opcodes/vax-dis.c

   1 /* Print VAX instructions.
   2    Copyright 1995, 1998, 2000, 2001, 2002, 2005, 2007
   3    Free Software Foundation, Inc.
   4    Contributed by Pauline Middelink <middelin@polyware.iaf.nl>
   5
   6    This file is part of the GNU opcodes library.
   7
   8    This library is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3, or (at your option)
  11    any later version.
  12
  13    It is distributed in the hope that it will be useful, but WITHOUT
  14    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  16    License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21    MA 02110-1301, USA.  */
  22
  23 #include <setjmp.h>
  24 #include <string.h>
  25 #include "sysdep.h"
  26 #include "opcode/vax.h"
  27 #include "dis-asm.h"
  28
  29 static char *reg_names[] =
  30 {
  31   "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
  32   "r8", "r9", "r10", "r11", "ap", "fp", "sp", "pc"
  33 };
  34
  35 /* Definitions for the function entry mask bits.  */
  36 static char *entry_mask_bit[] =
  37 {
  38   /* Registers 0 and 1 shall not be saved, since they're used to pass back
  39      a function's result to its caller...  */
  40   "~r0~", "~r1~",
  41   /* Registers 2 .. 11 are normal registers.  */
  42   "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11",
  43   /* Registers 12 and 13 are argument and frame pointer and must not
  44      be saved by using the entry mask.  */
  45   "~ap~", "~fp~",
  46   /* Bits 14 and 15 control integer and decimal overflow.  */
  47   "IntOvfl", "DecOvfl",
  48 };
  49
  50 /* Sign-extend an (unsigned char). */
  51 #define COERCE_SIGNED_CHAR(ch) ((signed char)(ch))
  52
  53 /* Get a 1 byte signed integer.  */
  54 #define NEXTBYTE(p)  \
  55   (p += 1, FETCH_DATA (info, p), \
  56   COERCE_SIGNED_CHAR(p[-1]))
  57
  58 /* Get a 2 byte signed integer.  */
  59 #define COERCE16(x) ((int) (((x) ^ 0x8000) - 0x8000))
  60 #define NEXTWORD(p)  \
  61   (p += 2, FETCH_DATA (info, p), \
  62    COERCE16 ((p[-1] << 8) + p[-2]))
  63
  64 /* Get a 4 byte signed integer.  */
  65 #define COERCE32(x) ((int) (((x) ^ 0x80000000) - 0x80000000))
  66 #define NEXTLONG(p)  \
  67   (p += 4, FETCH_DATA (info, p), \
  68    (COERCE32 ((((((p[-1] << 8) + p[-2]) << 8) + p[-3]) << 8) + p[-4])))
  69
  70 /* Maximum length of an instruction.  */
  71 #define MAXLEN 25
  72
  73 struct private
  74 {
  75   /* Points to first byte not fetched.  */
  76   bfd_byte * max_fetched;
  77   bfd_byte   the_buffer[MAXLEN];
  78   bfd_vma    insn_start;
  79   jmp_buf    bailout;
  80 };
  81
  82 /* Make sure that bytes from INFO->PRIVATE_DATA->BUFFER (inclusive)
  83    to ADDR (exclusive) are valid.  Returns 1 for success, longjmps
  84    on error.  */
  85 #define FETCH_DATA(info, addr) \
  86   ((addr) <= ((struct private *)(info->private_data))->max_fetched \
  87    ? 1 : fetch_data ((info), (addr)))
  88
  89 static int
  90 fetch_data (struct disassemble_info *info, bfd_byte *addr)
  91 {
  92   int status;
  93   struct private *priv = (struct private *) info->private_data;
  94   bfd_vma start = priv->insn_start + (priv->max_fetched - priv->the_buffer);
  95
  96   status = (*info->read_memory_func) (start,
  97                                       priv->max_fetched,
  98                                       addr - priv->max_fetched,
  99                                       info);
 100   if (status != 0)
 101     {
 102       (*info->memory_error_func) (status, start, info);
 103       longjmp (priv->bailout, 1);
 104     }
 105   else
 106     priv->max_fetched = addr;
 107
 108   return 1;
 109 }
 110
 111 /* Entry mask handling.  */
 112 static unsigned int  entry_addr_occupied_slots = 0;
 113 static unsigned int  entry_addr_total_slots = 0;
 114 static bfd_vma *     entry_addr = NULL;
 115
 116 /* Parse the VAX specific disassembler options.  These contain function
 117    entry addresses, which can be useful to disassemble ROM images, since
 118    there's no symbol table.  Returns TRUE upon success, FALSE otherwise.  */
 119
 120 static bfd_boolean
 121 parse_disassembler_options (char * options)
 122 {
 123   const char * entry_switch = "entry:";
 124
 125   while ((options = strstr (options, entry_switch)))
 126     {
 127       options += strlen (entry_switch);
 128
 129       /* The greater-than part of the test below is paranoia.  */
 130       if (entry_addr_occupied_slots >= entry_addr_total_slots)
 131         {
 132           /* A guesstimate of the number of entries we will have to create.  */
 133           entry_addr_total_slots +=
 134             strlen (options) / (strlen (entry_switch) + 5);
 135
 136           entry_addr = realloc (entry_addr, sizeof (bfd_vma)
 137                                 * entry_addr_total_slots);
 138         }
 139
 140       if (entry_addr == NULL)
 141         return FALSE;
 142
 143       entry_addr[entry_addr_occupied_slots] = bfd_scan_vma (options, NULL, 0);
 144       entry_addr_occupied_slots ++;
 145     }
 146
 147   return TRUE;
 148 }
 149
 150 #if 0 /* FIXME:  Ideally the disassembler should have target specific
 151          initialisation and termination function pointers.  Then
 152          parse_disassembler_options could be the init function and
 153          free_entry_array (below) could be the termination routine.
