gdb/progspace.h

   1 /* Program and address space management, for GDB, the GNU debugger.
   2
   3    Copyright (C) 2009, 2010 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
  27 struct target_ops;
  28 struct bfd;
  29 struct objfile;
  30 struct inferior;
  31 struct exec;
  32 struct address_space;
  33 struct program_space_data;
  34
  35 /* A program space represents a symbolic view of an address space.
  36    Roughly speaking, it holds all the data associated with a
  37    non-running-yet program (main executable, main symbols), and when
  38    an inferior is running and is bound to it, includes the list of its
  39    mapped in shared libraries.
  40
  41    In the traditional debugging scenario, there's a 1-1 correspondence
  42    among program spaces, inferiors and address spaces, like so:
  43
  44      pspace1 (prog1) <--> inf1(pid1) <--> aspace1
  45
  46    In the case of debugging more than one traditional unix process or
  47    program, we still have:
  48
  49      |-----------------+------------+---------|
  50      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  51      |----------------------------------------|
  52      | pspace2 (prog1) | no inf yet | aspace2 |
  53      |-----------------+------------+---------|
  54      | pspace3 (prog2) | inf2(pid2) | aspace3 |
  55      |-----------------+------------+---------|
  56
  57    In the former example, if inf1 forks (and GDB stays attached to
  58    both processes), the new child will have its own program and
  59    address spaces.  Like so:
  60
  61      |-----------------+------------+---------|
  62      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  63      |-----------------+------------+---------|
  64      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  65      |-----------------+------------+---------|
  66
  67    However, had inf1 from the latter case vforked instead, it would
  68    share the program and address spaces with its parent, until it
  69    execs or exits, like so:
  70
  71      |-----------------+------------+---------|
  72      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  73      |                 | inf2(pid2) |         |
  74      |-----------------+------------+---------|
  75
  76    When the vfork child execs, it is finally given new program and
  77    address spaces.
  78
  79      |-----------------+------------+---------|
  80      | pspace1 (prog1) | inf1(pid1) | aspace1 |
  81      |-----------------+------------+---------|
  82      | pspace2 (prog1) | inf2(pid2) | aspace2 |
  83      |-----------------+------------+---------|
  84
  85    There are targets where the OS (if any) doesn't provide memory
  86    management or VM protection, where all inferiors share the same
  87    address space --- e.g. uClinux.  GDB models this by having all
  88    inferiors share the same address space, but, giving each its own
  89    program space, like so:
  90
  91      |-----------------+------------+---------|
  92      | pspace1 (prog1) | inf1(pid1) |         |
  93      |-----------------+------------+         |
  94      | pspace2 (prog1) | inf2(pid2) | aspace1 |
  95      |-----------------+------------+         |
  96      | pspace3 (prog2) | inf3(pid3) |         |
  97      |-----------------+------------+---------|
  98
  99    The address space sharing matters for run control and breakpoints
 100    management.  E.g., did we just hit a known breakpoint that we need
 101    to step over?  Is this breakpoint a duplicate of this other one, or
 102    do I need to insert a trap?
 103
 104    Then, there are targets where all symbols look the same for all
 105    inferiors, although each has its own address space, as e.g.,
 106    Ericsson DICOS.  In such case, the model is:
 107
 108      |---------+------------+---------|
 109      |         | inf1(pid1) | aspace1 |
 110      |         +------------+---------|
 111      | pspace  | inf2(pid2) | aspace2 |
 112      |         +------------+---------|
 113      |         | inf3(pid3) | aspace3 |
 114      |---------+------------+---------|
 115
 116    Note however, that the DICOS debug API takes care of making GDB
 117    believe that breakpoints are "global".  That is, although each
 118    process does have its own private copy of data symbols (just like a
 119    bunch of forks), to the breakpoints module, all processes share a
 120    single address space, so all breakpoints set at the same address
 121    are duplicates of each other, even breakpoints set in the data
 122    space (e.g., call dummy breakpoints placed on stack).  This allows
 123    a simplification in the spaces implementation: we avoid caring for
 124    a many-many links between address and program spaces.  Either
 125    there's a single address space bound to the program space
 126    (traditional unix/uClinux), or, in the DICOS case, the address
 127    space bound to the program space is mostly ignored.  */
 128
 129 /* The program space structure.  */
 130
 131 struct program_space
 132   {
 133     /* Pointer to next in linked list.  */
 134     struct program_space *next;
 135
 136     /* Unique ID number.  */
 137     int num;
 138
 139     /* The main executable loaded into this program space.  This is
 140        managed by the exec target.  */
 141
 142     /* The BFD handle for the main executable.  */
 143     bfd *ebfd;
 144     /* The last-modified time, from when the exec was brought in.  */
 145     long ebfd_mtime;
 146
 147     /* The address space attached to this program space.  More than one
 148        program space may be bound to the same address space.  In the
 149        traditional unix-like debugging scenario, this will usually
 150        match the address space bound to the inferior, and is mostly
 151        used by the breakpoints module for address matches.  If the
 152        target shares a program space for all inferiors and breakpoints
 153        are global, then this field is ignored (we don't currently
 154        support inferiors sharing a program space if the target doesn't
 155        make breakpoints global).  */
 156     struct address_space *aspace;
 157
 158     /* True if this program space's section offsets don't yet represent
 159        the final offsets of the "live" address space (that is, the
