1 /*---------------------------------------------------------------------------+
2 | errors.c |
3 | |
4 | The error handling functions for wm-FPU-emu |
5 | |
6 | Copyright (C) 1992,1993,1994,1996 |
7 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
8 | E-mail billm@jacobi.maths.monash.edu.au |
9 | |
10 | |
11 +---------------------------------------------------------------------------*/
12
13 /*---------------------------------------------------------------------------+
14 | Note: |
15 | The file contains code which accesses user memory. |
16 | Emulator static data may change when user memory is accessed, due to |
17 | other processes using the emulator while swapping is in progress. |
18 +---------------------------------------------------------------------------*/
19
20 #include <linux/signal.h>
21
22 #include <asm/uaccess.h>
23
24 #include "fpu_emu.h"
25 #include "fpu_system.h"
26 #include "exception.h"
27 #include "status_w.h"
28 #include "control_w.h"
29 #include "reg_constant.h"
30 #include "version.h"
31
32 /* */
33 #undef PRINT_MESSAGES
34 /* */
35
36 #if 0
37 void Un_impl(void)
38 {
39 u_char byte1, FPU_modrm;
40 unsigned long address = FPU_ORIG_EIP;
41
42 RE_ENTRANT_CHECK_OFF;
43 /* No need to check access_ok(), we have previously fetched these bytes. */
44 printk("Unimplemented FPU Opcode at eip=%p : ", (void __user *)address);
45 if (FPU_CS == __USER_CS) {
46 while (1) {
47 FPU_get_user(byte1, (u_char __user *) address);
48 if ((byte1 & 0xf8) == 0xd8)
49 break;
50 printk("[%02x]", byte1);
51 address++;
52 }
53 printk("%02x ", byte1);
54 FPU_get_user(FPU_modrm, 1 + (u_char __user *) address);
55
56 if (FPU_modrm >= 0300)
57 printk("%02x (%02x+%d)\n", FPU_modrm, FPU_modrm & 0xf8,
58 FPU_modrm & 7);
59 else
60 printk("/%d\n", (FPU_modrm >> 3) & 7);
61 } else {
62 printk("cs selector = %04x\n", FPU_CS);
63 }
64
65 RE_ENTRANT_CHECK_ON;
66
67 EXCEPTION(EX_Invalid);
68
69 }
70 #endif /* 0 */
71
72 /*
73 Called for opcodes which are illegal and which are known to result in a
74 SIGILL with a real 80486.
75 */
FPU_illegal(void)76 void FPU_illegal(void)
77 {
78 math_abort(FPU_info, SIGILL);
79 }
80
FPU_printall(void)81 void FPU_printall(void)
82 {
83 int i;
84 static const char *tag_desc[] = { "Valid", "Zero", "ERROR", "Empty",
85 "DeNorm", "Inf", "NaN"
86 };
87 u_char byte1, FPU_modrm;
88 unsigned long address = FPU_ORIG_EIP;
89
90 RE_ENTRANT_CHECK_OFF;
91 /* No need to check access_ok(), we have previously fetched these bytes. */
92 printk("At %p:", (void *)address);
93 if (FPU_CS == __USER_CS) {
94 #define MAX_PRINTED_BYTES 20
95 for (i = 0; i < MAX_PRINTED_BYTES; i++) {
96 FPU_get_user(byte1, (u_char __user *) address);
97 if ((byte1 & 0xf8) == 0xd8) {
98 printk(" %02x", byte1);
99 break;
100 }
101 printk(" [%02x]", byte1);
102 address++;
103 }
104 if (i == MAX_PRINTED_BYTES)
105 printk(" [more..]\n");
106 else {
107 FPU_get_user(FPU_modrm, 1 + (u_char __user *) address);
108
109 if (FPU_modrm >= 0300)
110 printk(" %02x (%02x+%d)\n", FPU_modrm,
111 FPU_modrm & 0xf8, FPU_modrm & 7);
112 else
113 printk(" /%d, mod=%d rm=%d\n",
114 (FPU_modrm >> 3) & 7,
115 (FPU_modrm >> 6) & 3, FPU_modrm & 7);
116 }
117 } else {
118 printk("%04x\n", FPU_CS);
119 }
120
121 partial_status = status_word();
122
123 #ifdef DEBUGGING
124 if (partial_status & SW_Backward)
125 printk("SW: backward compatibility\n");
