gdb/dtrace-probe.c

   1 /* DTrace probe support for GDB.
   2
   3    Copyright (C) 2014-2015 Free Software Foundation, Inc.
   4
   5    Contributed by Oracle, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "probe.h"
  24 #include "vec.h"
  25 #include "elf-bfd.h"
  26 #include "gdbtypes.h"
  27 #include "obstack.h"
  28 #include "objfiles.h"
  29 #include "complaints.h"
  30 #include "value.h"
  31 #include "ax.h"
  32 #include "ax-gdb.h"
  33 #include "language.h"
  34 #include "parser-defs.h"
  35 #include "inferior.h"
  36
  37 /* The type of the ELF sections where we will find the DOF programs
  38    with information about probes.  */
  39
  40 #ifndef SHT_SUNW_dof
  41 # define SHT_SUNW_dof   0x6ffffff4
  42 #endif
  43
  44 /* Forward declaration.  */
  45
  46 static const struct probe_ops dtrace_probe_ops;
  47
  48 /* The following structure represents a single argument for the
  49    probe.  */
  50
  51 struct dtrace_probe_arg
  52 {
  53   /* The type of the probe argument.  */
  54   struct type *type;
  55
  56   /* A string describing the type.  */
  57   char *type_str;
  58
  59   /* The argument converted to an internal GDB expression.  */
  60   struct expression *expr;
  61 };
  62
  63 typedef struct dtrace_probe_arg dtrace_probe_arg_s;
  64 DEF_VEC_O (dtrace_probe_arg_s);
  65
  66 /* The following structure represents an enabler for a probe.  */
  67
  68 struct dtrace_probe_enabler
  69 {
  70   /* Program counter where the is-enabled probe is installed.  The
  71      contents (nops, whatever...) stored at this address are
  72      architecture dependent.  */
  73   CORE_ADDR address;
  74 };
  75
  76 typedef struct dtrace_probe_enabler dtrace_probe_enabler_s;
  77 DEF_VEC_O (dtrace_probe_enabler_s);
  78
  79 /* The following structure represents a dtrace probe.  */
  80
  81 struct dtrace_probe
  82 {
  83   /* Generic information about the probe.  This must be the first
  84      element of this struct, in order to maintain binary compatibility
  85      with the `struct probe' and be able to fully abstract it.  */
  86   struct probe p;
  87
  88   /* A probe can have zero or more arguments.  */
  89   int probe_argc;
  90   VEC (dtrace_probe_arg_s) *args;
  91
  92   /* A probe can have zero or more "enablers" associated with it.  */
  93   VEC (dtrace_probe_enabler_s) *enablers;
  94
  95   /* Whether the expressions for the arguments have been built.  */
  96   unsigned int args_expr_built : 1;
  97 };
  98
  99 /* Implementation of the probe_is_linespec method.  */
 100
 101 static int
 102 dtrace_probe_is_linespec (const char **linespecp)
 103 {
 104   static const char *const keywords[] = { "-pdtrace", "-probe-dtrace", NULL };
 105
 106   return probe_is_linespec_by_keyword (linespecp, keywords);
 107 }
 108
 109 /* DOF programs can contain an arbitrary number of sections of 26
 110    different types.  In order to support DTrace USDT probes we only
 111    need to handle a subset of these section types, fortunately.  These
 112    section types are defined in the following enumeration.
 113
 114    See linux/dtrace/dof_defines.h for a complete list of section types
 115    along with their values.  */
 116
 117 enum dtrace_dof_sect_type
 118 {
 119   /* Null section.  */
 120   DTRACE_DOF_SECT_TYPE_NONE = 0,
 121   /* A dof_ecbdesc_t. */
 122   DTRACE_DOF_SECT_TYPE_ECBDESC = 3,
 123   /* A string table.  */
 124   DTRACE_DOF_SECT_TYPE_STRTAB = 8,
 125   /* A dof_provider_t  */
 126   DTRACE_DOF_SECT_TYPE_PROVIDER = 15,
 127   /* Array of dof_probe_t  */
 128   DTRACE_DOF_SECT_TYPE_PROBES = 16,
 129   /* An array of probe arg mappings.  */
 130   DTRACE_DOF_SECT_TYPE_PRARGS = 17,
 131   /* An array of probe arg offsets.  */
 132   DTRACE_DOF_SECT_TYPE_PROFFS = 18,
 133   /* An array of probe is-enabled offsets.  */
 134   DTRACE_DOF_SECT_TYPE_PRENOFFS = 26
 135 };
 136
 137 /* The following collection of data structures map the structure of
 138    DOF entities.  Again, we only cover the subset of DOF used to
 139    implement USDT probes.
