diff options
Diffstat (limited to 'kernel/timer.c')
| -rw-r--r-- | kernel/timer.c | 1611 |
1 files changed, 1611 insertions, 0 deletions
diff --git a/kernel/timer.c b/kernel/timer.c new file mode 100644 index 0000000..ecb3d67 --- /dev/null +++ b/kernel/timer.c @@ -0,0 +1,1611 @@ +/* + * linux/kernel/timer.c + * + * Kernel internal timers, kernel timekeeping, basic process system calls + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better. + * + * 1997-09-10 Updated NTP code according to technical memorandum Jan '96 + * "A Kernel Model for Precision Timekeeping" by Dave Mills + * 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to + * serialize accesses to xtime/lost_ticks). + * Copyright (C) 1998 Andrea Arcangeli + * 1999-03-10 Improved NTP compatibility by Ulrich Windl + * 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love + * 2000-10-05 Implemented scalable SMP per-CPU timer handling. + * Copyright (C) 2000, 2001, 2002 Ingo Molnar + * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar + */ + +#include <linux/kernel_stat.h> +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/percpu.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/swap.h> +#include <linux/notifier.h> +#include <linux/thread_info.h> +#include <linux/time.h> +#include <linux/jiffies.h> +#include <linux/posix-timers.h> +#include <linux/cpu.h> +#include <linux/syscalls.h> + +#include <asm/uaccess.h> +#include <asm/unistd.h> +#include <asm/div64.h> +#include <asm/timex.h> +#include <asm/io.h> + +#ifdef CONFIG_TIME_INTERPOLATION +static void time_interpolator_update(long delta_nsec); +#else +#define time_interpolator_update(x) +#endif + +/* + * per-CPU timer vector definitions: + */ + +#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6) +#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8) +#define TVN_SIZE (1 << TVN_BITS) +#define TVR_SIZE (1 << TVR_BITS) +#define TVN_MASK (TVN_SIZE - 1) +#define TVR_MASK (TVR_SIZE - 1) + +typedef struct tvec_s { + struct list_head vec[TVN_SIZE]; +} tvec_t; + +typedef struct tvec_root_s { + struct list_head vec[TVR_SIZE]; +} tvec_root_t; + +struct tvec_t_base_s { + spinlock_t lock; + unsigned long timer_jiffies; + struct timer_list *running_timer; + tvec_root_t tv1; + tvec_t tv2; + tvec_t tv3; + tvec_t tv4; + tvec_t tv5; +} ____cacheline_aligned_in_smp; + +typedef struct tvec_t_base_s tvec_base_t; + +static inline void set_running_timer(tvec_base_t *base, + struct timer_list *timer) +{ +#ifdef CONFIG_SMP + base->running_timer = timer; +#endif +} + +/* Fake initialization */ +static DEFINE_PER_CPU(tvec_base_t, tvec_bases) = { SPIN_LOCK_UNLOCKED }; + +static void check_timer_failed(struct timer_list *timer) +{ + static int whine_count; + if (whine_count < 16) { + whine_count++; + printk("Uninitialised timer!\n"); + printk("This is just a warning. Your computer is OK\n"); + printk("function=0x%p, data=0x%lx\n", + timer->function, timer->data); + dump_stack(); + } + /* + * Now fix it up + */ + spin_lock_init(&timer->lock); + timer->magic = TIMER_MAGIC; +} + +static inline void check_timer(struct timer_list *timer) +{ + if (timer->magic != TIMER_MAGIC) + check_timer_failed(timer); +} + + +static void internal_add_timer(tvec_base_t *base, struct timer_list *timer) +{ + unsigned long expires = timer->expires; + unsigned long idx = expires - base->timer_jiffies; + struct list_head *vec; + + if (idx < TVR_SIZE) { + int i = expires & TVR_MASK; + vec = base->tv1.vec + i; + } else if (idx < 1 << (TVR_BITS + TVN_BITS)) { + int i = (expires >> TVR_BITS) & TVN_MASK; + vec = base->tv2.vec + i; + } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) { + int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK; + vec = base->tv3.vec + i; + } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) { + int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK; + vec = base->tv4.vec + i; + } else if ((signed long) idx < 0) { + /* + * Can happen if you add a timer with expires == jiffies, + * or you set a timer to go off in the past + */ + vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK); + } else { + int i; + /* If the timeout is larger than 0xffffffff on 64-bit + * architectures then we use the maximum timeout: + */ + if (idx > 0xffffffffUL) { + idx = 0xffffffffUL; + expires = idx + base->timer_jiffies; + } + i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK; + vec = base->tv5.vec + i; + } + /* + * Timers are FIFO: + */ + list_add_tail(&timer->entry, vec); +} + +int __mod_timer(struct timer_list *timer, unsigned long expires) +{ + tvec_base_t *old_base, *new_base; + unsigned long flags; + int ret = 0; + + BUG_ON(!timer->function); + + check_timer(timer); + + spin_lock_irqsave(&timer->lock, flags); + new_base = &__get_cpu_var(tvec_bases); +repeat: + old_base = timer->base; + + /* + * Prevent deadlocks via ordering by old_base < new_base. + */ + if (old_base && (new_base != old_base)) { + if (old_base < new_base) { + spin_lock(&new_base->lock); + spin_lock(&old_base->lock); + } else { + spin_lock(&old_base->lock); + spin_lock(&new_base->lock); + } + /* + * The timer base might have been cancelled while we were + * trying to take the lock(s): + */ + if (timer->base != old_base) { + spin_unlock(&new_base->lock); + spin_unlock(&old_base->lock); + goto repeat; + } + } else { + spin_lock(&new_base->lock); + if (timer->base != old_base) { + spin_unlock(&new_base->lock); + goto repeat; + } + } + + /* + * Delete