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Merge tag 'pm-4.15-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
[linux/fpc-iii.git] / fs / select.c
blob6de493bb42a4b90d6b029689f1b11de20ca3ac50
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * This file contains the procedures for the handling of select and poll
4 *
5 * Created for Linux based loosely upon Mathius Lattner's minix
6 * patches by Peter MacDonald. Heavily edited by Linus.
7 *
8 * 4 February 1994
9 * COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS
10 * flag set in its personality we do *not* modify the given timeout
11 * parameter to reflect time remaining.
12 *
13 * 24 January 2000
14 * Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation
15 * of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian).
16 */
17
18 #include <linux/kernel.h>
19 #include <linux/sched/signal.h>
20 #include <linux/sched/rt.h>
21 #include <linux/syscalls.h>
22 #include <linux/export.h>
23 #include <linux/slab.h>
24 #include <linux/poll.h>
25 #include <linux/personality.h> /* for STICKY_TIMEOUTS */
26 #include <linux/file.h>
27 #include <linux/fdtable.h>
28 #include <linux/fs.h>
29 #include <linux/rcupdate.h>
30 #include <linux/hrtimer.h>
31 #include <linux/freezer.h>
32 #include <net/busy_poll.h>
33 #include <linux/vmalloc.h>
34
35 #include <linux/uaccess.h>
36
37
38 /*
39 * Estimate expected accuracy in ns from a timeval.
40 *
41 * After quite a bit of churning around, we've settled on
42 * a simple thing of taking 0.1% of the timeout as the
43 * slack, with a cap of 100 msec.
44 * "nice" tasks get a 0.5% slack instead.
45 *
46 * Consider this comment an open invitation to come up with even
47 * better solutions..
48 */
49
50 #define MAX_SLACK (100 * NSEC_PER_MSEC)
51
52 static long __estimate_accuracy(struct timespec64 *tv)
53 {
54 long slack;
55 int divfactor = 1000;
56
57 if (tv->tv_sec < 0)
58 return 0;
59
60 if (task_nice(current) > 0)
61 divfactor = divfactor / 5;
62
63 if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor))
64 return MAX_SLACK;
65
66 slack = tv->tv_nsec / divfactor;
67 slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);
68
69 if (slack > MAX_SLACK)
70 return MAX_SLACK;
71
72 return slack;
73 }
74
75 u64 select_estimate_accuracy(struct timespec64 *tv)
76 {
77 u64 ret;
78 struct timespec64 now;
79
80 /*
81 * Realtime tasks get a slack of 0 for obvious reasons.
82 */
83
84 if (rt_task(current))
85 return 0;
86
87 ktime_get_ts64(&now);
88 now = timespec64_sub(*tv, now);
89 ret = __estimate_accuracy(&now);
90 if (ret < current->timer_slack_ns)
91 return current->timer_slack_ns;
92 return ret;
93 }
94
95
96
97 struct poll_table_page {
98 struct poll_table_page * next;
99 struct poll_table_entry * entry;
100 struct poll_table_entry entries[0];
101 };
102
103 #define POLL_TABLE_FULL(table) \
104 ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
105
106 /*
107 * Ok, Peter made a complicated, but straightforward multiple_wait() function.
108 * I have rewritten this, taking some shortcuts: This code may not be easy to
109 * follow, but it should be free of race-conditions, and it's practical. If you
110 * understand what I'm doing here, then you understand how the linux
111 * sleep/wakeup mechanism works.
112 *
113 * Two very simple procedures, poll_wait() and poll_freewait() make all the
114 * work. poll_wait() is an inline-function defined in <linux/poll.h>,
115 * as all select/poll functions have to call it to add an entry to the
116 * poll table.
117 */
118 static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
119 poll_table *p);
120
121 void poll_initwait(struct poll_wqueues *pwq)
122 {
123 init_poll_funcptr(&pwq->pt, __pollwait);
124 pwq->polling_task = current;
125 pwq->triggered = 0;
126 pwq->error = 0;
127 pwq->table = NULL;
128 pwq->inline_index = 0;
129 }
130 EXPORT_SYMBOL(poll_initwait);
131
132 static void free_poll_entry(struct poll_table_entry *entry)
133 {
134 remove_wait_queue(entry->wait_address, &entry->wait);
135 fput(entry->filp);
136 }
137
138 void poll_freewait(struct poll_wqueues *pwq)
139 {
140 struct poll_table_page * p = pwq->table;
141 int i;
142 for (i = 0; i < pwq->inline_index; i++)
143 free_poll_entry(pwq->inline_entries + i);
144 while (p) {
145 struct poll_table_entry * entry;
146 struct poll_table_page *old;
147
148 entry = p->entry;
149 do {
150 entry--;
151 free_poll_entry(entry);
152 } while (entry > p->entries);
153 old = p;
154 p = p->next;
155 free_page((unsigned long) old);
156 }
157 }
158 EXPORT_SYMBOL(poll_freewait);
159
160 static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p)
161 {
162 struct poll_table_page *table = p->table;
163
164 if (p->inline_index < N_INLINE_POLL_ENTRIES)
165 return p->inline_entries + p->inline_index++;
166
167 if (!table || POLL_TABLE_FULL(table)) {
168 struct poll_table_page *new_table;
169
170 new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
171 if (!new_table) {
172 p->error = -ENOMEM;
173 return NULL;
174 }
175 new_table->entry = new_table->entries;
176 new_table->next = table;
177 p->table = new_table;
178 table = new_table;
179 }
180
181 return table->entry++;
182 }
183
184 static int __pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
185 {
186 struct poll_wqueues *pwq = wait->private;
187 DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);
188
189 /*
190 * Although this function is called under waitqueue lock, LOCK
191 * doesn't imply write barrier and the users expect write
192 * barrier semantics on wakeup functions. The following
193 * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
194 * and is paired with smp_store_mb() in poll_schedule_timeout.
