1 /* 2 * Contiguous Memory Allocator 3 * 4 * Copyright (c) 2010-2011 by Samsung Electronics. 5 * Copyright IBM Corporation, 2013 6 * Copyright LG Electronics Inc., 2014 7 * Written by: 8 * Marek Szyprowski <m.szyprowski@samsung.com> 9 * Michal Nazarewicz <mina86@mina86.com> 10 * Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> 11 * Joonsoo Kim <iamjoonsoo.kim@lge.com> 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License as 15 * published by the Free Software Foundation; either version 2 of the 16 * License or (at your optional) any later version of the license. 17 */ 18 19 #define pr_fmt(fmt) "cma: " fmt 20 21 #ifdef CONFIG_CMA_DEBUG 22 #ifndef DEBUG 23 # define DEBUG 24 #endif 25 #endif 26 27 #include <linux/memblock.h> 28 #include <linux/err.h> 29 #include <linux/mm.h> 30 #include <linux/mutex.h> 31 #include <linux/sizes.h> 32 #include <linux/slab.h> 33 #include <linux/log2.h> 34 #include <linux/cma.h> 35 #include <linux/highmem.h> 36 37 struct cma { 38 unsigned long base_pfn; 39 unsigned long count; 40 unsigned long *bitmap; 41 unsigned int order_per_bit; /* Order of pages represented by one bit */ 42 struct mutex lock; 43 }; 44 45 static struct cma cma_areas[MAX_CMA_AREAS]; 46 static unsigned cma_area_count; 47 static DEFINE_MUTEX(cma_mutex); 48 49 phys_addr_t cma_get_base(struct cma *cma) 50 { 51 return PFN_PHYS(cma->base_pfn); 52 } 53 54 unsigned long cma_get_size(struct cma *cma) 55 { 56 return cma->count << PAGE_SHIFT; 57 } 58 59 static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order) 60 { 61 if (align_order <= cma->order_per_bit) 62 return 0; 63 return (1UL << (align_order - cma->order_per_bit)) - 1; 64 } 65 66 static unsigned long cma_bitmap_maxno(struct cma *cma) 67 { 68 return cma->count >> cma->order_per_bit; 69 } 70 71 static unsigned long cma_bitmap_pages_to_bits(struct cma *cma, 72 unsigned long pages) 73 { 74 return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit; 75 } 76 77 static void cma_clear_bitmap(struct cma *cma, unsigned long pfn, int count) 78 { 79 unsigned long bitmap_no, bitmap_count; 80 81 bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit; 82 bitmap_count = cma_bitmap_pages_to_bits(cma, count); 83 84 mutex_lock(&cma->lock); 85 bitmap_clear(cma->bitmap, bitmap_no, bitmap_count); 86 mutex_unlock(&cma->lock); 87 } 88 89 static int __init cma_activate_area(struct cma *cma) 90 { 91 int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long); 92 unsigned long base_pfn = cma->base_pfn, pfn = base_pfn; 93 unsigned i = cma->count >> pageblock_order; 94 struct zone *zone; 95 96 cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL); 97 98 if (!cma->bitmap) 99 return -ENOMEM; 100 101 WARN_ON_ONCE(!pfn_valid(pfn)); 102 zone = page_zone(pfn_to_page(pfn)); 103 104 do { 105 unsigned j; 106 107 base_pfn = pfn; 108 for (j = pageblock_nr_pages; j; --j, pfn++) { 109 WARN_ON_ONCE(!pfn_valid(pfn)); 110 /* 111 * alloc_contig_range requires the pfn range 112 * specified to be in the same zone. Make this 113 * simple by forcing the entire CMA resv range 114 * to be in the same zone. 115 */ 116 if (page_zone(pfn_to_page(pfn)) != zone) 117 goto err; 118 } 119 init_cma_reserved_pageblock(pfn_to_page(base_pfn)); 120 } while (--i); 121 122 mutex_init(&cma->lock); 123 return 0; 124 125 err: 126 kfree(cma->bitmap); 127 cma->count = 0; 128 return -EINVAL; 129 } 130 131 static int __init cma_init_reserved_areas(void) 132 { 133 int i; 134 135 for (i = 0; i < cma_area_count; i++) { 136 int ret = cma_activate_area(&cma_areas[i]); 137 138 if (ret) 139 return ret; 140 } 141 142 return 0; 143 } 144 core_initcall(cma_init_reserved_areas); 145 146 /** 147 * cma_init_reserved_mem() - create custom contiguous area from reserved memory 148 * @base: Base address of the reserved area 149 * @size: Size of the reserved area (in bytes), 150 * @order_per_bit: Order of pages represented by one bit on bitmap. 151 * @res_cma: Pointer to store the created cma region. 152 * 153 * This function creates custom contiguous area from already reserved memory. 