xref: /src/lib/libc/arch/riscv/gen/swapcontext.S

/*	$NetBSD: swapcontext.S,v 1.1 2014/09/19 17:36:25 matt Exp $	*/

/*-
 * Copyright (c) 2001 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Klaus Klein.
 *
 * 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``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 FOUNDATION OR CONTRIBUTORS
 * 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"
#include "assym.h"

__RCSID("$NetBSD: swapcontext.S,v 1.1 2014/09/19 17:36:25 matt Exp $")

#define	CALLFRAME_UCP	CALLFRAME_S1
#define	CALLFRAME_OUCP	CALLFRAME_S0

ENTRY(swapcontext)
	addi	sp, sp, -CALLFRAME_SIZ		# adjust stack
	REG_S	ra, CALLFRAME_RA(sp)		# save return address
	REG_S	a0, CALLFRAME_OUCP(sp)		# save oucp
	REG_S	a1, CALLFRAME_UCP(sp)		# save ucp

	call	PLT(_C_LABEL(_getcontext))	# getcontext(oucp)

	REG_L	ra, CALLFRAME_RA(sp)		# restore return address
	REG_L	a0, CALLFRAME_UCP(sp)		# load ucp
	REG_L	a1, CALLFRAME_OUCP(sp)		# load oucp for adjustment
	addi	sp, sp, CALLFRAME_SIZ		# restore stack

	bnez	v0, 1f				# error? yes, cleanup

	REG_S	ra, UC_GREGS_PC(a1)		# pc <- ra
	REG_S	sp, UC_GREGS_SP(a1)		# adjust sp

	jump	PLT(_C_LABEL(setcontext))	# setcontext(ucp)

1:	ret					# simply return
END(swapcontext)