v4.19.13 snapshot.
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
new file mode 100644
index 0000000..0796f93
--- /dev/null
+++ b/kernel/sched/cputime.c
@@ -0,0 +1,895 @@
+/*
+ * Simple CPU accounting cgroup controller
+ */
+#include "sched.h"
+
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+
+/*
+ * There are no locks covering percpu hardirq/softirq time.
+ * They are only modified in vtime_account, on corresponding CPU
+ * with interrupts disabled. So, writes are safe.
+ * They are read and saved off onto struct rq in update_rq_clock().
+ * This may result in other CPU reading this CPU's irq time and can
+ * race with irq/vtime_account on this CPU. We would either get old
+ * or new value with a side effect of accounting a slice of irq time to wrong
+ * task when irq is in progress while we read rq->clock. That is a worthy
+ * compromise in place of having locks on each irq in account_system_time.
+ */
+DEFINE_PER_CPU(struct irqtime, cpu_irqtime);
+
+static int sched_clock_irqtime;
+
+void enable_sched_clock_irqtime(void)
+{
+ sched_clock_irqtime = 1;
+}
+
+void disable_sched_clock_irqtime(void)
+{
+ sched_clock_irqtime = 0;
+}
+
+static void irqtime_account_delta(struct irqtime *irqtime, u64 delta,
+ enum cpu_usage_stat idx)
+{
+ u64 *cpustat = kcpustat_this_cpu->cpustat;
+
+ u64_stats_update_begin(&irqtime->sync);
+ cpustat[idx] += delta;
+ irqtime->total += delta;
+ irqtime->tick_delta += delta;
+ u64_stats_update_end(&irqtime->sync);
+}
+
+/*
+ * Called before incrementing preempt_count on {soft,}irq_enter
+ * and before decrementing preempt_count on {soft,}irq_exit.
+ */
+void irqtime_account_irq(struct task_struct *curr)
+{
+ struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
+ s64 delta;
+ int cpu;
+
+ if (!sched_clock_irqtime)
+ return;
+
+ cpu = smp_processor_id();
+ delta = sched_clock_cpu(cpu) - irqtime->irq_start_time;
+ irqtime->irq_start_time += delta;
+
+ /*
+ * We do not account for softirq time from ksoftirqd here.
+ * We want to continue accounting softirq time to ksoftirqd thread
+ * in that case, so as not to confuse scheduler with a special task
+ * that do not consume any time, but still wants to run.
+ */
+ if (hardirq_count())
+ irqtime_account_delta(irqtime, delta, CPUTIME_IRQ);
+ else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
+ irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ);
+}
+EXPORT_SYMBOL_GPL(irqtime_account_irq);
+
+static u64 irqtime_tick_accounted(u64 maxtime)
+{
+ struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
+ u64 delta;
+
+ delta = min(irqtime->tick_delta, maxtime);
+ irqtime->tick_delta -= delta;
+
+ return delta;
+}
+
+#else /* CONFIG_IRQ_TIME_ACCOUNTING */
+
+#define sched_clock_irqtime (0)
+
+static u64 irqtime_tick_accounted(u64 dummy)
+{
+ return 0;
+}
+
+#endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
+
+static inline void task_group_account_field(struct task_struct *p, int index,
+ u64 tmp)
+{
+ /*
+ * Since all updates are sure to touch the root cgroup, we
+ * get ourselves ahead and touch it first. If the root cgroup
+ * is the only cgroup, then nothing else should be necessary.
+ *
+ */
+ __this_cpu_add(kernel_cpustat.cpustat[index], tmp);
+
+ cgroup_account_cputime_field(p, index, tmp);
+}
+
+/*
+ * Account user CPU time to a process.
