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.
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
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.
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.
25 * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org>
27 * This source code is licensed under the GNU General Public License,
28 * Version 2. See the file COPYING for more details.
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>
40 static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
42 return chunk->end_addr - chunk->start_addr + 1;
45 static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
47 unsigned long val, nval;
52 if (val & mask_to_set)
55 } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
60 static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
62 unsigned long val, nval;
67 if ((val & mask_to_clear) != mask_to_clear)
70 } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
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
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
86 static int bitmap_set_ll(unsigned long *map, int start, int nr)
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);
93 while (nr - bits_to_set >= 0) {
94 if (set_bits_ll(p, mask_to_set))
97 bits_to_set = BITS_PER_LONG;
102 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
103 if (set_bits_ll(p, mask_to_set))
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
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.
121 static int bitmap_clear_ll(unsigned long *map, int start, int nr)
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);
128 while (nr - bits_to_clear >= 0) {
129 if (clear_bits_ll(p, mask_to_clear))
132 bits_to_clear = BITS_PER_LONG;
133 mask_to_clear = ~0UL;
137 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
138 if (clear_bits_ll(p, mask_to_clear))
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
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.
153 struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
155 struct gen_pool *pool;
157 pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
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;
167 EXPORT_SYMBOL(gen_pool_create);
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
178 * Add a new chunk of special memory to the specified pool.
180 * Returns 0 on success or a -ve errno on failure.
182 int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,
183 size_t size, int nid)
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);
190 chunk = kzalloc_node(nbytes, GFP_KERNEL, nid);
191 if (unlikely(chunk == NULL))
194 chunk->phys_addr = phys;
195 chunk->start_addr = virt;
196 chunk->end_addr = virt + size - 1;
197 atomic_set(&chunk->avail, size);
199 spin_lock(&pool->lock);
200 list_add_rcu(&chunk->next_chunk, &pool->chunks);
201 spin_unlock(&pool->lock);
205 EXPORT_SYMBOL(gen_pool_add_virt);
208 * gen_pool_virt_to_phys - return the physical address of memory
209 * @pool: pool to allocate from
210 * @addr: starting address of memory
212 * Returns the physical address on success, or -1 on error.
214 phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr)
216 struct gen_pool_chunk *chunk;
217 phys_addr_t paddr = -1;
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);
230 EXPORT_SYMBOL(gen_pool_virt_to_phys);
233 * gen_pool_destroy - destroy a special memory pool
234 * @pool: pool to destroy
236 * Destroy the specified special memory pool. Verifies that there are no
237 * outstanding allocations.
239 void gen_pool_destroy(struct gen_pool *pool)
241 struct list_head *_chunk, *_next_chunk;
242 struct gen_pool_chunk *chunk;
243 int order = pool->min_alloc_order;
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);
250 end_bit = chunk_size(chunk) >> order;
251 bit = find_next_bit(chunk->bits, end_bit, 0);
252 BUG_ON(bit < end_bit);
259 EXPORT_SYMBOL(gen_pool_destroy);
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
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.
271 unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size)
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;
278 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
285 nbits = (size + (1UL << order) - 1) >> order;
287 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
288 if (size > atomic_read(&chunk->avail))
291 end_bit = chunk_size(chunk) >> order;
293 start_bit = pool->algo(chunk->bits, end_bit, start_bit, nbits,
295 if (start_bit >= end_bit)
297 remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
299 remain = bitmap_clear_ll(chunk->bits, start_bit,
305 addr = chunk->start_addr + ((unsigned long)start_bit << order);
306 size = nbits << order;
307 atomic_sub(size, &chunk->avail);
313 EXPORT_SYMBOL(gen_pool_alloc);
316 * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
317 * @pool: pool to allocate from
318 * @size: number of bytes to allocate from the pool
319 * @dma: dma-view physical address return value. Use NULL if unneeded.
321 * Allocate the requested number of bytes from the specified pool.
322 * Uses the pool allocation function (with first-fit algorithm by default).
323 * Can not be used in NMI handler on architectures without
324 * NMI-safe cmpxchg implementation.
326 void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
333 vaddr = gen_pool_alloc(pool, size);
338 *dma = gen_pool_virt_to_phys(pool, vaddr);
340 return (void *)vaddr;
342 EXPORT_SYMBOL(gen_pool_dma_alloc);
345 * gen_pool_free - free allocated special memory back to the pool
346 * @pool: pool to free to
347 * @addr: starting address of memory to free back to pool
348 * @size: size in bytes of memory to free
350 * Free previously allocated special memory back to the specified
351 * pool. Can not be used in NMI handler on architectures without
352 * NMI-safe cmpxchg implementation.
354 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
356 struct gen_pool_chunk *chunk;
357 int order = pool->min_alloc_order;
358 int start_bit, nbits, remain;
360 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
364 nbits = (size + (1UL << order) - 1) >> order;
366 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
367 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
368 BUG_ON(addr + size - 1 > chunk->end_addr);
369 start_bit = (addr - chunk->start_addr) >> order;
370 remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
372 size = nbits << order;
373 atomic_add(size, &chunk->avail);
381 EXPORT_SYMBOL(gen_pool_free);
384 * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
385 * @pool: the generic memory pool
386 * @func: func to call
387 * @data: additional data used by @func
389 * Call @func for every chunk of generic memory pool. The @func is
390 * called with rcu_read_lock held.
392 void gen_pool_for_each_chunk(struct gen_pool *pool,
393 void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
396 struct gen_pool_chunk *chunk;
399 list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
400 func(pool, chunk, data);
403 EXPORT_SYMBOL(gen_pool_for_each_chunk);
406 * addr_in_gen_pool - checks if an address falls within the range of a pool
407 * @pool: the generic memory pool
408 * @start: start address
409 * @size: size of the region
411 * Check if the range of addresses falls within the specified pool. Returns
412 * true if the entire range is contained in the pool and false otherwise.
