diff -ru linux-2.6.10-rc1/include/asm-arm/div64.h linux-2.6.10-rc1-nsz/include/asm-arm/div64.h
--- linux-2.6.10-rc1/include/asm-arm/div64.h	2004-10-27 10:41:40.000000000 -0700
+++ linux-2.6.10-rc1-nsz/include/asm-arm/div64.h	2004-10-27 10:24:25.000000000 -0700
@@ -27,22 +27,27 @@
 #define __xh "r1"
 #endif
 
-#define do_div(n,base)						\
-({								\
-	register unsigned int __base      asm("r4") = base;	\
-	register unsigned long long __n   asm("r0") = n;	\
-	register unsigned long long __res asm("r2");		\
-	register unsigned int __rem       asm(__xh);		\
-	asm(	__asmeq("%0", __xh)				\
-		__asmeq("%1", "r2")				\
-		__asmeq("%2", "r0")				\
-		__asmeq("%3", "r4")				\
-		"bl	__do_div64"				\
-		: "=r" (__rem), "=r" (__res)			\
-		: "r" (__n), "r" (__base)			\
-		: "ip", "lr", "cc");				\
-	n = __res;						\
-	__rem;							\
+#define do_div(n,base)							\
+({									\
+	register unsigned long long __n   asm("r0") = n;		\
+	register unsigned long long __res asm("r2");			\
+	register unsigned int __rem       asm(__xh);			\
+	if (__builtin_constant_p(base) && !((base) & ((base)-1))) {	\
+		__rem = __n % (base);					\
+		__res = __n / (base);					\
+	} else {							\
+		register unsigned int __base      asm("r4") = base;	\
+		asm(	__asmeq("%0", __xh)				\
+			__asmeq("%1", "r2")				\
+			__asmeq("%2", "r0")				\
+			__asmeq("%3", "r4")				\
+			"bl	__do_div64"				\
+			: "=r" (__rem), "=r" (__res)			\
+			: "r" (__n), "r" (__base)			\
+			: "ip", "lr", "cc");				\
+	}								\
+	n = __res;							\
+	__rem;								\
 })
 
 #endif
diff -ru linux-2.6.10-rc1/include/asm-generic/div64.h linux-2.6.10-rc1-nsz/include/asm-generic/div64.h
--- linux-2.6.10-rc1/include/asm-generic/div64.h	2004-10-27 10:41:40.000000000 -0700
+++ linux-2.6.10-rc1-nsz/include/asm-generic/div64.h	2004-10-27 10:24:06.000000000 -0700
@@ -22,12 +22,17 @@
 
 #if BITS_PER_LONG == 64
 
-# define do_div(n,base) ({					\
-	uint32_t __base = (base);				\
-	uint32_t __rem;						\
-	__rem = ((uint64_t)(n)) % __base;			\
-	(n) = ((uint64_t)(n)) / __base;				\
-	__rem;							\
+# define do_div(n,base) ({						\
+	uint32_t __rem;							\
+	if (__builtin_constant_p(base) && !((base) & ((base)-1))) {	\
+		__rem = ((uint64_t)(n)) % (base);			\
+		(n) = ((uint64_t)(n)) / (base);				\
+	} else {							\
+		uint32_t __base = (base);				\
+		__rem = ((uint64_t)(n)) % __base;			\
+		(n) = ((uint64_t)(n)) / __base;				\
+	}								\
+	__rem;								\
  })
 
 #elif BITS_PER_LONG == 32
@@ -37,16 +42,21 @@
 /* The unnecessary pointer compare is there
  * to check for type safety (n must be 64bit)
  */
-# define do_div(n,base) ({				\
-	uint32_t __base = (base);			\
-	uint32_t __rem;					\
-	(void)(((typeof((n)) *)0) == ((uint64_t *)0));	\
-	if (likely(((n) >> 32) == 0)) {			\
-		__rem = (uint32_t)(n) % __base;		\
-		(n) = (uint32_t)(n) / __base;		\
-	} else 						\
-		__rem = __div64_32(&(n), __base);	\
-	__rem;						\
+# define do_div(n,base) ({						\
+	uint32_t __rem;						 	\
+	(void)(((typeof((n)) *)0) == ((uint64_t *)0));			\
+	if (__builtin_constant_p(base) && !((base) & ((base)-1))) {     \
+		__rem = ((uint64_t)(n)) % (base);			\
+		(n) = ((uint64_t)(n)) / (base);				\
+	} else {							\
+		uint32_t __base = (base);				\
+		if (likely(((n) >> 32) == 0)) {				\
+			__rem = (uint32_t)(n) % __base;			\
+			(n) = (uint32_t)(n) / __base;			\
+		} else 							\
+			__rem = __div64_32(&(n), __base);		\
+	}								\
+	__rem;								\
  })
 