+ * @p: the process that the CPU time gets accounted to
+ * @cputime: the CPU time spent in user space since the last update
+ */
+void account_user_time(struct task_struct *p, u64 cputime)
+{
+ int index;
+
+ /* Add user time to process. */
+ p->utime += cputime;
+ account_group_user_time(p, cputime);
+
+ index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
+
+ /* Add user time to cpustat. */
+ task_group_account_field(p, index, cputime);
+
+ /* Account for user time used */
+ acct_account_cputime(p);
+}
+
+/*
+ * Account guest CPU time to a process.
+ * @p: the process that the CPU time gets accounted to
+ * @cputime: the CPU time spent in virtual machine since the last update
+ */
+void account_guest_time(struct task_struct *p, u64 cputime)
+{
+ u64 *cpustat = kcpustat_this_cpu->cpustat;
+
+ /* Add guest time to process. */
+ p->utime += cputime;
+ account_group_user_time(p, cputime);
+ p->gtime += cputime;
+
+ /* Add guest time to cpustat. */
+ if (task_nice(p) > 0) {
+ cpustat[CPUTIME_NICE] += cputime;
+ cpustat[CPUTIME_GUEST_NICE] += cputime;
+ } else {
+ cpustat[CPUTIME_USER] += cputime;
+ cpustat[CPUTIME_GUEST] += cputime;
+ }
+}
+
+/*
+ * Account system CPU time to a process and desired cpustat field
+ * @p: the process that the CPU time gets accounted to
+ * @cputime: the CPU time spent in kernel space since the last update
+ * @index: pointer to cpustat field that has to be updated
+ */
+void account_system_index_time(struct task_struct *p,
+ u64 cputime, enum cpu_usage_stat index)
+{
+ /* Add system time to process. */
+ p->stime += cputime;
+ account_group_system_time(p, cputime);
+
+ /* Add system time to cpustat. */
+ task_group_account_field(p, index, cputime);
+
+ /* Account for system time used */
+ acct_account_cputime(p);
+}
+
+/*
+ * Account system CPU time to a process.
+ * @p: the process that the CPU time gets accounted to
+ * @hardirq_offset: the offset to subtract from hardirq_count()
+ * @cputime: the CPU time spent in kernel space since the last update
+ */
+void account_system_time(struct task_struct *p, int hardirq_offset, u64 cputime)
+{
+ int index;
+
+ if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
+ account_guest_time(p, cputime);
+ return;
+ }
+
+ if (hardirq_count() - hardirq_offset)
+ index = CPUTIME_IRQ;
+ else if (in_serving_softirq())
+ index = CPUTIME_SOFTIRQ;
+ else
+ index = CPUTIME_SYSTEM;
+
+ account_system_index_time(p, cputime, index);
+}
+
+/*
+ * Account for involuntary wait time.
+ * @cputime: the CPU time spent in involuntary wait
+ */
+void account_steal_time(u64 cputime)
+{
+ u64 *cpustat = kcpustat_this_cpu->cpustat;
+
+ cpustat[CPUTIME_STEAL] += cputime;
+}
+
+/*
+ * Account for idle time.
+ * @cputime: the CPU time spent in idle wait
+ */
+void account_idle_time(u64 cputime)
+{
+ u64 *cpustat = kcpustat_this_cpu->cpustat;
+ struct rq *rq = this_rq();
+
+ if (atomic_read(&rq->nr_iowait) > 0)
+ cpustat[CPUTIME_IOWAIT] += cputime;
+ else
+ cpustat[CPUTIME_IDLE] += cputime;
+}
+
+/*
+ * When a guest is interrupted for a longer amount of time, missed clock
+ * ticks are not redelivered later. Due to that, this function may on
+ * occasion account more time than the calling functions think elapsed.
+ */
+static __always_inline u64 steal_account_process_time(u64 maxtime)
+{
+#ifdef CONFIG_PARAVIRT
+ if (static_key_false(¶virt_steal_enabled)) {
+ u64 steal;
+
+ steal = paravirt_steal_clock(smp_processor_id());
+ steal -= this_rq()->prev_steal_time;
+ steal = min(steal, maxtime);
+ account_steal_time(steal);
+ this_rq()->prev_steal_time += steal;
+
+ return steal;
+ }
+#endif
+ return 0;
+}
+
+/*
+ * Account how much elapsed time was spent in steal, irq, or softirq time.
