linux/fs/select.c
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   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
  52static 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
  75u64 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
  97struct 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 */
 118static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
 119                       poll_table *p);
 120
 121void 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}
 130EXPORT_SYMBOL(poll_initwait);
 131
 132static 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
 138void 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}
 158EXPORT_SYMBOL(poll_freewait);
 159
 160static 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
 184static 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
 210static 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 && !(key_to_poll(key) & entry->key))
 216                return 0;
 217        return __pollwake(wait, mode, sync, key);
 218}
 219
 220/* Add a new entry */
 221static 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
 236static 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
 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 */
 273int 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
 290static int poll_select_copy_remaining(struct timespec64 *end_time,
 291                                      void __user *p,
 292                                      int timeval, int ret)
 293{
 294        struct timespec64 rts;
 295        struct timeval rtv;
 296
 297        if (!p)
 298                return ret;
 299
 300        if (current->personality & STICKY_TIMEOUTS)
 301                goto sticky;
 302
 303        /* No update for zero timeout */
 304        if (!end_time->tv_sec && !end_time->tv_nsec)
 305                return ret;
 306
 307        ktime_get_ts64(&rts);
 308        rts = timespec64_sub(*end_time, rts);
 309        if (rts.tv_sec < 0)
 310                rts.tv_sec = rts.tv_nsec = 0;
 311
 312
 313        if (timeval) {
 314                if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec))
 315                        memset(&rtv, 0, sizeof(rtv));
 316                rtv.tv_sec = rts.tv_sec;
 317                rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;
 318
 319                if (!copy_to_user(p, &rtv, sizeof(rtv)))
 320                        return ret;
 321
 322        } else if (!put_timespec64(&rts, p))
 323                return ret;
 324
 325        /*
 326         * If an application puts its timeval in read-only memory, we
 327         * don't want the Linux-specific update to the timeval to
 328         * cause a fault after the select has completed
 329         * successfully. However, because we're not updating the
 330         * timeval, we can't restart the system call.
 331         */
 332
 333sticky:
 334        if (ret == -ERESTARTNOHAND)
 335                ret = -EINTR;
 336        return ret;
 337}
 338
 339/*
 340 * Scalable version of the fd_set.
 341 */
 342
 343typedef struct {
 344        unsigned long *in, *out, *ex;
 345        unsigned long *res_in, *res_out, *res_ex;
 346} fd_set_bits;
 347
 348/*
 349 * How many longwords for "nr" bits?
 350 */
 351#define FDS_BITPERLONG  (8*sizeof(long))
 352#define FDS_LONGS(nr)   (((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
 353#define FDS_BYTES(nr)   (FDS_LONGS(nr)*sizeof(long))
 354
 355/*
 356 * We do a VERIFY_WRITE here even though we are only reading this time:
 357 * we'll write to it eventually..
 358 *
 359 * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
 360 */
 361static inline
 362int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
 363{
 364        nr = FDS_BYTES(nr);
 365        if (ufdset)
 366                return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
 367
 368        memset(fdset, 0, nr);
 369        return 0;
 370}
 371
 372static inline unsigned long __must_check
 373set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
 374{
 375        if (ufdset)
 376                return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
 377        return 0;
 378}
 379
 380static inline
 381void zero_fd_set(unsigned long nr, unsigned long *fdset)
 382{
 383        memset(fdset, 0, FDS_BYTES(nr));
 384}
 385
 386#define FDS_IN(fds, n)          (fds->in + n)
 387#define FDS_OUT(fds, n)         (fds->out + n)
 388#define FDS_EX(fds, n)          (fds->ex + n)
 389
 390#define BITS(fds, n)    (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
 391
 392static int max_select_fd(unsigned long n, fd_set_bits *fds)
 393{
 394        unsigned long *open_fds;
 395        unsigned long set;
 396        int max;
 397        struct fdtable *fdt;
 398
 399        /* handle last in-complete long-word first */
 400        set = ~(~0UL << (n & (BITS_PER_LONG-1)));
 401        n /= BITS_PER_LONG;
 402        fdt = files_fdtable(current->files);
 403        open_fds = fdt->open_fds + n;
 404        max = 0;
 405        if (set) {
 406                set &= BITS(fds, n);
 407                if (set) {
 408                        if (!(set & ~*open_fds))
 409                                goto get_max;
 410                        return -EBADF;
 411                }
 412        }
 413        while (n) {
 414                open_fds--;
 415                n--;
 416                set = BITS(fds, n);
 417                if (!set)
 418                        continue;
 419                if (set & ~*open_fds)
 420                        return -EBADF;
 421                if (max)
 422                        continue;
 423get_max:
 424                do {
 425                        max++;
 426                        set >>= 1;
 427                } while (set);
 428                max += n * BITS_PER_LONG;
 429        }
 430
 431        return max;
 432}
 433
 434#define POLLIN_SET (EPOLLRDNORM | EPOLLRDBAND | EPOLLIN | EPOLLHUP | EPOLLERR)
 435#define POLLOUT_SET (EPOLLWRBAND | EPOLLWRNORM | EPOLLOUT | EPOLLERR)
