[PATCH 2/3] kbuild: add infrastructure to build userspace programs

[Sascha Hauer]

On Tue, Jun 23, 2020 at 12:07:01PM +0900, Masahiro Yamada wrote:
> Import Linux commit 7f3a59db274c3e3d884c785e363a054110f1c266
> 
> Signed-off-by: Masahiro Yamada <masahiroy at kernel.org>
> ---
>

Very nice. Building userspace programs always was kind of a hack.

Applied, thanks

Sascha

>  Makefile                   | 13 ++++++++---
>  scripts/Makefile.build     |  6 +++++
>  scripts/Makefile.clean     |  2 +-
>  scripts/Makefile.userprogs | 45 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 62 insertions(+), 4 deletions(-)
>  create mode 100644 scripts/Makefile.userprogs
> 
> diff --git a/Makefile b/Makefile
> index a4aac3db4..0da032532 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -363,9 +363,12 @@ HOST_LFS_LIBS := $(shell getconf LFS_LIBS 2>/dev/null)
>  
>  HOSTCC       = gcc
>  HOSTCXX      = g++
> -KBUILD_HOSTCFLAGS   := -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 \
> -		-fomit-frame-pointer -std=gnu89 $(HOST_LFS_CFLAGS) \
> -		$(HOSTCFLAGS)
> +
> +export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
> +			      -O2 -fomit-frame-pointer -std=gnu89
> +export KBUILD_USERLDFLAGS :=
> +
> +KBUILD_HOSTCFLAGS   := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
>  KBUILD_HOSTCXXFLAGS := -Wall -O2 $(HOST_LFS_CFLAGS) $(HOSTCXXFLAGS)
>  KBUILD_HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS)
>  KBUILD_HOSTLDLIBS   := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
> @@ -608,6 +611,10 @@ KBUILD_CFLAGS += $(call cc-option, -fno-delete-null-pointer-checks,)
>  
>  KBUILD_CFLAGS   += $(call cc-disable-warning, address-of-packed-member)
>  
> +# Align the bit size of userspace programs with the kernel
> +KBUILD_USERCFLAGS  += $(filter -m32 -m64, $(KBUILD_CFLAGS))
> +KBUILD_USERLDFLAGS += $(filter -m32 -m64, $(KBUILD_CFLAGS))
> +
>  # arch Makefile may override CC so keep this after arch Makefile is included
>  NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
>  CHECKFLAGS     += $(NOSTDINC_FLAGS)
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 00f627791..a3dfe261a 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -49,6 +49,12 @@ ifneq ($(hostprogs)$(hostprogs-y)$(hostprogs-m),)
>  include scripts/Makefile.host
>  endif
>  
> +# Do not include userprogs rules unless needed.
> +userprogs := $(sort $(userprogs))
> +ifneq ($(userprogs),)
> +include scripts/Makefile.userprogs
> +endif
> +
>  ifndef obj
>  $(warning kbuild: Makefile.build is included improperly)
>  endif
> diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
> index 6e6c9ef7c..97fd2ef48 100644
> --- a/scripts/Makefile.clean
> +++ b/scripts/Makefile.clean
> @@ -37,7 +37,7 @@ subdir-ymn	:= $(addprefix $(obj)/,$(subdir-ymn))
>  
>  __clean-files	:= $(extra-y) $(extra-m) $(extra-)       \
>  		   $(always) $(always-y) $(always-m) $(always-) $(targets) $(clean-files)   \
> -		   $(hostprogs) $(hostprogs-y) $(hostprogs-m) $(hostprogs-)
> +		   $(hostprogs) $(hostprogs-y) $(hostprogs-m) $(hostprogs-) $(userprogs)
>  
>  # as clean-files is given relative to the current directory, this adds
>  # a $(obj) prefix, except for absolute paths
> diff --git a/scripts/Makefile.userprogs b/scripts/Makefile.userprogs
> new file mode 100644
> index 000000000..fb4152973
> --- /dev/null
> +++ b/scripts/Makefile.userprogs
> @@ -0,0 +1,45 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# Build userspace programs for the target system
> +#
> +
> +# Executables compiled from a single .c file
> +user-csingle	:= $(foreach m, $(userprogs), $(if $($(m)-objs),,$(m)))
> +
> +# Executables linked based on several .o files
> +user-cmulti	:= $(foreach m, $(userprogs), $(if $($(m)-objs),$(m)))
> +
> +# Objects compiled from .c files
> +user-cobjs	:= $(sort $(foreach m, $(userprogs), $($(m)-objs)))
> +
> +user-csingle	:= $(addprefix $(obj)/, $(user-csingle))
> +user-cmulti	:= $(addprefix $(obj)/, $(user-cmulti))
> +user-cobjs	:= $(addprefix $(obj)/, $(user-cobjs))
> +
> +user_ccflags	= -Wp,-MMD,$(depfile) $(KBUILD_USERCFLAGS) $(userccflags) \
> +			$($(target-stem)-userccflags)
> +user_ldflags	= $(KBUILD_USERLDFLAGS) $(userldflags) $($(target-stem)-userldflags)
> +
> +# Create an executable from a single .c file
> +quiet_cmd_user_cc_c = CC [U]  $@
> +      cmd_user_cc_c = $(CC) $(user_ccflags) $(user_ldflags) -o $@ $< \
> +		      $($(target-stem)-userldlibs)
> +$(user-csingle): $(obj)/%: $(src)/%.c FORCE
> +	$(call if_changed_dep,user_cc_c)
> +
> +# Link an executable based on list of .o files
> +quiet_cmd_user_ld = LD [U]  $@
> +      cmd_user_ld = $(CC) $(user_ldflags) -o $@ \
> +		    $(addprefix $(obj)/, $($(target-stem)-objs)) \
> +		    $($(target-stem)-userldlibs)
> +$(user-cmulti): FORCE
> +	$(call if_changed,user_ld)
> +$(call multi_depend, $(user-cmulti), , -objs)
> +
> +# Create .o file from a .c file
> +quiet_cmd_user_cc_o_c = CC [U]  $@
> +      cmd_user_cc_o_c = $(CC) $(user_ccflags) -c -o $@ $<
> +$(user-cobjs): $(obj)/%.o: $(src)/%.c FORCE
> +	$(call if_changed_dep,user_cc_o_c)
> +
> +targets += $(user-csingle) $(user-cmulti) $(user-cobjs)
> -- 
> 2.25.1
> 
> 
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