gdb/progspace.h

   1 /* Program and address space management, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2009-2019 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
  21 #ifndef PROGSPACE_H
  22 #define PROGSPACE_H
  23
  24 #include "target.h"
  25 #include "gdb_bfd.h"
  26 #include "gdbsupport/gdb_vecs.h"
  27 #include "registry.h"
  28 #include "gdbsupport/next-iterator.h"
  29 #include "gdbsupport/safe-iterator.h"
  30
  31 struct target_ops;
  32 struct bfd;
  33 struct objfile;
  34 struct inferior;
  35 struct exec;
  36 struct address_space;
  37 struct program_space_data;
  38 struct address_space_data;
  39
  40 /* A program space represents a symbolic view of an address space.
  41    Roughly speaking, it holds all the data associated with a
  42    non-running-yet program (main executable, main symbols), and when
  43    an inferior is running and is bound to it, includes the list of its
  44    mapped in shared libraries.
  45
  46    In the traditional debugging scenario, there's a 1-1 correspondence
  47    among program spaces, inferiors and address spaces, like so:
  48
  49      pspace1 (prog1) <--> inf1(pid1) <--> aspace1
  50
  51    In the case of debugging more than one traditional unix process or
  52    program, we still have:
  53
  54      |-----------------+------------+---------|
  55      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  56      |----------------------------------------|
  57      | pspace2 (prog1) | no inf yet | aspace2 |
  58      |-----------------+------------+---------|
  59      | pspace3 (prog2) | inf2(pid2) | aspace3 |
  60      |-----------------+------------+---------|
  61
  62    In the former example, if inf1 forks (and GDB stays attached to
  63    both processes), the new child will have its own program and
  64    address spaces.  Like so:
  65
  66      |-----------------+------------+---------|
  67      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  68      |-----------------+------------+---------|
  69      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  70      |-----------------+------------+---------|
  71
  72    However, had inf1 from the latter case vforked instead, it would
  73    share the program and address spaces with its parent, until it
  74    execs or exits, like so:
  75
  76      |-----------------+------------+---------|
  77      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  78      |                 | inf2(pid2) |         |
  79      |-----------------+------------+---------|
  80
  81    When the vfork child execs, it is finally given new program and
  82    address spaces.
  83
  84      |-----------------+------------+---------|
  85      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  86      |-----------------+------------+---------|
  87      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  88      |-----------------+------------+---------|
  89
  90    There are targets where the OS (if any) doesn't provide memory
  91    management or VM protection, where all inferiors share the same
  92    address space --- e.g. uClinux.  GDB models this by having all
  93    inferiors share the same address space, but, giving each its own
  94    program space, like so:
  95
  96      |-----------------+------------+---------|
  97      | pspace1 (prog1) | inf1(pid1) |         |
  98      |-----------------+------------+         |
  99      | pspace2 (prog1) | inf2(pid2) | aspace1 |
 100      |-----------------+------------+         |
 101      | pspace3 (prog2) | inf3(pid3) |         |
 102      |-----------------+------------+---------|
 103
 104    The address space sharing matters for run control and breakpoints
 105    management.  E.g., did we just hit a known breakpoint that we need
 106    to step over?  Is this breakpoint a duplicate of this other one, or
 107    do I need to insert a trap?
 108
 109    Then, there are targets where all symbols look the same for all
 110    inferiors, although each has its own address space, as e.g.,
 111    Ericsson DICOS.  In such case, the model is:
 112
 113      |---------+------------+---------|
 114      |         | inf1(pid1) | aspace1 |
 115      |         +------------+---------|
 116      | pspace  | inf2(pid2) | aspace2 |
 117      |         +------------+---------|
 118      |         | inf3(pid3) | aspace3 |
 119      |---------+------------+---------|
 120
 121    Note however, that the DICOS debug API takes care of making GDB
 122    believe that breakpoints are "global".  That is, although each
 123    process does have its own private copy of data symbols (just like a
 124    bunch of forks), to the breakpoints module, all processes share a
 125    single address space, so all breakpoints set at the same address
 126    are duplicates of each other, even breakpoints set in the data
 127    space (e.g., call dummy breakpoints placed on stack).  This allows
 128    a simplification in the spaces implementation: we avoid caring for
 129    a many-many links between address and program spaces.  Either
 130    there's a single address space bound to the program space
 131    (traditional unix/uClinux), or, in the DICOS case, the address
 132    space bound to the program space is mostly ignored.  */
 133
 134 /* The program space structure.  */
 135
 136 struct program_space
 137 {
 138   program_space (address_space *aspace_);
 139   ~program_space ();
 140
 141   typedef next_adapter<struct objfile> objfiles_range;
 142
 143   /* Return an iterable object that can be used to iterate over all
 144      objfiles.  The basic use is in a foreach, like:
 145
 146      for (objfile *objf : pspace->objfiles ()) { ... }  */
 147   objfiles_range objfiles ()
 148   {
 149     return objfiles_range (objfiles_head);
 150   }
 151
 152   typedef next_adapter<struct objfile,
 153                        basic_safe_iterator<next_iterator<objfile>>>
 154     objfiles_safe_range;
 155
 156   /* An iterable object that can be used to iterate over all objfiles.
