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linux/arch/powerpc/math-emu/math_efp.c
Joseph Myers 28fbf1d540 powerpc: fix e500 SPE float to integer and fixed-point conversions 
The e500 SPE floating-point emulation code has several problems in how
it handles conversions to integer and fixed-point fractional types.

There are the following 20 relevant instructions.  These can convert
to signed or unsigned 32-bit integers, either rounding towards zero
(as correct for C casts from floating-point to integer) or according
to the current rounding mode, or to signed or unsigned 32-bit
fixed-point values (values in the range [-1, 1) or [0, 1)).  For
conversion from double precision there are also instructions to
convert to 64-bit integers, rounding towards zero, although as far as
I know those instructions are completely theoretical (they are only
defined for implementations that support both SPE and classic 64-bit,
and I'm not aware of any such hardware even though the architecture
definition permits that combination).

#define EFSCTUI		0x2d4
#define EFSCTSI		0x2d5
#define EFSCTUF		0x2d6
#define EFSCTSF		0x2d7
#define EFSCTUIZ	0x2d8
#define EFSCTSIZ	0x2da

#define EVFSCTUI	0x294
#define EVFSCTSI	0x295
#define EVFSCTUF	0x296
#define EVFSCTSF	0x297
#define EVFSCTUIZ	0x298
#define EVFSCTSIZ	0x29a

#define EFDCTUIDZ	0x2ea
#define EFDCTSIDZ	0x2eb

#define EFDCTUI		0x2f4
#define EFDCTSI		0x2f5
#define EFDCTUF		0x2f6
#define EFDCTSF		0x2f7
#define EFDCTUIZ	0x2f8
#define EFDCTSIZ	0x2fa

The emulation code, for the instructions that come in variants
rounding either towards zero or according to the current rounding
direction, uses "if (func & 0x4)" as a condition for using _FP_ROUND
(otherwise _FP_ROUND_ZERO is used).  The condition is correct, but the
code it controls isn't.  Whether _FP_ROUND or _FP_ROUND_ZERO is used
makes no difference, as the effect of those soft-fp macros is to round
an intermediate floating-point result using the low three bits (the
last one sticky) of the working format.  As these operations are
dealing with a freshly unpacked floating-point input, those low bits
are zero and no rounding occurs.  The emulation code then uses the
FP_TO_INT_* macros for the actual integer conversion, with the effect
of always rounding towards zero; for rounding according to the current
rounding direction, it should be using FP_TO_INT_ROUND_*.

The instructions in question have semantics defined (in the Power ISA
documents) for out-of-range values and NaNs: out-of-range values
saturate and NaNs are converted to zero.  The emulation does nothing
to follow those semantics for NaNs (the soft-fp handling is to treat
them as infinities), and messes up the saturation semantics.  For
single-precision conversion to integers, (((func & 0x3) != 0) || SB_s)
is the condition used for doing a signed conversion.  The first part
is correct, but the second isn't: negative numbers should result in
saturation to 0 when converted to unsigned.  Double-precision
conversion to 64-bit integers correctly uses ((func & 0x1) == 0).
Double-precision conversion to 32-bit integers uses (((func & 0x3) !=
0) || DB_s), with correct first part and incorrect second part.  And
vector float conversion to integers uses (((func & 0x3) != 0) ||
SB0_s) (and similar for the other vector element), where the sign bit
check is again wrong.

The incorrect handling of negative numbers converted to unsigned was
introduced in commit afc0a07d4a.  The
rationale given there was a C testcase with cast from float to
unsigned int.  Conversion of out-of-range floating-point numbers to
integer types in C is undefined behavior in the base standard, defined
in Annex F to produce an unspecified value.  That is, the C testcase
used to justify that patch is incorrect - there is no ISO C
requirement for a particular value resulting from this conversion -
and in any case, the correct semantics for such emulation are the
semantics for the instruction (unsigned saturation, which is what it
does in hardware when the emulation is disabled).

The conversion to fixed-point values has its own problems.  That code
doesn't try to do a full emulation; it relies on the trap handler only
being called for arguments that are infinities, NaNs, subnormal or out
of range.  That's fine, but the logic ((vb.wp[1] >> 23) == 0xff &&
((vb.wp[1] & 0x7fffff) > 0)) for NaN detection won't detect negative
NaNs as being NaNs (the same applies for the double-precision case),
and subnormals are mapped to 0 rather than respecting the rounding
mode; the code should also explicitly raise the "invalid" exception.
The code for vectors works by executing the scalar float instruction
with the trapping disabled, meaning at least subnormals won't be
handled correctly.