126 if (partial_status & SW_C3)
127 printk("SW: condition bit 3\n");
128 if (partial_status & SW_C2)
129 printk("SW: condition bit 2\n");
130 if (partial_status & SW_C1)
131 printk("SW: condition bit 1\n");
132 if (partial_status & SW_C0)
133 printk("SW: condition bit 0\n");
134 if (partial_status & SW_Summary)
135 printk("SW: exception summary\n");
136 if (partial_status & SW_Stack_Fault)
137 printk("SW: stack fault\n");
138 if (partial_status & SW_Precision)
139 printk("SW: loss of precision\n");
140 if (partial_status & SW_Underflow)
141 printk("SW: underflow\n");
142 if (partial_status & SW_Overflow)
143 printk("SW: overflow\n");
144 if (partial_status & SW_Zero_Div)
145 printk("SW: divide by zero\n");
146 if (partial_status & SW_Denorm_Op)
147 printk("SW: denormalized operand\n");
148 if (partial_status & SW_Invalid)
149 printk("SW: invalid operation\n");
150 #endif /* DEBUGGING */
151
152 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 */
153 (partial_status & 0x3800) >> 11, /* stack top pointer */
154 partial_status & 0x80 ? 1 : 0, /* Error summary status */
155 partial_status & 0x40 ? 1 : 0, /* Stack flag */
156 partial_status & SW_C3 ? 1 : 0, partial_status & SW_C2 ? 1 : 0, /* cc */
157 partial_status & SW_C1 ? 1 : 0, partial_status & SW_C0 ? 1 : 0, /* cc */
158 partial_status & SW_Precision ? 1 : 0,
159 partial_status & SW_Underflow ? 1 : 0,
160 partial_status & SW_Overflow ? 1 : 0,
161 partial_status & SW_Zero_Div ? 1 : 0,
162 partial_status & SW_Denorm_Op ? 1 : 0,
163 partial_status & SW_Invalid ? 1 : 0);
164
165 printk(" CW: ic=%d rc=%d%d pc=%d%d iem=%d ef=%d%d%d%d%d%d\n",
166 control_word & 0x1000 ? 1 : 0,
167 (control_word & 0x800) >> 11, (control_word & 0x400) >> 10,
168 (control_word & 0x200) >> 9, (control_word & 0x100) >> 8,
169 control_word & 0x80 ? 1 : 0,
170 control_word & SW_Precision ? 1 : 0,
171 control_word & SW_Underflow ? 1 : 0,
172 control_word & SW_Overflow ? 1 : 0,
173 control_word & SW_Zero_Div ? 1 : 0,
174 control_word & SW_Denorm_Op ? 1 : 0,
175 control_word & SW_Invalid ? 1 : 0);
176
177 for (i = 0; i < 8; i++) {
178 FPU_REG *r = &st(i);
179 u_char tagi = FPU_gettagi(i);
180 switch (tagi) {
181 case TAG_Empty:
182 continue;
183 break;
184 case TAG_Zero:
185 case TAG_Special:
186 tagi = FPU_Special(r);
187 case TAG_Valid:
188 printk("st(%d) %c .%04lx %04lx %04lx %04lx e%+-6d ", i,
189 getsign(r) ? '-' : '+',
190 (long)(r->sigh >> 16),
191 (long)(r->sigh & 0xFFFF),
192 (long)(r->sigl >> 16),
193 (long)(r->sigl & 0xFFFF),
194 exponent(r) - EXP_BIAS + 1);
195 break;
196 default:
197 printk("Whoops! Error in errors.c: tag%d is %d ", i,
198 tagi);
199 continue;
200 break;
201 }
202 printk("%s\n", tag_desc[(int)(unsigned)tagi]);
203 }
204
205 RE_ENTRANT_CHECK_ON;
206
207 }
208
209 static struct {
210 int type;
211 const char *name;
212 } exception_names[] = {
213 {
214 EX_StackOver, "stack overflow"}, {
215 EX_StackUnder, "stack underflow"}, {
216 EX_Precision, "loss of precision"}, {
217 EX_Underflow, "underflow"}, {
218 EX_Overflow, "overflow"}, {
219 EX_ZeroDiv, "divide by zero"}, {
220 EX_Denormal, "denormalized operand"}, {
221 EX_Invalid, "invalid operation"}, {
222 EX_INTERNAL, "INTERNAL BUG in " FPU_VERSION}, {
223 0, NULL}
224 };
225
226 /*
227 EX_INTERNAL is always given with a code which indicates where the
228 error was detected.
