On Thu, Feb 20, 2014 at 6:21 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
> According to Documentation/Changes, make 3.80 is still being supported
> for building the kernel, hence make files must not make (unconditional)
> use of features introduced only in newer versions. Commit 8779657d
> ("stackprotector: Introduce CONFIG_CC_STACKPROTECTOR_STRONG") however
> introduced an "else ifdef" construct which make 3.80 doesn't understand.
Sounds fine to me; there is no third block to use a final "else", so
ditching the "else ifdef" is okay by me. Thanks for the fix!
>
> Also correct a warning message still referencing the old config option
> name.
>
> Apart from that I question the use of "ifdef" here (but it was used
> that way already prior to said commit): ifeq (,y) would seem more to
> the point.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> Makefile | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> --- 3.14-rc3/Makefile
> +++ 3.14-rc3-make-3.80/Makefile
> @@ -605,10 +605,11 @@ endif
> ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
> stackp-flag := -fstack-protector
> ifeq ($(call cc-option, $(stackp-flag)),)
> - $(warning Cannot use CONFIG_CC_STACKPROTECTOR: \
> + $(warning Cannot use CONFIG_CC_STACKPROTECTOR_REGULAR: \
> -fstack-protector not supported by compiler))
merge note: this line got the double-closing-paren fixed in a separate
patch. There must be a version of "make" that doesn't mind it, since
it seems neither you nor I tripped over it. :)
> endif
> -else ifdef CONFIG_CC_STACKPROTECTOR_STRONG
> +else
> +ifdef CONFIG_CC_STACKPROTECTOR_STRONG
> stackp-flag := -fstack-protector-strong
> ifeq ($(call cc-option, $(stackp-flag)),)
> $(warning Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: \
> @@ -618,6 +619,7 @@ else
> # Force off for distro compilers that enable stack protector by default.
> stackp-flag := $(call cc-option, -fno-stack-protector)
> endif
> +endif
> KBUILD_CFLAGS += $(stackp-flag)
>
> # This warning generated too much noise in a regular build.
Thanks!
-Kees
--
Kees Cook
Chrome OS Security
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