 160        section addresses still require the relocation offsets to be
 161        applied, and hence we can't trust the section addresses for
 162        anything that pokes at live memory).  E.g., for qOffsets
 163        targets, or for PIE executables, until we connect and ask the
 164        target for the final relocation offsets, the symbols we've used
 165        to set breakpoints point at the wrong addresses.  */
 166     int executing_startup;
 167
 168     /* True if no breakpoints should be inserted in this program
 169        space.  */
 170     int breakpoints_not_allowed;
 171
 172     /* The object file that the main symbol table was loaded from
 173        (e.g. the argument to the "symbol-file" or "file" command).  */
 174     struct objfile *symfile_object_file;
 175
 176     /* All known objfiles are kept in a linked list.  This points to
 177        the head of this list. */
 178     struct objfile *objfiles;
 179
 180     /* The set of target sections matching the sections mapped into
 181        this program space.  Managed by both exec_ops and solib.c.  */
 182     struct target_section_table target_sections;
 183
 184     /* List of shared objects mapped into this space.  Managed by
 185        solib.c.  */
 186     struct so_list *so_list;
 187
 188     /* Per pspace data-pointers required by other GDB modules.  */
 189     void **data;
 190     unsigned num_data;
 191   };
 192
 193 /* The object file that the main symbol table was loaded from (e.g. the
 194    argument to the "symbol-file" or "file" command).  */
 195
 196 #define symfile_objfile current_program_space->symfile_object_file
 197
 198 /* All known objfiles are kept in a linked list.  This points to the
 199    root of this list. */
 200 #define object_files current_program_space->objfiles
 201
 202 /* The set of target sections matching the sections mapped into the
 203    current program space.  */
 204 #define current_target_sections (&current_program_space->target_sections)
 205
 206 /* The list of all program spaces.  There's always at least one.  */
 207 extern struct program_space *program_spaces;
 208
 209 /* The current program space.  This is always non-null.  */
 210 extern struct program_space *current_program_space;
 211
 212 #define ALL_PSPACES(pspace) \
 213   for ((pspace) = program_spaces; (pspace) != NULL; (pspace) = (pspace)->next)
 214
 215 /* Add a new empty program space, and assign ASPACE to it.  Returns the
 216    pointer to the new object.  */
 217 extern struct program_space *add_program_space (struct address_space *aspace);
 218
 219 /* Release PSPACE and removes it from the pspace list.  */
 220 extern void remove_program_space (struct program_space *pspace);
 221
 222 /* Returns the number of program spaces listed.  */
 223 extern int number_of_program_spaces (void);
 224
 225 /* Copies program space SRC to DEST.  Copies the main executable file,
 226    and the main symbol file.  Returns DEST.  */
 227 extern struct program_space *clone_program_space (struct program_space *dest,
 228                                                 struct program_space *src);
 229
 230 /* Save the current program space so that it may be restored by a later
 231    call to do_cleanups.  Returns the struct cleanup pointer needed for
 232    later doing the cleanup.  */
 233 extern struct cleanup *save_current_program_space (void);
 234
 235 /* Sets PSPACE as the current program space.  This is usually used
 236    instead of set_current_space_and_thread when the current
 237    thread/inferior is not important for the operations that follow.
 238    E.g., when accessing the raw symbol tables.  If memory access is
 239    required, then you should use switch_to_program_space_and_thread.
 240    Otherwise, it is the caller's responsibility to make sure that the
 241    currently selected inferior/thread matches the selected program
 242    space.  */
 243 extern void set_current_program_space (struct program_space *pspace);
 244
 245 /* Saves the current thread (may be null), frame and program space in
 246    the current cleanup chain.  */
 247 extern struct cleanup *save_current_space_and_thread (void);
 248
 249 /* Switches full context to program space PSPACE.  Switches to the
 250    first thread found bound to PSPACE.  */
 251 extern void switch_to_program_space_and_thread (struct program_space *pspace);
 252
 253 /* Create a new address space object, and add it to the list.  */
 254 extern struct address_space *new_address_space (void);
 255
 256 /* Maybe create a new address space object, and add it to the list, or
 257    return a pointer to an existing address space, in case inferiors
 258    share an address space.  */
 259 extern struct address_space *maybe_new_address_space (void);
 260
 261 /* Returns the integer address space id of ASPACE.  */
 262 extern int address_space_num (struct address_space *aspace);
 263
 264 /* Update all program spaces matching to address spaces.  The user may
 265    have created several program spaces, and loaded executables into
 266    them before connecting to the target interface that will create the
 267    inferiors.  All that happens before GDB has a chance to know if the
 268    inferiors will share an address space or not.  Call this after
 269    having connected to the target interface and having fetched the
 270    target description, to fixup the program/address spaces
 271    mappings.  */
 272 extern void update_address_spaces (void);
 273
 274 /* Prune away automatically added program spaces that aren't required
 275    anymore.  */
 276 extern void prune_program_spaces (void);
 277
 278 /* Keep a registry of per-pspace data-pointers required by other GDB
 279    modules.  */
 280
 281 extern const struct program_space_data *register_program_space_data (void);
 282 extern const struct program_space_data *register_program_space_data_with_cleanup
 283   (void (*cleanup) (struct program_space *, void *));
 284 extern void clear_program_space_data (struct program_space *pspace);
 285 extern void set_program_space_data (struct program_space *pspace,
 286                               const struct program_space_data *data, void *value);
 287 extern void *program_space_data (struct program_space *pspace,
 288                            const struct program_space_data *data);
 289
 290 #endif