arch/i386/math-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               0x104  in poly_atan.c
 239               0x105  in reg_mul.c
 240               0x107  in fpu_trig.c
 241               0x108  in reg_compare.c
 242               0x109  in reg_compare.c
 243               0x110  in reg_add_sub.c
 244               0x111  in fpe_entry.c
 245               0x112  in fpu_trig.c
 246               0x113  in errors.c
 247               0x115  in fpu_trig.c
 248               0x116  in fpu_trig.c
 249               0x117  in fpu_trig.c
 250               0x118  in fpu_trig.c
 251               0x119  in fpu_trig.c
 252               0x120  in poly_atan.c
 253               0x121  in reg_compare.c
 254               0x122  in reg_compare.c
 255               0x123  in reg_compare.c
 256               0x125  in fpu_trig.c
 257               0x126  in fpu_entry.c
 258               0x127  in poly_2xm1.c
 259               0x128  in fpu_entry.c
 260               0x129  in fpu_entry.c
 261               0x130  in get_address.c
 262               0x131  in get_address.c
 263               0x132  in get_address.c
 264               0x133  in get_address.c
 265               0x140  in load_store.c
 266               0x141  in load_store.c
 267               0x150  in poly_sin.c
 268               0x151  in poly_sin.c
 269               0x160  in reg_ld_str.c
 270               0x161  in reg_ld_str.c
 271               0x162  in reg_ld_str.c
 272               0x163  in reg_ld_str.c
 273        0x2nn  in an *.S file:
 274               0x201  in reg_u_add.S
 275               0x202  in reg_u_div.S
 276               0x203  in reg_u_div.S
 277               0x204  in reg_u_div.S
 278               0x205  in reg_u_mul.S
 279               0x206  in reg_u_sub.S
 280               0x207  in wm_sqrt.S
 281               0x208  in reg_div.S
 282               0x209  in reg_u_sub.S
 283               0x210  in reg_u_sub.S
 284               0x211  in reg_u_sub.S
 285               0x212  in reg_u_sub.S
 286               0x213  in wm_sqrt.S
 287               0x214  in wm_sqrt.S
 288               0x215  in wm_sqrt.S
 289               0x220  in reg_norm.S
 290               0x221  in reg_norm.S
 291               0x230  in reg_round.S
 292               0x231  in reg_round.S
 293               0x232  in reg_round.S
 294               0x233  in reg_round.S
 295               0x234  in reg_round.S
 296               0x235  in reg_round.S
 297               0x236  in reg_round.S
 298               0x240  in div_Xsig.S
 299               0x241  in div_Xsig.S
 300               0x242  in div_Xsig.S
 301  */
 302 
 303 void exception(int n)
     /*  */
 304 {
 305   int i, int_type;
 306 
 307   int_type = 0;         /* Needed only to stop compiler warnings */
 308   if ( n & EX_INTERNAL )
 309     {
 310       int_type = n - EX_INTERNAL;
 311       n = EX_INTERNAL;
 312       /* Set lots of exception bits! */
 313       partial_status |= (SW_Exc_Mask | SW_Summary | SW_Backward);
 314     }
 315   else
 316     {
 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         {
 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     {
 336 #ifdef PRINT_MESSAGES
 337       /* My message from the sponsor */
 338       printk(FPU_VERSION" "__DATE__" (C) W. Metzenthen.\n");
 339 #endif PRINT_MESSAGES
 340       
 341       /* Get a name string for error reporting */
 342       for (i=0; exception_names[i].type; i++)
 343         if ( (exception_names[i].type & n) == exception_names[i].type )
 344           break;
 345       
 346       if (exception_names[i].type)
 347         {
 348 #ifdef PRINT_MESSAGES
 349           printk("FP Exception: %s!\n", exception_names[i].name);
 350 #endif PRINT_MESSAGES
 351         }
 352       else
 353         printk("FPU emulator: Unknown Exception: 0x%04x!\n", n);
 354       
 355       if ( n == EX_INTERNAL )
 356         {
 357           printk("FPU emulator: Internal error type 0x%04x\n", int_type);
 358           emu_printall();
 359         }
 360 #ifdef PRINT_MESSAGES
 361       else
 362         emu_printall();
 363 #endif PRINT_MESSAGES
 364 
 365       /*
 366        * The 80486 generates an interrupt on the next non-control FPU
 367        * instruction. So we need some means of flagging it.
