opcodes/s390-dis.c

   1 /* s390-dis.c -- Disassemble S390 instructions
   2    Copyright (C) 2000-2015 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
 111   /* Extract fragments of the operand byte for byte.  */
 112   insn += operand->shift / 8;
 113   bits = (operand->shift & 7) + operand->bits;
 114   val = 0;
 115   do
 116     {
 117       val <<= 8;
 118       val |= (unsigned int) *insn++;
 119       bits -= 8;
 120     }
 121   while (bits > 0);
 122   val >>= -bits;
 123   val &= ((1U << (operand->bits - 1)) << 1) - 1;
 124
 125   /* Check for special long displacement case.  */
 126   if (operand->bits == 20 && operand->shift == 20)
 127     val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;
 128
 129   /* Sign extend value if the operand is signed or pc relative.  Avoid
 130      integer overflows.  */
 131   if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
 132     {
 133       unsigned int m = 1U << (operand->bits - 1);
 134
 135       if (val >= m)
 136         ret.i = (int) (val - m) - 1 - (int) (m - 1U);
 137       else
 138         ret.i = (int) val;
 139     }
 140   else if (operand->flags & S390_OPERAND_LENGTH)
 141     /* Length x in an instruction has real length x + 1.  */
 142     ret.u = val + 1;
 143   else
 144     ret.u = val;
 145
 146   return ret;
 147 }
 148
 149 /* Print the S390 instruction in BUFFER, assuming that it matches the
 150    given OPCODE.  */
 151
 152 static void
 153 s390_print_insn_with_opcode (bfd_vma memaddr,
 154                              struct disassemble_info *info,
 155                              const bfd_byte *buffer,
 156                              const struct s390_opcode *opcode)
 157 {
 158   const unsigned char *opindex;
 159   char separator;
 160
 161   /* Mnemonic.  */
 162   info->fprintf_func (info->stream, "%s", opcode->name);
 163
 164   /* Operands.  */
 165   separator = '\t';
 166   for (opindex = opcode->operands; *opindex != 0; opindex++)
 167     {
 168       const struct s390_operand *operand = s390_operands + *opindex;
 169       union operand_value val = s390_extract_operand (buffer, operand);
 170       unsigned long flags = operand->flags;
 171
 172       if ((flags & S390_OPERAND_INDEX) && val.u == 0)
 173         continue;
 174       if ((flags & S390_OPERAND_BASE) &&
 175           val.u == 0 && separator == '(')
 176         {
 177           separator = ',';
 178           continue;
 179         }
 180
 181       info->fprintf_func (info->stream, "%c", separator);
 182
 183       if (flags & S390_OPERAND_GPR)
 184         info->fprintf_func (info->stream, "%%r%u", val.u);
 185       else if (flags & S390_OPERAND_FPR)
 186         info->fprintf_func (info->stream, "%%f%u", val.u);
 187       else if (flags & S390_OPERAND_AR)
 188         info->fprintf_func (info->stream, "%%a%u", val.u);
 189       else if (flags & S390_OPERAND_CR)
 190         info->fprintf_func (info->stream, "%%c%u", val.u);
 191       else if (flags & S390_OPERAND_PCREL)
 192         info->print_address_func (memaddr + val.i + val.i, info);
 193       else if (flags & S390_OPERAND_SIGNED)
 194         info->fprintf_func (info->stream, "%i", val.i);
 195       else
 196         info->fprintf_func (info->stream, "%u", val.u);
 197
 198       if (flags & S390_OPERAND_DISP)
 199         separator = '(';
 200       else if (flags & S390_OPERAND_BASE)
 201         {
 202           info->fprintf_func (info->stream, ")");
 203           separator = ',';
 204         }
 205       else
 206         separator = ',';
 207     }
 208 }
 209
 210 /* Check whether opcode A's mask is more specific than that of B.  */
 211
 212 static int
 213 opcode_mask_more_specific (const struct s390_opcode *a,
 214                            const struct s390_opcode *b)
 215 {
 216   return (((int) a->mask[0] + a->mask[1] + a->mask[2]
 217            + a->mask[3] + a->mask[4] + a->mask[5])
 218           > ((int) b->mask[0] + b->mask[1] + b->mask[2]
 219              + b->mask[3] + b->mask[4] + b->mask[5]));
 220 }
 221
 222 /* Print a S390 instruction.  */
 223
 224 int
 225 print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
 226 {
 227   bfd_byte buffer[6];
 228   const struct s390_opcode *opcode = NULL;
 229   unsigned int value;
 230   int status, opsize, bufsize;
 231
 232   if (init_flag == 0)
 233     init_disasm (info);
 234
 235   /* The output looks better if we put 6 bytes on a line.  */
 236   info->bytes_per_line = 6;
 237
 238   /* Every S390 instruction is max 6 bytes long.  */
 239   memset (buffer, 0, 6);
 240   status = info->read_memory_func (memaddr, buffer, 6, info);
 241   if (status != 0)
 242     {
 243       for (bufsize = 0; bufsize < 6; bufsize++)
 244         if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
 245           break;
 246       if (bufsize <= 0)
 247         {
 248           info->memory_error_func (status, memaddr, info);
 249           return -1;
 250         }
 251       opsize = s390_insn_length (buffer);
 252       status = opsize > bufsize;
 253     }
 254   else
 255     {
 256       bufsize = 6;
 257       opsize = s390_insn_length (buffer);
 258     }
 259
 260   if (status == 0)
 261     {
 262       const struct s390_opcode *op;
 263
 264       /* Find the "best match" in the opcode table.  */
 265       for (op = s390_opcodes + opc_index[buffer[0]];
 266            op != s390_opcodes + s390_num_opcodes
 267              && op->opcode[0] == buffer[0];
 268            op++)
 269         {
 270           if ((op->modes & current_arch_mask)
 271               && s390_insn_matches_opcode (buffer, op)
 272               && (opcode == NULL
 273                   || opcode_mask_more_specific (op, opcode)))
 274             opcode = op;
 275         }
 276     }
 277
 278   if (opcode != NULL)
 279     {
 280       /* The instruction is valid.  Print it and return its size.  */
 281       s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
 282       return opsize;
 283     }
 284
 285   /* Fall back to hex print.  */
 286   if (bufsize >= 4)
 287     {
 288       value = (unsigned int) buffer[0];
 289       value = (value << 8) + (unsigned int) buffer[1];
 290       value = (value << 8) + (unsigned int) buffer[2];
 291       value = (value << 8) + (unsigned int) buffer[3];
 292       info->fprintf_func (info->stream, ".long\t0x%08x", value);
 293       return 4;
 294     }
 295   else if (bufsize >= 2)
 296     {
 297       value = (unsigned int) buffer[0];
 298       value = (value << 8) + (unsigned int) buffer[1];
 299       info->fprintf_func (info->stream, ".short\t0x%04x", value);
 300       return 2;
 301     }
 302   else
 303     {
 304       value = (unsigned int) buffer[0];
 305       info->fprintf_func (info->stream, ".byte\t0x%02x", value);
 306       return 1;
 307     }
 308 }
 309
 310 void
 311 print_s390_disassembler_options (FILE *stream)
 312 {
 313   fprintf (stream, _("\n\
 314 The following S/390 specific disassembler options are supported for use\n\
 315 with the -M switch (multiple options should be separated by commas):\n"));
 316
 317   fprintf (stream, _("  esa         Disassemble in ESA architecture mode\n"));
 318   fprintf (stream, _("  zarch       Disassemble in z/Architecture mode\n"));
 319 }