kernel/dma/remap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2012 ARM Ltd.
   4  * Copyright (c) 2014 The Linux Foundation
   5  */
   6 #include <linux/dma-direct.h>
   7 #include <linux/dma-noncoherent.h>
   8 #include <linux/dma-contiguous.h>
   9 #include <linux/init.h>
  10 #include <linux/genalloc.h>
  11 #include <linux/slab.h>
  12 #include <linux/vmalloc.h>
  13
  14 static struct vm_struct *__dma_common_pages_remap(struct page **pages,
  15                         size_t size, unsigned long vm_flags, pgprot_t prot,
  16                         const void *caller)
  17 {
  18         struct vm_struct *area;
  19
  20         area = get_vm_area_caller(size, vm_flags, caller);
  21         if (!area)
  22                 return NULL;
  23
  24         if (map_vm_area(area, prot, pages)) {
  25                 vunmap(area->addr);
  26                 return NULL;
  27         }
  28
  29         return area;
  30 }
  31
  32 /*
  33  * Remaps an array of PAGE_SIZE pages into another vm_area.
  34  * Cannot be used in non-sleeping contexts
  35  */
  36 void *dma_common_pages_remap(struct page **pages, size_t size,
  37                         unsigned long vm_flags, pgprot_t prot,
  38                         const void *caller)
  39 {
  40         struct vm_struct *area;
  41
  42         area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
  43         if (!area)
  44                 return NULL;
  45
  46         area->pages = pages;
  47
  48         return area->addr;
  49 }
  50
  51 /*
  52  * Remaps an allocated contiguous region into another vm_area.
  53  * Cannot be used in non-sleeping contexts
  54  */
  55 void *dma_common_contiguous_remap(struct page *page, size_t size,
  56                         unsigned long vm_flags,
  57                         pgprot_t prot, const void *caller)
  58 {
  59         int i;
  60         struct page **pages;
  61         struct vm_struct *area;
  62
  63         pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
  64         if (!pages)
  65                 return NULL;
  66
  67         for (i = 0; i < (size >> PAGE_SHIFT); i++)
  68                 pages[i] = nth_page(page, i);
  69
  70         area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);
  71
  72         kfree(pages);
  73
  74         if (!area)
  75                 return NULL;
  76         return area->addr;
  77 }
  78
  79 /*
  80  * Unmaps a range previously mapped by dma_common_*_remap
  81  */
  82 void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
  83 {
  84         struct vm_struct *area = find_vm_area(cpu_addr);
  85
  86         if (!area || (area->flags & vm_flags) != vm_flags) {
  87                 WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
  88                 return;
  89         }
  90
  91         unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
  92         vunmap(cpu_addr);
  93 }
  94
  95 #ifdef CONFIG_DMA_DIRECT_REMAP
  96 static struct gen_pool *atomic_pool __ro_after_init;
  97
  98 #define DEFAULT_DMA_COHERENT_POOL_SIZE  SZ_256K
  99 static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE;
 100
 101 static int __init early_coherent_pool(char *p)
 102 {
 103         atomic_pool_size = memparse(p, &p);
 104         return 0;
 105 }
 106 early_param("coherent_pool", early_coherent_pool);
 107
 108 int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot)
 109 {
 110         unsigned int pool_size_order = get_order(atomic_pool_size);
 111         unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT;
 112         struct page *page;
 113         void *addr;
 114         int ret;
 115
 116         if (dev_get_cma_area(NULL))
 117                 page = dma_alloc_from_contiguous(NULL, nr_pages,
 118                                                  pool_size_order, false);
 119         else
 120                 page = alloc_pages(gfp, pool_size_order);
 121         if (!page)
 122                 goto out;
 123
 124         arch_dma_prep_coherent(page, atomic_pool_size);
 125
 126         atomic_pool = gen_pool_create(PAGE_SHIFT, -1);
 127         if (!atomic_pool)
 128                 goto free_page;
 129
 130         addr = dma_common_contiguous_remap(page, atomic_pool_size, VM_USERMAP,
 131                                            prot, __builtin_return_address(0));
 132         if (!addr)
 133                 goto destroy_genpool;
 134
 135         ret = gen_pool_add_virt(atomic_pool, (unsigned long)addr,