 154          Until then there is no way for the disassembler to tell us
 155          that it has finished and that we no longer need the entry
 156          array, so this routine is suppressed for now.  It does mean
 157          that we leak memory, but only to the extent that we do not
 158          free it just before the disassembler is about to terminate
 159          anyway.  */
 160
 161 /* Free memory allocated to our entry array.  */
 162
 163 static void
 164 free_entry_array (void)
 165 {
 166   if (entry_addr)
 167     {
 168       free (entry_addr);
 169       entry_addr = NULL;
 170       entry_addr_occupied_slots = entry_addr_total_slots = 0;
 171     }
 172 }
 173 #endif
 174 /* Check if the given address is a known function entry point.  This is
 175    the case if there is a symbol of the function type at this address.
 176    We also check for synthetic symbols as these are used for PLT entries
 177    (weak undefined symbols may not have the function type set).  Finally
 178    the address may have been forced to be treated as an entry point.  The
 179    latter helps in disassembling ROM images, because there's no symbol
 180    table at all.  Forced entry points can be given by supplying several
 181    -M options to objdump: -M entry:0xffbb7730.  */
 182
 183 static bfd_boolean
 184 is_function_entry (struct disassemble_info *info, bfd_vma addr)
 185 {
 186   unsigned int i;
 187
 188   /* Check if there's a function or PLT symbol at our address.  */
 189   if (info->symbols
 190       && info->symbols[0]
 191       && (info->symbols[0]->flags & (BSF_FUNCTION | BSF_SYNTHETIC))
 192       && addr == bfd_asymbol_value (info->symbols[0]))
 193     return TRUE;
 194
 195   /* Check for forced function entry address.  */
 196   for (i = entry_addr_occupied_slots; i--;)
 197     if (entry_addr[i] == addr)
 198       return TRUE;
 199
 200   return FALSE;
 201 }
 202
 203 /* Check if the given address is the last longword of a PLT entry.
 204    This longword is data and depending on the value it may interfere
 205    with disassembly of further PLT entries.  We make use of the fact
 206    PLT symbols are marked BSF_SYNTHETIC.  */
 207 static bfd_boolean
 208 is_plt_tail (struct disassemble_info *info, bfd_vma addr)
 209 {
 210   if (info->symbols
 211       && info->symbols[0]
 212       && (info->symbols[0]->flags & BSF_SYNTHETIC)
 213       && addr == bfd_asymbol_value (info->symbols[0]) + 8)
 214     return TRUE;
 215
 216   return FALSE;
 217 }
 218
 219 static int
 220 print_insn_mode (const char *d,
 221                  int size,
 222                  unsigned char *p0,
 223                  bfd_vma addr,  /* PC for this arg to be relative to.  */
 224                  disassemble_info *info)
 225 {
 226   unsigned char *p = p0;
 227   unsigned char mode, reg;
 228
 229   /* Fetch and interpret mode byte.  */
 230   mode = (unsigned char) NEXTBYTE (p);
 231   reg = mode & 0xF;
 232   switch (mode & 0xF0)
 233     {
 234     case 0x00:
 235     case 0x10:
 236     case 0x20:
 237     case 0x30: /* Literal mode                  $number.  */
 238       if (d[1] == 'd' || d[1] == 'f' || d[1] == 'g' || d[1] == 'h')
 239         (*info->fprintf_func) (info->stream, "$0x%x [%c-float]", mode, d[1]);
 240       else
 241         (*info->fprintf_func) (info->stream, "$0x%x", mode);
 242       break;
 243     case 0x40: /* Index:                        base-addr[Rn] */
 244       p += print_insn_mode (d, size, p0 + 1, addr + 1, info);
 245       (*info->fprintf_func) (info->stream, "[%s]", reg_names[reg]);
 246       break;
 247     case 0x50: /* Register:                     Rn */
 248       (*info->fprintf_func) (info->stream, "%s", reg_names[reg]);
 249       break;
 250     case 0x60: /* Register deferred:            (Rn) */
 251       (*info->fprintf_func) (info->stream, "(%s)", reg_names[reg]);
 252       break;
 253     case 0x70: /* Autodecrement:                -(Rn) */
 254       (*info->fprintf_func) (info->stream, "-(%s)", reg_names[reg]);
