[PATCH 06/19] x86/tsc: Use the full 64-bit TSC in delay_tsc()

[Borislav Petkov]

From: Andy Lutomirski <luto@xxxxxxxxxx>

As a very minor optimization, delay_tsc() was only using the low 32 bits
of the TSC. It's a delay function, so just use the whole thing.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Huang Rui <ray.huang@xxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Len Brown <lenb@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: kvm ML <kvm@xxxxxxxxxxxxxxx>
Cc: x86-ml <x86@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/bd1a277c71321b67c4794970cb5ace05efe21ab6.1434501121.git.luto@xxxxxxxxxx
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
 arch/x86/lib/delay.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c
index 9a52ad0c0758..35115f3786a9 100644
--- a/arch/x86/lib/delay.c
+++ b/arch/x86/lib/delay.c
@@ -49,16 +49,16 @@ static void delay_loop(unsigned long loops)
 /* TSC based delay: */
 static void delay_tsc(unsigned long __loops)
 {
-	u32 bclock, now, loops = __loops;
+	u64 bclock, now, loops = __loops;
 	int cpu;
 
 	preempt_disable();
 	cpu = smp_processor_id();
 	rdtsc_barrier();
-	rdtscl(bclock);
+	bclock = native_read_tsc();
 	for (;;) {
 		rdtsc_barrier();
-		rdtscl(now);
+		now = native_read_tsc();
 		if ((now - bclock) >= loops)
 			break;
 
@@ -80,7 +80,7 @@ static void delay_tsc(unsigned long __loops)
 			loops -= (now - bclock);
 			cpu = smp_processor_id();
 			rdtsc_barrier();
-			rdtscl(bclock);
+			bclock = native_read_tsc();
 		}
 	}
 	preempt_enable();
-- 
2.3.5

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