Merge tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/…

…git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - add modpost warn exported symbols marked as 'static' because 'static'
   and EXPORT_SYMBOL is an odd combination

 - break the build early if gold linker is used

 - optimize the Bison rule to produce .c and .h files by a single
   pattern rule

 - handle PREEMPT_RT in the module vermagic and UTS_VERSION

 - warn CONFIG options leaked to the user-space except existing ones

 - make single targets work properly

 - rebuild modules when module linker scripts are updated

 - split the module final link stage into scripts/Makefile.modfinal

 - fix the missed error code in merge_config.sh

 - improve the error message displayed on the attempt of the O= build in
   unclean source tree

 - remove 'clean-dirs' syntax

 - disable -Wimplicit-fallthrough warning for Clang

 - add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC

 - remove ARCH_{CPP,A,C}FLAGS variables

 - add $(BASH) to run bash scripts

 - change *CFLAGS_<basetarget>.o to take the relative path to $(obj)
   instead of the basename

 - stop suppressing Clang's -Wunused-function warnings when W=1

 - fix linux/export.h to avoid genksyms calculating CRC of trimmed
   exported symbols

 - misc cleanups

* tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (63 commits)
  genksyms: convert to SPDX License Identifier for lex.l and parse.y
  modpost: use __section in the output to *.mod.c
  modpost: use MODULE_INFO() for __module_depends
  export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols
  export.h: remove defined(__KERNEL__), which is no longer needed
  kbuild: allow Clang to find unused static inline functions for W=1 build
  kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARN
  kbuild: refactor scripts/Makefile.extrawarn
  merge_config.sh: ignore unwanted grep errors
  kbuild: change *FLAGS_<basetarget>.o to take the path relative to $(obj)
  modpost: add NOFAIL to strndup
  modpost: add guid_t type definition
  kbuild: add $(BASH) to run scripts with bash-extension
  kbuild: remove ARCH_{CPP,A,C}FLAGS
  kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
  kbuild: Do not enable -Wimplicit-fallthrough for clang for now
  kbuild: clean up subdir-ymn calculation in Makefile.clean
  kbuild: remove unneeded '+' marker from cmd_clean
  kbuild: remove clean-dirs syntax
  kbuild: check clean srctree even earlier
  ...

.gitignore

@@ -34,7 +34,6 @@
 *.mod.c
 *.o
 *.o.*
-*.order
 *.patch
 *.s
 *.so
@@ -46,6 +45,7 @@
 *.xz
 Module.symvers
 modules.builtin
+modules.order
 
 #
 # Top-level generic files

Documentation/kbuild/kbuild.rst

@@ -105,6 +105,15 @@ The output directory can also be specified using "O=...".
 
 Setting "O=..." takes precedence over KBUILD_OUTPUT.
 
+KBUILD_EXTRA_WARN
+-----------------
+Specify the extra build checks. The same value can be assigned by passing
+W=... from the command line.
+
+See `make help` for the list of the supported values.
+
+Setting "W=..." takes precedence over KBUILD_EXTRA_WARN.
+
 KBUILD_DEBARCH
 --------------
 For the deb-pkg target, allows overriding the normal heuristics deployed by
@@ -241,11 +250,6 @@ To get all available archs you can also specify all. E.g.::
 
     $ make ALLSOURCE_ARCHS=all tags
 
-KBUILD_ENABLE_EXTRA_GCC_CHECKS
-------------------------------
-If enabled over the make command line with "W=1", it turns on additional
-gcc -W... options for more extensive build-time checking.
-
 KBUILD_BUILD_TIMESTAMP
 ----------------------
 Setting this to a date string overrides the timestamp used in the
@@ -258,17 +262,3 @@ KBUILD_BUILD_USER, KBUILD_BUILD_HOST
 These two variables allow to override the user@host string displayed during
 boot and in /proc/version. The default value is the output of the commands
 whoami and host, respectively.
-
-KBUILD_LDS
-----------
-The linker script with full path. Assigned by the top-level Makefile.
-
-KBUILD_VMLINUX_OBJS
--------------------
-All object files for vmlinux. They are linked to vmlinux in the same
-order as listed in KBUILD_VMLINUX_OBJS.
-
-KBUILD_VMLINUX_LIBS
--------------------
-All .a "lib" files for vmlinux. KBUILD_VMLINUX_OBJS and KBUILD_VMLINUX_LIBS
-together specify all the object files used to link vmlinux.

Documentation/kbuild/makefiles.rst

@@ -471,21 +471,6 @@ more details, with real examples.
 	The second argument is optional, and if supplied will be used
 	if first argument is not supported.
 
