// SPDX-License-Identifier: GPL-2.0
/*---------------------------------------------------------------------------+
| errors.c |
| |
| The error handling functions for wm-FPU-emu |
| |
| Copyright (C) 1992,1993,1994,1996 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
| E-mail billm@jacobi.maths.monash.edu.au |
| |
| |
+---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------+
| Note: |
| The file contains code which accesses user memory. |
| Emulator static data may change when user memory is accessed, due to |
| other processes using the emulator while swapping is in progress. |
+---------------------------------------------------------------------------*/
#include <linux/signal.h>
#include <linux/uaccess.h>
#include "fpu_emu.h"
#include "fpu_system.h"
#include "exception.h"
#include "status_w.h"
#include "control_w.h"
#include "reg_constant.h"
#include "version.h"
/* */
#undef PRINT_MESSAGES
/* */
#if 0
void Un_impl(void)
{
u_char byte1, FPU_modrm;
unsigned long address = FPU_ORIG_EIP;
RE_ENTRANT_CHECK_OFF;
/* No need to check access_ok(), we have previously fetched these bytes. */
printk("Unimplemented FPU Opcode at eip=%p : ", (void __user *)address);
if (FPU_CS == __USER_CS) {
while (1) {
FPU_get_user(byte1, (u_char __user *) address);
if ((byte1 & 0xf8) == 0xd8)
break;
printk("[%02x]", byte1);
address++;
}
printk("%02x ", byte1);
FPU_get_user(FPU_modrm, 1 + (u_char __user *) address);
if (FPU_modrm >= 0300)
printk("%02x (%02x+%d)\n", FPU_modrm, FPU_modrm & 0xf8,
FPU_modrm & 7);
else
printk("/%d\n", (FPU_modrm >> 3) & 7);
} else {
printk("cs selector = %04x\n", FPU_CS);
}
RE_ENTRANT_CHECK_ON;
EXCEPTION(EX_Invalid);
}
#endif /* 0 */
/*
Called for opcodes which are illegal and which are known to result in a
SIGILL with a real 80486.
*/
void FPU_illegal(void)
{
math_abort(FPU_info, SIGILL);
}
void FPU_printall(void)
{
int i;
static const char *tag_desc[] = { "Valid", "Zero", "ERROR", "Empty",
"DeNorm", "Inf", "NaN"
};
u_char byte1, FPU_modrm;
unsigned long address = FPU_ORIG_EIP;
RE_ENTRANT_CHECK_OFF;
/* No need to check access_ok(), we have previously fetched these bytes. */
printk("At %p:", (void *)address);
if (FPU_CS == __USER_CS) {
#define MAX_PRINTED_BYTES 20
for (i = 0; i < MAX_PRINTED_BYTES; i++) {
FPU_get_user(byte1, (u_char __user *) address);
if ((byte1 & 0xf8) == 0xd8) {
printk(" %02x", byte1);
break;
}
printk(" [%02x]", byte1);
address++;
}
if (i == MAX_PRINTED_BYTES)
printk(" [more..]\n");
else {
FPU_get_user(FPU_modrm, 1 + (u_char __user *) address);
if (FPU_modrm >= 0300)
printk(" %02x (%02x+%d)\n", FPU_modrm,
FPU_modrm & 0xf8, FPU_modrm & 7);
else
printk(" /%d, mod=%d rm=%d\n",
(FPU_modrm >> 3) & 7,
(FPU_modrm >> 6) & 3, FPU_modrm & 7);
}
} else {
printk("%04x\n", FPU_CS);
}
partial_status = status_word();
#ifdef DEBUGGING
if (partial_status & SW_Backward)
printk("SW: backward compatibility\n");
if (partial_status & SW_C3)
printk("SW: condition bit 3\n");
