drivers/FPU-emu/errors.c

/* */
This source file includes following definitions.
Un_impl
FPU_illegal
emu_printall
exception
real_2op_NaN
arith_invalid
divide_by_zero
set_precision_flag
set_precision_flag_up
set_precision_flag_down
denormal_operand
arith_overflow
arith_underflow
stack_overflow
stack_underflow
stack_underflow_i
stack_underflow_pop
   1 /*---------------------------------------------------------------------------+
   2  |  errors.c                                                                 |
   3  |                                                                           |
   4  |  The error handling functions for wm-FPU-emu                              |
   5  |                                                                           |
   6  | Copyright (C) 1992,1993,1994                                              |
   7  |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   8  |                       Australia.  E-mail   billm@vaxc.cc.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/segment.h>
  23 
  24 #include "fpu_system.h"
  25 #include "exception.h"
  26 #include "fpu_emu.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 
  37 void Un_impl(void)
     /*  */
  38 {
  39   unsigned char byte1, FPU_modrm;
  40   unsigned long address = FPU_ORIG_EIP;
  41 
  42   RE_ENTRANT_CHECK_OFF;
  43   /* No need to verify_area(), we have previously fetched these bytes. */
  44   printk("Unimplemented FPU Opcode at eip=%p : ", (void *) address);
  45   if ( FPU_CS == USER_CS )
  46     {
  47       while ( 1 )
  48         {
  49           byte1 = get_fs_byte((unsigned char *) address);
  50           if ( (byte1 & 0xf8) == 0xd8 ) break;
  51           printk("[%02x]", byte1);
  52           address++;
  53         }
  54       printk("%02x ", byte1);
  55       FPU_modrm = get_fs_byte(1 + (unsigned char *) address);
  56       
  57       if (FPU_modrm >= 0300)
  58         printk("%02x (%02x+%d)\n", FPU_modrm, FPU_modrm & 0xf8, FPU_modrm & 7);
  59       else
  60         printk("/%d\n", (FPU_modrm >> 3) & 7);
  61     }
  62   else
  63     {
  64       printk("cs selector = %04x\n", FPU_CS);
  65     }
  66 
  67   RE_ENTRANT_CHECK_ON;
  68 
  69   EXCEPTION(EX_Invalid);
  70 
  71 }
  72 
  73 
  74 /*
  75    Called for opcodes which are illegal and which are known to result in a
  76    SIGILL with a real 80486.
  77    */
  78 void FPU_illegal(void)
     /*  */
  79 {
  80   math_abort(FPU_info,SIGILL);
  81 }
  82 
  83 
  84 
  85 void emu_printall()
     /*  */
  86 {
  87   int i;
  88   static char *tag_desc[] = { "Valid", "Zero", "ERROR", "ERROR",
  89                               "DeNorm", "Inf", "NaN", "Empty" };
  90   unsigned char byte1, FPU_modrm;
  91   unsigned long address = FPU_ORIG_EIP;
  92 
  93   RE_ENTRANT_CHECK_OFF;
  94   /* No need to verify_area(), we have previously fetched these bytes. */
  95   printk("At %p:", (void *) address);
  96   if ( FPU_CS == USER_CS )
  97     {
  98 #define MAX_PRINTED_BYTES 20
  99       for ( i = 0; i < MAX_PRINTED_BYTES; i++ )
 100         {
 101           byte1 = get_fs_byte((unsigned char *) address);
 102           if ( (byte1 & 0xf8) == 0xd8 )
 103             {
 104               printk(" %02x", byte1);
 105               break;
 106             }
 107           printk(" [%02x]", byte1);
 108           address++;
 109         }
 110       if ( i == MAX_PRINTED_BYTES )
