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linux_dsm_epyc7002/arch/mips/math-emu/ieee754.h
Aleksandar Markovic 3ec404d88c MIPS: math-emu: RINT.<D|S>: Fix several problems by reimplementation 
Reimplement RINT.<D|S> kernel emulation so that all RINT.<D|S>
specifications are met.

For the sake of simplicity, let's analyze RINT.S only. Prior to
this patch, RINT.S emulation was essentially implemented as (in
pseudocode) <output> = ieee754sp_flong(ieee754sp_tlong(<input>)),
where ieee754sp_tlong() and ieee754sp_flong() are functions
providing conversion from double to integer, and from integer
to double, respectively. On surface, this implementation looks
correct, but actually fails in many cases. Following problems
were detected:

1. NaN and infinity cases will not be handled properly. The
   function ieee754sp_flong() never returns NaN nor infinity.
2. For RINT.S, for all inputs larger than LONG_MAX, and smaller
   than FLT_MAX, the result will be wrong, and the overflow
   exception will be erroneously set. A similar problem for
   negative inputs exists as well.
3. For some rounding modes, for some negative inputs close to zero,
   the return value will be zero, and should be -zero. This is
   because ieee754sp_flong() never returns -zero.

This patch removes the problems above by implementing dedicated
functions for RINT.<D|S> emulation.

The core of the new function functionality is adapted version of
the core of the function ieee754sp_tlong(). However, there are many
details that are implemented to match RINT.<D|S> specification. It
should be said that the functionality of ieee754sp_tlong() actually
closely corresponds to CVT.L.S instruction, and it is used while
emulating CVT.L.S. However, RINT.S and CVT.L.S instructions differ
in many aspects. This patch fulfills missing support for RINT.<D|S>.

Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Douglas Leung <douglas.leung@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Maciej W. Rozycki <macro@imgtec.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Petar Jovanovic <petar.jovanovic@imgtec.com>
Cc: Raghu Gandham <raghu.gandham@imgtec.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17141/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2017-08-29 15:21:56 +02:00