229
230 Internal error types:
231 0x14 in fpu_etc.c
232 0x1nn in a *.c file:
233 0x101 in reg_add_sub.c
234 0x102 in reg_mul.c
235 0x104 in poly_atan.c
236 0x105 in reg_mul.c
237 0x107 in fpu_trig.c
238 0x108 in reg_compare.c
239 0x109 in reg_compare.c
240 0x110 in reg_add_sub.c
241 0x111 in fpe_entry.c
242 0x112 in fpu_trig.c
243 0x113 in errors.c
244 0x115 in fpu_trig.c
245 0x116 in fpu_trig.c
246 0x117 in fpu_trig.c
247 0x118 in fpu_trig.c
248 0x119 in fpu_trig.c
249 0x120 in poly_atan.c
250 0x121 in reg_compare.c
251 0x122 in reg_compare.c
252 0x123 in reg_compare.c
253 0x125 in fpu_trig.c
254 0x126 in fpu_entry.c
255 0x127 in poly_2xm1.c
256 0x128 in fpu_entry.c
257 0x129 in fpu_entry.c
258 0x130 in get_address.c
259 0x131 in get_address.c
260 0x132 in get_address.c
261 0x133 in get_address.c
262 0x140 in load_store.c
263 0x141 in load_store.c
264 0x150 in poly_sin.c
265 0x151 in poly_sin.c
266 0x160 in reg_ld_str.c
267 0x161 in reg_ld_str.c
268 0x162 in reg_ld_str.c
269 0x163 in reg_ld_str.c
270 0x164 in reg_ld_str.c
271 0x170 in fpu_tags.c
272 0x171 in fpu_tags.c
273 0x172 in fpu_tags.c
274 0x180 in reg_convert.c
275 0x2nn in an *.S file:
276 0x201 in reg_u_add.S
277 0x202 in reg_u_div.S
278 0x203 in reg_u_div.S
279 0x204 in reg_u_div.S
280 0x205 in reg_u_mul.S
281 0x206 in reg_u_sub.S
282 0x207 in wm_sqrt.S
283 0x208 in reg_div.S
284 0x209 in reg_u_sub.S
285 0x210 in reg_u_sub.S
286 0x211 in reg_u_sub.S
287 0x212 in reg_u_sub.S
288 0x213 in wm_sqrt.S
289 0x214 in wm_sqrt.S
290 0x215 in wm_sqrt.S
291 0x220 in reg_norm.S
292 0x221 in reg_norm.S
293 0x230 in reg_round.S
294 0x231 in reg_round.S
295 0x232 in reg_round.S
296 0x233 in reg_round.S
297 0x234 in reg_round.S
298 0x235 in reg_round.S
299 0x236 in reg_round.S
300 0x240 in div_Xsig.S
301 0x241 in div_Xsig.S
302 0x242 in div_Xsig.S
303 */
304
FPU_exception(int n)305 asmlinkage void FPU_exception(int n)
306 {
307 int i, int_type;
308
309 int_type = 0; /* Needed only to stop compiler warnings */
310 if (n & EX_INTERNAL) {
311 int_type = n - EX_INTERNAL;
312 n = EX_INTERNAL;
313 /* Set lots of exception bits! */
314 partial_status |= (SW_Exc_Mask | SW_Summary | SW_Backward);
315 } else {
316 /* Extract only the bits which we use to set the status word */
317 n &= (SW_Exc_Mask);
318 /* Set the corresponding exception bit */
319 partial_status |= n;
320 /* Set summary bits iff exception isn't masked */
321 if (partial_status & ~control_word & CW_Exceptions)
322 partial_status |= (SW_Summary | SW_Backward);
323 if (n & (SW_Stack_Fault | EX_Precision)) {
324 if (!(n & SW_C1))
325 /* This bit distinguishes over- from underflow for a stack fault,
326 and roundup from round-down for precision loss. */
327 partial_status &= ~SW_C1;
328 }
329 }
330
331 RE_ENTRANT_CHECK_OFF;
332 if ((~control_word & n & CW_Exceptions) || (n == EX_INTERNAL)) {
333 #ifdef PRINT_MESSAGES
334 /* My message from the sponsor */
335 printk(FPU_VERSION " " __DATE__ " (C) W. Metzenthen.\n");
336 #endif /* PRINT_MESSAGES */
337
