drivers/gpu/drm/drm_gem_shmem_helper.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2018 Noralf Trønnes
   4  */
   5
   6 #include <linux/dma-buf.h>
   7 #include <linux/export.h>
   8 #include <linux/module.h>
   9 #include <linux/mutex.h>
  10 #include <linux/shmem_fs.h>
  11 #include <linux/slab.h>
  12 #include <linux/vmalloc.h>
  13
  14 #ifdef CONFIG_X86
  15 #include <asm/set_memory.h>
  16 #endif
  17
  18 #include <drm/drm.h>
  19 #include <drm/drm_device.h>
  20 #include <drm/drm_drv.h>
  21 #include <drm/drm_gem_shmem_helper.h>
  22 #include <drm/drm_prime.h>
  23 #include <drm/drm_print.h>
  24
  25 MODULE_IMPORT_NS(DMA_BUF);
  26
  27 /**
  28  * DOC: overview
  29  *
  30  * This library provides helpers for GEM objects backed by shmem buffers
  31  * allocated using anonymous pageable memory.
  32  *
  33  * Functions that operate on the GEM object receive struct &drm_gem_shmem_object.
  34  * For GEM callback helpers in struct &drm_gem_object functions, see likewise
  35  * named functions with an _object_ infix (e.g., drm_gem_shmem_object_vmap() wraps
  36  * drm_gem_shmem_vmap()). These helpers perform the necessary type conversion.
  37  */
  38
  39 static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
  40         .free = drm_gem_shmem_object_free,
  41         .print_info = drm_gem_shmem_object_print_info,
  42         .pin = drm_gem_shmem_object_pin,
  43         .unpin = drm_gem_shmem_object_unpin,
  44         .get_sg_table = drm_gem_shmem_object_get_sg_table,
  45         .vmap = drm_gem_shmem_object_vmap,
  46         .vunmap = drm_gem_shmem_object_vunmap,
  47         .mmap = drm_gem_shmem_object_mmap,
  48         .vm_ops = &drm_gem_shmem_vm_ops,
  49 };
  50
  51 static struct drm_gem_shmem_object *
  52 __drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private)
  53 {
  54         struct drm_gem_shmem_object *shmem;
  55         struct drm_gem_object *obj;
  56         int ret = 0;
  57
  58         size = PAGE_ALIGN(size);
  59
  60         if (dev->driver->gem_create_object) {
  61                 obj = dev->driver->gem_create_object(dev, size);
  62                 if (IS_ERR(obj))
  63                         return ERR_CAST(obj);
  64                 shmem = to_drm_gem_shmem_obj(obj);
  65         } else {
  66                 shmem = kzalloc(sizeof(*shmem), GFP_KERNEL);
  67                 if (!shmem)
  68                         return ERR_PTR(-ENOMEM);
  69                 obj = &shmem->base;
  70         }
  71
  72         if (!obj->funcs)
  73                 obj->funcs = &drm_gem_shmem_funcs;
  74
  75         if (private) {
  76                 drm_gem_private_object_init(dev, obj, size);
  77                 shmem->map_wc = false; /* dma-buf mappings use always writecombine */
  78         } else {
  79                 ret = drm_gem_object_init(dev, obj, size);
  80         }
  81         if (ret) {
  82                 drm_gem_private_object_fini(obj);
  83                 goto err_free;
  84         }
  85
  86         ret = drm_gem_create_mmap_offset(obj);
  87         if (ret)
  88                 goto err_release;
  89
  90         INIT_LIST_HEAD(&shmem->madv_list);
  91
  92         if (!private) {
  93                 /*
  94                  * Our buffers are kept pinned, so allocating them
  95                  * from the MOVABLE zone is a really bad idea, and
  96                  * conflicts with CMA. See comments above new_inode()
  97                  * why this is required _and_ expected if you're
  98                  * going to pin these pages.
  99                  */
 100                 mapping_set_gfp_mask(obj->filp->f_mapping, GFP_HIGHUSER |
 101                                      __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
 102         }
 103
 104         return shmem;
 105
 106 err_release:
 107         drm_gem_object_release(obj);
 108 err_free:
 109         kfree(obj);
 110
 111         return ERR_PTR(ret);
 112 }
 113 /**
 114  * drm_gem_shmem_create - Allocate an object with the given size
 115  * @dev: DRM device
 116  * @size: Size of the object to allocate
 117  *
 118  * This function creates a shmem GEM object.
