From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80083C433ED for ; Wed, 7 Apr 2021 13:43:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EB7B61165 for ; Wed, 7 Apr 2021 13:43:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347500AbhDGNnX (ORCPT ); Wed, 7 Apr 2021 09:43:23 -0400 Received: from mx2.suse.de ([195.135.220.15]:57186 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245734AbhDGNnV (ORCPT ); Wed, 7 Apr 2021 09:43:21 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1617802991; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PTt2INgvl8GKTENrHC2C616TI8/OOmgd1MLV/x97y8g=; b=uy9k/YmtbPYUcRj8rwAiP9UdmKSdV0NvutC7siS97WestyjG3SzfHzCPJmyeFuzP/D9n/i B/3AsuYRLIYCoHqcYujCcgoZfPQ7/1igRnjNjDwrrQ5F50Mu0nvm4Y80IG4tN2Dr1GPbp4 VHUcNOUdVRU2eReuBmW31uT4B6r2+Is= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 11976B132; Wed, 7 Apr 2021 13:43:11 +0000 (UTC) Date: Wed, 7 Apr 2021 15:42:38 +0200 From: Petr Mladek To: Stephen Boyd Cc: Andrew Morton , linux-kernel@vger.kernel.org, Jiri Olsa , Alexei Starovoitov , Jessica Yu , Evan Green , Hsin-Yi Wang , Steven Rostedt , Andy Shevchenko , Matthew Wilcox Subject: Re: [PATCH v3 03/12] dump_stack: Add vmlinux build ID to stack traces Message-ID: References: <20210331030520.3816265-1-swboyd@chromium.org> <20210331030520.3816265-4-swboyd@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210331030520.3816265-4-swboyd@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2021-03-30 20:05:11, Stephen Boyd wrote: > Add the running kernel's build ID[1] to the stacktrace information > header. This makes it simpler for developers to locate the vmlinux with > full debuginfo for a particular kernel stacktrace. Combined with > scripts/decode_stracktrace.sh, a developer can download the correct > vmlinux from a debuginfod[2] server and find the exact file and line > number for the functions plus offsets in a stacktrace. > > This is especially useful for pstore crash debugging where the kernel > crashes are recorded in the pstore logs and the recovery kernel is > different or the debuginfo doesn't exist on the device due to space > concerns (the data can be large and a security concern). The stacktrace > can be analyzed after the crash by using the build ID to find the > matching vmlinux and understand where in the function something went > wrong. > > Example stacktrace from lkdtm: > > WARNING: CPU: 4 PID: 3255 at drivers/misc/lkdtm/bugs.c:83 lkdtm_WARNING+0x28/0x30 [lkdtm] > Modules linked in: lkdtm rfcomm algif_hash algif_skcipher af_alg xt_cgroup uinput xt_MASQUERADE > CPU: 4 PID: 3255 Comm: bash Not tainted 5.11 #3 aa23f7a1231c229de205662d5a9e0d4c580f19a1 > Hardware name: Google Lazor (rev3+) with KB Backlight (DT) > pstate: 00400009 (nzcv daif +PAN -UAO -TCO BTYPE=--) > pc : lkdtm_WARNING+0x28/0x30 [lkdtm] > > The hex string aa23f7a1231c229de205662d5a9e0d4c580f19a1 is the build ID, > following the kernel version number. Put it all behind a config option, > STACKTRACE_BUILD_ID, so that kernel developers can remove this > information if they decide it is too much. > > diff --git a/lib/dump_stack.c b/lib/dump_stack.c > index f5a33b6f773f..07e0214c2d4d 100644 > --- a/lib/dump_stack.c > +++ b/lib/dump_stack.c > @@ -45,13 +52,14 @@ void __init dump_stack_set_arch_desc(const char *fmt, ...) > */ > void dump_stack_print_info(const char *log_lvl) > { > - printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s\n", > + printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s" BUILD_ID_STR "\n", > log_lvl, raw_smp_processor_id(), current->pid, current->comm, > kexec_crash_loaded() ? "Kdump: loaded " : "", > print_tainted(), > init_utsname()->release, > (int)strcspn(init_utsname()->version, " "), > - init_utsname()->version); > + init_utsname()->version, > + IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) ? vmlinux_build_id : ""); I get the following warning when CONFIG_STACKTRACE_BUILD_ID is not enabled: CC lib/dump_stack.o lib/dump_stack.c: In function ‘dump_stack_print_info’: lib/dump_stack.c:62:67: warning: pointer type mismatch in conditional expression IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) ? vmlinux_build_id : ""); ^ lib/dump_stack.c:55:9: warning: format ‘%s’ expects argument of type ‘char *’, but argument 11 has type ‘void *’ [-Wformat=] printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s" BUILD_ID_STR "\n", ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ lib/dump_stack.c:43:24: note: format string is defined here #define BUILD_ID_STR "%s" ~^ %p and this when the options is enabled: CC lib/dump_stack.o lib/dump_stack.c: In function ‘dump_stack_print_info’: lib/dump_stack.c:62:67: warning: pointer type mismatch in conditional expression IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) ? vmlinux_build_id : ""); I think that you need to use something like: #ifdef CONFIG_STACKTRACE_BUILD_ID #define BUILD_ID_FTM " %20phN" #define BUILD_ID_VAL vmlinux_build_id #else #define BUILD_ID_FTM "%s" #define BUILD_ID_VAL "" #endif printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s" BUILD_ID_FTM "\n", log_lvl, raw_smp_processor_id(), current->pid, current->comm, kexec_crash_loaded() ? "Kdump: loaded " : "", print_tainted(), init_utsname()->release, (int)strcspn(init_utsname()->version, " "), init_utsname()->version, BUILD_ID_VAL); Best Regards, Petr