1/*
2 * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28/*
29 * @OSF_COPYRIGHT@
30 */
31/*
32 * Mach Operating System
33 * Copyright (c) 1991,1990 Carnegie Mellon University
34 * All Rights Reserved.
35 *
36 * Permission to use, copy, modify and distribute this software and its
37 * documentation is hereby granted, provided that both the copyright
38 * notice and this permission notice appear in all copies of the
39 * software, derivative works or modified versions, and any portions
40 * thereof, and that both notices appear in supporting documentation.
41 *
42 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
43 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
44 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
45 *
46 * Carnegie Mellon requests users of this software to return to
47 *
48 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
49 *  School of Computer Science
50 *  Carnegie Mellon University
51 *  Pittsburgh PA 15213-3890
52 *
53 * any improvements or extensions that they make and grant Carnegie Mellon
54 * the rights to redistribute these changes.
55 */
56/*
57 */
58
59#include <platforms.h>
60
61#include <i386/asm.h>
62#include <i386/proc_reg.h>
63#include <assym.s>
64
65#ifdef	SYMMETRY
66#include <sqt/asm_macros.h>
67#endif
68
69#if	AT386
70#include <i386/mp.h>
71#endif	/* AT386 */
72
73#define	CX(addr, reg)	addr(,reg,4)
74
75	.text
76/*
77 * Context switch routines for i386.
78 */
79
80Entry(Load_context)
81	movl	S_ARG0,%ecx			/* get thread */
82	movl	TH_KERNEL_STACK(%ecx),%ecx	/* get kernel stack */
83	lea	KERNEL_STACK_SIZE-IKS_SIZE-IEL_SIZE(%ecx),%edx
84						/* point to stack top */
85	movl	%ecx,%gs:CPU_ACTIVE_STACK	/* store stack address */
86	movl	%edx,%gs:CPU_KERNEL_STACK	/* store stack top */
87
88	movl	%edx,%esp
89	movl	%edx,%ebp
90
91	xorl	%eax,%eax			/* return zero (no old thread) */
92	pushl	%eax
93	call	EXT(thread_continue)
94
95/*
96 *	This has to save registers only
97 *	when there is no explicit continuation.
98 */
99
100Entry(Switch_context)
101	popl	%eax				/* pop return PC */
102
103	/* Test for a continuation and skip all state saving if so... */
104	cmpl	$0,4(%esp)
105	jne 	5f
106	movl	%gs:CPU_ACTIVE_STACK,%ecx	/* get old kernel stack */
107	movl	%ebx,KSS_EBX(%ecx)		/* save registers */
108	movl	%ebp,KSS_EBP(%ecx)
109	movl	%edi,KSS_EDI(%ecx)
110	movl	%esi,KSS_ESI(%ecx)
111	movl	%eax,KSS_EIP(%ecx)		/* save return PC */
112	movl	%esp,KSS_ESP(%ecx)		/* save SP */
1135:
114	movl	0(%esp),%eax			/* return old thread */
115	movl	8(%esp),%ebx			/* get new thread */
116	movl    %ebx,%gs:CPU_ACTIVE_THREAD      /* new thread is active */
117	movl	TH_KERNEL_STACK(%ebx),%ecx	/* get its kernel stack */
118	lea	KERNEL_STACK_SIZE-IKS_SIZE-IEL_SIZE(%ecx),%ebx
119						/* point to stack top */
120
121	movl	%ecx,%gs:CPU_ACTIVE_STACK	/* set current stack */
122	movl	%ebx,%gs:CPU_KERNEL_STACK	/* set stack top */
123
124
125	movl	KSS_ESP(%ecx),%esp		/* switch stacks */
126	movl	KSS_ESI(%ecx),%esi		/* restore registers */
127	movl	KSS_EDI(%ecx),%edi
128	movl	KSS_EBP(%ecx),%ebp
129	movl	KSS_EBX(%ecx),%ebx
130	jmp	*KSS_EIP(%ecx)			/* return old thread */
131
132Entry(Thread_continue)
133	pushl	%eax				/* push the thread argument */
134	xorl	%ebp,%ebp			/* zero frame pointer */
135	call	*%ebx				/* call real continuation */
136
137/*
138 * thread_t Shutdown_context(thread_t thread,
139 *			 void (*routine)(processor_t),
140 *			 processor_t processor)
141 *
142 * saves the kernel context of the thread,
143 * switches to the interrupt stack,
144 * continues the thread (with thread_continue),
145 * then runs routine on the interrupt stack.
146 *
147 */
148Entry(Shutdown_context)
149	movl	%gs:CPU_ACTIVE_STACK,%ecx /* get old kernel stack */
150	movl	%ebx,KSS_EBX(%ecx)		/* save registers */
151	movl	%ebp,KSS_EBP(%ecx)
152	movl	%edi,KSS_EDI(%ecx)
153	movl	%esi,KSS_ESI(%ecx)
154	popl	KSS_EIP(%ecx)			/* save return PC */
155	movl	%esp,KSS_ESP(%ecx)		/* save SP */
156
157	movl	0(%esp),%eax			/* get old thread */
158	movl	%ecx,TH_KERNEL_STACK(%eax)	/* save old stack */
159	movl	4(%esp),%ebx			/* get routine to run next */
160	movl	8(%esp),%esi			/* get its argument */
161
162	movl	%gs:CPU_INT_STACK_TOP,%esp 	/* switch to interrupt stack */
163
164	pushl	%esi				/* push argument */
165	call	*%ebx				/* call routine to run */
166	hlt					/* (should never return) */
167