linux-kernel - Re: [PATCH] ARM: decompressor: simplify libfdt builds

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Date:   Fri, 17 Jan 2020 22:15:34 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: decompressor: simplify libfdt builds

On Wed, Dec 04, 2019 at 01:49:50PM +0900, Masahiro Yamada wrote:
> Copying source files during the build time may not end up with
> as clean code as expected.
> 
> lib/fdt*.c simply wrap scripts/dtc/libfdt/fdt*.c, and it works
> nicely. Let's follow that approach for the arm decompressor, too.
> 
> Add four wrappers, arch/arm/boot/compressed/fdt*.c and remove
> the Makefile messes. Another nice thing is we no longer need to
> maintain the own libfdt_env.h because the decompressor can include
> <linux/libfdt_env.h>.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
> 
> KernelVersion: v5.5-rc1
> 
> 
>  arch/arm/boot/compressed/.gitignore     |  9 -------
>  arch/arm/boot/compressed/Makefile       | 33 +++++++------------------
>  arch/arm/boot/compressed/atags_to_fdt.c |  1 +
>  arch/arm/boot/compressed/fdt.c          |  1 +
>  arch/arm/boot/compressed/fdt_ro.c       |  1 +
>  arch/arm/boot/compressed/fdt_rw.c       |  1 +
>  arch/arm/boot/compressed/fdt_wip.c      |  1 +
>  arch/arm/boot/compressed/libfdt_env.h   | 24 ------------------
>  8 files changed, 14 insertions(+), 57 deletions(-)
>  create mode 100644 arch/arm/boot/compressed/fdt.c
>  create mode 100644 arch/arm/boot/compressed/fdt_ro.c
>  create mode 100644 arch/arm/boot/compressed/fdt_rw.c
>  create mode 100644 arch/arm/boot/compressed/fdt_wip.c
>  delete mode 100644 arch/arm/boot/compressed/libfdt_env.h
> 
> diff --git a/arch/arm/boot/compressed/.gitignore b/arch/arm/boot/compressed/.gitignore
> index 86b2f5d28240..2fdb4885846b 100644
> --- a/arch/arm/boot/compressed/.gitignore
> +++ b/arch/arm/boot/compressed/.gitignore
> @@ -6,12 +6,3 @@ hyp-stub.S
>  piggy_data
>  vmlinux
>  vmlinux.lds
> -
> -# borrowed libfdt files
> -fdt.c
> -fdt.h
> -fdt_ro.c
> -fdt_rw.c
> -fdt_wip.c
> -libfdt.h
> -libfdt_internal.h
> diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
> index da599c3a1193..d01ce71afac6 100644
> --- a/arch/arm/boot/compressed/Makefile
> +++ b/arch/arm/boot/compressed/Makefile
> @@ -76,29 +76,23 @@ compress-$(CONFIG_KERNEL_LZMA) = lzma
>  compress-$(CONFIG_KERNEL_XZ)   = xzkern
>  compress-$(CONFIG_KERNEL_LZ4)  = lz4
>  
> -# Borrowed libfdt files for the ATAG compatibility mode
> -
> -libfdt		:= fdt_rw.c fdt_ro.c fdt_wip.c fdt.c
> -libfdt_hdrs	:= fdt.h libfdt.h libfdt_internal.h
> -
> -libfdt_objs	:= $(addsuffix .o, $(basename $(libfdt)))
> -
> -$(addprefix $(obj)/,$(libfdt) $(libfdt_hdrs)): $(obj)/%: $(srctree)/scripts/dtc/libfdt/%
> -	$(call cmd,shipped)
> +ifeq ($(CONFIG_ARM_ATAG_DTB_COMPAT),y)
> +libfdt_objs = fdt_rw.o fdt_ro.o fdt_wip.o fdt.o atags_to_fdt.o
>  
> -$(addprefix $(obj)/,$(libfdt_objs) atags_to_fdt.o): \
> -	$(addprefix $(obj)/,$(libfdt_hdrs))
> +OBJS	+= $(libfdt_objs)
>  
> -ifeq ($(CONFIG_ARM_ATAG_DTB_COMPAT),y)
> -OBJS	+= $(libfdt_objs) atags_to_fdt.o
> +# -fstack-protector-strong triggers protection checks in this code,
> +# but it is being used too early to link to meaningful stack_chk logic.
> +nossp-flags-$(CONFIG_CC_HAS_STACKPROTECTOR_NONE) := -fno-stack-protector
> +$(foreach o, $(libfdt_objs), \
> +	$(eval CFLAGS_$(o) := -I $(srctree)/scripts/dtc/libfdt) $(nossp-flags-y))

The above change causes build breakage over a number of ARM builds,
which unfortunately doesn't result in emails from any build system
containing the cause of the failure.

See
https://kernelci.org/build/rmk/branch/for-next/kernel/v5.5-rc1-12-g9a6545e2fc83/

where the failures are reported as:

../arch/arm/boot/compressed/Makefile:87: *** missing separator. Stop.

Thanks.  Patch dropped.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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