sys/sysinfo: Respect boottime inside time namespace

The sysinfo() syscall includes uptime in seconds but has no correction for
time namespaces which makes it inconsistent with the /proc/uptime inside of
a time namespace.

Add the missing time namespace adjustment call.

Signed-off-by: Cyril Hrubis <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Reviewed-by: Dmitry Safonov <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]

kernel/sys.c

···
 #include <linux/syscalls.h>
 #include <linux/kprobes.h>
 #include <linux/user_namespace.h>
+#include <linux/time_namespace.h>
 #include <linux/binfmts.h>
 
 #include <linux/sched.h>
···
 	memset(info, 0, sizeof(struct sysinfo));
 
 	ktime_get_boottime_ts64(&tp);
+	timens_add_boottime(&tp);
 	info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
 
 	get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);