From: Arjan van de Ven Add a feature check that checks that the gcc compiler has stack-protector support and has the bugfix for PR28281 to make this work in kernel mode. The easiest solution I could find was to have a shell script in scripts/ to do the detection; if needed we can make this fancier in the future without making the makefile too complex. Signed-off-by: Arjan van de Ven Cc: Andi Kleen Acked-by: Sam Ravnborg Signed-off-by: Andrew Morton --- arch/x86_64/Makefile | 9 +++++++++ scripts/gcc-x86_64-has-stack-protector.sh | 6 ++++++ 2 files changed, 15 insertions(+) diff -puN arch/x86_64/Makefile~fstack-protector-feature-enable-the-compiler-flags arch/x86_64/Makefile --- a/arch/x86_64/Makefile~fstack-protector-feature-enable-the-compiler-flags +++ a/arch/x86_64/Makefile @@ -55,6 +55,15 @@ cflags-y += $(call cc-option,-funit-at-a # prevent gcc from generating any FP code by mistake cflags-y += $(call cc-option,-mno-sse -mno-mmx -mno-sse2 -mno-3dnow,) + +stack-protector = $(shell $(CONFIG_SHELL) \ + $(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(1)) + +cflags-$(CONFIG_CC_STACKPROTECTOR) += \ + $(call stack-protector, $(CC) -fstack-protector) +cflags-$(CONFIG_CC_STACKPROTECTOR_ALL) += \ + $(call stack-protector, $(CC) -fstack-protector-all) + CFLAGS += $(cflags-y) CFLAGS_KERNEL += $(cflags-kernel-y) AFLAGS += -m64 diff -puN /dev/null scripts/gcc-x86_64-has-stack-protector.sh --- /dev/null +++ a/scripts/gcc-x86_64-has-stack-protector.sh @@ -0,0 +1,6 @@ +#!/bin/sh + +echo "int foo(void) { char X[200]; return 3; }" | $1 -S -xc -c -O0 -mcmodel=kernel -fstack-protector - -o - | grep -q "%gs" +if [ "$?" -eq "0" ] ; then + echo $2 +fi _