the previous timeout (if there was any), and install + * the new one: + */ + if (old_base) { + list_del(&timer->entry); + ret = 1; + } + timer->expires = expires; + internal_add_timer(new_base, timer); + timer->base = new_base; + + if (old_base && (new_base != old_base)) + spin_unlock(&old_base->lock); + spin_unlock(&new_base->lock); + spin_unlock_irqrestore(&timer->lock, flags); + + return ret; +} + +EXPORT_SYMBOL(__mod_timer); + +/*** + * add_timer_on - start a timer on a particular CPU + * @timer: the timer to be added + * @cpu: the CPU to start it on + * + * This is not very scalable on SMP. Double adds are not possible. + */ +void add_timer_on(struct timer_list *timer, int cpu) +{ + tvec_base_t *base = &per_cpu(tvec_bases, cpu); + unsigned long flags; + + BUG_ON(timer_pending(timer) || !timer->function); + + check_timer(timer); + + spin_lock_irqsave(&base->lock, flags); + internal_add_timer(base, timer); + timer->base = base; + spin_unlock_irqrestore(&base->lock, flags); +} + + +/*** + * mod_timer - modify a timer's timeout + * @timer: the timer to be modified + * + * mod_timer is a more efficient way to update the expire field of an + * active timer (if the timer is inactive it will be activated) + * + * mod_timer(timer, expires) is equivalent to: + * + * del_timer(timer); timer->expires = expires; add_timer(timer); + * + * Note that if there are multiple unserialized concurrent users of the + * same timer, then mod_timer() is the only safe way to modify the timeout, + * since add_timer() cannot modify an already running timer. + * + * The function returns whether it has modified a pending timer or not. + * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an + * active timer returns 1.) + */ +int mod_timer(struct timer_list *timer, unsigned long expires) +{ + BUG_ON(!timer->function); + + check_timer(timer); + + /* + * This is a common optimization triggered by the + * networking code - if the timer is re-modified + * to be the same thing then just return: + */ + if (timer->expires == expires && timer_pending(timer)) + return 1; + + return __mod_timer(timer, expires); +} + +EXPORT_SYMBOL(mod_timer); + +/*** + * del_timer - deactive a timer. + * @timer: the timer to be deactivated + * + * del_timer() deactivates a timer - this works on both active and inactive + * timers. + * + * The function returns whether it has deactivated a pending timer or not. + * (ie. del_timer() of an inactive timer returns 0, del_timer() of an + * active timer returns 1.) + */ +int del_timer(struct timer_list *timer) +{ + unsigned long flags; + tvec_base_t *base; + + check_timer(timer); + +repeat: + base = timer->base; + if (!base) + return 0; + spin_lock_irqsave(&base->lock, flags); + if (base != timer->base) { + spin_unlock_irqrestore(&base->lock, flags); + goto repeat; + } + list_del(&timer->entry); + /* Need to make sure that anybody who sees a NULL base also sees the list ops */ + smp_wmb(); + timer->base = NULL; + spin_unlock_irqrestore(&base->lock, flags); + + return 1; +} + +EXPORT_SYMBOL(del_timer); + +#ifdef CONFIG_SMP +/*** + * del_timer_sync - deactivate a timer and wait for the handler to finish. + * @timer: the timer to be deactivated + * + * This function only differs from del_timer() on SMP: besides deactivating + * the timer it also makes sure the handler has finished executing on other + * CPUs. + * + * Synchronization rules: callers must prevent restarting of the timer, + * otherwise this function is meaningless. It must not be called from + * interrupt contexts. The caller must not hold locks which would prevent + * completion of the timer's handler. Upon exit the timer is not queued and + * the handler is not running on any CPU. + * + * The function returns whether it has deactivated a pending timer or not. + * + * del_timer_sync() is slow and complicated because it copes with timer + * handlers which re-arm the timer (periodic timers). If the timer handler + * is known to not do this (a single shot timer) then use + * del_singleshot_timer_sync() instead. + */ +int del_timer_sync(struct timer_list *timer) +{ + tvec_base_t *base; + int i, ret = 0; + + check_timer(timer); + +del_again: + ret += del_timer(timer); + + for_each_online_cpu(i) { + base = &per_cpu(tvec_bases, i); + if (base->running_timer == timer) { + while (base->running_timer == timer) { + cpu_relax(); + preempt_check_resched(); + } + break; + } + } + smp_rmb(); + if (timer_pending(timer)) + goto del_again; + + return ret; +} +EXPORT_SYMBOL(del_timer_sync); + +/*** + * del_singleshot_timer_sync - deactivate a non-recursive timer + * @timer: the timer to be deactivated + * + * This function is an optimization of del_timer_sync for the case where the + * caller can guarantee the timer does not reschedule itself in its timer + * function. + * + * Synchronization rules: callers must prevent restarting of the timer, + * otherwise this function is meaningless. It must not be called from + * interrupt contexts. The caller must not hold locks which wold prevent + * completion of the timer's handler. Upon exit the timer is not queued and + * the handler is not running on any CPU. + * + * The function returns whether it has deactivated a pending timer or not. + */ +int del_singleshot_timer_sync(struct timer_list *timer) +{ + int ret = del_timer(timer); + + if (!ret) { + ret = del_timer_sync(timer); + BUG_ON(ret); + } + + return ret; +} +EXPORT_SYMBOL(del_singleshot_timer_sync); +#endif + +static int cascade(tvec_base_t *base, tvec_t *tv, int index) +{ + /* cascade all the timers from tv up one level */ + struct list_head *head, *curr; + + head = tv->vec + index; + curr = head->next; + /* + * We are removing _all_ timers from the list, so we don't have to + * detach them individually, just clear the list afterwards. + */ + while (curr != head) { + struct timer_list *tmp; + + tmp = list_entry(curr, struct timer_list, entry); + BUG_ON(tmp->base != base); + curr = curr->next; + internal_add_timer(base, tmp); + } + INIT_LIST_HEAD(head); + + return index; +} + +/*** + * __run_timers - run all expired timers (if any) on this CPU. + * @base: the timer vector to be processed. + * + * This function cascades all vectors and executes all expired timer + * vectors. + */ +#define INDEX(N) (base->timer_jiffies >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK + +static inline void __run_timers(tvec_base_t *base) +{ + struct timer_list *timer; + + spin_lock_irq(&base->lock); + while (time_after_eq(jiffies, base->timer_jiffies)) { + struct list_head work_list = LIST_HEAD_INIT(work_list); + struct list_head *head = &work_list; + int index = base->timer_jiffies & TVR_MASK; + + /* + * Cascade timers: + */ + if (!index && + (!cascade(base, &base->tv2, INDEX(0))) && + (!cascade(base, &base->tv3, INDEX(1))) && + !cascade(base, &base->tv4, INDEX(2))) + cascade(base, &base->tv5, INDEX(3)); + ++base->timer_jiffies; + list_splice_init(base->tv1.vec + index, &work_list); +repeat: + if (!list_empty(head)) { + void (*fn)(unsigned long); + unsigned long data; + + timer = list_entry(head->next,struct timer_list,entry); + fn = timer->function; + data = timer->data; + + list_del(&timer->entry); + set_running_timer(base, timer); + smp_wmb(); + timer->base = NULL; + spin_unlock_irq(&base->lock); + { + u32 preempt_count = preempt_count(); + fn(data); + if (preempt_count != preempt_count()) { + printk("huh, entered %p with %08x, exited with %08x?\n", fn, preempt_count, preempt_count()); + BUG(); + } + } + spin_lock_irq(&base->lock); + goto repeat; + } + } + set_running_timer(base, NULL); + spin_unlock_irq(&base->lock); +} + +#ifdef CONFIG_NO_IDLE_HZ +/* + * Find out when the next timer event is due to happen. This + * is used on S/390 to stop all activity when a cpus is idle. + * This functions needs to be called disabled. + */ +unsigned long next_timer_interrupt(void) +{ + tvec_base_t *base; + struct list_head *list; + struct timer_list *nte; + unsigned long expires; + tvec_t *varray[4]; + int i, j; + + base = &__get_cpu_var(tvec_bases); + spin_lock(&base->lock); + expires = base->timer_jiffies + (LONG_MAX >> 1); + list = 0; + + /* Look for timer events in tv1. */ + j = base->timer_jiffies & TVR_MASK; + do { + list_for_each_entry(nte, base->tv1.vec + j, entry) { + expires = nte->expires; + if (j < (base->timer_jiffies & TVR_MASK)) + list = base->tv2.vec + (INDEX(0)); + goto found; + } + j = (j + 1) & TVR_MASK; + } while (j != (base->timer_jiffies & TVR_MASK)); + + /* Check tv2-tv5. */ + varray[0] = &base->tv2; + varray[1] = &base->tv3; + varray[2] = &base->tv4; + varray[3] = &base->tv5; + for (i = 0; i < 4; i++) { + j = INDEX(i); + do { + if (list_empty(varray[i]->vec + j)) { + j = (j + 1) & TVN_MASK; + continue; + } + list_for_each_entry(nte, varray[i]->vec + j, entry) + if (time_before(nte->expires, expires)) + expires = nte->expires; + if (j < (INDEX(i)) && i < 3) + list = varray[i + 1]->vec + (INDEX(i + 1)); + goto found; + } while (j != (INDEX(i))); + } +found: + if (list) { + /* + * The search wrapped. We need to look at the next list + * from next tv element that would cascade into tv element + * where we found the timer element. + */ + list_for_each_entry(nte, list, entry) { + if (time_before(nte->expires, expires)) + expires = nte->expires; + } + } + spin_unlock(&base->lock); + return expires; +} +#endif + +/******************************************************************/ + +/* + * Timekeeping variables + */ +unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */ +unsigned long tick_nsec = TICK_NSEC; /* ACTHZ period (nsec) */ + +/* + * The current time + * wall_to_monotonic is what we need to add to xtime (or xtime corrected + * for sub jiffie times) to get to monotonic time. Monotonic is pegged + * at zero at system boot time, so wall_to_monotonic will be negative, + * however, we will ALWAYS keep the tv_nsec part positive so we can use + * the usual normalization. + */ +struct timespec xtime __attribute__ ((aligned (16))); +struct timespec wall_to_monotonic __attribute__ ((aligned (16))); + +EXPORT_SYMBOL(xtime); + +/* Don't completely fail for HZ > 500. */ +int tickadj = 500/HZ ? : 1; /* microsecs */ + + +/* + * phase-lock loop variables + */ +/* TIME_ERROR prevents overwriting the CMOS clock */ +int time_state = TIME_OK; /* clock synchronization status */ +int time_status = STA_UNSYNC; /* clock status bits */ +long time_offset; /* time adjustment (us) */ +long time_constant = 2; /* pll time constant */ +long time_tolerance = MAXFREQ; /* frequency tolerance (ppm) */ +long time_precision = 1; /* clock precision (us) */ +long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */ +long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */ +static long time_phase; /* phase offset (scaled us) */ +long time_freq = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC; + /* frequency offset (scaled ppm)*/ +static long