[RFC PATCH] powerpc: Enable kcov

Dmitry Vyukov dvyukov at google.com
Tue Jan 15 17:40:52 AEDT 2019


On Tue, Jan 15, 2019 at 5:20 AM Andrew Donnellan
<andrew.donnellan at au1.ibm.com> wrote:
>
> 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.
>
> Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

Hi Andrew,

The patch looks good to me. Any reason to mail it as RFC rather than
final patch?

Acked-by: Dmitry Vyukov <dvyukov at google.com>

> ---
>
> kcov looks like it's working okay, both kcovtrace and syzkaller seem to be
> working. I did see some issues with compiling and booting kernels with gcc
> 6.3 and earlier versions which disappeared when I upgraded to gcc 8.2, I
> need to investigate that more.
>
> ---
>  arch/powerpc/Kconfig                | 1 +
>  arch/powerpc/kernel/Makefile        | 7 ++++++-
>  arch/powerpc/kernel/trace/Makefile  | 3 ++-
>  arch/powerpc/kernel/vdso32/Makefile | 1 +
>  arch/powerpc/kernel/vdso64/Makefile | 1 +
>  arch/powerpc/xmon/Makefile          | 1 +
>  6 files changed, 12 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..961f44eabb65 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -142,16 +142,21 @@ 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
>
> 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/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
>
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