opcodes/s390-dis.c

   1 /* s390-dis.c -- Disassemble S390 instructions
   2    Copyright (C) 2000-2017 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
  30 static int opc_index[256];
  31 static int current_arch_mask = 0;
  32 static int option_use_insn_len_bits_p = 0;
  33
  34 typedef struct
  35 {
  36   const char *name;
  37   const char *description;
  38 } s390_options_t;
  39
  40 static const s390_options_t options[] =
  41 {
  42   { "esa" ,       N_("Disassemble in ESA architecture mode") },
  43   { "zarch",      N_("Disassemble in z/Architecture mode") },
  44   { "insnlength", N_("Print unknown instructions according to "
  45                      "length from first two bits") }
  46 };
  47
  48 /* Set up index table for first opcode byte.  */
  49
  50 void
  51 disassemble_init_s390 (struct disassemble_info *info)
  52 {
  53   int i;
  54   const char *p;
  55
  56   memset (opc_index, 0, sizeof (opc_index));
  57
  58   /* Reverse order, such that each opc_index ends up pointing to the
  59      first matching entry instead of the last.  */
  60   for (i = s390_num_opcodes; i--; )
  61     opc_index[s390_opcodes[i].opcode[0]] = i;
  62
  63   current_arch_mask = 1 << S390_OPCODE_ZARCH;
  64   option_use_insn_len_bits_p = 0;
  65
  66   for (p = info->disassembler_options; p != NULL; )
  67     {
  68       if (CONST_STRNEQ (p, "esa"))
  69         current_arch_mask = 1 << S390_OPCODE_ESA;
  70       else if (CONST_STRNEQ (p, "zarch"))
  71         current_arch_mask = 1 << S390_OPCODE_ZARCH;
  72       else if (CONST_STRNEQ (p, "insnlength"))
  73         option_use_insn_len_bits_p = 1;
  74       else
  75         fprintf (stderr, "Unknown S/390 disassembler option: %s\n", p);
  76
  77       p = strchr (p, ',');
  78       if (p != NULL)
  79         p++;
  80     }
  81 }
  82
  83 /* Derive the length of an instruction from its first byte.  */
  84
  85 static inline int
  86 s390_insn_length (const bfd_byte *buffer)
  87 {
  88   /* 00xxxxxx -> 2, 01xxxxxx/10xxxxxx -> 4, 11xxxxxx -> 6.  */
  89   return ((buffer[0] >> 6) + 3) & ~1U;
  90 }
  91
  92 /* Match the instruction in BUFFER against the given OPCODE, excluding
  93    the first byte.  */
  94
  95 static inline int
  96 s390_insn_matches_opcode (const bfd_byte *buffer,
  97                           const struct s390_opcode *opcode)
  98 {
  99   return (buffer[1] & opcode->mask[1]) == opcode->opcode[1]
 100     && (buffer[2] & opcode->mask[2]) == opcode->opcode[2]
 101     && (buffer[3] & opcode->mask[3]) == opcode->opcode[3]
 102     && (buffer[4] & opcode->mask[4]) == opcode->opcode[4]
 103     && (buffer[5] & opcode->mask[5]) == opcode->opcode[5];
 104 }
 105
 106 union operand_value
 107 {
 108   int i;
 109   unsigned int u;
 110 };
 111
 112 /* Extracts an operand value from an instruction.  */
 113 /* We do not perform the shift operation for larl-type address
 114    operands here since that would lead to an overflow of the 32 bit
 115    integer value.  Instead the shift operation is done when printing
 116    the operand.  */
 117
 118 static inline union operand_value
 119 s390_extract_operand (const bfd_byte *insn,
 120                       const struct s390_operand *operand)
 121 {
 122   union operand_value ret;
 123   unsigned int val;
 124   int bits;
 125   const bfd_byte *orig_insn = insn;
 126
 127   /* Extract fragments of the operand byte for byte.  */
 128   insn += operand->shift / 8;
 129   bits = (operand->shift & 7) + operand->bits;
 130   val = 0;
 131   do
 132     {
 133       val <<= 8;
 134       val |= (unsigned int) *insn++;
 135       bits -= 8;
 136     }
 137   while (bits > 0);
 138   val >>= -bits;
 139   val &= ((1U << (operand->bits - 1)) << 1) - 1;
 140
 141   /* Check for special long displacement case.  */
 142   if (operand->bits == 20 && operand->shift == 20)
 143     val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;
 144
 145   /* Sign extend value if the operand is signed or pc relative.  Avoid
 146      integer overflows.  */
 147   if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
 148     {
 149       unsigned int m = 1U << (operand->bits - 1);
 150
 151       if (val >= m)
 152         ret.i = (int) (val - m) - 1 - (int) (m - 1U);
 153       else
 154         ret.i = (int) val;
 155     }
 156   else if (operand->flags & S390_OPERAND_LENGTH)
 157     /* Length x in an instruction has real length x + 1.  */
 158     ret.u = val + 1;
 159
 160   else if (operand->flags & S390_OPERAND_VR)
 161     {
 162       /* Extract the extra bits for a vector register operand stored
 163          in the RXB field.  */
