Kbuild fixes for v5.12

- Fix UNUSED_KSYMS_WHITELIST for Clang LTO
 
  - Make -s builds really silent irrespective of V= option
 
  - Fix build error when SUBLEVEL or PATCHLEVEL is empty
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Merge tag 'kbuild-fixes-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Fix UNUSED_KSYMS_WHITELIST for Clang LTO

 - Make -s builds really silent irrespective of V= option

 - Fix build error when SUBLEVEL or PATCHLEVEL is empty

* tag 'kbuild-fixes-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: Fix <linux/version.h> for empty SUBLEVEL or PATCHLEVEL again
  kbuild: make -s option take precedence over V=1
  ia64: remove redundant READELF from arch/ia64/Makefile
  kbuild: do not include include/config/auto.conf from adjust_autoksyms.sh
  kbuild: fix UNUSED_KSYMS_WHITELIST for Clang LTO
  kbuild: lto: add _mcount to list of used symbols

Makefile

@@ -96,6 +96,7 @@ endif
 
 ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
   quiet=silent_
+  KBUILD_VERBOSE = 0
 endif
 
 export quiet Q KBUILD_VERBOSE
@@ -1283,10 +1284,10 @@ endef
 define filechk_version.h
 	if [ $(SUBLEVEL) -gt 255 ]; then                                 \
 		echo \#define LINUX_VERSION_CODE $(shell                 \
-		expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 255); \
+		expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + 255); \
 	else                                                             \
 		echo \#define LINUX_VERSION_CODE $(shell                 \
-		expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + $(SUBLEVEL)); \
+		expr $(VERSION) \* 65536 + $(PATCHLEVEL) \* 256 + $(SUBLEVEL)); \
 	fi;                                                              \
 	echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) +  \
 	((c) > 255 ? 255 : (c)))';                                       \
@@ -1295,6 +1296,8 @@ define filechk_version.h
 	echo \#define LINUX_VERSION_SUBLEVEL $(SUBLEVEL)
 endef
 
+$(version_h): PATCHLEVEL := $(if $(PATCHLEVEL), $(PATCHLEVEL), 0)
+$(version_h): SUBLEVEL := $(if $(SUBLEVEL), $(SUBLEVEL), 0)
 $(version_h): FORCE
 	$(call filechk,version.h)
 

arch/ia64/Makefile

@@ -14,7 +14,6 @@
 KBUILD_DEFCONFIG := generic_defconfig
 
 NM := $(CROSS_COMPILE)nm -B
-READELF := $(CROSS_COMPILE)readelf
 
 CHECKFLAGS	+= -D__ia64=1 -D__ia64__=1 -D_LP64 -D__LP64__
 

init/Kconfig

@@ -2283,7 +2283,6 @@ config TRIM_UNUSED_KSYMS
 config UNUSED_KSYMS_WHITELIST
 	string "Whitelist of symbols to keep in ksymtab"
 	depends on TRIM_UNUSED_KSYMS
-	default "scripts/lto-used-symbollist.txt" if LTO_CLANG
 	help
 	  By default, all unused exported symbols will be un-exported from the
 	  build when TRIM_UNUSED_KSYMS is selected.

scripts/adjust_autoksyms.sh

@@ -34,9 +34,6 @@ case "$KBUILD_VERBOSE" in
 	;;
 esac
 
-# We need access to CONFIG_ symbols
-. include/config/auto.conf
-
 # Generate a new symbol list file
 $CONFIG_SHELL $srctree/scripts/gen_autoksyms.sh "$new_ksyms_file"
 

scripts/gen_autoksyms.sh

@@ -19,7 +19,26 @@ esac
 # We need access to CONFIG_ symbols
 . include/config/auto.conf
 
-ksym_wl=/dev/null
+needed_symbols=
+
+# Special case for modversions (see modpost.c)
+if [ -n "$CONFIG_MODVERSIONS" ]; then
+	needed_symbols="$needed_symbols module_layout"
+fi
+
+# With CONFIG_LTO_CLANG, LLVM bitcode has not yet been compiled into a binary
+# when the .mod files are generated, which means they don't yet contain
+# references to certain symbols that will be present in the final binaries.
+if [ -n "$CONFIG_LTO_CLANG" ]; then
+	# intrinsic functions
+	needed_symbols="$needed_symbols memcpy memmove memset"
+	# ftrace
+	needed_symbols="$needed_symbols _mcount"
+	# stack protector symbols
+	needed_symbols="$needed_symbols __stack_chk_fail __stack_chk_guard"
+fi
+
+ksym_wl=
 if [ -n "$CONFIG_UNUSED_KSYMS_WHITELIST" ]; then
 	# Use 'eval' to expand the whitelist path and check if it is relative
 	eval ksym_wl="$CONFIG_UNUSED_KSYMS_WHITELIST"
@@ -40,16 +59,14 @@ cat > "$output_file" << EOT
 EOT
 
 [ -f modules.order ] && modlist=modules.order || modlist=/dev/null
-sed 's/ko$/mod/' $modlist |
-xargs -n1 sed -n -e '2{s/ /\n/g;/^$/!p;}' -- |
-cat - "$ksym_wl" |
+
+{
+	sed 's/ko$/mod/' $modlist | xargs -n1 sed -n -e '2p'
+	echo "$needed_symbols"
+	[ -n "$ksym_wl" ] && cat "$ksym_wl"
+} | sed -e 's/ /\n/g' | sed -n -e '/^$/!p' |
 # Remove the dot prefix for ppc64; symbol names with a dot (.) hold entry
 # point addresses.
 sed -e 's/^\.//' |
 sort -u |
 sed -e 's/\(.*\)/#define __KSYM_\1 1/' >> "$output_file"
-
-# Special case for modversions (see modpost.c)
-if [ -n "$CONFIG_MODVERSIONS" ]; then
-	echo "#define __KSYM_module_layout 1" >> "$output_file"
-fi

scripts/lto-used-symbollist.txt

@@ -1,5 +0,0 @@
-memcpy
-memmove
-memset
-__stack_chk_fail
-__stack_chk_guard