brk.S revision 1.8 
1/*	$OpenBSD: brk.S,v 1.8 2016/05/30 05:18:52 guenther Exp $ */
2/*-
3 * Copyright (c) 1991, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Ralph Campbell.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "SYS.h"
35
36	.globl	__curbrk
37
38	.data
39__minbrk:
40	PTR_VAL	_C_LABEL(_end)
41	.size	__minbrk, . - __minbrk
42	.type	__minbrk,@object
43	.text
44
45FRAMESZ= MKFSIZ(1,1)
46GPOFF= FRAMESZ-2*REGSZ
47
48	.weak	brk
49
50LEAF(brk, FRAMESZ)
51	PTR_SUBU sp, FRAMESZ
52	SETUP_GP64(GPOFF, brk)
53	.set	reorder
54	PTR_L	v0, __minbrk
55	bgtu	a0, v0, 1f
56
57	move	a0, v0		# dont allow break < minbrk
581:
59	li	v0, SYS_break
60	syscall
61	bne	a3, zero, 2f
62	PTR_S	a0, __curbrk
63	move	v0, zero
64	RESTORE_GP64
65	PTR_ADDU sp, FRAMESZ
66	j	ra
672:
68	LA	t9, CERROR
69	RESTORE_GP64
70	PTR_ADDU sp, FRAMESZ
71	jr	t9
72END(brk)
73