 119  *
 120  * Returns:
 121  * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
 122  * error code on failure.
 123  */
 124 struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
 125 {
 126         return __drm_gem_shmem_create(dev, size, false);
 127 }
 128 EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
 129
 130 /**
 131  * drm_gem_shmem_free - Free resources associated with a shmem GEM object
 132  * @shmem: shmem GEM object to free
 133  *
 134  * This function cleans up the GEM object state and frees the memory used to
 135  * store the object itself.
 136  */
 137 void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
 138 {
 139         struct drm_gem_object *obj = &shmem->base;
 140
 141         if (obj->import_attach) {
 142                 drm_prime_gem_destroy(obj, shmem->sgt);
 143         } else {
 144                 dma_resv_lock(shmem->base.resv, NULL);
 145
 146                 drm_WARN_ON(obj->dev, shmem->vmap_use_count);
 147
 148                 if (shmem->sgt) {
 149                         dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
 150                                           DMA_BIDIRECTIONAL, 0);
 151                         sg_free_table(shmem->sgt);
 152                         kfree(shmem->sgt);
 153                 }
 154                 if (shmem->pages)
 155                         drm_gem_shmem_put_pages(shmem);
 156
 157                 drm_WARN_ON(obj->dev, shmem->pages_use_count);
 158
 159                 dma_resv_unlock(shmem->base.resv);
 160         }
 161
 162         drm_gem_object_release(obj);
 163         kfree(shmem);
 164 }
 165 EXPORT_SYMBOL_GPL(drm_gem_shmem_free);
 166
 167 static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
 168 {
 169         struct drm_gem_object *obj = &shmem->base;
 170         struct page **pages;
 171
 172         dma_resv_assert_held(shmem->base.resv);
 173
 174         if (shmem->pages_use_count++ > 0)
 175                 return 0;
 176
 177         pages = drm_gem_get_pages(obj);
 178         if (IS_ERR(pages)) {
 179                 drm_dbg_kms(obj->dev, "Failed to get pages (%ld)\n",
 180                             PTR_ERR(pages));
 181                 shmem->pages_use_count = 0;
 182                 return PTR_ERR(pages);
 183         }
 184
 185         /*
 186          * TODO: Allocating WC pages which are correctly flushed is only
 187          * supported on x86. Ideal solution would be a GFP_WC flag, which also
 188          * ttm_pool.c could use.
 189          */
 190 #ifdef CONFIG_X86
 191         if (shmem->map_wc)
 192                 set_pages_array_wc(pages, obj->size >> PAGE_SHIFT);
 193 #endif
 194
 195         shmem->pages = pages;
 196
 197         return 0;
 198 }
 199
 200 /*
 201  * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
 202  * @shmem: shmem GEM object
 203  *
 204  * This function decreases the use count and puts the backing pages when use drops to zero.
 205  */
 206 void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
 207 {
 208         struct drm_gem_object *obj = &shmem->base;
 209
 210         dma_resv_assert_held(shmem->base.resv);
 211
 212         if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
 213                 return;
 214
 215         if (--shmem->pages_use_count > 0)
 216                 return;
 217
 218 #ifdef CONFIG_X86
 219         if (shmem->map_wc)
 220                 set_pages_array_wb(shmem->pages, obj->size >> PAGE_SHIFT);
 221 #endif
 222
 223         drm_gem_put_pages(obj, shmem->pages,
 224                           shmem->pages_mark_dirty_on_put,
 225                           shmem->pages_mark_accessed_on_put);
 226         shmem->pages = NULL;
 227 }
 228 EXPORT_SYMBOL(drm_gem_shmem_put_pages);
 229
 230 int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
 231 {
 232         int ret;
 233
 234         dma_resv_assert_held(shmem->base.resv);
 235
 236         ret = drm_gem_shmem_get_pages(shmem);
 237
 238         return ret;
 239 }
 240 EXPORT_SYMBOL(drm_gem_shmem_pin_locked);
 241
 242 void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
 243 {
 244         dma_resv_assert_held(shmem->base.resv);
 245
 246         drm_gem_shmem_put_pages(shmem);
 247 }
 248 EXPORT_SYMBOL(drm_gem_shmem_unpin_locked);
 249
 250 /**
 251  * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
 252  * @shmem: shmem GEM object
 253  *
 254  * This function makes sure the backing pages are pinned in memory while the
 255  * buffer is exported.
