[RFC][PATCH] do_div_signed()

[RFC][PATCH] do_div_signed()

[john stultz]

Here's a quick pass at adding do_div_signed() which provides a signed
version of do_div, avoiding having do_div users hack around signed
issues (like in ntp.c).

It probably could be optimized further, so let me know if you have any
suggestions.


Other thoughts?

thanks
-john


Signed-off-by: John Stultz<johnstul@us.ibm.com>


diff --git a/include/asm-arm/div64.h b/include/asm-arm/div64.h
index 0b5f881..af44e10 100644
--- a/include/asm-arm/div64.h
+++ b/include/asm-arm/div64.h
@@ -225,5 +225,6 @@
 #endif
 
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 
 #endif
diff --git a/include/asm-generic/div64.h b/include/asm-generic/div64.h
index a4a4937..e1cac65 100644
--- a/include/asm-generic/div64.h
+++ b/include/asm-generic/div64.h
@@ -62,4 +62,5 @@ extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
 
 #endif /* BITS_PER_LONG */
 
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 #endif /* _ASM_GENERIC_DIV64_H */
diff --git a/include/asm-i386/div64.h b/include/asm-i386/div64.h
index 438e980..05320a5 100644
--- a/include/asm-i386/div64.h
+++ b/include/asm-i386/div64.h
@@ -49,4 +49,5 @@ div_ll_X_l_rem(long long divs, long div, long *rem)
 }
 
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 #endif
diff --git a/include/asm-m68k/div64.h b/include/asm-m68k/div64.h
index 33caad1..3c76059 100644
--- a/include/asm-m68k/div64.h
+++ b/include/asm-m68k/div64.h
@@ -26,4 +26,5 @@
 })
 
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 #endif /* _M68K_DIV64_H */
diff --git a/include/asm-mips/div64.h b/include/asm-mips/div64.h
index 66189f5..851ce40 100644
--- a/include/asm-mips/div64.h
+++ b/include/asm-mips/div64.h
@@ -111,5 +111,6 @@ static inline uint64_t div64_64(uint64_t dividend, uint64_t divisor)
 }
 
 #endif /* (_MIPS_SZLONG == 64) */
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 
 #endif /* _ASM_DIV64_H */
diff --git a/include/asm-um/div64.h b/include/asm-um/div64.h
index 7b73b2c..1fc4a2c 100644
--- a/include/asm-um/div64.h
+++ b/include/asm-um/div64.h
@@ -4,4 +4,5 @@
 #include "asm/arch/div64.h"
 
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+extern int64_t do_div_signed(int64_t *n, int32_t base);
 #endif
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 87aa5ff..7c093ad 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -302,16 +302,11 @@ int do_adjtimex(struct timex *txc)
 		    freq_adj = time_offset * mtemp;
 		    freq_adj = shift_right(freq_adj, time_constant * 2 +
 					   (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
-		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
+		    if (mtemp >= MINSEC && 
+		    		(time_status & STA_FLL || mtemp > MAXSEC)) {
 			temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL);
-			if (time_offset < 0) {
-			    temp64 = -temp64;
-			    do_div(temp64, mtemp);
-			    freq_adj -= temp64;
-			} else {
-			    do_div(temp64, mtemp);
-			    freq_adj += temp64;
-			}
+			do_div_signed(&temp64, mtemp);
+			freq_adj += temp64;
 		    }
 		    freq_adj += time_freq;
 		    freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
diff --git a/lib/div64.c b/lib/div64.c
index b71cf93..e6ff440 100644
--- a/lib/div64.c
+++ b/lib/div64.c
@@ -79,3 +79,37 @@ uint64_t div64_64(uint64_t dividend, uint64_t divisor)
 EXPORT_SYMBOL(div64_64);
 