if (partial_status & SW_C2)
printk("SW: condition bit 2\n");
if (partial_status & SW_C1)
printk("SW: condition bit 1\n");
if (partial_status & SW_C0)
printk("SW: condition bit 0\n");
if (partial_status & SW_Summary)
printk("SW: exception summary\n");
if (partial_status & SW_Stack_Fault)
printk("SW: stack fault\n");
if (partial_status & SW_Precision)
printk("SW: loss of precision\n");
if (partial_status & SW_Underflow)
printk("SW: underflow\n");
if (partial_status & SW_Overflow)
printk("SW: overflow\n");
if (partial_status & SW_Zero_Div)
printk("SW: divide by zero\n");
if (partial_status & SW_Denorm_Op)
printk("SW: denormalized operand\n");
if (partial_status & SW_Invalid)
printk("SW: invalid operation\n");
#endif /* DEBUGGING */
printk(" SW: b=%d st=%d es=%d sf=%d cc=%d%d%d%d ef=%d%d%d%d%d%d\n", partial_status & 0x8000 ? 1 : 0, /* busy */
(partial_status & 0x3800) >> 11, /* stack top pointer */
partial_status & 0x80 ? 1 : 0, /* Error summary status */
partial_status & 0x40 ? 1 : 0, /* Stack flag */
partial_status & SW_C3 ? 1 : 0, partial_status & SW_C2 ? 1 : 0, /* cc */
partial_status & SW_C1 ? 1 : 0, partial_status & SW_C0 ? 1 : 0, /* cc */
partial_status & SW_Precision ? 1 : 0,
partial_status & SW_Underflow ? 1 : 0,
partial_status & SW_Overflow ? 1 : 0,
partial_status & SW_Zero_Div ? 1 : 0,
partial_status & SW_Denorm_Op ? 1 : 0,
partial_status & SW_Invalid ? 1 : 0);
printk(" CW: ic=%d rc=%d%d pc=%d%d iem=%d ef=%d%d%d%d%d%d\n",
control_word & 0x1000 ? 1 : 0,
(control_word & 0x800) >> 11, (control_word & 0x400) >> 10,
(control_word & 0x200) >> 9, (control_word & 0x100) >> 8,
control_word & 0x80 ? 1 : 0,
control_word & SW_Precision ? 1 : 0,
control_word & SW_Underflow ? 1 : 0,
control_word & SW_Overflow ? 1 : 0,
control_word & SW_Zero_Div ? 1 : 0,
control_word & SW_Denorm_Op ? 1 : 0,
control_word & SW_Invalid ? 1 : 0);
for (i = 0; i < 8; i++) {
FPU_REG *r = &st(i);
u_char tagi = FPU_gettagi(i);
switch (tagi) {
case TAG_Empty:
continue;
case TAG_Zero:
case TAG_Special:
/* Update tagi for the printk below */
tagi = FPU_Special(r);
fallthrough;
case TAG_Valid:
printk("st(%d) %c .%04lx %04lx %04lx %04lx e%+-6d ", i,
getsign(r) ? '-' : '+',
(long)(r->sigh >> 16),
(long)(r->sigh & 0xFFFF),
(long)(r->sigl >> 16),
(long)(r->sigl & 0xFFFF),
exponent(r) - EXP_BIAS + 1);
break;
default:
printk("Whoops! Error in errors.c: tag%d is %d ", i,
tagi);
continue;
}
printk("%s\n", tag_desc[(int)(unsigned)tagi]);
}
RE_ENTRANT_CHECK_ON;
}
static struct {
int type;
const char *name;
} exception_names[] = {
{
EX_StackOver, "stack overflow"}, {
EX_StackUnder, "stack underflow"}, {
EX_Precision, "loss of precision"}, {
EX_Underflow, "underflow"}, {
EX_Overflow, "overflow"}, {
EX_ZeroDiv, "divide by zero"}, {
EX_Denormal, "denormalized operand"}, {
EX_Invalid, "invalid operation"}, {
EX_INTERNAL, "INTERNAL BUG in " FPU_VERSION}, {
0, NULL}
};
/*
EX_INTERNAL is always given with a code which indicates where the
error was detected.
