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_address.h>
  38 #include <linux/of_device.h>
  39
  40 static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
  41 {
  42         return chunk->end_addr - chunk->start_addr + 1;
  43 }
  44
  45 static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
  46 {
  47         unsigned long val, nval;
  48
  49         nval = *addr;
  50         do {
  51                 val = nval;
  52                 if (val & mask_to_set)
  53                         return -EBUSY;
  54                 cpu_relax();
  55         } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
  56
  57         return 0;
  58 }
  59
  60 static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
  61 {
  62         unsigned long val, nval;
  63
  64         nval = *addr;
  65         do {
  66                 val = nval;
  67                 if ((val & mask_to_clear) != mask_to_clear)
  68                         return -EBUSY;
  69                 cpu_relax();
  70         } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
  71
  72         return 0;
  73 }
  74
  75 /*
  76  * bitmap_set_ll - set the specified number of bits at the specified position
  77  * @map: pointer to a bitmap
  78  * @start: a bit position in @map
  79  * @nr: number of bits to set
  80  *
  81  * Set @nr bits start from @start in @map lock-lessly. Several users
  82  * can set/clear the same bitmap simultaneously without lock. If two
  83  * users set the same bit, one user will return remain bits, otherwise
  84  * return 0.
  85  */
  86 static int bitmap_set_ll(unsigned long *map, int start, int nr)
  87 {
  88         unsigned long *p = map + BIT_WORD(start);
  89         const int size = start + nr;
  90         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
  91         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
  92
  93         while (nr - bits_to_set >= 0) {
  94                 if (set_bits_ll(p, mask_to_set))
  95                         return nr;
  96                 nr -= bits_to_set;
  97                 bits_to_set = BITS_PER_LONG;
  98                 mask_to_set = ~0UL;
  99                 p++;
 100         }
 101         if (nr) {
 102                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
 103                 if (set_bits_ll(p, mask_to_set))
 104                         return nr;
 105         }
 106
 107         return 0;
 108 }
 109
 110 /*
 111  * bitmap_clear_ll - clear the specified number of bits at the specified position
 112  * @map: pointer to a bitmap
 113  * @start: a bit position in @map
 114  * @nr: number of bits to set
 115  *
 116  * Clear @nr bits start from @start in @map lock-lessly. Several users
 117  * can set/clear the same bitmap simultaneously without lock. If two
 118  * users clear the same bit, one user will return remain bits,
 119  * otherwise return 0.
 120  */
 121 static int bitmap_clear_ll(unsigned long *map, int start, int nr)
 122 {
 123         unsigned long *p = map + BIT_WORD(start);
 124         const int size = start + nr;
 125         int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
 126         unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
 127
 128         while (nr - bits_to_clear >= 0) {
 129                 if (clear_bits_ll(p, mask_to_clear))
 130                         return nr;
 131                 nr -= bits_to_clear;
 132                 bits_to_clear = BITS_PER_LONG;
 133                 mask_to_clear = ~0UL;
 134                 p++;
 135         }
 136         if (nr) {
 137                 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
 138                 if (clear_bits_ll(p, mask_to_clear))
 139                         return nr;
 140         }
 141
 142         return 0;
 143 }
 144
 145 /**
 146  * gen_pool_create - create a new special memory pool
 147  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 148  * @nid: node id of the node the pool structure should be allocated on, or -1
 149  *
 150  * Create a new special memory pool that can be used to manage special purpose
 151  * memory not managed by the regular kmalloc/kfree interface.
 152  */
 153 struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
 154 {
 155         struct gen_pool *pool;
 156
 157         pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
 158         if (pool != NULL) {
 159                 spin_lock_init(&pool->lock);
 160                 INIT_LIST_HEAD(&pool->chunks);
 161                 pool->min_alloc_order = min_alloc_order;
 162                 pool->algo = gen_pool_first_fit;
 163                 pool->data = NULL;
 164         }
 165         return pool;
 166 }
 167 EXPORT_SYMBOL(gen_pool_create);
 168
 169 /**
 170  * gen_pool_add_virt - add a new chunk of special memory to the pool
 171  * @pool: pool to add new memory chunk to
 172  * @virt: virtual starting address of memory chunk to add to pool
 173  * @phys: physical starting address of memory chunk to add to pool
 174  * @size: size in bytes of the memory chunk to add to pool
 175  * @nid: node id of the node the chunk structure and bitmap should be
 176  *       allocated on, or -1
 177  *
 178  * Add a new chunk of special memory to the specified pool.
