Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220329124017.737571-1-glider@google.com> <20220329124017.737571-13-glider@google.com>
In-Reply-To: <20220329124017.737571-13-glider@google.com>
From:   Marco Elver <elver@google.com>
Date:   Wed, 30 Mar 2022 08:00:00 +0200
Message-ID: <CANpmjNP7BG5OwV53UUZ8HZ0OwAk-Ownn44jiF2TwhAD-mu2YbQ@mail.gmail.com>
Subject: Re: [PATCH v2 12/48] kcsan: clang: retire CONFIG_KCSAN_KCOV_BROKEN
To:     Alexander Potapenko <glider@google.com>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrey Konovalov <andreyknvl@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
        Christoph Hellwig <hch@lst.de>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Eric Dumazet <edumazet@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Ilya Leoshkevich <iii@linux.ibm.com>,
        Ingo Molnar <mingo@redhat.com>, Jens Axboe <axboe@kernel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Kees Cook <keescook@chromium.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Matthew Wilcox <willy@infradead.org>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Pekka Enberg <penberg@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Vegard Nossum <vegard.nossum@oracle.com>,
        Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, 29 Mar 2022 at 14:41, Alexander Potapenko <glider@google.com> wrote:
>
> kcov used to be broken prior to Clang 11, but right now that version is
> already the minimum required to build with KCSAN, because no prior
> compiler has "-tsan-distinguish-volatile=1".
>
> Therefore KCSAN_KCOV_BROKEN is not needed anymore.
>
> Suggested-by: Marco Elver <elver@google.com>
> Signed-off-by: Alexander Potapenko <glider@google.com>

FYI, this is superseded by
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b027471adaf955efde6153d67f391fe1604b7292

> ---
> Link: https://linux-review.googlesource.com/id/Ida287421577f37de337139b5b5b9e977e4a6fee2
> ---
>  lib/Kconfig.kcsan | 11 -----------
>  1 file changed, 11 deletions(-)
>
> diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
> index 63b70b8c55519..de022445fbba5 100644
> --- a/lib/Kconfig.kcsan
> +++ b/lib/Kconfig.kcsan
> @@ -10,21 +10,10 @@ config HAVE_KCSAN_COMPILER
>           For the list of compilers that support KCSAN, please see
>           <file:Documentation/dev-tools/kcsan.rst>.
>
> -config KCSAN_KCOV_BROKEN
> -       def_bool KCOV && CC_HAS_SANCOV_TRACE_PC
> -       depends on CC_IS_CLANG
> -       depends on !$(cc-option,-Werror=unused-command-line-argument -fsanitize=thread -fsanitize-coverage=trace-pc)
> -       help
> -         Some versions of clang support either KCSAN and KCOV but not the
> -         combination of the two.
> -         See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status
> -         in newer releases.
> -
>  menuconfig KCSAN
>         bool "KCSAN: dynamic data race detector"
>         depends on HAVE_ARCH_KCSAN && HAVE_KCSAN_COMPILER
>         depends on DEBUG_KERNEL && !KASAN
> -       depends on !KCSAN_KCOV_BROKEN
>         select STACKTRACE
>         help
>           The Kernel Concurrency Sanitizer (KCSAN) is a dynamic
> --
> 2.35.1.1021.g381101b075-goog
>