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 <i386/mp.h>
64#include <assym.s>
65
66
67#define	CX(addr, reg)	addr(,reg,4)
68
69	.text
70/*
71 * Context switch routines for i386.
72 */
73
74Entry(Load_context)
75	movl	S_ARG0,%ecx			/* get thread */
76	movl	TH_KERNEL_STACK(%ecx),%ecx	/* get kernel stack */
77	lea	-IKS_SIZE(%ecx),%edx
78	add	EXT(kernel_stack_size),%edx		/* point to stack top */
79	movl	%ecx,%gs:CPU_ACTIVE_STACK	/* store stack address */
80	movl	%edx,%gs:CPU_KERNEL_STACK	/* store stack top */
81
82	movl	%edx,%esp
83	movl	%edx,%ebp
84
85	subl	$12, %esp			/* align stack */
86	xorl	%eax,%eax			/* return zero (no old thread) */
87	pushl	%eax
88	call	EXT(thread_continue)
89
90/*
91 *	This has to save registers only
92 *	when there is no explicit continuation.
93 */
94
95Entry(Switch_context)
96	popl	%eax				/* pop return PC */
97
98	/* Test for a continuation and skip all state saving if so... */
99	cmpl	$0,4(%esp)
100	jne 	5f
101	movl	%gs:CPU_KERNEL_STACK,%ecx	/* get old kernel stack top */
102	movl	%ebx,KSS_EBX(%ecx)		/* save registers */
103	movl	%ebp,KSS_EBP(%ecx)
104	movl	%edi,KSS_EDI(%ecx)
105	movl	%esi,KSS_ESI(%ecx)
106	movl	%eax,KSS_EIP(%ecx)		/* save return PC */
107	movl	%esp,KSS_ESP(%ecx)		/* save SP */
1085:
109	movl	0(%esp),%eax			/* return old thread */
110	movl	8(%esp),%ecx			/* get new thread */
111	movl    %ecx,%gs:CPU_ACTIVE_THREAD      /* new thread is active */
112	movl	TH_KERNEL_STACK(%ecx),%ebx	/* get its kernel stack */
113	lea	-IKS_SIZE(%ebx),%ecx
114	add	EXT(kernel_stack_size),%ecx
115						/* point to stack top */
116
117	movl	%ebx,%gs:CPU_ACTIVE_STACK	/* set current stack */
118	movl	%ecx,%gs:CPU_KERNEL_STACK	/* set stack top */
119
120
121	movl	KSS_ESP(%ecx),%esp		/* switch stacks */
122	movl	KSS_ESI(%ecx),%esi		/* restore registers */
123	movl	KSS_EDI(%ecx),%edi
124	movl	KSS_EBP(%ecx),%ebp
125	movl	KSS_EBX(%ecx),%ebx
126	jmp	*KSS_EIP(%ecx)			/* return old thread */
127
128Entry(Thread_continue)
129	subl	$12, %esp			/* align stack */
130	pushl	%eax				/* push the thread argument */
131	xorl	%ebp,%ebp			/* zero frame pointer */
132	call	*%ebx				/* call real continuation */
133
134/*
135 * thread_t Shutdown_context(thread_t thread,
136 *			 void (*routine)(processor_t),
137 *			 processor_t processor)
138 *
139 * saves the kernel context of the thread,
140 * switches to the interrupt stack,
141 * continues the thread (with thread_continue),
142 * then runs routine on the interrupt stack.
143 *
144 */
145Entry(Shutdown_context)
146	movl	%gs:CPU_KERNEL_STACK,%ecx /* get old kernel stack */
147	movl	%ebx,KSS_EBX(%ecx)		/* save registers */
148	movl	%ebp,KSS_EBP(%ecx)
149	movl	%edi,KSS_EDI(%ecx)
150	movl	%esi,KSS_ESI(%ecx)
151	popl	KSS_EIP(%ecx)			/* save return PC */
152	movl	%esp,KSS_ESP(%ecx)		/* save SP */
153
154	movl	%gs:CPU_ACTIVE_STACK,%ecx	/* get old stack */
155	movl	0(%esp),%eax			/* get old thread */
156	movl	%ecx,TH_KERNEL_STACK(%eax)	/* save old stack */
157	movl	4(%esp),%ebx			/* get routine to run next */
158	movl	8(%esp),%esi			/* get its argument */
159
160	movl	%gs:CPU_INT_STACK_TOP,%esp 	/* switch to interrupt stack */
161
162	subl	$12, %esp			/* align stack */
163	pushl	%esi				/* push argument */
164	call	*%ebx				/* call routine to run */
165	hlt					/* (should never return) */
166