/*
* Copyright (c) 2008 Apple Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
#include <sys/time.h>
#include <mach/mach_time.h>
#include <machine/cpu_capabilities.h>
#include <os/overflow.h>
#include <kern/arithmetic_128.h>
int __commpage_gettimeofday(struct timeval *);
__attribute__((visibility("hidden")))
int __commpage_gettimeofday_internal(struct timeval *tp, uint64_t *tbr_out);
int
__commpage_gettimeofday(struct timeval *tp)
{
return __commpage_gettimeofday_internal(tp, NULL);
}
int
__commpage_gettimeofday_internal(struct timeval *tp, uint64_t *tbr_out)
{
uint64_t now, over;
uint64_t delta, frac;
uint64_t TimeStamp_tick;
uint64_t TimeStamp_sec;
uint64_t TimeStamp_frac;
uint64_t Tick_scale;
uint64_t Ticks_per_sec;
volatile uint64_t *gtod_TimeStamp_tick_p;
volatile uint64_t *gtod_TimeStamp_sec_p;
volatile uint64_t *gtod_TimeStamp_frac_p;
volatile uint64_t *gtod_Ticks_scale_p;
volatile uint64_t *gtod_Ticks_per_sec_p;
COMM_PAGE_SLOT_TYPE(new_commpage_timeofday_data_t) commpage_timeofday_datap =
COMM_PAGE_SLOT(new_commpage_timeofday_data_t, NEWTIMEOFDAY_DATA);
gtod_TimeStamp_tick_p = &commpage_timeofday_datap->TimeStamp_tick;
gtod_TimeStamp_sec_p = &commpage_timeofday_datap->TimeStamp_sec;
gtod_TimeStamp_frac_p = &commpage_timeofday_datap->TimeStamp_frac;
gtod_Ticks_scale_p = &commpage_timeofday_datap->Ticks_scale;
gtod_Ticks_per_sec_p = &commpage_timeofday_datap->Ticks_per_sec;
do {
TimeStamp_tick = *gtod_TimeStamp_tick_p;
/*
* This call contains an instruction barrier which will ensure that the
* second read of the abs time isn't speculated above the reads of the
* other values above
*/
now = mach_absolute_time();
TimeStamp_sec = *gtod_TimeStamp_sec_p;
TimeStamp_frac = *gtod_TimeStamp_frac_p;
Tick_scale = *gtod_Ticks_scale_p;
Ticks_per_sec = *gtod_Ticks_per_sec_p;
/*
* This barrier prevents the reordering of the second read of gtod_TimeStamp_tick_p
* w.r.t the values read just after mach_absolute_time is invoked.
*/
#if (__ARM_ARCH__ >= 7)
__asm__ volatile ("dmb ishld" ::: "memory");
#endif
} while (TimeStamp_tick != *gtod_TimeStamp_tick_p);
if (TimeStamp_tick == 0) {
return 1;
}
delta = now - TimeStamp_tick;
/* If more than one second force a syscall */
if (delta >= Ticks_per_sec) {
return 1;
}
if (TimeStamp_sec > __LONG_MAX__) {
return 1;
}
tp->tv_sec = (__darwin_time_t)TimeStamp_sec;
over = multi_overflow(Tick_scale, delta);
if (over) {
tp->tv_sec += over;
}
/* Sum scale*delta to TimeStamp_frac, if it overflows increment sec */
frac = TimeStamp_frac;
frac += Tick_scale * delta;
if (TimeStamp_frac > frac) {
tp->tv_sec++;
}
/*
* Convert frac (64 bit frac of a sec) to usec
* usec = frac * USEC_PER_SEC / 2^64
*/
tp->tv_usec = ((uint64_t)1000000 * (uint32_t)(frac >> 32)) >> 32;
if (tbr_out) {
*tbr_out = now;
}
return 0;
}