drivers/dma-buf/udmabuf.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/cred.h>
   3 #include <linux/device.h>
   4 #include <linux/dma-buf.h>
   5 #include <linux/dma-resv.h>
   6 #include <linux/highmem.h>
   7 #include <linux/init.h>
   8 #include <linux/kernel.h>
   9 #include <linux/memfd.h>
  10 #include <linux/miscdevice.h>
  11 #include <linux/module.h>
  12 #include <linux/shmem_fs.h>
  13 #include <linux/slab.h>
  14 #include <linux/udmabuf.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/iosys-map.h>
  17
  18 static int list_limit = 1024;
  19 module_param(list_limit, int, 0644);
  20 MODULE_PARM_DESC(list_limit, "udmabuf_create_list->count limit. Default is 1024.");
  21
  22 static int size_limit_mb = 64;
  23 module_param(size_limit_mb, int, 0644);
  24 MODULE_PARM_DESC(size_limit_mb, "Max size of a dmabuf, in megabytes. Default is 64.");
  25
  26 struct udmabuf {
  27         pgoff_t pagecount;
  28         struct page **pages;
  29         struct sg_table *sg;
  30         struct miscdevice *device;
  31 };
  32
  33 static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf)
  34 {
  35         struct vm_area_struct *vma = vmf->vma;
  36         struct udmabuf *ubuf = vma->vm_private_data;
  37         pgoff_t pgoff = vmf->pgoff;
  38
  39         if (pgoff >= ubuf->pagecount)
  40                 return VM_FAULT_SIGBUS;
  41         vmf->page = ubuf->pages[pgoff];
  42         get_page(vmf->page);
  43         return 0;
  44 }
  45
  46 static const struct vm_operations_struct udmabuf_vm_ops = {
  47         .fault = udmabuf_vm_fault,
  48 };
  49
  50 static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
  51 {
  52         struct udmabuf *ubuf = buf->priv;
  53
  54         if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
  55                 return -EINVAL;
  56
  57         vma->vm_ops = &udmabuf_vm_ops;
  58         vma->vm_private_data = ubuf;
  59         return 0;
  60 }
  61
  62 static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
  63 {
  64         struct udmabuf *ubuf = buf->priv;
  65         void *vaddr;
  66
  67         dma_resv_assert_held(buf->resv);
  68
  69         vaddr = vm_map_ram(ubuf->pages, ubuf->pagecount, -1);
  70         if (!vaddr)
  71                 return -EINVAL;
  72
  73         iosys_map_set_vaddr(map, vaddr);
  74         return 0;
  75 }
  76
  77 static void vunmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
  78 {
  79         struct udmabuf *ubuf = buf->priv;
  80
  81         dma_resv_assert_held(buf->resv);
  82
  83         vm_unmap_ram(map->vaddr, ubuf->pagecount);
  84 }
  85
  86 static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
  87                                      enum dma_data_direction direction)
  88 {
  89         struct udmabuf *ubuf = buf->priv;
  90         struct sg_table *sg;
  91         int ret;
  92
  93         sg = kzalloc(sizeof(*sg), GFP_KERNEL);
  94         if (!sg)
  95                 return ERR_PTR(-ENOMEM);
  96         ret = sg_alloc_table_from_pages(sg, ubuf->pages, ubuf->pagecount,
  97                                         0, ubuf->pagecount << PAGE_SHIFT,
  98                                         GFP_KERNEL);
  99         if (ret < 0)
 100                 goto err;
 101         ret = dma_map_sgtable(dev, sg, direction, 0);
 102         if (ret < 0)
 103                 goto err;
 104         return sg;
 105
 106 err:
 107         sg_free_table(sg);
 108         kfree(sg);
 109         return ERR_PTR(ret);
 110 }
 111
 112 static void put_sg_table(struct device *dev, struct sg_table *sg,
 113                          enum dma_data_direction direction)
 114 {
 115         dma_unmap_sgtable(dev, sg, direction, 0);
 116         sg_free_table(sg);
 117         kfree(sg);
 118 }
 119
 120 static struct sg_table *map_udmabuf(struct dma_buf_attachment *at,
 121                                     enum dma_data_direction direction)
 122 {
 123         return get_sg_table(at->dev, at->dmabuf, direction);
 124 }
 125
 126 static void unmap_udmabuf(struct dma_buf_attachment *at,
 127                           struct sg_table *sg,
 128                           enum dma_data_direction direction)
 129 {
 130         return put_sg_table(at->dev, sg, direction);
 131 }
 132
 133 static void release_udmabuf(struct dma_buf *buf)
 134 {
 135         struct udmabuf *ubuf = buf->priv;
 136         struct device *dev = ubuf->device->this_device;
 137         pgoff_t pg;
 138
 139         if (ubuf->sg)
 140                 put_sg_table(dev, ubuf->sg, DMA_BIDIRECTIONAL);
 141
 142         for (pg = 0; pg < ubuf->pagecount; pg++)
 143                 put_page(ubuf->pages[pg]);
 144         kfree(ubuf->pages);
 145         kfree(ubuf);
 146 }
 147
 148 static int begin_cpu_udmabuf(struct dma_buf *buf,
 149                              enum dma_data_direction direction)
 150 {
 151         struct udmabuf *ubuf = buf->priv;
 152         struct device *dev = ubuf->device->this_device;
 153         int ret = 0;
 154
 155         if (!ubuf->sg) {
 156                 ubuf->sg = get_sg_table(dev, buf, direction);
 157                 if (IS_ERR(ubuf->sg)) {
 158                         ret = PTR_ERR(ubuf->sg);
 159                         ubuf->sg = NULL;
 160                 }
 161         } else {
 162                 dma_sync_sg_for_cpu(dev, ubuf->sg->sgl, ubuf->sg->nents,
 163                                     direction);
 164         }
 165
 166         return ret;
 167 }
 168
 169 static int end_cpu_udmabuf(struct dma_buf *buf,
 170                            enum dma_data_direction direction)
 171 {
 172         struct udmabuf *ubuf = buf->priv;
 173         struct device *dev = ubuf->device->this_device;
 174
 175         if (!ubuf->sg)
 176                 return -EINVAL;
 177
 178         dma_sync_sg_for_device(dev, ubuf->sg->sgl, ubuf->sg->nents, direction);
 179         return 0;
 180 }
 181
 182 static const struct dma_buf_ops udmabuf_ops = {
 183         .cache_sgt_mapping = true,
 184         .map_dma_buf       = map_udmabuf,
 185         .unmap_dma_buf     = unmap_udmabuf,
 186         .release           = release_udmabuf,
 187         .mmap              = mmap_udmabuf,
 188         .vmap              = vmap_udmabuf,
 189         .vunmap            = vunmap_udmabuf,
 190         .begin_cpu_access  = begin_cpu_udmabuf,
 191         .end_cpu_access    = end_cpu_udmabuf,
 192 };
 193
 194 #define SEALS_WANTED (F_SEAL_SHRINK)
 195 #define SEALS_DENIED (F_SEAL_WRITE)
 196
 197 static long udmabuf_create(struct miscdevice *device,
 198                            struct udmabuf_create_list *head,
 199                            struct udmabuf_create_item *list)
 200 {
 201         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 202         struct file *memfd = NULL;
 203         struct address_space *mapping = NULL;
 204         struct udmabuf *ubuf;
 205         struct dma_buf *buf;
 206         pgoff_t pgoff, pgcnt, pgidx, pgbuf = 0, pglimit;
 207         struct page *page;
 208         int seals, ret = -EINVAL;
 209         u32 i, flags;
 210
 211         ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL);
 212         if (!ubuf)
 213                 return -ENOMEM;
 214
 215         pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
 216         for (i = 0; i < head->count; i++) {
 217                 if (!IS_ALIGNED(list[i].offset, PAGE_SIZE))
 218                         goto err;
 219                 if (!IS_ALIGNED(list[i].size, PAGE_SIZE))
 220                         goto err;
 221                 ubuf->pagecount += list[i].size >> PAGE_SHIFT;
 222                 if (ubuf->pagecount > pglimit)
 223                         goto err;
 224         }
 225
 226         if (!ubuf->pagecount)
 227                 goto err;
 228
 229         ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(*ubuf->pages),
 230                                     GFP_KERNEL);
 231         if (!ubuf->pages) {
 232                 ret = -ENOMEM;
 233                 goto err;
 234         }
 235
 236         pgbuf = 0;
 237         for (i = 0; i < head->count; i++) {
 238                 ret = -EBADFD;
 239                 memfd = fget(list[i].memfd);
 240                 if (!memfd)
 241                         goto err;
 242                 mapping = memfd->f_mapping;
 243                 if (!shmem_mapping(mapping))
 244                         goto err;
 245                 seals = memfd_fcntl(memfd, F_GET_SEALS, 0);
 246                 if (seals == -EINVAL)
 247                         goto err;
 248                 ret = -EINVAL;
 249                 if ((seals & SEALS_WANTED) != SEALS_WANTED ||
 250                     (seals & SEALS_DENIED) != 0)
 251                         goto err;
 252                 pgoff = list[i].offset >> PAGE_SHIFT;
 253                 pgcnt = list[i].size   >> PAGE_SHIFT;
 254                 for (pgidx = 0; pgidx < pgcnt; pgidx++) {
 255                         page = shmem_read_mapping_page(mapping, pgoff + pgidx);
