blob: 3d4f85defeab043998a6b6b4e03264386481e601
1 | /* |
2 | * This file contains the procedures for the handling of select and poll |
3 | * |
4 | * Created for Linux based loosely upon Mathius Lattner's minix |
5 | * patches by Peter MacDonald. Heavily edited by Linus. |
6 | * |
7 | * 4 February 1994 |
8 | * COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS |
9 | * flag set in its personality we do *not* modify the given timeout |
10 | * parameter to reflect time remaining. |
11 | * |
12 | * 24 January 2000 |
13 | * Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation |
14 | * of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian). |
15 | */ |
16 | |
17 | #include <linux/kernel.h> |
18 | #include <linux/sched.h> |
19 | #include <linux/syscalls.h> |
20 | #include <linux/export.h> |
21 | #include <linux/slab.h> |
22 | #include <linux/poll.h> |
23 | #include <linux/personality.h> /* for STICKY_TIMEOUTS */ |
24 | #include <linux/file.h> |
25 | #include <linux/fdtable.h> |
26 | #include <linux/fs.h> |
27 | #include <linux/rcupdate.h> |
28 | #include <linux/hrtimer.h> |
29 | #include <linux/sched/rt.h> |
30 | #include <linux/freezer.h> |
31 | #include <net/busy_poll.h> |
32 | #include <linux/vmalloc.h> |
33 | |
34 | #include <asm/uaccess.h> |
35 | |
36 | |
37 | /* |
38 | * Estimate expected accuracy in ns from a timeval. |
39 | * |
40 | * After quite a bit of churning around, we've settled on |
41 | * a simple thing of taking 0.1% of the timeout as the |
42 | * slack, with a cap of 100 msec. |
43 | * "nice" tasks get a 0.5% slack instead. |
44 | * |
45 | * Consider this comment an open invitation to come up with even |
46 | * better solutions.. |
47 | */ |
48 | |
49 | #define MAX_SLACK (100 * NSEC_PER_MSEC) |
50 | |
51 | static long __estimate_accuracy(struct timespec64 *tv) |
52 | { |
53 | long slack; |
54 | int divfactor = 1000; |
55 | |
56 | if (tv->tv_sec < 0) |
57 | return 0; |
58 | |
59 | if (task_nice(current) > 0) |
60 | divfactor = divfactor / 5; |
61 | |
62 | if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor)) |
63 | return MAX_SLACK; |
64 | |
65 | slack = tv->tv_nsec / divfactor; |
66 | slack += tv->tv_sec * (NSEC_PER_SEC/divfactor); |
67 | |
68 | if (slack > MAX_SLACK) |
69 | return MAX_SLACK; |
70 | |
71 | return slack; |
72 | } |
73 | |
74 | u64 select_estimate_accuracy(struct timespec64 *tv) |
75 | { |
76 | u64 ret; |
77 | struct timespec64 now; |
78 | |
79 | /* |
80 | * Realtime tasks get a slack of 0 for obvious reasons. |
81 | */ |
82 | |
83 | if (rt_task(current)) |
84 | return 0; |
85 | |
86 | ktime_get_ts64(&now); |
87 | now = timespec64_sub(*tv, now); |
88 | ret = __estimate_accuracy(&now); |
89 | if (ret < current->timer_slack_ns) |
90 | return current->timer_slack_ns; |
91 | return ret; |
92 | } |
93 | |
94 | |
95 | |
96 | struct poll_table_page { |
97 | struct poll_table_page * next; |
98 | struct poll_table_entry * entry; |
99 | struct poll_table_entry entries[0]; |
100 | }; |
101 | |
102 | #define POLL_TABLE_FULL(table) \ |
103 | ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table)) |
104 | |
105 | /* |
106 | * Ok, Peter made a complicated, but straightforward multiple_wait() function. |
107 | * I have rewritten this, taking some shortcuts: This code may not be easy to |
108 | * follow, but it should be free of race-conditions, and it's practical. If you |
109 | * understand what I'm doing here, then you understand how the linux |
110 | * sleep/wakeup mechanism works. |
111 | * |
112 | * Two very simple procedures, poll_wait() and poll_freewait() make all the |
113 | * work. poll_wait() is an inline-function defined in <linux/poll.h>, |
114 | * as all select/poll functions have to call it to add an entry to the |
115 | * poll table. |
116 | */ |
117 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, |
118 | poll_table *p); |
119 | |
120 | void poll_initwait(struct poll_wqueues *pwq) |
121 | { |
122 | init_poll_funcptr(&pwq->pt, __pollwait); |
123 | pwq->polling_task = current; |
124 | pwq->triggered = 0; |
