The header implements definitions for the 64-bit division helpers on 64-bit builds only. For 32-bit builds, it can only provide prototypes and the actual implementation will need to come from elsewhere.
We didn't have any out-of-line definitions in barebox with the result that functions like div_s64_rem() were so far only usable in 64-bit barebox builds. On 32-bit builds, they would result in a linker error. Import the Linux v5.11-rc1 generic out-of-line 64-bit math on 32-bit implementation to fix this. While at it, synchronize the header to reduce diff to upstream. Signed-off-by: Ahmad Fatoum <[email protected]> --- include/linux/math64.h | 211 +++++++++++++++++++++++++++++++++++- lib/Makefile | 1 + lib/math/Makefile | 1 + lib/math/div64.c | 235 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 443 insertions(+), 5 deletions(-) create mode 100644 lib/math/Makefile create mode 100644 lib/math/div64.c diff --git a/include/linux/math64.h b/include/linux/math64.h index 71dd6d7109b7..e8b737e70e50 100644 --- a/include/linux/math64.h +++ b/include/linux/math64.h @@ -1,3 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_MATH64_H #define _LINUX_MATH64_H @@ -6,10 +7,16 @@ #if BITS_PER_LONG == 64 -#define div64_long(x,y) div64_s64((x),(y)) +#define div64_long(x, y) div64_s64((x), (y)) +#define div64_ul(x, y) div64_u64((x), (y)) /** * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder + * @dividend: unsigned 64bit dividend + * @divisor: unsigned 32bit divisor + * @remainder: pointer to unsigned 32bit remainder + * + * Return: sets ``*remainder``, then returns dividend / divisor * * This is commonly provided by 32bit archs to provide an optimized 64bit * divide. @@ -20,8 +27,13 @@ static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) return dividend / divisor; } -/** +/* * div_s64_rem - signed 64bit divide with 32bit divisor with remainder + * @dividend: signed 64bit dividend + * @divisor: signed 32bit divisor + * @remainder: pointer to signed 32bit remainder + * + * Return: sets ``*remainder``, then returns dividend / divisor */ static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder) { @@ -29,16 +41,38 @@ static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder) return dividend / divisor; } -/** +/* + * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder + * @dividend: unsigned 64bit dividend + * @divisor: unsigned 64bit divisor + * @remainder: pointer to unsigned 64bit remainder + * + * Return: sets ``*remainder``, then returns dividend / divisor + */ +static inline u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) +{ + *remainder = dividend % divisor; + return dividend / divisor; +} + +/* * div64_u64 - unsigned 64bit divide with 64bit divisor + * @dividend: unsigned 64bit dividend + * @divisor: unsigned 64bit divisor + * + * Return: dividend / divisor */ static inline u64 div64_u64(u64 dividend, u64 divisor) { return dividend / divisor; } -/** +/* * div64_s64 - signed 64bit divide with 64bit divisor + * @dividend: signed 64bit dividend + * @divisor: signed 64bit divisor + * + * Return: dividend / divisor */ static inline s64 div64_s64(s64 dividend, s64 divisor) { @@ -47,7 +81,8 @@ static inline s64 div64_s64(s64 dividend, s64 divisor) #elif BITS_PER_LONG == 32 -#define div64_long(x,y) div_s64((x),(y)) +#define div64_long(x, y) div_s64((x), (y)) +#define div64_ul(x, y) div_u64((x), (y)) #ifndef div_u64_rem static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) @@ -61,6 +96,10 @@ static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder); #endif +#ifndef div64_u64_rem +extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder); +#endif + #ifndef div64_u64 extern u64 div64_u64(u64 dividend, u64 divisor); #endif @@ -73,6 +112,8 @@ extern s64 div64_s64(s64 dividend, s64 divisor); /** * div_u64 - unsigned 64bit divide with 32bit divisor + * @dividend: unsigned 64bit dividend + * @divisor: unsigned 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 @@ -88,6 +129,8 @@ static inline u64 div_u64(u64 dividend, u32 divisor) /** * div_s64 - signed 64bit divide with 32bit divisor + * @dividend: signed 64bit dividend + * @divisor: signed 32bit divisor */ #ifndef div_s64 static inline s64 div_s64(s64 dividend, s32 divisor) @@ -99,6 +142,164 @@ static inline s64 div_s64(s64 dividend, s32 divisor) u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder); +#ifndef mul_u32_u32 +/* + * Many a GCC version messes this up and generates a 64x64 mult :-( + */ +static inline u64 mul_u32_u32(u32 a, u32 b) +{ + return (u64)a * b; +} +#endif + +#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__) + +#ifndef mul_u64_u32_shr +static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift) +{ + return (u64)(((unsigned __int128)a * mul) >> shift); +} +#endif /* mul_u64_u32_shr */ + +#ifndef mul_u64_u64_shr +static inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift) +{ + return (u64)(((unsigned __int128)a * mul) >> shift); +} +#endif /* mul_u64_u64_shr */ + +#else + +#ifndef mul_u64_u32_shr +static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift) +{ + u32 ah, al; + u64 ret; + + al = a; + ah = a >> 32; + + ret = mul_u32_u32(al, mul) >> shift; + if (ah) + ret += mul_u32_u32(ah, mul) << (32 - shift); + + return ret; +} +#endif /* mul_u64_u32_shr */ + +#ifndef mul_u64_u64_shr +static inline u64 mul_u64_u64_shr(u64 a, u64 b, unsigned int shift) +{ + union { + u64 ll; + struct { +#ifdef __BIG_ENDIAN + u32 high, low; +#else + u32 low, high; +#endif + } l; + } rl, rm, rn, rh, a0, b0; + u64 c; + + a0.ll = a; + b0.ll = b; + + rl.ll = mul_u32_u32(a0.l.low, b0.l.low); + rm.ll = mul_u32_u32(a0.l.low, b0.l.high); + rn.ll = mul_u32_u32(a0.l.high, b0.l.low); + rh.ll = mul_u32_u32(a0.l.high, b0.l.high); + + /* + * Each of these lines computes a 64-bit intermediate result into "c", + * starting at bits 32-95. The low 32-bits go into the result of the + * multiplication, the high 32-bits are carried into the next step. + */ + rl.l.high = c = (u64)rl.l.high + rm.l.low + rn.l.low; + rh.l.low = c = (c >> 32) + rm.l.high + rn.l.high + rh.l.low; + rh.l.high = (c >> 32) + rh.l.high; + + /* + * The 128-bit result of the multiplication is in rl.ll and rh.ll, + * shift it right and throw away the high part of the result. + */ + if (shift == 0) + return rl.ll; + if (shift < 64) + return (rl.ll >> shift) | (rh.ll << (64 - shift)); + return rh.ll >> (shift & 63); +} +#endif /* mul_u64_u64_shr */ + +#endif + +#ifndef mul_u64_u32_div +static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor) +{ + union { + u64 ll; + struct { +#ifdef __BIG_ENDIAN + u32 high, low; +#else + u32 low, high; +#endif + } l; + } u, rl, rh; + + u.ll = a; + rl.ll = mul_u32_u32(u.l.low, mul); + rh.ll = mul_u32_u32(u.l.high, mul) + rl.l.high; + + /* Bits 32-63 of the result will be in rh.l.low. */ + rl.l.high = do_div(rh.ll, divisor); + + /* Bits 0-31 of the result will be in rl.l.low. */ + do_div(rl.ll, divisor); + + rl.l.high = rh.l.low; + return rl.ll; +} +#endif /* mul_u64_u32_div */ + +u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div); + +#define DIV64_U64_ROUND_UP(ll, d) \ + ({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); }) + +/** + * DIV64_U64_ROUND_CLOSEST - unsigned 64bit divide with 64bit divisor rounded to nearest integer + * @dividend: unsigned 64bit dividend + * @divisor: unsigned 64bit divisor + * + * Divide unsigned 64bit dividend by unsigned 64bit divisor + * and round to closest integer. + * + * Return: dividend / divisor rounded to nearest integer + */ +#define DIV64_U64_ROUND_CLOSEST(dividend, divisor) \ + ({ u64 _tmp = (divisor); div64_u64((dividend) + _tmp / 2, _tmp); }) + +/* + * DIV_S64_ROUND_CLOSEST - signed 64bit divide with 32bit divisor rounded to nearest integer + * @dividend: signed 64bit dividend + * @divisor: signed 32bit divisor + * + * Divide signed 64bit dividend by signed 32bit divisor + * and round to closest integer. + * + * Return: dividend / divisor rounded to nearest integer + */ +#define DIV_S64_ROUND_CLOSEST(dividend, divisor)( \ +{ \ + s64 __x = (dividend); \ + s32 __d = (divisor); \ + ((__x > 0) == (__d > 0)) ? \ + div_s64((__x + (__d / 2)), __d) : \ + div_s64((__x - (__d / 2)), __d); \ +} \ +) + static __always_inline u32 __iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder) { diff --git a/lib/Makefile b/lib/Makefile index ba6af6f2ab24..9c6f4133d77c 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -25,6 +25,7 @@ obj-y += cmdlinepart.o obj-y += recursive_action.o obj-y += make_directory.o obj-y += math.o +obj-y += math/ obj-$(CONFIG_XXHASH) += xxhash.o obj-$(CONFIG_BZLIB) += decompress_bunzip2.o obj-$(CONFIG_ZLIB) += decompress_inflate.o zlib_inflate/ diff --git a/lib/math/Makefile b/lib/math/Makefile new file mode 100644 index 000000000000..3341a8e4744b --- /dev/null +++ b/lib/math/Makefile @@ -0,0 +1 @@ +obj-y += div64.o diff --git a/lib/math/div64.c b/lib/math/div64.c new file mode 100644 index 000000000000..507de8216a3e --- /dev/null +++ b/lib/math/div64.c @@ -0,0 +1,235 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2003 Bernardo Innocenti <[email protected]> + * + * Based on former do_div() implementation from asm-parisc/div64.h: + * Copyright (C) 1999 Hewlett-Packard Co + * Copyright (C) 1999 David Mosberger-Tang <[email protected]> + * + * + * Generic