[POWERPC] Timer interrupt: use a struct for two per_cpu varables

timer_interrupt() was calculating per_cpu_offset several times, having to
start from the toc because of potential aliasing issues.

Placing both decrementer per_cpu varables in a struct and calculating
the address once with __get_cpu_var results in better code on both 32
and 64 bit.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 12 insertions, 8 deletions

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 888c65726ebd..5cf394080590 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -116,8 +116,12 @@ static struct clock_event_device decrementer_clockevent = {
        .features       = CLOCK_EVT_FEAT_ONESHOT,
 };
 
-static DEFINE_PER_CPU(struct clock_event_device, decrementers);
-static DEFINE_PER_CPU(u64, decrementer_next_tb);
+struct decrementer_clock {
+        struct clock_event_device event;
+        u64 next_tb;
+};
+
+static DEFINE_PER_CPU(struct decrementer_clock, decrementers);
 
 #ifdef CONFIG_PPC_ISERIES
 static unsigned long __initdata iSeries_recal_titan;
@@ -555,8 +559,8 @@ void __init iSeries_time_init_early(void)
 void timer_interrupt(struct pt_regs * regs)
 {
         struct pt_regs *old_regs;
-        int cpu = smp_processor_id();
-        struct clock_event_device *evt = &per_cpu(decrementers, cpu);
+        struct decrementer_clock *decrementer =  &__get_cpu_var(decrementers);
+        struct clock_event_device *evt = &decrementer->event;
         u64 now;
 
         /* Ensure a positive value is written to the decrementer, or else
@@ -569,9 +573,9 @@ void timer_interrupt(struct pt_regs * regs)
 #endif
 
         now = get_tb_or_rtc();
-        if (now < per_cpu(decrementer_next_tb, cpu)) {
+        if (now < decrementer->next_tb) {
                 /* not time for this event yet */
-                now = per_cpu(decrementer_next_tb, cpu) - now;
+                now = decrementer->next_tb - now;
                 if (now <= DECREMENTER_MAX)
                         set_dec((int)now);
                 return;
@@ -810,7 +814,7 @@ void __init clocksource_init(void)
 static int decrementer_set_next_event(unsigned long evt,
                                       struct clock_event_device *dev)
 {
-        __get_cpu_var(decrementer_next_tb) = get_tb_or_rtc() + evt;
+        __get_cpu_var(decrementers).next_tb = get_tb_or_rtc() + evt;
         set_dec(evt);
         return 0;
 }
@@ -824,7 +828,7 @@ static void decrementer_set_mode(enum clock_event_mode mode,
 
 static void register_decrementer_clockevent(int cpu)
 {
-        struct clock_event_device *dec = &per_cpu(decrementers, cpu);
+        struct clock_event_device *dec = &per_cpu(decrementers, cpu).event;
 
         *dec = decrementer_clockevent;
         dec->cpumask = cpumask_of_cpu(cpu);