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Stan Shebs
1999-04-16 01:35:26 +00:00
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/* Definitions for symbol file management in GDB.
Copyright (C) 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#if !defined (OBJFILES_H)
#define OBJFILES_H
/* This structure maintains information on a per-objfile basis about the
"entry point" of the objfile, and the scope within which the entry point
exists. It is possible that gdb will see more than one objfile that is
executable, each with its own entry point.
For example, for dynamically linked executables in SVR4, the dynamic linker
code is contained within the shared C library, which is actually executable
and is run by the kernel first when an exec is done of a user executable
that is dynamically linked. The dynamic linker within the shared C library
then maps in the various program segments in the user executable and jumps
to the user executable's recorded entry point, as if the call had been made
directly by the kernel.
The traditional gdb method of using this info is to use the recorded entry
point to set the variables entry_file_lowpc and entry_file_highpc from
the debugging information, where these values are the starting address
(inclusive) and ending address (exclusive) of the instruction space in the
executable which correspond to the "startup file", I.E. crt0.o in most
cases. This file is assumed to be a startup file and frames with pc's
inside it are treated as nonexistent. Setting these variables is necessary
so that backtraces do not fly off the bottom of the stack.
Gdb also supports an alternate method to avoid running off the bottom
of the stack.
There are two frames that are "special", the frame for the function
containing the process entry point, since it has no predecessor frame,
and the frame for the function containing the user code entry point
(the main() function), since all the predecessor frames are for the
process startup code. Since we have no guarantee that the linked
in startup modules have any debugging information that gdb can use,
we need to avoid following frame pointers back into frames that might
have been built in the startup code, as we might get hopelessly
confused. However, we almost always have debugging information
available for main().
These variables are used to save the range of PC values which are valid
within the main() function and within the function containing the process
entry point. If we always consider the frame for main() as the outermost
frame when debugging user code, and the frame for the process entry
point function as the outermost frame when debugging startup code, then
all we have to do is have FRAME_CHAIN_VALID return false whenever a
frame's current PC is within the range specified by these variables.
In essence, we set "ceilings" in the frame chain beyond which we will
not proceed when following the frame chain back up the stack.
A nice side effect is that we can still debug startup code without
running off the end of the frame chain, assuming that we have usable
debugging information in the startup modules, and if we choose to not
use the block at main, or can't find it for some reason, everything
still works as before. And if we have no startup code debugging
information but we do have usable information for main(), backtraces
from user code don't go wandering off into the startup code.
To use this method, define your FRAME_CHAIN_VALID macro like:
#define FRAME_CHAIN_VALID(chain, thisframe) \
(chain != 0 \
&& !(inside_main_func ((thisframe)->pc)) \
&& !(inside_entry_func ((thisframe)->pc)))
and add initializations of the four scope controlling variables inside
the object file / debugging information processing modules. */
struct entry_info
{
/* The value we should use for this objects entry point.
The illegal/unknown value needs to be something other than 0, ~0
for instance, which is much less likely than 0. */
CORE_ADDR entry_point;
#define INVALID_ENTRY_POINT (~0) /* ~0 will not be in any file, we hope. */
/* Start (inclusive) and end (exclusive) of function containing the
entry point. */
CORE_ADDR entry_func_lowpc;
CORE_ADDR entry_func_highpc;
/* Start (inclusive) and end (exclusive) of object file containing the
entry point. */
CORE_ADDR entry_file_lowpc;
CORE_ADDR entry_file_highpc;
/* Start (inclusive) and end (exclusive) of the user code main() function. */
CORE_ADDR main_func_lowpc;
CORE_ADDR main_func_highpc;
/* Use these values when any of the above ranges is invalid. */
/* We use these values because it guarantees that there is no number that is
both >= LOWPC && < HIGHPC. It is also highly unlikely that 3 is a valid
module or function start address (as opposed to 0). */
#define INVALID_ENTRY_LOWPC (3)
#define INVALID_ENTRY_HIGHPC (1)
};
/* Sections in an objfile.
It is strange that we have both this notion of "sections"
and the one used by section_offsets. Section as used
here, (currently at least) means a BFD section, and the sections
are set up from the BFD sections in allocate_objfile.
The sections in section_offsets have their meaning determined by
the symbol format, and they are set up by the sym_offsets function
for that symbol file format.
I'm not sure this could or should be changed, however. */
struct obj_section {
CORE_ADDR addr; /* lowest address in section */
CORE_ADDR endaddr; /* 1+highest address in section */
/* This field is being used for nefarious purposes by syms_from_objfile.