 140
 141    See linux/dtrace/dof.h header for a complete list of data
 142    structures.  */
 143
 144 /* Offsets to index the dofh_ident[] array defined below.  */
 145
 146 enum dtrace_dof_ident
 147 {
 148   /* First byte of the magic number.  */
 149   DTRACE_DOF_ID_MAG0 = 0,
 150   /* Second byte of the magic number.  */
 151   DTRACE_DOF_ID_MAG1 = 1,
 152   /* Third byte of the magic number.  */
 153   DTRACE_DOF_ID_MAG2 = 2,
 154   /* Fourth byte of the magic number.  */
 155   DTRACE_DOF_ID_MAG3 = 3,
 156   /* An enum_dof_encoding value.  */
 157   DTRACE_DOF_ID_ENCODING = 5
 158 };
 159
 160 /* Possible values for dofh_ident[DOF_ID_ENCODING].  */
 161
 162 enum dtrace_dof_encoding
 163 {
 164   /* The DOF program is little-endian.  */
 165   DTRACE_DOF_ENCODE_LSB = 1,
 166   /* The DOF program is big-endian.  */
 167   DTRACE_DOF_ENCODE_MSB = 2
 168 };
 169
 170 /* A DOF header, which describes the contents of a DOF program: number
 171    of sections, size, etc.  */
 172
 173 struct dtrace_dof_hdr
 174 {
 175   /* Identification bytes (see above). */
 176   uint8_t dofh_ident[16];
 177   /* File attribute flags (if any). */
 178   uint32_t dofh_flags;
 179   /* Size of file header in bytes. */
 180   uint32_t dofh_hdrsize;
 181   /* Size of section header in bytes. */
 182   uint32_t dofh_secsize;
 183   /* Number of section headers. */
 184   uint32_t dofh_secnum;
 185   /* File offset of section headers. */
 186   uint64_t dofh_secoff;
 187   /* File size of loadable portion. */
 188   uint64_t dofh_loadsz;
 189   /* File size of entire DOF file. */
 190   uint64_t dofh_filesz;
 191   /* Reserved for future use. */
 192   uint64_t dofh_pad;
 193 };
 194
 195 /* A DOF section, whose contents depend on its type.  The several
 196    supported section types are described in the enum
 197    dtrace_dof_sect_type above.  */
 198
 199 struct dtrace_dof_sect
 200 {
 201   /* Section type (see the define above). */
 202   uint32_t dofs_type;
 203   /* Section data memory alignment. */
 204   uint32_t dofs_align;
 205   /* Section flags (if any). */
 206   uint32_t dofs_flags;
 207   /* Size of section entry (if table). */
 208   uint32_t dofs_entsize;
 209   /* DOF + offset points to the section data. */
 210   uint64_t dofs_offset;
 211   /* Size of section data in bytes.  */
 212   uint64_t dofs_size;
 213 };
 214
 215 /* A DOF provider, which is the provider of a probe.  */
 216
 217 struct dtrace_dof_provider
 218 {
 219   /* Link to a DTRACE_DOF_SECT_TYPE_STRTAB section. */
 220   uint32_t dofpv_strtab;
 221   /* Link to a DTRACE_DOF_SECT_TYPE_PROBES section. */
 222   uint32_t dofpv_probes;
 223   /* Link to a DTRACE_DOF_SECT_TYPE_PRARGS section. */
 224   uint32_t dofpv_prargs;
 225   /* Link to a DTRACE_DOF_SECT_TYPE_PROFFS section. */
 226   uint32_t dofpv_proffs;
 227   /* Provider name string. */
 228   uint32_t dofpv_name;
 229   /* Provider attributes. */
 230   uint32_t dofpv_provattr;
 231   /* Module attributes. */
 232   uint32_t dofpv_modattr;
 233   /* Function attributes. */
 234   uint32_t dofpv_funcattr;
 235   /* Name attributes. */
 236   uint32_t dofpv_nameattr;
 237   /* Args attributes. */
 238   uint32_t dofpv_argsattr;
 239   /* Link to a DTRACE_DOF_SECT_PRENOFFS section. */
 240   uint32_t dofpv_prenoffs;
 241 };
 242
 243 /* A set of DOF probes and is-enabled probes sharing a base address
 244    and several attributes.  The particular locations and attributes of
 245    each probe are maintained in arrays in several other DOF sections.
