opcodes/s390-dis.c

   1 /* s390-dis.c -- Disassemble S390 instructions
   2    Copyright (C) 2000-2016 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
  29 static int init_flag = 0;
  30 static int opc_index[256];
  31 static int current_arch_mask = 0;
  32
  33 /* Set up index table for first opcode byte.  */
  34
  35 static void
  36 init_disasm (struct disassemble_info *info)
  37 {
  38   int i;
  39   const char *p;
  40
  41   memset (opc_index, 0, sizeof (opc_index));
  42
  43   /* Reverse order, such that each opc_index ends up pointing to the
  44      first matching entry instead of the last.  */
  45   for (i = s390_num_opcodes; i--; )
  46     opc_index[s390_opcodes[i].opcode[0]] = i;
  47
  48   for (p = info->disassembler_options; p != NULL; )
  49     {
  50       if (CONST_STRNEQ (p, "esa"))
  51         current_arch_mask = 1 << S390_OPCODE_ESA;
  52       else if (CONST_STRNEQ (p, "zarch"))
  53         current_arch_mask = 1 << S390_OPCODE_ZARCH;
  54       else
  55         fprintf (stderr, "Unknown S/390 disassembler option: %s\n", p);
  56
  57       p = strchr (p, ',');
  58       if (p != NULL)
  59         p++;
  60     }
  61
  62   if (!current_arch_mask)
  63     current_arch_mask = 1 << S390_OPCODE_ZARCH;
  64
  65   init_flag = 1;
  66 }
  67
  68 /* Derive the length of an instruction from its first byte.  */
  69
  70 static inline int
  71 s390_insn_length (const bfd_byte *buffer)
  72 {
  73   /* 00xxxxxx -> 2, 01xxxxxx/10xxxxxx -> 4, 11xxxxxx -> 6.  */
  74   return ((buffer[0] >> 6) + 3) & ~1U;
  75 }
  76
  77 /* Match the instruction in BUFFER against the given OPCODE, excluding
  78    the first byte.  */
  79
  80 static inline int
  81 s390_insn_matches_opcode (const bfd_byte *buffer,
  82                           const struct s390_opcode *opcode)
  83 {
  84   return (buffer[1] & opcode->mask[1]) == opcode->opcode[1]
  85     && (buffer[2] & opcode->mask[2]) == opcode->opcode[2]
  86     && (buffer[3] & opcode->mask[3]) == opcode->opcode[3]
  87     && (buffer[4] & opcode->mask[4]) == opcode->opcode[4]
  88     && (buffer[5] & opcode->mask[5]) == opcode->opcode[5];
  89 }
  90
  91 union operand_value
  92 {
  93   int i;
  94   unsigned int u;
  95 };
  96
  97 /* Extracts an operand value from an instruction.  */
  98 /* We do not perform the shift operation for larl-type address
  99    operands here since that would lead to an overflow of the 32 bit
 100    integer value.  Instead the shift operation is done when printing
 101    the operand.  */
 102
 103 static inline union operand_value
 104 s390_extract_operand (const bfd_byte *insn,
 105                       const struct s390_operand *operand)
 106 {
 107   union operand_value ret;
 108   unsigned int val;
 109   int bits;
 110   const bfd_byte *orig_insn = insn;
 111
 112   /* Extract fragments of the operand byte for byte.  */
 113   insn += operand->shift / 8;
 114   bits = (operand->shift & 7) + operand->bits;
 115   val = 0;
 116   do
 117     {
 118       val <<= 8;
 119       val |= (unsigned int) *insn++;
 120       bits -= 8;
 121     }
 122   while (bits > 0);
 123   val >>= -bits;
 124   val &= ((1U << (operand->bits - 1)) << 1) - 1;
 125
 126   /* Check for special long displacement case.  */
 127   if (operand->bits == 20 && operand->shift == 20)
 128     val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;
 129
 130   /* Sign extend value if the operand is signed or pc relative.  Avoid
 131      integer overflows.  */
 132   if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
 133     {
 134       unsigned int m = 1U << (operand->bits - 1);
 135
 136       if (val >= m)
 137         ret.i = (int) (val - m) - 1 - (int) (m - 1U);
 138       else