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/*
* MIPS floating point support
* Copyright (C) 1994-2000 Algorithmics Ltd.
*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Nov 7, 2000
* Modification to allow integration with Linux kernel
*
* Kevin D. Kissell, kevink@mips.com and Carsten Langgard, carstenl@mips.com
* Copyright (C) 2000 MIPS Technologies, Inc. All rights reserved.
*/
#ifndef __ARCH_MIPS_MATH_EMU_IEEE754_H
#define __ARCH_MIPS_MATH_EMU_IEEE754_H
#include <linux/compiler.h>
#include <asm/byteorder.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <asm/bitfield.h>
union ieee754dp {
struct {
__BITFIELD_FIELD(unsigned int sign:1,
__BITFIELD_FIELD(unsigned int bexp:11,
__BITFIELD_FIELD(u64 mant:52,
;)))
};
u64 bits;
};
union ieee754sp {
struct {
__BITFIELD_FIELD(unsigned sign:1,
__BITFIELD_FIELD(unsigned bexp:8,
__BITFIELD_FIELD(unsigned mant:23,
;)))
};
u32 bits;
};
/*
* single precision (often aka float)
*/
int ieee754sp_class(union ieee754sp x);
union ieee754sp ieee754sp_abs(union ieee754sp x);
union ieee754sp ieee754sp_neg(union ieee754sp x);
union ieee754sp ieee754sp_add(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_sub(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_mul(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_div(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_fint(int x);
union ieee754sp ieee754sp_flong(s64 x);
union ieee754sp ieee754sp_fdp(union ieee754dp x);
union ieee754sp ieee754sp_rint(union ieee754sp x);
int ieee754sp_tint(union ieee754sp x);
s64 ieee754sp_tlong(union ieee754sp x);
int ieee754sp_cmp(union ieee754sp x, union ieee754sp y, int cop, int sig);
union ieee754sp ieee754sp_sqrt(union ieee754sp x);
union ieee754sp ieee754sp_maddf(union ieee754sp z, union ieee754sp x,
union ieee754sp y);
union ieee754sp ieee754sp_msubf(union ieee754sp z, union ieee754sp x,
union ieee754sp y);
int ieee754sp_2008class(union ieee754sp x);
union ieee754sp ieee754sp_fmin(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_fmax(union ieee754sp x, union ieee754sp y);
union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y);
/*
* double precision (often aka double)
*/
int ieee754dp_class(union ieee754dp x);
union ieee754dp ieee754dp_add(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_sub(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_mul(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_abs(union ieee754dp x);
union ieee754dp ieee754dp_neg(union ieee754dp x);
union ieee754dp ieee754dp_fint(int x);
union ieee754dp ieee754dp_flong(s64 x);
union ieee754dp ieee754dp_fsp(union ieee754sp x);
union ieee754dp ieee754dp_rint(union ieee754dp x);
int ieee754dp_tint(union ieee754dp x);
s64 ieee754dp_tlong(union ieee754dp x);
int ieee754dp_cmp(union ieee754dp x, union ieee754dp y, int cop, int sig);
union ieee754dp ieee754dp_sqrt(union ieee754dp x);
union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
union ieee754dp y);
union ieee754dp ieee754dp_msubf(union ieee754dp z, union ieee754dp x,
union ieee754dp y);
int ieee754dp_2008class(union ieee754dp x);
union ieee754dp ieee754dp_fmin(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_fmax(union ieee754dp x, union ieee754dp y);
union ieee754dp ieee754dp_fmaxa(union ieee754dp x, union ieee754dp y);
/* 5 types of floating point number
*/
enum {
IEEE754_CLASS_NORM = 0x00,
IEEE754_CLASS_ZERO = 0x01,
IEEE754_CLASS_DNORM = 0x02,
IEEE754_CLASS_INF = 0x03,
IEEE754_CLASS_SNAN = 0x04,
IEEE754_CLASS_QNAN = 0x05,
};
/* exception numbers */
#define IEEE754_INEXACT 0x01
#define IEEE754_UNDERFLOW 0x02
#define IEEE754_OVERFLOW 0x04
#define IEEE754_ZERO_DIVIDE 0x08
#define IEEE754_INVALID_OPERATION 0x10
/* cmp operators
*/
#define IEEE754_CLT 0x01
#define IEEE754_CEQ 0x02
#define IEEE754_CGT 0x04
#define IEEE754_CUN 0x08
/*
* The control status register
*/
struct _ieee754_csr {
__BITFIELD_FIELD(unsigned fcc:7, /* condition[7:1] */
__BITFIELD_FIELD(unsigned nod:1, /* set 1 for no denormals */
__BITFIELD_FIELD(unsigned c:1, /* condition[0] */
__BITFIELD_FIELD(unsigned pad0:3,
__BITFIELD_FIELD(unsigned abs2008:1, /* IEEE 754-2008 ABS/NEG.fmt */
__BITFIELD_FIELD(unsigned nan2008:1, /* IEEE 754-2008 NaN mode */
__BITFIELD_FIELD(unsigned cx:6, /* exceptions this operation */
__BITFIELD_FIELD(unsigned mx:5, /* exception enable mask */
__BITFIELD_FIELD(unsigned sx:5, /* exceptions total */
__BITFIELD_FIELD(unsigned rm:2, /* current rounding mode */
;))))))))))
