osfmk/kern/ast.c

   1 /*
   2  * Copyright (c) 2000 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 <cpus.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/thread_act.h>
  74 #include <kern/thread_swap.h>
  75 #include <kern/processor.h>
  76 #include <kern/spl.h>
  77 #include <mach/policy.h>
  78
  79 volatile ast_t need_ast[NCPUS];
  80
  81 void
  82 ast_init(void)
  83 {
  84 #ifndef MACHINE_AST
  85         register int i;
  86
  87         for (i=0; i<NCPUS; i++) {
  88                 need_ast[i] = AST_NONE;
  89         }
  90 #endif  /* MACHINE_AST */
  91 }
  92
  93 /*
  94  * Called at splsched.
  95  */
  96 void
  97 ast_taken(
  98         ast_t                   reasons,
  99         boolean_t               enable
 100 )
 101 {
 102         register thread_t               self = current_thread();
 103         register int                    mycpu = cpu_number();
 104         boolean_t                               preempt_trap = (reasons == AST_PREEMPTION);
 105
 106         reasons &= need_ast[mycpu];
 107         need_ast[mycpu] &= ~reasons;
 108
 109         /*
 110          * Handle ASTs for all threads
 111          * except idle processor threads.
 112          */
 113         if (!(self->state & TH_IDLE)) {
 114                 /*
 115                  * Check for urgent preemption.
 116                  */
 117                 if (    (reasons & AST_URGENT)                          &&
 118                                 wait_queue_assert_possible(self)                ) {
 119                         if (reasons & AST_PREEMPT) {
 120                                 counter(c_ast_taken_block++);
 121                                 thread_block_reason(THREAD_CONTINUE_NULL,
 122                                                                                 AST_PREEMPT | AST_URGENT);
 123                         }
 124
 125                         reasons &= ~AST_PREEMPTION;
 126                 }
 127
 128                 /*
 129                  * The kernel preempt traps
 130                  * skip all other ASTs.
 131                  */
 132                 if (!preempt_trap) {
 133                         ml_set_interrupts_enabled(enable);
 134
 135 #ifdef  MACH_BSD
 136                         /*
 137                          * Handle BSD hook.
 138                          */
 139                         if (reasons & AST_BSD) {
 140                                 extern void             bsd_ast(thread_act_t    act);
 141                                 thread_act_t    act = self->top_act;
 142
 143                                 thread_ast_clear(act, AST_BSD);
 144                                 bsd_ast(act);
 145                         }
 146 #endif
 147
 148                         /*
 149                          * Thread APC hook.
 150                          */
 151                         if (reasons & AST_APC)
 152                                 act_execute_returnhandlers();
 153
 154                         ml_set_interrupts_enabled(FALSE);
 155
 156                         /*
 157                          * Check for preemption.
 158                          */
 159                         if (reasons & AST_PREEMPT) {
 160                                 processor_t             myprocessor = current_processor();
 161
 162                                 if (csw_needed(self, myprocessor))
 163                                         reasons = AST_PREEMPT;
 164                                 else
 165                                         reasons = AST_NONE;
 166                         }
 167                         if (    (reasons & AST_PREEMPT)                         &&
 168                                         wait_queue_assert_possible(self)                ) {
 169                                 counter(c_ast_taken_block++);
 170                                 thread_block_reason(thread_exception_return, AST_PREEMPT);
 171                         }
 172                 }
 173         }
 174
 175         ml_set_interrupts_enabled(enable);
 176 }
 177
 178 /*
 179  * Called at splsched.
 180  */
 181 void
 182 ast_check(
 183         processor_t             processor)
 184 {
 185         register thread_t               self = processor->active_thread;
 186
 187         processor->current_pri = self->sched_pri;
 188         if (processor->state == PROCESSOR_RUNNING) {
 189                 register ast_t          preempt;
 190 processor_running:
 191
 192                 /*
 193                  *      Propagate thread ast to processor.
 194                  */
 195                 ast_propagate(self->top_act->ast);
 196
 197                 /*
 198                  *      Context switch check.
 199                  */
 200                 if ((preempt = csw_check(self, processor)) != AST_NONE)
 201                         ast_on(preempt);
 202         }
 203         else
 204         if (    processor->state == PROCESSOR_DISPATCHING       ||
 205                         processor->state == PROCESSOR_IDLE                      ) {
 206                 return;
 207         }
 208         else
 209         if (processor->state == PROCESSOR_SHUTDOWN)
 210                 goto processor_running;
 211 }