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

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