From patchwork Mon Jun 10 19:32:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 166371 Delivered-To: patch@linaro.org Received: by 2002:a92:4782:0:0:0:0:0 with SMTP id e2csp1410404ilk; Mon, 10 Jun 2019 12:33:57 -0700 (PDT) X-Google-Smtp-Source: APXvYqxVj4CzMQwqXbGitu/KbnDWwxr3+c2CCS7gtL4njJSOMddiRFAzWlU8py0QgRpzj6kbG/yi X-Received: by 2002:a6b:b204:: with SMTP id b4mr11855395iof.177.1560195237598; Mon, 10 Jun 2019 12:33:57 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1560195237; cv=none; d=google.com; s=arc-20160816; b=EzsVMhBH+go3hb/cGz453l8TziEmGahra+5WXvvnah54tvPrKrHA2tpzefoBVdTLIX 73Std28JemAtYoOL9bYeMJfPDcCB7jsQqkj1m1ZcHmFE+vlvUIiv2KCyxphNj126d1HO GATSw1WN6qpK7EDKnVi00CsgzCWgXxx1xybTiJoq5ScFVZgIHrF0B4W4Zoa2YNZSBpTv 0jn4LGNbcBYh0+MpxbSNKlig7vAsPY4HSiUStk5aJ8zyRsvwIsZgQS75G6Vghxs6IU8c Hiy2e00AwrofRjDZaNFUexx4NCpIm5dY6y+hx1bZV+djfUUKjzRRFgUxRlgfmmFdD03t mIkg== 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=/2efVw76EpIlAWOmz7Lpp+ufSJVO7tyorxPJ5n4UkVA=; b=CjAnOcmdM61mf8S+FAcNMBX2Io48WXewYkF/71BgGmqWtdJYDlIC+f/UXQVwGi86mC Ss0idoIGBJqKRrvb2ILMdKeT8i+H5ZQ4rL81lEPCcFp2szanVc71aRVVEPub3sMhmVnw AUoR9LGTz3qNHNL651PkvYTO8C5b/jT/xkZLlJld9HcvxKpycIVXNjgwcKm+DZyGgyb6 M5gWJb9XI9gobOb2z24Cmi75o5JMww7XXfHQyGlqWQImhXaAjOEDRQPntQldrWms1dIh GFH8reZdeV8W+lxrdna7N79svrsYBvkJtQ0ZXqD/UOHX0lg5toEhgya1AgVSP0ojp48C gxZA== 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 a101si7726467jai.2.2019.06.10.12.33.57 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 10 Jun 2019 12:33:57 -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 1haQ1u-0007fE-Vf; Mon, 10 Jun 2019 19:32:30 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1haQ1s-0007di-Ri for xen-devel@lists.xenproject.org; Mon, 10 Jun 2019 19:32:28 +0000 X-Inumbo-ID: 7b48ac70-8bb6-11e9-8980-bc764e045a96 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTP id 7b48ac70-8bb6-11e9-8980-bc764e045a96; Mon, 10 Jun 2019 19:32:28 +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 E5F4A344; Mon, 10 Jun 2019 12:32:27 -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 0922F3F73C; Mon, 10 Jun 2019 12:32:26 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Mon, 10 Jun 2019 20:32:05 +0100 Message-Id: <20190610193215.23704-8-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190610193215.23704-1-julien.grall@arm.com> References: <20190610193215.23704-1-julien.grall@arm.com> Subject: [Xen-devel] [PATCH 07/17] xen/arm64: 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: andre.przywara@arm.com, Julien Grall , Stefano Stabellini , andrii_anisov@epam.com, Oleksandr_Tyshchenko@epam.com 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 EL2. Lastly, document the behavior and the main registers usage within the function. Signed-off-by: Julien Grall Reviewed-by: Stefano Stabellini --- xen/arch/arm/arm64/head.S | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index ccd8a1b0a8..87fcd3be6c 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -350,6 +350,13 @@ secondary_switched: b launch ENDPROC(init_secondary) +/* + * Check if the CPU has been booted in Hypervisor mode. + * This function will never return when the CPU is booted in another mode + * than Hypervisor mode. + * + * Clobbers x0 - x5 + */ check_cpu_mode: PRINT("- Current EL ") mrs x5, CurrentEL @@ -359,15 +366,13 @@ check_cpu_mode: /* Are we in EL2 */ cmp x5, #PSR_MODE_EL2t ccmp x5, #PSR_MODE_EL2h, #0x4, ne - b.eq el2 /* Yes */ - + b.ne 1f /* No */ + ret +1: /* OK, we're boned. */ PRINT("- Xen must be entered in NS EL2 mode -\r\n") PRINT("- Please update the bootloader -\r\n") b fail - -el2: PRINT("- Xen starting at EL2 -\r\n") - ret ENDPROC(check_cpu_mode) zero_bss: