Merge tag 'kbuild-fixes-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - fix warning in out-of-tree 'make clean'

 - add READELF variable to the top Makefile

 - fix broken builds when LINUX_COMPILE_BY contains a backslash

 - fix build warning in kallsyms

 - fix NULL pointer access in expr_eq() in Kconfig

 - fix missing dependency on rsync in deb-pkg build

 - remove ---help--- from documentation

 - fix misleading documentation about directory descending

* tag 'kbuild-fixes-v5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: clarify the difference between obj-y and obj-m w.r.t. descending
  kconfig: remove ---help--- from documentation
  scripts: package: mkdebian: add missing rsync dependency
  kconfig: don't crash on NULL expressions in expr_eq()
  scripts/kallsyms: fix offset overflow of kallsyms_relative_base
  mkcompile_h: use printf for LINUX_COMPILE_BY
  mkcompile_h: git rid of UTS_TRUNCATE from LINUX_COMPILE_{BY,HOST}
  x86/boot: kbuild: allow readelf executable to be specified
  kbuild: fix 'No such file or directory' warning when cleaning

Author: torvalds

Documentation/kbuild/kconfig-language.rst

@@ -196,14 +196,11 @@ applicable everywhere (see syntax).
   or equal to the first symbol and smaller than or equal to the second
   symbol.
 
-- help text: "help" or "---help---"
+- help text: "help"
 
   This defines a help text. The end of the help text is determined by
   the indentation level, this means it ends at the first line which has
   a smaller indentation than the first line of the help text.
-  "---help---" and "help" do not differ in behaviour, "---help---" is
-  used to help visually separate configuration logic from help within
-  the file as an aid to developers.
 
 - misc options: "option" <symbol>[=<value>]
 

Documentation/kbuild/makefiles.rst

@@ -297,9 +297,19 @@ more details, with real examples.
 	If CONFIG_EXT2_FS is set to either 'y' (built-in) or 'm' (modular)
 	the corresponding obj- variable will be set, and kbuild will descend
 	down in the ext2 directory.
-	Kbuild only uses this information to decide that it needs to visit
-	the directory, it is the Makefile in the subdirectory that
-	specifies what is modular and what is built-in.
+
+	Kbuild uses this information not only to decide that it needs to visit
+	the directory, but also to decide whether or not to link objects from
+	the directory into vmlinux.
+
+	When Kbuild descends into the directory with 'y', all built-in objects
+	from that directory are combined into the built-in.a, which will be
+	eventually linked into vmlinux.
+
+	When Kbuild descends into the directory with 'm', in contrast, nothing
+	from that directory will be linked into vmlinux. If the Makefile in
+	that directory specifies obj-y, those objects will be left orphan.
+	It is very likely a bug of the Makefile or of dependencies in Kconfig.
 
 	It is good practice to use a `CONFIG_` variable when assigning directory
 	names. This allows kbuild to totally skip the directory if the

Makefile

@@ -414,6 +414,7 @@ STRIP		= $(CROSS_COMPILE)strip
 OBJCOPY		= $(CROSS_COMPILE)objcopy
 OBJDUMP		= $(CROSS_COMPILE)objdump
 OBJSIZE		= $(CROSS_COMPILE)size
+READELF		= $(CROSS_COMPILE)readelf
 PAHOLE		= pahole
 LEX		= flex
 YACC		= bison
@@ -472,7 +473,7 @@ GCC_PLUGINS_CFLAGS :=
 CLANG_FLAGS :=
 
 export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE AS LD CC
-export CPP AR NM STRIP OBJCOPY OBJDUMP OBJSIZE PAHOLE LEX YACC AWK INSTALLKERNEL
+export CPP AR NM STRIP OBJCOPY OBJDUMP OBJSIZE READELF PAHOLE LEX YACC AWK INSTALLKERNEL
 export PERL PYTHON PYTHON2 PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
 export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE
 

arch/x86/boot/compressed/Makefile

@@ -103,7 +103,7 @@ vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o
 quiet_cmd_check_data_rel = DATAREL $@
 define cmd_check_data_rel
 	for obj in $(filter %.o,$^); do \
-		${CROSS_COMPILE}readelf -S $$obj | grep -qF .rel.local && { \
+		$(READELF) -S $$obj | grep -qF .rel.local && { \
 			echo "error: $$obj has data relocations!" >&2; \
 			exit 1; \
 		} || true; \

scripts/kallsyms.c

@@ -310,6 +310,15 @@ static void output_label(const char *label)
 	printf("%s:\n", label);
 }
 
+/* Provide proper symbols relocatability by their '_text' relativeness. */
+static void output_address(unsigned long long addr)
+{
+	if (_text <= addr)
+		printf("\tPTR\t_text + %#llx\n", addr - _text);
+	else
+		printf("\tPTR\t_text - %#llx\n", _text - addr);
+}
+
 /* uncompress a compressed symbol. When this function is called, the best table
  * might still be compressed itself, so the function needs to be recursive */
 static int expand_symbol(const unsigned char *data, int len, char *result)
@@ -360,26 +369,20 @@ static void write_src(void)
 
 	printf("\t.section .rodata, \"a\"\n");
 
