aboutsummaryrefslogtreecommitdiff
path: root/gdb/stap-probe.c
blob: 9f4e00845a487ffeb8406b45f9aaaff2a5b35ae0 (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
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
/* SystemTap probe support for GDB.

   Copyright (C) 2012-2017 Free Software Foundation, Inc.

   This file is part of GDB.

   This program 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.

   This program 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, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "stap-probe.h"
#include "probe.h"
#include "vec.h"
#include "ui-out.h"
#include "objfiles.h"
#include "arch-utils.h"
#include "command.h"
#include "gdbcmd.h"
#include "filenames.h"
#include "value.h"
#include "ax.h"
#include "ax-gdb.h"
#include "complaints.h"
#include "cli/cli-utils.h"
#include "linespec.h"
#include "user-regs.h"
#include "parser-defs.h"
#include "language.h"
#include "elf-bfd.h"

#include <ctype.h>

/* The name of the SystemTap section where we will find information about
   the probes.  */

#define STAP_BASE_SECTION_NAME ".stapsdt.base"

/* Should we display debug information for the probe's argument expression
   parsing?  */

static unsigned int stap_expression_debug = 0;

/* The various possibilities of bitness defined for a probe's argument.

   The relationship is:

   - STAP_ARG_BITNESS_UNDEFINED:  The user hasn't specified the bitness.
   - STAP_ARG_BITNESS_8BIT_UNSIGNED:  argument string starts with `1@'.
   - STAP_ARG_BITNESS_8BIT_SIGNED:  argument string starts with `-1@'.
   - STAP_ARG_BITNESS_16BIT_UNSIGNED:  argument string starts with `2@'.
   - STAP_ARG_BITNESS_16BIT_SIGNED:  argument string starts with `-2@'.
   - STAP_ARG_BITNESS_32BIT_UNSIGNED:  argument string starts with `4@'.
   - STAP_ARG_BITNESS_32BIT_SIGNED:  argument string starts with `-4@'.
   - STAP_ARG_BITNESS_64BIT_UNSIGNED:  argument string starts with `8@'.
   - STAP_ARG_BITNESS_64BIT_SIGNED:  argument string starts with `-8@'.  */

enum stap_arg_bitness
{
  STAP_ARG_BITNESS_UNDEFINED,
  STAP_ARG_BITNESS_8BIT_UNSIGNED,
  STAP_ARG_BITNESS_8BIT_SIGNED,
  STAP_ARG_BITNESS_16BIT_UNSIGNED,
  STAP_ARG_BITNESS_16BIT_SIGNED,
  STAP_ARG_BITNESS_32BIT_UNSIGNED,
  STAP_ARG_BITNESS_32BIT_SIGNED,
  STAP_ARG_BITNESS_64BIT_UNSIGNED,
  STAP_ARG_BITNESS_64BIT_SIGNED,
};

/* The following structure represents a single argument for the probe.  */

struct stap_probe_arg
{
  /* Constructor for stap_probe_arg.  */
  stap_probe_arg (enum stap_arg_bitness bitness_, struct type *atype_,
		  expression_up &&aexpr_)
  : bitness (bitness_), atype (atype_), aexpr (std::move (aexpr_))
  {}

  /* The bitness of this argument.  */
  enum stap_arg_bitness bitness;

  /* The corresponding `struct type *' to the bitness.  */
  struct type *atype;

  /* The argument converted to an internal GDB expression.  */
  expression_up aexpr;
};

/* Class that implements the static probe methods for "stap" probes.  */

class stap_static_probe_ops : public static_probe_ops
{
public:
  /* See probe.h.  */
  bool is_linespec (const char **linespecp) const override;

  /* See probe.h.  */
  void get_probes (std::vector<probe *> *probesp,
		   struct objfile *objfile) const override;

  /* See probe.h.  */
  const char *type_name () const override;

  /* See probe.h.  */
  std::vector<struct info_probe_column> gen_info_probes_table_header
    () const override;
};

/* SystemTap static_probe_ops.  */

const stap_static_probe_ops stap_static_probe_ops;

class stap_probe : public probe
{
public:
  /* Constructor for stap_probe.  */
  stap_probe (std::string &&name_, std::string &&provider_, CORE_ADDR address_,
	      struct gdbarch *arch_, CORE_ADDR sem_addr, const char *args_text)
    : probe (std::move (name_), std::move (provider_), address_, arch_),
      m_sem_addr (sem_addr),
      m_have_parsed_args (false), m_unparsed_args_text (args_text)
  {}

  /* See probe.h.  */
  CORE_ADDR get_relocated_address (struct objfile *objfile) override;

  /* See probe.h.  */
  unsigned get_argument_count (struct frame_info *frame) override;

  /* See probe.h.  */
  bool can_evaluate_arguments () const override;

  /* See probe.h.  */
  struct value *evaluate_argument (unsigned n,
				   struct frame_info *frame) override;

  /* See probe.h.  */
  void compile_to_ax (struct agent_expr *aexpr,
		      struct axs_value *axs_value,
		      unsigned n) override;

  /* See probe.h.  */
  void set_semaphore (struct objfile *objfile,
		      struct gdbarch *gdbarch) override;

  /* See probe.h.  */
  void clear_semaphore (struct objfile *objfile,
			struct gdbarch *gdbarch) override;

  /* See probe.h.  */
  const static_probe_ops *get_static_ops () const override;

  /* See probe.h.  */
  std::vector<const char *> gen_info_probes_table_values () const override;

  /* Return argument N of probe.

     If the probe's arguments have not been parsed yet, parse them.  If
     there are no arguments, throw an exception (error).  Otherwise,
     return the requested argument.  */
  struct stap_probe_arg *get_arg_by_number (unsigned n,
					    struct gdbarch *gdbarch)
  {
    if (!m_have_parsed_args)
      this->parse_arguments (gdbarch);

    gdb_assert (m_have_parsed_args);
    if (m_parsed_args.empty ())
      internal_error (__FILE__, __LINE__,
		      _("Probe '%s' apparently does not have arguments, but \n"
			"GDB is requesting its argument number %u anyway.  "
			"This should not happen.  Please report this bug."),
		      this->get_name ().c_str (), n);

    if (n > m_parsed_args.size ())
      internal_error (__FILE__, __LINE__,
		      _("Probe '%s' has %d arguments, but GDB is requesting\n"
			"argument %u.  This should not happen.  Please\n"
			"report this bug."),
		      this->get_name ().c_str (),
		      (int) m_parsed_args.size (), n);

    return &m_parsed_args[n];
  }

  /* Function which parses an argument string from the probe,
     correctly splitting the arguments and storing their information
     in properly ways.

