1 // SPDX-License-Identifier: GPL-2.0
2 /*---------------------------------------------------------------------------+
3 | errors.c |
4 | |
5 | The error handling functions for wm-FPU-emu |
6 | |
7 | Copyright (C) 1992,1993,1994,1996 |
8 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
9 | E-mail billm@jacobi.maths.monash.edu.au |
10 | |
11 | |
12 +---------------------------------------------------------------------------*/
13
14 /*---------------------------------------------------------------------------+
15 | Note: |
16 | The file contains code which accesses user memory. |
17 | Emulator static data may change when user memory is accessed, due to |
18 | other processes using the emulator while swapping is in progress. |
19 +---------------------------------------------------------------------------*/
20
21 #include <linux/signal.h>
22
23 #include <linux/uaccess.h>
24
25 #include "fpu_emu.h"
26 #include "fpu_system.h"
27 #include "exception.h"
28 #include "status_w.h"
29 #include "control_w.h"
30 #include "reg_constant.h"
31 #include "version.h"
32
33 /* */
34 #undef PRINT_MESSAGES
35 /* */
36
37 #if 0
38 void Un_impl(void)
39 {
40 u_char byte1, FPU_modrm;
41 unsigned long address = FPU_ORIG_EIP;
42
43 RE_ENTRANT_CHECK_OFF;
44 /* No need to check access_ok(), we have previously fetched these bytes. */
45 printk("Unimplemented FPU Opcode at eip=%p : ", (void __user *)address);
46 if (FPU_CS == __USER_CS) {
47 while (1) {
48 FPU_get_user(byte1, (u_char __user *) address);
49 if ((byte1 & 0xf8) == 0xd8)
50 break;
51 printk("[%02x]", byte1);
52 address++;
53 }
54 printk("%02x ", byte1);
55 FPU_get_user(FPU_modrm, 1 + (u_char __user *) address);
56
57 if (FPU_modrm >= 0300)
58 printk("%02x (%02x+%d)\n", FPU_modrm, FPU_modrm & 0xf8,
59 FPU_modrm & 7);
60 else
61 printk("/%d\n", (FPU_modrm >> 3) & 7);
62 } else {
63 printk("cs selector = %04x\n", FPU_CS);
64 }
65
66 RE_ENTRANT_CHECK_ON;
67
68 EXCEPTION(EX_Invalid);
69
70 }
71 #endif /* 0 */
72
73 /*
74 Called for opcodes which are illegal and which are known to result in a
75 SIGILL with a real 80486.
76 */
FPU_illegal(void)77 void FPU_illegal(void)
78 {
79 math_abort(FPU_info, SIGILL);
80 }
81
FPU_printall(void)82 void FPU_printall(void)
83 {
84 int i;
85 static const char *tag_desc[] = { "Valid", "Zero", "ERROR", "Empty",
86 "DeNorm", "Inf", "NaN"
87 };
88 u_char byte1, FPU_modrm;
89 unsigned long address = FPU_ORIG_EIP;
90
91 RE_ENTRANT_CHECK_OFF;
92 /* No need to check access_ok(), we have previously fetched these bytes. */
93 printk("At %p:", (void *)address);
94 if (FPU_CS == __USER_CS) {
95 #define MAX_PRINTED_BYTES 20
96 for (i = 0; i < MAX_PRINTED_BYTES; i++) {
97 FPU_get_user(byte1, (u_char __user *) address);
98 if ((byte1 & 0xf8) == 0xd8) {
99 printk(" %02x", byte1);
100 break;
101 }
102 printk(" [%02x]", byte1);
103 address++;
104 }
105 if (i == MAX_PRINTED_BYTES)
106 printk(" [more..]\n");
107 else {
108 FPU_get_user(FPU_modrm, 1 + (u_char __user *) address);
109
110 if (FPU_modrm >= 0300)
111 printk(" %02x (%02x+%d)\n", FPU_modrm,
112 FPU_modrm & 0xf8, FPU_modrm & 7);
113 else
114 printk(" /%d, mod=%d rm=%d\n",
115 (FPU_modrm >> 3) & 7,
116 (FPU_modrm >> 6) & 3, FPU_modrm & 7);
117 }
118 } else {
119 printk("%04x\n", FPU_CS);
120 }
121
122 partial_status = status_word();
123
124 #ifdef DEBUGGING
125 if (partial_status & SW_Backward)
126 printk("SW: backward compatibility\n");
127 if (partial_status & SW_C3)
128 printk("SW: condition bit 3\n");
129 if (partial_status & SW_C2)
130 printk("SW: condition bit 2\n");
131 if (partial_status & SW_C1)
132 printk("SW: condition bit 1\n");
133 if (partial_status & SW_C0)
134 printk("SW: condition bit 0\n");
135 if (partial_status & SW_Summary)
136 printk("SW: exception summary\n");
137 if (partial_status & SW_Stack_Fault)
138 printk("SW: stack fault\n");
139 if (partial_status & SW_Precision)
140 printk("SW: loss of precision\n");
141 if (partial_status & SW_Underflow)
142 printk("SW: underflow\n");
143 if (partial_status & SW_Overflow)
144 printk("SW: overflow\n");
145 if (partial_status & SW_Zero_Div)
146 printk("SW: divide by zero\n");
147 if (partial_status & SW_Denorm_Op)
148 printk("SW: denormalized operand\n");
149 if (partial_status & SW_Invalid)
150 printk("SW: invalid operation\n");
151 #endif /* DEBUGGING */
152
153 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 */
154 (partial_status & 0x3800) >> 11, /* stack top pointer */
155 partial_status & 0x80 ? 1 : 0, /* Error summary status */
156 partial_status & 0x40 ? 1 : 0, /* Stack flag */
157 partial_status & SW_C3 ? 1 : 0, partial_status & SW_C2 ? 1 : 0, /* cc */
158 partial_status & SW_C1 ? 1 : 0, partial_status & SW_C0 ? 1 : 0, /* cc */
159 partial_status & SW_Precision ? 1 : 0,
160 partial_status & SW_Underflow ? 1 : 0,
161 partial_status & SW_Overflow ? 1 : 0,
162 partial_status & SW_Zero_Div ? 1 : 0,
163 partial_status & SW_Denorm_Op ? 1 : 0,
164 partial_status & SW_Invalid ? 1 : 0);
165
166 printk(" CW: ic=%d rc=%d%d pc=%d%d iem=%d ef=%d%d%d%d%d%d\n",
167 control_word & 0x1000 ? 1 : 0,
168 (control_word & 0x800) >> 11, (control_word & 0x400) >> 10,
169 (control_word & 0x200) >> 9, (control_word & 0x100) >> 8,
170 control_word & 0x80 ? 1 : 0,
171 control_word & SW_Precision ? 1 : 0,
172 control_word & SW_Underflow ? 1 : 0,
173 control_word & SW_Overflow ? 1 : 0,
174 control_word & SW_Zero_Div ? 1 : 0,
175 control_word & SW_Denorm_Op ? 1 : 0,
176 control_word & SW_Invalid ? 1 : 0);
177
178 for (i = 0; i < 8; i++) {
179 FPU_REG *r = &st(i);
180 u_char tagi = FPU_gettagi(i);
181
182 switch (tagi) {
183 case TAG_Empty:
184 continue;
185 case TAG_Zero:
186 case TAG_Special:
187 /* Update tagi for the printk below */
188 tagi = FPU_Special(r);
189 fallthrough;
190 case TAG_Valid:
191 printk("st(%d) %c .%04lx %04lx %04lx %04lx e%+-6d ", i,
192 getsign(r) ? '-' : '+',
193 (long)(r->sigh >> 16),
194 (long)(r->sigh & 0xFFFF),
195 (long)(r->sigl >> 16),
196 (long)(r->sigl & 0xFFFF),
197 exponent(r) - EXP_BIAS + 1);
198 break;
199 default:
200 printk("Whoops! Error in errors.c: tag%d is %d ", i,
201 tagi);
202 continue;
203 }
204 printk("%s\n", tag_desc[(int)(unsigned)tagi]);
205 }
206
207 RE_ENTRANT_CHECK_ON;
208
209 }
210
211 static struct {
212 int type;
213 const char *name;
214 } exception_names[] = {
215 {
216 EX_StackOver, "stack overflow"}, {
217 EX_StackUnder, "stack underflow"}, {
218 EX_Precision, "loss of precision"}, {
219 EX_Underflow, "underflow"}, {
220 EX_Overflow, "overflow"}, {
221 EX_ZeroDiv, "divide by zero"}, {
222 EX_Denormal, "denormalized operand"}, {
223 EX_Invalid, "invalid operation"}, {
224 EX_INTERNAL, "INTERNAL BUG in " FPU_VERSION}, {
225 0, NULL}
226 };
227
228 /*
229 EX_INTERNAL is always given with a code which indicates where the
230 error was detected.
