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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 29A03C433B4 for ; Tue, 13 Apr 2021 14:41:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0703D613AE for ; Tue, 13 Apr 2021 14:41:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343955AbhDMOll (ORCPT ); Tue, 13 Apr 2021 10:41:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:59738 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231917AbhDMOlc (ORCPT ); Tue, 13 Apr 2021 10:41:32 -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=1618324872; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XrS3LvtoF2dKQLQn8cBGzZViUcGsw61UP94N7EYr7+k=; b=ForxJz/oBkA0zRzL34o2nMOj9qljmCDmJdOXj5KRxijTFuU26d/zSTJyAqggC08fCacpQ+ 3GqRC7No8e46XAJCiPpSORCzGjYZ04QsvvL9p87reE5HjYOlPNLYXWQ9AQvCrxw/f4aH62 E0LUf9FsoBvDiJF3PaVhDnR/UHiDaQk= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id DB05BAF9E; Tue, 13 Apr 2021 14:41:11 +0000 (UTC) Date: Tue, 13 Apr 2021 16:41:11 +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 v4 04/13] dump_stack: Add vmlinux build ID to stack traces Message-ID: References: <20210410015300.3764485-1-swboyd@chromium.org> <20210410015300.3764485-5-swboyd@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210410015300.3764485-5-swboyd@chromium.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 2021-04-09 18:52:51, 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. > > Cc: Jiri Olsa > Cc: Alexei Starovoitov > Cc: Jessica Yu > Cc: Evan Green > Cc: Hsin-Yi Wang > Cc: Petr Mladek > Cc: Steven Rostedt > Cc: Andy Shevchenko > Cc: Matthew Wilcox > Link: https://fedoraproject.org/wiki/Releases/FeatureBuildId [1] > Link: https://sourceware.org/elfutils/Debuginfod.html [2] > Signed-off-by: Stephen Boyd Reviewed-by: Petr Mladek Tested-by: Petr Mladek One comment below. > --- > lib/Kconfig.debug | 11 +++++++++++ > lib/dump_stack.c | 13 +++++++++++-- > 2 files changed, 22 insertions(+), 2 deletions(-) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 2779c29d9981..5f883e50f406 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -35,6 +35,17 @@ config PRINTK_CALLER > no option to enable/disable at the kernel command line parameter or > sysfs interface. > > +config STACKTRACE_BUILD_ID > + bool "Show build ID information in stacktraces" > + depends on PRINTK > + help > + Selecting this option adds build ID information for symbols in > + stacktraces printed with the printk format '%p[SR]b'. > + > + This option is intended for distros where debuginfo is not easily > + accessible but can be downloaded given the build ID of the vmlinux or > + kernel module where the function is located. > + > config CONSOLE_LOGLEVEL_DEFAULT > int "Default console loglevel (1-15)" > range 1 15 > diff --git a/lib/dump_stack.c b/lib/dump_stack.c > index f5a33b6f773f..d685331b065f 100644 > --- a/lib/dump_stack.c > +++ b/lib/dump_stack.c > @@ -5,6 +5,7 @@ > */ > > #include > +#include > #include > #include > #include > @@ -36,6 +37,14 @@ void __init dump_stack_set_arch_desc(const char *fmt, ...) > va_end(args); > } > > +#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) > +#define BUILD_ID_FMT " %20phN" > +#define BUILD_ID_VAL vmlinux_build_id > +#else > +#define BUILD_ID_FMT "%s" > +#define BUILD_ID_VAL "" > +#endif 3rd patch always defines and initializes vmlinux_build_id. But it is used only when CONFIG_STACKTRACE_BUILD_ID is enabled. Is it intentional, please? It is not a big deal for vmlinux_build_id. But it is more questionable for the per-module id. I am going to open this question for 5th patch as well. Best Regards, Petr