- 根目录:
- arch
- s390
- kernel
- vtime.c
/*
* Virtual cpu timer based timer functions.
*
* Copyright IBM Corp. 2004, 2012
* Author(s): Jan Glauber <jan.glauber@de.ibm.com>
*/
#include <linux/kernel_stat.h>
#include <linux/notifier.h>
#include <linux/kprobes.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/timex.h>
#include <linux/types.h>
#include <linux/time.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <asm/irq_regs.h>
#include <asm/cputime.h>
#include <asm/vtimer.h>
#include <asm/irq.h>
#include "entry.h"
static void virt_timer_expire(void);
DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
static LIST_HEAD(virt_timer_list);
static DEFINE_SPINLOCK(virt_timer_lock);
static atomic64_t virt_timer_current;
static atomic64_t virt_timer_elapsed;
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 imm. afterwards */
: "=m" (timer) : "m" (expires));
S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
S390_lowcore.last_update_timer = expires;
}
static inline int virt_timer_forward(u64 elapsed)
{
BUG_ON(!irqs_disabled());
if (list_empty(&virt_timer_list))
return 0;
elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
return elapsed >= atomic64_read(&virt_timer_current);
}
/*
* Update process times based on virtual cpu times stored by entry.S
* to the lowcore fields user_timer, system_timer & steal_clock.
*/
static int 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);
}
return virt_timer_forward(user + system);
}
void vtime_task_switch(struct task_struct *prev)
{
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(current);
S390_lowcore.user_timer = ti->user_timer;
S390_lowcore.system_timer = ti->system_timer;
}
/*
* In s390, accounting pending user time also implies
* accounting system time in order to correctly compute
* the stolen time accounting.
*/
void vtime_account_user(struct task_struct *tsk)
{
if (do_account_vtime(tsk, HARDIRQ_OFFSET))
virt_timer_expire();
}
/*
* Update process times based on virtual cpu times stored by entry.S
* to the lowcore fields user_timer, system_timer & steal_clock.
*/
void vtime_account_irq_enter(struct task_struct *tsk)
{
struct thread_info *ti = task_thread_info(tsk);
u64 timer, system;
WARN_ON_ONCE(!irqs_disabled());
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);
virt_timer_forward(system);
}
EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
void vtime_account_system(struct task_struct *tsk)
__attribute__((alias("vtime_account_irq_enter")));
EXPORT_SYMBOL_GPL(vtime_account_system);
void __kprobes vtime_stop_cpu(void)
{
struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
unsigned long long idle_time;
unsigned long psw_mask;
trace_hardirqs_on();
/* Wait for external, I/O or machine check interrupt. */
psw_mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_DAT |
PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
idle->nohz_delay = 0;
/* Call the assembler magic in entry.S */
psw_idle(idle, psw_mask);
/* Account time spent with enabled wait psw loaded as idle time. */
idle->sequence++;
smp_wmb();
idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
idle->idle_time += idle_time;
idle->idle_count++;
account_idle_time(idle_time);
smp_wmb();
idle->sequence++;
}
cputime64_t s390_get_idle_time(int cpu)
{
struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
unsigned long long now, idle_enter, idle_exit;
unsigned int sequence;
do {
now = get_tod_clock();
sequence = ACCESS_ONCE(idle->sequence);
idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
} while ((sequence & 1) || (idle->sequence != sequence));
return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0;
}
/*
* 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 *tmp;
list_for_each_entry(tmp, head, entry) {
if (tmp->expires > timer->expires) {
list_add_tail(&timer->entry, &tmp->entry);
return;
}
}
list_add_tail(&timer->entry, head);
}
/*
* Handler for expired virtual CPU timer.
