linux/arch/ia64/kernel/unwind_decoder.c
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   1/*
   2 * Copyright (C) 2000 Hewlett-Packard Co
   3 * Copyright (C) 2000 David Mosberger-Tang <davidm@hpl.hp.com>
   4 *
   5 * Generic IA-64 unwind info decoder.
   6 *
   7 * This file is used both by the Linux kernel and objdump.  Please keep
   8 * the two copies of this file in sync.
   9 *
  10 * You need to customize the decoder by defining the following
  11 * macros/constants before including this file:
  12 *
  13 *  Types:
  14 *      unw_word        Unsigned integer type with at least 64 bits 
  15 *
  16 *  Register names:
  17 *      UNW_REG_BSP
  18 *      UNW_REG_BSPSTORE
  19 *      UNW_REG_FPSR
  20 *      UNW_REG_LC
  21 *      UNW_REG_PFS
  22 *      UNW_REG_PR
  23 *      UNW_REG_RNAT
  24 *      UNW_REG_PSP
  25 *      UNW_REG_RP
  26 *      UNW_REG_UNAT
  27 *
  28 *  Decoder action macros:
  29 *      UNW_DEC_BAD_CODE(code)
  30 *      UNW_DEC_ABI(fmt,abi,context,arg)
  31 *      UNW_DEC_BR_GR(fmt,brmask,gr,arg)
  32 *      UNW_DEC_BR_MEM(fmt,brmask,arg)
  33 *      UNW_DEC_COPY_STATE(fmt,label,arg)
  34 *      UNW_DEC_EPILOGUE(fmt,t,ecount,arg)
  35 *      UNW_DEC_FRGR_MEM(fmt,grmask,frmask,arg)
  36 *      UNW_DEC_FR_MEM(fmt,frmask,arg)
  37 *      UNW_DEC_GR_GR(fmt,grmask,gr,arg)
  38 *      UNW_DEC_GR_MEM(fmt,grmask,arg)
  39 *      UNW_DEC_LABEL_STATE(fmt,label,arg)
  40 *      UNW_DEC_MEM_STACK_F(fmt,t,size,arg)
  41 *      UNW_DEC_MEM_STACK_V(fmt,t,arg)
  42 *      UNW_DEC_PRIUNAT_GR(fmt,r,arg)
  43 *      UNW_DEC_PRIUNAT_WHEN_GR(fmt,t,arg)
  44 *      UNW_DEC_PRIUNAT_WHEN_MEM(fmt,t,arg)
  45 *      UNW_DEC_PRIUNAT_WHEN_PSPREL(fmt,pspoff,arg)
  46 *      UNW_DEC_PRIUNAT_WHEN_SPREL(fmt,spoff,arg)
  47 *      UNW_DEC_PROLOGUE(fmt,body,rlen,arg)
  48 *      UNW_DEC_PROLOGUE_GR(fmt,rlen,mask,grsave,arg)
  49 *      UNW_DEC_REG_PSPREL(fmt,reg,pspoff,arg)
  50 *      UNW_DEC_REG_REG(fmt,src,dst,arg)
  51 *      UNW_DEC_REG_SPREL(fmt,reg,spoff,arg)
  52 *      UNW_DEC_REG_WHEN(fmt,reg,t,arg)
  53 *      UNW_DEC_RESTORE(fmt,t,abreg,arg)
  54 *      UNW_DEC_RESTORE_P(fmt,qp,t,abreg,arg)
  55 *      UNW_DEC_SPILL_BASE(fmt,pspoff,arg)
  56 *      UNW_DEC_SPILL_MASK(fmt,imaskp,arg)
  57 *      UNW_DEC_SPILL_PSPREL(fmt,t,abreg,pspoff,arg)
  58 *      UNW_DEC_SPILL_PSPREL_P(fmt,qp,t,abreg,pspoff,arg)
  59 *      UNW_DEC_SPILL_REG(fmt,t,abreg,x,ytreg,arg)
  60 *      UNW_DEC_SPILL_REG_P(fmt,qp,t,abreg,x,ytreg,arg)
  61 *      UNW_DEC_SPILL_SPREL(fmt,t,abreg,spoff,arg)
  62 *      UNW_DEC_SPILL_SPREL_P(fmt,qp,t,abreg,pspoff,arg)
  63 */
  64
  65static unw_word
  66unw_decode_uleb128 (unsigned char **dpp)
  67{
  68  unsigned shift = 0;
  69  unw_word byte, result = 0;
  70  unsigned char *bp = *dpp;
  71
  72  while (1)
  73    {
  74      byte = *bp++;
  75      result |= (byte & 0x7f) << shift;
  76      if ((byte & 0x80) == 0)
  77        break;
  78      shift += 7;
  79    }
  80  *dpp = bp;
  81  return result;
  82}
  83
  84static unsigned char *
