1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Contiguous Memory Allocator for DMA mapping framework
4 * Copyright (c) 2010-2011 by Samsung Electronics.
5 * Written by:
6 * Marek Szyprowski <m.szyprowski@samsung.com>
7 * Michal Nazarewicz <mina86@mina86.com>
8 *
9 * Contiguous Memory Allocator
10 *
11 * The Contiguous Memory Allocator (CMA) makes it possible to
12 * allocate big contiguous chunks of memory after the system has
13 * booted.
14 *
15 * Why is it needed?
16 *
17 * Various devices on embedded systems have no scatter-getter and/or
18 * IO map support and require contiguous blocks of memory to
19 * operate. They include devices such as cameras, hardware video
20 * coders, etc.
21 *
22 * Such devices often require big memory buffers (a full HD frame
23 * is, for instance, more than 2 mega pixels large, i.e. more than 6
24 * MB of memory), which makes mechanisms such as kmalloc() or
25 * alloc_page() ineffective.
26 *
27 * At the same time, a solution where a big memory region is
28 * reserved for a device is suboptimal since often more memory is
29 * reserved then strictly required and, moreover, the memory is
30 * inaccessible to page system even if device drivers don't use it.
31 *
32 * CMA tries to solve this issue by operating on memory regions
33 * where only movable pages can be allocated from. This way, kernel
34 * can use the memory for pagecache and when device driver requests
35 * it, allocated pages can be migrated.
36 */
37
38#define pr_fmt(fmt) "cma: " fmt
39
40#include <asm/page.h>
41
42#include <linux/memblock.h>
43#include <linux/err.h>
44#include <linux/sizes.h>
45#include <linux/dma-map-ops.h>
46#include <linux/cma.h>
47#include <linux/nospec.h>
48
49#ifdef CONFIG_CMA_SIZE_MBYTES
50#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
51#else
52#define CMA_SIZE_MBYTES 0
53#endif
54
55struct cma *dma_contiguous_default_area;
56
57/*
58 * Default global CMA area size can be defined in kernel's .config.
59 * This is useful mainly for distro maintainers to create a kernel
60 * that works correctly for most supported systems.
61 * The size can be set in bytes or as a percentage of the total memory
62 * in the system.
63 *
64 * Users, who want to set the size of global CMA area for their system
65 * should use cma= kernel parameter.
66 */
67static const phys_addr_t size_bytes __initconst =
68 (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M;
69static phys_addr_t size_cmdline __initdata = -1;
70static phys_addr_t base_cmdline __initdata;
71static phys_addr_t limit_cmdline __initdata;
72
73static int __init early_cma(char *p)
74{
75 if (!p) {
76 pr_err("Config string not provided\n");
77 return -EINVAL;
78 }
79
80 size_cmdline = memparse(ptr: p, retptr: &p);
81 if (*p != '@')
82 return 0;
83 base_cmdline = memparse(ptr: p + 1, retptr: &p);
84 if (*p != '-') {
85 limit_cmdline = base_cmdline + size_cmdline;
86 return 0;
87 }
88 limit_cmdline = memparse(ptr: p + 1, retptr: &p);
89
90 return 0;
91}
92early_param("cma", early_cma);
93
94#ifdef CONFIG_DMA_NUMA_CMA
95
96static struct cma *dma_contiguous_numa_area[MAX_NUMNODES];
97static phys_addr_t numa_cma_size[MAX_NUMNODES] __initdata;
98static struct cma *dma_contiguous_pernuma_area[MAX_NUMNODES];
99static phys_addr_t pernuma_size_bytes __initdata;
100
101static int __init early_numa_cma(char *p)
102{
103 int nid, count = 0;
104 unsigned long tmp;
105 char *s = p;
106
107 while (*s) {
108 if (sscanf(s, "%lu%n", &tmp, &count) != 1)
109 break;
110
111 if (s[count] == ':') {
112 if (tmp >= MAX_NUMNODES)
113 break;
114 nid = array_index_nospec(tmp, MAX_NUMNODES);
115
116 s += count + 1;
117 tmp = memparse(ptr: s, retptr: &s);
118 numa_cma_size[nid] = tmp;
119
120 if (*s == ',')
121 s++;
122 else
123 break;
124 } else
125 break;
126 }
127
128 return 0;
129}
130early_param("numa_cma", early_numa_cma);
131
