/* $OpenBSD: brk.S,v 1.6 2023/12/10 16:45:52 deraadt Exp $ */

/*
 * Copyright (c) 1996 Dale Rahn
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "SYS.h"

        .extern __curbrk
        .extern _end

        .weak   brk

SYSENTRY(brk)
        RETGUARD_SETUP(brk, %r11)

        /* check >= _end, if not make the call for _end */
        addis %r5, %r2, .LC0@toc@ha
        ld  %r5, .LC0@toc@l(%r5)                /* # %r5 = &_end */

        cmpld   %r3, %r5
        bge+    .L_brk_call
        mr      %r3, %r5

.L_brk_call:
        mr      %r7, %r3
        /* call break(size) */
        addis   %r6, %r2, __curbrk@toc@ha
        addi    %r6, %r6, __curbrk@toc@l        /* # %r6 = &__curbrk */

        li %r0, SYS_break
99:     sc
        PINSYSCALL(SYS_break, 99b)

        /* check for error */
        cmpwi   %r0, 0
        beq+    .L_brk_ok       /* OK so this is stupid but I haven't read b */
        stw     %r0, R13_OFFSET_ERRNO(%r13)
        li      %r3, -1
        b       .L_done
        nop

        /* update, __curbrk and return */
.L_brk_ok:
        std     %r7, 0(%r6)     /* # remember, %r6=&__curbrk, %r3=new value */
        mr      %r3, 0          /* # return 0 */
.L_done:
        RETGUARD_CHECK(brk, %r11);
        blr
END(brk)

        .section        .toc,"aw",@progbits
.LC0:
        .tc _end[TC],_end