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 55 struct 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) 68 static phys_addr_t size_cmdline __initdata = -1; 69 static phys_addr_t base_cmdline __initdata; 70 static phys_addr_t limit_cmdline __initdata; 71 72 static 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(p, &p); 80 if (*p != '@') 81 return 0; 82 base_cmdline = memparse(p + 1, &p); 83 if (*p != '-') { 84 limit_cmdline = base_cmdline + size_cmdline; 85 return 0; 86 } 87 limit_cmdline = memparse(p + 1, &p); 88 89 return 0; 90 } 91 early_param("cma", early_cma); 92 93 #ifdef CONFIG_DMA_NUMA_CMA 94 95 static struct cma *dma_contiguous_numa_area[MAX_NUMNODES]; 96 static phys_addr_t numa_cma_size[MAX_NUMNODES] __initdata; 97 static struct cma *dma_contiguous_pernuma_area[MAX_NUMNODES]; 98 static phys_addr_t pernuma_size_bytes __initdata; 99 100 static 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(s, &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 } 129 early_param("numa_cma", early_numa_cma); 130 131 static int __init early_cma_pernuma(char *p) 132 { 133 pernuma_size_bytes = memparse(p, &p); 134 return 0; 135 } 136 early_param("cma_pernuma", early_cma_pernuma); 137 #endif 138 139 #ifdef CONFIG_CMA_SIZE_PERCENTAGE 140 141 static 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 149 150 static 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 158 static 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(name, sizeof(name), "pernuma%d", nid); 177 ret = cma_declare_contiguous_nid(0, pernuma_size_bytes, 0, 0, 178 0, false, name, 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(name, sizeof(name), "numa%d", nid); 188 ret = cma_declare_contiguous_nid(0, numa_cma_size[nid], 0, 0, 0, false, 189 name, cma, nid); 190 if (ret) 191 pr_warn("%s: reservation failed: err %d, node %d", __func__, 192 ret, nid); 193 } 194 } 195 } 196 #else 197 static 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 */ 211 void __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(selected_size, selected_base, 245 selected_limit, 246 &dma_contiguous_default_area, 247 fixed); 248 } 249 } 250 251 void __weak 252 dma_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 */ 273 int __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, 0, 0, fixed, 280 "reserved", res_cma); 281 if (ret) 282 return ret; 283 284 /* Architecture specific contiguous memory fixup. */ 285 dma_contiguous_early_fixup(cma_get_base(*res_cma), 286 cma_get_size(*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 */ 303 struct 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(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 */ 322 bool dma_release_from_contiguous(struct device *dev, struct page *pages, 323 int count) 324 { 325 return cma_release(dev_get_cma_area(dev), pages, count); 326 } 327 328 static 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, size >> PAGE_SHIFT, align, 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 */ 350 struct 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)) 358 return NULL; 359 if (dev->cma_area) 360 return cma_alloc_aligned(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(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 */ 400 void 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(dev->cma_area, 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(dma_contiguous_pernuma_area[page_to_nid(page)], 414 page, count)) 415 return; 416 if (cma_release(dma_contiguous_numa_area[page_to_nid(page)], 417 page, count)) 418 return; 419 #endif 420 if (cma_release(dma_contiguous_default_area, page, count)) 421 return; 422 } 423 424 /* not in any cma, free from buddy */ 425 __free_pages(page, 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 438 439 static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev) 440 { 441 dev->cma_area = rmem->priv; 442 return 0; 443 } 444 445 static void rmem_cma_device_release(struct reserved_mem *rmem, 446 struct device *dev) 447 { 448 dev->cma_area = NULL; 449 } 450 451 static const struct reserved_mem_ops rmem_cma_ops = { 452 .device_init = rmem_cma_device_init, 453 .device_release = rmem_cma_device_release, 454 }; 455 456 static 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, "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, "reusable", NULL) || 470 of_get_flat_dt_prop(node, "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(rmem->base, rmem->size, 0, rmem->name, &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(rmem->base, 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 } 497 RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup); 498 #endif 499