gdb/progspace.h

   1 /* Program and address space management, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2009-2017 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_vecs.h"
  27 #include "registry.h"
  28
  29 struct target_ops;
  30 struct bfd;
  31 struct objfile;
  32 struct inferior;
  33 struct exec;
  34 struct address_space;
  35 struct program_space_data;
  36 struct address_space_data;
  37
  38 typedef struct so_list *so_list_ptr;
  39 DEF_VEC_P (so_list_ptr);
  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     /* Pointer to next in linked list.  */
 140     struct program_space *next;
 141
 142     /* Unique ID number.  */
 143     int num;
 144
 145     /* The main executable loaded into this program space.  This is
 146        managed by the exec target.  */
 147
 148     /* The BFD handle for the main executable.  */
 149     bfd *ebfd;
 150     /* The last-modified time, from when the exec was brought in.  */
 151     long ebfd_mtime;
 152     /* Similar to bfd_get_filename (exec_bfd) but in original form given
 153        by user, without symbolic links and pathname resolved.
 154        It needs to be freed by xfree.  It is not NULL iff EBFD is not NULL.  */
 155     char *pspace_exec_filename;
 156
 157     /* The address space attached to this program space.  More than one
 158        program space may be bound to the same address space.  In the
 159        traditional unix-like debugging scenario, this will usually
 160        match the address space bound to the inferior, and is mostly
 161        used by the breakpoints module for address matches.  If the
 162        target shares a program space for all inferiors and breakpoints
 163        are global, then this field is ignored (we don't currently
 164        support inferiors sharing a program space if the target doesn't
 165        make breakpoints global).  */
 166     struct address_space *aspace;
 167
 168     /* True if this program space's section offsets don't yet represent
 169        the final offsets of the "live" address space (that is, the
 170        section addresses still require the relocation offsets to be
 171        applied, and hence we can't trust the section addresses for
 172        anything that pokes at live memory).  E.g., for qOffsets
 173        targets, or for PIE executables, until we connect and ask the
 174        target for the final relocation offsets, the symbols we've used
 175        to set breakpoints point at the wrong addresses.  */
 176     int executing_startup;
 177
 178     /* True if no breakpoints should be inserted in this program
 179        space.  */
 180     int breakpoints_not_allowed;
 181
 182     /* The object file that the main symbol table was loaded from
 183        (e.g. the argument to the "symbol-file" or "file" command).  */
 184     struct objfile *symfile_object_file;
 185
 186     /* All known objfiles are kept in a linked list.  This points to
 187        the head of this list.  */
 188     struct objfile *objfiles;
 189
 190     /* The set of target sections matching the sections mapped into
 191        this program space.  Managed by both exec_ops and solib.c.  */
 192     struct target_section_table target_sections;
 193
 194     /* List of shared objects mapped into this space.  Managed by
 195        solib.c.  */
 196     struct so_list *so_list;
 197
 198     /* Number of calls to solib_add.  */
 199     unsigned solib_add_generation;
 200
 201     /* When an solib is added, it is also added to this vector.  This
 202        is so we can properly report solib changes to the user.  */
 203     VEC (so_list_ptr) *added_solibs;
 204
 205     /* When an solib is removed, its name is added to this vector.