195 */
196 smp_wmb();
197 pwq->triggered = 1;
198
199 /*
200 * Perform the default wake up operation using a dummy
201 * waitqueue.
202 *
203 * TODO: This is hacky but there currently is no interface to
204 * pass in @sync. @sync is scheduled to be removed and once
205 * that happens, wake_up_process() can be used directly.
206 */
207 return default_wake_function(&dummy_wait, mode, sync, key);
208 }
209
210 static int pollwake(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
211 {
212 struct poll_table_entry *entry;
213
214 entry = container_of(wait, struct poll_table_entry, wait);
215 if (key && !((unsigned long)key & entry->key))
216 return 0;
217 return __pollwake(wait, mode, sync, key);
218 }
219
220 /* Add a new entry */
221 static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
222 poll_table *p)
223 {
224 struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt);
225 struct poll_table_entry *entry = poll_get_entry(pwq);
226 if (!entry)
227 return;
228 entry->filp = get_file(filp);
229 entry->wait_address = wait_address;
230 entry->key = p->_key;
231 init_waitqueue_func_entry(&entry->wait, pollwake);
232 entry->wait.private = pwq;
233 add_wait_queue(wait_address, &entry->wait);
234 }
235
236 int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
237 ktime_t *expires, unsigned long slack)
238 {
239 int rc = -EINTR;
240
241 set_current_state(state);
242 if (!pwq->triggered)
243 rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS);
244 __set_current_state(TASK_RUNNING);
245
246 /*
247 * Prepare for the next iteration.
248 *
249 * The following smp_store_mb() serves two purposes. First, it's
250 * the counterpart rmb of the wmb in pollwake() such that data
251 * written before wake up is always visible after wake up.
252 * Second, the full barrier guarantees that triggered clearing
253 * doesn't pass event check of the next iteration. Note that
254 * this problem doesn't exist for the first iteration as
255 * add_wait_queue() has full barrier semantics.
256 */
257 smp_store_mb(pwq->triggered, 0);
258
259 return rc;
260 }
261 EXPORT_SYMBOL(poll_schedule_timeout);
262
263 /**
264 * poll_select_set_timeout - helper function to setup the timeout value
265 * @to: pointer to timespec64 variable for the final timeout
266 * @sec: seconds (from user space)
267 * @nsec: nanoseconds (from user space)
268 *
269 * Note, we do not use a timespec for the user space value here, That
270 * way we can use the function for timeval and compat interfaces as well.
271 *
272 * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0.
273 */
274 int poll_select_set_timeout(struct timespec64 *to, time64_t sec, long nsec)
275 {
276 struct timespec64 ts = {.tv_sec = sec, .tv_nsec = nsec};
277
278 if (!timespec64_valid(&ts))
279 return -EINVAL;
280
281 /* Optimize for the zero timeout value here */
282 if (!sec && !nsec) {
283 to->tv_sec = to->tv_nsec = 0;
284 } else {
285 ktime_get_ts64(to);
286 *to = timespec64_add_safe(*to, ts);
287 }
288 return 0;
289 }
290
291 static int poll_select_copy_remaining(struct timespec64 *end_time,
292 void __user *p,
293 int timeval, int ret)
294 {
295 struct timespec64 rts;
296 struct timeval rtv;
297
298 if (!p)
299 return ret;
300
301 if (current->personality & STICKY_TIMEOUTS)
302 goto sticky;
303
304 /* No update for zero timeout */
305 if (!end_time->tv_sec && !end_time->tv_nsec)
306 return ret;
307
308 ktime_get_ts64(&rts);
309 rts = timespec64_sub(*end_time, rts);
310 if (rts.tv_sec < 0)
311 rts.tv_sec = rts.tv_nsec = 0;
312
313
314 if (timeval) {
315 if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec))
316 memset(&rtv, 0, sizeof(rtv));
317 rtv.tv_sec = rts.tv_sec;
318 rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;
319
320 if (!copy_to_user(p, &rtv, sizeof(rtv)))
321 return ret;
322
323 } else if (!put_timespec64(&rts, p))
324 return ret;
325
326 /*
327 * If an application puts its timeval in read-only memory, we
328 * don't want the Linux-specific update to the timeval to
329 * cause a fault after the select has completed
330 * successfully. However, because we're not updating the
331 * timeval, we can't restart the system call.
332 */
333
334 sticky:
335 if (ret == -ERESTARTNOHAND)
336 ret = -EINTR;
337 return ret;
338 }
339
340 /*
341 * Scalable version of the fd_set.
342 */
343
344 typedef struct {
345 unsigned long *in, *out, *ex;
346 unsigned long *res_in, *res_out, *res_ex;
347 } fd_set_bits;
348
349 /*
350 * How many longwords for "nr" bits?
351 */
352 #define FDS_BITPERLONG (8*sizeof(long))
353 #define FDS_LONGS(nr) (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
354 #define FDS_BYTES(nr) (FDS_LONGS(nr)*sizeof(long))
355
356 /*
357 * We do a VERIFY_WRITE here even though we are only reading this time:
358 * we'll write to it eventually..
359 *
360 * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
361 */
362 static inline
363 int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
364 {
365 nr = FDS_BYTES(nr);
366 if (ufdset)
367 return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
368
369 memset(fdset, 0, nr);
370 return 0;
371 }
372
373 static inline unsigned long __must_check
374 set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
375 {
376 if (ufdset)
377 return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
378 return 0;
379 }
380
381 static inline
382 void zero_fd_set(unsigned long nr, unsigned long *fdset)
383 {
384 memset(fdset, 0, FDS_BYTES(nr));
385 }
386
387 #define FDS_IN(fds, n) (fds->in + n)
388 #define FDS_OUT(fds, n) (fds->out + n)
389 #define FDS_EX(fds, n) (fds->ex + n)
390
391 #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
392
393 static int max_select_fd(unsigned long n, fd_set_bits *fds)
394 {
395 unsigned long *open_fds;
396 unsigned long set;
397 int max;
398 struct fdtable *fdt;
399
400 /* handle last in-complete long-word first */
401 set = ~(~0UL << (n & (BITS_PER_LONG-1)));
402 n /= BITS_PER_LONG;
403 fdt = files_fdtable(current->files);
404 open_fds = fdt->open_fds + n;
405 max = 0;
406 if (set) {
407 set &= BITS(fds, n);
408 if (set) {
409 if (!(set & ~*open_fds))
410 goto get_max;
411 return -EBADF;
412 }
413 }
414 while (n) {
415 open_fds--;
416 n--;
417 set = BITS(fds, n);
418 if (!set)
419 continue;
420 if (set & ~*open_fds)
421 return -EBADF;
422 if (max)
423 continue;
424 get_max:
425 do {
426 max++;
427 set >>= 1;
428 } while (set);
429 max += n * BITS_PER_LONG;
430 }
431
432 return max;
433 }
434
435 #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
436 #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
437 #define POLLEX_SET (POLLPRI)
438
439 static inline void wait_key_set(poll_table *wait, unsigned long in,
440 unsigned long out, unsigned long bit,
441 unsigned int ll_flag)
442 {
443 wait->_key = POLLEX_SET | ll_flag;
444 if (in & bit)
445 wait->_key |= POLLIN_SET;
446 if (out & bit)
447 wait->_key |= POLLOUT_SET;
448 }
449
450 static int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time)
451 {
452 ktime_t expire, *to = NULL;
453 struct poll_wqueues table;
454 poll_table *wait;
455 int retval, i, timed_out = 0;
456 u64 slack = 0;
457 unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
458 unsigned long busy_start = 0;
459
460 rcu_read_lock();
461 retval = max_select_fd(n, fds);
462 rcu_read_unlock();
463
464 if (retval < 0)
465 return retval;
466 n = retval;
467
468 poll_initwait(&table);
469 wait = &table.pt;
470 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
471 wait->_qproc = NULL;
472 timed_out = 1;
473 }
474
475 if (end_time && !timed_out)
476 slack = select_estimate_accuracy(end_time);
477
478 retval = 0;
479 for (;;) {
480 unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
481 bool can_busy_loop = false;
482
483 inp = fds->in; outp = fds->out; exp = fds->ex;
484 rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
485
486 for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
487 unsigned long in, out, ex, all_bits, bit = 1, mask, j;
488 unsigned long res_in = 0, res_out = 0, res_ex = 0;
489
490 in = *inp++; out = *outp++; ex = *exp++;
491 all_bits = in | out | ex;
492 if (all_bits == 0) {
493 i += BITS_PER_LONG;
494 continue;
495 }
496
497 for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) {
498 struct fd f;
499 if (i >= n)
500 break;
501 if (!(bit & all_bits))
502 continue;
503 f = fdget(i);
504 if (f.file) {
505 const struct file_operations *f_op;
506 f_op = f.file->f_op;
507 mask = DEFAULT_POLLMASK;
508 if (f_op->poll) {
509 wait_key_set(wait, in, out,
510 bit, busy_flag);
511 mask = (*f_op->poll)(f.file, wait);
512 }
513 fdput(f);
514 if ((mask & POLLIN_SET) && (in & bit)) {
515 res_in |= bit;
516 retval++;
517 wait->_qproc = NULL;
518 }
519 if ((mask & POLLOUT_SET) && (out & bit)) {
520 res_out |= bit;
521 retval++;
522 wait->_qproc = NULL;
523 }
524 if ((mask & POLLEX_SET) && (ex & bit)) {
525 res_ex |= bit;
526 retval++;
527 wait->_qproc = NULL;
528 }
529 /* got something, stop busy polling */
530 if (retval) {
531 can_busy_loop = false;
532 busy_flag = 0;
533
534 /*
535 * only remember a returned
536 * POLL_BUSY_LOOP if we asked for it
537 */
538 } else if (busy_flag & mask)
539 can_busy_loop = true;
540
541 }
542 }
543 if (res_in)
544 *rinp = res_in;
545 if (res_out)
546 *routp = res_out;
547 if (res_ex)
548 *rexp = res_ex;
549 cond_resched();
550 }
551 wait->_qproc = NULL;
552 if (retval || timed_out || signal_pending(current))
553 break;
554 if (table.error) {
555 retval = table.error;
556 break;
557 }
558
559 /* only if found POLL_BUSY_LOOP sockets && not out of time */
560 if (can_busy_loop && !need_resched()) {
561 if (!busy_start) {
562 busy_start = busy_loop_current_time();
563 continue;
564 }
565 if (!busy_loop_timeout(busy_start))
566 continue;
567 }
568 busy_flag = 0;
569
570 /*
571 * If this is the first loop and we have a timeout
572 * given, then we convert to ktime_t and set the to
573 * pointer to the expiry value.