 436#define POLLEX_SET (EPOLLPRI)
 437
 438static inline void wait_key_set(poll_table *wait, unsigned long in,
 439                                unsigned long out, unsigned long bit,
 440                                __poll_t ll_flag)
 441{
 442        wait->_key = POLLEX_SET | ll_flag;
 443        if (in & bit)
 444                wait->_key |= POLLIN_SET;
 445        if (out & bit)
 446                wait->_key |= POLLOUT_SET;
 447}
 448
 449static int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time)
 450{
 451        ktime_t expire, *to = NULL;
 452        struct poll_wqueues table;
 453        poll_table *wait;
 454        int retval, i, timed_out = 0;
 455        u64 slack = 0;
 456        __poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
 457        unsigned long busy_start = 0;
 458
 459        rcu_read_lock();
 460        retval = max_select_fd(n, fds);
 461        rcu_read_unlock();
 462
 463        if (retval < 0)
 464                return retval;
 465        n = retval;
 466
 467        poll_initwait(&table);
 468        wait = &table.pt;
 469        if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
 470                wait->_qproc = NULL;
 471                timed_out = 1;
 472        }
 473
 474        if (end_time && !timed_out)
 475                slack = select_estimate_accuracy(end_time);
 476
 477        retval = 0;
 478        for (;;) {
 479                unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
 480                bool can_busy_loop = false;
 481
 482                inp = fds->in; outp = fds->out; exp = fds->ex;
 483                rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
 484
 485                for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
 486                        unsigned long in, out, ex, all_bits, bit = 1, j;
 487                        unsigned long res_in = 0, res_out = 0, res_ex = 0;
 488                        __poll_t mask;
 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                                        wait_key_set(wait, in, out, bit,
 506                                                     busy_flag);
 507                                        mask = vfs_poll(f.file, wait);
 508
 509                                        fdput(f);
 510                                        if ((mask & POLLIN_SET) && (in & bit)) {
 511                                                res_in |= bit;
 512                                                retval++;
 513                                                wait->_qproc = NULL;
 514                                        }
 515                                        if ((mask & POLLOUT_SET) && (out & bit)) {
 516                                                res_out |= bit;
 517                                                retval++;
 518                                                wait->_qproc = NULL;
 519                                        }
 520                                        if ((mask & POLLEX_SET) && (ex & bit)) {
 521                                                res_ex |= bit;
 522                                                retval++;
 523                                                wait->_qproc = NULL;
 524                                        }
 525                                        /* got something, stop busy polling */
 526                                        if (retval) {
 527                                                can_busy_loop = false;
 528                                                busy_flag = 0;
 529
 530                                        /*
 531                                         * only remember a returned
 532                                         * POLL_BUSY_LOOP if we asked for it
 533                                         */
 534                                        } else if (busy_flag & mask)
 535                                                can_busy_loop = true;
 536
 537                                }
 538                        }
 539                        if (res_in)
 540                                *rinp = res_in;
 541                        if (res_out)
 542                                *routp = res_out;
 543                        if (res_ex)
 544                                *rexp = res_ex;
 545                        cond_resched();
 546                }
 547                wait->_qproc = NULL;
 548                if (retval || timed_out || signal_pending(current))
 549                        break;
 550                if (table.error) {
 551                        retval = table.error;
 552                        break;
 553                }
 554
 555                /* only if found POLL_BUSY_LOOP sockets && not out of time */
 556                if (can_busy_loop && !need_resched()) {
 557                        if (!busy_start) {
 558                                busy_start = busy_loop_current_time();
 559                                continue;
 560                        }
 561                        if (!busy_loop_timeout(busy_start))
 562                                continue;
 563                }
 564                busy_flag = 0;
 565
 566                /*
 567                 * If this is the first loop and we have a timeout
 568                 * given, then we convert to ktime_t and set the to
 569                 * pointer to the expiry value.
 570                 */
 571                if (end_time && !to) {
 572                        expire = timespec64_to_ktime(*end_time);
 573                        to = &expire;
 574                }
 575
 576                if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE,
 577                                           to, slack))
 578                        timed_out = 1;
 579        }
 580
 581        poll_freewait(&table);
 582
 583        return retval;
 584}
 585
 586/*
 587 * We can actually return ERESTARTSYS instead of EINTR, but I'd
 588 * like to be certain this leads to no problems. So I return
 589 * EINTR just for safety.
 590 *
 591 * Update: ERESTARTSYS breaks at least the xview clock binary, so
 592 * I'm trying ERESTARTNOHAND which restart only when you want to.
 593 */
 594int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
 595                           fd_set __user *exp, struct timespec64 *end_time)
 596{
 597        fd_set_bits fds;
 598        void *bits;
 599        int ret, max_fds;
 600        size_t size, alloc_size;
 601        struct fdtable *fdt;
 602        /* Allocate small arguments on the stack to save memory and be faster */
 603        long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
 604
 605        ret = -EINVAL;
 606        if (n < 0)
 607                goto out_nofds;
 608
 609        /* max_fds can increase, so grab it once to avoid race */
 610        rcu_read_lock();
 611        fdt = files_fdtable(current->files);
 612        max_fds = fdt->max_fds;
 613        rcu_read_unlock();
 614        if (n > max_fds)
 615                n = max_fds;
 616
 617        /*
 618         * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
 619         * since we used fdset we need to allocate memory in units of
 620         * long-words. 
 621         */
 622        size = FDS_BYTES(n);
 623        bits = stack_fds;
 624        if (size > sizeof(stack_fds) / 6) {
 625                /* Not enough space in on-stack array; must use kmalloc */
 626                ret = -ENOMEM;
 627                if (size > (SIZE_MAX / 6))
 628                        goto out_nofds;
 629
 630                alloc_size = 6 * size;
 631                bits = kvmalloc(alloc_size, GFP_KERNEL);
 632                if (!bits)
 633                        goto out_nofds;
 634        }
 635        fds.in      = bits;
 636        fds.out     = bits +   size;
 637        fds.ex      = bits + 2*size;
 638        fds.res_in  = bits + 3*size;
 639        fds.res_out = bits + 4*size;
 640        fds.res_ex  = bits + 5*size;
 641
 642        if ((ret = get_fd_set(n, inp, fds.in)) ||
 643            (ret = get_fd_set(n, outp, fds.out)) ||
 644            (ret = get_fd_set(n, exp, fds.ex)))
 645                goto out;
 646        zero_fd_set(n, fds.res_in);
 647        zero_fd_set(n, fds.res_out);
 648        zero_fd_set(n, fds.res_ex);
 649
 650        ret = do_select(n, &fds, end_time);
 651
 652        if (ret < 0)
 653                goto out;
 654        if (!ret) {
 655                ret = -ERESTARTNOHAND;
 656                if (signal_pending(current))
 657                        goto out;
 658                ret = 0;
 659        }
 660
 661        if (set_fd_set(n, inp, fds.res_in) ||
 662            set_fd_set(n, outp, fds.res_out) ||
 663            set_fd_set(n, exp, fds.res_ex))
 664                ret = -EFAULT;
 665
 666out:
 667        if (bits != stack_fds)
 668                kvfree(bits);
 669out_nofds:
 670        return ret;
 671}
 672
 673static int kern_select(int n, fd_set __user *inp, fd_set __user *outp,
 674                       fd_set __user *exp, struct timeval __user *tvp)
 675{
 676        struct timespec64 end_time, *to = NULL;
 677        struct timeval tv;
 678        int ret;
 679
 680        if (tvp) {
 681                if (copy_from_user(&tv, tvp, sizeof(tv)))
 682                        return -EFAULT;
 683
 684                to = &end_time;
 685                if (poll_select_set_timeout(to,
 686                                tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
 687                                (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
 688                        return -EINVAL;
 689        }
 690
 691        ret = core_sys_select(n, inp, outp, exp, to);
 692        ret = poll_select_copy_remaining(&end_time, tvp, 1, ret);
 693
 694        return ret;
 695}
 696
 697SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
 698                fd_set __user *, exp, struct timeval __user *, tvp)
 699{
 700        return kern_select(n, inp, outp, exp, tvp);
 701}
 702
 703static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,
 704                       fd_set __user *exp, struct timespec __user *tsp,
 705                       const sigset_t __user *sigmask, size_t sigsetsize)
 706{
 707        sigset_t ksigmask, sigsaved;
 708        struct timespec64 ts, end_time, *to = NULL;
 709        int ret;
 710
 711        if (tsp) {
 712                if (get_timespec64(&ts, tsp))
 713                        return -EFAULT;
 714
 715                to = &end_time;
 716                if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
 717                        return -EINVAL;
 718        }
 719
 720        if (sigmask) {
 721                /* XXX: Don't preclude handling different sized sigset_t's.  */
 722                if (sigsetsize != sizeof(sigset_t))
 723                        return -EINVAL;
 724                if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
 725                        return -EFAULT;
 726
 727                sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
 728                sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
 729        }
 730
 731        ret = core_sys_select(n, inp, outp, exp, to);
 732        ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
 733
 734        if (ret == -ERESTARTNOHAND) {
 735                /*
 736                 * Don't restore the signal mask yet. Let do_signal() deliver
 737                 * the signal on the way back to userspace, before the signal
 738                 * mask is restored.