 256  *
 257  * Returns:
 258  * 0 on success or a negative error code on failure.
 259  */
 260 int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
 261 {
 262         struct drm_gem_object *obj = &shmem->base;
 263         int ret;
 264
 265         drm_WARN_ON(obj->dev, obj->import_attach);
 266
 267         ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
 268         if (ret)
 269                 return ret;
 270         ret = drm_gem_shmem_pin_locked(shmem);
 271         dma_resv_unlock(shmem->base.resv);
 272
 273         return ret;
 274 }
 275 EXPORT_SYMBOL(drm_gem_shmem_pin);
 276
 277 /**
 278  * drm_gem_shmem_unpin - Unpin backing pages for a shmem GEM object
 279  * @shmem: shmem GEM object
 280  *
 281  * This function removes the requirement that the backing pages are pinned in
 282  * memory.
 283  */
 284 void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
 285 {
 286         struct drm_gem_object *obj = &shmem->base;
 287
 288         drm_WARN_ON(obj->dev, obj->import_attach);
 289
 290         dma_resv_lock(shmem->base.resv, NULL);
 291         drm_gem_shmem_unpin_locked(shmem);
 292         dma_resv_unlock(shmem->base.resv);
 293 }
 294 EXPORT_SYMBOL(drm_gem_shmem_unpin);
 295
 296 /*
 297  * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
 298  * @shmem: shmem GEM object
 299  * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
 300  *       store.
 301  *
 302  * This function makes sure that a contiguous kernel virtual address mapping
 303  * exists for the buffer backing the shmem GEM object. It hides the differences
 304  * between dma-buf imported and natively allocated objects.
 305  *
 306  * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap().
 307  *
 308  * Returns:
 309  * 0 on success or a negative error code on failure.
 310  */
 311 int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem,
 312                        struct iosys_map *map)
 313 {
 314         struct drm_gem_object *obj = &shmem->base;
 315         int ret = 0;
 316
 317         if (obj->import_attach) {
 318                 ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
 319                 if (!ret) {
 320                         if (drm_WARN_ON(obj->dev, map->is_iomem)) {
 321                                 dma_buf_vunmap(obj->import_attach->dmabuf, map);
 322                                 return -EIO;
 323                         }
 324                 }
 325         } else {
 326                 pgprot_t prot = PAGE_KERNEL;
 327
 328                 dma_resv_assert_held(shmem->base.resv);
 329
 330                 if (shmem->vmap_use_count++ > 0) {
 331                         iosys_map_set_vaddr(map, shmem->vaddr);
 332                         return 0;
 333                 }
 334
 335                 ret = drm_gem_shmem_get_pages(shmem);
 336                 if (ret)
 337                         goto err_zero_use;
 338
 339                 if (shmem->map_wc)
 340                         prot = pgprot_writecombine(prot);
 341                 shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
 342                                     VM_MAP, prot);
 343                 if (!shmem->vaddr)
 344                         ret = -ENOMEM;
 345                 else
 346                         iosys_map_set_vaddr(map, shmem->vaddr);
 347         }
 348
 349         if (ret) {
 350                 drm_dbg_kms(obj->dev, "Failed to vmap pages, error %d\n", ret);
 351                 goto err_put_pages;
 352         }
 353
 354         return 0;
 355
 356 err_put_pages:
 357         if (!obj->import_attach)
 358                 drm_gem_shmem_put_pages(shmem);
 359 err_zero_use:
 360         shmem->vmap_use_count = 0;
 361
 362         return ret;
 363 }
 364 EXPORT_SYMBOL(drm_gem_shmem_vmap);
 365
 366 /*
 367  * drm_gem_shmem_vunmap - Unmap a virtual mapping for a shmem GEM object
 368  * @shmem: shmem GEM object
 369  * @map: Kernel virtual address where the SHMEM GEM object was mapped
 370  *
 371  * This function cleans up a kernel virtual address mapping acquired by
 372  * drm_gem_shmem_vmap(). The mapping is only removed when the use count drops to
 373  * zero.
 374  *
 375  * This function hides the differences between dma-buf imported and natively
 376  * allocated objects.