     Consider the following argument string (x86 syntax):

     `4@%eax 4@$10'

     We have two arguments, `%eax' and `$10', both with 32-bit
     unsigned bitness.  This function basically handles them, properly
     filling some structures with this information.  */
  void parse_arguments (struct gdbarch *gdbarch);

private:
  /* If the probe has a semaphore associated, then this is the value of
     it, relative to SECT_OFF_DATA.  */
  CORE_ADDR m_sem_addr;

  /* True if the arguments have been parsed.  */
  bool m_have_parsed_args;

  /* The text version of the probe's arguments, unparsed.  */
  const char *m_unparsed_args_text;

  /* Information about each argument.  This is an array of `stap_probe_arg',
     with each entry representing one argument.  This is only valid if
     M_ARGS_PARSED is true.  */
  std::vector<struct stap_probe_arg> m_parsed_args;
};

/* When parsing the arguments, we have to establish different precedences
   for the various kinds of asm operators.  This enumeration represents those
   precedences.

   This logic behind this is available at
   <http://sourceware.org/binutils/docs/as/Infix-Ops.html#Infix-Ops>, or using
   the command "info '(as)Infix Ops'".  */

enum stap_operand_prec
{
  /* Lowest precedence, used for non-recognized operands or for the beginning
     of the parsing process.  */
  STAP_OPERAND_PREC_NONE = 0,

  /* Precedence of logical OR.  */
  STAP_OPERAND_PREC_LOGICAL_OR,

  /* Precedence of logical AND.  */
  STAP_OPERAND_PREC_LOGICAL_AND,

  /* Precedence of additive (plus, minus) and comparative (equal, less,
     greater-than, etc) operands.  */
  STAP_OPERAND_PREC_ADD_CMP,

  /* Precedence of bitwise operands (bitwise OR, XOR, bitwise AND,
     logical NOT).  */
  STAP_OPERAND_PREC_BITWISE,

  /* Precedence of multiplicative operands (multiplication, division,
     remainder, left shift and right shift).  */
  STAP_OPERAND_PREC_MUL
};

static void stap_parse_argument_1 (struct stap_parse_info *p, int has_lhs,
				   enum stap_operand_prec prec);

static void stap_parse_argument_conditionally (struct stap_parse_info *p);

/* Returns 1 if *S is an operator, zero otherwise.  */

static int stap_is_operator (const char *op);

static void
show_stapexpressiondebug (struct ui_file *file, int from_tty,
			  struct cmd_list_element *c, const char *value)
{
  fprintf_filtered (file, _("SystemTap Probe expression debugging is %s.\n"),
		    value);
}

/* Returns the operator precedence level of OP, or STAP_OPERAND_PREC_NONE
   if the operator code was not recognized.  */

static enum stap_operand_prec
stap_get_operator_prec (enum exp_opcode op)
{
  switch (op)
    {
    case BINOP_LOGICAL_OR:
      return STAP_OPERAND_PREC_LOGICAL_OR;

    case BINOP_LOGICAL_AND:
      return STAP_OPERAND_PREC_LOGICAL_AND;

    case BINOP_ADD:
    case BINOP_SUB:
    case BINOP_EQUAL:
    case BINOP_NOTEQUAL:
    case BINOP_LESS:
    case BINOP_LEQ:
    case BINOP_GTR:
    case BINOP_GEQ:
      return STAP_OPERAND_PREC_ADD_CMP;

    case BINOP_BITWISE_IOR:
    case BINOP_BITWISE_AND:
    case BINOP_BITWISE_XOR:
    case UNOP_LOGICAL_NOT:
      return STAP_OPERAND_PREC_BITWISE;

    case BINOP_MUL:
    case BINOP_DIV:
    case BINOP_REM:
    case BINOP_LSH:
    case BINOP_RSH:
      return STAP_OPERAND_PREC_MUL;

    default:
      return STAP_OPERAND_PREC_NONE;
    }
}

/* Given S, read the operator in it and fills the OP pointer with its code.
   Return 1 on success, zero if the operator was not recognized.  */

static enum exp_opcode
stap_get_opcode (const char **s)
{
  const char c = **s;
  enum exp_opcode op;

  *s += 1;

  switch (c)
    {
    case '*':
      op = BINOP_MUL;
      break;

    case '/':
      op = BINOP_DIV;
      break;

    case '%':
      op = BINOP_REM;
    break;

    case '<':
      op = BINOP_LESS;
      if (**s == '<')
	{
	  *s += 1;
	  op = BINOP_LSH;
	}
      else if (**s == '=')
	{
	  *s += 1;
	  op = BINOP_LEQ;
	}
      else if (**s == '>')
	{
	  *s += 1;
	  op = BINOP_NOTEQUAL;
	}
    break;

    case '>':
      op = BINOP_GTR;
      if (**s == '>')
	{
	  *s += 1;
	  op = BINOP_RSH;
	}
      else if (**s == '=')
	{
	  *s += 1;
	  op = BINOP_GEQ;
	}
    break;

    case '|':
      op = BINOP_BITWISE_IOR;
      if (**s == '|')
	{
	  *s += 1;
	  op = BINOP_LOGICAL_OR;
	}
    break;

    case '&':
      op = BINOP_BITWISE_AND;
      if (**s == '&')
	{
	  *s += 1;
	  op = BINOP_LOGICAL_AND;
	}
    break;

    case '^':
      op = BINOP_BITWISE_XOR;
      break;

    case '!':
      op = UNOP_LOGICAL_NOT;
      break;

    case '+':
      op = BINOP_ADD;
      break;

    case '-':
      op = BINOP_SUB;
      break;

    case '=':
      gdb_assert (**s == '=');
      op = BINOP_EQUAL;
      break;

    default:
      error (_("Invalid opcode in expression `%s' for SystemTap"
	       "probe"), *s);
    }

  return op;
}

/* Given the bitness of the argument, represented by B, return the
   corresponding `struct type *'.  */

static struct type *
stap_get_expected_argument_type (struct gdbarch *gdbarch,
				 enum stap_arg_bitness b,
				 const char *probe_name)
{
  switch (b)
    {
    case STAP_ARG_BITNESS_UNDEFINED:
      if (gdbarch_addr_bit (gdbarch) == 32)
	return builtin_type (gdbarch)->builtin_uint32;
      else
	return builtin_type (gdbarch)->builtin_uint64;

    case STAP_ARG_BITNESS_8BIT_UNSIGNED:
      return builtin_type (gdbarch)->builtin_uint8;

    case STAP_ARG_BITNESS_8BIT_SIGNED:
      return builtin_type (gdbarch)->builtin_int8;

    case STAP_ARG_BITNESS_16BIT_UNSIGNED:
      return builtin_type (gdbarch)->builtin_uint16;

    case STAP_ARG_BITNESS_16BIT_SIGNED:
      return builtin_type (gdbarch)->builtin_int16;

    case STAP_ARG_BITNESS_32BIT_SIGNED:
      return builtin_type (gdbarch)->builtin_int32;

    case STAP_ARG_BITNESS_32BIT_UNSIGNED:
      return builtin_type (gdbarch)->builtin_uint32;

    case STAP_ARG_BITNESS_64BIT_SIGNED:
      return builtin_type (gdbarch)->builtin_int64;

    case STAP_ARG_BITNESS_64BIT_UNSIGNED:
      return builtin_type (gdbarch)->builtin_uint64;

    default:
      error (_("Undefined bitness for probe '%s'."), probe_name);
      break;
    }
}

/* Helper function to check for a generic list of prefixes.  GDBARCH
   is the current gdbarch being used.  S is the expression being
   analyzed.  If R is not NULL, it will be used to return the found
   prefix.  PREFIXES is the list of expected prefixes.

