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 <linux/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 __visible 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 /* Get a name string for error reporting */ 334 for (i = 0; exception_names[i].type; i++) 335 if ((exception_names[i].type & n) == 336 exception_names[i].type) 337 break; 338 339 if (exception_names[i].type) { 340 #ifdef PRINT_MESSAGES 341 printk("FP Exception: %s!\n", exception_names[i].name); 342 #endif /* PRINT_MESSAGES */ 343 } else 344 printk("FPU emulator: Unknown Exception: 0x%04x!\n", n); 345 346 if (n == EX_INTERNAL) { 347 printk("FPU emulator: Internal error type 0x%04x\n", 348 int_type); 349 FPU_printall(); 350 } 351 #ifdef PRINT_MESSAGES 352 else 353 FPU_printall(); 354 #endif /* PRINT_MESSAGES */ 355 356 /* 357 * The 80486 generates an interrupt on the next non-control FPU 358 * instruction. So we need some means of flagging it. 359 * We use the ES (Error Summary) bit for this. 360 */ 361 } 362 RE_ENTRANT_CHECK_ON; 363 364 #ifdef __DEBUG__ 365 math_abort(FPU_info, SIGFPE); 366 #endif /* __DEBUG__ */ 367 368 } 369 370 /* Real operation attempted on a NaN. */ 371 /* Returns < 0 if the exception is unmasked */ 372 int real_1op_NaN(FPU_REG *a) 373 { 374 int signalling, isNaN; 375 376 isNaN = (exponent(a) == EXP_OVER) && (a->sigh & 0x80000000); 377 378 /* The default result for the case of two "equal" NaNs (signs may 379 differ) is chosen to reproduce 80486 behaviour */ 380 signalling = isNaN && !(a->sigh & 0x40000000); 381 382 if (!signalling) { 383 if (!isNaN) { /* pseudo-NaN, or other unsupported? */ 384 if (control_word & CW_Invalid) { 385 /* Masked response */ 386 reg_copy(&CONST_QNaN, a); 387 } 388 EXCEPTION(EX_Invalid); 389 return (!(control_word & CW_Invalid) ? FPU_Exception : 390 0) | TAG_Special; 391 } 392 return TAG_Special; 393 } 394 395 if (control_word & CW_Invalid) { 396 /* The masked response */ 397 if (!(a->sigh & 0x80000000)) { /* pseudo-NaN ? */ 398 reg_copy(&CONST_QNaN, a); 399 } 400 /* ensure a Quiet NaN */ 401 a->sigh |= 0x40000000; 402 } 403 404 EXCEPTION(EX_Invalid); 405 406 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special; 407 } 408 409 /* Real operation attempted on two operands, one a NaN. */ 410 /* Returns < 0 if the exception is unmasked */ 411 int real_2op_NaN(FPU_REG const *b, u_char tagb, 412 int deststnr, FPU_REG const *defaultNaN) 413 { 414 FPU_REG *dest = &st(deststnr); 415 FPU_REG const *a = dest; 416 u_char taga = FPU_gettagi(deststnr); 417 FPU_REG const *x; 418 int signalling, unsupported; 419 420 if (taga == TAG_Special) 421 taga = FPU_Special(a); 422 if (tagb == TAG_Special) 423 tagb = FPU_Special(b); 424 425 /* TW_NaN is also used for unsupported data types. */ 426 unsupported = ((taga == TW_NaN) 427 && !((exponent(a) == EXP_OVER) 428 && (a->sigh & 0x80000000))) 429 || ((tagb == TW_NaN) 430 && !((exponent(b) == EXP_OVER) && (b->sigh & 0x80000000))); 431 if (unsupported) { 432 if (control_word & CW_Invalid) { 433 /* Masked response */ 434 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr); 435 } 436 EXCEPTION(EX_Invalid); 437 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | 438 TAG_Special; 439 } 440 441 if (taga == TW_NaN) { 442 x = a; 443 if (tagb == TW_NaN) { 444 signalling = !(a->sigh & b->sigh & 0x40000000); 445 if (significand(b) > significand(a)) 446 x = b; 447 else if (significand(b) == significand(a)) { 448 /* The default result for the case of two "equal" NaNs (signs may 449 differ) is chosen to reproduce 80486 behaviour */ 450 x = defaultNaN; 451 } 452 } else { 453 /* return the quiet version of the NaN in a */ 454 signalling = !(a->sigh & 0x40000000); 455 } 456 } else 457 #ifdef PARANOID 458 if (tagb == TW_NaN) 459 #endif /* PARANOID */ 460 { 461 signalling = !(b->sigh & 0x40000000); 462 x = b; 463 } 464 #ifdef PARANOID 465 else { 466 signalling = 0; 467 EXCEPTION(EX_INTERNAL | 0x113); 468 x = &CONST_QNaN; 469 } 470 #endif /* PARANOID */ 471 472 if ((!signalling) || (control_word & CW_Invalid)) { 473 if (!x) 474 x = b; 475 476 if (!