As well as all those problems in the main emulation code, the rounding
handler - used to emulate rounding upward and downward when not
supported in hardware and when no higher priority exception occurred -
has its own problems.

* It gets called in some cases even for the instructions rounding to
  zero, and then acts according to the current rounding mode when it
  should just leave alone the truncated result provided by hardware.

* It presumes that the result is a single-precision, double-precision
  or single-precision vector as appropriate for the instruction type,
  determines the sign of the result accordingly, and then adjusts the
  result based on that sign and the rounding mode.

  - In the single-precision cases at least the sign determination for
    an integer result is the same as for a floating-point result; in
    the double-precision case, converted to 32-bit integer or fixed
    point, the sign of a double-precision value is in the high part of
    the register but it's the low part of the register that has the
    result of the conversion.

  - If the result is unsigned fixed-point, its sign may be wrongly
    determined as negative (does not actually cause problems, because
    inexact unsigned fixed-point results with the high bit set can
    only appear when converting from double, in which case the sign
    determination is instead wrongly using the high part of the
    register).

  - If the sign of the result is correctly determined as negative, any
    adjustment required to change the truncated result to one correct
    for the rounding mode should be in the opposite direction for
    two's-complement integers as for sign-magnitude floating-point
    values.

  - And if the integer result is zero, the correct sign can only be
    determined by examining the original operand, and not at all (as
    far as I can tell) if the operand and result are the same
    register.

This patch fixes all these problems (as far as possible, given the
inability to determine the correct sign in the rounding handler when
the truncated result is 0, the conversion is to a signed type and the
truncated result has overwritten the original operand).  Conversion to
fixed-point now uses full emulation, and does not use "asm" in the
vector case; the semantics are exactly those of converting to integer
according to the current rounding direction, once the exponent has
been adjusted, so the code makes such an adjustment then uses the
FP_TO_INT_ROUND macros.

The testcase I used for verifying that the instructions (other than
the theoretical conversions to 64-bit integers) produce the correct
results is at <http://lkml.org/lkml/2013/10/8/708>.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
2014-01-07 18:38:59 -06:00

