[S390] cputime: add sparse checking and cleanup

Make cputime_t and cputime64_t nocast to enable sparse checking to
detect incorrect use of cputime. Drop the cputime macros for simple
scalar operations. The conversion macros are still needed.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

23 files changed, 323 insertions, 429 deletions

diff --git a/arch/ia64/include/asm/cputime.h b/arch/ia64/include/asm/cputime.h
index 6073b187528a..461e52f0277f 100644
--- a/arch/ia64/include/asm/cputime.h
+++ b/arch/ia64/include/asm/cputime.h
@@ -26,59 +26,51 @@
 #include <linux/jiffies.h>
 #include <asm/processor.h>
 
-typedef u64 cputime_t;
-typedef u64 cputime64_t;
+typedef u64 __nocast cputime_t;
+typedef u64 __nocast cputime64_t;
 
-#define cputime_zero			((cputime_t)0)
 #define cputime_one_jiffy		jiffies_to_cputime(1)
-#define cputime_max			((~((cputime_t)0) >> 1) - 1)
-#define cputime_add(__a, __b)		((__a) +  (__b))
-#define cputime_sub(__a, __b)		((__a) -  (__b))
-#define cputime_div(__a, __n)		((__a) /  (__n))
-#define cputime_halve(__a)		((__a) >> 1)
-#define cputime_eq(__a, __b)		((__a) == (__b))
-#define cputime_gt(__a, __b)		((__a) >  (__b))
-#define cputime_ge(__a, __b)		((__a) >= (__b))
-#define cputime_lt(__a, __b)		((__a) <  (__b))
-#define cputime_le(__a, __b)		((__a) <= (__b))
-
-#define cputime64_zero			((cputime64_t)0)
-#define cputime64_add(__a, __b)		((__a) + (__b))
-#define cputime64_sub(__a, __b)		((__a) - (__b))
-#define cputime_to_cputime64(__ct)	(__ct)
 
 /*
  * Convert cputime <-> jiffies (HZ)
  */
-#define cputime_to_jiffies(__ct)	((__ct) / (NSEC_PER_SEC / HZ))
-#define jiffies_to_cputime(__jif)	((__jif) * (NSEC_PER_SEC / HZ))
-#define cputime64_to_jiffies64(__ct)	((__ct) / (NSEC_PER_SEC / HZ))
-#define jiffies64_to_cputime64(__jif)	((__jif) * (NSEC_PER_SEC / HZ))
+#define cputime_to_jiffies(__ct)	\
+	((__force u64)(__ct) / (NSEC_PER_SEC / HZ))
+#define jiffies_to_cputime(__jif)	\
+	(__force cputime_t)((__jif) * (NSEC_PER_SEC / HZ))
+#define cputime64_to_jiffies64(__ct)	\
+	((__force u64)(__ct) / (NSEC_PER_SEC / HZ))
+#define jiffies64_to_cputime64(__jif)	\
+	(__force cputime64_t)((__jif) * (NSEC_PER_SEC / HZ))
 
 /*
  * Convert cputime <-> microseconds
  */
-#define cputime_to_usecs(__ct)		((__ct) / NSEC_PER_USEC)
-#define usecs_to_cputime(__usecs)	((__usecs) * NSEC_PER_USEC)
+#define cputime_to_usecs(__ct)		\
+	((__force u64)(__ct) / NSEC_PER_USEC)
+#define usecs_to_cputime(__usecs)	\
+	(__force cputime_t)((__usecs) * NSEC_PER_USEC)
 
 /*
  * Convert cputime <-> seconds
  */
-#define cputime_to_secs(__ct)		((__ct) / NSEC_PER_SEC)
-#define secs_to_cputime(__secs)		((__secs) * NSEC_PER_SEC)
+#define cputime_to_secs(__ct)		\
+	((__force u64)(__ct) / NSEC_PER_SEC)
+#define secs_to_cputime(__secs)		\
+	(__force cputime_t)((__secs) * NSEC_PER_SEC)
 
 /*
  * Convert cputime <-> timespec (nsec)
  */
 static inline cputime_t timespec_to_cputime(const struct timespec *val)
 {
-	cputime_t ret = val->tv_sec * NSEC_PER_SEC;
-	return (ret + val->tv_nsec);
+	u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_nsec;
+	return (__force cputime_t) ret;
 }
 static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
 {
-	val->tv_sec  = ct / NSEC_PER_SEC;
-	val->tv_nsec = ct % NSEC_PER_SEC;
+	val->tv_sec  = (__force u64) ct / NSEC_PER_SEC;
+	val->tv_nsec = (__force u64) ct % NSEC_PER_SEC;
 }
 
