opcodes/s390-dis.c

   1 /* s390-dis.c -- Disassemble S390 instructions
   2    Copyright (C) 2000-2024 Free Software Foundation, Inc.
   3    Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
   4
   5    This file is part of the GNU opcodes library.
   6
   7    This library is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3, or (at your option)
  10    any later version.
  11
  12    It is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this file; see the file COPYING.  If not, write to the
  19    Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston,
  20    MA 02110-1301, USA.  */
  21
  22 #include "sysdep.h"
  23 #include <stdio.h>
  24 #include "ansidecl.h"
  25 #include "disassemble.h"
  26 #include "opintl.h"
  27 #include "opcode/s390.h"
  28 #include "libiberty.h"
  29 #include "dis-asm.h"
  30
  31 static int opc_index[256];
  32 static int current_arch_mask = 0;
  33 static int option_use_insn_len_bits_p = 0;
  34 static int option_print_insn_desc = 0;
  35
  36 typedef struct
  37 {
  38   const char *name;
  39   const char *description;
  40 } s390_options_t;
  41
  42 static const s390_options_t options[] =
  43 {
  44   { "esa" ,       N_("Disassemble in ESA architecture mode") },
  45   /* TRANSLATORS: Please do not translate 'z/Architecture' as this is a technical name.  */
  46   { "zarch",      N_("Disassemble in z/Architecture mode") },
  47   { "insnlength", N_("Print unknown instructions according to "
  48                      "length from first two bits") },
  49   { "insndesc",   N_("Print instruction description as comment") },
  50 };
  51
  52 /* Set up index table for first opcode byte.  */
  53
  54 void
  55 disassemble_init_s390 (struct disassemble_info *info)
  56 {
  57   int i;
  58   const char *p;
  59
  60   memset (opc_index, 0, sizeof (opc_index));
  61
  62   /* Reverse order, such that each opc_index ends up pointing to the
  63      first matching entry instead of the last.  */
  64   for (i = s390_num_opcodes; i--; )
  65     opc_index[s390_opcodes[i].opcode[0]] = i;
  66
  67   current_arch_mask = 1 << S390_OPCODE_ZARCH;
  68   option_use_insn_len_bits_p = 0;
  69   option_print_insn_desc = 0;
  70
  71   for (p = info->disassembler_options; p != NULL; )
  72     {
  73       if (startswith (p, "esa"))
  74         current_arch_mask = 1 << S390_OPCODE_ESA;
  75       else if (startswith (p, "zarch"))
  76         current_arch_mask = 1 << S390_OPCODE_ZARCH;
  77       else if (startswith (p, "insnlength"))
  78         option_use_insn_len_bits_p = 1;
  79       else if (startswith (p, "insndesc"))
  80         option_print_insn_desc = 1;
  81       else
  82         /* xgettext:c-format */
  83         opcodes_error_handler (_("unknown S/390 disassembler option: %s"), p);
  84
  85       p = strchr (p, ',');
  86       if (p != NULL)
  87         p++;
  88     }
  89 }
  90
  91 /* Derive the length of an instruction from its first byte.  */
  92
  93 static inline int
  94 s390_insn_length (const bfd_byte *buffer)
  95 {
  96   /* 00xxxxxx -> 2, 01xxxxxx/10xxxxxx -> 4, 11xxxxxx -> 6.  */
  97   return ((buffer[0] >> 6) + 3) & ~1U;
  98 }
  99
 100 /* Match the instruction in BUFFER against the given OPCODE, excluding
 101    the first byte.  */
 102
 103 static inline int
 104 s390_insn_matches_opcode (const bfd_byte *buffer,
 105                           const struct s390_opcode *opcode)
 106 {
 107   return (buffer[1] & opcode->mask[1]) == opcode->opcode[1]
 108     && (buffer[2] & opcode->mask[2]) == opcode->opcode[2]
 109     && (buffer[3] & opcode->mask[3]) == opcode->opcode[3]
 110     && (buffer[4] & opcode->mask[4]) == opcode->opcode[4]
 111     && (buffer[5] & opcode->mask[5]) == opcode->opcode[5];
 112 }
 113
 114 union operand_value
 115 {
 116   int i;
 117   unsigned int u;
 118 };
 119
 120 /* Extracts an operand value from an instruction.  */
 121 /* We do not perform the shift operation for larl-type address
 122    operands here since that would lead to an overflow of the 32 bit
