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