getcontext.s revision 9a70fc3be3b1e966bf78825cdb8d509963a6f0a1
/*
* 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() 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)