 377  */
 378 void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem,
 379                           struct iosys_map *map)
 380 {
 381         struct drm_gem_object *obj = &shmem->base;
 382
 383         if (obj->import_attach) {
 384                 dma_buf_vunmap(obj->import_attach->dmabuf, map);
 385         } else {
 386                 dma_resv_assert_held(shmem->base.resv);
 387
 388                 if (drm_WARN_ON_ONCE(obj->dev, !shmem->vmap_use_count))
 389                         return;
 390
 391                 if (--shmem->vmap_use_count > 0)
 392                         return;
 393
 394                 vunmap(shmem->vaddr);
 395                 drm_gem_shmem_put_pages(shmem);
 396         }
 397
 398         shmem->vaddr = NULL;
 399 }
 400 EXPORT_SYMBOL(drm_gem_shmem_vunmap);
 401
 402 static int
 403 drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
 404                                  struct drm_device *dev, size_t size,
 405                                  uint32_t *handle)
 406 {
 407         struct drm_gem_shmem_object *shmem;
 408         int ret;
 409
 410         shmem = drm_gem_shmem_create(dev, size);
 411         if (IS_ERR(shmem))
 412                 return PTR_ERR(shmem);
 413
 414         /*
 415          * Allocate an id of idr table where the obj is registered
 416          * and handle has the id what user can see.
 417          */
 418         ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
 419         /* drop reference from allocate - handle holds it now. */
 420         drm_gem_object_put(&shmem->base);
 421
 422         return ret;
 423 }
 424
 425 /* Update madvise status, returns true if not purged, else
 426  * false or -errno.
 427  */
 428 int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv)
 429 {
 430         dma_resv_assert_held(shmem->base.resv);
 431
 432         if (shmem->madv >= 0)
 433                 shmem->madv = madv;
 434
 435         madv = shmem->madv;
 436
 437         return (madv >= 0);
 438 }
 439 EXPORT_SYMBOL(drm_gem_shmem_madvise);
 440
 441 void drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem)
 442 {
 443         struct drm_gem_object *obj = &shmem->base;
 444         struct drm_device *dev = obj->dev;
 445
 446         dma_resv_assert_held(shmem->base.resv);
 447
 448         drm_WARN_ON(obj->dev, !drm_gem_shmem_is_purgeable(shmem));
 449
 450         dma_unmap_sgtable(dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
 451         sg_free_table(shmem->sgt);
 452         kfree(shmem->sgt);
 453         shmem->sgt = NULL;
 454
 455         drm_gem_shmem_put_pages(shmem);
 456
 457         shmem->madv = -1;
 458
 459         drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
 460         drm_gem_free_mmap_offset(obj);
 461
 462         /* Our goal here is to return as much of the memory as
 463          * is possible back to the system as we are called from OOM.
 464          * To do this we must instruct the shmfs to drop all of its
 465          * backing pages, *now*.
 466          */
 467         shmem_truncate_range(file_inode(obj->filp), 0, (loff_t)-1);
 468
 469         invalidate_mapping_pages(file_inode(obj->filp)->i_mapping, 0, (loff_t)-1);
 470 }
 471 EXPORT_SYMBOL(drm_gem_shmem_purge);
 472
 473 /**
 474  * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
 475  * @file: DRM file structure to create the dumb buffer for
 476  * @dev: DRM device
 477  * @args: IOCTL data
 478  *
 479  * This function computes the pitch of the dumb buffer and rounds it up to an
 480  * integer number of bytes per pixel. Drivers for hardware that doesn't have
 481  * any additional restrictions on the pitch can directly use this function as
 482  * their &drm_driver.dumb_create callback.
 483  *
 484  * For hardware with additional restrictions, drivers can adjust the fields
 485  * set up by userspace before calling into this function.
 486  *
 487  * Returns:
 488  * 0 on success or a negative error code on failure.