 #endif /* BITS_PER_LONG == 32 */
+
+/* Signed 64 bit dividend, result, rem. Signed 32 bit divisor */
+int64_t do_div_signed(int64_t *n, int32_t base)
+{
+	uint64_t num, den;
+	int64_t rem;
+	int num_sign = (*n < 0);
+	int den_sign = (base < 0);
+
+	if (num_sign)
+		num = (uint64_t)(-*n);
+	else
+		num = (uint64_t)*n;
+	
+	/* XXX this is sort of obnoxious,but seems necessary 
+	 * to handle the base possibly being negative as well
+	 */
+	if (den_sign)
+		den = (uint32_t)(-base);
+	else
+	den = (uint32_t)base;
+
+	rem = do_div(num, den);
+
+	*n = (int64_t)num;
+	if(num_sign ^ den_sign)
+		*n = -*n;
+	if(num_sign)
+		rem = -rem;
+
+	return rem;
+}
+
+EXPORT_SYMBOL(do_div_signed);

Re: [RFC][PATCH] do_div_signed()

[Roman Zippel]

Hi,

On Mon, 21 May 2007, john stultz wrote:

> Here's a quick pass at adding do_div_signed() which provides a signed
> version of do_div, avoiding having do_div users hack around signed
> issues (like in ntp.c).
> 
> It probably could be optimized further, so let me know if you have any
> suggestions.
> 
> 
> Other thoughts?

Did I mention that this API could use a little cleanup? :)
Below is what I had in mind, this makes it more clear what types the 
functions are working on. As bonus I cleaned up the i386 div64 
implementation to get rid of the ugly asm casts, so gcc can do better 
register allocation and generate better code.

bye, Roman


Signed-off-by: Roman Zippel <zippel@linux-m68k.org>

---
 include/asm-generic/div64.h |   14 ++++++++++++++
 include/asm-i386/div64.h    |   20 ++++++++++++++++++++
 include/linux/calc64.h      |   28 ++++++++++++++++++++++++++++
 kernel/time.c               |   26 +++++++-------------------
 kernel/time/ntp.c           |   21 +++++----------------
 lib/div64.c                 |   21 ++++++++++++++++++++-
 6 files changed, 94 insertions(+), 36 deletions(-)

Index: linux-2.6/include/asm-generic/div64.h
===================================================================
--- linux-2.6.orig/include/asm-generic/div64.h
+++ linux-2.6/include/asm-generic/div64.h
@@ -35,6 +35,20 @@ static inline uint64_t div64_64(uint64_t
 	return dividend / divisor;
 }
 
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	*remainder = dividend % divisor;
+	return dividend / divisor;
+}
+#define div_u64_rem	div_u64_rem
+
+static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
+{
+	*remainder = dividend % divisor;
+	return dividend / divisor;
+}
+#define div_s64_rem	div_s64_rem
+
 #elif BITS_PER_LONG == 32
 
 extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
Index: linux-2.6/include/asm-i386/div64.h
===================================================================
--- linux-2.6.orig/include/asm-i386/div64.h
+++ linux-2.6/include/asm-i386/div64.h
@@ -48,5 +48,25 @@ div_ll_X_l_rem(long long divs, long div,
 
 }
 
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	union {
+		u64 v64;
+		u32 v32[2];
+	} d = { dividend };
+	u32 upper;
+
+	upper = d.v32[1];
+	if (upper) {
+		upper = d.v32[1] % divisor;
+		d.v32[1] = d.v32[1] / divisor;
+	}
+	asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
+		"rm" (divisor), "0" (d.v32[0]), "1" (upper));
+	return d.v64;
+}
+#define div_u64_rem	div_u64_rem
+
 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
+
 #endif
Index: linux-2.6/include/linux/calc64.h
===================================================================
--- linux-2.6.orig/include/linux/calc64.h
+++ linux-2.6/include/linux/calc64.h
@@ -46,4 +46,32 @@ static inline long div_long_long_rem_sig
 	return res;
 }
 
