osfmk/kern/ast.c

   1 /*
   2  * Copyright (c) 2000-2009 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
  84
  85 void
  86 ast_init(void)
  87 {
  88 }
  89
  90 /*
  91  * Called at splsched.
  92  */
  93 void
  94 ast_taken(
  95         ast_t           reasons,
  96         boolean_t       enable
  97 )
  98 {
  99         boolean_t               preempt_trap = (reasons == AST_PREEMPTION);
 100         ast_t                   *myast = ast_pending();
 101         thread_t                thread = current_thread();
 102         perfCallback    perf_hook = perfASTHook;
 103
 104         /*
 105          * CHUD hook - all threads including idle processor threads
 106          */
 107         if (perf_hook) {
 108                 if (*myast & AST_CHUD_ALL) {
 109                         (*perf_hook)(0, NULL, 0, 0);
 110
 111                         if (*myast == AST_NONE)
 112                                 return;
 113                 }
 114         }
 115         else
 116                 *myast &= ~AST_CHUD_ALL;
 117
 118         reasons &= *myast;
 119         *myast &= ~reasons;
 120
 121         /*
 122          * Handle ASTs for all threads
 123          * except idle processor threads.
 124          */
 125         if (!(thread->state & TH_IDLE)) {
 126                 /*
 127                  * Check for urgent preemption.
 128                  */
 129                 if (    (reasons & AST_URGENT)                          &&
 130                                 wait_queue_assert_possible(thread)              ) {
 131                         if (reasons & AST_PREEMPT) {
 132                                 counter(c_ast_taken_block++);
 133                                 thread_block_reason(THREAD_CONTINUE_NULL, NULL,
 134                                                                                 AST_PREEMPT | AST_URGENT);
 135                         }
 136
 137                         reasons &= ~AST_PREEMPTION;
 138                 }
 139
 140                 /*
 141                  * The kernel preempt traps
 142                  * skip all other ASTs.
 143                  */
 144                 if (!preempt_trap) {
 145                         ml_set_interrupts_enabled(enable);
 146
 147 #ifdef  MACH_BSD
 148                         /*
 149                          * Handle BSD hook.
 150                          */
 151                         if (reasons & AST_BSD) {
 152                                 thread_ast_clear(thread, AST_BSD);
 153                                 bsd_ast(thread);
 154                         }
 155 #endif
 156
 157                         /*
 158                          * Thread APC hook.
 159                          */
 160                         if (reasons & AST_APC)
 161                                 act_execute_returnhandlers();
 162
 163                         ml_set_interrupts_enabled(FALSE);
 164
 165                         /*
 166                          * Check for preemption.
 167                          */
 168                         if (reasons & AST_PREEMPT)
 169                                 reasons = csw_check(current_processor());
 170
 171                         if (    (reasons & AST_PREEMPT)                         &&
 172                                         wait_queue_assert_possible(thread)              ) {
 173                                 counter(c_ast_taken_block++);
 174                                 thread_block_reason((thread_continue_t)thread_exception_return, NULL, AST_PREEMPT);
 175                         }
 176                 }
 177         }
 178
 179         ml_set_interrupts_enabled(enable);
 180 }
 181
 182 /*
 183  * Called at splsched.
 184  */
 185 void
 186 ast_check(
 187         processor_t             processor)
 188 {
 189         thread_t                        thread = processor->active_thread;
 190
 191         processor->current_pri = thread->sched_pri;
 192         if (    processor->state == PROCESSOR_RUNNING           ||
 193                         processor->state == PROCESSOR_SHUTDOWN          ) {
 194                 ast_t                   preempt;
 195
 196                 /*
 197                  *      Propagate thread ast to processor.
 198                  */
 199                 ast_propagate(thread->ast);
 200
 201                 /*
 202                  *      Context switch check.
 203                  */
 204                 if ((preempt = csw_check(processor)) != AST_NONE)
 205                         ast_on(preempt);
 206         }
 207 }