posix-timers: Make compat syscalls depend on CONFIG_COMPAT_32BIT_TIME

clock_gettime, clock_settime, clock_getres and clock_nanosleep
compat syscalls are also repurposed to provide backward compatibility
to support 32 bit time_t on 32 bit systems.

Note that nanosleep compat syscall will also be treated the same way
as the above syscalls as it shares common handler functions with
clock_nanosleep. But, there is no plan to provide y2038 safe solution
for nanosleep.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

kernel/time/hrtimer.c

@@ -1763,7 +1763,7 @@ SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
 	return hrtimer_nanosleep(&tu, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
 }
 
-#ifdef CONFIG_COMPAT
+#ifdef CONFIG_COMPAT_32BIT_TIME
 
 COMPAT_SYSCALL_DEFINE2(nanosleep, struct compat_timespec __user *, rqtp,
 		       struct compat_timespec __user *, rmtp)

kernel/time/posix-stubs.c

@@ -160,7 +160,9 @@ COMPAT_SYS_NI(timer_settime);
 COMPAT_SYS_NI(timer_gettime);
 COMPAT_SYS_NI(getitimer);
 COMPAT_SYS_NI(setitimer);
+#endif
 
+#ifdef CONFIG_COMPAT_32BIT_TIME
 COMPAT_SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,
 		       struct compat_timespec __user *, tp)
 {

kernel/time/posix-timers.c

@@ -1114,7 +1114,7 @@ SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
 	return error;
 }
 
-#ifdef CONFIG_COMPAT
+#ifdef CONFIG_COMPAT_32BIT_TIME
 
 COMPAT_SYSCALL_DEFINE2(clock_settime, clockid_t, which_clock,
 		       struct compat_timespec __user *, tp)
@@ -1149,6 +1149,10 @@ COMPAT_SYSCALL_DEFINE2(clock_gettime, clockid_t, which_clock,
 	return err;
 }
 
+#endif
+
+#ifdef CONFIG_COMPAT
+
 COMPAT_SYSCALL_DEFINE2(clock_adjtime, clockid_t, which_clock,
 		       struct compat_timex __user *, utp)
 {
@@ -1173,6 +1177,10 @@ COMPAT_SYSCALL_DEFINE2(clock_adjtime, clockid_t, which_clock,
 	return err;
 }
 
+#endif
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+
 COMPAT_SYSCALL_DEFINE2(clock_getres, clockid_t, which_clock,
 		       struct compat_timespec __user *, tp)
 {
@@ -1228,7 +1236,8 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
 	return kc->nsleep(which_clock, flags, &t);
 }
 
-#ifdef CONFIG_COMPAT
+#ifdef CONFIG_COMPAT_32BIT_TIME
+
 COMPAT_SYSCALL_DEFINE4(clock_nanosleep, clockid_t, which_clock, int, flags,
 		       struct compat_timespec __user *, rqtp,
 		       struct compat_timespec __user *, rmtp)
@@ -1253,6 +1262,7 @@ COMPAT_SYSCALL_DEFINE4(clock_nanosleep, clockid_t, which_clock, int, flags,
 
 	return kc->nsleep(which_clock, flags, &t);
 }
+
 #endif
 
 static const struct k_clock clock_realtime = {