gdb/solib-target.c

   1 /* Definitions for targets which report shared library events.
   2
   3    Copyright (C) 2007-2021 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "objfiles.h"
  22 #include "solist.h"
  23 #include "symtab.h"
  24 #include "symfile.h"
  25 #include "target.h"
  26 #include "solib-target.h"
  27 #include <vector>
  28 #include "inferior.h"
  29
  30 /* Private data for each loaded library.  */
  31 struct lm_info_target : public lm_info_base
  32 {
  33   /* The library's name.  The name is normally kept in the struct
  34      so_list; it is only here during XML parsing.  */
  35   std::string name;
  36
  37   /* The target can either specify segment bases or section bases, not
  38      both.  */
  39
  40   /* The base addresses for each independently relocatable segment of
  41      this shared library.  */
  42   std::vector<CORE_ADDR> segment_bases;
  43
  44   /* The base addresses for each independently allocatable,
  45      relocatable section of this shared library.  */
  46   std::vector<CORE_ADDR> section_bases;
  47
  48   /* The cached offsets for each section of this shared library,
  49      determined from SEGMENT_BASES, or SECTION_BASES.  */
  50   section_offsets offsets;
  51 };
  52
  53 typedef std::vector<std::unique_ptr<lm_info_target>> lm_info_vector;
  54
  55 #if !defined(HAVE_LIBEXPAT)
  56
  57 static lm_info_vector
  58 solib_target_parse_libraries (const char *library)
  59 {
  60   static int have_warned;
  61
  62   if (!have_warned)
  63     {
  64       have_warned = 1;
  65       warning (_("Can not parse XML library list; XML support was disabled "
  66                  "at compile time"));
  67     }
  68
  69   return lm_info_vector ();
  70 }
  71
  72 #else /* HAVE_LIBEXPAT */
  73
  74 #include "xml-support.h"
  75
  76 /* Handle the start of a <segment> element.  */
  77
  78 static void
  79 library_list_start_segment (struct gdb_xml_parser *parser,
  80                             const struct gdb_xml_element *element,
  81                             void *user_data,
  82                             std::vector<gdb_xml_value> &attributes)
  83 {
  84   lm_info_vector *list = (lm_info_vector *) user_data;
  85   lm_info_target *last = list->back ().get ();
  86   ULONGEST *address_p
  87     = (ULONGEST *) xml_find_attribute (attributes, "address")->value.get ();
  88   CORE_ADDR address = (CORE_ADDR) *address_p;
  89
  90   if (!last->section_bases.empty ())
  91     gdb_xml_error (parser,
  92                    _("Library list with both segments and sections"));
  93
  94   last->segment_bases.push_back (address);
  95 }
  96
  97 static void
  98 library_list_start_section (struct gdb_xml_parser *parser,
  99                             const struct gdb_xml_element *element,
 100                             void *user_data,
 101                             std::vector<gdb_xml_value> &attributes)
 102 {
 103   lm_info_vector *list = (lm_info_vector *) user_data;
 104   lm_info_target *last = list->back ().get ();
 105   ULONGEST *address_p
 106     = (ULONGEST *) xml_find_attribute (attributes, "address")->value.get ();
 107   CORE_ADDR address = (CORE_ADDR) *address_p;
 108
 109   if (!last->segment_bases.empty ())
 110     gdb_xml_error (parser,
 111                    _("Library list with both segments and sections"));
 112
 113   last->section_bases.push_back (address);
 114 }
 115
 116 /* Handle the start of a <library> element.  */
 117
 118 static void
 119 library_list_start_library (struct gdb_xml_parser *parser,
 120                             const struct gdb_xml_element *element,
 121                             void *user_data,
 122                             std::vector<gdb_xml_value> &attributes)
 123 {
 124   lm_info_vector *list = (lm_info_vector *) user_data;
 125   lm_info_target *item = new lm_info_target;
 126   item->name
 127     = (const char *) xml_find_attribute (attributes, "name")->value.get ();
 128
 129   list->emplace_back (item);
 130 }
 131
 132 static void
 133 library_list_end_library (struct gdb_xml_parser *parser,
 134                           const struct gdb_xml_element *element,
 135                           void *user_data, const char *body_text)
 136 {
 137   lm_info_vector *list = (lm_info_vector *) user_data;
 138   lm_info_target *lm_info = list->back ().get ();
 139
 140   if (lm_info->segment_bases.empty () && lm_info->section_bases.empty ())
 141     gdb_xml_error (parser, _("No segment or section bases defined"));
 142 }
 143
 144
 145 /* Handle the start of a <library-list> element.  */
 146
 147 static void
 148 library_list_start_list (struct gdb_xml_parser *parser,
 149                          const struct gdb_xml_element *element,
 150                          void *user_data,
 151                          std::vector<gdb_xml_value> &attributes)
 152 {
 153   struct gdb_xml_value *version = xml_find_attribute (attributes, "version");
 154
 155   /* #FIXED attribute may be omitted, Expat returns NULL in such case.  */
 156   if (version != NULL)
 157     {
 158       const char *string = (const char *) version->value.get ();
 159
 160       if (strcmp (string, "1.0") != 0)
 161         gdb_xml_error (parser,
 162                        _("Library list has unsupported version \"%s\""),
 163                        string);
 164     }
 165 }
 166
 167 /* The allowed elements and attributes for an XML library list.
 168    The root element is a <library-list>.  */
 169
 170 static const struct gdb_xml_attribute segment_attributes[] = {
 171   { "address", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
 172   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 173 };
 174
 175 static const struct gdb_xml_attribute section_attributes[] = {
 176   { "address", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
 177   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 178 };
 179
 180 static const struct gdb_xml_element library_children[] = {
 181   { "segment", segment_attributes, NULL,
 182     GDB_XML_EF_REPEATABLE | GDB_XML_EF_OPTIONAL,
 183     library_list_start_segment, NULL },
 184   { "section", section_attributes, NULL,
 185     GDB_XML_EF_REPEATABLE | GDB_XML_EF_OPTIONAL,
 186     library_list_start_section, NULL },
 187   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
 188 };
 189
 190 static const struct gdb_xml_attribute library_attributes[] = {
 191   { "name", GDB_XML_AF_NONE, NULL, NULL },
 192   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 193 };
 194
 195 static const struct gdb_xml_element library_list_children[] = {
 196   { "library", library_attributes, library_children,
 197     GDB_XML_EF_REPEATABLE | GDB_XML_EF_OPTIONAL,
 198     library_list_start_library, library_list_end_library },
 199   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
 200 };
 201
 202 static const struct gdb_xml_attribute library_list_attributes[] = {
 203   { "version", GDB_XML_AF_OPTIONAL, NULL, NULL },
 204   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 205 };
 206
 207 static const struct gdb_xml_element library_list_elements[] = {
 208   { "library-list", library_list_attributes, library_list_children,
 209     GDB_XML_EF_NONE, library_list_start_list, NULL },
 210   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
 211 };
 212
 213 static lm_info_vector
 214 solib_target_parse_libraries (const char *library)
 215 {
 216   lm_info_vector result;
 217
 218   if (gdb_xml_parse_quick (_("target library list"), "library-list.dtd",
 219                            library_list_elements, library, &result) == 0)
 220     {
 221       /* Parsed successfully.  */
 222       return result;
 223     }
 224
 225   result.clear ();
 226   return result;
 227 }
 228 #endif
 229
 230 static struct so_list *
 231 solib_target_current_sos (void)
 232 {
 233   struct so_list *new_solib, *start = NULL, *last = NULL;
 234
 235   /* Fetch the list of shared libraries.  */
 236   gdb::optional<gdb::char_vector> library_document
 237     = target_read_stralloc (current_inferior ()->top_target (),
 238                             TARGET_OBJECT_LIBRARIES, NULL);
 239   if (!library_document)
 240     return NULL;
 241
 242   /* Parse the list.  */
 243   lm_info_vector library_list
 244     = solib_target_parse_libraries (library_document->data ());
 245
 246   if (library_list.empty ())
 247     return NULL;
 248
 249   /* Build a struct so_list for each entry on the list.  */
 250   for (auto &&info : library_list)
 251     {
 252       new_solib = XCNEW (struct so_list);
 253       strncpy (new_solib->so_name, info->name.c_str (),
 254                SO_NAME_MAX_PATH_SIZE - 1);
 255       new_solib->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
 256       strncpy (new_solib->so_original_name, info->name.c_str (),
 257                SO_NAME_MAX_PATH_SIZE - 1);
 258       new_solib->so_original_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';
 259
 260       /* We no longer need this copy of the name.  */
 261       info->name.clear ();
 262
 263       new_solib->lm_info = info.release ();
 264
 265       /* Add it to the list.  */
 266       if (!start)
 267         last = start = new_solib;
 268       else
 269         {
 270           last->next = new_solib;
 271           last = new_solib;
 272         }
 273     }
 274
 275   return start;
 276 }
 277
 278 static void
 279 solib_target_solib_create_inferior_hook (int from_tty)
 280 {
 281   /* Nothing needed.  */
 282 }
 283
 284 static void
 285 solib_target_clear_solib (void)
 286 {
 287   /* Nothing needed.  */
 288 }
 289
 290 static void
 291 solib_target_free_so (struct so_list *so)
 292 {
 293   lm_info_target *li = (lm_info_target *) so->lm_info;
 294
 295   gdb_assert (li->name.empty ());
 296
 297   delete li;
 298 }
 299
 300 static void
 301 solib_target_relocate_section_addresses (struct so_list *so,
 302                                          struct target_section *sec)
 303 {
 304   CORE_ADDR offset;
 305   lm_info_target *li = (lm_info_target *) so->lm_info;
 306
 307   /* Build the offset table only once per object file.  We can not do
 308      it any earlier, since we need to open the file first.  */
 309   if (li->offsets.empty ())
 310     {
 311       int num_sections = gdb_bfd_count_sections (so->abfd);
 312
 313       li->offsets.assign (num_sections, 0);
 314
 315       if (!li->section_bases.empty ())
 316         {
 317           int i;
 318           asection *sect;
 319           int num_alloc_sections = 0;
 320
 321           for (i = 0, sect = so->abfd->sections;
 322                sect != NULL;
 323                i++, sect = sect->next)
 324             if ((bfd_section_flags (sect) & SEC_ALLOC))
 325               num_alloc_sections++;
 326
 327           if (num_alloc_sections != li->section_bases.size ())
 328             warning (_("\
 329 Could not relocate shared library \"%s\": wrong number of ALLOC sections"),
 330                      so->so_name);
 331           else
 332             {
 333               int bases_index = 0;
 334               int found_range = 0;
 335
 336               so->addr_low = ~(CORE_ADDR) 0;
 337               so->addr_high = 0;
 338               for (i = 0, sect = so->abfd->sections;
 339                    sect != NULL;
 340                    i++, sect = sect->next)
 341                 {
 342                   if (!(bfd_section_flags (sect) & SEC_ALLOC))
 343                     continue;
 344                   if (bfd_section_size (sect) > 0)
 345                     {
 346                       CORE_ADDR low, high;
 347
 348                       low = li->section_bases[i];
 349                       high = low + bfd_section_size (sect) - 1;
 350
 351                       if (low < so->addr_low)
 352                         so->addr_low = low;
 353                       if (high > so->addr_high)
 354                         so->addr_high = high;
 355                       gdb_assert (so->addr_low <= so->addr_high);
 356                       found_range = 1;
 357                     }
 358                   li->offsets[i] = li->section_bases[bases_index];
 359                   bases_index++;
 360                 }
 361               if (!found_range)
 362                 so->addr_low = so->addr_high = 0;