+#ifndef div_u64_rem
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	*remainder = do_div(dividend, divisor);
+	return dividend;
+}
+#endif
+
+#ifndef div_u64
+static inline u64 div_u64(u64 dividend, u32 divisor)
+{
+	u32 remainder;
+	return div_u64_rem(dividend, divisor, &remainder);
+}
+#endif
+
+#ifndef div_s64_rem
+extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
+#endif
+
+#ifndef div_s64
+static inline s64 div_s64(s64 dividend, s32 divisor)
+{
+	s32 remainder;
+	return div_s64_rem(dividend, divisor, &remainder);
+}
+#endif
+
 #endif
Index: linux-2.6/kernel/time.c
===================================================================
--- linux-2.6.orig/kernel/time.c
+++ linux-2.6/kernel/time.c
@@ -661,9 +661,7 @@ clock_t jiffies_to_clock_t(long x)
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
 	return x / (HZ / USER_HZ);
 #else
-	u64 tmp = (u64)x * TICK_NSEC;
-	do_div(tmp, (NSEC_PER_SEC / USER_HZ));
-	return (long)tmp;
+	return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(jiffies_to_clock_t);
@@ -675,16 +673,12 @@ unsigned long clock_t_to_jiffies(unsigne
 		return ~0UL;
 	return x * (HZ / USER_HZ);
 #else
-	u64 jif;
-
 	/* Don't worry about loss of precision here .. */
 	if (x >= ~0UL / HZ * USER_HZ)
 		return ~0UL;
 
 	/* .. but do try to contain it here */
-	jif = x * (u64) HZ;
-	do_div(jif, USER_HZ);
-	return jif;
+	return div_u64((u64)x * HZ, USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(clock_t_to_jiffies);
@@ -692,17 +686,15 @@ EXPORT_SYMBOL(clock_t_to_jiffies);
 u64 jiffies_64_to_clock_t(u64 x)
 {
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
-	do_div(x, HZ / USER_HZ);
+	return div_u64(x, HZ / USER_HZ);
 #else
 	/*
 	 * There are better ways that don't overflow early,
 	 * but even this doesn't overflow in hundreds of years
 	 * in 64 bits, so..
 	 */
-	x *= TICK_NSEC;
-	do_div(x, (NSEC_PER_SEC / USER_HZ));
+	return div_u64(x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
 #endif
-	return x;
 }
 
 EXPORT_SYMBOL(jiffies_64_to_clock_t);
@@ -710,21 +702,17 @@ EXPORT_SYMBOL(jiffies_64_to_clock_t);
 u64 nsec_to_clock_t(u64 x)
 {
 #if (NSEC_PER_SEC % USER_HZ) == 0
-	do_div(x, (NSEC_PER_SEC / USER_HZ));
+	return div_u64(x, NSEC_PER_SEC / USER_HZ);
 #elif (USER_HZ % 512) == 0
-	x *= USER_HZ/512;
-	do_div(x, (NSEC_PER_SEC / 512));
+	return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
 #else
 	/*
          * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
          * overflow after 64.99 years.
          * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
          */
-	x *= 9;
-	do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) /
-				  USER_HZ));
+	return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
 #endif
-	return x;
 }
 
 #if (BITS_PER_LONG < 64)
Index: linux-2.6/kernel/time/ntp.c
===================================================================
--- linux-2.6.orig/kernel/time/ntp.c
+++ linux-2.6/kernel/time/ntp.c
@@ -53,10 +53,8 @@ static void ntp_update_frequency(void)
 
 	tick_length_base = second_length;
 
-	do_div(second_length, HZ);
-	tick_nsec = second_length >> TICK_LENGTH_SHIFT;
-
-	do_div(tick_length_base, NTP_INTERVAL_FREQ);
+	tick_nsec = div_u64(second_length, HZ) >> TICK_LENGTH_SHIFT;
+	tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ);
 }
 
 /**
@@ -197,7 +195,7 @@ void __attribute__ ((weak)) notify_arch_
 int do_adjtimex(struct timex *txc)
 {
 	long mtemp, save_adjust, rem;
-	s64 freq_adj, temp64;
+	s64 freq_adj;
 	int result;
 
