Kbuild fixes for v6.0 (3rd)

- Fix build error for the combination of CONFIG_SYSTEM_TRUSTED_KEYRING=y
    and CONFIG_X509_CERTIFICATE_PARSER=m
 
  - Fix CONFIG_DEBUG_INFO_SPLIT to generate debug info for GCC 11+ and Clang 12+
 
  - Revive debug info for assembly files
 
  - Remove unused code
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Merge tag 'kbuild-fixes-v6.0-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Fix build error for the combination of SYSTEM_TRUSTED_KEYRING=y and
   X509_CERTIFICATE_PARSER=m

 - Fix DEBUG_INFO_SPLIT to generate debug info for GCC 11+ and Clang 12+

 - Revive debug info for assembly files

 - Remove unused code

* tag 'kbuild-fixes-v6.0-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  Makefile.debug: re-enable debug info for .S files
  Makefile.debug: set -g unconditional on CONFIG_DEBUG_INFO_SPLIT
  certs: make system keyring depend on built-in x509 parser
  Kconfig: remove unused function 'menu_get_root_menu'
  scripts/clang-tools: remove unused module

certs/Kconfig

@@ -43,7 +43,7 @@ config SYSTEM_TRUSTED_KEYRING
 	bool "Provide system-wide ring of trusted keys"
 	depends on KEYS
 	depends on ASYMMETRIC_KEY_TYPE
-	depends on X509_CERTIFICATE_PARSER
+	depends on X509_CERTIFICATE_PARSER = y
 	help
 	  Provide a system keyring to which trusted keys can be added.  Keys in
 	  the keyring are considered to be trusted.  Keys may be added at will

lib/Kconfig.debug

@@ -264,8 +264,10 @@ config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
 config DEBUG_INFO_DWARF4
 	bool "Generate DWARF Version 4 debuginfo"
 	select DEBUG_INFO
+	depends on !CC_IS_CLANG || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)))
 	help
-	  Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+.
+	  Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
+	  if using clang without clang's integrated assembler, and gdb 7.0+.
 
 	  If you have consumers of DWARF debug info that are not ready for
 	  newer revisions of DWARF, you may wish to choose this or have your

scripts/Makefile.debug

@@ -1,20 +1,19 @@
 DEBUG_CFLAGS	:=
+debug-flags-y	:= -g
 
 ifdef CONFIG_DEBUG_INFO_SPLIT
 DEBUG_CFLAGS	+= -gsplit-dwarf
-else
-DEBUG_CFLAGS	+= -g
 endif
 
-ifndef CONFIG_AS_IS_LLVM
-KBUILD_AFLAGS	+= -Wa,-gdwarf-2
-endif
-
-ifndef CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
-dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4
-dwarf-version-$(CONFIG_DEBUG_INFO_DWARF5) := 5
-DEBUG_CFLAGS	+= -gdwarf-$(dwarf-version-y)
+debug-flags-$(CONFIG_DEBUG_INFO_DWARF4)	+= -gdwarf-4
+debug-flags-$(CONFIG_DEBUG_INFO_DWARF5)	+= -gdwarf-5
+ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_AS_IS_GNU),yy)
+# Clang does not pass -g or -gdwarf-* option down to GAS.
+# Add -Wa, prefix to explicitly specify the flags.
+KBUILD_AFLAGS	+= $(addprefix -Wa$(comma), $(debug-flags-y))
 endif
+DEBUG_CFLAGS	+= $(debug-flags-y)
+KBUILD_AFLAGS	+= $(debug-flags-y)
 
 ifdef CONFIG_DEBUG_INFO_REDUCED
 DEBUG_CFLAGS	+= -fno-var-tracking
@@ -29,5 +28,5 @@ KBUILD_AFLAGS	+= -gz=zlib
 KBUILD_LDFLAGS	+= --compress-debug-sections=zlib
 endif
 
-KBUILD_CFLAGS += $(DEBUG_CFLAGS)
+KBUILD_CFLAGS	+= $(DEBUG_CFLAGS)
 export DEBUG_CFLAGS

scripts/clang-tools/run-clang-tools.py

@@ -12,7 +12,6 @@ compile_commands.json.
 import argparse
 import json
 import multiprocessing
-import os
 import subprocess
 import sys
 

scripts/kconfig/lkc.h

@@ -98,7 +98,6 @@ bool menu_is_empty(struct menu *menu);
 bool menu_is_visible(struct menu *menu);
 bool menu_has_prompt(struct menu *menu);
 const char *menu_get_prompt(struct menu *menu);
-struct menu *menu_get_root_menu(struct menu *menu);
 struct menu *menu_get_parent_menu(struct menu *menu);
 bool menu_has_help(struct menu *menu);
 const char *menu_get_help(struct menu *menu);

scripts/kconfig/menu.c

@@ -661,11 +661,6 @@ const char *menu_get_prompt(struct menu *menu)
 	return NULL;
 }
 
-struct menu *menu_get_root_menu(struct menu *menu)
-{
-	return &rootmenu;
-}
-
 struct menu *menu_get_parent_menu(struct menu *menu)
 {
 	enum prop_type type;