kbuild: use $(obj)/ instead of $(src)/ for common pattern rules

JIRA: https://issues.redhat.com/browse/RHEL-107194

commit 9a0ebe5
Author: Masahiro Yamada <masahiroy@kernel.org>
Date:   Sat Apr 27 23:55:01 2024 +0900

    kbuild: use $(obj)/ instead of $(src)/ for common pattern rules

    Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
    checked-in source files. It is merely a convention without any functional
    difference. In fact, $(obj) and $(src) are exactly the same, as defined
    in scripts/Makefile.build:

      src := $(obj)

    Before changing the semantics of $(src) in the next commit, this commit
    replaces $(obj)/ with $(src)/ in pattern rules where the prerequisite
    might be a generated file.

    C, assembly, Rust, and DTS files are sometimes generated by tools, so
    they could be either generated files or real sources. The $(obj)/ prefix
    works for both cases with the help of VPATH.

    As mentioned above, $(obj) and $(src) are the same at this point, hence
    this commit has no functional change.

    I did not modify scripts/Makefile.userprogs because there is no use
    case where userspace C files are generated.

    Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
    Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

Conflicts:
- scripts/Makefile.lib: since RHEL 9 does not have "dt-bindings: kbuild:
  Use DTB files for validation", we patch the yaml target instead.
- At scripts/Makefile.build:
  * Adjusted $(obj)/%.symversions patching due previously applied RHEL only
    commit "kbuild: expose explicit .symversions targets" and which now
    needs to also be update with this change
  * Dropped patching of some targets (eg. with %.rs) since RHEL 9 does not
    have "Kbuild: add Rust support"

Assisted-by: Patchpal AI
Signed-off-by: Herton R. Krzesinski <herton@redhat.com>

Author: Herton R. Krzesinski

scripts/Makefile.build

@@ -109,13 +109,13 @@ endif
 quiet_cmd_cc_s_c = CC $(quiet_modtag)  $@
       cmd_cc_s_c = $(CC) $(filter-out $(DEBUG_CFLAGS) $(CC_FLAGS_LTO), $(c_flags)) -fverbose-asm -S -o $@ $<
 
-$(obj)/%.s: $(src)/%.c FORCE
+$(obj)/%.s: $(obj)/%.c FORCE
 	$(call if_changed_dep,cc_s_c)
 
 quiet_cmd_cpp_i_c = CPP $(quiet_modtag) $@
 cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<
 
-$(obj)/%.i: $(src)/%.c FORCE
+$(obj)/%.i: $(obj)/%.c FORCE
 	$(call if_changed_dep,cpp_i_c)
 
 genksyms = scripts/genksyms/genksyms		\
@@ -128,22 +128,23 @@ cmd_gensymtypes_c = $(CPP) -D__GENKSYMS__ $(c_flags) $< | $(genksyms)
 
 quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
       cmd_cc_symtypes_c = $(call cmd_gensymtypes_c,true,$@) >/dev/null
+
+$(obj)/%.symtypes : $(obj)/%.c FORCE
+	$(call cmd,cc_symtypes_c)
+
 cmd_cc_symversions_c =                                                          \
     $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))   > $@;  \
     test -s $@ || rm -f $@
 
-$(obj)/%.symtypes : $(src)/%.c FORCE
-	$(call cmd,cc_symtypes_c)
-
-$(obj)/%.symversions : $(src)/%.c FORCE
+$(obj)/%.symversions : $(obj)/%.c FORCE
 	$(call cmd,cc_symversions_c)
 
 # LLVM assembly
 # Generate .ll files from .c
 quiet_cmd_cc_ll_c = CC $(quiet_modtag)  $@
       cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $<
 
-$(obj)/%.ll: $(src)/%.c FORCE
+$(obj)/%.ll: $(obj)/%.c FORCE
 	$(call if_changed_dep,cc_ll_c)
 