time_adj; /* tick adjust (scaled 1 / HZ) */ +long time_reftime; /* time at last adjustment (s) */ +long time_adjust; +long time_next_adjust; + +/* + * this routine handles the overflow of the microsecond field + * + * The tricky bits of code to handle the accurate clock support + * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame. + * They were originally developed for SUN and DEC kernels. + * All the kudos should go to Dave for this stuff. + * + */ +static void second_overflow(void) +{ + long ltemp; + + /* Bump the maxerror field */ + time_maxerror += time_tolerance >> SHIFT_USEC; + if ( time_maxerror > NTP_PHASE_LIMIT ) { + time_maxerror = NTP_PHASE_LIMIT; + time_status |= STA_UNSYNC; + } + + /* + * Leap second processing. If in leap-insert state at + * the end of the day, the system clock is set back one + * second; if in leap-delete state, the system clock is + * set ahead one second. The microtime() routine or + * external clock driver will insure that reported time + * is always monotonic. The ugly divides should be + * replaced. + */ + switch (time_state) { + + case TIME_OK: + if (time_status & STA_INS) + time_state = TIME_INS; + else if (time_status & STA_DEL) + time_state = TIME_DEL; + break; + + case TIME_INS: + if (xtime.tv_sec % 86400 == 0) { + xtime.tv_sec--; + wall_to_monotonic.tv_sec++; + /* The timer interpolator will make time change gradually instead + * of an immediate jump by one second. + */ + time_interpolator_update(-NSEC_PER_SEC); + time_state = TIME_OOP; + clock_was_set(); + printk(KERN_NOTICE "Clock: inserting leap second 23:59:60 UTC\n"); + } + break; + + case TIME_DEL: + if ((xtime.tv_sec + 1) % 86400 == 0) { + xtime.tv_sec++; + wall_to_monotonic.tv_sec--; + /* Use of time interpolator for a gradual change of time */ + time_interpolator_update(NSEC_PER_SEC); + time_state = TIME_WAIT; + clock_was_set(); + printk(KERN_NOTICE "Clock: deleting leap second 23:59:59 UTC\n"); + } + break; + + case TIME_OOP: + time_state = TIME_WAIT; + break; + + case TIME_WAIT: + if (!(time_status & (STA_INS | STA_DEL))) + time_state = TIME_OK; + } + + /* + * Compute the phase adjustment for the next second. In + * PLL mode, the offset is reduced by a fixed factor + * times the time constant. In FLL mode the offset is + * used directly. In either mode, the maximum phase + * adjustment for each second is clamped so as to spread + * the adjustment over not more than the number of + * seconds between updates. + */ + if (time_offset < 0) { + ltemp = -time_offset; + if (!(time_status & STA_FLL)) + ltemp >>= SHIFT_KG + time_constant; + if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE) + ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE; + time_offset += ltemp; + time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE); + } else { + ltemp = time_offset; + if (!(time_status & STA_FLL)) + ltemp >>= SHIFT_KG + time_constant; + if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE) + ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE; + time_offset -= ltemp; + time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE); + } + + /* + * Compute the frequency estimate and additional phase + * adjustment due to frequency error for the next + * second. When the PPS signal is engaged, gnaw on the + * watchdog counter and update the frequency computed by + * the pll and the PPS signal. + */ + pps_valid++; + if (pps_valid == PPS_VALID) { /* PPS signal lost */ + pps_jitter = MAXTIME; + pps_stabil = MAXFREQ; + time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER | + STA_PPSWANDER | STA_PPSERROR); + } + ltemp = time_freq + pps_freq; + if (ltemp < 0) + time_adj -= -ltemp >> + (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE); + else + time_adj += ltemp >> + (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE); + +#if HZ == 100 + /* Compensate for (HZ==100) != (1 << SHIFT_HZ). + * Add 25% and 3.125% to get 128.125; => only 0.125% error (p. 14) + */ + if (time_adj < 0) + time_adj -= (-time_adj >> 2) + (-time_adj >> 5); + else + time_adj += (time_adj >> 2) + (time_adj >> 5); +#endif +#if HZ == 1000 + /* Compensate for (HZ==1000) != (1 << SHIFT_HZ). + * Add 1.5625% and 0.78125% to get 1023.4375; => only 0.05% error (p. 14) + */ + if (time_adj < 0) + time_adj -= (-time_adj >> 6) + (-time_adj >> 7); + else + time_adj += (time_adj >> 6) + (time_adj >> 7); +#endif +} + +/* in the NTP reference this is called "hardclock()" */ +static void update_wall_time_one_tick(void) +{ + long time_adjust_step, delta_nsec; + + if ( (time_adjust_step = time_adjust) != 0 ) { + /* We are doing an adjtime thing. + * + * Prepare time_adjust_step to be within bounds. + * Note that a positive time_adjust means we want the clock + * to run faster. + * + * Limit the amount of the step to be in the range + * -tickadj .. +tickadj + */ + if (time_adjust > tickadj) + time_adjust_step = tickadj; + else if (time_adjust < -tickadj) + time_adjust_step = -tickadj; + + /* Reduce by this step the amount of time left */ + time_adjust -= time_adjust_step; + } + delta_nsec = tick_nsec + time_adjust_step * 1000; + /* + * Advance the phase, once it gets to one microsecond, then + * advance the tick more. + */ + time_phase += time_adj; + if (time_phase <= -FINENSEC) { + long ltemp = -time_phase >> (SHIFT_SCALE - 10); + time_phase += ltemp << (SHIFT_SCALE - 10); + delta_nsec -= ltemp; + } + else if (time_phase >= FINENSEC) { + long ltemp = time_phase >> (SHIFT_SCALE - 10); + time_phase -= ltemp << (SHIFT_SCALE - 10); + delta_nsec += ltemp; + } + xtime.tv_nsec += delta_nsec; + time_interpolator_update(delta_nsec); + + /* Changes by adjtime() do not take effect till next tick. */ + if (time_next_adjust != 0) { + time_adjust = time_next_adjust; + time_next_adjust = 0; + } +} + +/* + * Using a loop looks inefficient, but "ticks" is + * usually just one (we shouldn't be losing ticks, + * we're doing this this way mainly for interrupt + * latency reasons, not because we think we'll + * have lots of lost timer ticks + */ +static void update_wall_time(unsigned long ticks) +{ + do { + ticks--; + update_wall_time_one_tick(); + if (xtime.tv_nsec >= 1000000000) { + xtime.tv_nsec -= 1000000000; + xtime.tv_sec++; + second_overflow(); + } + } while (ticks); +} + +/* + * Called from the timer interrupt handler to charge one tick to the current + * process. user_tick is 1 if the tick is user time, 0 for system. + */ +void update_process_times(int user_tick) +{ + struct task_struct *p = current; + int cpu = smp_processor_id(); + + /* Note: this timer irq context must be accounted for as well. */ + if (user_tick) + account_user_time(p, jiffies_to_cputime(1)); + else + account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1)); + run_local_timers(); + if (rcu_pending(cpu)) + rcu_check_callbacks(cpu, user_tick); + scheduler_tick(); + run_posix_cpu_timers(p); +} + +/* + * Nr of active tasks - counted in fixed-point numbers + */ +static unsigned long count_active_tasks(void) +{ + return (nr_running() + nr_uninterruptible()) * FIXED_1; +} + +/* + * Hmm.. Changed this, as the GNU make sources (load.c) seems to + * imply that avenrun[] is the standard name for this kind of thing. + * Nothing else seems to be standardized: the fractional size etc + * all seem to differ on different machines. + * + * Requires xtime_lock to access. + */ +unsigned long avenrun[3]; + +EXPORT_SYMBOL(avenrun); + +/* + * calc_load - given tick count, update the avenrun load estimates. + * This is called while holding a write_lock on xtime_lock. + */ +static inline void calc_load(unsigned long ticks) +{ + unsigned long active_tasks; /* fixed-point */ + static int count = LOAD_FREQ; + + count -= ticks; + if (count < 0) { + count += LOAD_FREQ; + active_tasks = count_active_tasks(); + CALC_LOAD(avenrun[0], EXP_1, active_tasks); + CALC_LOAD(avenrun[1], EXP_5, active_tasks); + CALC_LOAD(avenrun[2], EXP_15, active_tasks); + } +} + +/* jiffies at the most recent update of wall time */ +unsigned long wall_jiffies = INITIAL_JIFFIES; + +/* + * This read-write spinlock protects us from races in SMP while + * playing with xtime and avenrun. + */ +#ifndef ARCH_HAVE_XTIME_LOCK +seqlock_t xtime_lock __cacheline_aligned_in_smp = SEQLOCK_UNLOCKED; + +EXPORT_SYMBOL(xtime_lock); +#endif + +/* + * This function runs timers and the timer-tq in bottom half context. + */ +static void run_timer_softirq(struct softirq_action *h) +{ + tvec_base_t *base = &__get_cpu_var(tvec_bases); + + if (time_after_eq(jiffies, base->timer_jiffies)) + __run_timers(base); +} + +/* + * Called by the local, per-CPU timer interrupt on SMP. + */ +void run_local_timers(void) +{ + raise_softirq(TIMER_SOFTIRQ); +} + +/* + * Called by the timer interrupt. xtime_lock must already be taken + * by the timer IRQ! + */ +static inline void update_times(void) +{ + unsigned long ticks; + + ticks = jiffies - wall_jiffies; + if (ticks) { + wall_jiffies += ticks; + update_wall_time(ticks); + } + calc_load(ticks); +} + +/* + * The 64-bit jiffies value is not atomic - you MUST NOT read it + * without sampling the sequence number in xtime_lock. + * jiffies is defined in the linker script... + */ + +void do_timer(struct pt_regs *regs) +{ + jiffies_64++; + update_times(); +} + +#ifdef __ARCH_WANT_SYS_ALARM + +/* + * For backwards compatibility? This can be done in libc so Alpha + * and all newer ports shouldn't need it. + */ +asmlinkage unsigned long sys_alarm(unsigned int seconds) +{ + struct itimerval it_new, it_old; + unsigned int oldalarm; + + it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0; + it_new.it_value.tv_sec = seconds; + it_new.it_value.tv_usec = 0; + do_setitimer(ITIMER_REAL, &it_new, &it_old); + oldalarm = it_old.it_value.tv_sec; + /* ehhh.. We can't return 0 if we have an alarm pending.. */ + /* And we'd better return too much than too little anyway */ + if ((!oldalarm && it_old.it_value.tv_usec) || it_old.it_value.tv_usec >= 500000) + oldalarm++; + return oldalarm; +} + +#endif + +#ifndef __alpha__ + +/* + * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this + * should be moved into arch/i386 instead? + */ + +/** + * sys_getpid - return the thread group id of the current process + * + * Note, despite the name, this returns the tgid not the pid. The tgid and + * the pid are identical unless CLONE_THREAD was specified on clone() in + * which case the tgid is the same in all threads of the same group. + * + * This is SMP safe as current->tgid does not change. + */ +asmlinkage long sys_getpid(void) +{ + return current->tgid; +} + +/* + * Accessing ->group_leader->real_parent is not SMP-safe, it could + * change from under us. However, rather than getting any lock + * we can use an optimistic algorithm: get the parent + * pid, and go back and check that the parent is still + * the same. If it has changed (which is extremely unlikely + * indeed), we just try again.. + * + * NOTE! This depends on the fact that even if we _do_ + * get an old value of "parent", we can happily dereference + * the pointer (it was and remains a dereferencable kernel pointer + * no matter what): we just can't necessarily trust the result + * until we know that the parent pointer is valid. + * + * NOTE2: ->group_leader never changes from under us. + */ +asmlinkage long sys_getppid(void) +{ + int pid; + struct task_struct *me = current; + struct task_struct *parent; + + parent = me->group_leader->real_parent; + for (;;) { + pid = parent->tgid; +#ifdef CONFIG_SMP +{ + struct task_struct *old = parent; + + /* + * Make sure we read the pid before re-reading the + * parent pointer: + */ + rmb(); + parent = me->group_leader->real_parent; + if (old != parent) + continue; +} +#endif + break; + } + return pid; +} + +asmlinkage long sys_getuid(void) +{ + /* Only we change this so SMP safe */ + return current->uid; +} + +asmlinkage long sys_geteuid(void) +{ + /* Only we change this so SMP safe */ + return current->euid; +} + +asmlinkage long sys_getgid(void) +{ + /* Only we change this so SMP safe */ + return current->gid; +} + +asmlinkage long sys_getegid(void) +{ + /* Only we change this so SMP safe */ + return current->egid; +} + +#endif + +static void process_timeout(unsigned long __data) +{ + wake_up_process((task_t *)__data); +} + +/** + * schedule_timeout - sleep until timeout + * @timeout: timeout value in jiffies + * + * Make the current task sleep until @timeout jiffies have + * elapsed. The routine will return immediately unless + * the current task state has been set (see set_current_state()). + * + * You can set the task state as follows - + * + * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to + * pass before the routine returns. The routine will return 0 + * + * %TASK_INTERRUPTIBLE - the routine may return early if a signal is + * delivered to the current task. In this case the remaining time + * in jiffies will be returned, or 0 if the timer expired in time + * + * The current task state is guaranteed to be TASK_RUNNING when this + * routine returns. + * + * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule + * the CPU away without a bound on the timeout. In this case the return + * value will be %MAX_SCHEDULE_TIMEOUT. + * + * In all cases the return value is guaranteed to be non-negative. + */ +fastcall signed long __sched schedule_timeout(signed long timeout) +{ + struct timer_list timer; + unsigned long expire; + + switch (timeout) + { + case MAX_SCHEDULE_TIMEOUT: + /* + * These two special cases are useful to be comfortable + * in the caller. Nothing more. We could take + * MAX_SCHEDULE_TIMEOUT from one of the negative value + * but I' d like to return a valid offset (>=0) to allow + * the caller to do everything it want with the retval. + */ + schedule(); + goto out; + default: + /* + * Another bit of PARANOID. Note that the retval will be + * 0 since no piece of kernel is supposed to do a check + * for a negative retval of schedule_timeout() (since it + * should never happens anyway). You just have the printk() + * that will tell you if something is gone wrong and where. + */ + if (timeout < 0) + { + printk(KERN_ERR "schedule_timeout: wrong timeout " + "value %lx from %p\n", timeout, + __builtin_return_address(0)); + current->state = TASK_RUNNING; + goto out; + } + } + + expire = timeout + jiffies; + + init_timer(&timer); + timer.expires = expire; + timer.data = (unsigned long) current; + timer.function = process_timeout; + + add_timer(&timer); + schedule(); + del_singleshot_timer_sync(&timer); + + timeout = expire - jiffies; + + out: + return timeout < 0 ? 0 : timeout; +} + +EXPORT_SYMBOL(schedule_timeout); + +/* Thread ID - the internal kernel "pid" */ +asmlinkage long sys_gettid(void) +{ + return current->pid; +} + +static long __sched nanosleep_restart(struct restart_block *restart) +{ + unsigned long expire = restart->arg0, now = jiffies; + struct timespec __user *rmtp = (struct timespec __user *) restart->arg1; + long ret; + + /* Did it expire while we handled signals? */ + if (!time_after(expire, now)) + return 0; + + current->state = TASK_INTERRUPTIBLE; + expire = schedule_timeout(expire - now); + + ret = 0; + if (expire) { + struct timespec t; + jiffies_to_timespec(expire, &t); + + ret = -ERESTART_RESTARTBLOCK; + if (rmtp && copy_to_user(rmtp, &t, sizeof(t))) + ret = -EFAULT; + /* The 'restart' block is already filled in */ + } + return ret; +} + +asmlinkage long sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp) +{ + struct timespec t; + unsigned long expire; + long ret; + + if (copy_from_user(&t, rqtp, sizeof(t))) + return -EFAULT; + + if ((t.tv_nsec >= 1000000000L) || (t.tv_nsec < 0) || (t.tv_sec < 0)) + return -EINVAL; + + expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec); + current->state = TASK_INTERRUPTIBLE; + expire = schedule_timeout(expire); + + ret = 0; + if (expire) { + struct restart_block *restart; + jiffies_to_timespec(expire, &t); + if (rmtp && copy_to_user(rmtp, &t, sizeof(t))) + return -EFAULT; + + restart = ¤t_thread_info()->restart_block; + restart->fn = nanosleep_restart; + restart->arg0 = jiffies + expire; + restart->arg1 = (unsigned long) rmtp; + ret = -ERESTART_RESTARTBLOCK; + } + return ret; +} + +/* + * sys_sysinfo - fill in sysinfo struct + */ +asmlinkage long sys_sysinfo(struct sysinfo __user *info) +{ + struct sysinfo val; + unsigned long