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Avoid beyond bounds copy while caching ACL
[zen-stable.git] / drivers / xen / evtchn.c
blobb1f60a0c0bea3e00627293101fd3dd38bb1fd96e
1 /******************************************************************************
2 * evtchn.c
3 *
4 * Driver for receiving and demuxing event-channel signals.
5 *
6 * Copyright (c) 2004-2005, K A Fraser
7 * Multi-process extensions Copyright (c) 2004, Steven Smith
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version 2
11 * as published by the Free Software Foundation; or, when distributed
12 * separately from the Linux kernel or incorporated into other
13 * software packages, subject to the following license:
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining a copy
16 * of this source file (the "Software"), to deal in the Software without
17 * restriction, including without limitation the rights to use, copy, modify,
18 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
19 * and to permit persons to whom the Software is furnished to do so, subject to
20 * the following conditions:
21 *
22 * The above copyright notice and this permission notice shall be included in
23 * all copies or substantial portions of the Software.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
31 * IN THE SOFTWARE.
32 */
33
34 #include <linux/module.h>
35 #include <linux/kernel.h>
36 #include <linux/sched.h>
37 #include <linux/slab.h>
38 #include <linux/string.h>
39 #include <linux/errno.h>
40 #include <linux/fs.h>
41 #include <linux/miscdevice.h>
42 #include <linux/major.h>
43 #include <linux/proc_fs.h>
44 #include <linux/stat.h>
45 #include <linux/poll.h>
46 #include <linux/irq.h>
47 #include <linux/init.h>
48 #include <linux/mutex.h>
49 #include <linux/cpu.h>
50
51 #include <xen/xen.h>
52 #include <xen/events.h>
53 #include <xen/evtchn.h>
54 #include <asm/xen/hypervisor.h>
55
56 struct per_user_data {
57 struct mutex bind_mutex; /* serialize bind/unbind operations */
58
59 /* Notification ring, accessed via /dev/xen/evtchn. */
60 #define EVTCHN_RING_SIZE (PAGE_SIZE / sizeof(evtchn_port_t))
61 #define EVTCHN_RING_MASK(_i) ((_i)&(EVTCHN_RING_SIZE-1))
62 evtchn_port_t *ring;
63 unsigned int ring_cons, ring_prod, ring_overflow;
64 struct mutex ring_cons_mutex; /* protect against concurrent readers */
65
66 /* Processes wait on this queue when ring is empty. */
67 wait_queue_head_t evtchn_wait;
68 struct fasync_struct *evtchn_async_queue;
69 const char *name;
70 };
71
72 /*
73 * Who's bound to each port? This is logically an array of struct
74 * per_user_data *, but we encode the current enabled-state in bit 0.
75 */
76 static unsigned long *port_user;
77 static DEFINE_SPINLOCK(port_user_lock); /* protects port_user[] and ring_prod */
78
79 static inline struct per_user_data *get_port_user(unsigned port)
80 {
81 return (struct per_user_data *)(port_user[port] & ~1);
82 }
83
84 static inline void set_port_user(unsigned port, struct per_user_data *u)
85 {
86 port_user[port] = (unsigned long)u;
87 }
88
89 static inline bool get_port_enabled(unsigned port)
90 {
91 return port_user[port] & 1;
92 }
93
94 static inline void set_port_enabled(unsigned port, bool enabled)
95 {
96 if (enabled)
97 port_user[port] |= 1;
98 else
99 port_user[port] &= ~1;
100 }
101
102 static irqreturn_t evtchn_interrupt(int irq, void *data)
103 {
104 unsigned int port = (unsigned long)data;
105 struct per_user_data *u;
106
107 spin_lock(&port_user_lock);
108
109 u = get_port_user(port);
110
111 WARN(!get_port_enabled(port),
112 "Interrupt for port %d, but apparently not enabled; per-user %p\n",
113 port, u);
114
115 disable_irq_nosync(irq);