125 | pwq->error = 0; |
126 | pwq->table = NULL; |
127 | pwq->inline_index = 0; |
128 | } |
129 | EXPORT_SYMBOL(poll_initwait); |
130 | |
131 | static void free_poll_entry(struct poll_table_entry *entry) |
132 | { |
133 | remove_wait_queue(entry->wait_address, &entry->wait); |
134 | fput(entry->filp); |
135 | } |
136 | |
137 | void poll_freewait(struct poll_wqueues *pwq) |
138 | { |
139 | struct poll_table_page * p = pwq->table; |
140 | int i; |
141 | for (i = 0; i < pwq->inline_index; i++) |
142 | free_poll_entry(pwq->inline_entries + i); |
143 | while (p) { |
144 | struct poll_table_entry * entry; |
145 | struct poll_table_page *old; |
146 | |
147 | entry = p->entry; |
148 | do { |
149 | entry--; |
150 | free_poll_entry(entry); |
151 | } while (entry > p->entries); |
152 | old = p; |
153 | p = p->next; |
154 | free_page((unsigned long) old); |
155 | } |
156 | } |
157 | EXPORT_SYMBOL(poll_freewait); |
158 | |
159 | static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p) |
160 | { |
161 | struct poll_table_page *table = p->table; |
162 | |
163 | if (p->inline_index < N_INLINE_POLL_ENTRIES) |
164 | return p->inline_entries + p->inline_index++; |
165 | |
166 | if (!table || POLL_TABLE_FULL(table)) { |
167 | struct poll_table_page *new_table; |
168 | |
169 | new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL); |
170 | if (!new_table) { |
171 | p->error = -ENOMEM; |
172 | return NULL; |
173 | } |
174 | new_table->entry = new_table->entries; |
175 | new_table->next = table; |
176 | p->table = new_table; |
177 | table = new_table; |
178 | } |
179 | |
180 | return table->entry++; |
181 | } |
182 | |
183 | static int __pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key) |
184 | { |
185 | struct poll_wqueues *pwq = wait->private; |
186 | DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task); |
187 | |
188 | /* |
189 | * Although this function is called under waitqueue lock, LOCK |
190 | * doesn't imply write barrier and the users expect write |
191 | * barrier semantics on wakeup functions. The following |
192 | * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up() |
193 | * and is paired with smp_store_mb() in poll_schedule_timeout. |
194 | */ |
195 | smp_wmb(); |
196 | pwq->triggered = 1; |
197 | |
198 | /* |
199 | * Perform the default wake up operation using a dummy |
200 | * waitqueue. |
201 | * |
202 | * TODO: This is hacky but there currently is no interface to |
203 | * pass in @sync. @sync is scheduled to be removed and once |
204 | * that happens, wake_up_process() can be used directly. |
205 | */ |
206 | return default_wake_function(&dummy_wait, mode, sync, key); |
207 | } |
208 | |
209 | static int pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key) |
210 | { |
211 | struct poll_table_entry *entry; |
212 | |
213 | entry = container_of(wait, struct poll_table_entry, wait); |
214 | if (key && !((unsigned long)key & entry->key)) |
215 | return 0; |
216 | return __pollwake(wait, mode, sync, key); |
217 | } |
218 | |
219 | /* Add a new entry */ |
220 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, |
221 | poll_table *p) |
222 | { |
223 | struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt); |
224 | struct poll_table_entry *entry = poll_get_entry(pwq); |
225 | if (!entry) |
226 | return; |
227 | entry->filp = get_file(filp); |
228 | entry->wait_address = wait_address; |
229 | entry->key = p->_key; |
230 | init_waitqueue_func_entry(&entry->wait, pollwake); |
231 | entry->wait.private = pwq; |
232 | add_wait_queue(wait_address, &entry->wait); |
233 | } |
234 | |
235 | int poll_schedule_timeout(struct poll_wqueues *pwq, int state, |
236 | ktime_t *expires, unsigned long slack) |
237 | { |
238 | int rc = -EINTR; |
239 | |
240 | set_current_state(state); |
241 | if (!pwq->triggered) |
242 | rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS); |
243 | __set_current_state(TASK_RUNNING); |
244 | |
245 | /* |
246 | * Prepare for the next iteration. |
247 | * |
248 | * The following smp_store_mb() serves two purposes. First, it's |
