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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 7ED00C43331 for ; Mon, 11 Nov 2019 08:47:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5140320818 for ; Mon, 11 Nov 2019 08:47:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="NHqcjmFT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727022AbfKKIrt (ORCPT ); Mon, 11 Nov 2019 03:47:49 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:49676 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726834AbfKKIrt (ORCPT ); Mon, 11 Nov 2019 03:47:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender: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=MWS4iDPKXqL9aeVZvrVY5JzKZIFEOsCQmC2rJZ7GvJc=; b=NHqcjmFTU72YEQ0NHLL0PvlhJ xmrjrC0pkf+ZWjbzkGG768hJ4OOzZ6NZsiYjbv4lGfcv42sKXJQJGhCxq75Ooo45OL01QBHliVmtS lsOGfX6aMkN5+3hNCGRQyGVfs+BLJ9hABBS6YFqYfqb8mKU5J53PYGHik7+oKseyZ2ZCH7YgP4YPo DIymuLRtZY9v4lKMXU6RMHFGuWQqN9+N9tBbCRlrz1jIarTi2Z5tPa/Uafai/Qjz21GnkxMFLdfUy K5kHQirn2/CRckRRDbA6FL7iV6UfNHkQ4jJdwNd+SG6kgYfcR+GhBbGkbPD/d5Y1/l18Y2lABz0IQ J+/iSQKIQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iU5MB-0003TQ-31; Mon, 11 Nov 2019 08:47:31 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id BAB7B305615; Mon, 11 Nov 2019 09:46:22 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EF09A2026E904; Mon, 11 Nov 2019 09:47:28 +0100 (CET) Date: Mon, 11 Nov 2019 09:47:28 +0100 From: Peter Zijlstra To: Josh Poimboeuf Cc: Steven Rostedt , linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , X86 ML , Nadav Amit , Andy Lutomirski , Dave Hansen , Song Liu , Masami Hiramatsu , Daniel Bristot de Oliveira , Alexei Starovoitov Subject: Re: [PATCH 00/10] ftrace: Add register_ftrace_direct() Message-ID: <20191111084728.GO4131@hirez.programming.kicks-ass.net> References: <20191108212834.594904349@goodmis.org> <20191108225100.ea3bhsbdf6oerj6g@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191108225100.ea3bhsbdf6oerj6g@treble> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 08, 2019 at 04:51:00PM -0600, Josh Poimboeuf wrote: > From: Josh Poimboeuf > Subject: [PATCH] ftrace/x86: Tell objtool to ignore nondeterministic ftrace stack layout > > Objtool complains about the new ftrace direct trampoline code: > > arch/x86/kernel/ftrace_64.o: warning: objtool: ftrace_regs_caller()+0x190: stack state mismatch: cfa1=7+16 cfa2=7+24 > > Typically, code has a deterministic stack layout, such that at a given > instruction address, the stack frame size is always the same. > > That's not the case for the new ftrace_regs_caller() code after it > adjusts the stack for the direct case. Just plead ignorance and assume > it's always the non-direct path. Note this creates a tiny window for > ORC to get confused. How is that not a problem for livepatch?