 739                 */
 740                if (sigmask) {
 741                        memcpy(&current->saved_sigmask, &sigsaved,
 742                                        sizeof(sigsaved));
 743                        set_restore_sigmask();
 744                }
 745        } else if (sigmask)
 746                sigprocmask(SIG_SETMASK, &sigsaved, NULL);
 747
 748        return ret;
 749}
 750
 751/*
 752 * Most architectures can't handle 7-argument syscalls. So we provide a
 753 * 6-argument version where the sixth argument is a pointer to a structure
 754 * which has a pointer to the sigset_t itself followed by a size_t containing
 755 * the sigset size.
 756 */
 757SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp,
 758                fd_set __user *, exp, struct timespec __user *, tsp,
 759                void __user *, sig)
 760{
 761        size_t sigsetsize = 0;
 762        sigset_t __user *up = NULL;
 763
 764        if (sig) {
 765                if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t))
 766                    || __get_user(up, (sigset_t __user * __user *)sig)
 767                    || __get_user(sigsetsize,
 768                                (size_t __user *)(sig+sizeof(void *))))
 769                        return -EFAULT;
 770        }
 771
 772        return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize);
 773}
 774
 775#ifdef __ARCH_WANT_SYS_OLD_SELECT
 776struct sel_arg_struct {
 777        unsigned long n;
 778        fd_set __user *inp, *outp, *exp;
 779        struct timeval __user *tvp;
 780};
 781
 782SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)
 783{
 784        struct sel_arg_struct a;
 785
 786        if (copy_from_user(&a, arg, sizeof(a)))
 787                return -EFAULT;
 788        return kern_select(a.n, a.inp, a.outp, a.exp, a.tvp);
 789}
 790#endif
 791
 792struct poll_list {
 793        struct poll_list *next;
 794        int len;
 795        struct pollfd entries[0];
 796};
 797
 798#define POLLFD_PER_PAGE  ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
 799
 800/*
 801 * Fish for pollable events on the pollfd->fd file descriptor. We're only
 802 * interested in events matching the pollfd->events mask, and the result
 803 * matching that mask is both recorded in pollfd->revents and returned. The
 804 * pwait poll_table will be used by the fd-provided poll handler for waiting,
 805 * if pwait->_qproc is non-NULL.
 806 */
 807static inline __poll_t do_pollfd(struct pollfd *pollfd, poll_table *pwait,
 808                                     bool *can_busy_poll,
 809                                     __poll_t busy_flag)
 810{
 811        int fd = pollfd->fd;
 812        __poll_t mask = 0, filter;
 813        struct fd f;
 814
 815        if (fd < 0)
 816                goto out;
 817        mask = EPOLLNVAL;
 818        f = fdget(fd);
 819        if (!f.file)
 820                goto out;
 821
 822        /* userland u16 ->events contains POLL... bitmap */
 823        filter = demangle_poll(pollfd->events) | EPOLLERR | EPOLLHUP;
 824        pwait->_key = filter | busy_flag;
 825        mask = vfs_poll(f.file, pwait);
 826        if (mask & busy_flag)
 827                *can_busy_poll = true;
 828        mask &= filter;         /* Mask out unneeded events. */
 829        fdput(f);
 830
 831out:
 832        /* ... and so does ->revents */
 833        pollfd->revents = mangle_poll(mask);
 834        return mask;
 835}
 836
 837static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
 838                   struct timespec64 *end_time)
 839{
 840        poll_table* pt = &wait->pt;
 841        ktime_t expire, *to = NULL;
 842        int timed_out = 0, count = 0;
 843        u64 slack = 0;
 844        __poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
 845        unsigned long busy_start = 0;
 846
 847        /* Optimise the no-wait case */
 848        if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
 849                pt->_qproc = NULL;
 850                timed_out = 1;
 851        }
 852
 853        if (end_time && !timed_out)
 854                slack = select_estimate_accuracy(end_time);
 855
 856        for (;;) {
 857                struct poll_list *walk;
 858                bool can_busy_loop = false;
 859
 860                for (walk = list; walk != NULL; walk = walk->next) {
 861                        struct pollfd * pfd, * pfd_end;
 862
 863                        pfd = walk->entries;
 864                        pfd_end = pfd + walk->len;
 865                        for (; pfd != pfd_end; pfd++) {
 866                                /*
 867                                 * Fish for events. If we found one, record it
 868                                 * and kill poll_table->_qproc, so we don't
 869                                 * needlessly register any other waiters after
 870                                 * this. They'll get immediately deregistered
 871                                 * when we break out and return.
