[PATCH 7/7] vdso/gettimeofday: Verify COMPAT_32BIT_TIME interactions

["Thomas Weißschuh" <thomas.weissschuh@linutronix.de>]

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality.

Add some build-time validations to make sure the architecture-specific
glue satisfies this requirement.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 lib/vdso/gettimeofday.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 4399e143d43a..0d134ac3dd84 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -6,6 +6,8 @@
 #include <vdso/datapage.h>
 #include <vdso/helpers.h>
 
+#include <linux/build_bug.h>
+
 /* Bring in default accessors */
 #include <vdso/vsyscall.h>
 
@@ -340,6 +342,8 @@ __cvdso_clock_gettime32_data(const struct vdso_time_data *vd, clockid_t clock,
 	struct __kernel_timespec ts;
 	bool ok;
 
+	BUILD_BUG_ON(!IS_ENABLED(CONFIG_COMPAT_32BIT_TIME));
+
 	ok = __cvdso_clock_gettime_common(vd, clock, &ts);
 
 	if (unlikely(!ok))
@@ -400,6 +404,8 @@ __cvdso_time_data(const struct vdso_time_data *vd, __kernel_old_time_t *time)
 	const struct vdso_clock *vc = vd->clock_data;
 	__kernel_old_time_t t;
 
+	BUILD_BUG_ON(sizeof(*time) != 8 && !IS_ENABLED(CONFIG_COMPAT_32BIT_TIME));
+
 	if (IS_ENABLED(CONFIG_TIME_NS) &&
 	    vc->clock_mode == VDSO_CLOCKMODE_TIMENS) {
 		vd = __arch_get_vdso_u_timens_data(vd);
@@ -491,6 +497,8 @@ __cvdso_clock_getres_time32_data(const struct vdso_time_data *vd, clockid_t cloc
 	struct __kernel_timespec ts;
 	bool ok;
 
+	BUILD_BUG_ON(!IS_ENABLED(CONFIG_COMPAT_32BIT_TIME));
+
 	ok = __cvdso_clock_getres_common(vd, clock, &ts);
 
 	if (unlikely(!ok))

-- 
2.53.0