/* * Basic general purpose allocator for managing special purpose * memory, for example, memory that is not managed by the regular * kmalloc/kfree interface.  Uses for this includes on-device special * memory, uncached memory etc. * * It is safe to use the allocator in NMI handlers and other special * unblockable contexts that could otherwise deadlock on locks.  This * is implemented by using atomic operations and retries on any * conflicts.  The disadvantage is that there may be livelocks in * extreme cases.  For better scalability, one allocator can be used * for each CPU. * * The lockless operation only works if there is enough memory * available.  If new memory is added to the pool a lock has to be * still taken.  So any user relying on locklessness has to ensure * that sufficient memory is preallocated. * * The basic atomic operation of this allocator is cmpxchg on long. * On architectures that don't have NMI-safe cmpxchg implementation, * the allocator can NOT be used in NMI handler.  So code uses the * allocator in NMI handler should depend on * CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG. * * Copyright 2005 (C) Jes Sorensen <jes@trained-monkey.org> * * This source code is licensed under the GNU General Public License, * Version 2.  See the file COPYING for more details. */ #include <linux/slab.h>#include <linux/module.h>#include <linux/bitmap.h>#include <linux/rculist.h>#include <linux/interrupt.h>#include <linux/genalloc.h> static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set){	unsigned long val, nval; 	nval = *addr;	do {		val = nval;		if (val & mask_to_set)			return -EBUSY;		cpu_relax();	} while ((nval = cmpxchg(addr, val, val | mask_to_set)) != val); 	return 0;} static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear){	unsigned long val, nval; 	nval = *addr;	do {		val = nval;		if ((val & mask_to_clear) != mask_to_clear)			return -EBUSY;		cpu_relax();	} while ((nval = cmpxchg(addr, val, val & ~mask_to_clear)) != val); 	return 0;} /* * bitmap_set_ll - set the specified number of bits at the specified position * @map: pointer to a bitmap * @start: a bit position in @map * @nr: number of bits to set * * Set @nr bits start from @start in @map lock-lessly. Several users * can set/clear the same bitmap simultaneously without lock. If two * users set the same bit, one user will return remain bits, otherwise * return 0. */static int bitmap_set_ll(unsigned long *map, int start, int nr){	unsigned long *p = map + BIT_WORD(start);	const int size = start + nr;	int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);	unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start); 	while (nr - bits_to_set >= 0) {		if (set_bits_ll(p, mask_to_set))			return nr;		nr -= bits_to_set;		bits_to_set = BITS_PER_LONG;		mask_to_set = ~0UL;		p++;	}	if (nr) {		mask_to_set &= BITMAP_LAST_WORD_MASK(size);		if (set_bits_ll(p, mask_to_set))			return nr;	} 	return 0;} /* * bitmap_clear_ll - clear the specified number of bits at the specified position * @map: pointer to a bitmap * @start: a bit position in @map * @nr: number of bits to set * * Clear @nr bits start from @start in @map lock-lessly. Several users * can set/clear the same bitmap simultaneously without lock. If two * users clear the same bit, one user will return remain bits, * otherwise return 0. */static int bitmap_clear_ll(unsigned long *map, int start, int nr){	unsigned long *p = map + BIT_WORD(start);	const int size = start + nr;	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); 	while (nr - bits_to_clear >= 0) {		if (clear_bits_ll(p, mask_to_clear))			return nr;		nr -= bits_to_clear;		bits_to_clear = BITS_PER_LONG;		mask_to_clear = ~0UL;		p++;	}	if (nr) {		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);		if (clear_bits_ll(p, mask_to_clear))			return nr;	} 	return 0;} /** * gen_pool_create - create a new special memory pool * @min_alloc_order: log base 2 of number of bytes each bitmap bit represents * @nid: node id of the node the pool structure should be allocated on, or -1 * * Create a new special memory pool that can be used to manage special purpose * memory not managed by the regular kmalloc/kfree interface. */struct gen_pool *gen_pool_create(int min_alloc_order, int nid){	struct gen_pool *pool; 	pool = kmalloc_node(sizeof(struct gen_pool), GFP_KERNEL, nid);	if (pool != NULL) {		spin_lock_init(&pool->lock);		INIT_LIST_HEAD(&pool->chunks);		pool->min_alloc_order = min_alloc_order;	}	return pool;}EXPORT_SYMBOL(gen_pool_create); /** * gen_pool_add_virt - add a new chunk of special memory to the pool * @pool: pool to add new memory chunk to * @virt: virtual starting address of memory chunk to add to pool * @phys: physical starting address of memory chunk to add to pool * @size: size in bytes of the memory chunk to add to pool * @nid: node id of the node the chunk structure and bitmap should be *       allocated on, or -1 * * Add a new chunk of special memory to the specified pool. * * Returns 0 on success or a -ve errno on failure. */int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys,		 size_t size, int nid){	struct gen_pool_chunk *chunk;	int nbits = size >> pool->min_alloc_order;	int nbytes = sizeof(struct gen_pool_chunk) +				(nbits + BITS_PER_BYTE - 1) / BITS_PER_BYTE; 	chunk = kmalloc_node(nbytes, GFP_KERNEL | __GFP_ZERO, nid);	if (unlikely(chunk == NULL))		return -ENOMEM; 	chunk->phys_addr = phys;	chunk->start_addr = virt;	chunk->end_addr = virt + size;	