root/drivers/gpu/drm/drm_ioctl.c

DEFINITIONS

1. drm_getunique
2. drm_unset_busid
3. drm_set_busid
4. drm_getclient
5. drm_getstats
6. drm_getcap
7. drm_setclientcap
8. drm_setversion
9. drm_noop
10. drm_invalid_op
11. drm_copy_field
12. drm_version
13. drm_ioctl_permit
14. drm_ioctl_kernel
15. drm_ioctl
16. drm_ioctl_flags

   1 /*
   2  * Created: Fri Jan  8 09:01:26 1999 by faith@valinux.com
   3  *
   4  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
   5  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
   6  * All Rights Reserved.
   7  *
   8  * Author Rickard E. (Rik) Faith <faith@valinux.com>
   9  * Author Gareth Hughes <gareth@valinux.com>
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a
  12  * copy of this software and associated documentation files (the "Software"),
  13  * to deal in the Software without restriction, including without limitation
  14  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  15  * and/or sell copies of the Software, and to permit persons to whom the
  16  * Software is furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice (including the next
  19  * paragraph) shall be included in all copies or substantial portions of the
  20  * Software.
  21  *
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  25  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  26  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  27  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  28  * OTHER DEALINGS IN THE SOFTWARE.
  29  */
  30 
  31 #include <linux/export.h>
  32 #include <linux/nospec.h>
  33 #include <linux/pci.h>
  34 #include <linux/uaccess.h>
  35 
  36 #include <drm/drm_agpsupport.h>
  37 #include <drm/drm_auth.h>
  38 #include <drm/drm_crtc.h>
  39 #include <drm/drm_drv.h>
  40 #include <drm/drm_file.h>
  41 #include <drm/drm_ioctl.h>
  42 #include <drm/drm_print.h>
  43 
  44 #include "drm_crtc_internal.h"
  45 #include "drm_internal.h"
  46 #include "drm_legacy.h"
  47 
  48 /**
  49  * DOC: getunique and setversion story
  50  *
  51  * BEWARE THE DRAGONS! MIND THE TRAPDOORS!
  52  *
  53  * In an attempt to warn anyone else who's trying to figure out what's going
  54  * on here, I'll try to summarize the story. First things first, let's clear up
  55  * the names, because the kernel internals, libdrm and the ioctls are all named
  56  * differently:
  57  *
  58  *  - GET_UNIQUE ioctl, implemented by drm_getunique is wrapped up in libdrm
  59  *    through the drmGetBusid function.
  60  *  - The libdrm drmSetBusid function is backed by the SET_UNIQUE ioctl. All
  61  *    that code is nerved in the kernel with drm_invalid_op().
  62  *  - The internal set_busid kernel functions and driver callbacks are
  63  *    exclusively use by the SET_VERSION ioctl, because only drm 1.0 (which is
  64  *    nerved) allowed userspace to set the busid through the above ioctl.
  65  *  - Other ioctls and functions involved are named consistently.
  66  *
  67  * For anyone wondering what's the difference between drm 1.1 and 1.4: Correctly
  68  * handling pci domains in the busid on ppc. Doing this correctly was only
  69  * implemented in libdrm in 2010, hence can't be nerved yet. No one knows what's
  70  * special with drm 1.2 and 1.3.
  71  *
  72  * Now the actual horror story of how device lookup in drm works. At large,
  73  * there's 2 different ways, either by busid, or by device driver name.
  74  *
  75  * Opening by busid is fairly simple:
  76  *
  77  * 1. First call SET_VERSION to make sure pci domains are handled properly. As a
  78  *    side-effect this fills out the unique name in the master structure.
  79  * 2. Call GET_UNIQUE to read out the unique name from the master structure,
  80  *    which matches the busid thanks to step 1. If it doesn't, proceed to try
  81  *    the next device node.
  82  *
  83  * Opening by name is slightly different:
  84  *
  85  * 1. Directly call VERSION to get the version and to match against the driver
  86  *    name returned by that ioctl. Note that SET_VERSION is not called, which
  87  *    means the the unique name for the master node just opening is _not_ filled
  88  *    out. This despite that with current drm device nodes are always bound to
  89  *    one device, and can't be runtime assigned like with drm 1.0.
  90  * 2. Match driver name. If it mismatches, proceed to the next device node.
  91  * 3. Call GET_UNIQUE, and check whether the unique name has length zero (by
  92  *    checking that the first byte in the string is 0). If that's not the case
  93  *    libdrm skips and proceeds to the next device node. Probably this is just
  94  *    copypasta from drm 1.0 times where a set unique name meant that the driver
  95  *    was in use already, but that's just conjecture.
  96  *
  97  * Long story short: To keep the open by name logic working, GET_UNIQUE must
  98  * _not_ return a unique string when SET_VERSION hasn't been called yet,
  99  * otherwise libdrm breaks. Even when that unique string can't ever change, and
 100  * is totally irrelevant for actually opening the device because runtime
 101  * assignable device instances were only support in drm 1.0, which is long dead.
 102  * But the libdrm code in drmOpenByName somehow survived, hence this can't be
 103  * broken.
 104  */
 105 
 106 /*
 107  * Get the bus id.
 108  *
 109  * \param inode device inode.
 110  * \param file_priv DRM file private.
 111  * \param cmd command.
 112  * \param arg user argument, pointing to a drm_unique structure.
 113  * \return zero on success or a negative number on failure.
 114  *
 115  * Copies the bus id from drm_device::unique into user space.
