From patchwork Thu Nov 26 12:35:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 11933425 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=-16.8 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,URIBL_BLOCKED, 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 87C28C63697 for ; Thu, 26 Nov 2020 12:39:03 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 23A5120B80 for ; Thu, 26 Nov 2020 12:39:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="1BojQAmp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23A5120B80 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=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:MIME-Version:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:References:In-Reply-To:Message-Id:Date:Subject:To: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=R+5IxgPTYk3ZroNTHy5lxvlRYbysgHl4sIzCmhdzd44=; b=1BojQAmpYH1yutP1kyauLTpn4h Qfq7hEPNC85+XdUuXVaFq+P6Dzzukm/4eIxEK9bwmmr1BU7meXfZDbH2agKGHeQ5FMg48Hsx3Ok+P HLzBcdIisjsFoMgPUa3/4cMqq0730cgmxDYH23vR0JwGjVg7z+qOryJJSFK1qLOFvePD/NcaqB8OO iQeetQoV7MSQzh6VetiwK3PisCSogcTRHIdGlj3mn9d7AZkq+ljYYKY84vmr3mS3NE4q046z0AzbD TjR9SKpCA2lZvNUcrv4pMn+riuxfinBf0zq/jFCONFfEZGWsS8AuHm54TNhKnY88RNkR0RYZwVh54 xCPvyYGQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kiGWX-0000dZ-8Z; Thu, 26 Nov 2020 12:37:21 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kiGVZ-0000MC-5P for linux-arm-kernel@lists.infradead.org; Thu, 26 Nov 2020 12:36:24 +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 AE1D8153B; Thu, 26 Nov 2020 04:36:19 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 78C563F71F; Thu, 26 Nov 2020 04:36:18 -0800 (PST) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 05/11] arm64: entry: prepare ret_to_user for function call Date: Thu, 26 Nov 2020 12:35:56 +0000 Message-Id: <20201126123602.23454-6-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20201126123602.23454-1-mark.rutland@arm.com> References: <20201126123602.23454-1-mark.rutland@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201126_073621_402128_5A933819 X-CRM114-Status: GOOD ( 13.49 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, elver@google.com, paulmck@kernel.org, peterz@infradead.org, catalin.marinas@arm.com, james.morse@arm.com, will@kernel.org, dvyukov@google.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org In a subsequent patch ret_to_user will need to make a C function call (in some configurations) which may clobber x0-x18 at the start of the finish_ret_to_user block, before enable_step_tsk consumes the flags loaded into x1. In preparation for this, let's load the flags into x19, which is preserved across C function calls. This avoids a redundant reload of the flags and ensures we operate on a consistent shapshot regardless. There should be no functional change as a result of this patch. At this point of the entry/exit paths we only need to preserve x28 (tsk) and the sp, and x19 is free for this use. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: James Morse Cc: Will Deacon --- arch/arm64/kernel/entry.S | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index b295fb912b12..84aec600eeed 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -774,13 +774,13 @@ SYM_CODE_END(el0_error) SYM_CODE_START_LOCAL(ret_to_user) disable_daif gic_prio_kentry_setup tmp=x3 - ldr x1, [tsk, #TSK_TI_FLAGS] - and x2, x1, #_TIF_WORK_MASK + ldr x19, [tsk, #TSK_TI_FLAGS] + and x2, x19, #_TIF_WORK_MASK cbnz x2, work_pending finish_ret_to_user: /* Ignore asynchronous tag check faults in the uaccess routines */ clear_mte_async_tcf - enable_step_tsk x1, x2 + enable_step_tsk x19, x2 #ifdef CONFIG_GCC_PLUGIN_STACKLEAK bl stackleak_erase #endif @@ -791,11 +791,12 @@ finish_ret_to_user: */ work_pending: mov x0, sp // 'regs' + mov x1, x19 bl do_notify_resume #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_on // enabled while in userspace #endif - ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for single-step + ldr x19, [tsk, #TSK_TI_FLAGS] // re-check for single-step b finish_ret_to_user SYM_CODE_END(ret_to_user)