 368        * We use the ES (Error Summary) bit for this, assuming that
 369        * this is the way a real FPU does it (until I can check it out),
 370        * if not, then some method such as the following kludge might
 371        * be needed.
 372        */
 373 /*      regs[0].tag |= TW_FPU_Interrupt; */
 374     }
 375   RE_ENTRANT_CHECK_ON;
 376 
 377 #ifdef __DEBUG__
 378   math_abort(FPU_info,SIGFPE);
 379 #endif __DEBUG__
 380 
 381 }
 382 
 383 
 384 /* Real operation attempted on two operands, one a NaN. */
 385 /* Returns nz if the exception is unmasked */
 386 asmlinkage int real_2op_NaN(FPU_REG const *a, FPU_REG const *b, FPU_REG *dest)
     /*  */
 387 {
 388   FPU_REG const *x;
 389   int signalling;
 390 
 391   /* The default result for the case of two "equal" NaNs (signs may
 392      differ) is chosen to reproduce 80486 behaviour */
 393   x = a;
 394   if (a->tag == TW_NaN)
 395     {
 396       if (b->tag == TW_NaN)
 397         {
 398           signalling = !(a->sigh & b->sigh & 0x40000000);
 399           /* find the "larger" */
 400           if ( significand(a) < significand(b) )
 401             x = b;
 402         }
 403       else
 404         {
 405           /* return the quiet version of the NaN in a */
 406           signalling = !(a->sigh & 0x40000000);
 407         }
 408     }
 409   else
 410 #ifdef PARANOID
 411     if (b->tag == TW_NaN)
 412 #endif PARANOID
 413     {
 414       signalling = !(b->sigh & 0x40000000);
 415       x = b;
 416     }
 417 #ifdef PARANOID
 418   else
 419     {
 420       signalling = 0;
 421       EXCEPTION(EX_INTERNAL|0x113);
 422       x = &CONST_QNaN;
 423     }
 424 #endif PARANOID
 425 
 426   if ( !signalling )
 427     {
 428       if ( !(x->sigh & 0x80000000) )  /* pseudo-NaN ? */
 429         x = &CONST_QNaN;
 430       reg_move(x, dest);
 431       return 0;
 432     }
 433 
 434   if ( control_word & CW_Invalid )
 435     {
 436       /* The masked response */
 437       if ( !(x->sigh & 0x80000000) )  /* pseudo-NaN ? */
 438         x = &CONST_QNaN;
 439       reg_move(x, dest);
 440       /* ensure a Quiet NaN */
 441       dest->sigh |= 0x40000000;
 442     }
 443 
 444   EXCEPTION(EX_Invalid);
 445   
 446   return !(control_word & CW_Invalid);
 447 }
 448 
 449 
 450 /* Invalid arith operation on Valid registers */
 451 /* Returns nz if the exception is unmasked */
 452 asmlinkage int arith_invalid(FPU_REG *dest)
     /*  */
 453 {
 454 
 455   EXCEPTION(EX_Invalid);
 456   
 457   if ( control_word & CW_Invalid )
 458     {
 459       /* The masked response */
 460       reg_move(&CONST_QNaN, dest);
 461     }
 462   
 463   return !(control_word & CW_Invalid);
 464 
 465 }
 466 
 467 
 468 /* Divide a finite number by zero */
 469 asmlinkage int divide_by_zero(int sign, FPU_REG *dest)
     /*  */
 470 {
 471 
 472   if ( control_word & CW_ZeroDiv )
 473     {
 474       /* The masked response */
 475       reg_move(&CONST_INF, dest);
 476       dest->sign = (unsigned char)sign;
 477     }
 478  
 479   EXCEPTION(EX_ZeroDiv);
 480 
 481   return !(control_word & CW_ZeroDiv);
 482 
 483 }
 484 
 485 
 486 /* This may be called often, so keep it lean */
 487 int set_precision_flag(int flags)
     /*  */
 488 {
 489   if ( control_word & CW_Precision )
 490     {
 491       partial_status &= ~(SW_C1 & flags);
 492       partial_status |= flags;   /* The masked response */
 493       return 0;
 494     }
 495   else
 496     {
 497       exception(flags);
 498       return 1;
 499     }
 500 }
 501 
 502 
 503 /* This may be called often, so keep it lean */
 504 asmlinkage void set_precision_flag_up(void)
     /*  */
 505 {
 506   if ( control_word & CW_Precision )
 507     partial_status |= (SW_Precision | SW_C1);   /* The masked response */