574 */
575 if (end_time && !to) {
576 expire = timespec64_to_ktime(*end_time);
577 to = &expire;
578 }
579
580 if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE,
581 to, slack))
582 timed_out = 1;
583 }
584
585 poll_freewait(&table);
586
587 return retval;
588 }
589
590 /*
591 * We can actually return ERESTARTSYS instead of EINTR, but I'd
592 * like to be certain this leads to no problems. So I return
593 * EINTR just for safety.
594 *
595 * Update: ERESTARTSYS breaks at least the xview clock binary, so
596 * I'm trying ERESTARTNOHAND which restart only when you want to.
597 */
598 int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
599 fd_set __user *exp, struct timespec64 *end_time)
600 {
601 fd_set_bits fds;
602 void *bits;
603 int ret, max_fds;
604 size_t size, alloc_size;
605 struct fdtable *fdt;
606 /* Allocate small arguments on the stack to save memory and be faster */
607 long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
608
609 ret = -EINVAL;
610 if (n < 0)
611 goto out_nofds;
612
613 /* max_fds can increase, so grab it once to avoid race */
614 rcu_read_lock();
615 fdt = files_fdtable(current->files);
616 max_fds = fdt->max_fds;
617 rcu_read_unlock();
618 if (n > max_fds)
619 n = max_fds;
620
621 /*
622 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
623 * since we used fdset we need to allocate memory in units of
624 * long-words.
625 */
626 size = FDS_BYTES(n);
627 bits = stack_fds;
628 if (size > sizeof(stack_fds) / 6) {
629 /* Not enough space in on-stack array; must use kmalloc */
630 ret = -ENOMEM;
631 if (size > (SIZE_MAX / 6))
632 goto out_nofds;
633
634 alloc_size = 6 * size;
635 bits = kvmalloc(alloc_size, GFP_KERNEL);
636 if (!bits)
637 goto out_nofds;
638 }
639 fds.in = bits;
640 fds.out = bits + size;
641 fds.ex = bits + 2*size;
642 fds.res_in = bits + 3*size;
643 fds.res_out = bits + 4*size;
644 fds.res_ex = bits + 5*size;
645
646 if ((ret = get_fd_set(n, inp, fds.in)) ||
647 (ret = get_fd_set(n, outp, fds.out)) ||
648 (ret = get_fd_set(n, exp, fds.ex)))
649 goto out;
650 zero_fd_set(n, fds.res_in);
651 zero_fd_set(n, fds.res_out);
652 zero_fd_set(n, fds.res_ex);
653
654 ret = do_select(n, &fds, end_time);
655
656 if (ret < 0)
657 goto out;
658 if (!ret) {
659 ret = -ERESTARTNOHAND;
660 if (signal_pending(current))
661 goto out;
662 ret = 0;
663 }
664
665 if (set_fd_set(n, inp, fds.res_in) ||
666 set_fd_set(n, outp, fds.res_out) ||
667 set_fd_set(n, exp, fds.res_ex))
668 ret = -EFAULT;
669
670 out:
671 if (bits != stack_fds)
672 kvfree(bits);
673 out_nofds:
674 return ret;
675 }
676
677 SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
678 fd_set __user *, exp, struct timeval __user *, tvp)
679 {
680 struct timespec64 end_time, *to = NULL;
681 struct timeval tv;
682 int ret;
683
684 if (tvp) {
685 if (copy_from_user(&tv, tvp, sizeof(tv)))
686 return -EFAULT;
687
688 to = &end_time;
689 if (poll_select_set_timeout(to,
690 tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
691 (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
692 return -EINVAL;
693 }
694
695 ret = core_sys_select(n, inp, outp, exp, to);
696 ret = poll_select_copy_remaining(&end_time, tvp, 1, ret);
697
698 return ret;
699 }
700
701 static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,
702 fd_set __user *exp, struct timespec __user *tsp,
703 const sigset_t __user *sigmask, size_t sigsetsize)
704 {
705 sigset_t ksigmask, sigsaved;
706 struct timespec64 ts, end_time, *to = NULL;
707 int ret;
708
709 if (tsp) {
710 if (get_timespec64(&ts, tsp))
711 return -EFAULT;
712
713 to = &end_time;
714 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
715 return -EINVAL;
716 }
717
718 if (sigmask) {
719 /* XXX: Don't preclude handling different sized sigset_t's. */
720 if (sigsetsize != sizeof(sigset_t))
721 return -EINVAL;
722 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
723 return -EFAULT;
724
725 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
726 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
727 }
728
729 ret = core_sys_select(n, inp, outp, exp, to);
730 ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
731
732 if (ret == -ERESTARTNOHAND) {
733 /*
734 * Don't restore the signal mask yet. Let do_signal() deliver
735 * the signal on the way back to userspace, before the signal
736 * mask is restored.
