gdb/progspace.h

   1 /* Program and address space management, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2009-2013 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
  37 typedef struct so_list *so_list_ptr;
  38 DEF_VEC_P (so_list_ptr);
  39
  40 /* A program space represents a symbolic view of an address space.
  41    Roughly speaking, it holds all the data associated with a
  42    non-running-yet program (main executable, main symbols), and when
  43    an inferior is running and is bound to it, includes the list of its
  44    mapped in shared libraries.
  45
  46    In the traditional debugging scenario, there's a 1-1 correspondence
  47    among program spaces, inferiors and address spaces, like so:
  48
  49      pspace1 (prog1) <--> inf1(pid1) <--> aspace1
  50
  51    In the case of debugging more than one traditional unix process or
  52    program, we still have:
  53
  54      |-----------------+------------+---------|
  55      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  56      |----------------------------------------|
  57      | pspace2 (prog1) | no inf yet | aspace2 |
  58      |-----------------+------------+---------|
  59      | pspace3 (prog2) | inf2(pid2) | aspace3 |
  60      |-----------------+------------+---------|
  61
  62    In the former example, if inf1 forks (and GDB stays attached to
  63    both processes), the new child will have its own program and
  64    address spaces.  Like so:
  65
  66      |-----------------+------------+---------|
  67      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  68      |-----------------+------------+---------|
  69      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  70      |-----------------+------------+---------|
  71
  72    However, had inf1 from the latter case vforked instead, it would
  73    share the program and address spaces with its parent, until it
  74    execs or exits, like so:
  75
  76      |-----------------+------------+---------|
  77      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  78      |                 | inf2(pid2) |         |
  79      |-----------------+------------+---------|
  80
  81    When the vfork child execs, it is finally given new program and
  82    address spaces.
  83
  84      |-----------------+------------+---------|
  85      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  86      |-----------------+------------+---------|
  87      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  88      |-----------------+------------+---------|
  89
  90    There are targets where the OS (if any) doesn't provide memory
  91    management or VM protection, where all inferiors share the same
  92    address space --- e.g. uClinux.  GDB models this by having all
  93    inferiors share the same address space, but, giving each its own
  94    program space, like so:
  95
  96      |-----------------+------------+---------|
  97      | pspace1 (prog1) | inf1(pid1) |         |
  98      |-----------------+------------+         |
  99      | pspace2 (prog1) | inf2(pid2) | aspace1 |
 100      |-----------------+------------+         |
 101      | pspace3 (prog2) | inf3(pid3) |         |
 102      |-----------------+------------+---------|
 103
 104    The address space sharing matters for run control and breakpoints
 105    management.  E.g., did we just hit a known breakpoint that we need
 106    to step over?  Is this breakpoint a duplicate of this other one, or
 107    do I need to insert a trap?
 108
 109    Then, there are targets where all symbols look the same for all
 110    inferiors, although each has its own address space, as e.g.,
 111    Ericsson DICOS.  In such case, the model is:
 112
 113      |---------+------------+---------|
 114      |         | inf1(pid1) | aspace1 |
 115      |         +------------+---------|
 116      | pspace  | inf2(pid2) | aspace2 |
 117      |         +------------+---------|
 118      |         | inf3(pid3) | aspace3 |
 119      |---------+------------+---------|
 120
 121    Note however, that the DICOS debug API takes care of making GDB
 122    believe that breakpoints are "global".  That is, although each
 123    process does have its own private copy of data symbols (just like a
 124    bunch of forks), to the breakpoints module, all processes share a
 125    single address space, so all breakpoints set at the same address
 126    are duplicates of each other, even breakpoints set in the data
 127    space (e.g., call dummy breakpoints placed on stack).  This allows
 128    a simplification in the spaces implementation: we avoid caring for
 129    a many-many links between address and program spaces.  Either
 130    there's a single address space bound to the program space
 131    (traditional unix/uClinux), or, in the DICOS case, the address
 132    space bound to the program space is mostly ignored.  */
 133
 134 /* The program space structure.  */
 135
 136 struct program_space
 137   {
 138     /* Pointer to next in linked list.  */
 139     struct program_space *next;
 140
 141     /* Unique ID number.  */
 142     int num;
 143
 144     /* The main executable loaded into this program space.  This is
 145        managed by the exec target.  */
 146
 147     /* The BFD handle for the main executable.  */
 148     bfd *ebfd;
 149     /* The last-modified time, from when the exec was brought in.  */
 150     long ebfd_mtime;
 151
 152     /* The address space attached to this program space.  More than one
 153        program space may be bound to the same address space.  In the
 154        traditional unix-like debugging scenario, this will usually
 155        match the address space bound to the inferior, and is mostly
 156        used by the breakpoints module for address matches.  If the
 157        target shares a program space for all inferiors and breakpoints
 158        are global, then this field is ignored (we don't currently
 159        support inferiors sharing a program space if the target doesn't
 160        make breakpoints global).  */
 161     struct address_space *aspace;
 162
 163     /* True if this program space's section offsets don't yet represent
 164        the final offsets of the "live" address space (that is, the
 165        section addresses still require the relocation offsets to be
 166        applied, and hence we can't trust the section addresses for
 167        anything that pokes at live memory).  E.g., for qOffsets
 168        targets, or for PIE executables, until we connect and ask the
 169        target for the final relocation offsets, the symbols we've used
 170        to set breakpoints point at the wrong addresses.  */
 171     int executing_startup;
 172
 173     /* True if no breakpoints should be inserted in this program
 174        space.  */
 175     int breakpoints_not_allowed;
 176
 177     /* The object file that the main symbol table was loaded from
 178        (e.g. the argument to the "symbol-file" or "file" command).  */
 179     struct objfile *symfile_object_file;
 180
 181     /* All known objfiles are kept in a linked list.  This points to
 182        the head of this list.  */
 183     struct objfile *objfiles;
 184
 185     /* The set of target sections matching the sections mapped into
 186        this program space.  Managed by both exec_ops and solib.c.  */
 187     struct target_section_table target_sections;
 188
 189     /* List of shared objects mapped into this space.  Managed by
 190        solib.c.  */
 191     struct so_list *so_list;
 192
 193     /* Number of calls to solib_add.  */
 194     unsigned solib_add_generation;
 195
 196     /* When an solib is added, it is also added to this vector.  This
 197        is so we can properly report solib changes to the user.  */
 198     VEC (so_list_ptr) *added_solibs;
 199
 200     /* When an solib is removed, its name is added to this vector.
