[PATCH v2 1/8] selftests: vDSO: Introduce vdso_types.h

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

Currently the vDSO selftests use the time-related types from libc.
This works on glibc by chance today but will break with other libc
implementations or on distributions which switch to 64-bit times
everywhere.

The kernel's UAPI headers provide the proper types to use with the vDSO
(and raw syscalls) but are not necessarily compatible with libc types.
Introduce a new header which makes the UAPI headers compatible with the
libc.

Tested with glibc, musl and nolibc.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 tools/testing/selftests/vDSO/vdso_types.h | 75 +++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/tools/testing/selftests/vDSO/vdso_types.h b/tools/testing/selftests/vDSO/vdso_types.h
new file mode 100644
index 000000000000..4cb564f3fa94
--- /dev/null
+++ b/tools/testing/selftests/vDSO/vdso_types.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2025 Thomas Weißschuh <thomas.weissschuh@linutronix.de>, Linutronix GmbH
+ *
+ * Types to use with vDSO functions.
+ *
+ * The types used by the vDSO functions do not necessarily match the ones used
+ * by libc. The kernel's UAPI headers do provide definitions for those types
+ * but are often not compatible with libc which applications need to use.
+ * As the types differ between platforms listing them manually is a lot of work
+ * and error prone. Instead hack around the incompatibilities of the libc and
+ * UAPI headers and use the UAPI types.
+ */
+#ifndef __VDSO_TYPES_H__
+#define __VDSO_TYPES_H__
+
+/*
+ * Include the headers from libc first to not override any of its types later.
+ */
+#include <time.h>
+#include <sys/time.h>
+
+/*
+ * Avoid collisions.
+ */
+#define timeval kernel_timeval_moved
+#define itimerspec kernel_itimerspec_moved
+#define itimerval kernel_itimerval_moved
+#define timezone kernel_timezone_moved
+
+#ifndef _STRUCT_TIMESPEC
+#define _STRUCT_TIMESPEC
+#endif
+
+/*
+ * Get the UAPI types.
+ */
+#include <linux/time.h>
+
+#undef timeval
+#undef itimerspec
+#undef itimerval
+#undef timezone
+
+/*
+ * The UAPI headers do not provide their own 'struct __kernel_timezone'.
+ * 'struct timezone' is the one from libc.
+ */
+struct kernel_timezone {
+	int	tz_minuteswest;
+	int	tz_dsttime;
+};
+
+#include <linux/version.h>
+
+/*
+ * UAPI headers from the libc may be older and not provide these.
+ */
+#if KERNEL_VERSION(5, 5, 0) > LINUX_VERSION_CODE
+typedef __kernel_long_t		__kernel_old_time_t;
+
+struct __kernel_old_timespec {
+	__kernel_old_time_t	tv_sec;
+	__kernel_long_t		tv_nsec;
+};
+#endif
+
+typedef long (*vdso_gettimeofday_t)(struct __kernel_old_timeval *tv, struct kernel_timezone *tz);
+typedef long (*vdso_clock_gettime_t)(__kernel_clockid_t clk_id, struct __kernel_old_timespec *ts);
+typedef long (*vdso_clock_gettime64_t)(__kernel_clockid_t clk_id, struct __kernel_timespec *ts);
+typedef long (*vdso_clock_getres_t)(__kernel_clockid_t clk_id, struct __kernel_old_timespec *ts);
+typedef long (*vdso_clock_getres_time64_t)(__kernel_clockid_t clk_id, struct __kernel_timespec *ts);
+typedef __kernel_old_time_t (*vdso_time_t)(__kernel_old_time_t *t);
+
+#endif /* __VDSO_TYPES_H__ */

-- 
2.55.0