xref: /titanic_41/usr/src/lib/libc/sparcv9/gen/swapctxt.c (revision 45916cd2fec6e79bca5dee0421bd39e3c2910d1e)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 
23 /*	Copyright (c) 1988 AT&T	*/
24 /*	  All Rights Reserved  	*/
25 
26 /*
27  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
28  * Use is subject to license terms.
29  */
30 
31 #pragma ident	"%Z%%M%	%I%	%E% SMI"
32 
33 #pragma weak swapcontext = _swapcontext
34 
35 #include "synonyms.h"
36 #include "thr_uberdata.h"
37 #include <ucontext.h>
38 #include <sys/types.h>
39 
40 int
41 swapcontext(ucontext_t *oucp, const ucontext_t *nucp)
42 {
43 	greg_t *reg;
44 
45 	if (__getcontext_syscall(oucp))
46 		return (-1);
47 
48 	/*
49 	 * Note that %o1 and %g1 are modified by the system call
50 	 * routine. ABI calling conventions specify that the caller
51 	 * can not depend upon %o0 thru %o5 nor g1, so no effort is
52 	 * made to maintain these registers. %o0 is forced to reflect
53 	 * an affirmative return code.
54 	 */
55 	reg = oucp->uc_mcontext.gregs;
56 	reg[REG_SP] = getfp();
57 	reg[REG_O7] = caller();
58 	reg[REG_PC] = reg[REG_O7] + 8;
59 	reg[REG_nPC] = reg[REG_PC] + 4;
60 	reg[REG_O0] = 0;
61 
62 	return (setcontext((ucontext_t *)nucp));
63 }
64