It is said to be redundant with section_offsets; it's not really being
used that way, however, it's some sort of hack I don't understand
and am not going to try to eliminate (yet, anyway). FIXME.
It was documented as "offset between (end)addr and actual memory
addresses", but that's not true; addr & endaddr are actual memory
addresses. */
CORE_ADDR offset;
sec_ptr the_bfd_section; /* BFD section pointer */
/* Objfile this section is part of. */
struct objfile *objfile;
/* True if this "overlay section" is mapped into an "overlay region". */
int ovly_mapped;
};
/* An import entry contains information about a symbol that
is used in this objfile but not defined in it, and so needs
to be imported from some other objfile */
/* Currently we just store the name; no attributes. 1997-08-05 */
typedef char * ImportEntry;
/* An export entry contains information about a symbol that
is defined in this objfile and available for use in other
objfiles */
typedef struct {
char * name; /* name of exported symbol */
int address; /* offset subject to relocation */
/* Currently no other attributes 1997-08-05 */
} ExportEntry;
/* The "objstats" structure provides a place for gdb to record some
interesting information about its internal state at runtime, on a
per objfile basis, such as information about the number of symbols
read, size of string table (if any), etc. */
#if MAINTENANCE_CMDS
struct objstats {
int n_minsyms; /* Number of minimal symbols read */
int n_psyms; /* Number of partial symbols read */
int n_syms; /* Number of full symbols read */
int n_stabs; /* Number of ".stabs" read (if applicable) */
int n_types; /* Number of types */
int sz_strtab; /* Size of stringtable, (if applicable) */
};
#define OBJSTAT(objfile, expr) (objfile -> stats.expr)
#define OBJSTATS struct objstats stats
extern void print_objfile_statistics PARAMS ((void));
extern void print_symbol_bcache_statistics PARAMS ((void));
#else
#define OBJSTAT(objfile, expr) /* Nothing */
#define OBJSTATS /* Nothing */
#endif /* MAINTENANCE_CMDS */
/* Master structure for keeping track of each file from which
gdb reads symbols. There are several ways these get allocated: 1.
The main symbol file, symfile_objfile, set by the symbol-file command,
2. Additional symbol files added by the add-symbol-file command,
3. Shared library objfiles, added by ADD_SOLIB, 4. symbol files
for modules that were loaded when GDB attached to a remote system
(see remote-vx.c). */
struct objfile
{
/* All struct objfile's are chained together by their next pointers.
The global variable "object_files" points to the first link in this
chain.
FIXME: There is a problem here if the objfile is reusable, and if
multiple users are to be supported. The problem is that the objfile
list is linked through a member of the objfile struct itself, which
is only valid for one gdb process. The list implementation needs to
be changed to something like:
struct list {struct list *next; struct objfile *objfile};
where the list structure is completely maintained separately within
each gdb process. */
struct objfile *next;
/* The object file's name. Malloc'd; free it if you free this struct. */
char *name;
/* TRUE if this objfile was created because the user explicitly caused
it (e.g., used the add-symbol-file command).
*/
int user_loaded;
/* TRUE if this objfile was explicitly created to represent a solib.
(If FALSE, the objfile may actually be a solib. This can happen if
the user created the objfile by using the add-symbol-file command.
GDB doesn't in that situation actually check whether the file is a
solib. Rather, the target's implementation of the solib interface
is responsible for setting this flag when noticing solibs used by
an inferior.)
