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 */ 77 void FPU_illegal(void) 78 { 79 math_abort(FPU_info, SIGILL); 80 } 81 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 switch (tagi) { 182 case TAG_Empty: 183 continue; 184 break; 185 case TAG_Zero: 186 case TAG_Special: 187 tagi = FPU_Special(r); 188 case TAG_Valid: 189 printk("st(%d) %c .%04lx %04lx %04lx %04lx e%+-6d ", i, 190 getsign(r) ? '-' : '+', 191 (long)(r->sigh >> 16), 192 (long)(r->sigh & 0xFFFF), 193 (long)(r->sigl >> 16), 194 (long)(r->sigl & 0xFFFF), 195 exponent(r) - EXP_BIAS + 1); 196 break; 197 default: 198 printk("Whoops! Error in errors.c: tag%d is %d ", i, 199 tagi); 200 continue; 201 break; 202 } 203 printk("%s\n", tag_desc[(int)(unsigned)tagi]); 204 } 205 206 RE_ENTRANT_CHECK_ON; 207 208 } 209 210 static struct { 211 int type; 212 const char *name; 213 } exception_names[] = { 214 { 215 EX_StackOver, "stack overflow"}, { 216 EX_StackUnder, "stack underflow"}, { 217 EX_Precision, "loss of precision"}, { 218 EX_Underflow, "underflow"}, { 219 EX_Overflow, "overflow"}, { 220 EX_ZeroDiv, "divide by zero"}, { 221 EX_Denormal, "denormalized operand"}, { 222 EX_Invalid, "invalid operation"}, { 223 EX_INTERNAL, "INTERNAL BUG in " FPU_VERSION}, { 224 0, NULL} 225 }; 226 227 /* 228 EX_INTERNAL is always given with a code which indicates where the 229 error was detected. 230 231 Internal error types: 232 0x14 in fpu_etc.c 233 0x1nn in a *.c file: 234 0x101 in reg_add_sub.c 235 0x102 in reg_mul.c 236 0x104 in poly_atan.c 237 0x105 in reg_mul.c 238 0x107 in fpu_trig.c 239 0x108 in reg_compare.c 240 0x109 in reg_compare.c 241 0x110 in reg_add_sub.c 242 0x111 in fpe_entry.c 243 0x112 in fpu_trig.c 244 0x113 in errors.c 245 0x115 in fpu_trig.c 246 0x116 in fpu_trig.c 247 0x117 in fpu_trig.c 248 0x118 in fpu_trig.c 249 0x119 in fpu_trig.c 250 0x120 in poly_atan.c 251 0x121 in reg_compare.c 252 0x122 in reg_compare.c 253 0x123 in reg_compare.c 254 0x125 in fpu_trig.c 255 0x126 in fpu_entry.c 256 0x127 in poly_2xm1.c 257 0x128 in fpu_entry.c 258 0x129 in fpu_entry.c 259 0x130 in get_address.c 260 0x131 in get_address.c 261 0x132 in get_address.c 262 0x133 in get_address.c 263 0x140 in load_store.c 264 0x141 in load_store.c 265 0x150 in poly_sin.c 266 0x151 in poly_sin.c 267 0x160 in reg_ld_str.c 268 0x161 in reg_ld_str.c 269 0x162 in reg_ld_str.c 270 0x163 in reg_ld_str.c 271 0x164 in reg_ld_str.c 272 0x170 in fpu_tags.c 273 0x171 in fpu_tags.c 274 0x172 in fpu_tags.c 275 0x180 in reg_convert.c 276 0x2nn in an *.S file: 277 0x201 in reg_u_add.S 278 0x202 in reg_u_div.S 279 0x203 in reg_u_div.S 280 0x204 in reg_u_div.S 281 0x205 in reg_u_mul.S 282 0x206 in reg_u_sub.S 283 0x207 in wm_sqrt.S 284 0x208 in reg_div.S 285 0x209 in reg_u_sub.S 286 0x210 in reg_u_sub.S 287 0x211 in reg_u_sub.S 288 0x212 in reg_u_sub.S 289 0x213 in wm_sqrt.S 290 0x214 in wm_sqrt.S 291 0x215 in wm_sqrt.S 292 0x220 in reg_norm.S 293 0x221 in reg_norm.S 294 0x230 in reg_round.S 295 0x231 in reg_round.S 296 0x232 in reg_round.S 297 0x233 in reg_round.S 298 0x234 in reg_round.S 299 0x235 in reg_round.S 300 0x236 in reg_round.S 301 0x240 in div_Xsig.S 302 0x241 in div_Xsig.S 303 0x242 in div_Xsig.S 304 */ 305 306 asmlinkage __visible