154 */ 155 int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size, 156 int order_per_bit, struct cma **res_cma) 157 { 158 struct cma *cma; 159 phys_addr_t alignment; 160 161 /* Sanity checks */ 162 if (cma_area_count == ARRAY_SIZE(cma_areas)) { 163 pr_err("Not enough slots for CMA reserved regions!\n"); 164 return -ENOSPC; 165 } 166 167 if (!size || !memblock_is_region_reserved(base, size)) 168 return -EINVAL; 169 170 /* ensure minimal alignment requied by mm core */ 171 alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order); 172 173 /* alignment should be aligned with order_per_bit */ 174 if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit)) 175 return -EINVAL; 176 177 if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size) 178 return -EINVAL; 179 180 /* 181 * Each reserved area must be initialised later, when more kernel 182 * subsystems (like slab allocator) are available. 183 */ 184 cma = &cma_areas[cma_area_count]; 185 cma->base_pfn = PFN_DOWN(base); 186 cma->count = size >> PAGE_SHIFT; 187 cma->order_per_bit = order_per_bit; 188 *res_cma = cma; 189 cma_area_count++; 190 191 return 0; 192 } 193 194 /** 195 * cma_declare_contiguous() - reserve custom contiguous area 196 * @base: Base address of the reserved area optional, use 0 for any 197 * @size: Size of the reserved area (in bytes), 198 * @limit: End address of the reserved memory (optional, 0 for any). 199 * @alignment: Alignment for the CMA area, should be power of 2 or zero 200 * @order_per_bit: Order of pages represented by one bit on bitmap. 201 * @fixed: hint about where to place the reserved area 202 * @res_cma: Pointer to store the created cma region. 203 * 204 * This function reserves memory from early allocator. It should be 205 * called by arch specific code once the early allocator (memblock or bootmem) 206 * has been activated and all other subsystems have already allocated/reserved 207 * memory. This function allows to create custom reserved areas. 208 * 209 * If @fixed is true, reserve contiguous area at exactly @base. If false, 210 * reserve in range from @base to @limit. 211 */ 212 int __init cma_declare_contiguous(phys_addr_t base, 213 phys_addr_t size, phys_addr_t limit, 214 phys_addr_t alignment, unsigned int order_per_bit, 215 bool fixed, struct cma **res_cma) 216 { 217 phys_addr_t memblock_end = memblock_end_of_DRAM(); 218 phys_addr_t highmem_start = __pa(high_memory); 219 int ret = 0; 220 221 pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n", 222 __func__, &size, &base, &limit, &alignment); 223 224 if (cma_area_count == ARRAY_SIZE(cma_areas)) { 225 pr_err("Not enough slots for CMA reserved regions!\n"); 226 return -ENOSPC; 227 } 228 229 if (!size) 230 return -EINVAL; 231 232 if (alignment && !is_power_of_2(alignment)) 233 return -EINVAL; 234 235 /* 236 * Sanitise input arguments. 237 * Pages both ends in CMA area could be merged into adjacent unmovable 238 * migratetype page by page allocator's buddy algorithm. In the case, 239 * you couldn't get a contiguous memory, which is not what we want. 240 */ 241 alignment = max(alignment, 242 (phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order)); 243 base = ALIGN(base, alignment); 244 size = ALIGN(size, alignment); 245 limit &= ~(alignment - 1); 246 247 if (!base) 248 fixed = false; 249 250 /* size should be aligned with order_per_bit */ 251 if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit)) 252 return -EINVAL; 253 254 /* 255 * If allocating at a fixed base the request region must not cross the 256 * low/high memory boundary. 257 */ 258 if (fixed && base < highmem_start && base + size > highmem_start) { 259 ret = -EINVAL; 260 pr_err("Region at %pa defined on low/high memory boundary (%pa)\n", 261 &base, &highmem_start); 262 goto err; 263 } 264 265 /* 266 * If the limit is unspecified or above the memblock end, its effective 267 * value will be the memblock end. Set it explicitly to simplify further 268 * checks. 269 */ 270 if (limit == 0 || limit > memblock_end) 271 limit = memblock_end; 272 273 /* Reserve memory */ 274 if (fixed) { 275 if (memblock_is_region_reserved(base, size) || 276 memblock_reserve(base, size) < 0) { 277 ret = -EBUSY; 278 goto err; 279 } 280 } else { 281 phys_addr_t addr = 0; 282 283 /* 284 * All pages in the reserved area must come from the same zone. 285 * If the requested region crosses the low/high memory boundary, 286 * try allocating from high memory first and fall back to low 287 * memory in case of failure. 288 */ 289 if (base < highmem_start && limit > highmem_start) { 290 addr = memblock_alloc_range(size, alignment, 291 highmem_start, limit); 292 limit = highmem_start; 293 } 294 295 if (!addr) { 296 addr = memblock_alloc_range(size, alignment, base, 297 limit); 298 if (!addr) { 299 ret = -ENOMEM; 300 goto err; 301 } 302 } 303 304 base = addr; 305 } 306 307 ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma); 308 if (ret) 309 goto err; 310 311 pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M, 312 &base); 313 return 0; 314 315 err: 316 pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M); 317 return ret; 318 } 319 320 /** 321 * cma_alloc() - allocate pages from contiguous area 322 * @cma: Contiguous memory region for which the allocation is performed. 323 * @count: Requested number of pages. 324 * @align: Requested alignment of pages (in PAGE_SIZE order). 325 * 326 * This function allocates part of contiguous memory on specific 327 * contiguous memory area. 328 */ 329 struct page *cma_alloc(struct cma *cma, int count, unsigned int align) 330 { 331 unsigned long mask, pfn, start = 0; 332 unsigned long bitmap_maxno, bitmap_no, bitmap_count; 333 struct page *page = NULL; 334 int ret; 335 336 if (!cma || !cma->count) 337 return NULL; 338 339 pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma, 340 count, align); 341 342 if (!count) 343 return NULL; 344 345 mask = cma_bitmap_aligned_mask(cma, align); 346 bitmap_maxno = cma_bitmap_maxno(cma); 347 bitmap_count = cma_bitmap_pages_to_bits(cma, count); 348 349 for (;;) { 350 mutex_lock(&cma->lock); 351 bitmap_no = bitmap_find_next_zero_area(cma->bitmap, 352 bitmap_maxno, start, bitmap_count, mask); 353 if (bitmap_no >= bitmap_maxno) { 354 mutex_unlock(&cma->lock); 355 break; 356 } 357 bitmap_set(cma->bitmap, bitmap_no, bitmap_count); 358 /* 359 * It's safe to drop the lock here. We've marked this region for 360 * our exclusive use. If the migration fails we will take the 361 * lock again and unmark it. 362 */ 363 mutex_unlock(&cma->lock); 364 365 pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit); 366 mutex_lock(&cma_mutex); 367 ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA); 368 mutex_unlock(&cma_mutex); 369 if (ret == 0) { 370 page = pfn_to_page(pfn); 371 break; 372 } 373 374 cma_clear_bitmap(cma, pfn, count); 375 if (ret != -EBUSY) 376 break; 377 378 pr_debug("%s(): memory range at %p is busy, retrying\n", 379 __func__, pfn_to_page(pfn)); 380 /* try again with a bit different memory target */ 381 start = bitmap_no + mask + 1; 382 } 383 384 pr_debug("%s(): returned %p\n", __func__, page); 385 return page; 386 } 387 388 /** 389 * cma_release() - release allocated pages 390 * @cma: Contiguous memory region for which the allocation is performed. 391 * @pages: Allocated pages. 392 * @count: Number of allocated pages. 393 * 394 * This function releases memory allocated by alloc_cma(). 395 * It returns false when provided pages do not belong to contiguous area and 396 * true otherwise. 397 */ 398 bool cma_release(struct cma *cma, struct page *pages, int count) 399 { 400 unsigned long pfn; 401 402 if (!cma || !pages) 403 return false; 404 405 pr_debug("%s(page %p)\n", __func__, (void *)pages); 406 407 pfn = page_to_pfn(pages); 408 409 if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) 410 return false; 411 412 VM_BUG_ON(pfn + count > cma->base_pfn + cma->count); 413 414 free_contig_range(pfn, count); 415 cma_clear_bitmap(cma, pfn, count); 416 417 return true; 418 } 419