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-rw-r--r--arch/s390/kernel/vtime.c454
1 files changed, 454 insertions, 0 deletions
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
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+++ b/arch/s390/kernel/vtime.c
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+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/sched/cputime.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/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 u64 get_vtimer(void)
+{
+ u64 timer;
+
+ asm volatile("stpt %0" : "=Q" (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 */
+ : "=Q" (timer) : "Q" (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);
+}
+
+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;
+
+ timer = S390_lowcore.last_update_timer;
+ clock = S390_lowcore.last_update_clock;
+ asm volatile(
+ " stpt %0\n" /* Store current cpu timer value */
+ " stckf %1" /* Store current tod clock value */
+ : "=Q" (S390_lowcore.last_update_timer),
+ "=Q" (S390_lowcore.last_update_clock)
+ : : "cc");
+ clock = S390_lowcore.last_update_clock - clock;
+ timer -= S390_lowcore.last_update_timer;
+
+ if (hardirq_count())
+ S390_lowcore.hardirq_timer += timer;
+ else
+ S390_lowcore.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(S390_lowcore.user_timer));
+ guest = update_tsk_timer(&tsk->thread.guest_timer,
+ READ_ONCE(S390_lowcore.guest_timer));
+ system = update_tsk_timer(&tsk->thread.system_timer,
+ READ_ONCE(S390_lowcore.system_timer));
+ hardirq = update_tsk_timer(&tsk->thread.hardirq_timer,
+ READ_ONCE(S390_lowcore.hardirq_timer));
+ softirq = update_tsk_timer(&tsk->thread.softirq_timer,
+ READ_ONCE(S390_lowcore.softirq_timer));
+ S390_lowcore.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)
+{
+ do_account_vtime(prev);
+ prev->thread.user_timer = S390_lowcore.user_timer;
+ prev->thread.guest_timer = S390_lowcore.guest_timer;
+ prev->thread.system_timer = S390_lowcore.system_timer;
+ prev->thread.hardirq_timer = S390_lowcore.hardirq_timer;
+ prev->thread.softirq_timer = S390_lowcore.softirq_timer;
+ S390_lowcore.user_timer = current->thread.user_timer;
+ S390_lowcore.guest_timer = current->thread.guest_timer;
+ S390_lowcore.system_timer = current->thread.system_timer;
+ S390_lowcore.hardirq_timer = current->thread.hardirq_timer;
+ S390_lowcore.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)
+{
+ u64 steal, avg_steal;
+
+ if (do_account_vtime(tsk))
+ virt_timer_expire();
+
+ steal = S390_lowcore.steal_timer;
+ avg_steal = S390_lowcore.avg_steal_timer / 2;
+ if ((s64) steal > 0) {
+ S390_lowcore.steal_timer = 0;
+ account_steal_time(cputime_to_nsecs(steal));
+ avg_steal += steal;
+ }
+ S390_lowcore.avg_steal_timer = avg_steal;
+}
+
+static u64 vtime_delta(void)
+{
+ u64 timer = S390_lowcore.last_update_timer;
+
+ S390_lowcore.last_update_timer = get_vtimer();
+
+ return timer - S390_lowcore.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)
+{
+ u64 delta = vtime_delta();
+
+ if (tsk->flags & PF_VCPU)
+ S390_lowcore.guest_timer += delta;
+ else
+ S390_lowcore.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();
+
+ S390_lowcore.softirq_timer += delta;
+
+ virt_timer_forward(delta);
+}
+
+void vtime_account_hardirq(struct task_struct *tsk)
+{
+ u64 delta = vtime_delta();
+
+ S390_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));
+ }
+}