 123    integer value.  Instead the shift operation is done when printing
 124    the operand.  */
 125
 126 static inline union operand_value
 127 s390_extract_operand (const bfd_byte *insn,
 128                       const struct s390_operand *operand)
 129 {
 130   union operand_value ret;
 131   unsigned int val;
 132   int bits;
 133   const bfd_byte *orig_insn = insn;
 134
 135   /* Extract fragments of the operand byte for byte.  */
 136   insn += operand->shift / 8;
 137   bits = (operand->shift & 7) + operand->bits;
 138   val = 0;
 139   do
 140     {
 141       val <<= 8;
 142       val |= (unsigned int) *insn++;
 143       bits -= 8;
 144     }
 145   while (bits > 0);
 146   val >>= -bits;
 147   val &= ((1U << (operand->bits - 1)) << 1) - 1;
 148
 149   /* Check for special long displacement case.  */
 150   if (operand->bits == 20 && operand->shift == 20)
 151     val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;
 152
 153   /* Sign extend value if the operand is signed or pc relative.  Avoid
 154      integer overflows.  */
 155   if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
 156     {
 157       unsigned int m = 1U << (operand->bits - 1);
 158
 159       if (val >= m)
 160         ret.i = (int) (val - m) - 1 - (int) (m - 1U);
 161       else
 162         ret.i = (int) val;
 163     }
 164   else if (operand->flags & S390_OPERAND_LENGTH)
 165     /* Length x in an instruction has real length x + 1.  */
 166     ret.u = val + 1;
 167
 168   else if (operand->flags & S390_OPERAND_VR)
 169     {
 170       /* Extract the extra bits for a vector register operand stored
 171          in the RXB field.  */
 172       unsigned vr = operand->shift == 32 ? 3
 173         : (unsigned) operand->shift / 4 - 2;
 174
 175       ret.u = val | ((orig_insn[4] & (1 << (3 - vr))) << (vr + 1));
 176     }
 177   else
 178     ret.u = val;
 179
 180   return ret;
 181 }
 182
 183 /* Print the S390 instruction in BUFFER, assuming that it matches the
 184    given OPCODE.  */
 185
 186 static void
 187 s390_print_insn_with_opcode (bfd_vma memaddr,
 188                              struct disassemble_info *info,
 189                              const bfd_byte *buffer,
 190                              const struct s390_opcode *opcode)
 191 {
 192   const unsigned char *opindex;
 193   char separator;
 194
 195   /* Mnemonic.  */
 196   info->fprintf_styled_func (info->stream, dis_style_mnemonic,
 197                              "%s", opcode->name);
 198
 199   /* Operands.  */
 200   separator = '\t';
 201   for (opindex = opcode->operands; *opindex != 0; opindex++)
 202     {
 203       const struct s390_operand *operand = s390_operands + *opindex;
 204       union operand_value val = s390_extract_operand (buffer, operand);
 205       unsigned long flags = operand->flags;
 206
 207       /* Omit index register 0.  */
 208       if ((flags & S390_OPERAND_INDEX) && val.u == 0)
 209         continue;
 210       /* Omit base register 0, if no or omitted index register 0.  */
 211       if ((flags & S390_OPERAND_BASE) && val.u == 0 && separator == '(')
 212         {
 213           separator = ',';
 214           continue;
 215         }
 216
 217       /* For instructions with a last optional operand don't print it
 218          if zero.  */
 219       if ((opcode->flags & (S390_INSTR_FLAG_OPTPARM | S390_INSTR_FLAG_OPTPARM2))
 220           && val.u == 0
 221           && opindex[1] == 0)
 222         break;
 223
 224       if ((opcode->flags & S390_INSTR_FLAG_OPTPARM2)
 225           && val.u == 0 && opindex[1] != 0 && opindex[2] == 0)
 226         {
 227           union operand_value next_op_val =
 228             s390_extract_operand (buffer, s390_operands + opindex[1]);
 229           if (next_op_val.u == 0)
 230             break;
 231         }
 232
 233       if (flags & S390_OPERAND_GPR)
 234         {
 235           info->fprintf_styled_func (info->stream, dis_style_text,
 236                                      "%c", separator);
 237           if ((flags & (S390_OPERAND_BASE | S390_OPERAND_INDEX))
