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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 D2A8EC43381 for ; Thu, 7 Mar 2019 17:48:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF17C20661 for ; Thu, 7 Mar 2019 17:48:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726783AbfCGRsJ (ORCPT ); Thu, 7 Mar 2019 12:48:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39834 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726729AbfCGRsG (ORCPT ); Thu, 7 Mar 2019 12:48:06 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D1E9B307D98B; Thu, 7 Mar 2019 17:48:05 +0000 (UTC) Received: from treble (ovpn-120-61.rdu2.redhat.com [10.10.120.61]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E24245D9C6; Thu, 7 Mar 2019 17:48:03 +0000 (UTC) Date: Thu, 7 Mar 2019 11:48:02 -0600 From: Josh Poimboeuf To: Peter Zijlstra Cc: torvalds@linux-foundation.org, tglx@linutronix.de, hpa@zytor.com, julien.thierry@arm.com, will.deacon@arm.com, luto@amacapital.net, mingo@kernel.org, catalin.marinas@arm.com, james.morse@arm.com, valentin.schneider@arm.com, brgerst@gmail.com, luto@kernel.org, bp@alien8.de, dvlasenk@redhat.com, linux-kernel@vger.kernel.org, dvyukov@google.com, rostedt@goodmis.org Subject: Re: [PATCH 00/20] objtool: UACCESS validation v3 Message-ID: <20190307174802.46fmpysxyo35hh43@treble> References: <20190307114511.870090179@infradead.org> <20190307120317.GD32477@hirez.programming.kicks-ass.net> <20190307125526.GB32534@hirez.programming.kicks-ass.net> <20190307131312.GC32534@hirez.programming.kicks-ass.net> <20190307164705.qbu4ytdfdmsighas@treble> <20190307174322.GK32477@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190307174322.GK32477@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Thu, 07 Mar 2019 17:48:06 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 07, 2019 at 06:43:22PM +0100, Peter Zijlstra wrote: > On Thu, Mar 07, 2019 at 10:47:05AM -0600, Josh Poimboeuf wrote: > > > This "fixes" it, and also seems to help -Os make much code: > > > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > > index 445348facea9..8de63db58fdd 100644 > > --- a/include/linux/compiler.h > > +++ b/include/linux/compiler.h > > @@ -67,7 +67,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, > > .line = __LINE__, \ > > }; \ > > ______r = !!(cond); \ > > - ______f.miss_hit[______r]++; \ > > + if (______r) ______f.miss_hit[1]++; else ______f.miss_hit[0]++; \ > > ______r; \ > > })) > > #endif /* CONFIG_PROFILE_ALL_BRANCHES */ > > Excellen; let me put the kids to bed and then I'll have a poke. Here's a proper patch. From: Josh Poimboeuf Subject: [PATCH] tracing: Improve "if" macro code generation With CONFIG_PROFILE_ALL_BRANCHES, the "if" macro converts the conditional to an array index. This can cause GCC to create horrible code. When there are nested ifs, the generated code uses register values to encode branching decisions. Make it easier for GCC to optimize by keeping the conditional as a conditional rather than converting it to an integer. This shrinks the generated code quite a bit, and also makes the code sane enough for objtool to understand. Reported-by: Peter Zijlstra Signed-off-by: Josh Poimboeuf --- include/linux/compiler.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 445348facea9..d58aa0db05f9 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -67,7 +67,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, .line = __LINE__, \ }; \ ______r = !!(cond); \ - ______f.miss_hit[______r]++; \ + ______r ? ______f.miss_hit[1]++ : ______f.miss_hit[0]++;\ ______r; \ })) #endif /* CONFIG_PROFILE_ALL_BRANCHES */ -- 2.17.2