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 */ 76 void FPU_illegal(void) 77 { 78 math_abort(FPU_info, SIGILL); 79 } 80 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 */ 304 305 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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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 } 564 565 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 } 575 576 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 } 603 604 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 } 632 633 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 } 647 648 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 } 661 662 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 } 675 676 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