 111         printk(" [more..]\n");
 112       else
 113         {
 114           FPU_modrm = get_fs_byte(1 + (unsigned char *) address);
 115           
 116           if (FPU_modrm >= 0300)
 117             printk(" %02x (%02x+%d)\n", FPU_modrm, FPU_modrm & 0xf8, FPU_modrm & 7);
 118           else
 119             printk(" /%d, mod=%d rm=%d\n",
 120                    (FPU_modrm >> 3) & 7, (FPU_modrm >> 6) & 3, FPU_modrm & 7);
 121         }
 122     }
 123   else
 124     {
 125       printk("%04x\n", FPU_CS);
 126     }
 127 
 128   partial_status = status_word();
 129 
 130 #ifdef DEBUGGING
 131 if ( partial_status & SW_Backward )    printk("SW: backward compatibility\n");
 132 if ( partial_status & SW_C3 )          printk("SW: condition bit 3\n");
 133 if ( partial_status & SW_C2 )          printk("SW: condition bit 2\n");
 134 if ( partial_status & SW_C1 )          printk("SW: condition bit 1\n");
 135 if ( partial_status & SW_C0 )          printk("SW: condition bit 0\n");
 136 if ( partial_status & SW_Summary )     printk("SW: exception summary\n");
 137 if ( partial_status & SW_Stack_Fault ) printk("SW: stack fault\n");
 138 if ( partial_status & SW_Precision )   printk("SW: loss of precision\n");
 139 if ( partial_status & SW_Underflow )   printk("SW: underflow\n");
 140 if ( partial_status & SW_Overflow )    printk("SW: overflow\n");
 141 if ( partial_status & SW_Zero_Div )    printk("SW: divide by zero\n");
 142 if ( partial_status & SW_Denorm_Op )   printk("SW: denormalized operand\n");
 143 if ( partial_status & SW_Invalid )     printk("SW: invalid operation\n");
 144 #endif DEBUGGING
 145 
 146   printk(" SW: b=%d st=%ld es=%d sf=%d cc=%d%d%d%d ef=%d%d%d%d%d%d\n",
 147          partial_status & 0x8000 ? 1 : 0,   /* busy */
 148          (partial_status & 0x3800) >> 11,   /* stack top pointer */
 149          partial_status & 0x80 ? 1 : 0,     /* Error summary status */
 150          partial_status & 0x40 ? 1 : 0,     /* Stack flag */
 151          partial_status & SW_C3?1:0, partial_status & SW_C2?1:0, /* cc */
 152          partial_status & SW_C1?1:0, partial_status & SW_C0?1:0, /* cc */
 153          partial_status & SW_Precision?1:0, partial_status & SW_Underflow?1:0,
 154          partial_status & SW_Overflow?1:0, partial_status & SW_Zero_Div?1:0,
 155          partial_status & SW_Denorm_Op?1:0, partial_status & SW_Invalid?1:0);
 156   
 157 printk(" CW: ic=%d rc=%ld%ld pc=%ld%ld iem=%d     ef=%d%d%d%d%d%d\n",
 158          control_word & 0x1000 ? 1 : 0,
 159          (control_word & 0x800) >> 11, (control_word & 0x400) >> 10,
 160          (control_word & 0x200) >> 9, (control_word & 0x100) >> 8,
 161          control_word & 0x80 ? 1 : 0,
 162          control_word & SW_Precision?1:0, control_word & SW_Underflow?1:0,
 163          control_word & SW_Overflow?1:0, control_word & SW_Zero_Div?1:0,
 164          control_word & SW_Denorm_Op?1:0, control_word & SW_Invalid?1:0);
 165 
 166   for ( i = 0; i < 8; i++ )
 167     {
 168       FPU_REG *r = &st(i);
 169       switch (r->tag)
 170         {
 171         case TW_Empty:
 172           continue;
 173           break;
 174         case TW_Zero:
 175 #if 0
 176           printk("st(%d)  %c .0000 0000 0000 0000         ",
 177                  i, r->sign ? '-' : '+');
 178           break;
 179 #endif
 180         case TW_Valid:
 181         case TW_NaN:
 182 /*      case TW_Denormal: */
