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