132static int __init early_cma_pernuma(char *p)
133{
134 pernuma_size_bytes = memparse(ptr: p, retptr: &p);
135 return 0;
136}
137early_param("cma_pernuma", early_cma_pernuma);
138#endif
139
140#ifdef CONFIG_CMA_SIZE_PERCENTAGE
141
142static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
143{
144 unsigned long total_pages = PHYS_PFN(memblock_phys_mem_size());
145
146 return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
147}
148
149#else
150
151static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
152{
153 return 0;
154}
155
156#endif
157
158#ifdef CONFIG_DMA_NUMA_CMA
159static void __init dma_numa_cma_reserve(void)
160{
161 int nid;
162
163 for_each_node(nid) {
164 int ret;
165 char name[CMA_MAX_NAME];
166 struct cma **cma;
167
168 if (!node_online(nid)) {
169 if (pernuma_size_bytes || numa_cma_size[nid])
170 pr_warn("invalid node %d specified\n", nid);
171 continue;
172 }
173
174 if (pernuma_size_bytes) {
175
176 cma = &dma_contiguous_pernuma_area[nid];
177 snprintf(buf: name, size: sizeof(name), fmt: "pernuma%d", nid);
178 ret = cma_declare_contiguous_nid(base: 0, size: pernuma_size_bytes, limit: 0, alignment: 0,
179 order_per_bit: 0, fixed: false, name, res_cma: cma, nid);
180 if (ret)
181 pr_warn("%s: reservation failed: err %d, node %d", __func__,
182 ret, nid);
183 }
184
185 if (numa_cma_size[nid]) {
186
187 cma = &dma_contiguous_numa_area[nid];
188 snprintf(buf: name, size: sizeof(name), fmt: "numa%d", nid);
189 ret = cma_declare_contiguous_nid(base: 0, size: numa_cma_size[nid], limit: 0, alignment: 0, order_per_bit: 0, fixed: false,
190 name, res_cma: cma, nid);
191 if (ret)
192 pr_warn("%s: reservation failed: err %d, node %d", __func__,
193 ret, nid);
194 }
195 }
196}
197#else
198static inline void __init dma_numa_cma_reserve(void)
199{
200}
201#endif
202
203/**
204 * dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
205 * @limit: End address of the reserved memory (optional, 0 for any).
206 *
207 * This function reserves memory from early allocator. It should be
208 * called by arch specific code once the early allocator (memblock or bootmem)
209 * has been activated and all other subsystems have already allocated/reserved
210 * memory.
211 */
212void __init dma_contiguous_reserve(phys_addr_t limit)
213{
214 phys_addr_t selected_size = 0;
215 phys_addr_t selected_base = 0;
216 phys_addr_t selected_limit = limit;
217 bool fixed = false;
218
219 dma_numa_cma_reserve();
220
221 pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
222
223 if (size_cmdline != -1) {
224 selected_size = size_cmdline;
225 selected_base = base_cmdline;
226 selected_limit = min_not_zero(limit_cmdline, limit);
227 if (base_cmdline + size_cmdline == limit_cmdline)
228 fixed = true;
229 } else {
230#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
231 selected_size = size_bytes;
232#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
233 selected_size = cma_early_percent_memory();
234#elif defined(CONFIG_CMA_SIZE_SEL_MIN)
235 selected_size = min(size_bytes, cma_early_percent_memory());
236#elif defined(CONFIG_CMA_SIZE_SEL_MAX)
237 selected_size = max(size_bytes, cma_early_percent_memory());
238#endif
239 }
240
241 if (selected_size && !dma_contiguous_default_area) {
242 pr_debug("%s: reserving %ld MiB for global area\n", __func__,
243 (unsigned long)selected_size / SZ_1M);
244
245 dma_contiguous_reserve_area(size: selected_size, base: selected_base,
246 limit: selected_limit,
247 res_cma: &dma_contiguous_default_area,
248 fixed);
249 }
250}
251
252void __weak
253dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
254{
255}
256
257/**
258 * dma_contiguous_reserve_area() - reserve custom contiguous area
259 * @size: Size of the reserved area (in bytes),
260 * @base: Base address of the reserved area optional, use 0 for any
261 * @limit: End address of the reserved memory (optional, 0 for any).