 183         case TW_Infinity:
 184           printk("st(%d)  %c .%04lx %04lx %04lx %04lx e%+-6ld ", i,
 185                  r->sign ? '-' : '+',
 186                  (long)(r->sigh >> 16),
 187                  (long)(r->sigh & 0xFFFF),
 188                  (long)(r->sigl >> 16),
 189                  (long)(r->sigl & 0xFFFF),
 190                  r->exp - EXP_BIAS + 1);
 191           break;
 192         default:
 193           printk("Whoops! Error in errors.c      ");
 194           break;
 195         }
 196       printk("%s\n", tag_desc[(int) (unsigned) r->tag]);
 197     }
 198 
 199 #ifdef OBSOLETE
 200   printk("[data] %c .%04lx %04lx %04lx %04lx e%+-6ld ",
 201          FPU_loaded_data.sign ? '-' : '+',
 202          (long)(FPU_loaded_data.sigh >> 16),
 203          (long)(FPU_loaded_data.sigh & 0xFFFF),
 204          (long)(FPU_loaded_data.sigl >> 16),
 205          (long)(FPU_loaded_data.sigl & 0xFFFF),
 206          FPU_loaded_data.exp - EXP_BIAS + 1);
 207   printk("%s\n", tag_desc[(int) (unsigned) FPU_loaded_data.tag]);
 208 #endif OBSOLETE
 209   RE_ENTRANT_CHECK_ON;
 210 
 211 }
 212 
 213 static struct {
 214   int type;
 215   char *name;
 216 } exception_names[] = {
 217   { EX_StackOver, "stack overflow" },
 218   { EX_StackUnder, "stack underflow" },
 219   { EX_Precision, "loss of precision" },
 220   { EX_Underflow, "underflow" },
 221   { EX_Overflow, "overflow" },
 222   { EX_ZeroDiv, "divide by zero" },
 223   { EX_Denormal, "denormalized operand" },
 224   { EX_Invalid, "invalid operation" },
 225   { EX_INTERNAL, "INTERNAL BUG in "FPU_VERSION },
 226   { 0, NULL }
 227 };
 228 
 229 /*
 230  EX_INTERNAL is always given with a code which indicates where the
 231  error was detected.
 232 
 233  Internal error types:
 234        0x14   in fpu_etc.c
 235        0x1nn  in a *.c file:
 236               0x101  in reg_add_sub.c
 237               0x102  in reg_mul.c
 238               0x103  in poly_sin.c
 239               0x104  in poly_atan.c
 240               0x105  in reg_mul.c
 241               0x106  in reg_ld_str.c
 242               0x107  in fpu_trig.c
 243               0x108  in reg_compare.c
 244               0x109  in reg_compare.c
 245               0x110  in reg_add_sub.c
 246               0x111  in fpe_entry.c
 247               0x112  in fpu_trig.c
 248               0x113  in errors.c
 249               0x114  in reg_ld_str.c
 250               0x115  in fpu_trig.c
 251               0x116  in fpu_trig.c
 252               0x117  in fpu_trig.c
 253               0x118  in fpu_trig.c
 254               0x119  in fpu_trig.c
 255               0x120  in poly_atan.c
 256               0x121  in reg_compare.c
 257               0x122  in reg_compare.c
 258               0x123  in reg_compare.c
 259               0x125  in fpu_trig.c
 260               0x126  in fpu_entry.c
 261               0x127  in poly_2xm1.c
 262               0x128  in fpu_entry.c
 263               0x129  in fpu_entry.c
 264               0x130  in get_address.c
 265               0x131  in get_address.c
 266               0x132  in get_address.c
 267               0x133  in get_address.c
 268               0x140  in load_store.c
 269               0x141  in load_store.c
 270        0x2nn  in an *.S file:
 271               0x201  in reg_u_add.S
 272               0x202  in reg_u_div.S
 273               0x203  in reg_u_div.S
 274               0x204  in reg_u_div.S
