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_device.h>
39 static inline size_t chunk_size(const struct gen_pool_chunk *chunk)
41 return chunk->end_addr - chunk->start_addr + 1;
44 static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
46 unsigned long val, nval;
51 if (val & mask_to_set)
54 } while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val);
59 static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
61 unsigned long val, nval;
66 if ((val & mask_to_clear) != mask_to_clear)
69 } while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val);
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
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
85 static int bitmap_set_ll(unsigned long *map, int start, int nr)
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);
92 while (nr - bits_to_set >= 0) {
93 if (set_bits_ll(p, mask_to_set))
96 bits_to_set = BITS_PER_LONG;
101 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
102 if (set_bits_ll(p, mask_to_set))
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
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.
120 static int bitmap_clear_ll(unsigned long *map, int start, int nr)
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);
127 while (nr - bits_to_clear >= 0) {
128 if (clear_bits_ll(p, mask_to_clear))
131 bits_to_clear = BITS_PER_LONG;
132 mask_to_clear = ~0UL;
136 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
137 if (clear_bits_ll(p, mask_to_clear))
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
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.
152 struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
154 struct gen_pool *pool;
156 pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);
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;
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);
256 kfree_const(pool->name);
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 return gen_pool_alloc_algo(pool, size, pool->algo, pool->data);
275 EXPORT_SYMBOL(gen_pool_alloc);
278 * gen_pool_alloc_algo - allocate special memory from the pool
279 * @pool: pool to allocate from
280 * @size: number of bytes to allocate from the pool
281 * @algo: algorithm passed from caller
282 * @data: data passed to algorithm
284 * Allocate the requested number of bytes from the specified pool.
285 * Uses the pool allocation function (with first-fit algorithm by default).
286 * Can not be used in NMI handler on architectures without
287 * NMI-safe cmpxchg implementation.
289 unsigned long gen_pool_alloc_algo(struct gen_pool *pool, size_t size,
290 genpool_algo_t algo, void *data)
292 struct gen_pool_chunk *chunk;
293 unsigned long addr = 0;
294 int order = pool->min_alloc_order;
295 int nbits, start_bit, end_bit, remain;
297 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
304 nbits = (size + (1UL << order) - 1) >> order;
306 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
307 if (size > atomic_read(&chunk->avail))
311 end_bit = chunk_size(chunk) >> order;
313 start_bit = algo(chunk->bits, end_bit, start_bit,
315 if (start_bit >= end_bit)
317 remain = bitmap_set_ll(chunk->bits, start_bit, nbits);
319 remain = bitmap_clear_ll(chunk->bits, start_bit,
325 addr = chunk->start_addr + ((unsigned long)start_bit << order);
326 size = nbits << order;
327 atomic_sub(size, &chunk->avail);
333 EXPORT_SYMBOL(gen_pool_alloc_algo);
336 * gen_pool_dma_alloc - allocate special memory from the pool for DMA usage
337 * @pool: pool to allocate from
338 * @size: number of bytes to allocate from the pool
339 * @dma: dma-view physical address return value. Use NULL if unneeded.
341 * Allocate the requested number of bytes from the specified pool.
342 * Uses the pool allocation function (with first-fit algorithm by default).
343 * Can not be used in NMI handler on architectures without
344 * NMI-safe cmpxchg implementation.
346 void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size, dma_addr_t *dma)
353 vaddr = gen_pool_alloc(pool, size);
358 *dma = gen_pool_virt_to_phys(pool, vaddr);
360 return (void *)vaddr;
362 EXPORT_SYMBOL(gen_pool_dma_alloc);
365 * gen_pool_free - free allocated special memory back to the pool
366 * @pool: pool to free to
367 * @addr: starting address of memory to free back to pool
368 * @size: size in bytes of memory to free
370 * Free previously allocated special memory back to the specified
371 * pool. Can not be used in NMI handler on architectures without
372 * NMI-safe cmpxchg implementation.
374 void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
376 struct gen_pool_chunk *chunk;
377 int order = pool->min_alloc_order;
378 int start_bit, nbits, remain;
380 #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
384 nbits = (size + (1UL << order) - 1) >> order;
386 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
387 if (addr >= chunk->start_addr && addr <= chunk->end_addr) {
388 BUG_ON(addr + size - 1 > chunk->end_addr);
389 start_bit = (addr - chunk->start_addr) >> order;
390 remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);
392 size = nbits << order;
393 atomic_add(size, &chunk->avail);
401 EXPORT_SYMBOL(gen_pool_free);
404 * gen_pool_for_each_chunk - call func for every chunk of generic memory pool
405 * @pool: the generic memory pool
406 * @func: func to call
407 * @data: additional data used by @func
409 * Call @func for every chunk of generic memory pool. The @func is
410 * called with rcu_read_lock held.
412 void gen_pool_for_each_chunk(struct gen_pool *pool,
413 void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),
416 struct gen_pool_chunk *chunk;
419 list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)
420 func(pool, chunk, data);
423 EXPORT_SYMBOL(gen_pool_for_each_chunk);
426 * addr_in_gen_pool - checks if an address falls within the range of a pool
427 * @pool: the generic memory pool
428 * @start: start address
429 * @size: size of the region
431 * Check if the range of addresses falls within the specified pool. Returns
432 * true if the entire range is contained in the pool and false otherwise.
434 bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
438 unsigned long end = start + size - 1;
439 struct gen_pool_chunk *chunk;
442 list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk) {
443 if (start >= chunk->start_addr && start <= chunk->end_addr) {
444 if (end <= chunk->end_addr) {
455 * gen_pool_avail - get available free space of the pool
456 * @pool: pool to get available free space
458 * Return available free space of the specified pool.
460 size_t gen_pool_avail(struct gen_pool *pool)
462 struct gen_pool_chunk *chunk;
466 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
467 avail += atomic_read(&chunk->avail);
471 EXPORT_SYMBOL_GPL(gen_pool_avail);
474 * gen_pool_size - get size in bytes of memory managed by the pool
475 * @pool: pool to get size
477 * Return size in bytes of memory managed by the pool.
479 size_t gen_pool_size(struct gen_pool *pool)
481 struct gen_pool_chunk *chunk;
485 list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)
486 size += chunk_size(chunk);
490 EXPORT_SYMBOL_GPL(gen_pool_size);
493 * gen_pool_set_algo - set the allocation algorithm
494 * @pool: pool to change allocation algorithm
495 * @algo: custom algorithm function
496 * @data: additional data used by @algo
498 * Call @algo for each memory allocation in the pool.
499 * If @algo is NULL use gen_pool_first_fit as default
500 * memory allocation function.
502 void gen_pool_set_algo(struct gen_pool *pool, genpool_algo_t algo, void *data)
508 pool->algo = gen_pool_first_fit;
514 EXPORT_SYMBOL(gen_pool_set_algo);
517 * gen_pool_first_fit - find the first available region
518 * of memory matching the size requirement (no alignment constraint)
519 * @map: The address to base the search on
520 * @size: The bitmap size in bits
521 * @start: The bitnumber to start searching at
522 * @nr: The number of zeroed bits we're looking for
523 * @data: additional data - unused
524 * @pool: pool to find the fit region memory from
526 unsigned long gen_pool_first_fit(unsigned long *map, unsigned long size,
527 unsigned long start, unsigned int nr, void *data,
528 struct gen_pool *pool)
530 return bitmap_find_next_zero_area(map, size, start, nr, 0);
532 EXPORT_SYMBOL(gen_pool_first_fit);
535 * gen_pool_first_fit_align - find the first available region
536 * of memory matching the size requirement (alignment constraint)
537 * @map: The address to base the search on
538 * @size: The bitmap size in bits
539 * @start: The bitnumber to start searching at
540 * @nr: The number of zeroed bits we're looking for
541 * @data: data for alignment
542 * @pool: pool to get order from
544 unsigned long gen_pool_first_fit_align(unsigned long *map, unsigned long size,
545 unsigned long start, unsigned int nr, void *data,
546 struct gen_pool *pool)
548 struct genpool_data_align *alignment;
549 unsigned long align_mask;
553 order = pool->min_alloc_order;
554 align_mask = ((alignment->align + (1UL << order) - 1) >> order) - 1;
555 return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
557 EXPORT_SYMBOL(gen_pool_first_fit_align);
560 * gen_pool_fixed_alloc - reserve a specific region
561 * @map: The address to base the search on
562 * @size: The bitmap size in bits
563 * @start: The bitnumber to start searching at
564 * @nr: The number of zeroed bits we're looking for
565 * @data: data for alignment
566 * @pool: pool to get order from
568 unsigned long gen_pool_fixed_alloc(unsigned long *map, unsigned long size,
569 unsigned long start, unsigned int nr, void *data,
570 struct gen_pool *pool)
572 struct genpool_data_fixed *fixed_data;
574 unsigned long offset_bit;
575 unsigned long start_bit;
578 order = pool->min_alloc_order;
579 offset_bit = fixed_data->offset >> order;
580 if (WARN_ON(fixed_data->offset & ((1UL << order) - 1)))
583 start_bit = bitmap_find_next_zero_area(map, size,
584 start + offset_bit, nr, 0);
585 if (start_bit != offset_bit)
589 EXPORT_SYMBOL(gen_pool_fixed_alloc);
592 * gen_pool_first_fit_order_align - find the first available region
593 * of memory matching the size requirement. The region will be aligned
594 * to the order of the size specified.
