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 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   program_space (address_space *aspace_);
 213   ~program_space ();
 214
 215   typedef unwrapping_objfile_range objfiles_range;
 216
 217   /* Return an iterable object that can be used to iterate over all
 218      objfiles.  The basic use is in a foreach, like:
 219
 220      for (objfile *objf : pspace->objfiles ()) { ... }  */
 221   objfiles_range objfiles ()
 222   {
 223     return unwrapping_objfile_range (objfiles_list);
 224   }
 225
 226   typedef basic_safe_range<objfiles_range> objfiles_safe_range;
 227
 228   /* An iterable object that can be used to iterate over all objfiles.
 229      The basic use is in a foreach, like:
 230
 231      for (objfile *objf : pspace->objfiles_safe ()) { ... }
 232
 233      This variant uses a basic_safe_iterator so that objfiles can be
 234      deleted during iteration.  */
 235   objfiles_safe_range objfiles_safe ()
 236   {
 237     return objfiles_safe_range (objfiles_list);
 238   }
 239
 240   /* Add OBJFILE to the list of objfiles, putting it just before
 241      BEFORE.  If BEFORE is nullptr, it will go at the end of the
 242      list.  */
 243   void add_objfile (std::shared_ptr<objfile> &&objfile,
 244                     struct objfile *before);
 245
 246   /* Remove OBJFILE from the list of objfiles.  */
 247   void remove_objfile (struct objfile *objfile);
 248
 249   /* Return true if there is more than one object file loaded; false
 250      otherwise.  */
 251   bool multi_objfile_p () const
 252   {
 253     return objfiles_list.size () > 1;
 254   }
 255
 256   /* Free all the objfiles associated with this program space.  */
 257   void free_all_objfiles ();
 258
 259
 260   /* Pointer to next in linked list.  */
 261   struct program_space *next = NULL;
 262
 263   /* Unique ID number.  */
 264   int num = 0;
 265
 266   /* The main executable loaded into this program space.  This is
 267      managed by the exec target.  */
 268
 269   /* The BFD handle for the main executable.  */
 270   bfd *ebfd = NULL;
 271   /* The last-modified time, from when the exec was brought in.  */
 272   long ebfd_mtime = 0;
 273   /* Similar to bfd_get_filename (exec_bfd) but in original form given
 274      by user, without symbolic links and pathname resolved.
 275      It needs to be freed by xfree.  It is not NULL iff EBFD is not NULL.  */
 276   char *pspace_exec_filename = NULL;
 277
 278   /* Binary file diddling handle for the core file.  */
 279   gdb_bfd_ref_ptr cbfd;
 280
 281   /* The address space attached to this program space.  More than one
 282      program space may be bound to the same address space.  In the
 283      traditional unix-like debugging scenario, this will usually
 284      match the address space bound to the inferior, and is mostly
 285      used by the breakpoints module for address matches.  If the
 286      target shares a program space for all inferiors and breakpoints
 287      are global, then this field is ignored (we don't currently
 288      support inferiors sharing a program space if the target doesn't
 289      make breakpoints global).  */
 290   struct address_space *aspace = NULL;
 291
 292   /* True if this program space's section offsets don't yet represent
 293      the final offsets of the "live" address space (that is, the
 294      section addresses still require the relocation offsets to be
 295      applied, and hence we can't trust the section addresses for
 296      anything that pokes at live memory).  E.g., for qOffsets
 297      targets, or for PIE executables, until we connect and ask the
 298      target for the final relocation offsets, the symbols we've used
 299      to set breakpoints point at the wrong addresses.  */
 300   int executing_startup = 0;
 301
 302   /* True if no breakpoints should be inserted in this program
 303      space.  */
 304   int breakpoints_not_allowed = 0;
 305
 306   /* The object file that the main symbol table was loaded from
 307      (e.g. the argument to the "symbol-file" or "file" command).  */
 308   struct objfile *symfile_object_file = NULL;
 309
 310   /* All known objfiles are kept in a linked list.  */
 311   std::list<std::shared_ptr<objfile>> objfiles_list;
 312
 313   /* The set of target sections matching the sections mapped into
 314      this program space.  Managed by both exec_ops and solib.c.  */
 315   struct target_section_table target_sections {};
 316
 317   /* List of shared objects mapped into this space.  Managed by
 318      solib.c.  */
 319   struct so_list *so_list = NULL;
 320
 321   /* Number of calls to solib_add.  */
 322   unsigned int solib_add_generation = 0;
 323
 324   /* When an solib is added, it is also added to this vector.  This
 325      is so we can properly report solib changes to the user.  */
 326   std::vector<struct so_list *> added_solibs;
 327
 328   /* When an solib is removed, its name is added to this vector.