249 | * the counterpart rmb of the wmb in pollwake() such that data |
250 | * written before wake up is always visible after wake up. |
251 | * Second, the full barrier guarantees that triggered clearing |
252 | * doesn't pass event check of the next iteration. Note that |
253 | * this problem doesn't exist for the first iteration as |
254 | * add_wait_queue() has full barrier semantics. |
255 | */ |
256 | smp_store_mb(pwq->triggered, 0); |
257 | |
258 | return rc; |
259 | } |
260 | EXPORT_SYMBOL(poll_schedule_timeout); |
261 | |
262 | /** |
263 | * poll_select_set_timeout - helper function to setup the timeout value |
264 | * @to: pointer to timespec64 variable for the final timeout |
265 | * @sec: seconds (from user space) |
266 | * @nsec: nanoseconds (from user space) |
267 | * |
268 | * Note, we do not use a timespec for the user space value here, That |
269 | * way we can use the function for timeval and compat interfaces as well. |
270 | * |
271 | * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0. |
272 | */ |
273 | int poll_select_set_timeout(struct timespec64 *to, time64_t sec, long nsec) |
274 | { |
275 | struct timespec64 ts = {.tv_sec = sec, .tv_nsec = nsec}; |
276 | |
277 | if (!timespec64_valid(&ts)) |
278 | return -EINVAL; |
279 | |
280 | /* Optimize for the zero timeout value here */ |
281 | if (!sec && !nsec) { |
282 | to->tv_sec = to->tv_nsec = 0; |
283 | } else { |
284 | ktime_get_ts64(to); |
285 | *to = timespec64_add_safe(*to, ts); |
286 | } |
287 | return 0; |
288 | } |
289 | |
290 | static int poll_select_copy_remaining(struct timespec64 *end_time, |
291 | void __user *p, |
292 | int timeval, int ret) |
293 | { |
294 | struct timespec64 rts64; |
295 | struct timespec 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(&rts64); |
309 | rts64 = timespec64_sub(*end_time, rts64); |
310 | if (rts64.tv_sec < 0) |
311 | rts64.tv_sec = rts64.tv_nsec = 0; |
312 | |
313 | rts = timespec64_to_timespec(rts64); |
314 | |
315 | if (timeval) { |
316 | if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec)) |
317 | memset(&rtv, 0, sizeof(rtv)); |
318 | rtv.tv_sec = rts64.tv_sec; |
319 | rtv.tv_usec = rts64.tv_nsec / NSEC_PER_USEC; |
320 | |
321 | if (!copy_to_user(p, &rtv, sizeof(rtv))) |
322 | return ret; |
323 | |
324 | } else if (!copy_to_user(p, &rts, sizeof(rts))) |
325 | return ret; |
326 | |
327 | /* |
328 | * If an application puts its timeval in read-only memory, we |
329 | * don't want the Linux-specific update to the timeval to |
330 | * cause a fault after the select has completed |
331 | * successfully. However, because we're not updating the |
332 | * timeval, we can't restart the system call. |
333 | */ |
334 | |
335 | sticky: |
336 | if (ret == -ERESTARTNOHAND) |
337 | ret = -EINTR; |
338 | return ret; |
339 | } |
340 | |
341 | #define FDS_IN(fds, n) (fds->in + n) |
342 | #define FDS_OUT(fds, n) (fds->out + n) |
343 | #define FDS_EX(fds, n) (fds->ex + n) |
344 | |
345 | #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n)) |
346 | |
347 | static int max_select_fd(unsigned long n, fd_set_bits *fds) |
348 | { |
349 | unsigned long *open_fds; |
350 | unsigned long set; |
351 | int max; |
352 | struct fdtable *fdt; |
353 | |
354 | /* handle last in-complete long-word first */ |
355 | set = ~(~0UL << (n & (BITS_PER_LONG-1))); |
356 | n /= BITS_PER_LONG; |
357 | fdt = files_fdtable(current->files); |
358 | open_fds = fdt->open_fds + n; |
359 | max = 0; |
360 | if (set) { |
361 | set &= BITS(fds, n); |
362 | if (set) { |
363 | if (!(set & ~*open_fds)) |
364 | goto get_max; |
365 | return -EBADF; |
366 | } |
367 | } |
368 | while (n) { |
369 | open_fds--; |
370 | n--; |
371 | set = BITS(fds, n); |
372 | if (!set) |
373 | continue; |
374 | if (set & ~*open_fds) |
375 | return -EBADF; |
376 | if (max) |
377 | continue; |
378 | get_max: |
379 | do { |
380 | max++; |
381 | set >>= 1; |
382 | } while (set); |
383 | max += n * BITS_PER_LONG; |
384 | } |
385 | |
386 | return max; |
387 | } |
388 | |
389 | #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR) |
390 | #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR) |
391 | #define POLLEX_SET (POLLPRI) |
392 | |
393 | static inline void wait_key_set(poll_table *wait, unsigned long in, |
394 | unsigned long out, unsigned long bit, |
395 | unsigned int ll_flag) |
396 | { |
397 | wait->_key = POLLEX_SET | ll_flag; |
398 | if (in & bit) |
399 | wait->_key |= POLLIN_SET; |
400 | if (out & bit) |
401 | wait->_key |= POLLOUT_SET; |
402 | } |
403 | |
404 | int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time) |
405 | { |
406 | ktime_t expire, *to = NULL; |
407 | struct poll_wqueues table; |
408 | poll_table *wait; |
409 | int retval, i, timed_out = 0; |
410 | u64 slack = 0; |
411 | unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; |
412 | unsigned long busy_end = 0; |
413 | |
414 | rcu_read_lock(); |
415 | retval = max_select_fd(n, fds); |
416 | rcu_read_unlock(); |
417 | |
418 | if (retval < 0) |
419 | return retval; |
420 | n = retval; |
421 | |
422 | poll_initwait(&table); |
423 | wait = &table.pt; |
424 | if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { |
425 | wait->_qproc = NULL; |
426 | timed_out = 1; |
427 | } |
428 | |
429 | if (end_time && !timed_out) |
430 | slack = select_estimate_accuracy(end_time); |
431 | |
432 | retval = 0; |
433 | for (;;) { |
434 | unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp; |
435 | bool can_busy_loop = false; |
436 | |
437 | inp = fds->in; outp = fds->out; exp = fds->ex; |
438 | rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex; |
439 | |
440 | for (i = 0; i < n; ++rinp, ++routp, ++rexp) { |
441 | unsigned long in, out, ex, all_bits, bit = 1, mask, j; |
442 | unsigned long res_in = 0, res_out = 0, res_ex = 0; |
443 | |
444 | in = *inp++; out = *outp++; ex = *exp++; |
445 | all_bits = in | out | ex; |
446 | if (all_bits == 0) { |
447 | i += BITS_PER_LONG; |
448 | continue; |
449 | } |
450 | |
451 | for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) { |
452 | struct fd f; |
453 | if (i >= n) |
454 | break; |
455 | if (!(bit & all_bits)) |
456 | continue; |
457 | f = fdget(i); |
458 | if (f.file) { |
459 | const struct file_operations *f_op; |
460 | f_op = f.file->f_op; |
461 | mask = DEFAULT_POLLMASK; |
462 | if (f_op->poll) { |
463 | wait_key_set(wait, in, out, |
464 | bit, busy_flag); |
465 | mask = (*f_op->poll)(f.file, wait); |
466 | } |
467 | fdput(f); |
468 | if ((mask & POLLIN_SET) && (in & bit)) { |
469 | res_in |= bit; |
470 | retval++; |
471 | wait->_qproc = NULL; |
472 | } |
473 | if ((mask & POLLOUT_SET) && (out & bit)) { |
474 | res_out |= bit; |
475 | retval++; |
476 | wait->_qproc = NULL; |
477 | } |
478 | if ((mask & POLLEX_SET) && (ex & bit)) { |
479 | res_ex |= bit; |
480 | retval++; |
481 | wait->_qproc = NULL; |
482 | } |
483 | /* got something, stop busy polling */ |
484 | if (retval) { |
485 | can_busy_loop = false; |
486 | busy_flag = 0; |
487 | |
488 | /* |
489 | * only remember a returned |
490 | * POLL_BUSY_LOOP if we asked for it |
491 | */ |
492 | } else if (busy_flag & mask) |
493 | can_busy_loop = true; |
494 | |
495 | } |
496 | } |
497 | if (res_in) |
498 | *rinp = res_in; |
499 | if (res_out) |
500 | *routp = res_out; |
501 | if (res_ex) |
502 | *rexp = res_ex; |
503 | cond_resched(); |
504 | } |
505 | wait->_qproc = NULL; |
506 | if (retval || timed_out || signal_pending(current)) |
507 | break; |
508 | if (table.error) { |
509 | retval = table.error; |
510 | break; |
511 | } |
512 | |
513 | /* only if found POLL_BUSY_LOOP sockets && not out of time */ |
514 | if (can_busy_loop && !need_resched()) { |
515 | if (!busy_end) { |
516 | busy_end = busy_loop_end_time(); |
517 | continue; |
518 | } |
519 | if (!busy_loop_timeout(busy_end)) |
520 | continue; |
521 | } |
522 | busy_flag = 0; |
523 | |
524 | /* |
525 | * If this is the first loop and we have a timeout |
526 | * given, then we convert to ktime_t and set the to |
527 | * pointer to the expiry value. |
528 | */ |
529 | if (end_time && !to) { |
530 | expire = timespec64_to_ktime(*end_time); |
