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From:   Marco Elver <elver@google.com>
Date:   Tue, 18 Apr 2023 15:07:09 +0200
Message-ID: <CANpmjNOSi32aN54_=WH1xb4jqzso+-riMomLxoqebO=AdbpHVA@mail.gmail.com>
Subject: Re: [PATCH] [v2] kasan: remove hwasan-kernel-mem-intrinsic-prefix=1
 for clang-14
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>, Tom Rix <trix@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        kasan-dev@googlegroups.com, linux-kbuild@vger.kernel.org,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev
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On Tue, 18 Apr 2023 at 14:24, Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> Some unknown -mllvm options (i.e. those starting with the letter "h")
> don't cause an error to be returned by clang, so the cc-option helper
> adds the unknown hwasan-kernel-mem-intrinsic-prefix=1 flag to CFLAGS
> with compilers that are new enough for hwasan but too old for this option.
>
> This causes a rather unreadable build failure:
>
> fixdep: error opening file: scripts/mod/.empty.o.d: No such file or directory
> make[4]: *** [/home/arnd/arm-soc/scripts/Makefile.build:252: scripts/mod/empty.o] Error 2
> fixdep: error opening file: scripts/mod/.devicetable-offsets.s.d: No such file or directory
> make[4]: *** [/home/arnd/arm-soc/scripts/Makefile.build:114: scripts/mod/devicetable-offsets.s] Error 2
>
> Add a version check to only allow this option with clang-15, gcc-13
> or later versions.
>
> Fixes: 51287dcb00cc ("kasan: emit different calls for instrumentable memintrinsics")
> Link: https://lore.kernel.org/all/CANpmjNMwYosrvqh4ogDO8rgn+SeDHM2b-shD21wTypm_6MMe=g@mail.gmail.com/
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Marco Elver <elver@google.com>

Thanks!

> ---
> v2: use one-line version check for both clang and gcc, clarify changelog text
> ---
>  scripts/Makefile.kasan | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
> index c186110ffa20..390658a2d5b7 100644
> --- a/scripts/Makefile.kasan
> +++ b/scripts/Makefile.kasan
> @@ -69,7 +69,9 @@ CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
>                 $(instrumentation_flags)
>
>  # Instrument memcpy/memset/memmove calls by using instrumented __hwasan_mem*().
> +ifeq ($(call clang-min-version, 150000)$(call gcc-min-version, 130000),y)
>  CFLAGS_KASAN += $(call cc-param,hwasan-kernel-mem-intrinsic-prefix=1)
> +endif
>
>  endif # CONFIG_KASAN_SW_TAGS
>
> --
> 2.39.2
>
>