gdb/progspace.h

   1 /* Program and address space management, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2009-2020 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 typedef std::list<std::shared_ptr<objfile>> objfile_list;
  42
  43 /* An iterator that wraps an iterator over std::shared_ptr<objfile>,
  44    and dereferences the returned object.  This is useful for iterating
  45    over a list of shared pointers and returning raw pointers -- which
  46    helped avoid touching a lot of code when changing how objfiles are
  47    managed.  */
  48
  49 class unwrapping_objfile_iterator
  50 {
  51 public:
  52
  53   typedef unwrapping_objfile_iterator self_type;
  54   typedef typename ::objfile *value_type;
  55   typedef typename ::objfile &reference;
  56   typedef typename ::objfile **pointer;
  57   typedef typename objfile_list::iterator::iterator_category iterator_category;
  58   typedef typename objfile_list::iterator::difference_type difference_type;
  59
  60   unwrapping_objfile_iterator (const objfile_list::iterator &iter)
  61     : m_iter (iter)
  62   {
  63   }
  64
  65   objfile *operator* () const
  66   {
  67     return m_iter->get ();
  68   }
  69
  70   unwrapping_objfile_iterator operator++ ()
  71   {
  72     ++m_iter;
  73     return *this;
  74   }
  75
  76   bool operator!= (const unwrapping_objfile_iterator &other) const
  77   {
  78     return m_iter != other.m_iter;
  79   }
  80
  81 private:
  82
  83   /* The underlying iterator.  */
  84   objfile_list::iterator m_iter;
  85 };
  86
  87
  88 /* A range that returns unwrapping_objfile_iterators.  */
  89
  90 struct unwrapping_objfile_range
  91 {
  92   typedef unwrapping_objfile_iterator iterator;
  93
  94   unwrapping_objfile_range (objfile_list &ol)
  95     : m_list (ol)
  96   {
  97   }
  98
  99   iterator begin () const
 100   {
 101     return iterator (m_list.begin ());
 102   }
 103
 104   iterator end () const
 105   {
 106     return iterator (m_list.end ());
 107   }
 108
 109 private:
 110
 111   objfile_list &m_list;
 112 };
 113
 114 /* A program space represents a symbolic view of an address space.
 115    Roughly speaking, it holds all the data associated with a
 116    non-running-yet program (main executable, main symbols), and when
 117    an inferior is running and is bound to it, includes the list of its
 118    mapped in shared libraries.
 119
 120    In the traditional debugging scenario, there's a 1-1 correspondence
 121    among program spaces, inferiors and address spaces, like so:
 122
 123      pspace1 (prog1) <--> inf1(pid1) <--> aspace1
 124
 125    In the case of debugging more than one traditional unix process or
 126    program, we still have:
 127
 128      |-----------------+------------+---------|
 129      | pspace1 (prog1) | inf1(pid1) | aspace1 |
 130      |----------------------------------------|
 131      | pspace2 (prog1) | no inf yet | aspace2 |
 132      |-----------------+------------+---------|
 133      | pspace3 (prog2) | inf2(pid2) | aspace3 |
 134      |-----------------+------------+---------|
 135
 136    In the former example, if inf1 forks (and GDB stays attached to
 137    both processes), the new child will have its own program and
 138    address spaces.  Like so:
 139
 140      |-----------------+------------+---------|
 141      | pspace1 (prog1) | inf1(pid1) | aspace1 |
 142      |-----------------+------------+---------|
 143      | pspace2 (prog1) | inf2(pid2) | aspace2 |
 144      |-----------------+------------+---------|
 145
 146    However, had inf1 from the latter case vforked instead, it would
 147    share the program and address spaces with its parent, until it
 148    execs or exits, like so:
 149
 150      |-----------------+------------+---------|
 151      | pspace1 (prog1) | inf1(pid1) | aspace1 |
 152      |                 | inf2(pid2) |         |
 153      |-----------------+------------+---------|
 154
 155    When the vfork child execs, it is finally given new program and
 156    address spaces.
 157
 158      |-----------------+------------+---------|
 159      | pspace1 (prog1) | inf1(pid1) | aspace1 |
 160      |-----------------+------------+---------|
 161      | pspace2 (prog1) | inf2(pid2) | aspace2 |
 162      |-----------------+------------+---------|
 163
 164    There are targets where the OS (if any) doesn't provide memory
 165    management or VM protection, where all inferiors share the same
 166    address space --- e.g. uClinux.  GDB models this by having all
 167    inferiors share the same address space, but, giving each its own
 168    program space, like so:
 169
 170      |-----------------+------------+---------|
 171      | pspace1 (prog1) | inf1(pid1) |         |
 172      |-----------------+------------+         |
 173      | pspace2 (prog1) | inf2(pid2) | aspace1 |
 174      |-----------------+------------+         |
 175      | pspace3 (prog2) | inf3(pid3) |         |
 176      |-----------------+------------+---------|
 177
 178    The address space sharing matters for run control and breakpoints
 179    management.  E.g., did we just hit a known breakpoint that we need
 180    to step over?  Is this breakpoint a duplicate of this other one, or
 181    do I need to insert a trap?
 182
 183    Then, there are targets where all symbols look the same for all
 184    inferiors, although each has its own address space, as e.g.,
 185    Ericsson DICOS.  In such case, the model is:
 186
 187      |---------+------------+---------|
 188      |         | inf1(pid1) | aspace1 |
 189      |         +------------+---------|
 190      | pspace  | inf2(pid2) | aspace2 |
 191      |         +------------+---------|
 192      |         | inf3(pid3) | aspace3 |
 193      |---------+------------+---------|
 194
 195    Note however, that the DICOS debug API takes care of making GDB
 196    believe that breakpoints are "global".  That is, although each
 197    process does have its own private copy of data symbols (just like a
 198    bunch of forks), to the breakpoints module, all processes share a
 199    single address space, so all breakpoints set at the same address
 200    are duplicates of each other, even breakpoints set in the data
 201    space (e.g., call dummy breakpoints placed on stack).  This allows
 202    a simplification in the spaces implementation: we avoid caring for
 203    a many-many links between address and program spaces.  Either
 204    there's a single address space bound to the program space
 205    (traditional unix/uClinux), or, in the DICOS case, the address
 206    space bound to the program space is mostly ignored.  */
 207
 208 /* The program space structure.  */
 209
 210 struct program_space
 211 {
 212   /* Constructs a new empty program space, binds it to ASPACE, and
 213      adds it to the program space list.  */
 214   explicit program_space (address_space *aspace);
 215
 216   /* Releases a program space, and all its contents (shared libraries,
 217      objfiles, and any other references to the program space in other
 218      modules).  It is an internal error to call this when the program
 219      space is the current program space, since there should always be
 220      a program space.  */
 221   ~program_space ();
 222
 223   typedef unwrapping_objfile_range objfiles_range;
 224
 225   /* Return an iterable object that can be used to iterate over all
 226      objfiles.  The basic use is in a foreach, like:
 227
 228      for (objfile *objf : pspace->objfiles ()) { ... }  */
 229   objfiles_range objfiles ()
 230   {
 231     return unwrapping_objfile_range (objfiles_list);
 232   }
 233
 234   typedef basic_safe_range<objfiles_range> objfiles_safe_range;
 235
 236   /* An iterable object that can be used to iterate over all objfiles.
