1 /* Copyright (C) 2005-2022 Free Software Foundation, Inc. 2 Contributed by Jakub Jelinek <jakub@redhat.com>. 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 #include <sys/syscall.h> 29 30 static inline long 31 sys_futex0 (int *addr, int op, int val) 32 { 33 register long int gpr2 __asm__ ("2"); 34 register long int gpr3 __asm__ ("3"); 35 register long int gpr4 __asm__ ("4"); 36 register long int gpr5 __asm__ ("5"); 37 38 gpr2 = (long) addr; 39 gpr3 = op; 40 gpr4 = val; 41 gpr5 = 0; 42 43 __asm volatile ("svc %b1" 44 : "=d" (gpr2) 45 : "i" (SYS_futex), 46 "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5) 47 : "memory"); 48 return gpr2; 49 } 50 51 static inline void 52 futex_wait (int *addr, int val) 53 { 54 long err = sys_futex0 (addr, gomp_futex_wait, val); 55 if (__builtin_expect (err == -ENOSYS, 0)) 56 { 57 gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG; 58 gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG; 59 sys_futex0 (addr, gomp_futex_wait, val); 60 } 61 } 62 63 static inline void 64 futex_wake (int *addr, int count) 65 { 66 long err = sys_futex0 (addr, gomp_futex_wake, count); 67 if (__builtin_expect (err == -ENOSYS, 0)) 68 { 69 gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG; 70 gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG; 71 sys_futex0 (addr, gomp_futex_wake, count); 72 } 73 } 74 75 static inline void 76 cpu_relax (void) 77 { 78 __asm volatile ("" : : : "memory"); 79 } 80