mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-15 04:31:49 +08:00
3dd9bb4620
I found that these tests:
make check-gdb RUNTESTFLAGS="--target_board=cc-with-gdb-index gdb.base/maint.exp"
make check-gdb RUNTESTFLAGS="--target_board=cc-with-debug-names gdb.base/maint.exp"
were causing GDB to segfault. It turns out that this test runs this
command:
maint print psymbols -pc main /path/to/some/file
which tries to lookup the partial_symtab for 'main'. The problem is
that there is no partial_symtab for 'main' as we are using the
.gdb_index or .debug_names instead of partial_symtabs.
What happens is that maintenance_print_symbols calls
find_pc_sect_psymtab, which looks for the partial_symtab in the
objfile's objfile->partial_symtabs->psymtabs_addrmap.
This is a problem because when we are using the indexes
psymtabs_addrmap is reused to hold things other than partial_symtabs,
this can be seen in dwarf2read.c in create_addrmap_from_index and
create_addrmap_from_aranges. If we then lookup in psymtabs_addrmap we
end up returning a pointer to something that isn't really a
partial_symtab, after which everything goes wrong.
Initially I simply added a check at the start of find_pc_sect_psymtab
that the objfile had some partial_symtabs, like:
if (objfile->partial_symtabs->psymtabs == NULL)
return NULL;
Figuring that if there were no partial_symtabs at all then this
function should always return NULL, however, this caused a failure in
the test gdb.python/py-event.exp which I didn't dig into too deeply,
but seems to be that in this tests there are initially no psymtabs,
but the second part of find_pc_sect_psymtab does manage to read some
in from somewhere, with the check I added the test fails as we
returned NULL here and this caused GDB to load in the full symtabs
earlier than was expected.
Instead I chose to guard only the access to psymtabs_addrmap with a
check that the function has some psymtabs. This allows my original
tests to pass, and the py-event.exp test to pass too.
Now, a good argument can be made that we simply should never call
find_pc_sect_psymtab on an objfile that is using indexes instead of
partial_symtabs. I did consider this approach, we could easily add an
assert into find_pc_sect_psymtab that if we find a partial_symtab in
psymtabs_addrmap then the psymtabs pointer must be non-null. The
responsibility would then be on the user of find_pc_sect_psymtab to
ensure that the objfile being checked is suitable. In the end I
didn't take this approach as the check in find_pc_sect_psymtab is
cheap and this ensures that any future miss-uses of the function will
not cause problems.
I also extended the comment on psymtabs_addrmap to indicate that it
holds more than just partial_symtabs as this was not at all clear from
the original comment, and caused me some confusion when I was
initially debugging this problem.
gdb/ChangeLog:
* psymtab.c (find_pc_sect_psymtab): Move baseaddr local into more
inner scope, add check that the objfile has psymtabs before
checking psymtabs_addrmap.
* psymtab.h (psymtab_storage) <psymtabs_addrmap>: Extend comment.
158 lines
5.0 KiB
C++
158 lines
5.0 KiB
C++
/* Public partial symbol table definitions.
|
|
|
|
Copyright (C) 2009-2019 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 3 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, see <http://www.gnu.org/licenses/>. */
|
|
|
|
#ifndef PSYMTAB_H
|
|
#define PSYMTAB_H
|
|
|
|
#include "gdb_obstack.h"
|
|
#include "symfile.h"
|
|
#include "gdbsupport/next-iterator.h"
|
|
#include "bcache.h"
|
|
|
|
struct partial_symbol;
|
|
|
|
/* An instance of this class manages the partial symbol tables and
|
|
partial symbols for a given objfile.
|
|
|
|
The core psymtab functions -- those in psymtab.c -- arrange for
|
|
nearly all psymtab- and psymbol-related allocations to happen
|
|
either in the psymtab_storage object (either on its obstack or in
|
|
other memory managed by this class), or on the per-BFD object. The
|
|
only link from the psymtab storage object back to the objfile (or
|
|
objfile_obstack) that is made by the core psymtab code is the
|
|
compunit_symtab member in the psymtab.