912 lines
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/*
* arch/powerpc/math-emu/math_efp.c
*
* Copyright (C) 2006-2008, 2010 Freescale Semiconductor, Inc.
*
* Author: Ebony Zhu, <ebony.zhu@freescale.com>
* Yu Liu, <yu.liu@freescale.com>
*
* Derived from arch/alpha/math-emu/math.c
* arch/powerpc/math-emu/math.c
*
* Description:
* This file is the exception handler to make E500 SPE instructions
* fully comply with IEEE-754 floating point standard.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/types.h>
#include <asm/uaccess.h>
#include <asm/reg.h>
#define FP_EX_BOOKE_E500_SPE
#include <asm/sfp-machine.h>
#include <math-emu/soft-fp.h>
#include <math-emu/single.h>
#include <math-emu/double.h>
#define EFAPU 0x4
#define VCT 0x4
#define SPFP 0x6
#define DPFP 0x7
#define EFSADD 0x2c0
#define EFSSUB 0x2c1
#define EFSABS 0x2c4
#define EFSNABS 0x2c5
#define EFSNEG 0x2c6
#define EFSMUL 0x2c8
#define EFSDIV 0x2c9
#define EFSCMPGT 0x2cc
#define EFSCMPLT 0x2cd
#define EFSCMPEQ 0x2ce
#define EFSCFD 0x2cf
#define EFSCFSI 0x2d1
#define EFSCTUI 0x2d4
#define EFSCTSI 0x2d5
#define EFSCTUF 0x2d6
#define EFSCTSF 0x2d7
#define EFSCTUIZ 0x2d8
#define EFSCTSIZ 0x2da
#define EVFSADD 0x280
#define EVFSSUB 0x281
#define EVFSABS 0x284
#define EVFSNABS 0x285
#define EVFSNEG 0x286
#define EVFSMUL 0x288
#define EVFSDIV 0x289
#define EVFSCMPGT 0x28c
#define EVFSCMPLT 0x28d
#define EVFSCMPEQ 0x28e
#define EVFSCTUI 0x294
#define EVFSCTSI 0x295
#define EVFSCTUF 0x296
#define EVFSCTSF 0x297
#define EVFSCTUIZ 0x298
#define EVFSCTSIZ 0x29a
#define EFDADD 0x2e0
#define EFDSUB 0x2e1
#define EFDABS 0x2e4
#define EFDNABS 0x2e5
#define EFDNEG 0x2e6
#define EFDMUL 0x2e8
#define EFDDIV 0x2e9
#define EFDCTUIDZ 0x2ea
#define EFDCTSIDZ 0x2eb
#define EFDCMPGT 0x2ec
#define EFDCMPLT 0x2ed
#define EFDCMPEQ 0x2ee
#define EFDCFS 0x2ef
#define EFDCTUI 0x2f4
#define EFDCTSI 0x2f5
#define EFDCTUF 0x2f6
#define EFDCTSF 0x2f7
#define EFDCTUIZ 0x2f8
#define EFDCTSIZ 0x2fa
#define AB 2
#define XA 3
#define XB 4
#define XCR 5
#define NOTYPE 0
#define SIGN_BIT_S (1UL << 31)
#define SIGN_BIT_D (1ULL << 63)
#define FP_EX_MASK (FP_EX_INEXACT | FP_EX_INVALID | FP_EX_DIVZERO | \
FP_EX_UNDERFLOW | FP_EX_OVERFLOW)
static int have_e500_cpu_a005_erratum;
union dw_union {
u64 dp[1];
u32 wp[2];
};
static unsigned long insn_type(unsigned long speinsn)
{
unsigned long ret = NOTYPE;
switch (speinsn & 0x7ff) {
case EFSABS: ret = XA; break;
case EFSADD: ret = AB; break;
case EFSCFD: ret = XB; break;
case EFSCMPEQ: ret = XCR; break;
case EFSCMPGT: ret = XCR; break;
case EFSCMPLT: ret = XCR; break;
case EFSCTSF: ret = XB; break;
case EFSCTSI: ret = XB; break;
case EFSCTSIZ: ret = XB; break;
case EFSCTUF: ret = XB; break;
case EFSCTUI: ret = XB; break;
case EFSCTUIZ: ret = XB; break;
case EFSDIV: ret = AB; break;
case EFSMUL: ret = AB; break;
case EFSNABS: ret = XA; break;
case EFSNEG: ret = XA; break;
case EFSSUB: ret = AB; break;
case EFSCFSI: ret = XB; break;
case EVFSABS: ret = XA; break;
case EVFSADD: ret = AB; break;
case EVFSCMPEQ: ret = XCR; break;