231
232 Internal error types:
233 0x14 in fpu_etc.c
234 0x1nn in a *.c file:
235 0x101 in reg_add_sub.c
236 0x102 in reg_mul.c
237 0x104 in poly_atan.c
238 0x105 in reg_mul.c
239 0x107 in fpu_trig.c
240 0x108 in reg_compare.c
241 0x109 in reg_compare.c
242 0x110 in reg_add_sub.c
243 0x111 in fpe_entry.c
244 0x112 in fpu_trig.c
245 0x113 in errors.c
246 0x115 in fpu_trig.c
247 0x116 in fpu_trig.c
248 0x117 in fpu_trig.c
249 0x118 in fpu_trig.c
250 0x119 in fpu_trig.c
251 0x120 in poly_atan.c
252 0x121 in reg_compare.c
253 0x122 in reg_compare.c
254 0x123 in reg_compare.c
255 0x125 in fpu_trig.c
256 0x126 in fpu_entry.c
257 0x127 in poly_2xm1.c
258 0x128 in fpu_entry.c
259 0x129 in fpu_entry.c
260 0x130 in get_address.c
261 0x131 in get_address.c
262 0x132 in get_address.c
263 0x133 in get_address.c
264 0x140 in load_store.c
265 0x141 in load_store.c
266 0x150 in poly_sin.c
267 0x151 in poly_sin.c
268 0x160 in reg_ld_str.c
269 0x161 in reg_ld_str.c
270 0x162 in reg_ld_str.c
271 0x163 in reg_ld_str.c
272 0x164 in reg_ld_str.c
273 0x170 in fpu_tags.c
274 0x171 in fpu_tags.c
275 0x172 in fpu_tags.c
276 0x180 in reg_convert.c
277 0x2nn in an *.S file:
278 0x201 in reg_u_add.S
279 0x202 in reg_u_div.S
280 0x203 in reg_u_div.S
281 0x204 in reg_u_div.S
282 0x205 in reg_u_mul.S
283 0x206 in reg_u_sub.S
284 0x207 in wm_sqrt.S
285 0x208 in reg_div.S
286 0x209 in reg_u_sub.S
287 0x210 in reg_u_sub.S
288 0x211 in reg_u_sub.S
289 0x212 in reg_u_sub.S
290 0x213 in wm_sqrt.S
291 0x214 in wm_sqrt.S
292 0x215 in wm_sqrt.S
293 0x220 in reg_norm.S
294 0x221 in reg_norm.S
295 0x230 in reg_round.S
296 0x231 in reg_round.S
297 0x232 in reg_round.S
298 0x233 in reg_round.S
299 0x234 in reg_round.S
300 0x235 in reg_round.S
301 0x236 in reg_round.S
302 0x240 in div_Xsig.S
303 0x241 in div_Xsig.S
304 0x242 in div_Xsig.S
305 */
306
FPU_exception(int n)307 asmlinkage __visible void FPU_exception(int n)
308 {
309 int i, int_type;
310
311 int_type = 0; /* Needed only to stop compiler warnings */
312 if (n & EX_INTERNAL) {
313 int_type = n - EX_INTERNAL;
314 n = EX_INTERNAL;
315 /* Set lots of exception bits! */
316 partial_status |= (SW_Exc_Mask | SW_Summary | SW_Backward);
317 } else {
318 /* Extract only the bits which we use to set the status word */
319 n &= (SW_Exc_Mask);
320 /* Set the corresponding exception bit */
321 partial_status |= n;
322 /* Set summary bits iff exception isn't masked */
323 if (partial_status & ~control_word & CW_Exceptions)
324 partial_status |= (SW_Summary | SW_Backward);
325 if (n & (SW_Stack_Fault | EX_Precision)) {
326 if (!(n & SW_C1))
327 /* This bit distinguishes over- from underflow for a stack fault,
328 and roundup from round-down for precision loss. */
329 partial_status &= ~SW_C1;
330 }
331 }
332
333 RE_ENTRANT_CHECK_OFF;
334 if ((~control_word & n & CW_Exceptions) || (n == EX_INTERNAL)) {
335 /* Get a name string for error reporting */
336 for (i = 0; exception_names[i].type; i++)
337 if ((exception_names[i].type & n) ==
