dmapool.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * DMA Pool allocator
  4 *
  5 * Copyright 2001 David Brownell
  6 * Copyright 2007 Intel Corporation
  7 *   Author: Matthew Wilcox <willy@linux.intel.com>
  8 *
  9 * This allocator returns small blocks of a given size which are DMA-able by
 10 * the given device.  It uses the dma_alloc_coherent page allocator to get
 11 * new pages, then splits them up into blocks of the required size.
 12 * Many older drivers still have their own code to do this.
 13 *
 14 * The current design of this allocator is fairly simple.  The pool is
 15 * represented by the 'struct dma_pool' which keeps a doubly-linked list of
 16 * allocated pages.  Each page in the page_list is split into blocks of at
 17 * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
 18 * list of free blocks across all pages.  Used blocks aren't tracked, but we
 19 * keep a count of how many are currently allocated from each page.
 20 */
 21
 22#include <linux/device.h>
 23#include <linux/dma-mapping.h>
 24#include <linux/dmapool.h>
 25#include <linux/kernel.h>
 26#include <linux/list.h>
 27#include <linux/export.h>
 28#include <linux/mutex.h>
 29#include <linux/poison.h>
 30#include <linux/sched.h>
 31#include <linux/sched/mm.h>
 32#include <linux/slab.h>
 33#include <linux/stat.h>
 34#include <linux/spinlock.h>
 35#include <linux/string.h>
 36#include <linux/types.h>
 37#include <linux/wait.h>
 38
 39#ifdef CONFIG_SLUB_DEBUG_ON
 40#define DMAPOOL_DEBUG 1
 41#endif
 42
 43struct dma_block {
 44	struct dma_block *next_block;
 45	dma_addr_t dma;
 46};
 47
 48struct dma_pool {		/* the pool */
 49	struct list_head page_list;
 50	spinlock_t lock;
 51	struct dma_block *next_block;
 52	size_t nr_blocks;
 53	size_t nr_active;
 54	size_t nr_pages;
 55	struct device *dev;
 56	unsigned int size;
 57	unsigned int allocation;
 58	unsigned int boundary;
 59	int node;
 60	char name[32];
 61	struct list_head pools;
 62};
 63
 64struct dma_page {		/* cacheable header for 'allocation' bytes */
 65	struct list_head page_list;
 66	void *vaddr;
 67	dma_addr_t dma;
 68};
 69
 70static DEFINE_MUTEX(pools_lock);
 71static DEFINE_MUTEX(pools_reg_lock);
 72
 73static ssize_t pools_show(struct device *dev, struct device_attribute *attr, char *buf)
 74{
 75	struct dma_pool *pool;
 76	unsigned size;
 77
 78	size = sysfs_emit(buf, "poolinfo - 0.1\n");
 79
 80	mutex_lock(&pools_lock);
 81	list_for_each_entry(pool, &dev->dma_pools, pools) {
 82		/* per-pool info, no real statistics yet */
 83		size += sysfs_emit_at(buf, size, "%-16s %4zu %4zu %4u %2zu\n",
 84				      pool->name, pool->nr_active,
 85				      pool->nr_blocks, pool->size,
 86				      pool->nr_pages);
 87	}
 88	mutex_unlock(&pools_lock);
 89
 90	return size;
 91}
 92
 93static DEVICE_ATTR_RO(pools);
 94
 95#ifdef DMAPOOL_DEBUG
 96static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
 97			     gfp_t mem_flags)
 98{
 99	u8 *data = (void *)block;
100	int i;
101
102	for (i = sizeof(struct dma_block); i < pool->size; i++) {
103		if (data[i] == POOL_POISON_FREED)
104			continue;
105		dev_err(pool->dev, "%s %s, %p (corrupted)\n", __func__,
106			pool->name, block);
107
108		/*
109		 * Dump the first 4 bytes even if they are not
110		 * POOL_POISON_FREED
111		 */
112		print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
113				data, pool->size, 1);
114		break;
115	}
116
117	if (!want_init_on_alloc(mem_flags))
118		memset(block, POOL_POISON_ALLOCATED, pool->size);
119}
120
121static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
122{
123	struct dma_page *page;
124
125	list_for_each_entry(page, &pool->page_list, page_list) {
126		if (dma < page->dma)
127			continue;
128		if ((dma - page->dma) < pool->allocation)
129			return page;
130	}
131	return NULL;
132}
133
134static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
135{
136	struct dma_block *block = pool->next_block;