mem_total, sav_total; + unsigned int mem_unit, bitcount; + unsigned long seq; + + memset((char *)&val, 0, sizeof(struct sysinfo)); + + do { + struct timespec tp; + seq = read_seqbegin(&xtime_lock); + + /* + * This is annoying. The below is the same thing + * posix_get_clock_monotonic() does, but it wants to + * take the lock which we want to cover the loads stuff + * too. + */ + + getnstimeofday(&tp); + tp.tv_sec += wall_to_monotonic.tv_sec; + tp.tv_nsec += wall_to_monotonic.tv_nsec; + if (tp.tv_nsec - NSEC_PER_SEC >= 0) { + tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC; + tp.tv_sec++; + } + val.uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0); + + val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT); + val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT); + val.loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT); + + val.procs = nr_threads; + } while (read_seqretry(&xtime_lock, seq)); + + si_meminfo(&val); + si_swapinfo(&val); + + /* + * If the sum of all the available memory (i.e. ram + swap) + * is less than can be stored in a 32 bit unsigned long then + * we can be binary compatible with 2.2.x kernels. If not, + * well, in that case 2.2.x was broken anyways... + * + * -Erik Andersen <andersee@debian.org> + */ + + mem_total = val.totalram + val.totalswap; + if (mem_total < val.totalram || mem_total < val.totalswap) + goto out; + bitcount = 0; + mem_unit = val.mem_unit; + while (mem_unit > 1) { + bitcount++; + mem_unit >>= 1; + sav_total = mem_total; + mem_total <<= 1; + if (mem_total < sav_total) + goto out; + } + + /* + * If mem_total did not overflow, multiply all memory values by + * val.mem_unit and set it to 1. This leaves things compatible + * with 2.2.x, and also retains compatibility with earlier 2.4.x + * kernels... + */ + + val.mem_unit = 1; + val.totalram <<= bitcount; + val.freeram <<= bitcount; + val.sharedram <<= bitcount; + val.bufferram <<= bitcount; + val.totalswap <<= bitcount; + val.freeswap <<= bitcount; + val.totalhigh <<= bitcount; + val.freehigh <<= bitcount; + + out: + if (copy_to_user(info, &val, sizeof(struct sysinfo))) + return -EFAULT; + + return 0; +} + +static void __devinit init_timers_cpu(int cpu) +{ + int j; + tvec_base_t *base; + + base = &per_cpu(tvec_bases, cpu); + spin_lock_init(&base->lock); + for (j = 0; j < TVN_SIZE; j++) { + INIT_LIST_HEAD(base->tv5.vec + j); + INIT_LIST_HEAD(base->tv4.vec + j); + INIT_LIST_HEAD(base->tv3.vec + j); + INIT_LIST_HEAD(base->tv2.vec + j); + } + for (j = 0; j < TVR_SIZE; j++) + INIT_LIST_HEAD(base->tv1.vec + j); + + base->timer_jiffies = jiffies; +} + +#ifdef CONFIG_HOTPLUG_CPU +static int migrate_timer_list(tvec_base_t *new_base, struct list_head *head) +{ + struct timer_list *timer; + + while (!list_empty(head)) { + timer = list_entry(head->next, struct timer_list, entry); + /* We're locking backwards from __mod_timer order here, + beware deadlock. */ + if (!spin_trylock(&timer->lock)) + return 0; + list_del(&timer->entry); + internal_add_timer(new_base, timer); + timer->base = new_base; + spin_unlock(&timer->lock); + } + return 1; +} + +static void __devinit migrate_timers(int cpu) +{ + tvec_base_t *old_base; + tvec_base_t *new_base; + int i; + + BUG_ON(cpu_online(cpu)); + old_base = &per_cpu(tvec_bases, cpu); + new_base = &get_cpu_var(tvec_bases); + + local_irq_disable(); +again: + /* Prevent deadlocks via ordering by old_base < new_base. */ + if (old_base < new_base) { + spin_lock(&new_base->lock); + spin_lock(&old_base->lock); + } else { + spin_lock(&old_base->lock); + spin_lock(&new_base->lock); + } + + if (old_base->running_timer) + BUG(); + for (i = 0; i < TVR_SIZE; i++) + if (!migrate_timer_list(new_base, old_base->tv1.vec + i)) + goto unlock_again; + for (i = 0; i < TVN_SIZE; i++) + if (!migrate_timer_list(new_base, old_base->tv2.vec + i) + || !migrate_timer_list(new_base, old_base->tv3.vec + i) + || !migrate_timer_list(new_base, old_base->tv4.vec + i) + || !migrate_timer_list(new_base, old_base->tv5.vec + i)) + goto unlock_again; + spin_unlock(&old_base->lock); + spin_unlock(&new_base->lock); + local_irq_enable(); + put_cpu_var(tvec_bases); + return; + +unlock_again: + /* Avoid deadlock with __mod_timer, by backing off. */ + spin_unlock(&old_base->lock); + spin_unlock(&new_base->lock); + cpu_relax(); + goto again; +} +#endif /* CONFIG_HOTPLUG_CPU */ + +static int __devinit timer_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + long cpu = (long)hcpu; + switch(action) { + case CPU_UP_PREPARE: + init_timers_cpu(cpu); + break; +#ifdef CONFIG_HOTPLUG_CPU + case CPU_DEAD: + migrate_timers(cpu); + break; +#endif + default: + break; + } + return NOTIFY_OK; +} + +static struct notifier_block __devinitdata timers_nb = { + .notifier_call = timer_cpu_notify, +}; + + +void __init init_timers(void) +{ + timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE, + (void *)(long)smp_processor_id()); + register_cpu_notifier(&timers_nb); + open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL); +} + +#ifdef CONFIG_TIME_INTERPOLATION + +struct time_interpolator *time_interpolator; +static struct time_interpolator *time_interpolator_list; +static DEFINE_SPINLOCK(time_interpolator_lock); + +static inline u64 time_interpolator_get_cycles(unsigned int src) +{ + unsigned long (*x)(void); + + switch (src) + { + case TIME_SOURCE_FUNCTION: + x = time_interpolator->addr; + return x(); + + case TIME_SOURCE_MMIO64 : + return