linux-kernel - [PATCH v2 09/10] kbuild: refactor cmd_modversions

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Date:   Tue,  5 Apr 2022 23:02:28 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     linux-kbuild@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        llvm@...ts.linux.dev
Subject: [PATCH v2 09/10] kbuild: refactor cmd_modversions_c

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@...nel.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)) \
 		    > $@...mversions;						\
 	else									\
 		rm -f $@...mversions;						\
-	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 $@...mversions ]; then						\
 		$(LD) $(KBUILD_LDFLAGS) -r -o $(@D)/.tmp_$(@F) $@ 		\
-			-T $(@D)/.tmp_$(@F:.o=.ver);				\
+			-T $@...mversions;					\
 		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