 116  */
 117 int drm_getunique(struct drm_device *dev, void *data,
 118                   struct drm_file *file_priv)
 119 {
 120         struct drm_unique *u = data;
 121         struct drm_master *master = file_priv->master;
 122 
 123         mutex_lock(&master->dev->master_mutex);
 124         if (u->unique_len >= master->unique_len) {
 125                 if (copy_to_user(u->unique, master->unique, master->unique_len)) {
 126                         mutex_unlock(&master->dev->master_mutex);
 127                         return -EFAULT;
 128                 }
 129         }
 130         u->unique_len = master->unique_len;
 131         mutex_unlock(&master->dev->master_mutex);
 132 
 133         return 0;
 134 }
 135 
 136 static void
 137 drm_unset_busid(struct drm_device *dev,
 138                 struct drm_master *master)
 139 {
 140         kfree(master->unique);
 141         master->unique = NULL;
 142         master->unique_len = 0;
 143 }
 144 
 145 static int drm_set_busid(struct drm_device *dev, struct drm_file *file_priv)
 146 {
 147         struct drm_master *master = file_priv->master;
 148         int ret;
 149 
 150         if (master->unique != NULL)
 151                 drm_unset_busid(dev, master);
 152 
 153         if (dev->dev && dev_is_pci(dev->dev)) {
 154                 ret = drm_pci_set_busid(dev, master);
 155                 if (ret) {
 156                         drm_unset_busid(dev, master);
 157                         return ret;
 158                 }
 159         } else {
 160                 WARN_ON(!dev->unique);
 161                 master->unique = kstrdup(dev->unique, GFP_KERNEL);
 162                 if (master->unique)
 163                         master->unique_len = strlen(dev->unique);
 164         }
 165 
 166         return 0;
 167 }
 168 
 169 /*
 170  * Get client information.
 171  *
 172  * \param inode device inode.
 173  * \param file_priv DRM file private.
 174  * \param cmd command.
 175  * \param arg user argument, pointing to a drm_client structure.
 176  *
 177  * \return zero on success or a negative number on failure.
 178  *
 179  * Searches for the client with the specified index and copies its information
 180  * into userspace
 181  */
 182 int drm_getclient(struct drm_device *dev, void *data,
 183                   struct drm_file *file_priv)
 184 {
 185         struct drm_client *client = data;
 186 
 187         /*
 188          * Hollowed-out getclient ioctl to keep some dead old drm tests/tools
 189          * not breaking completely. Userspace tools stop enumerating one they
 190          * get -EINVAL, hence this is the return value we need to hand back for
 191          * no clients tracked.
 192          *
 193          * Unfortunately some clients (*cough* libva *cough*) use this in a fun
 194          * attempt to figure out whether they're authenticated or not. Since
 195          * that's the only thing they care about, give it to the directly
 196          * instead of walking one giant list.
 197          */
 198         if (client->idx == 0) {
 199                 client->auth = file_priv->authenticated;
 200                 client->pid = task_pid_vnr(current);
 201                 client->uid = overflowuid;
 202                 client->magic = 0;
 203                 client->iocs = 0;
 204 
 205                 return 0;
 206         } else {
 207                 return -EINVAL;
 208         }
 209 }
 210 
 211 /*
 212  * Get statistics information.
 213  *
 214  * \param inode device inode.
 215  * \param file_priv DRM file private.
 216  * \param cmd command.
 217  * \param arg user argument, pointing to a drm_stats structure.
 218  *
 219  * \return zero on success or a negative number on failure.
 220  */
 221 static int drm_getstats(struct drm_device *dev, void *data,
 222                  struct drm_file *file_priv)
 223 {
 224         struct drm_stats *stats = data;
 225 
 226         /* Clear stats to prevent userspace from eating its stack garbage. */
 227         memset(stats, 0, sizeof(*stats));
 228 
 229         return 0;
 230 }
 231 
 232 /*
 233  * Get device/driver capabilities
 234  */
 235 static int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
 236 {
 237         struct drm_get_cap *req = data;
 238         struct drm_crtc *crtc;
 239 
 240         req->value = 0;
 241 
 242         /* Only some caps make sense with UMS/render-only drivers. */
 243         switch (req->capability) {
 244         case DRM_CAP_TIMESTAMP_MONOTONIC:
 245                 req->value = 1;
 246                 return 0;
 247         case DRM_CAP_PRIME:
 248                 req->value |= dev->driver->prime_fd_to_handle ? DRM_PRIME_CAP_IMPORT : 0;
 249                 req->value |= dev->driver->prime_handle_to_fd ? DRM_PRIME_CAP_EXPORT : 0;
 250                 return 0;
 251         case DRM_CAP_SYNCOBJ:
 252                 req->value = drm_core_check_feature(dev, DRIVER_SYNCOBJ);
 253                 return 0;
 254         case DRM_CAP_SYNCOBJ_TIMELINE:
 255                 req->value = drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE);
 256                 return 0;
 257         }
 258 
 259         /* Other caps only work with KMS drivers */
 260         if (!drm_core_check_feature(dev, DRIVER_MODESET))
 261                 return -EOPNOTSUPP;
 262 
 263         switch (req->capability) {
 264         case DRM_CAP_DUMB_BUFFER:
 265                 if (dev->driver->dumb_create)
 266                         req->value = 1;
 267                 break;
 268         case DRM_CAP_VBLANK_HIGH_CRTC:
 269                 req->value = 1;
 270                 break;
 271         case DRM_CAP_DUMB_PREFERRED_DEPTH:
 272                 req->value = dev->mode_config.preferred_depth;
 273                 break;
 274         case DRM_CAP_DUMB_PREFER_SHADOW:
 275                 req->value = dev->mode_config.prefer_shadow;
 276                 break;
 277         case DRM_CAP_ASYNC_PAGE_FLIP:
 278                 req->value = dev->mode_config.async_page_flip;
 279                 break;
 280         case DRM_CAP_PAGE_FLIP_TARGET:
 281                 req->value = 1;
 282                 drm_for_each_crtc(crtc, dev) {
 283                         if (!crtc->funcs->page_flip_target)
 284                                 req->value = 0;
 285                 }
 286                 break;
 287         case DRM_CAP_CURSOR_WIDTH:
 288                 if (dev->mode_config.cursor_width)
 289                         req->value = dev->mode_config.cursor_width;
 290                 else
 291                         req->value = 64;
 292                 break;
 293         case DRM_CAP_CURSOR_HEIGHT:
 294                 if (dev->mode_config.cursor_height)
 295                         req->value = dev->mode_config.cursor_height;
 296                 else
 297                         req->value = 64;
 298                 break;
 299         case DRM_CAP_ADDFB2_MODIFIERS:
 300                 req->value = dev->mode_config.allow_fb_modifiers;
 301                 break;
 302         case DRM_CAP_CRTC_IN_VBLANK_EVENT:
 303                 req->value = 1;
 304                 break;
 305         default:
 306                 return -EINVAL;
 307         }
 308         return 0;
 309 }
 310 
 311 /*
 312  * Set device/driver capabilities
 313  */
 314 static int
 315 drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
 316 {
 317         struct drm_set_client_cap *req = data;
 318 
 319         /* No render-only settable capabilities for now */
 320 
 321         /* Below caps that only works with KMS drivers */
 322         if (!drm_core_check_feature(dev, DRIVER_MODESET))
 323                 return -EOPNOTSUPP;
 324 
 325         switch (req->capability) {
 326         case DRM_CLIENT_CAP_STEREO_3D:
 327                 if (req->value > 1)
 328                         return -EINVAL;
 329                 file_priv->stereo_allowed = req->value;
 330                 break;
 331         case DRM_CLIENT_CAP_UNIVERSAL_PLANES:
 332                 if (req->value > 1)
 333                         return -EINVAL;
 334                 file_priv->universal_planes = req->value;
 335                 break;
 336         case DRM_CLIENT_CAP_ATOMIC:
 337                 if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
 338                         return -EOPNOTSUPP;
 339                 /* The modesetting DDX has a totally broken idea of atomic. */
 340                 if (current->comm[0] == 'X' && req->value == 1) {
 341                         pr_info("broken atomic modeset userspace detected, disabling atomic\n");
 342                         return -EOPNOTSUPP;
 343                 }
 344                 if (req->value > 2)
 345                         return -EINVAL;
 346                 file_priv->atomic = req->value;
 347                 file_priv->universal_planes = req->value;
 348                 /*
 349                  * No atomic user-space blows up on aspect ratio mode bits.
 350                  */
 351                 file_priv->aspect_ratio_allowed = req->value;
 352                 break;
 353         case DRM_CLIENT_CAP_ASPECT_RATIO:
 354                 if (req->value > 1)
 355                         return -EINVAL;
 356                 file_priv->aspect_ratio_allowed = req->value;
 357                 break;
 358         case DRM_CLIENT_CAP_WRITEBACK_CONNECTORS:
 359                 if (!file_priv->atomic)
 360                         return -EINVAL;
 361                 if (req->value > 1)
 362                         return -EINVAL;
 363                 file_priv->writeback_connectors = req->value;
 364                 break;
 365         default:
 366                 return -EINVAL;
 367         }
 368 
 369         return 0;
 370 }
 371 
 372 /*
 373  * Setversion ioctl.
 374  *
 375  * \param inode device inode.
 376  * \param file_priv DRM file private.
 377  * \param cmd command.
 378  * \param arg user argument, pointing to a drm_lock structure.
 379  * \return zero on success or negative number on failure.
 380  *
 381  * Sets the requested interface version
 382  */
 383 static int drm_setversion(struct drm_device *dev, void *data, struct drm_file *file_priv)
 384 {
 385         struct drm_set_version *sv = data;
 386         int if_version, retcode = 0;
 387 
 388         mutex_lock(&dev->master_mutex);
 389         if (sv->drm_di_major != -1) {
 390                 if (sv->drm_di_major != DRM_IF_MAJOR ||
 391                     sv->drm_di_minor < 0 || sv->drm_di_minor > DRM_IF_MINOR) {
 392                         retcode = -EINVAL;
 393                         goto done;
 394                 }
 395                 if_version = DRM_IF_VERSION(sv->drm_di_major,
 396                                             sv->drm_di_minor);
 397                 dev->if_version = max(if_version, dev->if_version);
 398                 if (sv->drm_di_minor >= 1) {
 399                         /*
 400                          * Version 1.1 includes tying of DRM to specific device
 401                          * Version 1.4 has proper PCI domain support
 402                          */
 403                         retcode = drm_set_busid(dev, file_priv);
 404                         if (retcode)
 405                                 goto done;
 406                 }
 407         }
 408 
 409         if (sv->drm_dd_major != -1) {
 410                 if (sv->drm_dd_major != dev->driver->major ||
 411                     sv->drm_dd_minor < 0 || sv->drm_dd_minor >
 412                     dev->driver->minor) {
 413                         retcode = -EINVAL;
 414                         goto done;
 415                 }
 416         }
 417 
 418 done:
 419         sv->drm_di_major = DRM_IF_MAJOR;
 420         sv->drm_di_minor = DRM_IF_MINOR;
 421         sv->drm_dd_major = dev->driver->major;
 422         sv->drm_dd_minor = dev->driver->minor;
 423         mutex_unlock(&dev->master_mutex);
 424 
 425         return retcode;
 426 }
 427 
 428 /**
 429  * drm_noop - DRM no-op ioctl implemntation
 430  * @dev: DRM device for the ioctl
 431  * @data: data pointer for the ioctl
 432  * @file_priv: DRM file for the ioctl call
 433  *
 434  * This no-op implementation for drm ioctls is useful for deprecated
 435  * functionality where we can't return a failure code because existing userspace
 436  * checks the result of the ioctl, but doesn't care about the action.
