1 /* s390-dis.c -- Disassemble S390 instructions
2 Copyright (C) 2000-2023 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 (startswith (p, "esa"))
69 current_arch_mask = 1 << S390_OPCODE_ESA;
70 else if (startswith (p, "zarch"))
71 current_arch_mask = 1 << S390_OPCODE_ZARCH;
72 else if (startswith (p, "insnlength"))
73 option_use_insn_len_bits_p = 1;
74 else
75 /* xgettext:c-format */
76 opcodes_error_handler (_("unknown S/390 disassembler option: %s"), p);
77
78 p = strchr (p, ',');
79 if (p != NULL)
80 p++;
81 }
82 }
83
84 /* Derive the length of an instruction from its first byte. */
85
86 static inline int
87 s390_insn_length (const bfd_byte *buffer)
88 {
89 /* 00xxxxxx -> 2, 01xxxxxx/10xxxxxx -> 4, 11xxxxxx -> 6. */
90 return ((buffer[0] >> 6) + 3) & ~1U;
91 }
92
93 /* Match the instruction in BUFFER against the given OPCODE, excluding
94 the first byte. */
95
96 static inline int
97 s390_insn_matches_opcode (const bfd_byte *buffer,
98 const struct s390_opcode *opcode)
99 {
100 return (buffer[1] & opcode->mask[1]) == opcode->opcode[1]
101 && (buffer[2] & opcode->mask[2]) == opcode->opcode[2]
102 && (buffer[3] & opcode->mask[3]) == opcode->opcode[3]
103 && (buffer[4] & opcode->mask[4]) == opcode->opcode[4]
104 && (buffer[5] & opcode->mask[5]) == opcode->opcode[5];
105 }
106
107 union operand_value
108 {
109 int i;
110 unsigned int u;
111 };
112
113 /* Extracts an operand value from an instruction. */
114 /* We do not perform the shift operation for larl-type address
115 operands here since that would lead to an overflow of the 32 bit
116 integer value. Instead the shift operation is done when printing
117 the operand. */
118
119 static inline union operand_value
120 s390_extract_operand (const bfd_byte *insn,
121 const struct s390_operand *operand)
122 {
123 union operand_value ret;
124 unsigned int val;
125 int bits;
126 const bfd_byte *orig_insn = insn;
127
128 /* Extract fragments of the operand byte for byte. */
129 insn += operand->shift / 8;
130 bits = (operand->shift & 7) + operand->bits;
131 val = 0;
132 do
133 {
134 val <<= 8;
135 val |= (unsigned int) *insn++;
136 bits -= 8;
137 }
138 while (bits > 0);
139 val >>= -bits;
140 val &= ((1U << (operand->bits - 1)) << 1) - 1;
141
142 /* Check for special long displacement case. */
143 if (operand->bits == 20 && operand->shift == 20)
144 val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;
145
146 /* Sign extend value if the operand is signed or pc relative. Avoid
147 integer overflows. */
148 if (operand->flags & (S390_OPERAND_SIGNED | S390_OPERAND_PCREL))
149 {
150 unsigned int m = 1U << (operand->bits - 1);
151
152 if (val >= m)
153 ret.i = (int) (val - m) - 1 - (int) (m - 1U);
154 else
155 ret.i = (int) val;
156 }
157 else if (operand->flags & S390_OPERAND_LENGTH)
158 /* Length x in an instruction has real length x + 1. */
159 ret.u = val + 1;
160
161 else if (operand->flags & S390_OPERAND_VR)
162 {
163 /* Extract the extra bits for a vector register operand stored
164 in the RXB field. */
165 unsigned vr = operand->shift == 32 ? 3
166 : (unsigned) operand->shift / 4 - 2;
167
168 ret.u = val | ((orig_insn[4] & (1 << (3 - vr))) << (vr + 1));
169 }
170 else
171 ret.u = val;
172
173 return ret;
174 }
175
176 /* Print the S390 instruction in BUFFER, assuming that it matches the
177 given OPCODE. */
178
179 static void
180 s390_print_insn_with_opcode (bfd_vma memaddr,
181 struct disassemble_info *info,
182 const bfd_byte *buffer,
183 const struct s390_opcode *opcode)
184 {
185 const unsigned char *opindex;
186 char separator;
187
188 /* Mnemonic. */
189 info->fprintf_styled_func (info->stream, dis_style_mnemonic,
190 "%s", opcode->name);
191
192 /* Operands. */
193 separator = '\t';
194 for (opindex = opcode->operands; *opindex != 0; opindex++)
195 {
196 const struct s390_operand *operand = s390_operands + *opindex;
197 union operand_value val = s390_extract_operand (buffer, operand);
198 unsigned long flags = operand->flags;
199
200 if ((flags & S390_OPERAND_INDEX) && val.u == 0)
201 continue;
202 if ((flags & S390_OPERAND_BASE) &&
203 val.u == 0 && separator == '(')
204 {
205 separator = ',';