 238               && val.u == 0)
 239             info->fprintf_styled_func (info->stream, dis_style_register,
 240                                        "%u", val.u);
 241           else
 242             info->fprintf_styled_func (info->stream, dis_style_register,
 243                                        "%%r%u", val.u);
 244         }
 245       else if (flags & S390_OPERAND_FPR)
 246         {
 247           info->fprintf_styled_func (info->stream, dis_style_text,
 248                                      "%c", separator);
 249           info->fprintf_styled_func (info->stream, dis_style_register,
 250                                      "%%f%u", val.u);
 251         }
 252       else if (flags & S390_OPERAND_VR)
 253         {
 254           info->fprintf_styled_func (info->stream, dis_style_text,
 255                                      "%c", separator);
 256           if ((flags & S390_OPERAND_INDEX) && val.u == 0)
 257             info->fprintf_styled_func (info->stream, dis_style_register,
 258                                        "%u", val.u);
 259           else
 260             info->fprintf_styled_func (info->stream, dis_style_register,
 261                                        "%%v%i", val.u);
 262         }
 263       else if (flags & S390_OPERAND_AR)
 264         {
 265           info->fprintf_styled_func (info->stream, dis_style_text,
 266                                      "%c", separator);
 267           info->fprintf_styled_func (info->stream, dis_style_register,
 268                                      "%%a%u", val.u);
 269         }
 270       else if (flags & S390_OPERAND_CR)
 271         {
 272           info->fprintf_styled_func (info->stream, dis_style_text,
 273                                      "%c", separator);
 274           info->fprintf_styled_func (info->stream, dis_style_register,
 275                                      "%%c%u", val.u);
 276         }
 277       else if (flags & S390_OPERAND_PCREL)
 278         {
 279           bfd_vma target = memaddr + val.i + val.i;
 280
 281           /* Provide info for jump visualization.  May be evaluated by p_a_f().  */
 282           info->target = target;
 283
 284           info->fprintf_styled_func (info->stream, dis_style_text,
 285                                      "%c", separator);
 286           info->print_address_func (target, info);
 287         }
 288       else if (flags & S390_OPERAND_SIGNED)
 289         {
 290           enum disassembler_style style;
 291
 292           info->fprintf_styled_func (info->stream, dis_style_text,
 293                                      "%c", separator);
 294           style = ((flags & S390_OPERAND_DISP)
 295                    ? dis_style_address_offset : dis_style_immediate);
 296           info->fprintf_styled_func (info->stream, style, "%i", val.i);
 297         }
 298       else
 299         {
 300           enum disassembler_style style;
 301
 302           if (!(flags & S390_OPERAND_LENGTH))
 303             {
 304               union operand_value insn_opval;
 305
 306               /* Mask any constant operand bits set in insn template.  */
 307               insn_opval = s390_extract_operand (opcode->opcode, operand);
 308               val.u &= ~insn_opval.u;
 309             }
 310
 311           if ((opcode->flags & S390_INSTR_FLAG_OPTPARM)
 312               && val.u == 0
 313               && opindex[1] == 0)
 314             break;
 315           info->fprintf_styled_func (info->stream, dis_style_text,
 316                                      "%c", separator);
 317           style = ((flags & S390_OPERAND_DISP)
 318                    ? dis_style_address_offset : dis_style_immediate);
 319           info->fprintf_styled_func (info->stream, style, "%u", val.u);
 320         }
 321
 322       if (flags & S390_OPERAND_DISP)
 323         separator = '(';
 324       else if (flags & S390_OPERAND_BASE)
 325         {
 326           info->fprintf_styled_func (info->stream, dis_style_text, ")");
