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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 7F443C433ED for ; Fri, 14 May 2021 11:59:02 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4953561458 for ; Fri, 14 May 2021 11:59:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4953561458 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:Cc:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=3voP4q+v9zDPdnoXCgbcyeUcw2SrdNZKuKbX0eLtJEI=; b=SSOzueiKS7g7bCqaBQ3vJT1zf ljvQgkFreUzee/q2MBCELPvoH1eaZM/AxCUAxeFbdBBCkfTh9q3c3kMxlY+MuDbBftmYdEIUpfEaT Wbtqff2NqcqEURRzBijdS7kyC3Ft/mSTRu6GDZZMoF2XymXbGfrYgQODl0wgHeCQ9g5d6AbFBkJbi vJ7W0LxQOBZOOAKZfdGPhalxcqzXc4O9pG8kmZMLxN7AdjnUmJPg8Tkts5ZX8wYIajRPUhrwI2Xrw eoGWkVS39gwjSZ4WiKW4SuS9hVNC5UM4cEGzHIEMYINmFbAXvn2vZlHpUF24gS+aSc6UOrPOTMPaR kEf92ybJA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lhWRZ-007yls-Uv; Fri, 14 May 2021 11:57:27 +0000 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lhWRX-007yll-KL for linux-arm-kernel@desiato.infradead.org; Fri, 14 May 2021 11:57:23 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=zoioge338LuBneDL7Gz5zj6R/iiVqqwfhePbBfarw4E=; b=CaBXNZm4Yg85RHVNcU2i2sJhuW EyC/zgehV/cV+a5z/BHG8FQPlSVBQJNu9LhpTLcUBU71qQOJxQqDAzKvkQpj7Dm/T4OEWx4HINjwR wM80iekXnLZFt4aopl8ohJ5xuESBVKd5uErw5eUDwM48nlTXgD1nzt5gZ2iVfjx9s1eWe6ebQaqbm 1JH+ExNFMESekxt06HdVO63cLCyO7/6yfG55EwCOd7iuCop+TrMPGvXDGsifyZzxhvuvGNxHduHp1 g5q6FBbYVZ5K8XOsM2G/8viiBdoy1znRyYn5rwvOJhDu8QLeWWrGlKwj3XBIcM1R47tvDl5VECI1f fOrx+NLA==; Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lhWRU-00BxC7-OI for linux-arm-kernel@lists.infradead.org; Fri, 14 May 2021 11:57:22 +0000 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 A9E7B1476; Fri, 14 May 2021 04:57:16 -0700 (PDT) Received: from e110467-lin.cambridge.arm.com (e110467-lin.cambridge.arm.com [10.1.196.41]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 03B8F3F73B; Fri, 14 May 2021 04:57:15 -0700 (PDT) From: Robin Murphy To: will@kernel.org, catalin.marinas@arm.com Cc: linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com Subject: [PATCH v2] arm64: Rewrite __arch_clear_user() Date: Fri, 14 May 2021 12:57:07 +0100 Message-Id: X-Mailer: git-send-email 2.21.0.dirty In-Reply-To: <76a1700b0316b50fb5881da603f2daf3c81468f4.1620738177.git.robin.murphy@arm.com> References: <76a1700b0316b50fb5881da603f2daf3c81468f4.1620738177.git.robin.murphy@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210514_045720_854452_B8B3293C X-CRM114-Status: UNSURE ( 9.82 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Now that we're always using STTR variants rather than abstracting two different addressing modes, the user_ldst macro here is frankly more obfuscating than helpful. Rewrite __arch_clear_user() with regular USER() annotations so that it's clearer what's going on, and take the opportunity to minimise the branchiness in the most common paths, while also allowing the exception fixup to return an accurate result. Signed-off-by: Robin Murphy --- v2: Tweak exception fixup to be exact arch/arm64/lib/clear_user.S | 44 ++++++++++++++++++++----------------- 1 file changed, 24 insertions(+), 20 deletions(-) diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S index af9afcbec92c..d30c03f6caed 100644 --- a/arch/arm64/lib/clear_user.S +++ b/arch/arm64/lib/clear_user.S @@ -1,12 +1,9 @@ /* SPDX-License-Identifier: GPL-2.0-only */ /* - * Based on arch/arm/lib/clear_user.S - * - * Copyright (C) 2012 ARM Ltd. + * Copyright (C) 2021 Arm Ltd. */ -#include -#include +#include #include .text @@ -19,25 +16,30 @@ * * Alignment fixed up by hardware. */ + .p2align 4 SYM_FUNC_START(__arch_clear_user) - mov x2, x1 // save the size for fixup return + add x2, x0, x1 subs x1, x1, #8 b.mi 2f 1: -user_ldst 9f, sttr, xzr, x0, 8 +USER(9f, sttr xzr, [x0]) + add x0, x0, #8 subs x1, x1, #8 - b.pl 1b -2: adds x1, x1, #4 - b.mi 3f -user_ldst 9f, sttr, wzr, x0, 4 - sub x1, x1, #4 -3: adds x1, x1, #2 - b.mi 4f -user_ldst 9f, sttrh, wzr, x0, 2 - sub x1, x1, #2 -4: adds x1, x1, #1 - b.mi 5f -user_ldst 9f, sttrb, wzr, x0, 0 + b.hi 1b +USER(9f, sttr xzr, [x2, #-8]) + mov x0, #0 + ret + +2: tbz x1, #2, 3f +USER(9f, sttr wzr, [x0]) +USER(8f, sttr wzr, [x2, #-4]) + mov x0, #0 + ret + +3: tbz x1, #1, 4f +USER(9f, sttrh wzr, [x0]) +4: tbz x1, #0, 5f +USER(7f, sttrb wzr, [x2, #-1]) 5: mov x0, #0 ret SYM_FUNC_END(__arch_clear_user) @@ -45,6 +47,8 @@ EXPORT_SYMBOL(__arch_clear_user) .section .fixup,"ax" .align 2 -9: mov x0, x2 // return the original size +7: sub x0, x2, #5 // Adjust for faulting on the final byte... +8: add x0, x0, #4 // ...or the second word of the 4-7 byte case +9: sub x0, x2, x0 ret .previous -- 2.21.0.dirty _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel