linux-kernel - Re: [PATCH v2] riscv: Allow building with kcov coverage

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Message-ID: <mhng-5606ac04-c52e-4211-bd30-fce86df7f0fd@palmerdabbelt-glaptop1>
Date:   Fri, 10 Jul 2020 21:27:30 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     tklauser@...tanz.ch
CC:     Paul Walmsley <paul.walmsley@...ive.com>, aou@...s.berkeley.edu,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Bjorn Topel <bjorn.topel@...il.com>, dvyukov@...gle.com
Subject:     Re: [PATCH v2] riscv: Allow building with kcov coverage

On Fri, 26 Jun 2020 05:40:56 PDT (-0700), tklauser@...tanz.ch wrote:
> Add ARCH_HAS_KCOV and HAVE_GCC_PLUGINS to the riscv Kconfig.
> Also disable instrumentation of some early boot code and vdso.
>
> Boot-tested on QEMU's riscv64 virt machine.

Thanks.  This is on for-next (with the ack).  I'm boot testing a config with

    CONFIG_KCOV=y
    CONFIG_KCOV_ENABLE_COMPARISONS=y

but LMK if there's something more interesting to test.  I don't see anything
coverage-related in the boot log...

> Cc: Björn Töpel <bjorn.topel@...il.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Signed-off-by: Tobias Klauser <tklauser@...tanz.ch>
> ---
>  arch/riscv/Kconfig              | 2 ++
>  arch/riscv/boot/Makefile        | 2 ++
>  arch/riscv/kernel/vdso/Makefile | 1 +
>  arch/riscv/mm/Makefile          | 2 ++
>  4 files changed, 7 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 089293e4ad46..a7d7f8184f15 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -19,6 +19,7 @@ config RISCV
>  	select ARCH_HAS_DEBUG_WX
>  	select ARCH_HAS_GCOV_PROFILE_ALL
>  	select ARCH_HAS_GIGANTIC_PAGE
> +	select ARCH_HAS_KCOV
>  	select ARCH_HAS_MMIOWB
>  	select ARCH_HAS_PTE_SPECIAL
>  	select ARCH_HAS_SET_DIRECT_MAP
> @@ -57,6 +58,7 @@ config RISCV
>  	select HAVE_DMA_CONTIGUOUS if MMU
>  	select HAVE_EBPF_JIT if MMU
>  	select HAVE_FUTEX_CMPXCHG if FUTEX
> +	select HAVE_GCC_PLUGINS
>  	select HAVE_GENERIC_VDSO if MMU && 64BIT
>  	select HAVE_PCI
>  	select HAVE_PERF_EVENTS
> diff --git a/arch/riscv/boot/Makefile b/arch/riscv/boot/Makefile
> index 3530c59b3ea7..c59fca695f9d 100644
> --- a/arch/riscv/boot/Makefile
> +++ b/arch/riscv/boot/Makefile
> @@ -14,6 +14,8 @@
>  # Based on the ia64 and arm64 boot/Makefile.
>  #
>
> +KCOV_INSTRUMENT := n
> +
>  OBJCOPYFLAGS_Image :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
>
>  targets := Image loader
> diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile
> index 29cf052f6541..4b0d3bcc44e5 100644
> --- a/arch/riscv/kernel/vdso/Makefile
> +++ b/arch/riscv/kernel/vdso/Makefile
> @@ -29,6 +29,7 @@ CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
>
>  # Disable gcov profiling for VDSO code
>  GCOV_PROFILE := n
> +KCOV_INSTRUMENT := n
>
>  # Force dependency
>  $(obj)/vdso.o: $(obj)/vdso.so
> diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
> index 363ef01c30b1..c0185e556ca5 100644
> --- a/arch/riscv/mm/Makefile
> +++ b/arch/riscv/mm/Makefile
> @@ -5,6 +5,8 @@ ifdef CONFIG_FTRACE
>  CFLAGS_REMOVE_init.o = -pg
>  endif
>
> +KCOV_INSTRUMENT_init.o := n
> +
>  obj-y += init.o
>  obj-y += extable.o
>  obj-$(CONFIG_MMU) += fault.o pageattr.o