y2038: Provide aliases for compat helpers

As part of the system call rework for 64-bit time_t, we are restructuring
the way that compat syscalls deal with 32-bit time_t, reusing the
implementation for 32-bit architectures. Christoph Hellwig suggested a
rename of the associated types and interfaces to avoid the confusing usage
of the 'compat' prefix for 32-bit architectures.

To prepare for doing that in linux-4.20, add a set of macros that allows to
convert subsystems separately to the new names and avoids some of the
nastier merge conflicts.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: y2038@lists.linaro.org
Cc: John Stultz <john.stultz@linaro.org>
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Link: https://lkml.kernel.org/r/20180821203329.2089473-1-arnd@arndb.de

include/linux/time32.h

@@ -207,4 +207,19 @@ static inline s64 timeval_to_ns(const struct timeval *tv)
 extern struct timeval ns_to_timeval(const s64 nsec);
 extern struct __kernel_old_timeval ns_to_kernel_old_timeval(s64 nsec);
 
+/*
+ * New aliases for compat time functions. These will be used to replace
+ * the compat code so it can be shared between 32-bit and 64-bit builds
+ * both of which provide compatibility with old 32-bit tasks.
+ */
+#define old_time32_t		compat_time_t
+#define old_timeval32		compat_timeval
+#define old_timespec32		compat_timespec
+#define old_itimerspec32	compat_itimerspec
+#define ns_to_old_timeval32	ns_to_compat_timeval
+#define get_old_itimerspec32	get_compat_itimerspec64
+#define put_old_itimerspec32	put_compat_itimerspec64
+#define get_old_timespec32	compat_get_timespec64
+#define put_old_timespec32	compat_put_timespec64
+
 #endif