 275               0x205  in reg_u_mul.S
 276               0x206  in reg_u_sub.S
 277               0x207  in wm_sqrt.S
 278               0x208  in reg_div.S
 279               0x209  in reg_u_sub.S
 280               0x210  in reg_u_sub.S
 281               0x211  in reg_u_sub.S
 282               0x212  in reg_u_sub.S
 283               0x213  in wm_sqrt.S
 284               0x214  in wm_sqrt.S
 285               0x215  in wm_sqrt.S
 286               0x220  in reg_norm.S
 287               0x221  in reg_norm.S
 288               0x230  in reg_round.S
 289               0x231  in reg_round.S
 290               0x232  in reg_round.S
 291               0x233  in reg_round.S
 292               0x234  in reg_round.S
 293               0x235  in reg_round.S
 294               0x236  in reg_round.S
 295  */
 296 
 297 void exception(int n)
     /*  */
 298 {
 299   int i, int_type;
 300 
 301   int_type = 0;         /* Needed only to stop compiler warnings */
 302   if ( n & EX_INTERNAL )
 303     {
 304       int_type = n - EX_INTERNAL;
 305       n = EX_INTERNAL;
 306       /* Set lots of exception bits! */
 307       partial_status |= (SW_Exc_Mask | SW_Summary | SW_Backward);
 308     }
 309   else
 310     {
 311       /* Extract only the bits which we use to set the status word */
 312       n &= (SW_Exc_Mask);
 313       /* Set the corresponding exception bit */
 314       partial_status |= n;
 315       /* Set summary bits iff exception isn't masked */
 316       if ( partial_status & ~control_word & CW_Exceptions )
 317         partial_status |= (SW_Summary | SW_Backward);
 318       if ( n & (SW_Stack_Fault | EX_Precision) )
 319         {
 320           if ( !(n & SW_C1) )
 321             /* This bit distinguishes over- from underflow for a stack fault,
 322                and roundup from round-down for precision loss. */
 323             partial_status &= ~SW_C1;
 324         }
 325     }
 326 
 327   RE_ENTRANT_CHECK_OFF;
 328   if ( (~control_word & n & CW_Exceptions) || (n == EX_INTERNAL) )
 329     {
 330 #ifdef PRINT_MESSAGES
 331       /* My message from the sponsor */
 332       printk(FPU_VERSION" "__DATE__" (C) W. Metzenthen.\n");
 333 #endif PRINT_MESSAGES
 334       
 335       /* Get a name string for error reporting */
 336       for (i=0; exception_names[i].type; i++)
 337         if ( (exception_names[i].type & n) == exception_names[i].type )
 338           break;
 339       
 340       if (exception_names[i].type)
 341         {
 342 #ifdef PRINT_MESSAGES
 343           printk("FP Exception: %s!\n", exception_names[i].name);
 344 #endif PRINT_MESSAGES
 345         }
 346       else
 347         printk("FPU emulator: Unknown Exception: 0x%04x!\n", n);
 348       
 349       if ( n == EX_INTERNAL )
 350         {
 351           printk("FPU emulator: Internal error type 0x%04x\n", int_type);
 352           emu_printall();
 353         }
 354 #ifdef PRINT_MESSAGES
 355       else
 356         emu_printall();
 357 #endif PRINT_MESSAGES
 358 
 359       /*
 360        * The 80486 generates an interrupt on the next non-control FPU
 361        * instruction. So we need some means of flagging it.
 362        * We use the ES (Error Summary) bit for this, assuming that
 363        * this is the way a real FPU does it (until I can check it out),
 364        * if not, then some method such as the following kludge might
 365        * be needed.
