mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-23 04:34:11 +08:00
658716d19f
The current implementation of div64_u64 for 32bit systems returns an approximately correct result when the divisor exceeds 32bits. Since doing 64bit division using 32bit hardware is a long since solved problem we just use one of the existing proven methods. Additionally, add a div64_s64 function to correctly handle doing signed 64bit division. Addresses https://bugzilla.redhat.com/show_bug.cgi?id=616105 Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Ben Woodard <bwoodard@llnl.gov> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Mark Grondona <mgrondona@llnl.gov> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
118 lines
2.4 KiB
C
118 lines
2.4 KiB
C
#ifndef _LINUX_MATH64_H
|
|
#define _LINUX_MATH64_H
|
|
|
|
#include <linux/types.h>
|
|
#include <asm/div64.h>
|
|
|
|
#if BITS_PER_LONG == 64
|
|
|
|
/**
|
|
* div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
|
|
*
|
|
* This is commonly provided by 32bit archs to provide an optimized 64bit
|
|
* divide.
|
|
*/
|
|
static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
|
|
{
|
|
*remainder = dividend % divisor;
|
|
return dividend / divisor;
|
|
}
|
|
|
|
/**
|
|
* div_s64_rem - signed 64bit divide with 32bit divisor with remainder
|
|
*/
|
|
static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
|
|
{
|
|
*remainder = dividend % divisor;
|
|
return dividend / divisor;
|
|
}
|
|
|
|
/**
|
|
* div64_u64 - unsigned 64bit divide with 64bit divisor
|
|
*/
|
|
static inline u64 div64_u64(u64 dividend, u64 divisor)
|
|
{
|
|
return dividend / divisor;
|
|
}
|
|
|
|
/**
|
|
* div64_s64 - signed 64bit divide with 64bit divisor
|
|
*/
|
|
static inline s64 div64_s64(s64 dividend, s64 divisor)
|
|
{
|
|
return dividend / divisor;
|
|
}
|
|
|
|
#elif BITS_PER_LONG == 32
|
|
|
|
#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_s64_rem
|
|
extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
|
|
#endif
|
|
|
|
#ifndef div64_u64
|
|
extern u64 div64_u64(u64 dividend, u64 divisor);
|
|
#endif
|
|
|
|
#ifndef div64_s64
|
|
extern s64 div64_s64(s64 dividend, s64 divisor);
|
|
#endif
|
|
|
|
#endif /* BITS_PER_LONG */
|
|
|
|
/**
|
|
* div_u64 - unsigned 64bit divide with 32bit divisor
|
|
*
|
|
* This is the most common 64bit divide and should be used if possible,
|
|
* as many 32bit archs can optimize this variant better than a full 64bit
|
|
* divide.
|
|
*/
|
|
#ifndef div_u64
|
|
static inline u64 div_u64(u64 dividend, u32 divisor)
|
|
{
|
|
u32 remainder;
|
|
return div_u64_rem(dividend, divisor, &remainder);
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* div_s64 - signed 64bit divide with 32bit divisor
|
|
*/
|
|
#ifndef div_s64
|
|
static inline s64 div_s64(s64 dividend, s32 divisor)
|
|
{
|
|
s32 remainder;
|
|
return div_s64_rem(dividend, divisor, &remainder);
|
|
}
|
|
#endif
|
|
|
|
u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
|
|
|
|
static __always_inline u32
|
|
__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
|
|
{
|
|
u32 ret = 0;
|
|
|
|
while (dividend >= divisor) {
|
|
/* The following asm() prevents the compiler from
|
|
optimising this loop into a modulo operation. */
|
|
asm("" : "+rm"(dividend));
|
|
|
|
dividend -= divisor;
|
|
ret++;
|
|
}
|
|
|
|
*remainder = dividend;
|
|
|
|
return ret;
|
|
}
|
|
|
|
#endif /* _LINUX_MATH64_H */
|