 508   else
 509     exception(EX_Precision | SW_C1);
 510 
 511 }
 512 
 513 
 514 /* This may be called often, so keep it lean */
 515 asmlinkage void set_precision_flag_down(void)
     /*  */
 516 {
 517   if ( control_word & CW_Precision )
 518     {   /* The masked response */
 519       partial_status &= ~SW_C1;
 520       partial_status |= SW_Precision;
 521     }
 522   else
 523     exception(EX_Precision);
 524 }
 525 
 526 
 527 asmlinkage int denormal_operand(void)
     /*  */
 528 {
 529   if ( control_word & CW_Denormal )
 530     {   /* The masked response */
 531       partial_status |= SW_Denorm_Op;
 532       return 0;
 533     }
 534   else
 535     {
 536       exception(EX_Denormal);
 537       return 1;
 538     }
 539 }
 540 
 541 
 542 asmlinkage int arith_overflow(FPU_REG *dest)
     /*  */
 543 {
 544 
 545   if ( control_word & CW_Overflow )
 546     {
 547       char sign;
 548       /* The masked response */
 549 /* ###### The response here depends upon the rounding mode */
 550       sign = dest->sign;
 551       reg_move(&CONST_INF, dest);
 552       dest->sign = sign;
 553     }
 554   else
 555     {
 556       /* Subtract the magic number from the exponent */
 557       dest->exp -= (3 * (1 << 13));
 558     }
 559 
 560   EXCEPTION(EX_Overflow);
 561   if ( control_word & CW_Overflow )
 562     {
 563       /* The overflow exception is masked. */
 564       /* By definition, precision is lost.
 565          The roundup bit (C1) is also set because we have
 566          "rounded" upwards to Infinity. */
 567       EXCEPTION(EX_Precision | SW_C1);
 568       return !(control_word & CW_Precision);
 569     }
 570 
 571   return !(control_word & CW_Overflow);
 572 
 573 }
 574 
 575 
 576 asmlinkage int arith_underflow(FPU_REG *dest)
     /*  */
 577 {
 578 
 579   if ( control_word & CW_Underflow )
 580     {
 581       /* The masked response */
 582       if ( dest->exp <= EXP_UNDER - 63 )
 583         {
 584           reg_move(&CONST_Z, dest);
 585           partial_status &= ~SW_C1;       /* Round down. */
 586         }
 587     }
 588   else
 589     {
 590       /* Add the magic number to the exponent. */
 591       dest->exp += (3 * (1 << 13));
 592     }
 593 
 594   EXCEPTION(EX_Underflow);
 595   if ( control_word & CW_Underflow )
 596     {
 597       /* The underflow exception is masked. */
 598       EXCEPTION(EX_Precision);
 599       return !(control_word & CW_Precision);
 600     }
 601 
 602   return !(control_word & CW_Underflow);
 603 
 604 }
 605 
 606 
 607 void stack_overflow(void)
     /*  */
 608 {
 609 
 610  if ( control_word & CW_Invalid )
 611     {
 612       /* The masked response */
 613       top--;
 614       reg_move(&CONST_QNaN, &st(0));
 615     }
 616 
 617   EXCEPTION(EX_StackOver);
 618 
 619   return;
 620 
 621 }
 622 
 623 
 624 void stack_underflow(void)
     /*  */
 625 {
 626 
 627  if ( control_word & CW_Invalid )
 628     {
 629       /* The masked response */
 630       reg_move(&CONST_QNaN, &st(0));
 631     }
 632 
 633   EXCEPTION(EX_StackUnder);
 634 
 635   return;
 636 
 637 }
 638 
 639 
 640 void stack_underflow_i(int i)
     /*  */
 641 {
 642 
 643  if ( control_word & CW_Invalid )
 644     {
 645       /* The masked response */
 646       reg_move(&CONST_QNaN, &(st(i)));
 647     }
 648 
 649   EXCEPTION(EX_StackUnder);
 650 
 651   return;
 652 
 653 }
 654 
 655 
 656 void stack_underflow_pop(int i)
     /*  */
 657 {
 658 
 659  if ( control_word & CW_Invalid )
 660     {
 661       /* The masked response */
 662       reg_move(&CONST_QNaN, &(st(i)));
 663       pop();
 664     }
 665 
 666   EXCEPTION(EX_StackUnder);
 667 
 668   return;
 669 
 670 }
 671
/* */
root/arch/i386/math-emu/errors.c

DEFINITIONS