 /*
@@ -86,25 +78,28 @@ static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
  */
 static inline cputime_t timeval_to_cputime(struct timeval *val)
 {
-	cputime_t ret = val->tv_sec * NSEC_PER_SEC;
-	return (ret + val->tv_usec * NSEC_PER_USEC);
+	u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_usec * NSEC_PER_USEC;
+	return (__force cputime_t) ret;
 }
 static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
 {
-	val->tv_sec = ct / NSEC_PER_SEC;
-	val->tv_usec = (ct % NSEC_PER_SEC) / NSEC_PER_USEC;
+	val->tv_sec = (__force u64) ct / NSEC_PER_SEC;
+	val->tv_usec = ((__force u64) ct % NSEC_PER_SEC) / NSEC_PER_USEC;
 }
 
 /*
  * Convert cputime <-> clock (USER_HZ)
  */
-#define cputime_to_clock_t(__ct)	((__ct) / (NSEC_PER_SEC / USER_HZ))
-#define clock_t_to_cputime(__x)		((__x) * (NSEC_PER_SEC / USER_HZ))
+#define cputime_to_clock_t(__ct)	\
+	((__force u64)(__ct) / (NSEC_PER_SEC / USER_HZ))
+#define clock_t_to_cputime(__x)		\
+	(__force cputime_t)((__x) * (NSEC_PER_SEC / USER_HZ))
 
 /*
  * Convert cputime64 to clock.
  */
-#define cputime64_to_clock_t(__ct)      cputime_to_clock_t((cputime_t)__ct)
+#define cputime64_to_clock_t(__ct)	\
+	cputime_to_clock_t((__force cputime_t)__ct)
 
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 #endif /* __IA64_CPUTIME_H */
diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index 1cf20bdfbeca..e94935c52019 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -29,25 +29,8 @@ static inline void setup_cputime_one_jiffy(void) { }
 #include <asm/time.h>
 #include <asm/param.h>
 
-typedef u64 cputime_t;
-typedef u64 cputime64_t;
-
-#define cputime_zero			((cputime_t)0)
-#define cputime_max			((~((cputime_t)0) >> 1) - 1)
-#define cputime_add(__a, __b)		((__a) +  (__b))
-#define cputime_sub(__a, __b)		((__a) -  (__b))
-#define cputime_div(__a, __n)		((__a) /  (__n))
-#define cputime_halve(__a)		((__a) >> 1)
-#define cputime_eq(__a, __b)		((__a) == (__b))
-#define cputime_gt(__a, __b)		((__a) >  (__b))
-#define cputime_ge(__a, __b)		((__a) >= (__b))
-#define cputime_lt(__a, __b)		((__a) <  (__b))
-#define cputime_le(__a, __b)		((__a) <= (__b))
-
-#define cputime64_zero			((cputime64_t)0)
-#define cputime64_add(__a, __b)		((__a) + (__b))
-#define cputime64_sub(__a, __b)		((__a) - (__b))
-#define cputime_to_cputime64(__ct)	(__ct)
+typedef u64 __nocast cputime_t;
+typedef u64 __nocast cputime64_t;
 
 #ifdef __KERNEL__
 
@@ -65,7 +48,7 @@ DECLARE_PER_CPU(unsigned long, cputime_scaled_last_delta);
 
 static inline unsigned long cputime_to_jiffies(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_jiffies_factor);
+	return mulhdu((__force u64) ct, __cputime_jiffies_factor);
 }
 
 /* Estimate the scaled cputime by scaling the real cputime based on
@@ -74,14 +57,15 @@ static inline cputime_t cputime_to_scaled(const cputime_t ct)
 {
 	if (cpu_has_feature(CPU_FTR_SPURR) &&
 	    __get_cpu_var(cputime_last_delta))
-		return ct * __get_cpu_var(cputime_scaled_last_delta) /
-			    __get_cpu_var(cputime_last_delta);
+		return (__force u64) ct *
+			__get_cpu_var(cputime_scaled_last_delta) /
+			__get_cpu_var(cputime_last_delta);
 	return ct;
 }
 
 static inline cputime_t jiffies_to_cputime(const unsigned long jif)
 {
-	cputime_t ct;
+	u64 ct;
 	unsigned long sec;
 
 	/* have to be a little careful about overflow */
@@ -93,7 +77,7 @@ static inline cputime_t jiffies_to_cputime(const unsigned long jif)
 	}
 	if (sec)
 		ct += (cputime_t) sec * tb_ticks_per_sec;
-	return ct;
+	return (__force cputime_t) ct;
 }
 
 static inline void setup_cputime_one_jiffy(void)
@@ -103,7 +87,7 @@ static inline void setup_cputime_one_jiffy(void)
 
 static inline cputime64_t jiffies64_to_cputime64(const u64 jif)
 {
-	cputime_t ct;
+	u64 ct;
 	u64 sec;
 
 	/* have to be a little careful about overflow */
@@ -114,13 +98,13 @@ static inline cputime64_t jiffies64_to_cputime64(const u64 jif)
 		do_div(ct, HZ);
 	}
 	if (sec)
-		ct += (cputime_t) sec * tb_ticks_per_sec;
-	return ct;
+		ct += (u64) sec * tb_ticks_per_sec;
+	return (__force cputime64_t) ct;
 }
 
 static inline u64 cputime64_to_jiffies64(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_jiffies_factor);
+	return mulhdu((__force u64) ct, __cputime_jiffies_factor);
 }
 
 /*
@@ -130,12 +114,12 @@ extern u64 __cputime_msec_factor;
 
 static inline unsigned long cputime_to_usecs(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_msec_factor) * USEC_PER_MSEC;
+	return mulhdu((__force u64) ct, __cputime_msec_factor) * USEC_PER_MSEC;
 }
 
 static inline cputime_t usecs_to_cputime(const unsigned long us)
 {
-	cputime_t ct;
+	u64 ct;
 	unsigned long sec;
 
 	/* have to be a little careful about overflow */
@@ -147,7 +131,7 @@ static inline cputime_t usecs_to_cputime(const unsigned long us)
 	}
 	if (sec)
 		ct += (cputime_t) sec * tb_ticks_per_sec;
-	return ct;
+	return (__force cputime_t) ct;
 }
 
 /*
@@ -157,12 +141,12 @@ extern u64 __cputime_sec_factor;
 
 static inline unsigned long cputime_to_secs(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_sec_factor);
+	return mulhdu((__force u64) ct, __cputime_sec_factor);
 }
 
 static inline cputime_t secs_to_cputime(const unsigned long sec)
 {
-	return (cputime_t) sec * tb_ticks_per_sec;
+	return (__force cputime_t)((u64) sec * tb_ticks_per_sec);
 }
 
 /*
@@ -170,7 +154,7 @@ static inline cputime_t secs_to_cputime(const unsigned long sec)
  */
 static inline void cputime_to_timespec(const cputime_t ct, struct timespec *p)
 {
-	u64 x = ct;
+	u64 x = (__force u64) ct;
 	unsigned int frac;
 
 	frac = do_div(x, tb_ticks_per_sec);
@@ -182,11 +166,11 @@ static inline void cputime_to_timespec(const cputime_t ct, struct timespec *p)
 
 static inline cputime_t timespec_to_cputime(const struct timespec *p)
 {
-	cputime_t ct;
+	u64 ct;
 
 	ct = (u64) p->tv_nsec * tb_ticks_per_sec;
 	do_div(ct, 1000000000);
-	return ct + (u64) p->tv_sec * tb_ticks_per_sec;
+	return (__force cputime_t)(ct + (u64) p->tv_sec * tb_ticks_per_sec);
 }
 
 /*
@@ -194,7 +178,7 @@ static inline cputime_t timespec_to_cputime(const struct timespec *p)
  */
 static inline void cputime_to_timeval(const cputime_t ct, struct timeval *p)
 {
-	u64 x = ct;
+	u64 x = (__force u64) ct;
 	unsigned int frac;
 
 	frac = do_div(x, tb_ticks_per_sec);
@@ -206,11 +190,11 @@ static inline void cputime_to_timeval(const cputime_t ct, struct timeval *p)
 
 static inline cputime_t timeval_to_cputime(const struct timeval *p)
 {
-	cputime_t ct;
+	u64 ct;
 
 	ct = (u64) p->tv_usec * tb_ticks_per_sec;
 	do_div(ct, 1000000);
-	return ct + (u64) p->tv_sec * tb_ticks_per_sec;
+	return (__force cputime_t)(ct + (u64) p->tv_sec * tb_ticks_per_sec);
 }
 
 /*
@@ -220,12 +204,12 @@ extern u64 __cputime_clockt_factor;
 
 static inline unsigned long cputime_to_clock_t(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_clockt_factor);
+	return mulhdu((__force u64) ct, __cputime_clockt_factor);
 }
 
 static inline cputime_t clock_t_to_cputime(const unsigned long clk)
 {
-	cputime_t ct;
+	u64 ct;
 	unsigned long sec;
 
