From nobody Fri Oct 3 07:39:28 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F2C352253E1; Thu, 4 Sep 2025 03:46:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756957617; cv=none; b=j8P6CAlR8v6NTVVeFivscKRgv/QDT92R7yl2NIJD0zllGDNcWbIV8HDUptkCOIL/BseSLS85ujbkAxIyqpsX/lzItc9867UbPgzw6ESXqQzQq9TXsQhuM6sA8OUmLU7KFF8vOsgvLo9v86pMS08gW92te4pSWnHh6M2SaxByQ2U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756957617; c=relaxed/simple; bh=/OwwI41G7+Tx15l2gGzfUnj2QKLIC0KZTQah1RCXchQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=LQsO7uECYGyFXWPlBQI+zc3icyEe/noXqAJuBMfYsC2Wpljh7d4CE2Lk+z/RqAbeFpsLjYJnZLIg2WAiDowe8+MnJfv2UJzHwjFtx0FKzreYl4GqpYAuZppdQzXmEcVqG2bf3wGab5F2amgB8kB361XFRHzwAAjs+FoiTHOdMEE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MylokCOL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MylokCOL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 793B1C4CEF1; Thu, 4 Sep 2025 03:46:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756957616; bh=/OwwI41G7+Tx15l2gGzfUnj2QKLIC0KZTQah1RCXchQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MylokCOLrkzILw21dOISnvzdCnC5ic0BWGjbhj8ixodadygjQteMcRPhO8kWoA6oM 6GGtXCwET8NKOjZBkeQkGxSP6IXjq1MixvApdHAq/v86BP1hkZUR0qeSbyCvE/ddJl nx+Fz20MrH6eKgXxDA9x1tjRS2xT7WVy2EwOeLedKKzRsKXAYtXbuC/jxFE1u9qpvj t+BktwnoIU7pmPMUzvEyGkybllUiJoG+Zmx/52PVWdBYgjjJZ+ZCXE/AeZwsmBRq9p GkGB5PYo+MShdaIc3qEtNQ8SgapozpZ2b0dMj9QaWmUCcQ6kOEbIQKgteHkRbDJXVx uMZB0k8YpJ8EA== From: Kees Cook To: Peter Zijlstra Cc: Kees Cook , Jonathan Corbet , "Paul E. McKenney" , Randy Dunlap , linux-doc@vger.kernel.org, Nathan Chancellor , Vegard Nossum , Miguel Ojeda , Linus Walleij , Jeff Johnson , David Woodhouse , "Russell King (Oracle)" , Nick Desaulniers , Bill Wendling , Justin Stitt , Marco Elver , Przemek Kitszel , Ramon de C Valle , Nicolas Schier , Masahiro Yamada , Arnd Bergmann , Krzysztof Kozlowski , Sami Tolvanen , Mark Rutland , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-kbuild@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2 3/9] x86/cfi: Document the "cfi=" bootparam options Date: Wed, 3 Sep 2025 20:46:42 -0700 Message-Id: <20250904034656.3670313-3-kees@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250904033217.it.414-kees@kernel.org> References: <20250904033217.it.414-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1713; i=kees@kernel.org; h=from:subject; bh=/OwwI41G7+Tx15l2gGzfUnj2QKLIC0KZTQah1RCXchQ=; b=owGbwMvMwCVmps19z/KJym7G02pJDBk7OYslK7sPyK8r/yYYUab2O3f2jr2JoYvqn009+jJ05 /mHQR/4OkpZGMS4GGTFFFmC7NzjXDzetoe7z1WEmcPKBDKEgYtTACbyXpnhf5wCS2RwSuTUzIet 4T/Zd6uV+UjqykrE3eZIe6IgUGClyshwNDmyTXFnvZOH35caoe/G/HMao/tC9mbahsZZqp28lcQ NAA== X-Developer-Key: i=kees@kernel.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The kernel-parameters.txt didn't have a section for the cfi=3D options. Add it. Signed-off-by: Kees Cook Reviewed-by: Nathan Chancellor --- Cc: Jonathan Corbet Cc: "Paul E. McKenney" Cc: Randy Dunlap Cc: Peter Zijlstra Cc: --- Documentation/admin-guide/kernel-parameters.txt | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index 747a55abf494..8bbffbb334ab 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -608,6 +608,23 @@ ccw_timeout_log [S390] See Documentation/arch/s390/common_io.rst for details. =20 + cfi=3D [X86-64] Set Control Flow Integrity checking features + when CONFIG_FINEIBT is enabled. + Format: feature[,feature...] + Default: auto + + auto: Use FineIBT if IBT available, otherwise kCFI. + Under FineIBT, enable "paranoid" mode when + FRED is not available. + off: Turn off CFI checking. + kcfi: Use kCFI (disable FineIBT). + fineibt: Use FineIBT (even if IBT not available). + norand: Do not re-randomize CFI hashes. + paranoid: Add caller hash checking under FineIBT. + bhi: Enable register poisoning to stop speculation + across FineIBT. (Disabled by default.) + warn: Do not enforce CFI checking: warn only. + cgroup_disable=3D [KNL] Disable a particular controller or optional featu= re Format: {name of the controller(s) or feature(s) to disable} The effects of cgroup_disable=3Dfoo are: --=20 2.34.1