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/kernel_stat.h>
   9
  10 static int uptime_proc_show(struct seq_file *m, void *v)
  11 {
  12         struct timespec uptime;
  13         struct timespec idle;
  14         u64 nsec;
  15         u32 rem;
  16         int i;
  17
  18         nsec = 0;
  19         for_each_possible_cpu(i)
  20                 nsec += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE];
  21
  22         get_monotonic_boottime(&uptime);
  23         idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
  24         idle.tv_nsec = rem;
  25         seq_printf(m, "%lu.%02lu %lu.%02lu\n",
  26                         (unsigned long) uptime.tv_sec,
  27                         (uptime.tv_nsec / (NSEC_PER_SEC / 100)),
  28                         (unsigned long) idle.tv_sec,
  29                         (idle.tv_nsec / (NSEC_PER_SEC / 100)));
  30         return 0;
  31 }
  32
  33 static int uptime_proc_open(struct inode *inode, struct file *file)
  34 {
  35         return single_open(file, uptime_proc_show, NULL);
  36 }
  37
  38 static const struct file_operations uptime_proc_fops = {
  39         .open           = uptime_proc_open,
  40         .read           = seq_read,
  41         .llseek         = seq_lseek,
  42         .release        = single_release,
  43 };
  44
  45 static int __init proc_uptime_init(void)
  46 {
  47         proc_create("uptime", 0, NULL, &uptime_proc_fops);
  48         return 0;
  49 }
  50 fs_initcall(proc_uptime_init);