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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A6ACC43334 for ; Sat, 18 Jun 2022 12:40:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 286B36B0071; Sat, 18 Jun 2022 08:40:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 236956B0072; Sat, 18 Jun 2022 08:40:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0D96F6B0073; Sat, 18 Jun 2022 08:40:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id EE7166B0071 for ; Sat, 18 Jun 2022 08:40:14 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id B7AB720751 for ; Sat, 18 Jun 2022 12:40:14 +0000 (UTC) X-FDA: 79591314348.30.246BD1E Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf29.hostedemail.com (Postfix) with ESMTP id 22017120008 for ; Sat, 18 Jun 2022 12:40:13 +0000 (UTC) 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 1EF68113E; Sat, 18 Jun 2022 05:40:13 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.35.139]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6859A3F792; Sat, 18 Jun 2022 05:40:08 -0700 (PDT) Date: Sat, 18 Jun 2022 13:40:01 +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> <4371a7c9-8766-9fee-2558-e6f43f06ad19@huawei.com> <0da734f3-5743-3df3-3f90-d92e5bd585ce@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <0da734f3-5743-3df3-3f90-d92e5bd585ce@huawei.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655556014; a=rsa-sha256; cv=none; b=cgJla/qE47DGblUbHVgPYr8VV1nZL/A7DMomHeZTMvablgtDi8n9wIRvOhtrphZSixRq+S stcyrqBXW5cJ1K2dk/IFyRpm/+FJ1U+5xakyfipgbRM2yxxOvNu4yqEgF10ZUDGOzvJMCK oxGkVXllzlnuJMB3ufkGaX9oICS8cPA= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf29.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655556014; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=LEvTA5Uj86Ib+RpZBYCLtqBDmUOEtAjezkJC0JWZZVA=; b=ap+6xW8uxAGG179DwH6pGMxPpk+iV3jsORknVy7BekQqxR5MnV5DyT+sDkaJ6DLC+CVDZq PkG9EXP5aclloYu+Kehlc540HSvkpiYLIhqUuMVobWyFBMHyY2vO61LDkKBaS0YvLnBCYM aGKIgTc6XpbmZPNgxUSy4RZg61b67Ck= X-Rspamd-Queue-Id: 22017120008 X-Rspam-User: Authentication-Results: imf29.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf29.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com X-Rspamd-Server: rspam06 X-Stat-Signature: qwz4ghbroun8eha86mp65ju7qx84hjpt X-HE-Tag: 1655556013-210738 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Jun 18, 2022 at 04:42:06PM +0800, Tong Tiangen wrote: > > > > 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. > > > > ok, will fix next version. > > > > Thanks, > > Tong. > > I tried to using data filelds as with C version, but here assembly code we > can not using operator such as << and |, if we use lsl and orr instructions, > the gpr will be occupied. > > So how about using 0x3ff directly here? it means err register and zero > register both set to x31. I had a go at implementing this, and it seems simple enough. Please see: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/extable/asm-uaccess Mark.