[PATCH v2 00/10] kbuild: misc cleanups

[PATCH v2 00/10] kbuild: misc cleanups

[Masahiro Yamada]

This is a series of prerequisite cleanups of my next work.


Masahiro Yamada (10):
  kbuild: factor out genksyms command from cmd_gensymtypes_{c,S}
  kbuild: do not remove empty *.symtypes explicitly
  modpost: remove useless export_from_sec()
  modpost: move export_from_secname() call to more relevant place
  modpost: remove redundant initializes for static variables
  modpost: remove annoying namespace_from_kstrtabns()
  kbuild: get rid of duplication in the first line of *.mod files
  kbuild: split the second line of *.mod into *.usyms
  kbuild: refactor cmd_modversions_c
  kbuild: refactor cmd_modversions_S

 .gitignore                  |  1 +
 Makefile                    |  2 +-
 scripts/Makefile.build      | 86 ++++++++++++++++---------------------
 scripts/adjust_autoksyms.sh |  2 +-
 scripts/gen_autoksyms.sh    | 18 +++++---
 scripts/mod/modpost.c       | 49 ++++++---------------
 scripts/mod/modpost.h       |  4 --
 scripts/mod/sumversion.c    | 11 +----
 8 files changed, 64 insertions(+), 109 deletions(-)

-- 
2.32.0

[PATCH v2 09/10] kbuild: refactor cmd_modversions_c

[Masahiro Yamada]

cmd_modversions_c implements two parts; run genksyms to calculate CRCs
of exported symbols, run $(LD) to update the object with the CRCs. The
latter is not executed for CONFIG_LTO_CLANG=y since the object is not
ELF but LLVM bit code at this point.

The first part can be unified because we can always use $(NM) instead
of "$(OBJDUMP) -h" to dump the symbols.

Split the code into the two macros, cmd_gen_symversions_c and
cmd_modversions.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

Changes in v2:
 - new

 scripts/Makefile.build | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index d934bdf84de4..ba2be555f942 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -169,29 +169,25 @@ ifdef CONFIG_MODVERSIONS
 #   the actual value of the checksum generated by genksyms
 # o remove .tmp_<file>.o to <file>.o
 
-ifdef CONFIG_LTO_CLANG
 # Generate .o.symversions files for each .o with exported symbols, and link these
 # to the kernel and/or modules at the end.
-cmd_modversions_c =								\
+gen_symversions =								\
 	if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then			\
-		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
+		$(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
 		    > $@.symversions;						\
 	else									\
 		rm -f $@.symversions;						\
-	fi;
-else
-cmd_modversions_c =								\
-	if $(OBJDUMP) -h $@ | grep -q __ksymtab; then				\
-		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
-		    > $(@D)/.tmp_$(@F:.o=.ver);					\
-										\
+	fi
+
+cmd_gen_symversions_c =	$(call gen_symversions,c)
+
+cmd_modversions =								\
+	if [ -r $@.symversions ]; then						\
 		$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ 		\
-			-T $(@D)/.tmp_$(@F:.o=.ver);				\
+			-T $@.symversions;					\
 		mv -f $(@D)/.tmp_$(@F) $@;					\
-		rm -f $(@D)/.tmp_$(@F:.o=.ver);					\
 	fi
 endif
-endif
 
 ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
 # compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
@@ -269,7 +265,8 @@ define rule_cc_o_c
 	$(call cmd,checksrc)
 	$(call cmd,checkdoc)
 	$(call cmd,gen_objtooldep)
-	$(call cmd,modversions_c)
+	$(call cmd,gen_symversions_c)
+	$(if $(CONFIG_LTO_CLANG),,$(call cmd,modversions))
 	$(call cmd,record_mcount)
 endef
 
-- 
2.32.0

[PATCH v2 09/10] kbuild: refactor cmd_modversions_c

[Masahiro Yamada]

cmd_modversions_c implements two parts; run genksyms to calculate CRCs
of exported symbols, run $(LD) to update the object with the CRCs. The
latter is not executed for CONFIG_LTO_CLANG=y since the object is not
ELF but LLVM bit code at this point.

The first part can be unified because we can always use $(NM) instead
of "$(OBJDUMP) -h" to dump the symbols.

