kernel/kexec_core: move kexec_core sysctls into its own file

This move the kernel/kexec_core.c respective sysctls to its own file.

kernel/sysctl.c has grown to an insane mess, We move sysctls to places
where features actually belong to improve the readability and reduce
merge conflicts. At the same time, the proc-sysctl maintainers can easily
care about the core logic other than the sysctl knobs added for some feature.

We already moved all filesystem sysctls out. This patch is part of the effort
to move kexec related sysctls out.

Signed-off-by: yingelin <yingelin@huawei.com>
Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

kernel/kexec_core.c

@@ -936,6 +936,28 @@ int kimage_load_segment(struct kimage *image,
 struct kimage *kexec_image;
 struct kimage *kexec_crash_image;
 int kexec_load_disabled;
+#ifdef CONFIG_SYSCTL
+static struct ctl_table kexec_core_sysctls[] = {
+	{
+		.procname	= "kexec_load_disabled",
+		.data		= &kexec_load_disabled,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		/* only handle a transition from default "0" to "1" */
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_ONE,
+	},
+	{ }
+};
+
+static int __init kexec_core_sysctl_init(void)
+{
+	register_sysctl_init("kernel", kexec_core_sysctls);
+	return 0;
+}
+late_initcall(kexec_core_sysctl_init);
+#endif
 
 /*
  * No panic_cpu check version of crash_kexec().  This function is called

kernel/sysctl.c

@@ -61,7 +61,6 @@
 #include <linux/capability.h>
 #include <linux/binfmts.h>
 #include <linux/sched/sysctl.h>
-#include <linux/kexec.h>
 #include <linux/mount.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/pid.h>
@@ -1712,18 +1711,6 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= tracepoint_printk_sysctl,
 	},
 #endif
-#ifdef CONFIG_KEXEC_CORE
-	{
-		.procname	= "kexec_load_disabled",
-		.data		= &kexec_load_disabled,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		/* only handle a transition from default "0" to "1" */
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ONE,
-		.extra2		= SYSCTL_ONE,
-	},
-#endif
 #ifdef CONFIG_MODULES
 	{
 		.procname	= "modprobe",