Internal error types:
0x14 in fpu_etc.c
0x1nn in a *.c file:
0x101 in reg_add_sub.c
0x102 in reg_mul.c
0x104 in poly_atan.c
0x105 in reg_mul.c
0x107 in fpu_trig.c
0x108 in reg_compare.c
0x109 in reg_compare.c
0x110 in reg_add_sub.c
0x111 in fpe_entry.c
0x112 in fpu_trig.c
0x113 in errors.c
0x115 in fpu_trig.c
0x116 in fpu_trig.c
0x117 in fpu_trig.c
0x118 in fpu_trig.c
0x119 in fpu_trig.c
0x120 in poly_atan.c
0x121 in reg_compare.c
0x122 in reg_compare.c
0x123 in reg_compare.c
0x125 in fpu_trig.c
0x126 in fpu_entry.c
0x127 in poly_2xm1.c
0x128 in fpu_entry.c
0x129 in fpu_entry.c
0x130 in get_address.c
0x131 in get_address.c
0x132 in get_address.c
0x133 in get_address.c
0x140 in load_store.c
0x141 in load_store.c
0x150 in poly_sin.c
0x151 in poly_sin.c
0x160 in reg_ld_str.c
0x161 in reg_ld_str.c
0x162 in reg_ld_str.c
0x163 in reg_ld_str.c
0x164 in reg_ld_str.c
0x170 in fpu_tags.c
0x171 in fpu_tags.c
0x172 in fpu_tags.c
0x180 in reg_convert.c
0x2nn in an *.S file:
0x201 in reg_u_add.S
0x202 in reg_u_div.S
0x203 in reg_u_div.S
0x204 in reg_u_div.S
0x205 in reg_u_mul.S
0x206 in reg_u_sub.S
0x207 in wm_sqrt.S
0x208 in reg_div.S
0x209 in reg_u_sub.S
0x210 in reg_u_sub.S
0x211 in reg_u_sub.S
0x212 in reg_u_sub.S
0x213 in wm_sqrt.S
0x214 in wm_sqrt.S
0x215 in wm_sqrt.S
0x220 in reg_norm.S
0x221 in reg_norm.S
0x230 in reg_round.S
0x231 in reg_round.S
0x232 in reg_round.S
0x233 in reg_round.S
0x234 in reg_round.S
0x235 in reg_round.S
0x236 in reg_round.S
0x240 in div_Xsig.S
0x241 in div_Xsig.S
0x242 in div_Xsig.S
*/
asmlinkage __visible void FPU_exception(int n)
{
int i, int_type;
int_type = 0; /* Needed only to stop compiler warnings */
if (n & EX_INTERNAL) {
int_type = n - EX_INTERNAL;
n = EX_INTERNAL;
/* Set lots of exception bits! */
partial_status |= (SW_Exc_Mask | SW_Summary | SW_Backward);
} else {
/* Extract only the bits which we use to set the status word */
n &= (SW_Exc_Mask);
/* Set the corresponding exception bit */
partial_status |= n;
/* Set summary bits iff exception isn't masked */
if (partial_status & ~control_word & CW_Exceptions)
partial_status |= (SW_Summary | SW_Backward);
if (n & (SW_Stack_Fault | EX_Precision)) {
if (!(n & SW_C1))
/* This bit distinguishes over- from underflow for a stack fault,
and roundup from round-down for precision loss. */
partial_status &= ~SW_C1;
}
}
RE_ENTRANT_CHECK_OFF;
if ((~control_word & n & CW_Exceptions) || (n == EX_INTERNAL)) {
/* Get a name string for error reporting */
for (i = 0; exception_names[i].type; i++)
if ((exception_names[i].type & n) ==
exception_names[i].type)
break;
if (exception_names[i].type) {
#ifdef PRINT_MESSAGES
printk("FP Exception: %s!\n", exception_names[i].name);
#endif /* PRINT_MESSAGES */
} else
printk("FPU emulator: Unknown Exception: 0x%04x!\n", n);
if (n == EX_INTERNAL) {
printk("FPU emulator: Internal error type 0x%04x\n",
int_type);
FPU_printall();
}
#ifdef PRINT_MESSAGES
else
FPU_printall();
#endif /* PRINT_MESSAGES */
/*
* The 80486 generates an interrupt on the next non-control FPU
* instruction. So we need some means of flagging it.