116 set_port_enabled(port, false);
117
118 if ((u->ring_prod - u->ring_cons) < EVTCHN_RING_SIZE) {
119 u->ring[EVTCHN_RING_MASK(u->ring_prod)] = port;
120 wmb(); /* Ensure ring contents visible */
121 if (u->ring_cons == u->ring_prod++) {
122 wake_up_interruptible(&u->evtchn_wait);
123 kill_fasync(&u->evtchn_async_queue,
124 SIGIO, POLL_IN);
125 }
126 } else
127 u->ring_overflow = 1;
128
129 spin_unlock(&port_user_lock);
130
131 return IRQ_HANDLED;
132 }
133
134 static ssize_t evtchn_read(struct file *file, char __user *buf,
135 size_t count, loff_t *ppos)
136 {
137 int rc;
138 unsigned int c, p, bytes1 = 0, bytes2 = 0;
139 struct per_user_data *u = file->private_data;
140
141 /* Whole number of ports. */
142 count &= ~(sizeof(evtchn_port_t)-1);
143
144 if (count == 0)
145 return 0;
146
147 if (count > PAGE_SIZE)
148 count = PAGE_SIZE;
149
150 for (;;) {
151 mutex_lock(&u->ring_cons_mutex);
152
153 rc = -EFBIG;
154 if (u->ring_overflow)
155 goto unlock_out;
156
157 c = u->ring_cons;
158 p = u->ring_prod;
159 if (c != p)
160 break;
161
162 mutex_unlock(&u->ring_cons_mutex);
163
164 if (file->f_flags & O_NONBLOCK)
165 return -EAGAIN;
166
167 rc = wait_event_interruptible(u->evtchn_wait,
168 u->ring_cons != u->ring_prod);
169 if (rc)
170 return rc;
171 }
172
173 /* Byte lengths of two chunks. Chunk split (if any) is at ring wrap. */
174 if (((c ^ p) & EVTCHN_RING_SIZE) != 0) {
175 bytes1 = (EVTCHN_RING_SIZE - EVTCHN_RING_MASK(c)) *
176 sizeof(evtchn_port_t);
177 bytes2 = EVTCHN_RING_MASK(p) * sizeof(evtchn_port_t);
178 } else {
179 bytes1 = (p - c) * sizeof(evtchn_port_t);
180 bytes2 = 0;
181 }
182
183 /* Truncate chunks according to caller's maximum byte count. */
184 if (bytes1 > count) {
185 bytes1 = count;
186 bytes2 = 0;
187 } else if ((bytes1 + bytes2) > count) {
188 bytes2 = count - bytes1;
189 }
190
191 rc = -EFAULT;
192 rmb(); /* Ensure that we see the port before we copy it. */
193 if (copy_to_user(buf, &u->ring[EVTCHN_RING_MASK(c)], bytes1) ||
194 ((bytes2 != 0) &&
195 copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))
196 goto unlock_out;
197
198 u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);
199 rc = bytes1 + bytes2;
200
201 unlock_out:
202 mutex_unlock(&u->ring_cons_mutex);
203 return rc;
204 }
205
206 static ssize_t evtchn_write(struct file *file, const char __user *buf,
207 size_t count, loff_t *ppos)
208 {
209 int rc, i;
210 evtchn_port_t *kbuf = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
211 struct per_user_data *u = file->private_data;
212
213 if (kbuf == NULL)
214 return -ENOMEM;
215
216 /* Whole number of ports. */
217 count &= ~(sizeof(evtchn_port_t)-1);
218
219 rc = 0;
220 if (count == 0)
221 goto out;
222
223 if (count > PAGE_SIZE)
224 count = PAGE_SIZE;
225
226 rc = -EFAULT;
227 if (copy_from_user(kbuf, buf, count) != 0)
228 goto out;
229
230 spin_lock_irq(&port_user_lock);
231
232 for (i = 0; i < (count/sizeof(evtchn_port_t)); i++) {
233 unsigned port = kbuf[i];
234
235 if (port < NR_EVENT_CHANNELS &&
236 get_port_user(port) == u &&
237 !get_port_enabled(port)) {
238 set_port_enabled(port, true);
239 enable_irq(irq_from_evtchn(port));
240 }
241 }
242
243 spin_unlock_irq(&port_user_lock);
244
245 rc = count;
246
247 out:
248 free_page((unsigned long)kbuf);
249 return rc;
250 }
251
252 static int evtchn_bind_to_user(struct per_user_data *u, int port)
253 {
254 int rc = 0;
255
256 /*
257 * Ports are never reused, so every caller should pass in a
258 * unique port.
259 *
260 * (Locking not necessary because we haven't registered the
261 * interrupt handler yet, and our caller has already
262 * serialized bind operations.)