 246    See the comment in dtrace_process_dof_probe for details on how
 247    these attributes are stored.  */
 248
 249 struct dtrace_dof_probe
 250 {
 251   /* Probe base address or offset. */
 252   uint64_t dofpr_addr;
 253   /* Probe function string. */
 254   uint32_t dofpr_func;
 255   /* Probe name string. */
 256   uint32_t dofpr_name;
 257   /* Native argument type strings. */
 258   uint32_t dofpr_nargv;
 259   /* Translated argument type strings. */
 260   uint32_t dofpr_xargv;
 261   /* Index of first argument mapping. */
 262   uint32_t dofpr_argidx;
 263   /* Index of first offset entry. */
 264   uint32_t dofpr_offidx;
 265   /* Native argument count. */
 266   uint8_t  dofpr_nargc;
 267   /* Translated argument count. */
 268   uint8_t  dofpr_xargc;
 269   /* Number of offset entries for probe. */
 270   uint16_t dofpr_noffs;
 271   /* Index of first is-enabled offset. */
 272   uint32_t dofpr_enoffidx;
 273   /* Number of is-enabled offsets. */
 274   uint16_t dofpr_nenoffs;
 275   /* Reserved for future use. */
 276   uint16_t dofpr_pad1;
 277   /* Reserved for future use. */
 278   uint32_t dofpr_pad2;
 279 };
 280
 281 /* DOF supports two different encodings: MSB (big-endian) and LSB
 282    (little-endian).  The encoding is itself encoded in the DOF header.
 283    The following function returns an unsigned value in the host
 284    endianness.  */
 285
 286 #define DOF_UINT(dof, field)                                            \
 287   extract_unsigned_integer ((gdb_byte *) &(field),                      \
 288                             sizeof ((field)),                           \
 289                             (((dof)->dofh_ident[DTRACE_DOF_ID_ENCODING] \
 290                               == DTRACE_DOF_ENCODE_MSB)                 \
 291                              ? BFD_ENDIAN_BIG : BFD_ENDIAN_LITTLE))
 292
 293 /* The following macro applies a given byte offset to a DOF (a pointer
 294    to a dtrace_dof_hdr structure) and returns the resulting
 295    address.  */
 296
 297 #define DTRACE_DOF_PTR(dof, offset) (&((char *) (dof))[(offset)])
 298
 299 /* The following macro returns a pointer to the beginning of a given
 300    section in a DOF object.  The section is referred to by its index
 301    in the sections array.  */
 302
 303 #define DTRACE_DOF_SECT(dof, idx)                                       \
 304   ((struct dtrace_dof_sect *)                                           \
 305    DTRACE_DOF_PTR ((dof),                                               \
 306                    DOF_UINT ((dof), (dof)->dofh_secoff)                 \
 307                    + ((idx) * DOF_UINT ((dof), (dof)->dofh_secsize))))
 308
 309 /* Helper function to examine the probe described by the given PROBE
 310    and PROVIDER data structures and add it to the PROBESP vector.
 311    STRTAB, OFFTAB, EOFFTAB and ARGTAB are pointers to tables in the
 312    DOF program containing the attributes for the probe.  */
 313
 314 static void
 315 dtrace_process_dof_probe (struct objfile *objfile,
 316                           struct gdbarch *gdbarch, VEC (probe_p) **probesp,
 317                           struct dtrace_dof_hdr *dof,
 318                           struct dtrace_dof_probe *probe,
 319                           struct dtrace_dof_provider *provider,
 320                           char *strtab, char *offtab, char *eofftab,
 321                           char *argtab, uint64_t strtab_size)
 322 {
 323   int i, j, num_probes, num_enablers;
 324   struct cleanup *cleanup;
 325   VEC (dtrace_probe_enabler_s) *enablers;
 326   char *p;
 327
 328   /* Each probe section can define zero or more probes of two
 329      different types:
 330
 331      - probe->dofpr_noffs regular probes whose program counters are
 332        stored in 32bit words starting at probe->dofpr_addr +
 333        offtab[probe->dofpr_offidx].
 334
 335      - probe->dofpr_nenoffs is-enabled probes whose program counters
 336        are stored in 32bit words starting at probe->dofpr_addr +
 337        eofftab[probe->dofpr_enoffidx].
 338
 339      However is-enabled probes are not probes per-se, but an
 340      optimization hack that is implemented in the kernel in a very
 341      similar way than normal probes.  This is how we support
 342      is-enabled probes on GDB:
 343
 344      - Our probes are always DTrace regular probes.
 345
 346      - Our probes can be associated with zero or more "enablers".  The
 347        list of enablers is built from the is-enabled probes defined in
 348        the Probe section.
 349
 350      - Probes having a non-empty list of enablers can be enabled or
 351        disabled using the `enable probe' and `disable probe' commands
 352        respectively.  The `Enabled' column in the output of `info
 353        probes' will read `yes' if the enablers are activated, `no'
 354        otherwise.
 355
 356      - Probes having an empty list of enablers are always enabled.
 357        The `Enabled' column in the output of `info probes' will
 358        read `always'.
