Kbuild fixes for v5.18

- Fix empty $(PYTHON) expansion.
 
  - Fix UML, which got broken by the attempt to suppress Clang warnings.
 
  - Fix warning message in modpost.
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Merge tag 'kbuild-fixes-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Fix empty $(PYTHON) expansion.

 - Fix UML, which got broken by the attempt to suppress Clang warnings.

 - Fix warning message in modpost.

* tag 'kbuild-fixes-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  modpost: restore the warning message for missing symbol versions
  Revert "um: clang: Strip out -mno-global-merge from USER_CFLAGS"
  kbuild: Remove '-mno-global-merge'
  kbuild: fix empty ${PYTHON} in scripts/link-vmlinux.sh
  kconfig: remove stale comment about removed kconfig_print_symbol()

Makefile

@@ -793,10 +793,6 @@ ifdef CONFIG_CC_IS_CLANG
 KBUILD_CPPFLAGS += -Qunused-arguments
 # The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
 KBUILD_CFLAGS += -Wno-gnu
-# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
-# source of a reference will be _MergedGlobals and not on of the whitelisted names.
-# See modpost pattern 2
-KBUILD_CFLAGS += -mno-global-merge
 else
 
 # gcc inanely warns about local variables called 'main'

arch/um/Makefile

@@ -75,10 +75,6 @@ USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \
 		-D_FILE_OFFSET_BITS=64 -idirafter $(srctree)/include \
 		-idirafter $(objtree)/include -D__KERNEL__ -D__UM_HOST__
 
-ifdef CONFIG_CC_IS_CLANG
-USER_CFLAGS := $(patsubst -mno-global-merge,,$(USER_CFLAGS))
-endif
-
 #This will adjust *FLAGS accordingly to the platform.
 include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS)
 

scripts/kconfig/confdata.c

@@ -658,13 +658,6 @@ static char *escape_string_value(const char *in)
 	return out;
 }
 
-/*
- * Kconfig configuration printer
- *
- * This printer is used when generating the resulting configuration after
- * kconfig invocation and `defconfig' files. Unset symbol might be omitted by
- * passing a non-NULL argument to the printer.
- */
 enum output_n { OUTPUT_N, OUTPUT_N_AS_UNSET, OUTPUT_N_NONE };
 
 static void __print_symbol(FILE *fp, struct symbol *sym, enum output_n output_n,

scripts/link-vmlinux.sh

@@ -50,7 +50,7 @@ gen_initcalls()
 {
 	info GEN .tmp_initcalls.lds
 
-	${PYTHON} ${srctree}/scripts/jobserver-exec		\
+	${PYTHON3} ${srctree}/scripts/jobserver-exec		\
 	${PERL} ${srctree}/scripts/generate_initcall_order.pl	\
 		${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}	\
 		> .tmp_initcalls.lds

scripts/mod/modpost.c

@@ -674,7 +674,7 @@ static void handle_modversion(const struct module *mod,
 	unsigned int crc;
 
 	if (sym->st_shndx == SHN_UNDEF) {
-		warn("EXPORT symbol \"%s\" [%s%s] version ...\n"
+		warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n"
 		     "Is \"%s\" prototyped in <asm/asm-prototypes.h>?\n",
 		     symname, mod->name, mod->is_vmlinux ? "" : ".ko",
 		     symname);