 437  *
 438  * Always returns successfully with 0.
 439  */
 440 int drm_noop(struct drm_device *dev, void *data,
 441              struct drm_file *file_priv)
 442 {
 443         DRM_DEBUG("\n");
 444         return 0;
 445 }
 446 EXPORT_SYMBOL(drm_noop);
 447 
 448 /**
 449  * drm_invalid_op - DRM invalid ioctl implemntation
 450  * @dev: DRM device for the ioctl
 451  * @data: data pointer for the ioctl
 452  * @file_priv: DRM file for the ioctl call
 453  *
 454  * This no-op implementation for drm ioctls is useful for deprecated
 455  * functionality where we really don't want to allow userspace to call the ioctl
 456  * any more. This is the case for old ums interfaces for drivers that
 457  * transitioned to kms gradually and so kept the old legacy tables around. This
 458  * only applies to radeon and i915 kms drivers, other drivers shouldn't need to
 459  * use this function.
 460  *
 461  * Always fails with a return value of -EINVAL.
 462  */
 463 int drm_invalid_op(struct drm_device *dev, void *data,
 464                    struct drm_file *file_priv)
 465 {
 466         return -EINVAL;
 467 }
 468 EXPORT_SYMBOL(drm_invalid_op);
 469 
 470 /*
 471  * Copy and IOCTL return string to user space
 472  */
 473 static int drm_copy_field(char __user *buf, size_t *buf_len, const char *value)
 474 {
 475         int len;
 476 
 477         /* don't overflow userbuf */
 478         len = strlen(value);
 479         if (len > *buf_len)
 480                 len = *buf_len;
 481 
 482         /* let userspace know exact length of driver value (which could be
 483          * larger than the userspace-supplied buffer) */
 484         *buf_len = strlen(value);
 485 
 486         /* finally, try filling in the userbuf */
 487         if (len && buf)
 488                 if (copy_to_user(buf, value, len))
 489                         return -EFAULT;
 490         return 0;
 491 }
 492 
 493 /*
 494  * Get version information
 495  *
 496  * \param inode device inode.
 497  * \param filp file pointer.
 498  * \param cmd command.
 499  * \param arg user argument, pointing to a drm_version structure.
 500  * \return zero on success or negative number on failure.
 501  *
 502  * Fills in the version information in \p arg.
 503  */
 504 int drm_version(struct drm_device *dev, void *data,
 505                        struct drm_file *file_priv)
 506 {
 507         struct drm_version *version = data;
 508         int err;
 509 
 510         version->version_major = dev->driver->major;
 511         version->version_minor = dev->driver->minor;
 512         version->version_patchlevel = dev->driver->patchlevel;
 513         err = drm_copy_field(version->name, &version->name_len,
 514                         dev->driver->name);
 515         if (!err)
 516                 err = drm_copy_field(version->date, &version->date_len,
 517                                 dev->driver->date);
 518         if (!err)
 519                 err = drm_copy_field(version->desc, &version->desc_len,
 520                                 dev->driver->desc);
 521 
 522         return err;
 523 }
 524 
 525 /**
 526  * drm_ioctl_permit - Check ioctl permissions against caller
 527  *
 528  * @flags: ioctl permission flags.
 529  * @file_priv: Pointer to struct drm_file identifying the caller.
 530  *
 531  * Checks whether the caller is allowed to run an ioctl with the
 532  * indicated permissions.
 533  *
 534  * Returns:
 535  * Zero if allowed, -EACCES otherwise.
 536  */
 537 int drm_ioctl_permit(u32 flags, struct drm_file *file_priv)
 538 {
 539         /* ROOT_ONLY is only for CAP_SYS_ADMIN */
 540         if (unlikely((flags & DRM_ROOT_ONLY) && !capable(CAP_SYS_ADMIN)))
 541                 return -EACCES;
 542 
 543         /* AUTH is only for authenticated or render client */
 544         if (unlikely((flags & DRM_AUTH) && !drm_is_render_client(file_priv) &&
 545                      !file_priv->authenticated))
 546                 return -EACCES;
 547 
 548         /* MASTER is only for master or control clients */
 549         if (unlikely((flags & DRM_MASTER) &&
 550                      !drm_is_current_master(file_priv)))
 551                 return -EACCES;
 552 
 553         /* Render clients must be explicitly allowed */
 554         if (unlikely(!(flags & DRM_RENDER_ALLOW) &&
 555                      drm_is_render_client(file_priv)))
 556                 return -EACCES;
 557 
 558         return 0;
 559 }
 560 EXPORT_SYMBOL(drm_ioctl_permit);
 561 
 562 #define DRM_IOCTL_DEF(ioctl, _func, _flags)     \
 563         [DRM_IOCTL_NR(ioctl)] = {               \
 564                 .cmd = ioctl,                   \
 565                 .func = _func,                  \
 566                 .flags = _flags,                \
 567                 .name = #ioctl                  \
 568         }
 569 
 570 #if IS_ENABLED(CONFIG_DRM_LEGACY)
 571 #define DRM_LEGACY_IOCTL_DEF(ioctl, _func, _flags)  DRM_IOCTL_DEF(ioctl, _func, _flags)
 572 #else
 573 #define DRM_LEGACY_IOCTL_DEF(ioctl, _func, _flags) DRM_IOCTL_DEF(ioctl, drm_invalid_op, _flags)