*/
int is_solib;
/* Some flag bits for this objfile. */
unsigned short flags;
/* Each objfile points to a linked list of symtabs derived from this file,
one symtab structure for each compilation unit (source file). Each link
in the symtab list contains a backpointer to this objfile. */
struct symtab *symtabs;
/* Each objfile points to a linked list of partial symtabs derived from
this file, one partial symtab structure for each compilation unit
(source file). */
struct partial_symtab *psymtabs;
/* List of freed partial symtabs, available for re-use */
struct partial_symtab *free_psymtabs;
/* The object file's BFD. Can be null if the objfile contains only
minimal symbols, e.g. the run time common symbols for SunOS4. */
bfd *obfd;
/* The modification timestamp of the object file, as of the last time
we read its symbols. */
long mtime;
/* Obstacks to hold objects that should be freed when we load a new symbol
table from this object file. */
struct obstack psymbol_obstack; /* Partial symbols */
struct obstack symbol_obstack; /* Full symbols */
struct obstack type_obstack; /* Types */
/* A byte cache where we can stash arbitrary "chunks" of bytes that
will not change. */
struct bcache psymbol_cache; /* Byte cache for partial syms */
/* Vectors of all partial symbols read in from file. The actual data
is stored in the psymbol_obstack. */
struct psymbol_allocation_list global_psymbols;
struct psymbol_allocation_list static_psymbols;
/* Each file contains a pointer to an array of minimal symbols for all
global symbols that are defined within the file. The array is terminated
by a "null symbol", one that has a NULL pointer for the name and a zero
value for the address. This makes it easy to walk through the array
when passed a pointer to somewhere in the middle of it. There is also
a count of the number of symbols, which does not include the terminating
null symbol. The array itself, as well as all the data that it points
to, should be allocated on the symbol_obstack for this file. */
struct minimal_symbol *msymbols;
int minimal_symbol_count;
/* For object file formats which don't specify fundamental types, gdb
can create such types. For now, it maintains a vector of pointers
to these internally created fundamental types on a per objfile basis,
however it really should ultimately keep them on a per-compilation-unit
basis, to account for linkage-units that consist of a number of
compilation units that may have different fundamental types, such as
linking C modules with ADA modules, or linking C modules that are
compiled with 32-bit ints with C modules that are compiled with 64-bit
ints (not inherently evil with a smarter linker). */
struct type **fundamental_types;
/* The mmalloc() malloc-descriptor for this objfile if we are using
the memory mapped malloc() package to manage storage for this objfile's
data. NULL if we are not. */
PTR md;
/* The file descriptor that was used to obtain the mmalloc descriptor
for this objfile. If we call mmalloc_detach with the malloc descriptor
we should then close this file descriptor. */
int mmfd;
/* Structure which keeps track of functions that manipulate objfile's
of the same type as this objfile. I.E. the function to read partial
symbols for example. Note that this structure is in statically
allocated memory, and is shared by all objfiles that use the
object module reader of this type. */
struct sym_fns *sf;
/* The per-objfile information about the entry point, the scope (file/func)
containing the entry point, and the scope of the user's main() func. */
struct entry_info ei;
/* Information about stabs. Will be filled in with a dbx_symfile_info
struct by those readers that need it. */
struct dbx_symfile_info *sym_stab_info;
/* Hook for information for use by the symbol reader (currently used
for information shared by sym_init and sym_read). It is
typically a pointer to malloc'd memory. The symbol reader's finish
function is responsible for freeing the memory thusly allocated. */
PTR sym_private;
/* Hook for target-architecture-specific information. This must
point to memory allocated on one of the obstacks in this objfile,
so that it gets freed automatically when reading a new object
file. */
PTR obj_private;
/* Set of relocation offsets to apply to each section.
Currently on the psymbol_obstack (which makes no sense, but I'm
not sure it's harming anything).
These offsets indicate that all symbols (including partial and
minimal symbols) which have been read have been relocated by this
much. Symbols which are yet to be read need to be relocated by
it. */
struct section_offsets *section_offsets;
int num_sections;
/* set of section begin and end addresses used to map pc addresses
into sections. Currently on the psymbol_obstack (which makes no
sense, but I'm not sure it's harming anything). */
struct obj_section
*sections,
*sections_end;
/* two auxiliary fields, used to hold the fp of separate symbol files */
FILE *auxf1, *auxf2;
/* Imported symbols */
ImportEntry * import_list;
int import_list_size;
/* Exported symbols */
ExportEntry * export_list;
int export_list_size;
/* Place to stash various statistics about this objfile */
OBJSTATS;
};
/* Defines for the objfile flag word. */
/* Gdb can arrange to allocate storage for all objects related to a
particular objfile in a designated section of its address space,
managed at a low level by mmap() and using a special version of
malloc that handles malloc/free/realloc on top of the mmap() interface.
This allows the "internal gdb state" for a particular objfile to be
dumped to a gdb state file and subsequently reloaded at a later time. */
#define OBJF_MAPPED (1 << 0) /* Objfile data is mmap'd */
/* When using mapped/remapped predigested gdb symbol information, we need
a flag that indicates that we have previously done an initial symbol
table read from this particular objfile. We can't just look for the
absence of any of the three symbol tables (msymbols, psymtab, symtab)
because if the file has no symbols for example, none of these will
exist. */
#define OBJF_SYMS (1 << 1) /* Have tried to read symbols */
/* When an object file has its functions reordered (currently Irix-5.2
shared libraries exhibit this behaviour), we will need an expensive
algorithm to locate a partial symtab or symtab via an address.
