396 lines
10 KiB
C
396 lines
10 KiB
C
/*
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* Virtual cpu timer based timer functions.
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*
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* Copyright IBM Corp. 2004, 2012
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* Author(s): Jan Glauber <jan.glauber@de.ibm.com>
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*/
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#include <linux/kernel_stat.h>
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#include <linux/notifier.h>
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#include <linux/kprobes.h>
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/timex.h>
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#include <linux/types.h>
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#include <linux/time.h>
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#include <linux/cpu.h>
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#include <linux/smp.h>
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#include <asm/irq_regs.h>
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#include <asm/cputime.h>
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#include <asm/vtimer.h>
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#include <asm/irq.h>
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#include "entry.h"
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static void virt_timer_expire(void);
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DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
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static LIST_HEAD(virt_timer_list);
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static DEFINE_SPINLOCK(virt_timer_lock);
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static atomic64_t virt_timer_current;
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static atomic64_t virt_timer_elapsed;
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static inline u64 get_vtimer(void)
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{
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u64 timer;
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asm volatile("stpt %0" : "=m" (timer));
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return timer;
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}
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static inline void set_vtimer(u64 expires)
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{
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u64 timer;
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asm volatile(
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" stpt %0\n" /* Store current cpu timer value */
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" spt %1" /* Set new value imm. afterwards */
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: "=m" (timer) : "m" (expires));
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S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
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S390_lowcore.last_update_timer = expires;
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}
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static inline int virt_timer_forward(u64 elapsed)
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{
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BUG_ON(!irqs_disabled());
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if (list_empty(&virt_timer_list))
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return 0;
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elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
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return elapsed >= atomic64_read(&virt_timer_current);
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}
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/*
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* Update process times based on virtual cpu times stored by entry.S
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* to the lowcore fields user_timer, system_timer & steal_clock.
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*/
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static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
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{
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struct thread_info *ti = task_thread_info(tsk);
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u64 timer, clock, user, system, steal;
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timer = S390_lowcore.last_update_timer;
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clock = S390_lowcore.last_update_clock;
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asm volatile(
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" stpt %0\n" /* Store current cpu timer value */
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" stck %1" /* Store current tod clock value */
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: "=m" (S390_lowcore.last_update_timer),
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"=m" (S390_lowcore.last_update_clock));
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S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
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S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
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user = S390_lowcore.user_timer - ti->user_timer;
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S390_lowcore.steal_timer -= user;
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ti->user_timer = S390_lowcore.user_timer;
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account_user_time(tsk, user, user);
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system = S390_lowcore.system_timer - ti->system_timer;
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S390_lowcore.steal_timer -= system;
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ti->system_timer = S390_lowcore.system_timer;
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account_system_time(tsk, hardirq_offset, system, system);
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steal = S390_lowcore.steal_timer;
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if ((s64) steal > 0) {
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S390_lowcore.steal_timer = 0;
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account_steal_time(steal);
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}
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return virt_timer_forward(user + system);
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}
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void account_vtime(struct task_struct *prev, struct task_struct *next)
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{
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struct thread_info *ti;
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do_account_vtime(prev, 0);
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ti = task_thread_info(prev);
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ti->user_timer = S390_lowcore.user_timer;
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ti->system_timer = S390_lowcore.system_timer;
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ti = task_thread_info(next);
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S390_lowcore.user_timer = ti->user_timer;
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S390_lowcore.system_timer = ti->system_timer;
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}
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void account_process_tick(struct task_struct *tsk, int user_tick)
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{
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if (do_account_vtime(tsk, HARDIRQ_OFFSET))
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virt_timer_expire();
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}
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/*
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* Update process times based on virtual cpu times stored by entry.S
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* to the lowcore fields user_timer, system_timer & steal_clock.
