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 #include "internal.h"
  11
  12 static int uptime_proc_show(struct seq_file *m, void *v)
  13 {
  14         struct timespec64 uptime;
  15         struct timespec64 idle;
  16         u64 idle_nsec;
  17         u32 rem;
  18         int i;
  19
  20         idle_nsec = 0;
  21         for_each_possible_cpu(i) {
  22                 struct kernel_cpustat kcs;
  23
  24                 kcpustat_cpu_fetch(&kcs, i);
  25                 idle_nsec += get_idle_time(&kcs, i);
  26         }
  27
  28         ktime_get_boottime_ts64(&uptime);
  29         timens_add_boottime(&uptime);
  30
  31         idle.tv_sec = div_u64_rem(idle_nsec, NSEC_PER_SEC, &rem);
  32         idle.tv_nsec = rem;
  33         seq_printf(m, "%lu.%02lu %lu.%02lu\n",
  34                         (unsigned long) uptime.tv_sec,
  35                         (uptime.tv_nsec / (NSEC_PER_SEC / 100)),
  36                         (unsigned long) idle.tv_sec,
  37                         (idle.tv_nsec / (NSEC_PER_SEC / 100)));
  38         return 0;
  39 }
  40
  41 static int __init proc_uptime_init(void)
  42 {
  43         struct proc_dir_entry *pde;
  44
  45         pde = proc_create_single("uptime", 0, NULL, uptime_proc_show);
  46         pde_make_permanent(pde);
  47         return 0;
  48 }
  49 fs_initcall(proc_uptime_init);