From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f54.google.com (mail-wm1-f54.google.com [209.85.128.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C02517082D for ; Mon, 27 Jul 2026 00:10:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.54 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785111057; cv=none; b=fBKLvOrATXXemFUqNPXZI7xrYigEZ6GcoLwZV6jDf73CT+c/otdCZ7FNAyWKMFcjoxhpco3Eu+tu465/TJ3TuSpSQrrJRm5LzHNzaeG+6Iqttw/GcnAEILWJ8uA3HcoWdH9TrMZ56XzsDKW8iVzejmRLm8hb3zZDYk/Egg1CpLo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785111057; c=relaxed/simple; bh=RM71rEpMshNU/1M43+xs6op/v06TdqK/Y4+1CcbduMo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WYVY+kK2Uu4cOSiiIauarabr9LImhZN2d1q2FN248rQHOirrYcBYjw6Gte9tqyI/Dc6ZYBmvEZJ28sLnRqLAT9uzsvdEik/YklG/LAUBG5pVMIkfA2QkYAJDr1kjd/zBXwqkecGW2dWJbkp901iaGlgDwqUsGNNVe9J9cn9sMpw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=XTxdw02U; arc=none smtp.client-ip=209.85.128.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="XTxdw02U" Received: by mail-wm1-f54.google.com with SMTP id 5b1f17b1804b1-4953de5be0aso14098415e9.0 for ; Sun, 26 Jul 2026 17:10:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1785111054; x=1785715854; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=01dl0IIZWjJRbfIXfFu72Txfn4OJSXE2utImaot0HF4=; b=XTxdw02UmK1nJ5yG6sKLznfb3GIokzTfEvCNcbSom8FkSnb1TJn3MA5FStbh77GLPz RUsUgPbnEMxVyhiign2UMBQmwXX6xLTnzftOukAInJ/c3cIDnDAzuAJoKUJI3AQOhXtK GOvuQ3O389c+I2EFsMTZ10fBCX2yJ42B2qd9bp3YWdHkuKuojqUNS1htJFj+B1+CMPA0 jX5wsV1B8f5lIZAUXdXSsiyZCYuab0kbi4Ye2bGcJNkTFqCJIr6Q90TBo6/e7S3jIiSO DR8Z232XkQjZf0cssiiGXmajtaIEg917dX7A9/zrpdMnvqGTy6E5GLI/0Y0kb3rhusVL +/bw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785111054; x=1785715854; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=01dl0IIZWjJRbfIXfFu72Txfn4OJSXE2utImaot0HF4=; b=ZioPIPEoQMY19KOgUBsA4oH0gb9D2jN0jogLiql756d3e3IBYMav1KAkTiCkqN38je jlnrdHjSsNRGb9PaqHy/dY3+BUWmHe8EwWNtQgH7/cxmJhMUjYaxNqGN6tzW2+xB/Cqu hm8m6KpCoeYm6P0PtMt4xr+ZE4zXTMGOLWI1C479qXVNB+ozhc7PEi6iFpq9DqN+y0uy dF5waPPWMwQwGhueLm6c5rLFwM64RLDZaHbGHAgV84A1Bq/iF6SUuEaHc+zie/3xFUSM Q6qJjs3NwTFnGksfWcXqUQj074NLUeucBBaBuB4UfF3kMB21DDT5ZtbFtrNx6bjEdfPN uOLw== X-Forwarded-Encrypted: i=1; AHgh+RoJ/q9iR3SanP+4JgfoUsuJxQGn9VE9xrwqayjEKvfYNDE7CGyI+EP0avG++7ihZiIKftMMhIIwaXIMkn+zZ7o=@vger.kernel.org X-Gm-Message-State: AOJu0YyojwAl13Ojd7RfIJZWw4ZgMf3fx2hOkC+/7mgv5VeOSTqdpAq9 XXsNmLkNOiifr/lJIdAobAnC8ojF3Io2X2kKrUAJH1EL7YyD9nGTqB6Y X-Gm-Gg: AR+sD10nUyhZBmx927gpnU7x8Yx8zak5XCN2Wd/rLpLxzZI8ahB7NBo60L4dJgmi/An hoMJlULpYStSM5YizxMbl9WOZXM3Jk2Lb1NxGSYK48JlQDwR1w7NMjg/QEFq+XDOaXHNI8Noe6Q B+Mta5yLTEDTpkPQyBmlxQ61lqBIKHP3YznBgxUIPhGV9Ar8Dl8DfZ2T5NEtB20vEB7cIwcERWW 1CmukIwtjVL7BPmSlseGeD5by2QZ+gdCUMrCShUlgmw2t4tFvxN7Ai5RscxUBZ70dlmACGcWyFR MiU+SE9cKxd7lbq3bw8wH7PMx/+UgAmQWJF/SeJYhh9Gb0+iPR3yVjlnEZuuan004PDGrGmCOJE LthDMt1av/8oTZaFiK7qtUZ3Qx1GovzPjNoGLGQ6RsM+awie2XJqe12LhHdGine080jrj59L5Ox 6UpedXIydjfwQ1Bmn7fBHfatRzc536zHComR1sy+JavhoaJE3683tYrnT1HJAoDeSIAITqYXPbw YQU1SJR6J2xxE3DstxtgH0VL6U1+IhoH8DPVhLuYD8= X-Received: by 2002:a05:600c:5492:b0:495:7eab:3abd with SMTP id 5b1f17b1804b1-496b5736f4fmr90983825e9.33.1785111053770; Sun, 26 Jul 2026 17:10:53 -0700 (PDT) Received: from unknown748F3CBA5068 (dynamic-095-114-116-215.95.114.pool.telefonica.de. [95.114.116.215]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-496b4d8d6efsm201357975e9.0.2026.07.26.17.10.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Jul 2026 17:10:52 -0700 (PDT) Date: Mon, 27 Jul 2026 02:10:19 +0200 From: Karl Mehltretter To: Kees Cook Cc: "Russell King (Oracle)" , Linus Walleij , Nathan Chancellor , Sami Tolvanen , Zhen Lei , Arnd Bergmann , =?utf-8?Q?Micha=C5=82?= Pecio , Sebastian Andrzej Siewior , linux-arm-kernel@lists.infradead.org, Russell King , Will Deacon , Mark Rutland , Nick Desaulniers , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-hardening@vger.kernel.org Subject: Re: [PATCH v3] ARM: traps: Implement KCFI trap handler for ARM32 Message-ID: References: <20260715175223.make.153-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260715175223.make.153-kees@kernel.org> On Wed, Jul 15, 2026 at 10:52:27AM +0100, Kees Cook wrote: > +bool arm_cfi_handle_failure(struct pt_regs *regs, enum bug_trap_type type) > +{ > + switch (type) { > + case BUG_TRAP_TYPE_BUG: > + die("Oops - CFI", regs, 0); > + break; > + case BUG_TRAP_TYPE_WARN: > + /* Permissive mode: skip the trapping instruction and continue. */ > + instruction_pointer(regs) += 4; > + break; On Thumb-2, Clang emits a 16-bit BKPT for CFI checks. This skips the following Thumb instruction. Thanks, Karl