 255       break;
 256     case 0x80: /* Autoincrement:                (Rn)+ */
 257       if (reg == 0xF)
 258         {       /* Immediate?  */
 259           int i;
 260
 261           FETCH_DATA (info, p + size);
 262           (*info->fprintf_func) (info->stream, "$0x");
 263           if (d[1] == 'd' || d[1] == 'f' || d[1] == 'g' || d[1] == 'h')
 264             {
 265               int float_word;
 266
 267               float_word = p[0] | (p[1] << 8);
 268               if ((d[1] == 'd' || d[1] == 'f')
 269                   && (float_word & 0xff80) == 0x8000)
 270                 {
 271                   (*info->fprintf_func) (info->stream, "[invalid %c-float]",
 272                                          d[1]);
 273                 }
 274               else
 275                 {
 276                   for (i = 0; i < size; i++)
 277                     (*info->fprintf_func) (info->stream, "%02x",
 278                                            p[size - i - 1]);
 279                   (*info->fprintf_func) (info->stream, " [%c-float]", d[1]);
 280                 }
 281             }
 282           else
 283             {
 284               for (i = 0; i < size; i++)
 285                 (*info->fprintf_func) (info->stream, "%02x", p[size - i - 1]);
 286             }
 287           p += size;
 288         }
 289       else
 290         (*info->fprintf_func) (info->stream, "(%s)+", reg_names[reg]);
 291       break;
 292     case 0x90: /* Autoincrement deferred:       @(Rn)+ */
 293       if (reg == 0xF)
 294         (*info->fprintf_func) (info->stream, "*0x%x", NEXTLONG (p));
 295       else
 296         (*info->fprintf_func) (info->stream, "@(%s)+", reg_names[reg]);
 297       break;
 298     case 0xB0: /* Displacement byte deferred:   *displ(Rn).  */
 299       (*info->fprintf_func) (info->stream, "*");
 300     case 0xA0: /* Displacement byte:            displ(Rn).  */
 301       if (reg == 0xF)
 302         (*info->print_address_func) (addr + 2 + NEXTBYTE (p), info);
 303       else
 304         (*info->fprintf_func) (info->stream, "0x%x(%s)", NEXTBYTE (p),
 305                                reg_names[reg]);
 306       break;
 307     case 0xD0: /* Displacement word deferred:   *displ(Rn).  */
 308       (*info->fprintf_func) (info->stream, "*");
 309     case 0xC0: /* Displacement word:            displ(Rn).  */
 310       if (reg == 0xF)
 311         (*info->print_address_func) (addr + 3 + NEXTWORD (p), info);
 312       else
 313         (*info->fprintf_func) (info->stream, "0x%x(%s)", NEXTWORD (p),
 314                                reg_names[reg]);
 315       break;
 316     case 0xF0: /* Displacement long deferred:   *displ(Rn).  */
 317       (*info->fprintf_func) (info->stream, "*");
 318     case 0xE0: /* Displacement long:            displ(Rn).  */
 319       if (reg == 0xF)
 320         (*info->print_address_func) (addr + 5 + NEXTLONG (p), info);
 321       else
 322         (*info->fprintf_func) (info->stream, "0x%x(%s)", NEXTLONG (p),
 323                                reg_names[reg]);
 324       break;
 325     }
 326
 327   return p - p0;
 328 }
 329
 330 /* Returns number of bytes "eaten" by the operand, or return -1 if an
 331    invalid operand was found, or -2 if an opcode tabel error was
 332    found. */
 333
 334 static int
 335 print_insn_arg (const char *d,
 336                 unsigned char *p0,
 337                 bfd_vma addr,   /* PC for this arg to be relative to.  */
 338                 disassemble_info *info)
 339 {
 340   int arg_len;
 341
 342   /* Check validity of addressing length.  */
 343   switch (d[1])
 344     {
 345     case 'b' : arg_len = 1;     break;
 346     case 'd' : arg_len = 8;     break;
 347     case 'f' : arg_len = 4;     break;
 348     case 'g' : arg_len = 8;     break;
 349     case 'h' : arg_len = 16;    break;
 350     case 'l' : arg_len = 4;     break;
 351     case 'o' : arg_len = 16;    break;
 352     case 'w' : arg_len = 2;     break;
 353     case 'q' : arg_len = 8;     break;
 354     default  : abort ();
