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 static struct cma *dma_contiguous_areas[MAX_CMA_AREAS]; 56 static unsigned int dma_contiguous_areas_num; 57 58 static int dma_contiguous_insert_area(struct cma *cma) 59 { 60 if (dma_contiguous_areas_num >= ARRAY_SIZE(dma_contiguous_areas)) 61 return -EINVAL; 62 63 dma_contiguous_areas[dma_contiguous_areas_num++] = cma; 64 65 return 0; 66 } 67 68 /** 69 * dma_contiguous_get_area_by_idx() - Get contiguous area at given index 70 * @idx: index of the area we query 71 * 72 * Queries for the contiguous area located at index @idx. 73 * 74 * Returns: 75 * A pointer to the requested contiguous area, or NULL otherwise. 76 */ 77 struct cma *dma_contiguous_get_area_by_idx(unsigned int idx) 78 { 79 if (idx >= dma_contiguous_areas_num) 80 return NULL; 81 82 return dma_contiguous_areas[idx]; 83 } 84 EXPORT_SYMBOL_GPL(dma_contiguous_get_area_by_idx); 85 86 static struct cma *dma_contiguous_default_area; 87 88 /* 89 * Default global CMA area size can be defined in kernel's .config. 90 * This is useful mainly for distro maintainers to create a kernel 91 * that works correctly for most supported systems. 92 * The size can be set in bytes or as a percentage of the total memory 93 * in the system. 94 * 95 * Users, who want to set the size of global CMA area for their system 96 * should use cma= kernel parameter. 97 */ 98 #define size_bytes ((phys_addr_t)CMA_SIZE_MBYTES * SZ_1M) 99 static phys_addr_t size_cmdline __initdata = -1; 100 static phys_addr_t base_cmdline __initdata; 101 static phys_addr_t limit_cmdline __initdata; 102 103 static int __init early_cma(char *p) 104 { 105 if (!p) { 106 pr_err("Config string not provided\n"); 107 return -EINVAL; 108 } 109 110 size_cmdline = memparse(p, &p); 111 if (*p != '@') 112 return 0; 113 base_cmdline = memparse(p + 1, &p); 114 if (*p != '-') { 115 limit_cmdline = base_cmdline + size_cmdline; 116 return 0; 117 } 118 limit_cmdline = memparse(p + 1, &p); 119 120 return 0; 121 } 122 early_param("cma", early_cma); 123 124 struct cma *dev_get_cma_area(struct device *dev) 125 { 126 if (dev && dev->cma_area) 127 return dev->cma_area; 128 129 return dma_contiguous_default_area; 130 } 131 EXPORT_SYMBOL_GPL(dev_get_cma_area); 132 133 #ifdef CONFIG_DMA_NUMA_CMA 134 135 static struct cma *dma_contiguous_numa_area[MAX_NUMNODES]; 136 static phys_addr_t numa_cma_size[MAX_NUMNODES] __initdata; 137 static struct cma *dma_contiguous_pernuma_area[MAX_NUMNODES]; 138 static phys_addr_t pernuma_size_bytes __initdata; 139 140 static int __init early_numa_cma(char *p) 141 { 142 int nid, count = 0; 143 unsigned long tmp; 144 char *s = p; 145 146 while (*s) { 147 if (sscanf(s, "%lu%n", &tmp, &count) != 1) 148 break; 149 150 if (s[count] == ':') { 151 if (tmp >= MAX_NUMNODES) 152 break; 153 nid = array_index_nospec(tmp, MAX_NUMNODES); 154 155 s += count + 1; 156 tmp = memparse(s, &s); 157 numa_cma_size[nid] = tmp; 158 159 if (*s == ',') 160 s++; 161 else 162 break; 163 } else 164 break; 165 } 166 167 return 0; 168 } 169 early_param("numa_cma", early_numa_cma); 170 171 static int __init early_cma_pernuma(char *p) 172 { 173 pernuma_size_bytes = memparse(p, &p); 174 return 0; 175 } 176 early_param("cma_pernuma", early_cma_pernuma); 177 #endif 178 179 #ifdef CONFIG_CMA_SIZE_PERCENTAGE 180 181 static phys_addr_t __init __maybe_unused cma_early_percent_memory(void) 182 { 183 unsigned long total_pages = PHYS_PFN(memblock_phys_mem_size()); 184 185 return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT; 186 } 187 188 #else 189 190 static inline __maybe_unused phys_addr_t cma_early_percent_memory(void) 191 { 192 return 0; 193 } 194 195 #endif 196 197 #ifdef CONFIG_DMA_NUMA_CMA 198 static void __init dma_numa_cma_reserve(void) 199 { 200 int nid; 201 202 for_each_node(nid) { 203 int ret; 204 char name[CMA_MAX_NAME]; 205 struct cma **cma; 206 207 if (!node_online(nid)) { 208 if (pernuma_size_bytes || numa_cma_size[nid]) 209 pr_warn("invalid node %d specified\n", nid); 210 continue; 211 } 212 213 if (pernuma_size_bytes) { 214 215 