338 exception_names[i].type)
339 break;
340
341 if (exception_names[i].type) {
342 #ifdef PRINT_MESSAGES
343 printk("FP Exception: %s!\n", exception_names[i].name);
344 #endif /* PRINT_MESSAGES */
345 } else
346 printk("FPU emulator: Unknown Exception: 0x%04x!\n", n);
347
348 if (n == EX_INTERNAL) {
349 printk("FPU emulator: Internal error type 0x%04x\n",
350 int_type);
351 FPU_printall();
352 }
353 #ifdef PRINT_MESSAGES
354 else
355 FPU_printall();
356 #endif /* PRINT_MESSAGES */
357
358 /*
359 * The 80486 generates an interrupt on the next non-control FPU
360 * instruction. So we need some means of flagging it.
361 * We use the ES (Error Summary) bit for this.
362 */
363 }
364 RE_ENTRANT_CHECK_ON;
365
366 #ifdef __DEBUG__
367 math_abort(FPU_info, SIGFPE);
368 #endif /* __DEBUG__ */
369
370 }
371
372 /* Real operation attempted on a NaN. */
373 /* Returns < 0 if the exception is unmasked */
real_1op_NaN(FPU_REG * a)374 int real_1op_NaN(FPU_REG *a)
375 {
376 int signalling, isNaN;
377
378 isNaN = (exponent(a) == EXP_OVER) && (a->sigh & 0x80000000);
379
380 /* The default result for the case of two "equal" NaNs (signs may
381 differ) is chosen to reproduce 80486 behaviour */
382 signalling = isNaN && !(a->sigh & 0x40000000);
383
384 if (!signalling) {
385 if (!isNaN) { /* pseudo-NaN, or other unsupported? */
386 if (control_word & CW_Invalid) {
387 /* Masked response */
388 reg_copy(&CONST_QNaN, a);
389 }
390 EXCEPTION(EX_Invalid);
391 return (!(control_word & CW_Invalid) ? FPU_Exception :
392 0) | TAG_Special;
393 }
394 return TAG_Special;
395 }
396
397 if (control_word & CW_Invalid) {
398 /* The masked response */
399 if (!(a->sigh & 0x80000000)) { /* pseudo-NaN ? */
400 reg_copy(&CONST_QNaN, a);
401 }
402 /* ensure a Quiet NaN */
403 a->sigh |= 0x40000000;
404 }
405
406 EXCEPTION(EX_Invalid);
407
408 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special;
409 }
410
411 /* Real operation attempted on two operands, one a NaN. */
412 /* Returns < 0 if the exception is unmasked */
real_2op_NaN(FPU_REG const * b,u_char tagb,int deststnr,FPU_REG const * defaultNaN)413 int real_2op_NaN(FPU_REG const *b, u_char tagb,
414 int deststnr, FPU_REG const *defaultNaN)
415 {
416 FPU_REG *dest = &st(deststnr);
417 FPU_REG const *a = dest;
418 u_char taga = FPU_gettagi(deststnr);
419 FPU_REG const *x;
420 int signalling, unsupported;
421
422 if (taga == TAG_Special)
423 taga = FPU_Special(a);
424 if (tagb == TAG_Special)
425 tagb = FPU_Special(b);
426
427 /* TW_NaN is also used for unsupported data types. */
428 unsupported = ((taga == TW_NaN)
429 && !((exponent(a) == EXP_OVER)
430 && (a->sigh & 0x80000000)))
431 || ((tagb == TW_NaN)
432 && !((exponent(b) == EXP_OVER) && (b->sigh & 0x80000000)));
433 if (unsupported) {
434 if (control_word & CW_Invalid) {
435 /* Masked response */
436 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr);
437 }
438 EXCEPTION(EX_Invalid);
439 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) |
440 TAG_Special;
441 }
442
