/*
* 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.
*/
.file "getcontext.s"
#include <sys/asm_linkage.h>
ANSI_PRAGMA_WEAK(getcontext,function)
ANSI_PRAGMA_WEAK(swapcontext,function)
#include "SYS.h"
#include <assym.h>
/*
* getcontext() and swapcontext() are written in assembler since it has to
* capture the correct machine state of the caller, including
* the registers: %edi, %esi and %ebx.
*
* As swapcontext() is actually equivalent to getcontext() + setcontext(),
* swapcontext() shares the most code with getcontext().
*/
#define GETCONTEXT_IMPL \
movl 4(%esp), %eax; /* %eax <-- first arg: ucp */ \
pushl %eax; /* push ucp for system call */ \
call __getcontext; /* call getcontext: syscall */ \
addl $4, %esp; /* pop arg */ \
andl %eax, %eax; /* if (err_ret_from_syscall) */ \
je 1f; \
ret; /* then return */ \
1: \
movl 4(%esp), %eax; /* recompute first arg */ \
/* \
* fix up %esp and %eip \
*/ \
leal UC_MCONTEXT_GREGS (%eax), %edx; \
/* %edx <-- &ucp->uc_mcontext.gregs */ \
movl 0(%esp), %eax; /* read return PC from stack */ \
movl %eax, EIP_OFF (%edx); \
/* store ret PC in EIP of env var */ \
leal 4(%esp), %eax; /* get caller's sp at time of call */ \
movl %eax, UESP_OFF (%edx); \
/* store the sp into UESP of env var */ \
xorl %eax, %eax; /* return 0 */ \
movl %eax, EAX_OFF (%edx); \
/* getcontext returns 0 after a setcontext */
/*
* getcontext(ucontext_t *ucp)
*/
ENTRY(getcontext)
GETCONTEXT_IMPL
ret
SET_SIZE(getcontext)
/*
* swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
*/
ENTRY(swapcontext)
GETCONTEXT_IMPL
/ call setcontext
movl 8(%esp), %eax /* %eax <-- second arg: ucp */
pushl %eax /* push ucp for setcontext */
call setcontext
addl $4, %esp /* pop arg: just in case */
ret
SET_SIZE(swapcontext)