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Date:   Tue, 18 Apr 2023 09:14:42 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Marco Elver <elver@google.com>, 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>,
        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
Subject: Re: [PATCH] [v2] kasan: remove hwasan-kernel-mem-intrinsic-prefix=1
 for clang-14
Message-ID: <20230418161442.GA3753@dev-arch.thelio-3990X>
References: <20230418122350.1646391-1-arnd@kernel.org>
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On Tue, Apr 18, 2023 at 02:23:35PM +0200, Arnd Bergmann 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: Nathan Chancellor <nathan@kernel.org>

Kudos to Marco for figuring out the 'starting with the letter "h"' part
of this issue :)

> ---
> 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
>