When CONFIG_X86_32 is defined and CONFIG_UML is not defined,
vdso_enabled belongs to arch/x86/entry/vdso/vdso32-setup.c.
So, move it into its own file.

Before this patch, vdso_enabled was allowed to be set to
a value exceeding 1 on x86_32 architecture. After this patch is
applied, vdso_enabled is not permitted to set the value more than 1.
It does not matter, because according to the function load_vdso32(),
only vdso_enabled is set to 1, VDSO would be enabled. Other values
all mean "disabled". The same limitation could be seen in the
function vdso32_setup().

Signed-off-by: Kaixiong Yu <redacted>
Reviewed-by: Kees Cook <kees@kernel.org>
---
v4:
 - const qualify struct ctl_table vdso_table
---
---
 arch/x86/entry/vdso/vdso32-setup.c | 16 +++++++++++-----
 kernel/sysctl.c                    |  8 +-------
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/x86/entry/vdso/vdso32-setup.c b/arch/x86/entry/vdso/vdso32-setup.c
index 76e4e74f35b5..f71625f99bf9 100644
--- a/arch/x86/entry/vdso/vdso32-setup.c
+++ b/arch/x86/entry/vdso/vdso32-setup.c

@@ -51,15 +51,17 @@ __setup("vdso32=", vdso32_setup);
 __setup_param("vdso=", vdso_setup, vdso32_setup, 0);
 #endif

-#ifdef CONFIG_X86_64

 #ifdef CONFIG_SYSCTL
-/* Register vsyscall32 into the ABI table */
 #include <linux/sysctl.h>

-static struct ctl_table abi_table2[] = {
+static const struct ctl_table vdso_table[] = {
        {
+#ifdef CONFIG_X86_64
                .procname       = "vsyscall32",
+#elif (defined(CONFIG_X86_32) && !defined(CONFIG_UML))

+               .procname       = "vdso_enabled",
+#endif
                .data           = &vdso32_enabled,
                .maxlen         = sizeof(int),
                .mode           = 0644,

@@ -71,10 +73,14 @@ static struct ctl_table abi_table2[] = {

 static __init int ia32_binfmt_init(void)
 {
-       register_sysctl("abi", abi_table2);
+#ifdef CONFIG_X86_64
+       /* Register vsyscall32 into the ABI table */
+       register_sysctl("abi", vdso_table);
+#elif (defined(CONFIG_X86_32) && !defined(CONFIG_UML))