   This function does a case-insensitive match.

   Return 1 if any prefix has been found, zero otherwise.  */

static int
stap_is_generic_prefix (struct gdbarch *gdbarch, const char *s,
			const char **r, const char *const *prefixes)
{
  const char *const *p;

  if (prefixes == NULL)
    {
      if (r != NULL)
	*r = "";

      return 1;
    }

  for (p = prefixes; *p != NULL; ++p)
    if (strncasecmp (s, *p, strlen (*p)) == 0)
      {
	if (r != NULL)
	  *r = *p;

	return 1;
      }

  return 0;
}

/* Return 1 if S points to a register prefix, zero otherwise.  For a
   description of the arguments, look at stap_is_generic_prefix.  */

static int
stap_is_register_prefix (struct gdbarch *gdbarch, const char *s,
			 const char **r)
{
  const char *const *t = gdbarch_stap_register_prefixes (gdbarch);

  return stap_is_generic_prefix (gdbarch, s, r, t);
}

/* Return 1 if S points to a register indirection prefix, zero
   otherwise.  For a description of the arguments, look at
   stap_is_generic_prefix.  */

static int
stap_is_register_indirection_prefix (struct gdbarch *gdbarch, const char *s,
				     const char **r)
{
  const char *const *t = gdbarch_stap_register_indirection_prefixes (gdbarch);

  return stap_is_generic_prefix (gdbarch, s, r, t);
}

/* Return 1 if S points to an integer prefix, zero otherwise.  For a
   description of the arguments, look at stap_is_generic_prefix.

   This function takes care of analyzing whether we are dealing with
   an expected integer prefix, or, if there is no integer prefix to be
   expected, whether we are dealing with a digit.  It does a
   case-insensitive match.  */

static int
stap_is_integer_prefix (struct gdbarch *gdbarch, const char *s,
			const char **r)
{
  const char *const *t = gdbarch_stap_integer_prefixes (gdbarch);
  const char *const *p;

  if (t == NULL)
    {
      /* A NULL value here means that integers do not have a prefix.
	 We just check for a digit then.  */
      if (r != NULL)
	*r = "";

      return isdigit (*s);
    }

  for (p = t; *p != NULL; ++p)
    {
      size_t len = strlen (*p);

      if ((len == 0 && isdigit (*s))
	  || (len > 0 && strncasecmp (s, *p, len) == 0))
	{
	  /* Integers may or may not have a prefix.  The "len == 0"
	     check covers the case when integers do not have a prefix
	     (therefore, we just check if we have a digit).  The call
	     to "strncasecmp" covers the case when they have a
	     prefix.  */
	  if (r != NULL)
	    *r = *p;

	  return 1;
	}
    }

  return 0;
}

/* Helper function to check for a generic list of suffixes.  If we are
   not expecting any suffixes, then it just returns 1.  If we are
   expecting at least one suffix, then it returns 1 if a suffix has
   been found, zero otherwise.  GDBARCH is the current gdbarch being
   used.  S is the expression being analyzed.  If R is not NULL, it
   will be used to return the found suffix.  SUFFIXES is the list of
   expected suffixes.  This function does a case-insensitive
   match.  */

static int
stap_generic_check_suffix (struct gdbarch *gdbarch, const char *s,
			   const char **r, const char *const *suffixes)
{
  const char *const *p;
  int found = 0;

  if (suffixes == NULL)
    {
      if (r != NULL)
	*r = "";

      return 1;
    }

  for (p = suffixes; *p != NULL; ++p)
    if (strncasecmp (s, *p, strlen (*p)) == 0)
      {
	if (r != NULL)
	  *r = *p;

	found = 1;
	break;
      }

  return found;
}

/* Return 1 if S points to an integer suffix, zero otherwise.  For a
   description of the arguments, look at
   stap_generic_check_suffix.  */

static int
stap_check_integer_suffix (struct gdbarch *gdbarch, const char *s,
			   const char **r)
{
  const char *const *p = gdbarch_stap_integer_suffixes (gdbarch);

  return stap_generic_check_suffix (gdbarch, s, r, p);
}

/* Return 1 if S points to a register suffix, zero otherwise.  For a
   description of the arguments, look at
   stap_generic_check_suffix.  */

static int
stap_check_register_suffix (struct gdbarch *gdbarch, const char *s,
			    const char **r)
{
  const char *const *p = gdbarch_stap_register_suffixes (gdbarch);

  return stap_generic_check_suffix (gdbarch, s, r, p);
}

/* Return 1 if S points to a register indirection suffix, zero
   otherwise.  For a description of the arguments, look at
   stap_generic_check_suffix.  */

static int
stap_check_register_indirection_suffix (struct gdbarch *gdbarch, const char *s,
					const char **r)
{
  const char *const *p = gdbarch_stap_register_indirection_suffixes (gdbarch);

  return stap_generic_check_suffix (gdbarch, s, r, p);
}

/* Function responsible for parsing a register operand according to
   SystemTap parlance.  Assuming:

   RP  = register prefix
   RS  = register suffix
   RIP = register indirection prefix
   RIS = register indirection suffix
   
   Then a register operand can be:
   
   [RIP] [RP] REGISTER [RS] [RIS]

