xref: /onnv-gate/usr/src/lib/libc/amd64/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() is written in assembler since it has to capture the correct
41*0Sstevel@tonic-gate * machine state of the calle.
42*0Sstevel@tonic-gate *
43*0Sstevel@tonic-gate * As swapcontext() is actually equivalent to getcontext() + setcontext(),
44*0Sstevel@tonic-gate * swapcontext() shares the most code with getcontext().
45*0Sstevel@tonic-gate */
46*0Sstevel@tonic-gate
47*0Sstevel@tonic-gate#define	GETCONTEXT_IMPL(offset)						\
48*0Sstevel@tonic-gate	pushq	%rdi;		/* preserve the ucontext_t pointer */	\
49*0Sstevel@tonic-gate	call	__getcontext_syscall;					\
50*0Sstevel@tonic-gate				/* call getcontext: syscall */		\
51*0Sstevel@tonic-gate	popq	%rdx;							\
52*0Sstevel@tonic-gate	andl	%eax, %eax;	/* if (error_return_from_syscall) */	\
53*0Sstevel@tonic-gate	je	1f;							\
54*0Sstevel@tonic-gate	addq	$offset, %rsp;						\
55*0Sstevel@tonic-gate	ret;			/*	then just return */		\
56*0Sstevel@tonic-gate1:									\
57*0Sstevel@tonic-gate	/*								\
58*0Sstevel@tonic-gate	 * fix up %rsp and %rip						\
59*0Sstevel@tonic-gate	 */								\
60*0Sstevel@tonic-gate	addq	$UC_MCONTEXT_GREGS, %rdx;				\
61*0Sstevel@tonic-gate				/* &ucp->uc_mcontext.gregs */		\
62*0Sstevel@tonic-gate	movq	offset+0(%rsp), %rax;					\
63*0Sstevel@tonic-gate				/* read return PC from stack */		\
64*0Sstevel@tonic-gate	movq	%rax, RIP_OFF (%rdx);					\
65*0Sstevel@tonic-gate				/* store ret PC in EIP of env var */	\
66*0Sstevel@tonic-gate	leaq	offset+8(%rsp), %rax;					\
67*0Sstevel@tonic-gate				/* get caller's sp at time of call */	\
68*0Sstevel@tonic-gate	movq	%rax, RSP_OFF (%rdx);					\
69*0Sstevel@tonic-gate				/* store the sp into UESP of env var */	\
70*0Sstevel@tonic-gate	xorq	%rax, %rax;	/* return 0 */				\
71*0Sstevel@tonic-gate	movq	%rax, RAX_OFF (%rdx);					\
72*0Sstevel@tonic-gate				/* getcontext returns 0 after 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
78*0Sstevel@tonic-gate	ANSI_PRAGMA_WEAK2(_private_getcontext,getcontext,function)
79*0Sstevel@tonic-gate
80*0Sstevel@tonic-gate	ENTRY(getcontext)
81*0Sstevel@tonic-gate	GETCONTEXT_IMPL(0)
82*0Sstevel@tonic-gate	ret
83*0Sstevel@tonic-gate	SET_SIZE(getcontext)
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
89*0Sstevel@tonic-gate	ENTRY(swapcontext)
90*0Sstevel@tonic-gate	pushq	%rsi			/* preserve the 2nd argument */
91*0Sstevel@tonic-gate
92*0Sstevel@tonic-gate	GETCONTEXT_IMPL(8)
93*0Sstevel@tonic-gate
94*0Sstevel@tonic-gate	/* call setcontext */
95*0Sstevel@tonic-gate	popq	%rdi
96*0Sstevel@tonic-gate	call	_private_setcontext	/* call setcontext */
97*0Sstevel@tonic-gate	ret
98*0Sstevel@tonic-gate	SET_SIZE(swapcontext)
99