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=-3.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 5298EC433E0 for ; Fri, 26 Jun 2020 11:30:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C89820663 for ; Fri, 26 Jun 2020 11:30:25 +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="EGCO0/B1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728594AbgFZLaU (ORCPT ); Fri, 26 Jun 2020 07:30:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728467AbgFZLaU (ORCPT ); Fri, 26 Jun 2020 07:30:20 -0400 Received: from casper.infradead.org (unknown [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F01FBC08C5C1; Fri, 26 Jun 2020 04:30:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=0MTNUdpvCFV2C1ooAXJ6Vvth7dm0A8sUroqcq/z5uD0=; b=EGCO0/B1XB2kdspcyQ89ZQhoyg Ax/IQM8mmxqV7jkKXl/MWFP7prA5jfkO8HqSZPvnttIDjSFg1w/tKaO3j0k8KL6L+qlIY0Zn2j/hq W4+C8nlebWIF5ebBhJfftDfljzTAMl06M2aRxkineGdmpGu/LekSm6EbJ+h10mKkHi/ilcNQ8Z18F M2MJ7rPoVqwffWXd5EUII1zbwujF3rIpU9+e9qp3xDauW8aC4GU0RX4H1LjU/WFGQSrKETn9e32/P Ej5EZj5V0SHGNf+0tpEq14xmxvUc265pk15KyovRcTjXtIcLHzhrye5Vn/4QwrJSU3Wa82Pvq0XOG Bstzz1kg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jomY2-0007sF-0f; Fri, 26 Jun 2020 11:29:34 +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 61A90301DFC; Fri, 26 Jun 2020 13:29:31 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4048629C95961; Fri, 26 Jun 2020 13:29:31 +0200 (CEST) Date: Fri, 26 Jun 2020 13:29:31 +0200 From: Peter Zijlstra To: Sami Tolvanen Cc: Steven Rostedt , Masahiro Yamada , Will Deacon , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org, Josh Poimboeuf , mhelsley@vmware.com Subject: Re: [RFC][PATCH] objtool,x86_64: Replace recordmcount with objtool Message-ID: <20200626112931.GF4817@hirez.programming.kicks-ass.net> References: <20200624203200.78870-1-samitolvanen@google.com> <20200624203200.78870-5-samitolvanen@google.com> <20200624212737.GV4817@hirez.programming.kicks-ass.net> <20200624214530.GA120457@google.com> <20200625074530.GW4817@hirez.programming.kicks-ass.net> <20200625161503.GB173089@google.com> <20200625200235.GQ4781@hirez.programming.kicks-ass.net> <20200625224042.GA169781@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200625224042.GA169781@google.com> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Jun 25, 2020 at 03:40:42PM -0700, Sami Tolvanen wrote: > > Not boot tested, but it generates the required sections and they look > > more or less as expected, ymmv. > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > > index a291823f3f26..189575c12434 100644 > > --- a/arch/x86/Kconfig > > +++ b/arch/x86/Kconfig > > @@ -174,7 +174,6 @@ config X86 > > select HAVE_EXIT_THREAD > > select HAVE_FAST_GUP > > select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE > > - select HAVE_FTRACE_MCOUNT_RECORD > > select HAVE_FUNCTION_GRAPH_TRACER > > select HAVE_FUNCTION_TRACER > > select HAVE_GCC_PLUGINS > > This breaks DYNAMIC_FTRACE according to kernel/trace/ftrace.c: > > #ifndef CONFIG_FTRACE_MCOUNT_RECORD > # error Dynamic ftrace depends on MCOUNT_RECORD > #endif > > And the build errors after that seem to confirm this. It looks like we might > need another flag to skip recordmcount. Hurm, Steve, how you want to do that? > Anyway, since objtool is run before recordmcount, I just left this unchanged > for testing and ignored the recordmcount warnings about __mcount_loc already > existing. Something is a bit off still though, I see this at boot: > > ------------[ ftrace bug ]------------ > ftrace failed to modify > [] __tracepoint_iter_initcall_level+0x0/0x40 > actual: 0f:1f:44:00:00 > Initializing ftrace call sites > ftrace record flags: 0 > (0) > expected tramp: ffffffff81056500 > ------------[ cut here ]------------ > > Otherwise, this looks pretty good. Ha! it is trying to convert the "CALL __fentry__" into a NOP and not finding the CALL -- because objtool already made it a NOP... Weird, I thought recordmcount would also write NOPs, it certainly has code for that. I suppose we can use CC_USING_NOP_MCOUNT to avoid those, but I'd rather Steve explain this before I wreck things further.