To avoid this penalty for normal object files, we use this flag,
whose setting is determined upon symbol table read in. */
#define OBJF_REORDERED (1 << 2) /* Functions are reordered */
/* Distinguish between an objfile for a shared library and a
"vanilla" objfile. */
#define OBJF_SHARED (1 << 3) /* From a shared library */
/* The object file that the main symbol table was loaded from (e.g. the
argument to the "symbol-file" or "file" command). */
extern struct objfile *symfile_objfile;
/* The object file that contains the runtime common minimal symbols
for SunOS4. Note that this objfile has no associated BFD. */
extern struct objfile *rt_common_objfile;
/* When we need to allocate a new type, we need to know which type_obstack
to allocate the type on, since there is one for each objfile. The places
where types are allocated are deeply buried in function call hierarchies
which know nothing about objfiles, so rather than trying to pass a
particular objfile down to them, we just do an end run around them and
set current_objfile to be whatever objfile we expect to be using at the
time types are being allocated. For instance, when we start reading
symbols for a particular objfile, we set current_objfile to point to that
objfile, and when we are done, we set it back to NULL, to ensure that we
never put a type someplace other than where we are expecting to put it.
FIXME: Maybe we should review the entire type handling system and
see if there is a better way to avoid this problem. */
extern struct objfile *current_objfile;
/* All known objfiles are kept in a linked list. This points to the
root of this list. */
extern struct objfile *object_files;
/* Declarations for functions defined in objfiles.c */
extern struct objfile *
allocate_objfile PARAMS ((bfd *, int, int, int));
extern int
build_objfile_section_table PARAMS ((struct objfile *));
extern void objfile_to_front PARAMS ((struct objfile *));
extern void
unlink_objfile PARAMS ((struct objfile *));
extern void
free_objfile PARAMS ((struct objfile *));
extern void
free_all_objfiles PARAMS ((void));
extern void
objfile_relocate PARAMS ((struct objfile *, struct section_offsets *));
extern int
have_partial_symbols PARAMS ((void));
extern int
have_full_symbols PARAMS ((void));
/* This operation deletes all objfile entries that represent solibs that
weren't explicitly loaded by the user, via e.g., the add-symbol-file
command.
*/
extern void
objfile_purge_solibs PARAMS ((void));
/* Functions for dealing with the minimal symbol table, really a misc
address<->symbol mapping for things we don't have debug symbols for. */
extern int
have_minimal_symbols PARAMS ((void));
extern struct obj_section *
find_pc_section PARAMS((CORE_ADDR pc));
extern struct obj_section *
find_pc_sect_section PARAMS((CORE_ADDR pc, asection *section));
extern int
in_plt_section PARAMS ((CORE_ADDR, char *));
/* Traverse all object files. ALL_OBJFILES_SAFE works even if you delete
the objfile during the traversal. */
#define ALL_OBJFILES(obj) \
for ((obj) = object_files; (obj) != NULL; (obj) = (obj)->next)
#define ALL_OBJFILES_SAFE(obj,nxt) \
for ((obj) = object_files; \
(obj) != NULL? ((nxt)=(obj)->next,1) :0; \
(obj) = (nxt))
/* Traverse all symtabs in one objfile. */
#define ALL_OBJFILE_SYMTABS(objfile, s) \
for ((s) = (objfile) -> symtabs; (s) != NULL; (s) = (s) -> next)
/* Traverse all psymtabs in one objfile. */
#define ALL_OBJFILE_PSYMTABS(objfile, p) \
for ((p) = (objfile) -> psymtabs; (p) != NULL; (p) = (p) -> next)
/* Traverse all minimal symbols in one objfile. */
#define ALL_OBJFILE_MSYMBOLS(objfile, m) \
for ((m) = (objfile) -> msymbols; SYMBOL_NAME(m) != NULL; (m)++)
/* Traverse all symtabs in all objfiles. */
#define ALL_SYMTABS(objfile, s) \
ALL_OBJFILES (objfile) \
ALL_OBJFILE_SYMTABS (objfile, s)
/* Traverse all psymtabs in all objfiles. */
#define ALL_PSYMTABS(objfile, p) \
ALL_OBJFILES (objfile) \
ALL_OBJFILE_PSYMTABS (objfile, p)
/* Traverse all minimal symbols in all objfiles. */
#define ALL_MSYMBOLS(objfile, m) \
ALL_OBJFILES (objfile) \
if ((objfile)->msymbols) \
ALL_OBJFILE_MSYMBOLS (objfile, m)
#define ALL_OBJFILE_OSECTIONS(objfile, osect) \
for (osect = objfile->sections; osect < objfile->sections_end; osect++)
#define ALL_OBJSECTIONS(objfile, osect) \
ALL_OBJFILES (objfile) \
ALL_OBJFILE_OSECTIONS (objfile, osect)
#endif /* !defined (OBJFILES_H) */