 359
 360      It follows that if there are DTrace is-enabled probes defined for
 361      some provider/name but no DTrace regular probes defined then the
 362      GDB user wont be able to enable/disable these conditionals.  */
 363
 364   num_probes = DOF_UINT (dof, probe->dofpr_noffs);
 365   if (num_probes == 0)
 366     return;
 367
 368   /* Build the list of enablers for the probes defined in this Probe
 369      DOF section.  */
 370   enablers = NULL;
 371   cleanup
 372     = make_cleanup (VEC_cleanup (dtrace_probe_enabler_s), &enablers);
 373   num_enablers = DOF_UINT (dof, probe->dofpr_nenoffs);
 374   for (i = 0; i < num_enablers; i++)
 375     {
 376       struct dtrace_probe_enabler enabler;
 377       uint32_t enabler_offset
 378         = ((uint32_t *) eofftab)[DOF_UINT (dof, probe->dofpr_enoffidx) + i];
 379
 380       enabler.address = DOF_UINT (dof, probe->dofpr_addr)
 381         + DOF_UINT (dof, enabler_offset);
 382       VEC_safe_push (dtrace_probe_enabler_s, enablers, &enabler);
 383     }
 384
 385   for (i = 0; i < num_probes; i++)
 386     {
 387       uint32_t probe_offset
 388         = ((uint32_t *) offtab)[DOF_UINT (dof, probe->dofpr_offidx) + i];
 389       struct dtrace_probe *ret
 390         = obstack_alloc (&objfile->per_bfd->storage_obstack, sizeof (*ret));
 391
 392       ret->p.pops = &dtrace_probe_ops;
 393       ret->p.arch = gdbarch;
 394       ret->args_expr_built = 0;
 395
 396       /* Set the provider and the name of the probe.  */
 397       ret->p.provider
 398         = xstrdup (strtab + DOF_UINT (dof, provider->dofpv_name));
 399       ret->p.name = xstrdup (strtab + DOF_UINT (dof, probe->dofpr_name));
 400
 401       /* The probe address.  */
 402       ret->p.address
 403         = DOF_UINT (dof, probe->dofpr_addr) + DOF_UINT (dof, probe_offset);
 404
 405       /* Number of arguments in the probe.  */
 406       ret->probe_argc = DOF_UINT (dof, probe->dofpr_nargc);
 407
 408       /* Store argument type descriptions.  A description of the type
 409          of the argument is in the (J+1)th null-terminated string
 410          starting at 'strtab' + 'probe->dofpr_nargv'.  */
 411       ret->args = NULL;
 412       p = strtab + DOF_UINT (dof, probe->dofpr_nargv);
 413       for (j = 0; j < ret->probe_argc; j++)
 414         {
 415           struct dtrace_probe_arg arg;
 416           struct expression *expr;
 417
 418           arg.type_str = xstrdup (p);
 419
 420           /* Use strtab_size as a sentinel.  */
 421           while (*p++ != '\0' && p - strtab < strtab_size);
 422
 423           /* Try to parse a type expression from the type string.  If
 424              this does not work then we set the type to `long
 425              int'.  */
 426           arg.type = builtin_type (gdbarch)->builtin_long;
 427           expr = parse_expression (arg.type_str);
 428           if (expr->elts[0].opcode == OP_TYPE)
 429             arg.type = expr->elts[1].type;
 430
 431           VEC_safe_push (dtrace_probe_arg_s, ret->args, &arg);
 432         }
 433
 434       /* Add the vector of enablers to this probe, if any.  */
 435       ret->enablers = VEC_copy (dtrace_probe_enabler_s, enablers);
 436
 437       /* Successfully created probe.  */
 438       VEC_safe_push (probe_p, *probesp, (struct probe *) ret);
 439     }
 440
 441   do_cleanups (cleanup);
 442 }
 443
 444 /* Helper function to collect the probes described in the DOF program
 445    whose header is pointed by DOF and add them to the PROBESP vector.