737 */
738 if (sigmask) {
739 memcpy(&current->saved_sigmask, &sigsaved,
740 sizeof(sigsaved));
741 set_restore_sigmask();
742 }
743 } else if (sigmask)
744 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
745
746 return ret;
747 }
748
749 /*
750 * Most architectures can't handle 7-argument syscalls. So we provide a
751 * 6-argument version where the sixth argument is a pointer to a structure
752 * which has a pointer to the sigset_t itself followed by a size_t containing
753 * the sigset size.
754 */
755 SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp,
756 fd_set __user *, exp, struct timespec __user *, tsp,
757 void __user *, sig)
758 {
759 size_t sigsetsize = 0;
760 sigset_t __user *up = NULL;
761
762 if (sig) {
763 if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t))
764 || __get_user(up, (sigset_t __user * __user *)sig)
765 || __get_user(sigsetsize,
766 (size_t __user *)(sig+sizeof(void *))))
767 return -EFAULT;
768 }
769
770 return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize);
771 }
772
773 #ifdef __ARCH_WANT_SYS_OLD_SELECT
774 struct sel_arg_struct {
775 unsigned long n;
776 fd_set __user *inp, *outp, *exp;
777 struct timeval __user *tvp;
778 };
779
780 SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)
781 {
782 struct sel_arg_struct a;
783
784 if (copy_from_user(&a, arg, sizeof(a)))
785 return -EFAULT;
786 return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp);
787 }
788 #endif
789
790 struct poll_list {
791 struct poll_list *next;
792 int len;
793 struct pollfd entries[0];
794 };
795
796 #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
797
798 /*
799 * Fish for pollable events on the pollfd->fd file descriptor. We're only
800 * interested in events matching the pollfd->events mask, and the result
801 * matching that mask is both recorded in pollfd->revents and returned. The
802 * pwait poll_table will be used by the fd-provided poll handler for waiting,
803 * if pwait->_qproc is non-NULL.
804 */
805 static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait,
806 bool *can_busy_poll,
807 unsigned int busy_flag)
808 {
809 unsigned int mask;
810 int fd;
811
812 mask = 0;
813 fd = pollfd->fd;
814 if (fd >= 0) {
815 struct fd f = fdget(fd);
816 mask = POLLNVAL;
817 if (f.file) {
818 mask = DEFAULT_POLLMASK;
819 if (f.file->f_op->poll) {
820 pwait->_key = pollfd->events|POLLERR|POLLHUP;
821 pwait->_key |= busy_flag;
822 mask = f.file->f_op->poll(f.file, pwait);
823 if (mask & busy_flag)
824 *can_busy_poll = true;
825 }
826 /* Mask out unneeded events. */
827 mask &= pollfd->events | POLLERR | POLLHUP;
828 fdput(f);
829 }
830 }
831 pollfd->revents = mask;
832
833 return mask;
834 }
835
836 static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
837 struct timespec64 *end_time)
838 {
839 poll_table* pt = &wait->pt;
840 ktime_t expire, *to = NULL;
841 int timed_out = 0, count = 0;
842 u64 slack = 0;
843 unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
844 unsigned long busy_start = 0;
845
846 /* Optimise the no-wait case */
847 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
848 pt->_qproc = NULL;
849 timed_out = 1;
850 }
851
852 if (end_time && !timed_out)
853 slack = select_estimate_accuracy(end_time);
854
855 for (;;) {
856 struct poll_list *walk;
857 bool can_busy_loop = false;
858
859 for (walk = list; walk != NULL; walk = walk->next) {
860 struct pollfd * pfd, * pfd_end;
861
862 pfd = walk->entries;
863 pfd_end = pfd + walk->len;
864 for (; pfd != pfd_end; pfd++) {
865 /*
866 * Fish for events. If we found one, record it
867 * and kill poll_table->_qproc, so we don't
868 * needlessly register any other waiters after
869 * this. They'll get immediately deregistered
870 * when we break out and return.
871 */
872 if (do_pollfd(pfd, pt, &can_busy_loop,
873 busy_flag)) {
874 count++;
875 pt->_qproc = NULL;
876 /* found something, stop busy polling */
877 busy_flag = 0;
878 can_busy_loop = false;
879 }
880 }
881 }
882 /*
883 * All waiters have already been registered, so don't provide
884 * a poll_table->_qproc to them on the next loop iteration.
885 */
886 pt->_qproc = NULL;
887 if (!count) {
888 count = wait->error;
889 if (signal_pending(current))
890 count = -EINTR;
891 }
892 if (count || timed_out)
893 break;
894
895 /* only if found POLL_BUSY_LOOP sockets && not out of time */
896 if (can_busy_loop && !need_resched()) {
897 if (!busy_start) {
898 busy_start = busy_loop_current_time();
899 continue;
900 }
901 if (!busy_loop_timeout(busy_start))
902 continue;
903 }
904 busy_flag = 0;
905
906 /*
907 * If this is the first loop and we have a timeout
908 * given, then we convert to ktime_t and set the to
909 * pointer to the expiry value.
