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      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 
     42 ENTRY(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)
     66 1:
     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
     74 END(swapcontext)
     75