 # C (.c) files
@@ -245,7 +246,7 @@ define rule_as_o_S
 endef
 
 # Built-in and composite module parts
-$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
+$(obj)/%.o: $(obj)/%.c $(recordmcount_source) FORCE
 	$(call if_changed_rule,cc_o_c)
 	$(call cmd,force_checksrc)
 
@@ -268,7 +269,7 @@ quiet_cmd_cc_lst_c = MKLST   $@
 		     $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
 				     System.map $(OBJDUMP) > $@
 
-$(obj)/%.lst: $(src)/%.c FORCE
+$(obj)/%.lst: $(obj)/%.c FORCE
 	$(call if_changed_dep,cc_lst_c)
 
 # Compile assembler sources (.S)
@@ -305,20 +306,21 @@ cmd_gensymversions_S =                                                      \
 
 quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
       cmd_cc_symtypes_S = $(call cmd_gensymtypes_S,true,$@) >/dev/null
+
+$(obj)/%.symtypes : $(obj)/%.S FORCE
+	$(call cmd,cc_symtypes_S)
+
 cmd_cc_symversions_S =                                                      \
     $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))   > $@;  \
     test -s $@ || rm -f $@
 
-$(obj)/%.symtypes : $(src)/%.S FORCE
-	$(call cmd,cc_symtypes_S)
-
-$(obj)/%.symversions : $(src)/%.S FORCE
+$(obj)/%.symversions : $(obj)/%.S FORCE
 	$(call cmd,cc_symversions_S)
 
 quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
 cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<
 
-$(obj)/%.s: $(src)/%.S FORCE
+$(obj)/%.s: $(obj)/%.S FORCE
 	$(call if_changed_dep,cpp_s_S)
 
 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
@@ -333,7 +335,7 @@ cmd_gen_symversions_S = $(call gen_symversions,S)
 
 endif
 
-$(obj)/%.o: $(src)/%.S FORCE
+$(obj)/%.o: $(obj)/%.S FORCE
 	$(call if_changed_rule,as_o_S)
 
 targets += $(filter-out $(subdir-builtin), $(real-obj-y))

scripts/Makefile.host

@@ -91,7 +91,7 @@ hostcxx_flags  = -Wp,-MMD,$(depfile) $(_hostcxx_flags)
 quiet_cmd_host-csingle 	= HOSTCC  $@
       cmd_host-csingle	= $(HOSTCC) $(hostc_flags) $(KBUILD_HOSTLDFLAGS) -o $@ $< \
 		$(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem))
-$(host-csingle): $(obj)/%: $(src)/%.c FORCE
+$(host-csingle): $(obj)/%: $(obj)/%.c FORCE
 	$(call if_changed_dep,host-csingle)
 
 # Link an executable based on list of .o files, all plain c
@@ -108,7 +108,7 @@ $(call multi_depend, $(host-cmulti), , -objs)
 # host-cobjs -> .o
 quiet_cmd_host-cobjs	= HOSTCC  $@
       cmd_host-cobjs	= $(HOSTCC) $(hostc_flags) -c -o $@ $<
-$(host-cobjs): $(obj)/%.o: $(src)/%.c FORCE
+$(host-cobjs): $(obj)/%.o: $(obj)/%.c FORCE
 	$(call if_changed_dep,host-cobjs)
 
 # Link an executable based on list of .o files, a mixture of .c and .cc

scripts/Makefile.lib

@@ -429,7 +429,7 @@ define rule_dtc
 	$(call cmd,dtb_check)
 endef
 
-$(obj)/%.dt.yaml: $(src)/%.dts $(DTC) $(DT_TMP_SCHEMA) FORCE
+$(obj)/%.dt.yaml: $(obj)/%.dts $(DTC) $(DT_TMP_SCHEMA) FORCE
 	$(call if_changed_rule,dtc)
 
 $(obj)/%.dtbo: $(src)/%.dtso $(DTC) FORCE