From 758517202bd2e427664857c9f2aa59da36848aca Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov@google.com>
Date: Thu, 14 Jun 2018 15:27:44 -0700
Subject: arm: port KCOV to arm

KCOV is code coverage collection facility used, in particular, by
syzkaller system call fuzzer.  There is some interest in using syzkaller
on arm devices.  So port KCOV to arm.

On implementation level this merely declares that KCOV is supported and
disables instrumentation of 3 special cases.  Reasons for disabling are
commented in code.

Tested with qemu-system-arm/vexpress-a15.

Link: http://lkml.kernel.org/r/20180511143248.112484-1-dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Abbott Liu <liuwenliang@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Koguchi Takuo <takuo.koguchi.sw@hitachi.com>
Cc: <syzkaller@googlegroups.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/arm/vdso/Makefile | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'arch/arm/vdso/Makefile')

diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile
index bb4118213fee..f4efff9d3afb 100644
--- a/arch/arm/vdso/Makefile
+++ b/arch/arm/vdso/Makefile
@@ -30,6 +30,9 @@ CFLAGS_vgettimeofday.o = -O2
 # Disable gcov profiling for VDSO code
 GCOV_PROFILE := n
 
+# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
+KCOV_INSTRUMENT := n
+
 # Force dependency
 $(obj)/vdso.o : $(obj)/vdso.so
 
-- 
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