+ */
+static inline u64 account_other_time(u64 max)
+{
+ u64 accounted;
+
+ lockdep_assert_irqs_disabled();
+
+ accounted = steal_account_process_time(max);
+
+ if (accounted < max)
+ accounted += irqtime_tick_accounted(max - accounted);
+
+ return accounted;
+}
+
+#ifdef CONFIG_64BIT
+static inline u64 read_sum_exec_runtime(struct task_struct *t)
+{
+ return t->se.sum_exec_runtime;
+}
+#else
+static u64 read_sum_exec_runtime(struct task_struct *t)
+{
+ u64 ns;
+ struct rq_flags rf;
+ struct rq *rq;
+
+ rq = task_rq_lock(t, &rf);
+ ns = t->se.sum_exec_runtime;
+ task_rq_unlock(rq, t, &rf);
+
+ return ns;
+}
+#endif
+
+/*
+ * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
+ * tasks (sum on group iteration) belonging to @tsk's group.
+ */
+void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
+{
+ struct signal_struct *sig = tsk->signal;
+ u64 utime, stime;
+ struct task_struct *t;
+ unsigned int seq, nextseq;
+ unsigned long flags;
+
+ /*
+ * Update current task runtime to account pending time since last
+ * scheduler action or thread_group_cputime() call. This thread group
+ * might have other running tasks on different CPUs, but updating
+ * their runtime can affect syscall performance, so we skip account
+ * those pending times and rely only on values updated on tick or
+ * other scheduler action.
+ */
+ if (same_thread_group(current, tsk))
+ (void) task_sched_runtime(current);
+
+ rcu_read_lock();
+ /* Attempt a lockless read on the first round. */
+ nextseq = 0;
+ do {
+ seq = nextseq;
+ flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
+ times->utime = sig->utime;
+ times->stime = sig->stime;
+ times->sum_exec_runtime = sig->sum_sched_runtime;
+
+ for_each_thread(tsk, t) {
+ task_cputime(t, &utime, &stime);
+ times->utime += utime;
+ times->stime += stime;
+ times->sum_exec_runtime += read_sum_exec_runtime(t);
+ }
+ /* If lockless access failed, take the lock. */
+ nextseq = 1;
+ } while (need_seqretry(&sig->stats_lock, seq));
+ done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
+ rcu_read_unlock();
+}
+
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+/*
+ * Account a tick to a process and cpustat
+ * @p: the process that the CPU time gets accounted to
+ * @user_tick: is the tick from userspace
+ * @rq: the pointer to rq
+ *
+ * Tick demultiplexing follows the order
+ * - pending hardirq update
+ * - pending softirq update
+ * - user_time
+ * - idle_time
+ * - system time
+ * - check for guest_time
+ * - else account as system_time
+ *
+ * Check for hardirq is done both for system and user time as there is
+ * no timer going off while we are on hardirq and hence we may never get an
+ * opportunity to update it solely in system time.
+ * p->stime and friends are only updated on system time and not on irq
+ * softirq as those do not count in task exec_runtime any more.
+ */
+static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
+ struct rq *rq, int ticks)
+{
+ u64 other, cputime = TICK_NSEC * ticks;
+
+ /*
+ * When returning from idle, many ticks can get accounted at
+ * once, including some ticks of steal, irq, and softirq time.
+ * Subtract those ticks from the amount of time accounted to
+ * idle, or potentially user or system time. Due to rounding,
+ * other time can exceed ticks occasionally.
+ */
+ other = account_other_time(ULONG_MAX);
+ if (other >= cputime)
+ return;
+
+ cputime -= other;
+
+ if (this_cpu_ksoftirqd() == p) {
+ /*
+ * ksoftirqd time do not get accounted in cpu_softirq_time.
