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swapcontext.S revision 1.12 
      1 /*	$NetBSD: swapcontext.S,v 1.12 2015/04/06 01:50:46 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 <machine/asm.h>
     33 #if defined(SYSLIBC_SCCS) && !defined(lint)
     34 	RCSID("$NetBSD: swapcontext.S,v 1.12 2015/04/06 01:50:46 uwe Exp $")
     35 #endif /* SYSLIBC_SCCS and not lint */
     36 
     37 /*
     38  * int
     39  * swapcontext(ucontext_t * restrict oucp, ucontext_t * restrict ucp);
     40  */
     41 ENTRY(swapcontext)
     42 	PIC_PROLOGUE(.L_got)
     43 	sts.l	pr, @-sp
     44 
     45 	mov.l	.L__getcontext, r0
     46 	mov.l	r5, @-sp
     47 1:	CALL	r0			! _getcontext(oucp)
     48 	 mov.l	r4, @-sp
     49 	!! getcontext captures oucp resuming here with r12 (when PIC),
     50 	!! pr, r5 and r4 pushed onto the stack
     51 
     52 	tst	r0, r0
     53 	bf.s	3f			! return error from getcontext
     54 	 mov.l	@sp, r1			! saved oucp
     55 
     56 	!! adjust oucp to resume after setcontext below
     57 	mova	3f, r0
     58 	mov.l	r0, @(36 + 1 * 4, r1)	! _UC_MACHINE_SET_PC(oucp, pr)
     59 
     60 	mov.l	.L_setcontext, r2
     61 2:	CALL	r2			! setcontext(ucp)
     62 	 mov.l	@(4, sp), r4		! saved ucp
     63 
     64 	.align	2
     65 3:	!! we get here on errors and when resuming oucp
     66 	add	#8, sp			! skip r4 and r5
     67 	lds.l	@sp+, pr
     68 	rts
     69 	 PIC_EPILOGUE_SLOT
     70 
     71 	.align	2
     72 .L_got:			PIC_GOT_DATUM
     73 .L__getcontext:		CALL_DATUM(_C_LABEL(_getcontext), 1b)
     74 .L_setcontext:		CALL_DATUM(_C_LABEL(setcontext), 2b)
     75 	SET_ENTRY_SIZE(swapcontext)
     76