 139         ret.i = (int) val;
 140     }
 141   else if (operand->flags & S390_OPERAND_LENGTH)
 142     /* Length x in an instruction has real length x + 1.  */
 143     ret.u = val + 1;
 144
 145   else if (operand->flags & S390_OPERAND_VR)
 146     {
 147       /* Extract the extra bits for a vector register operand stored
 148          in the RXB field.  */
 149       unsigned vr = operand->shift == 32 ? 3
 150         : (unsigned) operand->shift / 4 - 2;
 151
 152       ret.u = val | ((orig_insn[4] & (1 << (3 - vr))) << (vr + 1));
 153     }
 154   else
 155     ret.u = val;
 156
 157   return ret;
 158 }
 159
 160 /* Print the S390 instruction in BUFFER, assuming that it matches the
 161    given OPCODE.  */
 162
 163 static void
 164 s390_print_insn_with_opcode (bfd_vma memaddr,
 165                              struct disassemble_info *info,
 166                              const bfd_byte *buffer,
 167                              const struct s390_opcode *opcode)
 168 {
 169   const unsigned char *opindex;
 170   char separator;
 171
 172   /* Mnemonic.  */
 173   info->fprintf_func (info->stream, "%s", opcode->name);
 174
 175   /* Operands.  */
 176   separator = '\t';
 177   for (opindex = opcode->operands; *opindex != 0; opindex++)
 178     {
 179       const struct s390_operand *operand = s390_operands + *opindex;
 180       union operand_value val = s390_extract_operand (buffer, operand);
 181       unsigned long flags = operand->flags;
 182
 183       if ((flags & S390_OPERAND_INDEX) && val.u == 0)
 184         continue;
 185       if ((flags & S390_OPERAND_BASE) &&
 186           val.u == 0 && separator == '(')
 187         {
 188           separator = ',';
 189           continue;
 190         }
 191
 192       /* For instructions with a last optional operand don't print it
 193          if zero.  */
 194       if ((opcode->flags & S390_INSTR_FLAG_OPTPARM)
 195           && val.u == 0
 196           && opindex[1] == 0)
 197         break;
 198
 199       if (flags & S390_OPERAND_GPR)
 200         info->fprintf_func (info->stream, "%c%%r%u", separator, val.u);
 201       else if (flags & S390_OPERAND_FPR)
 202         info->fprintf_func (info->stream, "%c%%f%u", separator, val.u);
 203       else if (flags & S390_OPERAND_VR)
 204         info->fprintf_func (info->stream, "%c%%v%i", separator, val.u);
 205       else if (flags & S390_OPERAND_AR)
 206         info->fprintf_func (info->stream, "%c%%a%u", separator, val.u);
 207       else if (flags & S390_OPERAND_CR)
 208         info->fprintf_func (info->stream, "%c%%c%u", separator, val.u);
 209       else if (flags & S390_OPERAND_PCREL)
 210         {
 211           info->fprintf_func (info->stream, "%c", separator);
 212           info->print_address_func (memaddr + val.i + val.i, info);
 213         }
 214       else if (flags & S390_OPERAND_SIGNED)
 215         info->fprintf_func (info->stream, "%c%i", separator, val.i);
 216       else
 217         {
 218           if (flags & S390_OPERAND_OR1)
 219             val.u &= ~1;
 220           if (flags & S390_OPERAND_OR2)
 221             val.u &= ~2;
 222           if (flags & S390_OPERAND_OR8)
 223             val.u &= ~8;
 224
 225           if ((opcode->flags & S390_INSTR_FLAG_OPTPARM)
 226               && val.u == 0
 227               && opindex[1] == 0)
 228             break;
 229           info->fprintf_func (info->stream, "%c%u", separator, val.u);
 230         }
 231
 232       if (flags & S390_OPERAND_DISP)
 233         separator = '(';
 234       else if (flags & S390_OPERAND_BASE)
 235         {
 236           info->fprintf_func (info->stream, ")");
 237           separator = ',';
 238         }
 239       else
 240         separator = ',';
