1 files changed, 13 insertions, 8 deletions

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 398cd0c7b60f..85cf317c9069 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -219,7 +219,11 @@ static u64 read_purr(void)
  */
 static u64 read_spurr(u64 purr)
 {
-        if (cpu_has_feature(CPU_FTR_SPURR))
+        /*
+         * cpus without PURR won't have a SPURR
+         * We already know the former when we use this, so tell gcc
+         */
+        if (cpu_has_feature(CPU_FTR_PURR) && cpu_has_feature(CPU_FTR_SPURR))
                 return mfspr(SPRN_SPURR);
         return purr;
 }
@@ -230,29 +234,30 @@ static u64 read_spurr(u64 purr)
  */
 void account_system_vtime(struct task_struct *tsk)
 {
-        u64 now, nowscaled, delta, deltascaled;
+        u64 now, nowscaled, delta, deltascaled, sys_time;
         unsigned long flags;
 
         local_irq_save(flags);
         now = read_purr();
-        delta = now - get_paca()->startpurr;
-        get_paca()->startpurr = now;
         nowscaled = read_spurr(now);
+        delta = now - get_paca()->startpurr;
         deltascaled = nowscaled - get_paca()->startspurr;
+        get_paca()->startpurr = now;
         get_paca()->startspurr = nowscaled;
         if (!in_interrupt()) {
                 /* deltascaled includes both user and system time.
                  * Hence scale it based on the purr ratio to estimate
                  * the system time */
+                sys_time = get_paca()->system_time;
                 if (get_paca()->user_time)
-                        deltascaled = deltascaled * get_paca()->system_time /
-                             (get_paca()->system_time + get_paca()->user_time);
-                delta += get_paca()->system_time;
+                        deltascaled = deltascaled * sys_time /
+                             (sys_time + get_paca()->user_time);
+                delta += sys_time;
                 get_paca()->system_time = 0;
         }
         account_system_time(tsk, 0, delta);
-        get_paca()->purrdelta = delta;
         account_system_time_scaled(tsk, deltascaled);
+        get_paca()->purrdelta = delta;
         get_paca()->spurrdelta = deltascaled;
         local_irq_restore(flags);
 }