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 #include <vector>
  32
  33 struct target_ops;
  34 struct bfd;
  35 struct objfile;
  36 struct inferior;
  37 struct exec;
  38 struct address_space;
  39 struct program_space_data;
  40 struct address_space_data;
  41 struct so_list;
  42
  43 typedef std::list<std::shared_ptr<objfile>> objfile_list;
  44
  45 /* An iterator that wraps an iterator over std::shared_ptr<objfile>,
  46    and dereferences the returned object.  This is useful for iterating
  47    over a list of shared pointers and returning raw pointers -- which
  48    helped avoid touching a lot of code when changing how objfiles are
  49    managed.  */
  50
  51 class unwrapping_objfile_iterator
  52 {
  53 public:
  54
  55   typedef unwrapping_objfile_iterator self_type;
  56   typedef typename ::objfile *value_type;
  57   typedef typename ::objfile &reference;
  58   typedef typename ::objfile **pointer;
  59   typedef typename objfile_list::iterator::iterator_category iterator_category;
  60   typedef typename objfile_list::iterator::difference_type difference_type;
  61
  62   unwrapping_objfile_iterator (const objfile_list::iterator &iter)
  63     : m_iter (iter)
  64   {
  65   }
  66
  67   objfile *operator* () const
  68   {
  69     return m_iter->get ();
  70   }
  71
  72   unwrapping_objfile_iterator operator++ ()
  73   {
  74     ++m_iter;
  75     return *this;
  76   }
  77
  78   bool operator!= (const unwrapping_objfile_iterator &other) const
  79   {
  80     return m_iter != other.m_iter;
  81   }
  82
  83 private:
  84
  85   /* The underlying iterator.  */
  86   objfile_list::iterator m_iter;
  87 };
  88
  89
  90 /* A range that returns unwrapping_objfile_iterators.  */
  91
  92 struct unwrapping_objfile_range
  93 {
  94   typedef unwrapping_objfile_iterator iterator;
  95
  96   unwrapping_objfile_range (objfile_list &ol)
  97     : m_list (ol)
  98   {
  99   }
 100
 101   iterator begin () const
 102   {
 103     return iterator (m_list.begin ());
 104   }
 105
 106   iterator end () const
 107   {
 108     return iterator (m_list.end ());
 109   }
 110
 111 private:
 112
 113   objfile_list &m_list;
 114 };
 115
 116 /* A program space represents a symbolic view of an address space.
 117    Roughly speaking, it holds all the data associated with a
 118    non-running-yet program (main executable, main symbols), and when
 119    an inferior is running and is bound to it, includes the list of its
 120    mapped in shared libraries.
 121
 122    In the traditional debugging scenario, there's a 1-1 correspondence
 123    among program spaces, inferiors and address spaces, like so:
 124
 125      pspace1 (prog1) <--> inf1(pid1) <--> aspace1
 126
 127    In the case of debugging more than one traditional unix process or
 128    program, we still have:
 129
 130      |-----------------+------------+---------|
 131      | pspace1 (prog1) | inf1(pid1) | aspace1 |
 132      |----------------------------------------|
 133      | pspace2 (prog1) | no inf yet | aspace2 |
 134      |-----------------+------------+---------|
 135      | pspace3 (prog2) | inf2(pid2) | aspace3 |
 136      |-----------------+------------+---------|
 137
 138    In the former example, if inf1 forks (and GDB stays attached to
 139    both processes), the new child will have its own program and
 140    address spaces.  Like so:
 141
 142      |-----------------+------------+---------|
 143      | pspace1 (prog1) | inf1(pid1) | aspace1 |
 144      |-----------------+------------+---------|
 145      | pspace2 (prog1) | inf2(pid2) | aspace2 |
 146      |-----------------+------------+---------|
 147
 148    However, had inf1 from the latter case vforked instead, it would
 149    share the program and address spaces with its parent, until it
 150    execs or exits, like so:
 151
 152      |-----------------+------------+---------|
 153      | pspace1 (prog1) | inf1(pid1) | aspace1 |
 154      |                 | inf2(pid2) |         |
 155      |-----------------+------------+---------|
 156
 157    When the vfork child execs, it is finally given new program and
 158    address spaces.