|
|
|
|
However, it is up to each symbol reader to maintain this invariant
|
|
in other ways, if it wants to reuse psymtabs across multiple
|
|
objfiles. The main issue here is ensuring that read_symtab_private
|
|
does not point into objfile_obstack. */
|
|
|
|
class psymtab_storage
|
|
{
|
|
public:
|
|
|
|
psymtab_storage ();
|
|
|
|
~psymtab_storage ();
|
|
|
|
DISABLE_COPY_AND_ASSIGN (psymtab_storage);
|
|
|
|
/* Discard all partial symbol tables starting with "psymtabs" and
|
|
proceeding until "to" has been discarded. */
|
|
|
|
void discard_psymtabs_to (struct partial_symtab *to)
|
|
{
|
|
while (psymtabs != to)
|
|
discard_psymtab (psymtabs);
|
|
}
|
|
|
|
/* Discard the partial symbol table. */
|
|
|
|
void discard_psymtab (struct partial_symtab *pst);
|
|
|
|
/* Return the obstack that is used for storage by this object. */
|
|
|
|
struct obstack *obstack ()
|
|
{
|
|
if (!m_obstack.has_value ())
|
|
m_obstack.emplace ();
|
|
return &*m_obstack;
|
|
}
|
|
|
|
/* Allocate storage for the "dependencies" field of a psymtab.
|
|
NUMBER says how many dependencies there are. */
|
|
|
|
struct partial_symtab **allocate_dependencies (int number)
|
|
{
|
|
return OBSTACK_CALLOC (obstack (), number, struct partial_symtab *);
|
|
}
|
|
|
|
/* Allocate a new psymtab on the psymtab obstack. The new psymtab
|
|
will be linked in to the "psymtabs" list, but otherwise all other
|
|
fields will be zero. */
|
|
|
|
struct partial_symtab *allocate_psymtab ();
|
|
|
|
typedef next_adapter<struct partial_symtab> partial_symtab_range;
|
|
|
|
/* A range adapter that makes it possible to iterate over all
|
|
psymtabs in one objfile. */
|
|
|
|
partial_symtab_range range ()
|
|
{
|
|
return partial_symtab_range (psymtabs);
|
|
}
|
|
|
|
|
|
/* 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 = nullptr;
|
|
|
|
/* Map addresses to the entries of PSYMTABS. It would be more efficient to
|
|
have a map per the whole process but ADDRMAP cannot selectively remove
|
|
its items during FREE_OBJFILE. This mapping is already present even for
|
|
PARTIAL_SYMTABs which still have no corresponding full SYMTABs read.
|
|
|
|
The DWARF parser reuses this addrmap to store things other than
|
|
psymtabs in the cases where debug information is being read from, for
|
|
example, the .debug-names section. */
|
|
|
|
struct addrmap *psymtabs_addrmap = nullptr;
|
|
|
|
/* A byte cache where we can stash arbitrary "chunks" of bytes that
|
|
will not change. */
|
|
|
|
struct bcache psymbol_cache;
|
|
|
|
/* Vectors of all partial symbols read in from file. The actual data
|
|
is stored in the objfile_obstack. */
|
|
|
|
std::vector<partial_symbol *> global_psymbols;
|
|
std::vector<partial_symbol *> static_psymbols;
|
|
|
|
private:
|
|
|
|
/* List of freed partial symtabs, available for re-use. */
|
|
|
|
struct partial_symtab *free_psymtabs = nullptr;
|
|
|
|
/* The obstack where allocations are made. This is lazily allocated
|
|
so that we don't waste memory when there are no psymtabs. */
|
|
|
|
gdb::optional<auto_obstack> m_obstack;
|
|
};
|
|
|
|
|
|
extern const struct quick_symbol_functions psym_functions;
|
|
|
|
extern const struct quick_symbol_functions dwarf2_gdb_index_functions;
|
|
extern const struct quick_symbol_functions dwarf2_debug_names_functions;
|
|
|
|
/* Ensure that the partial symbols for OBJFILE have been loaded. If
|
|
VERBOSE is non-zero, then this will print a message when symbols
|
|
are loaded. This function returns a range adapter suitable for
|
|
iterating over the psymtabs of OBJFILE. */
|
|
|
|
extern psymtab_storage::partial_symtab_range require_partial_symbols
|
|
(struct objfile *objfile, int verbose);
|
|
|
|
#endif /* PSYMTAB_H */
|