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 "dis-asm.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)
 210           && val.u == 0
 211           && opindex[1] == 0)
 212         break;
 213
 214       if (flags & S390_OPERAND_GPR)
 215         info->fprintf_func (info->stream, "%c%%r%u", separator, val.u);
 216       else if (flags & S390_OPERAND_FPR)
 217         info->fprintf_func (info->stream, "%c%%f%u", separator, val.u);
 218       else if (flags & S390_OPERAND_VR)
 219         info->fprintf_func (info->stream, "%c%%v%i", separator, val.u);
 220       else if (flags & S390_OPERAND_AR)
 221         info->fprintf_func (info->stream, "%c%%a%u", separator, val.u);
 222       else if (flags & S390_OPERAND_CR)
 223         info->fprintf_func (info->stream, "%c%%c%u", separator, val.u);
 224       else if (flags & S390_OPERAND_PCREL)
 225         {
 226           info->fprintf_func (info->stream, "%c", separator);
 227           info->print_address_func (memaddr + val.i + val.i, info);
 228         }
 229       else if (flags & S390_OPERAND_SIGNED)
 230         info->fprintf_func (info->stream, "%c%i", separator, val.i);
 231       else
 232         {
 233           if (flags & S390_OPERAND_OR1)
 234             val.u &= ~1;
 235           if (flags & S390_OPERAND_OR2)
 236             val.u &= ~2;
 237           if (flags & S390_OPERAND_OR8)
 238             val.u &= ~8;
 239
 240           if ((opcode->flags & S390_INSTR_FLAG_OPTPARM)
 241               && val.u == 0
 242               && opindex[1] == 0)
 243             break;
 244           info->fprintf_func (info->stream, "%c%u", separator, val.u);
 245         }
 246
 247       if (flags & S390_OPERAND_DISP)
 248         separator = '(';
 249       else if (flags & S390_OPERAND_BASE)
 250         {
 251           info->fprintf_func (info->stream, ")");
 252           separator = ',';
 253         }
 254       else
 255         separator = ',';
 256     }
 257 }
 258
 259 /* Check whether opcode A's mask is more specific than that of B.  */
 260
 261 static int
 262 opcode_mask_more_specific (const struct s390_opcode *a,
 263                            const struct s390_opcode *b)
 264 {
 265   return (((int) a->mask[0] + a->mask[1] + a->mask[2]
 266            + a->mask[3] + a->mask[4] + a->mask[5])
 267           > ((int) b->mask[0] + b->mask[1] + b->mask[2]
 268              + b->mask[3] + b->mask[4] + b->mask[5]));
 269 }
 270
 271 /* Print a S390 instruction.  */
 272
 273 int
 274 print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
 275 {
 276   bfd_byte buffer[6];
 277   const struct s390_opcode *opcode = NULL;
 278   unsigned int value;
 279   int status, opsize, bufsize, bytes_to_dump, i;
 280
 281   /* The output looks better if we put 6 bytes on a line.  */
 282   info->bytes_per_line = 6;
 283
 284   /* Every S390 instruction is max 6 bytes long.  */
 285   memset (buffer, 0, 6);
 286   status = info->read_memory_func (memaddr, buffer, 6, info);
 287   if (status != 0)
 288     {
 289       for (bufsize = 0; bufsize < 6; bufsize++)
 290         if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
 291           break;
 292       if (bufsize <= 0)
 293         {
 294           info->memory_error_func (status, memaddr, info);
 295           return -1;
 296         }
 297       opsize = s390_insn_length (buffer);
 298       status = opsize > bufsize;
 299     }
 300   else
 301     {
 302       bufsize = 6;
 303       opsize = s390_insn_length (buffer);
 304     }
 305
 306   if (status == 0)
 307     {
 308       const struct s390_opcode *op;
 309
 310       /* Find the "best match" in the opcode table.  */
 311       for (op = s390_opcodes + opc_index[buffer[0]];