(x->sigh & 0x80000000)) /* pseudo-NaN ? */ 477 x = &CONST_QNaN; 478 479 FPU_copy_to_regi(x, TAG_Special, deststnr); 480 481 if (!signalling) 482 return TAG_Special; 483 484 /* ensure a Quiet NaN */ 485 dest->sigh |= 0x40000000; 486 } 487 488 EXCEPTION(EX_Invalid); 489 490 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special; 491 } 492 493 /* Invalid arith operation on Valid registers */ 494 /* Returns < 0 if the exception is unmasked */ 495 asmlinkage __visible int arith_invalid(int deststnr) 496 { 497 498 EXCEPTION(EX_Invalid); 499 500 if (control_word & CW_Invalid) { 501 /* The masked response */ 502 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr); 503 } 504 505 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Valid; 506 507 } 508 509 /* Divide a finite number by zero */ 510 asmlinkage __visible int FPU_divide_by_zero(int deststnr, u_char sign) 511 { 512 FPU_REG *dest = &st(deststnr); 513 int tag = TAG_Valid; 514 515 if (control_word & CW_ZeroDiv) { 516 /* The masked response */ 517 FPU_copy_to_regi(&CONST_INF, TAG_Special, deststnr); 518 setsign(dest, sign); 519 tag = TAG_Special; 520 } 521 522 EXCEPTION(EX_ZeroDiv); 523 524 return (!(control_word & CW_ZeroDiv) ? FPU_Exception : 0) | tag; 525 526 } 527 528 /* This may be called often, so keep it lean */ 529 int set_precision_flag(int flags) 530 { 531 if (control_word & CW_Precision) { 532 partial_status &= ~(SW_C1 & flags); 533 partial_status |= flags; /* The masked response */ 534 return 0; 535 } else { 536 EXCEPTION(flags); 537 return 1; 538 } 539 } 540 541 /* This may be called often, so keep it lean */ 542 asmlinkage __visible void set_precision_flag_up(void) 543 { 544 if (control_word & CW_Precision) 545 partial_status |= (SW_Precision | SW_C1); /* The masked response */ 546 else 547 EXCEPTION(EX_Precision | SW_C1); 548 } 549 550 /* This may be called often, so keep it lean */ 551 asmlinkage __visible void set_precision_flag_down(void) 552 { 553 if (control_word & CW_Precision) { /* The masked response */ 554 partial_status &= ~SW_C1; 555 partial_status |= SW_Precision; 556 } else 557 EXCEPTION(EX_Precision); 558 } 559 560 asmlinkage __visible int denormal_operand(void) 561 { 562 if (control_word & CW_Denormal) { /* The masked response */ 563 partial_status |= SW_Denorm_Op; 564 return TAG_Special; 565 } else { 566 EXCEPTION(EX_Denormal); 567 return TAG_Special | FPU_Exception; 568 } 569 } 570 571 asmlinkage __visible int arith_overflow(FPU_REG *dest) 572 { 573 int tag = TAG_Valid; 574 575 if (control_word & CW_Overflow) { 576 /* The masked response */ 577 /* ###### The response here depends upon the rounding mode */ 578 reg_copy(&CONST_INF, dest); 579 tag = TAG_Special; 580 } else { 581 /* Subtract the magic number from the exponent */ 582 addexponent(dest, (-3 * (1 << 13))); 583 } 584 585 EXCEPTION(EX_Overflow); 586 if (control_word & CW_Overflow) { 587 /* The overflow exception is masked. */ 588 /* By definition, precision is lost. 589 The roundup bit (C1) is also set because we have 590 "rounded" upwards to Infinity. */ 591 EXCEPTION(EX_Precision | SW_C1); 592 return tag; 593 } 594 595 return tag; 596 597 } 598 599 asmlinkage __visible int arith_underflow(FPU_REG *dest) 600 { 601 int tag = TAG_Valid; 602 603 if (control_word & CW_Underflow) { 604 /* The masked response */ 605 if (exponent16(dest) <= EXP_UNDER - 63) { 606 reg_copy(&CONST_Z, dest); 607 partial_status &= ~SW_C1; /* Round down. */ 608 tag = TAG_Zero; 609 } else { 610 stdexp(dest); 611 } 612 } else { 613 /* Add the magic number to the exponent. */ 614 addexponent(dest, (3 * (1 << 13)) + EXTENDED_Ebias); 615 } 616 617 EXCEPTION(EX_Underflow); 618 if (control_word & CW_Underflow) { 619 /* The underflow exception is masked. */ 620 EXCEPTION(EX_Precision); 621 return tag; 622 } 623 624 return tag; 625 626 } 627 628 void FPU_stack_overflow(void) 629 { 630 631 if (control_word & CW_Invalid) { 632 /* The masked response */ 633 top--; 634 FPU_copy_to_reg0(&CONST_QNaN, TAG_Special); 635 } 636 637 EXCEPTION(EX_StackOver); 638 639 return; 640 641 } 642 643 void FPU_stack_underflow(void) 644 { 645 646 if (control_word & CW_Invalid) { 647 /* The masked response */ 648 FPU_copy_to_reg0(&CONST_QNaN, TAG_Special); 649 } 650 651 EXCEPTION(EX_StackUnder); 652 653 return; 654 655 } 656 657 void FPU_stack_underflow_i(int i) 658 { 659 660 if (control_word & CW_Invalid) { 661 /* The masked response */ 662 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i); 663 } 664 665 EXCEPTION(EX_StackUnder); 666 667 return; 668 669 } 670 671 void FPU_stack_underflow_pop(int i) 672 { 673 674 if (control_word & CW_Invalid) { 675 /* The masked response */ 676 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i); 677 FPU_pop(); 678 } 679 680 EXCEPTION(EX_StackUnder); 681 682 return; 683 684 } 685