// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * tsacct.c - System accounting over taskstats interface
   *
   * Copyright (C) Jay Lan,	<jlan@sgi.com>

   */
  
  #include <linux/kernel.h>

  #include <linux/sched/signal.h>

  #include <linux/sched/mm.h>

  #include <linux/sched/cputime.h>

  #include <linux/tsacct_kern.h>
  #include <linux/acct.h>

  #include <linux/jiffies.h>

  #include <linux/mm.h>

  /*
   * fill in basic accounting fields
   */

  void bacct_add_tsk(struct user_namespace *user_ns,
  		   struct pid_namespace *pid_ns,
  		   struct taskstats *stats, struct task_struct *tsk)

  {

  	const struct cred *tcred;

  	u64 utime, stime, utimescaled, stimescaled;

  	u64 delta;

  	time64_t btime;

  
  	BUILD_BUG_ON(TS_COMM_LEN < TASK_COMM_LEN);

  	/* calculate task elapsed time in nsec */
  	delta = ktime_get_ns() - tsk->start_time;
  	/* Convert to micro seconds */
  	do_div(delta, NSEC_PER_USEC);
  	stats->ac_etime = delta;

  	/* Convert to seconds for btime (note y2106 limit) */
  	btime = ktime_get_real_seconds() - div_u64(delta, USEC_PER_SEC);
  	stats->ac_btime = clamp_t(time64_t, btime, 0, U32_MAX);

  	stats->ac_btime64 = btime;

  	if (thread_group_leader(tsk)) {
  		stats->ac_exitcode = tsk->exit_code;
  		if (tsk->flags & PF_FORKNOEXEC)
  			stats->ac_flag |= AFORK;
  	}
  	if (tsk->flags & PF_SUPERPRIV)
  		stats->ac_flag |= ASU;
  	if (tsk->flags & PF_DUMPCORE)
  		stats->ac_flag |= ACORE;
  	if (tsk->flags & PF_SIGNALED)
  		stats->ac_flag |= AXSIG;
  	stats->ac_nice	 = task_nice(tsk);
  	stats->ac_sched	 = tsk->policy;

  	stats->ac_pid	 = task_pid_nr_ns(tsk, pid_ns);

  	rcu_read_lock();

  	tcred = __task_cred(tsk);

  	stats->ac_uid	 = from_kuid_munged(user_ns, tcred->uid);
  	stats->ac_gid	 = from_kgid_munged(user_ns, tcred->gid);

  	stats->ac_ppid	 = pid_alive(tsk) ?

  		task_tgid_nr_ns(rcu_dereference(tsk->real_parent), pid_ns) : 0;

  	rcu_read_unlock();

  	task_cputime(tsk, &utime, &stime);
  	stats->ac_utime = div_u64(utime, NSEC_PER_USEC);
  	stats->ac_stime = div_u64(stime, NSEC_PER_USEC);

  	task_cputime_scaled(tsk, &utimescaled, &stimescaled);
  	stats->ac_utimescaled = div_u64(utimescaled, NSEC_PER_USEC);
  	stats->ac_stimescaled = div_u64(stimescaled, NSEC_PER_USEC);

  	stats->ac_minflt = tsk->min_flt;
  	stats->ac_majflt = tsk->maj_flt;

  
  	strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm));
  }

  
  #ifdef CONFIG_TASK_XACCT

  
  #define KB 1024
  #define MB (1024*KB)

  #define KB_MASK (~(KB-1))

  /*
   * fill in extended accounting fields
   */
  void xacct_add_tsk(struct taskstats *stats, struct task_struct *p)
  {

  	struct mm_struct *mm;

  	/* convert pages-nsec/1024 to Mbyte-usec, see __acct_update_integrals */
  	stats->coremem = p->acct_rss_mem1 * PAGE_SIZE;
  	do_div(stats->coremem, 1000 * KB);
  	stats->virtmem = p->acct_vm_mem1 * PAGE_SIZE;
  	do_div(stats->virtmem, 1000 * KB);

  	mm = get_task_mm(p);
  	if (mm) {

  		/* adjust to KB unit */

  		stats->hiwater_rss   = get_mm_hiwater_rss(mm) * PAGE_SIZE / KB;
  		stats->hiwater_vm    = get_mm_hiwater_vm(mm)  * PAGE_SIZE / KB;

  		mmput(mm);

  	}

  	stats->read_char	= p->ioac.rchar & KB_MASK;
  	stats->write_char	= p->ioac.wchar & KB_MASK;
  	stats->read_syscalls	= p->ioac.syscr & KB_MASK;
  	stats->write_syscalls	= p->ioac.syscw & KB_MASK;

  #ifdef CONFIG_TASK_IO_ACCOUNTING

  	stats->read_bytes	= p->ioac.read_bytes & KB_MASK;
  	stats->write_bytes	= p->ioac.write_bytes & KB_MASK;
  	stats->cancelled_write_bytes = p->ioac.cancelled_write_bytes & KB_MASK;

  #else
  	stats->read_bytes	= 0;
  	stats->write_bytes	= 0;
  	stats->cancelled_write_bytes = 0;
  #endif

  }

  #undef KB
  #undef MB

  static void __acct_update_integrals(struct task_struct *tsk,

  				    u64 utime, u64 stime)

  {

  	u64 time, delta;

  
  	if (!likely(tsk->mm))
  		return;

  	time = stime + utime;

  	delta = time - tsk->acct_timexpd;

  
  	if (delta < TICK_NSEC)

  		return;

  
  	tsk->acct_timexpd = time;
  	/*
  	 * Divide by 1024 to avoid overflow, and to avoid division.
  	 * The final unit reported to userspace is Mbyte-usecs,
  	 * the rest of the math is done in xacct_add_tsk.
  	 */
  	tsk->acct_rss_mem1 += delta * get_mm_rss(tsk->mm) >> 10;
  	tsk->acct_vm_mem1 += delta * tsk->mm->total_vm >> 10;

  }
  
  /**

   * acct_update_integrals - update mm integral fields in task_struct
   * @tsk: task_struct for accounting
   */
  void acct_update_integrals(struct task_struct *tsk)
  {

  	u64 utime, stime;

  	unsigned long flags;

  	local_irq_save(flags);

  	task_cputime(tsk, &utime, &stime);

  	__acct_update_integrals(tsk, utime, stime);

  	local_irq_restore(flags);

  }
  
  /**
   * acct_account_cputime - update mm integral after cputime update
   * @tsk: task_struct for accounting
   */
  void acct_account_cputime(struct task_struct *tsk)
  {
  	__acct_update_integrals(tsk, tsk->utime, tsk->stime);
  }
  
  /**

   * acct_clear_integrals - clear the mm integral fields in task_struct
   * @tsk: task_struct whose accounting fields are cleared
   */
  void acct_clear_integrals(struct task_struct *tsk)
  {

  	tsk->acct_timexpd = 0;

  	tsk->acct_rss_mem1 = 0;
  	tsk->acct_vm_mem1 = 0;
  }

  #endif