71 lines
2.3 KiB
C
71 lines
2.3 KiB
C
/* Copyright (C) 2010-2018 Free Software Foundation, Inc.
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Contributed by ARM Ltd.
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This file is part of the GNU Offloading and Multi Processing Library
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(libgomp).
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Libgomp 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, or (at your option)
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any later version.
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Libgomp 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 target-specific access to the futex system call. */
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/* The include file hierachy above us (wait.h) has pushed visibility
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hidden, this will be applied to prototypes with headers we include
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with the effect that we cannot link against an external function
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(syscall). The solution here is to push default visibility, include
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our required headers then reinstante the original visibility. */
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#pragma GCC visibility push(default)
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#define _GNU_SOURCE
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#include <unistd.h>
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#include <sys/syscall.h>
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#pragma GCC visibility pop
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static inline void
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futex_wait (int *addr, int val)
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{
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int err = syscall (SYS_futex, addr, gomp_futex_wait, val, NULL);
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if (__builtin_expect (err < 0 && errno == ENOSYS, 0))
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{
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gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
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gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
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syscall (SYS_futex, addr, gomp_futex_wait, val, NULL);
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}
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}
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static inline void
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futex_wake (int *addr, int count)
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{
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int err = syscall (SYS_futex, addr, gomp_futex_wake, count);
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if (__builtin_expect (err < 0 && errno == ENOSYS, 0))
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{
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gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
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gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
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syscall (SYS_futex, addr, gomp_futex_wake, count);
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}
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}
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static inline void
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cpu_relax (void)
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{
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__asm volatile ("" : : : "memory");
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}
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