   This function takes care of a register's indirection, displacement and
   direct access.  It also takes into consideration the fact that some
   registers are named differently inside and outside GDB, e.g., PPC's
   general-purpose registers are represented by integers in the assembly
   language (e.g., `15' is the 15th general-purpose register), but inside
   GDB they have a prefix (the letter `r') appended.  */

static void
stap_parse_register_operand (struct stap_parse_info *p)
{
  /* Simple flag to indicate whether we have seen a minus signal before
     certain number.  */
  int got_minus = 0;
  /* Flags to indicate whether this register access is being displaced and/or
     indirected.  */
  int disp_p = 0, indirect_p = 0;
  struct gdbarch *gdbarch = p->gdbarch;
  /* Needed to generate the register name as a part of an expression.  */
  struct stoken str;
  /* Variables used to extract the register name from the probe's
     argument.  */
  const char *start;
  char *regname;
  int len;
  const char *gdb_reg_prefix = gdbarch_stap_gdb_register_prefix (gdbarch);
  int gdb_reg_prefix_len = gdb_reg_prefix ? strlen (gdb_reg_prefix) : 0;
  const char *gdb_reg_suffix = gdbarch_stap_gdb_register_suffix (gdbarch);
  int gdb_reg_suffix_len = gdb_reg_suffix ? strlen (gdb_reg_suffix) : 0;
  const char *reg_prefix;
  const char *reg_ind_prefix;
  const char *reg_suffix;
  const char *reg_ind_suffix;

  /* Checking for a displacement argument.  */
  if (*p->arg == '+')
    {
      /* If it's a plus sign, we don't need to do anything, just advance the
	 pointer.  */
      ++p->arg;
    }

  if (*p->arg == '-')
    {
      got_minus = 1;
      ++p->arg;
    }

  if (isdigit (*p->arg))
    {
      /* The value of the displacement.  */
      long displacement;
      char *endp;

      disp_p = 1;
      displacement = strtol (p->arg, &endp, 10);
      p->arg = endp;

      /* Generating the expression for the displacement.  */
      write_exp_elt_opcode (&p->pstate, OP_LONG);
      write_exp_elt_type (&p->pstate, builtin_type (gdbarch)->builtin_long);
      write_exp_elt_longcst (&p->pstate, displacement);
      write_exp_elt_opcode (&p->pstate, OP_LONG);
      if (got_minus)
	write_exp_elt_opcode (&p->pstate, UNOP_NEG);
    }

  /* Getting rid of register indirection prefix.  */
  if (stap_is_register_indirection_prefix (gdbarch, p->arg, &reg_ind_prefix))
    {
      indirect_p = 1;
      p->arg += strlen (reg_ind_prefix);
    }

  if (disp_p && !indirect_p)
    error (_("Invalid register displacement syntax on expression `%s'."),
	   p->saved_arg);

  /* Getting rid of register prefix.  */
  if (stap_is_register_prefix (gdbarch, p->arg, &reg_prefix))
    p->arg += strlen (reg_prefix);

  /* Now we should have only the register name.  Let's extract it and get
     the associated number.  */
  start = p->arg;

  /* We assume the register name is composed by letters and numbers.  */
  while (isalnum (*p->arg))
    ++p->arg;

  len = p->arg - start;

  regname = (char *) alloca (len + gdb_reg_prefix_len + gdb_reg_suffix_len + 1);
  regname[0] = '\0';

  /* We only add the GDB's register prefix/suffix if we are dealing with
     a numeric register.  */
  if (gdb_reg_prefix && isdigit (*start))
    {
      strncpy (regname, gdb_reg_prefix, gdb_reg_prefix_len);
      strncpy (regname + gdb_reg_prefix_len, start, len);

      if (gdb_reg_suffix)
	strncpy (regname + gdb_reg_prefix_len + len,
		 gdb_reg_suffix, gdb_reg_suffix_len);

      len += gdb_reg_prefix_len + gdb_reg_suffix_len;
    }
  else
    strncpy (regname, start, len);

  regname[len] = '\0';

  /* Is this a valid register name?  */
  if (user_reg_map_name_to_regnum (gdbarch, regname, len) == -1)
    error (_("Invalid register name `%s' on expression `%s'."),
	   regname, p->saved_arg);

  write_exp_elt_opcode (&p->pstate, OP_REGISTER);
  str.ptr = regname;
  str.length = len;
  write_exp_string (&p->pstate, str);
  write_exp_elt_opcode (&p->pstate, OP_REGISTER);

  if (indirect_p)
    {
      if (disp_p)
	write_exp_elt_opcode (&p->pstate, BINOP_ADD);

      /* Casting to the expected type.  */
      write_exp_elt_opcode (&p->pstate, UNOP_CAST);
      write_exp_elt_type (&p->pstate, lookup_pointer_type (p->arg_type));
      write_exp_elt_opcode (&p->pstate, UNOP_CAST);

      write_exp_elt_opcode (&p->pstate, UNOP_IND);
    }

  /* Getting rid of the register name suffix.  */
  if (stap_check_register_suffix (gdbarch, p->arg, &reg_suffix))
    p->arg += strlen (reg_suffix);
  else
    error (_("Missing register name suffix on expression `%s'."),
	   p->saved_arg);

  /* Getting rid of the register indirection suffix.  */
  if (indirect_p)
    {
      if (stap_check_register_indirection_suffix (gdbarch, p->arg,
						  &reg_ind_suffix))
	p->arg += strlen (reg_ind_suffix);
      else
	error (_("Missing indirection suffix on expression `%s'."),
	       p->saved_arg);
    }
}

/* This function is responsible for parsing a single operand.

   A single operand can be:

      - an unary operation (e.g., `-5', `~2', or even with subexpressions
        like `-(2 + 1)')
      - a register displacement, which will be treated as a register
        operand (e.g., `-4(%eax)' on x86)
      - a numeric constant, or
      - a register operand (see function `stap_parse_register_operand')

   The function also calls special-handling functions to deal with
   unrecognized operands, allowing arch-specific parsers to be
   created.  */

static void
stap_parse_single_operand (struct stap_parse_info *p)
{
  struct gdbarch *gdbarch = p->gdbarch;
  const char *int_prefix = NULL;

  /* We first try to parse this token as a "special token".  */
  if (gdbarch_stap_parse_special_token_p (gdbarch))
    if (gdbarch_stap_parse_special_token (gdbarch, p) != 0)
      {
	/* If the return value of the above function is not zero,
	   it means it successfully parsed the special token.