910 */
911 if (end_time && !to) {
912 expire = timespec64_to_ktime(*end_time);
913 to = &expire;
914 }
915
916 if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))
917 timed_out = 1;
918 }
919 return count;
920 }
921
922 #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \
923 sizeof(struct pollfd))
924
925 static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
926 struct timespec64 *end_time)
927 {
928 struct poll_wqueues table;
929 int err = -EFAULT, fdcount, len, size;
930 /* Allocate small arguments on the stack to save memory and be
931 faster - use long to make sure the buffer is aligned properly
932 on 64 bit archs to avoid unaligned access */
933 long stack_pps[POLL_STACK_ALLOC/sizeof(long)];
934 struct poll_list *const head = (struct poll_list *)stack_pps;
935 struct poll_list *walk = head;
936 unsigned long todo = nfds;
937
938 if (nfds > rlimit(RLIMIT_NOFILE))
939 return -EINVAL;
940
941 len = min_t(unsigned int, nfds, N_STACK_PPS);
942 for (;;) {
943 walk->next = NULL;
944 walk->len = len;
945 if (!len)
946 break;
947
948 if (copy_from_user(walk->entries, ufds + nfds-todo,
949 sizeof(struct pollfd) * walk->len))
950 goto out_fds;
951
952 todo -= walk->len;
953 if (!todo)
954 break;
955
956 len = min(todo, POLLFD_PER_PAGE);
957 size = sizeof(struct poll_list) + sizeof(struct pollfd) * len;
958 walk = walk->next = kmalloc(size, GFP_KERNEL);
959 if (!walk) {
960 err = -ENOMEM;
961 goto out_fds;
962 }
963 }
964
965 poll_initwait(&table);
966 fdcount = do_poll(head, &table, end_time);
967 poll_freewait(&table);
968
969 for (walk = head; walk; walk = walk->next) {
970 struct pollfd *fds = walk->entries;
971 int j;
972
973 for (j = 0; j < walk->len; j++, ufds++)
974 if (__put_user(fds[j].revents, &ufds->revents))
975 goto out_fds;
976 }
977
978 err = fdcount;
979 out_fds:
980 walk = head->next;
981 while (walk) {
982 struct poll_list *pos = walk;
983 walk = walk->next;
984 kfree(pos);
985 }
986
987 return err;
988 }
989
990 static long do_restart_poll(struct restart_block *restart_block)
991 {
992 struct pollfd __user *ufds = restart_block->poll.ufds;
993 int nfds = restart_block->poll.nfds;
994 struct timespec64 *to = NULL, end_time;
995 int ret;
996
997 if (restart_block->poll.has_timeout) {
998 end_time.tv_sec = restart_block->poll.tv_sec;
999 end_time.tv_nsec = restart_block->poll.tv_nsec;
1000 to = &end_time;
1001 }
1002
1003 ret = do_sys_poll(ufds, nfds, to);
1004
1005 if (ret == -EINTR) {
1006 restart_block->fn = do_restart_poll;
1007 ret = -ERESTART_RESTARTBLOCK;
1008 }
1009 return ret;
1010 }
1011
1012 SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
1013 int, timeout_msecs)
1014 {
1015 struct timespec64 end_time, *to = NULL;
1016 int ret;
1017
1018 if (timeout_msecs >= 0) {
1019 to = &end_time;
1020 poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
1021 NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));
1022 }
1023
1024 ret = do_sys_poll(ufds, nfds, to);
1025
1026 if (ret == -EINTR) {
1027 struct restart_block *restart_block;
1028
1029 restart_block = &current->restart_block;
1030 restart_block->fn = do_restart_poll;
1031 restart_block->poll.ufds = ufds;
1032 restart_block->poll.nfds = nfds;
1033
1034 if (timeout_msecs >= 0) {
1035 restart_block->poll.tv_sec = end_time.tv_sec;
1036 restart_block->poll.tv_nsec = end_time.tv_nsec;
1037 restart_block->poll.has_timeout = 1;
1038 } else
1039 restart_block->poll.has_timeout = 0;
1040
1041 ret = -ERESTART_RESTARTBLOCK;
1042 }
1043 return ret;
1044 }
1045
1046 SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
1047 struct timespec __user *, tsp, const sigset_t __user *, sigmask,
1048 size_t, sigsetsize)
1049 {
1050 sigset_t ksigmask, sigsaved;
1051 struct timespec64 ts, end_time, *to = NULL;
1052 int ret;
1053
1054 if (tsp) {
1055 if (get_timespec64(&ts, tsp))
1056 return -EFAULT;
1057
1058 to = &end_time;
1059 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
1060 return -EINVAL;
1061 }
1062
1063 if (sigmask) {
1064 /* XXX: Don't preclude handling different sized sigset_t's. */
1065 if (sigsetsize != sizeof(sigset_t))
1066 return -EINVAL;
1067 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
1068 return -EFAULT;
1069
1070 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
1071 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
1072 }
1073
1074 ret = do_sys_poll(ufds, nfds, to);
1075
1076 /* We can restart this syscall, usually */
1077 if (ret == -EINTR) {
1078 /*
1079 * Don't restore the signal mask yet. Let do_signal() deliver
1080 * the signal on the way back to userspace, before the signal
1081 * mask is restored.