 136                                 page_to_phys(page), atomic_pool_size, -1);
 137         if (ret)
 138                 goto remove_mapping;
 139         gen_pool_set_algo(atomic_pool, gen_pool_first_fit_order_align, NULL);
 140
 141         pr_info("DMA: preallocated %zu KiB pool for atomic allocations\n",
 142                 atomic_pool_size / 1024);
 143         return 0;
 144
 145 remove_mapping:
 146         dma_common_free_remap(addr, atomic_pool_size, VM_USERMAP);
 147 destroy_genpool:
 148         gen_pool_destroy(atomic_pool);
 149         atomic_pool = NULL;
 150 free_page:
 151         if (!dma_release_from_contiguous(NULL, page, nr_pages))
 152                 __free_pages(page, pool_size_order);
 153 out:
 154         pr_err("DMA: failed to allocate %zu KiB pool for atomic coherent allocation\n",
 155                 atomic_pool_size / 1024);
 156         return -ENOMEM;
 157 }
 158
 159 bool dma_in_atomic_pool(void *start, size_t size)
 160 {
 161         return addr_in_gen_pool(atomic_pool, (unsigned long)start, size);
 162 }
 163
 164 void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags)
 165 {
 166         unsigned long val;
 167         void *ptr = NULL;
 168
 169         if (!atomic_pool) {
 170                 WARN(1, "coherent pool not initialised!\n");
 171                 return NULL;
 172         }
 173
 174         val = gen_pool_alloc(atomic_pool, size);
 175         if (val) {
 176                 phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
 177
 178                 *ret_page = pfn_to_page(__phys_to_pfn(phys));
 179                 ptr = (void *)val;
 180                 memset(ptr, 0, size);
 181         }
 182
 183         return ptr;
 184 }
 185
 186 bool dma_free_from_pool(void *start, size_t size)
 187 {
 188         if (!dma_in_atomic_pool(start, size))
 189                 return false;
 190         gen_pool_free(atomic_pool, (unsigned long)start, size);
 191         return true;
 192 }
 193
 194 void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 195                 gfp_t flags, unsigned long attrs)
 196 {
 197         struct page *page = NULL;
 198         void *ret;
 199
 200         size = PAGE_ALIGN(size);
 201
 202         if (!gfpflags_allow_blocking(flags) &&
 203             !(attrs & DMA_ATTR_NO_KERNEL_MAPPING)) {
 204                 ret = dma_alloc_from_pool(size, &page, flags);
 205                 if (!ret)
 206                         return NULL;
 207                 goto done;
 208         }
 209
 210         page = __dma_direct_alloc_pages(dev, size, dma_handle, flags, attrs);
 211         if (!page)
 212                 return NULL;
 213
 214         /* remove any dirty cache lines on the kernel alias */
 215         arch_dma_prep_coherent(page, size);
 216
 217         if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
 218                 ret = page; /* opaque cookie */
 219                 goto done;
 220         }
 221
 222         /* create a coherent mapping */
 223         ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
 224                         arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs),
 225                         __builtin_return_address(0));
 226         if (!ret) {
 227                 __dma_direct_free_pages(dev, size, page);
 228                 return ret;
 229         }
 230
 231         memset(ret, 0, size);
 232 done:
 233         *dma_handle = phys_to_dma(dev, page_to_phys(page));
 234         return ret;
 235 }
 236
 237 void arch_dma_free(struct device *dev, size_t size, void *vaddr,
 238                 dma_addr_t dma_handle, unsigned long attrs)
 239 {
 240         if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
 241                 /* vaddr is a struct page cookie, not a kernel address */
 242                 __dma_direct_free_pages(dev, size, vaddr);
 243         } else if (!dma_free_from_pool(vaddr, PAGE_ALIGN(size))) {
 244                 phys_addr_t phys = dma_to_phys(dev, dma_handle);
 245                 struct page *page = pfn_to_page(__phys_to_pfn(phys));
 246
 247                 vunmap(vaddr);
 248                 __dma_direct_free_pages(dev, size, page);
 249         }
 250 }
 251
 252 long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
 253                 dma_addr_t dma_addr)
 254 {
 255         return __phys_to_pfn(dma_to_phys(dev, dma_addr));
 256 }
 257 #endif /* CONFIG_DMA_DIRECT_REMAP */