cma = &dma_contiguous_pernuma_area[nid]; 216 snprintf(name, sizeof(name), "pernuma%d", nid); 217 ret = cma_declare_contiguous_nid(0, pernuma_size_bytes, 0, 0, 218 0, false, name, cma, nid); 219 if (ret) 220 pr_warn("%s: reservation failed: err %d, node %d", __func__, 221 ret, nid); 222 } 223 224 if (numa_cma_size[nid]) { 225 226 cma = &dma_contiguous_numa_area[nid]; 227 snprintf(name, sizeof(name), "numa%d", nid); 228 ret = cma_declare_contiguous_nid(0, numa_cma_size[nid], 0, 0, 0, false, 229 name, cma, nid); 230 if (ret) 231 pr_warn("%s: reservation failed: err %d, node %d", __func__, 232 ret, nid); 233 } 234 } 235 } 236 #else 237 static inline void __init dma_numa_cma_reserve(void) 238 { 239 } 240 #endif 241 242 /** 243 * dma_contiguous_reserve() - reserve area(s) for contiguous memory handling 244 * @limit: End address of the reserved memory (optional, 0 for any). 245 * 246 * This function reserves memory from early allocator. It should be 247 * called by arch specific code once the early allocator (memblock or bootmem) 248 * has been activated and all other subsystems have already allocated/reserved 249 * memory. 250 */ 251 void __init dma_contiguous_reserve(phys_addr_t limit) 252 { 253 phys_addr_t selected_size = 0; 254 phys_addr_t selected_base = 0; 255 phys_addr_t selected_limit = limit; 256 bool fixed = false; 257 258 dma_numa_cma_reserve(); 259 260 pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit); 261 262 if (size_cmdline != -1) { 263 selected_size = size_cmdline; 264 selected_base = base_cmdline; 265 266 /* Hornor the user setup dma address limit */ 267 selected_limit = limit_cmdline ?: limit; 268 269 if (base_cmdline + size_cmdline == limit_cmdline) 270 fixed = true; 271 } else { 272 #ifdef CONFIG_CMA_SIZE_SEL_MBYTES 273 selected_size = size_bytes; 274 #elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE) 275 selected_size = cma_early_percent_memory(); 276 #elif defined(CONFIG_CMA_SIZE_SEL_MIN) 277 selected_size = min(size_bytes, cma_early_percent_memory()); 278 #elif defined(CONFIG_CMA_SIZE_SEL_MAX) 279 selected_size = max(size_bytes, cma_early_percent_memory()); 280 #endif 281 } 282 283 if (selected_size && !dma_contiguous_default_area) { 284 int ret; 285 286 pr_debug("%s: reserving %ld MiB for global area\n", __func__, 287 (unsigned long)selected_size / SZ_1M); 288 289 ret = dma_contiguous_reserve_area(selected_size, selected_base, 290 selected_limit, 291 &dma_contiguous_default_area, 292 fixed); 293 if (ret) 294 return; 295 296 /* 297 * We need to insert the new area in our list to avoid 298 * any inconsistencies between having the default area 299 * listed in the DT or not. 300 * 301 * The DT case is handled by rmem_cma_setup() and will 302 * always insert all its areas in our list. However, if 303 * it didn't run (because OF_RESERVED_MEM isn't set, or 304 * there's no DT region specified), then we don't have a 305 * default area yet, and no area in our list. 306 * 307 * This block creates the default area in such a case, 308 * but we also need to insert it in our list to avoid 309 * having a default area but an empty list. 310 */ 311 ret = dma_contiguous_insert_area(dma_contiguous_default_area); 312 if (ret) 313 pr_warn("Couldn't queue default CMA region for heap creation."); 314 } 315 } 316 317 void __weak 318 dma_contiguous_early_fixup(phys_addr_t base, unsigned long size) 319 { 320 } 321 322 /** 323 * dma_contiguous_reserve_area() - reserve custom contiguous area 324 * @size: Size of the reserved area (in bytes), 325 * @base: Base address of the reserved area optional, use 0 for any 326 * @limit: End address of the reserved memory (optional, 0 for any). 327 * @res_cma: Pointer to store the created cma region. 328 * @fixed: hint about where to place the reserved area 329 * 330 * This function reserves memory from early allocator. It should be 331 * called by arch specific code once the early allocator (memblock or bootmem) 332 * has been activated and all other subsystems have already allocated/reserved 333 * memory. This function allows to create custom reserved areas for specific 334 * devices. 