aboutsummaryrefslogtreecommitdiff
path: root/opcodes/wasm32-dis.c
blob: d6f1697542493f53079c44aa684bbb2505a8c9d4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
/* Opcode printing code for the WebAssembly target
   Copyright (C) 2017-2018 Free Software Foundation, Inc.

   This file is part of libopcodes.

   This library is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   It is distributed in the hope that it will be useful, but WITHOUT
   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
   License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
   MA 02110-1301, USA.  */

#include "sysdep.h"
#include "disassemble.h"
#include "opintl.h"
#include "safe-ctype.h"
#include "floatformat.h"
#include "libiberty.h"
#include "elf-bfd.h"
#include "elf/internal.h"
#include "elf/wasm32.h"
#include <stdint.h>

/* Type names for blocks and signatures.  */
#define BLOCK_TYPE_NONE              0x40
#define BLOCK_TYPE_I32               0x7f
#define BLOCK_TYPE_I64               0x7e
#define BLOCK_TYPE_F32               0x7d
#define BLOCK_TYPE_F64               0x7c

enum wasm_class
{
  wasm_typed,
  wasm_special,
  wasm_break,
  wasm_break_if,
  wasm_break_table,
  wasm_return,
  wasm_call,
  wasm_call_import,
  wasm_call_indirect,
  wasm_get_local,
  wasm_set_local,
  wasm_tee_local,
  wasm_drop,
  wasm_constant_i32,
  wasm_constant_i64,
  wasm_constant_f32,
  wasm_constant_f64,
  wasm_unary,
  wasm_binary,
  wasm_conv,
  wasm_load,
  wasm_store,
  wasm_select,
  wasm_relational,
  wasm_eqz,
  wasm_current_memory,
  wasm_grow_memory,
  wasm_signature
};

struct wasm32_private_data
{
  bfd_boolean print_registers;
  bfd_boolean print_well_known_globals;

  /* Limit valid symbols to those with a given prefix.  */
  const char *section_prefix;
};

typedef struct
{
  const char *name;
  const char *description;
} wasm32_options_t;

static const wasm32_options_t options[] =
{
  { "registers", N_("Disassemble \"register\" names") },
  { "globals",   N_("Name well-known globals") },
};

#define WASM_OPCODE(opcode, name, intype, outtype, clas, signedness)     \
  { name, wasm_ ## clas, opcode },

struct wasm32_opcode_s
{
  const char *name;
  enum wasm_class clas;
  unsigned char opcode;
} wasm32_opcodes[] =
{
#include "opcode/wasm.h"
  { NULL, 0, 0 }
};

/* Parse the disassembler options in OPTS and initialize INFO.  */

static void
parse_wasm32_disassembler_options (struct disassemble_info *info,
                                   const char *opts)
{
  struct wasm32_private_data *private = info->private_data;

  while (opts != NULL)
    {
      if (CONST_STRNEQ (opts, "registers"))
        private->print_registers = TRUE;
      else if (CONST_STRNEQ (opts, "globals"))
        private->print_well_known_globals = TRUE;

      opts = strchr (opts, ',');
      if (opts)
        opts++;
    }
}

/* Check whether SYM is valid.  Special-case absolute symbols, which
   are unhelpful to print, and arguments to a "call" insn, which we
   want to be in a section matching a given prefix.  */

static bfd_boolean
wasm32_symbol_is_valid (asymbol *sym,
                        struct disassemble_info *info)
{
  struct wasm32_private_data *private_data = info->private_data;

  if (sym == NULL)
    return FALSE;

  if (strcmp(sym->section->name, "*ABS*") == 0)
    return FALSE;

  if (private_data && private_data->section_prefix != NULL
      && strncmp (sym->section->name, private_data->section_prefix,
                  strlen (private_data->section_prefix)))
    return FALSE;

  return TRUE;
}

/* Initialize the disassembler structures for INFO.  */

void
disassemble_init_wasm32 (struct disassemble_info *info)
{
  if (info->private_data == NULL)
    {
      static struct wasm32_private_data private;

      private.print_registers = FALSE;
      private.print_well_known_globals = FALSE;
      private.section_prefix = NULL;