263 */
264 BUG_ON(get_port_user(port) != NULL);
265 set_port_user(port, u);
266 set_port_enabled(port, true); /* start enabled */
267
268 rc = bind_evtchn_to_irqhandler(port, evtchn_interrupt, IRQF_DISABLED,
269 u->name, (void *)(unsigned long)port);
270 if (rc >= 0)
271 rc = evtchn_make_refcounted(port);
272
273 return rc;
274 }
275
276 static void evtchn_unbind_from_user(struct per_user_data *u, int port)
277 {
278 int irq = irq_from_evtchn(port);
279
280 unbind_from_irqhandler(irq, (void *)(unsigned long)port);
281
282 set_port_user(port, NULL);
283 }
284
285 static long evtchn_ioctl(struct file *file,
286 unsigned int cmd, unsigned long arg)
287 {
288 int rc;
289 struct per_user_data *u = file->private_data;
290 void __user *uarg = (void __user *) arg;
291
292 /* Prevent bind from racing with unbind */
293 mutex_lock(&u->bind_mutex);
294
295 switch (cmd) {
296 case IOCTL_EVTCHN_BIND_VIRQ: {
297 struct ioctl_evtchn_bind_virq bind;
298 struct evtchn_bind_virq bind_virq;
299
300 rc = -EFAULT;
301 if (copy_from_user(&bind, uarg, sizeof(bind)))
302 break;
303
304 bind_virq.virq = bind.virq;
305 bind_virq.vcpu = 0;
306 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
307 &bind_virq);
308 if (rc != 0)
309 break;
310
311 rc = evtchn_bind_to_user(u, bind_virq.port);
312 if (rc == 0)
313 rc = bind_virq.port;
314 break;
315 }
316
317 case IOCTL_EVTCHN_BIND_INTERDOMAIN: {
318 struct ioctl_evtchn_bind_interdomain bind;
319 struct evtchn_bind_interdomain bind_interdomain;
320
321 rc = -EFAULT;
322 if (copy_from_user(&bind, uarg, sizeof(bind)))
323 break;
324
325 bind_interdomain.remote_dom = bind.remote_domain;
326 bind_interdomain.remote_port = bind.remote_port;
327 rc = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
328 &bind_interdomain);
329 if (rc != 0)
330 break;
331
332 rc = evtchn_bind_to_user(u, bind_interdomain.local_port);
333 if (rc == 0)
334 rc = bind_interdomain.local_port;
335 break;
336 }
337
338 case IOCTL_EVTCHN_BIND_UNBOUND_PORT: {
339 struct ioctl_evtchn_bind_unbound_port bind;
340 struct evtchn_alloc_unbound alloc_unbound;
341
342 rc = -EFAULT;
343 if (copy_from_user(&bind, uarg, sizeof(bind)))
344 break;
345
346 alloc_unbound.dom = DOMID_SELF;
347 alloc_unbound.remote_dom = bind.remote_domain;
348 rc = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
349 &alloc_unbound);
350 if (rc != 0)
351 break;
352
353 rc = evtchn_bind_to_user(u, alloc_unbound.port);
354 if (rc == 0)
355 rc = alloc_unbound.port;
356 break;
357 }
358
359 case IOCTL_EVTCHN_UNBIND: {
360 struct ioctl_evtchn_unbind unbind;
361
362 rc = -EFAULT;
363 if (copy_from_user(&unbind, uarg, sizeof(unbind)))
364 break;
365
366 rc = -EINVAL;
367 if (unbind.port >= NR_EVENT_CHANNELS)
368 break;
369
370 spin_lock_irq(&port_user_lock);
371
372 rc = -ENOTCONN;
373 if (get_port_user(unbind.port) != u) {
374 spin_unlock_irq(&port_user_lock);
375 break;
376 }
377
378 disable_irq(irq_from_evtchn(unbind.port));
379
380 spin_unlock_irq(&port_user_lock);
381
382 evtchn_unbind_from_user(u, unbind.port);
383
384 rc = 0;
385 break;
386 }
387
388 case IOCTL_EVTCHN_NOTIFY: {
389 struct ioctl_evtchn_notify notify;
390
391 rc = -EFAULT;
392 if (copy_from_user(&notify, uarg, sizeof(notify)))
393 break;
394
395 if (notify.port >= NR_EVENT_CHANNELS) {
396 rc = -EINVAL;
397 } else if (get_port_user(notify.port) != u) {
398 rc = -ENOTCONN;
399 } else {
400 notify_remote_via_evtchn(notify.port);
401 rc = 0;
402 }
403 break;
404 }
405
406 case IOCTL_EVTCHN_RESET: {
407 /* Initialise the ring to empty. Clear errors. */
408 mutex_lock(&u->ring_cons_mutex);
409 spin_lock_irq(&port_user_lock);
410 u->ring_cons = u->ring_prod = u->ring_overflow = 0;
411 spin_unlock_irq(&port_user_lock);
412 mutex_unlock(&u->ring_cons_mutex);
413 rc = 0;
414 break;
415 }
416
417 default:
418 rc = -ENOSYS;
419 break;
420 }
421 mutex_unlock(&u->bind_mutex);
422
423 return rc;
424 }
425
426 static unsigned int evtchn_poll(struct file *file, poll_table *wait)
427 {
428 unsigned int mask = POLLOUT | POLLWRNORM;
429 struct per_user_data *u = file->private_data;
430
431 poll_wait(file, &u->evtchn_wait, wait);
432 if (u->ring_cons != u->ring_prod)
433 mask |= POLLIN | POLLRDNORM;
434 if (u->ring_overflow)
435 mask = POLLERR;
436 return mask;
437 }
438
439 static int evtchn_fasync(int fd, struct file *filp, int on)
440 {
441 struct per_user_data *u = filp->private_data;
442 return fasync_helper(fd, filp, on, &u->evtchn_async_queue);
443 }
444
445 static int evtchn_open(struct inode *inode, struct file *filp)
446 {
447 struct per_user_data *u;
448
449 u = kzalloc(sizeof(*u), GFP_KERNEL);
450 if (u == NULL)
451 return -ENOMEM;
452
453 u->name = kasprintf(GFP_KERNEL, "evtchn:%s", current->comm);
454 if (u->name == NULL) {
455 kfree(u);
456 return -ENOMEM;
457 }
458
459 init_waitqueue_head(&u->evtchn_wait);
460
461 u->ring = (evtchn_port_t *)__get_free_page(GFP_KERNEL);
462 if (u->ring == NULL) {
463 kfree(u->name);
464 kfree(u);
465 return -ENOMEM;
466 }
467
468 mutex_init(&u->bind_mutex);
469 mutex_init(&u->ring_cons_mutex);
470
471 filp->private_data = u;
472
473 return nonseekable_open(inode, filp);
474 }
475
476 static int evtchn_release(struct inode *inode, struct file *filp)
477 {
478 int i;
479 struct per_user_data *u = filp->private_data;
480
481 spin_lock_irq(&port_user_lock);
482
483 free_page((unsigned long)u->ring);
484
485 for (i = 0; i < NR_EVENT_CHANNELS; i++) {
486 if (get_port_user(i) != u)
487 continue;
488
489 disable_irq(irq_from_evtchn(i));
490 }
491
492 spin_unlock_irq(&port_user_lock);
493
494 for (i = 0; i < NR_EVENT_CHANNELS; i++) {
495 if (get_port_user(i) != u)
496 continue;
497
498 evtchn_unbind_from_user(get_port_user(i), i);
499 }
500
501 kfree(u->name);
502 kfree(u);
503
504 return 0;
505 }
506
507 static const struct file_operations evtchn_fops = {
508 .owner = THIS_MODULE,
509 .read = evtchn_read,
510 .write = evtchn_write,
511 .unlocked_ioctl = evtchn_ioctl,
512 .poll = evtchn_poll,
513 .fasync = evtchn_fasync,
514 .open = evtchn_open,
515 .release = evtchn_release,
516 .llseek = no_llseek,
517 };
518
519 static struct miscdevice evtchn_miscdev = {
520 .minor = MISC_DYNAMIC_MINOR,
521 .name = "xen/evtchn",
522 .fops = &evtchn_fops,
523 };
524 static int __init evtchn_init(void)
525 {
526 int err;
527
528 if (!xen_domain())
529 return -ENODEV;
530
531 port_user = kcalloc(NR_EVENT_CHANNELS, sizeof(*port_user), GFP_KERNEL);
532 if (port_user == NULL)
533 return -ENOMEM;
534
535 spin_lock_init(&port_user_lock);
536
537 /* Create '/dev/misc/evtchn'. */
538 err = misc_register(&evtchn_miscdev);
539 if (err != 0) {
540 printk(KERN_ALERT "Could not register /dev/misc/evtchn\n");
541 return err;
542 }
543
544 printk(KERN_INFO "Event-channel device installed.\n");
545
546 return 0;
547 }
548
549 static void __exit evtchn_cleanup(void)
550 {
551 kfree(port_user);
552 port_user = NULL;
553
554 misc_deregister(&evtchn_miscdev);
555 }
556
557 module_init(evtchn_init);
558 module_exit(evtchn_cleanup);
559
560 MODULE_LICENSE("GPL");