[PATCH v2 06/18] arm64: kvm: use -fno-jump-tables with clang
From: mark.rutland@arm.com (Mark Rutland)
Date: 2017-11-20 14:41:54
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On Wed, Nov 15, 2017 at 01:34:16PM -0800, Sami Tolvanen wrote:
Use -fno-jump-tables to make sure clang doesn't generate branches to EL1 virtual addresses.
Are there any other reasons that clang might generate absolute references/relocations? It would be nice if there was the option to disable that more generally, rather than disabling individual optimizations. Is there any PIC/PIE option that we could use? We might need something simnilar for GCC, even if we're not seeing problems today. Thanks, Mark.
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Suggested-by: AKASHI Takahiro <redacted> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- arch/arm64/kvm/hyp/Makefile | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile index f04400d494b7..19fa1c6b6b69 100644 --- a/arch/arm64/kvm/hyp/Makefile +++ b/arch/arm64/kvm/hyp/Makefile@@ -5,6 +5,10 @@ ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING +ifeq ($(cc-name),clang) +ccflags-y += -fno-jump-tables +endif + KVM=../../../../virt/kvm obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/vgic-v2-sr.o-- 2.15.0.448.gf294e3d99a-goog