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 return -EINVAL; 128 } 129 130 static int __init cma_init_reserved_areas(void) 131 { 132 int i; 133 134 for (i = 0; i < cma_area_count; i++) { 135 int ret = cma_activate_area(&cma_areas[i]); 136 137 if (ret) 138 return ret; 139 } 140 141 return 0; 142 } 143 core_initcall(cma_init_reserved_areas); 144 145 /** 146 * cma_init_reserved_mem() - create custom contiguous area from reserved memory 147 * @base: Base address of the reserved area 148 * @size: Size of the reserved area (in bytes), 149 * @order_per_bit: Order of pages represented by one bit on bitmap. 150 * @res_cma: Pointer to store the created cma region. 151 * 152 * This function creates custom contiguous area from already reserved memory. 153 */ 154 int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size, 155 int order_per_bit, struct cma **res_cma) 156 { 157 struct cma *cma; 158 phys_addr_t alignment; 159 160 /* Sanity checks */ 161 if (cma_area_count == ARRAY_SIZE(cma_areas)) { 162 pr_err("Not enough slots for CMA reserved regions!\n"); 163 return -ENOSPC; 164 } 165 166 if (!size || !memblock_is_region_reserved(base, size)) 167 return -EINVAL; 168 169 /* ensure minimal alignment requied by mm core */ 170 alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order); 171 172 /* alignment should be aligned with order_per_bit */ 173 if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit)) 174 return -EINVAL; 175 176 if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size) 177 return -EINVAL; 178 179 /* 180 * Each reserved area must be initialised later, when more kernel 181 * subsystems (like slab allocator) are available. 182 */ 183 cma = &cma_areas[cma_area_count]; 184 cma->base_pfn = PFN_DOWN(base); 185 cma->count = size >> PAGE_SHIFT; 186 cma->order_per_bit = order_per_bit; 187 *res_cma = cma; 188 cma_area_count++; 189 190 return 0; 191 } 192 193 /** 194 * cma_declare_contiguous() - reserve custom contiguous area 195 * @base: Base address of the reserved area optional, use 0 for any 196 * @size: Size of the reserved area (in bytes), 197 * @limit: End address of the reserved memory (optional, 0 for any). 198 * @alignment: Alignment for the CMA area, should be power of 2 or zero 199 * @order_per_bit: Order of pages represented by one bit on bitmap. 200 * @fixed: hint about where to place the reserved area 201 * @res_cma: Pointer to store the created cma region. 202 * 203 * This function reserves memory from early allocator. It should be 204 * called by arch specific code once the early allocator (memblock or bootmem) 205 * has been activated and all other subsystems have already allocated/reserved 206 * memory. This function allows to create custom reserved areas. 207 * 208 * If @fixed is true, reserve contiguous area at exactly @base. If false, 209 * reserve in range from @base to @limit. 210 */ 211 int __init cma_declare_contiguous(phys_addr_t base, 212 phys_addr_t size, phys_addr_t limit, 213 phys_addr_t alignment, unsigned int order_per_bit, 214 bool fixed, struct cma **res_cma) 215 { 216 phys_addr_t memblock_end = memblock_end_of_DRAM(); 217 phys_addr_t highmem_start = __pa(high_memory); 218 int ret = 0; 219 220 pr_debug("%s(size %lx, base %08lx, limit %08lx alignment %08lx)\n", 221 __func__, (unsigned long)size, (unsigned long)base, 222 (unsigned long)limit, (unsigned long)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 /* size should be aligned with order_per_bit */ 248 if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit)) 249 return -EINVAL; 250 251 /* 252 * adjust limit to avoid crossing low/high memory boundary for 253 * automatically allocated regions 254 */ 255 if (((limit == 0 || limit > memblock_end) && 256 (memblock_end - size < highmem_start && 257 memblock_end > highmem_start)) || 258 (!fixed && limit > highmem_start && limit - size < highmem_start)) { 259 limit = highmem_start; 260 } 261 262 if (fixed && base < highmem_start && base+size > highmem_start) { 263 ret = -EINVAL; 264 pr_err("Region at %08lx defined on low/high memory boundary (%08lx)\n", 265 (unsigned long)base, (unsigned long)highmem_start); 266 goto err; 267 } 268 269 /* Reserve memory */ 270 if (base && fixed) { 271 if (memblock_is_region_reserved(base, size) || 272 memblock_reserve(base, size) < 0) { 273 ret = -EBUSY; 274 goto err; 275 } 276 } else { 277 phys_addr_t addr = memblock_alloc_range(size, alignment, base, 278 limit); 279 if (!addr) { 280 ret = -ENOMEM; 281 goto err; 282 } else { 283 base = addr; 284 } 285 } 286 287 ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma); 288 if (ret) 289 goto err; 290 291 pr_info("Reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M, 292 (unsigned long)base); 293 return 0; 294 295 err: 296 pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M); 297 return ret; 298 } 299 300 /** 301 * cma_alloc() - allocate pages from contiguous area 302 * @cma: Contiguous memory region for which the allocation is performed. 303 * @count: Requested number of pages. 304 * @align: Requested alignment of pages (in PAGE_SIZE order). 305 * 306 * This function allocates part of contiguous memory on specific 307 * contiguous memory area. 308 */ 309 struct page *cma_alloc(struct cma *cma, int count, unsigned int align) 310 { 311 unsigned long mask, pfn, start = 0; 312 unsigned long bitmap_maxno, bitmap_no, bitmap_count; 313 struct page *page = NULL; 314 int ret; 315 316 if (!cma || !cma->count) 317 return NULL; 318 319 pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma, 320 count, align); 321 322 if (!count) 323 return NULL; 324 325 mask = cma_bitmap_aligned_mask(cma, align); 326 bitmap_maxno = cma_bitmap_maxno(cma); 327 bitmap_count = cma_bitmap_pages_to_bits(cma, count); 328 329 for (;;) { 330 mutex_lock(&cma->lock); 331 bitmap_no = bitmap_find_next_zero_area(cma->bitmap, 332 bitmap_maxno, start, bitmap_count, mask); 333 if (bitmap_no >= bitmap_maxno) { 334 mutex_unlock(&cma->lock); 335 break; 336 } 337 bitmap_set(cma->bitmap, bitmap_no, bitmap_count); 338 /* 339 * It's safe to drop the lock here. We've marked this region for 340 * our exclusive use. If the migration fails we will take the 341 * lock again and unmark it. 342 */ 343 mutex_unlock(&cma->lock); 344 345 pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit); 346 mutex_lock(&cma_mutex); 347 ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA); 348 mutex_unlock(&cma_mutex); 349 if (ret == 0) { 350 page = pfn_to_page(pfn); 351 break; 352 } 353 354 cma_clear_bitmap(cma, pfn, count); 355 if (ret != -EBUSY) 356 break; 357 358 pr_debug("%s(): memory range at %p is busy, retrying\n", 359 __func__, pfn_to_page(pfn)); 360 /* try again with a bit different memory target */ 361 start = bitmap_no + mask + 1; 362 } 363 364 pr_debug("%s(): returned %p\n", __func__, page); 365 return page; 366 } 367 368 /** 369 * cma_release() - release allocated pages 370 * @cma: Contiguous memory region for which the allocation is performed. 371 * @pages: Allocated pages. 372 * @count: Number of allocated pages. 373 * 374 * This function releases memory allocated by alloc_cma(). 375 * It returns false when provided pages do not belong to contiguous area and 376 * true otherwise. 377 */ 378 bool cma_release(struct cma *cma, struct page *pages, int count) 379 { 380 unsigned long pfn; 381 382 if (!cma || !pages) 383 return false; 384 385 pr_debug("%s(page %p)\n", __func__, (void *)pages); 386 387 pfn = page_to_pfn(pages); 388 389 if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) 390 return false; 391 392 VM_BUG_ON(pfn + count > cma->base_pfn + cma->count); 393 394 free_contig_range(pfn, count); 395 cma_clear_bitmap(cma, pfn, count); 396 397 return true; 398 } 399