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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E57AAC433F5 for ; Mon, 7 Mar 2022 13:25:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242168AbiCGNZz (ORCPT ); Mon, 7 Mar 2022 08:25:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57096 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234024AbiCGNZt (ORCPT ); Mon, 7 Mar 2022 08:25:49 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 550807EDB2 for ; Mon, 7 Mar 2022 05:24:53 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E3E8E611EF for ; Mon, 7 Mar 2022 13:24:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01CA0C340E9; Mon, 7 Mar 2022 13:24:51 +0000 (UTC) Date: Mon, 7 Mar 2022 08:24:50 -0500 From: Steven Rostedt To: Arend van Spriel Cc: Ingo Molnar , Linux Kernel Mailing List Subject: Re: ftrace bug Message-ID: <20220307082450.641ed866@gandalf.local.home> In-Reply-To: <9a86b2c9-1009-1683-442e-61c5a7dc8cf3@broadcom.com> References: <9a86b2c9-1009-1683-442e-61c5a7dc8cf3@broadcom.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 7 Mar 2022 12:26:45 +0100 Arend van Spriel wrote: > Hi Steven, > > I wanted to use FTRACE on an ARM platform and I hit the following > warning which results in ftrace bug. This happens upon loading a module. > Looking up the warning I suspect the branch target is too far off. The > module is quite large and therefor not loaded in the modules section. Is > there a way to exclude a module. In ftrace_module_init I see a check for > !mod->num_ftrace_callsites. Is there a way to avoid creating ftrace > callsites in a module? Are you sure it's the size. Just want to make sure that's the reason before going with different solutions. > > Regards, > Arend > > ------------[ cut here ]------------ > > WARNING: CPU: 2 PID: 1525 at arch/arm/kernel/insn.c:47 > __arm_gen_branch+0x70/0x78 > > CPU: 2 PID: 1525 Comm: insmod Tainted: P 4.19.183 #2 > > Hardware name: Generic DT based system > > [] (unwind_backtrace) from [] (show_stack+0x20/0x24) > > [] (show_stack) from [] (dump_stack+0x98/0xac) > > [] (dump_stack) from [] (__warn.part.0+0xcc/0xe8) > > [] (__warn.part.0) from [] > (warn_slowpath_null+0x54/0x74) > [] (warn_slowpath_null) from [] > (__arm_gen_branch+0x70/0x78) > [] (__arm_gen_branch) from [] > (ftrace_make_nop+0x64/0xec) > [] (ftrace_make_nop) from [] > (ftrace_process_locs+0x370/0x4b4) > > [] (ftrace_process_locs) from [] > (ftrace_module_init+0x38/0x3c) > > [] (ftrace_module_init) from [] > (load_module+0x18d0/0x2570) > [] (load_module) from [] > (sys_finit_module+0xe0/0xf8) > [] (sys_finit_module) from [] > (ret_fast_syscall+0x0/0x58) > Exception stack(0xd9b1bfa8 to 0xd9b1bff0) > > bfa0: 01170228 00000000 00000003 01170228 00000000 > beb7ceb3 > bfc0: 01170228 00000000 beb7cdc4 0000017b 00127010 00000000 00000000 > 00000000 > bfe0: beb7cc38 beb7cc28 0001a0dc 00012890 > > ---[ end trace f48808a851a4544a ]--- > > ------------[ cut here ]------------ > > WARNING: CPU: 2 PID: 1525 at kernel/trace/ftrace.c:2034 > ftrace_bug+0xfc/0x394 Three should be more content after the "cut here" that is very relevant (I hate that cut here, because I constantly need to tell people to show me more :-p I need to add a "ftrace bug cut here" line.) Could you show me the output right after that. -- Steve