From patchwork Mon Aug 12 17:30:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 11090273 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CCDD014DB for ; Mon, 12 Aug 2019 17:31:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BEA99284D4 for ; Mon, 12 Aug 2019 17:31:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B242A2850D; Mon, 12 Aug 2019 17:31:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 2DF2E284E8 for ; Mon, 12 Aug 2019 17:31:45 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hxE9a-0006mm-1r; Mon, 12 Aug 2019 17:30:42 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hxE9Y-0006lR-VI for xen-devel@lists.xenproject.org; Mon, 12 Aug 2019 17:30:40 +0000 X-Inumbo-ID: e767d733-bd26-11e9-8980-bc764e045a96 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTP id e767d733-bd26-11e9-8980-bc764e045a96; Mon, 12 Aug 2019 17:30:40 +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 EF0B21715; Mon, 12 Aug 2019 10:30:39 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 491D63F706; Mon, 12 Aug 2019 10:30:39 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Mon, 12 Aug 2019 18:30:05 +0100 Message-Id: <20190812173019.11956-15-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190812173019.11956-1-julien.grall@arm.com> References: <20190812173019.11956-1-julien.grall@arm.com> Subject: [Xen-devel] [PATCH v3 14/28] xen/arm32: head: Rework and document check_cpu_mode() X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Julien Grall , Stefano Stabellini , Volodymyr Babchuk MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP A branch in the success case can be avoided by inverting the branch condition. At the same time, remove a pointless comment as Xen can only run at Hypervisor Mode. Lastly, document the behavior and the main registers usage within the function. Signed-off-by: Julien Grall --- Changes in v2: - Patch added --- xen/arch/arm/arm32/head.S | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S index 4285f76463..c7b4fe4cd4 100644 --- a/xen/arch/arm/arm32/head.S +++ b/xen/arch/arm/arm32/head.S @@ -206,6 +206,16 @@ secondary_switched: b launch ENDPROC(init_secondary) +/* + * Check if the CPU supports virtualization extensions and has been booted + * in Hypervisor mode. + * + * This function will never return when the CPU doesn't support + * virtualization extensions or is booted in another mode than + * Hypervisor mode. + * + * Clobbers r0 - r3 + */ check_cpu_mode: /* Check that this CPU has Hyp mode */ mrc CP32(r0, ID_PFR1) @@ -220,15 +230,12 @@ check_cpu_mode: mrs r0, cpsr and r0, r0, #0x1f /* Mode is in the low 5 bits of CPSR */ teq r0, #0x1a /* Hyp Mode? */ - beq hyp + moveq pc, lr /* Yes, return */ /* OK, we're boned. */ PRINT("- Xen must be entered in NS Hyp mode -\r\n") PRINT("- Please update the bootloader -\r\n") b fail - -hyp: PRINT("- Xen starting in Hyp mode -\r\n") - mov pc, lr ENDPROC(check_cpu_mode) zero_bss: