brk.S revision 1.18 
1/* $OpenBSD: brk.S,v 1.18 2022/12/08 01:25:43 guenther Exp $ */
2
3/*
4 * Copyright (c) 1996 Dale Rahn
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include "SYS.h"
29
30	.extern __curbrk
31	.extern _end
32
33ENTRY_NB(brk)
34
35	/* check >= _end, if not make the call for _end */
36#ifndef __PIC__
37	addis 5,0,_end@h
38	ori  5,5,_end@l				/* # 5 = &_end */
39#else
40	mflr	10
41	bcl	20, 31, 1f
421:	mflr	9
43	addis	9, 9, _GLOBAL_OFFSET_TABLE_-1b@ha
44	addi	9, 9, _GLOBAL_OFFSET_TABLE_-1b@l
45	mtlr	10
46	lwz	5,_end@got(9)
47#endif
48	cmplw	3,5
49	bge+	.L_brk_call
50	mr	3, 5
51
52.L_brk_call:
53	mr	7, 3
54	/* call break(size) */
55#ifndef __PIC__
56	addis	6, 0, __curbrk@H
57	ori	6, 6, __curbrk@L	/* # 6 = &__curbrk */
58#else
59	lwz	6,__curbrk@got(9)
60#endif
61
62	li	0, SYS_break
63	sc
64
65	/* check for error */
66	cmpwi	0, 0
67	beq+	.L_brk_ok	/* OK so this is stupid but I haven't read b */
68	stw	0, R2_OFFSET_ERRNO(2)
69	li	3, -1
70	blr
71
72	/* update, __curbrk and return */
73.L_brk_ok:
74	stw	7, 0(6)		/* # remember, 6=&__curbrk, 3= new value */
75	mr	3, 0		/* # return 0 */
76	blr
77END(brk)
78	.weak	brk
79