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

#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/alarmtimer.h>
#include <linux/timerqueue.h>
#include <linux/task_work.h>

struct kernel_siginfo;
struct task_struct;

/*
 * Bit fields within a clockid:
 *
 * The most significant 29 bits hold either a pid or a file descriptor.
 *
 * Bit 2 indicates whether a cpu clock refers to a thread or a process.
 *
 * Bits 1 and 0 give the type: PROF=0, VIRT=1, SCHED=2, or FD=3.
 *
 * A clockid is invalid if bits 2, 1, and 0 are all set.
 */
#define CPUCLOCK_PID(clock)             ((pid_t) ~((clock) >> 3))
#define CPUCLOCK_PERTHREAD(clock) \
        (((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0)

#define CPUCLOCK_PERTHREAD_MASK 4
#define CPUCLOCK_WHICH(clock)   ((clock) & (clockid_t) CPUCLOCK_CLOCK_MASK)
#define CPUCLOCK_CLOCK_MASK     3
#define CPUCLOCK_PROF           0
#define CPUCLOCK_VIRT           1
#define CPUCLOCK_SCHED          2
#define CPUCLOCK_MAX            3
#define CLOCKFD                 CPUCLOCK_MAX
#define CLOCKFD_MASK            (CPUCLOCK_PERTHREAD_MASK|CPUCLOCK_CLOCK_MASK)

static inline clockid_t make_process_cpuclock(const unsigned int pid,
                const clockid_t clock)
{
        return ((~pid) << 3) | clock;
}
static inline clockid_t make_thread_cpuclock(const unsigned int tid,
                const clockid_t clock)
{
        return make_process_cpuclock(tid, clock | CPUCLOCK_PERTHREAD_MASK);
}

static inline clockid_t fd_to_clockid(const int fd)
{
        return make_process_cpuclock((unsigned int) fd, CLOCKFD);
}

static inline int clockid_to_fd(const clockid_t clk)
{
        return ~(clk >> 3);
}

#ifdef CONFIG_POSIX_TIMERS

/**
 * cpu_timer - Posix CPU timer representation for k_itimer
 * @node:       timerqueue node to queue in the task/sig
 * @head:       timerqueue head on which this timer is queued
 * @task:       Pointer to target task
 * @elist:      List head for the expiry list
 * @firing:     Timer is currently firing
 */
struct cpu_timer {
        struct timerqueue_node  node;
        struct timerqueue_head  *head;
        struct pid              *pid;
        struct list_head        elist;
        int                     firing;
};

static inline bool cpu_timer_enqueue(struct timerqueue_head *head,
                                     struct cpu_timer *ctmr)
{
        ctmr->head = head;
        return timerqueue_add(head, &ctmr->node);
}

static inline void cpu_timer_dequeue(struct cpu_timer *ctmr)
{
        if (ctmr->head) {
                timerqueue_del(ctmr->head, &ctmr->node);
                ctmr->head = NULL;
        }
}

static inline u64 cpu_timer_getexpires(struct cpu_timer *ctmr)
{
        return ctmr->node.expires;
}

static inline void cpu_timer_setexpires(struct cpu_timer *ctmr, u64 exp)
{
        ctmr->node.expires = exp;
}

/**
 * posix_cputimer_base - Container per posix CPU clock
 * @nextevt:            Earliest-expiration cache
 * @tqhead:             timerqueue head for cpu_timers
 */
struct posix_cputimer_base {
        u64                     nextevt;
        struct timerqueue_head  tqhead;
};

/**
 * posix_cputimers - Container for posix CPU timer related data
 * @bases:              Base container for posix CPU clocks
 * @timers_active:      Timers are queued.
 * @expiry_active:      Timer expiry is active. Used for
 *                      process wide timers to avoid multiple
 *                      task trying to handle expiry concurrently
 *
 * Used in task_struct and signal_struct
 */
struct posix_cputimers {
        struct posix_cputimer_base      bases[CPUCLOCK_MAX];
        unsigned int                    timers_active;
        unsigned int                    expiry_active;
};

