Re: [bpf-next PATCH v2 4/4] kbuild: refactor module BTF rule

Jiri Olsa
2023-10-19T08:15:52Z

On Thu, Oct 19, 2023 at 12:19:50AM +0900, Masahiro Yamada wrote:
> newer_prereqs_except and if_changed_except are ugly hacks of the
> newer-prereqs and if_changed in scripts/Kbuild.include.
>
> Remove.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
> Changes in v2:
> - Fix if_changed_except to if_changed
>
> scripts/Makefile.modfinal | 25 ++++++-------------------
> 1 file changed, 6 insertions(+), 19 deletions(-)
>
> diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
> index 9fd7a26e4fe9..fc07854bb7b9 100644
> --- a/scripts/Makefile.modfinal
> +++ b/scripts/Makefile.modfinal
> @@ -19,6 +19,9 @@ vmlinux :=
> ifdef CONFIG_DEBUG_INFO_BTF_MODULES
> ifneq ($(wildcard vmlinux),)
> vmlinux := vmlinux
> +cmd_btf = ; \
> + LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) --btf_base vmlinux $@; \
> + $(RESOLVE_BTFIDS) -b vmlinux $@
> else
> $(warning Skipping BTF generation due to unavailability of vmlinux)
> endif
> @@ -41,27 +44,11 @@ quiet_cmd_ld_ko_o = LD [M] $@
> cmd_ld_ko_o += \
> $(LD) -r $(KBUILD_LDFLAGS) \
> $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
> - -T scripts/module.lds -o $@ $(filter %.o, $^)
> + -T scripts/module.lds -o $@ $(filter %.o, $^) \
> + $(cmd_btf)
>
> -quiet_cmd_btf_ko = BTF [M] $@

nit not sure it's intentional but we no longer display 'BTF [M] ...ko' lines,
I don't mind not displaying that, but we should mention that in changelog

jirka

> - cmd_btf_ko = \
> - LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) --btf_base vmlinux $@; \
> - $(RESOLVE_BTFIDS) -b vmlinux $@
> -
> -# Same as newer-prereqs, but allows to exclude specified extra dependencies
> -newer_prereqs_except = $(filter-out $(PHONY) $(1),$?)
> -
> -# Same as if_changed, but allows to exclude specified extra dependencies
> -if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \
> - $(cmd); \
> - printf '%s\n' 'savedcmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
> -
> -# Re-generate module BTFs if either module's .ko or vmlinux changed
> %.ko: %.o %.mod.o scripts/module.lds $(vmlinux) FORCE
> - +$(call if_changed_except,ld_ko_o,vmlinux)
> -ifdef vmlinux
> - +$(if $(newer-prereqs),$(call cmd,btf_ko))
> -endif
> + +$(call if_changed,ld_ko_o)
>
> targets += $(modules:%.o=%.ko) $(modules:%.o=%.mod.o)
>
> --
> 2.40.1
>
>