 	/* have to be a little careful about overflow */
@@ -236,8 +220,8 @@ static inline cputime_t clock_t_to_cputime(const unsigned long clk)
 		do_div(ct, USER_HZ);
 	}
 	if (sec)
-		ct += (cputime_t) sec * tb_ticks_per_sec;
-	return ct;
+		ct += (u64) sec * tb_ticks_per_sec;
+	return (__force cputime_t) ct;
 }
 
 #define cputime64_to_clock_t(ct)	cputime_to_clock_t((cputime_t)(ct))
diff --git a/arch/s390/include/asm/cputime.h b/arch/s390/include/asm/cputime.h
index 081434878296..0887a0463e33 100644
--- a/arch/s390/include/asm/cputime.h
+++ b/arch/s390/include/asm/cputime.h
@@ -16,114 +16,98 @@
 
 /* We want to use full resolution of the CPU timer: 2**-12 micro-seconds. */
 
-typedef unsigned long long cputime_t;
-typedef unsigned long long cputime64_t;
+typedef unsigned long long __nocast cputime_t;
+typedef unsigned long long __nocast cputime64_t;
 
-#ifndef __s390x__
-
-static inline unsigned int
-__div(unsigned long long n, unsigned int base)
+static inline unsigned long __div(unsigned long long n, unsigned long base)
 {
+#ifndef __s390x__
 	register_pair rp;
 
 	rp.pair = n >> 1;
 	asm ("dr %0,%1" : "+d" (rp) : "d" (base >> 1));
 	return rp.subreg.odd;
+#else /* __s390x__ */
+	return n / base;
+#endif /* __s390x__ */
 }
 
-#else /* __s390x__ */
+#define cputime_one_jiffy		jiffies_to_cputime(1)
 
-static inline unsigned int
-__div(unsigned long long n, unsigned int base)
+/*
+ * Convert cputime to jiffies and back.
+ */
+static inline unsigned long cputime_to_jiffies(const cputime_t cputime)
 {
-	return n / base;
+	return __div((__force unsigned long long) cputime, 4096000000ULL / HZ);
 }
 
-#endif /* __s390x__ */
+static inline cputime_t jiffies_to_cputime(const unsigned int jif)
+{
+	return (__force cputime_t)(jif * (4096000000ULL / HZ));
+}
 
-#define cputime_zero			(0ULL)
-#define cputime_one_jiffy		jiffies_to_cputime(1)
-#define cputime_max			((~0UL >> 1) - 1)
-#define cputime_add(__a, __b)		((__a) +  (__b))
-#define cputime_sub(__a, __b)		((__a) -  (__b))
-#define cputime_div(__a, __n) ({		\
-	unsigned long long __div = (__a);	\
-	do_div(__div,__n);			\
-	__div;					\
-})
-#define cputime_halve(__a)		((__a) >> 1)
-#define cputime_eq(__a, __b)		((__a) == (__b))
-#define cputime_gt(__a, __b)		((__a) >  (__b))
-#define cputime_ge(__a, __b)		((__a) >= (__b))
-#define cputime_lt(__a, __b)		((__a) <  (__b))
-#define cputime_le(__a, __b)		((__a) <= (__b))
-#define cputime_to_jiffies(__ct)	(__div((__ct), 4096000000ULL / HZ))
-#define cputime_to_scaled(__ct)		(__ct)
-#define jiffies_to_cputime(__hz)	((cputime_t)(__hz) * (4096000000ULL / HZ))
-
-#define cputime64_zero			(0ULL)
-#define cputime64_add(__a, __b)		((__a) + (__b))
-#define cputime_to_cputime64(__ct)	(__ct)
-
-static inline u64
-cputime64_to_jiffies64(cputime64_t cputime)
-{
-	do_div(cputime, 4096000000ULL / HZ);
-	return cputime;
+static inline u64 cputime64_to_jiffies64(cputime64_t cputime)
+{
+	unsigned long long jif = (__force unsigned long long) cputime;
+	do_div(jif, 4096000000ULL / HZ);
+	return jif;
+}
+
+static inline cputime64_t jiffies64_to_cputime64(const u64 jif)
+{
+	return (__force cputime64_t)(jif * (4096000000ULL / HZ));
 }
 
 /*
  * Convert cputime to microseconds and back.
  */
-static inline unsigned int
-cputime_to_usecs(const cputime_t cputime)
+static inline unsigned int cputime_to_usecs(const cputime_t cputime)
 {
-	return cputime_div(cputime, 4096);
+	return (__force unsigned long long) cputime >> 12;
 }
 