414 bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
418 unsigned long end = start + size;
419 struct gen_pool_chunk *chunk;
422 list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
423 if (start >= chunk->start_addr && start <= chunk->end_addr) {
424 if (end <= chunk->end_addr) {
435 * gen_pool_avail - get available free space of the pool
436 * @pool: pool to get available free space
438 * Return available free space of the specified pool.
440 size_t gen_pool_avail(struct gen_pool *pool)
442 struct gen_pool_chunk *chunk;
446 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
447 avail += atomic_read(&chunk->avail);
451 EXPORT_SYMBOL_GPL(gen_pool_avail);
454 * gen_pool_size - get size in bytes of memory managed by the pool
455 * @pool: pool to get size
457 * Return size in bytes of memory managed by the pool.
459 size_t gen_pool_size(struct gen_pool *pool)
461 struct gen_pool_chunk *chunk;
465 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
466 size += chunk_size(chunk);
470 EXPORT_SYMBOL_GPL(gen_pool_size);
473 * gen_pool_set_algo - set the allocation algorithm
474 * @pool: pool to change allocation algorithm
475 * @algo: custom algorithm function
476 * @data: additional data used by @algo
478 * Call @algo for each memory allocation in the pool.
479 * If @algo is NULL use gen_pool_first_fit as default
480 * memory allocation function.
482 void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
488 pool->algo = gen_pool_first_fit;
494 EXPORT_SYMBOL(gen_pool_set_algo);
497 * gen_pool_first_fit - find the first available region
498 * of memory matching the size requirement (no alignment constraint)
499 * @map: The address to base the search on
500 * @size: The bitmap size in bits
501 * @start: The bitnumber to start searching at
502 * @nr: The number of zeroed bits we're looking for
503 * @data: additional data - unused
505 unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
506 unsigned long start, unsigned int nr, void *data)
508 return bitmap_find_next_zero_area(map, size, start, nr, 0);
510 EXPORT_SYMBOL(gen_pool_first_fit);
513 * gen_pool_first_fit_order_align - find the first available region
514 * of memory matching the size requirement. The region will be aligned
515 * to the order of the size specified.
516 * @map: The address to base the search on
517 * @size: The bitmap size in bits
518 * @start: The bitnumber to start searching at
519 * @nr: The number of zeroed bits we're looking for
520 * @data: additional data - unused
522 unsigned long gen_pool_first_fit_order_align(unsigned long *map,
523 unsigned long size, unsigned long start,
524 unsigned int nr, void *data)
526 unsigned long align_mask = roundup_pow_of_two(nr) - 1;
528 return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
530 EXPORT_SYMBOL(gen_pool_first_fit_order_align);
533 * gen_pool_best_fit - find the best fitting region of memory
534 * macthing the size requirement (no alignment constraint)
535 * @map: The address to base the search on
536 * @size: The bitmap size in bits
537 * @start: The bitnumber to start searching at
538 * @nr: The number of zeroed bits we're looking for
539 * @data: additional data - unused
541 * Iterate over the bitmap to find the smallest free region
542 * which we can allocate the memory.
544 unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
545 unsigned long start, unsigned int nr, void *data)
547 unsigned long start_bit = size;
548 unsigned long len = size + 1;
551 index = bitmap_find_next_zero_area(map, size, start, nr, 0);
553 while (index < size) {
554 int next_bit = find_next_bit(map, size, index + nr);
555 if ((next_bit - index) < len) {
556 len = next_bit - index;
561 index = bitmap_find_next_zero_area(map, size,
562 next_bit + 1, nr, 0);
567 EXPORT_SYMBOL(gen_pool_best_fit);
569 static void devm_gen_pool_release(struct device *dev, void *res)
571 gen_pool_destroy(*(struct gen_pool **)res);
575 * devm_gen_pool_create - managed gen_pool_create
576 * @dev: device that provides the gen_pool
577 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
578 * @nid: node id of the node the pool structure should be allocated on, or -1
580 * Create a new special memory pool that can be used to manage special purpose
581 * memory not managed by the regular kmalloc/kfree interface. The pool will be
582 * automatically destroyed by the device management code.
584 struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
587 struct gen_pool **ptr, *pool;
589 ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
591 pool = gen_pool_create(min_alloc_order, nid);
594 devres_add(dev, ptr);
601 EXPORT_SYMBOL(devm_gen_pool_create);
604 * dev_get_gen_pool - Obtain the gen_pool (if any) for a device
605 * @dev: device to retrieve the gen_pool from
607 * Returns the gen_pool for the device if one is present, or NULL.
609 struct gen_pool *dev_get_gen_pool(struct device *dev)
611 struct gen_pool **p = devres_find(dev, devm_gen_pool_release, NULL,
618 EXPORT_SYMBOL_GPL(dev_get_gen_pool);
622 * of_get_named_gen_pool - find a pool by phandle property
624 * @propname: property name containing phandle(s)
625 * @index: index into the phandle array
627 * Returns the pool that contains the chunk starting at the physical
628 * address of the device tree node pointed at by the phandle property,
629 * or NULL if not found.
631 struct gen_pool *of_get_named_gen_pool(struct device_node *np,
632 const char *propname, int index)
634 struct platform_device *pdev;
635 struct device_node *np_pool;
637 np_pool = of_parse_phandle(np, propname, index);
640 pdev = of_find_device_by_node(np_pool);
641 of_node_put(np_pool);
644 return dev_get_gen_pool(&pdev->dev);
646 EXPORT_SYMBOL_GPL(of_get_named_gen_pool);
647 #endif /* CONFIG_OF */