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From:   Marco Elver <elver@google.com>
Date:   Tue, 23 Mar 2021 13:51:32 +0100
Message-ID: <CANpmjNM8D+yp==DmKP0aa+g6=P38o0v6gd7y5iV52yyDUv91qw@mail.gmail.com>
Subject: Re: [PATCH] kasan: fix hwasan build for gcc
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>
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On Tue, 23 Mar 2021 at 13:41, Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> gcc-11 adds support for -fsanitize=kernel-hwaddress, so it becomes
> possible to enable CONFIG_KASAN_SW_TAGS.
>
> Unfortunately this fails to build at the moment, because the
> corresponding command line arguments use llvm specific syntax.
>
> Change it to use the cc-param macro instead, which works on both
> clang and gcc.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

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

Although I think you need to rebase against either -mm or -next,
because there have been changes to the CONFIG_KASAN_STACK variable.

> ---
>  scripts/Makefile.kasan | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
> index 1e000cc2e7b4..0a2789783d1b 100644
> --- a/scripts/Makefile.kasan
> +++ b/scripts/Makefile.kasan
> @@ -36,14 +36,14 @@ endif # CONFIG_KASAN_GENERIC
>  ifdef CONFIG_KASAN_SW_TAGS
>
>  ifdef CONFIG_KASAN_INLINE
> -    instrumentation_flags := -mllvm -hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET)
> +    instrumentation_flags := $(call cc-param,hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET))
>  else
> -    instrumentation_flags := -mllvm -hwasan-instrument-with-calls=1
> +    instrumentation_flags := $(call cc-param,hwasan-instrument-with-calls=1)
>  endif
>
>  CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
> -               -mllvm -hwasan-instrument-stack=$(CONFIG_KASAN_STACK) \
> -               -mllvm -hwasan-use-short-granules=0 \
> +               $(call cc-param,hwasan-instrument-stack=$(CONFIG_KASAN_STACK)) \
> +               $(call cc-param,hwasan-use-short-granules=0) \
>                 $(instrumentation_flags)
>
>  endif # CONFIG_KASAN_SW_TAGS
> --
> 2.29.2
>