 	/* In order to modify anything, you gotta be super-user! */
@@ -300,17 +298,8 @@ int do_adjtimex(struct timex *txc)
 		    freq_adj = time_offset * mtemp;
 		    freq_adj = shift_right(freq_adj, time_constant * 2 +
 					   (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
-		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
-			temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL);
-			if (time_offset < 0) {
-			    temp64 = -temp64;
-			    do_div(temp64, mtemp);
-			    freq_adj -= temp64;
-			} else {
-			    do_div(temp64, mtemp);
-			    freq_adj += temp64;
-			}
-		    }
+		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC))
+			freq_adj += div_s64(time_offset << (SHIFT_NSEC - SHIFT_FLL), mtemp);
 		    freq_adj += time_freq;
 		    freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
 		    time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
Index: linux-2.6/lib/div64.c
===================================================================
--- linux-2.6.orig/lib/div64.c
+++ linux-2.6/lib/div64.c
@@ -18,7 +18,7 @@
 
 #include <linux/types.h>
 #include <linux/module.h>
-#include <asm/div64.h>
+#include <linux/calc64.h>
 
 /* Not needed on 64bit architectures */
 #if BITS_PER_LONG == 32
@@ -78,4 +78,23 @@ uint64_t div64_64(uint64_t dividend, uin
 }
 EXPORT_SYMBOL(div64_64);
 
+#ifndef div_s64_rem
+s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
+{
+	u64 quotient;
+
+	if (dividend < 0) {
+		quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
+		*remainder = -*remainder;
+		if (divisor > 0)
+			quotient = -quotient;
+	} else {
+		quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
+		if (divisor < 0)
+			quotient = -quotient;
+	}
+	return quotient;
+}
+#endif
+
 #endif /* BITS_PER_LONG == 32 */

Re: [RFC][PATCH] do_div_signed()

[john stultz]

On Tue, 2007-05-22 at 13:52 +0200, Roman Zippel wrote:
> Hi,
> 
> On Mon, 21 May 2007, john stultz wrote:
> 
> > Here's a quick pass at adding do_div_signed() which provides a signed
> > version of do_div, avoiding having do_div users hack around signed
> > issues (like in ntp.c).
> > 
> > It probably could be optimized further, so let me know if you have any
> > suggestions.
> > 
> > 
> > Other thoughts?
> 
> Did I mention that this API could use a little cleanup? :)
> Below is what I had in mind, this makes it more clear what types the 
> functions are working on. As bonus I cleaned up the i386 div64 
> implementation to get rid of the ugly asm casts, so gcc can do better 
> register allocation and generate better code.
> 

Yep. Much nicer then mine!