 446    SECT is the ELF section containing the DOF program and OBJFILE is
 447    its containing object file.  */
 448
 449 static void
 450 dtrace_process_dof (asection *sect, struct objfile *objfile,
 451                     VEC (probe_p) **probesp, struct dtrace_dof_hdr *dof)
 452 {
 453   bfd *abfd = objfile->obfd;
 454   int size = bfd_get_arch_size (abfd) / 8;
 455   struct gdbarch *gdbarch = get_objfile_arch (objfile);
 456   struct dtrace_dof_sect *section;
 457   int i;
 458
 459   /* The first step is to check for the DOF magic number.  If no valid
 460      DOF data is found in the section then a complaint is issued to
 461      the user and the section skipped.  */
 462   if (dof->dofh_ident[DTRACE_DOF_ID_MAG0] != 0x7F
 463       || dof->dofh_ident[DTRACE_DOF_ID_MAG1] != 'D'
 464       || dof->dofh_ident[DTRACE_DOF_ID_MAG2] != 'O'
 465       || dof->dofh_ident[DTRACE_DOF_ID_MAG3] != 'F')
 466     goto invalid_dof_data;
 467
 468   /* Make sure the encoding mark is either DTRACE_DOF_ENCODE_LSB or
 469      DTRACE_DOF_ENCODE_MSB.  */
 470   if (dof->dofh_ident[DTRACE_DOF_ID_ENCODING] != DTRACE_DOF_ENCODE_LSB
 471       && dof->dofh_ident[DTRACE_DOF_ID_ENCODING] != DTRACE_DOF_ENCODE_MSB)
 472     goto invalid_dof_data;
 473
 474   /* Make sure this DOF is not an enabling DOF, i.e. there are no ECB
 475      Description sections.  */
 476   section = (struct dtrace_dof_sect *) DTRACE_DOF_PTR (dof,
 477                                                        DOF_UINT (dof, dof->dofh_secoff));
 478   for (i = 0; i < DOF_UINT (dof, dof->dofh_secnum); i++, section++)
 479     if (section->dofs_type == DTRACE_DOF_SECT_TYPE_ECBDESC)
 480       return;
 481
 482   /* Iterate over any section of type Provider and extract the probe
 483      information from them.  If there are no "provider" sections on
 484      the DOF then we just return.  */
 485   section = (struct dtrace_dof_sect *) DTRACE_DOF_PTR (dof,
 486                                                        DOF_UINT (dof, dof->dofh_secoff));
 487   for (i = 0; i < DOF_UINT (dof, dof->dofh_secnum); i++, section++)
 488     if (DOF_UINT (dof, section->dofs_type) == DTRACE_DOF_SECT_TYPE_PROVIDER)
 489       {
 490         struct dtrace_dof_provider *provider = (struct dtrace_dof_provider *)
 491           DTRACE_DOF_PTR (dof, DOF_UINT (dof, section->dofs_offset));
 492         struct dtrace_dof_sect *strtab_s
 493           = DTRACE_DOF_SECT (dof, DOF_UINT (dof, provider->dofpv_strtab));
 494         struct dtrace_dof_sect *probes_s
 495           = DTRACE_DOF_SECT (dof, DOF_UINT (dof, provider->dofpv_probes));
 496         struct dtrace_dof_sect *args_s
 497           = DTRACE_DOF_SECT (dof, DOF_UINT (dof, provider->dofpv_prargs));
 498         struct dtrace_dof_sect *offsets_s
 499           = DTRACE_DOF_SECT (dof, DOF_UINT (dof, provider->dofpv_proffs));
 500         struct dtrace_dof_sect *eoffsets_s
 501           = DTRACE_DOF_SECT (dof, DOF_UINT (dof, provider->dofpv_prenoffs));
 502         char *strtab  = DTRACE_DOF_PTR (dof, DOF_UINT (dof, strtab_s->dofs_offset));
 503         char *offtab  = DTRACE_DOF_PTR (dof, DOF_UINT (dof, offsets_s->dofs_offset));
 504         char *eofftab = DTRACE_DOF_PTR (dof, DOF_UINT (dof, eoffsets_s->dofs_offset));
 505         char *argtab  = DTRACE_DOF_PTR (dof, DOF_UINT (dof, args_s->dofs_offset));
 506         unsigned int entsize = DOF_UINT (dof, probes_s->dofs_entsize);
 507         int num_probes;
 508
 509         /* Very, unlikely, but could crash gdb if not handled
 510            properly.  */
 511         if (entsize == 0)
 512           goto invalid_dof_data;
 513
 514         num_probes = DOF_UINT (dof, probes_s->dofs_size) / entsize;
 515
 516         for (i = 0; i < num_probes; i++)
 517           {
 518             struct dtrace_dof_probe *probe = (struct dtrace_dof_probe *)
 519               DTRACE_DOF_PTR (dof, DOF_UINT (dof, probes_s->dofs_offset)
 520                               + (i * DOF_UINT (dof, probes_s->dofs_entsize)));
 521
 522             dtrace_process_dof_probe (objfile,
 523                                       gdbarch, probesp,
 524                                       dof, probe,
 525                                       provider, strtab, offtab, eofftab, argtab,
 526                                       DOF_UINT (dof, strtab_s->dofs_size));
 527           }
