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[192.237.175.120]) by mx.google.com with ESMTPS id h23si58323038jam.120.2019.07.22.14.41.16 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 22 Jul 2019 14:41:16 -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 1hpg2j-0002nT-S6; Mon, 22 Jul 2019 21:40:25 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hpg2i-0002jm-5e for xen-devel@lists.xenproject.org; Mon, 22 Jul 2019 21:40:24 +0000 X-Inumbo-ID: 4f58cf37-acc9-11e9-8980-bc764e045a96 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTP id 4f58cf37-acc9-11e9-8980-bc764e045a96; Mon, 22 Jul 2019 21:40:23 +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 F3E3A152F; Mon, 22 Jul 2019 14:40:22 -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 4CC763F71F; Mon, 22 Jul 2019 14:40:22 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Mon, 22 Jul 2019 22:39:42 +0100 Message-Id: <20190722213958.5761-20-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 19/35] xen/arm32: head: Add a macro to move an immediate constant into a 32-bit register 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" The current boot code is using the pattern ldr rX, =... to move an immediate constant into a 32-bit register. This pattern implies to load the immediate constant from a literal pool, meaning a memory access will be performed. The memory access can be avoided by using movw/movt instructions. A new macro is introduced to move an immediate constant into a 32-bit register without a memory load. Follow-up patches will make use of it. Signed-off-by: Julien Grall Acked-by: Stefano Stabellini --- Changes in v2: - Patch added --- xen/arch/arm/arm32/head.S | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S index 18ded49a04..99f4af18d8 100644 --- a/xen/arch/arm/arm32/head.S +++ b/xen/arch/arm/arm32/head.S @@ -37,6 +37,15 @@ #endif /* + * Move an immediate constant into a 32-bit register using movw/movt + * instructions. + */ +.macro mov_w reg, word + movw \reg, #:lower16:\word + movt \reg, #:upper16:\word +.endm + +/* * Common register usage in this file: * r0 - * r1 -