thanks!
-john

> 
> Signed-off-by: Roman Zippel <zippel@linux-m68k.org>

Acked-by: John Stultz <johnstul@us.ibm.com>


> ---
>  include/asm-generic/div64.h |   14 ++++++++++++++
>  include/asm-i386/div64.h    |   20 ++++++++++++++++++++
>  include/linux/calc64.h      |   28 ++++++++++++++++++++++++++++
>  kernel/time.c               |   26 +++++++-------------------
>  kernel/time/ntp.c           |   21 +++++----------------
>  lib/div64.c                 |   21 ++++++++++++++++++++-
>  6 files changed, 94 insertions(+), 36 deletions(-)
> 
> Index: linux-2.6/include/asm-generic/div64.h
> ===================================================================
> --- linux-2.6.orig/include/asm-generic/div64.h
> +++ linux-2.6/include/asm-generic/div64.h
> @@ -35,6 +35,20 @@ static inline uint64_t div64_64(uint64_t
>  	return dividend / divisor;
>  }
> 
> +static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
> +{
> +	*remainder = dividend % divisor;
> +	return dividend / divisor;
> +}
> +#define div_u64_rem	div_u64_rem
> +
> +static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
> +{
> +	*remainder = dividend % divisor;
> +	return dividend / divisor;
> +}
> +#define div_s64_rem	div_s64_rem
> +
>  #elif BITS_PER_LONG == 32
> 
>  extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
> Index: linux-2.6/include/asm-i386/div64.h
> ===================================================================
> --- linux-2.6.orig/include/asm-i386/div64.h
> +++ linux-2.6/include/asm-i386/div64.h
> @@ -48,5 +48,25 @@ div_ll_X_l_rem(long long divs, long div,
> 
>  }
> 
> +static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
> +{
> +	union {
> +		u64 v64;
> +		u32 v32[2];
> +	} d = { dividend };
> +	u32 upper;
> +
> +	upper = d.v32[1];
> +	if (upper) {
> +		upper = d.v32[1] % divisor;
> +		d.v32[1] = d.v32[1] / divisor;
> +	}
> +	asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
> +		"rm" (divisor), "0" (d.v32[0]), "1" (upper));
> +	return d.v64;
> +}
> +#define div_u64_rem	div_u64_rem
> +
>  extern uint64_t div64_64(uint64_t dividend, uint64_t divisor);
> +
>  #endif
> Index: linux-2.6/include/linux/calc64.h
> ===================================================================
> --- linux-2.6.orig/include/linux/calc64.h
> +++ linux-2.6/include/linux/calc64.h
> @@ -46,4 +46,32 @@ static inline long div_long_long_rem_sig
>  	return res;
>  }
> 
> +#ifndef div_u64_rem
> +static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
> +{
> +	*remainder = do_div(dividend, divisor);
> +	return dividend;
> +}
> +#endif
> +
> +#ifndef div_u64
> +static inline u64 div_u64(u64 dividend, u32 divisor)
> +{
> +	u32 remainder;
> +	return div_u64_rem(dividend, divisor, &remainder);
> +}
> +#endif
> +
> +#ifndef div_s64_rem
> +extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
> +#endif
> +
> +#ifndef div_s64
> +static inline s64 div_s64(s64 dividend, s32 divisor)
> +{
> +	s32 remainder;
> +	return div_s64_rem(dividend, divisor, &remainder);
> +}
> +#endif
> +
>  #endif
> Index: linux-2.6/kernel/time.c
> ===================================================================
> --- linux-2.6.orig/kernel/time.c
> +++ linux-2.6/kernel/time.c
> @@ -661,9 +661,7 @@ clock_t jiffies_to_clock_t(long x)
>  #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
>  	return x / (HZ / USER_HZ);
>  #else
> -	u64 tmp = (u64)x * TICK_NSEC;
> -	do_div(tmp, (NSEC_PER_SEC / USER_HZ));
> -	return (long)tmp;
> +	return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
>  #endif
>  }
>  EXPORT_SYMBOL(jiffies_to_clock_t);
> @@ -675,16 +673,12 @@ unsigned long clock_t_to_jiffies(unsigne
>  		return ~0UL;
>  	return x * (HZ / USER_HZ);
>  #else
> -	u64 jif;
> -
>  	/* Don't worry about loss of precision here .. */
>  	if (x >= ~0UL / HZ * USER_HZ)
>  		return ~0UL;
> 
>  	/* .. but do try to contain it here */
> -	jif = x * (u64) HZ;
> -	do_div(jif, USER_HZ);
> -	return jif;
> +	return div_u64((u64)x * HZ, USER_HZ);
>  #endif
>  }
>  EXPORT_SYMBOL(clock_t_to_jiffies);