 574 #endif
 575 
 576 /* Ioctl table */
 577 static const struct drm_ioctl_desc drm_ioctls[] = {
 578         DRM_IOCTL_DEF(DRM_IOCTL_VERSION, drm_version, DRM_RENDER_ALLOW),
 579         DRM_IOCTL_DEF(DRM_IOCTL_GET_UNIQUE, drm_getunique, 0),
 580         DRM_IOCTL_DEF(DRM_IOCTL_GET_MAGIC, drm_getmagic, 0),
 581         DRM_IOCTL_DEF(DRM_IOCTL_IRQ_BUSID, drm_irq_by_busid, DRM_MASTER|DRM_ROOT_ONLY),
 582 
 583         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_GET_MAP, drm_legacy_getmap_ioctl, 0),
 584 
 585         DRM_IOCTL_DEF(DRM_IOCTL_GET_CLIENT, drm_getclient, 0),
 586         DRM_IOCTL_DEF(DRM_IOCTL_GET_STATS, drm_getstats, 0),
 587         DRM_IOCTL_DEF(DRM_IOCTL_GET_CAP, drm_getcap, DRM_RENDER_ALLOW),
 588         DRM_IOCTL_DEF(DRM_IOCTL_SET_CLIENT_CAP, drm_setclientcap, 0),
 589         DRM_IOCTL_DEF(DRM_IOCTL_SET_VERSION, drm_setversion, DRM_MASTER),
 590 
 591         DRM_IOCTL_DEF(DRM_IOCTL_SET_UNIQUE, drm_invalid_op, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 592         DRM_IOCTL_DEF(DRM_IOCTL_BLOCK, drm_noop, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 593         DRM_IOCTL_DEF(DRM_IOCTL_UNBLOCK, drm_noop, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 594         DRM_IOCTL_DEF(DRM_IOCTL_AUTH_MAGIC, drm_authmagic, DRM_MASTER),
 595 
 596         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_ADD_MAP, drm_legacy_addmap_ioctl, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 597         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_RM_MAP, drm_legacy_rmmap_ioctl, DRM_AUTH),
 598 
 599         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_SET_SAREA_CTX, drm_legacy_setsareactx, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 600         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_GET_SAREA_CTX, drm_legacy_getsareactx, DRM_AUTH),
 601 
 602         DRM_IOCTL_DEF(DRM_IOCTL_SET_MASTER, drm_setmaster_ioctl, DRM_ROOT_ONLY),
 603         DRM_IOCTL_DEF(DRM_IOCTL_DROP_MASTER, drm_dropmaster_ioctl, DRM_ROOT_ONLY),
 604 
 605         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_ADD_CTX, drm_legacy_addctx, DRM_AUTH|DRM_ROOT_ONLY),
 606         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_RM_CTX, drm_legacy_rmctx, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 607         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_MOD_CTX, drm_noop, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 608         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_GET_CTX, drm_legacy_getctx, DRM_AUTH),
 609         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_SWITCH_CTX, drm_legacy_switchctx, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 610         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_NEW_CTX, drm_legacy_newctx, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 611         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_RES_CTX, drm_legacy_resctx, DRM_AUTH),
 612 
 613         DRM_IOCTL_DEF(DRM_IOCTL_ADD_DRAW, drm_noop, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 614         DRM_IOCTL_DEF(DRM_IOCTL_RM_DRAW, drm_noop, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 615 
 616         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_LOCK, drm_legacy_lock, DRM_AUTH),
 617         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_UNLOCK, drm_legacy_unlock, DRM_AUTH),
 618 
 619         DRM_IOCTL_DEF(DRM_IOCTL_FINISH, drm_noop, DRM_AUTH),
 620 
 621         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_ADD_BUFS, drm_legacy_addbufs, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 622         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_MARK_BUFS, drm_legacy_markbufs, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 623         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_INFO_BUFS, drm_legacy_infobufs, DRM_AUTH),
 624         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_MAP_BUFS, drm_legacy_mapbufs, DRM_AUTH),
 625         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_FREE_BUFS, drm_legacy_freebufs, DRM_AUTH),
 626         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_DMA, drm_legacy_dma_ioctl, DRM_AUTH),
 627         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_CONTROL, drm_legacy_irq_control, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 628 
 629 #if IS_ENABLED(CONFIG_AGP)
 630         DRM_IOCTL_DEF(DRM_IOCTL_AGP_ACQUIRE, drm_agp_acquire_ioctl, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 631         DRM_IOCTL_DEF(DRM_IOCTL_AGP_RELEASE, drm_agp_release_ioctl, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 632         DRM_IOCTL_DEF(DRM_IOCTL_AGP_ENABLE, drm_agp_enable_ioctl, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 633         DRM_IOCTL_DEF(DRM_IOCTL_AGP_INFO, drm_agp_info_ioctl, DRM_AUTH),
 634         DRM_IOCTL_DEF(DRM_IOCTL_AGP_ALLOC, drm_agp_alloc_ioctl, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 635         DRM_IOCTL_DEF(DRM_IOCTL_AGP_FREE, drm_agp_free_ioctl, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 636         DRM_IOCTL_DEF(DRM_IOCTL_AGP_BIND, drm_agp_bind_ioctl, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 637         DRM_IOCTL_DEF(DRM_IOCTL_AGP_UNBIND, drm_agp_unbind_ioctl, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 638 #endif