case EVFSCMPGT: ret = XCR; break;
case EVFSCMPLT: ret = XCR; break;
case EVFSCTSF: ret = XB; break;
case EVFSCTSI: ret = XB; break;
case EVFSCTSIZ: ret = XB; break;
case EVFSCTUF: ret = XB; break;
case EVFSCTUI: ret = XB; break;
case EVFSCTUIZ: ret = XB; break;
case EVFSDIV: ret = AB; break;
case EVFSMUL: ret = AB; break;
case EVFSNABS: ret = XA; break;
case EVFSNEG: ret = XA; break;
case EVFSSUB: ret = AB; break;
case EFDABS: ret = XA; break;
case EFDADD: ret = AB; break;
case EFDCFS: ret = XB; break;
case EFDCMPEQ: ret = XCR; break;
case EFDCMPGT: ret = XCR; break;
case EFDCMPLT: ret = XCR; break;
case EFDCTSF: ret = XB; break;
case EFDCTSI: ret = XB; break;
case EFDCTSIDZ: ret = XB; break;
case EFDCTSIZ: ret = XB; break;
case EFDCTUF: ret = XB; break;
case EFDCTUI: ret = XB; break;
case EFDCTUIDZ: ret = XB; break;
case EFDCTUIZ: ret = XB; break;
case EFDDIV: ret = AB; break;
case EFDMUL: ret = AB; break;
case EFDNABS: ret = XA; break;
case EFDNEG: ret = XA; break;
case EFDSUB: ret = AB; break;
}
return ret;
}
int do_spe_mathemu(struct pt_regs *regs)
{
FP_DECL_EX;
int IR, cmp;
unsigned long type, func, fc, fa, fb, src, speinsn;
union dw_union vc, va, vb;
if (get_user(speinsn, (unsigned int __user *) regs->nip))
return -EFAULT;
if ((speinsn >> 26) != EFAPU)
return -EINVAL; /* not an spe instruction */
type = insn_type(speinsn);
if (type == NOTYPE)
goto illegal;
func = speinsn & 0x7ff;
fc = (speinsn >> 21) & 0x1f;
fa = (speinsn >> 16) & 0x1f;
fb = (speinsn >> 11) & 0x1f;
src = (speinsn >> 5) & 0x7;
vc.wp[0] = current->thread.evr[fc];
vc.wp[1] = regs->gpr[fc];
va.wp[0] = current->thread.evr[fa];
va.wp[1] = regs->gpr[fa];
vb.wp[0] = current->thread.evr[fb];
vb.wp[1] = regs->gpr[fb];
__FPU_FPSCR = mfspr(SPRN_SPEFSCR);
pr_debug("speinsn:%08lx spefscr:%08lx\n", speinsn, __FPU_FPSCR);
pr_debug("vc: %08x %08x\n", vc.wp[0], vc.wp[1]);
pr_debug("va: %08x %08x\n", va.wp[0], va.wp[1]);
pr_debug("vb: %08x %08x\n", vb.wp[0], vb.wp[1]);
switch (src) {
case SPFP: {
FP_DECL_S(SA); FP_DECL_S(SB); FP_DECL_S(SR);
switch (type) {
case AB:
case XCR:
FP_UNPACK_SP(SA, va.wp + 1);
case XB:
FP_UNPACK_SP(SB, vb.wp + 1);
break;
case XA:
FP_UNPACK_SP(SA, va.wp + 1);
break;
}
pr_debug("SA: %ld %08lx %ld (%ld)\n", SA_s, SA_f, SA_e, SA_c);
pr_debug("SB: %ld %08lx %ld (%ld)\n", SB_s, SB_f, SB_e, SB_c);
switch (func) {
case EFSABS:
vc.wp[1] = va.wp[1] & ~SIGN_BIT_S;
goto update_regs;
case EFSNABS:
vc.wp[1] = va.wp[1] | SIGN_BIT_S;
goto update_regs;
case EFSNEG:
vc.wp[1] = va.wp[1] ^ SIGN_BIT_S;
goto update_regs;
case EFSADD:
FP_ADD_S(SR, SA, SB);
goto pack_s;
case EFSSUB:
FP_SUB_S(SR, SA, SB);
goto pack_s;
case EFSMUL:
FP_MUL_S(SR, SA, SB);
goto pack_s;
case EFSDIV:
FP_DIV_S(SR, SA, SB);
goto pack_s;
case EFSCMPEQ:
cmp = 0;
goto cmp_s;
case EFSCMPGT:
cmp = 1;
goto cmp_s;
case EFSCMPLT:
cmp = -1;
goto cmp_s;
case EFSCTSF:
case EFSCTUF:
if (SB_c == FP_CLS_NAN) {
vc.wp[1] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
SB_e += (func == EFSCTSF ? 31 : 32);
FP_TO_INT_ROUND_S(vc.wp[1], SB, 32,