1082 */
1083 if (sigmask) {
1084 memcpy(&current->saved_sigmask, &sigsaved,
1085 sizeof(sigsaved));
1086 set_restore_sigmask();
1087 }
1088 ret = -ERESTARTNOHAND;
1089 } else if (sigmask)
1090 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
1091
1092 ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
1093
1094 return ret;
1095 }
1096
1097 #ifdef CONFIG_COMPAT
1098 #define __COMPAT_NFDBITS (8 * sizeof(compat_ulong_t))
1099
1100 static
1101 int compat_poll_select_copy_remaining(struct timespec64 *end_time, void __user *p,
1102 int timeval, int ret)
1103 {
1104 struct timespec64 ts;
1105
1106 if (!p)
1107 return ret;
1108
1109 if (current->personality & STICKY_TIMEOUTS)
1110 goto sticky;
1111
1112 /* No update for zero timeout */
1113 if (!end_time->tv_sec && !end_time->tv_nsec)
1114 return ret;
1115
1116 ktime_get_ts64(&ts);
1117 ts = timespec64_sub(*end_time, ts);
1118 if (ts.tv_sec < 0)
1119 ts.tv_sec = ts.tv_nsec = 0;
1120
1121 if (timeval) {
1122 struct compat_timeval rtv;
1123
1124 rtv.tv_sec = ts.tv_sec;
1125 rtv.tv_usec = ts.tv_nsec / NSEC_PER_USEC;
1126
1127 if (!copy_to_user(p, &rtv, sizeof(rtv)))
1128 return ret;
1129 } else {
1130 if (!compat_put_timespec64(&ts, p))
1131 return ret;
1132 }
1133 /*
1134 * If an application puts its timeval in read-only memory, we
1135 * don't want the Linux-specific update to the timeval to
1136 * cause a fault after the select has completed
1137 * successfully. However, because we're not updating the
1138 * timeval, we can't restart the system call.
1139 */
1140
1141 sticky:
1142 if (ret == -ERESTARTNOHAND)
1143 ret = -EINTR;
1144 return ret;
1145 }
1146
1147 /*
1148 * Ooo, nasty. We need here to frob 32-bit unsigned longs to
1149 * 64-bit unsigned longs.
1150 */
1151 static
1152 int compat_get_fd_set(unsigned long nr, compat_ulong_t __user *ufdset,
1153 unsigned long *fdset)
1154 {
1155 if (ufdset) {
1156 return compat_get_bitmap(fdset, ufdset, nr);
1157 } else {
1158 zero_fd_set(nr, fdset);
1159 return 0;
1160 }
1161 }
1162
1163 static
1164 int compat_set_fd_set(unsigned long nr, compat_ulong_t __user *ufdset,
1165 unsigned long *fdset)
1166 {
1167 if (!ufdset)
1168 return 0;
1169 return compat_put_bitmap(ufdset, fdset, nr);
1170 }
1171
1172
1173 /*
1174 * This is a virtual copy of sys_select from fs/select.c and probably
1175 * should be compared to it from time to time
1176 */
1177
1178 /*
1179 * We can actually return ERESTARTSYS instead of EINTR, but I'd
1180 * like to be certain this leads to no problems. So I return
1181 * EINTR just for safety.
1182 *
1183 * Update: ERESTARTSYS breaks at least the xview clock binary, so
1184 * I'm trying ERESTARTNOHAND which restart only when you want to.
1185 */
1186 static int compat_core_sys_select(int n, compat_ulong_t __user *inp,
1187 compat_ulong_t __user *outp, compat_ulong_t __user *exp,
1188 struct timespec64 *end_time)
1189 {
1190 fd_set_bits fds;
1191 void *bits;
1192 int size, max_fds, ret = -EINVAL;
1193 struct fdtable *fdt;
1194 long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
1195
1196 if (n < 0)
1197 goto out_nofds;
1198
1199 /* max_fds can increase, so grab it once to avoid race */
1200 rcu_read_lock();
1201 fdt = files_fdtable(current->files);
1202 max_fds = fdt->max_fds;
1203 rcu_read_unlock();
1204 if (n > max_fds)
1205 n = max_fds;
1206
1207 /*
1208 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
1209 * since we used fdset we need to allocate memory in units of
1210 * long-words.
1211 */
1212 size = FDS_BYTES(n);
1213 bits = stack_fds;
1214 if (size > sizeof(stack_fds) / 6) {
1215 bits = kmalloc(6 * size, GFP_KERNEL);
1216 ret = -ENOMEM;
1217 if (!bits)
1218 goto out_nofds;
1219 }
1220 fds.in = (unsigned long *) bits;
1221 fds.out = (unsigned long *) (bits + size);
1222 fds.ex = (unsigned long *) (bits + 2*size);
1223 fds.res_in = (unsigned long *) (bits + 3*size);
1224 fds.res_out = (unsigned long *) (bits + 4*size);
1225 fds.res_ex = (unsigned long *) (bits + 5*size);
1226
1227 if ((ret = compat_get_fd_set(n, inp, fds.in)) ||
1228 (ret = compat_get_fd_set(n, outp, fds.out)) ||
1229 (ret = compat_get_fd_set(n, exp, fds.ex)))
1230 goto out;
1231 zero_fd_set(n, fds.res_in);
1232 zero_fd_set(n, fds.res_out);
1233 zero_fd_set(n, fds.res_ex);
1234
1235 ret = do_select(n, &fds, end_time);
1236
1237 if (ret < 0)
1238 goto out;
1239 if (!ret) {
1240 ret = -ERESTARTNOHAND;
1241 if (signal_pending(current))
1242 goto out;
1243 ret = 0;
1244 }
1245
1246 if (compat_set_fd_set(n, inp, fds.res_in) ||
1247 compat_set_fd_set(n, outp, fds.res_out) ||
1248 compat_set_fd_set(n, exp, fds.res_ex))
1249 ret = -EFAULT;
1250 out:
1251 if (bits != stack_fds)
1252 kfree(bits);
1253 out_nofds:
1254 return ret;
1255 }
1256
