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stackprotector: update make rules 

Impact: no default -fno-stack-protector if stackp is enabled, cleanup

Stackprotector make rules had the following problems.

* cc support test and warning are scattered across makefile and
  kernel/panic.c.

* -fno-stack-protector was always added regardless of configuration.

Update such that cc support test and warning are contained in makefile
and -fno-stack-protector is added iff stackp is turned off.  While at
it, prepare for 32bit support.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Tejun Heo 2009-02-09 22:17:39 +09:00 committed by Ingo Molnar
parent 76397f72fb
commit 5d707e9c8e
4 changed files with 15 additions and 13 deletions
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3
Makefile
View File

@ -532,8 +532,9 @@ KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN})
endif
# Force gcc to behave correct even for buggy distributions
# Arch Makefiles may override this setting
ifndef CONFIG_CC_STACKPROTECTOR
KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
endif
ifdef CONFIG_FRAME_POINTER
KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls

17
arch/x86/Makefile
View File

@ -70,14 +70,17 @@ else
# this works around some issues with generating unwind tables in older gccs
# newer gccs do it by default
KBUILD_CFLAGS += -maccumulate-outgoing-args
endif
stackp := $(CONFIG_SHELL) $(srctree)/scripts/gcc-x86_64-has-stack-protector.sh
stackp-$(CONFIG_CC_STACKPROTECTOR) := $(shell $(stackp) \
"$(CC)" "-fstack-protector -DGCC_HAS_SP" )
stackp-$(CONFIG_CC_STACKPROTECTOR_ALL) += $(shell $(stackp) \
"$(CC)" -fstack-protector-all )
KBUILD_CFLAGS += $(stackp-y)
ifdef CONFIG_CC_STACKPROTECTOR
cc_has_sp := $(srctree)/scripts/gcc-x86_$(BITS)-has-stack-protector.sh
ifeq ($(shell $(CONFIG_SHELL) $(cc_has_sp) $(CC)),y)
stackp-y := -fstack-protector
stackp-$(CONFIG_CC_STACKPROTECTOR_ALL) += -fstack-protector-all
KBUILD_CFLAGS += $(stackp-y)
else
$(warning stack protector enabled but no compiler support)
endif
endif
# Stackpointer is addressed different for 32 bit and 64 bit x86

4
kernel/panic.c
View File

@ -359,10 +359,6 @@ EXPORT_SYMBOL(warn_slowpath);
#ifdef CONFIG_CC_STACKPROTECTOR
#ifndef GCC_HAS_SP
#warning You have selected the CONFIG_CC_STACKPROTECTOR option, but the gcc used does not support this.
#endif
/*
* Called when gcc's -fstack-protector feature is used, and
* gcc detects corruption of the on-stack canary value

4
scripts/gcc-x86_64-has-stack-protector.sh
View File

@ -2,5 +2,7 @@
echo "int foo(void) { char X[200]; return 3; }" | $1 -S -xc -c -O0 -mcmodel=kernel -fstack-protector - -o - 2> /dev/null | grep -q "%gs"
if [ "$?" -eq "0" ] ; then
echo $2
echo y
else
echo n
fi