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 DBA44C43334 for ; Fri, 17 Jun 2022 08:24:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380912AbiFQIYy (ORCPT ); Fri, 17 Jun 2022 04:24:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380867AbiFQIYv (ORCPT ); Fri, 17 Jun 2022 04:24:51 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 118A064BE9 for ; Fri, 17 Jun 2022 01:24:51 -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 DA8681474; Fri, 17 Jun 2022 01:24:50 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.39.168]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6A6193F792; Fri, 17 Jun 2022 01:24:47 -0700 (PDT) Date: Fri, 17 Jun 2022 09:24:44 +0100 From: Mark Rutland To: Tong Tiangen Cc: James Morse , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Robin Murphy , Dave Hansen , Catalin Marinas , Will Deacon , Alexander Viro , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , x86@kernel.org, "H . Peter Anvin" , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kefeng Wang , Xie XiuQi , Guohanjun Subject: Re: [PATCH -next v5 2/8] arm64: extable: make uaaccess helper use extable type EX_TYPE_UACCESS_ERR_ZERO Message-ID: References: <20220528065056.1034168-1-tongtiangen@huawei.com> <20220528065056.1034168-3-tongtiangen@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220528065056.1034168-3-tongtiangen@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 28, 2022 at 06:50:50AM +0000, Tong Tiangen wrote: > Currnetly, the extable type used by __arch_copy_from/to_user() is > EX_TYPE_FIXUP. In fact, It is more clearly to use meaningful > EX_TYPE_UACCESS_*. > > Suggested-by: Mark Rutland > Signed-off-by: Tong Tiangen > --- > arch/arm64/include/asm/asm-extable.h | 8 ++++++++ > arch/arm64/include/asm/asm-uaccess.h | 12 ++++++------ > 2 files changed, 14 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/include/asm/asm-extable.h b/arch/arm64/include/asm/asm-extable.h > index 56ebe183e78b..9c94ac1f082c 100644 > --- a/arch/arm64/include/asm/asm-extable.h > +++ b/arch/arm64/include/asm/asm-extable.h > @@ -28,6 +28,14 @@ > __ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_FIXUP, 0) > .endm > > +/* > + * Create an exception table entry for uaccess `insn`, which will branch to `fixup` > + * when an unhandled fault is taken. > + * ex->data = ~0 means both reg_err and reg_zero is set to wzr(x31). > + */ > + .macro _asm_extable_uaccess, insn, fixup > + __ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_UACCESS_ERR_ZERO, ~0) > + .endm I'm not too keen on using `~0` here, since that also sets other bits in the data field, and its somewhat opaque. How painful is it to generate the data fields as with the C version of this macro, so that we can pass in wzr explciitly for the two sub-fields? Other than that, this looks good to me. Thanks, Mark. > /* > * Create an exception table entry for `insn` if `fixup` is provided. Otherwise > * do nothing. > diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h > index 0557af834e03..75b211c98dea 100644 > --- a/arch/arm64/include/asm/asm-uaccess.h > +++ b/arch/arm64/include/asm/asm-uaccess.h > @@ -61,7 +61,7 @@ alternative_else_nop_endif > > #define USER(l, x...) \ > 9999: x; \ > - _asm_extable 9999b, l > + _asm_extable_uaccess 9999b, l > > /* > * Generate the assembly for LDTR/STTR with exception table entries. > @@ -73,8 +73,8 @@ alternative_else_nop_endif > 8889: ldtr \reg2, [\addr, #8]; > add \addr, \addr, \post_inc; > > - _asm_extable 8888b,\l; > - _asm_extable 8889b,\l; > + _asm_extable_uaccess 8888b, \l; > + _asm_extable_uaccess 8889b, \l; > .endm > > .macro user_stp l, reg1, reg2, addr, post_inc > @@ -82,14 +82,14 @@ alternative_else_nop_endif > 8889: sttr \reg2, [\addr, #8]; > add \addr, \addr, \post_inc; > > - _asm_extable 8888b,\l; > - _asm_extable 8889b,\l; > + _asm_extable_uaccess 8888b,\l; > + _asm_extable_uaccess 8889b,\l; > .endm > > .macro user_ldst l, inst, reg, addr, post_inc > 8888: \inst \reg, [\addr]; > add \addr, \addr, \post_inc; > > - _asm_extable 8888b,\l; > + _asm_extable_uaccess 8888b, \l; > .endm > #endif > -- > 2.25.1 >