fs/proc/uptime.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/fs.h>
   3 #include <linux/init.h>
   4 #include <linux/proc_fs.h>
   5 #include <linux/sched.h>
   6 #include <linux/seq_file.h>
   7 #include <linux/time.h>
   8 #include <linux/time_namespace.h>
   9 #include <linux/kernel_stat.h>
  10
  11 static int uptime_proc_show(struct seq_file *m, void *v)
  12 {
  13         struct timespec64 uptime;
  14         struct timespec64 idle;
  15         u64 nsec;
  16         u32 rem;
  17         int i;
  18
  19         nsec = 0;
  20         for_each_possible_cpu(i)
  21                 nsec += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE];
  22
  23         ktime_get_boottime_ts64(&uptime);
  24         timens_add_boottime(&uptime);
  25
  26         idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
  27         idle.tv_nsec = rem;
  28         seq_printf(m, "%lu.%02lu %lu.%02lu\n",
  29                         (unsigned long) uptime.tv_sec,
  30                         (uptime.tv_nsec / (NSEC_PER_SEC / 100)),
  31                         (unsigned long) idle.tv_sec,
  32                         (idle.tv_nsec / (NSEC_PER_SEC / 100)));
  33         return 0;
  34 }
  35
  36 static int __init proc_uptime_init(void)
  37 {
  38         proc_create_single("uptime", 0, NULL, uptime_proc_show);
  39         return 0;
  40 }
  41 fs_initcall(proc_uptime_init);