 327           separator = ',';
 328         }
 329       else
 330         separator = ',';
 331     }
 332
 333   /* Optional: instruction name.  */
 334   if (option_print_insn_desc && opcode->description
 335       && opcode->description[0] != '\0')
 336     info->fprintf_styled_func (info->stream, dis_style_comment_start, "\t# %s",
 337                                opcode->description);
 338 }
 339
 340 /* Check whether opcode A's mask is more specific than that of B.  */
 341
 342 static int
 343 opcode_mask_more_specific (const struct s390_opcode *a,
 344                            const struct s390_opcode *b)
 345 {
 346   return (((int) a->mask[0] + a->mask[1] + a->mask[2]
 347            + a->mask[3] + a->mask[4] + a->mask[5])
 348           > ((int) b->mask[0] + b->mask[1] + b->mask[2]
 349              + b->mask[3] + b->mask[4] + b->mask[5]));
 350 }
 351
 352 /* Print a S390 instruction.  */
 353
 354 int
 355 print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
 356 {
 357   bfd_byte buffer[6];
 358   const struct s390_opcode *opcode = NULL;
 359   unsigned int value;
 360   int status, opsize, bufsize, bytes_to_dump, i;
 361
 362   /* The output looks better if we put 6 bytes on a line.  */
 363   info->bytes_per_line = 6;
 364
 365   /* Set some defaults for the insn info.  */
 366   info->insn_info_valid    = 0;
 367   info->branch_delay_insns = 0;
 368   info->data_size          = 0;
 369   info->insn_type          = dis_nonbranch;
 370   info->target             = 0;
 371   info->target2            = 0;
 372
 373   /* Every S390 instruction is max 6 bytes long.  */
 374   memset (buffer, 0, 6);
 375   status = info->read_memory_func (memaddr, buffer, 6, info);
 376   if (status != 0)
 377     {
 378       for (bufsize = 0; bufsize < 6; bufsize++)
 379         if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
 380           break;
 381       if (bufsize <= 0)
 382         {
 383           info->memory_error_func (status, memaddr, info);
 384           return -1;
 385         }
 386       opsize = s390_insn_length (buffer);
 387       status = opsize > bufsize;
 388     }
 389   else
 390     {
 391       bufsize = 6;
 392       opsize = s390_insn_length (buffer);
 393     }
 394
 395   if (status == 0)
 396     {
 397       const struct s390_opcode *op;
 398
 399       /* Find the "best match" in the opcode table.  */
 400       for (op = s390_opcodes + opc_index[buffer[0]];
 401            op != s390_opcodes + s390_num_opcodes
 402              && op->opcode[0] == buffer[0];
 403            op++)
 404         {
 405           if ((op->modes & current_arch_mask)
 406               && s390_insn_matches_opcode (buffer, op)
 407               && (opcode == NULL
 408                   || opcode_mask_more_specific (op, opcode)))
 409             opcode = op;
 410         }
 411
 412       if (opcode != NULL)
 413         {
 414           /* Provide info for jump visualization.  Must be done before print.  */
 415           switch (opcode->flags & S390_INSTR_FLAG_CLASS_MASK)
 416             {
 417             case S390_INSTR_FLAGS_CLASS_JUMP:
 418               info->insn_type = dis_branch;
 419               break;
 420             case S390_INSTR_FLAGS_CLASS_CONDJUMP:
 421               info->insn_type = dis_condbranch;
 422               break;
 423             case S390_INSTR_FLAGS_CLASS_JUMPSR:
 424               info->insn_type = dis_jsr;
 425               break;
 426             default:
 427               info->insn_type = dis_nonbranch;
 428             }
 429           info->insn_info_valid = 1;
 430
 431           /* The instruction is valid.  Print it and return its size.  */
 432           s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
 433           return opsize;
 434         }
 435     }
 436
 437   /* For code sections it makes sense to skip unknown instructions
 438      according to their length bits.  */
 439   if (status == 0
 440       && option_use_insn_len_bits_p
 441       && info->section != NULL