 872                                 */
 873                                if (do_pollfd(pfd, pt, &can_busy_loop,
 874                                              busy_flag)) {
 875                                        count++;
 876                                        pt->_qproc = NULL;
 877                                        /* found something, stop busy polling */
 878                                        busy_flag = 0;
 879                                        can_busy_loop = false;
 880                                }
 881                        }
 882                }
 883                /*
 884                 * All waiters have already been registered, so don't provide
 885                 * a poll_table->_qproc to them on the next loop iteration.
 886                 */
 887                pt->_qproc = NULL;
 888                if (!count) {
 889                        count = wait->error;
 890                        if (signal_pending(current))
 891                                count = -EINTR;
 892                }
 893                if (count || timed_out)
 894                        break;
 895
 896                /* only if found POLL_BUSY_LOOP sockets && not out of time */
 897                if (can_busy_loop && !need_resched()) {
 898                        if (!busy_start) {
 899                                busy_start = busy_loop_current_time();
 900                                continue;
 901                        }
 902                        if (!busy_loop_timeout(busy_start))
 903                                continue;
 904                }
 905                busy_flag = 0;
 906
 907                /*
 908                 * If this is the first loop and we have a timeout
 909                 * given, then we convert to ktime_t and set the to
 910                 * pointer to the expiry value.
 911                 */
 912                if (end_time && !to) {
 913                        expire = timespec64_to_ktime(*end_time);
 914                        to = &expire;
 915                }
 916
 917                if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))
 918                        timed_out = 1;
 919        }
 920        return count;
 921}
 922
 923#define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list))  / \
 924                        sizeof(struct pollfd))
 925
 926static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
 927                struct timespec64 *end_time)
 928{
 929        struct poll_wqueues table;
 930        int err = -EFAULT, fdcount, len, size;
 931        /* Allocate small arguments on the stack to save memory and be
 932           faster - use long to make sure the buffer is aligned properly
 933           on 64 bit archs to avoid unaligned access */
 934        long stack_pps[POLL_STACK_ALLOC/sizeof(long)];
 935        struct poll_list *const head = (struct poll_list *)stack_pps;
 936        struct poll_list *walk = head;
 937        unsigned long todo = nfds;
 938
 939        if (nfds > rlimit(RLIMIT_NOFILE))
 940                return -EINVAL;
 941
 942        len = min_t(unsigned int, nfds, N_STACK_PPS);
 943        for (;;) {
 944                walk->next = NULL;
 945                walk->len = len;
 946                if (!len)
 947                        break;
 948
 949                if (copy_from_user(walk->entries, ufds + nfds-todo,
 950                                        sizeof(struct pollfd) * walk->len))
 951                        goto out_fds;
 952
 953                todo -= walk->len;
 954                if (!todo)
 955                        break;
 956
 957                len = min(todo, POLLFD_PER_PAGE);
 958                size = sizeof(struct poll_list) + sizeof(struct pollfd) * len;
 959                walk = walk->next = kmalloc(size, GFP_KERNEL);
 960                if (!walk) {
 961                        err = -ENOMEM;
 962                        goto out_fds;
 963                }
 964        }
 965
 966        poll_initwait(&table);
 967        fdcount = do_poll(head, &table, end_time);
 968        poll_freewait(&table);
 969
 970        for (walk = head; walk; walk = walk->next) {
 971                struct pollfd *fds = walk->entries;
 972                int j;
 973
 974                for (j = 0; j < walk->len; j++, ufds++)
 975                        if (__put_user(fds[j].revents, &ufds->revents))
 976                                goto out_fds;
 977        }
 978
 979        err = fdcount;
 980out_fds:
 981        walk = head->next;
 982        while (walk) {
 983                struct poll_list *pos = walk;
 984                walk = walk->next;
 985                kfree(pos);
 986        }
 987
 988        return err;
 989}
 990
 991static long do_restart_poll(struct restart_block *restart_block)
 992{
 993        struct pollfd __user *ufds = restart_block->poll.ufds;
 994        int nfds = restart_block->poll.nfds;
 995        struct timespec64 *to = NULL, end_time;
 996        int ret;
 997
 998        if (restart_block->poll.has_timeout) {
 999                end_time.tv_sec = restart_block->poll.tv_sec;
1000                end_time.tv_nsec = restart_block->poll.tv_nsec;
1001                to = &end_time;
1002        }
1003