void FPU_exception(int n) 307 { 308 int i, int_type; 309 310 int_type = 0; /* Needed only to stop compiler warnings */ 311 if (n & EX_INTERNAL) { 312 int_type = n - EX_INTERNAL; 313 n = EX_INTERNAL; 314 /* Set lots of exception bits! */ 315 partial_status |= (SW_Exc_Mask | SW_Summary | SW_Backward); 316 } else { 317 /* Extract only the bits which we use to set the status word */ 318 n &= (SW_Exc_Mask); 319 /* Set the corresponding exception bit */ 320 partial_status |= n; 321 /* Set summary bits iff exception isn't masked */ 322 if (partial_status & ~control_word & CW_Exceptions) 323 partial_status |= (SW_Summary | SW_Backward); 324 if (n & (SW_Stack_Fault | EX_Precision)) { 325 if (!(n & SW_C1)) 326 /* This bit distinguishes over- from underflow for a stack fault, 327 and roundup from round-down for precision loss. */ 328 partial_status &= ~SW_C1; 329 } 330 } 331 332 RE_ENTRANT_CHECK_OFF; 333 if ((~control_word & n & CW_Exceptions) || (n == EX_INTERNAL)) { 334 /* Get a name string for error reporting */ 335 for (i = 0; exception_names[i].type; i++) 336 if ((exception_names[i].type & n) == 337 exception_names[i].type) 338 break; 339 340 if (exception_names[i].type) { 341 #ifdef PRINT_MESSAGES 342 printk("FP Exception: %s!\n", exception_names[i].name); 343 #endif /* PRINT_MESSAGES */ 344 } else 345 printk("FPU emulator: Unknown Exception: 0x%04x!\n", n); 346 347 if (n == EX_INTERNAL) { 348 printk("FPU emulator: Internal error type 0x%04x\n", 349 int_type); 350 FPU_printall(); 351 } 352 #ifdef PRINT_MESSAGES 353 else 354 FPU_printall(); 355 #endif /* PRINT_MESSAGES */ 356 357 /* 358 * The 80486 generates an interrupt on the next non-control FPU 359 * instruction. So we need some means of flagging it. 360 * We use the ES (Error Summary) bit for this. 361 */ 362 } 363 RE_ENTRANT_CHECK_ON; 364 365 #ifdef __DEBUG__ 366 math_abort(FPU_info, SIGFPE); 367 #endif /* __DEBUG__ */ 368 369 } 370 371 /* Real operation attempted on a NaN. */ 372 /* Returns < 0 if the exception is unmasked */ 373 int real_1op_NaN(FPU_REG *a) 374 { 375 int signalling, isNaN; 376 377 isNaN = (exponent(a) == EXP_OVER) && (a->sigh & 0x80000000); 378 379 /* The default result for the case of two "equal" NaNs (signs may 380 differ) is chosen to reproduce 80486 behaviour */ 381 signalling = isNaN && !(a->sigh & 0x40000000); 382 383 if (!signalling) { 384 if (!isNaN) { /* pseudo-NaN, or other unsupported? */ 385 if (control_word & CW_Invalid) { 386 /* Masked response */ 387 reg_copy(&CONST_QNaN, a); 388 } 389 EXCEPTION(EX_Invalid); 390 return (!(control_word & CW_Invalid) ? FPU_Exception : 391 0) | TAG_Special; 392 } 393 return TAG_Special; 394 } 395 396 if (control_word & CW_Invalid) { 397 /* The masked response */ 398 if (!(a->sigh & 0x80000000)) { /* pseudo-NaN ? */ 399 reg_copy(&CONST_QNaN, a); 400 } 401 /* ensure a Quiet NaN */ 402 a->sigh |= 0x40000000; 403 } 404 405 EXCEPTION(EX_Invalid); 406 407 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special; 408 } 409 410 /* Real operation attempted on two operands, one a NaN. */ 411 /* Returns < 0 if the exception is unmasked */ 412 int real_2op_NaN(FPU_REG const *b, u_char tagb, 413 int deststnr, FPU_REG const *defaultNaN) 414 { 415 FPU_REG *dest = &st(deststnr); 416 FPU_REG const *a = dest; 417 u_char taga = FPU_gettagi(deststnr); 418 FPU_REG const *x; 419 int signalling, unsupported; 420 421 if (taga == TAG_Special) 422 taga = FPU_Special(a); 423 if (tagb == TAG_Special) 424 tagb = FPU_Special(b); 425 426 /* TW_NaN is also used for unsupported data types. */ 427 unsupported = ((taga == TW_NaN) 428 && !((exponent(a) == EXP_OVER) 429 && (a->sigh & 0x80000000))) 430 || ((tagb == TW_NaN) 431 && !((exponent(b) == EXP_OVER) && (b->sigh & 0x80000000))); 432 if (unsupported) { 433 if (control_word & CW_Invalid) { 434 /* Masked response */ 435 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr); 436 } 437 EXCEPTION(EX_Invalid); 438 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | 439 TAG_Special; 440 } 441 442 if (taga == TW_NaN) { 443 x = a; 444 if (tagb == TW_NaN) { 445 signalling = !(a->sigh & b->sigh & 0x40000000); 446 if (significand(b) > significand(a)) 447 x = b; 448 else if (significand(b) == significand(a)) { 449 /* The default result for the case of two "equal" NaNs (signs may 450 differ) is chosen to reproduce 80486 behaviour */ 451 x = defaultNaN; 452 } 453 } else { 454 /* return the quiet version of the NaN in a */ 455 signalling = !(a->sigh & 0x40000000); 456 } 457 } else 458 #ifdef PARANOID 459 if (tagb == TW_NaN) 460 #endif /* PARANOID */ 461 { 462 signalling = !(b->sigh & 0x40000000); 463 x = b; 464 } 465 #ifdef PARANOID 466 else { 467 signalling = 0; 468 EXCEPTION(EX_INTERNAL | 0x113); 469 x = &CONST_QNaN; 470 } 471 #endif /* PARANOID */ 472 473 if ((!signalling) || (control_word & CW_Invalid)) { 474 if (!x) 475 x = b; 476 477 if (!(x->sigh & 0x80000000)) /* pseudo-NaN ? */ 478 x = &CONST_QNaN; 479 480 FPU_copy_to_regi(x, TAG_Special, deststnr); 481 482 if (!signalling) 483 return TAG_Special; 484 485 /* ensure a Quiet NaN */ 486 dest->sigh |= 0x40000000; 487 } 488 489 EXCEPTION(EX_Invalid); 490 491 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Special; 492 } 493 494 /* Invalid arith operation on Valid registers */ 495 /* Returns < 0 if the exception is unmasked */ 496 asmlinkage __visible int arith_invalid(int deststnr) 497 { 498 499 EXCEPTION(EX_Invalid); 500 501 if (control_word & CW_Invalid) { 502 /* The masked response */ 503 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, deststnr); 504 } 505 506 return (!(control_word & CW_Invalid) ? FPU_Exception : 0) | TAG_Valid; 507 508 } 509 510 /* Divide a finite number by zero */ 511 asmlinkage __visible int FPU_divide_by_zero(int deststnr, u_char sign) 512 { 513 FPU_REG *dest = &st(deststnr); 514 int tag = TAG_Valid; 515 516 if (control_word & CW_ZeroDiv) { 517 /* The masked response */ 518 FPU_copy_to_regi(&CONST_INF, TAG_Special, deststnr); 519 setsign(dest, sign); 520 tag = TAG_Special; 521 } 522 523 EXCEPTION(EX_ZeroDiv); 524 525 return (!