[PATCH 09/21] arm64: stackprotector: Re-enable per-task stackprotector

[Will Deacon]

Now that 'current' resides in TPIDRRO_EL0, update the per-task
stackprotector compiler invocation to use the new register.

Note that this requires a very recent build of clang [1], as (unlike
GCC), it historically rejected all registers other than SP_EL0.

Cc: Mark Rutland <mark.rutland at arm.com>
Link: https://github.com/llvm/llvm-project/pull/188054 [1]
Signed-off-by: Will Deacon <will at kernel.org>
---
 arch/arm64/Kconfig  | 3 +--
 arch/arm64/Makefile | 2 +-
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b8270b301809..020fcaf36b1b 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2450,12 +2450,11 @@ config RANDOMIZE_MODULE_REGION_FULL
 	  exhaustion, modules might be able to fall back to a larger 2GB area.
 
 config CC_HAVE_STACKPROTECTOR_SYSREG
-	def_bool $(cc-option,-mstack-protector-guard=sysreg -mstack-protector-guard-reg=sp_el0 -mstack-protector-guard-offset=0)
+	def_bool $(cc-option,-mstack-protector-guard=sysreg -mstack-protector-guard-reg=tpidrro_el0 -mstack-protector-guard-offset=0)
 
 config STACKPROTECTOR_PER_TASK
 	def_bool y
 	depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_SYSREG
-	depends on BROKEN
 
 config UNWIND_PATCH_PAC_INTO_SCS
 	bool "Enable shadow call stack dynamically using code patching"
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 6b005c8fef70..a293ab67818f 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -72,7 +72,7 @@ ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
 prepare: stack_protector_prepare
 stack_protector_prepare: prepare0
 	$(eval KBUILD_CFLAGS += -mstack-protector-guard=sysreg		  \
-				-mstack-protector-guard-reg=sp_el0	  \
+				-mstack-protector-guard-reg=tpidrro_el0	  \
 				-mstack-protector-guard-offset=$(shell	  \
 			awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}' \
 				$(objtree)/include/generated/asm-offsets.h))
-- 
2.55.0.979.g7e5102b832-goog