262 * @res_cma: Pointer to store the created cma region.
263 * @fixed: hint about where to place the reserved area
264 *
265 * This function reserves memory from early allocator. It should be
266 * called by arch specific code once the early allocator (memblock or bootmem)
267 * has been activated and all other subsystems have already allocated/reserved
268 * memory. This function allows to create custom reserved areas for specific
269 * devices.
270 *
271 * If @fixed is true, reserve contiguous area at exactly @base. If false,
272 * reserve in range from @base to @limit.
273 */
274int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
275 phys_addr_t limit, struct cma **res_cma,
276 bool fixed)
277{
278 int ret;
279
280 ret = cma_declare_contiguous(base, size, limit, alignment: 0, order_per_bit: 0, fixed,
281 name: "reserved", res_cma);
282 if (ret)
283 return ret;
284
285 /* Architecture specific contiguous memory fixup. */
286 dma_contiguous_early_fixup(base: cma_get_base(cma: *res_cma),
287 size: cma_get_size(cma: *res_cma));
288
289 return 0;
290}
291
292/**
293 * dma_alloc_from_contiguous() - allocate pages from contiguous area
294 * @dev: Pointer to device for which the allocation is performed.
295 * @count: Requested number of pages.
296 * @align: Requested alignment of pages (in PAGE_SIZE order).
297 * @no_warn: Avoid printing message about failed allocation.
298 *
299 * This function allocates memory buffer for specified device. It uses
300 * device specific contiguous memory area if available or the default
301 * global one. Requires architecture specific dev_get_cma_area() helper
302 * function.
303 */
304struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
305 unsigned int align, bool no_warn)
306{
307 if (align > CONFIG_CMA_ALIGNMENT)
308 align = CONFIG_CMA_ALIGNMENT;
309
310 return cma_alloc(cma: dev_get_cma_area(dev), count, align, no_warn);
311}
312
313/**
314 * dma_release_from_contiguous() - release allocated pages
315 * @dev: Pointer to device for which the pages were allocated.
316 * @pages: Allocated pages.
317 * @count: Number of allocated pages.
318 *
319 * This function releases memory allocated by dma_alloc_from_contiguous().
320 * It returns false when provided pages do not belong to contiguous area and
321 * true otherwise.
322 */
323bool dma_release_from_contiguous(struct device *dev, struct page *pages,
324 int count)
325{
326 return cma_release(cma: dev_get_cma_area(dev), pages, count);
327}
328
329static struct page *cma_alloc_aligned(struct cma *cma, size_t size, gfp_t gfp)
330{
331 unsigned int align = min(get_order(size), CONFIG_CMA_ALIGNMENT);
332
333 return cma_alloc(cma, count: size >> PAGE_SHIFT, align, no_warn: gfp & __GFP_NOWARN);
334}
335
336/**
337 * dma_alloc_contiguous() - allocate contiguous pages
338 * @dev: Pointer to device for which the allocation is performed.
339 * @size: Requested allocation size.
340 * @gfp: Allocation flags.
341 *
342 * tries to use device specific contiguous memory area if available, or it
343 * tries to use per-numa cma, if the allocation fails, it will fallback to
344 * try default global one.
345 *
346 * Note that it bypass one-page size of allocations from the per-numa and
347 * global area as the addresses within one page are always contiguous, so
348 * there is no need to waste CMA pages for that kind; it also helps reduce
349 * fragmentations.
350 */
351struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
352{
353#ifdef CONFIG_DMA_NUMA_CMA
354 int nid = dev_to_node(dev);
355#endif
356
357 /* CMA can be used only in the context which permits sleeping */
358 if (!gfpflags_allow_blocking(gfp_flags: gfp))
359 return NULL;
360 if (dev->cma_area)
361 return cma_alloc_aligned(cma: dev->cma_area, size, gfp);
362 if (size <= PAGE_SIZE)
363 return NULL;
364
365#ifdef CONFIG_DMA_NUMA_CMA
366 if (nid != NUMA_NO_NODE && !(gfp & (GFP_DMA | GFP_DMA32))) {
367 struct cma *cma = dma_contiguous_pernuma_area[nid];
368 struct page *page;
369
370 if (cma) {
371 page = cma_alloc_aligned(cma, size, gfp);
372 if (page)
373 return page;
374 }
375
376 cma = dma_contiguous_numa_area[nid];
377 if (cma) {
378 page = cma_alloc_aligned(cma, size, gfp);
379 if (page)
380 return page;
381 }
382 }
383#endif
384 if (!dma_contiguous_default_area)
385 return NULL;
386
387 return cma_alloc_aligned(cma: dma_contiguous_default_area, size, gfp);
388}
389
390/**
391 * dma_free_contiguous() - release allocated pages
392 * @dev: Pointer to device for which the pages were allocated.
