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
  36 struct cma {
  37         unsigned long   base_pfn;
  38         unsigned long   count;
  39         unsigned long   *bitmap;
  40         unsigned int order_per_bit; /* Order of pages represented by one bit */
  41         struct mutex    lock;
  42 };
  43
  44 static struct cma cma_areas[MAX_CMA_AREAS];
  45 static unsigned cma_area_count;
  46 static DEFINE_MUTEX(cma_mutex);
  47
  48 phys_addr_t cma_get_base(struct cma *cma)
  49 {
  50         return PFN_PHYS(cma->base_pfn);
  51 }
  52
  53 unsigned long cma_get_size(struct cma *cma)
  54 {
  55         return cma->count << PAGE_SHIFT;
  56 }
  57
  58 static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order)
  59 {
  60         return (1UL << (align_order >> cma->order_per_bit)) - 1;
  61 }
  62
  63 static unsigned long cma_bitmap_maxno(struct cma *cma)
  64 {
  65         return cma->count >> cma->order_per_bit;
  66 }
  67
  68 static unsigned long cma_bitmap_pages_to_bits(struct cma *cma,
  69                                                 unsigned long pages)
  70 {
  71         return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
  72 }
  73
  74 static void cma_clear_bitmap(struct cma *cma, unsigned long pfn, int count)
  75 {
  76         unsigned long bitmap_no, bitmap_count;
  77
  78         bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
  79         bitmap_count = cma_bitmap_pages_to_bits(cma, count);
  80
  81         mutex_lock(&cma->lock);
  82         bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
  83         mutex_unlock(&cma->lock);
  84 }
  85
  86 static int __init cma_activate_area(struct cma *cma)
  87 {
  88         int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
  89         unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
  90         unsigned i = cma->count >> pageblock_order;
  91         struct zone *zone;
  92
  93         cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
  94
  95         if (!cma->bitmap)
  96                 return -ENOMEM;
  97
  98         WARN_ON_ONCE(!pfn_valid(pfn));
  99         zone = page_zone(pfn_to_page(pfn));
 100
 101         do {
 102                 unsigned j;
 103
 104                 base_pfn = pfn;
 105                 for (j = pageblock_nr_pages; j; --j, pfn++) {
 106                         WARN_ON_ONCE(!pfn_valid(pfn));
 107                         /*
 108                          * alloc_contig_range requires the pfn range
 109                          * specified to be in the same zone. Make this
 110                          * simple by forcing the entire CMA resv range
 111                          * to be in the same zone.
 112                          */
 113                         if (page_zone(pfn_to_page(pfn)) != zone)
 114                                 goto err;
 115                 }
 116                 init_cma_reserved_pageblock(pfn_to_page(base_pfn));
 117         } while (--i);
 118
 119         mutex_init(&cma->lock);
 120         return 0;
 121
 122 err:
 123         kfree(cma->bitmap);
 124         return -EINVAL;
 125 }
 126
 127 static int __init cma_init_reserved_areas(void)
 128 {
 129         int i;
 130
 131         for (i = 0; i < cma_area_count; i++) {
 132                 int ret = cma_activate_area(&cma_areas[i]);
 133
 134                 if (ret)
 135                         return ret;
 136         }
 137
 138         return 0;
 139 }
 140 core_initcall(cma_init_reserved_areas);
 141
 142 /**
 143  * cma_declare_contiguous() - reserve custom contiguous area
 144  * @base: Base address of the reserved area optional, use 0 for any
 145  * @size: Size of the reserved area (in bytes),
 146  * @limit: End address of the reserved memory (optional, 0 for any).
 147  * @alignment: Alignment for the CMA area, should be power of 2 or zero
 148  * @order_per_bit: Order of pages represented by one bit on bitmap.
 149  * @fixed: hint about where to place the reserved area
 150  * @res_cma: Pointer to store the created cma region.
 151  *
 152  * This function reserves memory from early allocator. It should be
 153  * called by arch specific code once the early allocator (memblock or bootmem)
 154  * has been activated and all other subsystems have already allocated/reserved
 155  * memory. This function allows to create custom reserved areas.
 156  *
 157  * If @fixed is true, reserve contiguous area at exactly @base.  If false,
 158  * reserve in range from @base to @limit.
 159  */
 160 int __init cma_declare_contiguous(phys_addr_t base,
 161                         phys_addr_t size, phys_addr_t limit,
 162                         phys_addr_t alignment, unsigned int order_per_bit,
 163                         bool fixed, struct cma **res_cma)
 164 {
 165         struct cma *cma;
 166         int ret = 0;
 167
 168         pr_debug("%s(size %lx, base %08lx, limit %08lx alignment %08lx)\n",
 169                 __func__, (unsigned long)size, (unsigned long)base,
 170                 (unsigned long)limit, (unsigned long)alignment);
 171
 172         if (cma_area_count == ARRAY_SIZE(cma_areas)) {
 173                 pr_err("Not enough slots for CMA reserved regions!\n");
 174                 return -ENOSPC;
 175         }
 176
 177         if (!size)
 178                 return -EINVAL;
 179
 180         if (alignment && !is_power_of_2(alignment))
 181                 return -EINVAL;
 182
 183         /*
 184          * Sanitise input arguments.
 185          * Pages both ends in CMA area could be merged into adjacent unmovable
 186          * migratetype page by page allocator's buddy algorithm. In the case,
 187          * you couldn't get a contiguous memory, which is not what we want.
 188          */
 189         alignment = max(alignment,
 190                 (phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order));
 191         base = ALIGN(base, alignment);
 192         size = ALIGN(size, alignment);
 193         limit &= ~(alignment - 1);
 194
 195         /* size should be aligned with order_per_bit */
 196         if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
 197                 return -EINVAL;
 198
 199         /* Reserve memory */
 200         if (base && fixed) {
 201                 if (memblock_is_region_reserved(base, size) ||
 202                     memblock_reserve(base, size) < 0) {
 203                         ret = -EBUSY;
 204                         goto err;
 205                 }
 206         } else {
 207                 phys_addr_t addr = memblock_alloc_range(size, alignment, base,
 208                                                         limit);
 209                 if (!addr) {
 210                         ret = -ENOMEM;
 211                         goto err;
 212                 } else {
 213                         base = addr;
 214                 }
 215         }
 216
 217         /*
 218          * Each reserved area must be initialised later, when more kernel
 219          * subsystems (like slab allocator) are available.
 220          */
 221         cma = &cma_areas[cma_area_count];
 222         cma->base_pfn = PFN_DOWN(base);
 223         cma->count = size >> PAGE_SHIFT;
 224         cma->order_per_bit = order_per_bit;
 225         *res_cma = cma;
 226         cma_area_count++;
 227
 228         pr_info("Reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
 229                 (unsigned long)base);
 230         return 0;
 231
 232 err:
 233         pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
 234         return ret;
 235 }
 236
 237 /**
 238  * cma_alloc() - allocate pages from contiguous area
 239  * @cma:   Contiguous memory region for which the allocation is performed.
 240  * @count: Requested number of pages.
 241  * @align: Requested alignment of pages (in PAGE_SIZE order).
 242  *
 243  * This function allocates part of contiguous memory on specific
 244  * contiguous memory area.
 245  */
 246 struct page *cma_alloc(struct cma *cma, int count, unsigned int align)
 247 {
 248         unsigned long mask, pfn, start = 0;
 249         unsigned long bitmap_maxno, bitmap_no, bitmap_count;
 250         struct page *page = NULL;
 251         int ret;
 252
 253         if (!cma || !cma->count)
 254                 return NULL;
 255
 256         pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
 257                  count, align);
 258
 259         if (!count)
 260                 return NULL;
 261
 262         mask = cma_bitmap_aligned_mask(cma, align);
 263         bitmap_maxno = cma_bitmap_maxno(cma);
 264         bitmap_count = cma_bitmap_pages_to_bits(cma, count);
 265
 266         for (;;) {
 267                 mutex_lock(&cma->lock);
 268                 bitmap_no = bitmap_find_next_zero_area(cma->bitmap,
 269                                 bitmap_maxno, start, bitmap_count, mask);
 270                 if (bitmap_no >= bitmap_maxno) {
 271                         mutex_unlock(&cma->lock);
 272                         break;
 273                 }
 274                 bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
 275                 /*
 276                  * It's safe to drop the lock here. We've marked this region for
 277                  * our exclusive use. If the migration fails we will take the
 278                  * lock again and unmark it.
 279                  */
 280                 mutex_unlock(&cma->lock);
 281
 282                 pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
 283                 mutex_lock(&cma_mutex);
 284                 ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
 285                 mutex_unlock(&cma_mutex);
 286                 if (ret == 0) {
 287                         page = pfn_to_page(pfn);
 288                         break;
 289                 }
 290
 291                 cma_clear_bitmap(cma, pfn, count);
 292                 if (ret != -EBUSY)
 293                         break;
 294
 295                 pr_debug("%s(): memory range at %p is busy, retrying\n",
 296                          __func__, pfn_to_page(pfn));
 297                 /* try again with a bit different memory target */
 298                 start = bitmap_no + mask + 1;
 299         }
 300
 301         pr_debug("%s(): returned %p\n", __func__, page);
 302         return page;
 303 }
 304
 305 /**
 306  * cma_release() - release allocated pages
 307  * @cma:   Contiguous memory region for which the allocation is performed.
 308  * @pages: Allocated pages.
 309  * @count: Number of allocated pages.
 310  *
 311  * This function releases memory allocated by alloc_cma().
 312  * It returns false when provided pages do not belong to contiguous area and
 313  * true otherwise.
 314  */
 315 bool cma_release(struct cma *cma, struct page *pages, int count)
 316 {
 317         unsigned long pfn;
 318
 319         if (!cma || !pages)
 320                 return false;
 321
 322         pr_debug("%s(page %p)\n", __func__, (void *)pages);
 323
 324         pfn = page_to_pfn(pages);
 325
 326         if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
 327                 return false;
 328
 329         VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
 330
 331         free_contig_range(pfn, count);
 332         cma_clear_bitmap(cma, pfn, count);
 333
 334         return true;
 335 }