      info->private_data = &private;
    }

  if (info->disassembler_options)
    {
      parse_wasm32_disassembler_options (info, info->disassembler_options);

      info->disassembler_options = NULL;
    }

  info->symbol_is_valid = wasm32_symbol_is_valid;
}

/* Read an LEB128-encoded integer from INFO at address PC, reading one
   byte at a time.  Set ERROR_RETURN if no complete integer could be
   read, LENGTH_RETURN to the number oof bytes read (including bytes
   in incomplete numbers).  SIGN means interpret the number as
   SLEB128.  Unfortunately, this is a duplicate of wasm-module.c's
   wasm_read_leb128 ().  */

static uint64_t
wasm_read_leb128 (bfd_vma                   pc,
                  struct disassemble_info * info,
                  bfd_boolean *             error_return,
                  unsigned int *            length_return,
                  bfd_boolean               sign)
{
  uint64_t result = 0;
  unsigned int num_read = 0;
  unsigned int shift = 0;
  unsigned char byte = 0;
  bfd_boolean success = FALSE;

  while (info->read_memory_func (pc + num_read, &byte, 1, info) == 0)
    {
      num_read++;

      result |= ((bfd_vma) (byte & 0x7f)) << shift;

      shift += 7;
      if ((byte & 0x80) == 0)
        {
          success = TRUE;
          break;
        }
    }

  if (length_return != NULL)
    *length_return = num_read;
  if (error_return != NULL)
    *error_return = ! success;

  if (sign && (shift < 8 * sizeof (result)) && (byte & 0x40))
    result |= -((uint64_t) 1 << shift);

  return result;
}

/* Read a 32-bit IEEE float from PC using INFO, convert it to a host
   double, and store it at VALUE.  */

static int
read_f32 (double *value, bfd_vma pc, struct disassemble_info *info)
{
  bfd_byte buf[4];

  if (info->read_memory_func (pc, buf, sizeof (buf), info))
    return -1;

  floatformat_to_double (&floatformat_ieee_single_little, buf,
                         value);

  return sizeof (buf);
}

/* Read a 64-bit IEEE float from PC using INFO, convert it to a host
   double, and store it at VALUE.  */

static int
read_f64 (double *value, bfd_vma pc, struct disassemble_info *info)
{
  bfd_byte buf[8];

  if (info->read_memory_func (pc, buf, sizeof (buf), info))
    return -1;

  floatformat_to_double (&floatformat_ieee_double_little, buf,
                         value);

  return sizeof (buf);
}

/* Main disassembly routine.  Disassemble insn at PC using INFO.  */

int
print_insn_wasm32 (bfd_vma pc, struct disassemble_info *info)
{
  unsigned char opcode;
  struct wasm32_opcode_s *op;
  bfd_byte buffer[16];
  void *stream = info->stream;
  fprintf_ftype prin = info->fprintf_func;
  struct wasm32_private_data *private_data = info->private_data;
  long long constant = 0;
  double fconstant = 0.0;
  long flags = 0;
  long offset = 0;
  long depth = 0;
  long function_index = 0;
  long target_count = 0;
  long block_type = 0;
  int len = 1;
  int ret = 0;
  unsigned int bytes_read = 0;
  int i;
  const char *locals[] =
    {
      "$dpc", "$sp1", "$r0", "$r1", "$rpc", "$pc0",
      "$rp", "$fp", "$sp",
      "$r2", "$r3", "$r4", "$r5", "$r6", "$r7",
      "$i0", "$i1", "$i2", "$i3", "$i4", "$i5", "$i6", "$i7",
      "$f0", "$f1", "$f2", "$f3", "$f4", "$f5", "$f6", "$f7",
    };
  int nlocals = ARRAY_SIZE (locals);
  const char *globals[] =
    {
      "$got", "$plt", "$gpo"
    };
  int nglobals = ARRAY_SIZE (globals);
  bfd_boolean error = FALSE;

  if (info->read_memory_func (pc, buffer, 1, info))
    return -1;

  opcode = buffer[0];

  for (op = wasm32_opcodes; op->name; op++)
    if (op->opcode == opcode)
      break;

  if (!op->name)
    {
      prin (stream, "\t.byte 0x%02x\n", buffer[0]);
      return 1;
    }
  else
    {
      len = 1;

