getcontext.S revision 119724 
1/*-
2 * Copyright (c) 2003 Peter Wemm <peter@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <machine/asm.h>
28__FBSDID("$FreeBSD: head/lib/libc/i386/sys/getcontext.S 119724 2003-09-04 00:20:40Z peter $");
29
30#include <SYS.h>
31
32/*
33 * This has to be magic to handle the multiple returns.
34 * Otherwise, the setcontext() syscall will return here and we'll
35 * pop off the return address and go to the *setcontext* call.
36 */
37	.weak	_getcontext
38	.set	_getcontext,__sys_getcontext
39	.weak	getcontext
40	.set	getcontext,__sys_getcontext
41ENTRY(__sys_getcontext)
42	movl	(%esp),%ecx	/* save getcontext return address */
43	mov	$SYS_getcontext,%eax
44	KERNCALL
45	jb	1f
46	addl	$4,%esp		/* remove stale (setcontext) return address */
47	jmp	*%ecx		/* restore return address */
481:
49	PIC_PROLOGUE
50	jmp	PIC_PLT(HIDENAME(cerror))
51