linux-kernel - [PATCH v2 4/9] x86/cfi: Standardize on common "CFI:" prefix for CFI reports

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Message-Id: <20250904034656.3670313-4-kees@kernel.org>
Date: Wed,  3 Sep 2025 20:46:43 -0700
From: Kees Cook <kees@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Kees Cook <kees@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Vegard Nossum <vegard.nossum@...cle.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Jeff Johnson <jeff.johnson@....qualcomm.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	David Woodhouse <dwmw2@...radead.org>,
	"Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Marco Elver <elver@...gle.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Ramon de C Valle <rcvalle@...gle.com>,
	Jonathan Corbet <corbet@....net>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Nicolas Schier <nicolas.schier@...ux.dev>,
	Masahiro Yamada <masahiroy@...nel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Mark Rutland <mark.rutland@....com>,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev,
	linux-doc@...r.kernel.org,
	linux-kbuild@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	x86@...nel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH v2 4/9] x86/cfi: Standardize on common "CFI:" prefix for CFI reports

Use a regular "CFI:" prefix for CFI reports during alternatives setup,
including reporting when nothing has happened (i.e. CONFIG_FINEIBT=n).

Signed-off-by: Kees Cook <kees@...nel.org>
---
Cc: Peter Zijlstra <peterz@...radead.org>
---
 arch/x86/kernel/alternative.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 7bde68247b5f..d8f4ac95b4df 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1266,26 +1266,26 @@ static __init int cfi_parse_cmdline(char *str)
 		} else if (!strcmp(str, "norand")) {
 			cfi_rand = false;
 		} else if (!strcmp(str, "warn")) {
-			pr_alert("CFI mismatch non-fatal!\n");
+			pr_alert("CFI: mismatch non-fatal!\n");
 			cfi_warn = true;
 		} else if (!strcmp(str, "paranoid")) {
 			if (cfi_mode == CFI_FINEIBT) {
 				cfi_paranoid = true;
 			} else {
-				pr_err("Ignoring paranoid; depends on fineibt.\n");
+				pr_err("CFI: ignoring paranoid; depends on fineibt.\n");
 			}
 		} else if (!strcmp(str, "bhi")) {
 #ifdef CONFIG_FINEIBT_BHI
 			if (cfi_mode == CFI_FINEIBT) {
 				cfi_bhi = true;
 			} else {
-				pr_err("Ignoring bhi; depends on fineibt.\n");
+				pr_err("CFI: ignoring bhi; depends on fineibt.\n");
 			}
 #else
-			pr_err("Ignoring bhi; depends on FINEIBT_BHI=y.\n");
+			pr_err("CFI: ignoring bhi; depends on FINEIBT_BHI=y.\n");
 #endif
 		} else {
-			pr_err("Ignoring unknown cfi option (%s).", str);
+			pr_err("CFI: Ignoring unknown option (%s).", str);
 		}
 
 		str = next;
@@ -1757,7 +1757,7 @@ static void __apply_fineibt(s32 *start_retpoline, s32 *end_retpoline,
 	switch (cfi_mode) {
 	case CFI_OFF:
 		if (builtin)
-			pr_info("Disabling CFI\n");
+			pr_info("CFI: disabled\n");
 		return;
 
 	case CFI_KCFI:
@@ -1766,7 +1766,8 @@ static void __apply_fineibt(s32 *start_retpoline, s32 *end_retpoline,
 			goto err;
 
 		if (builtin)
-			pr_info("Using kCFI\n");
+			pr_info("CFI: Using %sretpoline kCFI\n",
+				cfi_rand ? "rehashed " : "");
 		return;
 
 	case CFI_FINEIBT:
@@ -2005,6 +2006,8 @@ bool decode_fineibt_insn(struct pt_regs *regs, unsigned long *target, u32 *type)
 static void __apply_fineibt(s32 *start_retpoline, s32 *end_retpoline,
 			    s32 *start_cfi, s32 *end_cfi, bool builtin)
 {
+	if (IS_ENABLED(CONFIG_CFI) && builtin)
+		pr_info("CFI: Using standard kCFI\n");
 }
 
 #ifdef CONFIG_X86_KERNEL_IBT
-- 
2.34.1