From patchwork Mon Jul 22 21:39:26 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 11053487 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 AFAFA1398 for ; Mon, 22 Jul 2019 21:41:21 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A02F02847E for ; Mon, 22 Jul 2019 21:41:21 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 943A3284DB; Mon, 22 Jul 2019 21:41:21 +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 3D2262847E for ; Mon, 22 Jul 2019 21:41:21 +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 1hpg2U-0002Qg-NM; Mon, 22 Jul 2019 21:40:10 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hpg2T-0002Ps-7e for xen-devel@lists.xenproject.org; Mon, 22 Jul 2019 21:40:09 +0000 X-Inumbo-ID: 46acabbc-acc9-11e9-8980-bc764e045a96 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTP id 46acabbc-acc9-11e9-8980-bc764e045a96; Mon, 22 Jul 2019 21:40:08 +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 68F93153B; Mon, 22 Jul 2019 14:40:08 -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 B6F463F71F; Mon, 22 Jul 2019 14:40:07 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Mon, 22 Jul 2019 22:39:26 +0100 Message-Id: <20190722213958.5761-4-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190722213958.5761-1-julien.grall@arm.com> References: <20190722213958.5761-1-julien.grall@arm.com> Subject: [Xen-devel] [PATCH v2 03/35] xen/arm64: head: Don't clobber x30/lr in the macro PRINT 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 The current implementation of the macro PRINT will clobber x30/lr. This means the user should save lr if it cares about it. Follow-up patches will introduce more use of PRINT in place where lr should be preserved. Rather than requiring all the users to preserve lr, the macro PRINT is modified to save and restore it. While the comment state x3 will be clobbered, this is not the case. So PRINT will use x3 to preserve lr. Lastly, take the opportunity to move the comment on top of PRINT and use PRINT in init_uart. Both changes will be helpful in a follow-up patch. Signed-off-by: Julien Grall Reviewed-by: Stefano Stabellini --- Changes in v2: - Add Stefano's reviewed-by --- xen/arch/arm/arm64/head.S | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index f2d7445f6a..6afe83c347 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -78,12 +78,17 @@ * x30 - lr */ -/* Macro to print a string to the UART, if there is one. - * Clobbers x0-x3. */ #ifdef CONFIG_EARLY_PRINTK -#define PRINT(_s) \ - adr x0, 98f ; \ - bl puts ; \ +/* + * Macro to print a string to the UART, if there is one. + * + * Clobbers x0 - x3 + */ +#define PRINT(_s) \ + mov x3, lr ; \ + adr x0, 98f ; \ + bl puts ; \ + mov lr, x3 ; \ RODATA_STR(98, _s) #else /* CONFIG_EARLY_PRINTK */ #define PRINT(s) @@ -622,9 +627,8 @@ init_uart: #ifdef EARLY_PRINTK_INIT_UART early_uart_init x23, 0 #endif - adr x0, 1f - b puts -RODATA_STR(1, "- UART enabled -\r\n") + PRINT("- UART enabled -\r\n") + ret /* Print early debug messages. * x0: Nul-terminated string to print.