path: root/arch/s390/kernel/vtime.c

/*
 *  arch/s390/kernel/vtime.c
 *    Virtual cpu timer based timer functions.
 *
 *  S390 version
 *    Copyright (C) 2004 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Jan Glauber <jan.glauber@de.ibm.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/types.h>
#include <linux/timex.h>
#include <linux/notifier.h>
#include <linux/kernel_stat.h>
#include <linux/rcupdate.h>
#include <linux/posix-timers.h>

#include <asm/s390_ext.h>
#include <asm/timer.h>
#include <asm/irq_regs.h>

static ext_int_info_t ext_int_info_timer;
DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);

#ifdef CONFIG_VIRT_CPU_ACCOUNTING
/*
 * Update process times based on virtual cpu times stored by entry.S
 * to the lowcore fields user_timer, system_timer & steal_clock.
 */
void account_tick_vtime(struct task_struct *tsk)
{
	cputime_t cputime;
	__u64 timer, clock;
	int rcu_user_flag;

	timer = S390_lowcore.last_update_timer;
	clock = S390_lowcore.last_update_clock;
	asm volatile ("  STPT %0\n"    /* Store current cpu timer value */
		      "  STCK %1"      /* Store current tod clock value */
		      : "=m" (S390_lowcore.last_update_timer),
		        "=m" (S390_lowcore.last_update_clock) );
	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
	S390_lowcore.steal_clock += S390_lowcore.last_update_clock - clock;

	cputime = S390_lowcore.user_timer >> 12;
	rcu_user_flag = cputime != 0;
	S390_lowcore.user_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_user_time(tsk, cputime);

	cputime =  S390_lowcore.system_timer >> 12;
	S390_lowcore.system_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_system_time(tsk, HARDIRQ_OFFSET, cputime);

	cputime = S390_lowcore.steal_clock;
	if ((__s64) cputime > 0) {
		cputime >>= 12;
		S390_lowcore.steal_clock -= cputime << 12;
		account_steal_time(tsk, cputime);
	}

	run_local_timers();
	if (rcu_pending(smp_processor_id()))
		rcu_check_callbacks(smp_processor_id(), rcu_user_flag);
	scheduler_tick();
 	run_posix_cpu_timers(tsk);
}

/*
 * Update process times based on virtual cpu times stored by entry.S
 * to the lowcore fields user_timer, system_timer & steal_clock.
 */
void account_vtime(struct task_struct *tsk)
{
	cputime_t cputime;
	__u64 timer;

	timer = S390_lowcore.last_update_timer;
	asm volatile ("  STPT %0"    /* Store current cpu timer value */
		      : "=m" (S390_lowcore.last_update_timer) );
	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;

	cputime = S390_lowcore.user_timer >> 12;
	S390_lowcore.user_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_user_time(tsk, cputime);

	cputime =  S390_lowcore.system_timer >> 12;
	S390_lowcore.system_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_system_time(tsk, 0, cputime);
}

/*
 * Update process times based on virtual cpu times stored by entry.S
 * to the lowcore fields user_timer, system_timer & steal_clock.
 */
void account_system_vtime(struct task_struct *tsk)
{
	cputime_t cputime;
	__u64 timer;

	timer = S390_lowcore.last_update_timer;
	asm volatile ("  STPT %0"    /* Store current cpu timer value */
		      : "=m" (S390_lowcore.last_update_timer) );
	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;

	cputime =  S390_lowcore.system_timer >> 12;
	S390_lowcore.system_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_system_time(tsk, 0, cputime);
}

static inline void set_vtimer(__u64 expires)
{
	__u64 timer;

	asm volatile ("  STPT %0\n"  /* Store current cpu timer value */
		      "  SPT %1"     /* Set new value immediatly afterwards */
		      : "=m" (timer) : "m" (expires) );
	S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
	S390_lowcore.last_update_timer = expires;

	/* store expire time for this CPU timer */
	per_cpu(virt_cpu_timer, smp_processor_id()).to_expire = expires;
}
#else
static inline void set_vtimer(__u64 expires)
{
	S390_lowcore.last_update_timer = expires;
	asm volatile ("SPT %0" : : "m" (S390_lowcore.last_update_timer));

	/* store expire time for this CPU timer */
	per_cpu(virt_cpu_timer, smp_processor_id()).to_expire = expires;
}
#endif

static void start_cpu_timer(void)
{
	struct vtimer_queue *vt_list;

	vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());

	/* CPU timer interrupt is pending, don't reprogramm it */
	if (vt_list->idle & 1LL<<63)
		return;

	if (!list_empty(&vt_list->list))
		set_vtimer(vt_list->idle);
}

static void stop_cpu_timer(void)
{
	struct vtimer_queue *vt_list;

	vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());

	/* nothing to do */
	if (list_empty(&vt_list->list)) {
		vt_list->idle = VTIMER_MAX_SLICE;
		goto fire;
	}

	/* store the actual expire value */
	asm volatile ("STPT %0" : "=m" (vt_list->idle));

	/*
	 * If the CPU timer is negative we don't reprogramm
	 * it because we will get instantly an interrupt.
	 */
	if (vt_list->idle & 1LL<<63)
		return;

	vt_list->offset += vt_list->to_expire - vt_list->idle;

	/*
	 * We cannot halt the CPU timer, we just write a value that
	 * nearly never expires (only after 71 years) and re-write
	 * the stored expire value if we continue the timer
	 */
 fire:
	set_vtimer(VTIMER_MAX_SLICE);
}

/*
 * Sorted add to a list. List is linear searched until first bigger
 * element is found.
 */
static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
{
	struct vtimer_list *event;

	list_for_each_entry(event, head, entry) {
		if (event->expires > timer->expires) {
			list_add_tail(&timer->entry, &event->entry);
			return;
		}
	}
	list_add_tail(&timer->entry, head);
}

/*
 * Do the callback functions of expired vtimer events.
 * Called from within the interrupt handler.
 */
static void do_callbacks(struct list_head *cb_list, struct pt_regs *regs)
{
	struct vtimer_queue *vt_list;
	struct vtimer_list *event, *tmp;
	void (*fn)(unsigned long, struct pt_regs*);
	unsigned long data;

	if (list_empty(cb_list))
		return;

	vt_list = &per_cpu(virt_cpu_timer, smp_processor_id());

	list_for_each_entry_safe(event, tmp, cb_list, entry) {
		fn = event->function;
		data = event->data;
		fn(data, regs);

		if (!event->interval)
			/* delete one shot timer */
			list_del_init(&event->entry);
		else {
			/* move interval timer back to list */
			spin_lock(&vt_list->lock);
			list_del_init(&event->entry);
			list_add_sorted(event, &vt_list->list);