335 * 336 * If @fixed is true, reserve contiguous area at exactly @base. If false, 337 * reserve in range from @base to @limit. 338 */ 339 int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, 340 phys_addr_t limit, struct cma **res_cma, 341 bool fixed) 342 { 343 int ret; 344 345 ret = cma_declare_contiguous(base, size, limit, 0, 0, fixed, 346 "reserved", res_cma); 347 if (ret) 348 return ret; 349 350 /* Architecture specific contiguous memory fixup. */ 351 dma_contiguous_early_fixup(cma_get_base(*res_cma), 352 cma_get_size(*res_cma)); 353 354 return 0; 355 } 356 357 /** 358 * dma_alloc_from_contiguous() - allocate pages from contiguous area 359 * @dev: Pointer to device for which the allocation is performed. 360 * @count: Requested number of pages. 361 * @align: Requested alignment of pages (in PAGE_SIZE order). 362 * @no_warn: Avoid printing message about failed allocation. 363 * 364 * This function allocates memory buffer for specified device. It uses 365 * device specific contiguous memory area if available or the default 366 * global one. Requires architecture specific dev_get_cma_area() helper 367 * function. 368 */ 369 struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, 370 unsigned int align, bool no_warn) 371 { 372 if (align > CONFIG_CMA_ALIGNMENT) 373 align = CONFIG_CMA_ALIGNMENT; 374 375 return cma_alloc(dev_get_cma_area(dev), count, align, no_warn); 376 } 377 378 /** 379 * dma_release_from_contiguous() - release allocated pages 380 * @dev: Pointer to device for which the pages were allocated. 381 * @pages: Allocated pages. 382 * @count: Number of allocated pages. 383 * 384 * This function releases memory allocated by dma_alloc_from_contiguous(). 385 * It returns false when provided pages do not belong to contiguous area and 386 * true otherwise. 387 */ 388 bool dma_release_from_contiguous(struct device *dev, struct page *pages, 389 int count) 390 { 391 return cma_release(dev_get_cma_area(dev), pages, count); 392 } 393 394 static struct page *cma_alloc_aligned(struct cma *cma, size_t size, gfp_t gfp) 395 { 396 unsigned int align = min(get_order(size), CONFIG_CMA_ALIGNMENT); 397 398 return cma_alloc(cma, size >> PAGE_SHIFT, align, gfp & __GFP_NOWARN); 399 } 400 401 /** 402 * dma_alloc_contiguous() - allocate contiguous pages 403 * @dev: Pointer to device for which the allocation is performed. 404 * @size: Requested allocation size. 405 * @gfp: Allocation flags. 406 * 407 * tries to use device specific contiguous memory area if available, or it 408 * tries to use per-numa cma, if the allocation fails, it will fallback to 409 * try default global one. 410 * 411 * Note that it bypass one-page size of allocations from the per-numa and 412 * global area as the addresses within one page are always contiguous, so 413 * there is no need to waste CMA pages for that kind; it also helps reduce 414 * fragmentations. 415 */ 416 struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) 417 { 418 #ifdef CONFIG_DMA_NUMA_CMA 419 int nid = dev_to_node(dev); 420 #endif 421 422 /* CMA can be used only in the context which permits sleeping */ 423 if (!gfpflags_allow_blocking(gfp)) 424 return NULL; 425 if (dev->cma_area) 426 return cma_alloc_aligned(dev->cma_area, size, gfp); 427 if (size <= PAGE_SIZE) 428 return NULL; 429 430 #ifdef CONFIG_DMA_NUMA_CMA 431 if (nid != NUMA_NO_NODE && !(gfp & (GFP_DMA | GFP_DMA32))) { 432 struct cma *cma = dma_contiguous_pernuma_area[nid]; 433 struct page *page; 434 435 if (cma) { 436 page = cma_alloc_aligned(cma, size, gfp); 437 if (page) 438 return page; 439 } 440 441 cma = dma_contiguous_numa_area[nid]; 442 if (cma) { 443 page = cma_alloc_aligned(cma, size, gfp); 444 if (page) 445 return page; 446 } 447 } 448 #endif 449 if (!dma_contiguous_default_area) 450 return NULL; 451 452 return cma_alloc_aligned(dma_contiguous_default_area, size, gfp); 453 } 454 455 /** 456 * dma_free_contiguous() - release allocated pages 457 * @dev: Pointer to device for which the pages were allocated. 458 * @page: Pointer to the allocated pages. 459 * @size: Size of allocated pages. 460 * 461 * This function releases memory allocated by dma_alloc_contiguous(). As the 462 * cma_release returns false when provided pages do not belong to contiguous 463 * area and true otherwise, this function then does a fallback __free_pages() 464 * upon a false-return. 465 */ 466 void dma_free_contiguous(struct device *dev, struct page *page, size_t size) 467 { 468 unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; 469 470 /* if dev has its own cma, free page from there */ 471 if (dev->cma_area) { 472 if (cma_release(dev->cma_area, page, count)) 473 return; 474 } else { 475 /* 476 * otherwise, page is from either per-numa cma or default cma 477 */ 478 #ifdef CONFIG_DMA_NUMA_CMA 479 if (cma_release(dma_contiguous_pernuma_area[page_to_nid(page)], 480 page, count)) 481 return; 482 if (cma_release(dma_contiguous_numa_area[page_to_nid(page)], 483 page, count)) 484 return; 485 #endif 486 if (cma_release(dma_contiguous_default_area, page, count)) 487 return; 488 } 489 490 /* not in any cma, free from buddy */ 491 __free_pages(page, get_order(size)); 492 } 493 494 /* 495 * Support for reserved memory regions defined in device tree 496 */ 497 #ifdef CONFIG_OF_RESERVED_MEM 498 #include <linux/of.h> 499 #include <linux/of_fdt.h> 500 #include <linux/of_reserved_mem.h> 501 502 #undef pr_fmt 503 #define pr_fmt(fmt) fmt 504 505 static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev) 506 { 507 dev->cma_area = rmem->priv; 508 return 0; 509 } 510 511 static void rmem_cma_device_release(struct reserved_mem *rmem, 512 struct device *dev) 513 { 514 dev->cma_area = NULL; 515 } 516 517 static int __init __rmem_cma_verify_node(unsigned long node) 518 { 519 if (!of_get_flat_dt_prop(node, "reusable", NULL) || 520 of_get_flat_dt_prop(node, "no-map", NULL)) 521 return -ENODEV; 522 523 if (size_cmdline != -1 && 524 of_get_flat_dt_prop(node, "linux,cma-default", NULL)) { 525 pr_err("Skipping dt linux,cma-default node in favor for \"cma=\" kernel param.\n"); 526 return -EBUSY; 527 } 528 return 0; 529 } 530 531 static int __init rmem_cma_validate(unsigned long node, phys_addr_t *align) 532 { 533 int ret = __rmem_cma_verify_node(node); 534 535 if (ret) 536 return ret; 537 538 if (align) 539 *align = max_t(phys_addr_t, *align, CMA_MIN_ALIGNMENT_BYTES); 540 541 return 0; 542 } 543 544 static int __init rmem_cma_fixup(unsigned long node, phys_addr_t base, 545 phys_addr_t size) 546 { 547 int ret = __rmem_cma_verify_node(node); 548 549 if (ret) 550 return ret; 551 552 /* Architecture specific contiguous memory fixup. */ 553 dma_contiguous_early_fixup(base, size); 554 return 0; 555 } 556 557 static int __init rmem_cma_setup(unsigned long node, struct reserved_mem *rmem) 558 { 559 bool default_cma = of_get_flat_dt_prop(node, "linux,cma-default", NULL); 560 struct cma *cma; 561 int ret; 562 563 ret = __rmem_cma_verify_node(node); 564 if (ret) 565 return ret; 566 567 if (!IS_ALIGNED(rmem->base | rmem->size, CMA_MIN_ALIGNMENT_BYTES)) { 568 pr_err("Reserved memory: incorrect alignment of CMA region\n"); 569 return -EINVAL; 570 } 571 572 ret = cma_init_reserved_mem(rmem->base, rmem->size, 0, rmem->name, &cma); 573 if (ret) { 574 pr_err("Reserved memory: unable to setup CMA region\n"); 575 return ret; 576 } 577 578 if (default_cma) 579 dma_contiguous_default_area = cma; 580 581 rmem->priv = cma; 582 583 pr_info("Reserved memory: created CMA memory pool at %pa, size %ld MiB\n", 584 &rmem->base, (unsigned long)rmem->size / SZ_1M); 585 586 ret = dma_contiguous_insert_area(cma); 587 if (ret) 588 pr_warn("Couldn't store CMA reserved area."); 589 590 return 0; 591 } 592 593 static const struct reserved_mem_ops rmem_cma_ops = { 594 .node_validate = rmem_cma_validate, 595 .node_fixup = rmem_cma_fixup, 596 .node_init = rmem_cma_setup, 597 .device_init = rmem_cma_device_init, 598 .device_release = rmem_cma_device_release, 599 }; 600 601 RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", &rmem_cma_ops); 602 #endif 603