Re: [PATCH v1] arm64: allow building with kcov coverage on ARM64

From: Alexander Potapenko
Date: Thu Mar 31 2016 - 10:02:53 EST


On Thu, Mar 31, 2016 at 3:54 PM, Alexander Potapenko <glider@xxxxxxxxxx> wrote:
> Add ARCH_HAS_KCOV to ARM64 config. Disable instrumentation of
> arch/arm64/lib/delay.c
>
> Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
> ---
> arch/arm64/Kconfig | 1 +
> arch/arm64/lib/Makefile | 3 +++
> 2 files changed, 4 insertions(+)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 4f43622..c52aa61 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/lib/Makefile b/arch/arm64/lib/Makefile
> index c86b790..b407bc1 100644
> --- a/arch/arm64/lib/Makefile
> +++ b/arch/arm64/lib/Makefile
> @@ -1,3 +1,6 @@
> +# Produces uninteresting flaky coverage.
> +KCOV_INSTRUMENT_delay.o := n
> +
> lib-y := bitops.o clear_user.o delay.o copy_from_user.o \
> copy_to_user.o copy_in_user.o copy_page.o \
> clear_page.o memchr.o memcpy.o memmove.o memset.o \
> --
> 2.8.0.rc3.226.g39d4020
>

Hi all,

I've ported the above patch from kernel 3.18, which I was able to
successfully run with kcov support on an arm64 device.
The original 3.18 patch is at
https://chromium-review.googlesource.com/#/c/334560/1, it also touches
arch/arm64/kernel/Makefile, which is unnecessary in upstream code,
because efi-stub.c has been moved to libstub.
Therefore I suspect the above patch should be correct, but I don't
have an opportunity to actually test it.

Alex

--
Alexander Potapenko
Software Engineer

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