1257 COMPAT_SYSCALL_DEFINE5(select, int, n, compat_ulong_t __user *, inp,
1258 compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,
1259 struct compat_timeval __user *, tvp)
1260 {
1261 struct timespec64 end_time, *to = NULL;
1262 struct compat_timeval tv;
1263 int ret;
1264
1265 if (tvp) {
1266 if (copy_from_user(&tv, tvp, sizeof(tv)))
1267 return -EFAULT;
1268
1269 to = &end_time;
1270 if (poll_select_set_timeout(to,
1271 tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
1272 (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
1273 return -EINVAL;
1274 }
1275
1276 ret = compat_core_sys_select(n, inp, outp, exp, to);
1277 ret = compat_poll_select_copy_remaining(&end_time, tvp, 1, ret);
1278
1279 return ret;
1280 }
1281
1282 struct compat_sel_arg_struct {
1283 compat_ulong_t n;
1284 compat_uptr_t inp;
1285 compat_uptr_t outp;
1286 compat_uptr_t exp;
1287 compat_uptr_t tvp;
1288 };
1289
1290 COMPAT_SYSCALL_DEFINE1(old_select, struct compat_sel_arg_struct __user *, arg)
1291 {
1292 struct compat_sel_arg_struct a;
1293
1294 if (copy_from_user(&a, arg, sizeof(a)))
1295 return -EFAULT;
1296 return compat_sys_select(a.n, compat_ptr(a.inp), compat_ptr(a.outp),
1297 compat_ptr(a.exp), compat_ptr(a.tvp));
1298 }
1299
1300 static long do_compat_pselect(int n, compat_ulong_t __user *inp,
1301 compat_ulong_t __user *outp, compat_ulong_t __user *exp,
1302 struct compat_timespec __user *tsp, compat_sigset_t __user *sigmask,
1303 compat_size_t sigsetsize)
1304 {
1305 sigset_t ksigmask, sigsaved;
1306 struct timespec64 ts, end_time, *to = NULL;
1307 int ret;
1308
1309 if (tsp) {
1310 if (compat_get_timespec64(&ts, tsp))
1311 return -EFAULT;
1312
1313 to = &end_time;
1314 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
1315 return -EINVAL;
1316 }
1317
1318 if (sigmask) {
1319 if (sigsetsize != sizeof(compat_sigset_t))
1320 return -EINVAL;
1321 if (get_compat_sigset(&ksigmask, sigmask))
1322 return -EFAULT;
1323
1324 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
1325 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
1326 }
1327
1328 ret = compat_core_sys_select(n, inp, outp, exp, to);
1329 ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret);
1330
1331 if (ret == -ERESTARTNOHAND) {
1332 /*
1333 * Don't restore the signal mask yet. Let do_signal() deliver
1334 * the signal on the way back to userspace, before the signal
1335 * mask is restored.
1336 */
1337 if (sigmask) {
1338 memcpy(&current->saved_sigmask, &sigsaved,
1339 sizeof(sigsaved));
1340 set_restore_sigmask();
1341 }
1342 } else if (sigmask)
1343 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
1344
1345 return ret;
1346 }
1347
1348 COMPAT_SYSCALL_DEFINE6(pselect6, int, n, compat_ulong_t __user *, inp,
1349 compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,
1350 struct compat_timespec __user *, tsp, void __user *, sig)
1351 {
1352 compat_size_t sigsetsize = 0;
1353 compat_uptr_t up = 0;
1354
1355 if (sig) {
1356 if (!access_ok(VERIFY_READ, sig,
1357 sizeof(compat_uptr_t)+sizeof(compat_size_t)) ||
1358 __get_user(up, (compat_uptr_t __user *)sig) ||
1359 __get_user(sigsetsize,
1360 (compat_size_t __user *)(sig+sizeof(up))))
1361 return -EFAULT;
1362 }
1363 return do_compat_pselect(n, inp, outp, exp, tsp, compat_ptr(up),
1364 sigsetsize);
1365 }
1366
1367 COMPAT_SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds,
1368 unsigned int, nfds, struct compat_timespec __user *, tsp,
1369 const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize)
1370 {
1371 sigset_t ksigmask, sigsaved;
1372 struct timespec64 ts, end_time, *to = NULL;
1373 int ret;
1374
1375 if (tsp) {
1376 if (compat_get_timespec64(&ts, tsp))
1377 return -EFAULT;
1378
1379 to = &end_time;
1380 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
1381 return -EINVAL;
1382 }
1383
1384 if (sigmask) {
1385 if (sigsetsize != sizeof(compat_sigset_t))
1386 return -EINVAL;
1387 if (get_compat_sigset(&ksigmask, sigmask))
1388 return -EFAULT;
1389
1390 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
1391 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
1392 }
1393
1394 ret = do_sys_poll(ufds, nfds, to);
1395
1396 /* We can restart this syscall, usually */
1397 if (ret == -EINTR) {
1398 /*
1399 * Don't restore the signal mask yet. Let do_signal() deliver
1400 * the signal on the way back to userspace, before the signal
1401 * mask is restored.
1402 */
1403 if (sigmask) {
1404 memcpy(&current->saved_sigmask, &sigsaved,
1405 sizeof(sigsaved));
1406 set_restore_sigmask();
1407 }
1408 ret = -ERESTARTNOHAND;
1409 } else if (sigmask)
1410 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
1411
1412 ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret);
1413
1414 return ret;
1415 }
1416 #endif
Linux with added FPC-III support