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 "common/vec.h"
  26 #include "gdb_bfd.h"
  27 #include "common/gdb_vecs.h"
  28 #include "registry.h"
  29 #include "common/next-iterator.h"
  30 #include "common/safe-iterator.h"
  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 next_adapter<struct objfile> objfiles_range;
 143
 144   /* Return an iterarable 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_range (objfiles_head);
 151   }
 152
 153   typedef next_adapter<struct objfile,
 154                        basic_safe_iterator<next_iterator<objfile>>>
 155     objfiles_safe_range;
 156
 157   /* An iterable object that can be used to iterate over all objfiles.
 158      The basic use is in a foreach, like:
 159
 160      for (objfile *objf : pspace->objfiles_safe ()) { ... }
 161
 162      This variant uses a basic_safe_iterator so that objfiles can be
 163      deleted during iteration.  */
 164   objfiles_safe_range objfiles_safe ()
 165   {
 166     return objfiles_safe_range (objfiles_head);
 167   }
 168
 169   /* Pointer to next in linked list.  */
 170   struct program_space *next = NULL;
 171
 172   /* Unique ID number.  */
 173   int num = 0;
 174
 175   /* The main executable loaded into this program space.  This is
 176      managed by the exec target.  */
 177
 178   /* The BFD handle for the main executable.  */
 179   bfd *ebfd = NULL;
 180   /* The last-modified time, from when the exec was brought in.  */
 181   long ebfd_mtime = 0;
 182   /* Similar to bfd_get_filename (exec_bfd) but in original form given
 183      by user, without symbolic links and pathname resolved.
 184      It needs to be freed by xfree.  It is not NULL iff EBFD is not NULL.  */
 185   char *pspace_exec_filename = NULL;
 186
 187   /* Binary file diddling handle for the core file.  */
 188   gdb_bfd_ref_ptr cbfd;
 189
 190   /* The address space attached to this program space.  More than one
 191      program space may be bound to the same address space.  In the
 192      traditional unix-like debugging scenario, this will usually
 193      match the address space bound to the inferior, and is mostly
 194      used by the breakpoints module for address matches.  If the
 195      target shares a program space for all inferiors and breakpoints
 196      are global, then this field is ignored (we don't currently
 197      support inferiors sharing a program space if the target doesn't
 198      make breakpoints global).  */
 199   struct address_space *aspace = NULL;
 200
 201   /* True if this program space's section offsets don't yet represent
 202      the final offsets of the "live" address space (that is, the
 203      section addresses still require the relocation offsets to be
 204      applied, and hence we can't trust the section addresses for
 205      anything that pokes at live memory).  E.g., for qOffsets
 206      targets, or for PIE executables, until we connect and ask the
 207      target for the final relocation offsets, the symbols we've used
 208      to set breakpoints point at the wrong addresses.  */
 209   int executing_startup = 0;
 210
 211   /* True if no breakpoints should be inserted in this program
 212      space.  */
 213   int breakpoints_not_allowed = 0;
 214
 215   /* The object file that the main symbol table was loaded from
 216      (e.g. the argument to the "symbol-file" or "file" command).  */
 217   struct objfile *symfile_object_file = NULL;
 218
 219   /* All known objfiles are kept in a linked list.  This points to
 220      the head of this list.  */
 221   struct objfile *objfiles_head = NULL;
 222
 223   /* The set of target sections matching the sections mapped into
 224      this program space.  Managed by both exec_ops and solib.c.  */
 225   struct target_section_table target_sections {};
 226
 227   /* List of shared objects mapped into this space.  Managed by
 228      solib.c.  */
 229   struct so_list *so_list = NULL;
 230
 231   /* Number of calls to solib_add.  */
 232   unsigned int solib_add_generation = 0;
 233
 234   /* When an solib is added, it is also added to this vector.  This
 235      is so we can properly report solib changes to the user.  */
 236   std::vector<struct so_list *> added_solibs;
 237
 238   /* When an solib is removed, its name is added to this vector.