  85unw_decode_x1 (unsigned char *dp, unsigned char code, void *arg)
  86{
  87  unsigned char byte1, abreg;
  88  unw_word t, off;
  89
  90  byte1 = *dp++;
  91  t = unw_decode_uleb128 (&dp);
  92  off = unw_decode_uleb128 (&dp);
  93  abreg = (byte1 & 0x7f);
  94  if (byte1 & 0x80)
  95          UNW_DEC_SPILL_SPREL(X1, t, abreg, off, arg);
  96  else
  97          UNW_DEC_SPILL_PSPREL(X1, t, abreg, off, arg);
  98  return dp;
  99}
 100
 101static unsigned char *
 102unw_decode_x2 (unsigned char *dp, unsigned char code, void *arg)
 103{
 104  unsigned char byte1, byte2, abreg, x, ytreg;
 105  unw_word t;
 106
 107  byte1 = *dp++; byte2 = *dp++;
 108  t = unw_decode_uleb128 (&dp);
 109  abreg = (byte1 & 0x7f);
 110  ytreg = byte2;
 111  x = (byte1 >> 7) & 1;
 112  if ((byte1 & 0x80) == 0 && ytreg == 0)
 113    UNW_DEC_RESTORE(X2, t, abreg, arg);
 114  else
 115    UNW_DEC_SPILL_REG(X2, t, abreg, x, ytreg, arg);
 116  return dp;
 117}
 118
 119static unsigned char *
 120unw_decode_x3 (unsigned char *dp, unsigned char code, void *arg)
 121{
 122  unsigned char byte1, byte2, abreg, qp;
 123  unw_word t, off;
 124
 125  byte1 = *dp++; byte2 = *dp++;
 126  t = unw_decode_uleb128 (&dp);
 127  off = unw_decode_uleb128 (&dp);
 128
 129  qp = (byte1 & 0x3f);
 130  abreg = (byte2 & 0x7f);
 131
 132  if (byte1 & 0x80)
 133    UNW_DEC_SPILL_SPREL_P(X3, qp, t, abreg, off, arg);
 134  else
 135    UNW_DEC_SPILL_PSPREL_P(X3, qp, t, abreg, off, arg);
 136  return dp;
 137}
 138
 139static unsigned char *
 140unw_decode_x4 (unsigned char *dp, unsigned char code, void *arg)
 141{
 142  unsigned char byte1, byte2, byte3, qp, abreg, x, ytreg;
 143  unw_word t;
 144
 145  byte1 = *dp++; byte2 = *dp++; byte3 = *dp++;
 146  t = unw_decode_uleb128 (&dp);
 147
 148  qp = (byte1 & 0x3f);
 149  abreg = (byte2 & 0x7f);
 150  x = (byte2 >> 7) & 1;
 151  ytreg = byte3;
 152
 153  if ((byte2 & 0x80) == 0 && byte3 == 0)
 154    UNW_DEC_RESTORE_P(X4, qp, t, abreg, arg);
 155  else
 156    UNW_DEC_SPILL_REG_P(X4, qp, t, abreg, x, ytreg, arg);
 157  return dp;
 158}
 159
 160static unsigned char *
 161unw_decode_r1 (unsigned char *dp, unsigned char code, void *arg)
 162{
 163  int body = (code & 0x20) != 0;
 164  unw_word rlen;
 165
 166  rlen = (code & 0x1f);
 167  UNW_DEC_PROLOGUE(R1, body, rlen, arg);
 168  return dp;
 169}
 170
 171static unsigned char *
 172unw_decode_r2 (unsigned char *dp, unsigned char code, void *arg)
 173{
 174  unsigned char byte1, mask, grsave;
 175  unw_word rlen;
 176
 177  byte1 = *dp++;
 178
 179  mask = ((code & 0x7) << 1) | ((byte1 >> 7) & 1);
 180  grsave = (byte1 & 0x7f);
 181  rlen = unw_decode_uleb128 (&dp);
 182  UNW_DEC_PROLOGUE_GR(R2, rlen, mask, grsave, arg);
 183  return dp;
 184}
 185
 186static unsigned char *
 187unw_decode_r3 (unsigned char *dp, unsigned char code, void *arg)
 188{
 189  unw_word rlen;
 190
 191  rlen = unw_decode_uleb128 (&dp);
 192  UNW_DEC_PROLOGUE(R3, ((code & 0x3) == 1), rlen, arg);
 193  return dp;
 194}
 195
 196static unsigned char *
