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 #include <list>
  31
  32 struct target_ops;
  33 struct bfd;
  34 struct objfile;
  35 struct inferior;
  36 struct exec;
  37 struct address_space;
  38 struct program_space_data;
  39 struct address_space_data;
  40
  41 /* A program space represents a symbolic view of an address space.
  42    Roughly speaking, it holds all the data associated with a
  43    non-running-yet program (main executable, main symbols), and when
  44    an inferior is running and is bound to it, includes the list of its
  45    mapped in shared libraries.
  46
  47    In the traditional debugging scenario, there's a 1-1 correspondence
  48    among program spaces, inferiors and address spaces, like so:
  49
  50      pspace1 (prog1) <--> inf1(pid1) <--> aspace1
  51
  52    In the case of debugging more than one traditional unix process or
  53    program, we still have:
  54
  55      |-----------------+------------+---------|
  56      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  57      |----------------------------------------|
  58      | pspace2 (prog1) | no inf yet | aspace2 |
  59      |-----------------+------------+---------|
  60      | pspace3 (prog2) | inf2(pid2) | aspace3 |
  61      |-----------------+------------+---------|
  62
  63    In the former example, if inf1 forks (and GDB stays attached to
  64    both processes), the new child will have its own program and
  65    address spaces.  Like so:
  66
  67      |-----------------+------------+---------|
  68      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  69      |-----------------+------------+---------|
  70      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  71      |-----------------+------------+---------|
  72
  73    However, had inf1 from the latter case vforked instead, it would
  74    share the program and address spaces with its parent, until it
  75    execs or exits, like so:
  76
  77      |-----------------+------------+---------|
  78      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  79      |                 | inf2(pid2) |         |
  80      |-----------------+------------+---------|
  81
  82    When the vfork child execs, it is finally given new program and
  83    address spaces.
  84
  85      |-----------------+------------+---------|
  86      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  87      |-----------------+------------+---------|
  88      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  89      |-----------------+------------+---------|
  90
  91    There are targets where the OS (if any) doesn't provide memory
  92    management or VM protection, where all inferiors share the same
  93    address space --- e.g. uClinux.  GDB models this by having all
  94    inferiors share the same address space, but, giving each its own
  95    program space, like so:
  96
  97      |-----------------+------------+---------|
  98      | pspace1 (prog1) | inf1(pid1) |         |
  99      |-----------------+------------+         |
 100      | pspace2 (prog1) | inf2(pid2) | aspace1 |
 101      |-----------------+------------+         |
 102      | pspace3 (prog2) | inf3(pid3) |         |
 103      |-----------------+------------+---------|
 104
 105    The address space sharing matters for run control and breakpoints
 106    management.  E.g., did we just hit a known breakpoint that we need
 107    to step over?  Is this breakpoint a duplicate of this other one, or
 108    do I need to insert a trap?
 109
 110    Then, there are targets where all symbols look the same for all
 111    inferiors, although each has its own address space, as e.g.,
 112    Ericsson DICOS.  In such case, the model is:
 113
 114      |---------+------------+---------|
 115      |         | inf1(pid1) | aspace1 |
 116      |         +------------+---------|
 117      | pspace  | inf2(pid2) | aspace2 |
 118      |         +------------+---------|
 119      |         | inf3(pid3) | aspace3 |
 120      |---------+------------+---------|
 121
 122    Note however, that the DICOS debug API takes care of making GDB
 123    believe that breakpoints are "global".  That is, although each
 124    process does have its own private copy of data symbols (just like a
 125    bunch of forks), to the breakpoints module, all processes share a
 126    single address space, so all breakpoints set at the same address
 127    are duplicates of each other, even breakpoints set in the data
 128    space (e.g., call dummy breakpoints placed on stack).  This allows
 129    a simplification in the spaces implementation: we avoid caring for
 130    a many-many links between address and program spaces.  Either
 131    there's a single address space bound to the program space
 132    (traditional unix/uClinux), or, in the DICOS case, the address
 133    space bound to the program space is mostly ignored.  */
 134
 135 /* The program space structure.  */
 136
 137 struct program_space
 138 {
 139   program_space (address_space *aspace_);
 140   ~program_space ();
 141
 142   typedef std::list<struct objfile *> objfiles_range;
 143
 144   /* Return an iterable object that can be used to iterate over all
 145      objfiles.  The basic use is in a foreach, like:
 146
 147      for (objfile *objf : pspace->objfiles ()) { ... }  */
 148   objfiles_range &objfiles ()
 149   {
 150     return objfiles_list;
 151   }
 152
 153   typedef basic_safe_range<objfiles_range> objfiles_safe_range;
 154
 155   /* An iterable object that can be used to iterate over all objfiles.
 156      The basic use is in a foreach, like:
 157
 158      for (objfile *objf : pspace->objfiles_safe ()) { ... }
 159
 160      This variant uses a basic_safe_iterator so that objfiles can be
 161      deleted during iteration.  */
 162   objfiles_safe_range objfiles_safe ()
 163   {
 164     return objfiles_safe_range (objfiles_list);
 165   }
 166
 167   /* Add OBJFILE to the list of objfiles, putting it just before
 168      BEFORE.  If BEFORE is nullptr, it will go at the end of the
 169      list.  */
 170   void add_objfile (struct objfile *objfile, struct objfile *before);
 171
 172   /* Remove OBJFILE from the list of objfiles.  */
 173   void remove_objfile (struct objfile *objfile);
 174
 175   /* Return true if there is more than one object file loaded; false
 176      otherwise.  */
 177   bool multi_objfile_p () const
 178   {
 179     return objfiles_list.size () > 1;
 180   }
 181
 182
 183   /* Pointer to next in linked list.  */
 184   struct program_space *next = NULL;
 185
 186   /* Unique ID number.  */
 187   int num = 0;
 188
 189   /* The main executable loaded into this program space.  This is
 190      managed by the exec target.  */
 191
 192   /* The BFD handle for the main executable.  */
 193   bfd *ebfd = NULL;
 194   /* The last-modified time, from when the exec was brought in.  */
 195   long ebfd_mtime = 0;
 196   /* Similar to bfd_get_filename (exec_bfd) but in original form given
 197      by user, without symbolic links and pathname resolved.
 198      It needs to be freed by xfree.  It is not NULL iff EBFD is not NULL.  */
 199   char *pspace_exec_filename = NULL;
 200
 201   /* Binary file diddling handle for the core file.  */
 202   gdb_bfd_ref_ptr cbfd;
 203
 204   /* The address space attached to this program space.  More than one
 205      program space may be bound to the same address space.  In the
 206      traditional unix-like debugging scenario, this will usually
 207      match the address space bound to the inferior, and is mostly
 208      used by the breakpoints module for address matches.  If the
 209      target shares a program space for all inferiors and breakpoints
 210      are global, then this field is ignored (we don't currently
 211      support inferiors sharing a program space if the target doesn't
 212      make breakpoints global).  */
 213   struct address_space *aspace = NULL;
 214
 215   /* True if this program space's section offsets don't yet represent
 216      the final offsets of the "live" address space (that is, the
 217      section addresses still require the relocation offsets to be
 218      applied, and hence we can't trust the section addresses for
 219      anything that pokes at live memory).  E.g., for qOffsets
 220      targets, or for PIE executables, until we connect and ask the
 221      target for the final relocation offsets, the symbols we've used
 222      to set breakpoints point at the wrong addresses.  */
 223   int executing_startup = 0;
 224
 225   /* True if no breakpoints should be inserted in this program
 226      space.  */
 227   int breakpoints_not_allowed = 0;
 228
 229   /* The object file that the main symbol table was loaded from
 230      (e.g. the argument to the "symbol-file" or "file" command).  */
 231   struct objfile *symfile_object_file = NULL;
 232
 233   /* All known objfiles are kept in a linked list.  */
 234   std::list<struct objfile *> objfiles_list;
 235
 236   /* The set of target sections matching the sections mapped into
 237      this program space.  Managed by both exec_ops and solib.c.  */
 238   struct target_section_table target_sections {};
 239
 240   /* List of shared objects mapped into this space.  Managed by
 241      solib.c.  */
 242   struct so_list *so_list = NULL;
 243
 244   /* Number of calls to solib_add.  */
 245   unsigned int solib_add_generation = 0;
 246
 247   /* When an solib is added, it is also added to this vector.  This
 248      is so we can properly report solib changes to the user.  */
 249   std::vector<struct so_list *> added_solibs;
 250
 251   /* When an solib is removed, its name is added to this vector.