-static inline cputime_t
-usecs_to_cputime(const unsigned int m)
+static inline cputime_t usecs_to_cputime(const unsigned int m)
 {
-	return (cputime_t) m * 4096;
+	return (__force cputime_t)(m * 4096ULL);
 }
 
 /*
  * Convert cputime to milliseconds and back.
  */
-static inline unsigned int
-cputime_to_secs(const cputime_t cputime)
+static inline unsigned int cputime_to_secs(const cputime_t cputime)
 {
-	return __div(cputime, 2048000000) >> 1;
+	return __div((__force unsigned long long) cputime, 2048000000) >> 1;
 }
 
-static inline cputime_t
-secs_to_cputime(const unsigned int s)
+static inline cputime_t secs_to_cputime(const unsigned int s)
 {
-	return (cputime_t) s * 4096000000ULL;
+	return (__force cputime_t)(s * 4096000000ULL);
 }
 
 /*
  * Convert cputime to timespec and back.
  */
-static inline cputime_t
-timespec_to_cputime(const struct timespec *value)
+static inline cputime_t timespec_to_cputime(const struct timespec *value)
 {
-	return value->tv_nsec * 4096 / 1000 + (u64) value->tv_sec * 4096000000ULL;
+	unsigned long long ret = value->tv_sec * 4096000000ULL;
+	return (__force cputime_t)(ret + value->tv_nsec * 4096 / 1000);
 }
 
-static inline void
-cputime_to_timespec(const cputime_t cputime, struct timespec *value)
+static inline void cputime_to_timespec(const cputime_t cputime,
+				       struct timespec *value)
 {
+	unsigned long long __cputime = (__force unsigned long long) cputime;
 #ifndef __s390x__
 	register_pair rp;
 
-	rp.pair = cputime >> 1;
+	rp.pair = __cputime >> 1;
 	asm ("dr %0,%1" : "+d" (rp) : "d" (2048000000UL));
 	value->tv_nsec = rp.subreg.even * 1000 / 4096;
 	value->tv_sec = rp.subreg.odd;
 #else
-	value->tv_nsec = (cputime % 4096000000ULL) * 1000 / 4096;
-	value->tv_sec = cputime / 4096000000ULL;
+	value->tv_nsec = (__cputime % 4096000000ULL) * 1000 / 4096;
+	value->tv_sec = __cputime / 4096000000ULL;
 #endif
 }
 
@@ -132,50 +116,52 @@ cputime_to_timespec(const cputime_t cputime, struct timespec *value)
  * Since cputime and timeval have the same resolution (microseconds)
  * this is easy.
  */
-static inline cputime_t
-timeval_to_cputime(const struct timeval *value)
+static inline cputime_t timeval_to_cputime(const struct timeval *value)
 {
-	return value->tv_usec * 4096 + (u64) value->tv_sec * 4096000000ULL;
+	unsigned long long ret = value->tv_sec * 4096000000ULL;
+	return (__force cputime_t)(ret + value->tv_usec * 4096ULL);
 }
 
-static inline void
-cputime_to_timeval(const cputime_t cputime, struct timeval *value)
+static inline void cputime_to_timeval(const cputime_t cputime,
+				      struct timeval *value)
 {
+	unsigned long long __cputime = (__force unsigned long long) cputime;
 #ifndef __s390x__
 	register_pair rp;
 
-	rp.pair = cputime >> 1;
+	rp.pair = __cputime >> 1;
 	asm ("dr %0,%1" : "+d" (rp) : "d" (2048000000UL));
 	value->tv_usec = rp.subreg.even / 4096;
 	value->tv_sec = rp.subreg.odd;
 #else
-	value->tv_usec = (cputime % 4096000000ULL) / 4096;
-	value->tv_sec = cputime / 4096000000ULL;
+	value->tv_usec = (__cputime % 4096000000ULL) / 4096;
+	value->tv_sec = __cputime / 4096000000ULL;
 #endif
 }
 
 /*
  * Convert cputime to clock and back.
  */
-static inline clock_t
-cputime_to_clock_t(cputime_t cputime)
+static inline clock_t cputime_to_clock_t(cputime_t cputime)
 {
-	return cputime_div(cputime, 4096000000ULL / USER_HZ);
+	unsigned long long clock = (__force unsigned long long) cputime;
+	do_div(clock, 4096000000ULL / USER_HZ);
+	return clock;
 }
 
-static inline cputime_t
-clock_t_to_cputime(unsigned long x)
+static inline cputime_t clock_t_to_cputime(unsigned long x)
 {
-	return (cputime_t) x * (4096000000ULL / USER_HZ);
+	return (__force cputime_t)(x * (4096000000ULL / USER_HZ));
 }
 
