sysdeps/unix/sysv/linux/i386/lowlevellock-futex.h

   1 /* Low-level locking access to futex facilities.  Linux/i386 version.
   2    Copyright (C) 2014-2015 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 #define FUTEX_WAIT              0
  23 #define FUTEX_WAKE              1
  24 #define FUTEX_CMP_REQUEUE       4
  25 #define FUTEX_WAKE_OP           5
  26 #define FUTEX_LOCK_PI           6
  27 #define FUTEX_UNLOCK_PI         7
  28 #define FUTEX_TRYLOCK_PI        8
  29 #define FUTEX_WAIT_BITSET       9
  30 #define FUTEX_WAKE_BITSET       10
  31 #define FUTEX_WAIT_REQUEUE_PI   11
  32 #define FUTEX_CMP_REQUEUE_PI    12
  33 #define FUTEX_PRIVATE_FLAG      128
  34 #define FUTEX_CLOCK_REALTIME    256
  35
  36 #define FUTEX_BITSET_MATCH_ANY  0xffffffff
  37
  38 #define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE   ((4 << 24) | 1)
  39
  40 /* Values for 'private' parameter of locking macros.  Yes, the
  41    definition seems to be backwards.  But it is not.  The bit will be
  42    reversed before passing to the system call.  */
  43 #define LLL_PRIVATE     0
  44 #define LLL_SHARED      FUTEX_PRIVATE_FLAG
  45
  46
  47 #if IS_IN (libc) || IS_IN (rtld)
  48 /* In libc.so or ld.so all futexes are private.  */
  49 # ifdef __ASSUME_PRIVATE_FUTEX
  50 #  define __lll_private_flag(fl, private) \
  51   ((fl) | FUTEX_PRIVATE_FLAG)
  52 # else
  53 #  define __lll_private_flag(fl, private) \
  54   ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))
  55 # endif
  56 #else
  57 # ifdef __ASSUME_PRIVATE_FUTEX
  58 #  define __lll_private_flag(fl, private) \
  59   (((fl) | FUTEX_PRIVATE_FLAG) ^ (private))
  60 # else
  61 #  define __lll_private_flag(fl, private) \
  62   (__builtin_constant_p (private)                                             \
  63    ? ((private) == 0                                                          \
  64       ? ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))            \
  65       : (fl))                                                                 \
  66    : ({ unsigned int __fl = ((private) ^ FUTEX_PRIVATE_FLAG);                 \
  67         asm ("andl %%gs:%P1, %0" : "+r" (__fl)                                \
  68              : "i" (offsetof (struct pthread, header.private_futex)));        \
  69         __fl | (fl); }))
  70 # endif
  71 #endif
  72
  73
  74 #ifndef __ASSEMBLER__
  75
  76 /* To avoid naming conflicts with lowlevellock.h, use a different prefix
  77    here.  */
  78 #ifdef PIC
  79 # define LLLF_EBX_LOAD  "xchgl %2, %%ebx\n"
  80 # define LLLF_EBX_REG   "D"
  81 #else
  82 # define LLLF_EBX_LOAD
  83 # define LLLF_EBX_REG   "b"
  84 #endif
  85
  86 #ifdef I386_USE_SYSENTER
  87 # ifdef SHARED
  88 #  define LLLF_ENTER_KERNEL     "call *%%gs:%P6\n\t"
  89 # else
  90 #  define LLLF_ENTER_KERNEL     "call *_dl_sysinfo\n\t"
  91 # endif
  92 #else
  93 # define LLLF_ENTER_KERNEL      "int $0x80\n\t"
  94 #endif
  95
  96
  97 #define lll_futex_wait(futex, val, private) \
  98   lll_futex_timed_wait (futex, val, NULL, private)
  99
 100
 101 #define lll_futex_timed_wait(futex, val, timeout, private) \
 102   ({                                                                          \
 103     int __status;                                                             \
 104     register __typeof (val) _val asm ("edx") = (val);                         \
 105     __asm __volatile (LLLF_EBX_LOAD                                           \
 106                       LLLF_ENTER_KERNEL                                       \
 107                       LLLF_EBX_LOAD                                           \
 108                       : "=a" (__status)                                       \
 109                       : "0" (SYS_futex), LLLF_EBX_REG (futex), "S" (timeout),  \
 110                         "c" (__lll_private_flag (FUTEX_WAIT, private)),       \
 111                         "d" (_val), "i" (offsetof (tcbhead_t, sysinfo))       \
 112                       : "memory");                                            \
 113     __status;                                                                 \
 114   })
 115
 116
 117 #define lll_futex_wake(futex, nr, private) \
 118   ({                                                                          \
 119     int __status;                                                             \
 120     register __typeof (nr) _nr asm ("edx") = (nr);                            \
 121     LIBC_PROBE (lll_futex_wake, 3, futex, nr, private);                       \
 122     __asm __volatile (LLLF_EBX_LOAD                                           \
 123                       LLLF_ENTER_KERNEL                                       \
 124                       LLLF_EBX_LOAD                                           \
 125                       : "=a" (__status)                                       \
 126                       : "0" (SYS_futex), LLLF_EBX_REG (futex),                \
 127                         "c" (__lll_private_flag (FUTEX_WAKE, private)),       \
 128                         "d" (_nr),                                            \
 129                         "i" (0) /* phony, to align next arg's number */,      \
 130                         "i" (offsetof (tcbhead_t, sysinfo)));                 \
 131     __status;                                                                 \
 132   })
 133
 134
 135 #endif  /* !__ASSEMBLER__ */
 136
 137 #endif  /* lowlevellock-futex.h */