Commit f05eb1d2 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

ARM: stackprotector: prefer compiler for TLS based per-task protector 



Currently, we implement the per-task stack protector for ARM using a GCC
plugin, due to lack of native compiler support. However, work is
underway to get this implemented in the compiler, which means we will be
able to deprecate the GCC plugin at some point.

In the meantime, we will need to support both, where the native compiler
implementation is obviously preferred. So let's wire this up in Kconfig
and the Makefile.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Tested-by: default avatarMarc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
parent 672513bf

arch/arm/Kconfig

+6 −2
Original line number Diff line number Diff line
@@ -1607,10 +1607,14 @@ config XEN 
	help

	  Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.



config CC_HAVE_STACKPROTECTOR_TLS

	def_bool $(cc-option,-mtp=cp15 -mstack-protector-guard=tls -mstack-protector-guard-offset=0)



config STACKPROTECTOR_PER_TASK

	bool "Use a unique stack canary value for each task"

	depends on GCC_PLUGINS && STACKPROTECTOR && THREAD_INFO_IN_TASK && !XIP_DEFLATED_DATA

	select GCC_PLUGIN_ARM_SSP_PER_TASK

	depends on STACKPROTECTOR && THREAD_INFO_IN_TASK && !XIP_DEFLATED_DATA

	depends on GCC_PLUGINS || CC_HAVE_STACKPROTECTOR_TLS

	select GCC_PLUGIN_ARM_SSP_PER_TASK if !CC_HAVE_STACKPROTECTOR_TLS

	default y

	help

	  Due to the fact that GCC uses an ordinary symbol reference from

arch/arm/Makefile

+9 −0
Original line number Diff line number Diff line
@@ -275,6 +275,14 @@ endif 


ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)

prepare: stack_protector_prepare

ifeq ($(CONFIG_CC_HAVE_STACKPROTECTOR_TLS),y)

stack_protector_prepare: prepare0

	$(eval KBUILD_CFLAGS += \

		-mstack-protector-guard=tls \

		-mstack-protector-guard-offset=$(shell	\

			awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}'\

				include/generated/asm-offsets.h))

else

stack_protector_prepare: prepare0

	$(eval SSP_PLUGIN_CFLAGS := \

		-fplugin-arg-arm_ssp_per_task_plugin-offset=$(shell	\
@@ -283,6 +291,7 @@ stack_protector_prepare: prepare0 
	$(eval KBUILD_CFLAGS += $(SSP_PLUGIN_CFLAGS))

	$(eval GCC_PLUGINS_CFLAGS += $(SSP_PLUGIN_CFLAGS))

endif

endif



all:	$(notdir $(KBUILD_IMAGE))