1/*        $NetBSD: swapcontext.S,v 1.8 2018/02/28 20:51:58 uwe Exp $  */
2
3/*-
4 * Copyright (c) 2001 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Klaus Klein.
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#include "assym.h"
34
35__RCSID("$NetBSD: swapcontext.S,v 1.8 2018/02/28 20:51:58 uwe Exp $")
36
37#define   XCALLFRAMELEN       (((2+3)*SZREG + CALLFRAMELEN - 1) & -CALLFRAMELEN)
38#define   XCALLFRAME_R30      (XCALLFRAMELEN-1*SZREG)
39#define   XCALLFRAME_UCP      (XCALLFRAMELEN-2*SZREG)
40#define   XCALLFRAME_OUCP     (XCALLFRAMELEN-3*SZREG)
41
42ENTRY(swapcontext)
43          stwu      %r1,-XCALLFRAMELEN(%r1)                 # set up new stack frame
44          mflr      %r0
45          stw       %r0,XCALLFRAMELEN+CALLFRAME_LR(%r1)     # save link register
46          stw       %r3,XCALLFRAME_OUCP(%r1)      # must save oucp
47          stw       %r4,XCALLFRAME_UCP(%r1)                 # must save ucp
48#ifdef __PIC__
49          stw       %r30,XCALLFRAME_R30(%r1)      # must save r30
50          PIC_TOCSETUP(swapcontext,%r30)                    # setup toc pointer
51#endif
52          bl        PIC_PLT(_C_LABEL(_getcontext))          # getcontext(oucp)
53          cmpwi     %r3,0
54          bne       1f
55          lwz       %r11,XCALLFRAME_OUCP(%r1)     # load oucp for adjustment
56          lwz       %r0,XCALLFRAMELEN+CALLFRAME_LR(%r1)
57          stw       %r0,UC_GREGS_PC(%r11)                   # pc <- lr
58          addi      %r0,%r1,XCALLFRAMELEN
59          stw       %r0,UC_GREGS_R1(%r11)                   # adjust sp
60#ifdef __PIC__
61          lwz       %r0,XCALLFRAME_R30(%r1)
62          stw       %r0,UC_GREGS_R30(%r11)                  # caller's r30
63#endif
64          lwz       %r3,XCALLFRAME_UCP(%r1)                 # load ucp
65          bl        PIC_PLT(_C_LABEL(setcontext)) # setcontext(ucp)
661:
67          lwz       %r0,XCALLFRAMELEN+CALLFRAME_LR(%r1)
68#ifdef __PIC__
69          lwz       %r30,XCALLFRAME_R30(%r1)
70#endif
71          mtlr      %r0
72          addi      %r1,%r1,XCALLFRAMELEN
73          blr
74END(swapcontext)
75