linux-kernel - Re: [PATCH v2 16/18] arm64: crypto: disable LTO for aes-ce-cipher.c

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Message-ID: <20171120152014.hftuded4zxwn2r7m@lakrids.cambridge.arm.com>
Date:   Mon, 20 Nov 2017 15:20:14 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Sami Tolvanen <samitolvanen@...gle.com>
Cc:     Alex Matveev <alxmtvv@...il.com>, Andi Kleen <ak@...ux.intel.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Greg Hackmann <ghackmann@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Maxim Kuvyrkov <maxim.kuvyrkov@...aro.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Yury Norov <ynorov@...iumnetworks.com>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: Re: [PATCH v2 16/18] arm64: crypto: disable LTO for aes-ce-cipher.c

On Wed, Nov 15, 2017 at 01:34:26PM -0800, Sami Tolvanen wrote:
> CONFIG_LTO_CLANG requires the use of clang's integrated assembler, which
> doesn't understand the inline assembly in aes-ce-cipher.c. Disable LTO for
> the file to work around the issue.

Could you elaborate on what the integrated asembler doesn't like?

It's not entirely clear at a glance, as the asm in that file doesn't
seem to do anything that obscure.

Is it a bug?

Thanks,
Mark.

> Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
> ---
>  arch/arm64/crypto/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/crypto/Makefile b/arch/arm64/crypto/Makefile
> index b5edc5918c28..af08508521a3 100644
> --- a/arch/arm64/crypto/Makefile
> +++ b/arch/arm64/crypto/Makefile
> @@ -24,7 +24,7 @@ obj-$(CONFIG_CRYPTO_CRC32_ARM64_CE) += crc32-ce.o
>  crc32-ce-y:= crc32-ce-core.o crc32-ce-glue.o
>  
>  obj-$(CONFIG_CRYPTO_AES_ARM64_CE) += aes-ce-cipher.o
> -CFLAGS_aes-ce-cipher.o += -march=armv8-a+crypto
> +CFLAGS_aes-ce-cipher.o += -march=armv8-a+crypto $(DISABLE_LTO_CLANG)
>  
>  obj-$(CONFIG_CRYPTO_AES_ARM64_CE_CCM) += aes-ce-ccm.o
>  aes-ce-ccm-y := aes-ce-ccm-glue.o aes-ce-ccm-core.o
> -- 
> 2.15.0.448.gf294e3d99a-goog
>