 639 
 640         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_SG_ALLOC, drm_legacy_sg_alloc, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 641         DRM_LEGACY_IOCTL_DEF(DRM_IOCTL_SG_FREE, drm_legacy_sg_free, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 642 
 643         DRM_IOCTL_DEF(DRM_IOCTL_WAIT_VBLANK, drm_wait_vblank_ioctl, DRM_UNLOCKED),
 644 
 645         DRM_IOCTL_DEF(DRM_IOCTL_MODESET_CTL, drm_legacy_modeset_ctl_ioctl, 0),
 646 
 647         DRM_IOCTL_DEF(DRM_IOCTL_UPDATE_DRAW, drm_noop, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 648 
 649         DRM_IOCTL_DEF(DRM_IOCTL_GEM_CLOSE, drm_gem_close_ioctl, DRM_RENDER_ALLOW),
 650         DRM_IOCTL_DEF(DRM_IOCTL_GEM_FLINK, drm_gem_flink_ioctl, DRM_AUTH),
 651         DRM_IOCTL_DEF(DRM_IOCTL_GEM_OPEN, drm_gem_open_ioctl, DRM_AUTH),
 652 
 653         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETRESOURCES, drm_mode_getresources, 0),
 654 
 655         DRM_IOCTL_DEF(DRM_IOCTL_PRIME_HANDLE_TO_FD, drm_prime_handle_to_fd_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
 656         DRM_IOCTL_DEF(DRM_IOCTL_PRIME_FD_TO_HANDLE, drm_prime_fd_to_handle_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
 657 
 658         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETPLANERESOURCES, drm_mode_getplane_res, 0),
 659         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETCRTC, drm_mode_getcrtc, 0),
 660         DRM_IOCTL_DEF(DRM_IOCTL_MODE_SETCRTC, drm_mode_setcrtc, DRM_MASTER),
 661         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETPLANE, drm_mode_getplane, 0),
 662         DRM_IOCTL_DEF(DRM_IOCTL_MODE_SETPLANE, drm_mode_setplane, DRM_MASTER),
 663         DRM_IOCTL_DEF(DRM_IOCTL_MODE_CURSOR, drm_mode_cursor_ioctl, DRM_MASTER),
 664         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETGAMMA, drm_mode_gamma_get_ioctl, 0),
 665         DRM_IOCTL_DEF(DRM_IOCTL_MODE_SETGAMMA, drm_mode_gamma_set_ioctl, DRM_MASTER),
 666         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETENCODER, drm_mode_getencoder, 0),
 667         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETCONNECTOR, drm_mode_getconnector, 0),
 668         DRM_IOCTL_DEF(DRM_IOCTL_MODE_ATTACHMODE, drm_noop, DRM_MASTER),
 669         DRM_IOCTL_DEF(DRM_IOCTL_MODE_DETACHMODE, drm_noop, DRM_MASTER),
 670         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETPROPERTY, drm_mode_getproperty_ioctl, 0),
 671         DRM_IOCTL_DEF(DRM_IOCTL_MODE_SETPROPERTY, drm_connector_property_set_ioctl, DRM_MASTER),
 672         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETPROPBLOB, drm_mode_getblob_ioctl, 0),
 673         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETFB, drm_mode_getfb, 0),
 674         DRM_IOCTL_DEF(DRM_IOCTL_MODE_ADDFB, drm_mode_addfb_ioctl, 0),
 675         DRM_IOCTL_DEF(DRM_IOCTL_MODE_ADDFB2, drm_mode_addfb2_ioctl, 0),
 676         DRM_IOCTL_DEF(DRM_IOCTL_MODE_RMFB, drm_mode_rmfb_ioctl, 0),
 677         DRM_IOCTL_DEF(DRM_IOCTL_MODE_PAGE_FLIP, drm_mode_page_flip_ioctl, DRM_MASTER),
 678         DRM_IOCTL_DEF(DRM_IOCTL_MODE_DIRTYFB, drm_mode_dirtyfb_ioctl, DRM_MASTER),
 679         DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_DUMB, drm_mode_create_dumb_ioctl, 0),
 680         DRM_IOCTL_DEF(DRM_IOCTL_MODE_MAP_DUMB, drm_mode_mmap_dumb_ioctl, 0),
 681         DRM_IOCTL_DEF(DRM_IOCTL_MODE_DESTROY_DUMB, drm_mode_destroy_dumb_ioctl, 0),
 682         DRM_IOCTL_DEF(DRM_IOCTL_MODE_OBJ_GETPROPERTIES, drm_mode_obj_get_properties_ioctl, 0),
 683         DRM_IOCTL_DEF(DRM_IOCTL_MODE_OBJ_SETPROPERTY, drm_mode_obj_set_property_ioctl, DRM_MASTER),
 684         DRM_IOCTL_DEF(DRM_IOCTL_MODE_CURSOR2, drm_mode_cursor2_ioctl, DRM_MASTER),
 685         DRM_IOCTL_DEF(DRM_IOCTL_MODE_ATOMIC, drm_mode_atomic_ioctl, DRM_MASTER),
 686         DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATEPROPBLOB, drm_mode_createblob_ioctl, 0),
 687         DRM_IOCTL_DEF(DRM_IOCTL_MODE_DESTROYPROPBLOB, drm_mode_destroyblob_ioctl, 0),
 688 
 689         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_CREATE, drm_syncobj_create_ioctl,
 690                       DRM_RENDER_ALLOW),
 691         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_DESTROY, drm_syncobj_destroy_ioctl,
 692                       DRM_RENDER_ALLOW),
 693         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD, drm_syncobj_handle_to_fd_ioctl,
 694                       DRM_RENDER_ALLOW),
 695         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE, drm_syncobj_fd_to_handle_ioctl,
 696                       DRM_RENDER_ALLOW),
 697         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_TRANSFER, drm_syncobj_transfer_ioctl,
 698                       DRM_RENDER_ALLOW),
 699         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_WAIT, drm_syncobj_wait_ioctl,