* We use the ES (Error Summary) bit for this.
*/
}
RE_ENTRANT_CHECK_ON;
#ifdef __DEBUG__
math_abort(FPU_info, SIGFPE);
#endif /* __DEBUG__ */
}
/* Real operation attempted on a NaN. */
/* Returns < 0 if the exception is unmasked */
int real_1op_NaN(FPU_REG *a)
{
int signalling, isNaN;
isNaN = (exponent(a) == EXP_OVER) && (a->sigh & 0x80000000);
/* The default result for the case of two "equal" NaNs (signs may
differ) is chosen to reproduce 80486 behaviour */
signalling = isNaN && !(a->sigh & 0x40000000);
if (!signalling) {
if (!isNaN) { /* pseudo-NaN, or other unsupported? */
if (control_word & CW_Invalid) {
/* Masked response */
reg_copy(&CONST_QNaN, a);
}
EXCEPTION(EX_Invalid);
return (!(control_word & CW_Invalid) ? FPU_Exception :
0) | TAG_Special;
}
return TAG_Special;
}
if (control_word & CW_Invalid) {
/* The masked response */
if (!(a->sigh & 0x80000000)) { /* pseudo-NaN ? */
reg_copy(&CONST_QNaN, a);
}
/* ensure a Quiet NaN */
a->sigh |= 0x40000000;
}
EXCEPTION(EX_Invalid);
return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special;
}
/* Real operation attempted on two operands, one a NaN. */
/* Returns < 0 if the exception is unmasked */
int real_2op_NaN(FPU_REG const *b, u_char tagb,
int deststnr, FPU_REG const *defaultNaN)
{
FPU_REG *dest = &st(deststnr);
FPU_REG const *a = dest;
u_char taga = FPU_gettagi(deststnr);
FPU_REG const *x;
int signalling, unsupported;
if (taga == TAG_Special)
taga = FPU_Special(a);
if (tagb == TAG_Special)
tagb = FPU_Special(b);
/* TW_NaN is also used for unsupported data types. */
unsupported = ((taga == TW_NaN)
&& !((exponent(a) == EXP_OVER)
&& (a->sigh & 0x80000000)))
|| ((tagb == TW_NaN)
&& !((exponent(b) == EXP_OVER) && (b->sigh & 0x80000000)));
if (unsupported) {
if (control_word & CW_Invalid) {
/* Masked response */
FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr);
}
EXCEPTION(EX_Invalid);
return (!(control_word & CW_Invalid) ? FPU_Exception : 0) |
TAG_Special;
}
if (taga == TW_NaN) {
x = a;
if (tagb == TW_NaN) {
signalling = !(a->sigh & b->sigh & 0x40000000);
if (significand(b) > significand(a))
x = b;
else if (significand(b) == significand(a)) {
/* The default result for the case of two "equal" NaNs (signs may
differ) is chosen to reproduce 80486 behaviour */
x = defaultNaN;
}
} else {
/* return the quiet version of the NaN in a */
signalling = !(a->sigh & 0x40000000);
}
} else
#ifdef PARANOID
if (tagb == TW_NaN)
#endif /* PARANOID */
{
signalling = !(b->sigh & 0x40000000);
x = b;
}
#ifdef PARANOID
else {
signalling = 0;
EXCEPTION(EX_INTERNAL | 0x113);
x = &CONST_QNaN;
}
#endif /* PARANOID */
if ((!signalling) || (control_word & CW_Invalid)) {
if (!x)
x = b;
if (!(x->sigh & 0x80000000)) /* pseudo-NaN ? */
x = &CONST_QNaN;
FPU_copy_to_regi(x, TAG_Special, deststnr);
if (!signalling)
return TAG_Special;
/* ensure a Quiet NaN */
dest->sigh |= 0x40000000;
}
EXCEPTION(EX_Invalid);
return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special;
}
/* Invalid arith operation on Valid registers */
/* Returns < 0 if the exception is unmasked */
asmlinkage __visible int arith_invalid(int deststnr)
{
EXCEPTION(EX_Invalid);
if (control_word & CW_Invalid) {
/* The masked response */
FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr);
}
return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Valid;
}
