[PATCH v3 2/9] 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 <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
---
 lib/vdso/gettimeofday.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index e0f289d3d110..b8c1fc85eb74 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;

-- 
2.55.0