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
  ...

include/linux/compiler_types.h

@@ -130,10 +130,6 @@ struct ftrace_likely_data {
 
 /*
  * Force always-inline if the user requests it so via the .config.
- * GCC does not warn about unused static inline functions for
- * -Wunused-function.  This turns out to avoid the need for complex #ifdef
- * directives.  Suppress the warning in clang as well by using "unused"
- * function attribute, which is redundant but not harmful for gcc.
  * Prefer gnu_inline, so that extern inline functions do not emit an
  * externally visible function. This makes extern inline behave as per gnu89
  * semantics rather than c99. This prevents multiple symbol definition errors
@@ -144,15 +140,27 @@ struct ftrace_likely_data {
  */
 #if !defined(CONFIG_OPTIMIZE_INLINING)
 #define inline inline __attribute__((__always_inline__)) __gnu_inline \
-	__maybe_unused notrace
+	__inline_maybe_unused notrace
 #else
 #define inline inline                                    __gnu_inline \
-	__maybe_unused notrace
+	__inline_maybe_unused notrace
 #endif
 
 #define __inline__ inline
 #define __inline   inline
 
+/*
+ * GCC does not warn about unused static inline functions for -Wunused-function.
+ * Suppress the warning in clang as well by using __maybe_unused, but enable it
+ * for W=1 build. This will allow clang to find unused functions. Remove the
+ * __inline_maybe_unused entirely after fixing most of -Wunused-function warnings.
+ */
+#ifdef KBUILD_EXTRA_WARN1
+#define __inline_maybe_unused
+#else
+#define __inline_maybe_unused __maybe_unused
+#endif
+
 /*
  * Rather then using noinline to prevent stack consumption, use
  * noinline_for_stack instead.  For documentation reasons.

include/linux/export.h

@@ -18,9 +18,6 @@ extern struct module __this_module;
 #define THIS_MODULE ((struct module *)0)
 #endif
 
-#ifdef CONFIG_MODULES
-
-#if defined(__KERNEL__) && !defined(__GENKSYMS__)
 #ifdef CONFIG_MODVERSIONS
 /* Mark the CRC weak since genksyms apparently decides not to
  * generate a checksums for some symbols */
@@ -74,6 +71,12 @@ struct kernel_symbol {
 };
 #endif
 
+#ifdef __GENKSYMS__
+
+#define ___EXPORT_SYMBOL(sym, sec)	__GENKSYMS_EXPORT_SYMBOL(sym)
+
+#else
+
 /* For every exported symbol, place a struct in the __ksymtab section */
 #define ___EXPORT_SYMBOL(sym, sec)					\
 	extern typeof(sym) sym;						\
@@ -83,7 +86,9 @@ struct kernel_symbol {
 	= #sym;								\
 	__KSYMTAB_ENTRY(sym, sec)
 
-#if defined(__DISABLE_EXPORTS)
+#endif
+
+#if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS)
 
 /*
  * Allow symbol exports to be disabled completely so that C code may
@@ -117,37 +122,22 @@ struct kernel_symbol {
 #define __cond_export_sym_0(sym, sec) /* nothing */
 
 #else
-#define __EXPORT_SYMBOL ___EXPORT_SYMBOL
-#endif
 
-#define EXPORT_SYMBOL(sym)					\
-	__EXPORT_SYMBOL(sym, "")
+#define __EXPORT_SYMBOL(sym, sec)	___EXPORT_SYMBOL(sym, sec)
 
-#define EXPORT_SYMBOL_GPL(sym)					\
-	__EXPORT_SYMBOL(sym, "_gpl")
-
-#define EXPORT_SYMBOL_GPL_FUTURE(sym)				\
-	__EXPORT_SYMBOL(sym, "_gpl_future")
+#endif /* CONFIG_MODULES */
 
+#define EXPORT_SYMBOL(sym)		__EXPORT_SYMBOL(sym, "")
+#define EXPORT_SYMBOL_GPL(sym)		__EXPORT_SYMBOL(sym, "_gpl")
+#define EXPORT_SYMBOL_GPL_FUTURE(sym)	__EXPORT_SYMBOL(sym, "_gpl_future")
 #ifdef CONFIG_UNUSED_SYMBOLS
-#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
-#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
+#define EXPORT_UNUSED_SYMBOL(sym)	__EXPORT_SYMBOL(sym, "_unused")
+#define EXPORT_UNUSED_SYMBOL_GPL(sym)	__EXPORT_SYMBOL(sym, "_unused_gpl")
 #else
 #define EXPORT_UNUSED_SYMBOL(sym)
 #define EXPORT_UNUSED_SYMBOL_GPL(sym)
 #endif
 
-#endif	/* __GENKSYMS__ */
-
-#else /* !CONFIG_MODULES... */
-
-#define EXPORT_SYMBOL(sym)
-#define EXPORT_SYMBOL_GPL(sym)
-#define EXPORT_SYMBOL_GPL_FUTURE(sym)
-#define EXPORT_UNUSED_SYMBOL(sym)
-#define EXPORT_UNUSED_SYMBOL_GPL(sym)
-
-#endif /* CONFIG_MODULES */
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _LINUX_EXPORT_H */

include/linux/vermagic.h

@@ -9,6 +9,8 @@
 #endif
 #ifdef CONFIG_PREEMPT
 #define MODULE_VERMAGIC_PREEMPT "preempt "
+#elif defined(CONFIG_PREEMPT_RT)
+#define MODULE_VERMAGIC_PREEMPT "preempt_rt "
 #else
 #define MODULE_VERMAGIC_PREEMPT ""
 #endif