(control_word & CW_ZeroDiv) ? FPU_Exception : 0) | tag; 526 527 } 528 529 /* This may be called often, so keep it lean */ 530 int set_precision_flag(int flags) 531 { 532 if (control_word & CW_Precision) { 533 partial_status &= ~(SW_C1 & flags); 534 partial_status |= flags; /* The masked response */ 535 return 0; 536 } else { 537 EXCEPTION(flags); 538 return 1; 539 } 540 } 541 542 /* This may be called often, so keep it lean */ 543 asmlinkage __visible void set_precision_flag_up(void) 544 { 545 if (control_word & CW_Precision) 546 partial_status |= (SW_Precision | SW_C1); /* The masked response */ 547 else 548 EXCEPTION(EX_Precision | SW_C1); 549 } 550 551 /* This may be called often, so keep it lean */ 552 asmlinkage __visible void set_precision_flag_down(void) 553 { 554 if (control_word & CW_Precision) { /* The masked response */ 555 partial_status &= ~SW_C1; 556 partial_status |= SW_Precision; 557 } else 558 EXCEPTION(EX_Precision); 559 } 560 561 asmlinkage __visible int denormal_operand(void) 562 { 563 if (control_word & CW_Denormal) { /* The masked response */ 564 partial_status |= SW_Denorm_Op; 565 return TAG_Special; 566 } else { 567 EXCEPTION(EX_Denormal); 568 return TAG_Special | FPU_Exception; 569 } 570 } 571 572 asmlinkage __visible int arith_overflow(FPU_REG *dest) 573 { 574 int tag = TAG_Valid; 575 576 if (control_word & CW_Overflow) { 577 /* The masked response */ 578 /* ###### The response here depends upon the rounding mode */ 579 reg_copy(&CONST_INF, dest); 580 tag = TAG_Special; 581 } else { 582 /* Subtract the magic number from the exponent */ 583 addexponent(dest, (-3 * (1 << 13))); 584 } 585 586 EXCEPTION(EX_Overflow); 587 if (control_word & CW_Overflow) { 588 /* The overflow exception is masked. */ 589 /* By definition, precision is lost. 590 The roundup bit (C1) is also set because we have 591 "rounded" upwards to Infinity. */ 592 EXCEPTION(EX_Precision | SW_C1); 593 return tag; 594 } 595 596 return tag; 597 598 } 599 600 asmlinkage __visible int arith_underflow(FPU_REG *dest) 601 { 602 int tag = TAG_Valid; 603 604 if (control_word & CW_Underflow) { 605 /* The masked response */ 606 if (exponent16(dest) <= EXP_UNDER - 63) { 607 reg_copy(&CONST_Z, dest); 608 partial_status &= ~SW_C1; /* Round down. */ 609 tag = TAG_Zero; 610 } else { 611 stdexp(dest); 612 } 613 } else { 614 /* Add the magic number to the exponent. */ 615 addexponent(dest, (3 * (1 << 13)) + EXTENDED_Ebias); 616 } 617 618 EXCEPTION(EX_Underflow); 619 if (control_word & CW_Underflow) { 620 /* The underflow exception is masked. */ 621 EXCEPTION(EX_Precision); 622 return tag; 623 } 624 625 return tag; 626 627 } 628 629 void FPU_stack_overflow(void) 630 { 631 632 if (control_word & CW_Invalid) { 633 /* The masked response */ 634 top--; 635 FPU_copy_to_reg0(&CONST_QNaN, TAG_Special); 636 } 637 638 EXCEPTION(EX_StackOver); 639 640 return; 641 642 } 643 644 void FPU_stack_underflow(void) 645 { 646 647 if (control_word & CW_Invalid) { 648 /* The masked response */ 649 FPU_copy_to_reg0(&CONST_QNaN, TAG_Special); 650 } 651 652 EXCEPTION(EX_StackUnder); 653 654 return; 655 656 } 657 658 void FPU_stack_underflow_i(int i) 659 { 660 661 if (control_word & CW_Invalid) { 662 /* The masked response */ 663 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i); 664 } 665 666 EXCEPTION(EX_StackUnder); 667 668 return; 669 670 } 671 672 void FPU_stack_underflow_pop(int i) 673 { 674 675 if (control_word & CW_Invalid) { 676 /* The masked response */ 677 FPU_copy_to_regi(&CONST_QNaN, TAG_Special, i); 678 FPU_pop(); 679 } 680 681 EXCEPTION(EX_StackUnder); 682 683 return; 684 685 } 686