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*/
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void account_system_vtime(struct task_struct *tsk)
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{
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struct thread_info *ti = task_thread_info(tsk);
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u64 timer, system;
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timer = S390_lowcore.last_update_timer;
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S390_lowcore.last_update_timer = get_vtimer();
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S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
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system = S390_lowcore.system_timer - ti->system_timer;
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S390_lowcore.steal_timer -= system;
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ti->system_timer = S390_lowcore.system_timer;
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account_system_time(tsk, 0, system, system);
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virt_timer_forward(system);
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}
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EXPORT_SYMBOL_GPL(account_system_vtime);
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void __kprobes vtime_stop_cpu(void)
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{
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struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
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unsigned long long idle_time;
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unsigned long psw_mask;
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trace_hardirqs_on();
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/* Don't trace preempt off for idle. */
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stop_critical_timings();
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/* Wait for external, I/O or machine check interrupt. */
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psw_mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_DAT |
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PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
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idle->nohz_delay = 0;
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/* Call the assembler magic in entry.S */
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psw_idle(idle, psw_mask);
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/* Reenable preemption tracer. */
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start_critical_timings();
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/* Account time spent with enabled wait psw loaded as idle time. */
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idle->sequence++;
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smp_wmb();
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idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
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idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
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idle->idle_time += idle_time;
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idle->idle_count++;
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account_idle_time(idle_time);
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smp_wmb();
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idle->sequence++;
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}
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cputime64_t s390_get_idle_time(int cpu)
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{
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struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
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unsigned long long now, idle_enter, idle_exit;
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unsigned int sequence;
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do {
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now = get_clock();
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sequence = ACCESS_ONCE(idle->sequence);
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idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
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idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
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} while ((sequence & 1) || (idle->sequence != sequence));
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return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0;
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}
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/*
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* Sorted add to a list. List is linear searched until first bigger
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* element is found.
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*/
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static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
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{
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struct vtimer_list *tmp;
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list_for_each_entry(tmp, head, entry) {
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if (tmp->expires > timer->expires) {
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list_add_tail(&timer->entry, &tmp->entry);
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return;
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}
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}
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list_add_tail(&timer->entry, head);
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}
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/*
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* Handler for expired virtual CPU timer.
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*/
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static void virt_timer_expire(void)
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{
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struct vtimer_list *timer, *tmp;
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unsigned long elapsed;
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LIST_HEAD(cb_list);
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/* walk timer list, fire all expired timers */
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spin_lock(&virt_timer_lock);
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elapsed = atomic64_read(&virt_timer_elapsed);
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list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
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if (timer->expires < elapsed)
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/* move expired timer to the callback queue */
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list_move_tail(&timer->entry, &cb_list);
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else
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timer->expires -= elapsed;
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}
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if (!list_empty(&virt_timer_list)) {
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timer = list_first_entry(&virt_timer_list,
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struct vtimer_list, entry);
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atomic64_set(&virt_timer_current, timer->expires);
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}
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atomic64_sub(elapsed, &virt_timer_elapsed);
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spin_unlock(&virt_timer_lock);
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/* Do callbacks and recharge periodic timers */
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list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
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list_del_init(&timer->entry);
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timer->function(timer->data);
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if (timer->interval) {
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/* Recharge interval timer */
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timer->expires = timer->interval +
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atomic64_read(&virt_timer_elapsed);
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spin_lock(&virt_timer_lock);
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list_add_sorted(timer, &virt_timer_list);
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spin_unlock(&virt_timer_lock);
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}
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}
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}
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void init_virt_timer(struct vtimer_list *timer)
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{
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timer->function = NULL;
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INIT_LIST_HEAD(&timer->entry);
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}
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EXPORT_SYMBOL(init_virt_timer);
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static inline int vtimer_pending(struct vtimer_list *timer)