 239      This is so we can properly report solib changes to the user.  */
 240   std::vector<std::string> deleted_solibs;
 241
 242   /* Per pspace data-pointers required by other GDB modules.  */
 243   REGISTRY_FIELDS {};
 244 };
 245
 246 /* An address space.  It is used for comparing if
 247    pspaces/inferior/threads see the same address space and for
 248    associating caches to each address space.  */
 249 struct address_space
 250 {
 251   int num;
 252
 253   /* Per aspace data-pointers required by other GDB modules.  */
 254   REGISTRY_FIELDS;
 255 };
 256
 257 /* The object file that the main symbol table was loaded from (e.g. the
 258    argument to the "symbol-file" or "file" command).  */
 259
 260 #define symfile_objfile current_program_space->symfile_object_file
 261
 262 /* All known objfiles are kept in a linked list.  This points to the
 263    root of this list.  */
 264 #define object_files current_program_space->objfiles_head
 265
 266 /* The set of target sections matching the sections mapped into the
 267    current program space.  */
 268 #define current_target_sections (&current_program_space->target_sections)
 269
 270 /* The list of all program spaces.  There's always at least one.  */
 271 extern struct program_space *program_spaces;
 272
 273 /* The current program space.  This is always non-null.  */
 274 extern struct program_space *current_program_space;
 275
 276 #define ALL_PSPACES(pspace) \
 277   for ((pspace) = program_spaces; (pspace) != NULL; (pspace) = (pspace)->next)
 278
 279 /* Remove a program space from the program spaces list and release it.  It is
 280    an error to call this function while PSPACE is the current program space. */
 281 extern void delete_program_space (struct program_space *pspace);
 282
 283 /* Returns the number of program spaces listed.  */
 284 extern int number_of_program_spaces (void);
 285
 286 /* Returns true iff there's no inferior bound to PSPACE.  */
 287 extern int program_space_empty_p (struct program_space *pspace);
 288
 289 /* Copies program space SRC to DEST.  Copies the main executable file,
 290    and the main symbol file.  Returns DEST.  */
 291 extern struct program_space *clone_program_space (struct program_space *dest,
 292                                                 struct program_space *src);
 293
 294 /* Sets PSPACE as the current program space.  This is usually used
 295    instead of set_current_space_and_thread when the current
 296    thread/inferior is not important for the operations that follow.
 297    E.g., when accessing the raw symbol tables.  If memory access is
 298    required, then you should use switch_to_program_space_and_thread.
 299    Otherwise, it is the caller's responsibility to make sure that the
 300    currently selected inferior/thread matches the selected program
 301    space.  */
 302 extern void set_current_program_space (struct program_space *pspace);
 303
 304 /* Save/restore the current program space.  */
 305
 306 class scoped_restore_current_program_space
 307 {
 308 public:
 309   scoped_restore_current_program_space ()
 310     : m_saved_pspace (current_program_space)
 311   {}
 312
 313   ~scoped_restore_current_program_space ()
 314   { set_current_program_space (m_saved_pspace); }
 315
 316   DISABLE_COPY_AND_ASSIGN (scoped_restore_current_program_space);
 317
 318 private:
 319   program_space *m_saved_pspace;
 320 };
 321
 322 /* Create a new address space object, and add it to the list.  */
 323 extern struct address_space *new_address_space (void);
 324
 325 /* Maybe create a new address space object, and add it to the list, or
 326    return a pointer to an existing address space, in case inferiors
 327    share an address space.  */
 328 extern struct address_space *maybe_new_address_space (void);
 329
 330 /* Returns the integer address space id of ASPACE.  */
 331 extern int address_space_num (struct address_space *aspace);
 332
 333 /* Update all program spaces matching to address spaces.  The user may
 334    have created several program spaces, and loaded executables into
 335    them before connecting to the target interface that will create the
 336    inferiors.  All that happens before GDB has a chance to know if the
 337    inferiors will share an address space or not.  Call this after
 338    having connected to the target interface and having fetched the
 339    target description, to fixup the program/address spaces
 340    mappings.  */
 341 extern void update_address_spaces (void);
 342
 343 /* Reset saved solib data at the start of an solib event.  This lets
 344    us properly collect the data when calling solib_add, so it can then
 345    later be printed.  */
 346 extern void clear_program_space_solib_cache (struct program_space *);
 347
 348 /* Keep a registry of per-pspace data-pointers required by other GDB
 349    modules.  */
 350
 351 DECLARE_REGISTRY (program_space);
 352
 353 /* Keep a registry of per-aspace data-pointers required by other GDB
 354    modules.  */
 355
 356 DECLARE_REGISTRY (address_space);
 357
 358 #endif