 355     }
 356
 357   /* Branches have no mode byte.  */
 358   if (d[0] == 'b')
 359     {
 360       unsigned char *p = p0;
 361
 362       if (arg_len == 1)
 363         (*info->print_address_func) (addr + 1 + NEXTBYTE (p), info);
 364       else
 365         (*info->print_address_func) (addr + 2 + NEXTWORD (p), info);
 366
 367       return p - p0;
 368     }
 369
 370   return print_insn_mode (d, arg_len, p0, addr, info);
 371 }
 372
 373 /* Print the vax instruction at address MEMADDR in debugged memory,
 374    on INFO->STREAM.  Returns length of the instruction, in bytes.  */
 375
 376 int
 377 print_insn_vax (bfd_vma memaddr, disassemble_info *info)
 378 {
 379   static bfd_boolean parsed_disassembler_options = FALSE;
 380   const struct vot *votp;
 381   const char *argp;
 382   unsigned char *arg;
 383   struct private priv;
 384   bfd_byte *buffer = priv.the_buffer;
 385
 386   info->private_data = & priv;
 387   priv.max_fetched = priv.the_buffer;
 388   priv.insn_start = memaddr;
 389
 390   if (! parsed_disassembler_options
 391       && info->disassembler_options != NULL)
 392     {
 393       parse_disassembler_options (info->disassembler_options);
 394
 395       /* To avoid repeated parsing of these options.  */
 396       parsed_disassembler_options = TRUE;
 397     }
 398
 399   if (setjmp (priv.bailout) != 0)
 400     /* Error return.  */
 401     return -1;
 402
 403   argp = NULL;
 404   /* Check if the info buffer has more than one byte left since
 405      the last opcode might be a single byte with no argument data.  */
 406   if (info->buffer_length - (memaddr - info->buffer_vma) > 1)
 407     {
 408       FETCH_DATA (info, buffer + 2);
 409     }
 410   else
 411     {
 412       FETCH_DATA (info, buffer + 1);
 413       buffer[1] = 0;
 414     }
 415
 416   /* Decode function entry mask.  */
 417   if (is_function_entry (info, memaddr))
 418     {
 419       int i = 0;
 420       int register_mask = buffer[1] << 8 | buffer[0];
 421
 422       (*info->fprintf_func) (info->stream, ".word 0x%04x # Entry mask: <",
 423                              register_mask);
 424
 425       for (i = 15; i >= 0; i--)
 426         if (register_mask & (1 << i))
 427           (*info->fprintf_func) (info->stream, " %s", entry_mask_bit[i]);
 428
 429       (*info->fprintf_func) (info->stream, " >");
 430
 431       return 2;
 432     }
 433
 434   /* Decode PLT entry offset longword.  */
 435   if (is_plt_tail (info, memaddr))
 436     {
 437       int offset;
 438
 439       FETCH_DATA (info, buffer + 4);
 440       offset = buffer[3] << 24 | buffer[2] << 16 | buffer[1] << 8 | buffer[0];
 441       (*info->fprintf_func) (info->stream, ".long 0x%08x", offset);
 442
 443       return 4;
 444     }
 445
 446   for (votp = &votstrs[0]; votp->name[0]; votp++)
 447     {
 448       vax_opcodeT opcode = votp->detail.code;
 449
 450       /* 2 byte codes match 2 buffer pos. */
 451       if ((bfd_byte) opcode == buffer[0]
 452           && (opcode >> 8 == 0 || opcode >> 8 == buffer[1]))
 453         {
 454           argp = votp->detail.args;
 455           break;
 456         }
 457     }
 458   if (argp == NULL)
 459     {
 460       /* Handle undefined instructions. */
 461       (*info->fprintf_func) (info->stream, ".word 0x%x",
 462                              (buffer[0] << 8) + buffer[1]);
 463       return 2;
 464     }
 465
 466   /* Point at first byte of argument data, and at descriptor for first
 467      argument.  */
 468   arg = buffer + ((votp->detail.code >> 8) ? 2 : 1);
 469
 470   /* Make sure we have it in mem */
 471   FETCH_DATA (info, arg);
 472
 473   (*info->fprintf_func) (info->stream, "%s", votp->name);
 474   if (*argp)
 475     (*info->fprintf_func) (info->stream, " ");
 476
 477   while (*argp)
 478     {
 479       arg += print_insn_arg (argp, arg, memaddr + arg - buffer, info);
 480       argp += 2;
 481       if (*argp)
 482         (*info->fprintf_func) (info->stream, ",");
 483     }
 484
 485   return arg - buffer;
 486 }
 487