137	struct dma_page *page;
138
139	page = pool_find_page(pool, dma);
140	if (!page) {
141		dev_err(pool->dev, "%s %s, %p/%pad (bad dma)\n",
142			__func__, pool->name, vaddr, &dma);
143		return true;
144	}
145
146	while (block) {
147		if (block != vaddr) {
148			block = block->next_block;
149			continue;
150		}
151		dev_err(pool->dev, "%s %s, dma %pad already free\n",
152			__func__, pool->name, &dma);
153		return true;
154	}
155
156	memset(vaddr, POOL_POISON_FREED, pool->size);
157	return false;
158}
159
160static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
161{
162	memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
163}
164#else
165static void pool_check_block(struct dma_pool *pool, struct dma_block *block,
166			     gfp_t mem_flags)
167{
168}
169
170static bool pool_block_err(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
171{
172	if (want_init_on_free())
173		memset(vaddr, 0, pool->size);
174	return false;
175}
176
177static void pool_init_page(struct dma_pool *pool, struct dma_page *page)
178{
179}
180#endif
181
182static struct dma_block *pool_block_pop(struct dma_pool *pool)
183{
184	struct dma_block *block = pool->next_block;
185
186	if (block) {
187		pool->next_block = block->next_block;
188		pool->nr_active++;
189	}
190	return block;
191}
192
193static void pool_block_push(struct dma_pool *pool, struct dma_block *block,
194			    dma_addr_t dma)
195{
196	block->dma = dma;
197	block->next_block = pool->next_block;
198	pool->next_block = block;
199}
200
201
202/**
203 * dma_pool_create_node - Creates a pool of coherent DMA memory blocks.
204 * @name: name of pool, for diagnostics
205 * @dev: device that will be doing the DMA
206 * @size: size of the blocks in this pool.
207 * @align: alignment requirement for blocks; must be a power of two
208 * @boundary: returned blocks won't cross this power of two boundary
209 * @node: optional NUMA node to allocate structs 'dma_pool' and 'dma_page' on
210 * Context: not in_interrupt()
211 *
212 * Given one of these pools, dma_pool_alloc()
213 * may be used to allocate memory.  Such memory will all have coherent
214 * DMA mappings, accessible by the device and its driver without using
215 * cache flushing primitives.  The actual size of blocks allocated may be
216 * larger than requested because of alignment.
217 *
218 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
219 * cross that size boundary.  This is useful for devices which have
220 * addressing restrictions on individual DMA transfers, such as not crossing
221 * boundaries of 4KBytes.
222 *
223 * Return: a dma allocation pool with the requested characteristics, or
224 * %NULL if one can't be created.
225 */
226struct dma_pool *dma_pool_create_node(const char *name, struct device *dev,
227		size_t size, size_t align, size_t boundary, int node)
228{
229	struct dma_pool *retval;
230	size_t allocation;
231	bool empty;
232
233	if (!dev)
234		return NULL;
235
236	if (align == 0)
237		align = 1;
238	else if (align & (align - 1))
239		return NULL;
240
241	if (size == 0 || size > INT_MAX)
242		return NULL;
243	if (size < sizeof(struct dma_block))
244		size = sizeof(struct dma_block);
245
246	size = ALIGN(size, align);
247	allocation = max_t(size_t, size, PAGE_SIZE);
248
249	if (!boundary)
250		boundary = allocation;
251	else if ((boundary < size) || (boundary & (boundary - 1)))
252		return NULL;
253
254	boundary = min(boundary, allocation);
255
256	retval = kzalloc_node(sizeof(*retval), GFP_KERNEL, node);
257	if (!retval)
258		return retval;
259
260	strscpy(retval->name, name, sizeof(retval->name));
261
262	retval->dev = dev;
263
264	INIT_LIST_HEAD(&retval->page_list);
265	spin_lock_init(&retval->lock);
266	retval->size = size;
267	retval->boundary = boundary;
268	retval->allocation = allocation;
269	retval->node = node;
270	INIT_LIST_HEAD(&retval->pools);
271
272	/*
273	 * pools_lock ensures that the ->dma_pools list does not get corrupted.
