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         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 }