*/
static void virt_timer_expire(void)
{
struct vtimer_list *timer, *tmp;
unsigned long elapsed;
LIST_HEAD(cb_list);
/* walk timer list, fire all expired timers */
spin_lock(&virt_timer_lock);
elapsed = atomic64_read(&virt_timer_elapsed);
list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
if (timer->expires < elapsed)
/* move expired timer to the callback queue */
list_move_tail(&timer->entry, &cb_list);
else
timer->expires -= elapsed;
}
if (!list_empty(&virt_timer_list)) {
timer = list_first_entry(&virt_timer_list,
struct vtimer_list, entry);
atomic64_set(&virt_timer_current, timer->expires);
}
atomic64_sub(elapsed, &virt_timer_elapsed);
spin_unlock(&virt_timer_lock);
/* Do callbacks and recharge periodic timers */
list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
list_del_init(&timer->entry);
timer->function(timer->data);
if (timer->interval) {
/* Recharge interval timer */
timer->expires = timer->interval +
atomic64_read(&virt_timer_elapsed);
spin_lock(&virt_timer_lock);
list_add_sorted(timer, &virt_timer_list);
spin_unlock(&virt_timer_lock);
}
}
}
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);
}
static void internal_add_vtimer(struct vtimer_list *timer)
{
if (list_empty(&virt_timer_list)) {
/* First timer, just program it. */
atomic64_set(&virt_timer_current, timer->expires);
atomic64_set(&virt_timer_elapsed, 0);
list_add(&timer->entry, &virt_timer_list);
} else {
/* Update timer against current base. */
timer->expires += atomic64_read(&virt_timer_elapsed);
if (likely((s64) timer->expires <
(s64) atomic64_read(&virt_timer_current)))
/* The new timer expires before the current timer. */
atomic64_set(&virt_timer_current, timer->expires);
/* Insert new timer into the list. */
list_add_sorted(timer, &virt_timer_list);
}
}
static void __add_vtimer(struct vtimer_list *timer, int periodic)
{
unsigned long flags;
timer->interval = periodic ? timer->expires : 0;
spin_lock_irqsave(&virt_timer_lock, flags);
internal_add_vtimer(timer);
spin_unlock_irqrestore(&virt_timer_lock, flags);
}
/*
* add_virt_timer - add an oneshot virtual CPU timer
*/
void add_virt_timer(struct vtimer_list *timer)
{
__add_vtimer(timer, 0);
}
EXPORT_SYMBOL(add_virt_timer);
/*
* add_virt_timer_int - add an interval virtual CPU timer
*/
void add_virt_timer_periodic(struct vtimer_list *timer)
{
__add_vtimer(timer, 1);
}
EXPORT_SYMBOL(add_virt_timer_periodic);
static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
{
unsigned long flags;
int rc;
BUG_ON(!timer->function);
if (timer->expires == expires && vtimer_pending(timer))
return 1;
spin_lock_irqsave(&virt_timer_lock, flags);
rc = vtimer_pending(timer);
if (rc)
list_del_init(&timer->entry);
timer->interval = periodic ? expires : 0;
timer->expires = expires;
internal_add_vtimer(timer);
spin_unlock_irqrestore(&virt_timer_lock, flags);
return rc;
}
/*
* 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);
/*
* 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;
if (!vtimer_pending(timer))
return 0;
spin_lock_irqsave(&virt_timer_lock, flags);
list_del_init(&timer->entry);
spin_unlock_irqrestore(&virt_timer_lock, flags);
return 1;
}
EXPORT_SYMBOL(del_virt_timer);
/*
* Start the virtual CPU timer on the current CPU.
*/
void __cpuinit init_cpu_vtimer(void)
{
/* set initial cpu timer */
set_vtimer(VTIMER_MAX_SLICE);
}
static int __cpuinit s390_nohz_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
struct s390_idle_data *idle;
long cpu = (long) hcpu;
idle = &per_cpu(s390_idle, cpu);
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DYING:
idle->nohz_delay = 0;
default:
break;
}
return NOTIFY_OK;
}
void __init vtime_init(void)
{
/* Enable cpu timer interrupts on the boot cpu. */
init_cpu_vtimer();
cpu_notifier(s390_nohz_notify, 0);
}