x86: fix TSC build error on 32bit

Dave Hansen reported a build error on 32bit which went unnoticed
as newer gcc versions seem to optimize unused static functions
away before compiling them.

Make vread_tsc() depend on CONFIG_X86_64

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 3c36f92160c9..7603c0553909 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -358,6 +358,7 @@ static cycle_t read_tsc(void)
                 ret : clocksource_tsc.cycle_last;
 }
 
+#ifdef CONFIG_X86_64
 static cycle_t __vsyscall_fn vread_tsc(void)
 {
         cycle_t ret = (cycle_t)vget_cycles();
@@ -365,6 +366,7 @@ static cycle_t __vsyscall_fn vread_tsc(void)
         return ret >= __vsyscall_gtod_data.clock.cycle_last ?
                 ret : __vsyscall_gtod_data.clock.cycle_last;
 }
+#endif
 
 static struct clocksource clocksource_tsc = {
         .name                   = "tsc",