-    cc-ldoption
-	cc-ldoption is used to check if $(CC) when used to link object files
-	supports the given option.  An optional second option may be
-	specified if first option are not supported.
-
-	Example::
-
-		#arch/x86/kernel/Makefile
-		vsyscall-flags += $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
-
-	In the above example, vsyscall-flags will be assigned the option
-	-Wl$(comma)--hash-style=sysv if it is supported by $(CC).
-	The second argument is optional, and if supplied will be used
-	if first argument is not supported.
-
     as-instr
 	as-instr checks if the assembler reports a specific instruction
 	and then outputs either option1 or option2
@@ -765,7 +750,8 @@ Files matching the patterns "*.[oas]", "*.ko", plus some additional files
 generated by kbuild are deleted all over the kernel src tree when
 "make clean" is executed.
 
-Additional files can be specified in kbuild makefiles by use of $(clean-files).
+Additional files or directories can be specified in kbuild makefiles by use of
+$(clean-files).
 
 	Example::
 
@@ -776,23 +762,8 @@ When executing "make clean", the file "crc32table.h" will be deleted.
 Kbuild will assume files to be in the same relative directory as the
 Makefile, except if prefixed with $(objtree).
 
-To delete a directory hierarchy use:
-
-	Example::
-
-		#scripts/package/Makefile
-		clean-dirs := $(objtree)/debian/
-
-This will delete the directory debian in the toplevel directory, including all
-subdirectories.
-
-To exclude certain files from make clean, use the $(no-clean-files) variable.
-This is only a special case used in the top level Kbuild file:
-
-	Example::
-
-		#Kbuild
-		no-clean-files := $(bounds-file) $(offsets-file)
+To exclude certain files or directories from make clean, use the
+$(no-clean-files) variable.
 
 Usually kbuild descends down in subdirectories due to "obj-* := dir/",
 but in the architecture makefiles where the kbuild infrastructure
@@ -988,13 +959,25 @@ When kbuild executes, the following steps are followed (roughly):
 	$(KBUILD_ARFLAGS) set by the top level Makefile to "D" (deterministic
 	mode) if this option is supported by $(AR).
 
-    ARCH_CPPFLAGS, ARCH_AFLAGS, ARCH_CFLAGS   Overrides the kbuild defaults
+    KBUILD_LDS
+
+	The linker script with full path. Assigned by the top-level Makefile.
+
+    KBUILD_LDS_MODULE
+
+	The module linker script with full path. Assigned by the top-level
+	Makefile and additionally by the arch Makefile.
+
+    KBUILD_VMLINUX_OBJS
+
+	All object files for vmlinux. They are linked to vmlinux in the same
+	order as listed in KBUILD_VMLINUX_OBJS.
 
-	These variables are appended to the KBUILD_CPPFLAGS,
-	KBUILD_AFLAGS, and KBUILD_CFLAGS, respectively, after the
-	top-level Makefile has set any other flags. This provides a
-	means for an architecture to override the defaults.
+    KBUILD_VMLINUX_LIBS
 
+	All .a "lib" files for vmlinux. KBUILD_VMLINUX_OBJS and
+	KBUILD_VMLINUX_LIBS together specify all the object files used to
+	link vmlinux.
 
 6.2 Add prerequisites to archheaders
 ------------------------------------
@@ -1139,19 +1122,19 @@ When kbuild executes, the following steps are followed (roughly):
 
     header-test-y
 
-	header-test-y specifies headers (*.h) in the current directory that
+	header-test-y specifies headers (`*.h`) in the current directory that
 	should be compile tested to ensure they are self-contained,
 	i.e. compilable as standalone units. If CONFIG_HEADER_TEST is enabled,
 	this builds them as part of extra-y.
 
     header-test-pattern-y
 
 	This works as a weaker version of header-test-y, and accepts wildcard
-	patterns. The typical usage is:
+	patterns. The typical usage is::
 
-		  header-test-pattern-y += *.h
+		header-test-pattern-y += *.h
 
-	This specifies all the files that matches to '*.h' in the current
+	This specifies all the files that matches to `*.h` in the current
 	directory, but the files in 'header-test-' are excluded.
 
 6.7 Commands useful for building a boot image

Kbuild

@@ -18,8 +18,6 @@ $(bounds-file): kernel/bounds.s FORCE
 
 timeconst-file := include/generated/timeconst.h
 
-targets += $(timeconst-file)
-
 filechk_gentimeconst = echo $(CONFIG_HZ) | bc -q $<
 
 $(timeconst-file): kernel/time/timeconst.bc FORCE
@@ -42,7 +40,6 @@ $(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
 # Check for missing system calls
 
 always += missing-syscalls
-targets += missing-syscalls
 
 quiet_cmd_syscalls = CALL    $<
       cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)
@@ -54,13 +51,9 @@ missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
 # Check atomic headers are up-to-date
 
 always += old-atomics
-targets += old-atomics
 
 quiet_cmd_atomics = CALL    $<
       cmd_atomics = $(CONFIG_SHELL) $<
 
 old-atomics: scripts/atomic/check-atomics.sh FORCE
 	$(call cmd,atomics)
-
-# Keep these three files during make clean
-no-clean-files := $(bounds-file) $(offsets-file) $(timeconst-file)