[PATCH v4] arm64: allow building with kcov coverage on ARM64

Add ARCH_HAS_KCOV to ARM64 config. To avoid potential crashes, disable
instrumentation of the files in arch/arm64/kvm/hyp/*.

Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Marc Zyngier <redacted>
Tested-by: James Morse <james.morse@arm.com>
---
v4: - added ack from Marc Zyngier and Tested-by from James Morse
v3: - reverted arch/arm64/boot/Makefile, there's no code in that dir
    - added ack from Mark Rutland
v2: - disable instrumentation of arch/arm64/{boot,kvm/hyp}
    - enable instrumentation of arch/arm64/lib/delay.c
---
 arch/arm64/Kconfig          | 1 +
 arch/arm64/kvm/hyp/Makefile | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5a0a691..eb0b0a0 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -7,6 +7,7 @@ config ARM64
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_GCOV_PROFILE_ALL
+	select ARCH_HAS_KCOV
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_USE_CMPXCHG_LOCKREF

diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
index 778d0ef..0c85feb 100644
--- a/arch/arm64/kvm/hyp/Makefile
+++ b/arch/arm64/kvm/hyp/Makefile

@@ -17,6 +17,10 @@ obj-$(CONFIG_KVM_ARM_HOST) += tlb.o
 obj-$(CONFIG_KVM_ARM_HOST) += hyp-entry.o
 obj-$(CONFIG_KVM_ARM_HOST) += s2-setup.o
 
+# KVM code is run at a different exception code with a different map, so
+# compiler instrumentation that inserts callbacks or checks into the code may
+# cause crashes. Just disable it.
 GCOV_PROFILE	:= n
 KASAN_SANITIZE	:= n
 UBSAN_SANITIZE	:= n
+KCOV_INSTRUMENT	:= n

-- 
2.8.0.rc3.226.g39d4020

On Thu, Jun 16, 2016 at 06:39:52PM +0200, Alexander Potapenko wrote:

Add ARCH_HAS_KCOV to ARM64 config. To avoid potential crashes, disable
instrumentation of the files in arch/arm64/kvm/hyp/*.

Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Marc Zyngier <redacted>
Tested-by: James Morse <james.morse@arm.com>

Thanks. I'll queue it for 4.8.

-- 
Catalin