 #else /* BITS_PER_LONG == ?? */
diff -ru linux-2.6.10-rc1/include/asm-i386/div64.h linux-2.6.10-rc1-nsz/include/asm-i386/div64.h
--- linux-2.6.10-rc1/include/asm-i386/div64.h	2004-10-27 10:41:40.000000000 -0700
+++ linux-2.6.10-rc1-nsz/include/asm-i386/div64.h	2004-10-27 10:15:04.000000000 -0700
@@ -14,16 +14,23 @@
  * convention" on x86.
  */
 #define do_div(n,base) ({ \
-	unsigned long __upper, __low, __high, __mod, __base; \
-	__base = (base); \
-	asm("":"=a" (__low), "=d" (__high):"A" (n)); \
-	__upper = __high; \
-	if (__high) { \
-		__upper = __high % (__base); \
-		__high = __high / (__base); \
+	unsigned long __mod; \
+	if (__builtin_constant_p(base) && !((base) & ((base)-1))) { \
+		__mod = ((uint64_t)(n)) % base;	\
+		(n) = ((uint64_t)(n)) / base; \
+	} else { \
+		unsigned long __upper, __low, __high, __base; \
+		__base = (base); \
+		asm("":"=a" (__low), "=d" (__high):"A" (n)); \
+		__upper = __high; \
+		if (__high) { \
+			__upper = __high % (__base); \
+			__high = __high / (__base); \
+		} \
+		asm("divl %2":	"=a" (__low), "=d" (__mod) : \
+				"rm" (__base), "0" (__low), "1" (__upper)); \
+		asm("":"=A" (n):"a" (__low),"d" (__high)); \
 	} \
-	asm("divl %2":"=a" (__low), "=d" (__mod):"rm" (__base), "0" (__low), "1" (__upper)); \
-	asm("":"=A" (n):"a" (__low),"d" (__high)); \
 	__mod; \
 })
 
diff -ru linux-2.6.10-rc1/include/asm-m32r/div64.h linux-2.6.10-rc1-nsz/include/asm-m32r/div64.h
--- linux-2.6.10-rc1/include/asm-m32r/div64.h	2004-10-27 10:41:40.000000000 -0700
+++ linux-2.6.10-rc1-nsz/include/asm-m32r/div64.h	2004-10-27 10:23:37.000000000 -0700
@@ -11,28 +11,33 @@
  *  n = n / base;
  *  return value = n % base;
  */
-#define do_div(n, base)						\
-({								\
-	unsigned long _res, _high, _mid, _low;			\
-								\
-	_low = (n) & 0xffffffffUL;				\
-	_high = (n) >> 32;					\
-	if (_high) {						\
-		_mid = (_high % (unsigned long)(base)) << 16;	\
-		_high = _high / (unsigned long)(base);		\
-		_mid += _low >> 16;				\
-		_low &= 0x0000ffffUL;				\
-		_low += (_mid % (unsigned long)(base)) << 16;	\
-		_mid = _mid / (unsigned long)(base);		\
-		_res = _low % (unsigned long)(base);		\
-		_low = _low / (unsigned long)(base);		\
-		n = _low + ((long long)_mid << 16) +		\
-			((long long)_high << 32);		\
-	} else {						\
-		_res = _low % (unsigned long)(base);		\
-		n = (_low / (unsigned long)(base));		\
-	}							\
-	_res;							\
+#define do_div(n, base)							\
+({									\
+	unsigned long _res;						\
+	if (__builtin_constant_p(base) && !((base) & ((base)-1))) {	\
+		_res = ((uint64_t)(n)) % (base);			\
+		(n) = ((uint64_t)(n)) / (base);				\
+	} else {							\
+		unsigned long _high, _mid, _low;			\
+		_low = (n) & 0xffffffffUL;				\
+		_high = (n) >> 32;					\
+		if (_high) {						\
+			_mid = (_high % (unsigned long)(base)) << 16;	\
+			_high = _high / (unsigned long)(base);		\
+			_mid += _low >> 16;				\
+			_low &= 0x0000ffffUL;				\
+			_low += (_mid % (unsigned long)(base)) << 16;	\
+			_mid = _mid / (unsigned long)(base);		\
+			_res = _low % (unsigned long)(base);		\
+			_low = _low / (unsigned long)(base);		\
+			n = _low + ((long long)_mid << 16) +		\
+				((long long)_high << 32);		\
+		} else {						\
+			_res = _low % (unsigned long)(base);		\
+			n = (_low / (unsigned long)(base));		\
+		}							\
+	}								\
+	_res;								\
 })
 