531 | to = &expire; |
532 | } |
533 | |
534 | if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE, |
535 | to, slack)) |
536 | timed_out = 1; |
537 | } |
538 | |
539 | poll_freewait(&table); |
540 | |
541 | return retval; |
542 | } |
543 | |
544 | /* |
545 | * We can actually return ERESTARTSYS instead of EINTR, but I'd |
546 | * like to be certain this leads to no problems. So I return |
547 | * EINTR just for safety. |
548 | * |
549 | * Update: ERESTARTSYS breaks at least the xview clock binary, so |
550 | * I'm trying ERESTARTNOHAND which restart only when you want to. |
551 | */ |
552 | int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, |
553 | fd_set __user *exp, struct timespec64 *end_time) |
554 | { |
555 | fd_set_bits fds; |
556 | void *bits; |
557 | int ret, max_fds; |
558 | size_t size, alloc_size; |
559 | struct fdtable *fdt; |
560 | /* Allocate small arguments on the stack to save memory and be faster */ |
561 | long stack_fds[SELECT_STACK_ALLOC/sizeof(long)]; |
562 | |
563 | ret = -EINVAL; |
564 | if (n < 0) |
565 | goto out_nofds; |
566 | |
567 | /* max_fds can increase, so grab it once to avoid race */ |
568 | rcu_read_lock(); |
569 | fdt = files_fdtable(current->files); |
570 | max_fds = fdt->max_fds; |
571 | rcu_read_unlock(); |
572 | if (n > max_fds) |
573 | n = max_fds; |
574 | |
575 | /* |
576 | * We need 6 bitmaps (in/out/ex for both incoming and outgoing), |
577 | * since we used fdset we need to allocate memory in units of |
578 | * long-words. |
579 | */ |
580 | size = FDS_BYTES(n); |
581 | bits = stack_fds; |
582 | if (size > sizeof(stack_fds) / 6) { |
583 | /* Not enough space in on-stack array; must use kmalloc */ |
584 | ret = -ENOMEM; |
585 | if (size > (SIZE_MAX / 6)) |
586 | goto out_nofds; |
587 | |
588 | alloc_size = 6 * size; |
589 | bits = kmalloc(alloc_size, GFP_KERNEL|__GFP_NOWARN); |
590 | if (!bits && alloc_size > PAGE_SIZE) |
591 | bits = vmalloc(alloc_size); |
592 | |
593 | if (!bits) |
594 | goto out_nofds; |
595 | } |
596 | fds.in = bits; |
597 | fds.out = bits + size; |
598 | fds.ex = bits + 2*size; |
599 | fds.res_in = bits + 3*size; |
600 | fds.res_out = bits + 4*size; |
601 | fds.res_ex = bits + 5*size; |
602 | |
603 | if ((ret = get_fd_set(n, inp, fds.in)) || |
604 | (ret = get_fd_set(n, outp, fds.out)) || |
605 | (ret = get_fd_set(n, exp, fds.ex))) |
606 | goto out; |
607 | zero_fd_set(n, fds.res_in); |
608 | zero_fd_set(n, fds.res_out); |
609 | zero_fd_set(n, fds.res_ex); |
610 | |
611 | ret = do_select(n, &fds, end_time); |
612 | |
613 | if (ret < 0) |
614 | goto out; |
615 | if (!ret) { |
616 | ret = -ERESTARTNOHAND; |
617 | if (signal_pending(current)) |
618 | goto out; |
619 | ret = 0; |
620 | } |
621 | |
622 | if (set_fd_set(n, inp, fds.res_in) || |
623 | set_fd_set(n, outp, fds.res_out) || |
624 | set_fd_set(n, exp, fds.res_ex)) |
625 | ret = -EFAULT; |
626 | |
627 | out: |
628 | if (bits != stack_fds) |
629 | kvfree(bits); |
630 | out_nofds: |
631 | return ret; |
632 | } |
633 | |
634 | SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp, |
635 | fd_set __user *, exp, struct timeval __user *, tvp) |
636 | { |
637 | struct timespec64 end_time, *to = NULL; |
638 | struct timeval tv; |
639 | int ret; |
640 | |
641 | if (tvp) { |
642 | if (copy_from_user(&tv, tvp, sizeof(tv))) |
643 | return -EFAULT; |
644 | |
645 | to = &end_time; |
646 | if (poll_select_set_timeout(to, |
647 | tv.tv_sec + (tv.tv_usec / USEC_PER_SEC), |
648 | (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC)) |
649 | return -EINVAL; |
650 | } |
651 | |
652 | ret = core_sys_select(n, inp, outp, exp, to); |
653 | ret = poll_select_copy_remaining(&end_time, tvp, 1, ret); |
654 | |
655 | return ret; |
656 | } |
657 | |
658 | static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp, |
659 | fd_set __user *exp, struct timespec __user *tsp, |
660 | const sigset_t __user *sigmask, size_t sigsetsize) |
661 | { |
662 | sigset_t ksigmask, sigsaved; |
663 | struct timespec ts; |
664 | struct timespec64 ts64, end_time, *to = NULL; |
