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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5ECB1C433F5 for ; Tue, 12 Apr 2022 17:08:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357990AbiDLRLG (ORCPT ); Tue, 12 Apr 2022 13:11:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350498AbiDLRLD (ORCPT ); Tue, 12 Apr 2022 13:11:03 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id D528060AB7 for ; Tue, 12 Apr 2022 10:08:45 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8CE6A1424; Tue, 12 Apr 2022 10:08:45 -0700 (PDT) Received: from [10.1.196.40] (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 086BD3F5A1; Tue, 12 Apr 2022 10:08:37 -0700 (PDT) Message-ID: <38c6d4b5-a3db-5c3e-02e7-39875edb3476@arm.com> Date: Tue, 12 Apr 2022 18:08:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [RFC PATCH -next V3 4/6] arm64: add copy_{to, from}_user to machine check safe Content-Language: en-GB To: Tong Tiangen , Mark Rutland , James Morse , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Catalin Marinas , Will Deacon , Alexander Viro , x86@kernel.org, "H . Peter Anvin" Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kefeng Wang , Xie XiuQi References: <20220412072552.2526871-1-tongtiangen@huawei.com> <20220412072552.2526871-5-tongtiangen@huawei.com> From: Robin Murphy In-Reply-To: <20220412072552.2526871-5-tongtiangen@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/04/2022 8:25 am, Tong Tiangen wrote: [...] > diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h > index 0557af834e03..bb17f0829042 100644 > --- a/arch/arm64/include/asm/asm-uaccess.h > +++ b/arch/arm64/include/asm/asm-uaccess.h > @@ -92,4 +92,20 @@ alternative_else_nop_endif > > _asm_extable 8888b,\l; > .endm > + > + .macro user_ldp_mc l, reg1, reg2, addr, post_inc > +8888: ldtr \reg1, [\addr]; > +8889: ldtr \reg2, [\addr, #8]; > + add \addr, \addr, \post_inc; > + > + _asm_extable_uaccess_mc 8888b, \l; > + _asm_extable_uaccess_mc 8889b, \l; > + .endm You're replacing the only user of this, so please just s/_asm_extable/_asm_extable_uaccess_mc/ in the existing macro and save the rest of the churn. Furthermore, how come you're not similarly updating user_stp, given that you *are* updating the other stores in copy_to_user? > + > + .macro user_ldst_mc l, inst, reg, addr, post_inc > +8888: \inst \reg, [\addr]; > + add \addr, \addr, \post_inc; > + > + _asm_extable_uaccess_mc 8888b, \l; > + .endm Similarly, I think we can just update user_ldst itself. The two instances that you're not replacing here are bogus anyway, and deserve to be fixed with the patch below first. [...] > @@ -62,7 +63,11 @@ SYM_FUNC_START(__arch_copy_from_user) > ret > > // Exception fixups > -9997: cmp dst, dstin > +9997: mrs esr, esr_el1 // Check exception first > + and esr, esr, #ESR_ELx_FSC > + cmp esr, #ESR_ELx_FSC_EXTABT Should we be checking EC to make sure it's a data abort - and thus FSC is valid - in the first place? I'm a little fuzzy on all the possible paths into fixup_exception(), and it's not entirely obvious whether this is actually safe or not. Thanks, Robin. ----->8----- Subject: [PATCH] arm64: mte: Clean up user tag accessors Invoking user_ldst to explicitly add a post-increment of 0 is silly. Just use a normal USER() annotation and save the redundant instruction. Signed-off-by: Robin Murphy --- arch/arm64/lib/mte.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/lib/mte.S b/arch/arm64/lib/mte.S index 8590af3c98c0..eeb9e45bcce8 100644 --- a/arch/arm64/lib/mte.S +++ b/arch/arm64/lib/mte.S @@ -93,7 +93,7 @@ SYM_FUNC_START(mte_copy_tags_from_user) mov x3, x1 cbz x2, 2f 1: - user_ldst 2f, ldtrb, w4, x1, 0 +USER(2f, ldtrb w4, [x1]) lsl x4, x4, #MTE_TAG_SHIFT stg x4, [x0], #MTE_GRANULE_SIZE add x1, x1, #1 @@ -120,7 +120,7 @@ SYM_FUNC_START(mte_copy_tags_to_user) 1: ldg x4, [x1] ubfx x4, x4, #MTE_TAG_SHIFT, #MTE_TAG_SIZE - user_ldst 2f, sttrb, w4, x0, 0 +USER(2f, sttrb w4, [x0]) add x0, x0, #1 add x1, x1, #MTE_GRANULE_SIZE subs x2, x2, #1 -- 2.28.0.dirty