Merge tag 'hardening-v6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:

 - lkdtm/bugs: add test for hung smp_call_function_single() (Mark
   Rutland)

 - gcc-plugins: Remove duplicate included header file stringpool.h
   (Thorsten Blum)

 - ARM: Remove address checking for MMUless devices (Yanjun Yang)

 - randomize_kstack: Clean up per-arch entropy and codegen

 - KCFI: Make FineIBT mode Kconfig selectable

 - fortify: Do not special-case 0-sized destinations

* tag 'hardening-v6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  randomize_kstack: Improve stack alignment codegen
  ARM: Remove address checking for MMUless devices
  gcc-plugins: Remove duplicate included header file stringpool.h
  randomize_kstack: Remove non-functional per-arch entropy filtering
  fortify: Do not special-case 0-sized destinations
  x86/alternatives: Make FineIBT mode Kconfig selectable
  lkdtm/bugs: add test for hung smp_call_function_single()

4 files changed, 16 insertions, 7 deletions

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 67c425341a95..ab01b51de559 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -25,6 +25,8 @@
 
 #include "fault.h"
 
+#ifdef CONFIG_MMU
+
 bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
 {
 	unsigned long addr = (unsigned long)unsafe_src;
@@ -32,8 +34,6 @@ bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
 	return addr >= TASK_SIZE && ULONG_MAX - addr >= size;
 }
 
-#ifdef CONFIG_MMU
-
 /*
  * This is useful to dump out the page tables associated with
  * 'addr' in mm 'mm'.
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9778234cf111..7cd41bbaf875 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2414,6 +2414,15 @@ config STRICT_SIGALTSTACK_SIZE
 
 	  Say 'N' unless you want to really enforce this check.
 
+config CFI_AUTO_DEFAULT
+	bool "Attempt to use FineIBT by default at boot time"
+	depends on FINEIBT
+	default y
+	help
+	  Attempt to use FineIBT by default at boot time. If enabled,
+	  this is the same as booting with "cfi=auto". If disabled,
+	  this is the same as booting with "cfi=kcfi".
+
 source "kernel/livepatch/Kconfig"
 
 endmenu
diff --git a/arch/x86/include/asm/cfi.h b/arch/x86/include/asm/cfi.h
index 7cd752557905..31d19c815f99 100644
--- a/arch/x86/include/asm/cfi.h
+++ b/arch/x86/include/asm/cfi.h
@@ -93,7 +93,7 @@
  *
  */
 enum cfi_mode {
-	CFI_DEFAULT,	/* FineIBT if hardware has IBT, otherwise kCFI */
+	CFI_AUTO,	/* FineIBT if hardware has IBT, otherwise kCFI */
 	CFI_OFF,	/* Taditional / IBT depending on .config */
 	CFI_KCFI,	/* Optionally CALL_PADDING, IBT, RETPOLINE */
 	CFI_FINEIBT,	/* see arch/x86/kernel/alternative.c */
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 333b16181357..d17518ca19b8 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -901,8 +901,8 @@ void __init_or_module apply_seal_endbr(s32 *start, s32 *end) { }
 
 #endif /* CONFIG_X86_KERNEL_IBT */
 
-#ifdef CONFIG_FINEIBT
-#define __CFI_DEFAULT	CFI_DEFAULT
+#ifdef CONFIG_CFI_AUTO_DEFAULT
+#define __CFI_DEFAULT	CFI_AUTO
 #elif defined(CONFIG_CFI_CLANG)
 #define __CFI_DEFAULT	CFI_KCFI
 #else
@@ -1010,7 +1010,7 @@ static __init int cfi_parse_cmdline(char *str)
 		}
 
 		if (!strcmp(str, "auto")) {
-			cfi_mode = CFI_DEFAULT;
+			cfi_mode = CFI_AUTO;
 		} else if (!strcmp(str, "off")) {
 			cfi_mode = CFI_OFF;
 			cfi_rand = false;
@@ -1270,7 +1270,7 @@ static void __apply_fineibt(s32 *start_retpoline, s32 *end_retpoline,
 		      "FineIBT preamble wrong size: %ld", fineibt_preamble_size))
 		return;
 
-	if (cfi_mode == CFI_DEFAULT) {
+	if (cfi_mode == CFI_AUTO) {
 		cfi_mode = CFI_KCFI;
 		if (HAS_KERNEL_IBT && cpu_feature_enabled(X86_FEATURE_IBT))
 			cfi_mode = CFI_FINEIBT;