1  /*
  2   * Copyright (c) 2000-2018 Apple Inc. All rights reserved.
  3   *
  4   * @APPLE_OSREFERENCE_LICENSE_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 License
 10   * may not be used to create, or enable the creation or redistribution of,
 11   * unlawful or unlicensed copies of an Apple operating system, or to
 12   * circumvent, violate, or enable the circumvention or violation of, any
 13   * terms of an Apple operating system software license agreement.
 14   *
 15   * Please obtain a copy of the License at
 16   * http://www.opensource.apple.com/apsl/ and read it before using this file.
 17   *
 18   * The Original Code and all software distributed under the License are
 19   * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 20   * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 21   * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 22   * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 23   * Please see the License for the specific language governing rights and
 24   * limitations under the License.
 25   *
 26   * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 27   */
 28  /*
 29   * @OSF_COPYRIGHT@
 30   */
 31  /*
 32   * Mach Operating System
 33   * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 34   * All Rights Reserved.
 35   *
 36   * Permission to use, copy, modify and distribute this software and its
 37   * documentation is hereby granted, provided that both the copyright
 38   * notice and this permission notice appear in all copies of the
 39   * software, derivative works or modified versions, and any portions
 40   * thereof, and that both notices appear in supporting documentation.
 41   *
 42   * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 43   * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 44   * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 45   *
 46   * Carnegie Mellon requests users of this software to return to
 47   *
 48   *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 49   *  School of Computer Science
 50   *  Carnegie Mellon University
 51   *  Pittsburgh PA 15213-3890
 52   *
 53   * any improvements or extensions that they make and grant Carnegie Mellon
 54   * the rights to redistribute these changes.
 55   */
 56  
 57  #include <mach/kern_return.h>
 58  #include <mach/port.h>
 59  #include <kern/queue.h>
 60  #include <kern/processor.h>
 61  #include <kern/thread.h>
 62  #include <kern/sched_prim.h>
 63  #include <kern/timer.h>
 64  
 65  #include <machine/config.h>
 66  
 67  #if CONFIG_SKIP_PRECISE_USER_KERNEL_TIME && !HAS_FAST_CNTVCT
 68  int precise_user_kernel_time = 0;
 69  #else
 70  int precise_user_kernel_time = 1;
 71  #endif
 72  
 73  void
 74  timer_init(timer_t timer)
 75  {
 76  	memset(timer, 0, sizeof(*timer));
 77  }
 78  
 79  uint64_t
 80  timer_delta(timer_t timer, uint64_t *prev_in_cur_out)
 81  {
 82  	uint64_t old = *prev_in_cur_out;
 83  	uint64_t new = *prev_in_cur_out = timer_grab(timer);
 84  	return new - old;
 85  }
 86  
 87  static void
 88  timer_advance(timer_t timer, uint64_t delta)
 89  {
 90  #if defined(__LP64__)
 91  	timer->all_bits += delta;
 92  #else /* defined(__LP64__) */
 93  	extern void timer_advance_internal_32(timer_t timer, uint32_t high,
 94  	    uint32_t low);
 95  	uint64_t low = delta + timer->low_bits;
 96  	if (low >> 32) {
 97  		timer_advance_internal_32(timer,
 98  		    (uint32_t)(timer->high_bits + (low >> 32)), (uint32_t)low);
 99  	} else {
100  		timer->low_bits = (uint32_t)low;
101  	}
102  #endif /* defined(__LP64__) */
103  }
104  
105  void
106  timer_start(timer_t timer, uint64_t tstamp)
107  {
108  	timer->tstamp = tstamp;
109  }
110  
111  void
112  timer_stop(timer_t timer, uint64_t tstamp)
113  {
114  	timer_advance(timer, tstamp - timer->tstamp);
115  }
116  
117  void
118  timer_update(timer_t timer, uint64_t tstamp)
119  {
120  	timer_advance(timer, tstamp - timer->tstamp);
121  	timer->tstamp = tstamp;
122  }
123  
124  void
125  timer_switch(timer_t timer, uint64_t tstamp, timer_t new_timer)
126  {
127  	timer_advance(timer, tstamp - timer->tstamp);
128  	new_timer->tstamp = tstamp;
129  }
130  
131  /*
132   * Update the current processor's thread timer with `tstamp` and switch the
133   * processor's thread timer to `new_timer`.
134   *
135   * Called with interrupts disabled.
136   */
137  void
138  processor_timer_switch_thread(uint64_t tstamp, timer_t new_timer)
139  {
140  	processor_t processor = current_processor();
141  	timer_t timer;
142  
143  	/* Update current timer. */
144  	timer = processor->thread_timer;
145  	timer_advance(timer, tstamp - timer->tstamp);
146  
147  	/* Start new timer. */
148  	processor->thread_timer = new_timer;
149  	new_timer->tstamp = tstamp;
150  }