| 1 | /* Definitions for symbol file management in GDB. |
| 2 | Copyright (C) 1992 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of GDB. |
| 5 | |
| 6 | This program is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 2 of the License, or |
| 9 | (at your option) any later version. |
| 10 | |
| 11 | This program is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with this program; if not, write to the Free Software |
| 18 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ |
| 19 | |
| 20 | #if !defined (OBJFILES_H) |
| 21 | #define OBJFILES_H |
| 22 | |
| 23 | /* This structure maintains information on a per-objfile basis about the |
| 24 | "entry point" of the objfile, and the scope within which the entry point |
| 25 | exists. It is possible that gdb will see more than one objfile that is |
| 26 | executable, each with it's own entry point. |
| 27 | |
| 28 | For example, for dynamically linked executables in SVR4, the dynamic linker |
| 29 | code is contained within the shared C library, which is actually executable |
| 30 | and is run by the kernel first when an exec is done of a user executable |
| 31 | that is dynamically linked. The dynamic linker within the shared C library |
| 32 | then maps in the various program segments in the user executable and jumps |
| 33 | to the user executable's recorded entry point, as if the call had been made |
| 34 | directly by the kernel. |
| 35 | |
| 36 | The traditional gdb method of using this info is to use the recorded entry |
| 37 | point to set the variables entry_file_lowpc and entry_file_highpc from |
| 38 | the debugging information, where these values are the starting address |
| 39 | (inclusive) and ending address (exclusive) of the instruction space in the |
| 40 | executable which correspond to the "startup file", I.E. crt0.o in most |
| 41 | cases. This file is assumed to be a startup file and frames with pc's |
| 42 | inside it are treated as nonexistent. Setting these variables is necessary |
| 43 | so that backtraces do not fly off the bottom of the stack (or top, depending |
| 44 | upon your stack orientation). |
| 45 | |
| 46 | Gdb also supports an alternate method to avoid running off the top/bottom |
| 47 | of the stack. |
| 48 | |
| 49 | There are two frames that are "special", the frame for the function |
| 50 | containing the process entry point, since it has no predecessor frame, |
| 51 | and the frame for the function containing the user code entry point |
| 52 | (the main() function), since all the predecessor frames are for the |
| 53 | process startup code. Since we have no guarantee that the linked |
| 54 | in startup modules have any debugging information that gdb can use, |
| 55 | we need to avoid following frame pointers back into frames that might |
| 56 | have been built in the startup code, as we might get hopelessly |
| 57 | confused. However, we almost always have debugging information |
| 58 | available for main(). |
| 59 | |
| 60 | These variables are used to save the range of PC values which are valid |
| 61 | within the main() function and within the function containing the process |
| 62 | entry point. If we always consider the frame for main() as the outermost |
| 63 | frame when debugging user code, and the frame for the process entry |
| 64 | point function as the outermost frame when debugging startup code, then |
| 65 | all we have to do is have FRAME_CHAIN_VALID return false whenever a |
| 66 | frame's current PC is within the range specified by these variables. |
| 67 | In essence, we set "ceilings" in the frame chain beyond which we will |
| 68 | not proceed when following the frame chain back up the stack. |
| 69 | |
| 70 | A nice side effect is that we can still debug startup code without |
| 71 | running off the end of the frame chain, assuming that we have usable |
| 72 | debugging information in the startup modules, and if we choose to not |
| 73 | use the block at main, or can't find it for some reason, everything |
| 74 | still works as before. And if we have no startup code debugging |