atomic_set(&chunk->avail, size); 	spin_lock(&pool->lock);	list_add_rcu(&chunk->next_chunk, &pool->chunks);	spin_unlock(&pool->lock); 	return 0;}EXPORT_SYMBOL(gen_pool_add_virt); /** * gen_pool_virt_to_phys - return the physical address of memory * @pool: pool to allocate from * @addr: starting address of memory * * Returns the physical address on success, or -1 on error. */phys_addr_t gen_pool_virt_to_phys(struct gen_pool *pool, unsigned long addr){	struct gen_pool_chunk *chunk;	phys_addr_t paddr = -1; 	rcu_read_lock();	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {		if (addr >= chunk->start_addr && addr < chunk->end_addr) {			paddr = chunk->phys_addr + (addr - chunk->start_addr);			break;		}	}	rcu_read_unlock(); 	return paddr;}EXPORT_SYMBOL(gen_pool_virt_to_phys); /** * gen_pool_destroy - destroy a special memory pool * @pool: pool to destroy * * Destroy the specified special memory pool. Verifies that there are no * outstanding allocations. */void gen_pool_destroy(struct gen_pool *pool){	struct list_head *_chunk, *_next_chunk;	struct gen_pool_chunk *chunk;	int order = pool->min_alloc_order;	int bit, end_bit; 	list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {		chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);		list_del(&chunk->next_chunk); 		end_bit = (chunk->end_addr - chunk->start_addr) >> order;		bit = find_next_bit(chunk->bits, end_bit, 0);		BUG_ON(bit < end_bit); 		kfree(chunk);	}	kfree(pool);	return;}EXPORT_SYMBOL(gen_pool_destroy); /** * gen_pool_alloc - allocate special memory from the pool * @pool: pool to allocate from * @size: number of bytes to allocate from the pool * * Allocate the requested number of bytes from the specified pool. * Uses a first-fit algorithm. Can not be used in NMI handler on * architectures without NMI-safe cmpxchg implementation. */unsigned long gen_pool_alloc(struct gen_pool *pool, size_t size){	struct gen_pool_chunk *chunk;	unsigned long addr = 0;	int order = pool->min_alloc_order;	int nbits, start_bit = 0, end_bit, remain; #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG	BUG_ON(in_nmi());#endif 	if (size == 0)		return 0; 	nbits = (size + (1UL << order) - 1) >> order;	rcu_read_lock();	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {		if (size > atomic_read(&chunk->avail))			continue; 		end_bit = (chunk->end_addr - chunk->start_addr) >> order;retry:		start_bit = bitmap_find_next_zero_area(chunk->bits, end_bit,						       start_bit, nbits, 0);		if (start_bit >= end_bit)			continue;		remain = bitmap_set_ll(chunk->bits, start_bit, nbits);		if (remain) {			remain = bitmap_clear_ll(chunk->bits, start_bit,						 nbits - remain);			BUG_ON(remain);			goto retry;		} 		addr = chunk->start_addr + ((unsigned long)start_bit << order);		size = nbits << order;		atomic_sub(size, &chunk->avail);		break;	}	rcu_read_unlock();	return addr;}EXPORT_SYMBOL(gen_pool_alloc); /** * gen_pool_free - free allocated special memory back to the pool * @pool: pool to free to * @addr: starting address of memory to free back to pool * @size: size in bytes of memory to free * * Free previously allocated special memory back to the specified * pool.  Can not be used in NMI handler on architectures without * NMI-safe cmpxchg implementation. */void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size){	struct gen_pool_chunk *chunk;	int order = pool->min_alloc_order;	int start_bit, nbits, remain; #ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG	BUG_ON(in_nmi());#endif 	nbits = (size + (1UL << order) - 1) >> order;	rcu_read_lock();	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {		if (addr >= chunk->start_addr && addr < chunk->end_addr) {			BUG_ON(addr + size > chunk->end_addr);			start_bit = (addr - chunk->start_addr) >> order;			remain = bitmap_clear_ll(chunk->bits, start_bit, nbits);			BUG_ON(remain);			size = nbits << order;			atomic_add(size, &chunk->avail);			rcu_read_unlock();			return;		}	}	rcu_read_unlock();	BUG();}EXPORT_SYMBOL(gen_pool_free); /** * gen_pool_for_each_chunk - call func for every chunk of generic memory pool * @pool:	the generic memory pool * @func:	func to call * @data:	additional data used by @func * * Call @func for every chunk of generic memory pool.  The @func is * called with rcu_read_lock held. */void gen_pool_for_each_chunk(struct gen_pool *pool,	void (*func)(struct gen_pool *pool, struct gen_pool_chunk *chunk, void *data),	void *data){	struct gen_pool_chunk *chunk; 	rcu_read_lock();	list_for_each_entry_rcu(chunk, &(pool)->chunks, next_chunk)		func(pool, chunk, data);	rcu_read_unlock();}EXPORT_SYMBOL(gen_pool_for_each_chunk); /** * gen_pool_avail - get available free space of the pool * @pool: pool to get available free space * * Return available free space of the specified pool. */size_t gen_pool_avail(struct gen_pool *pool){	struct gen_pool_chunk *chunk;	size_t avail = 0; 	rcu_read_lock();	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)		avail += atomic_read(&chunk->avail);	rcu_read_unlock();	return avail;}EXPORT_SYMBOL_GPL(gen_pool_avail); /** * gen_pool_size - get size in bytes of memory managed by the pool * @pool: pool to get size * * Return size in bytes of memory managed by the pool. */size_t gen_pool_size(struct gen_pool *pool){	struct gen_pool_chunk *chunk;	size_t size = 0; 	rcu_read_lock();	list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk)		size += chunk->end_addr - chunk->start_addr;	rcu_read_unlock();	return size;}EXPORT_SYMBOL_GPL(gen_pool_size);