1004        ret = do_sys_poll(ufds, nfds, to);
1005
1006        if (ret == -EINTR) {
1007                restart_block->fn = do_restart_poll;
1008                ret = -ERESTART_RESTARTBLOCK;
1009        }
1010        return ret;
1011}
1012
1013SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
1014                int, timeout_msecs)
1015{
1016        struct timespec64 end_time, *to = NULL;
1017        int ret;
1018
1019        if (timeout_msecs >= 0) {
1020                to = &end_time;
1021                poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
1022                        NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));
1023        }
1024
1025        ret = do_sys_poll(ufds, nfds, to);
1026
1027        if (ret == -EINTR) {
1028                struct restart_block *restart_block;
1029
1030                restart_block = &current->restart_block;
1031                restart_block->fn = do_restart_poll;
1032                restart_block->poll.ufds = ufds;
1033                restart_block->poll.nfds = nfds;
1034
1035                if (timeout_msecs >= 0) {
1036                        restart_block->poll.tv_sec = end_time.tv_sec;
1037                        restart_block->poll.tv_nsec = end_time.tv_nsec;
1038                        restart_block->poll.has_timeout = 1;
1039                } else
1040                        restart_block->poll.has_timeout = 0;
1041
1042                ret = -ERESTART_RESTARTBLOCK;
1043        }
1044        return ret;
1045}
1046
1047SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
1048                struct timespec __user *, tsp, const sigset_t __user *, sigmask,
1049                size_t, sigsetsize)
1050{
1051        sigset_t ksigmask, sigsaved;
1052        struct timespec64 ts, end_time, *to = NULL;
1053        int ret;
1054
1055        if (tsp) {
1056                if (get_timespec64(&ts, tsp))
1057                        return -EFAULT;
1058
1059                to = &end_time;
1060                if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
1061                        return -EINVAL;
1062        }
1063
1064        if (sigmask) {
1065                /* XXX: Don't preclude handling different sized sigset_t's.  */
1066                if (sigsetsize != sizeof(sigset_t))
1067                        return -EINVAL;
1068                if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
1069                        return -EFAULT;
1070
1071                sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
1072                sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
1073        }
1074
1075        ret = do_sys_poll(ufds, nfds, to);
1076
1077        /* We can restart this syscall, usually */
1078        if (ret == -EINTR) {
1079                /*
1080                 * Don't restore the signal mask yet. Let do_signal() deliver
1081                 * the signal on the way back to userspace, before the signal
1082                 * mask is restored.
1083                 */
1084                if (sigmask) {
1085                        memcpy(&current->saved_sigmask, &sigsaved,
1086                                        sizeof(sigsaved));
1087                        set_restore_sigmask();
1088                }
1089                ret = -ERESTARTNOHAND;
1090        } else if (sigmask)
1091                sigprocmask(SIG_SETMASK, &sigsaved, NULL);
1092
1093        ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
1094
1095        return ret;
1096}
1097
1098#ifdef CONFIG_COMPAT
1099#define __COMPAT_NFDBITS       (8 * sizeof(compat_ulong_t))
1100
1101static
1102int compat_poll_select_copy_remaining(struct timespec64 *end_time, void __user *p,
1103                                      int timeval, int ret)
1104{
1105        struct timespec64 ts;
1106
1107        if (!p)
1108                return ret;
1109
1110        if (current->personality & STICKY_TIMEOUTS)
1111                goto sticky;
1112
1113        /* No update for zero timeout */
1114        if (!end_time->tv_sec && !end_time->tv_nsec)
1115                return ret;
1116
1117        ktime_get_ts64(&ts);
1118        ts = timespec64_sub(*end_time, ts);
1119        if (ts.tv_sec < 0)
1120                ts.tv_sec = ts.tv_nsec = 0;
1121
1122        if (timeval) {
1123                struct old_timeval32 rtv;
1124
1125                rtv.tv_sec = ts.tv_sec;
1126                rtv.tv_usec = ts.tv_nsec / NSEC_PER_USEC;
1127
1128                if (!copy_to_user(p, &rtv, sizeof(rtv)))
1129                        return ret;
1130        } else {
1131                if (!put_old_timespec32(&ts, p))
1132                        return ret;
1133        }
1134        /*
1135         * If an application puts its timeval in read-only memory, we
1136         * don't want the Linux-specific update to the timeval to
1137         * cause a fault after the select has completed
1138         * successfully. However, because we're not updating the
1139         * timeval, we can't restart the system call.
1140         */
1141
1142sticky:
1143        if (ret == -ERESTARTNOHAND)
1144                ret = -EINTR;
1145        return ret;
1146}
1147
1148/*
1149 * Ooo, nasty.  We need here to frob 32-bit unsigned longs to
1150 * 64-bit unsigned longs.