 237      The basic use is in a foreach, like:
 238
 239      for (objfile *objf : pspace->objfiles_safe ()) { ... }
 240
 241      This variant uses a basic_safe_iterator so that objfiles can be
 242      deleted during iteration.  */
 243   objfiles_safe_range objfiles_safe ()
 244   {
 245     return objfiles_safe_range (objfiles_list);
 246   }
 247
 248   /* Add OBJFILE to the list of objfiles, putting it just before
 249      BEFORE.  If BEFORE is nullptr, it will go at the end of the
 250      list.  */
 251   void add_objfile (std::shared_ptr<objfile> &&objfile,
 252                     struct objfile *before);
 253
 254   /* Remove OBJFILE from the list of objfiles.  */
 255   void remove_objfile (struct objfile *objfile);
 256
 257   /* Return true if there is more than one object file loaded; false
 258      otherwise.  */
 259   bool multi_objfile_p () const
 260   {
 261     return objfiles_list.size () > 1;
 262   }
 263
 264   /* Free all the objfiles associated with this program space.  */
 265   void free_all_objfiles ();
 266
 267
 268   /* Pointer to next in linked list.  */
 269   struct program_space *next = NULL;
 270
 271   /* Unique ID number.  */
 272   int num = 0;
 273
 274   /* The main executable loaded into this program space.  This is
 275      managed by the exec target.  */
 276
 277   /* The BFD handle for the main executable.  */
 278   bfd *ebfd = NULL;
 279   /* The last-modified time, from when the exec was brought in.  */
 280   long ebfd_mtime = 0;
 281   /* Similar to bfd_get_filename (exec_bfd) but in original form given
 282      by user, without symbolic links and pathname resolved.
 283      It needs to be freed by xfree.  It is not NULL iff EBFD is not NULL.  */
 284   char *pspace_exec_filename = NULL;
 285
 286   /* Binary file diddling handle for the core file.  */
 287   gdb_bfd_ref_ptr cbfd;
 288
 289   /* The address space attached to this program space.  More than one
 290      program space may be bound to the same address space.  In the
 291      traditional unix-like debugging scenario, this will usually
 292      match the address space bound to the inferior, and is mostly
 293      used by the breakpoints module for address matches.  If the
 294      target shares a program space for all inferiors and breakpoints
 295      are global, then this field is ignored (we don't currently
 296      support inferiors sharing a program space if the target doesn't
 297      make breakpoints global).  */
 298   struct address_space *aspace = NULL;
 299
 300   /* True if this program space's section offsets don't yet represent
 301      the final offsets of the "live" address space (that is, the
 302      section addresses still require the relocation offsets to be
 303      applied, and hence we can't trust the section addresses for
 304      anything that pokes at live memory).  E.g., for qOffsets
 305      targets, or for PIE executables, until we connect and ask the
 306      target for the final relocation offsets, the symbols we've used
 307      to set breakpoints point at the wrong addresses.  */
 308   int executing_startup = 0;
 309
 310   /* True if no breakpoints should be inserted in this program
 311      space.  */
 312   int breakpoints_not_allowed = 0;
 313
 314   /* The object file that the main symbol table was loaded from
 315      (e.g. the argument to the "symbol-file" or "file" command).  */
 316   struct objfile *symfile_object_file = NULL;
 317
 318   /* All known objfiles are kept in a linked list.  */
 319   std::list<std::shared_ptr<objfile>> objfiles_list;
 320
 321   /* The set of target sections matching the sections mapped into
 322      this program space.  Managed by both exec_ops and solib.c.  */
 323   struct target_section_table target_sections {};
 324
 325   /* List of shared objects mapped into this space.  Managed by
 326      solib.c.  */
 327   struct so_list *so_list = NULL;
 328
 329   /* Number of calls to solib_add.  */
 330   unsigned int solib_add_generation = 0;
 331
 332   /* When an solib is added, it is also added to this vector.  This
 333      is so we can properly report solib changes to the user.  */
 334   std::vector<struct so_list *> added_solibs;
 335
 336   /* When an solib is removed, its name is added to this vector.