 329      This is so we can properly report solib changes to the user.  */
 330   std::vector<std::string> deleted_solibs;
 331
 332   /* Per pspace data-pointers required by other GDB modules.  */
 333   REGISTRY_FIELDS {};
 334 };
 335
 336 /* An address space.  It is used for comparing if
 337    pspaces/inferior/threads see the same address space and for
 338    associating caches to each address space.  */
 339 struct address_space
 340 {
 341   int num;
 342
 343   /* Per aspace data-pointers required by other GDB modules.  */
 344   REGISTRY_FIELDS;
 345 };
 346
 347 /* The object file that the main symbol table was loaded from (e.g. the
 348    argument to the "symbol-file" or "file" command).  */
 349
 350 #define symfile_objfile current_program_space->symfile_object_file
 351
 352 /* The set of target sections matching the sections mapped into the
 353    current program space.  */
 354 #define current_target_sections (&current_program_space->target_sections)
 355
 356 /* The list of all program spaces.  There's always at least one.  */
 357 extern struct program_space *program_spaces;
 358
 359 /* The current program space.  This is always non-null.  */
 360 extern struct program_space *current_program_space;
 361
 362 #define ALL_PSPACES(pspace) \
 363   for ((pspace) = program_spaces; (pspace) != NULL; (pspace) = (pspace)->next)
 364
 365 /* Remove a program space from the program spaces list and release it.  It is
 366    an error to call this function while PSPACE is the current program space. */
 367 extern void delete_program_space (struct program_space *pspace);
 368
 369 /* Returns the number of program spaces listed.  */
 370 extern int number_of_program_spaces (void);
 371
 372 /* Returns true iff there's no inferior bound to PSPACE.  */
 373 extern int program_space_empty_p (struct program_space *pspace);
 374
 375 /* Copies program space SRC to DEST.  Copies the main executable file,
 376    and the main symbol file.  Returns DEST.  */
 377 extern struct program_space *clone_program_space (struct program_space *dest,
 378                                                 struct program_space *src);
 379
 380 /* Sets PSPACE as the current program space.  This is usually used
 381    instead of set_current_space_and_thread when the current
 382    thread/inferior is not important for the operations that follow.
 383    E.g., when accessing the raw symbol tables.  If memory access is
 384    required, then you should use switch_to_program_space_and_thread.
 385    Otherwise, it is the caller's responsibility to make sure that the
 386    currently selected inferior/thread matches the selected program
 387    space.  */
 388 extern void set_current_program_space (struct program_space *pspace);
 389
 390 /* Save/restore the current program space.  */
 391
 392 class scoped_restore_current_program_space
 393 {
 394 public:
 395   scoped_restore_current_program_space ()
 396     : m_saved_pspace (current_program_space)
 397   {}
 398
 399   ~scoped_restore_current_program_space ()
 400   { set_current_program_space (m_saved_pspace); }
 401
 402   DISABLE_COPY_AND_ASSIGN (scoped_restore_current_program_space);
 403
 404 private:
 405   program_space *m_saved_pspace;
 406 };
 407
 408 /* Create a new address space object, and add it to the list.  */
 409 extern struct address_space *new_address_space (void);
 410
 411 /* Maybe create a new address space object, and add it to the list, or
 412    return a pointer to an existing address space, in case inferiors
 413    share an address space.  */
 414 extern struct address_space *maybe_new_address_space (void);
 415
 416 /* Returns the integer address space id of ASPACE.  */
 417 extern int address_space_num (struct address_space *aspace);
 418
 419 /* Update all program spaces matching to address spaces.  The user may
 420    have created several program spaces, and loaded executables into
 421    them before connecting to the target interface that will create the
 422    inferiors.  All that happens before GDB has a chance to know if the
 423    inferiors will share an address space or not.  Call this after
 424    having connected to the target interface and having fetched the
 425    target description, to fixup the program/address spaces
 426    mappings.  */
 427 extern void update_address_spaces (void);
 428
 429 /* Reset saved solib data at the start of an solib event.  This lets
 430    us properly collect the data when calling solib_add, so it can then
 431    later be printed.  */
 432 extern void clear_program_space_solib_cache (struct program_space *);
 433
 434 /* Keep a registry of per-pspace data-pointers required by other GDB
 435    modules.  */
 436
 437 DECLARE_REGISTRY (program_space);
 438
 439 /* Keep a registry of per-aspace data-pointers required by other GDB
 440    modules.  */
 441
 442 DECLARE_REGISTRY (address_space);
 443
 444 #endif