1/*
2 * Copyright (c) 2000-2008 Apple 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) 1991,1990,1989,1988,1987 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/*
60 *
61 *	This file contains routines to check whether an ast is needed.
62 *
63 *	ast_check() - check whether ast is needed for interrupt or context
64 *	switch.  Usually called by clock interrupt handler.
65 *
66 */
67
68#include <cputypes.h>
69#include <platforms.h>
70
71#include <kern/ast.h>
72#include <kern/counters.h>
73#include <kern/cpu_number.h>
74#include <kern/misc_protos.h>
75#include <kern/queue.h>
76#include <kern/sched_prim.h>
77#include <kern/thread.h>
78#include <kern/processor.h>
79#include <kern/spl.h>
80#include <kern/wait_queue.h>
81#include <mach/policy.h>
82#include <machine/trap.h> // for CHUD AST hook
83
84void
85ast_init(void)
86{
87}
88
89/*
90 * Called at splsched.
91 */
92void
93ast_taken(
94	ast_t		reasons,
95	boolean_t	enable
96)
97{
98	boolean_t		preempt_trap = (reasons == AST_PREEMPTION);
99	ast_t			*myast = ast_pending();
100	thread_t		thread = current_thread();
101
102	/*
103	 * CHUD hook - all threads including idle processor threads
104	 */
105	if(perfASTHook) {
106		if(*myast & AST_CHUD_ALL) {
107			perfASTHook(0, NULL, 0, 0);
108
109			if(*myast == AST_NONE) {
110				return; // nothing left to do
111			}
112		}
113	} else {
114		*myast &= ~AST_CHUD_ALL;
115	}
116
117	reasons &= *myast;
118	*myast &= ~reasons;
119
120	/*
121	 * Handle ASTs for all threads
122	 * except idle processor threads.
123	 */
124	if (!(thread->state & TH_IDLE)) {
125		/*
126		 * Check for urgent preemption.
127		 */
128		if (	(reasons & AST_URGENT)				&&
129				wait_queue_assert_possible(thread)		) {
130			if (reasons & AST_PREEMPT) {
131				counter(c_ast_taken_block++);
132				thread_block_reason(THREAD_CONTINUE_NULL, NULL,
133										AST_PREEMPT | AST_URGENT);
134			}
135
136			reasons &= ~AST_PREEMPTION;
137		}
138
139		/*
140		 * The kernel preempt traps
141		 * skip all other ASTs.
142		 */
143		if (!preempt_trap) {
144			ml_set_interrupts_enabled(enable);
145
146#ifdef	MACH_BSD
147			/*
148			 * Handle BSD hook.
149			 */
150			if (reasons & AST_BSD) {
151				thread_ast_clear(thread, AST_BSD);
152				bsd_ast(thread);
153			}
154#endif
155
156			/*
157			 * Thread APC hook.
158			 */
159			if (reasons & AST_APC)
160				act_execute_returnhandlers();
161
162			ml_set_interrupts_enabled(FALSE);
163
164			/*
165			 * Check for preemption.
166			 */
167			if (reasons & AST_PREEMPT)
168				reasons = csw_check(current_processor());
169
170			if (	(reasons & AST_PREEMPT)				&&
171					wait_queue_assert_possible(thread)		) {
172				counter(c_ast_taken_block++);
173				thread_block_reason((thread_continue_t)thread_exception_return, NULL, AST_PREEMPT);
174			}
175		}
176	}
177
178	ml_set_interrupts_enabled(enable);
179}
180
181/*
182 * Called at splsched.
183 */
184void
185ast_check(
186	processor_t		processor)
187{
188	thread_t			thread = processor->active_thread;
189
190	processor->current_pri = thread->sched_pri;
191	if (	processor->state == PROCESSOR_RUNNING		||
192			processor->state == PROCESSOR_SHUTDOWN		) {
193		ast_t			preempt;
194
195		/*
196		 *	Propagate thread ast to processor.
197		 */
198		ast_propagate(thread->ast);
199
200		/*
201		 *	Context switch check.
202		 */
203		if ((preempt = csw_check(processor)) != AST_NONE)
204			ast_on(preempt);
205	}
206}
207