/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_SCHED_CPUTIME_H
#define _LINUX_SCHED_CPUTIME_H

#include <linux/static_call_types.h>
#include <linux/sched/signal.h>

/*
 * cputime accounting APIs:
 */

#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
extern bool task_cputime(struct task_struct *t,
                         u64 *utime, u64 *stime);
extern u64 task_gtime(struct task_struct *t);
#else
static inline bool task_cputime(struct task_struct *t,
                                u64 *utime, u64 *stime)
{
        *utime = t->utime;
        *stime = t->stime;
        return false;
}

static inline u64 task_gtime(struct task_struct *t)
{
        return t->gtime;
}
#endif

#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
static inline void task_cputime_scaled(struct task_struct *t,
                                       u64 *utimescaled,
                                       u64 *stimescaled)
{
        *utimescaled = t->utimescaled;
        *stimescaled = t->stimescaled;
}
#else
static inline void task_cputime_scaled(struct task_struct *t,
                                       u64 *utimescaled,
                                       u64 *stimescaled)
{
        task_cputime(t, utimescaled, stimescaled);
}
#endif

extern void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st);
extern void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st);
extern void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
                           u64 *ut, u64 *st);

/*
 * Thread group CPU time accounting.
 */
void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
void thread_group_sample_cputime(struct task_struct *tsk, u64 *samples);

/*
 * The following are functions that support scheduler-internal time accounting.
 * These functions are generally called at the timer tick.  None of this depends
 * on CONFIG_SCHEDSTATS.
 */

/**
 * get_running_cputimer - return &tsk->signal->cputimer if cputimers are active
 *
 * @tsk:        Pointer to target task.
 */
#ifdef CONFIG_POSIX_TIMERS
static inline
struct thread_group_cputimer *get_running_cputimer(struct task_struct *tsk)
{
        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

        /*
         * Check whether posix CPU timers are active. If not the thread
         * group accounting is not active either. Lockless check.
         */
        if (!READ_ONCE(tsk->signal->posix_cputimers.timers_active))
                return NULL;

        /*
         * After we flush the task's sum_exec_runtime to sig->sum_sched_runtime
         * in __exit_signal(), we won't account to the signal struct further
         * cputime consumed by that task, even though the task can still be
         * ticking after __exit_signal().
         *
         * In order to keep a consistent behaviour between thread group cputime
         * and thread group cputimer accounting, lets also ignore the cputime
         * elapsing after __exit_signal() in any thread group timer running.
         *
         * This makes sure that POSIX CPU clocks and timers are synchronized, so
         * that a POSIX CPU timer won't expire while the corresponding POSIX CPU
         * clock delta is behind the expiring timer value.
         */
        if (unlikely(!tsk->sighand))
                return NULL;

        return cputimer;
}
#else
static inline
struct thread_group_cputimer *get_running_cputimer(struct task_struct *tsk)
{
        return NULL;
}
#endif

/**
 * account_group_user_time - Maintain utime for a thread group.
 *
 * @tsk:        Pointer to task structure.
 * @cputime:    Time value by which to increment the utime field of the
 *              thread_group_cputime structure.
 *
 * If thread group time is being maintained, get the structure for the
 * running CPU and update the utime field there.
 */
static inline void account_group_user_time(struct task_struct *tsk,
                                           u64 cputime)
{
        struct thread_group_cputimer *cputimer = get_running_cputimer(tsk);

        if (!cputimer)
                return;

        atomic64_add(cputime, &cputimer->cputime_atomic.utime);
}

/**
 * account_group_system_time - Maintain stime for a thread group.
 *
 * @tsk:        Pointer to task structure.
 * @cputime:    Time value by which to increment the stime field of the
 *              thread_group_cputime structure.
 *
 * If thread group time is being maintained, get the structure for the
 * running CPU and update the stime field there.
 */
static inline void account_group_system_time(struct task_struct *tsk,
                                             u64 cputime)
{
        struct thread_group_cputimer *cputimer = get_running_cputimer(tsk);

        if (!cputimer)
                return;

        atomic64_add(cputime, &cputimer->cputime_atomic.stime);
}

/**
 * account_group_exec_runtime - Maintain exec runtime for a thread group.
 *
 * @tsk:        Pointer to task structure.
 * @ns:         Time value by which to increment the sum_exec_runtime field
 *              of the thread_group_cputime structure.
 *
 * If thread group time is being maintained, get the structure for the
 * running CPU and update the sum_exec_runtime field there.
 */
static inline void account_group_exec_runtime(struct task_struct *tsk,
                                              unsigned long long ns)
{
        struct thread_group_cputimer *cputimer = get_running_cputimer(tsk);

        if (!cputimer)
                return;

        atomic64_add(ns, &cputimer->cputime_atomic.sum_exec_runtime);
}

static inline void prev_cputime_init(struct prev_cputime *prev)
{
#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
        prev->utime = prev->stime = 0;
        raw_spin_lock_init(&prev->lock);
#endif
}

extern unsigned long long
task_sched_runtime(struct task_struct *task);

#ifdef CONFIG_PARAVIRT
struct static_key;
extern struct static_key paravirt_steal_enabled;
extern struct static_key paravirt_steal_rq_enabled;

#ifdef CONFIG_HAVE_PV_STEAL_CLOCK_GEN
u64 dummy_steal_clock(int cpu);

DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);

static inline u64 paravirt_steal_clock(int cpu)
{
        return static_call(pv_steal_clock)(cpu);
}
#endif
#endif

#endif /* _LINUX_SCHED_CPUTIME_H */