 256                         if (IS_ERR(page)) {
 257                                 ret = PTR_ERR(page);
 258                                 goto err;
 259                         }
 260                         ubuf->pages[pgbuf++] = page;
 261                 }
 262                 fput(memfd);
 263                 memfd = NULL;
 264         }
 265
 266         exp_info.ops  = &udmabuf_ops;
 267         exp_info.size = ubuf->pagecount << PAGE_SHIFT;
 268         exp_info.priv = ubuf;
 269         exp_info.flags = O_RDWR;
 270
 271         ubuf->device = device;
 272         buf = dma_buf_export(&exp_info);
 273         if (IS_ERR(buf)) {
 274                 ret = PTR_ERR(buf);
 275                 goto err;
 276         }
 277
 278         flags = 0;
 279         if (head->flags & UDMABUF_FLAGS_CLOEXEC)
 280                 flags |= O_CLOEXEC;
 281         return dma_buf_fd(buf, flags);
 282
 283 err:
 284         while (pgbuf > 0)
 285                 put_page(ubuf->pages[--pgbuf]);
 286         if (memfd)
 287                 fput(memfd);
 288         kfree(ubuf->pages);
 289         kfree(ubuf);
 290         return ret;
 291 }
 292
 293 static long udmabuf_ioctl_create(struct file *filp, unsigned long arg)
 294 {
 295         struct udmabuf_create create;
 296         struct udmabuf_create_list head;
 297         struct udmabuf_create_item list;
 298
 299         if (copy_from_user(&create, (void __user *)arg,
 300                            sizeof(create)))
 301                 return -EFAULT;
 302
 303         head.flags  = create.flags;
 304         head.count  = 1;
 305         list.memfd  = create.memfd;
 306         list.offset = create.offset;
 307         list.size   = create.size;
 308
 309         return udmabuf_create(filp->private_data, &head, &list);
 310 }
 311
 312 static long udmabuf_ioctl_create_list(struct file *filp, unsigned long arg)
 313 {
 314         struct udmabuf_create_list head;
 315         struct udmabuf_create_item *list;
 316         int ret = -EINVAL;
 317         u32 lsize;
 318
 319         if (copy_from_user(&head, (void __user *)arg, sizeof(head)))
 320                 return -EFAULT;
 321         if (head.count > list_limit)
 322                 return -EINVAL;
 323         lsize = sizeof(struct udmabuf_create_item) * head.count;
 324         list = memdup_user((void __user *)(arg + sizeof(head)), lsize);
 325         if (IS_ERR(list))
 326                 return PTR_ERR(list);
 327
 328         ret = udmabuf_create(filp->private_data, &head, list);
 329         kfree(list);
 330         return ret;
 331 }
 332
 333 static long udmabuf_ioctl(struct file *filp, unsigned int ioctl,
 334                           unsigned long arg)
 335 {
 336         long ret;
 337
 338         switch (ioctl) {
 339         case UDMABUF_CREATE:
 340                 ret = udmabuf_ioctl_create(filp, arg);
 341                 break;
 342         case UDMABUF_CREATE_LIST:
 343                 ret = udmabuf_ioctl_create_list(filp, arg);
 344                 break;
 345         default:
 346                 ret = -ENOTTY;
 347                 break;
 348         }
 349         return ret;
 350 }
 351
 352 static const struct file_operations udmabuf_fops = {
 353         .owner          = THIS_MODULE,
 354         .unlocked_ioctl = udmabuf_ioctl,
 355 #ifdef CONFIG_COMPAT
 356         .compat_ioctl   = udmabuf_ioctl,
 357 #endif
 358 };
 359
 360 static struct miscdevice udmabuf_misc = {
 361         .minor          = MISC_DYNAMIC_MINOR,
 362         .name           = "udmabuf",
 363         .fops           = &udmabuf_fops,
 364 };
 365
 366 static int __init udmabuf_dev_init(void)
 367 {
 368         int ret;
 369
 370         ret = misc_register(&udmabuf_misc);
 371         if (ret < 0) {
 372                 pr_err("Could not initialize udmabuf device\n");
 373                 return ret;
 374         }
 375
 376         ret = dma_coerce_mask_and_coherent(udmabuf_misc.this_device,
 377                                            DMA_BIT_MASK(64));
 378         if (ret < 0) {
 379                 pr_err("Could not setup DMA mask for udmabuf device\n");
 380                 misc_deregister(&udmabuf_misc);
 381                 return ret;
 382         }
 383
 384         return 0;
 385 }
 386
 387 static void __exit udmabuf_dev_exit(void)
 388 {
 389         misc_deregister(&udmabuf_misc);
 390 }
 391
 392 module_init(udmabuf_dev_init)
 393 module_exit(udmabuf_dev_exit)
 394
 395 MODULE_AUTHOR("Gerd Hoffmann <kraxel@redhat.com>");