 337      This is so we can properly report solib changes to the user.  */
 338   std::vector<std::string> deleted_solibs;
 339
 340   /* Per pspace data-pointers required by other GDB modules.  */
 341   REGISTRY_FIELDS {};
 342 };
 343
 344 /* An address space.  It is used for comparing if
 345    pspaces/inferior/threads see the same address space and for
 346    associating caches to each address space.  */
 347 struct address_space
 348 {
 349   int num;
 350
 351   /* Per aspace data-pointers required by other GDB modules.  */
 352   REGISTRY_FIELDS;
 353 };
 354
 355 /* The object file that the main symbol table was loaded from (e.g. the
 356    argument to the "symbol-file" or "file" command).  */
 357
 358 #define symfile_objfile current_program_space->symfile_object_file
 359
 360 /* The set of target sections matching the sections mapped into the
 361    current program space.  */
 362 #define current_target_sections (&current_program_space->target_sections)
 363
 364 /* The list of all program spaces.  There's always at least one.  */
 365 extern struct program_space *program_spaces;
 366
 367 /* The current program space.  This is always non-null.  */
 368 extern struct program_space *current_program_space;
 369
 370 #define ALL_PSPACES(pspace) \
 371   for ((pspace) = program_spaces; (pspace) != NULL; (pspace) = (pspace)->next)
 372
 373 /* Returns the number of program spaces listed.  */
 374 extern int number_of_program_spaces (void);
 375
 376 /* Returns true iff there's no inferior bound to PSPACE.  */
 377 extern int program_space_empty_p (struct program_space *pspace);
 378
 379 /* Copies program space SRC to DEST.  Copies the main executable file,
 380    and the main symbol file.  Returns DEST.  */
 381 extern struct program_space *clone_program_space (struct program_space *dest,
 382                                                 struct program_space *src);
 383
 384 /* Sets PSPACE as the current program space.  This is usually used
 385    instead of set_current_space_and_thread when the current
 386    thread/inferior is not important for the operations that follow.
 387    E.g., when accessing the raw symbol tables.  If memory access is
 388    required, then you should use switch_to_program_space_and_thread.
 389    Otherwise, it is the caller's responsibility to make sure that the
 390    currently selected inferior/thread matches the selected program
 391    space.  */
 392 extern void set_current_program_space (struct program_space *pspace);
 393
 394 /* Save/restore the current program space.  */
 395
 396 class scoped_restore_current_program_space
 397 {
 398 public:
 399   scoped_restore_current_program_space ()
 400     : m_saved_pspace (current_program_space)
 401   {}
 402
 403   ~scoped_restore_current_program_space ()
 404   { set_current_program_space (m_saved_pspace); }
 405
 406   DISABLE_COPY_AND_ASSIGN (scoped_restore_current_program_space);
 407
 408 private:
 409   program_space *m_saved_pspace;
 410 };
 411
 412 /* Create a new address space object, and add it to the list.  */
 413 extern struct address_space *new_address_space (void);
 414
 415 /* Maybe create a new address space object, and add it to the list, or
 416    return a pointer to an existing address space, in case inferiors
 417    share an address space.  */
 418 extern struct address_space *maybe_new_address_space (void);
 419
 420 /* Returns the integer address space id of ASPACE.  */
 421 extern int address_space_num (struct address_space *aspace);
 422
 423 /* Update all program spaces matching to address spaces.  The user may
 424    have created several program spaces, and loaded executables into
 425    them before connecting to the target interface that will create the
 426    inferiors.  All that happens before GDB has a chance to know if the
 427    inferiors will share an address space or not.  Call this after
 428    having connected to the target interface and having fetched the
 429    target description, to fixup the program/address spaces
 430    mappings.  */
 431 extern void update_address_spaces (void);
 432
 433 /* Reset saved solib data at the start of an solib event.  This lets
 434    us properly collect the data when calling solib_add, so it can then
 435    later be printed.  */
 436 extern void clear_program_space_solib_cache (struct program_space *);
 437
 438 /* Keep a registry of per-pspace data-pointers required by other GDB
 439    modules.  */
 440
 441 DECLARE_REGISTRY (program_space);
 442
 443 /* Keep a registry of per-aspace data-pointers required by other GDB
 444    modules.  */
 445
 446 DECLARE_REGISTRY (address_space);
 447
 448 #endif