 442       && (info->section->flags & SEC_CODE))
 443     bytes_to_dump = opsize;
 444   else
 445     /* By default unknown instructions are printed as .long's/.short'
 446        depending on how many bytes are available.  */
 447     bytes_to_dump = bufsize >= 4 ? 4 : bufsize;
 448
 449   if (bytes_to_dump == 0)
 450     return 0;
 451
 452   info->insn_type = dis_noninsn;
 453   info->insn_info_valid = 1;
 454
 455   /* Fall back to hex print.  */
 456   switch (bytes_to_dump)
 457     {
 458     case 4:
 459       value = (unsigned int) buffer[0];
 460       value = (value << 8) + (unsigned int) buffer[1];
 461       value = (value << 8) + (unsigned int) buffer[2];
 462       value = (value << 8) + (unsigned int) buffer[3];
 463       info->fprintf_styled_func (info->stream, dis_style_assembler_directive,
 464                                  ".long");
 465       info->fprintf_styled_func (info->stream, dis_style_text,
 466                                  "\t");
 467       info->fprintf_styled_func (info->stream, dis_style_immediate,
 468                                  "0x%08x", value);
 469       return 4;
 470     case 2:
 471       value = (unsigned int) buffer[0];
 472       value = (value << 8) + (unsigned int) buffer[1];
 473       info->fprintf_styled_func (info->stream, dis_style_assembler_directive,
 474                                  ".short");
 475       info->fprintf_styled_func (info->stream, dis_style_text,
 476                                  "\t");
 477       info->fprintf_styled_func (info->stream, dis_style_immediate,
 478                                  "0x%04x", value);
 479       return 2;
 480     default:
 481       info->fprintf_styled_func (info->stream, dis_style_assembler_directive,
 482                                  ".byte");
 483       info->fprintf_styled_func (info->stream, dis_style_text,
 484                                  "\t");
 485       info->fprintf_styled_func (info->stream, dis_style_immediate,
 486                                  "0x%02x", (unsigned int) buffer[0]);
 487       for (i = 1; i < bytes_to_dump; i++)
 488         info->fprintf_styled_func (info->stream, dis_style_immediate,
 489                                    "0x%02x", (unsigned int) buffer[i]);
 490       return bytes_to_dump;
 491     }
 492   return 0;
 493 }
 494
 495 const disasm_options_and_args_t *
 496 disassembler_options_s390 (void)
 497 {
 498   static disasm_options_and_args_t *opts_and_args;
 499
 500   if (opts_and_args == NULL)
 501     {
 502       size_t i, num_options = ARRAY_SIZE (options);
 503       disasm_options_t *opts;
 504
 505       opts_and_args = XNEW (disasm_options_and_args_t);
 506       opts_and_args->args = NULL;
 507
 508       opts = &opts_and_args->options;
 509       opts->name = XNEWVEC (const char *, num_options + 1);
 510       opts->description = XNEWVEC (const char *, num_options + 1);
 511       opts->arg = NULL;
 512       for (i = 0; i < num_options; i++)
 513         {
 514           opts->name[i] = options[i].name;
 515           opts->description[i] = _(options[i].description);
 516         }
 517       /* The array we return must be NULL terminated.  */
 518       opts->name[i] = NULL;
 519       opts->description[i] = NULL;
 520     }
 521
 522   return opts_and_args;
 523 }
 524
 525 void
 526 print_s390_disassembler_options (FILE *stream)
 527 {
 528   unsigned int i, max_len = 0;
 529   fprintf (stream, _("\n\
 530 The following S/390 specific disassembler options are supported for use\n\
 531 with the -M switch (multiple options should be separated by commas):\n"));
 532
 533   for (i = 0; i < ARRAY_SIZE (options); i++)
 534     {
 535       unsigned int len = strlen (options[i].name);
 536       if (max_len < len)
 537         max_len = len;
 538     }
 539
 540   for (i = 0, max_len++; i < ARRAY_SIZE (options); i++)
 541     fprintf (stream, "  %s%*c %s\n",
 542              options[i].name,
 543              (int)(max_len - strlen (options[i].name)), ' ',
 544              _(options[i].description));
 545 }