 164       unsigned vr = operand->shift == 32 ? 3
 165         : (unsigned) operand->shift / 4 - 2;
 166
 167       ret.u = val | ((orig_insn[4] & (1 << (3 - vr))) << (vr + 1));
 168     }
 169   else
 170     ret.u = val;
 171
 172   return ret;
 173 }
 174
 175 /* Print the S390 instruction in BUFFER, assuming that it matches the
 176    given OPCODE.  */
 177
 178 static void
 179 s390_print_insn_with_opcode (bfd_vma memaddr,
 180                              struct disassemble_info *info,
 181                              const bfd_byte *buffer,
 182                              const struct s390_opcode *opcode)
 183 {
 184   const unsigned char *opindex;
 185   char separator;
 186
 187   /* Mnemonic.  */
 188   info->fprintf_func (info->stream, "%s", opcode->name);
 189
 190   /* Operands.  */
 191   separator = '\t';
 192   for (opindex = opcode->operands; *opindex != 0; opindex++)
 193     {
 194       const struct s390_operand *operand = s390_operands + *opindex;
 195       union operand_value val = s390_extract_operand (buffer, operand);
 196       unsigned long flags = operand->flags;
 197
 198       if ((flags & S390_OPERAND_INDEX) && val.u == 0)
 199         continue;
 200       if ((flags & S390_OPERAND_BASE) &&
 201           val.u == 0 && separator == '(')
 202         {
 203           separator = ',';
 204           continue;
 205         }
 206
 207       /* For instructions with a last optional operand don't print it
 208          if zero.  */
 209       if ((opcode->flags & (S390_INSTR_FLAG_OPTPARM | S390_INSTR_FLAG_OPTPARM2))
 210           && val.u == 0
 211           && opindex[1] == 0)
 212         break;
 213
 214       if ((opcode->flags & S390_INSTR_FLAG_OPTPARM2)
 215           && val.u == 0 && opindex[1] != 0 && opindex[2] == 0)
 216         {
 217           union operand_value next_op_val =
 218             s390_extract_operand (buffer, s390_operands + opindex[1]);
 219           if (next_op_val.u == 0)
 220             break;
 221         }
 222
 223       if (flags & S390_OPERAND_GPR)
 224         info->fprintf_func (info->stream, "%c%%r%u", separator, val.u);
 225       else if (flags & S390_OPERAND_FPR)
 226         info->fprintf_func (info->stream, "%c%%f%u", separator, val.u);
 227       else if (flags & S390_OPERAND_VR)
 228         info->fprintf_func (info->stream, "%c%%v%i", separator, val.u);
 229       else if (flags & S390_OPERAND_AR)
 230         info->fprintf_func (info->stream, "%c%%a%u", separator, val.u);
 231       else if (flags & S390_OPERAND_CR)
 232         info->fprintf_func (info->stream, "%c%%c%u", separator, val.u);
 233       else if (flags & S390_OPERAND_PCREL)
 234         {
 235           info->fprintf_func (info->stream, "%c", separator);
 236           info->print_address_func (memaddr + val.i + val.i, info);
 237         }
 238       else if (flags & S390_OPERAND_SIGNED)
 239         info->fprintf_func (info->stream, "%c%i", separator, val.i);
 240       else
 241         {
 242           if (flags & S390_OPERAND_OR1)
 243             val.u &= ~1;
 244           if (flags & S390_OPERAND_OR2)
 245             val.u &= ~2;
 246           if (flags & S390_OPERAND_OR8)
 247             val.u &= ~8;
 248
 249           if ((opcode->flags & S390_INSTR_FLAG_OPTPARM)
 250               && val.u == 0
 251               && opindex[1] == 0)
 252             break;
 253           info->fprintf_func (info->stream, "%c%u", separator, val.u);
 254         }
 255
 256       if (flags & S390_OPERAND_DISP)
 257         separator = '(';
 258       else if (flags & S390_OPERAND_BASE)
 259         {
 260           info->fprintf_func (info->stream, ")");
 261           separator = ',';
 262         }
 263       else
 264         separator = ',';
 265     }
 266 }
 267
 268 /* Check whether opcode A's mask is more specific than that of B.  */
 269
 270 static int
 271 opcode_mask_more_specific (const struct s390_opcode *a,
 272                            const struct s390_opcode *b)
 273 {
 274   return (((int) a->mask[0] + a->mask[1] + a->mask[2]
 275            + a->mask[3] + a->mask[4] + a->mask[5])
 276           > ((int) b->mask[0] + b->mask[1] + b->mask[2]
 277              + b->mask[3] + b->mask[4] + b->mask[5]));
 278 }
 279
 280 /* Print a S390 instruction.  */
 281
 282 int
 283 print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
 284 {
 285   bfd_byte buffer[6];
 286   const struct s390_opcode *opcode = NULL;
 287   unsigned int value;
 288   int status, opsize, bufsize, bytes_to_dump, i;
 289
 290   /* The output looks better if we put 6 bytes on a line.  */
 291   info->bytes_per_line = 6;
