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 <= DMA_BIT_MASK(zone_dma_bits);
74	if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
75		return end <= DMA_BIT_MASK(32);
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, 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_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
187static int __init dma_atomic_pool_init(void)
188{
189	int ret = 0;
190
191	/*
192	 * If coherent_pool was not used on the command line, default the pool
193	 * sizes to 128KB per 1GB of memory, min 128KB, max MAX_PAGE_ORDER.
194	 */
195	if (!atomic_pool_size) {
196		unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K);
197		pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES);
198		atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K);
199	}
200	INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);
201
202	atomic_pool_kernel = __dma_atomic_pool_init(atomic_pool_size,
203						    GFP_KERNEL);
204	if (!atomic_pool_kernel)
205		ret = -ENOMEM;
206	if (has_managed_dma()) {
207		atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
208						GFP_KERNEL | GFP_DMA);
209		if (!atomic_pool_dma)
210			ret = -ENOMEM;
211	}
212	if (IS_ENABLED(CONFIG_ZONE_DMA32)) {
213		atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
214						GFP_KERNEL | GFP_DMA32);
215		if (!atomic_pool_dma32)
216			ret = -ENOMEM;
217	}
218
219	dma_atomic_pool_debugfs_init();
220	return ret;
221}
222postcore_initcall(dma_atomic_pool_init);
223
224static inline struct gen_pool *dma_guess_pool(struct gen_pool *prev, gfp_t gfp)
225{
226	if (prev == NULL) {
227		if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
228			return atomic_pool_dma32;
229		if (atomic_pool_dma && (gfp & GFP_DMA))
230			return atomic_pool_dma;
231		return atomic_pool_kernel;
232	}
233	if (prev == atomic_pool_kernel)
234		return atomic_pool_dma32 ? atomic_pool_dma32 : atomic_pool_dma;
235	if (prev == atomic_pool_dma32)
236		return atomic_pool_dma;
237	return NULL;
238}
239
240static struct page *__dma_alloc_from_pool(struct device *dev, size_t size,
241		struct gen_pool *pool, void **cpu_addr,
242		bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))
243{
244	unsigned long addr;
245	phys_addr_t phys;
246
247	addr = gen_pool_alloc(pool, size);
248	if (!addr)
249		return NULL;
250
251	phys = gen_pool_virt_to_phys(pool, addr);
252	if (phys_addr_ok && !phys_addr_ok(dev, phys, size)) {
253		gen_pool_free(pool, addr, size);
254		return NULL;
255	}
256
257	if (gen_pool_avail(pool) < atomic_pool_size)
258		schedule_work(&atomic_pool_work);
259
260	*cpu_addr = (void *)addr;
261	memset(*cpu_addr, 0, size);
262	return pfn_to_page(__phys_to_pfn(phys));
263}
264
265struct page *dma_alloc_from_pool(struct device *dev, size_t size,
266		void **cpu_addr, gfp_t gfp,
267		bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t))
268{
269	struct gen_pool *pool = NULL;
270	struct page *page;
271
272	while ((pool = dma_guess_pool(pool, gfp))) {
273		page = __dma_alloc_from_pool(dev, size, pool, cpu_addr,
274					     phys_addr_ok);
275		if (page)
276			return page;
277	}
278
279	WARN(1, "Failed to get suitable pool for %s\n", dev_name(dev));
280	return NULL;
281}
282
283bool dma_free_from_pool(struct device *dev, void *start, size_t size)
284{
285	struct gen_pool *pool = NULL;
286
287	while ((pool = dma_guess_pool(pool, 0))) {
288		if (!gen_pool_has_addr(pool, (unsigned long)start, size))
289			continue;
290		gen_pool_free(pool, (unsigned long)start, size);
291		return true;
292	}
293
294	return false;
295}
296