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