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All rights reserved. * * @APPLE_OSREFERENCE_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. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * 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_OSREFERENCE_LICENSE_HEADER_END@ */ /* * @OSF_COPYRIGHT@ */ /* */ #include <mach/mach_types.h> #include <kern/lock.h> #include <kern/spl.h> #include <kern/sched_prim.h> #include <kern/thread.h> #include <kern/clock.h> #include <kern/host_notify.h> #include <IOKit/IOPlatformExpert.h> #include <machine/commpage.h> #include <mach/mach_traps.h> #include <mach/mach_time.h> uint32_t hz_tick_interval = 1; decl_simple_lock_data(,clock_lock) #define clock_lock() \ simple_lock(&clock_lock) #define clock_unlock() \ simple_unlock(&clock_lock) #define clock_lock_init() \ simple_lock_init(&clock_lock, 0) /* * Time of day (calendar) variables. * * Algorithm: * * TOD <- (seconds + epoch, fraction) <- CONV(current absolute time + offset) * * where CONV converts absolute time units into seconds and a fraction. */ static struct clock_calend { uint64_t epoch; uint64_t offset; int32_t adjdelta; /* Nanosecond time delta for this adjustment period */ uint64_t adjstart; /* Absolute time value for start of this adjustment period */ uint32_t adjoffset; /* Absolute time offset for this adjustment period as absolute value */ } clock_calend; #if CONFIG_DTRACE /* * Unlocked calendar flipflop; this is used to track a clock_calend such * that we can safely access a snapshot of a valid clock_calend structure * without needing to take any locks to do it. * * The trick is to use a generation count and set the low bit when it is * being updated/read; by doing this, we guarantee, through use of the * hw_atomic functions, that the generation is incremented when the bit * is cleared atomically (by using a 1 bit add). */ static struct unlocked_clock_calend { struct clock_calend calend; /* copy of calendar */ uint32_t gen; /* generation count */ } flipflop[ 2]; static void clock_track_calend_nowait(void); #endif /* * Calendar adjustment variables and values. */ #define calend_adjperiod (NSEC_PER_SEC / 100) /* adjustment period, ns */ #define calend_adjskew (40 * NSEC_PER_USEC) /* "standard" skew, ns / period */ #define calend_adjbig (NSEC_PER_SEC) /* use 10x skew above adjbig ns */ static int64_t calend_adjtotal; /* Nanosecond remaining total adjustment */ static uint64_t calend_adjdeadline; /* Absolute time value for next adjustment period */ static uint32_t calend_adjinterval; /* Absolute time interval of adjustment period */ static timer_call_data_t calend_adjcall; static uint32_t calend_adjactive; static uint32_t calend_set_adjustment( long *secs, int *microsecs); static void calend_adjust_call(void); static uint32_t calend_adjust(void); static thread_call_data_t calend_wakecall; extern void IOKitResetTime(void); static uint64_t clock_boottime; /* Seconds boottime epoch */ #define TIME_ADD(rsecs, secs, rfrac, frac, unit) \ MACRO_BEGIN \ if (((rfrac) += (frac)) >= (unit)) { \ (rfrac) -= (unit); \ (rsecs) += 1; \ } \ (rsecs) += (secs); \ MACRO_END #define TIME_SUB(rsecs, secs, rfrac, frac, unit) \ MACRO_BEGIN \ if ((int)((rfrac) -= (frac)) < 0) { \ (rfrac) += (unit); \ (rsecs) -= 1; \ } \ (rsecs) -= (secs); \ MACRO_END /* * clock_config: * * Called once at boot to configure the clock subsystem. */ void clock_config(void) { clock_lock_init(); timer_call_setup(&calend_adjcall, (timer_call_func_t)calend_adjust_call, NULL); thread_call_setup(&calend_wakecall, (thread_call_func_t)IOKitResetTime, NULL); clock_oldconfig(); } /* * clock_init: * * Called on a processor each time started. */ void clock_init(void) { clock_oldinit(); } /* * clock_timebase_init: * * Called