futex.h revision 169695 
1/* Copyright (C) 2005 Free Software Foundation, Inc.
2   Contributed by Richard Henderson <rth@redhat.com>.
3
4   This file is part of the GNU OpenMP Library (libgomp).
5
6   Libgomp is free software; you can redistribute it and/or modify it
7   under the terms of the GNU Lesser General Public License as published by
8   the Free Software Foundation; either version 2.1 of the License, or
9   (at your option) any later version.
10
11   Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
12   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
13   FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
14   more details.
15
16   You should have received a copy of the GNU Lesser General Public License
17   along with libgomp; see the file COPYING.LIB.  If not, write to the
18   Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
19   MA 02110-1301, USA.  */
20
21/* As a special exception, if you link this library with other files, some
22   of which are compiled with GCC, to produce an executable, this library
23   does not by itself cause the resulting executable to be covered by the
24   GNU General Public License.  This exception does not however invalidate
25   any other reasons why the executable file might be covered by the GNU
26   General Public License.  */
27
28/* Provide target-specific access to the futex system call.  */
29
30#define FUTEX_WAIT	0
31#define FUTEX_WAKE	1
32
33#ifdef __LP64__
34# ifndef SYS_futex
35#  define SYS_futex	202
36# endif
37
38static inline void
39futex_wait (int *addr, int val)
40{
41  register long r10 __asm__("%r10") = 0;
42  long res;
43
44  __asm volatile ("syscall"
45		  : "=a" (res)
46		  : "0"(SYS_futex), "D" (addr), "S"(FUTEX_WAIT),
47		    "d"(val), "r"(r10)
48		  : "r11", "rcx", "memory");
49}
50
51static inline void
52futex_wake (int *addr, int count)
53{
54  long res;
55
56  __asm volatile ("syscall"
57		  : "=a" (res)
58		  : "0"(SYS_futex), "D" (addr), "S"(FUTEX_WAKE), "d"(count)
59		  : "r11", "rcx", "memory");
60}
61#else
62# ifndef SYS_futex
63#  define SYS_futex	240
64# endif
65
66# ifdef __PIC__
67
68static inline void
69sys_futex0 (int *addr, int op, int val)
70{
71  long res;
72
73  __asm volatile ("xchgl\t%%ebx, %2\n\t"
74		  "int\t$0x80\n\t"
75		  "xchgl\t%%ebx, %2"
76		  : "=a" (res)
77		  : "0"(SYS_futex), "r" (addr), "c"(op),
78		    "d"(val), "S"(0)
79		  : "memory");
80}
81
82# else
83
84static inline void
85sys_futex0 (int *addr, int op, int val)
86{
87  long res;
88
89  __asm volatile ("int $0x80"
90		  : "=a" (res)
91		  : "0"(SYS_futex), "b" (addr), "c"(op),
92		    "d"(val), "S"(0)
93		  : "memory");
94}
95
96# endif /* __PIC__ */
97
98static inline void
99futex_wait (int *addr, int val)
100{
101  sys_futex0 (addr, FUTEX_WAIT, val);
102}
103
104static inline void
105futex_wake (int *addr, int count)
106{
107  sys_futex0 (addr, FUTEX_WAKE, count);
108}
109
110#endif /* __LP64__ */
111