/* Divide a finite number by zero */
asmlinkage __visible int FPU_divide_by_zero(int deststnr, u_char sign)
{
FPU_REG *dest = &st(deststnr);
int tag = TAG_Valid;
if (control_word & CW_ZeroDiv) {
/* The masked response */
FPU_copy_to_regi(&CONST_INF, TAG_Special, deststnr);
setsign(dest, sign);
tag = TAG_Special;
}
EXCEPTION(EX_ZeroDiv);
return (!(control_word & CW_ZeroDiv) ? FPU_Exception : 0) | tag;
}
/* This may be called often, so keep it lean */
int set_precision_flag(int flags)
{
if (control_word & CW_Precision) {
partial_status &= ~(SW_C1 & flags);
partial_status |= flags; /* The masked response */
return 0;
} else {
EXCEPTION(flags);
return 1;
}
}
/* This may be called often, so keep it lean */
asmlinkage __visible void set_precision_flag_up(void)
{
if (control_word & CW_Precision)
partial_status |= (SW_Precision | SW_C1); /* The masked response */
else
EXCEPTION(EX_Precision | SW_C1);
}
/* This may be called often, so keep it lean */
asmlinkage __visible void set_precision_flag_down(void)
{
if (control_word & CW_Precision) { /* The masked response */
partial_status &= ~SW_C1;
partial_status |= SW_Precision;
} else
EXCEPTION(EX_Precision);
}
asmlinkage __visible int denormal_operand(void)
{
if (control_word & CW_Denormal) { /* The masked response */
partial_status |= SW_Denorm_Op;
return TAG_Special;
} else {
EXCEPTION(EX_Denormal);
return TAG_Special | FPU_Exception;
}
}
asmlinkage __visible int arith_overflow(FPU_REG *dest)
{
int tag = TAG_Valid;
if (control_word & CW_Overflow) {
/* The masked response */
/* ###### The response here depends upon the rounding mode */
reg_copy(&CONST_INF, dest);
tag = TAG_Special;
} else {
/* Subtract the magic number from the exponent */
addexponent(dest, (-3 * (1 << 13)));
}
EXCEPTION(EX_Overflow);
if (control_word & CW_Overflow) {
/* The overflow exception is masked. */
/* By definition, precision is lost.
The roundup bit (C1) is also set because we have
"rounded" upwards to Infinity. */
EXCEPTION(EX_Precision | SW_C1);
return tag;
}
return tag;
}
asmlinkage __visible int arith_underflow(FPU_REG *dest)
{
int tag = TAG_Valid;
if (control_word & CW_Underflow) {
/* The masked response */
if (exponent16(dest) <= EXP_UNDER - 63) {
reg_copy(&CONST_Z, dest);
partial_status &= ~SW_C1; /* Round down. */
tag = TAG_Zero;
} else {
stdexp(dest);
}
} else {
/* Add the magic number to the exponent. */
addexponent(dest, (3 * (1 << 13)) + EXTENDED_Ebias);
}
EXCEPTION(EX_Underflow);
if (control_word & CW_Underflow) {
/* The underflow exception is masked. */
EXCEPTION(EX_Precision);
return tag;
}
return tag;
}
void FPU_stack_overflow(void)
{
if (control_word & CW_Invalid) {
/* The masked response */
top--;
FPU_copy_to_reg0(&CONST_QNaN, TAG_Special);
}
EXCEPTION(EX_StackOver);
return;
}
void FPU_stack_underflow(void)
{
if (control_word & CW_Invalid) {
/* The masked response */
FPU_copy_to_reg0(&CONST_QNaN, TAG_Special);
}
EXCEPTION(EX_StackUnder);
return;
}
void FPU_stack_underflow_i(int i)
{
if (control_word & CW_Invalid) {
/* The masked response */
FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i);
}
EXCEPTION(EX_StackUnder);
return;
}
void FPU_stack_underflow_pop(int i)
{
if (control_word & CW_Invalid) {
/* The masked response */
FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i);
FPU_pop();
}
EXCEPTION(EX_StackUnder);
return;
}