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 void
  94 ast_taken(
  95         ast_t                   reasons,
  96         boolean_t               enable
  97 )
  98 {
  99         register int                    mycpu;
 100         register processor_t    myprocessor;
 101         register thread_t               self = current_thread();
 102         boolean_t                               preempt_trap = (reasons == AST_PREEMPT);
 103
 104         disable_preemption();
 105         mycpu = cpu_number();
 106         reasons &= need_ast[mycpu];
 107         need_ast[mycpu] &= ~reasons;
 108         enable_preemption();
 109
 110         /*
 111          * No ast for an idle thread
 112          */
 113         if (self->state & TH_IDLE)
 114                 goto enable_and_return;
 115
 116         /*
 117          * Check for urgent preemption
 118          */
 119         if ((reasons & AST_URGENT) && wait_queue_assert_possible(self)) {
 120                 if (reasons & AST_BLOCK) {
 121                         counter(c_ast_taken_block++);
 122                         thread_block_reason((void (*)(void))0, AST_BLOCK);
 123                 }
 124
 125                 reasons &= ~AST_PREEMPT;
 126                 if (reasons == 0)
 127                         goto enable_and_return;
 128         }
 129
 130         if (preempt_trap)
 131                 goto enable_and_return;
 132
 133         ml_set_interrupts_enabled(enable);
 134
 135 #ifdef  MACH_BSD
 136         /*
 137          * Check for 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          * migration APC hook
 150          */
 151         if (reasons & AST_APC) {
 152                 act_execute_returnhandlers();
 153         }
 154
 155         /*
 156          * Check for normal preemption
 157          */
 158         reasons &= AST_BLOCK;
 159     if (reasons == 0) {
 160         disable_preemption();
 161         myprocessor = current_processor();
 162         if (csw_needed(self, myprocessor))
 163             reasons = AST_BLOCK;
 164         enable_preemption();
 165     }
 166         if (    (reasons & AST_BLOCK)                           &&
 167                         wait_queue_assert_possible(self)                ) {
 168                 counter(c_ast_taken_block++);
 169                 thread_block_reason(thread_exception_return, AST_BLOCK);
 170         }
 171
 172         goto just_return;
 173
 174 enable_and_return:
 175     ml_set_interrupts_enabled(enable);
 176
 177 just_return:
 178         return;
 179 }
 180
 181 /*
 182  * Called at splsched.
 183  */
 184 void
 185 ast_check(
 186         processor_t             processor)
 187 {
 188         register thread_t               self = processor->cpu_data->active_thread;
 189
 190         processor->current_pri = self->sched_pri;
 191         if (processor->state == PROCESSOR_RUNNING) {
 192                 register ast_t          preempt;
 193 processor_running:
 194
 195                 /*
 196                  *      Propagate thread ast to processor.
 197                  */
 198                 ast_propagate(self->top_act->ast);
 199
 200                 /*
 201                  *      Context switch check.
 202                  */
 203                 if ((preempt = csw_check(self, processor)) != AST_NONE)
 204                         ast_on(preempt);
 205         }
 206         else
 207         if (    processor->state == PROCESSOR_DISPATCHING       ||
 208                         processor->state == PROCESSOR_IDLE                      ) {
 209                 return;
 210         }
 211         else
 212         if (processor->state == PROCESSOR_SHUTDOWN)
 213                 goto processor_running;
 214         else
 215         if (processor->state == PROCESSOR_ASSIGN)
 216                 ast_on(AST_BLOCK);
 217 }