 489  */
 490 int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
 491                               struct drm_mode_create_dumb *args)
 492 {
 493         u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
 494
 495         if (!args->pitch || !args->size) {
 496                 args->pitch = min_pitch;
 497                 args->size = PAGE_ALIGN(args->pitch * args->height);
 498         } else {
 499                 /* ensure sane minimum values */
 500                 if (args->pitch < min_pitch)
 501                         args->pitch = min_pitch;
 502                 if (args->size < args->pitch * args->height)
 503                         args->size = PAGE_ALIGN(args->pitch * args->height);
 504         }
 505
 506         return drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
 507 }
 508 EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
 509
 510 static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
 511 {
 512         struct vm_area_struct *vma = vmf->vma;
 513         struct drm_gem_object *obj = vma->vm_private_data;
 514         struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 515         loff_t num_pages = obj->size >> PAGE_SHIFT;
 516         vm_fault_t ret;
 517         struct page *page;
 518         pgoff_t page_offset;
 519
 520         /* We don't use vmf->pgoff since that has the fake offset */
 521         page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
 522
 523         dma_resv_lock(shmem->base.resv, NULL);
 524
 525         if (page_offset >= num_pages ||
 526             drm_WARN_ON_ONCE(obj->dev, !shmem->pages) ||
 527             shmem->madv < 0) {
 528                 ret = VM_FAULT_SIGBUS;
 529         } else {
 530                 page = shmem->pages[page_offset];
 531
 532                 ret = vmf_insert_pfn(vma, vmf->address, page_to_pfn(page));
 533         }
 534
 535         dma_resv_unlock(shmem->base.resv);
 536
 537         return ret;
 538 }
 539
 540 static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
 541 {
 542         struct drm_gem_object *obj = vma->vm_private_data;
 543         struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 544
 545         drm_WARN_ON(obj->dev, obj->import_attach);
 546
 547         dma_resv_lock(shmem->base.resv, NULL);
 548
 549         /*
 550          * We should have already pinned the pages when the buffer was first
 551          * mmap'd, vm_open() just grabs an additional reference for the new
 552          * mm the vma is getting copied into (ie. on fork()).
 553          */
 554         if (!drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
 555                 shmem->pages_use_count++;
 556
 557         dma_resv_unlock(shmem->base.resv);
 558
 559         drm_gem_vm_open(vma);
 560 }
 561
 562 static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
 563 {
 564         struct drm_gem_object *obj = vma->vm_private_data;
 565         struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 566
 567         dma_resv_lock(shmem->base.resv, NULL);
 568         drm_gem_shmem_put_pages(shmem);
 569         dma_resv_unlock(shmem->base.resv);
 570
 571         drm_gem_vm_close(vma);
 572 }
 573
 574 const struct vm_operations_struct drm_gem_shmem_vm_ops = {
 575         .fault = drm_gem_shmem_fault,
 576         .open = drm_gem_shmem_vm_open,
 577         .close = drm_gem_shmem_vm_close,
 578 };
 579 EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
 580
 581 /**
 582  * drm_gem_shmem_mmap - Memory-map a shmem GEM object
 583  * @shmem: shmem GEM object
 584  * @vma: VMA for the area to be mapped
 585  *
 586  * This function implements an augmented version of the GEM DRM file mmap
 587  * operation for shmem objects.
 588  *
 589  * Returns:
 590  * 0 on success or a negative error code on failure.
 591  */
 592 int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct *vma)
 593 {
 594         struct drm_gem_object *obj = &shmem->base;
 595         int ret;
 596
 597         if (obj->import_attach) {
 598                 /* Reset both vm_ops and vm_private_data, so we don't end up with
 599                  * vm_ops pointing to our implementation if the dma-buf backend
 600                  * doesn't set those fields.
 601                  */
 602                 vma->vm_private_data = NULL;
 603                 vma->vm_ops = NULL;
 604
 605                 ret = dma_buf_mmap(obj->dma_buf, vma, 0);
 606
 607                 /* Drop the reference drm_gem_mmap_obj() acquired.*/
 608                 if (!ret)
 609                         drm_gem_object_put(obj);
 610
 611                 return ret;
 612         }
 613
 614         dma_resv_lock(shmem->base.resv, NULL);
 615         ret = drm_gem_shmem_get_pages(shmem);
 616         dma_resv_unlock(shmem->base.resv);
 617
 618         if (ret)
 619                 return ret;
 620
 621         vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
 622         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 623         if (shmem->map_wc)
 624                 vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 625
 626         return 0;
 627 }
 628 EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
 629
 630 /**
 631  * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
 632  * @shmem: shmem GEM object
 633  * @p: DRM printer
 634  * @indent: Tab indentation level
 635  */
 636 void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
 637                               struct drm_printer *p, unsigned int indent)
 638 {
 639         if (shmem->base.import_attach)
 640                 return;
 641
 642         drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
 643         drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
 644         drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
 645 }
 646 EXPORT_SYMBOL(drm_gem_shmem_print_info);
 647
 648 /**
 649  * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
 650  *                              pages for a shmem GEM object
 651  * @shmem: shmem GEM object
 652  *
 653  * This function exports a scatter/gather table suitable for PRIME usage by
 654  * calling the standard DMA mapping API.