-	/* Provide proper symbols relocatability by their relativeness
-	 * to a fixed anchor point in the runtime image, either '_text'
-	 * for absolute address tables, in which case the linker will
-	 * emit the final addresses at build time. Otherwise, use the
-	 * offset relative to the lowest value encountered of all relative
-	 * symbols, and emit non-relocatable fixed offsets that will be fixed
-	 * up at runtime.
-	 *
-	 * The symbol names cannot be used to construct normal symbol
-	 * references as the list of symbols contains symbols that are
-	 * declared static and are private to their .o files.  This prevents
-	 * .tmp_kallsyms.o or any other object from referencing them.
-	 */
 	if (!base_relative)
 		output_label("kallsyms_addresses");
 	else
 		output_label("kallsyms_offsets");
 
 	for (i = 0; i < table_cnt; i++) {
 		if (base_relative) {
+			/*
+			 * Use the offset relative to the lowest value
+			 * encountered of all relative symbols, and emit
+			 * non-relocatable fixed offsets that will be fixed
+			 * up at runtime.
+			 */
+
 			long long offset;
 			int overflow;
 
@@ -402,12 +405,7 @@ static void write_src(void)
 			}
 			printf("\t.long\t%#x\n", (int)offset);
 		} else if (!symbol_absolute(&table[i])) {
-			if (_text <= table[i].addr)
-				printf("\tPTR\t_text + %#llx\n",
-					table[i].addr - _text);
-			else
-				printf("\tPTR\t_text - %#llx\n",
-					_text - table[i].addr);
+			output_address(table[i].addr);
 		} else {
 			printf("\tPTR\t%#llx\n", table[i].addr);
 		}
@@ -416,7 +414,7 @@ static void write_src(void)
 
 	if (base_relative) {
 		output_label("kallsyms_relative_base");
-		printf("\tPTR\t_text - %#llx\n", _text - relative_base);
+		output_address(relative_base);
 		printf("\n");
 	}
 

scripts/kconfig/expr.c

@@ -254,6 +254,13 @@ static int expr_eq(struct expr *e1, struct expr *e2)
 {
 	int res, old_count;
 
+	/*
+	 * A NULL expr is taken to be yes, but there's also a different way to
+	 * represent yes. expr_is_yes() checks for either representation.
+	 */
+	if (!e1 || !e2)
+		return expr_is_yes(e1) && expr_is_yes(e2);
+
 	if (e1->type != e2->type)
 		return 0;
 	switch (e1->type) {

scripts/mkcompile_h

@@ -55,12 +55,10 @@ CONFIG_FLAGS=""
 if [ -n "$SMP" ] ; then CONFIG_FLAGS="SMP"; fi
 if [ -n "$PREEMPT" ] ; then CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT"; fi
 if [ -n "$PREEMPT_RT" ] ; then CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT_RT"; fi
-UTS_VERSION="$UTS_VERSION $CONFIG_FLAGS $TIMESTAMP"
 
 # Truncate to maximum length
-
 UTS_LEN=64
-UTS_TRUNCATE="cut -b -$UTS_LEN"
+UTS_VERSION="$(echo $UTS_VERSION $CONFIG_FLAGS $TIMESTAMP | cut -b -$UTS_LEN)"
 
 # Generate a temporary compile.h
 
@@ -69,10 +67,10 @@ UTS_TRUNCATE="cut -b -$UTS_LEN"
 
   echo \#define UTS_MACHINE \"$ARCH\"
 
-  echo \#define UTS_VERSION \"`echo $UTS_VERSION | $UTS_TRUNCATE`\"
+  echo \#define UTS_VERSION \"$UTS_VERSION\"
 
-  echo \#define LINUX_COMPILE_BY \"`echo $LINUX_COMPILE_BY | $UTS_TRUNCATE`\"
-  echo \#define LINUX_COMPILE_HOST \"`echo $LINUX_COMPILE_HOST | $UTS_TRUNCATE`\"
+  printf '#define LINUX_COMPILE_BY "%s"\n' "$LINUX_COMPILE_BY"
+  echo \#define LINUX_COMPILE_HOST \"$LINUX_COMPILE_HOST\"
 
   echo \#define LINUX_COMPILER \"`$CC -v 2>&1 | grep ' version ' | sed 's/[[:space:]]*$//'`\"
 } > .tmpcompile

scripts/package/mkdebian

@@ -174,7 +174,7 @@ Source: $sourcename
 Section: kernel
 Priority: optional
 Maintainer: $maintainer
-Build-Depends: bc, kmod, cpio, bison, flex | flex:native $extra_build_depends
+Build-Depends: bc, rsync, kmod, cpio, bison, flex | flex:native $extra_build_depends
 Homepage: http://www.kernel.org/
 
 Package: $packagename

usr/include/Makefile

@@ -91,7 +91,7 @@ endif
 # asm-generic/*.h is used by asm/*.h, and should not be included directly
 header-test- += asm-generic/%
 
-extra-y := $(patsubst $(obj)/%.h,%.hdrtest, $(shell find $(obj) -name '*.h'))
+extra-y := $(patsubst $(obj)/%.h,%.hdrtest, $(shell find $(obj) -name '*.h' 2>/dev/null))
 
 quiet_cmd_hdrtest = HDRTEST $<
       cmd_hdrtest = \