by machine dependent code * to initialize areas dependent on the * timebase value. May be called multiple * times during start up. */ void clock_timebase_init(void) { uint64_t abstime; nanoseconds_to_absolutetime(calend_adjperiod, &abstime); calend_adjinterval = (uint32_t)abstime; nanoseconds_to_absolutetime(NSEC_PER_SEC / 100, &abstime); hz_tick_interval = (uint32_t)abstime; sched_timebase_init(); } /* * mach_timebase_info_trap: * * User trap returns timebase constant. */ kern_return_t mach_timebase_info_trap( struct mach_timebase_info_trap_args *args) { mach_vm_address_t out_info_addr = args->info; mach_timebase_info_data_t info; clock_timebase_info(&info); copyout((void *)&info, out_info_addr, sizeof (info)); return (KERN_SUCCESS); } /* * Calendar routines. */ /* * clock_get_calendar_microtime: * * Returns the current calendar value, * microseconds as the fraction. */ void clock_get_calendar_microtime( clock_sec_t *secs, clock_usec_t *microsecs) { uint64_t now; spl_t s; s = splclock(); clock_lock(); now = mach_absolute_time(); if (clock_calend.adjdelta < 0) { uint32_t t32; /* * Since offset is decremented during a negative adjustment, * ensure that time increases monotonically without going * temporarily backwards. * If the delta has not yet passed, now is set to the start * of the current adjustment period; otherwise, we're between * the expiry of the delta and the next call to calend_adjust(), * and we offset accordingly. */ if (now > clock_calend.adjstart) { t32 = (uint32_t)(now - clock_calend.adjstart); if (t32 > clock_calend.adjoffset) now -= clock_calend.adjoffset; else now = clock_calend.adjstart; } } now += clock_calend.offset; absolutetime_to_microtime(now, secs, microsecs); *secs += (clock_sec_t)clock_calend.epoch; clock_unlock(); splx(s); } /* * clock_get_calendar_nanotime: * * Returns the current calendar value, * nanoseconds as the fraction. * * Since we do not have an interface to * set the calendar with resolution greater * than a microsecond, we honor that here. */ void clock_get_calendar_nanotime( clock_sec_t *secs, clock_nsec_t *nanosecs) { uint64_t now; spl_t s; s = splclock(); clock_lock(); now = mach_absolute_time(); if (clock_calend.adjdelta < 0) { uint32_t t32; if (now > clock_calend.adjstart) { t32 = (uint32_t)(now - clock_calend.adjstart); if (t32 > clock_calend.adjoffset) now -= clock_calend.adjoffset; else now = clock_calend.adjstart; } } now += clock_calend.offset; absolutetime_to_microtime(now, secs, nanosecs); *nanosecs *= NSEC_PER_USEC; *secs += (clock_sec_t)clock_calend.epoch; clock_unlock(); splx(s); } /* * clock_gettimeofday: * * Kernel interface for commpage implementation of * gettimeofday() syscall. * * Returns the current calendar value, and updates the * commpage info as appropriate. Because most calls to * gettimeofday() are handled in user mode by the commpage, * this routine should be used infrequently. */ void clock_gettimeofday( clock_sec_t *secs, clock_usec_t *microsecs) { uint64_t now; spl_t s; s = splclock(); clock_lock(); now = mach_absolute_time(); if (clock_calend.adjdelta >= 0) { clock_gettimeofday_set_commpage(now, clock_calend.epoch, clock_calend.offset, secs, microsecs); } else { uint32_t t32; if (now > clock_calend.adjstart) { t32 = (uint32_t)(now - clock_calend.adjstart); if (t32 > clock_calend.adjoffset) now -= clock_calend.adjoffset; else now = clock_calend.adjstart; } now += clock_calend.offset; absolutetime_to_microtime(now, secs, microsecs); *secs += (clock_sec_t)clock_calend.epoch; } clock_unlock(); splx(s); } /* * clock_set_calendar_microtime: * * Sets the current calendar value by * recalculating the epoch and offset * from the system clock. * * Also adjusts the boottime to keep the * value consistent, writes