 /*
  * Convert cputime64 to clock.
  */
-static inline clock_t
-cputime64_to_clock_t(cputime64_t cputime)
+static inline clock_t cputime64_to_clock_t(cputime64_t cputime)
 {
-       return cputime_div(cputime, 4096000000ULL / USER_HZ);
+	unsigned long long clock = (__force unsigned long long) cputime;
+	do_div(clock, 4096000000ULL / USER_HZ);
+	return clock;
 }
 
 struct s390_idle_data {
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index c97b468ee9f7..7f31a031c0b5 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -103,15 +103,14 @@ static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
 	cputime64_t busy_time;
 
 	cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
-	busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
-			kstat_cpu(cpu).cpustat.system);
-
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
-
-	idle_time = cputime64_sub(cur_wall_time, busy_time);
+	busy_time  = kstat_cpu(cpu).cpustat.user;
+	busy_time += kstat_cpu(cpu).cpustat.system;
+	busy_time += kstat_cpu(cpu).cpustat.irq;
+	busy_time += kstat_cpu(cpu).cpustat.softirq;
+	busy_time += kstat_cpu(cpu).cpustat.steal;
+	busy_time += kstat_cpu(cpu).cpustat.nice;
+
+	idle_time = cur_wall_time - busy_time;
 	if (wall)
 		*wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
 
@@ -353,20 +352,20 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 
 		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 
-		wall_time = (unsigned int) cputime64_sub(cur_wall_time,
-				j_dbs_info->prev_cpu_wall);
+		wall_time = (unsigned int)
+			(cur_wall_time - j_dbs_info->prev_cpu_wall);
 		j_dbs_info->prev_cpu_wall = cur_wall_time;
 
-		idle_time = (unsigned int) cputime64_sub(cur_idle_time,
-				j_dbs_info->prev_cpu_idle);
+		idle_time = (unsigned int)
+			(cur_idle_time - j_dbs_info->prev_cpu_idle);
 		j_dbs_info->prev_cpu_idle = cur_idle_time;
 
 		if (dbs_tuners_ins.ignore_nice) {
 			cputime64_t cur_nice;
 			unsigned long cur_nice_jiffies;
 
-			cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
-					 j_dbs_info->prev_cpu_nice);
+			cur_nice = kstat_cpu(j).cpustat.nice -
+					j_dbs_info->prev_cpu_nice;
 			/*
 			 * Assumption: nice time between sampling periods will
 			 * be less than 2^32 jiffies for 32 bit sys
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index fa8af4ebb1d6..07cffe2f6cff 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -127,15 +127,14 @@ static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
 	cputime64_t busy_time;
 
 	cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
-	busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
-			kstat_cpu(cpu).cpustat.system);
-
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
-
-	idle_time = cputime64_sub(cur_wall_time, busy_time);
+	busy_time  = kstat_cpu(cpu).cpustat.user;
+	busy_time += kstat_cpu(cpu).cpustat.system;
+	busy_time += kstat_cpu(cpu).cpustat.irq;
+	busy_time += kstat_cpu(cpu).cpustat.softirq;
+	busy_time += kstat_cpu(cpu).cpustat.steal;
+	busy_time += kstat_cpu(cpu).cpustat.nice;
+
+	idle_time = cur_wall_time - busy_time;
 	if (wall)
 		*wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
 
@@ -442,24 +441,24 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 		cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
 
-		wall_time = (unsigned int) cputime64_sub(cur_wall_time,
-				j_dbs_info->prev_cpu_wall);
+		wall_time = (unsigned int)
+			(cur_wall_time - j_dbs_info->prev_cpu_wall);
 		j_dbs_info->prev_cpu_wall = cur_wall_time;
 
-		idle_time = (unsigned int) cputime64_sub(cur_idle_time,
-				j_dbs_info->prev_cpu_idle);
+		idle_time = (unsigned int)
+			(cur_idle_time - j_dbs_info->prev_cpu_idle);
 		j_dbs_info->prev_cpu_idle = cur_idle_time;
 
-		iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
-				j_dbs_info->prev_cpu_iowait);
+		iowait_time = (unsigned int)
+			(cur_iowait_time - j_dbs_info->prev_cpu_iowait);
 		j_dbs_info->prev_cpu_iowait = cur_iowait_time;
 
 		if (dbs_tuners_ins.ignore_nice) {
 			cputime64_t cur_nice;
 			unsigned long cur_nice_jiffies;
 