 700                       DRM_RENDER_ALLOW),
 701         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_TIMELINE_WAIT, drm_syncobj_timeline_wait_ioctl,
 702                       DRM_RENDER_ALLOW),
 703         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_RESET, drm_syncobj_reset_ioctl,
 704                       DRM_RENDER_ALLOW),
 705         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_SIGNAL, drm_syncobj_signal_ioctl,
 706                       DRM_RENDER_ALLOW),
 707         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL, drm_syncobj_timeline_signal_ioctl,
 708                       DRM_RENDER_ALLOW),
 709         DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_QUERY, drm_syncobj_query_ioctl,
 710                       DRM_RENDER_ALLOW),
 711         DRM_IOCTL_DEF(DRM_IOCTL_CRTC_GET_SEQUENCE, drm_crtc_get_sequence_ioctl, 0),
 712         DRM_IOCTL_DEF(DRM_IOCTL_CRTC_QUEUE_SEQUENCE, drm_crtc_queue_sequence_ioctl, 0),
 713         DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_LEASE, drm_mode_create_lease_ioctl, DRM_MASTER),
 714         DRM_IOCTL_DEF(DRM_IOCTL_MODE_LIST_LESSEES, drm_mode_list_lessees_ioctl, DRM_MASTER),
 715         DRM_IOCTL_DEF(DRM_IOCTL_MODE_GET_LEASE, drm_mode_get_lease_ioctl, DRM_MASTER),
 716         DRM_IOCTL_DEF(DRM_IOCTL_MODE_REVOKE_LEASE, drm_mode_revoke_lease_ioctl, DRM_MASTER),
 717 };
 718 
 719 #define DRM_CORE_IOCTL_COUNT    ARRAY_SIZE( drm_ioctls )
 720 
 721 /**
 722  * DOC: driver specific ioctls
 723  *
 724  * First things first, driver private IOCTLs should only be needed for drivers
 725  * supporting rendering. Kernel modesetting is all standardized, and extended
 726  * through properties. There are a few exceptions in some existing drivers,
 727  * which define IOCTL for use by the display DRM master, but they all predate
 728  * properties.
 729  *
 730  * Now if you do have a render driver you always have to support it through
 731  * driver private properties. There's a few steps needed to wire all the things
 732  * up.
 733  *
 734  * First you need to define the structure for your IOCTL in your driver private
 735  * UAPI header in ``include/uapi/drm/my_driver_drm.h``::
 736  *
 737  *     struct my_driver_operation {
 738  *             u32 some_thing;
 739  *             u32 another_thing;
 740  *     };
 741  *
 742  * Please make sure that you follow all the best practices from
 743  * ``Documentation/ioctl/botching-up-ioctls.rst``. Note that drm_ioctl()
 744  * automatically zero-extends structures, hence make sure you can add more stuff
 745  * at the end, i.e. don't put a variable sized array there.
 746  *
 747  * Then you need to define your IOCTL number, using one of DRM_IO(), DRM_IOR(),
 748  * DRM_IOW() or DRM_IOWR(). It must start with the DRM_IOCTL\_ prefix::
 749  *
 750  *     ##define DRM_IOCTL_MY_DRIVER_OPERATION \
 751  *         DRM_IOW(DRM_COMMAND_BASE, struct my_driver_operation)
 752  *
 753  * DRM driver private IOCTL must be in the range from DRM_COMMAND_BASE to
 754  * DRM_COMMAND_END. Finally you need an array of &struct drm_ioctl_desc to wire
 755  * up the handlers and set the access rights::
 756  *
 757  *     static const struct drm_ioctl_desc my_driver_ioctls[] = {
 758  *         DRM_IOCTL_DEF_DRV(MY_DRIVER_OPERATION, my_driver_operation,
 759  *                 DRM_AUTH|DRM_RENDER_ALLOW),
 760  *     };
 761  *
 762  * And then assign this to the &drm_driver.ioctls field in your driver
 763  * structure.
 764  *
 765  * See the separate chapter on :ref:`file operations<drm_driver_fops>` for how
 766  * the driver-specific IOCTLs are wired up.
 767  */
 768 
 769 long drm_ioctl_kernel(struct file *file, drm_ioctl_t *func, void *kdata,
 770                       u32 flags)
 771 {
 772         struct drm_file *file_priv = file->private_data;
 773         struct drm_device *dev = file_priv->minor->dev;
 774         int retcode;
 775 
 776         if (drm_dev_is_unplugged(dev))
 777                 return -ENODEV;
 778 
 779         retcode = drm_ioctl_permit(flags, file_priv);
 780         if (unlikely(retcode))
 781                 return retcode;
 782 
 783         /* Enforce sane locking for modern driver ioctls. */
 784         if (likely(!drm_core_check_feature(dev, DRIVER_LEGACY)) ||
 785             (flags & DRM_UNLOCKED))
 786                 retcode = func(dev, kdata, file_priv);
 787         else {
 788                 mutex_lock(&drm_global_mutex);
 789                 retcode = func(dev, kdata, file_priv);
 790                 mutex_unlock(&drm_global_mutex);
 791         }
 792         return retcode;
 793 }
 794 EXPORT_SYMBOL(drm_ioctl_kernel);
 795 
 796 /**
 797  * drm_ioctl - ioctl callback implementation for DRM drivers
 798  * @filp: file this ioctl is called on
 799  * @cmd: ioctl cmd number
 800  * @arg: user argument
 801  *
 802  * Looks up the ioctl function in the DRM core and the driver dispatch table,
 803  * stored in &drm_driver.ioctls. It checks for necessary permission by calling
 804  * drm_ioctl_permit(), and dispatches to the respective function.