| 75 | information but we do have usable information for main(), backtraces |
| 76 | from user code don't go wandering off into the startup code. |
| 77 | |
| 78 | To use this method, define your FRAME_CHAIN_VALID macro like: |
| 79 | |
| 80 | #define FRAME_CHAIN_VALID(chain, thisframe) \ |
| 81 | (chain != 0 \ |
| 82 | && !(inside_main_func ((thisframe)->pc)) \ |
| 83 | && !(inside_entry_func ((thisframe)->pc))) |
| 84 | |
| 85 | and add initializations of the four scope controlling variables inside |
| 86 | the object file / debugging information processing modules. */ |
| 87 | |
| 88 | struct entry_info |
| 89 | { |
| 90 | |
| 91 | /* The value we should use for this objects entry point. |
| 92 | The illegal/unknown value needs to be something other than 0, ~0 |
| 93 | for instance, which is much less likely than 0. */ |
| 94 | |
| 95 | CORE_ADDR entry_point; |
| 96 | |
| 97 | /* Start (inclusive) and end (exclusive) of function containing the |
| 98 | entry point. */ |
| 99 | |
| 100 | CORE_ADDR entry_func_lowpc; |
| 101 | CORE_ADDR entry_func_highpc; |
| 102 | |
| 103 | /* Start (inclusive) and end (exclusive) of object file containing the |
| 104 | entry point. */ |
| 105 | |
| 106 | CORE_ADDR entry_file_lowpc; |
| 107 | CORE_ADDR entry_file_highpc; |
| 108 | |
| 109 | /* Start (inclusive) and end (exclusive) of the user code main() function. */ |
| 110 | |
| 111 | CORE_ADDR main_func_lowpc; |
| 112 | CORE_ADDR main_func_highpc; |
| 113 | |
| 114 | }; |
| 115 | |
| 116 | |
| 117 | /* Master structure for keeping track of each input file from which |
| 118 | gdb reads symbols. One of these is allocated for each such file we |
| 119 | access, e.g. the exec_file, symbol_file, and any shared library object |
| 120 | files. */ |
| 121 | |
| 122 | struct objfile |
| 123 | { |
| 124 | |
| 125 | /* All struct objfile's are chained together by their next pointers. |
| 126 | The global variable "object_files" points to the first link in this |
| 127 | chain. |
| 128 | |
| 129 | FIXME: There is a problem here if the objfile is reusable, and if |
| 130 | multiple users are to be supported. The problem is that the objfile |
| 131 | list is linked through a member of the objfile struct itself, which |
| 132 | is only valid for one gdb process. The list implementation needs to |
| 133 | be changed to something like: |
| 134 | |
| 135 | struct list {struct list *next; struct objfile *objfile}; |
| 136 | |
| 137 | where the list structure is completely maintained separately within |
| 138 | each gdb process. */ |
| 139 | |
| 140 | struct objfile *next; |
| 141 | |
| 142 | /* The object file's name. Malloc'd; free it if you free this struct. */ |
| 143 | |
| 144 | char *name; |
| 145 | |
| 146 | /* Some flag bits for this objfile. */ |
| 147 | |
| 148 | unsigned short flags; |
| 149 | |
| 150 | /* Each objfile points to a linked list of symtabs derived from this file, |
| 151 | one symtab structure for each compilation unit (source file). Each link |
| 152 | in the symtab list contains a backpointer to this objfile. */ |
| 153 | |
| 154 | struct symtab *symtabs; |
| 155 | |
| 156 | /* Each objfile points to a linked list of partial symtabs derived from |
| 157 | this file, one partial symtab structure for each compilation unit |
| 158 | (source file). */ |
| 159 | |
| 160 | struct partial_symtab *psymtabs; |
| 161 | |
| 162 | /* List of freed partial symtabs, available for re-use */ |
| 163 | |
| 164 | struct partial_symtab *free_psymtabs; |
| 165 | |
| 166 | /* The object file's BFD. Can be null, in which case bfd_open (name) and |
| 167 | put the result here. */ |
| 168 | |
| 169 | bfd *obfd; |
| 170 | |
| 171 | /* The modification timestamp of the object file, as of the last time |
| 172 | we read its symbols. */ |
| 173 | |
| 174 | long mtime; |
| 175 | |
| 176 | /* Obstacks to hold objects that should be freed when we load a new symbol |
| 177 | table from this object file. */ |
| 178 | |
| 179 | struct obstack psymbol_obstack; /* Partial symbols */ |
| 180 | struct obstack symbol_obstack; /* Full symbols */ |
| 181 | struct obstack type_obstack; /* Types */ |
| 182 | |
