osfmk/kern/ast.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * @OSF_COPYRIGHT@
  27  */
  28 /*
  29  * Mach Operating System
  30  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  31  * All Rights Reserved.
  32  *
  33  * Permission to use, copy, modify and distribute this software and its
  34  * documentation is hereby granted, provided that both the copyright
  35  * notice and this permission notice appear in all copies of the
  36  * software, derivative works or modified versions, and any portions
  37  * thereof, and that both notices appear in supporting documentation.
  38  *
  39  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  40  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  41  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  42  *
  43  * Carnegie Mellon requests users of this software to return to
  44  *
  45  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  46  *  School of Computer Science
  47  *  Carnegie Mellon University
  48  *  Pittsburgh PA 15213-3890
  49  *
  50  * any improvements or extensions that they make and grant Carnegie Mellon
  51  * the rights to redistribute these changes.
  52  */
  53 /*
  54  */
  55
  56 /*
  57  *
  58  *      This file contains routines to check whether an ast is needed.
  59  *
  60  *      ast_check() - check whether ast is needed for interrupt or context
  61  *      switch.  Usually called by clock interrupt handler.
  62  *
  63  */
  64
  65 #include <cputypes.h>
  66 #include <cpus.h>
  67 #include <platforms.h>
  68
  69 #include <kern/ast.h>
  70 #include <kern/counters.h>
  71 #include <kern/cpu_number.h>
  72 #include <kern/misc_protos.h>
  73 #include <kern/queue.h>
  74 #include <kern/sched_prim.h>
  75 #include <kern/thread.h>
  76 #include <kern/thread_act.h>
  77 #include <kern/thread_swap.h>
  78 #include <kern/processor.h>
  79 #include <kern/spl.h>
  80 #include <mach/policy.h>
  81
  82 volatile ast_t need_ast[NCPUS];
  83
  84 void
  85 ast_init(void)
  86 {
  87 #ifndef MACHINE_AST
  88         register int i;
  89
  90         for (i=0; i<NCPUS; i++) {
  91                 need_ast[i] = AST_NONE;
  92         }
  93 #endif  /* MACHINE_AST */
  94 }
  95
  96 void
  97 ast_taken(
  98         ast_t                   reasons,
  99         boolean_t               enable
 100 )
 101 {
 102         register int                    mycpu;
 103         register processor_t    myprocessor;
 104         register thread_t               self = current_thread();
 105         boolean_t                               preempt_trap = (reasons == AST_PREEMPT);
 106
 107         disable_preemption();
 108         mycpu = cpu_number();
 109         reasons &= need_ast[mycpu];
 110         need_ast[mycpu] &= ~reasons;
 111         enable_preemption();
 112
 113         /*
 114          * No ast for an idle thread
 115          */
 116         if (self->state & TH_IDLE)
 117                 goto enable_and_return;
 118
 119         /*
 120          * Check for urgent preemption
 121          */
 122         if ((reasons & AST_URGENT) && wait_queue_assert_possible(self)) {
 123                 if (reasons & AST_BLOCK) {
 124                         counter(c_ast_taken_block++);
 125                         thread_block_reason((void (*)(void))0, AST_BLOCK);
 126                 }
 127
 128                 reasons &= ~AST_PREEMPT;
 129                 if (reasons == 0)
 130                         goto enable_and_return;
 131         }
 132
 133         if (preempt_trap)
 134                 goto enable_and_return;
 135
 136         ml_set_interrupts_enabled(enable);
 137
 138 #ifdef  MACH_BSD
 139         /*
 140          * Check for BSD hook
 141          */
 142         if (reasons & AST_BSD) {
 143                 extern void             bsd_ast(thread_act_t    act);
 144                 thread_act_t    act = self->top_act;
 145
 146                 thread_ast_clear(act, AST_BSD);
 147                 bsd_ast(act);
 148         }
 149 #endif
 150
 151         /*
 152          * migration APC hook
 153          */
 154         if (reasons & AST_APC) {
 155                 act_execute_returnhandlers();
 156         }
 157
 158         /*
 159          * Check for normal preemption
 160          */
 161         reasons &= AST_BLOCK;
 162     if (reasons == 0) {
 163         disable_preemption();
 164         myprocessor = current_processor();
 165         if (csw_needed(self, myprocessor))
 166             reasons = AST_BLOCK;
 167         enable_preemption();
 168     }
 169         if (    (reasons & AST_BLOCK)                           &&
 170                         wait_queue_assert_possible(self)                ) {
 171                 counter(c_ast_taken_block++);
 172                 thread_block_reason(thread_exception_return, AST_BLOCK);
 173         }
 174
 175         goto just_return;
 176
 177 enable_and_return:
 178     ml_set_interrupts_enabled(enable);
 179
 180 just_return:
 181         return;
 182 }
 183
 184 /*
 185  * Called at splsched.
 186  */
 187 void
 188 ast_check(
 189         processor_t             processor)
 190 {
 191         register thread_t               self = processor->cpu_data->active_thread;
 192
 193         processor->current_pri = self->sched_pri;
 194         if (processor->state == PROCESSOR_RUNNING) {
 195                 register ast_t          preempt;
 196 processor_running:
 197
 198                 /*
 199                  *      Propagate thread ast to processor.
 200                  */
 201                 ast_propagate(self->top_act->ast);
 202
 203                 /*
 204                  *      Context switch check.
 205                  */
 206                 if ((preempt = csw_check(self, processor)) != AST_NONE)
 207                         ast_on(preempt);
 208         }
 209         else
 210         if (    processor->state == PROCESSOR_DISPATCHING       ||
 211                         processor->state == PROCESSOR_IDLE                      ) {
 212                 return;
 213         }
 214         else
 215         if (processor->state == PROCESSOR_SHUTDOWN)
 216                 goto processor_running;
 217         else
 218         if (processor->state == PROCESSOR_ASSIGN)
 219                 ast_on(AST_BLOCK);
 220 }