readq((void __iomem *) time_interpolator->addr); + + case TIME_SOURCE_MMIO32 : + return readl((void __iomem *) time_interpolator->addr); + + default: return get_cycles(); + } +} + +static inline u64 time_interpolator_get_counter(void) +{ + unsigned int src = time_interpolator->source; + + if (time_interpolator->jitter) + { + u64 lcycle; + u64 now; + + do { + lcycle = time_interpolator->last_cycle; + now = time_interpolator_get_cycles(src); + if (lcycle && time_after(lcycle, now)) + return lcycle; + /* Keep track of the last timer value returned. The use of cmpxchg here + * will cause contention in an SMP environment. + */ + } while (unlikely(cmpxchg(&time_interpolator->last_cycle, lcycle, now) != lcycle)); + return now; + } + else + return time_interpolator_get_cycles(src); +} + +void time_interpolator_reset(void) +{ + time_interpolator->offset = 0; + time_interpolator->last_counter = time_interpolator_get_counter(); +} + +#define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift) + +unsigned long time_interpolator_get_offset(void) +{ + /* If we do not have a time interpolator set up then just return zero */ + if (!time_interpolator) + return 0; + + return time_interpolator->offset + + GET_TI_NSECS(time_interpolator_get_counter(), time_interpolator); +} + +#define INTERPOLATOR_ADJUST 65536 +#define INTERPOLATOR_MAX_SKIP 10*INTERPOLATOR_ADJUST + +static void time_interpolator_update(long delta_nsec) +{ + u64 counter; + unsigned long offset; + + /* If there is no time interpolator set up then do nothing */ + if (!time_interpolator) + return; + + /* The interpolator compensates for late ticks by accumulating + * the late time in time_interpolator->offset. A tick earlier than + * expected will lead to a reset of the offset and a corresponding + * jump of the clock forward. Again this only works if the + * interpolator clock is running slightly slower than the regular clock + * and the tuning logic insures that. + */ + + counter = time_interpolator_get_counter(); + offset = time_interpolator->offset + GET_TI_NSECS(counter, time_interpolator); + + if (delta_nsec < 0 || (unsigned long) delta_nsec < offset) + time_interpolator->offset = offset - delta_nsec; + else { + time_interpolator->skips++; + time_interpolator->ns_skipped += delta_nsec - offset; + time_interpolator->offset = 0; + } + time_interpolator->last_counter = counter; + + /* Tuning logic for time interpolator invoked every minute or so. + * Decrease interpolator clock speed if no skips occurred and an offset is carried. + * Increase interpolator clock speed if we skip too much time. + */ + if (jiffies % INTERPOLATOR_ADJUST == 0) + { + if (time_interpolator->skips == 0 && time_interpolator->offset > TICK_NSEC) + time_interpolator->nsec_per_cyc--; + if (time_interpolator->ns_skipped > INTERPOLATOR_MAX_SKIP && time_interpolator->offset == 0) + time_interpolator->nsec_per_cyc++; + time_interpolator->skips = 0; + time_interpolator->ns_skipped = 0; + } +} + +static inline int +is_better_time_interpolator(struct time_interpolator *new) +{ + if (!time_interpolator) + return 1; + return new->frequency > 2*time_interpolator->frequency || + (unsigned long)new->drift < (unsigned long)time_interpolator->drift; +} + +void +register_time_interpolator(struct time_interpolator *ti) +{ + unsigned long flags; + + /* Sanity check */ + if (ti->frequency == 0 || ti->mask == 0) + BUG(); + + ti->nsec_per_cyc = ((u64)NSEC_PER_SEC << ti->shift) / ti->frequency; + spin_lock(&time_interpolator_lock); + write_seqlock_irqsave(&xtime_lock, flags); + if (is_better_time_interpolator(ti)) { + time_interpolator = ti; + time_interpolator_reset(); + } + write_sequnlock_irqrestore(&xtime_lock, flags); + + ti->next = time_interpolator_list; + time_interpolator_list = ti; + spin_unlock(&time_interpolator_lock); +} + +void +unregister_time_interpolator(struct time_interpolator *ti) +{ + struct time_interpolator *curr, **prev; + unsigned long flags; + + spin_lock(&time_interpolator_lock); + prev = &time_interpolator_list; + for (curr = *prev; curr; curr = curr->next) { + if (curr == ti) { + *prev = curr->next; + break; + } + prev = &curr->next; + } + + write_seqlock_irqsave(&xtime_lock, flags); + if (ti == time_interpolator) { + /* we lost the best time-interpolator: */ + time_interpolator = NULL; + /* find the next-best interpolator */ + for (curr = time_interpolator_list; curr; curr = curr->next) + if (is_better_time_interpolator(curr)) + time_interpolator = curr; + time_interpolator_reset(); + } + write_sequnlock_irqrestore(&xtime_lock, flags); + spin_unlock(&time_interpolator_lock); +} +#endif /* CONFIG_TIME_INTERPOLATION */ + +/** + * msleep - sleep safely even with waitqueue interruptions + * @msecs: Time in milliseconds to sleep for + */ +void msleep(unsigned int msecs) +{ + unsigned long timeout = msecs_to_jiffies(msecs) + 1; + + while (timeout) { + set_current_state(TASK_UNINTERRUPTIBLE); + timeout = schedule_timeout(timeout); + } +} + +EXPORT_SYMBOL(msleep); + +/** + * msleep_interruptible - sleep waiting for waitqueue interruptions + * @msecs: Time in milliseconds to sleep for + */ +unsigned long msleep_interruptible(unsigned int msecs) +{ + unsigned long timeout = msecs_to_jiffies(msecs) + 1; + + while (timeout && !signal_pending(current)) { + set_current_state(TASK_INTERRUPTIBLE); + timeout = schedule_timeout(timeout); + } + return jiffies_to_msecs(timeout); +} + +EXPORT_SYMBOL(msleep_interruptible); |
