fs/proc/uptime.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <linux/fs.h>
0003 #include <linux/init.h>
0004 #include <linux/proc_fs.h>
0005 #include <linux/sched.h>
0006 #include <linux/seq_file.h>
0007 #include <linux/time.h>
0008 #include <linux/time_namespace.h>
0009 #include <linux/kernel_stat.h>
0010
0011 static int uptime_proc_show(struct seq_file *m, void *v)
0012 {
0013     struct timespec64 uptime;
0014     struct timespec64 idle;
0015     u64 idle_nsec;
0016     u32 rem;
0017     int i;
0018
0019     idle_nsec = 0;
0020     for_each_possible_cpu(i) {
0021         struct kernel_cpustat kcs;
0022
0023         kcpustat_cpu_fetch(&kcs, i);
0024         idle_nsec += get_idle_time(&kcs, i);
0025     }
0026
0027     ktime_get_boottime_ts64(&uptime);
0028     timens_add_boottime(&uptime);
0029
0030     idle.tv_sec = div_u64_rem(idle_nsec, NSEC_PER_SEC, &rem);
0031     idle.tv_nsec = rem;
0032     seq_printf(m, "%lu.%02lu %lu.%02lu\n",
0033             (unsigned long) uptime.tv_sec,
0034             (uptime.tv_nsec / (NSEC_PER_SEC / 100)),
0035             (unsigned long) idle.tv_sec,
0036             (idle.tv_nsec / (NSEC_PER_SEC / 100)));
0037     return 0;
0038 }
0039
0040 static int __init proc_uptime_init(void)
0041 {
0042     proc_create_single("uptime", 0, NULL, uptime_proc_show);
0043     return 0;
0044 }
0045 fs_initcall(proc_uptime_init);