// SPDX-License-Identifier: GPL-2.0
/*
* Virtual cpu timer based timer functions.
*
* Copyright IBM Corp. 2004, 2012
* Author(s): Jan Glauber <[email protected]>
*/
#include <linux/kernel_stat.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/timex.h>
#include <linux/types.h>
#include <linux/time.h>
#include <asm/alternative.h>
#include <asm/cputime.h>
#include <asm/vtimer.h>
#include <asm/vtime.h>
#include <asm/cpu_mf.h>
#include <asm/smp.h>
#include "entry.h"
static void virt_timer_expire(void);
static LIST_HEAD(virt_timer_list);
static DEFINE_SPINLOCK(virt_timer_lock);
static atomic64_t virt_timer_current;
static atomic64_t virt_timer_elapsed;
DEFINE_PER_CPU(u64, mt_cycles[8]);
static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 };
static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 };
static DEFINE_PER_CPU(u64, mt_scaling_jiffies);
static inline void set_vtimer(u64 expires)
{
struct lowcore *lc = get_lowcore();
u64 timer;
asm volatile(
" stpt %0\n" /* Store current cpu timer value */
" spt %1" /* Set new value imm. afterwards */
: "=Q" (timer) : "Q" (expires));
lc->system_timer += lc->last_update_timer - timer;
lc->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);
}
static void update_mt_scaling(void)
{
u64 cycles_new[8], *cycles_old;
u64 delta, fac, mult, div;
int i;
stcctm(MT_DIAG, smp_cpu_mtid + 1, cycles_new);
cycles_old = this_cpu_ptr(mt_cycles);
fac = 1;
mult = div = 0;
for (i = 0; i <= smp_cpu_mtid; i++) {
delta = cycles_new[i] - cycles_old[i];
div += delta;
mult *= i + 1;
mult += delta * fac;
fac *= i + 1;
}
div *= fac;
if (div > 0) {
/* Update scaling factor */
__this_cpu_write(mt_scaling_mult, mult);
__this_cpu_write(mt_scaling_div, div);
memcpy(cycles_old, cycles_new,
sizeof(u64) * (smp_cpu_mtid + 1));
}
__this_cpu_write(mt_scaling_jiffies, jiffies_64);
}
static inline u64 update_tsk_timer(unsigned long *tsk_vtime, u64 new)
{
u64 delta;
delta = new - *tsk_vtime;
*tsk_vtime = new;
return delta;
}
static inline u64 scale_vtime(u64 vtime)
{
u64 mult = __this_cpu_read(mt_scaling_mult);
u64 div = __this_cpu_read(mt_scaling_div);
if (smp_cpu_mtid)
return vtime * mult / div;
return vtime;
}
static void account_system_index_scaled(struct task_struct *p, u64 cputime,
enum cpu_usage_stat index)
{
p->stimescaled += cputime_to_nsecs(scale_vtime(cputime));
account_system_index_time(p, cputime_to_nsecs(cputime), index);
}
/*
* 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)
{
u64 timer, clock, user, guest, system, hardirq, softirq;
struct lowcore *lc = get_lowcore();
timer = lc->last_update_timer;
clock = lc->last_update_clock;
asm volatile(
" stpt %0\n" /* Store current cpu timer value */
" stckf %1" /* Store current tod clock value */
: "=Q" (lc->last_update_timer),
"=Q" (lc->last_update_clock)
: : "cc");
clock = lc->last_update_clock - clock;
timer -= lc->last_update_timer;
if (hardirq_count())
lc->hardirq_timer += timer;
else
lc->system_timer += timer;
/* Update MT utilization calculation */
if (smp_cpu_mtid &&
time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
update_mt_scaling();
/* Calculate cputime delta */
user = update_tsk_timer(&tsk->thread.user_timer,
READ_ONCE(lc->user_timer));
guest = update_tsk_timer(&tsk->thread.guest_timer,
READ_ONCE(lc->guest_timer));
system = update_tsk_timer(&tsk->thread.system_timer,
READ_ONCE(lc->system_timer));
hardirq = update_tsk_timer(&tsk->thread.hardirq_timer,
READ_ONCE(lc->hardirq_timer));
softirq = update_tsk_timer(&tsk->thread.softirq_timer,
READ_ONCE(lc->softirq_timer));
lc->steal_timer +=
clock - user - guest - system - hardirq - softirq;
/* Push account value */
if (user) {
account_user_time(tsk, cputime_to_nsecs(user));
tsk->utimescaled += cputime_to_nsecs(scale_vtime(user));
}
if (guest) {
account_guest_time(tsk, cputime_to_nsecs(guest));
tsk->utimescaled += cputime_to_nsecs(scale_vtime(guest));
}
if (system)
account_system_index_scaled(tsk, system, CPUTIME_SYSTEM);
if (hardirq)
account_system_index_scaled(tsk, hardirq, CPUTIME_IRQ);
if (softirq)
account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ);
return virt_timer_forward(user + guest + system + hardirq + softirq);
}
void vtime_task_switch(struct task_struct *prev)
{
struct lowcore *lc = get_lowcore();
do_account_vtime(prev);
prev->thread.user_timer = lc->user_timer;
prev->thread.guest_timer = lc->guest_timer;
prev->thread.system_timer = lc->system_timer;
prev->thread.hardirq_timer = lc->hardirq_timer;
prev->thread.softirq_timer = lc->softirq_timer;
lc->user_timer = current->thread.user_timer;
lc->guest_timer = current->thread.guest_timer;
lc->system_timer = current->thread.system_timer;
lc->hardirq_timer = current->thread.hardirq_timer;
lc->softirq_timer = current->thread.softirq_timer;
}
/*
* In s390, accounting pending user time also implies
* accounting system time in order to correctly compute
* the stolen time accounting.
*/
void vtime_flush(struct task_struct *tsk)
{
struct lowcore *lc = get_lowcore();
u64 steal, avg_steal;
if (do_account_vtime(tsk))
virt_timer_expire();
steal = lc->steal_timer;
avg_steal = lc->avg_steal_timer;
if ((s64) steal > 0) {
lc->steal_timer = 0;
account_steal_time(cputime_to_nsecs(steal));
avg_steal += steal;
}
lc->avg_steal_timer = avg_steal / 2;
}
static u64 vtime_delta(void)
{
struct lowcore *lc = get_lowcore();
u64 timer = lc->last_update_timer;
lc->last_update_timer = get_cpu_timer();
return timer - lc->last_update_timer;
}
/*
* 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_kernel(struct task_struct *tsk)
{
struct lowcore *lc = get_lowcore();
u64 delta = vtime_delta();
if (tsk->flags & PF_VCPU)
lc->guest_timer += delta;
else
lc->system_timer += delta;
virt_timer_forward(delta);
}
EXPORT_SYMBOL_GPL(vtime_account_kernel);
void vtime_account_softirq(struct task_struct *tsk)
{
u64 delta = vtime_delta();
get_lowcore()->softirq_timer += delta;
virt_timer_forward(delta);
}
void vtime_account_hardirq(struct task_struct *tsk)
{
u64 delta = vtime_delta();
get_lowcore()->hardirq_timer += delta;
virt_timer_forward(delta);
}
/*
* 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 a 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 vtime_init(void)
{
/* set initial cpu timer */
set_vtimer(VTIMER_MAX_SLICE);
/* Setup initial MT scaling values */
if (smp_cpu_mtid) {
__this_cpu_write(mt_scaling_jiffies, jiffies);
__this_cpu_write(mt_scaling_mult, 1);
__this_cpu_write(mt_scaling_div, 1);
stcctm(MT_DIAG, smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles));
}
}
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