gdb/progspace.h

   1 /* Program and address space management, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2009-2018 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 "vec.h"
  26 #include "gdb_bfd.h"
  27 #include "gdb_vecs.h"
  28 #include "registry.h"
  29
  30 struct target_ops;
  31 struct bfd;
  32 struct objfile;
  33 struct inferior;
  34 struct exec;
  35 struct address_space;
  36 struct program_space_data;
  37 struct address_space_data;
  38
  39 /* A program space represents a symbolic view of an address space.
  40    Roughly speaking, it holds all the data associated with a
  41    non-running-yet program (main executable, main symbols), and when
  42    an inferior is running and is bound to it, includes the list of its
  43    mapped in shared libraries.
  44
  45    In the traditional debugging scenario, there's a 1-1 correspondence
  46    among program spaces, inferiors and address spaces, like so:
  47
  48      pspace1 (prog1) <--> inf1(pid1) <--> aspace1
  49
  50    In the case of debugging more than one traditional unix process or
  51    program, we still have:
  52
  53      |-----------------+------------+---------|
  54      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  55      |----------------------------------------|
  56      | pspace2 (prog1) | no inf yet | aspace2 |
  57      |-----------------+------------+---------|
  58      | pspace3 (prog2) | inf2(pid2) | aspace3 |
  59      |-----------------+------------+---------|
  60
  61    In the former example, if inf1 forks (and GDB stays attached to
  62    both processes), the new child will have its own program and
  63    address spaces.  Like so:
  64
  65      |-----------------+------------+---------|
  66      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  67      |-----------------+------------+---------|
  68      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  69      |-----------------+------------+---------|
  70
  71    However, had inf1 from the latter case vforked instead, it would
  72    share the program and address spaces with its parent, until it
  73    execs or exits, like so:
  74
  75      |-----------------+------------+---------|
  76      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  77      |                 | inf2(pid2) |         |
  78      |-----------------+------------+---------|
  79
  80    When the vfork child execs, it is finally given new program and
  81    address spaces.
  82
  83      |-----------------+------------+---------|
  84      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  85      |-----------------+------------+---------|
  86      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  87      |-----------------+------------+---------|
  88
  89    There are targets where the OS (if any) doesn't provide memory
  90    management or VM protection, where all inferiors share the same
  91    address space --- e.g. uClinux.  GDB models this by having all
  92    inferiors share the same address space, but, giving each its own
  93    program space, like so:
  94
  95      |-----------------+------------+---------|
  96      | pspace1 (prog1) | inf1(pid1) |         |
  97      |-----------------+------------+         |
  98      | pspace2 (prog1) | inf2(pid2) | aspace1 |
  99      |-----------------+------------+         |
 100      | pspace3 (prog2) | inf3(pid3) |         |
 101      |-----------------+------------+---------|
 102
 103    The address space sharing matters for run control and breakpoints
 104    management.  E.g., did we just hit a known breakpoint that we need
 105    to step over?  Is this breakpoint a duplicate of this other one, or
 106    do I need to insert a trap?
 107
 108    Then, there are targets where all symbols look the same for all
 109    inferiors, although each has its own address space, as e.g.,
 110    Ericsson DICOS.  In such case, the model is:
 111
 112      |---------+------------+---------|
 113      |         | inf1(pid1) | aspace1 |
 114      |         +------------+---------|
 115      | pspace  | inf2(pid2) | aspace2 |
 116      |         +------------+---------|
 117      |         | inf3(pid3) | aspace3 |
 118      |---------+------------+---------|
 119
 120    Note however, that the DICOS debug API takes care of making GDB
 121    believe that breakpoints are "global".  That is, although each
 122    process does have its own private copy of data symbols (just like a
 123    bunch of forks), to the breakpoints module, all processes share a
 124    single address space, so all breakpoints set at the same address
 125    are duplicates of each other, even breakpoints set in the data
 126    space (e.g., call dummy breakpoints placed on stack).  This allows
 127    a simplification in the spaces implementation: we avoid caring for
 128    a many-many links between address and program spaces.  Either
 129    there's a single address space bound to the program space
 130    (traditional unix/uClinux), or, in the DICOS case, the address
 131    space bound to the program space is mostly ignored.  */
 132
 133 /* The program space structure.  */
 134
 135 struct program_space
 136 {
 137   program_space (address_space *aspace_);
 138   ~program_space ();
 139
 140   /* Pointer to next in linked list.  */
 141   struct program_space *next = NULL;
 142
 143   /* Unique ID number.  */
 144   int num = 0;
 145
 146   /* The main executable loaded into this program space.  This is
 147      managed by the exec target.  */
 148
 149   /* The BFD handle for the main executable.  */
 150   bfd *ebfd = NULL;
 151   /* The last-modified time, from when the exec was brought in.  */
 152   long ebfd_mtime = 0;
 153   /* Similar to bfd_get_filename (exec_bfd) but in original form given
 154      by user, without symbolic links and pathname resolved.
 155      It needs to be freed by xfree.  It is not NULL iff EBFD is not NULL.  */
 156   char *pspace_exec_filename = NULL;
 157
 158   /* Binary file diddling handle for the core file.  */
 159   gdb_bfd_ref_ptr cbfd;
 160
 161   /* The address space attached to this program space.  More than one
 162      program space may be bound to the same address space.  In the
 163      traditional unix-like debugging scenario, this will usually
 164      match the address space bound to the inferior, and is mostly
 165      used by the breakpoints module for address matches.  If the
 166      target shares a program space for all inferiors and breakpoints
 167      are global, then this field is ignored (we don't currently
 168      support inferiors sharing a program space if the target doesn't
 169      make breakpoints global).  */
 170   struct address_space *aspace = NULL;
 171
 172   /* True if this program space's section offsets don't yet represent
 173      the final offsets of the "live" address space (that is, the
 174      section addresses still require the relocation offsets to be
 175      applied, and hence we can't trust the section addresses for
 176      anything that pokes at live memory).  E.g., for qOffsets
 177      targets, or for PIE executables, until we connect and ask the
 178      target for the final relocation offsets, the symbols we've used
 179      to set breakpoints point at the wrong addresses.  */
 180   int executing_startup = 0;
 181
 182   /* True if no breakpoints should be inserted in this program
 183      space.  */
 184   int breakpoints_not_allowed = 0;
 185
 186   /* The object file that the main symbol table was loaded from
 187      (e.g. the argument to the "symbol-file" or "file" command).  */
 188   struct objfile *symfile_object_file = NULL;
 189
 190   /* All known objfiles are kept in a linked list.  This points to
 191      the head of this list.  */
 192   struct objfile *objfiles = NULL;
 193
 194   /* The set of target sections matching the sections mapped into
 195      this program space.  Managed by both exec_ops and solib.c.  */
 196   struct target_section_table target_sections {};
 197
 198   /* List of shared objects mapped into this space.  Managed by
 199      solib.c.  */
 200   struct so_list *so_list = NULL;
 201
 202   /* Number of calls to solib_add.  */
 203   unsigned int solib_add_generation = 0;
 204
 205   /* When an solib is added, it is also added to this vector.  This
 206      is so we can properly report solib changes to the user.  */
 207   std::vector<struct so_list *> added_solibs;
 208
 209   /* When an solib is removed, its name is added to this vector.