Split the code into the two macros, cmd_gen_symversions_c and
cmd_modversions.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

Changes in v2:
 - new

 scripts/Makefile.build | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index d934bdf84de4..ba2be555f942 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -169,29 +169,25 @@ ifdef CONFIG_MODVERSIONS
 #   the actual value of the checksum generated by genksyms
 # o remove .tmp_<file>.o to <file>.o
 
-ifdef CONFIG_LTO_CLANG
 # Generate .o.symversions files for each .o with exported symbols, and link these
 # to the kernel and/or modules at the end.
-cmd_modversions_c =								\
+gen_symversions =								\
 	if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then			\
-		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
+		$(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
 		    > $@.symversions;						\
 	else									\
 		rm -f $@.symversions;						\
-	fi;
-else
-cmd_modversions_c =								\
-	if $(OBJDUMP) -h $@ | grep -q __ksymtab; then				\
-		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
-		    > $(@D)/.tmp_$(@F:.o=.ver);					\
-										\
+	fi
+
+cmd_gen_symversions_c =	$(call gen_symversions,c)
+
+cmd_modversions =								\
+	if [ -r $@.symversions ]; then						\
 		$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ 		\
-			-T $(@D)/.tmp_$(@F:.o=.ver);				\
+			-T $@.symversions;					\
 		mv -f $(@D)/.tmp_$(@F) $@;					\
-		rm -f $(@D)/.tmp_$(@F:.o=.ver);					\
 	fi
 endif
-endif
 
 ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
 # compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
@@ -269,7 +265,8 @@ define rule_cc_o_c
 	$(call cmd,checksrc)
 	$(call cmd,checkdoc)
 	$(call cmd,gen_objtooldep)
-	$(call cmd,modversions_c)
+	$(call cmd,gen_symversions_c)
+	$(if $(CONFIG_LTO_CLANG),,$(call cmd,modversions))
 	$(call cmd,record_mcount)
 endef
 
-- 
2.32.0

Re: [PATCH v2 09/10] kbuild: refactor cmd_modversions_c

[Nick Desaulniers]

On Tue, Apr 5, 2022 at 4:34 AM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> cmd_modversions_c implements two parts; run genksyms to calculate CRCs
> of exported symbols, run $(LD) to update the object with the CRCs. The
> latter is not executed for CONFIG_LTO_CLANG=y since the object is not
> ELF but LLVM bit code at this point.
>
> The first part can be unified because we can always use $(NM) instead
> of "$(OBJDUMP) -h" to dump the symbols.
>
> Split the code into the two macros, cmd_gen_symversions_c and
> cmd_modversions.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>
> Changes in v2:
>  - new
>
>  scripts/Makefile.build | 25 +++++++++++--------------
>  1 file changed, 11 insertions(+), 14 deletions(-)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index d934bdf84de4..ba2be555f942 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -169,29 +169,25 @@ ifdef CONFIG_MODVERSIONS
>  #   the actual value of the checksum generated by genksyms
>  # o remove .tmp_<file>.o to <file>.o
>
> -ifdef CONFIG_LTO_CLANG
>  # Generate .o.symversions files for each .o with exported symbols, and link these
>  # to the kernel and/or modules at the end.
> -cmd_modversions_c =                                                            \
> +gen_symversions =                                                              \
>         if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then                       \
> -               $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))  \
> +               $(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
>                     > $@.symversions;                                           \
>         else                                                                    \
>                 rm -f $@.symversions;                                           \
> -       fi;
> -else
> -cmd_modversions_c =                                                            \
> -       if $(OBJDUMP) -h $@ | grep -q __ksymtab; then                           \
> -               $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))  \
> -                   > $(@D)/.tmp_$(@F:.o=.ver);                                 \
> -                                                                               \
> +       fi
> +
> +cmd_gen_symversions_c =        $(call gen_symversions,c)
> +
> +cmd_modversions =                                                              \
> +       if [ -r $@.symversions ]; then                                          \
>                 $(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@               \
> -                       -T $(@D)/.tmp_$(@F:.o=.ver);                            \
> +                       -T $@.symversions;                                      \
>                 mv -f $(@D)/.tmp_$(@F) $@;                                      \
> -               rm -f $(@D)/.tmp_$(@F:.o=.ver);                                 \
>         fi
>  endif
> -endif
>
>  ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
>  # compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
> @@ -269,7 +265,8 @@ define rule_cc_o_c
>         $(call cmd,checksrc)
>         $(call cmd,checkdoc)
>         $(call cmd,gen_objtooldep)
> -       $(call cmd,modversions_c)
> +       $(call cmd,gen_symversions_c)
> +       $(if $(CONFIG_LTO_CLANG),,$(call cmd,modversions))
>         $(call cmd,record_mcount)
>  endef
>
> --
> 2.32.0
>


-- 
Thanks,
~Nick Desaulniers