osfmk/kern/ast.c

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_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. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*
  24  * @OSF_COPYRIGHT@
  25  */
  26 /*
  27  * Mach Operating System
  28  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  29  * All Rights Reserved.
  30  *
  31  * Permission to use, copy, modify and distribute this software and its
  32  * documentation is hereby granted, provided that both the copyright
  33  * notice and this permission notice appear in all copies of the
  34  * software, derivative works or modified versions, and any portions
  35  * thereof, and that both notices appear in supporting documentation.
  36  *
  37  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  38  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  39  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  40  *
  41  * Carnegie Mellon requests users of this software to return to
  42  *
  43  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  44  *  School of Computer Science
  45  *  Carnegie Mellon University
  46  *  Pittsburgh PA 15213-3890
  47  *
  48  * any improvements or extensions that they make and grant Carnegie Mellon
  49  * the rights to redistribute these changes.
  50  */
  51 /*
  52  */
  53
  54 /*
  55  *
  56  *      This file contains routines to check whether an ast is needed.
  57  *
  58  *      ast_check() - check whether ast is needed for interrupt or context
  59  *      switch.  Usually called by clock interrupt handler.
  60  *
  61  */
  62
  63 #include <cputypes.h>
  64 #include <platforms.h>
  65
  66 #include <kern/ast.h>
  67 #include <kern/counters.h>
  68 #include <kern/cpu_number.h>
  69 #include <kern/misc_protos.h>
  70 #include <kern/queue.h>
  71 #include <kern/sched_prim.h>
  72 #include <kern/thread.h>
  73 #include <kern/processor.h>
  74 #include <kern/spl.h>
  75 #include <kern/wait_queue.h>
  76 #include <mach/policy.h>
  77
  78 #ifdef __ppc__
  79 #include <ppc/trap.h> // for CHUD AST hook
  80 #endif
  81
  82 void
  83 ast_init(void)
  84 {
  85 }
  86
  87 /*
  88  * Called at splsched.
  89  */
  90 void
  91 ast_taken(
  92         ast_t           reasons,
  93         boolean_t       enable
  94 )
  95 {
  96         boolean_t               preempt_trap = (reasons == AST_PREEMPTION);
  97         ast_t                   *myast = ast_pending();
  98         thread_t                thread = current_thread();
  99
 100 #ifdef __ppc__
 101         /*
 102          * CHUD hook - all threads including idle processor threads
 103          */
 104         if(perfASTHook) {
 105                 if(*myast & AST_PPC_CHUD_ALL) {
 106                         perfASTHook(0, NULL, 0, 0);
 107
 108                         if(*myast == AST_NONE) {
 109                                 return; // nothing left to do
 110                         }
 111                 }
 112         } else {
 113                 *myast &= ~AST_PPC_CHUD_ALL;
 114         }
 115 #endif
 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                                 processor_t             myprocessor = current_processor();
 169
 170                                 if (csw_needed(thread, myprocessor))
 171                                         reasons = AST_PREEMPT;
 172                                 else
 173                                         reasons = AST_NONE;
 174                         }
 175                         if (    (reasons & AST_PREEMPT)                         &&
 176                                         wait_queue_assert_possible(thread)              ) {
 177                                 counter(c_ast_taken_block++);
 178                                 thread_block_reason((thread_continue_t)thread_exception_return, NULL, AST_PREEMPT);
 179                         }
 180                 }
 181         }
 182
 183         ml_set_interrupts_enabled(enable);
 184 }
 185
 186 /*
 187  * Called at splsched.
 188  */
 189 void
 190 ast_check(
 191         processor_t             processor)
 192 {
 193         register thread_t               thread = processor->active_thread;
 194
 195         processor->current_pri = thread->sched_pri;
 196         if (    processor->state == PROCESSOR_RUNNING           ||
 197                         processor->state == PROCESSOR_SHUTDOWN          ) {
 198                 register ast_t          preempt;
 199
 200                 /*
 201                  *      Propagate thread ast to processor.
 202                  */
 203                 ast_propagate(thread->ast);
 204
 205                 /*
 206                  *      Context switch check.
 207                  */
 208                 if ((preempt = csw_check(thread, processor)) != AST_NONE)
 209                         ast_on(preempt);
 210         }
 211 }