linux-kernel - Re: [PATCH v4 09/13] selftests/sgx: Specify freestanding environment for enclave compilation

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Date:   Sun, 27 Aug 2023 21:35:30 +0300
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Jo Van Bulck" <jo.vanbulck@...kuleuven.be>, <kai.huang@...el.com>,
        <linux-sgx@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Cc:     <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v4 09/13] selftests/sgx: Specify freestanding
 environment for enclave compilation

On Fri Aug 25, 2023 at 4:32 PM EEST, Jo Van Bulck wrote:
> Use -ffreestanding to assert the enclave compilation targets a
> freestanding environment (i.e., without "main" or standard libraries).
> This fixes clang reporting "undefined reference to `memset'" after
> erroneously optimizing away the provided memset/memcpy implementations.
>
> Still need to instruct the linker from using standard system startup
> functions, but drop -nostartfiles as it is implied by -nostdlib.
>
> Signed-off-by: Jo Van Bulck <jo.vanbulck@...kuleuven.be>
> ---
>  tools/testing/selftests/sgx/Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/sgx/Makefile b/tools/testing/selftests/sgx/Makefile
> index 2de970f7237c..f96667bdf9f2 100644
> --- a/tools/testing/selftests/sgx/Makefile
> +++ b/tools/testing/selftests/sgx/Makefile
> @@ -14,8 +14,8 @@ endif
>  INCLUDES := -I$(top_srcdir)/tools/include
>  HOST_CFLAGS := -Wall -Werror -g $(INCLUDES) -fPIC
>  HOST_LDFLAGS := -z noexecstack -lcrypto
> -ENCL_CFLAGS := -Wall -Werror -static-pie -nostdlib -nostartfiles -fPIE \
> -	       -fno-stack-protector -mrdrnd $(INCLUDES)
> +ENCL_CFLAGS := -Wall -Werror -static-pie -nostdlib -ffreestanding -fPIE \
> +		-fno-stack-protector -mrdrnd $(INCLUDES)
>  ENCL_LDFLAGS := -Wl,-T,test_encl.lds,--build-id=none
>  
>  TEST_CUSTOM_PROGS := $(OUTPUT)/test_sgx
> -- 
> 2.25.1

Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>

BR, Jarkko