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