/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License (the "License").

 * You may not use this file except in compliance with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

#include <sys/asm_linkage.h>

	ANSI_PRAGMA_WEAK(getcontext,function)

	ANSI_PRAGMA_WEAK(swapcontext,function)

#include "SYS.h"

#include <../assym.h>

/*

 * getcontext() is written in assembler since it has to capture the correct

 * machine state of the calle.

 *

 * As swapcontext() is actually equivalent to getcontext() + setcontext(),

 * swapcontext() shares the most code with getcontext().

 */

#define	GETCONTEXT_IMPL(offset)						\

	pushq	%rdi;		/* preserve the ucontext_t pointer */	\

	call	__getcontext;						\

				/* call getcontext: syscall */		\

	popq	%rdx;							\

	andl	%eax, %eax;	/* if (error_return_from_syscall) */	\

	je	1f;							\

	addq	$offset, %rsp;						\

	ret;			/*	then just return */		\

1:									\

	/*								\

	 * fix up %rsp and %rip						\

	 */								\

	addq	$UC_MCONTEXT_GREGS, %rdx;				\

				/* &ucp->uc_mcontext.gregs */		\

	movq	offset+0(%rsp), %rax;					\

				/* read return PC from stack */		\

	movq	%rax, RIP_OFF (%rdx);					\

				/* store ret PC in EIP of env var */	\

	leaq	offset+8(%rsp), %rax;					\

				/* get caller's sp at time of call */	\

	movq	%rax, RSP_OFF (%rdx);					\

				/* store the sp into UESP of env var */	\

	xorq	%rax, %rax;	/* return 0 */				\

	movq	%rax, RAX_OFF (%rdx);					\

				/* getcontext returns 0 after setcontext */

/*	

 * getcontext(ucontext_t *ucp)

 */

	ENTRY(getcontext)

	GETCONTEXT_IMPL(0)

	ret

	SET_SIZE(getcontext)

/*

 * swapcontext(ucontext_t *oucp, const ucontext_t *ucp)

 */

	ENTRY(swapcontext)

	pushq	%rsi			/* preserve the 2nd argument */

	GETCONTEXT_IMPL(8)

	/* call setcontext */

	popq	%rdi

	call	setcontext

	ret

	SET_SIZE(swapcontext)