From patchwork Mon Jun 10 19:32:00 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 10985341 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 86D7914BB for ; Mon, 10 Jun 2019 19:33:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7724C27F17 for ; Mon, 10 Jun 2019 19:33:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6B713286CD; Mon, 10 Jun 2019 19:33:45 +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 1902E27F17 for ; Mon, 10 Jun 2019 19:33:45 +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 1haQ1n-0007ce-U4; Mon, 10 Jun 2019 19:32:23 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1haQ1n-0007cO-8a for xen-devel@lists.xenproject.org; Mon, 10 Jun 2019 19:32:23 +0000 X-Inumbo-ID: 780e1bbf-8bb6-11e9-8980-bc764e045a96 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTP id 780e1bbf-8bb6-11e9-8980-bc764e045a96; Mon, 10 Jun 2019 19:32:22 +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 5892BC0A; Mon, 10 Jun 2019 12:32:22 -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 708313F73C; Mon, 10 Jun 2019 12:32:21 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Mon, 10 Jun 2019 20:32:00 +0100 Message-Id: <20190610193215.23704-3-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 02/17] 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: 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" 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 --- xen/arch/arm/arm64/head.S | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index c8bbdf05a6..a5147c8d80 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 +/* + * 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) @@ -630,9 +635,8 @@ 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.