[Crash-utility] Re: [PATCH v2] symbols: expand all kernel module symtable if not all expanded previously
On 2023/11/17 16:52, Tao Liu wrote:
For the stacktrace of "dis -rl", it calls
dw2_expand_all_symtabs() to expand
all symtable of the objfile, or "*.ko.debug" in our case. However for
the stacktrace of "bt", it doesn't expand all, but only a subset of
symtable
which is enough to find a symbol by dw2_lookup_symbol(). As a result, the
objfile->compunit_symtabs, which is the head of a single linked list of
struct compunit_symtab, is not NULL but didn't contain all symtables. It
will not be reinitialized in gdb_get_line_number() by "dis -rl" because
!objfile_has_full_symbols(objfile) check will fail, so it cannot display
the proper code line number data.
Since objfile_has_full_symbols(objfile) check cannot ensure all symbols
been expanded, this patch add a new member as a flag for struct objfile
to record if all symbols have been expanded. The flag will be set only ofter
expand_all_symtabs been called.
Thank you for the v2.
Great, I can't think of any better way than this for now.
Acked-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
(maybe I will reduce the commit log a bit when merging.)
Thanks,
Kazu
>
> Signed-off-by: Tao Liu <ltao(a)redhat.com>
> ---
> v1 -> v2: new method for kernel module symtabs expansion.
> v1: expand all kernel modules symtabs when loading by mod -s/-S
> v2: record if a specific kernel module's symtab been all expanded,
> and skip re-expansion if true.
> ---
> gdb-10.2.patch | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 50 insertions(+)
>
> diff --git a/gdb-10.2.patch b/gdb-10.2.patch
> index d81030d..2f7d585 100644
> --- a/gdb-10.2.patch
> +++ b/gdb-10.2.patch
> @@ -3187,3 +3187,53 @@ exit 0
> result = stringtab + symbol_entry->_n._n_n._n_offset;
> }
> else
> +--- gdb-10.2/gdb/objfiles.h.orig
> ++++ gdb-10.2/gdb/objfiles.h
> +@@ -712,6 +712,8 @@ struct objfile
> + next time. If an objfile does not have the symbols, it will
> + never have them. */
> + bool skip_jit_symbol_lookup = false;
> ++
> ++ bool all_symtabs_expanded = false;
> + };
> +
> + /* A deleter for objfile. */
> +--- gdb-10.2/gdb/symfile.c.orig
> ++++ gdb-10.2/gdb/symfile.c
> +@@ -1133,8 +1133,10 @@ symbol_file_add_with_addrs (bfd *abfd, const char *name,
> + printf_filtered (_("Expanding full symbols from %ps...\n"),
> + styled_string (file_name_style.style (), name));
> +
> +- if (objfile->sf)
> ++ if (objfile->sf) {
> + objfile->sf->qf->expand_all_symtabs (objfile);
> ++ objfile->all_symtabs_expanded = true;
> ++ }
> + }
> +
> + /* Note that we only print a message if we have no symbols and have
> +--- gdb-10.2/gdb/symtab.c.orig
> ++++ gdb-10.2/gdb/symtab.c
> +@@ -7097,8 +7097,9 @@ gdb_get_line_number(struct gnu_request *req)
> + */
> + if (req->lm) {
> + objfile = req->lm->loaded_objfile;
> +- if (!objfile_has_full_symbols(objfile) &&
objfile->sf) {
> ++ if (!objfile->all_symtabs_expanded &&
objfile->sf) {
> +
objfile->sf->qf->expand_all_symtabs(objfile);
> ++ objfile->all_symtabs_expanded = true;
> + sal = find_pc_line(pc, 0);
> + }
> + }
> +@@ -7761,8 +7765,10 @@ iterate_datatypes (struct gnu_request *req)
> + {
> + for (objfile *objfile : current_program_space->objfiles ())
> + {
> +- if (objfile->sf)
> ++ if (objfile->sf) {
> + objfile->sf->qf->expand_all_symtabs(objfile);
> ++ objfile->all_symtabs_expanded = true;
> ++ }
> +
> + for (compunit_symtab *cust : objfile->compunits ())
> + {