 197unw_decode_p1 (unsigned char *dp, unsigned char code, void *arg)
 198{
 199  unsigned char brmask = (code & 0x1f);
 200
 201  UNW_DEC_BR_MEM(P1, brmask, arg);
 202  return dp;
 203}
 204
 205static unsigned char *
 206unw_decode_p2_p5 (unsigned char *dp, unsigned char code, void *arg)
 207{
 208  if ((code & 0x10) == 0)
 209    {
 210      unsigned char byte1 = *dp++;
 211
 212      UNW_DEC_BR_GR(P2, ((code & 0xf) << 1) | ((byte1 >> 7) & 1),
 213                    (byte1 & 0x7f), arg);
 214    }
 215  else if ((code & 0x08) == 0)
 216    {
 217      unsigned char byte1 = *dp++, r, dst;
 218
 219      r = ((code & 0x7) << 1) | ((byte1 >> 7) & 1);
 220      dst = (byte1 & 0x7f);
 221      switch (r)
 222        {
 223        case 0: UNW_DEC_REG_GR(P3, UNW_REG_PSP, dst, arg); break;
 224        case 1: UNW_DEC_REG_GR(P3, UNW_REG_RP, dst, arg); break;
 225        case 2: UNW_DEC_REG_GR(P3, UNW_REG_PFS, dst, arg); break;
 226        case 3: UNW_DEC_REG_GR(P3, UNW_REG_PR, dst, arg); break;
 227        case 4: UNW_DEC_REG_GR(P3, UNW_REG_UNAT, dst, arg); break;
 228        case 5: UNW_DEC_REG_GR(P3, UNW_REG_LC, dst, arg); break;
 229        case 6: UNW_DEC_RP_BR(P3, dst, arg); break;
 230        case 7: UNW_DEC_REG_GR(P3, UNW_REG_RNAT, dst, arg); break;
 231        case 8: UNW_DEC_REG_GR(P3, UNW_REG_BSP, dst, arg); break;
 232        case 9: UNW_DEC_REG_GR(P3, UNW_REG_BSPSTORE, dst, arg); break;
 233        case 10: UNW_DEC_REG_GR(P3, UNW_REG_FPSR, dst, arg); break;
 234        case 11: UNW_DEC_PRIUNAT_GR(P3, dst, arg); break;
 235        default: UNW_DEC_BAD_CODE(r); break;
 236        }
 237    }
 238  else if ((code & 0x7) == 0)
 239    UNW_DEC_SPILL_MASK(P4, dp, arg);
 240  else if ((code & 0x7) == 1)
 241    {
 242      unw_word grmask, frmask, byte1, byte2, byte3;
 243
 244      byte1 = *dp++; byte2 = *dp++; byte3 = *dp++;
 245      grmask = ((byte1 >> 4) & 0xf);
 246      frmask = ((byte1 & 0xf) << 16) | (byte2 << 8) | byte3;
 247      UNW_DEC_FRGR_MEM(P5, grmask, frmask, arg);
 248    }
 249  else
 250    UNW_DEC_BAD_CODE(code);
 251  return dp;
 252}
 253
 254static unsigned char *
 255unw_decode_p6 (unsigned char *dp, unsigned char code, void *arg)
 256{
 257  int gregs = (code & 0x10) != 0;
 258  unsigned char mask = (code & 0x0f);
 259
 260  if (gregs)
 261    UNW_DEC_GR_MEM(P6, mask, arg);
 262  else
 263    UNW_DEC_FR_MEM(P6, mask, arg);
 264  return dp;
 265}
 266
 267static unsigned char *
 268unw_decode_p7_p10 (unsigned char *dp, unsigned char code, void *arg)
 269{
 270  unsigned char r, byte1, byte2;
 271  unw_word t, size;
 272
 273  if ((code & 0x10) == 0)
 274    {
 275      r = (code & 0xf);
 276      t = unw_decode_uleb128 (&dp);
 277      switch (r)
 278        {
 279        case 0:
 280          size = unw_decode_uleb128 (&dp);
 281          UNW_DEC_MEM_STACK_F(P7, t, size, arg);
 282          break;
 283
 284        case 1: UNW_DEC_MEM_STACK_V(P7, t, arg); break;
 285        case 2: UNW_DEC_SPILL_BASE(P7, t, arg); break;