 292
 293   /* Every S390 instruction is max 6 bytes long.  */
 294   memset (buffer, 0, 6);
 295   status = info->read_memory_func (memaddr, buffer, 6, info);
 296   if (status != 0)
 297     {
 298       for (bufsize = 0; bufsize < 6; bufsize++)
 299         if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
 300           break;
 301       if (bufsize <= 0)
 302         {
 303           info->memory_error_func (status, memaddr, info);
 304           return -1;
 305         }
 306       opsize = s390_insn_length (buffer);
 307       status = opsize > bufsize;
 308     }
 309   else
 310     {
 311       bufsize = 6;
 312       opsize = s390_insn_length (buffer);
 313     }
 314
 315   if (status == 0)
 316     {
 317       const struct s390_opcode *op;
 318
 319       /* Find the "best match" in the opcode table.  */
 320       for (op = s390_opcodes + opc_index[buffer[0]];
 321            op != s390_opcodes + s390_num_opcodes
 322              && op->opcode[0] == buffer[0];
 323            op++)
 324         {
 325           if ((op->modes & current_arch_mask)
 326               && s390_insn_matches_opcode (buffer, op)
 327               && (opcode == NULL
 328                   || opcode_mask_more_specific (op, opcode)))
 329             opcode = op;
 330         }
 331
 332       if (opcode != NULL)
 333         {
 334           /* The instruction is valid.  Print it and return its size.  */
 335           s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
 336           return opsize;
 337         }
 338     }
 339
 340   /* For code sections it makes sense to skip unknown instructions
 341      according to their length bits.  */
 342   if (status == 0
 343       && option_use_insn_len_bits_p
 344       && info->section != NULL
 345       && (info->section->flags & SEC_CODE))
 346     bytes_to_dump = opsize;
 347   else
 348     /* By default unknown instructions are printed as .long's/.short'
 349        depending on how many bytes are available.  */
 350     bytes_to_dump = bufsize >= 4 ? 4 : bufsize;
 351
 352   if (bytes_to_dump == 0)
 353     return 0;
 354
 355   /* Fall back to hex print.  */
 356   switch (bytes_to_dump)
 357     {
 358     case 4:
 359       value = (unsigned int) buffer[0];
 360       value = (value << 8) + (unsigned int) buffer[1];
 361       value = (value << 8) + (unsigned int) buffer[2];
 362       value = (value << 8) + (unsigned int) buffer[3];
 363       info->fprintf_func (info->stream, ".long\t0x%08x", value);
 364       return 4;
 365     case 2:
 366       value = (unsigned int) buffer[0];
 367       value = (value << 8) + (unsigned int) buffer[1];
 368       info->fprintf_func (info->stream, ".short\t0x%04x", value);
 369       return 2;
 370     default:
 371       info->fprintf_func (info->stream, ".byte\t0x%02x",
 372                           (unsigned int) buffer[0]);
 373       for (i = 1; i < bytes_to_dump; i++)
 374         info->fprintf_func (info->stream, ",0x%02x",
 375                           (unsigned int) buffer[i]);
 376       return bytes_to_dump;
 377     }
 378   return 0;
 379 }
 380
 381 const disasm_options_t *
 382 disassembler_options_s390 (void)
 383 {
 384   static disasm_options_t *opts = NULL;
 385
 386   if (opts == NULL)
 387     {
 388       size_t i, num_options = ARRAY_SIZE (options);
 389       opts = XNEW (disasm_options_t);
 390       opts->name = XNEWVEC (const char *, num_options + 1);
 391       opts->description = XNEWVEC (const char *, num_options + 1);
 392       for (i = 0; i < num_options; i++)
 393         {
 394           opts->name[i] = options[i].name;
 395           opts->description[i] = _(options[i].description);
 396         }
 397       /* The array we return must be NULL terminated.  */
 398       opts->name[i] = NULL;
 399       opts->description[i] = NULL;
 400     }
 401
 402   return opts;
 403 }
 404
 405 void
 406 print_s390_disassembler_options (FILE *stream)
 407 {
 408   unsigned int i, max_len = 0;
 409   fprintf (stream, _("\n\
 410 The following S/390 specific disassembler options are supported for use\n\
 411 with the -M switch (multiple options should be separated by commas):\n"));
 412
 413   for (i = 0; i < ARRAY_SIZE (options); i++)
 414     {
 415       unsigned int len = strlen (options[i].name);
 416       if (max_len < len)
 417         max_len = len;
 418     }
 419
 420   for (i = 0, max_len++; i < ARRAY_SIZE (options); i++)
 421     fprintf (stream, "  %s%*c %s\n",
 422              options[i].name,
 423              (int)(max_len - strlen (options[i].name)), ' ',
 424              _(options[i].description));
 425 }