+ * So, we have to handle it separately here.
+ * Also, p->stime needs to be updated for ksoftirqd.
+ */
+ account_system_index_time(p, cputime, CPUTIME_SOFTIRQ);
+ } else if (user_tick) {
+ account_user_time(p, cputime);
+ } else if (p == rq->idle) {
+ account_idle_time(cputime);
+ } else if (p->flags & PF_VCPU) { /* System time or guest time */
+ account_guest_time(p, cputime);
+ } else {
+ account_system_index_time(p, cputime, CPUTIME_SYSTEM);
+ }
+}
+
+static void irqtime_account_idle_ticks(int ticks)
+{
+ struct rq *rq = this_rq();
+
+ irqtime_account_process_tick(current, 0, rq, ticks);
+}
+#else /* CONFIG_IRQ_TIME_ACCOUNTING */
+static inline void irqtime_account_idle_ticks(int ticks) { }
+static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
+ struct rq *rq, int nr_ticks) { }
+#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
+
+/*
+ * Use precise platform statistics if available:
+ */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING
+# ifndef __ARCH_HAS_VTIME_TASK_SWITCH
+void vtime_common_task_switch(struct task_struct *prev)
+{
+ if (is_idle_task(prev))
+ vtime_account_idle(prev);
+ else
+ vtime_account_system(prev);
+
+ vtime_flush(prev);
+ arch_vtime_task_switch(prev);
+}
+# endif
+#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
+
+
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+/*
+ * Archs that account the whole time spent in the idle task
+ * (outside irq) as idle time can rely on this and just implement
+ * vtime_account_system() and vtime_account_idle(). Archs that
+ * have other meaning of the idle time (s390 only includes the
+ * time spent by the CPU when it's in low power mode) must override
+ * vtime_account().
+ */
+#ifndef __ARCH_HAS_VTIME_ACCOUNT
+void vtime_account_irq_enter(struct task_struct *tsk)
+{
+ if (!in_interrupt() && is_idle_task(tsk))
+ vtime_account_idle(tsk);
+ else
+ vtime_account_system(tsk);
+}
+EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
+#endif /* __ARCH_HAS_VTIME_ACCOUNT */
+
+void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
+ u64 *ut, u64 *st)
+{
+ *ut = curr->utime;
+ *st = curr->stime;
+}
+
+void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
+{
+ *ut = p->utime;
+ *st = p->stime;
+}
+EXPORT_SYMBOL_GPL(task_cputime_adjusted);
+
+void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
+{
+ struct task_cputime cputime;
+
+ thread_group_cputime(p, &cputime);
+
+ *ut = cputime.utime;
+ *st = cputime.stime;
+}
+
+#else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE: */
+
+/*
+ * Account a single tick of CPU time.
+ * @p: the process that the CPU time gets accounted to
+ * @user_tick: indicates if the tick is a user or a system tick
+ */
+void account_process_tick(struct task_struct *p, int user_tick)
+{
+ u64 cputime, steal;
+ struct rq *rq = this_rq();
+
+ if (vtime_accounting_cpu_enabled())
+ return;
+
+ if (sched_clock_irqtime) {
+ irqtime_account_process_tick(p, user_tick, rq, 1);
+ return;
+ }
+
+ cputime = TICK_NSEC;
+ steal = steal_account_process_time(ULONG_MAX);
+
+ if (steal >= cputime)
+ return;
+
+ cputime -= steal;
+
+ if (user_tick)
+ account_user_time(p, cputime);
+ else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
+ account_system_time(p, HARDIRQ_OFFSET, cputime);
+ else
+ account_idle_time(cputime);
+}
+
+/*
+ * Account multiple ticks of idle time.
