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linux/math64.h: Extract common header for vDSO

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The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split math64.h into linux and common headers to make the latter suitable
for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-10-vincenzo.frascino@arm.com
This commit is contained in:
Vincenzo Frascino 2020-03-20 14:53:34 +00:00 committed by Thomas Gleixner
parent 14ee2ac618
commit b874b8358c
2 changed files with 25 additions and 19 deletions
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20
include/linux/math64.h
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@ -3,6 +3,7 @@
#define _LINUX_MATH64_H
#include <linux/types.h>
#include <vdso/math64.h>
#include <asm/div64.h>
#if BITS_PER_LONG == 64
@ -142,25 +143,6 @@ static inline s64 div_s64(s64 dividend, s32 divisor)
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;
}
#ifndef mul_u32_u32
/*
* Many a GCC version messes this up and generates a 64x64 mult :-(

24
include/vdso/math64.h Normal file
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@ -0,0 +1,24 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __VDSO_MATH64_H
#define __VDSO_MATH64_H
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 /* __VDSO_MATH64_H */