 363               gdb_assert (so->addr_low <= so->addr_high);
 364             }
 365         }
 366       else if (!li->segment_bases.empty ())
 367         {
 368           symfile_segment_data_up data
 369             = get_symfile_segment_data (so->abfd);
 370
 371           if (data == NULL)
 372             warning (_("\
 373 Could not relocate shared library \"%s\": no segments"), so->so_name);
 374           else
 375             {
 376               ULONGEST orig_delta;
 377               int i;
 378
 379               if (!symfile_map_offsets_to_segments (so->abfd, data.get (),
 380                                                     li->offsets,
 381                                                     li->segment_bases.size (),
 382                                                     li->segment_bases.data ()))
 383                 warning (_("\
 384 Could not relocate shared library \"%s\": bad offsets"), so->so_name);
 385
 386               /* Find the range of addresses to report for this library in
 387                  "info sharedlibrary".  Report any consecutive segments
 388                  which were relocated as a single unit.  */
 389               gdb_assert (li->segment_bases.size () > 0);
 390               orig_delta = li->segment_bases[0] - data->segments[0].base;
 391
 392               for (i = 1; i < data->segments.size (); i++)
 393                 {
 394                   /* If we have run out of offsets, assume all
 395                      remaining segments have the same offset.  */
 396                   if (i >= li->segment_bases.size ())
 397                     continue;
 398
 399                   /* If this segment does not have the same offset, do
 400                      not include it in the library's range.  */
 401                   if (li->segment_bases[i] - data->segments[i].base
 402                       != orig_delta)
 403                     break;
 404                 }
 405
 406               so->addr_low = li->segment_bases[0];
 407               so->addr_high = (data->segments[i - 1].base
 408                                + data->segments[i - 1].size
 409                                + orig_delta);
 410               gdb_assert (so->addr_low <= so->addr_high);
 411             }
 412         }
 413     }
 414
 415   offset = li->offsets[gdb_bfd_section_index (sec->the_bfd_section->owner,
 416                                               sec->the_bfd_section)];
 417   sec->addr += offset;
 418   sec->endaddr += offset;
 419 }
 420
 421 static int
 422 solib_target_open_symbol_file_object (int from_tty)
 423 {
 424   /* We can't locate the main symbol file based on the target's
 425      knowledge; the user has to specify it.  */
 426   return 0;
 427 }
 428
 429 static int
 430 solib_target_in_dynsym_resolve_code (CORE_ADDR pc)
 431 {
 432   /* We don't have a range of addresses for the dynamic linker; there
 433      may not be one in the program's address space.  So only report
 434      PLT entries (which may be import stubs).  */
 435   return in_plt_section (pc);
 436 }
 437
 438 struct target_so_ops solib_target_so_ops;
 439
 440 void _initialize_solib_target ();
 441 void
 442 _initialize_solib_target ()
 443 {
 444   solib_target_so_ops.relocate_section_addresses
 445     = solib_target_relocate_section_addresses;
 446   solib_target_so_ops.free_so = solib_target_free_so;
 447   solib_target_so_ops.clear_solib = solib_target_clear_solib;
 448   solib_target_so_ops.solib_create_inferior_hook
 449     = solib_target_solib_create_inferior_hook;
 450   solib_target_so_ops.current_sos = solib_target_current_sos;
 451   solib_target_so_ops.open_symbol_file_object
 452     = solib_target_open_symbol_file_object;
 453   solib_target_so_ops.in_dynsym_resolve_code
 454     = solib_target_in_dynsym_resolve_code;
 455   solib_target_so_ops.bfd_open = solib_bfd_open;
 456
 457   /* Set current_target_so_ops to solib_target_so_ops if not already
 458      set.  */
 459   if (current_target_so_ops == 0)
 460     current_target_so_ops = &solib_target_so_ops;
 461 }