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 39F33C433EF for ; Mon, 2 May 2022 17:59:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244402AbiEBSDC (ORCPT ); Mon, 2 May 2022 14:03:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57344 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231134AbiEBSC5 (ORCPT ); Mon, 2 May 2022 14:02:57 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E9DDCDE6 for ; Mon, 2 May 2022 10:59:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651514367; h=from:from:reply-to:subject:subject: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=52m/RMJe9vQWruEJqEyw+MPMfE0VFlYZPqLbzzwAEvg=; b=Eu2R+zsIpl14ZUFfEXpqyy9yd5k+ilfe6Ss9G9roymQ1WLGlcwjNxQZ45DR6AGUduL/b2j /E9Fm6QmP1hH2pf47GvkSXG4UFKHOS1PBmg+iQgEF8S5X9NCIn9liWRDOY5vEVSz15Dtcm TCg/ITTx1zJ3Ulga8jct9FrMLDb4OuA= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-497-ocWIqvWZNZ2snWcMPjj7rg-1; Mon, 02 May 2022 13:59:26 -0400 X-MC-Unique: ocWIqvWZNZ2snWcMPjj7rg-1 Received: by mail-qk1-f198.google.com with SMTP id c84-20020a379a57000000b0069fcf83c373so3463942qke.20 for ; Mon, 02 May 2022 10:59:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=52m/RMJe9vQWruEJqEyw+MPMfE0VFlYZPqLbzzwAEvg=; b=U9OWdp6S264AP1fFoqXuSt81Tk6uy6dugxvnJ9xiU0hGnj54I4nwLxQN1d5nnQJIJv P1nhGFWfpullmD3bXSl3ilgigKYN3oo8ytI98MvaKl3gT7aq9RsoUwDipZHEOwNNaZoM xIH1aXNdDbdrUASLHWeYm1V+mrICCJxZinpAMk6oub5p1cOuU+jPf6Hjv0g8at0CWIet lsEbTbXWeknkCyE0OC0fYrJcIP8DEjgI2/RB1pkIypLYnYOvk87G+K4yXVLeRVKOT7ib bOHsVL+ut2jUrRiuBfsOnDaZGU9knDzyMkA5hcoJ+YjTJoQRcHVBn3tLvTUZhsUTCVbQ qhtw== X-Gm-Message-State: AOAM532axS0ocRvOlFJDnoetRcMWU+XIaruQ4dYqcNN/MZBXnr4oM5Gu 8uXiLaac5jOQgGOFH8s+TbhvOlFpTI6JwF3vAX2p10BhHsobpNLGDAtcE2/pQf5AhtpherULXvo jYwwtNDmTMF9Vi90ow+ckqyJU X-Received: by 2002:a05:6214:445:b0:456:4d9e:db71 with SMTP id cc5-20020a056214044500b004564d9edb71mr10428886qvb.93.1651514365466; Mon, 02 May 2022 10:59:25 -0700 (PDT) X-Google-Smtp-Source: ABdhPJx7rkjG3ZO067xLuanXZqyfDsInyWmL9p+DIIRyNJDZ72hWMgjJoOKZRjJwM12mgIEO+ieSOw== X-Received: by 2002:a05:6214:445:b0:456:4d9e:db71 with SMTP id cc5-20020a056214044500b004564d9edb71mr10428870qvb.93.1651514365173; Mon, 02 May 2022 10:59:25 -0700 (PDT) Received: from treble ([2600:1700:6e32:6c00::a]) by smtp.gmail.com with ESMTPSA id g19-20020ac842d3000000b002f1f934bedfsm4850258qtm.3.2022.05.02.10.59.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 May 2022 10:59:24 -0700 (PDT) Date: Mon, 2 May 2022 10:59:21 -0700 From: Josh Poimboeuf To: Peter Zijlstra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Masami Hiramatsu Subject: Re: [PATCH] objtool: Fix STACK_FRAME_NON_STANDARD reloc type Message-ID: <20220502175921.oruktb6dleabvdyx@treble> References: <20220429092024.GT2731@worktop.programming.kicks-ass.net> <20220429225636.6qm2orq4uwnl33ii@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 30, 2022 at 01:44:00PM +0200, Peter Zijlstra wrote: > > > I also don't see any kprobe/optprobe hooks in unwind.h, so what happens > > > if we hit an optprobe? > > > > Same as for any other generated code, the unwinder will try to fall back > > to frame pointers, and if that doesn't work, the unwind stops. > > > > That commit didn't change anything since it was already not being > > directly executed anyway, but rather used to generate code on the fly. > > > > And before that commit it was being ignored by ORC anyway, thanks to > > STACK_FRAME_NON_STANDARD. Which can now be removed since this code is > > now data and objtool will no longer try to understand it. > > Right; but I suppose I'm wondering if we should fix this. It seems a > rather sub-optimal state of affairs. Masami recently fixed some kprobes ORC issues but I don't know if this one was fixed. As to the whether it's worth fixing, I dunno. There are trade offs. Depends on how common the stack trace is -- I'm guessing not very, since I've never seen a bug report -- and how important it is to get to full ORC coverage. If our goal is full coverage, we'd need a way for generated code to add/remove ORC entries. -- Josh