Date: Tue, 14 Nov 2023 16:32:07 +0800 From: Tao Liu <ltao(a)redhat.com&gt; Subject: [Crash-utility] [PATCH v2] symbols: skip load .init.* sections if module was successfully initialized To: devel(a)lists.crash-utility.osci.io Cc: Tao Liu <ltao(a)redhat.com&gt; Message-ID: <20231114083206.11202-1-ltao(a)redhat.com&gt; Content-Type: text/plain; charset="US-ASCII"; x-default=true There might be address overlap of one module's .init.text symbols and another module's .text symbols. As a result, gdb fails to translate the address to symbol name correctly: crash> sym -m virtio_blk | grep MODULE ffffffffc00a4000 MODULE START: virtio_blk ffffffffc00a86ec MODULE END: virtio_blk crash> gdb info address floppy_module_init Symbol "floppy_module_init" is a function at address 0xffffffffc00a4131. Since the .init.* sections of a module had been freed by kernel if the module was initialized successfully, there is no need to load the .init.* sections data from "*.ko.debug" in gdb to create such an overlap. lm->mod_init_module_ptr is used as a flag of whether module is freed.

crash> mod -S crash> struct blk_mq_ops 0xffffffffc00a7160 struct blk_mq_ops { queue_rq = 0xffffffffc00a45b0 <floppy_module_init+1151>, <-- symbol translated from module floppy map_queue = 0xffffffff813015c0 <blk_mq_map_queue>, ...snip... complete = 0xffffffffc00a4370 <floppy_module_init+575>, init_request = 0xffffffffc00a4260 <floppy_module_init+303>, ...snip... } With the patch: crash> mod -S crash> struct blk_mq_ops 0xffffffffc00a7160 struct blk_mq_ops { queue_rq = 0xffffffffc00a45b0 <virtio_queue_rq>, <-- symbol translated from module virtio_blk map_queue = 0xffffffff813015c0 <blk_mq_map_queue>, ...snip... complete = 0xffffffffc00a4370 <virtblk_request_done>, init_request = 0xffffffffc00a4260 <virtblk_init_request>, ...snip... } Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; --- v1: [PATCH 1/2] symbols: expand kernel modules symtable before symbols translation [PATCH 2/2] symbols: fix the error belonging of the kernel modules symbols v2 -> v1: Used different solution, re-drafted patch based on Kazu's comments, so v1 can be discarded. --- symbols.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/symbols.c b/symbols.c index 8e8b4c3..dae5b04 100644 --- a/symbols.c +++ b/symbols.c @@ -13283,7 +13283,7 @@ add_symbol_file_kallsyms(struct load_module *lm, struct gnu_request *req) shift_string_right(req->buf, strlen(buf)); BCOPY(buf, req->buf, strlen(buf)); retval = TRUE; - } else { + } else if (lm->mod_init_module_ptr || !STRNEQ(section_name, ".init.")) { sprintf(buf, " -s %s 0x%lx", section_name, section_vaddr); while ((len + strlen(buf)) >= buflen) { RESIZEBUF(req->buf, buflen, buflen * 2); -- 2.40.1