| 183 | /* Vectors of all partial symbols read in from file. The actual data |
| 184 | is stored in the psymbol_obstack. */ |
| 185 | |
| 186 | struct psymbol_allocation_list global_psymbols; |
| 187 | struct psymbol_allocation_list static_psymbols; |
| 188 | |
| 189 | /* Each file contains a pointer to an array of minimal symbols for all |
| 190 | global symbols that are defined within the file. The array is terminated |
| 191 | by a "null symbol", one that has a NULL pointer for the name and a zero |
| 192 | value for the address. This makes it easy to walk through the array |
| 193 | when passed a pointer to somewhere in the middle of it. There is also |
| 194 | a count of the number of symbols, which does include the terminating |
| 195 | null symbol. The array itself, as well as all the data that it points |
| 196 | to, should be allocated on the symbol_obstack for this file. */ |
| 197 | |
| 198 | struct minimal_symbol *msymbols; |
| 199 | int minimal_symbol_count; |
| 200 | |
| 201 | /* For object file formats which don't specify fundamental types, gdb |
| 202 | can create such types. For now, it maintains a vector of pointers |
| 203 | to these internally created fundamental types on a per objfile basis, |
| 204 | however it really should ultimately keep them on a per-compilation-unit |
| 205 | basis, to account for linkage-units that consist of a number of |
| 206 | compilation units that may have different fundamental types, such as |
| 207 | linking C modules with ADA modules, or linking C modules that are |
| 208 | compiled with 32-bit ints with C modules that are compiled with 64-bit |
| 209 | ints (not inherently evil with a smarter linker). */ |
| 210 | |
| 211 | struct type **fundamental_types; |
| 212 | |
| 213 | /* The mmalloc() malloc-descriptor for this objfile if we are using |
| 214 | the memory mapped malloc() package to manage storage for this objfile's |
| 215 | data. NULL if we are not. */ |
| 216 | |
| 217 | PTR md; |
| 218 | |
| 219 | /* The file descriptor that was used to obtain the mmalloc descriptor |
| 220 | for this objfile. If we call mmalloc_detach with the malloc descriptor |
| 221 | we should then close this file descriptor. */ |
| 222 | |
| 223 | int mmfd; |
| 224 | |
| 225 | /* Structure which keeps track of functions that manipulate objfile's |
| 226 | of the same type as this objfile. I.E. the function to read partial |
| 227 | symbols for example. Note that this structure is in statically |
| 228 | allocated memory, and is shared by all objfiles that use the |
| 229 | object module reader of this type. */ |
| 230 | |
| 231 | struct sym_fns *sf; |
| 232 | |
| 233 | /* The per-objfile information about the entry point, the scope (file/func) |
| 234 | containing the entry point, and the scope of the user's main() func. */ |
| 235 | |
| 236 | struct entry_info ei; |
| 237 | |
| 238 | /* Hook for information which is shared by sym_init and sym_read for |
| 239 | this objfile. It is typically a pointer to malloc'd memory. */ |
| 240 | |
| 241 | PTR sym_private; |
| 242 | |
| 243 | }; |
| 244 | |
| 245 | /* Defines for the objfile flag word. */ |
| 246 | |
| 247 | /* Gdb can arrange to allocate storage for all objects related to a |
| 248 | particular objfile in a designated section of it's address space, |
| 249 | managed at a low level by mmap() and using a special version of |
| 250 | malloc that handles malloc/free/realloc on top of the mmap() interface. |
| 251 | This allows the "internal gdb state" for a particular objfile to be |
| 252 | dumped to a gdb state file and subsequently reloaded at a later time. */ |
| 253 | |
| 254 | #define OBJF_MAPPED (1 << 0) /* Objfile data is mmap'd */ |
| 255 | |
| 256 | /* When using mapped/remapped predigested gdb symbol information, we need |
| 257 | a flag that indicates that we have previously done an initial symbol |
| 258 | table read from this particular objfile. We can't just look for the |
| 259 | absence of any of the three symbol tables (msymbols, psymtab, symtab) |
| 260 | because if the file has no symbols for example, none of these will |
| 261 | exist. */ |
| 262 | |
| 263 | #define OBJF_SYMS (1 << 1) /* Have tried to read symbols */ |
| 264 | |
| 265 | /* The object file that the main symbol table was loaded from (e.g. the |
| 266 | argument to the "symbol-file" or "file" command). */ |
| 267 | |
| 268 | extern struct objfile *symfile_objfile; |
| 269 | |
| 270 | /* When we need to allocate a new type, we need to know which type_obstack |
| 271 | to allocate the type on, since there is one for each objfile. The places |
| 272 | where types are allocated are deeply buried in function call hierarchies |
| 273 | which know nothing about objfiles, so rather than trying to pass a |
| 274 | particular objfile down to them, we just do an end run around them and |
| 275 | set current_objfile to be whatever objfile we expect to be using at the |
| 276 | time types are being allocated. For instance, when we start reading |
| 277 | symbols for a particular objfile, we set current_objfile to point to that |
| 278 | objfile, and when we are done, we set it back to NULL, to ensure that we |
| 279 | never put a type someplace other than where we are expecting to put it. |
| 280 | FIXME: Maybe we should review the entire type handling system and |
| 281 | see if there is a better way to avoid this problem. */ |
| 282 | |
| 283 | extern struct objfile *current_objfile; |
| 284 | |
| 285 | /* All known objfiles are kept in a linked list. This points to the |
| 286 | root of this list. */ |
| 287 | |
| 288 | extern struct objfile *object_files; |
| 289 | |
| 290 | /* Declarations for functions defined in objfiles.c */ |
| 291 | |
| 292 | extern struct objfile * |
| 293 | allocate_objfile PARAMS ((bfd *, int)); |
| 294 | |
| 295 | extern void |
| 296 | unlink_objfile PARAMS ((struct objfile *)); |
| 297 | |
| 298 | extern void |
| 299 | free_objfile PARAMS ((struct objfile *)); |
| 300 | |
| 301 | extern void |
| 302 | free_all_objfiles PARAMS ((void)); |
| 303 | |
| 304 | extern int |
| 305 | have_partial_symbols PARAMS ((void)); |
| 306 | |
| 307 | extern int |
| 308 | have_full_symbols PARAMS ((void)); |
| 309 | |
| 310 | /* Functions for dealing with the minimal symbol table, really a misc |
| 311 | address<->symbol mapping for things we don't have debug symbols for. */ |
| 312 | |
| 313 | extern int |
| 314 | have_minimal_symbols PARAMS ((void)); |
| 315 | |
| 316 | |
| 317 | /* Traverse all object files. ALL_OBJFILES_SAFE works even if you delete |
| 318 | the objfile during the traversal. */ |
| 319 | |
| 320 | #define ALL_OBJFILES(obj) \ |
| 321 | for ((obj) = object_files; (obj) != NULL; (obj) = (obj)->next) |
| 322 | |
| 323 | #define ALL_OBJFILES_SAFE(obj,nxt) \ |
| 324 | for ((obj) = object_files; \ |
| 325 | (obj) != NULL? ((nxt)=(obj)->next,1) :0; \ |
| 326 | (obj) = (nxt)) |
| 327 | |
| 328 | |
| 329 | /* Traverse all symtabs in one objfile. */ |
| 330 | |
| 331 | #define ALL_OBJFILE_SYMTABS(objfile, s) \ |
| 332 | for ((s) = (objfile) -> symtabs; (s) != NULL; (s) = (s) -> next) |
| 333 | |
| 334 | /* Traverse all psymtabs in one objfile. */ |
| 335 | |
| 336 | #define ALL_OBJFILE_PSYMTABS(objfile, p) \ |
| 337 | for ((p) = (objfile) -> psymtabs; (p) != NULL; (p) = (p) -> next) |
| 338 | |
| 339 | /* Traverse all minimal symbols in one objfile. */ |
| 340 | |
| 341 | #define ALL_OBJFILE_MSYMBOLS(objfile, m) \ |
| 342 | for ((m) = (objfile) -> msymbols; (m)->name != NULL; (m)++) |
| 343 | |
| 344 | |
| 345 | /* Traverse all symtabs in all objfiles. */ |
| 346 | |
| 347 | #define ALL_SYMTABS(objfile, s) \ |
| 348 | ALL_OBJFILES (objfile) \ |
| 349 | ALL_OBJFILE_SYMTABS (objfile, s) |
| 350 | |
| 351 | /* Traverse all psymtabs in all objfiles. */ |
| 352 | |
| 353 | #define ALL_PSYMTABS(objfile, p) \ |
| 354 | ALL_OBJFILES (objfile) \ |
| 355 | ALL_OBJFILE_PSYMTABS (objfile, p) |
| 356 | |
| 357 | /* Traverse all minimal symbols in all objfiles. */ |
| 358 | |
| 359 | #define ALL_MSYMBOLS(objfile, m) \ |
| 360 | ALL_OBJFILES (objfile) \ |
| 361 | if ((objfile)->msymbols) \ |
| 362 | ALL_OBJFILE_MSYMBOLS (objfile, m) |
| 363 | |
| 364 | #endif /* !defined (OBJFILES_H) */ |