665 | int ret; |
666 | |
667 | if (tsp) { |
668 | if (copy_from_user(&ts, tsp, sizeof(ts))) |
669 | return -EFAULT; |
670 | ts64 = timespec_to_timespec64(ts); |
671 | |
672 | to = &end_time; |
673 | if (poll_select_set_timeout(to, ts64.tv_sec, ts64.tv_nsec)) |
674 | return -EINVAL; |
675 | } |
676 | |
677 | if (sigmask) { |
678 | /* XXX: Don't preclude handling different sized sigset_t's. */ |
679 | if (sigsetsize != sizeof(sigset_t)) |
680 | return -EINVAL; |
681 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) |
682 | return -EFAULT; |
683 | |
684 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
685 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); |
686 | } |
687 | |
688 | ret = core_sys_select(n, inp, outp, exp, to); |
689 | ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); |
690 | |
691 | if (ret == -ERESTARTNOHAND) { |
692 | /* |
693 | * Don't restore the signal mask yet. Let do_signal() deliver |
694 | * the signal on the way back to userspace, before the signal |
695 | * mask is restored. |
696 | */ |
697 | if (sigmask) { |
698 | memcpy(¤t->saved_sigmask, &sigsaved, |
699 | sizeof(sigsaved)); |
700 | set_restore_sigmask(); |
701 | } |
702 | } else if (sigmask) |
703 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); |
704 | |
705 | return ret; |
706 | } |
707 | |
708 | /* |
709 | * Most architectures can't handle 7-argument syscalls. So we provide a |
710 | * 6-argument version where the sixth argument is a pointer to a structure |
711 | * which has a pointer to the sigset_t itself followed by a size_t containing |
712 | * the sigset size. |
713 | */ |
714 | SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp, |
715 | fd_set __user *, exp, struct timespec __user *, tsp, |
716 | void __user *, sig) |
717 | { |
718 | size_t sigsetsize = 0; |
719 | sigset_t __user *up = NULL; |
720 | |
721 | if (sig) { |
722 | if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t)) |
723 | || __get_user(up, (sigset_t __user * __user *)sig) |
724 | || __get_user(sigsetsize, |
725 | (size_t __user *)(sig+sizeof(void *)))) |
726 | return -EFAULT; |
727 | } |
728 | |
729 | return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize); |
730 | } |
731 | |
732 | #ifdef __ARCH_WANT_SYS_OLD_SELECT |
733 | struct sel_arg_struct { |
734 | unsigned long n; |
735 | fd_set __user *inp, *outp, *exp; |
736 | struct timeval __user *tvp; |
737 | }; |
738 | |
739 | SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg) |
740 | { |
741 | struct sel_arg_struct a; |
742 | |
743 | if (copy_from_user(&a, arg, sizeof(a))) |
744 | return -EFAULT; |
745 | return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp); |
746 | } |
747 | #endif |
748 | |
749 | struct poll_list { |
750 | struct poll_list *next; |
751 | int len; |
752 | struct pollfd entries[0]; |
753 | }; |
754 | |
755 | #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd)) |
756 | |
757 | /* |
758 | * Fish for pollable events on the pollfd->fd file descriptor. We're only |
759 | * interested in events matching the pollfd->events mask, and the result |
760 | * matching that mask is both recorded in pollfd->revents and returned. The |
761 | * pwait poll_table will be used by the fd-provided poll handler for waiting, |
762 | * if pwait->_qproc is non-NULL. |
763 | */ |
764 | static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait, |
765 | bool *can_busy_poll, |
766 | unsigned int busy_flag) |
767 | { |
768 | unsigned int mask; |
769 | int fd; |
770 | |
771 | mask = 0; |
772 | fd = pollfd->fd; |
773 | if (fd >= 0) { |
774 | struct fd f = fdget(fd); |
775 | mask = POLLNVAL; |
776 | if (f.file) { |
777 | mask = DEFAULT_POLLMASK; |
778 | if (f.file->f_op->poll) { |
779 | pwait->_key = pollfd->events|POLLERR|POLLHUP; |
780 | pwait->_key |= busy_flag; |
781 | mask = f.file->f_op->poll(f.file, pwait); |
782 | if (mask & busy_flag) |
783 | *can_busy_poll = true; |
784 | } |
785 | /* Mask out unneeded events. */ |
786 | mask &= pollfd->events | POLLERR | POLLHUP; |
787 | fdput(f); |
788 | } |
789 | } |
