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 DCC30C433FE for ; Wed, 9 Mar 2022 01:18:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230478AbiCIBTM (ORCPT ); Tue, 8 Mar 2022 20:19:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231545AbiCIBS1 (ORCPT ); Tue, 8 Mar 2022 20:18:27 -0500 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D92CF12E17D for ; Tue, 8 Mar 2022 17:08:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=NUm+eI6I7vXUsufLZj3Ybgr0AUlu0fM8Z9nEWhEtbG4=; b=J2BvjLjQK+kQUeBycrbQzD2N01 A0P8NwaE/jEcHIfpsidYyEwAeE8FMX11IhtmE+1KgjrRosjKJVQn5rpovGCyA4IvS4GS3GepULNK/ UB5BNggxnhRB6wzPMjwJKYlql7mW/PYlYh99BLVYWlBM7CFK4wtG88BpBFGvNQS7a8cFGcGSXA+rt wJFoXSaWRY63BKrmoxjDnAV3Ajz9PW0Yg4L8ncfnuhEqQLZFYXyHB6AKHNhNLCFaF8mLsjsTk9Ss2 k8GRAIVPNCqoXbRgNaodtHvNAjBaq9pjIaTkFhEVLPEASrihE96DwNWHuD2ymD9PlD9U8UaJAZwy3 sUZQyoMg==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:57732) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1nRkoN-0001C5-Et; Wed, 09 Mar 2022 01:08:19 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1nRkoL-0007Or-U2; Wed, 09 Mar 2022 01:08:17 +0000 Date: Wed, 9 Mar 2022 01:08:17 +0000 From: "Russell King (Oracle)" To: Ard Biesheuvel Cc: Corentin Labbe , Linus Walleij , Arnd Bergmann , Linux ARM , Linux Kernel Mailing List Subject: Re: boot flooded with unwind: Index not found Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: Russell King (Oracle) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 09, 2022 at 12:01:26AM +0000, Russell King (Oracle) wrote: > To reinterate what I've just put on IRC - we have not got to the bottom > of this problem yet - it still very much exists. > > There seems to be something of a fundamental issue with the unwinder, > it now appears to be going wrong and failing to unwind beyond a > couple of functions, and the address it's coming out with appears to > be incorrect. I've only just discovered this because I created my very > own bug, and yet again, the timing sucks with the proximity of the > merge window. > > I'm getting: > > [ 13.198803] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [ 13.198820] [] (show_stack) from [] (0xc2be78d4) > > for the WARN_ON() stacktrace, and that address that apparently called > show_stack() is most definitely rubbish and incorrect. This makes any > WARN_ON() condition undebuggable. > > This is with both 9183/1 and 9184/1 applied on top of pulling your > "arm-ftrace-for-rmk" tag and also with just the "arm-vmap-stacks-v6" > tag. This seems to point at one of these patches breaking the > unwinder: > > a1c510d0adc6 ARM: implement support for vmap'ed stacks > 532319b9c418 ARM: unwind: disregard unwind info before stack frame is set up The above commit appears to be what's breaking the unwinder. Without this I get sane stacktraces. With it, the unwinder spits out stupid function addresses. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!