the new * calendar value to the platform clock, * and sends calendar change notifications. */ void clock_set_calendar_microtime( clock_sec_t secs, clock_usec_t microsecs) { clock_sec_t sys; clock_usec_t microsys; clock_sec_t newsecs; spl_t s; newsecs = (microsecs < 500*USEC_PER_SEC)? secs: secs + 1; s = splclock(); clock_lock(); commpage_disable_timestamp(); /* * Calculate the new calendar epoch based on * the new value and the system clock. */ clock_get_system_microtime(&sys, µsys); TIME_SUB(secs, sys, microsecs, microsys, USEC_PER_SEC); /* * Adjust the boottime based on the delta. */ clock_boottime += secs - clock_calend.epoch; /* * Set the new calendar epoch. */ clock_calend.epoch = secs; nanoseconds_to_absolutetime((uint64_t)microsecs * NSEC_PER_USEC, &clock_calend.offset); /* * Cancel any adjustment in progress. */ calend_adjtotal = clock_calend.adjdelta = 0; clock_unlock(); /* * Set the new value for the platform clock. */ PESetGMTTimeOfDay(newsecs); splx(s); /* * Send host notifications. */ host_notify_calendar_change(); #if CONFIG_DTRACE clock_track_calend_nowait(); #endif } /* * clock_initialize_calendar: * * Set the calendar and related clocks * from the platform clock at boot or * wake event. * * Also sends host notifications. */ void clock_initialize_calendar(void) { clock_sec_t sys, secs = PEGetGMTTimeOfDay(); clock_usec_t microsys, microsecs = 0; spl_t s; s = splclock(); clock_lock(); commpage_disable_timestamp(); if ((long)secs >= (long)clock_boottime) { /* * Initialize the boot time based on the platform clock. */ if (clock_boottime == 0) clock_boottime = secs; /* * Calculate the new calendar epoch based on * the platform clock and the system clock. */ clock_get_system_microtime(&sys, µsys); TIME_SUB(secs, sys, microsecs, microsys, USEC_PER_SEC); /* * Set the new calendar epoch. */ clock_calend.epoch = secs; nanoseconds_to_absolutetime((uint64_t)microsecs * NSEC_PER_USEC, &clock_calend.offset); /* * Cancel any adjustment in progress. */ calend_adjtotal = clock_calend.adjdelta = 0; } clock_unlock(); splx(s); /* * Send host notifications. */ host_notify_calendar_change(); #if CONFIG_DTRACE clock_track_calend_nowait(); #endif } /* * clock_get_boottime_nanotime: * * Return the boottime, used by sysctl. */ void clock_get_boottime_nanotime( clock_sec_t *secs, clock_nsec_t *nanosecs) { spl_t s; s = splclock(); clock_lock(); *secs = (clock_sec_t)clock_boottime; *nanosecs = 0; clock_unlock(); splx(s); } /* * clock_adjtime: * * Interface to adjtime() syscall. * * Calculates adjustment variables and * initiates adjustment. */ void clock_adjtime( long *secs, int *microsecs) { uint32_t interval; spl_t s; s = splclock(); clock_lock(); interval = calend_set_adjustment(secs, microsecs); if (interval != 0) { calend_adjdeadline = mach_absolute_time() + interval; if (!timer_call_enter(&calend_adjcall, calend_adjdeadline, TIMER_CALL_CRITICAL)) calend_adjactive++; } else if (timer_call_cancel(&calend_adjcall)) calend_adjactive--; clock_unlock(); splx(s); } static uint32_t calend_set_adjustment( long *secs, int *microsecs) { uint64_t now, t64; int64_t total, ototal; uint32_t interval = 0; /* * Compute the total adjustment time in nanoseconds. */ total = (int64_t)*secs * NSEC_PER_SEC + *microsecs * NSEC_PER_USEC; /* * Disable commpage gettimeofday(). */ commpage_disable_timestamp(); /* * Get current absolute time. */ now = mach_absolute_time(); /* * Save the old adjustment total for later return. */ ototal = calend_adjtotal; /* * Is a new correction specified? */ if (total != 0) { /* * Set delta to the standard, small, adjustment skew. */ int32_t delta = calend_adjskew; if (total > 0) { /* * Positive adjustment. If greater than the preset 'big' * threshold, slew at a faster