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The elision interfaces are closely aligned between the targets that implement them, so declare them in the generic <lowlevellock.h> file. Empty .c stubs are provided, so that fewer makefile updates under sysdeps are needed. Also simplify initialization via __libc_early_init. The symbols __lll_clocklock_elision, __lll_lock_elision, __lll_trylock_elision, __lll_unlock_elision, __pthread_force_elision move into libc. For the time being, non-hidden references are used from libpthread to access them, but once that part of libpthread is moved into libc, hidden symbols will be used again. (Hidden references seem desirable to reduce the likelihood of transactions aborts.)
59 lines
1.8 KiB
C
59 lines
1.8 KiB
C
/* low level locking for pthread library. Generic futex-using version.
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Copyright (C) 2003-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include <futex-internal.h>
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#include <atomic.h>
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#include <stap-probe.h>
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void
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__lll_lock_wait_private (int *futex)
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{
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if (atomic_load_relaxed (futex) == 2)
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goto futex;
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while (atomic_exchange_acquire (futex, 2) != 0)
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{
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futex:
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LIBC_PROBE (lll_lock_wait_private, 1, futex);
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futex_wait ((unsigned int *) futex, 2, LLL_PRIVATE); /* Wait if *futex == 2. */
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}
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}
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libc_hidden_def (__lll_lock_wait_private)
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void
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__lll_lock_wait (int *futex, int private)
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{
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if (atomic_load_relaxed (futex) == 2)
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goto futex;
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while (atomic_exchange_acquire (futex, 2) != 0)
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{
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futex:
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LIBC_PROBE (lll_lock_wait, 1, futex);
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futex_wait ((unsigned int *) futex, 2, private); /* Wait if *futex == 2. */
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}
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}
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libc_hidden_def (__lll_lock_wait)
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#if ENABLE_ELISION_SUPPORT
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int __pthread_force_elision __attribute__ ((nocommon));
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libc_hidden_data_def (__pthread_force_elision)
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#endif
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