(func == EFSCTSF));
}
goto update_regs;
case EFSCFD: {
FP_DECL_D(DB);
FP_CLEAR_EXCEPTIONS;
FP_UNPACK_DP(DB, vb.dp);
pr_debug("DB: %ld %08lx %08lx %ld (%ld)\n",
DB_s, DB_f1, DB_f0, DB_e, DB_c);
FP_CONV(S, D, 1, 2, SR, DB);
goto pack_s;
}
case EFSCTSI:
case EFSCTUI:
if (SB_c == FP_CLS_NAN) {
vc.wp[1] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
FP_TO_INT_ROUND_S(vc.wp[1], SB, 32,
((func & 0x3) != 0));
}
goto update_regs;
case EFSCTSIZ:
case EFSCTUIZ:
if (SB_c == FP_CLS_NAN) {
vc.wp[1] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
FP_TO_INT_S(vc.wp[1], SB, 32,
((func & 0x3) != 0));
}
goto update_regs;
default:
goto illegal;
}
break;
pack_s:
pr_debug("SR: %ld %08lx %ld (%ld)\n", SR_s, SR_f, SR_e, SR_c);
FP_PACK_SP(vc.wp + 1, SR);
goto update_regs;
cmp_s:
FP_CMP_S(IR, SA, SB, 3);
if (IR == 3 && (FP_ISSIGNAN_S(SA) || FP_ISSIGNAN_S(SB)))
FP_SET_EXCEPTION(FP_EX_INVALID);
if (IR == cmp) {
IR = 0x4;
} else {
IR = 0;
}
goto update_ccr;
}
case DPFP: {
FP_DECL_D(DA); FP_DECL_D(DB); FP_DECL_D(DR);
switch (type) {
case AB:
case XCR:
FP_UNPACK_DP(DA, va.dp);
case XB:
FP_UNPACK_DP(DB, vb.dp);
break;
case XA:
FP_UNPACK_DP(DA, va.dp);
break;
}
pr_debug("DA: %ld %08lx %08lx %ld (%ld)\n",
DA_s, DA_f1, DA_f0, DA_e, DA_c);
pr_debug("DB: %ld %08lx %08lx %ld (%ld)\n",
DB_s, DB_f1, DB_f0, DB_e, DB_c);
switch (func) {
case EFDABS:
vc.dp[0] = va.dp[0] & ~SIGN_BIT_D;
goto update_regs;
case EFDNABS:
vc.dp[0] = va.dp[0] | SIGN_BIT_D;
goto update_regs;
case EFDNEG:
vc.dp[0] = va.dp[0] ^ SIGN_BIT_D;
goto update_regs;
case EFDADD:
FP_ADD_D(DR, DA, DB);
goto pack_d;
case EFDSUB:
FP_SUB_D(DR, DA, DB);
goto pack_d;
case EFDMUL:
FP_MUL_D(DR, DA, DB);
goto pack_d;
case EFDDIV:
FP_DIV_D(DR, DA, DB);
goto pack_d;
case EFDCMPEQ:
cmp = 0;
goto cmp_d;
case EFDCMPGT:
cmp = 1;
goto cmp_d;
case EFDCMPLT:
cmp = -1;
goto cmp_d;
case EFDCTSF:
case EFDCTUF:
if (DB_c == FP_CLS_NAN) {
vc.wp[1] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
DB_e += (func == EFDCTSF ? 31 : 32);
FP_TO_INT_ROUND_D(vc.wp[1], DB, 32,
(func == EFDCTSF));
}
goto update_regs;
case EFDCFS: {
FP_DECL_S(SB);
FP_CLEAR_EXCEPTIONS;
FP_UNPACK_SP(SB, vb.wp + 1);
pr_debug("SB: %ld %08lx %ld (%ld)\n",
SB_s, SB_f, SB_e, SB_c);
FP_CONV(D, S, 2, 1, DR, SB);
goto pack_d;
}
case EFDCTUIDZ:
case EFDCTSIDZ:
if (DB_c == FP_CLS_NAN) {
vc.dp[0] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
FP_TO_INT_D(vc.dp[0], DB, 64,
((func & 0x1) == 0));
}
goto update_regs;
case EFDCTUI:
case EFDCTSI:
if (DB_c == FP_CLS_NAN) {
vc.wp[1] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
FP_TO_INT_ROUND_D(vc.wp[1], DB, 32,
((func & 0x3) != 0));
}
goto update_regs;
case EFDCTUIZ:
case EFDCTSIZ:
if (DB_c == FP_CLS_NAN) {
vc.wp[1] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
FP_TO_INT_D(vc.wp[1], DB, 32,
((func & 0x3) != 0));
}
goto update_regs;
default:
goto illegal;
}
break;
pack_d:
pr_debug("DR: %ld %08lx %08lx %ld (%ld)\n",
DR_s, DR_f1, DR_f0, DR_e, DR_c);
FP_PACK_DP(vc.dp, DR);
goto update_regs;
cmp_d:
FP_CMP_D(IR, DA, DB, 3);
if (IR == 3 && (FP_ISSIGNAN_D(DA) || FP_ISSIGNAN_D(DB)))