 159
 160      |-----------------+------------+---------|
 161      | pspace1 (prog1) | inf1(pid1) | aspace1 |
 162      |-----------------+------------+---------|
 163      | pspace2 (prog1) | inf2(pid2) | aspace2 |
 164      |-----------------+------------+---------|
 165
 166    There are targets where the OS (if any) doesn't provide memory
 167    management or VM protection, where all inferiors share the same
 168    address space --- e.g. uClinux.  GDB models this by having all
 169    inferiors share the same address space, but, giving each its own
 170    program space, like so:
 171
 172      |-----------------+------------+---------|
 173      | pspace1 (prog1) | inf1(pid1) |         |
 174      |-----------------+------------+         |
 175      | pspace2 (prog1) | inf2(pid2) | aspace1 |
 176      |-----------------+------------+         |
 177      | pspace3 (prog2) | inf3(pid3) |         |
 178      |-----------------+------------+---------|
 179
 180    The address space sharing matters for run control and breakpoints
 181    management.  E.g., did we just hit a known breakpoint that we need
 182    to step over?  Is this breakpoint a duplicate of this other one, or
 183    do I need to insert a trap?
 184
 185    Then, there are targets where all symbols look the same for all
 186    inferiors, although each has its own address space, as e.g.,
 187    Ericsson DICOS.  In such case, the model is:
 188
 189      |---------+------------+---------|
 190      |         | inf1(pid1) | aspace1 |
 191      |         +------------+---------|
 192      | pspace  | inf2(pid2) | aspace2 |
 193      |         +------------+---------|
 194      |         | inf3(pid3) | aspace3 |
 195      |---------+------------+---------|
 196
 197    Note however, that the DICOS debug API takes care of making GDB
 198    believe that breakpoints are "global".  That is, although each
 199    process does have its own private copy of data symbols (just like a
 200    bunch of forks), to the breakpoints module, all processes share a
 201    single address space, so all breakpoints set at the same address
 202    are duplicates of each other, even breakpoints set in the data
 203    space (e.g., call dummy breakpoints placed on stack).  This allows
 204    a simplification in the spaces implementation: we avoid caring for
 205    a many-many links between address and program spaces.  Either
 206    there's a single address space bound to the program space
 207    (traditional unix/uClinux), or, in the DICOS case, the address
 208    space bound to the program space is mostly ignored.  */
 209
 210 /* The program space structure.  */
 211
 212 struct program_space
 213 {
 214   /* Constructs a new empty program space, binds it to ASPACE, and
 215      adds it to the program space list.  */
 216   explicit program_space (address_space *aspace);
 217
 218   /* Releases a program space, and all its contents (shared libraries,
 219      objfiles, and any other references to the program space in other
 220      modules).  It is an internal error to call this when the program
 221      space is the current program space, since there should always be
 222      a program space.  */
 223   ~program_space ();
 224
 225   typedef unwrapping_objfile_range objfiles_range;
 226
 227   /* Return an iterable object that can be used to iterate over all
 228      objfiles.  The basic use is in a foreach, like:
 229
 230      for (objfile *objf : pspace->objfiles ()) { ... }  */
 231   objfiles_range objfiles ()
 232   {
 233     return unwrapping_objfile_range (objfiles_list);
 234   }
 235
 236   typedef basic_safe_range<objfiles_range> objfiles_safe_range;
 237
 238   /* An iterable object that can be used to iterate over all objfiles.