	   If it is NULL, we try to parse it using our method.  */
	return;
      }

  if (*p->arg == '-' || *p->arg == '~' || *p->arg == '+')
    {
      char c = *p->arg;
      /* We use this variable to do a lookahead.  */
      const char *tmp = p->arg;
      int has_digit = 0;

      /* Skipping signal.  */
      ++tmp;

      /* This is an unary operation.  Here is a list of allowed tokens
	 here:

	 - numeric literal;
	 - number (from register displacement)
	 - subexpression (beginning with `(')

	 We handle the register displacement here, and the other cases
	 recursively.  */
      if (p->inside_paren_p)
	tmp = skip_spaces (tmp);

      while (isdigit (*tmp))
	{
	  /* We skip the digit here because we are only interested in
	     knowing what kind of unary operation this is.  The digit
	     will be handled by one of the functions that will be
	     called below ('stap_parse_argument_conditionally' or
	     'stap_parse_register_operand').  */
	  ++tmp;
	  has_digit = 1;
	}

      if (has_digit && stap_is_register_indirection_prefix (gdbarch, tmp,
							    NULL))
	{
	  /* If we are here, it means it is a displacement.  The only
	     operations allowed here are `-' and `+'.  */
	  if (c == '~')
	    error (_("Invalid operator `%c' for register displacement "
		     "on expression `%s'."), c, p->saved_arg);

	  stap_parse_register_operand (p);
	}
      else
	{
	  /* This is not a displacement.  We skip the operator, and
	     deal with it when the recursion returns.  */
	  ++p->arg;
	  stap_parse_argument_conditionally (p);
	  if (c == '-')
	    write_exp_elt_opcode (&p->pstate, UNOP_NEG);
	  else if (c == '~')
	    write_exp_elt_opcode (&p->pstate, UNOP_COMPLEMENT);
	}
    }
  else if (isdigit (*p->arg))
    {
      /* A temporary variable, needed for lookahead.  */
      const char *tmp = p->arg;
      char *endp;
      long number;

      /* We can be dealing with a numeric constant, or with a register
	 displacement.  */
      number = strtol (tmp, &endp, 10);
      tmp = endp;

      if (p->inside_paren_p)
	tmp = skip_spaces (tmp);

      /* If "stap_is_integer_prefix" returns true, it means we can
	 accept integers without a prefix here.  But we also need to
	 check whether the next token (i.e., "tmp") is not a register
	 indirection prefix.  */
      if (stap_is_integer_prefix (gdbarch, p->arg, NULL)
	  && !stap_is_register_indirection_prefix (gdbarch, tmp, NULL))
	{
	  const char *int_suffix;

	  /* We are dealing with a numeric constant.  */
	  write_exp_elt_opcode (&p->pstate, OP_LONG);
	  write_exp_elt_type (&p->pstate,
			      builtin_type (gdbarch)->builtin_long);
	  write_exp_elt_longcst (&p->pstate, number);
	  write_exp_elt_opcode (&p->pstate, OP_LONG);

	  p->arg = tmp;

	  if (stap_check_integer_suffix (gdbarch, p->arg, &int_suffix))
	    p->arg += strlen (int_suffix);
	  else
	    error (_("Invalid constant suffix on expression `%s'."),
		   p->saved_arg);
	}
      else if (stap_is_register_indirection_prefix (gdbarch, tmp, NULL))
	stap_parse_register_operand (p);
      else
	error (_("Unknown numeric token on expression `%s'."),
	       p->saved_arg);
    }
  else if (stap_is_integer_prefix (gdbarch, p->arg, &int_prefix))
    {
      /* We are dealing with a numeric constant.  */
      long number;
      char *endp;
      const char *int_suffix;

      p->arg += strlen (int_prefix);
      number = strtol (p->arg, &endp, 10);
      p->arg = endp;

      write_exp_elt_opcode (&p->pstate, OP_LONG);
      write_exp_elt_type (&p->pstate, builtin_type (gdbarch)->builtin_long);
      write_exp_elt_longcst (&p->pstate, number);
      write_exp_elt_opcode (&p->pstate, OP_LONG);

      if (stap_check_integer_suffix (gdbarch, p->arg, &int_suffix))
	p->arg += strlen (int_suffix);
      else
	error (_("Invalid constant suffix on expression `%s'."),
	       p->saved_arg);
    }
  else if (stap_is_register_prefix (gdbarch, p->arg, NULL)
	   || stap_is_register_indirection_prefix (gdbarch, p->arg, NULL))
    stap_parse_register_operand (p);
  else
    error (_("Operator `%c' not recognized on expression `%s'."),
	   *p->arg, p->saved_arg);
}

/* This function parses an argument conditionally, based on single or
   non-single operands.  A non-single operand would be a parenthesized
   expression (e.g., `(2 + 1)'), and a single operand is anything that
   starts with `-', `~', `+' (i.e., unary operators), a digit, or
   something recognized by `gdbarch_stap_is_single_operand'.  */

static void
stap_parse_argument_conditionally (struct stap_parse_info *p)
{
  gdb_assert (gdbarch_stap_is_single_operand_p (p->gdbarch));

  if (*p->arg == '-' || *p->arg == '~' || *p->arg == '+' /* Unary.  */
      || isdigit (*p->arg)
      || gdbarch_stap_is_single_operand (p->gdbarch, p->arg))
    stap_parse_single_operand (p);
  else if (*p->arg == '(')
    {
      /* We are dealing with a parenthesized operand.  It means we
	 have to parse it as it was a separate expression, without
	 left-side or precedence.  */
      ++p->arg;
      p->arg = skip_spaces (p->arg);
      ++p->inside_paren_p;

      stap_parse_argument_1 (p, 0, STAP_OPERAND_PREC_NONE);

      --p->inside_paren_p;
      if (*p->arg != ')')
	error (_("Missign close-paren on expression `%s'."),
	       p->saved_arg);

      ++p->arg;
      if (p->inside_paren_p)
	p->arg = skip_spaces (p->arg);
    }
  else
    error (_("Cannot parse expression `%s'."), p->saved_arg);
}

/* Helper function for `stap_parse_argument'.  Please, see its comments to
   better understand what this function does.  */

static void
stap_parse_argument_1 (struct stap_parse_info *p, int has_lhs,
		       enum stap_operand_prec prec)
{
  /* This is an operator-precedence parser.

     We work with left- and right-sides of expressions, and
     parse them depending on the precedence of the operators
     we find.  */

  gdb_assert (p->arg != NULL);

  if (p->inside_paren_p)
    p->arg = skip_spaces (p->arg);

  if (!has_lhs)
    {
      /* We were called without a left-side, either because this is the
	 first call, or because we were called to parse a parenthesized
	 expression.  It doesn't really matter; we have to parse the
	 left-side in order to continue the process.  */
      stap_parse_argument_conditionally (p);
    }

  /* Start to parse the right-side, and to "join" left and right sides
     depending on the operation specified.