/**
 * posix_cputimers_work - Container for task work based posix CPU timer expiry
 * @work:       The task work to be scheduled
 * @scheduled:  @work has been scheduled already, no further processing
 */
struct posix_cputimers_work {
        struct callback_head    work;
        unsigned int            scheduled;
};

static inline void posix_cputimers_init(struct posix_cputimers *pct)
{
        memset(pct, 0, sizeof(*pct));
        pct->bases[0].nextevt = U64_MAX;
        pct->bases[1].nextevt = U64_MAX;
        pct->bases[2].nextevt = U64_MAX;
}

void posix_cputimers_group_init(struct posix_cputimers *pct, u64 cpu_limit);

static inline void posix_cputimers_rt_watchdog(struct posix_cputimers *pct,
                                               u64 runtime)
{
        pct->bases[CPUCLOCK_SCHED].nextevt = runtime;
}

/* Init task static initializer */
#define INIT_CPU_TIMERBASE(b) {                                         \
        .nextevt        = U64_MAX,                                      \
}

#define INIT_CPU_TIMERBASES(b) {                                        \
        INIT_CPU_TIMERBASE(b[0]),                                       \
        INIT_CPU_TIMERBASE(b[1]),                                       \
        INIT_CPU_TIMERBASE(b[2]),                                       \
}

#define INIT_CPU_TIMERS(s)                                              \
        .posix_cputimers = {                                            \
                .bases = INIT_CPU_TIMERBASES(s.posix_cputimers.bases),  \
        },
#else
struct posix_cputimers { };
struct cpu_timer { };
#define INIT_CPU_TIMERS(s)
static inline void posix_cputimers_init(struct posix_cputimers *pct) { }
static inline void posix_cputimers_group_init(struct posix_cputimers *pct,
                                              u64 cpu_limit) { }
#endif

#ifdef CONFIG_POSIX_CPU_TIMERS_TASK_WORK
void posix_cputimers_init_work(void);
#else
static inline void posix_cputimers_init_work(void) { }
#endif

#define REQUEUE_PENDING 1

/**
 * struct k_itimer - POSIX.1b interval timer structure.
 * @list:               List head for binding the timer to signals->posix_timers
 * @t_hash:             Entry in the posix timer hash table
 * @it_lock:            Lock protecting the timer
 * @kclock:             Pointer to the k_clock struct handling this timer
 * @it_clock:           The posix timer clock id
 * @it_id:              The posix timer id for identifying the timer
 * @it_active:          Marker that timer is active
 * @it_overrun:         The overrun counter for pending signals
 * @it_overrun_last:    The overrun at the time of the last delivered signal
 * @it_requeue_pending: Indicator that timer waits for being requeued on
 *                      signal delivery
 * @it_sigev_notify:    The notify word of sigevent struct for signal delivery
 * @it_interval:        The interval for periodic timers
 * @it_signal:          Pointer to the creators signal struct
 * @it_pid:             The pid of the process/task targeted by the signal
 * @it_process:         The task to wakeup on clock_nanosleep (CPU timers)
 * @sigq:               Pointer to preallocated sigqueue
 * @it:                 Union representing the various posix timer type
 *                      internals.
 * @rcu:                RCU head for freeing the timer.
 */
struct k_itimer {
        struct list_head        list;
        struct hlist_node       t_hash;
        spinlock_t              it_lock;
        const struct k_clock    *kclock;
        clockid_t               it_clock;
        timer_t                 it_id;
        int                     it_active;
        s64                     it_overrun;
        s64                     it_overrun_last;
        int                     it_requeue_pending;
        int                     it_sigev_notify;
        ktime_t                 it_interval;
        struct signal_struct    *it_signal;
        union {
                struct pid              *it_pid;
                struct task_struct      *it_process;
        };
        struct sigqueue         *sigq;
        union {
                struct {
                        struct hrtimer  timer;
                } real;
                struct cpu_timer        cpu;
                struct {
                        struct alarm    alarmtimer;
                } alarm;
        } it;
        struct rcu_head         rcu;
};

void run_posix_cpu_timers(void);
void posix_cpu_timers_exit(struct task_struct *task);
void posix_cpu_timers_exit_group(struct task_struct *task);
void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
                           u64 *newval, u64 *oldval);

void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);

void posixtimer_rearm(struct kernel_siginfo *info);
#endif