 252      This is so we can properly report solib changes to the user.  */
 253   std::vector<std::string> deleted_solibs;
 254
 255   /* Per pspace data-pointers required by other GDB modules.  */
 256   REGISTRY_FIELDS {};
 257 };
 258
 259 /* An address space.  It is used for comparing if
 260    pspaces/inferior/threads see the same address space and for
 261    associating caches to each address space.  */
 262 struct address_space
 263 {
 264   int num;
 265
 266   /* Per aspace data-pointers required by other GDB modules.  */
 267   REGISTRY_FIELDS;
 268 };
 269
 270 /* The object file that the main symbol table was loaded from (e.g. the
 271    argument to the "symbol-file" or "file" command).  */
 272
 273 #define symfile_objfile current_program_space->symfile_object_file
 274
 275 /* The set of target sections matching the sections mapped into the
 276    current program space.  */
 277 #define current_target_sections (&current_program_space->target_sections)
 278
 279 /* The list of all program spaces.  There's always at least one.  */
 280 extern struct program_space *program_spaces;
 281
 282 /* The current program space.  This is always non-null.  */
 283 extern struct program_space *current_program_space;
 284
 285 #define ALL_PSPACES(pspace) \
 286   for ((pspace) = program_spaces; (pspace) != NULL; (pspace) = (pspace)->next)
 287
 288 /* Remove a program space from the program spaces list and release it.  It is
 289    an error to call this function while PSPACE is the current program space. */
 290 extern void delete_program_space (struct program_space *pspace);
 291
 292 /* Returns the number of program spaces listed.  */
 293 extern int number_of_program_spaces (void);
 294
 295 /* Returns true iff there's no inferior bound to PSPACE.  */
 296 extern int program_space_empty_p (struct program_space *pspace);
 297
 298 /* Copies program space SRC to DEST.  Copies the main executable file,
 299    and the main symbol file.  Returns DEST.  */
 300 extern struct program_space *clone_program_space (struct program_space *dest,
 301                                                 struct program_space *src);
 302
 303 /* Sets PSPACE as the current program space.  This is usually used
 304    instead of set_current_space_and_thread when the current
 305    thread/inferior is not important for the operations that follow.
 306    E.g., when accessing the raw symbol tables.  If memory access is
 307    required, then you should use switch_to_program_space_and_thread.
 308    Otherwise, it is the caller's responsibility to make sure that the
 309    currently selected inferior/thread matches the selected program
 310    space.  */
 311 extern void set_current_program_space (struct program_space *pspace);
 312
 313 /* Save/restore the current program space.  */
 314
 315 class scoped_restore_current_program_space
 316 {
 317 public:
 318   scoped_restore_current_program_space ()
 319     : m_saved_pspace (current_program_space)
 320   {}
 321
 322   ~scoped_restore_current_program_space ()
 323   { set_current_program_space (m_saved_pspace); }
 324
 325   DISABLE_COPY_AND_ASSIGN (scoped_restore_current_program_space);
 326
 327 private:
 328   program_space *m_saved_pspace;
 329 };
 330
 331 /* Create a new address space object, and add it to the list.  */
 332 extern struct address_space *new_address_space (void);
 333
 334 /* Maybe create a new address space object, and add it to the list, or
 335    return a pointer to an existing address space, in case inferiors
 336    share an address space.  */
 337 extern struct address_space *maybe_new_address_space (void);
 338
 339 /* Returns the integer address space id of ASPACE.  */
 340 extern int address_space_num (struct address_space *aspace);
 341
 342 /* Update all program spaces matching to address spaces.  The user may
 343    have created several program spaces, and loaded executables into
 344    them before connecting to the target interface that will create the
 345    inferiors.  All that happens before GDB has a chance to know if the
 346    inferiors will share an address space or not.  Call this after
 347    having connected to the target interface and having fetched the
 348    target description, to fixup the program/address spaces
 349    mappings.  */
 350 extern void update_address_spaces (void);
 351
 352 /* Reset saved solib data at the start of an solib event.  This lets
 353    us properly collect the data when calling solib_add, so it can then
 354    later be printed.  */
 355 extern void clear_program_space_solib_cache (struct program_space *);
 356
 357 /* Keep a registry of per-pspace data-pointers required by other GDB
 358    modules.  */
 359
 360 DECLARE_REGISTRY (program_space);
 361
 362 /* Keep a registry of per-aspace data-pointers required by other GDB
 363    modules.  */
 364
 365 DECLARE_REGISTRY (address_space);
 366
 367 #endif