 179  *
 180  * Returns 0 on success or a -ve errno on failure.
 181  */
 182 int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
 183                  size_t size, int nid)
 184 {
 185         struct gen_pool_chunk *chunk;
 186         int nbits = size >> pool->min_alloc_order;
 187         int nbytes = sizeof(struct gen_pool_chunk) +
 188                                 BITS_TO_LONGS(nbits) * sizeof(long);
 189
 190         chunk = kzalloc_node(nbytes, GFP_KERNEL, nid);
 191         if (unlikely(chunk == NULL))
 192                 return -ENOMEM;
 193
 194         chunk->phys_addr = phys;
 195         chunk->start_addr = virt;
 196         chunk->end_addr = virt + size - 1;
 197         atomic_set(&chunk->avail, size);
 198
 199         spin_lock(&pool->lock);
 200         list_add_rcu(&chunk->next_chunk, &pool->chunks);
 201         spin_unlock(&pool->lock);
 202
 203         return 0;
 204 }
 205 EXPORT_SYMBOL(gen_pool_add_virt);
 206
 207 /**
 208  * gen_pool_virt_to_phys - return the physical address of memory
 209  * @pool: pool to allocate from
 210  * @addr: starting address of memory
 211  *
 212  * Returns the physical address on success, or -1 on error.
 213  */
 214 phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
 215 {
 216         struct gen_pool_chunk *chunk;
 217         phys_addr_t paddr = -1;
 218
 219         rcu_read_lock();
 220         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 221                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 222                         paddr = chunk->phys_addr + (addr - chunk->start_addr);
 223                         break;
 224                 }
 225         }
 226         rcu_read_unlock();
 227
 228         return paddr;
 229 }
 230 EXPORT_SYMBOL(gen_pool_virt_to_phys);
 231
 232 /**
 233  * gen_pool_destroy - destroy a special memory pool
 234  * @pool: pool to destroy
 235  *
 236  * Destroy the specified special memory pool. Verifies that there are no
 237  * outstanding allocations.
 238  */
 239 void gen_pool_destroy(struct gen_pool *pool)
 240 {
 241         struct list_head *_chunk, *_next_chunk;
 242         struct gen_pool_chunk *chunk;
 243         int order = pool->min_alloc_order;
 244         int bit, end_bit;
 245
 246         list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
 247                 chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 248                 list_del(&chunk->next_chunk);
 249
 250                 end_bit = chunk_size(chunk) >> order;
 251                 bit = find_next_bit(chunk->bits, end_bit, 0);
 252                 BUG_ON(bit < end_bit);
 253
 254                 kfree(chunk);
 255         }
 256         kfree(pool);
 257         return;
 258 }
 259 EXPORT_SYMBOL(gen_pool_destroy);
 260
 261 /**
 262  * gen_pool_alloc - allocate special memory from the pool
 263  * @pool: pool to allocate from
 264  * @size: number of bytes to allocate from the pool
 265  *
 266  * Allocate the requested number of bytes from the specified pool.
 267  * Uses the pool allocation function (with first-fit algorithm by default).
 268  * Can not be used in NMI handler on architectures without
 269  * NMI-safe cmpxchg implementation.
 270  */
 271 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
 272 {
 273         struct gen_pool_chunk *chunk;
 274         unsigned long addr = 0;
 275         int order = pool->min_alloc_order;
 276         int nbits, start_bit = 0, end_bit, remain;
 277
 278 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 279         BUG_ON(in_nmi());
 280 #endif
 281
 282         if (size == 0)
 283                 return 0;
 284
 285         nbits = (size + (1UL << order) - 1) >> order;
 286         rcu_read_lock();
 287         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 288                 if (size > atomic_read(&chunk->avail))
 289                         continue;
 290
 291                 end_bit = chunk_size(chunk) >> order;
 292 retry:
 293                 start_bit = pool->algo(chunk->bits, end_bit, start_bit, nbits,
 294                                 pool->data);
 295                 if (start_bit >= end_bit)
 296                         continue;
 297                 remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
 298                 if (remain) {
 299                         remain = bitmap_clear_ll(chunk->bits, start_bit,
 300                                                  nbits - remain);
 301                         BUG_ON(remain);
 302                         goto retry;
 303                 }
 304
 305                 addr = chunk->start_addr + ((unsigned long)start_bit << order);
 306                 size = nbits << order;
 307                 atomic_sub(size, &chunk->avail);
 308                 break;
 309         }
 310         rcu_read_unlock();
 311         return addr;
 312 }
 313 EXPORT_SYMBOL(gen_pool_alloc);
 314
 315 /**
 316  * gen_pool_free - free allocated special memory back to the pool
 317  * @pool: pool to free to
 318  * @addr: starting address of memory to free back to pool
 319  * @size: size in bytes of memory to free
 320  *
 321  * Free previously allocated special memory back to the specified
 322  * pool.  Can not be used in NMI handler on architectures without
 323  * NMI-safe cmpxchg implementation.
