drivers/dma-buf/sw_sync.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Sync File validation framework
   4  *
   5  * Copyright (C) 2012 Google, Inc.
   6  */
   7
   8 #include <linux/file.h>
   9 #include <linux/fs.h>
  10 #include <linux/uaccess.h>
  11 #include <linux/slab.h>
  12 #include <linux/sync_file.h>
  13
  14 #include "sync_debug.h"
  15
  16 #define CREATE_TRACE_POINTS
  17 #include "sync_trace.h"
  18
  19 /*
  20  * SW SYNC validation framework
  21  *
  22  * A sync object driver that uses a 32bit counter to coordinate
  23  * synchronization.  Useful when there is no hardware primitive backing
  24  * the synchronization.
  25  *
  26  * To start the framework just open:
  27  *
  28  * <debugfs>/sync/sw_sync
  29  *
  30  * That will create a sync timeline, all fences created under this timeline
  31  * file descriptor will belong to the this timeline.
  32  *
  33  * The 'sw_sync' file can be opened many times as to create different
  34  * timelines.
  35  *
  36  * Fences can be created with SW_SYNC_IOC_CREATE_FENCE ioctl with struct
  37  * sw_sync_create_fence_data as parameter.
  38  *
  39  * To increment the timeline counter, SW_SYNC_IOC_INC ioctl should be used
  40  * with the increment as u32. This will update the last signaled value
  41  * from the timeline and signal any fence that has a seqno smaller or equal
  42  * to it.
  43  *
  44  * struct sw_sync_create_fence_data
  45  * @value:      the seqno to initialise the fence with
  46  * @name:       the name of the new sync point
  47  * @fence:      return the fd of the new sync_file with the created fence
  48  */
  49 struct sw_sync_create_fence_data {
  50         __u32   value;
  51         char    name[32];
  52         __s32   fence; /* fd of new fence */
  53 };
  54
  55 /**
  56  * struct sw_sync_get_deadline - get the deadline hint of a sw_sync fence
  57  * @deadline_ns: absolute time of the deadline
  58  * @pad:        must be zero
  59  * @fence_fd:   the sw_sync fence fd (in)
  60  *
  61  * Return the earliest deadline set on the fence.  The timebase for the
  62  * deadline is CLOCK_MONOTONIC (same as vblank).  If there is no deadline
  63  * set on the fence, this ioctl will return -ENOENT.
  64  */
  65 struct sw_sync_get_deadline {
  66         __u64   deadline_ns;
  67         __u32   pad;
  68         __s32   fence_fd;
  69 };
  70
  71 #define SW_SYNC_IOC_MAGIC       'W'
  72
  73 #define SW_SYNC_IOC_CREATE_FENCE        _IOWR(SW_SYNC_IOC_MAGIC, 0,\
  74                 struct sw_sync_create_fence_data)
  75
  76 #define SW_SYNC_IOC_INC                 _IOW(SW_SYNC_IOC_MAGIC, 1, __u32)
  77 #define SW_SYNC_GET_DEADLINE            _IOWR(SW_SYNC_IOC_MAGIC, 2, \
  78                 struct sw_sync_get_deadline)
  79
  80
  81 #define SW_SYNC_HAS_DEADLINE_BIT        DMA_FENCE_FLAG_USER_BITS
  82
  83 static const struct dma_fence_ops timeline_fence_ops;
  84
  85 static inline struct sync_pt *dma_fence_to_sync_pt(struct dma_fence *fence)
  86 {
  87         if (fence->ops != &timeline_fence_ops)
  88                 return NULL;
  89         return container_of(fence, struct sync_pt, base);
  90 }
  91
  92 /**
  93  * sync_timeline_create() - creates a sync object
  94  * @name:       sync_timeline name
  95  *
  96  * Creates a new sync_timeline. Returns the sync_timeline object or NULL in
  97  * case of error.
