xref: /onnv-gate/usr/src/lib/libc/i386/sys/getcontext.s (revision 0:68f95e015346)
1*0Sstevel@tonic-gate/*
2*0Sstevel@tonic-gate * CDDL HEADER START
3*0Sstevel@tonic-gate *
4*0Sstevel@tonic-gate * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate * (the "License").  You may not use this file except in compliance
7*0Sstevel@tonic-gate * with the License.
8*0Sstevel@tonic-gate *
9*0Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate * and limitations under the License.
13*0Sstevel@tonic-gate *
14*0Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate *
20*0Sstevel@tonic-gate * CDDL HEADER END
21*0Sstevel@tonic-gate */
22*0Sstevel@tonic-gate/*
23*0Sstevel@tonic-gate * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24*0Sstevel@tonic-gate * Use is subject to license terms.
25*0Sstevel@tonic-gate */
26*0Sstevel@tonic-gate
27*0Sstevel@tonic-gate#pragma ident	"%Z%%M%	%I%	%E% SMI"
28*0Sstevel@tonic-gate
29*0Sstevel@tonic-gate	.file	"%M%"
30*0Sstevel@tonic-gate
31*0Sstevel@tonic-gate#include <sys/asm_linkage.h>
32*0Sstevel@tonic-gate
33*0Sstevel@tonic-gate	ANSI_PRAGMA_WEAK(getcontext,function)
34*0Sstevel@tonic-gate	ANSI_PRAGMA_WEAK(swapcontext,function)
35*0Sstevel@tonic-gate
36*0Sstevel@tonic-gate#include "SYS.h"
37*0Sstevel@tonic-gate#include <assym.h>
38*0Sstevel@tonic-gate
39*0Sstevel@tonic-gate/*
40*0Sstevel@tonic-gate * getcontext() and swapcontext() are written in assembler since it has to
41*0Sstevel@tonic-gate * capture the correct machine state of the caller, including
42*0Sstevel@tonic-gate * the registers: %edi, %esi and %ebx.
43*0Sstevel@tonic-gate *
44*0Sstevel@tonic-gate * As swapcontext() is actually equivalent to getcontext() + setcontext(),
45*0Sstevel@tonic-gate * swapcontext() shares the most code with getcontext().
46*0Sstevel@tonic-gate */
47*0Sstevel@tonic-gate
48*0Sstevel@tonic-gate
49*0Sstevel@tonic-gate#define	GETCONTEXT_IMPL							\
50*0Sstevel@tonic-gate	movl	4(%esp), %eax;		/* %eax <-- first arg: ucp */	\
51*0Sstevel@tonic-gate	pushl	%eax;			/* push ucp for system call */	\
52*0Sstevel@tonic-gate	call	__getcontext_syscall;	/* call getcontext: syscall */	\
53*0Sstevel@tonic-gate	addl	$4, %esp;		/* pop arg */			\
54*0Sstevel@tonic-gate	andl	%eax, %eax;		/* if (err_ret_from_syscall) */	\
55*0Sstevel@tonic-gate	je	1f;							\
56*0Sstevel@tonic-gate	ret;				/*	then return */		\
57*0Sstevel@tonic-gate1:									\
58*0Sstevel@tonic-gate	movl	4(%esp), %eax;		/* recompute first arg */	\
59*0Sstevel@tonic-gate	/*								\
60*0Sstevel@tonic-gate	 * fix up %esp and %eip						\
61*0Sstevel@tonic-gate	 */								\
62*0Sstevel@tonic-gate	leal	UC_MCONTEXT_GREGS (%eax), %edx;				\
63*0Sstevel@tonic-gate				/* %edx <-- &ucp->uc_mcontext.gregs */	\
64*0Sstevel@tonic-gate	movl	0(%esp), %eax;	/* read return PC from stack */		\
65*0Sstevel@tonic-gate	movl	%eax, EIP_OFF (%edx);					\
66*0Sstevel@tonic-gate				/* store ret PC in EIP of env var */	\
67*0Sstevel@tonic-gate	leal	4(%esp), %eax;	/* get caller's sp at time of call */	\
68*0Sstevel@tonic-gate	movl	%eax, UESP_OFF (%edx);					\
69*0Sstevel@tonic-gate				/* store the sp into UESP of env var */	\
70*0Sstevel@tonic-gate	xorl	%eax, %eax;	/* return 0 */				\
71*0Sstevel@tonic-gate	movl	%eax, EAX_OFF (%edx);					\
72*0Sstevel@tonic-gate				/* getcontext returns 0 after a setcontext */
73*0Sstevel@tonic-gate
74*0Sstevel@tonic-gate/*
75*0Sstevel@tonic-gate * getcontext(ucontext_t *ucp)
76*0Sstevel@tonic-gate */
77*0Sstevel@tonic-gate	ANSI_PRAGMA_WEAK2(_private_getcontext,getcontext,function)
78*0Sstevel@tonic-gate
79*0Sstevel@tonic-gate	ENTRY(getcontext)
80*0Sstevel@tonic-gate	GETCONTEXT_IMPL
81*0Sstevel@tonic-gate	ret
82*0Sstevel@tonic-gate	SET_SIZE(getcontext)
83*0Sstevel@tonic-gate
84*0Sstevel@tonic-gate
85*0Sstevel@tonic-gate/*
86*0Sstevel@tonic-gate * swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
87*0Sstevel@tonic-gate */
88*0Sstevel@tonic-gate	ENTRY(swapcontext)
89*0Sstevel@tonic-gate	GETCONTEXT_IMPL
90*0Sstevel@tonic-gate	/ call setcontext
91*0Sstevel@tonic-gate	movl	8(%esp), %eax		/* %eax <-- second arg: ucp */
92*0Sstevel@tonic-gate	pushl	%eax			/* push ucp for setcontext */
93*0Sstevel@tonic-gate	call	_private_setcontext	/* call setcontext */
94*0Sstevel@tonic-gate	addl	$4, %esp		/* pop arg: just in case */
95*0Sstevel@tonic-gate	ret
96*0Sstevel@tonic-gate	SET_SIZE(swapcontext)
97