> @@ -692,17 +686,15 @@ EXPORT_SYMBOL(clock_t_to_jiffies);
>  u64 jiffies_64_to_clock_t(u64 x)
>  {
>  #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
> -	do_div(x, HZ / USER_HZ);
> +	return div_u64(x, HZ / USER_HZ);
>  #else
>  	/*
>  	 * There are better ways that don't overflow early,
>  	 * but even this doesn't overflow in hundreds of years
>  	 * in 64 bits, so..
>  	 */
> -	x *= TICK_NSEC;
> -	do_div(x, (NSEC_PER_SEC / USER_HZ));
> +	return div_u64(x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
>  #endif
> -	return x;
>  }
> 
>  EXPORT_SYMBOL(jiffies_64_to_clock_t);
> @@ -710,21 +702,17 @@ EXPORT_SYMBOL(jiffies_64_to_clock_t);
>  u64 nsec_to_clock_t(u64 x)
>  {
>  #if (NSEC_PER_SEC % USER_HZ) == 0
> -	do_div(x, (NSEC_PER_SEC / USER_HZ));
> +	return div_u64(x, NSEC_PER_SEC / USER_HZ);
>  #elif (USER_HZ % 512) == 0
> -	x *= USER_HZ/512;
> -	do_div(x, (NSEC_PER_SEC / 512));
> +	return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
>  #else
>  	/*
>           * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
>           * overflow after 64.99 years.
>           * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
>           */
> -	x *= 9;
> -	do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) /
> -				  USER_HZ));
> +	return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
>  #endif
> -	return x;
>  }
> 
>  #if (BITS_PER_LONG < 64)
> Index: linux-2.6/kernel/time/ntp.c
> ===================================================================
> --- linux-2.6.orig/kernel/time/ntp.c
> +++ linux-2.6/kernel/time/ntp.c
> @@ -53,10 +53,8 @@ static void ntp_update_frequency(void)
> 
>  	tick_length_base = second_length;
> 
> -	do_div(second_length, HZ);
> -	tick_nsec = second_length >> TICK_LENGTH_SHIFT;
> -
> -	do_div(tick_length_base, NTP_INTERVAL_FREQ);
> +	tick_nsec = div_u64(second_length, HZ) >> TICK_LENGTH_SHIFT;
> +	tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ);
>  }
> 
>  /**
> @@ -197,7 +195,7 @@ void __attribute__ ((weak)) notify_arch_
>  int do_adjtimex(struct timex *txc)
>  {
>  	long mtemp, save_adjust, rem;
> -	s64 freq_adj, temp64;
> +	s64 freq_adj;
>  	int result;
> 
>  	/* In order to modify anything, you gotta be super-user! */
> @@ -300,17 +298,8 @@ int do_adjtimex(struct timex *txc)
>  		    freq_adj = time_offset * mtemp;
>  		    freq_adj = shift_right(freq_adj, time_constant * 2 +
>  					   (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
> -		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
> -			temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL);
> -			if (time_offset < 0) {
> -			    temp64 = -temp64;
> -			    do_div(temp64, mtemp);
> -			    freq_adj -= temp64;
> -			} else {
> -			    do_div(temp64, mtemp);
> -			    freq_adj += temp64;
> -			}
> -		    }
> +		    if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC))
> +			freq_adj += div_s64(time_offset << (SHIFT_NSEC - SHIFT_FLL), mtemp);
>  		    freq_adj += time_freq;
>  		    freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
>  		    time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
> Index: linux-2.6/lib/div64.c
> ===================================================================
> --- linux-2.6.orig/lib/div64.c
> +++ linux-2.6/lib/div64.c
> @@ -18,7 +18,7 @@
> 
>  #include <linux/types.h>
>  #include <linux/module.h>
> -#include <asm/div64.h>
> +#include <linux/calc64.h>
> 
>  /* Not needed on 64bit architectures */
>  #if BITS_PER_LONG == 32
> @@ -78,4 +78,23 @@ uint64_t div64_64(uint64_t dividend, uin
>  }
>  EXPORT_SYMBOL(div64_64);
> 
> +#ifndef div_s64_rem
> +s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
> +{
> +	u64 quotient;
> +
> +	if (dividend < 0) {
> +		quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
> +		*remainder = -*remainder;
> +		if (divisor > 0)
> +			quotient = -quotient;
> +	} else {
> +		quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
> +		if (divisor < 0)
> +			quotient = -quotient;
> +	}
> +	return quotient;
> +}
> +#endif
> +
>  #endif /* BITS_PER_LONG == 32 */