  98  */
  99 static struct sync_timeline *sync_timeline_create(const char *name)
 100 {
 101         struct sync_timeline *obj;
 102
 103         obj = kzalloc(sizeof(*obj), GFP_KERNEL);
 104         if (!obj)
 105                 return NULL;
 106
 107         kref_init(&obj->kref);
 108         obj->context = dma_fence_context_alloc(1);
 109         strscpy(obj->name, name, sizeof(obj->name));
 110
 111         obj->pt_tree = RB_ROOT;
 112         INIT_LIST_HEAD(&obj->pt_list);
 113         spin_lock_init(&obj->lock);
 114
 115         sync_timeline_debug_add(obj);
 116
 117         return obj;
 118 }
 119
 120 static void sync_timeline_free(struct kref *kref)
 121 {
 122         struct sync_timeline *obj =
 123                 container_of(kref, struct sync_timeline, kref);
 124
 125         sync_timeline_debug_remove(obj);
 126
 127         kfree(obj);
 128 }
 129
 130 static void sync_timeline_get(struct sync_timeline *obj)
 131 {
 132         kref_get(&obj->kref);
 133 }
 134
 135 static void sync_timeline_put(struct sync_timeline *obj)
 136 {
 137         kref_put(&obj->kref, sync_timeline_free);
 138 }
 139
 140 static const char *timeline_fence_get_driver_name(struct dma_fence *fence)
 141 {
 142         return "sw_sync";
 143 }
 144
 145 static const char *timeline_fence_get_timeline_name(struct dma_fence *fence)
 146 {
 147         struct sync_timeline *parent = dma_fence_parent(fence);
 148
 149         return parent->name;
 150 }
 151
 152 static void timeline_fence_release(struct dma_fence *fence)
 153 {
 154         struct sync_pt *pt = dma_fence_to_sync_pt(fence);
 155         struct sync_timeline *parent = dma_fence_parent(fence);
 156         unsigned long flags;
 157
 158         spin_lock_irqsave(fence->lock, flags);
 159         if (!list_empty(&pt->link)) {
 160                 list_del(&pt->link);
 161                 rb_erase(&pt->node, &parent->pt_tree);
 162         }
 163         spin_unlock_irqrestore(fence->lock, flags);
 164
 165         sync_timeline_put(parent);
 166         dma_fence_free(fence);
 167 }
 168
 169 static bool timeline_fence_signaled(struct dma_fence *fence)
 170 {
 171         struct sync_timeline *parent = dma_fence_parent(fence);
 172
 173         return !__dma_fence_is_later(fence->seqno, parent->value, fence->ops);
 174 }
 175
 176 static void timeline_fence_value_str(struct dma_fence *fence,
 177                                     char *str, int size)
 178 {
 179         snprintf(str, size, "%lld", fence->seqno);
 180 }
 181
 182 static void timeline_fence_timeline_value_str(struct dma_fence *fence,
 183                                              char *str, int size)
 184 {
 185         struct sync_timeline *parent = dma_fence_parent(fence);
 186
 187         snprintf(str, size, "%d", parent->value);
 188 }
 189
 190 static void timeline_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
 191 {
 192         struct sync_pt *pt = dma_fence_to_sync_pt(fence);
 193         unsigned long flags;
 194
 195         spin_lock_irqsave(fence->lock, flags);
 196         if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
 197                 if (ktime_before(deadline, pt->deadline))
 198                         pt->deadline = deadline;
 199         } else {
 200                 pt->deadline = deadline;
 201                 __set_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags);
 202         }
 203         spin_unlock_irqrestore(fence->lock, flags);
 204 }
 205
 206 static const struct dma_fence_ops timeline_fence_ops = {
 207         .get_driver_name = timeline_fence_get_driver_name,
 208         .get_timeline_name = timeline_fence_get_timeline_name,
 209         .signaled = timeline_fence_signaled,
 210         .release = timeline_fence_release,
 211         .fence_value_str = timeline_fence_value_str,
 212         .timeline_value_str = timeline_fence_timeline_value_str,
 213         .set_deadline = timeline_fence_set_deadline,
 214 };
 215
 216 /**
 217  * sync_timeline_signal() - signal a status change on a sync_timeline
 218  * @obj:        sync_timeline to signal
 219  * @inc:        num to increment on timeline->value
 220  *
 221  * A sync implementation should call this any time one of it's fences
 222  * has signaled or has an error condition.
 223  */
 224 static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc)
 225 {
 226         LIST_HEAD(signalled);
 227         struct sync_pt *pt, *next;
 228
 229         trace_sync_timeline(obj);
 230
 231         spin_lock_irq(&obj->lock);
 232
 233         obj->value += inc;
 234
 235         list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
 236                 if (!timeline_fence_signaled(&pt->base))
 237                         break;
 238
 239                 dma_fence_get(&pt->base);
 240
 241                 list_move_tail(&pt->link, &signalled);
 242                 rb_erase(&pt->node, &obj->pt_tree);
 243
 244                 dma_fence_signal_locked(&pt->base);
 245         }
 246
 247         spin_unlock_irq(&obj->lock);
 248
 249         list_for_each_entry_safe(pt, next, &signalled, link) {
 250                 list_del_init(&pt->link);
 251                 dma_fence_put(&pt->base);
 252         }
 253 }
 254
 255 /**
 256  * sync_pt_create() - creates a sync pt
 257  * @obj:        parent sync_timeline
 258  * @value:      value of the fence
 259  *
 260  * Creates a new sync_pt (fence) as a child of @parent.  @size bytes will be
 261  * allocated allowing for implementation specific data to be kept after
 262  * the generic sync_timeline struct. Returns the sync_pt object or
 263  * NULL in case of error.
 264  */
 265 static struct sync_pt *sync_pt_create(struct sync_timeline *obj,
 266                                       unsigned int value)
 267 {
 268         struct sync_pt *pt;
 269
 270         pt = kzalloc(sizeof(*pt), GFP_KERNEL);
 271         if (!pt)
 272                 return NULL;
 273
 274         sync_timeline_get(obj);
 275         dma_fence_init(&pt->base, &timeline_fence_ops, &obj->lock,
 276                        obj->context, value);
 277         INIT_LIST_HEAD(&pt->link);
 278
 279         spin_lock_irq(&obj->lock);
 280         if (!dma_fence_is_signaled_locked(&pt->base)) {
 281                 struct rb_node **p = &obj->pt_tree.rb_node;
 282                 struct rb_node *parent = NULL;
 283
 284                 while (*p) {
 285                         struct sync_pt *other;
 286                         int cmp;
 287
 288                         parent = *p;
 289                         other = rb_entry(parent, typeof(*pt), node);
 290                         cmp = value - other->base.seqno;
 291                         if (cmp > 0) {
 292                                 p = &parent->rb_right;
 293                         } else if (cmp < 0) {
 294                                 p = &parent->rb_left;
 295                         } else {
 296                                 if (dma_fence_get_rcu(&other->base)) {
 297                                         sync_timeline_put(obj);
 298                                         kfree(pt);
 299                                         pt = other;
 300                                         goto unlock;
 301                                 }
 302                                 p = &parent->rb_left;
 303                         }
 304                 }
 305                 rb_link_node(&pt->node, parent, p);
 306                 rb_insert_color(&pt->node, &obj->pt_tree);
 307
 308                 parent = rb_next(&pt->node);
 309                 list_add_tail(&pt->link,
 310                               parent ? &rb_entry(parent, typeof(*pt), node)->link : &obj->pt_list);
 311         }
 312 unlock:
 313         spin_unlock_irq(&obj->lock);
 314
 315         return pt;
 316 }
 317
 318 /*
 319  * *WARNING*
 320  *
 321  * improper use of this can result in deadlocking kernel drivers from userspace.