     This loop shall continue until we run out of characters in the input,
     or until we find a close-parenthesis, which means that we've reached
     the end of a sub-expression.  */
  while (*p->arg != '\0' && *p->arg != ')' && !isspace (*p->arg))
    {
      const char *tmp_exp_buf;
      enum exp_opcode opcode;
      enum stap_operand_prec cur_prec;

      if (!stap_is_operator (p->arg))
	error (_("Invalid operator `%c' on expression `%s'."), *p->arg,
	       p->saved_arg);

      /* We have to save the current value of the expression buffer because
	 the `stap_get_opcode' modifies it in order to get the current
	 operator.  If this operator's precedence is lower than PREC, we
	 should return and not advance the expression buffer pointer.  */
      tmp_exp_buf = p->arg;
      opcode = stap_get_opcode (&tmp_exp_buf);

      cur_prec = stap_get_operator_prec (opcode);
      if (cur_prec < prec)
	{
	  /* If the precedence of the operator that we are seeing now is
	     lower than the precedence of the first operator seen before
	     this parsing process began, it means we should stop parsing
	     and return.  */
	  break;
	}

      p->arg = tmp_exp_buf;
      if (p->inside_paren_p)
	p->arg = skip_spaces (p->arg);

      /* Parse the right-side of the expression.  */
      stap_parse_argument_conditionally (p);

      /* While we still have operators, try to parse another
	 right-side, but using the current right-side as a left-side.  */
      while (*p->arg != '\0' && stap_is_operator (p->arg))
	{
	  enum exp_opcode lookahead_opcode;
	  enum stap_operand_prec lookahead_prec;

	  /* Saving the current expression buffer position.  The explanation
	     is the same as above.  */
	  tmp_exp_buf = p->arg;
	  lookahead_opcode = stap_get_opcode (&tmp_exp_buf);
	  lookahead_prec = stap_get_operator_prec (lookahead_opcode);

	  if (lookahead_prec <= prec)
	    {
	      /* If we are dealing with an operator whose precedence is lower
		 than the first one, just abandon the attempt.  */
	      break;
	    }

	  /* Parse the right-side of the expression, but since we already
	     have a left-side at this point, set `has_lhs' to 1.  */
	  stap_parse_argument_1 (p, 1, lookahead_prec);
	}

      write_exp_elt_opcode (&p->pstate, opcode);
    }
}

/* Parse a probe's argument.

   Assuming that:

   LP = literal integer prefix
   LS = literal integer suffix

   RP = register prefix
   RS = register suffix

   RIP = register indirection prefix
   RIS = register indirection suffix

   This routine assumes that arguments' tokens are of the form:

   - [LP] NUMBER [LS]
   - [RP] REGISTER [RS]
   - [RIP] [RP] REGISTER [RS] [RIS]
   - If we find a number without LP, we try to parse it as a literal integer
   constant (if LP == NULL), or as a register displacement.
   - We count parenthesis, and only skip whitespaces if we are inside them.
   - If we find an operator, we skip it.

   This function can also call a special function that will try to match
   unknown tokens.  It will return the expression_up generated from
   parsing the argument.  */

static expression_up
stap_parse_argument (const char **arg, struct type *atype,
		     struct gdbarch *gdbarch)
{
  struct stap_parse_info p;
  struct cleanup *back_to;

  /* We need to initialize the expression buffer, in order to begin
     our parsing efforts.  We use language_c here because we may need
     to do pointer arithmetics.  */
  initialize_expout (&p.pstate, 10, language_def (language_c), gdbarch);
  back_to = make_cleanup (free_current_contents, &p.pstate.expout);

  p.saved_arg = *arg;
  p.arg = *arg;
  p.arg_type = atype;
  p.gdbarch = gdbarch;
  p.inside_paren_p = 0;

  stap_parse_argument_1 (&p, 0, STAP_OPERAND_PREC_NONE);

  discard_cleanups (back_to);

  gdb_assert (p.inside_paren_p == 0);

  /* Casting the final expression to the appropriate type.  */
  write_exp_elt_opcode (&p.pstate, UNOP_CAST);
  write_exp_elt_type (&p.pstate, atype);
  write_exp_elt_opcode (&p.pstate, UNOP_CAST);

  reallocate_expout (&p.pstate);

  p.arg = skip_spaces (p.arg);
  *arg = p.arg;

  /* We can safely return EXPOUT here.  */
  return expression_up (p.pstate.expout);
}

/* Implementation of 'parse_arguments' method.  */

void
stap_probe::parse_arguments (struct gdbarch *gdbarch)
{
  const char *cur;

  gdb_assert (!m_have_parsed_args);
  cur = m_unparsed_args_text;
  m_have_parsed_args = true;

  if (cur == NULL || *cur == '\0' || *cur == ':')
    return;

  while (*cur != '\0')
    {
      enum stap_arg_bitness bitness;
      bool got_minus = false;

      /* We expect to find something like:

	 N@OP

	 Where `N' can be [+,-][1,2,4,8].  This is not mandatory, so
	 we check it here.  If we don't find it, go to the next
	 state.  */
      if ((cur[0] == '-' && isdigit (cur[1]) && cur[2] == '@')
	  || (isdigit (cur[0]) && cur[1] == '@'))
	{
	  if (*cur == '-')
	    {
	      /* Discard the `-'.  */
	      ++cur;
	      got_minus = true;
	    }

	  /* Defining the bitness.  */
	  switch (*cur)
	    {
	    case '1':
	      bitness = (got_minus ? STAP_ARG_BITNESS_8BIT_SIGNED
			 : STAP_ARG_BITNESS_8BIT_UNSIGNED);
	      break;

	    case '2':
	      bitness = (got_minus ? STAP_ARG_BITNESS_16BIT_SIGNED
			 : STAP_ARG_BITNESS_16BIT_UNSIGNED);
	      break;

	    case '4':
	      bitness = (got_minus ? STAP_ARG_BITNESS_32BIT_SIGNED
			 : STAP_ARG_BITNESS_32BIT_UNSIGNED);
	      break;

	    case '8':
	      bitness = (got_minus ? STAP_ARG_BITNESS_64BIT_SIGNED
			 : STAP_ARG_BITNESS_64BIT_UNSIGNED);
	      break;

	    default:
	      {
		/* We have an error, because we don't expect anything
		   except 1, 2, 4 and 8.  */
		warning (_("unrecognized bitness %s%c' for probe `%s'"),
			 got_minus ? "`-" : "`", *cur,
			 this->get_name ().c_str ());
		return;
	      }
	    }
	  /* Discard the number and the `@' sign.  */
	  cur += 2;
	}
      else
	bitness = STAP_ARG_BITNESS_UNDEFINED;

      struct type *atype
	= stap_get_expected_argument_type (gdbarch, bitness,
					   this->get_name ().c_str ());

      expression_up expr = stap_parse_argument (&cur, atype, gdbarch);

      if (stap_expression_debug)
	dump_raw_expression (expr.get (), gdb_stdlog,
			     "before conversion to prefix form");

      prefixify_expression (expr.get ());

      if (stap_expression_debug)
	dump_prefix_expression (expr.get (), gdb_stdlog);

      m_parsed_args.emplace_back (bitness, atype, std::move (expr));

