[tip: timers/vdso] vdso/gettimeofday: Validate system call existence for time() and gettimeofday()

[tip-bot2 for Thomas Weißschuh]

The following commit has been merged into the timers/vdso branch of tip:

Commit-ID:     f8b946772554ea11380fe03fc446376794a81a36
Gitweb:        https://git.kernel.org/tip/f8b946772554ea11380fe03fc446376794a81a36
Author:        Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
AuthorDate:    Thu, 02 Jul 2026 10:21:26 +02:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxx>
CommitterDate: Tue, 07 Jul 2026 23:52:53 +02:00

vdso/gettimeofday: Validate system call existence for time() and gettimeofday()

Not all architectures have the system calls for time() and
gettimeofday(). When the system call is missing, the vDSO function
should also not be present.

Validate that.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxxxxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
Link: https://patch.msgid.link/20260702-vdso-compat_32bit_time-v3-2-db9f36d8d432@xxxxxxxxxxxxx
---
 lib/vdso/gettimeofday.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index e0f289d..b8c1fc8 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -12,6 +12,8 @@
 #include <vdso/time32.h>
 #include <vdso/time64.h>
 
+#include <uapi/linux/unistd.h>
+
 /*
  * The generic vDSO implementation requires that gettimeofday.h
  * provides:
@@ -348,6 +350,10 @@ __cvdso_gettimeofday_data(const struct vdso_time_data *vd,
 {
 	const struct vdso_clock *vc = vd->clock_data;
 
+#ifndef __NR_gettimeofday
+	BUILD_BUG();
+#endif
+
 	if (likely(tv != NULL)) {
 		struct __kernel_timespec ts;
 
@@ -382,6 +388,10 @@ __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;
 
+#ifndef __NR_time
+	BUILD_BUG();
+#endif
+
 	if (vdso_is_timens_clock(vc)) {
 		vd = vdso_timens_data(vd);
 		vc = vd->clock_data;