 239      The basic use is in a foreach, like:
 240
 241      for (objfile *objf : pspace->objfiles_safe ()) { ... }
 242
 243      This variant uses a basic_safe_iterator so that objfiles can be
 244      deleted during iteration.  */
 245   objfiles_safe_range objfiles_safe ()
 246   {
 247     return objfiles_safe_range (objfiles_list);
 248   }
 249
 250   /* Add OBJFILE to the list of objfiles, putting it just before
 251      BEFORE.  If BEFORE is nullptr, it will go at the end of the
 252      list.  */
 253   void add_objfile (std::shared_ptr<objfile> &&objfile,
 254                     struct objfile *before);
 255
 256   /* Remove OBJFILE from the list of objfiles.  */
 257   void remove_objfile (struct objfile *objfile);
 258
 259   /* Return true if there is more than one object file loaded; false
 260      otherwise.  */
 261   bool multi_objfile_p () const
 262   {
 263     return objfiles_list.size () > 1;
 264   }
 265
 266   /* Free all the objfiles associated with this program space.  */
 267   void free_all_objfiles ();
 268
 269   /* Return a range adapter for iterating over all the solibs in this
 270      program space.  Use it like:
 271
 272      for (so_list *so : pspace->solibs ()) { ... }  */
 273   next_adapter<struct so_list> solibs () const;
 274
 275
 276   /* Unique ID number.  */
 277   int num = 0;
 278
 279   /* The main executable loaded into this program space.  This is
 280      managed by the exec target.  */
 281
 282   /* The BFD handle for the main executable.  */
 283   bfd *ebfd = NULL;
 284   /* The last-modified time, from when the exec was brought in.  */
 285   long ebfd_mtime = 0;
 286   /* Similar to bfd_get_filename (exec_bfd) but in original form given
 287      by user, without symbolic links and pathname resolved.
 288      It needs to be freed by xfree.  It is not NULL iff EBFD is not NULL.  */
 289   char *pspace_exec_filename = NULL;
 290
 291   /* Binary file diddling handle for the core file.  */
 292   gdb_bfd_ref_ptr cbfd;
 293
 294   /* The address space attached to this program space.  More than one
 295      program space may be bound to the same address space.  In the
 296      traditional unix-like debugging scenario, this will usually
 297      match the address space bound to the inferior, and is mostly
 298      used by the breakpoints module for address matches.  If the
 299      target shares a program space for all inferiors and breakpoints
 300      are global, then this field is ignored (we don't currently
 301      support inferiors sharing a program space if the target doesn't
 302      make breakpoints global).  */
 303   struct address_space *aspace = NULL;
 304
 305   /* True if this program space's section offsets don't yet represent
 306      the final offsets of the "live" address space (that is, the
 307      section addresses still require the relocation offsets to be
 308      applied, and hence we can't trust the section addresses for
 309      anything that pokes at live memory).  E.g., for qOffsets
 310      targets, or for PIE executables, until we connect and ask the
 311      target for the final relocation offsets, the symbols we've used
 312      to set breakpoints point at the wrong addresses.  */
 313   int executing_startup = 0;
 314
 315   /* True if no breakpoints should be inserted in this program
 316      space.  */
 317   int breakpoints_not_allowed = 0;
 318
 319   /* The object file that the main symbol table was loaded from
 320      (e.g. the argument to the "symbol-file" or "file" command).  */
 321   struct objfile *symfile_object_file = NULL;
 322
 323   /* All known objfiles are kept in a linked list.  */
 324   std::list<std::shared_ptr<objfile>> objfiles_list;
 325
 326   /* The set of target sections matching the sections mapped into
 327      this program space.  Managed by both exec_ops and solib.c.  */
 328   struct target_section_table target_sections {};
 329
 330   /* List of shared objects mapped into this space.  Managed by
 331      solib.c.  */
 332   struct so_list *so_list = NULL;
 333
 334   /* Number of calls to solib_add.  */
 335   unsigned int solib_add_generation = 0;
 336
 337   /* When an solib is added, it is also added to this vector.  This
 338      is so we can properly report solib changes to the user.  */
 339   std::vector<struct so_list *> added_solibs;
 340
 341   /* When an solib is removed, its name is added to this vector.