C version of 64bit/32bit division and modulo, with + * 64bit result and 32bit remainder. + * + * The fast case for (n>>32 == 0) is handled inline by do_div(). + * + * Code generated for this function might be very inefficient + * for some CPUs. __div64_32() can be overridden by linking arch-specific + * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S + * or by defining a preprocessor macro in arch/include/asm/div64.h. + */ + +#include <linux/bitops.h> +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/math64.h> +#include <linux/log2.h> + +/* Not needed on 64bit architectures */ +#if BITS_PER_LONG == 32 + +#ifndef __div64_32 +uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base) +{ + uint64_t rem = *n; + uint64_t b = base; + uint64_t res, d = 1; + uint32_t high = rem >> 32; + + /* Reduce the thing a bit first */ + res = 0; + if (high >= base) { + high /= base; + res = (uint64_t) high << 32; + rem -= (uint64_t) (high*base) << 32; + } + + while ((int64_t)b > 0 && b < rem) { + b = b+b; + d = d+d; + } + + do { + if (rem >= b) { + rem -= b; + res += d; + } + b >>= 1; + d >>= 1; + } while (d); + + *n = res; + return rem; +} +EXPORT_SYMBOL(__div64_32); +#endif + +/** + * div_s64_rem - signed 64bit divide with 64bit divisor and remainder + * @dividend: 64bit dividend + * @divisor: 64bit divisor + * @remainder: 64bit remainder + */ +#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; +} +EXPORT_SYMBOL(div_s64_rem); +#endif + +/** + * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder + * @dividend: 64bit dividend + * @divisor: 64bit divisor + * @remainder: 64bit remainder + * + * This implementation is a comparable to algorithm used by div64_u64. + * But this operation, which includes math for calculating the remainder, + * is kept distinct to avoid slowing down the div64_u64 operation on 32bit + * systems. + */ +#ifndef div64_u64_rem +u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) +{ + u32 high = divisor >> 32; + u64 quot; + + if (high == 0) { + u32 rem32; + quot = div_u64_rem(dividend, divisor, &rem32); + *remainder = rem32; + } else { + int n = fls(high); + quot = div_u64(dividend >> n, divisor >> n); + + if (quot != 0) + quot--; + + *remainder = dividend - quot * divisor; + if (*remainder >= divisor) { + quot++; + *remainder -= divisor; + } + } + + return quot; +} +EXPORT_SYMBOL(div64_u64_rem); +#endif + +/** + * div64_u64 - unsigned 64bit divide with 64bit divisor + * @dividend: 64bit dividend + * @divisor: 64bit divisor + * + * This implementation is a modified version of the algorithm proposed + * by the book 'Hacker's Delight'. The original source and full proof + * can be found here and is available for use without restriction. + * + * 'http://www.hackersdelight.org/hdcodetxt/divDouble.c.txt' + */ +#ifndef div64_u64 +u64 div64_u64(u64 dividend, u64 divisor) +{ + u32 high = divisor >> 32; + u64 quot; + + if (high == 0) { + quot = div_u64(dividend, divisor); + } else { + int n = fls(high); + quot = div_u64(dividend >> n, divisor >> n); + + if (quot != 0) + quot--; + if ((dividend - quot * divisor) >= divisor) + quot++; + } + + return quot; +} +EXPORT_SYMBOL(div64_u64); +#endif + +/** + * div64_s64 - signed 64bit divide with 64bit divisor + * @dividend: 64bit dividend + * @divisor: 64bit divisor + */ +#ifndef div64_s64 +s64 div64_s64(s64 dividend, s64 divisor) +{ + s64 quot, t; + + quot = div64_u64(abs(dividend), abs(divisor)); + t = (dividend ^ divisor) >> 63; + + return (quot ^ t) - t; +} +EXPORT_SYMBOL(div64_s64); +#endif + +#endif /* BITS_PER_LONG == 32 */ + +/* + * Iterative div/mod for use when dividend is not expected to be much + * bigger than divisor. + */ +u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder) +{ + return __iter_div_u64_rem(dividend, divisor, remainder); +} +EXPORT_SYMBOL(iter_div_u64_rem); + +#ifndef mul_u64_u64_div_u64 +u64 mul_u64_u64_div_u64(u64 a, u64 b, u64 c) +{ + u64 res = 0, div, rem; + int shift; + + /* can a * b overflow ? */ + if (ilog2(a) + ilog2(b) > 62) { + /* + * (b * a) / c is equal to + * + * (b / c) * a + + * (b % c) * a / c + * + * if nothing overflows. Can the 1st multiplication + * overflow? Yes, but we do not care: this can only + * happen if the end result can't fit in u64 anyway. + * + * So the code below does + * + * res = (b / c) * a; + * b = b % c; + */ + div = div64_u64_rem(b, c, &rem); + res = div * a; + b = rem; + + shift = ilog2(a) + ilog2(b) - 62; + if (shift > 0) { + /* drop precision */ + b >>= shift; + c >>= shift; + if (!c) + return res; + } + } + + return res + div64_u64(a * b, c); +} +#endif -- 2.29.2 _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