 286        case 3: UNW_DEC_REG_SPREL(P7, UNW_REG_PSP, t, arg); break;
 287        case 4: UNW_DEC_REG_WHEN(P7, UNW_REG_RP, t, arg); break;
 288        case 5: UNW_DEC_REG_PSPREL(P7, UNW_REG_RP, t, arg); break;
 289        case 6: UNW_DEC_REG_WHEN(P7, UNW_REG_PFS, t, arg); break;
 290        case 7: UNW_DEC_REG_PSPREL(P7, UNW_REG_PFS, t, arg); break;
 291        case 8: UNW_DEC_REG_WHEN(P7, UNW_REG_PR, t, arg); break;
 292        case 9: UNW_DEC_REG_PSPREL(P7, UNW_REG_PR, t, arg); break;
 293        case 10: UNW_DEC_REG_WHEN(P7, UNW_REG_LC, t, arg); break;
 294        case 11: UNW_DEC_REG_PSPREL(P7, UNW_REG_LC, t, arg); break;
 295        case 12: UNW_DEC_REG_WHEN(P7, UNW_REG_UNAT, t, arg); break;
 296        case 13: UNW_DEC_REG_PSPREL(P7, UNW_REG_UNAT, t, arg); break;
 297        case 14: UNW_DEC_REG_WHEN(P7, UNW_REG_FPSR, t, arg); break;
 298        case 15: UNW_DEC_REG_PSPREL(P7, UNW_REG_FPSR, t, arg); break;
 299        default: UNW_DEC_BAD_CODE(r); break;
 300        }
 301    }
 302  else
 303    {
 304      switch (code & 0xf)
 305        {
 306        case 0x0: /* p8 */
 307          {
 308            r = *dp++;
 309            t = unw_decode_uleb128 (&dp);
 310            switch (r)
 311              {
 312              case  1: UNW_DEC_REG_SPREL(P8, UNW_REG_RP, t, arg); break;
 313              case  2: UNW_DEC_REG_SPREL(P8, UNW_REG_PFS, t, arg); break;
 314              case  3: UNW_DEC_REG_SPREL(P8, UNW_REG_PR, t, arg); break;
 315              case  4: UNW_DEC_REG_SPREL(P8, UNW_REG_LC, t, arg); break;
 316              case  5: UNW_DEC_REG_SPREL(P8, UNW_REG_UNAT, t, arg); break;
 317              case  6: UNW_DEC_REG_SPREL(P8, UNW_REG_FPSR, t, arg); break;
 318              case  7: UNW_DEC_REG_WHEN(P8, UNW_REG_BSP, t, arg); break;
 319              case  8: UNW_DEC_REG_PSPREL(P8, UNW_REG_BSP, t, arg); break;
 320              case  9: UNW_DEC_REG_SPREL(P8, UNW_REG_BSP, t, arg); break;
 321              case 10: UNW_DEC_REG_WHEN(P8, UNW_REG_BSPSTORE, t, arg); break;
 322              case 11: UNW_DEC_REG_PSPREL(P8, UNW_REG_BSPSTORE, t, arg); break;
 323              case 12: UNW_DEC_REG_SPREL(P8, UNW_REG_BSPSTORE, t, arg); break;
 324              case 13: UNW_DEC_REG_WHEN(P8, UNW_REG_RNAT, t, arg); break;
 325              case 14: UNW_DEC_REG_PSPREL(P8, UNW_REG_RNAT, t, arg); break;
 326              case 15: UNW_DEC_REG_SPREL(P8, UNW_REG_RNAT, t, arg); break;
 327              case 16: UNW_DEC_PRIUNAT_WHEN_GR(P8, t, arg); break;
 328              case 17: UNW_DEC_PRIUNAT_PSPREL(P8, t, arg); break;
 329              case 18: UNW_DEC_PRIUNAT_SPREL(P8, t, arg); break;
 330              case 19: UNW_DEC_PRIUNAT_WHEN_MEM(P8, t, arg); break;
 331              default: UNW_DEC_BAD_CODE(r); break;
 332            }
 333          }
 334          break;
 335
 336        case 0x1:
 337          byte1 = *dp++; byte2 = *dp++;
 338          UNW_DEC_GR_GR(P9, (byte1 & 0xf), (byte2 & 0x7f), arg);
 339          break;
 340
 341        case 0xf: /* p10 */
 342          byte1 = *dp++; byte2 = *dp++;