 528       }
 529
 530   return;
 531
 532  invalid_dof_data:
 533   complaint (&symfile_complaints,
 534              _("skipping section '%s' which does not contain valid DOF data."),
 535              sect->name);
 536 }
 537
 538 /* Helper function to build the GDB internal expressiosn that, once
 539    evaluated, will calculate the values of the arguments of a given
 540    PROBE.  */
 541
 542 static void
 543 dtrace_build_arg_exprs (struct dtrace_probe *probe,
 544                         struct gdbarch *gdbarch)
 545 {
 546   struct parser_state pstate;
 547   struct dtrace_probe_arg *arg;
 548   int i;
 549
 550   probe->args_expr_built = 1;
 551
 552   /* Iterate over the arguments in the probe and build the
 553      corresponding GDB internal expression that will generate the
 554      value of the argument when executed at the PC of the probe.  */
 555   for (i = 0; i < probe->probe_argc; i++)
 556     {
 557       struct cleanup *back_to;
 558
 559       arg = VEC_index (dtrace_probe_arg_s, probe->args, i);
 560
 561       /* Initialize the expression buffer in the parser state.  The
 562          language does not matter, since we are using our own
 563          parser.  */
 564       initialize_expout (&pstate, 10, current_language, gdbarch);
 565       back_to = make_cleanup (free_current_contents, &pstate.expout);
 566
 567       /* The argument value, which is ABI dependent and casted to
 568          `long int'.  */
 569       gdbarch_dtrace_parse_probe_argument (gdbarch, &pstate, i);
 570
 571       discard_cleanups (back_to);
 572
 573       /* Casting to the expected type, but only if the type was
 574          recognized at probe load time.  Otherwise the argument will
 575          be evaluated as the long integer passed to the probe.  */
 576       if (arg->type != NULL)
 577         {
 578           write_exp_elt_opcode (&pstate, UNOP_CAST);
 579           write_exp_elt_type (&pstate, arg->type);
 580           write_exp_elt_opcode (&pstate, UNOP_CAST);
 581         }
 582
 583       reallocate_expout (&pstate);
 584       arg->expr = pstate.expout;
 585       prefixify_expression (arg->expr);
 586     }
 587 }
 588
 589 /* Helper function to return the Nth argument of a given PROBE.  */
 590
 591 static struct dtrace_probe_arg *
 592 dtrace_get_arg (struct dtrace_probe *probe, unsigned n,
 593                 struct gdbarch *gdbarch)
 594 {
 595   if (!probe->args_expr_built)
 596     dtrace_build_arg_exprs (probe, gdbarch);
 597
 598   return VEC_index (dtrace_probe_arg_s, probe->args, n);
 599 }
 600
 601 /* Implementation of the get_probes method.  */
 602
 603 static void
 604 dtrace_get_probes (VEC (probe_p) **probesp, struct objfile *objfile)
 605 {
 606   bfd *abfd = objfile->obfd;
 607   asection *sect = NULL;
 608
 609   /* Do nothing in case this is a .debug file, instead of the objfile
 610      itself.  */
 611   if (objfile->separate_debug_objfile_backlink != NULL)
 612     return;
 613
 614   /* Iterate over the sections in OBJFILE looking for DTrace
 615      information.  */
 616   for (sect = abfd->sections; sect != NULL; sect = sect->next)
 617     {
 618       if (elf_section_data (sect)->this_hdr.sh_type == SHT_SUNW_dof)
 619         {
 620           struct dtrace_dof_hdr *dof;
 621
 622           /* Read the contents of the DOF section and then process it to
 623              extract the information of any probe defined into it.  */
 624           if (!bfd_malloc_and_get_section (abfd, sect, (bfd_byte **) &dof))
 625             complaint (&symfile_complaints,
 626                        _("could not obtain the contents of"
 627                          "section '%s' in objfile `%s'."),
 628                        sect->name, abfd->filename);
 629
 630           dtrace_process_dof (sect, objfile, probesp, dof);
 631           xfree (dof);
 632         }
 633     }
 634 }
 635
 636 /* Helper function to determine whether a given probe is "enabled" or
 637    "disabled".  A disabled probe is a probe in which one or more
 638    enablers are disabled.  */
 639
 640 static int
 641 dtrace_probe_is_enabled (struct dtrace_probe *probe)
 642 {
 643   int i;
 644   struct gdbarch *gdbarch = probe->p.arch;
 645   struct dtrace_probe_enabler *enabler;
 646
 647   for (i = 0;
 648        VEC_iterate (dtrace_probe_enabler_s, probe->enablers, i, enabler);
