1 files changed, 402 insertions, 0 deletions
diff --git a/lib/genalloc.c b/lib/genalloc.c
new file mode 100644
index 00000000..6bc04aab
--- /dev/null
+++ b/lib/genalloc.c
@@ -0,0 +1,402 @@
+/*
+ * 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/export.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);