linux/arch/s390/kernel/vtime.c

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/*
* 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>
#include <asm/cputime.h>
static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);
DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
static inline __u64 get_vtimer(void)
{
__u64 timer;
asm volatile("STPT %0" : "=m" (timer));
return timer;
}
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;
}
/*
* Update process times based on virtual cpu times stored by entry.S
* to the lowcore fields user_timer, system_timer & steal_clock.
*/
static void do_account_vtime(struct task_struct *tsk, int hardirq_offset)
{
struct thread_info *ti = task_thread_info(tsk);
__u64 timer, clock, user, system, steal;
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_timer += S390_lowcore.last_update_clock - clock;
user = S390_lowcore.user_timer - ti->user_timer;
S390_lowcore.steal_timer -= user;
ti->user_timer = S390_lowcore.user_timer;
account_user_time(tsk, user, user);
system = S390_lowcore.system_timer - ti->system_timer;
S390_lowcore.steal_timer -= system;
ti->system_timer = S390_lowcore.system_timer;
account_system_time(tsk, hardirq_offset, system, system);
steal = S390_lowcore.steal_timer;
if ((s64) steal > 0) {
S390_lowcore.steal_timer = 0;
account_steal_time(steal);
}
}
void account_vtime(struct task_struct *prev, struct task_struct *next)
{
struct thread_info *ti;
do_account_vtime(prev, 0);
ti = task_thread_info(prev);
ti->user_timer = S390_lowcore.user_timer;
ti->system_timer = S390_lowcore.system_timer;
ti = task_thread_info(next);
S390_lowcore.user_timer = ti->user_timer;
S390_lowcore.system_timer = ti->system_timer;
}
void account_process_tick(struct task_struct *tsk, int user_tick)
{
do_account_vtime(tsk, HARDIRQ_OFFSET);
}
/*
* 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)
{
struct thread_info *ti = task_thread_info(tsk);
__u64 timer, system;
timer = S390_lowcore.last_update_timer;
S390_lowcore.last_update_timer = get_vtimer();
S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
system = S390_lowcore.system_timer - ti->system_timer;
S390_lowcore.steal_timer -= system;
ti->system_timer = S390_lowcore.system_timer;
account_system_time(tsk, 0, system, system);
}
EXPORT_SYMBOL_GPL(account_system_vtime);
void vtime_start_cpu(void)
{
struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer);
__u64 idle_time, expires;
/* Account time spent with enabled wait psw loaded as idle time. */
idle_time = S390_lowcore.int_clock - idle->idle_enter;
account_idle_time(idle_time);
S390_lowcore.steal_timer +=
idle->idle_enter - S390_lowcore.last_update_clock;
S390_lowcore.last_update_clock = S390_lowcore.int_clock;
/* Account system time spent going idle. */
S390_lowcore.system_timer += S390_lowcore.last_update_timer - vq->idle;
S390_lowcore.last_update_timer = S390_lowcore.async_enter_timer;
/* Restart vtime CPU timer */
if (vq->do_spt) {
/* Program old expire value but first save progress. */
expires = vq->idle - S390_lowcore.async_enter_timer;
expires += get_vtimer();
set_vtimer(expires);
} else {
/* Don't account the CPU timer delta while the cpu was idle. */
vq->elapsed -= vq->idle - S390_lowcore.async_enter_timer;
}
idle->sequence++;
smp_wmb();
idle->idle_time += idle_time;
idle->idle_enter = 0ULL;
idle->idle_count++;
smp_wmb();
idle->sequence++;
}
void vtime_stop_cpu(void)
{
struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer);
psw_t psw;
/* Wait for external, I/O or machine check interrupt. */
psw.mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_IO | PSW_MASK_EXT;
/* Check if the CPU timer needs to be reprogrammed. */
if (vq->do_spt) {
__u64 vmax = VTIMER_MAX_SLICE;
/*
* The inline assembly is equivalent to
* vq->idle = get_cpu_timer();
* set_cpu_timer(VTIMER_MAX_SLICE);
* idle->idle_enter = get_clock();
* __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
* PSW_MASK_IO | PSW_MASK_EXT);
* The difference is that the inline assembly makes sure that
* the last three instruction are stpt, stck and lpsw in that
* order. This is done to increase the precision.
*/
asm volatile(
#ifndef CONFIG_64BIT
" basr 1,0\n"
"0: ahi 1,1f-0b\n"
" st 1,4(%2)\n"
#else /* CONFIG_64BIT */
" larl 1,1f\n"
" stg 1,8(%2)\n"
#endif /* CONFIG_64BIT */
" stpt 0(%4)\n"
" spt 0(%5)\n"
" stck 0(%3)\n"
#ifndef CONFIG_64BIT
" lpsw 0(%2)\n"
#else /* CONFIG_64BIT */
" lpswe 0(%2)\n"
#endif /* CONFIG_64BIT */
"1:"
: "=m" (idle->idle_enter), "=m" (vq->idle)
: "a" (&psw), "a" (&idle->idle_enter),
"a" (&vq->idle), "a" (&vmax), "m" (vmax), "m" (psw)
: "memory", "cc", "1");
} else {
/*
* The inline assembly is equivalent to
* vq->idle = get_cpu_timer();
* idle->idle_enter = get_clock();
* __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
* PSW_MASK_IO | PSW_MASK_EXT);
* The difference is that the inline assembly makes sure that
* the last three instruction are stpt, stck and lpsw in that
* order. This is done to increase the precision.
*/
asm volatile(
#ifndef CONFIG_64BIT
" basr 1,0\n"
"0: ahi 1,1f-0b\n"
" st 1,4(%2)\n"
#else /* CONFIG_64BIT */
" larl 1,1f\n"
" stg 1,8(%2)\n"
#endif /* CONFIG_64BIT */
" stpt 0(%4)\n"
" stck 0(%3)\n"
#ifndef CONFIG_64BIT
" lpsw 0(%2)\n"
#else /* CONFIG_64BIT */
" lpswe 0(%2)\n"
#endif /* CONFIG_64BIT */
"1:"
: "=m" (idle->idle_enter), "=m" (vq->idle)
: "a" (&psw), "a" (&idle->idle_enter),
"a" (&vq->idle), "m" (psw)
: "memory", "cc", "1");
}
}
cputime64_t s390_get_idle_time(int cpu)
{
struct s390_idle_data *idle;
unsigned long long now, idle_time, idle_enter;
unsigned int sequence;
idle = &per_cpu(s390_idle, cpu);
now = get_clock();
repeat:
sequence = idle->sequence;
smp_rmb();
if (sequence & 1)
goto repeat;
idle_time = 0;
idle_enter = idle->idle_enter;
if (idle_enter != 0ULL && idle_enter < now)
idle_time = now - idle_enter;
smp_rmb();
if (idle->sequence != sequence)
goto repeat;
return idle_time;
}
/*
* 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 vtimer_queue *vq;
struct vtimer_list *event, *tmp;
if (list_empty(cb_list))
return;
vq = &__get_cpu_var(virt_cpu_timer);
list_for_each_entry_safe(event, tmp, cb_list, entry) {
list_del_init(&event->entry);
(event->function)(event->data);
if (event->interval) {
/* Recharge interval timer */
event->expires = event->interval + vq->elapsed;
spin_lock(&vq->lock);
list_add_sorted(event, &vq->list);
spin_unlock(&vq->lock);
}
}
}
/*
* Handler for the virtual CPU timer.
*/
static void do_cpu_timer_interrupt(__u16 error_code)
{
struct vtimer_queue *vq;
struct vtimer_list *event, *tmp;
struct list_head cb_list; /* the callback queue */
__u64 elapsed, next;
INIT_LIST_HEAD(&cb_list);
vq = &__get_cpu_var(virt_cpu_timer);
/* walk timer list, fire all expired events */
spin_lock(&vq->lock);
elapsed = vq->elapsed + (vq->timer - S390_lowcore.async_enter_timer);
BUG_ON((s64) elapsed < 0);
vq->elapsed = 0;
list_for_each_entry_safe(event, tmp, &vq->list, entry) {
if (event->expires < elapsed)
/* move expired timer to the callback queue */
list_move_tail(&event->entry, &cb_list);
else
event->expires -= elapsed;
}
spin_unlock(&vq->lock);
vq->do_spt = list_empty(&cb_list);
do_callbacks(&cb_list);
/* next event is first in list */
next = VTIMER_MAX_SLICE;
spin_lock(&vq->lock);
if (!list_empty(&vq->list)) {
event = list_first_entry(&vq->list, struct vtimer_list, entry);
next = event->expires;
} else
vq->do_spt = 0;
spin_unlock(&vq->lock);
/*
* To improve precision add the time spent by the
* interrupt handler to the elapsed time.
