osfmk/kern/ast.c

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_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
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 /*
  31  * @OSF_COPYRIGHT@
  32  */
  33 /*
  34  * Mach Operating System
  35  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  36  * All Rights Reserved.
  37  *
  38  * Permission to use, copy, modify and distribute this software and its
  39  * documentation is hereby granted, provided that both the copyright
  40  * notice and this permission notice appear in all copies of the
  41  * software, derivative works or modified versions, and any portions
  42  * thereof, and that both notices appear in supporting documentation.
  43  *
  44  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  45  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  46  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  47  *
  48  * Carnegie Mellon requests users of this software to return to
  49  *
  50  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  51  *  School of Computer Science
  52  *  Carnegie Mellon University
  53  *  Pittsburgh PA 15213-3890
  54  *
  55  * any improvements or extensions that they make and grant Carnegie Mellon
  56  * the rights to redistribute these changes.
  57  */
  58 /*
  59  */
  60
  61 /*
  62  *
  63  *      This file contains routines to check whether an ast is needed.
  64  *
  65  *      ast_check() - check whether ast is needed for interrupt or context
  66  *      switch.  Usually called by clock interrupt handler.
  67  *
  68  */
  69
  70 #include <cputypes.h>
  71 #include <platforms.h>
  72
  73 #include <kern/ast.h>
  74 #include <kern/counters.h>
  75 #include <kern/cpu_number.h>
  76 #include <kern/misc_protos.h>
  77 #include <kern/queue.h>
  78 #include <kern/sched_prim.h>
  79 #include <kern/thread.h>
  80 #include <kern/processor.h>
  81 #include <kern/spl.h>
  82 #include <kern/wait_queue.h>
  83 #include <mach/policy.h>
  84
  85 #ifdef __ppc__
  86 #include <ppc/trap.h> // for CHUD AST hook
  87 #endif
  88
  89 void
  90 ast_init(void)
  91 {
  92 }
  93
  94 /*
  95  * Called at splsched.
  96  */
  97 void
  98 ast_taken(
  99         ast_t           reasons,
 100         boolean_t       enable
 101 )
 102 {
 103         boolean_t               preempt_trap = (reasons == AST_PREEMPTION);
 104         ast_t                   *myast = ast_pending();
 105         thread_t                thread = current_thread();
 106
 107 #ifdef __ppc__
 108         /*
 109          * CHUD hook - all threads including idle processor threads
 110          */
 111         if(perfASTHook) {
 112                 if(*myast & AST_PPC_CHUD_ALL) {
 113                         perfASTHook(0, NULL, 0, 0);
 114
 115                         if(*myast == AST_NONE) {
 116                                 return; // nothing left to do
 117                         }
 118                 }
 119         } else {
 120                 *myast &= ~AST_PPC_CHUD_ALL;
 121         }
 122 #endif
 123
 124         reasons &= *myast;
 125         *myast &= ~reasons;
 126
 127         /*
 128          * Handle ASTs for all threads
 129          * except idle processor threads.
 130          */
 131         if (!(thread->state & TH_IDLE)) {
 132                 /*
 133                  * Check for urgent preemption.
 134                  */
 135                 if (    (reasons & AST_URGENT)                          &&
 136                                 wait_queue_assert_possible(thread)              ) {
 137                         if (reasons & AST_PREEMPT) {
 138                                 counter(c_ast_taken_block++);
 139                                 thread_block_reason(THREAD_CONTINUE_NULL, NULL,
 140                                                                                 AST_PREEMPT | AST_URGENT);
 141                         }
 142
 143                         reasons &= ~AST_PREEMPTION;
 144                 }
 145
 146                 /*
 147                  * The kernel preempt traps
 148                  * skip all other ASTs.
 149                  */
 150                 if (!preempt_trap) {
 151                         ml_set_interrupts_enabled(enable);
 152
 153 #ifdef  MACH_BSD
 154                         /*
 155                          * Handle BSD hook.
 156                          */
 157                         if (reasons & AST_BSD) {
 158                                 thread_ast_clear(thread, AST_BSD);
 159                                 bsd_ast(thread);
 160                         }
 161 #endif
 162
 163                         /*
 164                          * Thread APC hook.
 165                          */
 166                         if (reasons & AST_APC)
 167                                 act_execute_returnhandlers();
 168
 169                         ml_set_interrupts_enabled(FALSE);
 170
 171                         /*
 172                          * Check for preemption.
 173                          */
 174                         if (reasons & AST_PREEMPT) {
 175                                 processor_t             myprocessor = current_processor();
 176
 177                                 if (csw_needed(thread, myprocessor))
 178                                         reasons = AST_PREEMPT;
 179                                 else
 180                                         reasons = AST_NONE;
 181                         }
 182                         if (    (reasons & AST_PREEMPT)                         &&
 183                                         wait_queue_assert_possible(thread)              ) {
 184                                 counter(c_ast_taken_block++);
 185                                 thread_block_reason((thread_continue_t)thread_exception_return, NULL, AST_PREEMPT);
 186                         }
 187                 }
 188         }
 189
 190         ml_set_interrupts_enabled(enable);
 191 }
 192
 193 /*
 194  * Called at splsched.
 195  */
 196 void
 197 ast_check(
 198         processor_t             processor)
 199 {
 200         register thread_t               thread = processor->active_thread;
 201
 202         processor->current_pri = thread->sched_pri;
 203         if (    processor->state == PROCESSOR_RUNNING           ||
 204                         processor->state == PROCESSOR_SHUTDOWN          ) {
 205                 register ast_t          preempt;
 206
 207                 /*
 208                  *      Propagate thread ast to processor.
 209                  */
 210                 ast_propagate(thread->ast);
 211
 212                 /*
 213                  *      Context switch check.
 214                  */
 215                 if ((preempt = csw_check(thread, processor)) != AST_NONE)
 216                         ast_on(preempt);
 217         }
 218 }