 241     }
 242 }
 243
 244 /* Check whether opcode A's mask is more specific than that of B.  */
 245
 246 static int
 247 opcode_mask_more_specific (const struct s390_opcode *a,
 248                            const struct s390_opcode *b)
 249 {
 250   return (((int) a->mask[0] + a->mask[1] + a->mask[2]
 251            + a->mask[3] + a->mask[4] + a->mask[5])
 252           > ((int) b->mask[0] + b->mask[1] + b->mask[2]
 253              + b->mask[3] + b->mask[4] + b->mask[5]));
 254 }
 255
 256 /* Print a S390 instruction.  */
 257
 258 int
 259 print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
 260 {
 261   bfd_byte buffer[6];
 262   const struct s390_opcode *opcode = NULL;
 263   unsigned int value;
 264   int status, opsize, bufsize;
 265
 266   if (init_flag == 0)
 267     init_disasm (info);
 268
 269   /* The output looks better if we put 6 bytes on a line.  */
 270   info->bytes_per_line = 6;
 271
 272   /* Every S390 instruction is max 6 bytes long.  */
 273   memset (buffer, 0, 6);
 274   status = info->read_memory_func (memaddr, buffer, 6, info);
 275   if (status != 0)
 276     {
 277       for (bufsize = 0; bufsize < 6; bufsize++)
 278         if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
 279           break;
 280       if (bufsize <= 0)
 281         {
 282           info->memory_error_func (status, memaddr, info);
 283           return -1;
 284         }
 285       opsize = s390_insn_length (buffer);
 286       status = opsize > bufsize;
 287     }
 288   else
 289     {
 290       bufsize = 6;
 291       opsize = s390_insn_length (buffer);
 292     }
 293
 294   if (status == 0)
 295     {
 296       const struct s390_opcode *op;
 297
 298       /* Find the "best match" in the opcode table.  */
 299       for (op = s390_opcodes + opc_index[buffer[0]];
 300            op != s390_opcodes + s390_num_opcodes
 301              && op->opcode[0] == buffer[0];
 302            op++)
 303         {
 304           if ((op->modes & current_arch_mask)
 305               && s390_insn_matches_opcode (buffer, op)
 306               && (opcode == NULL
 307                   || opcode_mask_more_specific (op, opcode)))
 308             opcode = op;
 309         }
 310     }
 311
 312   if (opcode != NULL)
 313     {
 314       /* The instruction is valid.  Print it and return its size.  */
 315       s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
 316       return opsize;
 317     }
 318
 319   /* Fall back to hex print.  */
 320   if (bufsize >= 4)
 321     {
 322       value = (unsigned int) buffer[0];
 323       value = (value << 8) + (unsigned int) buffer[1];
 324       value = (value << 8) + (unsigned int) buffer[2];
 325       value = (value << 8) + (unsigned int) buffer[3];
 326       info->fprintf_func (info->stream, ".long\t0x%08x", value);
 327       return 4;
 328     }
 329   else if (bufsize >= 2)
 330     {
 331       value = (unsigned int) buffer[0];
 332       value = (value << 8) + (unsigned int) buffer[1];
 333       info->fprintf_func (info->stream, ".short\t0x%04x", value);
 334       return 2;
 335     }
 336   else
 337     {
 338       value = (unsigned int) buffer[0];
 339       info->fprintf_func (info->stream, ".byte\t0x%02x", value);
 340       return 1;
 341     }
 342 }
 343
 344 void
 345 print_s390_disassembler_options (FILE *stream)
 346 {
 347   fprintf (stream, _("\n\
 348 The following S/390 specific disassembler options are supported for use\n\
 349 with the -M switch (multiple options should be separated by commas):\n"));
 350
 351   fprintf (stream, _("  esa         Disassemble in ESA architecture mode\n"));
 352   fprintf (stream, _("  zarch       Disassemble in z/Architecture mode\n"));
 353 }