1 /* Copyright (C) 2005-2022 Free Software Foundation, Inc.
2 Contributed by Richard Henderson <rth@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 #ifdef __x86_64__
29 # ifndef SYS_futex
30 # define SYS_futex 202
31 # endif
32
33 static inline long
__futex_wait(int * addr,int futex_op,int val)34 __futex_wait (int *addr, int futex_op, int val)
35 {
36 long res;
37
38 register void *timeout __asm ("r10") = NULL;
39 __asm volatile ("syscall"
40 : "=a" (res)
41 : "0" (SYS_futex), "D" (addr), "S" (futex_op),
42 "d" (val), "r" (timeout)
43 : "r11", "rcx", "memory");
44 return res;
45 }
46
47 static inline long
__futex_wake(int * addr,int futex_op,int count)48 __futex_wake (int *addr, int futex_op, int count)
49 {
50 long res;
51
52 __asm volatile ("syscall"
53 : "=a" (res)
54 : "0" (SYS_futex), "D" (addr), "S" (futex_op),
55 "d" (count)
56 : "r11", "rcx", "memory");
57 return res;
58 }
59 #else
60 # ifndef SYS_futex
61 # define SYS_futex 240
62 # endif
63
64 static inline long
__futex_wait(int * addr,int futex_op,int val)65 __futex_wait (int *addr, int futex_op, int val)
66 {
67 long res;
68
69 void *timeout = NULL;
70 __asm volatile ("int $0x80"
71 : "=a" (res)
72 : "0" (SYS_futex), "b" (addr), "c" (futex_op),
73 "d" (val), "S" (timeout)
74 : "memory");
75 return res;
76 }
77
78 static inline long
__futex_wake(int * addr,int futex_op,int count)79 __futex_wake (int *addr, int futex_op, int count)
80 {
81 long res;
82
83 __asm volatile ("int $0x80"
84 : "=a" (res)
85 : "0" (SYS_futex), "b" (addr), "c" (futex_op),
86 "d" (count)
87 : "memory");
88 return res;
89 }
90 #endif /* __x86_64__ */
91
92 static inline void
futex_wait(int * addr,int val)93 futex_wait (int *addr, int val)
94 {
95 long err = __futex_wait (addr, gomp_futex_wait, val);
96
97 if (__builtin_expect (err == -ENOSYS, 0))
98 {
99 gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
100 gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
101
102 __futex_wait (addr, gomp_futex_wait, val);
103 }
104 }
105
106 static inline void
futex_wake(int * addr,int count)107 futex_wake (int *addr, int count)
108 {
109 long err = __futex_wake (addr, gomp_futex_wake, count);
110
111 if (__builtin_expect (err == -ENOSYS, 0))
112 {
113 gomp_futex_wait &= ~FUTEX_PRIVATE_FLAG;
114 gomp_futex_wake &= ~FUTEX_PRIVATE_FLAG;
115
116 __futex_wake (addr, gomp_futex_wake, count);
117 }
118 }
119
120 static inline void
cpu_relax(void)121 cpu_relax (void)
122 {
123 __builtin_ia32_pause ();
124 }
125