rate, capping if necessary. */ if (total > calend_adjbig) delta *= 10; if (delta > total) delta = (int32_t)total; /* * Convert the delta back from ns to absolute time and store in adjoffset. */ nanoseconds_to_absolutetime((uint64_t)delta, &t64); clock_calend.adjoffset = (uint32_t)t64; } else { /* * Negative adjustment; therefore, negate the delta. If * greater than the preset 'big' threshold, slew at a faster * rate, capping if necessary. */ if (total < -calend_adjbig) delta *= 10; delta = -delta; if (delta < total) delta = (int32_t)total; /* * Save the current absolute time. Subsequent time operations occuring * during this negative correction can make use of this value to ensure * that time increases monotonically. */ clock_calend.adjstart = now; /* * Convert the delta back from ns to absolute time and store in adjoffset. */ nanoseconds_to_absolutetime((uint64_t)-delta, &t64); clock_calend.adjoffset = (uint32_t)t64; } /* * Store the total adjustment time in ns. */ calend_adjtotal = total; /* * Store the delta for this adjustment period in ns. */ clock_calend.adjdelta = delta; /* * Set the interval in absolute time for later return. */ interval = calend_adjinterval; } else { /* * No change; clear any prior adjustment. */ calend_adjtotal = clock_calend.adjdelta = 0; } /* * If an prior correction was in progress, return the * remaining uncorrected time from it. */ if (ototal != 0) { *secs = (long)(ototal / NSEC_PER_SEC); *microsecs = (int)((ototal % NSEC_PER_SEC) / NSEC_PER_USEC); } else *secs = *microsecs = 0; #if CONFIG_DTRACE clock_track_calend_nowait(); #endif return (interval); } static void calend_adjust_call(void) { uint32_t interval; spl_t s; s = splclock(); clock_lock(); if (--calend_adjactive == 0) { interval = calend_adjust(); if (interval != 0) { clock_deadline_for_periodic_event(interval, mach_absolute_time(), &calend_adjdeadline); if (!timer_call_enter(&calend_adjcall, calend_adjdeadline, TIMER_CALL_CRITICAL)) calend_adjactive++; } } clock_unlock(); splx(s); } static uint32_t calend_adjust(void) { uint64_t now, t64; int32_t delta; uint32_t interval = 0; commpage_disable_timestamp(); now = mach_absolute_time(); delta = clock_calend.adjdelta; if (delta > 0) { clock_calend.offset += clock_calend.adjoffset; calend_adjtotal -= delta; if (delta > calend_adjtotal) { clock_calend.adjdelta = delta = (int32_t)calend_adjtotal; nanoseconds_to_absolutetime((uint64_t)delta, &t64); clock_calend.adjoffset = (uint32_t)t64; } } else if (delta < 0) { clock_calend.offset -= clock_calend.adjoffset; calend_adjtotal -= delta; if (delta < calend_adjtotal) { clock_calend.adjdelta = delta = (int32_t)calend_adjtotal; nanoseconds_to_absolutetime((uint64_t)-delta, &t64); clock_calend.adjoffset = (uint32_t)t64; } if (clock_calend.adjdelta != 0) clock_calend.adjstart = now; } if (clock_calend.adjdelta != 0) interval = calend_adjinterval; #if CONFIG_DTRACE clock_track_calend_nowait(); #endif return (interval); } /* * clock_wakeup_calendar: * * Interface to power management, used * to initiate the reset of the calendar * on wake from sleep event. */ void clock_wakeup_calendar(void) { thread_call_enter(&calend_wakecall); } /* * Wait / delay routines. */ static void mach_wait_until_continue( __unused void *parameter, wait_result_t wresult) { thread_syscall_return((wresult == THREAD_INTERRUPTED)? KERN_ABORTED: KERN_SUCCESS); /*NOTREACHED*/ } kern_return_t mach_wait_until_trap( struct mach_wait_until_trap_args *args) { uint64_t deadline = args->deadline; wait_result_t wresult; wresult = assert_wait_deadline((event_t)mach_wait_until_trap, THREAD_ABORTSAFE, deadline); if (wresult == THREAD_WAITING) wresult = thread_block(mach_wait_until_continue); return ((wresult == THREAD_INTERRUPTED)? KERN_ABORTED: KERN_SUCCESS); } void clock_delay_until( uint64_t deadline) { uint64_t now = mach_absolute_time(); if (now >= deadline) return; if ( (deadline - now) < (8 * sched_cswtime) || get_preemption_level() != 0 || ml_get_interrupts_enabled() == FALSE ) machine_delay_until(deadline); else { assert_wait_deadline((event_t)clock_delay_until, THREAD_UNINT, deadline - sched_cswtime); thread_block(THREAD_CONTINUE_NULL); } } void delay_for_interval( uint32_t interval, uint32_t scale_factor) { uint64_t end; clock_interval_to_deadline(interval, scale_factor, &end); clock_delay_until(end); } void delay( int usec) { delay_for_interval((usec < 0)? -usec: usec, NSEC_PER_USEC); } /* * Miscellaneous routines. */ void clock_interval_to_deadline( uint32_t interval, uint32_t scale_factor, uint64_t *result) { uint64_t abstime; clock_interval_to_absolutetime_interval(interval, scale_factor, &abstime); *result = mach_absolute_time() + abstime; } void clock_absolutetime_interval_to_deadline( uint64_t abstime, uint64_t *result) { *result = mach_absolute_time() + abstime; } void clock_get_uptime( uint64_t *result) { *result = mach_absolute_time(); } void clock_deadline_for_periodic_event( uint64_t interval, uint64_t abstime, uint64_t *deadline) { assert(interval != 0); *deadline += interval; if (*deadline <= abstime) { *deadline = abstime + interval; abstime = mach_absolute_time(); if (*deadline <= abstime) *deadline = abstime + interval; } } #if CONFIG_DTRACE /* * clock_get_calendar_nanotime_nowait * * Description: Non-blocking version of clock_get_calendar_nanotime() * * Notes: This function operates by separately tracking calendar time * updates using a two element structure to copy the calendar * state, which may be asynchronously modified. It utilizes * barrier instructions in the tracking process and in the local * stable snapshot process in order to ensure that a consistent * snapshot is used to perform the calculation. */ void clock_get_calendar_nanotime_nowait( clock_sec_t *secs, clock_nsec_t *nanosecs) { int i = 0; uint64_t now; struct unlocked_clock_calend stable; for (;;) { stable = flipflop[i]; /* take snapshot */ /* * Use a barrier instructions to ensure atomicity. We AND * off the "in progress" bit to get the current generation * count. */ (void)hw_atomic_and(&stable.gen, ~(uint32_t)1); /* * If an update _is_ in progress, the generation count will be * off by one, if it _was_ in progress, it will be off by two, * and if we caught it at a good time, it will be equal (and * our snapshot is threfore stable). */ if (flipflop[i].gen == stable.gen) break; /* Switch to the oher element of the flipflop, and try again. */ i ^= 1; } now = mach_absolute_time(); if (stable.calend.adjdelta < 0) { uint32_t t32; if (now > stable.calend.adjstart) { t32 = (uint32_t)(now - stable.calend.adjstart); if (t32 > stable.calend.adjoffset) now -= stable.calend.adjoffset; else now = stable.calend.adjstart; } } now += stable.calend.offset; absolutetime_to_microtime(now, secs, nanosecs); *nanosecs *= NSEC_PER_USEC; *secs += (clock_sec_t)stable.calend.epoch; } static void clock_track_calend_nowait(void) { int i; for (i = 0; i < 2; i++) { struct clock_calend tmp = clock_calend; /* * Set the low bit if the generation count; since we use a * barrier instruction to do this, we are guaranteed that this * will flag an update in progress to an async caller trying * to examine the contents. */ (void)hw_atomic_or(&flipflop[i].gen, 1); flipflop[i].calend = tmp; /* * Increment the generation count to clear the low bit to * signal completion. If a caller compares the generation * count after taking a copy while in progress, the count * will be off by two. */ (void)hw_atomic_add(&flipflop[i].gen, 1); } } #endif /* CONFIG_DTRACE */ |