393 * @page: Pointer to the allocated pages.
394 * @size: Size of allocated pages.
395 *
396 * This function releases memory allocated by dma_alloc_contiguous(). As the
397 * cma_release returns false when provided pages do not belong to contiguous
398 * area and true otherwise, this function then does a fallback __free_pages()
399 * upon a false-return.
400 */
401void dma_free_contiguous(struct device *dev, struct page *page, size_t size)
402{
403 unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
404
405 /* if dev has its own cma, free page from there */
406 if (dev->cma_area) {
407 if (cma_release(cma: dev->cma_area, pages: page, count))
408 return;
409 } else {
410 /*
411 * otherwise, page is from either per-numa cma or default cma
412 */
413#ifdef CONFIG_DMA_NUMA_CMA
414 if (cma_release(cma: dma_contiguous_pernuma_area[page_to_nid(page)],
415 pages: page, count))
416 return;
417 if (cma_release(cma: dma_contiguous_numa_area[page_to_nid(page)],
418 pages: page, count))
419 return;
420#endif
421 if (cma_release(cma: dma_contiguous_default_area, pages: page, count))
422 return;
423 }
424
425 /* not in any cma, free from buddy */
426 __free_pages(page, order: get_order(size));
427}
428
429/*
430 * Support for reserved memory regions defined in device tree
431 */
432#ifdef CONFIG_OF_RESERVED_MEM
433#include <linux/of.h>
434#include <linux/of_fdt.h>
435#include <linux/of_reserved_mem.h>
436
437#undef pr_fmt
438#define pr_fmt(fmt) fmt
439
440static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
441{
442 dev->cma_area = rmem->priv;
443 return 0;
444}
445
446static void rmem_cma_device_release(struct reserved_mem *rmem,
447 struct device *dev)
448{
449 dev->cma_area = NULL;
450}
451
452static const struct reserved_mem_ops rmem_cma_ops = {
453 .device_init = rmem_cma_device_init,
454 .device_release = rmem_cma_device_release,
455};
456
457static int __init rmem_cma_setup(struct reserved_mem *rmem)
458{
459 unsigned long node = rmem->fdt_node;
460 bool default_cma = of_get_flat_dt_prop(node, name: "linux,cma-default", NULL);
461 struct cma *cma;
462 int err;
463
464 if (size_cmdline != -1 && default_cma) {
465 pr_info("Reserved memory: bypass %s node, using cmdline CMA params instead\n",
466 rmem->name);
467 return -EBUSY;
468 }
469
470 if (!of_get_flat_dt_prop(node, name: "reusable", NULL) ||
471 of_get_flat_dt_prop(node, name: "no-map", NULL))
472 return -EINVAL;
473
474 if (!IS_ALIGNED(rmem->base | rmem->size, CMA_MIN_ALIGNMENT_BYTES)) {
475 pr_err("Reserved memory: incorrect alignment of CMA region\n");
476 return -EINVAL;
477 }
478
479 err = cma_init_reserved_mem(base: rmem->base, size: rmem->size, order_per_bit: 0, name: rmem->name, res_cma: &cma);
480 if (err) {
481 pr_err("Reserved memory: unable to setup CMA region\n");
482 return err;
483 }
484 /* Architecture specific contiguous memory fixup. */
485 dma_contiguous_early_fixup(base: rmem->base, size: rmem->size);
486
487 if (default_cma)
488 dma_contiguous_default_area = cma;
489
490 rmem->ops = &rmem_cma_ops;
491 rmem->priv = cma;
492
493 pr_info("Reserved memory: created CMA memory pool at %pa, size %ld MiB\n",
494 &rmem->base, (unsigned long)rmem->size / SZ_1M);
495
496 return 0;
497}
498RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup);
499#endif
500

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source code of linux/kernel/dma/contiguous.c