 157      The basic use is in a foreach, like:
 158
 159      for (objfile *objf : pspace->objfiles_safe ()) { ... }
 160
 161      This variant uses a basic_safe_iterator so that objfiles can be
 162      deleted during iteration.  */
 163   objfiles_safe_range objfiles_safe ()
 164   {
 165     return objfiles_safe_range (objfiles_head);
 166   }
 167
 168   /* Pointer to next in linked list.  */
 169   struct program_space *next = NULL;
 170
 171   /* Unique ID number.  */
 172   int num = 0;
 173
 174   /* The main executable loaded into this program space.  This is
 175      managed by the exec target.  */
 176
 177   /* The BFD handle for the main executable.  */
 178   bfd *ebfd = NULL;
 179   /* The last-modified time, from when the exec was brought in.  */
 180   long ebfd_mtime = 0;
 181   /* Similar to bfd_get_filename (exec_bfd) but in original form given
 182      by user, without symbolic links and pathname resolved.
 183      It needs to be freed by xfree.  It is not NULL iff EBFD is not NULL.  */
 184   char *pspace_exec_filename = NULL;
 185
 186   /* Binary file diddling handle for the core file.  */
 187   gdb_bfd_ref_ptr cbfd;
 188
 189   /* The address space attached to this program space.  More than one
 190      program space may be bound to the same address space.  In the
 191      traditional unix-like debugging scenario, this will usually
 192      match the address space bound to the inferior, and is mostly
 193      used by the breakpoints module for address matches.  If the
 194      target shares a program space for all inferiors and breakpoints
 195      are global, then this field is ignored (we don't currently
 196      support inferiors sharing a program space if the target doesn't
 197      make breakpoints global).  */
 198   struct address_space *aspace = NULL;
 199
 200   /* True if this program space's section offsets don't yet represent
 201      the final offsets of the "live" address space (that is, the
 202      section addresses still require the relocation offsets to be
 203      applied, and hence we can't trust the section addresses for
 204      anything that pokes at live memory).  E.g., for qOffsets
 205      targets, or for PIE executables, until we connect and ask the
 206      target for the final relocation offsets, the symbols we've used
 207      to set breakpoints point at the wrong addresses.  */
 208   int executing_startup = 0;
 209
 210   /* True if no breakpoints should be inserted in this program
 211      space.  */
 212   int breakpoints_not_allowed = 0;
 213
 214   /* The object file that the main symbol table was loaded from
 215      (e.g. the argument to the "symbol-file" or "file" command).  */
 216   struct objfile *symfile_object_file = NULL;
 217
 218   /* All known objfiles are kept in a linked list.  This points to
 219      the head of this list.  */
 220   struct objfile *objfiles_head = NULL;
 221
 222   /* The set of target sections matching the sections mapped into
 223      this program space.  Managed by both exec_ops and solib.c.  */
 224   struct target_section_table target_sections {};
 225
 226   /* List of shared objects mapped into this space.  Managed by
 227      solib.c.  */
 228   struct so_list *so_list = NULL;
 229
 230   /* Number of calls to solib_add.  */
 231   unsigned int solib_add_generation = 0;
 232
 233   /* When an solib is added, it is also added to this vector.  This
 234      is so we can properly report solib changes to the user.  */
 235   std::vector<struct so_list *> added_solibs;
 236
 237   /* When an solib is removed, its name is added to this vector.