+ * @ticks: number of stolen ticks
+ */
+void account_idle_ticks(unsigned long ticks)
+{
+ u64 cputime, steal;
+
+ if (sched_clock_irqtime) {
+ irqtime_account_idle_ticks(ticks);
+ return;
+ }
+
+ cputime = ticks * TICK_NSEC;
+ steal = steal_account_process_time(ULONG_MAX);
+
+ if (steal >= cputime)
+ return;
+
+ cputime -= steal;
+ account_idle_time(cputime);
+}
+
+/*
+ * Perform (stime * rtime) / total, but avoid multiplication overflow by
+ * loosing precision when the numbers are big.
+ */
+static u64 scale_stime(u64 stime, u64 rtime, u64 total)
+{
+ u64 scaled;
+
+ for (;;) {
+ /* Make sure "rtime" is the bigger of stime/rtime */
+ if (stime > rtime)
+ swap(rtime, stime);
+
+ /* Make sure 'total' fits in 32 bits */
+ if (total >> 32)
+ goto drop_precision;
+
+ /* Does rtime (and thus stime) fit in 32 bits? */
+ if (!(rtime >> 32))
+ break;
+
+ /* Can we just balance rtime/stime rather than dropping bits? */
+ if (stime >> 31)
+ goto drop_precision;
+
+ /* We can grow stime and shrink rtime and try to make them both fit */
+ stime <<= 1;
+ rtime >>= 1;
+ continue;
+
+drop_precision:
+ /* We drop from rtime, it has more bits than stime */
+ rtime >>= 1;
+ total >>= 1;
+ }
+
+ /*
+ * Make sure gcc understands that this is a 32x32->64 multiply,
+ * followed by a 64/32->64 divide.
+ */
+ scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total);
+ return scaled;
+}
+
+/*
+ * Adjust tick based cputime random precision against scheduler runtime
+ * accounting.
+ *
+ * Tick based cputime accounting depend on random scheduling timeslices of a
+ * task to be interrupted or not by the timer. Depending on these
+ * circumstances, the number of these interrupts may be over or
+ * under-optimistic, matching the real user and system cputime with a variable
+ * precision.
+ *
+ * Fix this by scaling these tick based values against the total runtime
+ * accounted by the CFS scheduler.
+ *
+ * This code provides the following guarantees:
+ *
+ * stime + utime == rtime
+ * stime_i+1 >= stime_i, utime_i+1 >= utime_i
+ *
+ * Assuming that rtime_i+1 >= rtime_i.
+ */
+void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
+ u64 *ut, u64 *st)
+{
+ u64 rtime, stime, utime;
+ unsigned long flags;
+
+ /* Serialize concurrent callers such that we can honour our guarantees */
+ raw_spin_lock_irqsave(&prev->lock, flags);
+ rtime = curr->sum_exec_runtime;
+
+ /*
+ * This is possible under two circumstances:
+ * - rtime isn't monotonic after all (a bug);
+ * - we got reordered by the lock.
+ *
+ * In both cases this acts as a filter such that the rest of the code
+ * can assume it is monotonic regardless of anything else.
+ */
+ if (prev->stime + prev->utime >= rtime)
+ goto out;
+
+ stime = curr->stime;
+ utime = curr->utime;
+
+ /*
+ * If either stime or utime are 0, assume all runtime is userspace.
+ * Once a task gets some ticks, the monotonicy code at 'update:'
+ * will ensure things converge to the observed ratio.
+ */
+ if (stime == 0) {
+ utime = rtime;
+ goto update;
+ }
+
+ if (utime == 0) {
+ stime = rtime;
+ goto update;
+ }
+
+ stime = scale_stime(stime, rtime, stime + utime);
+
+update:
+ /*
+ * Make sure stime doesn't go backwards; this preserves monotonicity
+ * for utime because rtime is monotonic.
+ *
+ * utime_i+1 = rtime_i+1 - stime_i
+ * = rtime_i+1 - (rtime_i - utime_i)
+ * = (rtime_i+1 - rtime_i) + utime_i
+ * >= utime_i
+ */
+ if (stime < prev->stime)
+ stime = prev->stime;
+ utime = rtime - stime;
+
+ /*
+ * Make sure utime doesn't go backwards; this still preserves
+ * monotonicity for stime, analogous argument to above.
