osfmk/kern/ast.c

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * @OSF_COPYRIGHT@
  24  */
  25 /*
  26  * Mach Operating System
  27  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  28  * All Rights Reserved.
  29  *
  30  * Permission to use, copy, modify and distribute this software and its
  31  * documentation is hereby granted, provided that both the copyright
  32  * notice and this permission notice appear in all copies of the
  33  * software, derivative works or modified versions, and any portions
  34  * thereof, and that both notices appear in supporting documentation.
  35  *
  36  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  37  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  38  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  39  *
  40  * Carnegie Mellon requests users of this software to return to
  41  *
  42  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  43  *  School of Computer Science
  44  *  Carnegie Mellon University
  45  *  Pittsburgh PA 15213-3890
  46  *
  47  * any improvements or extensions that they make and grant Carnegie Mellon
  48  * the rights to redistribute these changes.
  49  */
  50 /*
  51  */
  52
  53 /*
  54  *
  55  *      This file contains routines to check whether an ast is needed.
  56  *
  57  *      ast_check() - check whether ast is needed for interrupt or context
  58  *      switch.  Usually called by clock interrupt handler.
  59  *
  60  */
  61
  62 #include <cputypes.h>
  63 #include <platforms.h>
  64
  65 #include <kern/ast.h>
  66 #include <kern/counters.h>
  67 #include <kern/cpu_number.h>
  68 #include <kern/misc_protos.h>
  69 #include <kern/queue.h>
  70 #include <kern/sched_prim.h>
  71 #include <kern/thread.h>
  72 #include <kern/processor.h>
  73 #include <kern/spl.h>
  74 #include <kern/wait_queue.h>
  75 #include <mach/policy.h>
  76 #include <machine/trap.h> // for CHUD AST hook
  77
  78 void
  79 ast_init(void)
  80 {
  81 }
  82
  83 /*
  84  * Called at splsched.
  85  */
  86 void
  87 ast_taken(
  88         ast_t           reasons,
  89         boolean_t       enable
  90 )
  91 {
  92         boolean_t               preempt_trap = (reasons == AST_PREEMPTION);
  93         ast_t                   *myast = ast_pending();
  94         thread_t                thread = current_thread();
  95
  96         /*
  97          * CHUD hook - all threads including idle processor threads
  98          */
  99         if(perfASTHook) {
 100                 if(*myast & AST_CHUD_ALL) {
 101                         perfASTHook(0, NULL, 0, 0);
 102
 103                         if(*myast == AST_NONE) {
 104                                 return; // nothing left to do
 105                         }
 106                 }
 107         } else {
 108                 *myast &= ~AST_CHUD_ALL;
 109         }
 110
 111         reasons &= *myast;
 112         *myast &= ~reasons;
 113
 114         /*
 115          * Handle ASTs for all threads
 116          * except idle processor threads.
 117          */
 118         if (!(thread->state & TH_IDLE)) {
 119                 /*
 120                  * Check for urgent preemption.
 121                  */
 122                 if (    (reasons & AST_URGENT)                          &&
 123                                 wait_queue_assert_possible(thread)              ) {
 124                         if (reasons & AST_PREEMPT) {
 125                                 counter(c_ast_taken_block++);
 126                                 thread_block_reason(THREAD_CONTINUE_NULL, NULL,
 127                                                                                 AST_PREEMPT | AST_URGENT);
 128                         }
 129
 130                         reasons &= ~AST_PREEMPTION;
 131                 }
 132
 133                 /*
 134                  * The kernel preempt traps
 135                  * skip all other ASTs.
 136                  */
 137                 if (!preempt_trap) {
 138                         ml_set_interrupts_enabled(enable);
 139
 140 #ifdef  MACH_BSD
 141                         /*
 142                          * Handle BSD hook.
 143                          */
 144                         if (reasons & AST_BSD) {
 145                                 thread_ast_clear(thread, AST_BSD);
 146                                 bsd_ast(thread);
 147                         }
 148 #endif
 149
 150                         /*
 151                          * Thread APC hook.
 152                          */
 153                         if (reasons & AST_APC)
 154                                 act_execute_returnhandlers();
 155
 156                         ml_set_interrupts_enabled(FALSE);
 157
 158                         /*
 159                          * Check for preemption.
 160                          */
 161                         if (reasons & AST_PREEMPT) {
 162                                 processor_t             myprocessor = current_processor();
 163
 164                                 if (csw_needed(thread, myprocessor))
 165                                         reasons = AST_PREEMPT;
 166                                 else
 167                                         reasons = AST_NONE;
 168                         }
 169                         if (    (reasons & AST_PREEMPT)                         &&
 170                                         wait_queue_assert_possible(thread)              ) {
 171                                 counter(c_ast_taken_block++);
 172                                 thread_block_reason((thread_continue_t)thread_exception_return, NULL, AST_PREEMPT);
 173                         }
 174                 }
 175         }
 176
 177         ml_set_interrupts_enabled(enable);
 178 }
 179
 180 /*
 181  * Called at splsched.
 182  */
 183 void
 184 ast_check(
 185         processor_t             processor)
 186 {
 187         register thread_t               thread = processor->active_thread;
 188
 189         processor->current_pri = thread->sched_pri;
 190         if (    processor->state == PROCESSOR_RUNNING           ||
 191                         processor->state == PROCESSOR_SHUTDOWN          ) {
 192                 register ast_t          preempt;
 193
 194                 /*
 195                  *      Propagate thread ast to processor.
 196                  */
 197                 ast_propagate(thread->ast);
 198
 199                 /*
 200                  *      Context switch check.
 201                  */
 202                 if ((preempt = csw_check(thread, processor)) != AST_NONE)
 203                         ast_on(preempt);
 204         }
 205 }