uptime.c 922 Bytes
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/fs.h>
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#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
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#include <linux/seq_file.h>
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#include <linux/time.h>
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#include <linux/kernel_stat.h>
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static int uptime_proc_show(struct seq_file *m, void *v)
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{
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	struct timespec64 uptime;
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	struct timespec64 idle;
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	u64 nsec;
	u32 rem;
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	int i;

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	nsec = 0;
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	for_each_possible_cpu(i)
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		nsec += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE];
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	ktime_get_boottime_ts64(&uptime);
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	idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
	idle.tv_nsec = rem;
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	seq_printf(m, "%lu.%02lu %lu.%02lu\n",
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			(unsigned long) uptime.tv_sec,
			(uptime.tv_nsec / (NSEC_PER_SEC / 100)),
			(unsigned long) idle.tv_sec,
			(idle.tv_nsec / (NSEC_PER_SEC / 100)));
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	return 0;
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}

static int __init proc_uptime_init(void)
{
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	proc_create_single("uptime", 0, NULL, uptime_proc_show);
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	return 0;
}
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fs_initcall(proc_uptime_init);