kernel/dma/pool.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2012 ARM Ltd.
   4  * Copyright (C) 2020 Google LLC
   5  */
   6 #include <linux/debugfs.h>
   7 #include <linux/dma-direct.h>
   8 #include <linux/dma-noncoherent.h>
   9 #include <linux/init.h>
  10 #include <linux/genalloc.h>
  11 #include <linux/set_memory.h>
  12 #include <linux/slab.h>
  13 #include <linux/workqueue.h>
  14
  15 static struct gen_pool *atomic_pool_dma __ro_after_init;
  16 static unsigned long pool_size_dma;
  17 static struct gen_pool *atomic_pool_dma32 __ro_after_init;
  18 static unsigned long pool_size_dma32;
  19 static struct gen_pool *atomic_pool_kernel __ro_after_init;
  20 static unsigned long pool_size_kernel;
  21
  22 /* Size can be defined by the coherent_pool command line */
  23 static size_t atomic_pool_size;
  24
  25 /* Dynamic background expansion when the atomic pool is near capacity */
  26 static struct work_struct atomic_pool_work;
  27
  28 static int __init early_coherent_pool(char *p)
  29 {
  30         atomic_pool_size = memparse(p, &p);
  31         return 0;
  32 }
  33 early_param("coherent_pool", early_coherent_pool);
  34
  35 static void __init dma_atomic_pool_debugfs_init(void)
  36 {
  37         struct dentry *root;
  38
  39         root = debugfs_create_dir("dma_pools", NULL);
  40         if (IS_ERR_OR_NULL(root))
  41                 return;
  42
  43         debugfs_create_ulong("pool_size_dma", 0400, root, &pool_size_dma);
  44         debugfs_create_ulong("pool_size_dma32", 0400, root, &pool_size_dma32);
  45         debugfs_create_ulong("pool_size_kernel", 0400, root, &pool_size_kernel);
  46 }
  47
  48 static void dma_atomic_pool_size_add(gfp_t gfp, size_t size)
  49 {
  50         if (gfp & __GFP_DMA)
  51                 pool_size_dma += size;
  52         else if (gfp & __GFP_DMA32)
  53                 pool_size_dma32 += size;
  54         else
  55                 pool_size_kernel += size;
  56 }
  57
  58 static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
  59                               gfp_t gfp)
  60 {
  61         unsigned int order;
  62         struct page *page;
  63         void *addr;
  64         int ret = -ENOMEM;
  65
  66         /* Cannot allocate larger than MAX_ORDER-1 */
  67         order = min(get_order(pool_size), MAX_ORDER-1);
  68
  69         do {
  70                 pool_size = 1 << (PAGE_SHIFT + order);
  71                 page = alloc_pages(gfp, order);
  72         } while (!page && order-- > 0);
  73         if (!page)
  74                 goto out;
  75
  76         arch_dma_prep_coherent(page, pool_size);
  77
  78 #ifdef CONFIG_DMA_DIRECT_REMAP
  79         addr = dma_common_contiguous_remap(page, pool_size,
  80                                            pgprot_dmacoherent(PAGE_KERNEL),
  81                                            __builtin_return_address(0));
  82         if (!addr)
  83                 goto free_page;
  84 #else
  85         addr = page_to_virt(page);
  86 #endif
  87         /*
  88          * Memory in the atomic DMA pools must be unencrypted, the pools do not
  89          * shrink so no re-encryption occurs in dma_direct_free_pages().
  90          */
  91         ret = set_memory_decrypted((unsigned long)page_to_virt(page),
  92                                    1 << order);
  93         if (ret)
  94                 goto remove_mapping;
  95         ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page),
  96                                 pool_size, NUMA_NO_NODE);
  97         if (ret)
  98                 goto encrypt_mapping;
  99
 100         dma_atomic_pool_size_add(gfp, pool_size);
 101         return 0;
 102
 103 encrypt_mapping:
 104         ret = set_memory_encrypted((unsigned long)page_to_virt(page),
 105                                    1 << order);
 106         if (WARN_ON_ONCE(ret)) {
 107                 /* Decrypt succeeded but encrypt failed, purposely leak */
 108                 goto out;
 109         }
 110 remove_mapping:
 111 #ifdef CONFIG_DMA_DIRECT_REMAP
 112         dma_common_free_remap(addr, pool_size);
 113 #endif
 114 free_page: __maybe_unused
 115         __free_pages(page, order);
 116 out:
 117         return ret;
 118 }
 119
 120 static void atomic_pool_resize(struct gen_pool *pool, gfp_t gfp)
 121 {
 122         if (pool && gen_pool_avail(pool) < atomic_pool_size)
 123                 atomic_pool_expand(pool, gen_pool_size(pool), gfp);
 124 }
 125
 126 static void atomic_pool_work_fn(struct work_struct *work)
 127 {
 128         if (IS_ENABLED(CONFIG_ZONE_DMA))
 129                 atomic_pool_resize(atomic_pool_dma,
 130                                    GFP_KERNEL | GFP_DMA);
 131         if (IS_ENABLED(CONFIG_ZONE_DMA32))
 132                 atomic_pool_resize(atomic_pool_dma32,
 133                                    GFP_KERNEL | GFP_DMA32);
 134         atomic_pool_resize(atomic_pool_kernel, GFP_KERNEL);
 135 }
 136
 137 static __init struct gen_pool *__dma_atomic_pool_init(size_t pool_size,
 138                                                       gfp_t gfp)
 139 {
 140         struct gen_pool *pool;
 141         int ret;
 142
 143         pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
 144         if (!pool)
 145                 return NULL;
 146
 147         gen_pool_set_algo(pool, gen_pool_first_fit_order_align, NULL);
 148
 149         ret = atomic_pool_expand(pool, pool_size, gfp);
 150         if (ret) {
 151                 gen_pool_destroy(pool);
 152                 pr_err("DMA: failed to allocate %zu KiB %pGg pool for atomic allocation\n",
 153                        pool_size >> 10, &gfp);
 154                 return NULL;
 155         }
 156
 157         pr_info("DMA: preallocated %zu KiB %pGg pool for atomic allocations\n",
 158                 gen_pool_size(pool) >> 10, &gfp);
 159         return pool;
 160 }
 161
 162 static int __init dma_atomic_pool_init(void)
 163 {
 164         int ret = 0;
 165
 166         /*
 167          * If coherent_pool was not used on the command line, default the pool
 168          * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER-1.