FP_SET_EXCEPTION(FP_EX_INVALID);
if (IR == cmp) {
IR = 0x4;
} else {
IR = 0;
}
goto update_ccr;
}
case VCT: {
FP_DECL_S(SA0); FP_DECL_S(SB0); FP_DECL_S(SR0);
FP_DECL_S(SA1); FP_DECL_S(SB1); FP_DECL_S(SR1);
int IR0, IR1;
switch (type) {
case AB:
case XCR:
FP_UNPACK_SP(SA0, va.wp);
FP_UNPACK_SP(SA1, va.wp + 1);
case XB:
FP_UNPACK_SP(SB0, vb.wp);
FP_UNPACK_SP(SB1, vb.wp + 1);
break;
case XA:
FP_UNPACK_SP(SA0, va.wp);
FP_UNPACK_SP(SA1, va.wp + 1);
break;
}
pr_debug("SA0: %ld %08lx %ld (%ld)\n",
SA0_s, SA0_f, SA0_e, SA0_c);
pr_debug("SA1: %ld %08lx %ld (%ld)\n",
SA1_s, SA1_f, SA1_e, SA1_c);
pr_debug("SB0: %ld %08lx %ld (%ld)\n",
SB0_s, SB0_f, SB0_e, SB0_c);
pr_debug("SB1: %ld %08lx %ld (%ld)\n",
SB1_s, SB1_f, SB1_e, SB1_c);
switch (func) {
case EVFSABS:
vc.wp[0] = va.wp[0] & ~SIGN_BIT_S;
vc.wp[1] = va.wp[1] & ~SIGN_BIT_S;
goto update_regs;
case EVFSNABS:
vc.wp[0] = va.wp[0] | SIGN_BIT_S;
vc.wp[1] = va.wp[1] | SIGN_BIT_S;
goto update_regs;
case EVFSNEG:
vc.wp[0] = va.wp[0] ^ SIGN_BIT_S;
vc.wp[1] = va.wp[1] ^ SIGN_BIT_S;
goto update_regs;
case EVFSADD:
FP_ADD_S(SR0, SA0, SB0);
FP_ADD_S(SR1, SA1, SB1);
goto pack_vs;
case EVFSSUB:
FP_SUB_S(SR0, SA0, SB0);
FP_SUB_S(SR1, SA1, SB1);
goto pack_vs;
case EVFSMUL:
FP_MUL_S(SR0, SA0, SB0);
FP_MUL_S(SR1, SA1, SB1);
goto pack_vs;
case EVFSDIV:
FP_DIV_S(SR0, SA0, SB0);
FP_DIV_S(SR1, SA1, SB1);
goto pack_vs;
case EVFSCMPEQ:
cmp = 0;
goto cmp_vs;
case EVFSCMPGT:
cmp = 1;
goto cmp_vs;
case EVFSCMPLT:
cmp = -1;
goto cmp_vs;
case EVFSCTUF:
case EVFSCTSF:
if (SB0_c == FP_CLS_NAN) {
vc.wp[0] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
SB0_e += (func == EVFSCTSF ? 31 : 32);
FP_TO_INT_ROUND_S(vc.wp[0], SB0, 32,
(func == EVFSCTSF));
}
if (SB1_c == FP_CLS_NAN) {
vc.wp[1] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
SB1_e += (func == EVFSCTSF ? 31 : 32);
FP_TO_INT_ROUND_S(vc.wp[1], SB1, 32,
(func == EVFSCTSF));
}
goto update_regs;
case EVFSCTUI:
case EVFSCTSI:
if (SB0_c == FP_CLS_NAN) {
vc.wp[0] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
FP_TO_INT_ROUND_S(vc.wp[0], SB0, 32,
((func & 0x3) != 0));
}
if (SB1_c == FP_CLS_NAN) {
vc.wp[1] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
FP_TO_INT_ROUND_S(vc.wp[1], SB1, 32,
((func & 0x3) != 0));
}
goto update_regs;
case EVFSCTUIZ:
case EVFSCTSIZ:
if (SB0_c == FP_CLS_NAN) {
vc.wp[0] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
FP_TO_INT_S(vc.wp[0], SB0, 32,
((func & 0x3) != 0));
}
if (SB1_c == FP_CLS_NAN) {
vc.wp[1] = 0;
FP_SET_EXCEPTION(FP_EX_INVALID);
} else {
FP_TO_INT_S(vc.wp[1], SB1, 32,
((func & 0x3) != 0));
}
goto update_regs;
default:
goto illegal;
}
break;
pack_vs:
pr_debug("SR0: %ld %08lx %ld (%ld)\n",
SR0_s, SR0_f, SR0_e, SR0_c);
pr_debug("SR1: %ld %08lx %ld (%ld)\n",
SR1_s, SR1_f, SR1_e, SR1_c);
FP_PACK_SP(vc.wp, SR0);
FP_PACK_SP(vc.wp + 1, SR1);
goto update_regs;
cmp_vs:
{
int ch, cl;
FP_CMP_S(IR0, SA0, SB0, 3);
FP_CMP_S(IR1, SA1, SB1, 3);
if (IR0 == 3 && (FP_ISSIGNAN_S(SA0) || FP_ISSIGNAN_S(SB0)))
FP_SET_EXCEPTION(FP_EX_INVALID);
