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

   1 /* Copyright (C) 2002-2019 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   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_H
  20 #define _LOWLEVELLOCK_H 1
  21
  22 #include <stap-probe.h>
  23
  24 #ifndef __ASSEMBLER__
  25 # include <time.h>
  26 # include <sys/param.h>
  27 # include <bits/pthreadtypes.h>
  28 # include <kernel-features.h>
  29 /* <tcb-offsets.h> is generated from tcb-offsets.sym to define offsets
  30    and sizes of types in <tls.h> as well as <pthread.h> which includes
  31    <lowlevellock.h> via nptl/descr.h.  Don't include <tcb-offsets.h>
  32    when generating <tcb-offsets.h> to avoid circular dependency which
  33    may lead to build hang on a many-core machine.  */
  34 # ifndef GEN_AS_CONST_HEADERS
  35 #  include <tcb-offsets.h>
  36 # endif
  37
  38 # ifndef LOCK_INSTR
  39 #  ifdef UP
  40 #   define LOCK_INSTR   /* nothing */
  41 #  else
  42 #   define LOCK_INSTR "lock;"
  43 #  endif
  44 # endif
  45 #else
  46 # ifndef LOCK
  47 #  ifdef UP
  48 #   define LOCK
  49 #  else
  50 #   define LOCK lock
  51 #  endif
  52 # endif
  53 #endif
  54
  55 #include <lowlevellock-futex.h>
  56
  57 /* XXX Remove when no assembler code uses futexes anymore.  */
  58 #define SYS_futex               __NR_futex
  59
  60 #ifndef __ASSEMBLER__
  61
  62 /* Initializer for compatibility lock.  */
  63 #define LLL_LOCK_INITIALIZER            (0)
  64 #define LLL_LOCK_INITIALIZER_LOCKED     (1)
  65 #define LLL_LOCK_INITIALIZER_WAITERS    (2)
  66
  67
  68 /* NB: in the lll_trylock macro we simply return the value in %eax
  69    after the cmpxchg instruction.  In case the operation succeded this
  70    value is zero.  In case the operation failed, the cmpxchg instruction
  71    has loaded the current value of the memory work which is guaranteed
  72    to be nonzero.  */
  73 #if !IS_IN (libc) || defined UP
  74 # define __lll_trylock_asm LOCK_INSTR "cmpxchgl %2, %1"
  75 #else
  76 # define __lll_trylock_asm "cmpl $0, %%gs:%P5\n\t" \
  77                            "je 0f\n\t"                                        \
  78                            "lock\n"                                           \
  79                            "0:\tcmpxchgl %2, %1"
  80 #endif
  81
  82 #define lll_trylock(futex) \
  83   ({ int ret;                                                                 \
  84      __asm __volatile (__lll_trylock_asm                                      \
  85                        : "=a" (ret), "=m" (futex)                             \
  86                        : "r" (LLL_LOCK_INITIALIZER_LOCKED), "m" (futex),      \
  87                          "0" (LLL_LOCK_INITIALIZER),                          \
  88                          "i" (MULTIPLE_THREADS_OFFSET)                        \
  89                        : "memory");                                           \
  90      ret; })
  91
  92
  93 #define lll_cond_trylock(futex) \
  94   ({ int ret;                                                                 \
  95      __asm __volatile (LOCK_INSTR "cmpxchgl %2, %1"                           \
  96                        : "=a" (ret), "=m" (futex)                             \
  97                        : "r" (LLL_LOCK_INITIALIZER_WAITERS),                  \
  98                          "m" (futex), "0" (LLL_LOCK_INITIALIZER)              \
  99                        : "memory");                                           \
 100      ret; })
 101
 102 #if !IS_IN (libc) || defined UP
 103 # define __lll_lock_asm_start LOCK_INSTR "cmpxchgl %1, %2\n\t"
 104 #else
 105 # define __lll_lock_asm_start "cmpl $0, %%gs:%P6\n\t"                         \
 106                               "je 0f\n\t"                                     \
 107                               "lock\n"                                        \
 108                               "0:\tcmpxchgl %1, %2\n\t"
 109 #endif
 110
 111 #define lll_lock(futex, private) \
 112   (void)                                                                      \
 113     ({ int ignore1, ignore2;                                                  \
 114        if (__builtin_constant_p (private) && (private) == LLL_PRIVATE)        \
 115          __asm __volatile (__lll_lock_asm_start                               \
 116                            "jz 18f\n\t"                               \
 117                            "1:\tleal %2, %%ecx\n"                             \
 118                            "2:\tcall __lll_lock_wait_private\n"               \
 119                            "18:"                                              \
 120                            : "=a" (ignore1), "=c" (ignore2), "=m" (futex)     \
 121                            : "0" (0), "1" (1), "m" (futex),                   \
 122                              "i" (MULTIPLE_THREADS_OFFSET)                    \
 123                            : "memory");                                       \
 124        else                                                                   \
 125          {                                                                    \
 126            int ignore3;                                                       \
 127            __asm __volatile (__lll_lock_asm_start                             \
 128                              "jz 18f\n\t"                                     \
 129                              "1:\tleal %2, %%edx\n"                           \
 130                              "0:\tmovl %8, %%ecx\n"                           \
 131                              "2:\tcall __lll_lock_wait\n"                     \
 132                              "18:"                                            \
 133                              : "=a" (ignore1), "=c" (ignore2),                \
 134                                "=m" (futex), "=&d" (ignore3)                  \
 135                              : "1" (1), "m" (futex),                          \
 136                                "i" (MULTIPLE_THREADS_OFFSET), "0" (0),        \
 137                                "g" ((int) (private))                          \
 138                              : "memory");                                     \
 139          }                                                                    \
 140     })
 141
 142
 143 /* Special version of lll_lock which causes the unlock function to
 144    always wakeup waiters.  */
 145 #define lll_cond_lock(futex, private) \
 146   (void)                                                                      \
 147     ({ int ignore1, ignore2, ignore3;                                         \
 148        __asm __volatile (LOCK_INSTR "cmpxchgl %1, %2\n\t"                     \
 149                          "jz 18f\n\t"                                         \
 150                          "1:\tleal %2, %%edx\n"                               \
 151                          "0:\tmovl %7, %%ecx\n"                               \
 152                          "2:\tcall __lll_lock_wait\n"                         \
 153                          "18:"                                                \
 154                          : "=a" (ignore1), "=c" (ignore2), "=m" (futex),      \
 155                            "=&d" (ignore3)                                    \
 156                          : "0" (0), "1" (2), "m" (futex), "g" ((int) (private))\
 157                          : "memory");                                         \
 158     })
 159
 160
 161 #define lll_timedlock(futex, timeout, private) \
 162   ({ int result, ignore1, ignore2, ignore3;                                   \
 163      __asm __volatile (LOCK_INSTR "cmpxchgl %1, %3\n\t"                       \
 164                        "jz 18f\n\t"                                           \
 165                        "1:\tleal %3, %%ecx\n"                                 \
 166                        "0:\tmovl %8, %%edx\n"                                 \
 167                        "2:\tcall __lll_timedlock_wait\n"                      \
 168                        "18:"                                                  \
 169                        : "=a" (result), "=c" (ignore1), "=&d" (ignore2),      \
 170                          "=m" (futex), "=S" (ignore3)                         \
 171                        : "0" (0), "1" (1), "m" (futex), "m" (timeout),        \
 172                          "4" ((int) (private))                                \
 173                        : "memory");                                           \
 174      result; })
 175
 176 extern int __lll_timedlock_elision (int *futex, short *adapt_count,
 177                                          const struct timespec *timeout,
 178                                          int private) attribute_hidden;
 179
 180 #define lll_timedlock_elision(futex, adapt_count, timeout, private)     \
 181   __lll_timedlock_elision(&(futex), &(adapt_count), timeout, private)
 182
 183 #if !IS_IN (libc) || defined UP
 184 # define __lll_unlock_asm LOCK_INSTR "subl $1, %0\n\t"
 185 #else
 186 # define __lll_unlock_asm "cmpl $0, %%gs:%P3\n\t"                             \
 187                           "je 0f\n\t"                                         \
 188                           "lock\n"                                            \
 189                           "0:\tsubl $1,%0\n\t"
 190 #endif
 191
 192 #define lll_unlock(futex, private) \
 193   (void)                                                                      \
 194     ({ int ignore;                                                            \
 195        if (__builtin_constant_p (private) && (private) == LLL_PRIVATE)        \
 196          __asm __volatile (__lll_unlock_asm                                   \
 197                            "je 18f\n\t"                                       \
 198                            "1:\tleal %0, %%eax\n"                             \
 199                            "2:\tcall __lll_unlock_wake_private\n"             \
 200                            "18:"                                              \
 201                            : "=m" (futex), "=&a" (ignore)                     \
 202                            : "m" (futex), "i" (MULTIPLE_THREADS_OFFSET)       \
 203                            : "memory");                                       \
 204        else                                                                   \
 205          {                                                                    \
 206            int ignore2;                                                       \
 207            __asm __volatile (__lll_unlock_asm                                 \
 208                              "je 18f\n\t"                                     \
 209                              "1:\tleal %0, %%eax\n"                           \
 210                              "0:\tmovl %5, %%ecx\n"                           \
 211                              "2:\tcall __lll_unlock_wake\n"                   \
 212                              "18:"                                            \
 213                              : "=m" (futex), "=&a" (ignore), "=&c" (ignore2)  \
 214                              : "i" (MULTIPLE_THREADS_OFFSET), "m" (futex),    \
 215                                "g" ((int) (private))                          \
 216                              : "memory");                                     \
 217          }                                                                    \
 218     })
 219
 220
 221 #define lll_islocked(futex) \
 222   (futex != LLL_LOCK_INITIALIZER)
 223
 224 /* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
 225    wake-up when the clone terminates.  The memory location contains the
 226    thread ID while the clone is running and is reset to zero by the kernel
 227    afterwards.  The kernel up to version 3.16.3 does not use the private futex
 228    operations for futex wake-up when the clone terminates.  */
 229 #define lll_wait_tid(tid) \
 230   do {                                  \
 231     __typeof (tid) __tid;               \
 232     while ((__tid = (tid)) != 0)        \
 233       lll_futex_wait (&(tid), __tid, LLL_SHARED);\
 234   } while (0)
 235
 236 extern int __lll_timedwait_tid (int *tid, const struct timespec *abstime)
 237      __attribute__ ((regparm (2))) attribute_hidden;
 238
 239 /* As lll_wait_tid, but with a timeout.  If the timeout occurs then return
 240    ETIMEDOUT.  If ABSTIME is invalid, return EINVAL.
 241    XXX Note that this differs from the generic version in that we do the
 242    error checking here and not in __lll_timedwait_tid.  */
 243 #define lll_timedwait_tid(tid, abstime) \
 244   ({                                                                          \
 245     int __result = 0;                                                         \
 246     if ((tid) != 0)                                                           \
 247       __result = __lll_timedwait_tid (&(tid), (abstime));                     \
 248     __result; })
 249
 250
 251 extern int __lll_lock_elision (int *futex, short *adapt_count, int private)
 252   attribute_hidden;
 253
 254 extern int __lll_unlock_elision(int *lock, int private)
 255   attribute_hidden;
 256
 257 extern int __lll_trylock_elision(int *lock, short *adapt_count)
 258   attribute_hidden;
 259
 260 #define lll_lock_elision(futex, adapt_count, private) \
 261   __lll_lock_elision (&(futex), &(adapt_count), private)
 262 #define lll_unlock_elision(futex, adapt_count, private) \
 263   __lll_unlock_elision (&(futex), private)
 264 #define lll_trylock_elision(futex, adapt_count) \
 265   __lll_trylock_elision(&(futex), &(adapt_count))
 266
 267 #endif  /* !__ASSEMBLER__ */
 268
 269 #endif  /* lowlevellock.h */