1151 */
1152static
1153int compat_get_fd_set(unsigned long nr, compat_ulong_t __user *ufdset,
1154                        unsigned long *fdset)
1155{
1156        if (ufdset) {
1157                return compat_get_bitmap(fdset, ufdset, nr);
1158        } else {
1159                zero_fd_set(nr, fdset);
1160                return 0;
1161        }
1162}
1163
1164static
1165int compat_set_fd_set(unsigned long nr, compat_ulong_t __user *ufdset,
1166                      unsigned long *fdset)
1167{
1168        if (!ufdset)
1169                return 0;
1170        return compat_put_bitmap(ufdset, fdset, nr);
1171}
1172
1173
1174/*
1175 * This is a virtual copy of sys_select from fs/select.c and probably
1176 * should be compared to it from time to time
1177 */
1178
1179/*
1180 * We can actually return ERESTARTSYS instead of EINTR, but I'd
1181 * like to be certain this leads to no problems. So I return
1182 * EINTR just for safety.
1183 *
1184 * Update: ERESTARTSYS breaks at least the xview clock binary, so
1185 * I'm trying ERESTARTNOHAND which restart only when you want to.
1186 */
1187static int compat_core_sys_select(int n, compat_ulong_t __user *inp,
1188        compat_ulong_t __user *outp, compat_ulong_t __user *exp,
1189        struct timespec64 *end_time)
1190{
1191        fd_set_bits fds;
1192        void *bits;
1193        int size, max_fds, ret = -EINVAL;
1194        struct fdtable *fdt;
1195        long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
1196
1197        if (n < 0)
1198                goto out_nofds;
1199
1200        /* max_fds can increase, so grab it once to avoid race */
1201        rcu_read_lock();
1202        fdt = files_fdtable(current->files);
1203        max_fds = fdt->max_fds;
1204        rcu_read_unlock();
1205        if (n > max_fds)
1206                n = max_fds;
1207
1208        /*
1209         * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
1210         * since we used fdset we need to allocate memory in units of
1211         * long-words.
1212         */
1213        size = FDS_BYTES(n);
1214        bits = stack_fds;
1215        if (size > sizeof(stack_fds) / 6) {
1216                bits = kmalloc_array(6, size, GFP_KERNEL);
1217                ret = -ENOMEM;
1218                if (!bits)
1219                        goto out_nofds;
1220        }
1221        fds.in      = (unsigned long *)  bits;
1222        fds.out     = (unsigned long *) (bits +   size);
1223        fds.ex      = (unsigned long *) (bits + 2*size);
1224        fds.res_in  = (unsigned long *) (bits + 3*size);
1225        fds.res_out = (unsigned long *) (bits + 4*size);
1226        fds.res_ex  = (unsigned long *) (bits + 5*size);
1227
1228        if ((ret = compat_get_fd_set(n, inp, fds.in)) ||
1229            (ret = compat_get_fd_set(n, outp, fds.out)) ||
1230            (ret = compat_get_fd_set(n, exp, fds.ex)))
1231                goto out;
1232        zero_fd_set(n, fds.res_in);
1233        zero_fd_set(n, fds.res_out);
1234        zero_fd_set(n, fds.res_ex);
1235
1236        ret = do_select(n, &fds, end_time);
1237
1238        if (ret < 0)
1239                goto out;
1240        if (!ret) {
1241                ret = -ERESTARTNOHAND;
1242                if (signal_pending(current))
1243                        goto out;
1244                ret = 0;
1245        }
1246
1247        if (compat_set_fd_set(n, inp, fds.res_in) ||
1248            compat_set_fd_set(n, outp, fds.res_out) ||
1249            compat_set_fd_set(n, exp, fds.res_ex))
1250                ret = -EFAULT;
1251out:
1252        if (bits != stack_fds)
1253                kfree(bits);
1254out_nofds:
1255        return ret;
1256}
1257
1258static int do_compat_select(int n, compat_ulong_t __user *inp,
1259        compat_ulong_t __user *outp, compat_ulong_t __user *exp,
1260        struct old_timeval32 __user *tvp)
1261{
1262        struct timespec64 end_time, *to = NULL;
1263        struct old_timeval32 tv;
1264        int ret;
1265
1266        if (tvp) {
1267                if (copy_from_user(&tv, tvp, sizeof(tv)))
1268                        return -EFAULT;
1269
1270                to = &end_time;
1271                if (poll_select_set_timeout(to,
1272                                tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
1273                                (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
1274                        return -EINVAL;
1275        }
1276
1277        ret = compat_core_sys_select(n, inp, outp, exp, to);
1278        ret = compat_poll_select_copy_remaining(&end_time, tvp, 1, ret);
1279
1280        return ret;
1281}
1282
1283COMPAT_SYSCALL_DEFINE5(select, int, n, compat_ulong_t __user *, inp,
1284        compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,
1285        struct old_timeval32 __user *, tvp)
1286{
1287        return do_compat_select(n, inp, outp, exp, tvp);
1288}
1289
1290struct compat_sel_arg_struct {
1291        compat_ulong_t n;
1292        compat_uptr_t inp;
1293        compat_uptr_t outp;
1294        compat_uptr_t exp;
1295        compat_uptr_t tvp;
1296};
1297
