check if the range of addresses falls within the specified pool. Returns
 411  * true if the entire range is contained in the pool and false otherwise.
 412  */
 413 bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
 414                         size_t size)
 415 {
 416         bool found = false;
 417         unsigned long end = start + size - 1;
 418         struct gen_pool_chunk *chunk;
 419
 420         rcu_read_lock();
 421         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
 422                 if (start >= chunk->start_addr && start <= chunk->end_addr) {
 423                         if (end <= chunk->end_addr) {
 424                                 found = true;
 425                                 break;
 426                         }
 427                 }
 428         }
 429         rcu_read_unlock();
 430         return found;
 431 }
 432
 433 /**
 434  * gen_pool_avail - get available free space of the pool
 435  * @pool: pool to get available free space
 436  *
 437  * Return available free space of the specified pool.
 438  */
 439 size_t gen_pool_avail(struct gen_pool *pool)
 440 {
 441         struct gen_pool_chunk *chunk;
 442         size_t avail = 0;
 443
 444         rcu_read_lock();
 445         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 446                 avail += atomic_read(&chunk->avail);
 447         rcu_read_unlock();
 448         return avail;
 449 }
 450 EXPORT_SYMBOL_GPL(gen_pool_avail);
 451
 452 /**
 453  * gen_pool_size - get size in bytes of memory managed by the pool
 454  * @pool: pool to get size
 455  *
 456  * Return size in bytes of memory managed by the pool.
 457  */
 458 size_t gen_pool_size(struct gen_pool *pool)
 459 {
 460         struct gen_pool_chunk *chunk;
 461         size_t size = 0;
 462
 463         rcu_read_lock();
 464         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 465                 size += chunk_size(chunk);
 466         rcu_read_unlock();
 467         return size;
 468 }
 469 EXPORT_SYMBOL_GPL(gen_pool_size);
 470
 471 /**
 472  * gen_pool_set_algo - set the allocation algorithm
 473  * @pool: pool to change allocation algorithm
 474  * @algo: custom algorithm function
 475  * @data: additional data used by @algo
 476  *
 477  * Call @algo for each memory allocation in the pool.
 478  * If @algo is NULL use gen_pool_first_fit as default
 479  * memory allocation function.
 480  */
 481 void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
 482 {
 483         rcu_read_lock();
 484
 485         pool->algo = algo;
 486         if (!pool->algo)
 487                 pool->algo = gen_pool_first_fit;
 488
 489         pool->data = data;
 490
 491         rcu_read_unlock();
 492 }
 493 EXPORT_SYMBOL(gen_pool_set_algo);
 494
 495 /**
 496  * gen_pool_first_fit - find the first available region
 497  * of memory matching the size requirement (no alignment constraint)
 498  * @map: The address to base the search on
 499  * @size: The bitmap size in bits
 500  * @start: The bitnumber to start searching at
 501  * @nr: The number of zeroed bits we're looking for
 502  * @data: additional data - unused
 503  */
 504 unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 505                 unsigned long start, unsigned int nr, void *data)
 506 {
 507         return bitmap_find_next_zero_area(map, size, start, nr, 0);
 508 }
 509 EXPORT_SYMBOL(gen_pool_first_fit);
 510
 511 /**
 512  * gen_pool_first_fit_order_align - find the first available region
 513  * of memory matching the size requirement. The region will be aligned
 514  * to the order of the size specified.
 515  * @map: The address to base the search on
 516  * @size: The bitmap size in bits
 517  * @start: The bitnumber to start searching at
 518  * @nr: The number of zeroed bits we're looking for
 519  * @data: additional data - unused
 520  */
 521 unsigned long gen_pool_first_fit_order_align(unsigned long *map,
 522                 unsigned long size, unsigned long start,
 523                 unsigned int nr, void *data)
 524 {
 525         unsigned long align_mask = roundup_pow_of_two(nr) - 1;
 526
 527         return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
 528 }
 529 EXPORT_SYMBOL(gen_pool_first_fit_order_align);
 530
 531 /**
 532  * gen_pool_best_fit - find the best fitting region of memory
 533  * macthing the size requirement (no alignment constraint)
 534  * @map: The address to base the search on
 535  * @size: The bitmap size in bits
 536  * @start: The bitnumber to start searching at
 537  * @nr: The number of zeroed bits we're looking for
 538  * @data: additional data - unused
 539  *
 540  * Iterate over the bitmap to find the smallest free region
 541  * which we can allocate the memory.