443 if (taga == TW_NaN) {
444 x = a;
445 if (tagb == TW_NaN) {
446 signalling = !(a->sigh & b->sigh & 0x40000000);
447 if (significand(b) > significand(a))
448 x = b;
449 else if (significand(b) == significand(a)) {
450 /* The default result for the case of two "equal" NaNs (signs may
451 differ) is chosen to reproduce 80486 behaviour */
452 x = defaultNaN;
453 }
454 } else {
455 /* return the quiet version of the NaN in a */
456 signalling = !(a->sigh & 0x40000000);
457 }
458 } else
459 #ifdef PARANOID
460 if (tagb == TW_NaN)
461 #endif /* PARANOID */
462 {
463 signalling = !(b->sigh & 0x40000000);
464 x = b;
465 }
466 #ifdef PARANOID
467 else {
468 signalling = 0;
469 EXCEPTION(EX_INTERNAL | 0x113);
470 x = &CONST_QNaN;
471 }
472 #endif /* PARANOID */
473
474 if ((!signalling) || (control_word & CW_Invalid)) {
475 if (!x)
476 x = b;
477
478 if (!(x->sigh & 0x80000000)) /* pseudo-NaN ? */
479 x = &CONST_QNaN;
480
481 FPU_copy_to_regi(x, TAG_Special, deststnr);
482
483 if (!signalling)
484 return TAG_Special;
485
486 /* ensure a Quiet NaN */
487 dest->sigh |= 0x40000000;
488 }
489
490 EXCEPTION(EX_Invalid);
491
492 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special;
493 }
494
495 /* Invalid arith operation on Valid registers */
496 /* Returns < 0 if the exception is unmasked */
arith_invalid(int deststnr)497 asmlinkage __visible int arith_invalid(int deststnr)
498 {
499
500 EXCEPTION(EX_Invalid);
501
502 if (control_word & CW_Invalid) {
503 /* The masked response */
504 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr);
505 }
506
507 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Valid;
508
509 }
510
511 /* Divide a finite number by zero */
FPU_divide_by_zero(int deststnr,u_char sign)512 asmlinkage __visible int FPU_divide_by_zero(int deststnr, u_char sign)
513 {
514 FPU_REG *dest = &st(deststnr);
515 int tag = TAG_Valid;
516
517 if (control_word & CW_ZeroDiv) {
518 /* The masked response */
519 FPU_copy_to_regi(&CONST_INF, TAG_Special, deststnr);
520 setsign(dest, sign);
521 tag = TAG_Special;
522 }
523
524 EXCEPTION(EX_ZeroDiv);
525
526 return (!(control_word & CW_ZeroDiv) ? FPU_Exception : 0) | tag;
527
528 }
529
530 /* This may be called often, so keep it lean */
set_precision_flag(int flags)531 int set_precision_flag(int flags)
532 {
533 if (control_word & CW_Precision) {
534 partial_status &= ~(SW_C1 & flags);
535 partial_status |= flags; /* The masked response */
536 return 0;
537 } else {
538 EXCEPTION(flags);
539 return 1;
540 }
541 }
542
543 /* This may be called often, so keep it lean */
set_precision_flag_up(void)544 asmlinkage __visible void set_precision_flag_up(void)
545 {
546 if (control_word & CW_Precision)
547 partial_status |= (SW_Precision | SW_C1); /* The masked response */
548 else
549 EXCEPTION(EX_Precision | SW_C1);
550 }
551
552 /* This may be called often, so keep it lean */
set_precision_flag_down(void)553 asmlinkage __visible void set_precision_flag_down(void)
554 {
555 if (control_word & CW_Precision) { /* The masked response */