595 * @map: The address to base the search on
596 * @size: The bitmap size in bits
597 * @start: The bitnumber to start searching at
598 * @nr: The number of zeroed bits we're looking for
599 * @data: additional data - unused
600 * @pool: pool to find the fit region memory from
602 unsigned long gen_pool_first_fit_order_align(unsigned long *map,
603 unsigned long size, unsigned long start,
604 unsigned int nr, void *data, struct gen_pool *pool)
606 unsigned long align_mask = roundup_pow_of_two(nr) - 1;
608 return bitmap_find_next_zero_area(map, size, start, nr, align_mask);
610 EXPORT_SYMBOL(gen_pool_first_fit_order_align);
613 * gen_pool_best_fit - find the best fitting region of memory
614 * macthing the size requirement (no alignment constraint)
615 * @map: The address to base the search on
616 * @size: The bitmap size in bits
617 * @start: The bitnumber to start searching at
618 * @nr: The number of zeroed bits we're looking for
619 * @data: additional data - unused
620 * @pool: pool to find the fit region memory from
622 * Iterate over the bitmap to find the smallest free region
623 * which we can allocate the memory.
625 unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
626 unsigned long start, unsigned int nr, void *data,
627 struct gen_pool *pool)
629 unsigned long start_bit = size;
630 unsigned long len = size + 1;
633 index = bitmap_find_next_zero_area(map, size, start, nr, 0);
635 while (index < size) {
636 int next_bit = find_next_bit(map, size, index + nr);
637 if ((next_bit - index) < len) {
638 len = next_bit - index;
643 index = bitmap_find_next_zero_area(map, size,
644 next_bit + 1, nr, 0);
649 EXPORT_SYMBOL(gen_pool_best_fit);
651 static void devm_gen_pool_release(struct device *dev, void *res)
653 gen_pool_destroy(*(struct gen_pool **)res);
656 static int devm_gen_pool_match(struct device *dev, void *res, void *data)
658 struct gen_pool **p = res;
660 /* NULL data matches only a pool without an assigned name */
661 if (!data && !(*p)->name)
664 if (!data || !(*p)->name)
667 return !strcmp((*p)->name, data);
671 * gen_pool_get - Obtain the gen_pool (if any) for a device
672 * @dev: device to retrieve the gen_pool from
673 * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
675 * Returns the gen_pool for the device if one is present, or NULL.
677 struct gen_pool *gen_pool_get(struct device *dev, const char *name)
681 p = devres_find(dev, devm_gen_pool_release, devm_gen_pool_match,
687 EXPORT_SYMBOL_GPL(gen_pool_get);
690 * devm_gen_pool_create - managed gen_pool_create
691 * @dev: device that provides the gen_pool
692 * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents
693 * @nid: node selector for allocated gen_pool, %NUMA_NO_NODE for all nodes
694 * @name: name of a gen_pool or NULL, identifies a particular gen_pool on device
696 * Create a new special memory pool that can be used to manage special purpose
697 * memory not managed by the regular kmalloc/kfree interface. The pool will be
698 * automatically destroyed by the device management code.
700 struct gen_pool *devm_gen_pool_create(struct device *dev, int min_alloc_order,
701 int nid, const char *name)
703 struct gen_pool **ptr, *pool;
704 const char *pool_name = NULL;
706 /* Check that genpool to be created is uniquely addressed on device */
707 if (gen_pool_get(dev, name))
708 return ERR_PTR(-EINVAL);
711 pool_name = kstrdup_const(name, GFP_KERNEL);
713 return ERR_PTR(-ENOMEM);
716 ptr = devres_alloc(devm_gen_pool_release, sizeof(*ptr), GFP_KERNEL);
720 pool = gen_pool_create(min_alloc_order, nid);
725 pool->name = pool_name;
726 devres_add(dev, ptr);
733 kfree_const(pool_name);
735 return ERR_PTR(-ENOMEM);
737 EXPORT_SYMBOL(devm_gen_pool_create);
741 * of_gen_pool_get - find a pool by phandle property
743 * @propname: property name containing phandle(s)
744 * @index: index into the phandle array
746 * Returns the pool that contains the chunk starting at the physical
747 * address of the device tree node pointed at by the phandle property,
748 * or NULL if not found.
750 struct gen_pool *of_gen_pool_get(struct device_node *np,
751 const char *propname, int index)
753 struct platform_device *pdev;
754 struct device_node *np_pool, *parent;
755 const char *name = NULL;
756 struct gen_pool *pool = NULL;
758 np_pool = of_parse_phandle(np, propname, index);
762 pdev = of_find_device_by_node(np_pool);
764 /* Check if named gen_pool is created by parent node device */
765 parent = of_get_parent(np_pool);
766 pdev = of_find_device_by_node(parent);
769 of_property_read_string(np_pool, "label", &name);
771 name = np_pool->name;
774 pool = gen_pool_get(&pdev->dev, name);
775 of_node_put(np_pool);
779 EXPORT_SYMBOL_GPL(of_gen_pool_get);
780 #endif /* CONFIG_OF */