linux-kernel - Re: [PATCH 12/43] kcsan: clang: retire CONFIG_KCSAN_KCOV

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Date:   Wed, 15 Dec 2021 13:33:46 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Alexander Potapenko <glider@...gle.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@....de>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Ingo Molnar <mingo@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Marco Elver <elver@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Pekka Enberg <penberg@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/43] kcsan: clang: retire CONFIG_KCSAN_KCOV_BROKEN

On Tue, Dec 14, 2021 at 05:20:19PM +0100, Alexander Potapenko wrote:
> kcov used to be broken prior to Clang 11, but right now that version is
> already the minimum required to build with KCSAN, that is why we don't
> need KCSAN_KCOV_BROKEN anymore.

Just to check, how is that requirement enforced?

I see the core Makefiles enforce 10.0.1+, but I couldn't spot an explicit
version dependency in Kconfig.kcsan.

Otherwise, this looks good to me!

Mark.

> Suggested-by: Marco Elver <elver@...gle.com>
> Signed-off-by: Alexander Potapenko <glider@...gle.com>
> ---
> 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 e0a93ffdef30e..b81454b2a0d09 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
> -- 
> 2.34.1.173.g76aa8bc2d0-goog
>