790 | pollfd->revents = mask; |
791 | |
792 | return mask; |
793 | } |
794 | |
795 | static int do_poll(struct poll_list *list, struct poll_wqueues *wait, |
796 | struct timespec64 *end_time) |
797 | { |
798 | poll_table* pt = &wait->pt; |
799 | ktime_t expire, *to = NULL; |
800 | int timed_out = 0, count = 0; |
801 | u64 slack = 0; |
802 | unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; |
803 | unsigned long busy_end = 0; |
804 | |
805 | /* Optimise the no-wait case */ |
806 | if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { |
807 | pt->_qproc = NULL; |
808 | timed_out = 1; |
809 | } |
810 | |
811 | if (end_time && !timed_out) |
812 | slack = select_estimate_accuracy(end_time); |
813 | |
814 | for (;;) { |
815 | struct poll_list *walk; |
816 | bool can_busy_loop = false; |
817 | |
818 | for (walk = list; walk != NULL; walk = walk->next) { |
819 | struct pollfd * pfd, * pfd_end; |
820 | |
821 | pfd = walk->entries; |
822 | pfd_end = pfd + walk->len; |
823 | for (; pfd != pfd_end; pfd++) { |
824 | /* |
825 | * Fish for events. If we found one, record it |
826 | * and kill poll_table->_qproc, so we don't |
827 | * needlessly register any other waiters after |
828 | * this. They'll get immediately deregistered |
829 | * when we break out and return. |
830 | */ |
831 | if (do_pollfd(pfd, pt, &can_busy_loop, |
832 | busy_flag)) { |
833 | count++; |
834 | pt->_qproc = NULL; |
835 | /* found something, stop busy polling */ |
836 | busy_flag = 0; |
837 | can_busy_loop = false; |
838 | } |
839 | } |
840 | } |
841 | /* |
842 | * All waiters have already been registered, so don't provide |
843 | * a poll_table->_qproc to them on the next loop iteration. |
844 | */ |
845 | pt->_qproc = NULL; |
846 | if (!count) { |
847 | count = wait->error; |
848 | if (signal_pending(current)) |
849 | count = -EINTR; |
850 | } |
851 | if (count || timed_out) |
852 | break; |
853 | |
854 | /* only if found POLL_BUSY_LOOP sockets && not out of time */ |
855 | if (can_busy_loop && !need_resched()) { |
856 | if (!busy_end) { |
857 | busy_end = busy_loop_end_time(); |
858 | continue; |
859 | } |
860 | if (!busy_loop_timeout(busy_end)) |
861 | continue; |
862 | } |
863 | busy_flag = 0; |
864 | |
865 | /* |
866 | * If this is the first loop and we have a timeout |
867 | * given, then we convert to ktime_t and set the to |
868 | * pointer to the expiry value. |
869 | */ |
870 | if (end_time && !to) { |
871 | expire = timespec64_to_ktime(*end_time); |
872 | to = &expire; |
873 | } |
874 | |
875 | if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack)) |
876 | timed_out = 1; |
877 | } |
878 | return count; |
879 | } |
880 | |
881 | #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \ |
882 | sizeof(struct pollfd)) |
883 | |
884 | int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, |
885 | struct timespec64 *end_time) |
886 | { |
887 | struct poll_wqueues table; |
888 | int err = -EFAULT, fdcount, len, size; |
889 | /* Allocate small arguments on the stack to save memory and be |
890 | faster - use long to make sure the buffer is aligned properly |
891 | on 64 bit archs to avoid unaligned access */ |
892 | long stack_pps[POLL_STACK_ALLOC/sizeof(long)]; |
893 | struct poll_list *const head = (struct poll_list *)stack_pps; |
894 | struct poll_list *walk = head; |
895 | unsigned long todo = nfds; |
896 | |
897 | if (nfds > rlimit(RLIMIT_NOFILE)) |
898 | return -EINVAL; |
899 | |
900 | len = min_t(unsigned int, nfds, N_STACK_PPS); |
901 | for (;;) { |
902 | walk->next = NULL; |
903 | walk->len = len; |
904 | if (!len) |
905 | break; |
906 | |
907 | if (copy_from_user(walk->entries, ufds + nfds-todo, |
908 | sizeof(struct pollfd) * walk->len)) |
909 | goto out_fds; |
910 | |
911 | todo -= walk->len; |
912 | if (!todo) |
913 | break; |
914 | |
915 | len = min(todo, POLLFD_PER_PAGE); |
916 | size = sizeof(struct poll_list) + sizeof(struct pollfd) * len; |
917 | walk = walk->next = kmalloc(size, GFP_KERNEL); |
918 | if (!walk) { |
919 | err = -ENOMEM; |
920 | goto out_fds; |