206 continue;
207 }
208
209 /* For instructions with a last optional operand don't print it
210 if zero. */
211 if ((opcode->flags & (S390_INSTR_FLAG_OPTPARM | S390_INSTR_FLAG_OPTPARM2))
212 && val.u == 0
213 && opindex[1] == 0)
214 break;
215
216 if ((opcode->flags & S390_INSTR_FLAG_OPTPARM2)
217 && val.u == 0 && opindex[1] != 0 && opindex[2] == 0)
218 {
219 union operand_value next_op_val =
220 s390_extract_operand (buffer, s390_operands + opindex[1]);
221 if (next_op_val.u == 0)
222 break;
223 }
224
225 if (flags & S390_OPERAND_GPR)
226 {
227 info->fprintf_styled_func (info->stream, dis_style_text,
228 "%c", separator);
229 info->fprintf_styled_func (info->stream, dis_style_register,
230 "%%r%u", val.u);
231 }
232 else if (flags & S390_OPERAND_FPR)
233 {
234 info->fprintf_styled_func (info->stream, dis_style_text,
235 "%c", separator);
236 info->fprintf_styled_func (info->stream, dis_style_register,
237 "%%f%u", val.u);
238 }
239 else if (flags & S390_OPERAND_VR)
240 {
241 info->fprintf_styled_func (info->stream, dis_style_text,
242 "%c", separator);
243 info->fprintf_styled_func (info->stream, dis_style_register,
244 "%%v%i", val.u);
245 }
246 else if (flags & S390_OPERAND_AR)
247 {
248 info->fprintf_styled_func (info->stream, dis_style_text,
249 "%c", separator);
250 info->fprintf_styled_func (info->stream, dis_style_register,
251 "%%a%u", val.u);
252 }
253 else if (flags & S390_OPERAND_CR)
254 {
255 info->fprintf_styled_func (info->stream, dis_style_text,
256 "%c", separator);
257 info->fprintf_styled_func (info->stream, dis_style_register,
258 "%%c%u", val.u);
259 }
260 else if (flags & S390_OPERAND_PCREL)
261 {
262 info->fprintf_styled_func (info->stream, dis_style_text,
263 "%c", separator);
264 info->print_address_func (memaddr + val.i + val.i, info);
265 }
266 else if (flags & S390_OPERAND_SIGNED)
267 {
268 enum disassembler_style style;
269
270 info->fprintf_styled_func (info->stream, dis_style_text,
271 "%c", separator);
272 style = ((flags & S390_OPERAND_DISP)
273 ? dis_style_address_offset : dis_style_immediate);
274 info->fprintf_styled_func (info->stream, style, "%i", val.i);
275 }
276 else
277 {
278 enum disassembler_style style;
279
280 if (flags & S390_OPERAND_OR1)
281 val.u &= ~1;
282 if (flags & S390_OPERAND_OR2)
283 val.u &= ~2;
284 if (flags & S390_OPERAND_OR8)
285 val.u &= ~8;
286
287 if ((opcode->flags & S390_INSTR_FLAG_OPTPARM)
288 && val.u == 0
289 && opindex[1] == 0)
290 break;
291 info->fprintf_styled_func (info->stream, dis_style_text,
292 "%c", separator);
293 style = ((flags & S390_OPERAND_DISP)
294 ? dis_style_address_offset : dis_style_immediate);
295 info->fprintf_styled_func (info->stream, style, "%u", val.u);
296 }
297
298 if (flags & S390_OPERAND_DISP)
299 separator = '(';
300 else if (flags & S390_OPERAND_BASE)
301 {
302 info->fprintf_styled_func (info->stream, dis_style_text, ")");
303 separator = ',';
304 }
305 else
306 separator = ',';
307 }
308 }
309
310 /* Check whether opcode A's mask is more specific than that of B. */
311
312 static int
313 opcode_mask_more_specific (const struct s390_opcode *a,
314 const struct s390_opcode *b)
315 {
316 return (((int) a->mask[0] + a->mask[1] + a->mask[2]
317 + a->mask[3] + a->mask[4] + a->mask[5])
318 > ((int) b->mask[0] + b->mask[1] + b->mask[2]
319 + b->mask[3] + b->mask[4] + b->mask[5]));
320 }
321
322 /* Print a S390 instruction. */
323
324 int
325 print_insn_s390 (bfd_vma memaddr, struct disassemble_info *info)
326 {
327 bfd_byte buffer[6];
328 const struct s390_opcode *opcode = NULL;
329 unsigned int value;
330 int status, opsize, bufsize, bytes_to_dump, i;
331
332 /* The output looks better if we put 6 bytes on a line. */
333 info->bytes_per_line = 6;
334
335 /* Every S390 instruction is max 6 bytes long. */
336 memset (buffer, 0, 6);
337 status = info->read_memory_func (memaddr, buffer, 6, info);
338 if (status != 0)
339 {
340 for (bufsize = 0; bufsize < 6; bufsize++)
341 if (info->read_memory_func (memaddr, buffer, bufsize + 1, info) != 0)
342 break;
343 if (bufsize <= 0)
344 {
345 info->memory_error_func (status, memaddr, info);
346 return -1;
347 }
