[PATCH] include: <linux/math64.h>: sync with upstream
Ahmad Fatoum
ahmad at a3f.at
Tue Dec 29 07:32:54 EST 2020
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 <ahmad at a3f.at>
---
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 <bernie at develer.com>
+ *
+ * Based on former do_div() implementation from asm-parisc/div64.h:
+ * Copyright (C) 1999 Hewlett-Packard Co
+ * Copyright (C) 1999 David Mosberger-Tang <davidm at hpl.hp.com>
+ *
+ *
+ * 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
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