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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=unavailable 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 5D047C48BE5 for ; Mon, 21 Jun 2021 18:50:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47EA26115A for ; Mon, 21 Jun 2021 18:50:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232051AbhFUSwq (ORCPT ); Mon, 21 Jun 2021 14:52:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231176AbhFUSwp (ORCPT ); Mon, 21 Jun 2021 14:52:45 -0400 Received: from mail-ej1-x635.google.com (mail-ej1-x635.google.com [IPv6:2a00:1450:4864:20::635]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26DD5C061766 for ; Mon, 21 Jun 2021 11:50:30 -0700 (PDT) Received: by mail-ej1-x635.google.com with SMTP id hz1so7926325ejc.1 for ; Mon, 21 Jun 2021 11:50:30 -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=Su81jZ58rhgHEJ5xNq4SVnXH+2VzVF+NBRidhz73D1A=; b=fj1t9s647G21SEyRURvGSz0x9wtmxJ1tZ8/CUue9B6KUosAd6dSoUS60m96cQ+7eyu X+YDOnrvGr+bsP98c9Ca2GgLJ+1qdkFzpx1kZ4FjC9sSbmixe3cBrCy5j7iiA/8H78Ad qWzJYPTfCuC5c+PUdeApqrOKftevo3P8yumqzO/0U21y4euK6bSiWWRwcW6CnM20ymWn pngu/blLd7uK6hsKweTMDWkfmorb5VY9mnJDNM5UXnw3AqND/Bg88L0a/8/8CI1sTioU NjhPSc1Q63+MzLtw8gnM6sknXv0ioUMK76/Z/kE4nBov+x0xRP9UtXsfzDXe0v2gU9Kb N7iA== 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=Su81jZ58rhgHEJ5xNq4SVnXH+2VzVF+NBRidhz73D1A=; b=mYvIgNaObALrH8RAX0VAx9KPOu+RLYAdMBfpX5643ZSnGBjvQlqc8gko2Jdjr96xa2 7p0PFC2s8vDSfFDPLtY+zQtPBA7rjuxfTqGxlCzS7gqq5azrOe7XDNGQWVY+C7KEI9Xn /bEl6+GyhxI84LTq36q0FYs22BKpnj8t9UkCeocgNlPLEwZ3xVJ2kqY3ojGeU+SA6B3J 2b4SXQEyzTBp1hKK0P4HLAF2A39V6eeVqeeoXvvrXO4JRNiXrRCx323+pfTwFPLd8HK+ l2eb9TsySAZ7GwDfyIiDpdR+E7Gb0mWHuTAnjwkfBr8kF+YcedbOrjD4trInDwGaD2nK aTmA== X-Gm-Message-State: AOAM532bePiAZ7z/ItdGLLsm+hNn0YqABm7TlclDJaVkdNAWIlob2zyH QlC4YBBqsoL+Chd65gPu2SgT/oqpSIUrMxk/0IrM X-Google-Smtp-Source: ABdhPJxQyvHqkYkNkWIsH1dHYcEpHGTwWmWGnD1nZJKmm5KPLeVDAC8o6xVf4JO7qmGgkAFyzuoFRp5TgnFiSAjuZZk= X-Received: by 2002:a17:906:e108:: with SMTP id gj8mr25315960ejb.90.1624301428439; Mon, 21 Jun 2021 11:50:28 -0700 (PDT) MIME-Version: 1.0 References: <20210618233023.1360185-1-ndesaulniers@google.com> <20210618233023.1360185-3-ndesaulniers@google.com> In-Reply-To: From: Bill Wendling Date: Mon, 21 Jun 2021 11:50:17 -0700 Message-ID: Subject: Re: [PATCH 2/2] Kconfig: CC_HAS_NO_PROFILE_FN_ATTR, depend on for GCOV and PGO To: Nick Desaulniers Cc: Will Deacon , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Peter Oberparleiter , Kees Cook , Peter Zijlstra , Bill Wendling , Sami Tolvanen , Masahiro Yamada , Miguel Ojeda , Nathan Chancellor , Luc Van Oostenryck , Arnd Bergmann , Andrew Morton , Rasmus Villemoes , LKML , clang-built-linux , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Borislav Petkov , Martin Liska , Jonathan Corbet , Fangrui Song , Linux Doc Mailing List , Linux Kbuild mailing list , Dmitry Vyukov , Johannes Berg , linux-toolchains@vger.kernel.org, Marco Elver , Linux ARM , linux-s390 Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-toolchains@vger.kernel.org On Mon, Jun 21, 2021 at 11:22 AM Nick Desaulniers wrote: > > On Fri, Jun 18, 2021 at 11:23 PM Marco Elver wrote: > > > > On Sat, 19 Jun 2021 at 01:30, Nick Desaulniers wrote: > > > > > > We don't want compiler instrumentation to touch noinstr functions, which > > > are annotated with the no_profile function attribute. Add a Kconfig test > > > for this and make PGO and GCOV depend on it. > > > > > > Cc: Masahiro Yamada > > > Cc: Peter Oberparleiter > > > Link: https://lore.kernel.org/lkml/YMTn9yjuemKFLbws@hirez.programming.kicks-ass.net/ > > > Link: https://lore.kernel.org/lkml/YMcssV%2Fn5IBGv4f0@hirez.programming.kicks-ass.net/ > > > Suggested-by: Peter Zijlstra > > > Signed-off-by: Nick Desaulniers > > > --- > > > init/Kconfig | 3 +++ > > > kernel/gcov/Kconfig | 1 + > > > kernel/pgo/Kconfig | 3 ++- > > > 3 files changed, 6 insertions(+), 1 deletion(-) > > > > > > diff --git a/init/Kconfig b/init/Kconfig > > > index 1ea12c64e4c9..540f862b40c6 100644 > > > --- a/init/Kconfig > > > +++ b/init/Kconfig > > > @@ -83,6 +83,9 @@ config TOOLS_SUPPORT_RELR > > > config CC_HAS_ASM_INLINE > > > def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) > > > > > > +config CC_HAS_NO_PROFILE_FN_ATTR > > > + def_bool $(success,echo '__attribute__((no_profile)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) > > > + > > > config CONSTRUCTORS > > > bool > > > > > > diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig > > > index 58f87a3092f3..19facd4289cd 100644 > > > --- a/kernel/gcov/Kconfig > > > +++ b/kernel/gcov/Kconfig > > > @@ -5,6 +5,7 @@ config GCOV_KERNEL > > > bool "Enable gcov-based kernel profiling" > > > depends on DEBUG_FS > > > depends on !CC_IS_CLANG || CLANG_VERSION >= 110000 > > > + depends on !X86 || (X86 && CC_HAS_NO_PROFILE_FN_ATTR) > > > > [+Cc Mark] > > > > arm64 is also starting to rely on noinstr working properly. > > Sure, > Will, Catalin, other arm64 folks: > Any thoughts on requiring GCC 7.1+/Clang 13.0+ for GCOV support? That > way we can better guarantee that GCOV (and eventually, PGO) don't > touch noinstr functions? > > If that's ok, I'll add modify the above like: > > + depends on !ARM64 || (ARM64 && CC_HAS_NO_PROFILE_FN_ATTR) > Wouldn't "!ARM64 || CC_HAS_NO_PROFILE_FN_ATTR" be more succinct? > to the above hunk in v2. Oh, looks like arch/s390 also uses noinstr. > Same question applies then: > > + depends on !S390 || (S390 && CC_HAS_NO_PROFILE_FN_ATTR) > > Or, we could just do > > + depends on CC_HAS_NO_PROFILE_FN_ATTR > > Though that will penalize architectures not using noinstr, that still > would like to use GCOV with versions of GCC older than 7.1. Perhaps > there are no such such users, or they should consider upgrading their > tools to we can stick with the simpler Kconfig? Thoughts? > > > > > This should probably be a 'select ARCH_HAS_GCOV_PROFILE_ALL if > > CC_HAS_NO_PROFILE_FN_ATTR' in the relevant arch/../Kconfig. > > > > Alternatively, using: > > https://lkml.kernel.org/r/YMcssV/n5IBGv4f0@hirez.programming.kicks-ass.net > > > > But I'd probably not overcomplicate things at this point and just use > > ARCH_HAS_GCOV_PROFILE_ALL, because GCOV seems to be a) rarely used, > > and b) if someone decides to selectively instrument stuff like entry > > code, we can just say it's user error. > > > > > > > select CONSTRUCTORS > > > default n > > > help > > > diff --git a/kernel/pgo/Kconfig b/kernel/pgo/Kconfig > > > index d2053df1111c..26f75ac4c6c1 100644 > > > --- a/kernel/pgo/Kconfig > > > +++ b/kernel/pgo/Kconfig > > > @@ -8,7 +8,8 @@ config PGO_CLANG > > > bool "Enable clang's PGO-based kernel profiling" > > > depends on DEBUG_FS > > > depends on ARCH_SUPPORTS_PGO_CLANG > > > - depends on CC_IS_CLANG && CLANG_VERSION >= 120000 > > > + depends on CC_IS_CLANG > > > + depends on CC_HAS_NO_PROFILE_FN_ATTR > > > help > > > This option enables clang's PGO (Profile Guided Optimization) based > > > code profiling to better optimize the kernel. > > > -- > > > 2.32.0.288.g62a8d224e6-goog > > > > > > > -- > Thanks, > ~Nick Desaulniers