sysdeps/nacl/futex-internal.h

   1 /* futex operations for glibc-internal use.  NaCl version.
   2    Copyright (C) 2014-2016 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef FUTEX_INTERNAL_H
  20 #define FUTEX_INTERNAL_H
  21
  22 #include <sysdeps/nptl/futex-internal.h>
  23 #include <errno.h>
  24 #include <lowlevellock-futex.h>
  25 #include <nacl-interfaces.h>
  26 #include <nptl/pthreadP.h>
  27
  28 /* See sysdeps/nptl/futex-internal.h for documentation; this file only
  29    contains NaCl-specific comments.
  30
  31    There is no support yet for shared futexes nor for exact relative
  32    timeouts.  */
  33
  34 /* See sysdeps/nptl/futex-internal.h for constraints on the value of the
  35    FUTEX_PRIVATE and FUTEX_SHARED constants.
  36    Shared futexes are not yet supported, and we never allow clients to
  37    actually request shared futexes.  Therefore, we do not need a different
  38    value.  */
  39 #undef FUTEX_SHARED
  40 #define FUTEX_SHARED  FUTEX_PRIVATE
  41
  42 /* FUTEX_SHARED is not yet supported.  */
  43 static __always_inline int
  44 futex_supports_pshared (int pshared)
  45 {
  46   if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))
  47     return 0;
  48   else if (pshared == PTHREAD_PROCESS_SHARED)
  49     return ENOTSUP;
  50   else
  51     return EINVAL;
  52 }
  53
  54 /* Relative timeouts are only emulated via absolute timeouts using the
  55    system clock.  */
  56 static __always_inline bool
  57 futex_supports_exact_relative_timeouts (void)
  58 {
  59   return false;
  60 }
  61
  62 /* See sysdeps/nptl/futex-internal.h for details.  */
  63 static __always_inline int
  64 futex_wait (unsigned int *futex_word, unsigned int expected, int private)
  65 {
  66   int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
  67   switch (err)
  68     {
  69     case 0:
  70     case -EAGAIN:
  71     case -EINTR:
  72       return -err;
  73
  74     case -ETIMEDOUT: /* Cannot have happened as we provided no timeout.  */
  75     case -EFAULT: /* Must have been caused by a glibc or application bug.  */
  76     case -EINVAL: /* Either due to wrong alignment or due to the timeout not
  77                      being normalized.  Must have been caused by a glibc or
  78                      application bug.  */
  79     case -ENOSYS: /* Must have been caused by a glibc bug.  */
  80     /* No other errors are documented at this time.  */
  81     default:
  82       futex_fatal_error ();
  83     }
  84 }
  85
  86 /* See sysdeps/nptl/futex-internal.h for details.  */
  87 static __always_inline int
  88 futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,
  89                        int private)
  90 {
  91   int oldtype;
  92   oldtype = __pthread_enable_asynccancel ();
  93   int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
  94   __pthread_disable_asynccancel (oldtype);
  95   switch (err)
  96     {
  97     case 0:
  98     case -EAGAIN:
  99     case -EINTR:
 100       return -err;
 101
 102     case -ETIMEDOUT: /* Cannot have happened as we provided no timeout.  */
 103     case -EFAULT: /* Must have been caused by a glibc or application bug.  */
 104     case -EINVAL: /* Either due to wrong alignment or due to the timeout not
 105                      being normalized.  Must have been caused by a glibc or
 106                      application bug.  */
 107     case -ENOSYS: /* Must have been caused by a glibc bug.  */
 108     /* No other errors are documented at this time.  */
 109     default:
 110       futex_fatal_error ();
 111     }
 112 }
 113
 114 /* See sysdeps/nptl/futex-internal.h for details.  */
 115 static __always_inline int
 116 futex_reltimed_wait (unsigned int *futex_word, unsigned int expected,
 117                      const struct timespec *reltime, int private)
 118 {
 119   int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
 120   switch (err)
 121     {
 122     case 0:
 123     case -EAGAIN:
 124     case -EINTR:
 125     case -ETIMEDOUT:
 126       return -err;
 127
 128     case -EFAULT: /* Must have been caused by a glibc or application bug.  */
 129     case -EINVAL: /* Either due to wrong alignment or due to the timeout not
 130                      being normalized.  Must have been caused by a glibc or
 131                      application bug.  */
 132     case -ENOSYS: /* Must have been caused by a glibc bug.  */
 133     /* No other errors are documented at this time.  */
 134     default:
 135       futex_fatal_error ();
 136     }
 137 }
 138
 139 /* See sysdeps/nptl/futex-internal.h for details.  */
 140 static __always_inline int
 141 futex_reltimed_wait_cancelable (unsigned int *futex_word,
 142                                 unsigned int expected,
 143                                 const struct timespec *reltime, int private)
 144 {
 145   int oldtype;
 146   oldtype = __pthread_enable_asynccancel ();
 147   int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
 148   __pthread_disable_asynccancel (oldtype);
 149   switch (err)
 150     {
 151     case 0:
 152     case -EAGAIN:
 153     case -EINTR:
 154     case -ETIMEDOUT:
 155       return -err;
 156
 157     case -EFAULT: /* Must have been caused by a glibc or application bug.  */
 158     case -EINVAL: /* Either due to wrong alignment or due to the timeout not
 159                      being normalized.  Must have been caused by a glibc or
 160                      application bug.  */
 161     case -ENOSYS: /* Must have been caused by a glibc bug.  */
 162     /* No other errors are documented at this time.  */
 163     default:
 164       futex_fatal_error ();
 165     }
 166 }
 167
 168 /* See sysdeps/nptl/futex-internal.h for details.  */
 169 static __always_inline int
 170 futex_abstimed_wait (unsigned int *futex_word, unsigned int expected,
 171                      const struct timespec *abstime, int private)
 172 {
 173   int err = __nacl_irt_futex.futex_wait_abs ((volatile int *) futex_word,
 174                                              expected, abstime);
 175   switch (err)
 176     {
 177     case 0:
 178     case EAGAIN:
 179     case EINTR:
 180     case ETIMEDOUT:
 181       return err;
 182
 183     case EFAULT: /* Must have been caused by a glibc or application bug.  */
 184     case EINVAL: /* Either due to wrong alignment or due to the timeout not
 185                     being normalized.  Must have been caused by a glibc or
 186                     application bug.  */
 187     case ENOSYS: /* Must have been caused by a glibc bug.  */
 188     /* No other errors are documented at this time.  */
 189     default:
 190       futex_fatal_error ();
 191     }
 192 }
 193
 194 /* See sysdeps/nptl/futex-internal.h for details.  */
 195 static __always_inline int
 196 futex_abstimed_wait_cancelable (unsigned int *futex_word,
 197                                 unsigned int expected,
 198                                 const struct timespec *abstime, int private)
 199 {
 200   int oldtype;
 201   oldtype = __pthread_enable_asynccancel ();
 202   int err = __nacl_irt_futex.futex_wait_abs ((volatile int *) futex_word,
 203                                              expected, abstime);
 204   __pthread_disable_asynccancel (oldtype);
 205   switch (err)
 206     {
 207     case 0:
 208     case EAGAIN:
 209     case EINTR:
 210     case ETIMEDOUT:
 211       return err;
 212
 213     case EFAULT: /* Must have been caused by a glibc or application bug.  */
 214     case EINVAL: /* Either due to wrong alignment or due to the timeout not
 215                     being normalized.  Must have been caused by a glibc or
 216                     application bug.  */
 217     case ENOSYS: /* Must have been caused by a glibc bug.  */
 218     /* No other errors are documented at this time.  */
 219     default:
 220       futex_fatal_error ();
 221     }
 222 }
 223
 224 /* See sysdeps/nptl/futex-internal.h for details.  */
 225 static __always_inline void
 226 futex_wake (unsigned int *futex_word, int processes_to_wake, int private)
 227 {
 228   int res = lll_futex_wake (futex_word, processes_to_wake, private);
 229   /* No error.  Ignore the number of woken processes.  */
 230   if (res >= 0)
 231     return;
 232   switch (res)
 233     {
 234     case -EFAULT: /* Could have happened due to memory reuse.  */
 235     case -EINVAL: /* Could be either due to incorrect alignment (a bug in
 236                      glibc or in the application) or due to memory being
 237                      reused for a PI futex.  We cannot distinguish between the
 238                      two causes, and one of them is correct use, so we do not
 239                      act in this case.  */
 240       return;
 241     case -ENOSYS: /* Must have been caused by a glibc bug.  */
 242     /* No other errors are documented at this time.  */
 243     default:
 244       futex_fatal_error ();
 245     }
 246 }
 247
 248 #endif  /* futex-internal.h */