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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 6787CC49EA2 for ; Tue, 22 Jun 2021 09:25:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4FD4D6044F for ; Tue, 22 Jun 2021 09:25:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229718AbhFVJ16 (ORCPT ); Tue, 22 Jun 2021 05:27:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:55128 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229490AbhFVJ15 (ORCPT ); Tue, 22 Jun 2021 05:27:57 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E7FB76128E; Tue, 22 Jun 2021 09:25:36 +0000 (UTC) Date: Tue, 22 Jun 2021 10:25:34 +0100 From: Catalin Marinas To: Nick Desaulniers Cc: Bill Wendling , Masahiro Yamada , Will Deacon , Mark Rutland , Ard Biesheuvel , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Peter Oberparleiter , Kees Cook , Peter Zijlstra , Bill Wendling , Sami Tolvanen , 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 Subject: Re: [PATCH 2/2] Kconfig: CC_HAS_NO_PROFILE_FN_ATTR, depend on for GCOV and PGO Message-ID: <20210622092533.GB3555@arm.com> References: <20210618233023.1360185-1-ndesaulniers@google.com> <20210618233023.1360185-3-ndesaulniers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-toolchains@vger.kernel.org On Mon, Jun 21, 2021 at 01:43:54PM -0700, Nick Desaulniers wrote: > On Mon, Jun 21, 2021 at 11:50 AM Bill Wendling wrote: > > 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? > > We need to be able to express via Kconfig "GCOV should not be enabled > for architectures that use noinstr when the toolchain does not support > __attribute__((no_profile_instrument_function))." > > Where "architectures that use noinstr" are currently arm64, s390, and > x86. So I guess we could do: > > + depends on !ARM64 || !S390 || !X86 || CC_HAS_NO_PROFILE_FN_ATTR I think you want: depends on !(ARM64 || S390 || X86) || CC_HAS_NO_PROFILE_FN_ATTR > (We could add a Kconfig for ARCH_WANTS_NO_INSTR, which might be more > informative than listed out architectures which might be non-obvious > to passers-by). That would probably look better. -- Catalin