338 /* Get a name string for error reporting */
339 for (i = 0; exception_names[i].type; i++)
340 if ((exception_names[i].type & n) ==
341 exception_names[i].type)
342 break;
343
344 if (exception_names[i].type) {
345 #ifdef PRINT_MESSAGES
346 printk("FP Exception: %s!\n", exception_names[i].name);
347 #endif /* PRINT_MESSAGES */
348 } else
349 printk("FPU emulator: Unknown Exception: 0x%04x!\n", n);
350
351 if (n == EX_INTERNAL) {
352 printk("FPU emulator: Internal error type 0x%04x\n",
353 int_type);
354 FPU_printall();
355 }
356 #ifdef PRINT_MESSAGES
357 else
358 FPU_printall();
359 #endif /* PRINT_MESSAGES */
360
361 /*
362 * The 80486 generates an interrupt on the next non-control FPU
363 * instruction. So we need some means of flagging it.
364 * We use the ES (Error Summary) bit for this.
365 */
366 }
367 RE_ENTRANT_CHECK_ON;
368
369 #ifdef __DEBUG__
370 math_abort(FPU_info, SIGFPE);
371 #endif /* __DEBUG__ */
372
373 }
374
375 /* Real operation attempted on a NaN. */
376 /* Returns < 0 if the exception is unmasked */
real_1op_NaN(FPU_REG * a)377 int real_1op_NaN(FPU_REG *a)
378 {
379 int signalling, isNaN;
380
381 isNaN = (exponent(a) == EXP_OVER) && (a->sigh & 0x80000000);
382
383 /* The default result for the case of two "equal" NaNs (signs may
384 differ) is chosen to reproduce 80486 behaviour */
385 signalling = isNaN && !(a->sigh & 0x40000000);
386
387 if (!signalling) {
388 if (!isNaN) { /* pseudo-NaN, or other unsupported? */
389 if (control_word & CW_Invalid) {
390 /* Masked response */
391 reg_copy(&CONST_QNaN, a);
392 }
393 EXCEPTION(EX_Invalid);
394 return (!(control_word & CW_Invalid) ? FPU_Exception :
395 0) | TAG_Special;
396 }
397 return TAG_Special;
398 }
399
400 if (control_word & CW_Invalid) {
401 /* The masked response */
402 if (!(a->sigh & 0x80000000)) { /* pseudo-NaN ? */
403 reg_copy(&CONST_QNaN, a);
404 }
405 /* ensure a Quiet NaN */
406 a->sigh |= 0x40000000;
407 }
408
409 EXCEPTION(EX_Invalid);
410
411 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special;
412 }
413
414 /* Real operation attempted on two operands, one a NaN. */
415 /* Returns < 0 if the exception is unmasked */
real_2op_NaN(FPU_REG const * b,u_char tagb,int deststnr,FPU_REG const * defaultNaN)416 int real_2op_NaN(FPU_REG const *b, u_char tagb,
417 int deststnr, FPU_REG const *defaultNaN)
418 {
419 FPU_REG *dest = &st(deststnr);
420 FPU_REG const *a = dest;
421 u_char taga = FPU_gettagi(deststnr);
422 FPU_REG const *x;
423 int signalling, unsupported;
424
425 if (taga == TAG_Special)
426 taga = FPU_Special(a);
427 if (tagb == TAG_Special)
428 tagb = FPU_Special(b);
429
430 /* TW_NaN is also used for unsupported data types. */
431 unsupported = ((taga == TW_NaN)
432 && !((exponent(a) == EXP_OVER)
433 && (a->sigh & 0x80000000)))
434 || ((tagb == TW_NaN)
435 && !((exponent(b) == EXP_OVER) && (b->sigh & 0x80000000)));
436 if (unsupported) {
437 if (control_word & CW_Invalid) {
438 /* Masked response */
439 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr);
440 }