if (IR1 == 3 && (FP_ISSIGNAN_S(SA1) || FP_ISSIGNAN_S(SB1)))
FP_SET_EXCEPTION(FP_EX_INVALID);
ch = (IR0 == cmp) ? 1 : 0;
cl = (IR1 == cmp) ? 1 : 0;
IR = (ch << 3) | (cl << 2) | ((ch | cl) << 1) |
((ch & cl) << 0);
goto update_ccr;
}
}
default:
return -EINVAL;
}
update_ccr:
regs->ccr &= ~(15 << ((7 - ((speinsn >> 23) & 0x7)) << 2));
regs->ccr |= (IR << ((7 - ((speinsn >> 23) & 0x7)) << 2));
update_regs:
/*
* If the "invalid" exception sticky bit was set by the
* processor for non-finite input, but was not set before the
* instruction being emulated, clear it. Likewise for the
* "underflow" bit, which may have been set by the processor
* for exact underflow, not just inexact underflow when the
* flag should be set for IEEE 754 semantics. Other sticky
* exceptions will only be set by the processor when they are
* correct according to IEEE 754 semantics, and we must not
* clear sticky bits that were already set before the emulated
* instruction as they represent the user-visible sticky
* exception status. "inexact" traps to kernel are not
* required for IEEE semantics and are not enabled by default,
* so the "inexact" sticky bit may have been set by a previous
* instruction without the kernel being aware of it.
*/
__FPU_FPSCR
&= ~(FP_EX_INVALID | FP_EX_UNDERFLOW) | current->thread.spefscr_last;
__FPU_FPSCR |= (FP_CUR_EXCEPTIONS & FP_EX_MASK);
mtspr(SPRN_SPEFSCR, __FPU_FPSCR);
current->thread.spefscr_last = __FPU_FPSCR;
current->thread.evr[fc] = vc.wp[0];
regs->gpr[fc] = vc.wp[1];
pr_debug("ccr = %08lx\n", regs->ccr);
pr_debug("cur exceptions = %08x spefscr = %08lx\n",
FP_CUR_EXCEPTIONS, __FPU_FPSCR);
pr_debug("vc: %08x %08x\n", vc.wp[0], vc.wp[1]);
pr_debug("va: %08x %08x\n", va.wp[0], va.wp[1]);
pr_debug("vb: %08x %08x\n", vb.wp[0], vb.wp[1]);
return 0;
illegal:
if (have_e500_cpu_a005_erratum) {
/* according to e500 cpu a005 erratum, reissue efp inst */
regs->nip -= 4;
pr_debug("re-issue efp inst: %08lx\n", speinsn);
return 0;
}
printk(KERN_ERR "\nOoops! IEEE-754 compliance handler encountered un-supported instruction.\ninst code: %08lx\n", speinsn);
return -ENOSYS;
}
int speround_handler(struct pt_regs *regs)
{
union dw_union fgpr;
int s_lo, s_hi;
int lo_inexact, hi_inexact;
int fp_result;
unsigned long speinsn, type, fb, fc, fptype, func;
if (get_user(speinsn, (unsigned int __user *) regs->nip))
return -EFAULT;
if ((speinsn >> 26) != 4)
return -EINVAL; /* not an spe instruction */
func = speinsn & 0x7ff;
type = insn_type(func);
if (type == XCR) return -ENOSYS;
__FPU_FPSCR = mfspr(SPRN_SPEFSCR);
pr_debug("speinsn:%08lx spefscr:%08lx\n", speinsn, __FPU_FPSCR);
fptype = (speinsn >> 5) & 0x7;
/* No need to round if the result is exact */
lo_inexact = __FPU_FPSCR & (SPEFSCR_FG | SPEFSCR_FX);
hi_inexact = __FPU_FPSCR & (SPEFSCR_FGH | SPEFSCR_FXH);
if (!(lo_inexact || (hi_inexact && fptype == VCT)))
return 0;
fc = (speinsn >> 21) & 0x1f;
s_lo = regs->gpr[fc] & SIGN_BIT_S;
s_hi = current->thread.evr[fc] & SIGN_BIT_S;
fgpr.wp[0] = current->thread.evr[fc];
fgpr.wp[1] = regs->gpr[fc];
fb = (speinsn >> 11) & 0x1f;