 #endif  /* _ASM_M32R_DIV64 */
diff -ru linux-2.6.10-rc1/include/asm-m68k/div64.h linux-2.6.10-rc1-nsz/include/asm-m68k/div64.h
--- linux-2.6.10-rc1/include/asm-m68k/div64.h	2004-10-27 10:41:40.000000000 -0700
+++ linux-2.6.10-rc1-nsz/include/asm-m68k/div64.h	2004-10-27 10:23:23.000000000 -0700
@@ -3,24 +3,30 @@
 
 /* n = n / base; return rem; */
 
-#define do_div(n, base) ({					\
-	union {							\
-		unsigned long n32[2];				\
-		unsigned long long n64;				\
-	} __n;							\
-	unsigned long __rem, __upper;				\
-								\
-	__n.n64 = (n);						\
-	if ((__upper = __n.n32[0])) {				\
-		asm ("divul.l %2,%1:%0"				\
-			: "=d" (__n.n32[0]), "=d" (__upper)	\
-			: "d" (base), "0" (__n.n32[0]));	\
-	}							\
-	asm ("divu.l %2,%1:%0"					\
-		: "=d" (__n.n32[1]), "=d" (__rem)		\
-		: "d" (base), "1" (__upper), "0" (__n.n32[1]));	\
-	(n) = __n.n64;						\
-	__rem;							\
-})
+#define do_div(n, base) ({						\
+	unsigned long __rem;						\
+	if (__builtin_constant_p(base) && !((base) & ((base)-1))) {	\
+		__rem = ((uint64_t)(n)) % (base);			\
+		(n) = ((uint64_t)(n)) / (base);				\
+	} else {							\
+		union {							\
+			unsigned long n32[2];				\
+			unsigned long long n64;				\
+		} __n;							\
+		unsigned long __upper;					\
+									\
+		__n.n64 = (n);						\
+		if ((__upper = __n.n32[0])) {				\
+			asm ("divul.l %2,%1:%0"				\
+				: "=d" (__n.n32[0]), "=d" (__upper)	\
+				: "d" (base), "0" (__n.n32[0]));	\
+		}							\
+		asm ("divu.l %2,%1:%0"					\
+			: "=d" (__n.n32[1]), "=d" (__rem)		\
+			: "d" (base), "1" (__upper), "0" (__n.n32[1]));	\
+		(n) = __n.n64;						\
+	}								\
+	__rem;								\
+}))
 
 #endif /* _M68K_DIV64_H */
diff -ru linux-2.6.10-rc1/include/asm-mips/div64.h linux-2.6.10-rc1-nsz/include/asm-mips/div64.h
--- linux-2.6.10-rc1/include/asm-mips/div64.h	2004-10-27 10:41:40.000000000 -0700
+++ linux-2.6.10-rc1-nsz/include/asm-mips/div64.h	2004-10-27 10:34:01.000000000 -0700
@@ -52,27 +52,32 @@
 	__mod; })
 
 #define do_div(n, base) ({ \
+	unsigned long long __div; \
 	unsigned long long __quot; \
 	unsigned long __mod; \
-	unsigned long long __div; \
-	unsigned long __upper, __low, __high, __base; \
 	\
 	__div = (n); \
-	__base = (base); \
-	\
-	__high = __div >> 32; \
-	__low = __div; \
-	__upper = __high; \
-	\
-	if (__high) \
-		__asm__("divu	$0, %z2, %z3" \
-			: "=h" (__upper), "=l" (__high) \
-			: "Jr" (__high), "Jr" (__base)); \
-	\
-	__mod = do_div64_32(__low, __upper, __low, __base); \
-	\
-	__quot = __high; \
-	__quot = __quot << 32 | __low; \
+	if (__builtin_constant_p(base) && !((base) & ((base)-1))) { \
+		__mod = __div % (base); \
+		__quot = __div / (base); \
+	} else { \
+		unsigned long __upper, __low, __high, __base; \
+		\
+		__base = (base); \
+		__high = __div >> 32; \
+		__low = __div; \
+		__upper = __high; \
+		\
+		if (__high) \
+			__asm__("divu	$0, %z2, %z3" \
+				: "=h" (__upper), "=l" (__high) \
+				: "Jr" (__high), "Jr" (__base)); \
+		\
+		__mod = do_div64_32(__low, __upper, __low, __base); \
+		\
+		__quot = __high; \
+		__quot = __quot << 32 | __low; \
+	} \
 	(n) = __quot; \
 	__mod; })
 #endif /* (_MIPS_SZLONG == 32) */
@@ -104,18 +109,22 @@
  * Hey, we're already 64-bit, no
  * need to play games..
  */
-#define do_div(n, base) ({ \
+#define do_div(n, base) ( \
+	unsigned long __div; \
 	unsigned long __quot; \
 	unsigned int __mod; \
-	unsigned long __div; \
-	unsigned int __base; \
 	\
 	__div = (n); \
-	__base = (base); \
-	\
-	__mod = __div % __base; \
-	__quot = __div / __base; \
-	\
+	if (__builtin_constant_p(base) && !((base) & ((base)-1))) { \
+		__mod = __div % (base); \
+		__quot = __div / (base); \
+	} else { \
+		unsigned int __base; \
+		\
+		__base = (base); \
+		__mod = __div % __base; \
+		__quot = __div / __base; \
+	} \
 	(n) = __quot; \
 	__mod; })
 
