1/* Copyright (C) 2010-2022 Free Software Foundation, Inc. 2 Contributed by ARM Ltd. 3 4 This file is part of the GNU Offloading and Multi Processing Library 5 (libgomp). 6 7 Libgomp is free software; you can redistribute it and/or modify it 8 under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3, or (at your option) 10 any later version. 11 12 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY 13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15 more details. 16 17 Under Section 7 of GPL version 3, you are granted additional 18 permissions described in the GCC Runtime Library Exception, version 19 3.1, as published by the Free Software Foundation. 20 21 You should have received a copy of the GNU General Public License and 22 a copy of the GCC Runtime Library Exception along with this program; 23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 <http://www.gnu.org/licenses/>. */ 25 26/* Provide target-specific access to the futex system call. */ 27 28/* The include file hierachy above us (wait.h) has pushed visibility 29 hidden, this will be applied to prototypes with headers we include 30 with the effect that we cannot link against an external function 31 (syscall). The solution here is to push default visibility, include 32 our required headers then reinstante the original visibility. */ 33 34#pragma GCC visibility push(default) 35 36#define _GNU_SOURCE 37#include <unistd.h> 38#include <sys/syscall.h> 39 40#pragma GCC visibility pop 41 42static inline void 43futex_wait (int *addr, int val) 44{ 45 int err = syscall (SYS_futex, addr, gomp_futex_wait, val, NULL); 46 if (__builtin_expect (err < 0 && errno == ENOSYS, 0)) 47 { 48 gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG; 49 gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG; 50 syscall (SYS_futex, addr, gomp_futex_wait, val, NULL); 51 } 52} 53 54static inline void 55futex_wake (int *addr, int count) 56{ 57 int err = syscall (SYS_futex, addr, gomp_futex_wake, count); 58 if (__builtin_expect (err < 0 && errno == ENOSYS, 0)) 59 { 60 gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG; 61 gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG; 62 syscall (SYS_futex, addr, gomp_futex_wake, count); 63 } 64} 65 66static inline void 67cpu_relax (void) 68{ 69 __asm volatile ("" : : : "memory"); 70} 71