 343          UNW_DEC_ABI(P10, byte1, byte2, arg);
 344          break;
 345
 346        case 0x9:
 347          return unw_decode_x1 (dp, code, arg);
 348
 349        case 0xa:
 350          return unw_decode_x2 (dp, code, arg);
 351
 352        case 0xb:
 353          return unw_decode_x3 (dp, code, arg);
 354
 355        case 0xc:
 356          return unw_decode_x4 (dp, code, arg);
 357
 358        default:
 359          UNW_DEC_BAD_CODE(code);
 360          break;
 361        }
 362    }
 363  return dp;
 364}
 365
 366static unsigned char *
 367unw_decode_b1 (unsigned char *dp, unsigned char code, void *arg)
 368{
 369  unw_word label = (code & 0x1f);
 370
 371  if ((code & 0x20) != 0)
 372    UNW_DEC_COPY_STATE(B1, label, arg);
 373  else
 374    UNW_DEC_LABEL_STATE(B1, label, arg);
 375  return dp;
 376}
 377
 378static unsigned char *
 379unw_decode_b2 (unsigned char *dp, unsigned char code, void *arg)
 380{
 381  unw_word t;
 382
 383  t = unw_decode_uleb128 (&dp);
 384  UNW_DEC_EPILOGUE(B2, t, (code & 0x1f), arg);
 385  return dp;
 386}
 387
 388static unsigned char *
 389unw_decode_b3_x4 (unsigned char *dp, unsigned char code, void *arg)
 390{
 391  unw_word t, ecount, label;
 392
 393  if ((code & 0x10) == 0)
 394    {
 395      t = unw_decode_uleb128 (&dp);
 396      ecount = unw_decode_uleb128 (&dp);
 397      UNW_DEC_EPILOGUE(B3, t, ecount, arg);
 398    }
 399  else if ((code & 0x07) == 0)
 400    {
 401      label = unw_decode_uleb128 (&dp);
 402      if ((code & 0x08) != 0)
 403        UNW_DEC_COPY_STATE(B4, label, arg);
 404      else
 405        UNW_DEC_LABEL_STATE(B4, label, arg);
 406    }
 407  else
 408    switch (code & 0x7)
 409      {
 410      case 1: return unw_decode_x1 (dp, code, arg);
 411      case 2: return unw_decode_x2 (dp, code, arg);
 412      case 3: return unw_decode_x3 (dp, code, arg);
 413      case 4: return unw_decode_x4 (dp, code, arg);
 414      default: UNW_DEC_BAD_CODE(code); break;
 415      }
 416  return dp;
 417}
 418
 419typedef unsigned char *(*unw_decoder) (unsigned char *, unsigned char, void *);
 420
 421static unw_decoder unw_decode_table[2][8] =
 422{
 423  /* prologue table: */
 424  {
 425    unw_decode_r1,      /* 0 */
 426    unw_decode_r1,
 427    unw_decode_r2,
 428    unw_decode_r3,
 429    unw_decode_p1,      /* 4 */
 430    unw_decode_p2_p5,
 431    unw_decode_p6,
 432    unw_decode_p7_p10
 433  },
 434  {
 435    unw_decode_r1,      /* 0 */
 436    unw_decode_r1,
 437    unw_decode_r2,
 438    unw_decode_r3,
 439    unw_decode_b1,      /* 4 */
 440    unw_decode_b1,
 441    unw_decode_b2,
 442    unw_decode_b3_x4
 443  }
 444};
 445
 446/*
 447 * Decode one descriptor and return address of next descriptor.
 448 */
 449static inline unsigned char *
 450unw_decode (unsigned char *dp, int inside_body, void *arg)
 451{
 452  unw_decoder decoder;
 453  unsigned char code;
 454
 455  code = *dp++;
 456  decoder = unw_decode_table[inside_body][code >> 5];
 457  dp = (*decoder) (dp, code, arg);
 458  return dp;
 459}
 460