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brk.S revision 1.1 
      1 /*	$NetBSD: brk.S,v 1.1 2014/09/19 17:36:25 matt Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2014 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Matt Thomas of 3am Software Foundry.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include "SYS.h"
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 	RCSID("$NetBSD: brk.S,v 1.1 2014/09/19 17:36:25 matt Exp $")
     36 #endif /* LIBC_SCCS and not lint */
     37 
     38 	.hidden	_C_LABEL(__minbrk)
     39 	.hidden	_C_LABEL(__curbrk)
     40 	.globl	_C_LABEL(__minbrk)
     41 	.globl	_C_LABEL(__curbrk)
     42 	.globl	_C_LABEL(_end)
     43 
     44 #ifdef WEAK_ALIAS
     45 WEAK_ALIAS(brk, _brk)
     46 #endif
     47 
     48 	.data
     49 	.p2align	PTR_SCALESHIFT
     50 _C_LABEL(__minbrk):
     51 	PTR_WORD	_C_LABEL(_end)
     52 _C_LABEL(__curbrk):
     53 	PTR_WORD	_C_LABEL(_end)
     54 
     55 	.text
     56 
     57 ENTRY(_brk)
     58 	auipc	t1, %pcrel_hi(_C_LABEL(__minbrk))
     59 	addi	t1, t1, %pcrel_lo(_C_LABEL(__minbrk))
     60 	PTR_L	v0, 0(t1)
     61 	bgeu	a0, v0, 1f
     62 	move	a0, v0		# dont allow break < minbrk
     63 1:
     64 	SYSTRAP(break)
     65 	JUMP_TO_CERROR()				/* error */
     66 	PTR_S	a0, __SIZEOF_POINTER__(t1)		/* success */
     67 	move	v0, zero
     68 	ret
     69 END(_brk)
     70