powerpc/time: Fix tracing in time.c

Since trace_clock is in a different file and already marked with notrace,
enable tracing in time.c by removing it from the disabled list in Makefile.
Also annotate clocksource read functions and sched_clock with notrace.

Testing: Timer and ftrace selftests run with different trace clocks.
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/Makefile

@@ -25,8 +25,6 @@ CFLAGS_REMOVE_cputable.o = -mno-sched-epilog $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_prom_init.o = -mno-sched-epilog $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_btext.o = -mno-sched-epilog $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_prom.o = -mno-sched-epilog $(CC_FLAGS_FTRACE)
-# timers used by tracing
-CFLAGS_REMOVE_time.o = -mno-sched-epilog $(CC_FLAGS_FTRACE)
 endif
 
 obj-y				:= cputable.o ptrace.o syscalls.o \

arch/powerpc/kernel/time.c

@@ -675,7 +675,7 @@ EXPORT_SYMBOL_GPL(tb_to_ns);
  * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
  * are 64-bit unsigned numbers.
  */
-unsigned long long sched_clock(void)
+notrace unsigned long long sched_clock(void)
 {
 	if (__USE_RTC())
 		return get_rtc();
@@ -831,12 +831,12 @@ void read_persistent_clock(struct timespec *ts)
 }
 
 /* clocksource code */
-static u64 rtc_read(struct clocksource *cs)
+static notrace u64 rtc_read(struct clocksource *cs)
 {
 	return (u64)get_rtc();
 }
 
-static u64 timebase_read(struct clocksource *cs)
+static notrace u64 timebase_read(struct clocksource *cs)
 {
 	return (u64)get_tb();
 }