274	 * pools_reg_lock ensures that there is not a race between
275	 * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
276	 * when the first invocation of dma_pool_create() failed on
277	 * device_create_file() and the second assumes that it has been done (I
278	 * know it is a short window).
279	 */
280	mutex_lock(&pools_reg_lock);
281	mutex_lock(&pools_lock);
282	empty = list_empty(&dev->dma_pools);
283	list_add(&retval->pools, &dev->dma_pools);
284	mutex_unlock(&pools_lock);
285	if (empty) {
286		int err;
287
288		err = device_create_file(dev, &dev_attr_pools);
289		if (err) {
290			mutex_lock(&pools_lock);
291			list_del(&retval->pools);
292			mutex_unlock(&pools_lock);
293			mutex_unlock(&pools_reg_lock);
294			kfree(retval);
295			return NULL;
296		}
297	}
298	mutex_unlock(&pools_reg_lock);
299	return retval;
300}
301EXPORT_SYMBOL(dma_pool_create_node);
302
303static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
304{
305	unsigned int next_boundary = pool->boundary, offset = 0;
306	struct dma_block *block, *first = NULL, *last = NULL;
307
308	pool_init_page(pool, page);
309	while (offset + pool->size <= pool->allocation) {
310		if (offset + pool->size > next_boundary) {
311			offset = next_boundary;
312			next_boundary += pool->boundary;
313			continue;
314		}
315
316		block = page->vaddr + offset;
317		block->dma = page->dma + offset;
318		block->next_block = NULL;
319
320		if (last)
321			last->next_block = block;
322		else
323			first = block;
324		last = block;
325
326		offset += pool->size;
327		pool->nr_blocks++;
328	}
329
330	last->next_block = pool->next_block;
331	pool->next_block = first;
332
333	list_add(&page->page_list, &pool->page_list);
334	pool->nr_pages++;
335}
336
337static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
338{
339	struct dma_page *page;
340
341	page = kmalloc_node(sizeof(*page), mem_flags, pool->node);
342	if (!page)
343		return NULL;
344
345	page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
346					 &page->dma, mem_flags);
347	if (!page->vaddr) {
348		kfree(page);
349		return NULL;
350	}
351
352	return page;
353}
354
355/**
356 * dma_pool_destroy - destroys a pool of dma memory blocks.
357 * @pool: dma pool that will be destroyed
358 * Context: !in_interrupt()
359 *
360 * Caller guarantees that no more memory from the pool is in use,
361 * and that nothing will try to use the pool after this call.
362 */
363void dma_pool_destroy(struct dma_pool *pool)
364{
365	struct dma_page *page, *tmp;
366	bool empty, busy = false;
367
368	if (unlikely(!pool))
369		return;
370
371	mutex_lock(&pools_reg_lock);
372	mutex_lock(&pools_lock);
373	list_del(&pool->pools);
374	empty = list_empty(&pool->dev->dma_pools);
375	mutex_unlock(&pools_lock);
376	if (empty)
377		device_remove_file(pool->dev, &dev_attr_pools);
378	mutex_unlock(&pools_reg_lock);
379
380	if (pool->nr_active) {
381		dev_err(pool->dev, "%s %s busy\n", __func__, pool->name);
382		busy = true;
383	}
384
385	list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) {
386		if (!busy)
387			dma_free_coherent(pool->dev, pool->allocation,
388					  page->vaddr, page->dma);
389		list_del(&page->page_list);
390		kfree(page);
391	}
392
393	kfree(pool);
394}
395EXPORT_SYMBOL(dma_pool_destroy);
396
397/**
398 * dma_pool_alloc - get a block of coherent memory
399 * @pool: dma pool that will produce the block
400 * @mem_flags: GFP_* bitmask
401 * @handle: pointer to dma address of block
402 *
403 * Return: the kernel virtual address of a currently unused block,
404 * and reports its dma address through the handle.
