[PATCH v3 2/2] powerpc: Enable kcov

[Daniel Axtens]

Hi Andrew,

> kcov provides kernel coverage data that's useful for fuzzing tools like
> syzkaller.
>
> Wire up kcov support on powerpc. Disable kcov instrumentation on the same
> files where we currently disable gcov and UBSan instrumentation, plus some
> additional exclusions which appear necessary to boot on book3e machines.
>
> Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>
> Acked-by: Dmitry Vyukov <dvyukov at google.com>
> Tested-by: Daniel Axtens <dja at axtens.net> # e6500

Just confirming that this still works for me.

Regards,
Daniel

> ---
>
> v2->v3:
> - Add additional exclusions required to boot on book3e (dja)
> ---
>  arch/powerpc/Kconfig                |  1 +
>  arch/powerpc/kernel/Makefile        | 12 +++++++++++-
>  arch/powerpc/kernel/trace/Makefile  |  3 ++-
>  arch/powerpc/kernel/vdso32/Makefile |  1 +
>  arch/powerpc/kernel/vdso64/Makefile |  1 +
>  arch/powerpc/mm/Makefile            |  5 +++++
>  arch/powerpc/xmon/Makefile          |  1 +
>  7 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 2890d36eb531..d3698dae0e60 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -134,6 +134,7 @@ config PPC
>  	select ARCH_HAS_ELF_RANDOMIZE
>  	select ARCH_HAS_FORTIFY_SOURCE
>  	select ARCH_HAS_GCOV_PROFILE_ALL
> +	select ARCH_HAS_KCOV
>  	select ARCH_HAS_PHYS_TO_DMA
>  	select ARCH_HAS_PMEM_API                if PPC64
>  	select ARCH_HAS_PTE_SPECIAL
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index cb7f0bb9ee71..3ae079014c04 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -142,19 +142,29 @@ endif
>  obj-$(CONFIG_EPAPR_PARAVIRT)	+= epapr_paravirt.o epapr_hcalls.o
>  obj-$(CONFIG_KVM_GUEST)		+= kvm.o kvm_emul.o
>  
> -# Disable GCOV & sanitizers in odd or sensitive code
> +# Disable GCOV, KCOV & sanitizers in odd or sensitive code
>  GCOV_PROFILE_prom_init.o := n
> +KCOV_INSTRUMENT_prom_init.o := n
>  UBSAN_SANITIZE_prom_init.o := n
>  GCOV_PROFILE_machine_kexec_64.o := n
> +KCOV_INSTRUMENT_machine_kexec_64.o := n
>  UBSAN_SANITIZE_machine_kexec_64.o := n
>  GCOV_PROFILE_machine_kexec_32.o := n
> +KCOV_INSTRUMENT_machine_kexec_32.o := n
>  UBSAN_SANITIZE_machine_kexec_32.o := n
>  GCOV_PROFILE_kprobes.o := n
> +KCOV_INSTRUMENT_kprobes.o := n
>  UBSAN_SANITIZE_kprobes.o := n
>  GCOV_PROFILE_kprobes-ftrace.o := n
> +KCOV_INSTRUMENT_kprobes-ftrace.o := n
>  UBSAN_SANITIZE_kprobes-ftrace.o := n
>  UBSAN_SANITIZE_vdso.o := n
>  
> +# Necessary for booting with kcov enabled on book3e machines
> +KCOV_INSTRUMENT_cputable.o := n
> +KCOV_INSTRUMENT_setup_64.o := n
> +KCOV_INSTRUMENT_paca.o := n
> +
>  extra-$(CONFIG_PPC_FPU)		+= fpu.o
>  extra-$(CONFIG_ALTIVEC)		+= vector.o
>  extra-$(CONFIG_PPC64)		+= entry_64.o
> diff --git a/arch/powerpc/kernel/trace/Makefile b/arch/powerpc/kernel/trace/Makefile
> index b1725ad3e13d..858503775c58 100644
> --- a/arch/powerpc/kernel/trace/Makefile
> +++ b/arch/powerpc/kernel/trace/Makefile
> @@ -23,6 +23,7 @@ obj-$(CONFIG_TRACING)			+= trace_clock.o
>  obj-$(CONFIG_PPC64)			+= $(obj64-y)
>  obj-$(CONFIG_PPC32)			+= $(obj32-y)
>  
> -# Disable GCOV & sanitizers in odd or sensitive code
> +# Disable GCOV, KCOV & sanitizers in odd or sensitive code
>  GCOV_PROFILE_ftrace.o := n
> +KCOV_INSTRUMENT_ftrace.o := n
>  UBSAN_SANITIZE_ftrace.o := n
> diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile
> index 50112d4473bb..ce199f6e4256 100644
> --- a/arch/powerpc/kernel/vdso32/Makefile
> +++ b/arch/powerpc/kernel/vdso32/Makefile
> @@ -23,6 +23,7 @@ targets := $(obj-vdso32) vdso32.so vdso32.so.dbg
>  obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
>  
>  GCOV_PROFILE := n
> +KCOV_INSTRUMENT := n
>  UBSAN_SANITIZE := n
>  
>  ccflags-y := -shared -fno-common -fno-builtin
> diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile
> index 69cecb346269..28e7d112aa2f 100644
> --- a/arch/powerpc/kernel/vdso64/Makefile
> +++ b/arch/powerpc/kernel/vdso64/Makefile
> @@ -9,6 +9,7 @@ targets := $(obj-vdso64) vdso64.so vdso64.so.dbg
>  obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
>  
>  GCOV_PROFILE := n
> +KCOV_INSTRUMENT := n
>  UBSAN_SANITIZE := n
>  
>  ccflags-y := -shared -fno-common -fno-builtin
> diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
> index f965fc33a8b7..d4d32e229ace 100644
> --- a/arch/powerpc/mm/Makefile
> +++ b/arch/powerpc/mm/Makefile
> @@ -55,3 +55,8 @@ obj-$(CONFIG_PPC_BOOK3S_64)	+= dump_linuxpagetables-book3s64.o
>  endif
>  obj-$(CONFIG_PPC_HTDUMP)	+= dump_hashpagetable.o
>  obj-$(CONFIG_PPC_MEM_KEYS)	+= pkeys.o
> +
> +# Disable kcov instrumentation on sensitive code
> +# This is necessary for booting with kcov enabled on book3e machines
> +KCOV_INSTRUMENT_tlb_nohash.o := n
> +KCOV_INSTRUMENT_fsl_booke_mmu.o := n
> diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile
> index 878f9c1d3615..3050f9323254 100644
> --- a/arch/powerpc/xmon/Makefile
> +++ b/arch/powerpc/xmon/Makefile
> @@ -5,6 +5,7 @@
>  subdir-ccflags-y := $(call cc-disable-warning, builtin-requires-header)
>  
>  GCOV_PROFILE := n
> +KCOV_INSTRUMENT := n
>  UBSAN_SANITIZE := n
>  
>  # Disable ftrace for the entire directory
> -- 
> 2.11.0