-			cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
-					 j_dbs_info->prev_cpu_nice);
+			cur_nice = kstat_cpu(j).cpustat.nice -
+					j_dbs_info->prev_cpu_nice;
 			/*
 			 * Assumption: nice time between sampling periods will
 			 * be less than 2^32 jiffies for 32 bit sys
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index c5072a91e848..2a508edd768b 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -61,9 +61,8 @@ static int cpufreq_stats_update(unsigned int cpu)
 	spin_lock(&cpufreq_stats_lock);
 	stat = per_cpu(cpufreq_stats_table, cpu);
 	if (stat->time_in_state)
-		stat->time_in_state[stat->last_index] =
-			cputime64_add(stat->time_in_state[stat->last_index],
-				      cputime_sub(cur_time, stat->last_time));
+		stat->time_in_state[stat->last_index] +=
+			cur_time - stat->last_time;
 	stat->last_time = cur_time;
 	spin_unlock(&cpufreq_stats_lock);
 	return 0;
diff --git a/drivers/macintosh/rack-meter.c b/drivers/macintosh/rack-meter.c
index 2637c139777b..909908ebf164 100644
--- a/drivers/macintosh/rack-meter.c
+++ b/drivers/macintosh/rack-meter.c
@@ -83,11 +83,10 @@ static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
 {
 	cputime64_t retval;
 
-	retval = cputime64_add(kstat_cpu(cpu).cpustat.idle,
-			kstat_cpu(cpu).cpustat.iowait);
+	retval = kstat_cpu(cpu).cpustat.idle + kstat_cpu(cpu).cpustat.iowait;
 
 	if (rackmeter_ignore_nice)
-		retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice);
+		retval += kstat_cpu(cpu).cpustat.nice;
 
 	return retval;
 }
@@ -220,13 +219,11 @@ static void rackmeter_do_timer(struct work_struct *work)
 	int i, offset, load, cumm, pause;
 
 	cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
-	total_ticks = (unsigned int)cputime64_sub(cur_jiffies,
-						  rcpu->prev_wall);
+	total_ticks = (unsigned int) (cur_jiffies - rcpu->prev_wall);
 	rcpu->prev_wall = cur_jiffies;
 
 	total_idle_ticks = get_cpu_idle_time(cpu);
-	idle_ticks = (unsigned int) cputime64_sub(total_idle_ticks,
-				rcpu->prev_idle);
+	idle_ticks = (unsigned int) (total_idle_ticks - rcpu->prev_idle);
 	rcpu->prev_idle = total_idle_ticks;
 
 	/* We do a very dumb calculation to update the LEDs for now,
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 3a1dafd228d1..8c344f037bd0 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -394,8 +394,8 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 
 	sigemptyset(&sigign);
 	sigemptyset(&sigcatch);
-	cutime = cstime = utime = stime = cputime_zero;
-	cgtime = gtime = cputime_zero;
+	cutime = cstime = utime = stime = 0;
+	cgtime = gtime = 0;
 
 	if (lock_task_sighand(task, &flags)) {
 		struct signal_struct *sig = task->signal;
@@ -423,14 +423,14 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 			do {
 				min_flt += t->min_flt;
 				maj_flt += t->maj_flt;
-				gtime = cputime_add(gtime, t->gtime);
+				gtime += t->gtime;
 				t = next_thread(t);
 			} while (t != task);
 
 			min_flt += sig->min_flt;
 			maj_flt += sig->maj_flt;
 			thread_group_times(task, &utime, &stime);
-			gtime = cputime_add(gtime, sig->gtime);
+			gtime += sig->gtime;
 		}
 
 		sid = task_session_nr_ns(task, ns);
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 2a30d67dd6b8..714d5d131e76 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -30,7 +30,7 @@ static cputime64_t get_idle_time(int cpu)
 	if (idle_time == -1ULL) {
 		/* !NO_HZ so we can rely on cpustat.idle */
 		idle = kstat_cpu(cpu).cpustat.idle;
-		idle = cputime64_add(idle, arch_idle_time(cpu));
+		idle += arch_idle_time(cpu);
 	} else
 		idle = nsecs_to_jiffies64(1000 * idle_time);
 