405 * If such a memory block can't be allocated, %NULL is returned.
406 */
407void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
408		     dma_addr_t *handle)
409{
410	struct dma_block *block;
411	struct dma_page *page;
412	unsigned long flags;
413
414	might_alloc(mem_flags);
415
416	spin_lock_irqsave(&pool->lock, flags);
417	block = pool_block_pop(pool);
418	if (!block) {
419		/*
420		 * pool_alloc_page() might sleep, so temporarily drop
421		 * &pool->lock
422		 */
423		spin_unlock_irqrestore(&pool->lock, flags);
424
425		page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
426		if (!page)
427			return NULL;
428
429		spin_lock_irqsave(&pool->lock, flags);
430		pool_initialise_page(pool, page);
431		block = pool_block_pop(pool);
432	}
433	spin_unlock_irqrestore(&pool->lock, flags);
434
435	*handle = block->dma;
436	pool_check_block(pool, block, mem_flags);
437	if (want_init_on_alloc(mem_flags))
438		memset(block, 0, pool->size);
439
440	return block;
441}
442EXPORT_SYMBOL(dma_pool_alloc);
443
444/**
445 * dma_pool_free - put block back into dma pool
446 * @pool: the dma pool holding the block
447 * @vaddr: virtual address of block
448 * @dma: dma address of block
449 *
450 * Caller promises neither device nor driver will again touch this block
451 * unless it is first re-allocated.
452 */
453void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
454{
455	struct dma_block *block = vaddr;
456	unsigned long flags;
457
458	spin_lock_irqsave(&pool->lock, flags);
459	if (!pool_block_err(pool, vaddr, dma)) {
460		pool_block_push(pool, block, dma);
461		pool->nr_active--;
462	}
463	spin_unlock_irqrestore(&pool->lock, flags);
464}
465EXPORT_SYMBOL(dma_pool_free);
466
467/*
468 * Managed DMA pool
469 */
470static void dmam_pool_release(struct device *dev, void *res)
471{
472	struct dma_pool *pool = *(struct dma_pool **)res;
473
474	dma_pool_destroy(pool);
475}
476
477static int dmam_pool_match(struct device *dev, void *res, void *match_data)
478{
479	return *(struct dma_pool **)res == match_data;
480}
481
482/**
483 * dmam_pool_create - Managed dma_pool_create()
484 * @name: name of pool, for diagnostics
485 * @dev: device that will be doing the DMA
486 * @size: size of the blocks in this pool.
487 * @align: alignment requirement for blocks; must be a power of two
488 * @allocation: returned blocks won't cross this boundary (or zero)
489 *
490 * Managed dma_pool_create().  DMA pool created with this function is
491 * automatically destroyed on driver detach.
492 *
493 * Return: a managed dma allocation pool with the requested
494 * characteristics, or %NULL if one can't be created.
495 */
496struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
497				  size_t size, size_t align, size_t allocation)
498{
499	struct dma_pool **ptr, *pool;
500
501	ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
502	if (!ptr)
503		return NULL;
504
505	pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
506	if (pool)
507		devres_add(dev, ptr);
508	else
509		devres_free(ptr);
510
511	return pool;
512}
513EXPORT_SYMBOL(dmam_pool_create);
514
515/**
516 * dmam_pool_destroy - Managed dma_pool_destroy()
517 * @pool: dma pool that will be destroyed
518 *
519 * Managed dma_pool_destroy().
520 */
521void dmam_pool_destroy(struct dma_pool *pool)
522{
523	struct device *dev = pool->dev;
524
525	WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
526}
527EXPORT_SYMBOL(dmam_pool_destroy);