[Crash-utility] [PATCH 1/2] symbols: expand kernel modules symtable before symbols translation

The kernel modules symbol translation may change after a c expression evaluation. without patch: crash> mod -S crash> struct blk_mq_ops 0xffffffffc00a7160 struct blk_mq_ops { queue_rq = 0xffffffffc00a45b0 <virtio_queue_rq>, <--symbol translated from kernel map_queue = 0xffffffff813015c0 <blk_mq_map_queue>, ...snip... complete = 0xffffffffc00a4370 <virtblk_request_done>, init_request = 0xffffffffc00a4260 <virtblk_init_request>, ...snip... } crash> px ((struct request *)0xffff880fdb246000)->q->mq_ops $1 = (struct blk_mq_ops *) 0xffffffffc00a7160 <virtio_mq_ops> crash> struct blk_mq_ops 0xffffffffc00a7160 struct blk_mq_ops { queue_rq = 0xffffffffc00a45b0 <floppy_module_init+1151>, <--symbol translated from module map_queue = 0xffffffff813015c0 <blk_mq_map_queue>, ...snip... complete = 0xffffffffc00a4370 <floppy_module_init+575>, init_request = 0xffffffffc00a4260 <floppy_module_init+303>, ...snip... } with patch: crash> mod -S crash> struct blk_mq_ops 0xffffffffc00a7160 struct blk_mq_ops { queue_rq = 0xffffffffc00a45b0 <floppy_module_init+1151>, <--symbol translated from module map_queue = 0xffffffff813015c0 <blk_mq_map_queue>, ...snip... complete = 0xffffffffc00a4370 <floppy_module_init+575>, init_request = 0xffffffffc00a4260 <floppy_module_init+303>, ..snip... } crash> px ((struct request *)0xffff880fdb246000)->q->mq_ops $1 = (struct blk_mq_ops *) 0xffffffffc00a7160 <virtio_mq_ops> crash> struct blk_mq_ops 0xffffffffc00a7160 struct blk_mq_ops { queue_rq = 0xffffffffc00a45b0 <floppy_module_init+1151>, <--symbol translated from module map_queue = 0xffffffff813015c0 <blk_mq_map_queue>, ...snip... complete = 0xffffffffc00a4370 <floppy_module_init+575>, init_request = 0xffffffffc00a4260 <floppy_module_init+303>, ...snip... } The root cause for the changing of symbol translation is, after "mod -S", the kernel modules files "*.ko.debug" will be loaded. However the compile unit symtable of the kernel modules may not get expanded. As a result, the symtable of kernel modules, or obj_file->compunit_symtabs is nullptr, which don't take any effect for gdb symbol translation, it is unexpected. A c expression evaluation will trigger such an expansion. This patch will make sure symtable always get expanded before gdb symbol translation. Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; --- gdb-10.2.patch | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/gdb-10.2.patch b/gdb-10.2.patch index d81030d..31135ca 100644 --- a/gdb-10.2.patch +++ b/gdb-10.2.patch @@ -3187,3 +3187,20 @@ exit 0 result = stringtab + symbol_entry->_n._n_n._n_offset; } else +--- gdb-10.2/gdb/symtab.c.orig ++++ gdb-10.2/gdb/symtab.c +@@ -2931,6 +2931,14 @@ find_pc_sect_compunit_symtab (CORE_ADDR pc, struct obj_section *section) + + for (objfile *obj_file : current_program_space->objfiles ()) + { ++#ifdef CRASH_MERGE ++ std::string objfile_name = objfile_filename(obj_file); ++ ++ if (objfile_name.find(".ko") != std::string::npos) { ++ if (obj_file->sf && obj_file->compunit_symtabs == nullptr) ++ obj_file->sf->qf->expand_all_symtabs(obj_file); ++ } ++#endif + for (compunit_symtab *cust : obj_file->compunits ()) + { + const struct block *b; \ No newline at end of file -- 2.40.1