x86/asm/tsc: Use the full 64-bit TSC in delay_tsc()

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 <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: kvm ML <[email protected]>
Link: http://lkml.kernel.org/r/bd1a277c71321b67c4794970cb5ace05efe21ab6.1434501121.git.luto@kernel.org
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c
index 9a52ad0c07581c256704e68ea2af3dc9712f937a..35115f3786a908e5b487b7f976c06ded5b13ab14 100644 (file)
--- 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();