 324  */
 325 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 326 {
 327         struct gen_pool_chunk *chunk;
 328         int order = pool->min_alloc_order;
 329         int start_bit, nbits, remain;
 330
 331 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
 332         BUG_ON(in_nmi());
 333 #endif
 334
 335         nbits = (size + (1UL << order) - 1) >> order;
 336         rcu_read_lock();
 337         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
 338                 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
 339                         BUG_ON(addr + size - 1 > chunk->end_addr);
 340                         start_bit = (addr - chunk->start_addr) >> order;
 341                         remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
 342                         BUG_ON(remain);
 343                         size = nbits << order;
 344                         atomic_add(size, &chunk->avail);
 345                         rcu_read_unlock();
 346                         return;
 347                 }
 348         }
 349         rcu_read_unlock();
 350         BUG();
 351 }
 352 EXPORT_SYMBOL(gen_pool_free);
 353
 354 /**
 355  * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
 356  * @pool:       the generic memory pool
 357  * @func:       func to call
 358  * @data:       additional data used by @func
 359  *
 360  * Call @func for every chunk of generic memory pool.  The @func is
 361  * called with rcu_read_lock held.
 362  */
 363 void gen_pool_for_each_chunk(struct gen_pool *pool,
 364         void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
 365         void *data)
 366 {
 367         struct gen_pool_chunk *chunk;
 368
 369         rcu_read_lock();
 370         list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
 371                 func(pool, chunk, data);
 372         rcu_read_unlock();
 373 }
 374 EXPORT_SYMBOL(gen_pool_for_each_chunk);
 375
 376 /**
 377  * gen_pool_avail - get available free space of the pool
 378  * @pool: pool to get available free space
 379  *
 380  * Return available free space of the specified pool.
 381  */
 382 size_t gen_pool_avail(struct gen_pool *pool)
 383 {
 384         struct gen_pool_chunk *chunk;
 385         size_t avail = 0;
 386
 387         rcu_read_lock();
 388         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 389                 avail += atomic_read(&chunk->avail);
 390         rcu_read_unlock();
 391         return avail;
 392 }
 393 EXPORT_SYMBOL_GPL(gen_pool_avail);
 394
 395 /**
 396  * gen_pool_size - get size in bytes of memory managed by the pool
 397  * @pool: pool to get size
 398  *
 399  * Return size in bytes of memory managed by the pool.
 400  */
 401 size_t gen_pool_size(struct gen_pool *pool)
 402 {
 403         struct gen_pool_chunk *chunk;
 404         size_t size = 0;
 405
 406         rcu_read_lock();
 407         list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
 408                 size += chunk_size(chunk);
 409         rcu_read_unlock();
 410         return size;
 411 }
 412 EXPORT_SYMBOL_GPL(gen_pool_size);
 413
 414 /**
 415  * gen_pool_set_algo - set the allocation algorithm
 416  * @pool: pool to change allocation algorithm
 417  * @algo: custom algorithm function
 418  * @data: additional data used by @algo
 419  *
 420  * Call @algo for each memory allocation in the pool.
 421  * If @algo is NULL use gen_pool_first_fit as default
 422  * memory allocation function.
