linux-kernel - [PATCH v2 06/18] arm64: kvm: use -fno-jump-tables with clang

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Date:   Wed, 15 Nov 2017 13:34:16 -0800
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     Alex Matveev <alxmtvv@...il.com>, Andi Kleen <ak@...ux.intel.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Greg Hackmann <ghackmann@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Maxim Kuvyrkov <maxim.kuvyrkov@...aro.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Yury Norov <ynorov@...iumnetworks.com>,
        Matthias Kaehlcke <mka@...omium.org>
Cc:     Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH v2 06/18] arm64: kvm: use -fno-jump-tables with clang

Use -fno-jump-tables to make sure clang doesn't generate branches
to EL1 virtual addresses.

Suggested-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
Signed-off-by: Sami Tolvanen <samitolvanen@...gle.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