@@ -63,23 +63,22 @@ static int show_stat(struct seq_file *p, void *v)
 	struct timespec boottime;
 
 	user = nice = system = idle = iowait =
-		irq = softirq = steal = cputime64_zero;
-	guest = guest_nice = cputime64_zero;
+		irq = softirq = steal = 0;
+	guest = guest_nice = 0;
 	getboottime(&boottime);
 	jif = boottime.tv_sec;
 
 	for_each_possible_cpu(i) {
-		user = cputime64_add(user, kstat_cpu(i).cpustat.user);
-		nice = cputime64_add(nice, kstat_cpu(i).cpustat.nice);
-		system = cputime64_add(system, kstat_cpu(i).cpustat.system);
-		idle = cputime64_add(idle, get_idle_time(i));
-		iowait = cputime64_add(iowait, get_iowait_time(i));
-		irq = cputime64_add(irq, kstat_cpu(i).cpustat.irq);
-		softirq = cputime64_add(softirq, kstat_cpu(i).cpustat.softirq);
-		steal = cputime64_add(steal, kstat_cpu(i).cpustat.steal);
-		guest = cputime64_add(guest, kstat_cpu(i).cpustat.guest);
-		guest_nice = cputime64_add(guest_nice,
-			kstat_cpu(i).cpustat.guest_nice);
+		user += kstat_cpu(i).cpustat.user;
+		nice += kstat_cpu(i).cpustat.nice;
+		system += kstat_cpu(i).cpustat.system;
+		idle += get_idle_time(i);
+		iowait += get_iowait_time(i);
+		irq += kstat_cpu(i).cpustat.irq;
+		softirq += kstat_cpu(i).cpustat.softirq;
+		steal += kstat_cpu(i).cpustat.steal;
+		guest += kstat_cpu(i).cpustat.guest;
+		guest_nice += kstat_cpu(i).cpustat.guest_nice;
 		sum += kstat_cpu_irqs_sum(i);
 		sum += arch_irq_stat_cpu(i);
 
diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index 766b1d456050..ac5243657da3 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -12,10 +12,10 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 	struct timespec uptime;
 	struct timespec idle;
 	int i;
-	cputime_t idletime = cputime_zero;
+	cputime_t idletime = 0;
 
 	for_each_possible_cpu(i)
-		idletime = cputime64_add(idletime, kstat_cpu(i).cpustat.idle);
+		idletime += kstat_cpu(i).cpustat.idle;
 
 	do_posix_clock_monotonic_gettime(&uptime);
 	monotonic_to_bootbased(&uptime);
diff --git a/include/asm-generic/cputime.h b/include/asm-generic/cputime.h
index 62ce6823c0f2..77202e2c9fc5 100644
--- a/include/asm-generic/cputime.h
+++ b/include/asm-generic/cputime.h
@@ -4,70 +4,64 @@
 #include <linux/time.h>
 #include <linux/jiffies.h>
 
-typedef unsigned long cputime_t;
+typedef unsigned long __nocast cputime_t;
 
-#define cputime_zero			(0UL)
 #define cputime_one_jiffy		jiffies_to_cputime(1)
-#define cputime_max			((~0UL >> 1) - 1)
-#define cputime_add(__a, __b)		((__a) +  (__b))
-#define cputime_sub(__a, __b)		((__a) -  (__b))
-#define cputime_div(__a, __n)		((__a) /  (__n))
-#define cputime_halve(__a)		((__a) >> 1)
-#define cputime_eq(__a, __b)		((__a) == (__b))
-#define cputime_gt(__a, __b)		((__a) >  (__b))
-#define cputime_ge(__a, __b)		((__a) >= (__b))
-#define cputime_lt(__a, __b)		((__a) <  (__b))
-#define cputime_le(__a, __b)		((__a) <= (__b))
-#define cputime_to_jiffies(__ct)	(__ct)
+#define cputime_to_jiffies(__ct)	(__force unsigned long)(__ct)
 #define cputime_to_scaled(__ct)		(__ct)
-#define jiffies_to_cputime(__hz)	(__hz)
+#define jiffies_to_cputime(__hz)	(__force cputime_t)(__hz)
 
-typedef u64 cputime64_t;
+typedef u64 __nocast cputime64_t;
 
-#define cputime64_zero (0ULL)
-#define cputime64_add(__a, __b)		((__a) + (__b))
-#define cputime64_sub(__a, __b)		((__a) - (__b))
-#define cputime64_to_jiffies64(__ct)	(__ct)
-#define jiffies64_to_cputime64(__jif)	(__jif)
-#define cputime_to_cputime64(__ct)	((u64) __ct)
-#define cputime64_gt(__a, __b)		((__a) >  (__b))
+#define cputime64_to_jiffies64(__ct)	(__force u64)(__ct)
+#define jiffies64_to_cputime64(__jif)	(__force cputime64_t)(__jif)
 
-#define nsecs_to_cputime64(__ct)	nsecs_to_jiffies64(__ct)
+#define nse