 423  */
 424 void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
 425 {
 426         rcu_read_lock();
 427
 428         pool->algo = algo;
 429         if (!pool->algo)
 430                 pool->algo = gen_pool_first_fit;
 431
 432         pool->data = data;
 433
 434         rcu_read_unlock();
 435 }
 436 EXPORT_SYMBOL(gen_pool_set_algo);
 437
 438 /**
 439  * gen_pool_first_fit - find the first available region
 440  * of memory matching the size requirement (no alignment constraint)
 441  * @map: The address to base the search on
 442  * @size: The bitmap size in bits
 443  * @start: The bitnumber to start searching at
 444  * @nr: The number of zeroed bits we're looking for
 445  * @data: additional data - unused
 446  */
 447 unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
 448                 unsigned long start, unsigned int nr, void *data)
 449 {
 450         return bitmap_find_next_zero_area(map, size, start, nr, 0);
 451 }
 452 EXPORT_SYMBOL(gen_pool_first_fit);
 453
 454 /**
 455  * gen_pool_best_fit - find the best fitting region of memory
 456  * macthing the size requirement (no alignment constraint)
 457  * @map: The address to base the search on
 458  * @size: The bitmap size in bits
 459  * @start: The bitnumber to start searching at
 460  * @nr: The number of zeroed bits we're looking for
 461  * @data: additional data - unused
 462  *
 463  * Iterate over the bitmap to find the smallest free region
 464  * which we can allocate the memory.
 465  */
 466 unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
 467                 unsigned long start, unsigned int nr, void *data)
 468 {
 469         unsigned long start_bit = size;
 470         unsigned long len = size + 1;
 471         unsigned long index;
 472
 473         index = bitmap_find_next_zero_area(map, size, start, nr, 0);
 474
 475         while (index < size) {
 476                 int next_bit = find_next_bit(map, size, index + nr);
 477                 if ((next_bit - index) < len) {
 478                         len = next_bit - index;
 479                         start_bit = index;
 480                         if (len == nr)
 481                                 return start_bit;
 482                 }
 483                 index = bitmap_find_next_zero_area(map, size,
 484                                                    next_bit + 1, nr, 0);
 485         }
 486
 487         return start_bit;
 488 }
 489 EXPORT_SYMBOL(gen_pool_best_fit);
 490
 491 static void devm_gen_pool_release(struct device *dev, void *res)
 492 {
 493         gen_pool_destroy(*(struct gen_pool **)res);
 494 }
 495
 496 /**
 497  * devm_gen_pool_create - managed gen_pool_create
 498  * @dev: device that provides the gen_pool
 499  * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
 500  * @nid: node id of the node the pool structure should be allocated on, or -1
 501  *
 502  * Create a new special memory pool that can be used to manage special purpose
 503  * memory not managed by the regular kmalloc/kfree interface. The pool will be
 504  * automatically destroyed by the device management code.
 505  */
 506 struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
 507                 int nid)
 508 {
 509         struct gen_pool **ptr, *pool;
 510
 511         ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
 512
 513         pool = gen_pool_create(min_alloc_order, nid);
 514         if (pool) {
 515                 *ptr = pool;
 516                 devres_add(dev, ptr);
 517         } else {
 518                 devres_free(ptr);
 519         }
 520
 521         return pool;
 522 }
 523
 524 /**
 525  * dev_get_gen_pool - Obtain the gen_pool (if any) for a device
 526  * @dev: device to retrieve the gen_pool from
 527  *
 528  * Returns the gen_pool for the device if one is present, or NULL.
 529  */
 530 struct gen_pool *dev_get_gen_pool(struct device *dev)
 531 {
 532         struct gen_pool **p = devres_find(dev, devm_gen_pool_release, NULL,
 533                                         NULL);
 534
 535         if (!p)
 536                 return NULL;
 537         return *p;
 538 }
 539 EXPORT_SYMBOL_GPL(dev_get_gen_pool);
 540
 541 #ifdef CONFIG_OF
 542 /**
 543  * of_get_named_gen_pool - find a pool by phandle property
 544  * @np: device node
 545  * @propname: property name containing phandle(s)
 546  * @index: index into the phandle array
 547  *
 548  * Returns the pool that contains the chunk starting at the physical
 549  * address of the device tree node pointed at by the phandle property,
 550  * or NULL if not found.
 551  */
 552 struct gen_pool *of_get_named_gen_pool(struct device_node *np,
 553         const char *propname, int index)
 554 {
 555         struct platform_device *pdev;
 556         struct device_node *np_pool;
 557
 558         np_pool = of_parse_phandle(np, propname, index);
 559         if (!np_pool)
 560                 return NULL;
 561         pdev = of_find_device_by_node(np_pool);
 562         if (!pdev)
 563                 return NULL;
 564         return dev_get_gen_pool(&pdev->dev);
 565 }
 566 EXPORT_SYMBOL_GPL(of_get_named_gen_pool);
 567 #endif /* CONFIG_OF */