From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22AEEC2D0EA for ; Wed, 8 Apr 2020 09:58:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED0D320753 for ; Wed, 8 Apr 2020 09:58:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728069AbgDHJ6V (ORCPT ); Wed, 8 Apr 2020 05:58:21 -0400 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:56289 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725932AbgDHJ6U (ORCPT ); Wed, 8 Apr 2020 05:58:20 -0400 X-Originating-IP: 84.210.220.251 Received: from [192.168.1.123] (cm-84.210.220.251.getinternet.no [84.210.220.251]) (Authenticated sender: fredrik@strupe.net) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id EEA966000F; Wed, 8 Apr 2020 09:58:17 +0000 (UTC) Subject: Re: [PATCH] arm64: armv8_deprecated: Fix undef_hook mask for thumb setend To: Catalin Marinas Cc: Suzuki K Poulose , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, will.deacon@arm.com References: <911db2f1-e078-a460-32ee-154a0b4de5d4@strupe.net> <20200407092744.GA2665@gaia> <0d7b582a-1bd0-9db2-2fdc-04fc887f64c6@strupe.net> <20200408090111.GA27331@gaia> From: Fredrik Strupe Message-ID: <9979396e-5d01-0cfe-722f-3a4f6e81dc01@strupe.net> Date: Wed, 8 Apr 2020 11:58:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200408090111.GA27331@gaia> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08.04.2020 11:01, Catalin Marinas wrote: > On Tue, Apr 07, 2020 at 01:18:21PM +0200, Fredrik Strupe wrote: >> (Sorry for duplicate, something went terribly wrong with the formatting of >> the previous email.) > > It's still wrong here with tabs converted to spaces. The patch doesn't > apply. Could you please send the patch separately as a v2? It looks fine > otherwise. > > Thanks. > Alright, let's hope third time's the charm. Fredrik --- For thumb instructions, call_undef_hook() in traps.c first reads a u16, and if the u16 indicates a T32 instruction (u16 >= 0xe800), a second u16 is read, which then makes up the the lower half-word of a T32 instruction. For T16 instructions, the second u16 is not read, which makes the resulting u32 opcode always have the upper half set to 0. However, having the upper half of instr_mask in the undef_hook set to 0 masks out the upper half of all thumb instructions - both T16 and T32. This results in trapped T32 instructions with the lower half-word equal to the T16 encoding of setend (b650) being matched, even though the upper half-word is not 0000 and thus indicates a T32 opcode. An example of such a T32 instruction is eaa0b650, which should raise a SIGILL since T32 instructions with an eaa prefix are unallocated as per Arm ARM, but instead works as a SETEND because the second half-word is set to b650. This patch fixes the issue by extending instr_mask to include the upper u32 half, which will still match T16 instructions where the upper half is 0, but not T32 instructions. Signed-off-by: Fredrik Strupe Cc: Catalin Marinas Cc: Will Deacon Fixes: 2d888f48e056 ("arm64: Emulate SETEND for AArch32 tasks") --- arch/arm64/kernel/armv8_deprecated.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index 9d3442d62..8c06dfee0 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -609,7 +609,7 @@ static struct undef_hook setend_hooks[] = { }, { /* Thumb mode */ - .instr_mask = 0x0000fff7, + .instr_mask = 0xfffffff7, .instr_val = 0x0000b650, .pstate_mask = (PSR_AA32_T_BIT | PSR_AA32_MODE_MASK), .pstate_val = (PSR_AA32_T_BIT | PSR_AA32_MODE_USR), -- 2.20.1