441 EXCEPTION(EX_Invalid);
442 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) |
443 TAG_Special;
444 }
445
446 if (taga == TW_NaN) {
447 x = a;
448 if (tagb == TW_NaN) {
449 signalling = !(a->sigh & b->sigh & 0x40000000);
450 if (significand(b) > significand(a))
451 x = b;
452 else if (significand(b) == significand(a)) {
453 /* The default result for the case of two "equal" NaNs (signs may
454 differ) is chosen to reproduce 80486 behaviour */
455 x = defaultNaN;
456 }
457 } else {
458 /* return the quiet version of the NaN in a */
459 signalling = !(a->sigh & 0x40000000);
460 }
461 } else
462 #ifdef PARANOID
463 if (tagb == TW_NaN)
464 #endif /* PARANOID */
465 {
466 signalling = !(b->sigh & 0x40000000);
467 x = b;
468 }
469 #ifdef PARANOID
470 else {
471 signalling = 0;
472 EXCEPTION(EX_INTERNAL | 0x113);
473 x = &CONST_QNaN;
474 }
475 #endif /* PARANOID */
476
477 if ((!signalling) || (control_word & CW_Invalid)) {
478 if (!x)
479 x = b;
480
481 if (!(x->sigh & 0x80000000)) /* pseudo-NaN ? */
482 x = &CONST_QNaN;
483
484 FPU_copy_to_regi(x, TAG_Special, deststnr);
485
486 if (!signalling)
487 return TAG_Special;
488
489 /* ensure a Quiet NaN */
490 dest->sigh |= 0x40000000;
491 }
492
493 EXCEPTION(EX_Invalid);
494
495 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special;
496 }
497
498 /* Invalid arith operation on Valid registers */
499 /* Returns < 0 if the exception is unmasked */
arith_invalid(int deststnr)500 asmlinkage int arith_invalid(int deststnr)
501 {
502
503 EXCEPTION(EX_Invalid);
504
505 if (control_word & CW_Invalid) {
506 /* The masked response */
507 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr);
508 }
509
510 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Valid;
511
512 }
513
514 /* Divide a finite number by zero */
FPU_divide_by_zero(int deststnr,u_char sign)515 asmlinkage int FPU_divide_by_zero(int deststnr, u_char sign)
516 {
517 FPU_REG *dest = &st(deststnr);
518 int tag = TAG_Valid;
519
520 if (control_word & CW_ZeroDiv) {
521 /* The masked response */
522 FPU_copy_to_regi(&CONST_INF, TAG_Special, deststnr);
523 setsign(dest, sign);
524 tag = TAG_Special;
525 }
526
527 EXCEPTION(EX_ZeroDiv);
528
529 return (!(control_word & CW_ZeroDiv) ? FPU_Exception : 0) | tag;
530
531 }
532
533 /* This may be called often, so keep it lean */
set_precision_flag(int flags)534 int set_precision_flag(int flags)
535 {
536 if (control_word & CW_Precision) {
537 partial_status &= ~(SW_C1 & flags);
538 partial_status |= flags; /* The masked response */
539 return 0;
540 } else {
541 EXCEPTION(flags);
542 return 1;
543 }
544 }
545
546 /* This may be called often, so keep it lean */
set_precision_flag_up(void)547 asmlinkage void set_precision_flag_up(void)
548 {
549 if (control_word & CW_Precision)
550 partial_status |= (SW_Precision | SW_C1); /* The masked response */
551 else
552 EXCEPTION(EX_Precision | SW_C1);
553 }
554
555 /* This may be called often, so keep it lean */
set_precision_flag_down(void)556 asmlinkage void set_precision_flag_down(void)
