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 #define CREATE_TRACE_POINTS 27 28 #include <linux/memblock.h> 29 #include <linux/err.h> 30 #include <linux/mm.h> 31 #include <linux/mutex.h> 32 #include <linux/sizes.h> 33 #include <linux/slab.h> 34 #include <linux/log2.h> 35 #include <linux/cma.h> 36 #include <linux/highmem.h> 37 #include <linux/io.h> 38 #include <trace/events/cma.h> 39 40 #include "cma.h" 41 42 struct cma cma_areas[MAX_CMA_AREAS]; 43 unsigned cma_area_count; 44 static DEFINE_MUTEX(cma_mutex); 45 46 phys_addr_t cma_get_base(const struct cma *cma) 47 { 48 return PFN_PHYS(cma->base_pfn); 49 } 50 51 unsigned long cma_get_size(const struct cma *cma) 52 { 53 return cma->count << PAGE_SHIFT; 54 } 55 56 static unsigned long cma_bitmap_aligned_mask(const struct cma *cma, 57 int align_order) 58 { 59 if (align_order <= cma->order_per_bit) 60 return 0; 61 return (1UL << (align_order - cma->order_per_bit)) - 1; 62 } 63 64 /* 65 * Find a PFN aligned to the specified order and return an offset represented in 66 * order_per_bits. 67 */ 68 static unsigned long cma_bitmap_aligned_offset(const struct cma *cma, 69 int align_order) 70 { 71 if (align_order <= cma->order_per_bit) 72 return 0; 73 74 return (ALIGN(cma->base_pfn, (1UL << align_order)) 75 - cma->base_pfn) >> cma->order_per_bit; 76 } 77 78 static unsigned long cma_bitmap_pages_to_bits(const struct cma *cma, 79 unsigned long pages) 80 { 81 return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit; 82 } 83 84 static void cma_clear_bitmap(struct cma *cma, unsigned long pfn, 85 unsigned int count) 86 { 87 unsigned long bitmap_no, bitmap_count; 88 89 bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit; 90 bitmap_count = cma_bitmap_pages_to_bits(cma, count); 91 92 mutex_lock(&cma->lock); 93 bitmap_clear(cma->bitmap, bitmap_no, bitmap_count); 94 mutex_unlock(&cma->lock); 95 } 96 97 static int __init cma_activate_area(struct cma *cma) 98 { 99 int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long); 100 unsigned long base_pfn = cma->base_pfn, pfn = base_pfn; 101 unsigned i = cma->count >> pageblock_order; 102 struct zone *zone; 103 104 cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL); 105 106 if (!cma->bitmap) 107 return -ENOMEM; 108 109 WARN_ON_ONCE(!pfn_valid(pfn)); 110 zone = page_zone(pfn_to_page(pfn)); 111 112 do { 113 unsigned j; 114 115 base_pfn = pfn; 116 for (j = pageblock_nr_pages; j; --j, pfn++) { 117 WARN_ON_ONCE(!pfn_valid(pfn)); 118 /* 119 * alloc_contig_range requires the pfn range 120 * specified to be in the same zone. Make this 121 * simple by forcing the entire CMA resv range 122 * to be in the same zone. 123 */ 124 if (page_zone(pfn_to_page(pfn)) != zone) 125 goto err; 126 } 127 init_cma_reserved_pageblock(pfn_to_page(base_pfn)); 128 } while (--i); 129 130 mutex_init(&cma->lock); 131 132 #ifdef CONFIG_CMA_DEBUGFS 133 INIT_HLIST_HEAD(&cma->mem_head); 134 spin_lock_init(&cma->mem_head_lock); 135 #endif 136 137 return 0; 138 139 err: 140 kfree(cma->bitmap); 141 cma->count = 0; 142 return -EINVAL; 143 } 144 145 static int __init cma_init_reserved_areas(void) 146 { 147 int i; 148 149 for (i = 0; i < cma_area_count; i++) { 150 int ret = cma_activate_area(&cma_areas[i]); 151 152 if (ret) 153 return ret; 154 } 155 156 return 0; 157 } 158 core_initcall(cma_init_reserved_areas); 159 160 /** 161 * cma_init_reserved_mem() - create custom contiguous area from reserved memory 162 * @base: Base address of the reserved area 163 * @size: Size of the reserved area (in bytes), 164 * @order_per_bit: Order of pages represented by one bit on bitmap. 165 * @res_cma: Pointer to store the created cma region. 166 * 167 * This function creates custom contiguous area from already reserved memory. 168 */ 169 int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size, 170 unsigned int order_per_bit, 171 struct cma **res_cma) 172 { 173 struct cma *cma; 174 phys_addr_t alignment; 175 176 /* Sanity checks */ 177 if (cma_area_count == ARRAY_SIZE(cma_areas)) { 178 pr_err("Not enough slots for CMA reserved regions!\n"); 179 return -ENOSPC; 180 } 181 182 if (!size || !memblock_is_region_reserved(base, size)) 183 return -EINVAL; 184 185 /* ensure minimal alignment required by mm core */ 186 alignment = PAGE_SIZE << 187 max_t(unsigned long, MAX_ORDER - 1, pageblock_order); 188 189 /* alignment should be aligned with order_per_bit */ 190 if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit)) 191 return -EINVAL; 192 193 if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size) 194 return -EINVAL; 195 196 /* 197 * Each reserved area must be initialised later, when more kernel 198 * subsystems (like slab allocator) are available. 199 */ 200 cma = &cma_areas[cma_area_count]; 201 cma->base_pfn = PFN_DOWN(base); 202 cma->count = size >> PAGE_SHIFT; 203 cma->order_per_bit = order_per_bit; 204 *res_cma = cma; 205 cma_area_count++; 206 totalcma_pages += (size / PAGE_SIZE); 207 208 return 0; 209 } 210 211 /** 212 * cma_declare_contiguous() - reserve custom contiguous area 213 * @base: Base address of the reserved area optional, use 0 for any 214 * @size: Size of the reserved area (in bytes), 215 * @limit: End address of the reserved memory (optional, 0 for any). 216 * @alignment: Alignment for the CMA area, should be power of 2 or zero 217 * @order_per_bit: Order of pages represented by one bit on bitmap. 218 * @fixed: hint about where to place the reserved area 219 * @res_cma: Pointer to store the created cma region. 220 * 221 * This function reserves memory from early allocator. It should be 222 * called by arch specific code once the early allocator (memblock or bootmem) 223 * has been activated and all other subsystems have already allocated/reserved 224 * memory. This function allows to create custom reserved areas. 225 * 226 * If @fixed is true, reserve contiguous area at exactly @base. If false, 227 * reserve in range from @base to @limit. 228 */ 229 int __init cma_declare_contiguous(phys_addr_t base, 230 phys_addr_t size, phys_addr_t limit, 231 phys_addr_t alignment, unsigned int order_per_bit, 232 bool fixed, struct cma **res_cma) 233 { 234 phys_addr_t memblock_end = memblock_end_of_DRAM(); 235 phys_addr_t highmem_start; 236 int ret = 0; 237 238 #ifdef CONFIG_X86 239 /* 240 * high_memory isn't direct mapped memory so retrieving its physical 241 * address isn't appropriate. But it would be useful to check the 242 * physical address of the highmem boundary so it's justifiable to get 243 * the physical address from it. On x86 there is a validation check for 244 * this case, so the following workaround is needed to avoid it. 245 */ 246 highmem_start = __pa_nodebug(high_memory); 247 #else 248 highmem_start = __pa(high_memory); 249 #endif 250 pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n", 251 __func__, &size, &base, &limit, &alignment); 252 253 if (cma_area_count == ARRAY_SIZE(cma_areas)) { 254 pr_err("Not enough slots for CMA reserved regions!\n"); 255 return -ENOSPC; 256 } 257 258 if (!size) 259 return -EINVAL; 260 261 if (alignment && !is_power_of_2(alignment)) 262 return -EINVAL; 263 264 /* 265 * Sanitise input arguments. 266 * Pages both ends in CMA area could be merged into adjacent unmovable 267 * migratetype page by page allocator's buddy algorithm. In the case, 268 * you couldn't get a contiguous memory, which is not what we want. 269 */ 270 alignment = max(alignment, (phys_addr_t)PAGE_SIZE << 271 max_t(unsigned long, MAX_ORDER - 1, pageblock_order)); 272 base = ALIGN(base, alignment); 273 size = ALIGN(size, alignment); 274 limit &= ~(alignment - 1); 275 276 if (!base) 277 fixed = false; 278 279 /* size should be aligned with order_per_bit */ 280 if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit)) 281 return -EINVAL; 282 283 /* 284 * If allocating at a fixed base the request region must not cross the 285 * low/high memory boundary. 286 */ 287 if (fixed && base < highmem_start && base + size > highmem_start) { 288 ret = -EINVAL; 289 pr_err("Region at %pa defined on low/high memory boundary (%pa)\n", 290 &base, &highmem_start); 291 goto err; 292 } 293 294 /* 295 * If the limit is unspecified or above the memblock end, its effective 296 * value will be the memblock end. Set it explicitly to simplify further 297 * checks. 298 */ 299 if (limit == 0 || limit > memblock_end) 300 limit = memblock_end; 301 302 /* Reserve memory */ 303 if (fixed) { 304 if (memblock_is_region_reserved(base, size) || 305 memblock_reserve(base, size) < 0) { 306 ret = -EBUSY; 307 goto err; 308 } 309 } else { 310 phys_addr_t addr = 0; 311 312 /* 313 * All pages in the reserved area must come from the same zone. 314 * If the requested region crosses the low/high memory boundary, 315 * try allocating from high memory first and fall back to low 316 * memory in case of failure. 317 */ 318 if (base < highmem_start && limit > highmem_start) { 319 addr = memblock_alloc_range(size, alignment, 320 highmem_start, limit, 321 MEMBLOCK_NONE); 322 limit = highmem_start; 323 } 324 325 if (!addr) { 326 addr = memblock_alloc_range(size, alignment, base, 327 limit, 328 MEMBLOCK_NONE); 329 if (!addr) { 330 ret = -ENOMEM; 331 goto err; 332 } 333 } 334 335 /* 336 * kmemleak scans/reads tracked objects for pointers to other 337 * objects but this address isn't mapped and accessible 338 */ 339 kmemleak_ignore(phys_to_virt(addr)); 340 base = addr; 341 } 342 343 ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma); 344 if (ret) 345 goto err; 346 347 pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M, 348 &base); 349 return 0; 350 351 err: 352 pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M); 353 return ret; 354 } 355 356 /** 357 * cma_alloc() - allocate pages from contiguous area 358 * @cma: Contiguous memory region for which the allocation is performed. 359 * @count: Requested number of pages. 360 * @align: Requested alignment of pages (in PAGE_SIZE order). 361 * 362 * This function allocates part of contiguous memory on specific 363 * contiguous memory area. 364 */ 365 struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align) 366 { 367 unsigned long mask, offset; 368 unsigned long pfn = -1; 369 unsigned long start = 0; 370 unsigned long bitmap_maxno, bitmap_no, bitmap_count; 371 struct page *page = NULL; 372 int ret; 373 374 if (!cma || !cma->count) 375 return NULL; 376 377 pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma, 378 count, align); 379 380 if (!count) 381 return NULL; 382 383 mask = cma_bitmap_aligned_mask(cma, align); 384 offset = cma_bitmap_aligned_offset(cma, align); 385 bitmap_maxno = cma_bitmap_maxno(cma); 386 bitmap_count = cma_bitmap_pages_to_bits(cma, count); 387 388 for (;;) { 389 mutex_lock(&cma->lock); 390 bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap, 391 bitmap_maxno, start, bitmap_count, mask, 392 offset); 393 if (bitmap_no >= bitmap_maxno) { 394 mutex_unlock(&cma->lock); 395 break; 396 } 397 bitmap_set(cma->bitmap, bitmap_no, bitmap_count); 398 /* 399 * It's safe to drop the lock here. We've marked this region for 400 * our exclusive use. If the migration fails we will take the 401 * lock again and unmark it. 402 */ 403 mutex_unlock(&cma->lock); 404 405 pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit); 406 mutex_lock(&cma_mutex); 407 ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA); 408 mutex_unlock(&cma_mutex); 409 if (ret == 0) { 410 page = pfn_to_page(pfn); 411 break; 412 } 413 414 cma_clear_bitmap(cma, pfn, count); 415 if (ret != -EBUSY) 416 break; 417 418 pr_debug("%s(): memory range at %p is busy, retrying\n", 419 __func__, pfn_to_page(pfn)); 420 /* try again with a bit different memory target */ 421 start = bitmap_no + mask + 1; 422 } 423 424 trace_cma_alloc(pfn, page, count, align); 425 426 pr_debug("%s(): returned %p\n", __func__, page); 427 return page; 428 } 429 430 /** 431 * cma_release() - release allocated pages 432 * @cma: Contiguous memory region for which the allocation is performed. 433 * @pages: Allocated pages. 434 * @count: Number of allocated pages. 435 * 436 * This function releases memory allocated by alloc_cma(). 437 * It returns false when provided pages do not belong to contiguous area and 438 * true otherwise. 439 */ 440 bool cma_release(struct cma *cma, const struct page *pages, unsigned int count) 441 { 442 unsigned long pfn; 443 444 if (!cma || !pages) 445 return false; 446 447 pr_debug("%s(page %p)\n", __func__, (void *)pages); 448 449 pfn = page_to_pfn(pages); 450 451 if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) 452 return false; 453 454 VM_BUG_ON(pfn + count > cma->base_pfn + cma->count); 455 456 free_contig_range(pfn, count); 457 cma_clear_bitmap(cma, pfn, count); 458 trace_cma_release(pfn, pages, count); 459 460 return true; 461 } 462