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75eff3fe90
This patch moves the AArch64 port to the main sysdeps hierarchy. The move is essentially: git mv ports/sysdeps/aarch64 sysdeps/aarch64 git mv ports/sysdeps/unix/sysv/linux/aarch64 sysdeps/unix/sysv/linux/aarch64 The README is updated and I've updated ChangeLog.aarch64 along the lines of the ARM move. The AArch64 build has been tested to confirm that there were no changes in objdump -dr output or the shared objects.
91 lines
2.5 KiB
C
91 lines
2.5 KiB
C
/* Copyright (C) 2004-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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 License as
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published by the Free Software Foundation; either version 2.1 of the
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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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<http://www.gnu.org/licenses/>. */
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#include "pthreadP.h"
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#include <lowlevellock.h>
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unsigned long int __fork_generation attribute_hidden;
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static void
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clear_once_control (void *arg)
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{
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pthread_once_t *once_control = (pthread_once_t *) arg;
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*once_control = 0;
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lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
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}
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int
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__pthread_once (pthread_once_t *once_control, void (*init_routine) (void))
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{
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for (;;)
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{
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int oldval;
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int newval;
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/* Pseudo code:
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newval = __fork_generation | 1;
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oldval = *once_control;
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if ((oldval & 2) == 0)
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*once_control = newval;
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Do this atomically.
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*/
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do
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{
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newval = __fork_generation | 1;
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oldval = *once_control;
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if (oldval & 2)
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break;
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} while (atomic_compare_and_exchange_val_acq (once_control, newval, oldval) != oldval);
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/* Check if the initializer has already been done. */
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if ((oldval & 2) != 0)
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return 0;
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/* Check if another thread already runs the initializer. */
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if ((oldval & 1) == 0)
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break;
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/* Check whether the initializer execution was interrupted by a fork. */
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if (oldval != newval)
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break;
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/* Same generation, some other thread was faster. Wait. */
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lll_futex_wait (once_control, oldval, LLL_PRIVATE);
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}
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/* This thread is the first here. Do the initialization.
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Register a cleanup handler so that in case the thread gets
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interrupted the initialization can be restarted. */
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pthread_cleanup_push (clear_once_control, once_control);
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init_routine ();
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pthread_cleanup_pop (0);
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/* Say that the initialisation is done. */
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*once_control = __fork_generation | 2;
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/* Wake up all other threads. */
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lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
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return 0;
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}
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weak_alias (__pthread_once, pthread_once)
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hidden_def (__pthread_once)
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