 649        i++)
 650     if (!gdbarch_dtrace_probe_is_enabled (gdbarch, enabler->address))
 651       return 0;
 652
 653   return 1;
 654 }
 655
 656 /* Implementation of the get_probe_address method.  */
 657
 658 static CORE_ADDR
 659 dtrace_get_probe_address (struct probe *probe, struct objfile *objfile)
 660 {
 661   gdb_assert (probe->pops == &dtrace_probe_ops);
 662   return probe->address + ANOFFSET (objfile->section_offsets,
 663                                     SECT_OFF_DATA (objfile));
 664 }
 665
 666 /* Implementation of the get_probe_argument_count method.  */
 667
 668 static unsigned
 669 dtrace_get_probe_argument_count (struct probe *probe_generic,
 670                                  struct frame_info *frame)
 671 {
 672   struct dtrace_probe *dtrace_probe = (struct dtrace_probe *) probe_generic;
 673
 674   gdb_assert (probe_generic->pops == &dtrace_probe_ops);
 675
 676   return dtrace_probe->probe_argc;
 677 }
 678
 679 /* Implementation of the can_evaluate_probe_arguments method.  */
 680
 681 static int
 682 dtrace_can_evaluate_probe_arguments (struct probe *probe_generic)
 683 {
 684   struct gdbarch *gdbarch = probe_generic->arch;
 685
 686   gdb_assert (probe_generic->pops == &dtrace_probe_ops);
 687   return gdbarch_dtrace_parse_probe_argument_p (gdbarch);
 688 }
 689
 690 /* Implementation of the evaluate_probe_argument method.  */
 691
 692 static struct value *
 693 dtrace_evaluate_probe_argument (struct probe *probe_generic, unsigned n,
 694                                 struct frame_info *frame)
 695 {
 696   struct gdbarch *gdbarch = probe_generic->arch;
 697   struct dtrace_probe *dtrace_probe = (struct dtrace_probe *) probe_generic;
 698   struct dtrace_probe_arg *arg;
 699   int pos = 0;
 700
 701   gdb_assert (probe_generic->pops == &dtrace_probe_ops);
 702
 703   arg = dtrace_get_arg (dtrace_probe, n, gdbarch);
 704   return evaluate_subexp_standard (arg->type, arg->expr, &pos, EVAL_NORMAL);
 705 }
 706
 707 /* Implementation of the compile_to_ax method.  */
 708
 709 static void
 710 dtrace_compile_to_ax (struct probe *probe_generic, struct agent_expr *expr,
 711                       struct axs_value *value, unsigned n)
 712 {
 713   struct dtrace_probe *dtrace_probe = (struct dtrace_probe *) probe_generic;
 714   struct dtrace_probe_arg *arg;
 715   union exp_element *pc;
 716
 717   gdb_assert (probe_generic->pops == &dtrace_probe_ops);
 718
 719   arg = dtrace_get_arg (dtrace_probe, n, expr->gdbarch);
 720
 721   pc = arg->expr->elts;
 722   gen_expr (arg->expr, &pc, expr, value);
 723
 724   require_rvalue (expr, value);
 725   value->type = arg->type;
 726 }
 727
 728 /* Implementation of the probe_destroy method.  */
 729
 730 static void
 731 dtrace_probe_destroy (struct probe *probe_generic)
 732 {
 733   struct dtrace_probe *probe = (struct dtrace_probe *) probe_generic;
 734   struct dtrace_probe_arg *arg;
 735   int i;
 736
 737   gdb_assert (probe_generic->pops == &dtrace_probe_ops);
 738
 739   for (i = 0; VEC_iterate (dtrace_probe_arg_s, probe->args, i, arg); i++)
 740     {
 741       xfree (arg->type_str);
 742       xfree (arg->expr);
 743     }
 744
 745   VEC_free (dtrace_probe_enabler_s, probe->enablers);
 746   VEC_free (dtrace_probe_arg_s, probe->args);
 747 }
 748
 749 /* Implementation of the type_name method.  */
 750
 751 static const char *
 752 dtrace_type_name (struct probe *probe_generic)
 753 {
 754   gdb_assert (probe_generic->pops == &dtrace_probe_ops);
 755   return "dtrace";
 756 }
 757
 758 /* Implementation of the gen_info_probes_table_header method.  */
 759
 760 static void
 761 dtrace_gen_info_probes_table_header (VEC (info_probe_column_s) **heads)
 762 {
 763   info_probe_column_s dtrace_probe_column;
 764
 765   dtrace_probe_column.field_name = "enabled";
 766   dtrace_probe_column.print_name = _("Enabled");
 767
 768   VEC_safe_push (info_probe_column_s, *heads, &dtrace_probe_column);
 769 }
 770
 771 /* Implementation of the gen_info_probes_table_values method.  */
 772
 773 static void
 774 dtrace_gen_info_probes_table_values (struct probe *probe_generic,
 775                                      VEC (const_char_ptr) **ret)
 776 {
 777   struct dtrace_probe *probe = (struct dtrace_probe *) probe_generic;
 778   const char *val = NULL;
 779
 780   gdb_assert (probe_generic->pops == &dtrace_probe_ops);
 781