 322  */
 323
 324 /* opening sw_sync create a new sync obj */
 325 static int sw_sync_debugfs_open(struct inode *inode, struct file *file)
 326 {
 327         struct sync_timeline *obj;
 328         char task_comm[TASK_COMM_LEN];
 329
 330         get_task_comm(task_comm, current);
 331
 332         obj = sync_timeline_create(task_comm);
 333         if (!obj)
 334                 return -ENOMEM;
 335
 336         file->private_data = obj;
 337
 338         return 0;
 339 }
 340
 341 static int sw_sync_debugfs_release(struct inode *inode, struct file *file)
 342 {
 343         struct sync_timeline *obj = file->private_data;
 344         struct sync_pt *pt, *next;
 345
 346         spin_lock_irq(&obj->lock);
 347
 348         list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
 349                 dma_fence_set_error(&pt->base, -ENOENT);
 350                 dma_fence_signal_locked(&pt->base);
 351         }
 352
 353         spin_unlock_irq(&obj->lock);
 354
 355         sync_timeline_put(obj);
 356         return 0;
 357 }
 358
 359 static long sw_sync_ioctl_create_fence(struct sync_timeline *obj,
 360                                        unsigned long arg)
 361 {
 362         int fd = get_unused_fd_flags(O_CLOEXEC);
 363         int err;
 364         struct sync_pt *pt;
 365         struct sync_file *sync_file;
 366         struct sw_sync_create_fence_data data;
 367
 368         if (fd < 0)
 369                 return fd;
 370
 371         if (copy_from_user(&data, (void __user *)arg, sizeof(data))) {
 372                 err = -EFAULT;
 373                 goto err;
 374         }
 375
 376         pt = sync_pt_create(obj, data.value);
 377         if (!pt) {
 378                 err = -ENOMEM;
 379                 goto err;
 380         }
 381
 382         sync_file = sync_file_create(&pt->base);
 383         dma_fence_put(&pt->base);
 384         if (!sync_file) {
 385                 err = -ENOMEM;
 386                 goto err;
 387         }
 388
 389         data.fence = fd;
 390         if (copy_to_user((void __user *)arg, &data, sizeof(data))) {
 391                 fput(sync_file->file);
 392                 err = -EFAULT;
 393                 goto err;
 394         }
 395
 396         fd_install(fd, sync_file->file);
 397
 398         return 0;
 399
 400 err:
 401         put_unused_fd(fd);
 402         return err;
 403 }
 404
 405 static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg)
 406 {
 407         u32 value;
 408
 409         if (copy_from_user(&value, (void __user *)arg, sizeof(value)))
 410                 return -EFAULT;
 411
 412         while (value > INT_MAX)  {
 413                 sync_timeline_signal(obj, INT_MAX);
 414                 value -= INT_MAX;
 415         }
 416
 417         sync_timeline_signal(obj, value);
 418
 419         return 0;
 420 }
 421
 422 static int sw_sync_ioctl_get_deadline(struct sync_timeline *obj, unsigned long arg)
 423 {
 424         struct sw_sync_get_deadline data;
 425         struct dma_fence *fence;
 426         unsigned long flags;
 427         struct sync_pt *pt;
 428         int ret = 0;
 429
 430         if (copy_from_user(&data, (void __user *)arg, sizeof(data)))
 431                 return -EFAULT;
 432
 433         if (data.deadline_ns || data.pad)
 434                 return -EINVAL;
 435
 436         fence = sync_file_get_fence(data.fence_fd);
 437         if (!fence)
 438                 return -EINVAL;
 439
 440         pt = dma_fence_to_sync_pt(fence);
 441         if (!pt)
 442                 return -EINVAL;
 443
 444         spin_lock_irqsave(fence->lock, flags);
 445         if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
 446                 data.deadline_ns = ktime_to_ns(pt->deadline);
 447         } else {
 448                 ret = -ENOENT;
 449         }
 450         spin_unlock_irqrestore(fence->lock, flags);
 451
 452         dma_fence_put(fence);
 453
 454         if (ret)
 455                 return ret;
 456
 457         if (copy_to_user((void __user *)arg, &data, sizeof(data)))
 458                 return -EFAULT;
 459
 460         return 0;
 461 }
 462
 463 static long sw_sync_ioctl(struct file *file, unsigned int cmd,
 464                           unsigned long arg)
 465 {
 466         struct sync_timeline *obj = file->private_data;
 467
 468         switch (cmd) {
 469         case SW_SYNC_IOC_CREATE_FENCE:
 470                 return sw_sync_ioctl_create_fence(obj, arg);
 471
 472         case SW_SYNC_IOC_INC:
 473                 return sw_sync_ioctl_inc(obj, arg);
 474
 475         case SW_SYNC_GET_DEADLINE:
 476                 return sw_sync_ioctl_get_deadline(obj, arg);
 477
 478         default:
 479                 return -ENOTTY;
 480         }
 481 }
 482
 483 const struct file_operations sw_sync_debugfs_fops = {
 484         .open           = sw_sync_debugfs_open,
 485         .release        = sw_sync_debugfs_release,
 486         .unlocked_ioctl = sw_sync_ioctl,
 487         .compat_ioctl   = compat_ptr_ioctl,
 488 };