 655  *
 656  * Drivers who need to acquire an scatter/gather table for objects need to call
 657  * drm_gem_shmem_get_pages_sgt() instead.
 658  *
 659  * Returns:
 660  * A pointer to the scatter/gather table of pinned pages or error pointer on failure.
 661  */
 662 struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem)
 663 {
 664         struct drm_gem_object *obj = &shmem->base;
 665
 666         drm_WARN_ON(obj->dev, obj->import_attach);
 667
 668         return drm_prime_pages_to_sg(obj->dev, shmem->pages, obj->size >> PAGE_SHIFT);
 669 }
 670 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
 671
 672 static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_object *shmem)
 673 {
 674         struct drm_gem_object *obj = &shmem->base;
 675         int ret;
 676         struct sg_table *sgt;
 677
 678         if (shmem->sgt)
 679                 return shmem->sgt;
 680
 681         drm_WARN_ON(obj->dev, obj->import_attach);
 682
 683         ret = drm_gem_shmem_get_pages(shmem);
 684         if (ret)
 685                 return ERR_PTR(ret);
 686
 687         sgt = drm_gem_shmem_get_sg_table(shmem);
 688         if (IS_ERR(sgt)) {
 689                 ret = PTR_ERR(sgt);
 690                 goto err_put_pages;
 691         }
 692         /* Map the pages for use by the h/w. */
 693         ret = dma_map_sgtable(obj->dev->dev, sgt, DMA_BIDIRECTIONAL, 0);
 694         if (ret)
 695                 goto err_free_sgt;
 696
 697         shmem->sgt = sgt;
 698
 699         return sgt;
 700
 701 err_free_sgt:
 702         sg_free_table(sgt);
 703         kfree(sgt);
 704 err_put_pages:
 705         drm_gem_shmem_put_pages(shmem);
 706         return ERR_PTR(ret);
 707 }
 708
 709 /**
 710  * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
 711  *                               scatter/gather table for a shmem GEM object.
 712  * @shmem: shmem GEM object
 713  *
 714  * This function returns a scatter/gather table suitable for driver usage. If
 715  * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
 716  * table created.
 717  *
 718  * This is the main function for drivers to get at backing storage, and it hides
 719  * and difference between dma-buf imported and natively allocated objects.
 720  * drm_gem_shmem_get_sg_table() should not be directly called by drivers.
 721  *
 722  * Returns:
 723  * A pointer to the scatter/gather table of pinned pages or errno on failure.
 724  */
 725 struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
 726 {
 727         int ret;
 728         struct sg_table *sgt;
 729
 730         ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
 731         if (ret)
 732                 return ERR_PTR(ret);
 733         sgt = drm_gem_shmem_get_pages_sgt_locked(shmem);
 734         dma_resv_unlock(shmem->base.resv);
 735
 736         return sgt;
 737 }
 738 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);
 739
 740 /**
 741  * drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
 742  *                 another driver's scatter/gather table of pinned pages
 743  * @dev: Device to import into
 744  * @attach: DMA-BUF attachment
 745  * @sgt: Scatter/gather table of pinned pages
 746  *
 747  * This function imports a scatter/gather table exported via DMA-BUF by
 748  * another driver. Drivers that use the shmem helpers should set this as their
 749  * &drm_driver.gem_prime_import_sg_table callback.
 750  *
 751  * Returns:
 752  * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
 753  * error code on failure.
 754  */
 755 struct drm_gem_object *
 756 drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
 757                                     struct dma_buf_attachment *attach,
 758                                     struct sg_table *sgt)
 759 {
 760         size_t size = PAGE_ALIGN(attach->dmabuf->size);
 761         struct drm_gem_shmem_object *shmem;
 762
 763         shmem = __drm_gem_shmem_create(dev, size, true);
 764         if (IS_ERR(shmem))
 765                 return ERR_CAST(shmem);
 766
 767         shmem->sgt = sgt;
 768
 769         drm_dbg_prime(dev, "size = %zu\n", size);
 770
 771         return &shmem->base;
 772 }
 773 EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);
 774
 775 MODULE_DESCRIPTION("DRM SHMEM memory-management helpers");
 776 MODULE_IMPORT_NS(DMA_BUF);
 777 MODULE_LICENSE("GPL v2");