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{
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return !list_empty(&timer->entry);
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}
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static void internal_add_vtimer(struct vtimer_list *timer)
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{
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if (list_empty(&virt_timer_list)) {
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/* First timer, just program it. */
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atomic64_set(&virt_timer_current, timer->expires);
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atomic64_set(&virt_timer_elapsed, 0);
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list_add(&timer->entry, &virt_timer_list);
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} else {
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/* Update timer against current base. */
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timer->expires += atomic64_read(&virt_timer_elapsed);
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if (likely((s64) timer->expires <
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(s64) atomic64_read(&virt_timer_current)))
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/* The new timer expires before the current timer. */
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atomic64_set(&virt_timer_current, timer->expires);
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/* Insert new timer into the list. */
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list_add_sorted(timer, &virt_timer_list);
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}
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}
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static void __add_vtimer(struct vtimer_list *timer, int periodic)
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{
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unsigned long flags;
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timer->interval = periodic ? timer->expires : 0;
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spin_lock_irqsave(&virt_timer_lock, flags);
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internal_add_vtimer(timer);
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spin_unlock_irqrestore(&virt_timer_lock, flags);
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}
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/*
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* add_virt_timer - add an oneshot virtual CPU timer
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*/
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void add_virt_timer(struct vtimer_list *timer)
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{
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__add_vtimer(timer, 0);
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}
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EXPORT_SYMBOL(add_virt_timer);
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/*
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* add_virt_timer_int - add an interval virtual CPU timer
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*/
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void add_virt_timer_periodic(struct vtimer_list *timer)
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{
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__add_vtimer(timer, 1);
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}
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EXPORT_SYMBOL(add_virt_timer_periodic);
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static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
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{
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unsigned long flags;
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int rc;
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BUG_ON(!timer->function);
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if (timer->expires == expires && vtimer_pending(timer))
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return 1;
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spin_lock_irqsave(&virt_timer_lock, flags);
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rc = vtimer_pending(timer);
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if (rc)
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list_del_init(&timer->entry);
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timer->interval = periodic ? expires : 0;
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timer->expires = expires;
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internal_add_vtimer(timer);
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spin_unlock_irqrestore(&virt_timer_lock, flags);
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return rc;
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}
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/*
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* returns whether it has modified a pending timer (1) or not (0)
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*/
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int mod_virt_timer(struct vtimer_list *timer, u64 expires)
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{
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return __mod_vtimer(timer, expires, 0);
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}
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EXPORT_SYMBOL(mod_virt_timer);
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/*
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* returns whether it has modified a pending timer (1) or not (0)
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*/
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int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
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{
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return __mod_vtimer(timer, expires, 1);
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}
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EXPORT_SYMBOL(mod_virt_timer_periodic);
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/*
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* Delete a virtual timer.
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*
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* returns whether the deleted timer was pending (1) or not (0)
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*/
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int del_virt_timer(struct vtimer_list *timer)
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{
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unsigned long flags;
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if (!vtimer_pending(timer))
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return 0;
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spin_lock_irqsave(&virt_timer_lock, flags);
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list_del_init(&timer->entry);
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spin_unlock_irqrestore(&virt_timer_lock, flags);
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return 1;
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}
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EXPORT_SYMBOL(del_virt_timer);
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/*
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* Start the virtual CPU timer on the current CPU.
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*/
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void __cpuinit init_cpu_vtimer(void)
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{
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/* set initial cpu timer */
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set_vtimer(VTIMER_MAX_SLICE);
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}
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static int __cpuinit s390_nohz_notify(struct notifier_block *self,
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unsigned long action, void *hcpu)
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{
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struct s390_idle_data *idle;
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long cpu = (long) hcpu;
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idle = &per_cpu(s390_idle, cpu);
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switch (action & ~CPU_TASKS_FROZEN) {
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case CPU_DYING:
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idle->nohz_delay = 0;
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default:
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break;
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}
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return NOTIFY_OK;
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}
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void __init vtime_init(void)
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{
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/* Enable cpu timer interrupts on the boot cpu. */
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init_cpu_vtimer();
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cpu_notifier(s390_nohz_notify, 0);
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}
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