 169          */
 170         if (!atomic_pool_size) {
 171                 unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K);
 172                 pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES);
 173                 atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K);
 174         }
 175         INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);
 176
 177         atomic_pool_kernel = __dma_atomic_pool_init(atomic_pool_size,
 178                                                     GFP_KERNEL);
 179         if (!atomic_pool_kernel)
 180                 ret = -ENOMEM;
 181         if (IS_ENABLED(CONFIG_ZONE_DMA)) {
 182                 atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
 183                                                 GFP_KERNEL | GFP_DMA);
 184                 if (!atomic_pool_dma)
 185                         ret = -ENOMEM;
 186         }
 187         if (IS_ENABLED(CONFIG_ZONE_DMA32)) {
 188                 atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
 189                                                 GFP_KERNEL | GFP_DMA32);
 190                 if (!atomic_pool_dma32)
 191                         ret = -ENOMEM;
 192         }
 193
 194         dma_atomic_pool_debugfs_init();
 195         return ret;
 196 }
 197 postcore_initcall(dma_atomic_pool_init);
 198
 199 static inline struct gen_pool *dma_guess_pool_from_device(struct device *dev)
 200 {
 201         u64 phys_mask;
 202         gfp_t gfp;
 203
 204         gfp = dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
 205                                           &phys_mask);
 206         if (IS_ENABLED(CONFIG_ZONE_DMA) && gfp == GFP_DMA)
 207                 return atomic_pool_dma;
 208         if (IS_ENABLED(CONFIG_ZONE_DMA32) && gfp == GFP_DMA32)
 209                 return atomic_pool_dma32;
 210         return atomic_pool_kernel;
 211 }
 212
 213 static inline struct gen_pool *dma_get_safer_pool(struct gen_pool *bad_pool)
 214 {
 215         if (bad_pool == atomic_pool_kernel)
 216                 return atomic_pool_dma32 ? : atomic_pool_dma;
 217
 218         if (bad_pool == atomic_pool_dma32)
 219                 return atomic_pool_dma;
 220
 221         return NULL;
 222 }
 223
 224 static inline struct gen_pool *dma_guess_pool(struct device *dev,
 225                                               struct gen_pool *bad_pool)
 226 {
 227         if (bad_pool)
 228                 return dma_get_safer_pool(bad_pool);
 229
 230         return dma_guess_pool_from_device(dev);
 231 }
 232
 233 void *dma_alloc_from_pool(struct device *dev, size_t size,
 234                           struct page **ret_page, gfp_t flags)
 235 {
 236         struct gen_pool *pool = NULL;
 237         unsigned long val = 0;
 238         void *ptr = NULL;
 239         phys_addr_t phys;
 240
 241         while (1) {
 242                 pool = dma_guess_pool(dev, pool);
 243                 if (!pool) {
 244                         WARN(1, "Failed to get suitable pool for %s\n",
 245                              dev_name(dev));
 246                         break;
 247                 }
 248
 249                 val = gen_pool_alloc(pool, size);
 250                 if (!val)
 251                         continue;
 252
 253                 phys = gen_pool_virt_to_phys(pool, val);
 254                 if (dma_coherent_ok(dev, phys, size))
 255                         break;
 256
 257                 gen_pool_free(pool, val, size);
 258                 val = 0;
 259         }
 260
 261
 262         if (val) {
 263                 *ret_page = pfn_to_page(__phys_to_pfn(phys));
 264                 ptr = (void *)val;
 265                 memset(ptr, 0, size);
 266
 267                 if (gen_pool_avail(pool) < atomic_pool_size)
 268                         schedule_work(&atomic_pool_work);
 269         }
 270
 271         return ptr;
 272 }
 273
 274 bool dma_free_from_pool(struct device *dev, void *start, size_t size)
 275 {
 276         struct gen_pool *pool = NULL;
 277
 278         while (1) {
 279                 pool = dma_guess_pool(dev, pool);
 280                 if (!pool)
 281                         return false;
 282
 283                 if (gen_pool_has_addr(pool, (unsigned long)start, size)) {
 284                         gen_pool_free(pool, (unsigned long)start, size);
 285                         return true;
 286                 }
 287         }
 288 }