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Message-Id: <20191018161033.261971-13-samitolvanen@google.com>
Date: Fri, 18 Oct 2019 09:10:27 -0700
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Will Deacon <will@...nel.org>, Catalin Marinas <catalin.marinas@....com>,
Steven Rostedt <rostedt@...dmis.org>, Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Dave Martin <Dave.Martin@....com>, Kees Cook <keescook@...omium.org>,
Laura Abbott <labbott@...hat.com>, Mark Rutland <mark.rutland@....com>,
Nick Desaulniers <ndesaulniers@...gle.com>, clang-built-linux@...glegroups.com,
kernel-hardening@...ts.openwall.com, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH 12/18] arm64: reserve x18 only with Shadow Call Stack
Only reserve x18 with CONFIG_SHADOW_CALL_STACK. Note that all external
kernel modules must also have x18 reserved if the kernel uses SCS.
Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
arch/arm64/Makefile | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 1c7b276bc7c5..ef76101201b2 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -55,7 +55,7 @@ endif
KBUILD_CFLAGS += -mgeneral-regs-only $(lseinstr) $(brokengasinst) \
$(compat_vdso) $(cc_has_k_constraint)
-KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -ffixed-x18
+KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
KBUILD_CFLAGS += $(call cc-disable-warning, psabi)
KBUILD_AFLAGS += $(lseinstr) $(brokengasinst) $(compat_vdso)
@@ -72,6 +72,10 @@ stack_protector_prepare: prepare0
include/generated/asm-offsets.h))
endif
+ifeq ($(CONFIG_SHADOW_CALL_STACK), y)
+KBUILD_CFLAGS += -ffixed-x18
+endif
+
ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
KBUILD_CPPFLAGS += -mbig-endian
CHECKFLAGS += -D__AARCH64EB__
--
2.23.0.866.gb869b98d4c-goog
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