 238      This is so we can properly report solib changes to the user.  */
 239   std::vector<std::string> deleted_solibs;
 240
 241   /* Per pspace data-pointers required by other GDB modules.  */
 242   REGISTRY_FIELDS {};
 243 };
 244
 245 /* An address space.  It is used for comparing if
 246    pspaces/inferior/threads see the same address space and for
 247    associating caches to each address space.  */
 248 struct address_space
 249 {
 250   int num;
 251
 252   /* Per aspace data-pointers required by other GDB modules.  */
 253   REGISTRY_FIELDS;
 254 };
 255
 256 /* The object file that the main symbol table was loaded from (e.g. the
 257    argument to the "symbol-file" or "file" command).  */
 258
 259 #define symfile_objfile current_program_space->symfile_object_file
 260
 261 /* All known objfiles are kept in a linked list.  This points to the
 262    root of this list.  */
 263 #define object_files current_program_space->objfiles_head
 264
 265 /* The set of target sections matching the sections mapped into the
 266    current program space.  */
 267 #define current_target_sections (&current_program_space->target_sections)
 268
 269 /* The list of all program spaces.  There's always at least one.  */
 270 extern struct program_space *program_spaces;
 271
 272 /* The current program space.  This is always non-null.  */
 273 extern struct program_space *current_program_space;
 274
 275 #define ALL_PSPACES(pspace) \
 276   for ((pspace) = program_spaces; (pspace) != NULL; (pspace) = (pspace)->next)
 277
 278 /* Remove a program space from the program spaces list and release it.  It is
 279    an error to call this function while PSPACE is the current program space. */
 280 extern void delete_program_space (struct program_space *pspace);
 281
 282 /* Returns the number of program spaces listed.  */
 283 extern int number_of_program_spaces (void);
 284
 285 /* Returns true iff there's no inferior bound to PSPACE.  */
 286 extern int program_space_empty_p (struct program_space *pspace);
 287
 288 /* Copies program space SRC to DEST.  Copies the main executable file,
 289    and the main symbol file.  Returns DEST.  */
 290 extern struct program_space *clone_program_space (struct program_space *dest,
 291                                                 struct program_space *src);
 292
 293 /* Sets PSPACE as the current program space.  This is usually used
 294    instead of set_current_space_and_thread when the current
 295    thread/inferior is not important for the operations that follow.
 296    E.g., when accessing the raw symbol tables.  If memory access is
 297    required, then you should use switch_to_program_space_and_thread.
 298    Otherwise, it is the caller's responsibility to make sure that the
 299    currently selected inferior/thread matches the selected program
 300    space.  */
 301 extern void set_current_program_space (struct program_space *pspace);
 302
 303 /* Save/restore the current program space.  */
 304
 305 class scoped_restore_current_program_space
 306 {
 307 public:
 308   scoped_restore_current_program_space ()
 309     : m_saved_pspace (current_program_space)
 310   {}
 311
 312   ~scoped_restore_current_program_space ()
 313   { set_current_program_space (m_saved_pspace); }
 314
 315   DISABLE_COPY_AND_ASSIGN (scoped_restore_current_program_space);
 316
 317 private:
 318   program_space *m_saved_pspace;
 319 };
 320
 321 /* Create a new address space object, and add it to the list.  */
 322 extern struct address_space *new_address_space (void);
 323
 324 /* Maybe create a new address space object, and add it to the list, or
 325    return a pointer to an existing address space, in case inferiors
 326    share an address space.  */
 327 extern struct address_space *maybe_new_address_space (void);
 328
 329 /* Returns the integer address space id of ASPACE.  */
 330 extern int address_space_num (struct address_space *aspace);
 331
 332 /* Update all program spaces matching to address spaces.  The user may
 333    have created several program spaces, and loaded executables into
 334    them before connecting to the target interface that will create the
 335    inferiors.  All that happens before GDB has a chance to know if the
 336    inferiors will share an address space or not.  Call this after
 337    having connected to the target interface and having fetched the
 338    target description, to fixup the program/address spaces
 339    mappings.  */
 340 extern void update_address_spaces (void);
 341
 342 /* Reset saved solib data at the start of an solib event.  This lets
 343    us properly collect the data when calling solib_add, so it can then
 344    later be printed.  */
 345 extern void clear_program_space_solib_cache (struct program_space *);
 346
 347 /* Keep a registry of per-pspace data-pointers required by other GDB
 348    modules.  */
 349
 350 DECLARE_REGISTRY (program_space);
 351
 352 /* Keep a registry of per-aspace data-pointers required by other GDB
 353    modules.  */
 354
 355 DECLARE_REGISTRY (address_space);
 356
 357 #endif