 805  *
 806  * Returns:
 807  * Zero on success, negative error code on failure.
 808  */
 809 long drm_ioctl(struct file *filp,
 810               unsigned int cmd, unsigned long arg)
 811 {
 812         struct drm_file *file_priv = filp->private_data;
 813         struct drm_device *dev;
 814         const struct drm_ioctl_desc *ioctl = NULL;
 815         drm_ioctl_t *func;
 816         unsigned int nr = DRM_IOCTL_NR(cmd);
 817         int retcode = -EINVAL;
 818         char stack_kdata[128];
 819         char *kdata = NULL;
 820         unsigned int in_size, out_size, drv_size, ksize;
 821         bool is_driver_ioctl;
 822 
 823         dev = file_priv->minor->dev;
 824 
 825         if (drm_dev_is_unplugged(dev))
 826                 return -ENODEV;
 827 
 828         is_driver_ioctl = nr >= DRM_COMMAND_BASE && nr < DRM_COMMAND_END;
 829 
 830         if (is_driver_ioctl) {
 831                 /* driver ioctl */
 832                 unsigned int index = nr - DRM_COMMAND_BASE;
 833 
 834                 if (index >= dev->driver->num_ioctls)
 835                         goto err_i1;
 836                 index = array_index_nospec(index, dev->driver->num_ioctls);
 837                 ioctl = &dev->driver->ioctls[index];
 838         } else {
 839                 /* core ioctl */
 840                 if (nr >= DRM_CORE_IOCTL_COUNT)
 841                         goto err_i1;
 842                 nr = array_index_nospec(nr, DRM_CORE_IOCTL_COUNT);
 843                 ioctl = &drm_ioctls[nr];
 844         }
 845 
 846         drv_size = _IOC_SIZE(ioctl->cmd);
 847         out_size = in_size = _IOC_SIZE(cmd);
 848         if ((cmd & ioctl->cmd & IOC_IN) == 0)
 849                 in_size = 0;
 850         if ((cmd & ioctl->cmd & IOC_OUT) == 0)
 851                 out_size = 0;
 852         ksize = max(max(in_size, out_size), drv_size);
 853 
 854         DRM_DEBUG("pid=%d, dev=0x%lx, auth=%d, %s\n",
 855                   task_pid_nr(current),
 856                   (long)old_encode_dev(file_priv->minor->kdev->devt),
 857                   file_priv->authenticated, ioctl->name);
 858 
 859         /* Do not trust userspace, use our own definition */
 860         func = ioctl->func;
 861 
 862         if (unlikely(!func)) {
 863                 DRM_DEBUG("no function\n");
 864                 retcode = -EINVAL;
 865                 goto err_i1;
 866         }
 867 
 868         if (ksize <= sizeof(stack_kdata)) {
 869                 kdata = stack_kdata;
 870         } else {
 871                 kdata = kmalloc(ksize, GFP_KERNEL);
 872                 if (!kdata) {
 873                         retcode = -ENOMEM;
 874                         goto err_i1;
 875                 }
 876         }
 877 
 878         if (copy_from_user(kdata, (void __user *)arg, in_size) != 0) {
 879                 retcode = -EFAULT;
 880                 goto err_i1;
 881         }
 882 
 883         if (ksize > in_size)
 884                 memset(kdata + in_size, 0, ksize - in_size);
 885 
 886         retcode = drm_ioctl_kernel(filp, func, kdata, ioctl->flags);
 887         if (copy_to_user((void __user *)arg, kdata, out_size) != 0)
 888                 retcode = -EFAULT;
 889 
 890       err_i1:
 891         if (!ioctl)
 892                 DRM_DEBUG("invalid ioctl: pid=%d, dev=0x%lx, auth=%d, cmd=0x%02x, nr=0x%02x\n",
 893                           task_pid_nr(current),
 894                           (long)old_encode_dev(file_priv->minor->kdev->devt),
 895                           file_priv->authenticated, cmd, nr);
 896 
 897         if (kdata != stack_kdata)
 898                 kfree(kdata);
 899         if (retcode)
 900                 DRM_DEBUG("pid=%d, ret = %d\n", task_pid_nr(current), retcode);
 901         return retcode;
 902 }
 903 EXPORT_SYMBOL(drm_ioctl);
 904 
 905 /**
 906  * drm_ioctl_flags - Check for core ioctl and return ioctl permission flags
 907  * @nr: ioctl number
 908  * @flags: where to return the ioctl permission flags
 909  *
 910  * This ioctl is only used by the vmwgfx driver to augment the access checks
 911  * done by the drm core and insofar a pretty decent layering violation. This
 912  * shouldn't be used by any drivers.
 913  *
 914  * Returns:
 915  * True if the @nr corresponds to a DRM core ioctl number, false otherwise.
 916  */
 917 bool drm_ioctl_flags(unsigned int nr, unsigned int *flags)
 918 {
 919         if (nr >= DRM_COMMAND_BASE && nr < DRM_COMMAND_END)
 920                 return false;
 921 
 922         if (nr >= DRM_CORE_IOCTL_COUNT)
 923                 return false;
 924         nr = array_index_nospec(nr, DRM_CORE_IOCTL_COUNT);
 925 
 926         *flags = drm_ioctls[nr].flags;
 927         return true;
 928 }
 929 EXPORT_SYMBOL(drm_ioctl_flags);