[Buildroot] [PATCH 3/5 v2] toolchain: check the SSP option is known

[Arnout Vandecappelle <arnout@mind.be>]

On 12/03/2019 13:09, yann.morin at orange.com wrote:
> From: "Yann E. MORIN" <yann.morin@orange.com>
> 
> Some toolchain vendors may have backported those options to older gcc
> versions, and we have no way to know, so we have to check that the
> user's selection is acceptable.
> 
> Extend the macro that currently checks for SSP in the toolchain, with
> a new test that the actual SSP option is recognised and accepted.
> 
> Note that the SSP option is either totaly empty, or an already-quoted
> string, so we can safely and easily assign it to a shell variable to
> test and use it.
> 
> Note that we do not introduce BR2_TOOLCHAIN_HAS_SSP_STRONG, because:
> 
>   - our internal toolchain infra only supports gcc >= 4.9, so it has
>     SSP strong;
> 
>   - of the external pre-built toolchains, only the codesourcery-arm
>     one has a gcc-4.8 which lacks SSP strong, all the others have a
>     gcc >= 4.9;
> 
>   - we'd still have to do the actual check for custom external
>     toolchains anyway.
> 
> So, we're not adding BR2_TOOLCHAIN_HAS_SSP_STRONG just for a single
> case.
> 
> Signed-off-by: "Yann E. MORIN" <yann.morin@orange.com>
> Cc: Matt Weber <matthew.weber@rockwellcollins.com>
> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
> Cc: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
> Cc: Arnout Vandecappelle <arnout@mind.be>
> 
> ---
> Changes v1 -> v2:
>   - expand the commit log to explain why we're not adding
>     BR2_TOOLCHAIN_HAS_SSP_STRONG  (Arnout)
> ---
>  toolchain/helpers.mk                                   | 8 ++++++++
>  toolchain/toolchain-external/pkg-toolchain-external.mk | 2 +-
>  2 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/toolchain/helpers.mk b/toolchain/helpers.mk
> index e5520c00c3..ba097e83cf 100644
> --- a/toolchain/helpers.mk
> +++ b/toolchain/helpers.mk
> @@ -415,6 +415,7 @@ check_unusable_toolchain = \
>  # Check if the toolchain has SSP (stack smashing protector) support
>  #
>  # $1: cross-gcc path
> +# $2: gcc ssp option
>  #
>  check_toolchain_ssp = \
>  	__CROSS_CC=$(strip $1) ; \
> @@ -427,6 +428,13 @@ check_toolchain_ssp = \
>  		echo "SSP support not available in this toolchain, please disable BR2_TOOLCHAIN_EXTERNAL_HAS_SSP" ; \
>  		exit 1 ; \
>  	fi ; \
> +	__SSP_OPTION=$(2); \

 Is there any reason to pass this as an argument rather than using
$(BR2_SSP_OPTION) directly?

 The same goes for $(TOOLCHAIN_EXTERNAL_CC), but that ship has sailed.

 Regards,
 Arnout

> +	if [ -n "$${__SSP_OPTION}" ] ; then \
> +		if ! echo 'void main(){}' | $${__CROSS_CC} -Werror $${__SSP_OPTION} -x c - -o $(BUILD_DIR)/.br-toolchain-test.tmp >/dev/null 2>&1 ; then \
> +			echo "SSP option $${__SSP_OPTION} not available in this toolchain, please select another SSP level" ; \
> +			exit 1 ; \
> +		fi; \
> +	fi; \
>  	rm -f $(BUILD_DIR)/.br-toolchain-test.tmp*
>  
>  #
> diff --git a/toolchain/toolchain-external/pkg-toolchain-external.mk b/toolchain/toolchain-external/pkg-toolchain-external.mk
> index db3570d96f..00cbd7b17a 100644
> --- a/toolchain/toolchain-external/pkg-toolchain-external.mk
> +++ b/toolchain/toolchain-external/pkg-toolchain-external.mk
> @@ -549,7 +549,7 @@ define $(2)_CONFIGURE_CMDS
>  	else \
>  		$$(call check_glibc,$$$${SYSROOT_DIR}) ; \
>  	fi
> -	$$(Q)$$(call check_toolchain_ssp,$$(TOOLCHAIN_EXTERNAL_CC))
> +	$$(Q)$$(call check_toolchain_ssp,$$(TOOLCHAIN_EXTERNAL_CC),$(BR2_SSP_OPTION))
>  endef
>  
>  $(2)_TOOLCHAIN_WRAPPER_ARGS += $$(TOOLCHAIN_EXTERNAL_TOOLCHAIN_WRAPPER_ARGS)
>