+ */
+ if (utime < prev->utime) {
+ utime = prev->utime;
+ stime = rtime - utime;
+ }
+
+ prev->stime = stime;
+ prev->utime = utime;
+out:
+ *ut = prev->utime;
+ *st = prev->stime;
+ raw_spin_unlock_irqrestore(&prev->lock, flags);
+}
+
+void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
+{
+ struct task_cputime cputime = {
+ .sum_exec_runtime = p->se.sum_exec_runtime,
+ };
+
+ task_cputime(p, &cputime.utime, &cputime.stime);
+ cputime_adjust(&cputime, &p->prev_cputime, ut, st);
+}
+EXPORT_SYMBOL_GPL(task_cputime_adjusted);
+
+void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
+{
+ struct task_cputime cputime;
+
+ thread_group_cputime(p, &cputime);
+ cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
+}
+#endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
+
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
+static u64 vtime_delta(struct vtime *vtime)
+{
+ unsigned long long clock;
+
+ clock = sched_clock();
+ if (clock < vtime->starttime)
+ return 0;
+
+ return clock - vtime->starttime;
+}
+
+static u64 get_vtime_delta(struct vtime *vtime)
+{
+ u64 delta = vtime_delta(vtime);
+ u64 other;
+
+ /*
+ * Unlike tick based timing, vtime based timing never has lost
+ * ticks, and no need for steal time accounting to make up for
+ * lost ticks. Vtime accounts a rounded version of actual
+ * elapsed time. Limit account_other_time to prevent rounding
+ * errors from causing elapsed vtime to go negative.
+ */
+ other = account_other_time(delta);
+ WARN_ON_ONCE(vtime->state == VTIME_INACTIVE);
+ vtime->starttime += delta;
+
+ return delta - other;
+}
+
+static void __vtime_account_system(struct task_struct *tsk,
+ struct vtime *vtime)
+{
+ vtime->stime += get_vtime_delta(vtime);
+ if (vtime->stime >= TICK_NSEC) {
+ account_system_time(tsk, irq_count(), vtime->stime);
+ vtime->stime = 0;
+ }
+}
+
+static void vtime_account_guest(struct task_struct *tsk,
+ struct vtime *vtime)
+{
+ vtime->gtime += get_vtime_delta(vtime);
+ if (vtime->gtime >= TICK_NSEC) {
+ account_guest_time(tsk, vtime->gtime);
+ vtime->gtime = 0;
+ }
+}
+
+void vtime_account_system(struct task_struct *tsk)
+{
+ struct vtime *vtime = &tsk->vtime;
+
+ if (!vtime_delta(vtime))
+ return;
+
+ write_seqcount_begin(&vtime->seqcount);
+ /* We might have scheduled out from guest path */
+ if (current->flags & PF_VCPU)
+ vtime_account_guest(tsk, vtime);
+ else
+ __vtime_account_system(tsk, vtime);
+ write_seqcount_end(&vtime->seqcount);
+}
+
+void vtime_user_enter(struct task_struct *tsk)
+{
+ struct vtime *vtime = &tsk->vtime;
+
+ write_seqcount_begin(&vtime->seqcount);
+ __vtime_account_system(tsk, vtime);
+ vtime->state = VTIME_USER;
+ write_seqcount_end(&vtime->seqcount);
+}
+
+void vtime_user_exit(struct task_struct *tsk)
+{
+ struct vtime *vtime = &tsk->vtime;
+
+ write_seqcount_begin(&vtime->seqcount);
+ vtime->utime += get_vtime_delta(vtime);
+ if (vtime->utime >= TICK_NSEC) {
+ account_user_time(tsk, vtime->utime);
+ vtime->utime = 0;
+ }
+ vtime->state = VTIME_SYS;
+ write_seqcount_end(&vtime->seqcount);
+}
+
+void vtime_guest_enter(struct task_struct *tsk)
+{
+ struct vtime *vtime = &tsk->vtime;
+ /*
+ * The flags must be updated under the lock with
+ * the vtime_starttime flush and update.