921 | } |
922 | } |
923 | |
924 | poll_initwait(&table); |
925 | fdcount = do_poll(head, &table, end_time); |
926 | poll_freewait(&table); |
927 | |
928 | for (walk = head; walk; walk = walk->next) { |
929 | struct pollfd *fds = walk->entries; |
930 | int j; |
931 | |
932 | for (j = 0; j < walk->len; j++, ufds++) |
933 | if (__put_user(fds[j].revents, &ufds->revents)) |
934 | goto out_fds; |
935 | } |
936 | |
937 | err = fdcount; |
938 | out_fds: |
939 | walk = head->next; |
940 | while (walk) { |
941 | struct poll_list *pos = walk; |
942 | walk = walk->next; |
943 | kfree(pos); |
944 | } |
945 | |
946 | return err; |
947 | } |
948 | |
949 | static long do_restart_poll(struct restart_block *restart_block) |
950 | { |
951 | struct pollfd __user *ufds = restart_block->poll.ufds; |
952 | int nfds = restart_block->poll.nfds; |
953 | struct timespec64 *to = NULL, end_time; |
954 | int ret; |
955 | |
956 | if (restart_block->poll.has_timeout) { |
957 | end_time.tv_sec = restart_block->poll.tv_sec; |
958 | end_time.tv_nsec = restart_block->poll.tv_nsec; |
959 | to = &end_time; |
960 | } |
961 | |
962 | ret = do_sys_poll(ufds, nfds, to); |
963 | |
964 | if (ret == -EINTR) { |
965 | restart_block->fn = do_restart_poll; |
966 | ret = -ERESTART_RESTARTBLOCK; |
967 | } |
968 | return ret; |
969 | } |
970 | |
971 | SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds, |
972 | int, timeout_msecs) |
973 | { |
974 | struct timespec64 end_time, *to = NULL; |
975 | int ret; |
976 | |
977 | if (timeout_msecs >= 0) { |
978 | to = &end_time; |
979 | poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC, |
980 | NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC)); |
981 | } |
982 | |
983 | ret = do_sys_poll(ufds, nfds, to); |
984 | |
985 | if (ret == -EINTR) { |
986 | struct restart_block *restart_block; |
987 | |
988 | restart_block = ¤t->restart_block; |
989 | restart_block->fn = do_restart_poll; |
990 | restart_block->poll.ufds = ufds; |
991 | restart_block->poll.nfds = nfds; |
992 | |
993 | if (timeout_msecs >= 0) { |
994 | restart_block->poll.tv_sec = end_time.tv_sec; |
995 | restart_block->poll.tv_nsec = end_time.tv_nsec; |
996 | restart_block->poll.has_timeout = 1; |
997 | } else |
998 | restart_block->poll.has_timeout = 0; |
999 | |
1000 | ret = -ERESTART_RESTARTBLOCK; |
1001 | } |
1002 | return ret; |
1003 | } |
1004 | |
1005 | SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds, |
1006 | struct timespec __user *, tsp, const sigset_t __user *, sigmask, |
1007 | size_t, sigsetsize) |
1008 | { |
1009 | sigset_t ksigmask, sigsaved; |
1010 | struct timespec ts; |
1011 | struct timespec64 end_time, *to = NULL; |
1012 | int ret; |
1013 | |
1014 | if (tsp) { |
1015 | if (copy_from_user(&ts, tsp, sizeof(ts))) |
1016 | return -EFAULT; |
1017 | |
1018 | to = &end_time; |
1019 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) |
1020 | return -EINVAL; |
1021 | } |
1022 | |
1023 | if (sigmask) { |
1024 | /* XXX: Don't preclude handling different sized sigset_t's. */ |
1025 | if (sigsetsize != sizeof(sigset_t)) |
1026 | return -EINVAL; |
1027 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) |
1028 | return -EFAULT; |
1029 | |
1030 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); |
1031 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); |
1032 | } |
1033 | |
1034 | ret = do_sys_poll(ufds, nfds, to); |
1035 | |
1036 | /* We can restart this syscall, usually */ |
1037 | if (ret == -EINTR) { |
1038 | /* |
1039 | * Don't restore the signal mask yet. Let do_signal() deliver |
1040 | * the signal on the way back to userspace, before the signal |
1041 | * mask is restored. |
1042 | */ |
1043 | if (sigmask) { |
1044 | memcpy(¤t->saved_sigmask, &sigsaved, |
1045 | sizeof(sigsaved)); |
1046 | set_restore_sigmask(); |
1047 | } |
1048 | ret = -ERESTARTNOHAND; |
1049 | } else if (sigmask) |
1050 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); |
1051 | |
1052 | ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); |
1053 | |
1054 | return ret; |
1055 | } |
1056 |