 542  */
 543 unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
 544                 unsigned long start, unsigned int nr, void *data)
 545 {
 546         unsigned long start_bit = size;
 547         unsigned long len = size + 1;
 548         unsigned long index;
 549
 550         index = bitmap_find_next_zero_area(map, size, start, nr, 0);
 551
 552         while (index < size) {
 553                 int next_bit = find_next_bit(map, size, index + nr);
 554                 if ((next_bit - index) < len) {
 555                         len = next_bit - index;
 556                         start_bit = index;
 557                         if (len == nr)
 558                                 return start_bit;
 559                 }
 560                 index = bitmap_find_next_zero_area(map, size,
 561                                                    next_bit + 1, nr, 0);
 562         }
 563
 564         return start_bit;
 565 }
 566 EXPORT_SYMBOL(gen_pool_best_fit);
 567
 568 static void devm_gen_pool_release(struct device *dev, void *res)
 569 {
 570         gen_pool_destroy(*(struct gen_pool **)res);
 571 }
 572
 573 /**
 574  * devm_gen_pool_create - managed gen_pool_create
 575  * @dev: device that provides the gen_pool
 576  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 577  * @nid: node id of the node the pool structure should be allocated on, or -1
 578  *
 579  * Create a new special memory pool that can be used to manage special purpose
 580  * memory not managed by the regular kmalloc/kfree interface. The pool will be
 581  * automatically destroyed by the device management code.
 582  */
 583 struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
 584                 int nid)
 585 {
 586         struct gen_pool **ptr, *pool;
 587
 588         ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
 589         if (!ptr)
 590                 return NULL;
 591
 592         pool = gen_pool_create(min_alloc_order, nid);
 593         if (pool) {
 594                 *ptr = pool;
 595                 devres_add(dev, ptr);
 596         } else {
 597                 devres_free(ptr);
 598         }
 599
 600         return pool;
 601 }
 602 EXPORT_SYMBOL(devm_gen_pool_create);
 603
 604 /**
 605  * gen_pool_get - Obtain the gen_pool (if any) for a device
 606  * @dev: device to retrieve the gen_pool from
 607  *
 608  * Returns the gen_pool for the device if one is present, or NULL.
 609  */
 610 struct gen_pool *gen_pool_get(struct device *dev)
 611 {
 612         struct gen_pool **p = devres_find(dev, devm_gen_pool_release, NULL,
 613                                         NULL);
 614
 615         if (!p)
 616                 return NULL;
 617         return *p;
 618 }
 619 EXPORT_SYMBOL_GPL(gen_pool_get);
 620
 621 #ifdef CONFIG_OF
 622 /**
 623  * of_gen_pool_get - find a pool by phandle property
 624  * @np: device node
 625  * @propname: property name containing phandle(s)
 626  * @index: index into the phandle array
 627  *
 628  * Returns the pool that contains the chunk starting at the physical
 629  * address of the device tree node pointed at by the phandle property,
 630  * or NULL if not found.
 631  */
 632 struct gen_pool *of_gen_pool_get(struct device_node *np,
 633         const char *propname, int index)
 634 {
 635         struct platform_device *pdev;
 636         struct device_node *np_pool;
 637
 638         np_pool = of_parse_phandle(np, propname, index);
 639         if (!np_pool)
 640                 return NULL;
 641         pdev = of_find_device_by_node(np_pool);
 642         of_node_put(np_pool);
 643         if (!pdev)
 644                 return NULL;
 645         return gen_pool_get(&pdev->dev);
 646 }
 647 EXPORT_SYMBOL_GPL(of_gen_pool_get);
 648 #endif /* CONFIG_OF */