switch (func) {
case EFSCTUIZ:
case EFSCTSIZ:
case EVFSCTUIZ:
case EVFSCTSIZ:
case EFDCTUIDZ:
case EFDCTSIDZ:
case EFDCTUIZ:
case EFDCTSIZ:
/*
* These instructions always round to zero,
* independent of the rounding mode.
*/
return 0;
case EFSCTUI:
case EFSCTUF:
case EVFSCTUI:
case EVFSCTUF:
case EFDCTUI:
case EFDCTUF:
fp_result = 0;
s_lo = 0;
s_hi = 0;
break;
case EFSCTSI:
case EFSCTSF:
fp_result = 0;
/* Recover the sign of a zero result if possible. */
if (fgpr.wp[1] == 0)
s_lo = regs->gpr[fb] & SIGN_BIT_S;
break;
case EVFSCTSI:
case EVFSCTSF:
fp_result = 0;
/* Recover the sign of a zero result if possible. */
if (fgpr.wp[1] == 0)
s_lo = regs->gpr[fb] & SIGN_BIT_S;
if (fgpr.wp[0] == 0)
s_hi = current->thread.evr[fb] & SIGN_BIT_S;
break;
case EFDCTSI:
case EFDCTSF:
fp_result = 0;
s_hi = s_lo;
/* Recover the sign of a zero result if possible. */
if (fgpr.wp[1] == 0)
s_hi = current->thread.evr[fb] & SIGN_BIT_S;
break;
default:
fp_result = 1;
break;
}
pr_debug("round fgpr: %08x %08x\n", fgpr.wp[0], fgpr.wp[1]);
switch (fptype) {
/* Since SPE instructions on E500 core can handle round to nearest
* and round toward zero with IEEE-754 complied, we just need
* to handle round toward +Inf and round toward -Inf by software.
*/
case SPFP:
if ((FP_ROUNDMODE) == FP_RND_PINF) {
if (!s_lo) fgpr.wp[1]++; /* Z > 0, choose Z1 */
} else { /* round to -Inf */
if (s_lo) {
if (fp_result)
fgpr.wp[1]++; /* Z < 0, choose Z2 */
else
fgpr.wp[1]--; /* Z < 0, choose Z2 */
}
}
break;
case DPFP:
if (FP_ROUNDMODE == FP_RND_PINF) {
if (!s_hi) {
if (fp_result)
fgpr.dp[0]++; /* Z > 0, choose Z1 */
else
fgpr.wp[1]++; /* Z > 0, choose Z1 */
}
} else { /* round to -Inf */
if (s_hi) {
if (fp_result)
fgpr.dp[0]++; /* Z < 0, choose Z2 */
else
fgpr.wp[1]--; /* Z < 0, choose Z2 */
}
}
break;
case VCT:
if (FP_ROUNDMODE == FP_RND_PINF) {
if (lo_inexact && !s_lo)
fgpr.wp[1]++; /* Z_low > 0, choose Z1 */
if (hi_inexact && !s_hi)
fgpr.wp[0]++; /* Z_high word > 0, choose Z1 */
} else { /* round to -Inf */
if (lo_inexact && s_lo) {
if (fp_result)
fgpr.wp[1]++; /* Z_low < 0, choose Z2 */
else
fgpr.wp[1]--; /* Z_low < 0, choose Z2 */
}
if (hi_inexact && s_hi) {
if (fp_result)
fgpr.wp[0]++; /* Z_high < 0, choose Z2 */
else
fgpr.wp[0]--; /* Z_high < 0, choose Z2 */
}
}
break;
default:
return -EINVAL;
}
current->thread.evr[fc] = fgpr.wp[0];
regs->gpr[fc] = fgpr.wp[1];
pr_debug(" to fgpr: %08x %08x\n", fgpr.wp[0], fgpr.wp[1]);
return 0;
}
int __init spe_mathemu_init(void)
{
u32 pvr, maj, min;
pvr = mfspr(SPRN_PVR);
if ((PVR_VER(pvr) == PVR_VER_E500V1) ||
(PVR_VER(pvr) == PVR_VER_E500V2)) {
maj = PVR_MAJ(pvr);
min = PVR_MIN(pvr);
/*
* E500 revision below 1.1, 2.3, 3.1, 4.1, 5.1
* need cpu a005 errata workaround
*/
switch (maj) {
case 1:
if (min < 1)
have_e500_cpu_a005_erratum = 1;
break;
case 2:
if (min < 3)
have_e500_cpu_a005_erratum = 1;
break;
case 3:
case 4:
case 5:
if (min < 1)
have_e500_cpu_a005_erratum = 1;
break;
default:
break;
}
}
return 0;
}
module_init(spe_mathemu_init);
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