pool.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2012 ARM Ltd.
  4 * Copyright (C) 2020 Google LLC
  5 */
  6#include <linux/cma.h>
  7#include <linux/debugfs.h>
  8#include <linux/dma-map-ops.h>
  9#include <linux/dma-direct.h>
 10#include <linux/init.h>
 11#include <linux/genalloc.h>
 12#include <linux/set_memory.h>
 13#include <linux/slab.h>
 14#include <linux/workqueue.h>
 15
 16static struct gen_pool *atomic_pool_dma __ro_after_init;
 17static unsigned long pool_size_dma;
 18static struct gen_pool *atomic_pool_dma32 __ro_after_init;
 19static unsigned long pool_size_dma32;
 20static struct gen_pool *atomic_pool_kernel __ro_after_init;
 21static unsigned long pool_size_kernel;
 22
 23/* Size can be defined by the coherent_pool command line */
 24static size_t atomic_pool_size;
 25
 26/* Dynamic background expansion when the atomic pool is near capacity */
 27static struct work_struct atomic_pool_work;
 28
 29static int __init early_coherent_pool(char *p)
 30{
 31	atomic_pool_size = memparse(p, &p);
 32	return 0;
 33}
 34early_param("coherent_pool", early_coherent_pool);
 35
 36static void __init dma_atomic_pool_debugfs_init(void)
 37{
 38	struct dentry *root;
 39
 40	root = debugfs_create_dir("dma_pools", NULL);
 41	debugfs_create_ulong("pool_size_dma", 0400, root, &pool_size_dma);
 42	debugfs_create_ulong("pool_size_dma32", 0400, root, &pool_size_dma32);
 43	debugfs_create_ulong("pool_size_kernel", 0400, root, &pool_size_kernel);
 44}
 45
 46static void dma_atomic_pool_size_add(gfp_t gfp, size_t size)
 47{
 48	if (gfp & __GFP_DMA)
 49		pool_size_dma += size;
 50	else if (gfp & __GFP_DMA32)
 51		pool_size_dma32 += size;
 52	else
 53		pool_size_kernel += size;
 54}
 55
 56static bool cma_in_zone(gfp_t gfp)
 57{
 58	unsigned long size;
 59	phys_addr_t end;
 60	struct cma *cma;
 61
 62	cma = dev_get_cma_area(NULL);
 63	if (!cma)
 64		return false;
 65
 66	size = cma_get_size(cma);
 67	if (!size)
 68		return false;
 69
 70	/* CMA can't cross zone boundaries, see cma_activate_area() */
 71	end = cma_get_base(cma) + size - 1;
 72	if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA))
 73		return end <= zone_dma_limit;
 74	if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
 75		return end <= max(DMA_BIT_MASK(32), zone_dma_limit);
 76	return true;
 77}
 78
 79static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
 80			      gfp_t gfp)
 81{
 82	unsigned int order;
 83	struct page *page = NULL;
 84	void *addr;
 85	int ret = -ENOMEM;
 86
 87	/* Cannot allocate larger than MAX_PAGE_ORDER */
 88	order = min(get_order(pool_size), MAX_PAGE_ORDER);
 89
 90	do {
 91		pool_size = 1 << (PAGE_SHIFT + order);
 92		if (cma_in_zone(gfp))
 93			page = dma_alloc_from_contiguous(NULL, 1 << order,
 94							 order, false);
 95		if (!page)
 96			page = alloc_pages(gfp | __GFP_NOWARN, order);
 97	} while (!page && order-- > 0);
 98	if (!page)
 99		goto out;
100
101	arch_dma_prep_coherent(page, pool_size);
102
103#ifdef CONFIG_DMA_DIRECT_REMAP
104	addr = dma_common_contiguous_remap(page, pool_size,
105			pgprot_decrypted(pgprot_dmacoherent(PAGE_KERNEL)),
106			__builtin_return_address(0));
107	if (!addr)
108		goto free_page;
109#else
110	addr = page_to_virt(page);
111#endif
112	/*
113	 * Memory in the atomic DMA pools must be unencrypted, the pools do not
114	 * shrink so no re-encryption occurs in dma_direct_free().
