sysdeps/unix/sysv/linux/lowlevellock-futex.h

   1 /* Low-level locking access to futex facilities.  Linux version.
   2    Copyright (C) 2005-2015 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 _LOWLEVELLOCK_FUTEX_H
  20 #define _LOWLEVELLOCK_FUTEX_H   1
  21
  22 #ifndef __ASSEMBLER__
  23 #include <sysdep.h>
  24 #include <tls.h>
  25 #include <kernel-features.h>
  26 #endif
  27
  28 #define FUTEX_WAIT              0
  29 #define FUTEX_WAKE              1
  30 #define FUTEX_REQUEUE           3
  31 #define FUTEX_CMP_REQUEUE       4
  32 #define FUTEX_WAKE_OP           5
  33 #define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE   ((4 << 24) | 1)
  34 #define FUTEX_LOCK_PI           6
  35 #define FUTEX_UNLOCK_PI         7
  36 #define FUTEX_TRYLOCK_PI        8
  37 #define FUTEX_WAIT_BITSET       9
  38 #define FUTEX_WAKE_BITSET       10
  39 #define FUTEX_WAIT_REQUEUE_PI   11
  40 #define FUTEX_CMP_REQUEUE_PI    12
  41 #define FUTEX_PRIVATE_FLAG      128
  42 #define FUTEX_CLOCK_REALTIME    256
  43
  44 #define FUTEX_BITSET_MATCH_ANY  0xffffffff
  45
  46 /* Values for 'private' parameter of locking macros.  Yes, the
  47    definition seems to be backwards.  But it is not.  The bit will be
  48    reversed before passing to the system call.  */
  49 #define LLL_PRIVATE     0
  50 #define LLL_SHARED      FUTEX_PRIVATE_FLAG
  51
  52 #ifndef __ASSEMBLER__
  53
  54 #if IS_IN (libc) || IS_IN (rtld)
  55 /* In libc.so or ld.so all futexes are private.  */
  56 # ifdef __ASSUME_PRIVATE_FUTEX
  57 #  define __lll_private_flag(fl, private) \
  58   ((fl) | FUTEX_PRIVATE_FLAG)
  59 # else
  60 #  define __lll_private_flag(fl, private) \
  61   ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))
  62 # endif
  63 #else
  64 # ifdef __ASSUME_PRIVATE_FUTEX
  65 #  define __lll_private_flag(fl, private) \
  66   (((fl) | FUTEX_PRIVATE_FLAG) ^ (private))
  67 # else
  68 #  define __lll_private_flag(fl, private) \
  69   (__builtin_constant_p (private)                                             \
  70    ? ((private) == 0                                                          \
  71       ? ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))            \
  72       : (fl))                                                                 \
  73    : ((fl) | (((private) ^ FUTEX_PRIVATE_FLAG)                                \
  74               & THREAD_GETMEM (THREAD_SELF, header.private_futex))))
  75 # endif
  76 #endif
  77
  78 #define lll_futex_syscall(nargs, futexp, op, ...)                       \
  79   ({                                                                    \
  80     INTERNAL_SYSCALL_DECL (__err);                                      \
  81     long int __ret = INTERNAL_SYSCALL (futex, __err, nargs, futexp, op, \
  82                                        __VA_ARGS__);                    \
  83     (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (__ret, __err))         \
  84      ? -INTERNAL_SYSCALL_ERRNO (__ret, __err) : 0);                     \
  85   })
  86
  87 #define lll_futex_wait(futexp, val, private) \
  88   lll_futex_timed_wait (futexp, val, NULL, private)
  89
  90 #define lll_futex_timed_wait(futexp, val, timeout, private)     \
  91   lll_futex_syscall (4, futexp,                                 \
  92                      __lll_private_flag (FUTEX_WAIT, private),  \
  93                      val, timeout)
  94
  95 #define lll_futex_timed_wait_bitset(futexp, val, timeout, clockbit, private) \
  96   lll_futex_syscall (6, futexp,                                         \
  97                      __lll_private_flag (FUTEX_WAIT_BITSET | (clockbit), \
  98                                          private),                      \
  99                      val, timeout, NULL /* Unused.  */,                 \
 100                      FUTEX_BITSET_MATCH_ANY)
 101
 102 #define lll_futex_wake(futexp, nr, private)                             \
 103   lll_futex_syscall (4, futexp,                                         \
 104                      __lll_private_flag (FUTEX_WAKE, private), nr, 0)
 105
 106 /* Returns non-zero if error happened, zero if success.  */
 107 #define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
 108   lll_futex_syscall (6, futexp,                                         \
 109                      __lll_private_flag (FUTEX_CMP_REQUEUE, private),   \
 110                      nr_wake, nr_move, mutex, val)
 111
 112 /* Returns non-zero if error happened, zero if success.  */
 113 #define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
 114   lll_futex_syscall (6, futexp,                                         \
 115                      __lll_private_flag (FUTEX_WAKE_OP, private),       \
 116                      nr_wake, nr_wake2, futexp2,                        \
 117                      FUTEX_OP_CLEAR_WAKE_IF_GT_ONE)
 118
 119 /* Priority Inheritance support.  */
 120 #define lll_futex_wait_requeue_pi(futexp, val, mutex, private) \
 121   lll_futex_timed_wait_requeue_pi (futexp, val, NULL, 0, mutex, private)
 122
 123 #define lll_futex_timed_wait_requeue_pi(futexp, val, timeout, clockbit, \
 124                                         mutex, private)                 \
 125   lll_futex_syscall (5, futexp,                                         \
 126                      __lll_private_flag (FUTEX_WAIT_REQUEUE_PI          \
 127                                          | (clockbit), private),        \
 128                      val, timeout, mutex)
 129
 130
 131 #define lll_futex_cmp_requeue_pi(futexp, nr_wake, nr_move, mutex,       \
 132                                  val, private)                          \
 133   lll_futex_syscall (6, futexp,                                         \
 134                      __lll_private_flag (FUTEX_CMP_REQUEUE_PI,          \
 135                                          private),                      \
 136                      nr_wake, nr_move, mutex, val)
 137
 138 #endif  /* !__ASSEMBLER__  */
 139
 140 #endif  /* lowlevellock-futex.h */