      /* Start it over again.  */
      cur = skip_spaces (cur);
    }
}

/* Helper function to relocate an address.  */

static CORE_ADDR
relocate_address (CORE_ADDR address, struct objfile *objfile)
{
  return address + ANOFFSET (objfile->section_offsets,
			     SECT_OFF_DATA (objfile));
}

/* Implementation of the get_relocated_address method.  */

CORE_ADDR
stap_probe::get_relocated_address (struct objfile *objfile)
{
  return relocate_address (this->get_address (), objfile);
}

/* Given PROBE, returns the number of arguments present in that probe's
   argument string.  */

unsigned
stap_probe::get_argument_count (struct frame_info *frame)
{
  struct gdbarch *gdbarch = get_frame_arch (frame);

  if (!m_have_parsed_args)
    {
      if (this->can_evaluate_arguments ())
	this->parse_arguments (gdbarch);
      else
	{
	  static int have_warned_stap_incomplete = 0;

	  if (!have_warned_stap_incomplete)
	    {
	      warning (_(
"The SystemTap SDT probe support is not fully implemented on this target;\n"
"you will not be able to inspect the arguments of the probes.\n"
"Please report a bug against GDB requesting a port to this target."));
	      have_warned_stap_incomplete = 1;
	    }

	  /* Marking the arguments as "already parsed".  */
	  m_have_parsed_args = true;
	}
    }

  gdb_assert (m_have_parsed_args);
  return m_parsed_args.size ();
}

/* Return 1 if OP is a valid operator inside a probe argument, or zero
   otherwise.  */

static int
stap_is_operator (const char *op)
{
  int ret = 1;

  switch (*op)
    {
    case '*':
    case '/':
    case '%':
    case '^':
    case '!':
    case '+':
    case '-':
    case '<':
    case '>':
    case '|':
    case '&':
      break;

    case '=':
      if (op[1] != '=')
	ret = 0;
      break;

    default:
      /* We didn't find any operator.  */
      ret = 0;
    }

  return ret;
}

/* Implement the `can_evaluate_arguments' method.  */

bool
stap_probe::can_evaluate_arguments () const
{
  struct gdbarch *gdbarch = this->get_gdbarch ();

  /* For SystemTap probes, we have to guarantee that the method
     stap_is_single_operand is defined on gdbarch.  If it is not, then it
     means that argument evaluation is not implemented on this target.  */
  return gdbarch_stap_is_single_operand_p (gdbarch);
}

/* Evaluate the probe's argument N (indexed from 0), returning a value
   corresponding to it.  Assertion is thrown if N does not exist.  */

struct value *
stap_probe::evaluate_argument (unsigned n, struct frame_info *frame)
{
  struct stap_probe_arg *arg;
  int pos = 0;
  struct gdbarch *gdbarch = get_frame_arch (frame);

  arg = this->get_arg_by_number (n, gdbarch);
  return evaluate_subexp_standard (arg->atype, arg->aexpr.get (), &pos,
				   EVAL_NORMAL);
}

/* Compile the probe's argument N (indexed from 0) to agent expression.
   Assertion is thrown if N does not exist.  */

void
stap_probe::compile_to_ax (struct agent_expr *expr, struct axs_value *value,
			   unsigned n)
{
  struct stap_probe_arg *arg;
  union exp_element *pc;

  arg = this->get_arg_by_number (n, expr->gdbarch);

  pc = arg->aexpr->elts;
  gen_expr (arg->aexpr.get (), &pc, expr, value);

  require_rvalue (expr, value);
  value->type = arg->atype;
}


/* Set or clear a SystemTap semaphore.  ADDRESS is the semaphore's
   address.  SET is zero if the semaphore should be cleared, or one if
   it should be set.  This is a helper function for
   'stap_probe::set_semaphore' and 'stap_probe::clear_semaphore'.  */

static void
stap_modify_semaphore (CORE_ADDR address, int set, struct gdbarch *gdbarch)
{
  gdb_byte bytes[sizeof (LONGEST)];
  /* The ABI specifies "unsigned short".  */
  struct type *type = builtin_type (gdbarch)->builtin_unsigned_short;
  ULONGEST value;

  if (address == 0)
    return;

  /* Swallow errors.  */
  if (target_read_memory (address, bytes, TYPE_LENGTH (type)) != 0)
    {
      warning (_("Could not read the value of a SystemTap semaphore."));
      return;
    }

  value = extract_unsigned_integer (bytes, TYPE_LENGTH (type),
				    gdbarch_byte_order (gdbarch));
  /* Note that we explicitly don't worry about overflow or
     underflow.  */
  if (set)
    ++value;
  else
    --value;

  store_unsigned_integer (bytes, TYPE_LENGTH (type),
			  gdbarch_byte_order (gdbarch), value);

  if (target_write_memory (address, bytes, TYPE_LENGTH (type)) != 0)
    warning (_("Could not write the value of a SystemTap semaphore."));
}

/* Implementation of the 'set_semaphore' method.

   SystemTap semaphores act as reference counters, so calls to this
   function must be paired with calls to 'clear_semaphore'.

   This function and 'clear_semaphore' race with another tool
   changing the probes, but that is too rare to care.  */

void
stap_probe::set_semaphore (struct objfile *objfile, struct gdbarch *gdbarch)
{
  stap_modify_semaphore (relocate_address (m_sem_addr, objfile), 1, gdbarch);
}

/* Implementation of the 'clear_semaphore' method.  */

void
stap_probe::clear_semaphore (struct objfile *objfile, struct gdbarch *gdbarch)
{
  stap_modify_semaphore (relocate_address (m_sem_addr, objfile), 0, gdbarch);
}

/* Implementation of the 'get_static_ops' method.  */

const static_probe_ops *
stap_probe::get_static_ops () const
{
  return &stap_static_probe_ops;
}

/* Implementation of the 'gen_info_probes_table_values' method.  */

std::vector<const char *>
stap_probe::gen_info_probes_table_values () const
{
  const char *val = NULL;

  if (m_sem_addr != 0)
    val = print_core_address (this->get_gdbarch (), m_sem_addr);

  return std::vector<const char *> { val };
}

/* Helper function that parses the information contained in a
   SystemTap's probe.  Basically, the information consists in:

   - Probe's PC address;
   - Link-time section address of `.stapsdt.base' section;
   - Link-time address of the semaphore variable, or ZERO if the
     probe doesn't have an associated semaphore;
   - Probe's provider name;
   - Probe's name;
   - Probe's argument format
   