 201        This is so we can properly report solib changes to the user.  */
 202     VEC (char_ptr) *deleted_solibs;
 203
 204     /* Per pspace data-pointers required by other GDB modules.  */
 205     REGISTRY_FIELDS;
 206   };
 207
 208 /* The object file that the main symbol table was loaded from (e.g. the
 209    argument to the "symbol-file" or "file" command).  */
 210
 211 #define symfile_objfile current_program_space->symfile_object_file
 212
 213 /* All known objfiles are kept in a linked list.  This points to the
 214    root of this list.  */
 215 #define object_files current_program_space->objfiles
 216
 217 /* The set of target sections matching the sections mapped into the
 218    current program space.  */
 219 #define current_target_sections (&current_program_space->target_sections)
 220
 221 /* The list of all program spaces.  There's always at least one.  */
 222 extern struct program_space *program_spaces;
 223
 224 /* The current program space.  This is always non-null.  */
 225 extern struct program_space *current_program_space;
 226
 227 #define ALL_PSPACES(pspace) \
 228   for ((pspace) = program_spaces; (pspace) != NULL; (pspace) = (pspace)->next)
 229
 230 /* Add a new empty program space, and assign ASPACE to it.  Returns the
 231    pointer to the new object.  */
 232 extern struct program_space *add_program_space (struct address_space *aspace);
 233
 234 /* Release PSPACE and removes it from the pspace list.  */
 235 extern void remove_program_space (struct program_space *pspace);
 236
 237 /* Returns the number of program spaces listed.  */
 238 extern int number_of_program_spaces (void);
 239
 240 /* Copies program space SRC to DEST.  Copies the main executable file,
 241    and the main symbol file.  Returns DEST.  */
 242 extern struct program_space *clone_program_space (struct program_space *dest,
 243                                                 struct program_space *src);
 244
 245 /* Save the current program space so that it may be restored by a later
 246    call to do_cleanups.  Returns the struct cleanup pointer needed for
 247    later doing the cleanup.  */
 248 extern struct cleanup *save_current_program_space (void);
 249
 250 /* Sets PSPACE as the current program space.  This is usually used
 251    instead of set_current_space_and_thread when the current
 252    thread/inferior is not important for the operations that follow.
 253    E.g., when accessing the raw symbol tables.  If memory access is
 254    required, then you should use switch_to_program_space_and_thread.
 255    Otherwise, it is the caller's responsibility to make sure that the
 256    currently selected inferior/thread matches the selected program
 257    space.  */
 258 extern void set_current_program_space (struct program_space *pspace);
 259
 260 /* Saves the current thread (may be null), frame and program space in
 261    the current cleanup chain.  */
 262 extern struct cleanup *save_current_space_and_thread (void);
 263
 264 /* Switches full context to program space PSPACE.  Switches to the
 265    first thread found bound to PSPACE.  */
 266 extern void switch_to_program_space_and_thread (struct program_space *pspace);
 267
 268 /* Create a new address space object, and add it to the list.  */
 269 extern struct address_space *new_address_space (void);
 270
 271 /* Maybe create a new address space object, and add it to the list, or
 272    return a pointer to an existing address space, in case inferiors
 273    share an address space.  */
 274 extern struct address_space *maybe_new_address_space (void);
 275
 276 /* Returns the integer address space id of ASPACE.  */
 277 extern int address_space_num (struct address_space *aspace);
 278
 279 /* Update all program spaces matching to address spaces.  The user may
 280    have created several program spaces, and loaded executables into
 281    them before connecting to the target interface that will create the
 282    inferiors.  All that happens before GDB has a chance to know if the
 283    inferiors will share an address space or not.  Call this after
 284    having connected to the target interface and having fetched the
 285    target description, to fixup the program/address spaces
 286    mappings.  */
 287 extern void update_address_spaces (void);
 288
 289 /* Prune away automatically added program spaces that aren't required
 290    anymore.  */
 291 extern void prune_program_spaces (void);
 292
 293 /* Reset saved solib data at the start of an solib event.  This lets
 294    us properly collect the data when calling solib_add, so it can then
 295    later be printed.  */
 296 extern void clear_program_space_solib_cache (struct program_space *);
 297
 298 /* Keep a registry of per-pspace data-pointers required by other GDB
 299    modules.  */
 300
 301 DECLARE_REGISTRY (program_space);
 302
 303 #endif