348 opsize = s390_insn_length (buffer);
349 status = opsize > bufsize;
350 }
351 else
352 {
353 bufsize = 6;
354 opsize = s390_insn_length (buffer);
355 }
356
357 if (status == 0)
358 {
359 const struct s390_opcode *op;
360
361 /* Find the "best match" in the opcode table. */
362 for (op = s390_opcodes + opc_index[buffer[0]];
363 op != s390_opcodes + s390_num_opcodes
364 && op->opcode[0] == buffer[0];
365 op++)
366 {
367 if ((op->modes & current_arch_mask)
368 && s390_insn_matches_opcode (buffer, op)
369 && (opcode == NULL
370 || opcode_mask_more_specific (op, opcode)))
371 opcode = op;
372 }
373
374 if (opcode != NULL)
375 {
376 /* The instruction is valid. Print it and return its size. */
377 s390_print_insn_with_opcode (memaddr, info, buffer, opcode);
378 return opsize;
379 }
380 }
381
382 /* For code sections it makes sense to skip unknown instructions
383 according to their length bits. */
384 if (status == 0
385 && option_use_insn_len_bits_p
386 && info->section != NULL
387 && (info->section->flags & SEC_CODE))
388 bytes_to_dump = opsize;
389 else
390 /* By default unknown instructions are printed as .long's/.short'
391 depending on how many bytes are available. */
392 bytes_to_dump = bufsize >= 4 ? 4 : bufsize;
393
394 if (bytes_to_dump == 0)
395 return 0;
396
397 /* Fall back to hex print. */
398 switch (bytes_to_dump)
399 {
400 case 4:
401 value = (unsigned int) buffer[0];
402 value = (value << 8) + (unsigned int) buffer[1];
403 value = (value << 8) + (unsigned int) buffer[2];
404 value = (value << 8) + (unsigned int) buffer[3];
405 info->fprintf_styled_func (info->stream, dis_style_assembler_directive,
406 ".long");
407 info->fprintf_styled_func (info->stream, dis_style_text,
408 "\t");
409 info->fprintf_styled_func (info->stream, dis_style_immediate,
410 "0x%08x", value);
411 return 4;
412 case 2:
413 value = (unsigned int) buffer[0];
414 value = (value << 8) + (unsigned int) buffer[1];
415 info->fprintf_styled_func (info->stream, dis_style_assembler_directive,
416 ".short");
417 info->fprintf_styled_func (info->stream, dis_style_text,
418 "\t");
419 info->fprintf_styled_func (info->stream, dis_style_immediate,
420 "0x%04x", value);
421 return 2;
422 default:
423 info->fprintf_styled_func (info->stream, dis_style_assembler_directive,
424 ".byte");
425 info->fprintf_styled_func (info->stream, dis_style_text,
426 "\t");
427 info->fprintf_styled_func (info->stream, dis_style_immediate,
428 "0x%02x", (unsigned int) buffer[0]);
429 for (i = 1; i < bytes_to_dump; i++)
430 info->fprintf_styled_func (info->stream, dis_style_immediate,
431 "0x%02x", (unsigned int) buffer[i]);
432 return bytes_to_dump;
433 }
434 return 0;
435 }
436
437 const disasm_options_and_args_t *
438 disassembler_options_s390 (void)
439 {
440 static disasm_options_and_args_t *opts_and_args;
441
442 if (opts_and_args == NULL)
443 {
444 size_t i, num_options = ARRAY_SIZE (options);
445 disasm_options_t *opts;
446
447 opts_and_args = XNEW (disasm_options_and_args_t);
448 opts_and_args->args = NULL;
449
450 opts = &opts_and_args->options;
451 opts->name = XNEWVEC (const char *, num_options + 1);
452 opts->description = XNEWVEC (const char *, num_options + 1);
453 opts->arg = NULL;
454 for (i = 0; i < num_options; i++)
455 {
456 opts->name[i] = options[i].name;
457 opts->description[i] = _(options[i].description);
458 }
459 /* The array we return must be NULL terminated. */
460 opts->name[i] = NULL;
461 opts->description[i] = NULL;
462 }
463
464 return opts_and_args;
465 }
466
467 void
468 print_s390_disassembler_options (FILE *stream)
469 {
470 unsigned int i, max_len = 0;
471 fprintf (stream, _("\n\
472 The following S/390 specific disassembler options are supported for use\n\
473 with the -M switch (multiple options should be separated by commas):\n"));
474
475 for (i = 0; i < ARRAY_SIZE (options); i++)
476 {
477 unsigned int len = strlen (options[i].name);
478 if (max_len < len)
479 max_len = len;
480 }
481
482 for (i = 0, max_len++; i < ARRAY_SIZE (options); i++)
483 fprintf (stream, " %s%*c %s\n",
484 options[i].name,
485 (int)(max_len - strlen (options[i].name)), ' ',
486 _(options[i].description));
487 }