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=-11.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 93BB2C433E0 for ; Fri, 29 May 2020 18:37:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7340A206A1 for ; Fri, 29 May 2020 18:37:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ZMny2DF2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727803AbgE2ShL (ORCPT ); Fri, 29 May 2020 14:37:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51060 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725901AbgE2ShJ (ORCPT ); Fri, 29 May 2020 14:37:09 -0400 Received: from mail-oi1-x243.google.com (mail-oi1-x243.google.com [IPv6:2607:f8b0:4864:20::243]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90FCBC03E969 for ; Fri, 29 May 2020 11:37:09 -0700 (PDT) Received: by mail-oi1-x243.google.com with SMTP id w4so3497686oia.1 for ; Fri, 29 May 2020 11:37:09 -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=qgm4s52vNNhERtvdEgwZpi9/hHsa34APX0EThyas0Hg=; b=ZMny2DF2NBmtRcYhSX7CHk0Bywmqfi5HP0rftPQ/8cwBsP0rFw+v7v3VkO9QDeOfj5 42roL7TvZp/jwwCX4J223Zty0smJJFgXrlm8o1QuqhGa8LxDqSZ2l8a3NGQZZYaKihUG Ldtip+qJpWonx/883hfGjm9fo+e5EjIuVKEWUvB88C+goEDub4gjId/y0AvJ/uIspKxl evnyp4MEPdyXjAGhB/NudeAWfu4Z0sKUYWPeDe1VO1OJQ1EwbXyJLOVvm6JR+/7md7kd gVqqsvPAd+NFIFKIQePCK6y3/nTl9lELpooyCqoOSCKOCTsNDutLfIwqClLsQ8+tTZR0 d8SQ== 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=qgm4s52vNNhERtvdEgwZpi9/hHsa34APX0EThyas0Hg=; b=ZPcJN5DFefbX0wkAokPPcD7e8xFsRrv/RT4riH74hxt6ud/qX2QLFGahSmTkodNLOa vY55EOT26lSCANqpRDvdk/JbAUimfQb6ZwDvRmD4YcJCNjaZVKraeTZkHp5B7rLk7o0m qM7D+j2ZJu8sZ1DyPFneACeIsnHQYgFbD0EghKlPcnXKgGDEGVWWr4ndXcrbpdi31hdy 56j6WbxmAeqy9Zw4TjPwX2cudK710E7BvdjdJA61nmZxxtKbjEKkJvQQoXtiLT+HOtX5 FU+sWi4Xji8tvYhy0480TrWtjHuXFt25SjyX9+cPlbvkwpCI37JaT3h0nXqA3wBAI33B QxeQ== X-Gm-Message-State: AOAM530g0yrFiD8PHq1WfMe3zdATnd1b7kEX3VS4A8nnkqe5TAQuiYpH Qn5PiBpWygBnNuPly5HKIfF25v0ybStpmop/ouBU7w== X-Google-Smtp-Source: ABdhPJwSPmcBjhdoyTnfvSzZj1WZkdcgTPSIEsVfZagyp/eQHSg278s5ZbhWp/APU3cSGebjvLPWOcA3zOjfaAo+Ycs= X-Received: by 2002:aca:d0d:: with SMTP id 13mr6951426oin.172.1590777428688; Fri, 29 May 2020 11:37:08 -0700 (PDT) MIME-Version: 1.0 References: <20200521142047.169334-1-elver@google.com> <20200521142047.169334-6-elver@google.com> <20200529170755.GN706495@hirez.programming.kicks-ass.net> In-Reply-To: <20200529170755.GN706495@hirez.programming.kicks-ass.net> From: Marco Elver Date: Fri, 29 May 2020 20:36:56 +0200 Message-ID: Subject: Re: [PATCH -tip v3 05/11] kcsan: Remove 'noinline' from __no_kcsan_or_inline To: Peter Zijlstra Cc: "Paul E. McKenney" , Dmitry Vyukov , Alexander Potapenko , Andrey Konovalov , kasan-dev , LKML , Thomas Gleixner , Ingo Molnar , Will Deacon , clang-built-linux , Borislav Petkov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 29 May 2020 at 19:08, Peter Zijlstra wrote: [...] > > Doesn't this mean we can do the below? If nobody complains about the lack of __no_kcsan_or_inline, let's do it. See comments below. > --- > Documentation/dev-tools/kcsan.rst | 6 ------ > arch/x86/include/asm/bitops.h | 6 +----- > include/linux/compiler_types.h | 14 ++++---------- > kernel/kcsan/kcsan-test.c | 4 ++-- > 4 files changed, 7 insertions(+), 23 deletions(-) > > diff --git a/Documentation/dev-tools/kcsan.rst b/Documentation/dev-tools/kcsan.rst > index ce4bbd918648..b38379f06194 100644 > --- a/Documentation/dev-tools/kcsan.rst > +++ b/Documentation/dev-tools/kcsan.rst > @@ -114,12 +114,6 @@ functions, compilation units, or entire subsystems. For static blacklisting, > To dynamically limit for which functions to generate reports, see the > `DebugFS interface`_ blacklist/whitelist feature. > > - For ``__always_inline`` functions, replace ``__always_inline`` with > - ``__no_kcsan_or_inline`` (which implies ``__always_inline``):: > - > - static __no_kcsan_or_inline void foo(void) { > - ... > - > * To disable data race detection for a particular compilation unit, add to the > ``Makefile``:: I suppose, if we say that __no_kcsan_or_inline should just disappear because '__no_kcsan inline' is now good enough, we can delete it. I think functions that absolutely must be __always_inline would break with __no_kcsan_or_inline under KCSAN anyway. So, let's simplify. > diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h > index 35460fef39b8..0367efdc5b7a 100644 > --- a/arch/x86/include/asm/bitops.h > +++ b/arch/x86/include/asm/bitops.h > @@ -201,12 +201,8 @@ arch_test_and_change_bit(long nr, volatile unsigned long *addr) > return GEN_BINARY_RMWcc(LOCK_PREFIX __ASM_SIZE(btc), *addr, c, "Ir", nr); > } > > -static __no_kcsan_or_inline bool constant_test_bit(long nr, const volatile unsigned long *addr) > +static __always_inline bool constant_test_bit(long nr, const volatile unsigned long *addr) > { > - /* > - * Because this is a plain access, we need to disable KCSAN here to > - * avoid double instrumentation via instrumented bitops. > - */ Yes, we should have reverted this eventually. > return ((1UL << (nr & (BITS_PER_LONG-1))) & > (addr[nr >> _BITOPS_LONG_SHIFT])) != 0; > } > diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h > index 4e4982d6f3b0..6a2c0f857ac3 100644 > --- a/include/linux/compiler_types.h > +++ b/include/linux/compiler_types.h > @@ -118,10 +118,6 @@ struct ftrace_likely_data { > #define notrace __attribute__((__no_instrument_function__)) > #endif > > -/* Section for code which can't be instrumented at all */ > -#define noinstr \ > - noinline notrace __attribute((__section__(".noinstr.text"))) > - > /* > * it doesn't make sense on ARM (currently the only user of __naked) > * to trace naked functions because then mcount is called without > @@ -192,17 +188,15 @@ struct ftrace_likely_data { > #endif > > #define __no_kcsan __no_sanitize_thread > -#ifdef __SANITIZE_THREAD__ > -# define __no_kcsan_or_inline __no_kcsan notrace __maybe_unused > -# define __no_sanitize_or_inline __no_kcsan_or_inline I think we just want to keep __no_sanitize_or_inline, for READ_ONCE_NOCHECK. Having READ_ONCE_NOCHECK do KCSAN-checking seems wrong, and I don't know what might break. > -#else > -# define __no_kcsan_or_inline __always_inline > -#endif > > #ifndef __no_sanitize_or_inline > #define __no_sanitize_or_inline __always_inline > #endif > > +/* Section for code which can't be instrumented at all */ > +#define noinstr \ > + noinline notrace __attribute((__section__(".noinstr.text"))) __no_kcsan > + Will this eventually need __no_sanitize_address? > #endif /* __KERNEL__ */ > > #endif /* __ASSEMBLY__ */ > diff --git a/kernel/kcsan/kcsan-test.c b/kernel/kcsan/kcsan-test.c > index a8c11506dd2a..374263ddffe2 100644 > --- a/kernel/kcsan/kcsan-test.c > +++ b/kernel/kcsan/kcsan-test.c > @@ -43,7 +43,7 @@ static struct { > }; > > /* Setup test checking loop. */ > -static __no_kcsan_or_inline void > +static __no_kcsan inline void > begin_test_checks(void (*func1)(void), void (*func2)(void)) > { > kcsan_disable_current(); > @@ -60,7 +60,7 @@ begin_test_checks(void (*func1)(void), void (*func2)(void)) > } > > /* End test checking loop. */ > -static __no_kcsan_or_inline bool > +static __no_kcsan inline bool > end_test_checks(bool stop) > { > if (!stop && time_before(jiffies, end_time)) { Acked -- if you send a patch, do split the test-related change, so that Paul can apply it to the test which is currently only in -rcu. Thanks, -- Marco