 312            op != s390_opcodes + s390_num_opcodes
 313              && op->opcode[0] == buffer[0];
 314            op++)
 315         {
 316           if ((op->modes & current_arch_mask)
 317               && s390_insn_matches_opcode (buffer, op)
 318               && (opcode == NULL
 319                   || opcode_mask_more_specific (op, opcode)))
 320             opcode = op;
 321         }
 322
 323       if (opcode != NULL)
 324         {
 325           /* The instruction is valid.  Print it and return its size.  */
 326           s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
 327           return opsize;
 328         }
 329     }
 330
 331   /* For code sections it makes sense to skip unknown instructions
 332      according to their length bits.  */
 333   if (status == 0
 334       && option_use_insn_len_bits_p
 335       && info->section != NULL
 336       && (info->section->flags & SEC_CODE))
 337     bytes_to_dump = opsize;
 338   else
 339     /* By default unknown instructions are printed as .long's/.short'
 340        depending on how many bytes are available.  */
 341     bytes_to_dump = bufsize >= 4 ? 4 : bufsize;
 342
 343   if (bytes_to_dump == 0)
 344     return 0;
 345
 346   /* Fall back to hex print.  */
 347   switch (bytes_to_dump)
 348     {
 349     case 4:
 350       value = (unsigned int) buffer[0];
 351       value = (value << 8) + (unsigned int) buffer[1];
 352       value = (value << 8) + (unsigned int) buffer[2];
 353       value = (value << 8) + (unsigned int) buffer[3];
 354       info->fprintf_func (info->stream, ".long\t0x%08x", value);
 355       return 4;
 356     case 2:
 357       value = (unsigned int) buffer[0];
 358       value = (value << 8) + (unsigned int) buffer[1];
 359       info->fprintf_func (info->stream, ".short\t0x%04x", value);
 360       return 2;
 361     default:
 362       info->fprintf_func (info->stream, ".byte\t0x%02x",
 363                           (unsigned int) buffer[0]);
 364       for (i = 1; i < bytes_to_dump; i++)
 365         info->fprintf_func (info->stream, ",0x%02x",
 366                           (unsigned int) buffer[i]);
 367       return bytes_to_dump;
 368     }
 369   return 0;
 370 }
 371
 372 const disasm_options_t *
 373 disassembler_options_s390 (void)
 374 {
 375   static disasm_options_t *opts = NULL;
 376
 377   if (opts == NULL)
 378     {
 379       size_t i, num_options = ARRAY_SIZE (options);
 380       opts = XNEW (disasm_options_t);
 381       opts->name = XNEWVEC (const char *, num_options + 1);
 382       opts->description = XNEWVEC (const char *, num_options + 1);
 383       for (i = 0; i < num_options; i++)
 384         {
 385           opts->name[i] = options[i].name;
 386           opts->description[i] = _(options[i].description);
 387         }
 388       /* The array we return must be NULL terminated.  */
 389       opts->name[i] = NULL;
 390       opts->description[i] = NULL;
 391     }
 392
 393   return opts;
 394 }
 395
 396 void
 397 print_s390_disassembler_options (FILE *stream)
 398 {
 399   unsigned int i, max_len = 0;
 400   fprintf (stream, _("\n\
 401 The following S/390 specific disassembler options are supported for use\n\
 402 with the -M switch (multiple options should be separated by commas):\n"));
 403
 404   for (i = 0; i < ARRAY_SIZE (options); i++)
 405     {
 406       unsigned int len = strlen (options[i].name);
 407       if (max_len < len)
 408         max_len = len;
 409     }
 410
 411   for (i = 0, max_len++; i < ARRAY_SIZE (options); i++)
 412     fprintf (stream, "  %s%*c %s\n",
 413              options[i].name,
 414              (int)(max_len - strlen (options[i].name)), ' ',
 415              _(options[i].description));
 416 }