      prin (stream, "\t");
      prin (stream, "%s", op->name);

      if (op->clas == wasm_typed)
        {
          block_type = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          switch (block_type)
            {
            case BLOCK_TYPE_NONE:
              prin (stream, "[]");
              break;
            case BLOCK_TYPE_I32:
              prin (stream, "[i]");
              break;
            case BLOCK_TYPE_I64:
              prin (stream, "[l]");
              break;
            case BLOCK_TYPE_F32:
              prin (stream, "[f]");
              break;
            case BLOCK_TYPE_F64:
              prin (stream, "[d]");
              break;
            }
        }

      switch (op->clas)
        {
        case wasm_special:
        case wasm_eqz:
        case wasm_binary:
        case wasm_unary:
        case wasm_conv:
        case wasm_relational:
        case wasm_drop:
        case wasm_signature:
        case wasm_call_import:
        case wasm_typed:
        case wasm_select:
          break;

        case wasm_break_table:
          target_count = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          prin (stream, " %ld", target_count);
          for (i = 0; i < target_count + 1; i++)
            {
              long target = 0;
              target = wasm_read_leb128
                (pc + len, info, &error, &bytes_read, FALSE);
              if (error)
                return -1;
              len += bytes_read;
              prin (stream, " %ld", target);
            }
          break;

        case wasm_break:
        case wasm_break_if:
          depth = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          prin (stream, " %ld", depth);
          break;

        case wasm_return:
          break;

        case wasm_constant_i32:
        case wasm_constant_i64:
          constant = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, TRUE);
          if (error)
            return -1;
          len += bytes_read;
          prin (stream, " %lld", constant);
          break;

        case wasm_constant_f32:
          /* This appears to be the best we can do, even though we're
             using host doubles for WebAssembly floats.  */
          ret = read_f32 (&fconstant, pc + len, info);
          if (ret < 0)
            return -1;
          len += ret;
	  prin (stream, " %.9g", fconstant);
          break;

        case wasm_constant_f64:
          ret = read_f64 (&fconstant, pc + len, info);
          if (ret < 0)
            return -1;
          len += ret;
	  prin (stream, " %.17g", fconstant);
          break;

        case wasm_call:
          function_index = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          prin (stream, " ");
          private_data->section_prefix = ".space.function_index";
          (*info->print_address_func) ((bfd_vma) function_index, info);
          private_data->section_prefix = NULL;
          break;

        case wasm_call_indirect:
          constant = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          prin (stream, " %lld", constant);
          constant = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          prin (stream, " %lld", constant);
          break;

        case wasm_get_local:
        case wasm_set_local:
        case wasm_tee_local:
          constant = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          prin (stream, " %lld", constant);
          if (strcmp (op->name + 4, "local") == 0)
            {
              if (private_data->print_registers
                  && constant >= 0 && constant < nlocals)
                prin (stream, " <%s>", locals[constant]);
            }
          else
            {
              if (private_data->print_well_known_globals
                  && constant >= 0 && constant < nglobals)
                prin (stream, " <%s>", globals[constant]);
            }
          break;

        case wasm_grow_memory:
        case wasm_current_memory:
          constant = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          prin (stream, " %lld", constant);
          break;

        case wasm_load:
        case wasm_store:
          flags = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          offset = wasm_read_leb128
            (pc + len, info, &error, &bytes_read, FALSE);
          if (error)
            return -1;
          len += bytes_read;
          prin (stream, " a=%ld %ld", flags, offset);
        }
    }
  return len;
}

/* Print valid disassembler options to STREAM.  */

void
print_wasm32_disassembler_options (FILE *stream)
{
  unsigned int i, max_len = 0;

  fprintf (stream, _("\
The following WebAssembly-specific disassembler options are supported for use\n\
with the -M switch:\n"));

  for (i = 0; i < ARRAY_SIZE (options); i++)
    {
      unsigned int len = strlen (options[i].name);

      if (max_len < len)
	max_len = len;
    }

  for (i = 0, max_len++; i < ARRAY_SIZE (options); i++)
    fprintf (stream, "  %s%*c %s\n",
	     options[i].name,
	     (int)(max_len - strlen (options[i].name)), ' ',
	     _(options[i].description));
}