1298COMPAT_SYSCALL_DEFINE1(old_select, struct compat_sel_arg_struct __user *, arg)
1299{
1300        struct compat_sel_arg_struct a;
1301
1302        if (copy_from_user(&a, arg, sizeof(a)))
1303                return -EFAULT;
1304        return do_compat_select(a.n, compat_ptr(a.inp), compat_ptr(a.outp),
1305                                compat_ptr(a.exp), compat_ptr(a.tvp));
1306}
1307
1308static long do_compat_pselect(int n, compat_ulong_t __user *inp,
1309        compat_ulong_t __user *outp, compat_ulong_t __user *exp,
1310        struct old_timespec32 __user *tsp, compat_sigset_t __user *sigmask,
1311        compat_size_t sigsetsize)
1312{
1313        sigset_t ksigmask, sigsaved;
1314        struct timespec64 ts, end_time, *to = NULL;
1315        int ret;
1316
1317        if (tsp) {
1318                if (get_old_timespec32(&ts, tsp))
1319                        return -EFAULT;
1320
1321                to = &end_time;
1322                if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
1323                        return -EINVAL;
1324        }
1325
1326        if (sigmask) {
1327                if (sigsetsize != sizeof(compat_sigset_t))
1328                        return -EINVAL;
1329                if (get_compat_sigset(&ksigmask, sigmask))
1330                        return -EFAULT;
1331
1332                sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
1333                sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
1334        }
1335
1336        ret = compat_core_sys_select(n, inp, outp, exp, to);
1337        ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret);
1338
1339        if (ret == -ERESTARTNOHAND) {
1340                /*
1341                 * Don't restore the signal mask yet. Let do_signal() deliver
1342                 * the signal on the way back to userspace, before the signal
1343                 * mask is restored.
1344                 */
1345                if (sigmask) {
1346                        memcpy(&current->saved_sigmask, &sigsaved,
1347                                        sizeof(sigsaved));
1348                        set_restore_sigmask();
1349                }
1350        } else if (sigmask)
1351                sigprocmask(SIG_SETMASK, &sigsaved, NULL);
1352
1353        return ret;
1354}
1355
1356COMPAT_SYSCALL_DEFINE6(pselect6, int, n, compat_ulong_t __user *, inp,
1357        compat_ulong_t __user *, outp, compat_ulong_t __user *, exp,
1358        struct old_timespec32 __user *, tsp, void __user *, sig)
1359{
1360        compat_size_t sigsetsize = 0;
1361        compat_uptr_t up = 0;
1362
1363        if (sig) {
1364                if (!access_ok(VERIFY_READ, sig,
1365                                sizeof(compat_uptr_t)+sizeof(compat_size_t)) ||
1366                        __get_user(up, (compat_uptr_t __user *)sig) ||
1367                        __get_user(sigsetsize,
1368                                (compat_size_t __user *)(sig+sizeof(up))))
1369                        return -EFAULT;
1370        }
1371        return do_compat_pselect(n, inp, outp, exp, tsp, compat_ptr(up),
1372                                 sigsetsize);
1373}
1374
1375COMPAT_SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds,
1376        unsigned int,  nfds, struct old_timespec32 __user *, tsp,
1377        const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize)
1378{
1379        sigset_t ksigmask, sigsaved;
1380        struct timespec64 ts, end_time, *to = NULL;
1381        int ret;
1382
1383        if (tsp) {
1384                if (get_old_timespec32(&ts, tsp))
1385                        return -EFAULT;
1386
1387                to = &end_time;
1388                if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
1389                        return -EINVAL;
1390        }
1391
1392        if (sigmask) {
1393                if (sigsetsize != sizeof(compat_sigset_t))
1394                        return -EINVAL;
1395                if (get_compat_sigset(&ksigmask, sigmask))
1396                        return -EFAULT;
1397
1398                sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
1399                sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
1400        }
1401
1402        ret = do_sys_poll(ufds, nfds, to);
1403
1404        /* We can restart this syscall, usually */
1405        if (ret == -EINTR) {
1406                /*
1407                 * Don't restore the signal mask yet. Let do_signal() deliver
1408                 * the signal on the way back to userspace, before the signal
1409                 * mask is restored.
1410                 */
1411                if (sigmask) {
1412                        memcpy(&current->saved_sigmask, &sigsaved,
1413                                sizeof(sigsaved));
1414                        set_restore_sigmask();
1415                }
1416                ret = -ERESTARTNOHAND;
1417        } else if (sigmask)
1418                sigprocmask(SIG_SETMASK, &sigsaved, NULL);
1419
1420        ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret);
1421
1422        return ret;
1423}
1424#endif
1425