* Note: CPU timer counts down and we got an interrupt,
* the current content is negative
*/
elapsed = S390_lowcore.async_enter_timer - get_vtimer();
set_vtimer(next - elapsed);
vq->timer = next - elapsed;
vq->elapsed = elapsed;
}
void init_virt_timer(struct vtimer_list *timer)
{
timer->function = NULL;
INIT_LIST_HEAD(&timer->entry);
}
EXPORT_SYMBOL(init_virt_timer);
static inline int vtimer_pending(struct vtimer_list *timer)
{
return (!list_empty(&timer->entry));
}
/*
* this function should only run on the specified CPU
*/
static void internal_add_vtimer(struct vtimer_list *timer)
{
struct vtimer_queue *vq;
unsigned long flags;
__u64 left, expires;
vq = &per_cpu(virt_cpu_timer, timer->cpu);
spin_lock_irqsave(&vq->lock, flags);
BUG_ON(timer->cpu != smp_processor_id());
if (list_empty(&vq->list)) {
/* First timer on this cpu, just program it. */
list_add(&timer->entry, &vq->list);
set_vtimer(timer->expires);
vq->timer = timer->expires;
vq->elapsed = 0;
} else {
/* Check progress of old timers. */
expires = timer->expires;
left = get_vtimer();
if (likely((s64) expires < (s64) left)) {
/* The new timer expires before the current timer. */
set_vtimer(expires);
vq->elapsed += vq->timer - left;
vq->timer = expires;
} else {
vq->elapsed += vq->timer - left;
vq->timer = left;
}
/* Insert new timer into per cpu list. */
timer->expires += vq->elapsed;
list_add_sorted(timer, &vq->list);
}
spin_unlock_irqrestore(&vq->lock, flags);
/* release CPU acquired in prepare_vtimer or mod_virt_timer() */
put_cpu();
}
static inline void prepare_vtimer(struct vtimer_list *timer)
{
BUG_ON(!timer->function);
BUG_ON(!timer->expires || timer->expires > VTIMER_MAX_SLICE);
BUG_ON(vtimer_pending(timer));
timer->cpu = get_cpu();
}
/*
* add_virt_timer - add an oneshot virtual CPU timer
*/
void add_virt_timer(void *new)
{
struct vtimer_list *timer;
timer = (struct vtimer_list *)new;
prepare_vtimer(timer);
timer->interval = 0;
internal_add_vtimer(timer);
}
EXPORT_SYMBOL(add_virt_timer);
/*
* add_virt_timer_int - add an interval virtual CPU timer
*/
void add_virt_timer_periodic(void *new)
{
struct vtimer_list *timer;
timer = (struct vtimer_list *)new;
prepare_vtimer(timer);
timer->interval = timer->expires;
internal_add_vtimer(timer);
}
EXPORT_SYMBOL(add_virt_timer_periodic);
int __mod_vtimer(struct vtimer_list *timer, __u64 expires, int periodic)
{
struct vtimer_queue *vq;
unsigned long flags;
int cpu;
BUG_ON(!timer->function);
BUG_ON(!expires || expires > VTIMER_MAX_SLICE);
if (timer->expires == expires && vtimer_pending(timer))
return 1;
cpu = get_cpu();
vq = &per_cpu(virt_cpu_timer, cpu);
/* disable interrupts before test if timer is pending */
spin_lock_irqsave(&vq->lock, flags);
/* if timer isn't pending add it on the current CPU */
if (!vtimer_pending(timer)) {
spin_unlock_irqrestore(&vq->lock, flags);
if (periodic)
timer->interval = expires;
else
timer->interval = 0;
timer->expires = expires;
timer->cpu = cpu;
internal_add_vtimer(timer);
return 0;
}
/* check if we run on the right CPU */
BUG_ON(timer->cpu != cpu);
list_del_init(&timer->entry);
timer->expires = expires;
if (periodic)
timer->interval = expires;
/* the timer can't expire anymore so we can release the lock */
spin_unlock_irqrestore(&vq->lock, flags);
internal_add_vtimer(timer);
return 1;
}
/*
* If we change a pending timer the function must be called on the CPU
* where the timer is running on.
*
* returns whether it has modified a pending timer (1) or not (0)
*/
int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
{
return __mod_vtimer(timer, expires, 0);
}
EXPORT_SYMBOL(mod_virt_timer);
/*
* If we change a pending timer the function must be called on the CPU
* where the timer is running on.
*
* returns whether it has modified a pending timer (1) or not (0)
*/
int mod_virt_timer_periodic(struct vtimer_list *timer, __u64 expires)
{
return __mod_vtimer(timer, expires, 1);
}
EXPORT_SYMBOL(mod_virt_timer_periodic);
/*
* delete a virtual timer
*
* returns whether the deleted timer was pending (1) or not (0)
*/
int del_virt_timer(struct vtimer_list *timer)
{
unsigned long flags;
struct vtimer_queue *vq;
/* check if timer is pending */
if (!vtimer_pending(timer))
return 0;
vq = &per_cpu(virt_cpu_timer, timer->cpu);
spin_lock_irqsave(&vq->lock, flags);
/* we don't interrupt a running timer, just let it expire! */
list_del_init(&timer->entry);
spin_unlock_irqrestore(&vq->lock, flags);
return 1;
}
EXPORT_SYMBOL(del_virt_timer);
/*
* Start the virtual CPU timer on the current CPU.
*/
void init_cpu_vtimer(void)
{
struct vtimer_queue *vq;
/* initialize per cpu vtimer structure */
vq = &__get_cpu_var(virt_cpu_timer);
INIT_LIST_HEAD(&vq->list);
spin_lock_init(&vq->lock);
/* enable cpu timer interrupts */
__ctl_set_bit(0,10);
}
void __init vtime_init(void)
{
/* request the cpu timer external interrupt */
if (register_external_interrupt(0x1005, do_cpu_timer_interrupt))
panic("Couldn't request external interrupt 0x1005");
/* Enable cpu timer interrupts on the boot cpu. */
init_cpu_vtimer();
}