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