 342      This is so we can properly report solib changes to the user.  */
 343   std::vector<std::string> deleted_solibs;
 344
 345   /* Per pspace data-pointers required by other GDB modules.  */
 346   REGISTRY_FIELDS {};
 347 };
 348
 349 /* An address space.  It is used for comparing if
 350    pspaces/inferior/threads see the same address space and for
 351    associating caches to each address space.  */
 352 struct address_space
 353 {
 354   int num;
 355
 356   /* Per aspace data-pointers required by other GDB modules.  */
 357   REGISTRY_FIELDS;
 358 };
 359
 360 /* The object file that the main symbol table was loaded from (e.g. the
 361    argument to the "symbol-file" or "file" command).  */
 362
 363 #define symfile_objfile current_program_space->symfile_object_file
 364
 365 /* The set of target sections matching the sections mapped into the
 366    current program space.  */
 367 #define current_target_sections (&current_program_space->target_sections)
 368
 369 /* The list of all program spaces.  There's always at least one.  */
 370 extern std::vector<struct program_space *>program_spaces;
 371
 372 /* The current program space.  This is always non-null.  */
 373 extern struct program_space *current_program_space;
 374
 375 /* Returns true iff there's no inferior bound to PSPACE.  */
 376 extern int program_space_empty_p (struct program_space *pspace);
 377
 378 /* Copies program space SRC to DEST.  Copies the main executable file,
 379    and the main symbol file.  Returns DEST.  */
 380 extern struct program_space *clone_program_space (struct program_space *dest,
 381                                                 struct program_space *src);
 382
 383 /* Sets PSPACE as the current program space.  This is usually used
 384    instead of set_current_space_and_thread when the current
 385    thread/inferior is not important for the operations that follow.
 386    E.g., when accessing the raw symbol tables.  If memory access is
 387    required, then you should use switch_to_program_space_and_thread.
 388    Otherwise, it is the caller's responsibility to make sure that the
 389    currently selected inferior/thread matches the selected program
 390    space.  */
 391 extern void set_current_program_space (struct program_space *pspace);
 392
 393 /* Save/restore the current program space.  */
 394
 395 class scoped_restore_current_program_space
 396 {
 397 public:
 398   scoped_restore_current_program_space ()
 399     : m_saved_pspace (current_program_space)
 400   {}
 401
 402   ~scoped_restore_current_program_space ()
 403   { set_current_program_space (m_saved_pspace); }
 404
 405   DISABLE_COPY_AND_ASSIGN (scoped_restore_current_program_space);
 406
 407 private:
 408   program_space *m_saved_pspace;
 409 };
 410
 411 /* Create a new address space object, and add it to the list.  */
 412 extern struct address_space *new_address_space (void);
 413
 414 /* Maybe create a new address space object, and add it to the list, or
 415    return a pointer to an existing address space, in case inferiors
 416    share an address space.  */
 417 extern struct address_space *maybe_new_address_space (void);
 418
 419 /* Returns the integer address space id of ASPACE.  */
 420 extern int address_space_num (struct address_space *aspace);
 421
 422 /* Update all program spaces matching to address spaces.  The user may
 423    have created several program spaces, and loaded executables into
 424    them before connecting to the target interface that will create the
 425    inferiors.  All that happens before GDB has a chance to know if the
 426    inferiors will share an address space or not.  Call this after
 427    having connected to the target interface and having fetched the
 428    target description, to fixup the program/address spaces
 429    mappings.  */
 430 extern void update_address_spaces (void);
 431
 432 /* Reset saved solib data at the start of an solib event.  This lets
 433    us properly collect the data when calling solib_add, so it can then
 434    later be printed.  */
 435 extern void clear_program_space_solib_cache (struct program_space *);
 436
 437 /* Keep a registry of per-pspace data-pointers required by other GDB
 438    modules.  */
 439
 440 DECLARE_REGISTRY (program_space);
 441
 442 /* Keep a registry of per-aspace data-pointers required by other GDB
 443    modules.  */
 444
 445 DECLARE_REGISTRY (address_space);
 446
 447 #endif