[PATCH v4 -next 13/15] x86: vdso: move the sysctl to arch/x86/entry/vdso/vdso32-setup.c

[Kaixiong Yu]

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 <yukaixiong at huawei.com>
Reviewed-by: Kees Cook <kees at 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))
+	register_sysctl_init("vm", vdso_table);
+#endif
 	return 0;
 }
 __initcall(ia32_binfmt_init);
 #endif /* CONFIG_SYSCTL */
 
-#endif	/* CONFIG_X86_64 */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 860dea8f1587..7ff07b7560b4 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2013,17 +2013,11 @@ static struct ctl_table kern_table[] = {
 };
 
 static struct ctl_table vm_table[] = {
-#if (defined(CONFIG_X86_32) && !defined(CONFIG_UML))|| \
-   (defined(CONFIG_SUPERH) && defined(CONFIG_VSYSCALL))
+#if defined(CONFIG_SUPERH) && defined(CONFIG_VSYSCALL)
 	{
 		.procname	= "vdso_enabled",
-#ifdef CONFIG_X86_32
-		.data		= &vdso32_enabled,
-		.maxlen		= sizeof(vdso32_enabled),
-#else
 		.data		= &vdso_enabled,
 		.maxlen		= sizeof(vdso_enabled),
-#endif
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 		.extra1		= SYSCTL_ZERO,
-- 
2.34.1