 210      This is so we can properly report solib changes to the user.  */
 211   std::vector<std::string> deleted_solibs;
 212
 213   /* Per pspace data-pointers required by other GDB modules.  */
 214   REGISTRY_FIELDS {};
 215 };
 216
 217 /* An address space.  It is used for comparing if
 218    pspaces/inferior/threads see the same address space and for
 219    associating caches to each address space.  */
 220 struct address_space
 221 {
 222   int num;
 223
 224   /* Per aspace data-pointers required by other GDB modules.  */
 225   REGISTRY_FIELDS;
 226 };
 227
 228 /* The object file that the main symbol table was loaded from (e.g. the
 229    argument to the "symbol-file" or "file" command).  */
 230
 231 #define symfile_objfile current_program_space->symfile_object_file
 232
 233 /* All known objfiles are kept in a linked list.  This points to the
 234    root of this list.  */
 235 #define object_files current_program_space->objfiles
 236
 237 /* The set of target sections matching the sections mapped into the
 238    current program space.  */
 239 #define current_target_sections (&current_program_space->target_sections)
 240
 241 /* The list of all program spaces.  There's always at least one.  */
 242 extern struct program_space *program_spaces;
 243
 244 /* The current program space.  This is always non-null.  */
 245 extern struct program_space *current_program_space;
 246
 247 #define ALL_PSPACES(pspace) \
 248   for ((pspace) = program_spaces; (pspace) != NULL; (pspace) = (pspace)->next)
 249
 250 /* Remove a program space from the program spaces list and release it.  It is
 251    an error to call this function while PSPACE is the current program space. */
 252 extern void delete_program_space (struct program_space *pspace);
 253
 254 /* Returns the number of program spaces listed.  */
 255 extern int number_of_program_spaces (void);
 256
 257 /* Returns true iff there's no inferior bound to PSPACE.  */
 258 extern int program_space_empty_p (struct program_space *pspace);
 259
 260 /* Copies program space SRC to DEST.  Copies the main executable file,
 261    and the main symbol file.  Returns DEST.  */
 262 extern struct program_space *clone_program_space (struct program_space *dest,
 263                                                 struct program_space *src);
 264
 265 /* Sets PSPACE as the current program space.  This is usually used
 266    instead of set_current_space_and_thread when the current
 267    thread/inferior is not important for the operations that follow.
 268    E.g., when accessing the raw symbol tables.  If memory access is
 269    required, then you should use switch_to_program_space_and_thread.
 270    Otherwise, it is the caller's responsibility to make sure that the
 271    currently selected inferior/thread matches the selected program
 272    space.  */
 273 extern void set_current_program_space (struct program_space *pspace);
 274
 275 /* Save/restore the current program space.  */
 276
 277 class scoped_restore_current_program_space
 278 {
 279 public:
 280   scoped_restore_current_program_space ()
 281     : m_saved_pspace (current_program_space)
 282   {}
 283
 284   ~scoped_restore_current_program_space ()
 285   { set_current_program_space (m_saved_pspace); }
 286
 287   DISABLE_COPY_AND_ASSIGN (scoped_restore_current_program_space);
 288
 289 private:
 290   program_space *m_saved_pspace;
 291 };
 292
 293 /* Create a new address space object, and add it to the list.  */
 294 extern struct address_space *new_address_space (void);
 295
 296 /* Maybe create a new address space object, and add it to the list, or
 297    return a pointer to an existing address space, in case inferiors
 298    share an address space.  */
 299 extern struct address_space *maybe_new_address_space (void);
 300
 301 /* Returns the integer address space id of ASPACE.  */
 302 extern int address_space_num (struct address_space *aspace);
 303
 304 /* Update all program spaces matching to address spaces.  The user may
 305    have created several program spaces, and loaded executables into
 306    them before connecting to the target interface that will create the
 307    inferiors.  All that happens before GDB has a chance to know if the
 308    inferiors will share an address space or not.  Call this after
 309    having connected to the target interface and having fetched the
 310    target description, to fixup the program/address spaces
 311    mappings.  */
 312 extern void update_address_spaces (void);
 313
 314 /* Reset saved solib data at the start of an solib event.  This lets
 315    us properly collect the data when calling solib_add, so it can then
 316    later be printed.  */
 317 extern void clear_program_space_solib_cache (struct program_space *);
 318
 319 /* Keep a registry of per-pspace data-pointers required by other GDB
 320    modules.  */
 321
 322 DECLARE_REGISTRY (program_space);
 323
 324 /* Keep a registry of per-aspace data-pointers required by other GDB
 325    modules.  */
 326
 327 DECLARE_REGISTRY (address_space);
 328
 329 #endif