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: 171103 Delivered-To: patch@linaro.org Received: by 2002:a92:d204:0:0:0:0:0 with SMTP id y4csp3120216ily; Mon, 12 Aug 2019 10:31:46 -0700 (PDT) X-Google-Smtp-Source: APXvYqy5dls2eW/NE76m74sl8XHxBSgTYRSkXCmvWlX0jIQQCeRaxOiVgH/rXd+YVTrAbzAIxQsV X-Received: by 2002:a05:6638:105:: with SMTP id x5mr12643013jao.43.1565631106361; Mon, 12 Aug 2019 10:31:46 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1565631106; cv=none; d=google.com; s=arc-20160816; b=lmg0IvvYlZDn1c9JevNI2OpJNmhekuBguQItgN7sgG/PLBjvv1X8F5MmAZkdUdRg6L Ez9mx2FqXfTpzaevYtzYNtVkUvZjhUtD1J96UyX0YIGWpVVj4taJZR2RTOIwp1MR+s/S l3ftwNCDvjCEkLfrSPqhnkSvt6AfWzlpeWRRjyUmzpEX6KuxfjvENJHP/H097acWzEDu myPELZA4rPQtsB55xUDYrU5+pbg+iQUCOmQ2q9Zygu9cqj4p6fIWrJP5vcdalgg+rDhR bNsCLRFL3u2kh5vazXpQq9LTAB2rIhvgnI1KudvygsAHTVn2eabRwgFppyNlzHmYGnc5 NQbQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:errors-to:content-transfer-encoding:mime-version:cc :list-subscribe:list-help:list-post:list-unsubscribe:list-id :precedence:subject:references:in-reply-to:message-id:date:to:from; bh=8dHSU4/G6Zygf9l3myCMrCWC87mfAv/spWzDvyaYzwE=; b=LBthvAGd3yquoni1VEea8z2gtr2BBD2+25uQgWtFSqSLKX2Tfstz3ZD/99ArZm5tPh ch0M66k4LRHXP3oiCGMkuPbPPBRhRQJn8IyV5mc6m87HrWhJg80IicL7rh2UMzKgCFnd oMcz3v9vrsTWo9pw859EdOh300ijd4pkGmp8ducF19f4HQ3/jIZd3QNcbI7IIJ6N2XsO wIdec6hTIiuXymnq2zEu8dPQJegLGS1+dyI4counVW4a2EmvWXWCbaaVnjPmnKPbTVNH 7MfEfT+iSKmH+LNwdTKMYULEun2fBIXZ9tJiPcws9HabIACB0XfM3gcW//BHtebeY/Dw PvjQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of xen-devel-bounces@lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Return-Path: Received: from lists.xenproject.org (lists.xenproject.org. [192.237.175.120]) by mx.google.com with ESMTPS id u73si90316jab.120.2019.08.12.10.31.46 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 12 Aug 2019 10:31:46 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of xen-devel-bounces@lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of xen-devel-bounces@lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org 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" 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: