mm/cma.c

   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 }