 782   if (VEC_empty (dtrace_probe_enabler_s, probe->enablers))
 783     val = "always";
 784   else if (!gdbarch_dtrace_probe_is_enabled_p (probe_generic->arch))
 785     val = "unknown";
 786   else if (dtrace_probe_is_enabled (probe))
 787     val = "yes";
 788   else
 789     val = "no";
 790
 791   VEC_safe_push (const_char_ptr, *ret, val);
 792 }
 793
 794 /* Implementation of the enable_probe method.  */
 795
 796 static void
 797 dtrace_enable_probe (struct probe *probe)
 798 {
 799   struct gdbarch *gdbarch = probe->arch;
 800   struct dtrace_probe *dtrace_probe = (struct dtrace_probe *) probe;
 801   struct dtrace_probe_enabler *enabler;
 802   int i;
 803
 804   gdb_assert (probe->pops == &dtrace_probe_ops);
 805
 806   /* Enabling a dtrace probe implies patching the text section of the
 807      running process, so make sure the inferior is indeed running.  */
 808   if (ptid_equal (inferior_ptid, null_ptid))
 809     error (_("No inferior running"));
 810
 811   /* Fast path.  */
 812   if (dtrace_probe_is_enabled (dtrace_probe))
 813     return;
 814
 815   /* Iterate over all defined enabler in the given probe and enable
 816      them all using the corresponding gdbarch hook.  */
 817
 818   for (i = 0;
 819        VEC_iterate (dtrace_probe_enabler_s, dtrace_probe->enablers, i, enabler);
 820        i++)
 821     if (gdbarch_dtrace_enable_probe_p (gdbarch))
 822       gdbarch_dtrace_enable_probe (gdbarch, enabler->address);
 823 }
 824
 825
 826 /* Implementation of the disable_probe method.  */
 827
 828 static void
 829 dtrace_disable_probe (struct probe *probe)
 830 {
 831   struct gdbarch *gdbarch = probe->arch;
 832   struct dtrace_probe *dtrace_probe = (struct dtrace_probe *) probe;
 833   struct dtrace_probe_enabler *enabler;
 834   int i;
 835
 836   gdb_assert (probe->pops == &dtrace_probe_ops);
 837
 838   /* Disabling a dtrace probe implies patching the text section of the
 839      running process, so make sure the inferior is indeed running.  */
 840   if (ptid_equal (inferior_ptid, null_ptid))
 841     error (_("No inferior running"));
 842
 843   /* Fast path.  */
 844   if (!dtrace_probe_is_enabled (dtrace_probe))
 845     return;
 846
 847   /* Are we trying to disable a probe that does not have any enabler
 848      associated?  */
 849   if (VEC_empty (dtrace_probe_enabler_s, dtrace_probe->enablers))
 850     error (_("Probe %s:%s cannot be disabled: no enablers."), probe->provider, probe->name);
 851
 852   /* Iterate over all defined enabler in the given probe and disable
 853      them all using the corresponding gdbarch hook.  */
 854
 855   for (i = 0;
 856        VEC_iterate (dtrace_probe_enabler_s, dtrace_probe->enablers, i, enabler);
 857        i++)
 858     if (gdbarch_dtrace_disable_probe_p (gdbarch))
 859       gdbarch_dtrace_disable_probe (gdbarch, enabler->address);
 860 }
 861
 862 /* DTrace probe_ops.  */
 863
 864 static const struct probe_ops dtrace_probe_ops =
 865 {
 866   dtrace_probe_is_linespec,
 867   dtrace_get_probes,
 868   dtrace_get_probe_address,
 869   dtrace_get_probe_argument_count,
 870   dtrace_can_evaluate_probe_arguments,
 871   dtrace_evaluate_probe_argument,
 872   dtrace_compile_to_ax,
 873   NULL, /* set_semaphore  */
 874   NULL, /* clear_semaphore  */
 875   dtrace_probe_destroy,
 876   dtrace_type_name,
 877   dtrace_gen_info_probes_table_header,
 878   dtrace_gen_info_probes_table_values,
 879   dtrace_enable_probe,
 880   dtrace_disable_probe
 881 };
 882
 883 /* Implementation of the `info probes dtrace' command.  */
 884
 885 static void
 886 info_probes_dtrace_command (char *arg, int from_tty)
 887 {
 888   info_probes_for_ops (arg, from_tty, &dtrace_probe_ops);
 889 }
 890
 891 void _initialize_dtrace_probe (void);
 892
 893 void
 894 _initialize_dtrace_probe (void)
 895 {
 896   VEC_safe_push (probe_ops_cp, all_probe_ops, &dtrace_probe_ops);
 897
 898   add_cmd ("dtrace", class_info, info_probes_dtrace_command,
 899            _("\
 900 Show information about DTrace static probes.\n\
 901 Usage: info probes dtrace [PROVIDER [NAME [OBJECT]]]\n\
 902 Each argument is a regular expression, used to select probes.\n\
 903 PROVIDER matches probe provider names.\n\
 904 NAME matches the probe names.\n\
 905 OBJECT matches the executable or shared library name."),
 906            info_probes_cmdlist_get ());
 907 }