From mboxrd@z Thu Jan 1 00:00:00 1970 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 0F3C32AE7F; Wed, 26 Feb 2025 02:56:01 +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=1740538562; cv=none; b=FkLSEwixytbGdl04+DZWLvukcZXwN5jJnoh//ipO0qYtS52aLIPxYT5VvM4KN2T2B/EJQiQ9Xcqta/o0ClLUtZKBQWy6C4ytSG5D28OCEIkOxpedpvreH+b2UE5KnTceyKuyoQIpmz0jwaTzueVOv2b9aw5jpOnEk4x1bgosqEQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740538562; c=relaxed/simple; bh=0QrH2Zd+D5Gfx52FrY2snKkSglnbNxISIbI0Z4qrDzg=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=e53oxT72RkCvS8gx2xyJVqWX2ATTv9X0Um26jf3HxD8irVA/bVphYWMXik/yg/kxVWDmmfmKoiWh6sji7aI9J1RqOak+t9lLZrQ4aSNGNsNPcx6K8p+Zl5UBpZkmz2ZgDtFjRl45LzjXKadNB+HhC7wO7D+JbAfpbSwQDchbhKU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VBw7aDFl; 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="VBw7aDFl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B73FC4CEDD; Wed, 26 Feb 2025 02:56:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740538561; bh=0QrH2Zd+D5Gfx52FrY2snKkSglnbNxISIbI0Z4qrDzg=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=VBw7aDFlLfoIsY52a+6ydG8VMiyc0pTFo66YhF8mJSN06vLgLxpw+8MjxxO32U8an 1VVrOKR6KsB/+Cg2P9rG7pEv5uZlr+Fd9h5vyg/Ngi9ZJtAM4VSMAccJ9UyiIO5ccG 2Vuw5TwryLQCUqT8mD0lOE+k/JiTrRQGoRlrtwUiV8huoFfba81+pZHQXc7quO4ven +Nj7HgYljgiHN6VsdRIL/vaOcBRNopLF37jAvmyM8rBDPLwnd4a3IfhftjLDGdK0mT fSCtWBkDBe/7j8i1XYiPH/lJbWXZ2jMDoD1a6PpJQRgO3Vnzd8LYSyVC3MbnPo/pm8 oE5Lttk8HIBVg== Date: Tue, 25 Feb 2025 18:55:59 -0800 From: Kees Cook To: Andrew Cooper , Rudolf Marek , Jann Horn CC: jmill@asu.edu, joao@overdrivepizza.com, luto@kernel.org, samitolvanen@google.com, "Peter Zijlstra (Intel)" , linux-hardening@vger.kernel.org, lkml , x86 maintainers Subject: Re: [RFC] Circumventing FineIBT Via Entrypoints User-Agent: K-9 Mail for Android In-Reply-To: <8b82b394-3f54-437b-bd3a-7ac0eabda687@citrix.com> References: <1cf8d5a5-bf3e-4667-bc6a-d1b1d662d822@citrix.com> <8b82b394-3f54-437b-bd3a-7ac0eabda687@citrix.com> Message-ID: <7D503F1A-42FD-4585-BB4F-D8D00C303BE5@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On February 25, 2025 1:14:01 PM PST, Andrew Cooper wrote: >Peter Zijlstra has added a FineIBT=3Dparanoid mode which performs the has= h >check ahead of calling the function pointer, which ought to mitigate >this but at even higher overhead=2E Was kCFI vs FineIBT perf ever measured? Is the assumption of higher overhe= ad based on kCFI filling dcache in addition to icache, whereas FineIBT only= fills icache? -Kees --=20 Kees Cook