 366        */
 367 /*      regs[0].tag |= TW_FPU_Interrupt; */
 368     }
 369   RE_ENTRANT_CHECK_ON;
 370 
 371 #ifdef __DEBUG__
 372   math_abort(FPU_info,SIGFPE);
 373 #endif __DEBUG__
 374 
 375 }
 376 
 377 
 378 /* Real operation attempted on two operands, one a NaN. */
 379 /* Returns nz if the exception is unmasked */
 380 asmlinkage int real_2op_NaN(FPU_REG const *a, FPU_REG const *b, FPU_REG *dest)
     /*  */
 381 {
 382   FPU_REG const *x;
 383   int signalling;
 384 
 385   /* The default result for the case of two "equal" NaNs (signs may
 386      differ) is chosen to reproduce 80486 behaviour */
 387   x = a;
 388   if (a->tag == TW_NaN)
 389     {
 390       if (b->tag == TW_NaN)
 391         {
 392           signalling = !(a->sigh & b->sigh & 0x40000000);
 393           /* find the "larger" */
 394           if ( significand(a) < significand(b) )
 395             x = b;
 396         }
 397       else
 398         {
 399           /* return the quiet version of the NaN in a */
 400           signalling = !(a->sigh & 0x40000000);
 401         }
 402     }
 403   else
 404 #ifdef PARANOID
 405     if (b->tag == TW_NaN)
 406 #endif PARANOID
 407     {
 408       signalling = !(b->sigh & 0x40000000);
 409       x = b;
 410     }
 411 #ifdef PARANOID
 412   else
 413     {
 414       signalling = 0;
 415       EXCEPTION(EX_INTERNAL|0x113);
 416       x = &CONST_QNaN;
 417     }
 418 #endif PARANOID
 419 
 420   if ( !signalling )
 421     {
 422       if ( !(x->sigh & 0x80000000) )  /* pseudo-NaN ? */
 423         x = &CONST_QNaN;
 424       reg_move(x, dest);
 425       return 0;
 426     }
 427 
 428   if ( control_word & CW_Invalid )
 429     {
 430       /* The masked response */
 431       if ( !(x->sigh & 0x80000000) )  /* pseudo-NaN ? */
 432         x = &CONST_QNaN;
 433       reg_move(x, dest);
 434       /* ensure a Quiet NaN */
 435       dest->sigh |= 0x40000000;
 436     }
 437 
 438   EXCEPTION(EX_Invalid);
 439   
 440   return !(control_word & CW_Invalid);
 441 }
 442 
 443 
 444 /* Invalid arith operation on Valid registers */
 445 /* Returns nz if the exception is unmasked */
 446 asmlinkage int arith_invalid(FPU_REG *dest)
     /*  */
 447 {
 448 
 449   EXCEPTION(EX_Invalid);
 450   
 451   if ( control_word & CW_Invalid )
 452     {
 453       /* The masked response */
 454       reg_move(&CONST_QNaN, dest);
 455     }
 456   
 457   return !(control_word & CW_Invalid);
 458 
 459 }
 460 
 461 
 462 /* Divide a finite number by zero */
 463 asmlinkage int divide_by_zero(int sign, FPU_REG *dest)
     /*  */
 464 {
 465 
 466   if ( control_word & CW_ZeroDiv )
 467     {
 468       /* The masked response */
 469       reg_move(&CONST_INF, dest);
 470       dest->sign = (unsigned char)sign;
 471     }
 472  
 473   EXCEPTION(EX_ZeroDiv);
 474 
 475   return !(control_word & CW_ZeroDiv);
 476 
 477 }
 478 
 479 
 480 /* This may be called often, so keep it lean */
 481 int set_precision_flag(int flags)
     /*  */
 482 {
 483   if ( control_word & CW_Precision )
 484     {
 485       partial_status &= ~(SW_C1 & flags);
 486       partial_status |= flags;   /* The masked response */
 487       return 0;
 488     }
 489   else
 490     {
 491       exception(flags);
 492       return 1;
 493     }
 494 }
 495 
 496 
 497 /* This may be called often, so keep it lean */
 498 asmlinkage void set_precision_flag_up(void)
     /*  */
 499 {
 500   if ( control_word & CW_Precision )
 501     partial_status |= (SW_Precision | SW_C1);   /* The masked response */
 502   else
 503     exception(EX_Precision | SW_C1);
 504 
 505 }
 506 
 507 
 508 /* This may be called often, so keep it lean */
 509 asmlinkage void set_precision_flag_down(void)
     /*  */
 510 {
 511   if ( control_word & CW_Precision )
 512     {   /* The masked response */
 513       partial_status &= ~SW_C1;
 514       partial_status |= SW_Precision;
 515     }
 516   else
 517     exception(EX_Precision);
 518 }
 519 
 520 
 521 asmlinkage int denormal_operand(void)
     /*  */
 522 {
 523   if ( control_word & CW_Denormal )
 524     {   /* The masked response */
 525       partial_status |= SW_Denorm_Op;
 526       return 0;
 527     }
 528   else
 529     {
 530       exception(EX_Denormal);
 531       return 1;
 532     }
 533 }
 534 
 535 
 536 asmlinkage int arith_overflow(FPU_REG *dest)
     /*  */
 537 {
 538 
 539   if ( control_word & CW_Overflow )
 540     {
 541       char sign;
 542       /* The masked response */
 543 /* ###### The response here depends upon the rounding mode */
 544       sign = dest->sign;
 545       reg_move(&CONST_INF, dest);
 546       dest->sign = sign;
 547     }
 548   else
 549     {
 550       /* Subtract the magic number from the exponent */
 551       dest->exp -= (3 * (1 << 13));
 552     }
 553 
 554   EXCEPTION(EX_Overflow);
 555   if ( control_word & CW_Overflow )
 556     {
 557       /* The overflow exception is masked. */
 558       /* By definition, precision is lost.
