time: Move time_t conversion helpers to time32.h

On 64-bit architectures, the timespec64 based helpers in linux/time.h
are defined as macros pointing to their timespec based counterparts.
This made sense when they were first introduced, but as we are migrating
away from timespec in general, it's much less intuitive now.

This changes the macros to work in the exact opposite way: we always
provide the timespec64 based helpers and define the old interfaces as
macros for them. Now we can move those macros into linux/time32.h, which
already contains the respective helpers for 32-bit architectures.

Cc: Thomas Gleixner <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Miroslav Lichvar <[e-mail]>
Cc: Richard Cochran <[e-mail]>
Cc: Prarit Bhargava <[e-mail]>
Cc: Stephen Boyd <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: John Stultz <[e-mail]>

include/linux/time32.h

···
 
 #define TIME_T_MAX	(time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1)
 
+#if __BITS_PER_LONG == 64
+
+/* timespec64 is defined as timespec here */
+static inline struct timespec timespec64_to_timespec(const struct timespec64 ts64)
+{
+	return ts64;
+}
+
+static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
+{
+	return ts;
+}
+
+# define timespec_equal			timespec64_equal
+# define timespec_compare		timespec64_compare
+# define set_normalized_timespec	set_normalized_timespec64
+# define timespec_add			timespec64_add
+# define timespec_sub			timespec64_sub
+# define timespec_valid			timespec64_valid
+# define timespec_valid_strict		timespec64_valid_strict
+# define timespec_to_ns			timespec64_to_ns
+# define ns_to_timespec			ns_to_timespec64
+# define timespec_add_ns		timespec64_add_ns
+
+#else
+static inline struct timespec timespec64_to_timespec(const struct timespec64 ts64)
+{
+	struct timespec ret;
+
+	ret.tv_sec = (time_t)ts64.tv_sec;
+	ret.tv_nsec = ts64.tv_nsec;
+	return ret;
+}
+
+static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
+{
+	struct timespec64 ret;
+
+	ret.tv_sec = ts.tv_sec;
+	ret.tv_nsec = ts.tv_nsec;
+	return ret;
+}
+
 static inline int timespec_equal(const struct timespec *a,
 				 const struct timespec *b)
 {
···
 	a->tv_sec += __iter_div_u64_rem(a->tv_nsec + ns, NSEC_PER_SEC, &ns);
 	a->tv_nsec = ns;
 }
+
+#endif
 
 /**
  * time_to_tm - converts the calendar time to local broken-down time

include/linux/time64.h

···
 typedef __s64 time64_t;
 typedef __u64 timeu64_t;
 
-/*
- * This wants to go into uapi/linux/time.h once we agreed about the
- * userspace interfaces.
- */
 #if __BITS_PER_LONG == 64
+/* this trick allows us to optimize out timespec64_to_timespec */
 # define timespec64 timespec
 #define itimerspec64 itimerspec
 #else
···
 #define TIME64_MAX			((s64)~((u64)1 << 63))
 #define KTIME_MAX			((s64)~((u64)1 << 63))
 #define KTIME_SEC_MAX			(KTIME_MAX / NSEC_PER_SEC)
-
-#if __BITS_PER_LONG == 64
-
-static inline struct timespec timespec64_to_timespec(const struct timespec64 ts64)
-{
-	return ts64;
-}
-
-static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
-{
-	return ts;
-}
-
-# define timespec64_equal		timespec_equal
-# define timespec64_compare		timespec_compare
-# define set_normalized_timespec64	set_normalized_timespec
-# define timespec64_add			timespec_add
-# define timespec64_sub			timespec_sub
-# define timespec64_valid		timespec_valid
-# define timespec64_valid_strict	timespec_valid_strict
-# define timespec64_to_ns		timespec_to_ns
-# define ns_to_timespec64		ns_to_timespec
-# define timespec64_add_ns		timespec_add_ns
-
-#else
-
-static inline struct timespec timespec64_to_timespec(const struct timespec64 ts64)
-{
-	struct timespec ret;
-
-	ret.tv_sec = (time_t)ts64.tv_sec;
-	ret.tv_nsec = ts64.tv_nsec;
-	return ret;
-}
-
-static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
-{
-	struct timespec64 ret;
-
-	ret.tv_sec = ts.tv_sec;
-	ret.tv_nsec = ts.tv_nsec;
-	return ret;
-}
 
 static inline int timespec64_equal(const struct timespec64 *a,
 				   const struct timespec64 *b)
···
 	a->tv_sec += __iter_div_u64_rem(a->tv_nsec + ns, NSEC_PER_SEC, &ns);
 	a->tv_nsec = ns;
 }
-
-#endif
 
 /*
  * timespec64_add_safe assumes both values are positive and checks for

kernel/time/time.c

···
 }
 EXPORT_SYMBOL(mktime64);
 
+#if __BITS_PER_LONG == 32
 /**
  * set_normalized_timespec - set timespec sec and nsec parts and normalize
  *
···
 	return ts;
 }
 EXPORT_SYMBOL(ns_to_timespec);
+#endif
 
 /**
  * ns_to_timeval - Convert nanoseconds to timeval
···
 }
 EXPORT_SYMBOL(ns_to_timeval);
 
-#if BITS_PER_LONG == 32
 /**
  * set_normalized_timespec - set timespec sec and nsec parts and normalize
  *
···
 	return ts;
 }
 EXPORT_SYMBOL(ns_to_timespec64);
-#endif
+
 /**
  * msecs_to_jiffies: - convert milliseconds to jiffies
  * @m:	time in milliseconds