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Date:   Mon, 26 Sep 2022 13:14:08 +0200
From:   Pavel Machek <pavel@denx.de>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        James Morse <james.morse@arm.com>,
        Sami Tolvanen <samitolvanen@google.com>,
        Kees Cook <keescook@chromium.org>,
        Ard Biesheuvel <ardb@kernel.org>,
        Will Deacon <will@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 4.14 05/40] efi/libstub: Disable Shadow Call Stack
Message-ID: <20220926111408.GF8978@amd>
References: <20220926100738.148626940@linuxfoundation.org>
 <20220926100738.422260948@linuxfoundation.org>
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Hi!

> From: Sami Tolvanen <samitolvanen@google.com>
>=20
> [ Upstream commit cc49c71d2abe99c1c2c9bedf0693ad2d3ee4a067 ]
>=20
> Shadow stacks are not available in the EFI stub, filter out SCS
> flags.

AFAICT, SCS is not available in 4.19, CC_FLAGS_SCS is not defined
there, and we should apply this patch.

Best regards,
								Pavel

> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -23,6 +23,9 @@ KBUILD_CFLAGS			:=3D $(cflags-y) -DDISABLE_BRANCH_PROFI=
LING \
>  				   $(call cc-option,-ffreestanding) \
>  				   $(call cc-option,-fno-stack-protector)
> =20
> +# remove SCS flags from all objects in this directory
> +KBUILD_CFLAGS :=3D $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
> +
>  GCOV_PROFILE			:=3D n
>  KASAN_SANITIZE			:=3D n
>  UBSAN_SANITIZE			:=3D n

--=20
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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