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Commit 75851720 authored by Dmitry Vyukov's avatar Dmitry Vyukov Committed by Linus Torvalds
Browse files

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: default avatarDmitry Vyukov <dvyukov@google.com>
Acked-by: default avatarMark 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0ed557aa

arch/arm/Kconfig

+2 −1
Original line number Diff line number Diff line
@@ -8,9 +8,10 @@ config ARM 
	select ARCH_HAS_DEVMEM_IS_ALLOWED

	select ARCH_HAS_ELF_RANDOMIZE

	select ARCH_HAS_FORTIFY_SOURCE

	select ARCH_HAS_KCOV

	select ARCH_HAS_PTE_SPECIAL if ARM_LPAE

	select ARCH_HAS_SET_MEMORY

	select ARCH_HAS_PHYS_TO_DMA

	select ARCH_HAS_SET_MEMORY

	select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL

	select ARCH_HAS_STRICT_MODULE_RWX if MMU

	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST

arch/arm/boot/compressed/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -25,6 +25,9 @@ endif 


GCOV_PROFILE		:= n



# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.

KCOV_INSTRUMENT		:= n



#

# Architecture dependencies

#

arch/arm/kvm/hyp/Makefile

+8 −0
Original line number Diff line number Diff line
@@ -23,3 +23,11 @@ obj-$(CONFIG_KVM_ARM_HOST) += hyp-entry.o 
obj-$(CONFIG_KVM_ARM_HOST) += switch.o

CFLAGS_switch.o		   += $(CFLAGS_ARMV7VE)

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

arch/arm/vdso/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -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