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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 9717CC2B9F4 for ; Mon, 14 Jun 2021 18:09:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67EEF61075 for ; Mon, 14 Jun 2021 18:09:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235327AbhFNSLa (ORCPT ); Mon, 14 Jun 2021 14:11:30 -0400 Received: from mail-lj1-f179.google.com ([209.85.208.179]:45009 "EHLO mail-lj1-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235076AbhFNSLZ (ORCPT ); Mon, 14 Jun 2021 14:11:25 -0400 Received: by mail-lj1-f179.google.com with SMTP id d2so21306929ljj.11 for ; Mon, 14 Jun 2021 11:09:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=q/XB3mh4kqA0R3Mq5xG+IQPk2u072QCh1Aa1N8SVimI=; b=gNoMBqwIekxVN4ZTQA2lb+R20pn6emj+cRv+063F8GUQEh+FfehSxGO7Xfa3xVcU3y JNiHA/bieZlQ0jgmetM3eerqFAtGCVDc8wlzQ3M/mwfNPBGiWljejiloap0qpolaWRwM zyFvn32ZAv4OTwgqbKcKUFRfB2w3GYsBl0Ohsk903f3S2aJ8ihqajen4jcWO3pTZeTl4 m993LukbpLj1Ytei7kh8YWEerFqD3osLEVw7AF8D6GGia1vZCt8v8SzbH6rbqhKztVFJ 7UMl8nAKNXJuvuZDmibTlloR0VSSNTu7UEsrHWjpM6yBK+GGIpZf5DhbG3UVlYNesjYH dONw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=q/XB3mh4kqA0R3Mq5xG+IQPk2u072QCh1Aa1N8SVimI=; b=dUDfk5xBJ7briRH5G8YlrdDTIDl5jyceMeU3Wde1lMQp01Y97zGBMG/qU4LV9E8LP6 ObbXURSXK2jGVNJQGi8JOclKiGnzEp78bpzDYQ5m15/1x1dWDL999v1oDnuH7tg4+OfK M1RK/cIEWGUcB2WmSW8yCXHujh0+t37wuVN3a0Wkiv2xoILWopNH8rmKKABYdSqLvRhv oc0iqVX4nUwnbFMrxdcSuDIyAtAUgAjy9POEWoik2Fn8SXRJt5rjPCnOr97lTHr2Fini cIVqGMCzS8mj3//MBVllvvH40Hu5CPiR/AwJngMqfcCO5FTpEdj9yoISUf+H3T6dGdHk WSqQ== X-Gm-Message-State: AOAM530GdrDyApIynEd92difnYTAe/j1nR2RUW1OqSgl6wg5TFdbZ5UG viRRtUvKZqMgBuxnluEWD2hdu6Z5zXVR4PfwAKKqRA== X-Google-Smtp-Source: ABdhPJxKUKdlT+gTIv6tps2+MYGOK2jI4OTbw6VDol/+bdJyGm1oEKl+AJBHsonScc4F4P1rTyqrJq3Fw4OFoMUrzZ0= X-Received: by 2002:a05:651c:1111:: with SMTP id d17mr14547090ljo.116.1623694091627; Mon, 14 Jun 2021 11:08:11 -0700 (PDT) MIME-Version: 1.0 References: <20210612202505.GG68208@worktop.programming.kicks-ass.net> <202106140817.F584D2F@keescook> <20210614153545.GA68749@worktop.programming.kicks-ass.net> <202106140921.5E591BD@keescook> In-Reply-To: <202106140921.5E591BD@keescook> From: Nick Desaulniers Date: Mon, 14 Jun 2021 11:07:59 -0700 Message-ID: Subject: Re: [PATCH v9] pgo: add clang's Profile Guided Optimization infrastructure To: Kees Cook Cc: Peter Zijlstra , Marco Elver , Bill Wendling , Jonathan Corbet , Masahiro Yamada , Linux Doc Mailing List , LKML , Linux Kbuild mailing list , clang-built-linux , Andrew Morton , Nathan Chancellor , Sami Tolvanen , Fangrui Song , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Andrey Konovalov , Dmitry Vyukov , Johannes Berg , oberpar@linux.vnet.ibm.com, linux-toolchains@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 14, 2021 at 9:23 AM Kees Cook wrote: > > On Mon, Jun 14, 2021 at 05:35:45PM +0200, Peter Zijlstra wrote: > > On Mon, Jun 14, 2021 at 08:26:01AM -0700, Kees Cook wrote: > > > So, AFAICT, the original blocking issue ("PGO does not respect noinstr") > > > is not actually an issue (noinstr contains notrace, which IS respected > > > by PGO[2]), I think this is fine to move forward. > > > > It is *NOT*: https://godbolt.org/z/9c7xdvGd9 > > > > Look at how both compilers generate instrumentation in the no_instr() > > function. > > Well that's disappointing. I'll put this on hold until Clang can grow an > appropriate attribute (or similar work-around). Thanks for catching > that. Cross referencing since these two threads are related. https://lore.kernel.org/lkml/CAKwvOdmPTi93n2L0_yQkrzLdmpxzrOR7zggSzonyaw2PGshApw@mail.gmail.com/ -- Thanks, ~Nick Desaulniers