osfmk/kern/syscall_subr.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 #include <mach/boolean.h>
  54 #include <mach/thread_switch.h>
  55 #include <ipc/ipc_port.h>
  56 #include <ipc/ipc_space.h>
  57 #include <kern/counters.h>
  58 #include <kern/etap_macros.h>
  59 #include <kern/ipc_kobject.h>
  60 #include <kern/processor.h>
  61 #include <kern/sched.h>
  62 #include <kern/sched_prim.h>
  63 #include <kern/spl.h>
  64 #include <kern/task.h>
  65 #include <kern/thread.h>
  66 #include <kern/ast.h>
  67 #include <mach/policy.h>
  68
  69 #include <kern/syscall_subr.h>
  70 #include <mach/mach_host_server.h>
  71 #include <mach/mach_syscalls.h>
  72
  73 #include <kern/mk_sp.h>
  74
  75 /*
  76  *      swtch and swtch_pri both attempt to context switch (logic in
  77  *      thread_block no-ops the context switch if nothing would happen).
  78  *      A boolean is returned that indicates whether there is anything
  79  *      else runnable.
  80  *
  81  *      This boolean can be used by a thread waiting on a
  82  *      lock or condition:  If FALSE is returned, the thread is justified
  83  *      in becoming a resource hog by continuing to spin because there's
  84  *      nothing else useful that the processor could do.  If TRUE is
  85  *      returned, the thread should make one more check on the
  86  *      lock and then be a good citizen and really suspend.
  87  */
  88
  89 void
  90 swtch_continue(void)
  91 {
  92         register processor_t    myprocessor;
  93     boolean_t                           result;
  94
  95     mp_disable_preemption();
  96         myprocessor = current_processor();
  97         result =                myprocessor->runq.count > 0                                     ||
  98                                 myprocessor->processor_set->runq.count > 0;
  99         mp_enable_preemption();
 100
 101         thread_syscall_return(result);
 102         /*NOTREACHED*/
 103 }
 104
 105 boolean_t
 106 swtch(void)
 107 {
 108         register processor_t    myprocessor;
 109         boolean_t                               result;
 110
 111         mp_disable_preemption();
 112         myprocessor = current_processor();
 113         if (            myprocessor->runq.count == 0                            &&
 114                         myprocessor->processor_set->runq.count == 0                     ) {
 115                 mp_enable_preemption();
 116
 117                 return (FALSE);
 118         }
 119         mp_enable_preemption();
 120
 121         counter(c_swtch_block++);
 122
 123         thread_block(swtch_continue);
 124
 125         mp_disable_preemption();
 126         myprocessor = current_processor();
 127         result =                myprocessor->runq.count > 0                                     ||
 128                                 myprocessor->processor_set->runq.count > 0;
 129         mp_enable_preemption();
 130
 131         return (result);
 132 }
 133
 134 void
 135 swtch_pri_continue(void)
 136 {
 137         register processor_t    myprocessor;
 138     boolean_t                           result;
 139
 140         _mk_sp_thread_depress_abort(current_thread(), FALSE);
 141
 142     mp_disable_preemption();
 143         myprocessor = current_processor();
 144         result =                myprocessor->runq.count > 0                                     ||
 145                                 myprocessor->processor_set->runq.count > 0;
 146         mp_enable_preemption();
 147
 148         thread_syscall_return(result);
 149         /*NOTREACHED*/
 150 }
 151
 152 boolean_t
 153 swtch_pri(
 154         int                             pri)
 155 {
 156         register processor_t    myprocessor;
 157         boolean_t                               result;
 158
 159         mp_disable_preemption();
 160         myprocessor = current_processor();
 161         if (    myprocessor->runq.count == 0                                    &&
 162                         myprocessor->processor_set->runq.count == 0                     ) {
 163                 mp_enable_preemption();
 164
 165                 return (FALSE);
 166         }
 167         mp_enable_preemption();
 168
 169         counter(c_swtch_pri_block++);
 170
 171         _mk_sp_thread_depress_abstime(std_quantum);
 172
 173         thread_block(swtch_pri_continue);
 174
 175         _mk_sp_thread_depress_abort(current_thread(), FALSE);
 176
 177         mp_disable_preemption();
 178         myprocessor = current_processor();
 179         result =        myprocessor->runq.count > 0                                             ||
 180                                 myprocessor->processor_set->runq.count > 0;
 181         mp_enable_preemption();
 182
 183         return (result);
 184 }
 185
 186 /*
 187  *      thread_switch:
 188  *
 189  *      Context switch.  User may supply thread hint.
 190  */
 191 kern_return_t
 192 thread_switch(
 193         mach_port_name_t                thread_name,
 194         int                                             option,
 195         mach_msg_timeout_t              option_time)
 196 {
 197     register thread_t           self = current_thread();
 198     register thread_act_t       hint_act = THR_ACT_NULL;
 199
 200     /*
 201      *  Process option.
 202      */
 203     switch (option) {
 204
 205         case SWITCH_OPTION_NONE:
 206         case SWITCH_OPTION_DEPRESS:
 207         case SWITCH_OPTION_WAIT:
 208             break;
 209
 210         default:
 211             return (KERN_INVALID_ARGUMENT);
 212     }
 213
 214     if (thread_name != MACH_PORT_NULL) {
 215                 ipc_port_t                      port;
 216
 217                 if (ipc_port_translate_send(self->top_act->task->itk_space,
 218                                                                         thread_name, &port) == KERN_SUCCESS) {
 219                         ip_reference(port);
 220                         ip_unlock(port);
 221
 222                         hint_act = convert_port_to_act(port);
 223                         ipc_port_release(port);
 224                 }
 225         }
 226
 227     return _mk_sp_thread_switch(hint_act, option, option_time);
 228 }