556 partial_status &= ~SW_C1;
557 partial_status |= SW_Precision;
558 } else
559 EXCEPTION(EX_Precision);
560 }
561
denormal_operand(void)562 asmlinkage __visible int denormal_operand(void)
563 {
564 if (control_word & CW_Denormal) { /* The masked response */
565 partial_status |= SW_Denorm_Op;
566 return TAG_Special;
567 } else {
568 EXCEPTION(EX_Denormal);
569 return TAG_Special | FPU_Exception;
570 }
571 }
572
arith_overflow(FPU_REG * dest)573 asmlinkage __visible int arith_overflow(FPU_REG *dest)
574 {
575 int tag = TAG_Valid;
576
577 if (control_word & CW_Overflow) {
578 /* The masked response */
579 /* ###### The response here depends upon the rounding mode */
580 reg_copy(&CONST_INF, dest);
581 tag = TAG_Special;
582 } else {
583 /* Subtract the magic number from the exponent */
584 addexponent(dest, (-3 * (1 << 13)));
585 }
586
587 EXCEPTION(EX_Overflow);
588 if (control_word & CW_Overflow) {
589 /* The overflow exception is masked. */
590 /* By definition, precision is lost.
591 The roundup bit (C1) is also set because we have
592 "rounded" upwards to Infinity. */
593 EXCEPTION(EX_Precision | SW_C1);
594 return tag;
595 }
596
597 return tag;
598
599 }
600
arith_underflow(FPU_REG * dest)601 asmlinkage __visible int arith_underflow(FPU_REG *dest)
602 {
603 int tag = TAG_Valid;
604
605 if (control_word & CW_Underflow) {
606 /* The masked response */
607 if (exponent16(dest) <= EXP_UNDER - 63) {
608 reg_copy(&CONST_Z, dest);
609 partial_status &= ~SW_C1; /* Round down. */
610 tag = TAG_Zero;
611 } else {
612 stdexp(dest);
613 }
614 } else {
615 /* Add the magic number to the exponent. */
616 addexponent(dest, (3 * (1 << 13)) + EXTENDED_Ebias);
617 }
618
619 EXCEPTION(EX_Underflow);
620 if (control_word & CW_Underflow) {
621 /* The underflow exception is masked. */
622 EXCEPTION(EX_Precision);
623 return tag;
624 }
625
626 return tag;
627
628 }
629
FPU_stack_overflow(void)630 void FPU_stack_overflow(void)
631 {
632
633 if (control_word & CW_Invalid) {
634 /* The masked response */
635 top--;
636 FPU_copy_to_reg0(&CONST_QNaN, TAG_Special);
637 }
638
639 EXCEPTION(EX_StackOver);
640
641 return;
642
643 }
644
FPU_stack_underflow(void)645 void FPU_stack_underflow(void)
646 {
647
648 if (control_word & CW_Invalid) {
649 /* The masked response */
650 FPU_copy_to_reg0(&CONST_QNaN, TAG_Special);
651 }
652
653 EXCEPTION(EX_StackUnder);
654
655 return;
656
657 }
658
FPU_stack_underflow_i(int i)659 void FPU_stack_underflow_i(int i)
660 {
661
662 if (control_word & CW_Invalid) {
663 /* The masked response */
664 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i);
665 }
666
667 EXCEPTION(EX_StackUnder);
668
669 return;
670
671 }
672
FPU_stack_underflow_pop(int i)673 void FPU_stack_underflow_pop(int i)
674 {
675
676 if (control_word & CW_Invalid) {
677 /* The masked response */
678 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i);
679 FPU_pop();
680 }
681
682 EXCEPTION(EX_StackUnder);
683
684 return;
685
686 }
687