557 {
558 if (control_word & CW_Precision) { /* The masked response */
559 partial_status &= ~SW_C1;
560 partial_status |= SW_Precision;
561 } else
562 EXCEPTION(EX_Precision);
563 }
564
denormal_operand(void)565 asmlinkage int denormal_operand(void)
566 {
567 if (control_word & CW_Denormal) { /* The masked response */
568 partial_status |= SW_Denorm_Op;
569 return TAG_Special;
570 } else {
571 EXCEPTION(EX_Denormal);
572 return TAG_Special | FPU_Exception;
573 }
574 }
575
arith_overflow(FPU_REG * dest)576 asmlinkage int arith_overflow(FPU_REG *dest)
577 {
578 int tag = TAG_Valid;
579
580 if (control_word & CW_Overflow) {
581 /* The masked response */
582 /* ###### The response here depends upon the rounding mode */
583 reg_copy(&CONST_INF, dest);
584 tag = TAG_Special;
585 } else {
586 /* Subtract the magic number from the exponent */
587 addexponent(dest, (-3 * (1 << 13)));
588 }
589
590 EXCEPTION(EX_Overflow);
591 if (control_word & CW_Overflow) {
592 /* The overflow exception is masked. */
593 /* By definition, precision is lost.
594 The roundup bit (C1) is also set because we have
595 "rounded" upwards to Infinity. */
596 EXCEPTION(EX_Precision | SW_C1);
597 return tag;
598 }
599
600 return tag;
601
602 }
603
arith_underflow(FPU_REG * dest)604 asmlinkage int arith_underflow(FPU_REG *dest)
605 {
606 int tag = TAG_Valid;
607
608 if (control_word & CW_Underflow) {
609 /* The masked response */
610 if (exponent16(dest) <= EXP_UNDER - 63) {
611 reg_copy(&CONST_Z, dest);
612 partial_status &= ~SW_C1; /* Round down. */
613 tag = TAG_Zero;
614 } else {
615 stdexp(dest);
616 }
617 } else {
618 /* Add the magic number to the exponent. */
619 addexponent(dest, (3 * (1 << 13)) + EXTENDED_Ebias);
620 }
621
622 EXCEPTION(EX_Underflow);
623 if (control_word & CW_Underflow) {
624 /* The underflow exception is masked. */
625 EXCEPTION(EX_Precision);
626 return tag;
627 }
628
629 return tag;
630
631 }
632
FPU_stack_overflow(void)633 void FPU_stack_overflow(void)
634 {
635
636 if (control_word & CW_Invalid) {
637 /* The masked response */
638 top--;
639 FPU_copy_to_reg0(&CONST_QNaN, TAG_Special);
640 }
641
642 EXCEPTION(EX_StackOver);
643
644 return;
645
646 }
647
FPU_stack_underflow(void)648 void FPU_stack_underflow(void)
649 {
650
651 if (control_word & CW_Invalid) {
652 /* The masked response */
653 FPU_copy_to_reg0(&CONST_QNaN, TAG_Special);
654 }
655
656 EXCEPTION(EX_StackUnder);
657
658 return;
659
660 }
661
FPU_stack_underflow_i(int i)662 void FPU_stack_underflow_i(int i)
663 {
664
665 if (control_word & CW_Invalid) {
666 /* The masked response */
667 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i);
668 }
669
670 EXCEPTION(EX_StackUnder);
671
672 return;
673
674 }
675
FPU_stack_underflow_pop(int i)676 void FPU_stack_underflow_pop(int i)
677 {
678
679 if (control_word & CW_Invalid) {
680 /* The masked response */
681 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i);
682 FPU_pop();
683 }
684
685 EXCEPTION(EX_StackUnder);
686
687 return;
688
689 }
690