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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=no 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 62D5AC11F64 for ; Tue, 29 Jun 2021 01:08:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 46520613EA for ; Tue, 29 Jun 2021 01:08:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232026AbhF2BKa (ORCPT ); Mon, 28 Jun 2021 21:10:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:37780 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232050AbhF2BK1 (ORCPT ); Mon, 28 Jun 2021 21:10:27 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 718F861360; Tue, 29 Jun 2021 01:08:00 +0000 (UTC) Date: Mon, 28 Jun 2021 21:07:58 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: jpoimboe@redhat.com, tglx@linutronix.de, linux-kernel@vger.kernel.org, joro@8bytes.org, boris.ostrovsky@oracle.com, jgross@suse.com, x86@kernel.org, mbenes@suse.com, dvyukov@google.com, elver@google.com Subject: Re: [PATCH v2 03/24] objtool: Handle __sanitize_cov*() tail calls Message-ID: <20210628210758.46a85e56@oasis.local.home> In-Reply-To: References: <20210624094059.886075998@infradead.org> <20210624095147.818783799@infradead.org> <20210625093824.03eb3cf7@oasis.local.home> X-Mailer: Claws Mail 3.17.3 (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 Sat, 26 Jun 2021 10:18:12 +0200 Peter Zijlstra wrote: > > > + if (mcount && !strcmp(insn->call_dest->name, "__fentry__")) { > > > + if (sibling) > > > + WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset); > > > > Have you ever triggered the above? > > No, that would be really daft. But since this function is to be called > for both regular and tail calls, I figured I'd at least pretend to > handle the case. OK. I thought this was like one of those weird laws that were made because you know that someone did something really stupid once. -- Steve