 559          The roundup bit (C1) is also set because we have
 560          "rounded" upwards to Infinity. */
 561       EXCEPTION(EX_Precision | SW_C1);
 562       return !(control_word & CW_Precision);
 563     }
 564 
 565   return !(control_word & CW_Overflow);
 566 
 567 }
 568 
 569 
 570 asmlinkage int arith_underflow(FPU_REG *dest)
     /*  */
 571 {
 572 
 573   if ( control_word & CW_Underflow )
 574     {
 575       /* The masked response */
 576       if ( dest->exp <= EXP_UNDER - 63 )
 577         {
 578           reg_move(&CONST_Z, dest);
 579           partial_status &= ~SW_C1;       /* Round down. */
 580         }
 581     }
 582   else
 583     {
 584       /* Add the magic number to the exponent. */
 585       dest->exp += (3 * (1 << 13));
 586     }
 587 
 588   EXCEPTION(EX_Underflow);
 589   if ( control_word & CW_Underflow )
 590     {
 591       /* The underflow exception is masked. */
 592       EXCEPTION(EX_Precision);
 593       return !(control_word & CW_Precision);
 594     }
 595 
 596   return !(control_word & CW_Underflow);
 597 
 598 }
 599 
 600 
 601 void stack_overflow(void)
     /*  */
 602 {
 603 
 604  if ( control_word & CW_Invalid )
 605     {
 606       /* The masked response */
 607       top--;
 608       reg_move(&CONST_QNaN, &st(0));
 609     }
 610 
 611   EXCEPTION(EX_StackOver);
 612 
 613   return;
 614 
 615 }
 616 
 617 
 618 void stack_underflow(void)
     /*  */
 619 {
 620 
 621  if ( control_word & CW_Invalid )
 622     {
 623       /* The masked response */
 624       reg_move(&CONST_QNaN, &st(0));
 625     }
 626 
 627   EXCEPTION(EX_StackUnder);
 628 
 629   return;
 630 
 631 }
 632 
 633 
 634 void stack_underflow_i(int i)
     /*  */
 635 {
 636 
 637  if ( control_word & CW_Invalid )
 638     {
 639       /* The masked response */
 640       reg_move(&CONST_QNaN, &(st(i)));
 641     }
 642 
 643   EXCEPTION(EX_StackUnder);
 644 
 645   return;
 646 
 647 }
 648 
 649 
 650 void stack_underflow_pop(int i)
     /*  */
 651 {
 652 
 653  if ( control_word & CW_Invalid )
 654     {
 655       /* The masked response */
 656       reg_move(&CONST_QNaN, &(st(i)));
 657       pop();
 658     }
 659 
 660   EXCEPTION(EX_StackUnder);
 661 
 662   return;
 663 
 664 }
 665
/* */
root/drivers/FPU-emu/errors.c

DEFINITIONS