   This function returns 1 if the handling was successful, and zero
   otherwise.  */

static void
handle_stap_probe (struct objfile *objfile, struct sdt_note *el,
		   std::vector<probe *> *probesp, CORE_ADDR base)
{
  bfd *abfd = objfile->obfd;
  int size = bfd_get_arch_size (abfd) / 8;
  struct gdbarch *gdbarch = get_objfile_arch (objfile);
  struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr;

  /* Provider and the name of the probe.  */
  const char *provider = (const char *) &el->data[3 * size];
  const char *name = ((const char *)
		      memchr (provider, '\0',
			      (char *) el->data + el->size - provider));
  /* Making sure there is a name.  */
  if (name == NULL)
    {
      complaint (&symfile_complaints, _("corrupt probe name when "
					"reading `%s'"),
		 objfile_name (objfile));

      /* There is no way to use a probe without a name or a provider, so
	 returning zero here makes sense.  */
      return;
    }
  else
    ++name;

  /* Retrieving the probe's address.  */
  CORE_ADDR address = extract_typed_address (&el->data[0], ptr_type);

  /* Link-time sh_addr of `.stapsdt.base' section.  */
  CORE_ADDR base_ref = extract_typed_address (&el->data[size], ptr_type);

  /* Semaphore address.  */
  CORE_ADDR sem_addr = extract_typed_address (&el->data[2 * size], ptr_type);

  address += base - base_ref;
  if (sem_addr != 0)
    sem_addr += base - base_ref;

  /* Arguments.  We can only extract the argument format if there is a valid
     name for this probe.  */
  const char *probe_args = ((const char*)
			    memchr (name, '\0',
				    (char *) el->data + el->size - name));

  if (probe_args != NULL)
    ++probe_args;

  if (probe_args == NULL
      || (memchr (probe_args, '\0', (char *) el->data + el->size - name)
	  != el->data + el->size - 1))
    {
      complaint (&symfile_complaints, _("corrupt probe argument when "
					"reading `%s'"),
		 objfile_name (objfile));
      /* If the argument string is NULL, it means some problem happened with
	 it.  So we return 0.  */
      return;
    }

  stap_probe *ret = new stap_probe (std::string (name), std::string (provider),
				    address, gdbarch, sem_addr, probe_args);

  /* Successfully created probe.  */
  probesp->push_back (ret);
}

/* Helper function which tries to find the base address of the SystemTap
   base section named STAP_BASE_SECTION_NAME.  */

static void
get_stap_base_address_1 (bfd *abfd, asection *sect, void *obj)
{
  asection **ret = (asection **) obj;

  if ((sect->flags & (SEC_DATA | SEC_ALLOC | SEC_HAS_CONTENTS))
      && sect->name && !strcmp (sect->name, STAP_BASE_SECTION_NAME))
    *ret = sect;
}

/* Helper function which iterates over every section in the BFD file,
   trying to find the base address of the SystemTap base section.
   Returns 1 if found (setting BASE to the proper value), zero otherwise.  */

static int
get_stap_base_address (bfd *obfd, bfd_vma *base)
{
  asection *ret = NULL;

  bfd_map_over_sections (obfd, get_stap_base_address_1, (void *) &ret);

  if (ret == NULL)
    {
      complaint (&symfile_complaints, _("could not obtain base address for "
					"SystemTap section on objfile `%s'."),
		 obfd->filename);
      return 0;
    }

  if (base != NULL)
    *base = ret->vma;

  return 1;
}

/* Implementation of the 'is_linespec' method.  */

bool
stap_static_probe_ops::is_linespec (const char **linespecp) const
{
  static const char *const keywords[] = { "-pstap", "-probe-stap", NULL };

  return probe_is_linespec_by_keyword (linespecp, keywords);
}

/* Implementation of the 'get_probes' method.  */

void
stap_static_probe_ops::get_probes (std::vector<probe *> *probesp,
				   struct objfile *objfile) const
{
  /* If we are here, then this is the first time we are parsing the
     SystemTap probe's information.  We basically have to count how many
     probes the objfile has, and then fill in the necessary information
     for each one.  */
  bfd *obfd = objfile->obfd;
  bfd_vma base;
  struct sdt_note *iter;
  unsigned save_probesp_len = probesp->size ();

  if (objfile->separate_debug_objfile_backlink != NULL)
    {
      /* This is a .debug file, not the objfile itself.  */
      return;
    }

  if (elf_tdata (obfd)->sdt_note_head == NULL)
    {
      /* There isn't any probe here.  */
      return;
    }

  if (!get_stap_base_address (obfd, &base))
    {
      /* There was an error finding the base address for the section.
	 Just return NULL.  */
      return;
    }

  /* Parsing each probe's information.  */
  for (iter = elf_tdata (obfd)->sdt_note_head;
       iter != NULL;
       iter = iter->next)
    {
      /* We first have to handle all the information about the
	 probe which is present in the section.  */
      handle_stap_probe (objfile, iter, probesp, base);
    }

  if (save_probesp_len == probesp->size ())
    {
      /* If we are here, it means we have failed to parse every known
	 probe.  */
      complaint (&symfile_complaints, _("could not parse SystemTap probe(s) "
					"from inferior"));
      return;
    }
}

/* Implementation of the type_name method.  */

const char *
stap_static_probe_ops::type_name () const
{
  return "stap";
}

/* Implementation of the 'gen_info_probes_table_header' method.  */

std::vector<struct info_probe_column>
stap_static_probe_ops::gen_info_probes_table_header () const
{
  struct info_probe_column stap_probe_column;

  stap_probe_column.field_name = "semaphore";
  stap_probe_column.print_name = _("Semaphore");

  return std::vector<struct info_probe_column> { stap_probe_column };
}

/* Implementation of the `info probes stap' command.  */

static void
info_probes_stap_command (const char *arg, int from_tty)
{
  info_probes_for_spops (arg, from_tty, &stap_static_probe_ops);
}

void
_initialize_stap_probe (void)
{
  all_static_probe_ops.push_back (&stap_static_probe_ops);

  add_setshow_zuinteger_cmd ("stap-expression", class_maintenance,
			     &stap_expression_debug,
			     _("Set SystemTap expression debugging."),
			     _("Show SystemTap expression debugging."),
			     _("When non-zero, the internal representation "
			       "of SystemTap expressions will be printed."),
			     NULL,
			     show_stapexpressiondebug,
			     &setdebuglist, &showdebuglist);

  add_cmd ("stap", class_info, info_probes_stap_command,
	   _("\
Show information about SystemTap static probes.\n\
Usage: info probes stap [PROVIDER [NAME [OBJECT]]]\n\
Each argument is a regular expression, used to select probes.\n\
PROVIDER matches probe provider names.\n\
NAME matches the probe names.\n\
OBJECT matches the executable or shared library name."),
	   info_probes_cmdlist_get ());

}