};
#define ieee754_csr (*(struct _ieee754_csr *)(&current->thread.fpu.fcr31))
static inline unsigned ieee754_getrm(void)
{
return (ieee754_csr.rm);
}
static inline unsigned ieee754_setrm(unsigned rm)
{
return (ieee754_csr.rm = rm);
}
/*
* get current exceptions
*/
static inline unsigned ieee754_getcx(void)
{
return (ieee754_csr.cx);
}
/* test for current exception condition
*/
static inline int ieee754_cxtest(unsigned n)
{
return (ieee754_csr.cx & n);
}
/*
* get sticky exceptions
*/
static inline unsigned ieee754_getsx(void)
{
return (ieee754_csr.sx);
}
/* clear sticky conditions
*/
static inline unsigned ieee754_clrsx(void)
{
return (ieee754_csr.sx = 0);
}
/* test for sticky exception condition
*/
static inline int ieee754_sxtest(unsigned n)
{
return (ieee754_csr.sx & n);
}
/* debugging */
union ieee754sp ieee754sp_dump(char *s, union ieee754sp x);
union ieee754dp ieee754dp_dump(char *s, union ieee754dp x);
#define IEEE754_SPCVAL_PZERO 0 /* +0.0 */
#define IEEE754_SPCVAL_NZERO 1 /* -0.0 */
#define IEEE754_SPCVAL_PONE 2 /* +1.0 */
#define IEEE754_SPCVAL_NONE 3 /* -1.0 */
#define IEEE754_SPCVAL_PTEN 4 /* +10.0 */
#define IEEE754_SPCVAL_NTEN 5 /* -10.0 */
#define IEEE754_SPCVAL_PINFINITY 6 /* +inf */
#define IEEE754_SPCVAL_NINFINITY 7 /* -inf */
#define IEEE754_SPCVAL_INDEF_LEG 8 /* legacy quiet NaN */
#define IEEE754_SPCVAL_INDEF_2008 9 /* IEEE 754-2008 quiet NaN */
#define IEEE754_SPCVAL_PMAX 10 /* +max norm */
#define IEEE754_SPCVAL_NMAX 11 /* -max norm */
#define IEEE754_SPCVAL_PMIN 12 /* +min norm */
#define IEEE754_SPCVAL_NMIN 13 /* -min norm */
#define IEEE754_SPCVAL_PMIND 14 /* +min denorm */
#define IEEE754_SPCVAL_NMIND 15 /* -min denorm */
#define IEEE754_SPCVAL_P1E31 16 /* + 1.0e31 */
#define IEEE754_SPCVAL_P1E63 17 /* + 1.0e63 */
extern const union ieee754dp __ieee754dp_spcvals[];
extern const union ieee754sp __ieee754sp_spcvals[];
#define ieee754dp_spcvals ((const union ieee754dp *)__ieee754dp_spcvals)
#define ieee754sp_spcvals ((const union ieee754sp *)__ieee754sp_spcvals)
/*
* Return infinity with given sign
*/
#define ieee754dp_inf(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PINFINITY+(sn)])
#define ieee754dp_zero(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
#define ieee754dp_one(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
#define ieee754dp_ten(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
#define ieee754dp_indef() (ieee754dp_spcvals[IEEE754_SPCVAL_INDEF_LEG + \
ieee754_csr.nan2008])
#define ieee754dp_max(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
#define ieee754dp_min(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
#define ieee754dp_mind(sn) (ieee754dp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
#define ieee754dp_1e31() (ieee754dp_spcvals[IEEE754_SPCVAL_P1E31])
#define ieee754dp_1e63() (ieee754dp_spcvals[IEEE754_SPCVAL_P1E63])
#define ieee754sp_inf(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PINFINITY+(sn)])
#define ieee754sp_zero(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
#define ieee754sp_one(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
#define ieee754sp_ten(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
#define ieee754sp_indef() (ieee754sp_spcvals[IEEE754_SPCVAL_INDEF_LEG + \
ieee754_csr.nan2008])
#define ieee754sp_max(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
#define ieee754sp_min(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
#define ieee754sp_mind(sn) (ieee754sp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
#define ieee754sp_1e31() (ieee754sp_spcvals[IEEE754_SPCVAL_P1E31])
#define ieee754sp_1e63() (ieee754sp_spcvals[IEEE754_SPCVAL_P1E63])
/*
* Indefinite integer value
*/
static inline int ieee754si_indef(void)
{
return ieee754_csr.nan2008 ? 0 : INT_MAX;
}
static inline s64 ieee754di_indef(void)
{
return ieee754_csr.nan2008 ? 0 : S64_MAX;
}
/*
* Overflow integer value
*/
static inline int ieee754si_overflow(int xs)
{
return ieee754_csr.nan2008 && xs ? INT_MIN : INT_MAX;
}
static inline s64 ieee754di_overflow(int xs)
{
return ieee754_csr.nan2008 && xs ? S64_MIN : S64_MAX;
}
/* result types for xctx.rt */
#define IEEE754_RT_SP 0
#define IEEE754_RT_DP 1
#define IEEE754_RT_XP 2
#define IEEE754_RT_SI 3
#define IEEE754_RT_DI 4
/* compat */
#define ieee754dp_fix(x) ieee754dp_tint(x)
#define ieee754sp_fix(x) ieee754sp_tint(x)
#endif /* __ARCH_MIPS_MATH_EMU_IEEE754_H */
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