+ * That enforces a right ordering and update sequence
+ * synchronization against the reader (task_gtime())
+ * that can thus safely catch up with a tickless delta.
+ */
+ write_seqcount_begin(&vtime->seqcount);
+ __vtime_account_system(tsk, vtime);
+ current->flags |= PF_VCPU;
+ write_seqcount_end(&vtime->seqcount);
+}
+EXPORT_SYMBOL_GPL(vtime_guest_enter);
+
+void vtime_guest_exit(struct task_struct *tsk)
+{
+ struct vtime *vtime = &tsk->vtime;
+
+ write_seqcount_begin(&vtime->seqcount);
+ vtime_account_guest(tsk, vtime);
+ current->flags &= ~PF_VCPU;
+ write_seqcount_end(&vtime->seqcount);
+}
+EXPORT_SYMBOL_GPL(vtime_guest_exit);
+
+void vtime_account_idle(struct task_struct *tsk)
+{
+ account_idle_time(get_vtime_delta(&tsk->vtime));
+}
+
+void arch_vtime_task_switch(struct task_struct *prev)
+{
+ struct vtime *vtime = &prev->vtime;
+
+ write_seqcount_begin(&vtime->seqcount);
+ vtime->state = VTIME_INACTIVE;
+ write_seqcount_end(&vtime->seqcount);
+
+ vtime = ¤t->vtime;
+
+ write_seqcount_begin(&vtime->seqcount);
+ vtime->state = VTIME_SYS;
+ vtime->starttime = sched_clock();
+ write_seqcount_end(&vtime->seqcount);
+}
+
+void vtime_init_idle(struct task_struct *t, int cpu)
+{
+ struct vtime *vtime = &t->vtime;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ write_seqcount_begin(&vtime->seqcount);
+ vtime->state = VTIME_SYS;
+ vtime->starttime = sched_clock();
+ write_seqcount_end(&vtime->seqcount);
+ local_irq_restore(flags);
+}
+
+u64 task_gtime(struct task_struct *t)
+{
+ struct vtime *vtime = &t->vtime;
+ unsigned int seq;
+ u64 gtime;
+
+ if (!vtime_accounting_enabled())
+ return t->gtime;
+
+ do {
+ seq = read_seqcount_begin(&vtime->seqcount);
+
+ gtime = t->gtime;
+ if (vtime->state == VTIME_SYS && t->flags & PF_VCPU)
+ gtime += vtime->gtime + vtime_delta(vtime);
+
+ } while (read_seqcount_retry(&vtime->seqcount, seq));
+
+ return gtime;
+}
+
+/*
+ * Fetch cputime raw values from fields of task_struct and
+ * add up the pending nohz execution time since the last
+ * cputime snapshot.
+ */
+void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
+{
+ struct vtime *vtime = &t->vtime;
+ unsigned int seq;
+ u64 delta;
+
+ if (!vtime_accounting_enabled()) {
+ *utime = t->utime;
+ *stime = t->stime;
+ return;
+ }
+
+ do {
+ seq = read_seqcount_begin(&vtime->seqcount);
+
+ *utime = t->utime;
+ *stime = t->stime;
+
+ /* Task is sleeping, nothing to add */
+ if (vtime->state == VTIME_INACTIVE || is_idle_task(t))
+ continue;
+
+ delta = vtime_delta(vtime);
+
+ /*
+ * Task runs either in user or kernel space, add pending nohz time to
+ * the right place.
+ */
+ if (vtime->state == VTIME_USER || t->flags & PF_VCPU)
+ *utime += vtime->utime + delta;
+ else if (vtime->state == VTIME_SYS)
+ *stime += vtime->stime + delta;
+ } while (read_seqcount_retry(&vtime->seqcount, seq));
+}
+#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */