84 lines
2.4 KiB
C++
84 lines
2.4 KiB
C++
/* Copyright (C) 2008-2020 Free Software Foundation, Inc.
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Contributed by Richard Henderson <rth@redhat.com>.
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This file is part of the GNU Transactional Memory Library (libitm).
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Libitm is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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Libitm is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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/* Provide access to the futex system call. */
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#include "libitm_i.h"
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#include "futex.h"
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#include <futex_bits.h>
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#include <errno.h>
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namespace GTM HIDDEN {
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#define FUTEX_WAIT 0
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#define FUTEX_WAKE 1
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#define FUTEX_PRIVATE_FLAG 128
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static int gtm_futex_wait = FUTEX_WAIT | FUTEX_PRIVATE_FLAG;
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static int gtm_futex_wake = FUTEX_WAKE | FUTEX_PRIVATE_FLAG;
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void
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futex_wait (std::atomic<int> *addr, int val)
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{
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long res;
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res = sys_futex0 (addr, gtm_futex_wait, val);
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if (__builtin_expect (res == -ENOSYS, 0))
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{
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gtm_futex_wait = FUTEX_WAIT;
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gtm_futex_wake = FUTEX_WAKE;
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res = sys_futex0 (addr, FUTEX_WAIT, val);
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}
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if (__builtin_expect (res < 0, 0))
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{
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if (res == -EWOULDBLOCK || res == -ETIMEDOUT)
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;
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else if (res == -EFAULT)
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GTM_fatal ("futex failed (EFAULT %p)", addr);
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else
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GTM_fatal ("futex failed (%s)", strerror(-res));
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}
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}
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long
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futex_wake (std::atomic<int> *addr, int count)
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{
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long res = sys_futex0 (addr, gtm_futex_wake, count);
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if (__builtin_expect (res == -ENOSYS, 0))
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{
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gtm_futex_wait = FUTEX_WAIT;
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gtm_futex_wake = FUTEX_WAKE;
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res = sys_futex0 (addr, FUTEX_WAKE, count);
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}
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if (__builtin_expect (res < 0, 0))
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GTM_fatal ("futex failed (%s)", strerror(-res));
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else
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return res;
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}
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} // namespace GTM
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