Merge tag 'hardening-v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull compiler hardening updates from Kees Cook:
 "These are various compiler-related hardening feature updates. Notable
  is the addition of an explicit limited rationale for, and deprecation
  schedule of, gcc-plugins.

  gcc-plugins:
   - remove support for GCC 4.9 and older (Ard Biesheuvel)
   - remove duplicate include in gcc-common.h (Ye Guojin)
   - Explicitly document purpose and deprecation schedule (Kees Cook)
   - Remove cyc_complexity (Kees Cook)

  instrumentation:
   - Avoid harmless Clang option under CONFIG_INIT_STACK_ALL_ZERO (Kees Cook)

  Clang LTO:
   - kallsyms: strip LTO suffixes from static functions (Nick Desaulniers)"

* tag 'hardening-v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  gcc-plugins: remove duplicate include in gcc-common.h
  gcc-plugins: Remove cyc_complexity
  gcc-plugins: Explicitly document purpose and deprecation schedule
  kallsyms: strip LTO suffixes from static functions
  gcc-plugins: remove support for GCC 4.9 and older
  hardening: Avoid harmless Clang option under CONFIG_INIT_STACK_ALL_ZERO

security/Kconfig.hardening

@@ -23,13 +23,16 @@ config CC_HAS_AUTO_VAR_INIT_PATTERN
 	def_bool $(cc-option,-ftrivial-auto-var-init=pattern)
 
 config CC_HAS_AUTO_VAR_INIT_ZERO
+	# GCC ignores the -enable flag, so we can test for the feature with
+	# a single invocation using the flag, but drop it as appropriate in
+	# the Makefile, depending on the presence of Clang.
 	def_bool $(cc-option,-ftrivial-auto-var-init=zero -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang)
 
 choice
 	prompt "Initialize kernel stack variables at function entry"
 	default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL if COMPILE_TEST && GCC_PLUGINS
 	default INIT_STACK_ALL_PATTERN if COMPILE_TEST && CC_HAS_AUTO_VAR_INIT_PATTERN
-	default INIT_STACK_ALL_ZERO if CC_HAS_AUTO_VAR_INIT_PATTERN
+	default INIT_STACK_ALL_ZERO if CC_HAS_AUTO_VAR_INIT_ZERO
 	default INIT_STACK_NONE
 	help
 	  This option enables initialization of stack variables at
@@ -53,7 +56,8 @@ choice
 
 	config GCC_PLUGIN_STRUCTLEAK_USER
 		bool "zero-init structs marked for userspace (weak)"
-		depends on GCC_PLUGINS
+		# Plugin can be removed once the kernel only supports GCC 12+
+		depends on GCC_PLUGINS && !CC_HAS_AUTO_VAR_INIT_ZERO
 		select GCC_PLUGIN_STRUCTLEAK
 		help
 		  Zero-initialize any structures on the stack containing
@@ -64,7 +68,8 @@ choice
 
 	config GCC_PLUGIN_STRUCTLEAK_BYREF
 		bool "zero-init structs passed by reference (strong)"
-		depends on GCC_PLUGINS
+		# Plugin can be removed once the kernel only supports GCC 12+
+		depends on GCC_PLUGINS && !CC_HAS_AUTO_VAR_INIT_ZERO
 		depends on !(KASAN && KASAN_STACK)
 		select GCC_PLUGIN_STRUCTLEAK
 		help
@@ -82,7 +87,8 @@ choice
 
 	config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
 		bool "zero-init everything passed by reference (very strong)"
-		depends on GCC_PLUGINS
+		# Plugin can be removed once the kernel only supports GCC 12+
+		depends on GCC_PLUGINS && !CC_HAS_AUTO_VAR_INIT_ZERO
 		depends on !(KASAN && KASAN_STACK)
 		select GCC_PLUGIN_STRUCTLEAK
 		help