diff -ru linux-2.6.10-rc1/include/asm-s390/div64.h linux-2.6.10-rc1-nsz/include/asm-s390/div64.h
--- linux-2.6.10-rc1/include/asm-s390/div64.h	2004-10-27 10:42:32.000000000 -0700
+++ linux-2.6.10-rc1-nsz/include/asm-s390/div64.h	2004-10-27 10:43:06.000000000 -0700
@@ -4,42 +4,47 @@
 #ifndef __s390x__
 
 /* for do_div "base" needs to be smaller than 2^31-1 */
-#define do_div(n, base) (					\
-	unsigned long long __n = (n);				\
-	unsigned long __r;					\
-								\
-	asm ("   slr  0,0\n"					\
-	     "   l    1,%1\n"					\
-	     "   srdl 0,1\n"					\
-	     "   dr   0,%2\n"					\
-	     "   alr  1,1\n"					\
-	     "   alr  0,0\n"					\
-	     "   lhi  2,1\n"					\
-	     "   n    2,%1\n"					\
-	     "   alr  0,2\n"					\
-	     "   clr  0,%2\n"					\
-	     "   jl   0f\n"					\
-	     "   slr  0,%2\n"					\
-             "   ahi  1,1\n"					\
-	     "0: st   1,%1\n"					\
-	     "   l    1,4+%1\n"					\
-	     "   srdl 0,1\n"					\
-             "   dr   0,%2\n"					\
-	     "   alr  1,1\n"					\
-	     "   alr  0,0\n"					\
-	     "   lhi  2,1\n"					\
-	     "   n    2,4+%1\n"					\
-	     "   alr  0,2\n"					\
-	     "   clr  0,%2\n"					\
-             "   jl   1f\n"					\
-	     "   slr  0,%2\n"					\
-	     "   ahi  1,1\n"					\
-	     "1: st   1,4+%1\n"					\
-             "   lr   %0,0"					\
-	     : "=d" (__r), "=m" (__n)				\
-	     : "d" (base), "m" (__n) : "0", "1", "2", "cc" );	\
-	(n) = (__n);						\
-        __r;                                                    \
+#define do_div(n, base) ({						\
+	unsigned long long __n = (n);					\
+	unsigned long __r;						\
+									\
+	if (__builtin_constant_p(base) && !((base) & ((base)-1))) {	\
+		__r = __n % (base);					\
+		__n = __n / (base);					\
+	} else {							\
+		asm ("   slr  0,0\n"					\
+		     "   l    1,%1\n"					\
+		     "   srdl 0,1\n"					\
+		     "   dr   0,%2\n"					\
+		     "   alr  1,1\n"					\
+		     "   alr  0,0\n"					\
+		     "   lhi  2,1\n"					\
+		     "   n    2,%1\n"					\
+		     "   alr  0,2\n"					\
+		     "   clr  0,%2\n"					\
+		     "   jl   0f\n"					\
+		     "   slr  0,%2\n"					\
+		     "   ahi  1,1\n"					\
+		     "0: st   1,%1\n"					\
+		     "   l    1,4+%1\n"					\
+		     "   srdl 0,1\n"					\
+		     "   dr   0,%2\n"					\
+		     "   alr  1,1\n"					\
+		     "   alr  0,0\n"					\
+		     "   lhi  2,1\n"					\
+		     "   n    2,4+%1\n"					\
+		     "   alr  0,2\n"					\
+		     "   clr  0,%2\n"					\
+		     "   jl   1f\n"					\
+		     "   slr  0,%2\n"					\
+		     "   ahi  1,1\n"					\
+		     "1: st   1,4+%1\n"					\
+		     "   lr   %0,0"					\
+		     : "=d" (__r), "=m" (__n)				\
+		     : "d" (base), "m" (__n) : "0", "1", "2", "cc" );	\
+	}								\
+	(n) = (__n);							\
+	__r;								\
 })
 
 #else /* __s390x__ */