115	 */
116	ret = set_memory_decrypted((unsigned long)page_to_virt(page),
117				   1 << order);
118	if (ret)
119		goto remove_mapping;
120	ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page),
121				pool_size, NUMA_NO_NODE);
122	if (ret)
123		goto encrypt_mapping;
124
125	dma_atomic_pool_size_add(gfp, pool_size);
126	return 0;
127
128encrypt_mapping:
129	ret = set_memory_encrypted((unsigned long)page_to_virt(page),
130				   1 << order);
131	if (WARN_ON_ONCE(ret)) {
132		/* Decrypt succeeded but encrypt failed, purposely leak */
133		goto out;
134	}
135remove_mapping:
136#ifdef CONFIG_DMA_DIRECT_REMAP
137	dma_common_free_remap(addr, pool_size);
138free_page:
139	__free_pages(page, order);
140#endif
141out:
142	return ret;
143}
144
145static void atomic_pool_resize(struct gen_pool *pool, gfp_t gfp)
146{
147	if (pool && gen_pool_avail(pool) < atomic_pool_size)
148		atomic_pool_expand(pool, gen_pool_size(pool), gfp);
149}
150
151static void atomic_pool_work_fn(struct work_struct *work)
152{
153	if (IS_ENABLED(CONFIG_ZONE_DMA))
154		atomic_pool_resize(atomic_pool_dma,
155				   GFP_KERNEL | GFP_DMA);
156	if (IS_ENABLED(CONFIG_ZONE_DMA32))
157		atomic_pool_resize(atomic_pool_dma32,
158				   GFP_KERNEL | GFP_DMA32);
159	atomic_pool_resize(atomic_pool_kernel, GFP_KERNEL);
160}
161
162static __init struct gen_pool *__dma_atomic_pool_init(size_t pool_size,
163						      gfp_t gfp)
164{
165	struct gen_pool *pool;
166	int ret;
167
168	pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
169	if (!pool)
170		return NULL;
171
172	gen_pool_set_algo(pool, gen_pool_first_fit_order_align, NULL);
173
174	ret = atomic_pool_expand(pool, pool_size, gfp);
175	if (ret) {
176		gen_pool_destroy(pool);
177		pr_err("DMA: failed to allocate %zu KiB %pGg pool for atomic allocation\n",
178		       pool_size >> 10, &gfp);
179		return NULL;
180	}
181
182	pr_info("DMA: preallocated %zu KiB %pGg pool for atomic allocations\n",
183		gen_pool_size(pool) >> 10, &gfp);
184	return pool;
185}
186
187#ifdef CONFIG_ZONE_DMA32
188#define has_managed_dma32 has_managed_zone(ZONE_DMA32)
189#else
190#define has_managed_dma32 false
191#endif
192
193static int __init dma_atomic_pool_init(void)
194{
195	int ret = 0;
196
197	/*
198	 * If coherent_pool was not used on the command line, default the pool
199	 * sizes to 128KB per 1GB of memory, min 128KB, max MAX_PAGE_ORDER.
200	 */
201	if (!atomic_pool_size) {
202		unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K);
203		pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES);
204		atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K);
205	}
206	INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);
207
208	/* All memory might be in the DMA zone(s) to begin with */
209	if (has_managed_zone(ZONE_NORMAL)) {
210		atomic_pool_kernel = __dma_atomic_pool_init(atomic_pool_size,
211						    GFP_KERNEL);
212		if (!atomic_pool_kernel)
213			ret = -ENOMEM;
214	}
215	if (has_managed_dma()) {
216		atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
217						GFP_KERNEL | GFP_DMA);
218		if (!atomic_pool_dma)
219			ret = -ENOMEM;
220	}
221	if (has_managed_dma32) {
222		atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
223						GFP_KERNEL | GFP_DMA32);
224		if (!atomic_pool_dma32)
225			ret = -ENOMEM;
226	}
227
228	dma_atomic_pool_debugfs_init();
229	return ret;
230}
231postcore_initcall(dma_atomic_pool_init);
232
233static inline struct gen_pool *dma_guess_pool(struct gen_pool *prev, gfp_t gfp)
234{
235	if (prev == NULL) {
236		if (gfp & GFP_DMA)
237			return atomic_pool_dma ?: atomic_pool_dma32 ?: atomic_pool_kernel;
238		if (gfp & GFP_DMA32)
239			return atomic_pool_dma32 ?: atomic_pool_dma ?: atomic_pool_kernel;
240		return atomic_pool_kernel ?: atomic_pool_dma32 ?: atomic_pool_dma;
241	}
242	if (prev == atomic_pool_kernel)
243		return atomic_pool_dma32 ? atomic_pool_dma32 : atomic_pool_dma;
244	if (prev == atomic_pool_dma32)
245		return atomic_pool_dma;
246	return NULL;
247}
248
249static struct page *__dma_alloc_from_pool(struct device *dev, size_t size,
250		struct gen_pool *pool, void **cpu_addr,
251		bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))
252{
253	unsigned long addr;
254	phys_addr_t phys;
255
256	addr = gen_pool_alloc(pool, size);
257	if (!addr)
258		return NULL;
259
260	phys = gen_pool_virt_to_phys(pool, addr);
261	if (phys_addr_ok && !phys_addr_ok(dev, phys, size)) {
262		gen_pool_free(pool, addr, size);
263		return NULL;
264	}
265
266	if (gen_pool_avail(pool) < atomic_pool_size)
267		schedule_work(&atomic_pool_work);
268
269	*cpu_addr = (void *)addr;
270	memset(*cpu_addr, 0, size);
271	return pfn_to_page(__phys_to_pfn(phys));
272}
273
274struct page *dma_alloc_from_pool(struct device *dev, size_t size,
275		void **cpu_addr, gfp_t gfp,
276		bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))
277{
278	struct gen_pool *pool = NULL;
279	struct page *page;
280	bool pool_found = false;
281
282	while ((pool = dma_guess_pool(pool, gfp))) {
283		pool_found = true;
284		page = __dma_alloc_from_pool(dev, size, pool, cpu_addr,
285					     phys_addr_ok);
286		if (page)
287			return page;
288	}
289
290	if (pool_found)
291		WARN(!(gfp & __GFP_NOWARN), "DMA pool exhausted for %s\n", dev_name(dev));
292	else
293		WARN(1, "Failed to get suitable pool for %s\n", dev_name(dev));
294	return NULL;
295}
296
297bool dma_free_from_pool(struct device *dev, void *start, size_t size)
298{
299	struct gen_pool *pool = NULL;
300
301	while ((pool = dma_guess_pool(pool, 0))) {
302		if (!gen_pool_has_addr(pool, (unsigned long)start, size))
303			continue;
304		gen_pool_free(pool, (unsigned long)start, size);
305		return true;
306	}
307
308	return false;
309}