 206        This is so we can properly report solib changes to the user.  */
 207     VEC (char_ptr) *deleted_solibs;
 208
 209     /* Per pspace data-pointers required by other GDB modules.  */
 210     REGISTRY_FIELDS;
 211   };
 212
 213 /* The object file that the main symbol table was loaded from (e.g. the
 214    argument to the "symbol-file" or "file" command).  */
 215
 216 #define symfile_objfile current_program_space->symfile_object_file
 217
 218 /* All known objfiles are kept in a linked list.  This points to the
 219    root of this list.  */
 220 #define object_files current_program_space->objfiles
 221
 222 /* The set of target sections matching the sections mapped into the
 223    current program space.  */
 224 #define current_target_sections (&current_program_space->target_sections)
 225
 226 /* The list of all program spaces.  There's always at least one.  */
 227 extern struct program_space *program_spaces;
 228
 229 /* The current program space.  This is always non-null.  */
 230 extern struct program_space *current_program_space;
 231
 232 #define ALL_PSPACES(pspace) \
 233   for ((pspace) = program_spaces; (pspace) != NULL; (pspace) = (pspace)->next)
 234
 235 /* Add a new empty program space, and assign ASPACE to it.  Returns the
 236    pointer to the new object.  */
 237 extern struct program_space *add_program_space (struct address_space *aspace);
 238
 239 /* Remove a program space from the program spaces list and release it.  It is
 240    an error to call this function while PSPACE is the current program space. */
 241 extern void delete_program_space (struct program_space *pspace);
 242
 243 /* Returns the number of program spaces listed.  */
 244 extern int number_of_program_spaces (void);
 245
 246 /* Returns true iff there's no inferior bound to PSPACE.  */
 247 extern int program_space_empty_p (struct program_space *pspace);
 248
 249 /* Copies program space SRC to DEST.  Copies the main executable file,
 250    and the main symbol file.  Returns DEST.  */
 251 extern struct program_space *clone_program_space (struct program_space *dest,
 252                                                 struct program_space *src);
 253
 254 /* Sets PSPACE as the current program space.  This is usually used
 255    instead of set_current_space_and_thread when the current
 256    thread/inferior is not important for the operations that follow.
 257    E.g., when accessing the raw symbol tables.  If memory access is
 258    required, then you should use switch_to_program_space_and_thread.
 259    Otherwise, it is the caller's responsibility to make sure that the
 260    currently selected inferior/thread matches the selected program
 261    space.  */
 262 extern void set_current_program_space (struct program_space *pspace);
 263
 264 /* Save/restore the current program space.  */
 265
 266 class scoped_restore_current_program_space
 267 {
 268 public:
 269   scoped_restore_current_program_space ()
 270     : m_saved_pspace (current_program_space)
 271   {}
 272
 273   ~scoped_restore_current_program_space ()
 274   { set_current_program_space (m_saved_pspace); }
 275
 276   /* Disable copy.  */
 277   scoped_restore_current_program_space
 278     (const scoped_restore_current_program_space &) = delete;
 279   void operator=
 280     (const scoped_restore_current_program_space &) = delete;
 281
 282 private:
 283   program_space *m_saved_pspace;
 284 };
 285
 286 /* Create a new address space object, and add it to the list.  */
 287 extern struct address_space *new_address_space (void);
 288
 289 /* Maybe create a new address space object, and add it to the list, or
 290    return a pointer to an existing address space, in case inferiors
 291    share an address space.  */
 292 extern struct address_space *maybe_new_address_space (void);
 293
 294 /* Returns the integer address space id of ASPACE.  */
 295 extern int address_space_num (struct address_space *aspace);
 296
 297 /* Update all program spaces matching to address spaces.  The user may
 298    have created several program spaces, and loaded executables into
 299    them before connecting to the target interface that will create the
 300    inferiors.  All that happens before GDB has a chance to know if the
 301    inferiors will share an address space or not.  Call this after
 302    having connected to the target interface and having fetched the
 303    target description, to fixup the program/address spaces
 304    mappings.  */
 305 extern void update_address_spaces (void);
 306
 307 /* Reset saved solib data at the start of an solib event.  This lets
 308    us properly collect the data when calling solib_add, so it can then
 309    later be printed.  */
 310 extern void clear_program_space_solib_cache (struct program_space *);
 311
 312 /* Keep a registry of per-pspace data-pointers required by other GDB
 313    modules.  */
 314
 315 DECLARE_REGISTRY (program_space);
 316
 317 /* Keep a registry of per-aspace data-pointers required by other GDB
 318    modules.  */
 319
 320 DECLARE_REGISTRY (address_space);
 321
 322 #endif